Andrei Volgin - Academia.edu (original) (raw)
Papers by Andrei Volgin
Cancer Research, 2008
Aberrant expression and/or activity of members of the Src family of nonreceptor protein tyrosine ... more Aberrant expression and/or activity of members of the Src family of nonreceptor protein tyrosine kinases (SFK) are commonly observed in progressive stages of human tumors. In prostate cancer, two SFKs (Src and Lyn) have been specifically implicated in tumor growth and progression. However, there are no data in preclinical models demonstrating potential efficacy of Src inhibitors against prostate cancer growth and/or metastasis. In this study, we used the small molecule SFK/Abl kinase inhibitor dasatinib, currently in clinical trials for solid tumors, to examine in vitro and in vivo effects of inhibiting SFKs in prostate tumor cells. In vitro, dasatinib inhibits both Src and Lyn activity, resulting in decreased cellular proliferation, migration, and invasion. In orthotopic nude mouse models, dasatinib treatment effectively inhibits expression of activated SFKs, resulting in inhibition of both tumor growth and development of lymph node metastases in both androgen-sensitive and androgen-resistant tumors. In primary tumors, SFK inhibition leads to decreased cellular proliferation (determined by immunohistochemistry for proliferating cell nuclear antigen). In vitro, small interfering RNA (siRNA)-mediated inhibition of Lyn affects cellular proliferation; siRNA inhibition of Src affects primarily cellular migration. Therefore, we conclude that SFKs are promising therapeutic targets for treatment of human prostate cancer and that Src and Lyn activities affect different cellular functions required for prostate tumor growth and progression.
Clinical cancer research : an official journal of the American Association for Cancer Research, Jan 24, 2015
to characterize the prevalence of hypoxia in the leukemic bone marrow (BM), its association with ... more to characterize the prevalence of hypoxia in the leukemic bone marrow (BM), its association with metabolic and transcriptional changes in the leukemic blasts and the utility of hypoxia activated prodrug TH-302 in leukemia models. hyperpolarized magnetic resonance spectroscopy was utilized to interrogate the pyruvate metabolism of the bone marrow in the murine AML model. Nanostring technology was used to evaluate a gene set defining a hypoxia signature in leukemic blasts and normal donors. The efficacy of the hypoxia-activated pro-drug TH-302 was examined in the in vitro and in vivo leukemia models. Metabolic imaging has demonstrated increased glycolysis in the femur of leukemic mice compared to healthy control mice, suggesting metabolic re-programming of hypoxic BM niches. Primary leukemic blasts in samples from AML patients overexpressed genes defining a "hypoxia index" compared to samples from normal donors. TH-302 depleted hypoxic cells, prolonged survival of xenograft ...
Molecular imaging
Tumor spheroids more faithfully mimic tumor biology than monolayer cultures and require three-dim... more Tumor spheroids more faithfully mimic tumor biology than monolayer cultures and require three-dimensional microscopy. Our goal in this study was to overcome the limitations of signal to noise ratio that have traditionally limited three-dimensional imaging to depths of 100 microm or less. We studied the expression of hypoxia-inducible factor 1alpha (HIF-1alpha), the main regulator of cellular hypoxic response in C6 glioma spheroids. In our spheroids, red fluorescent protein is expressed constitutively and green fluorescent protein is expressed conditionally under control of a HIF-1alpha promoter. In this article, we show a series of optimizations that allowed us to obtain excellent quality confocal microscopy images at imaging depths of up to 320 microm. The combined use of special objectives, glass-bottomed culture dishes, and depth-dependent laser output modulation extended our depth range beyond previously accepted limits. This allowed us to image up to the equator of spheroids of...
Molecular Immunology, 1998
Eur J Nucl Med Mol Imaging, 2008
![Research paper thumbnail of Evaluation of 2'-deoxy-2'-[18F]fluoro-5-methyl-1-beta-L: -arabinofuranosyluracil ([18F]-L: -FMAU) as a PET imaging agent for cellular proliferation: comparison with [18F]-D: -FMAU and [18F]FLT](https://attachments.academia-assets.com/43633947/thumbnails/1.jpg)
](European journal of nuclear medicine and molecular imaging, 2008
Clevudine (L: -FMAU) an un-natural analogue of thymidine, is in clinical trials for the treatment... more Clevudine (L: -FMAU) an un-natural analogue of thymidine, is in clinical trials for the treatment of hepatitis B virus (HBV). L: -FMAU is phosphorylated by cellular kinases such as thymidine kinase 1 and deoxycytidine kinase, and its triphosphate form inhibits HBV deoxyribonucleic acid synthesis. Thus, L: -FMAU, radiolabeled with an appropriate isotope, may be useful for positron emission tomography (PET) imaging of tumor proliferation. We evaluated [18F]-L-FMAU as a PET imaging agent in tumor-bearing mice and compared the results with those of two other radiotracers, [18F]-d-FMAU and [18F]-FLT. Subcutaneous xenografts of the human lung cancer cell lines H441 and H3255 were established in mice. A micro-PET scanner was used to obtain images of the tumor-bearing animals with [18F]-L-FMAU, [18F]-D-FMAU, and [18F]-FLT. At 2 h postinjection, the tumor uptake (% ID/g) of 18F]-L: -FMAU, 18F]-D: -FMAU, and [18F]-FLT in the faster-growing H441 cells was 3.13 +/- 1.11, 7.74 +/- 1.39, and 5.10...
Proceedings of the National Academy of Sciences, 2011
![Research paper thumbnail of Detection of Pancreatic Carcinomas by Imaging Lactose-Binding Protein Expression in Peritumoral Pancreas Using [18F]Fluoroethyl-Deoxylactose PET/CT](https://attachments.academia-assets.com/43633950/thumbnails/1.jpg)
](PLoS ONE, 2009
Background: Early diagnosis of pancreatic carcinoma with highly sensitive diagnostic imaging meth... more Background: Early diagnosis of pancreatic carcinoma with highly sensitive diagnostic imaging methods could save lives of many thousands of patients, because early detection increases resectability and survival rates. Current non-invasive diagnostic imaging techniques have inadequate resolution and sensitivity for detection of small size (,2-3 mm) early pancreatic carcinoma lesions. Therefore, we have assessed the efficacy of positron emission tomography and computer tomography (PET/CT) imaging with b-O-D-galactopyranosyl-(1,49)-29-deoxy-29-[ 18 F]fluoroethyl-D-glucopyranose ([ 18 F]FEDL) for detection of less than 3 mm orthotopic xenografts of L3.6pl pancreatic carcinomas in mice. [ 18 F]FEDL is a novel radioligand of hepatocarcinoma-intestine-pancreas/pancreatitis-associated protein (HIP/PAP), which is overexpressed in peritumoral pancreatic acinar cells.
![Research paper thumbnail of N3-Substituted thymidine analogues V: Synthesis and preliminary PET imaging of N3-[18F]fluoroethyl thymidine and N3-[18F]fluoropropyl thymidine](https://attachments.academia-assets.com/43633945/thumbnails/1.jpg)
](Nuclear Medicine and Biology, 2008
Introduction: [ 18 F]-Labeled analogues of thymidine have demonstrated efficacy for PET imaging o... more Introduction: [ 18 F]-Labeled analogues of thymidine have demonstrated efficacy for PET imaging of cellular proliferation. We have synthesized two [ 18 F]-labeled N 3 -substituted thymidine analogues, N 3 -[ 18 F]fluoroethyl thymidine (N 3 -[ 18 F]-FET) and N 3 -[ 18 F]fluoropropyl thymidine (N 3 -[ 18 F]-FPrT), and performed preliminary PET imaging studies in tumor-bearing mice. Methods: Thymidine was converted to its 3′,5′-O-bis-tetrahydropyranyl ether, which was then converted to the N 3 -ethyl and propylsubstituted mesylate precursors. Reactions of these mesylate precursors with n-Bu 4 N[ 18 F] or K[ 18 F]/kryptofix followed by acid hydrolysis and HPLC purification yielded N 3 -[ 18 F]-FET and N 3 -[ 18 F]-FPrT, respectively. Subcutaneous (sc) xenografts of H441 human non-small cell lung cancer were established in two groups of mice (each n=6). Micro-PET images of the tumor-bearing animals were acquired after intravenous injection of N 3 -[ 18 F]-FET or N 3 -[ 18 F]-FPrT (3700 KBq/animal). Results: The radiochemical yields were 2-12% (d.c.) for N 3 -[ 18 F]-FET and 30-38% (d.c.) for N 3 -[ 18 F]-FPrT. Radiochemical purity was N99% and calculated specific activity was N74 GBq/μmol at the end of synthesis. The accumulation of N 3 -[ 18 F]-FET and N 3 -[ 18 F]-FPrT in the tumor tissue at 2 h postinjection was 1.81±0.78 and 2.95±1
Nuclear Medicine and Biology, 2000
Interest remains strong for the development of a noninvasive technique for assessment of regional... more Interest remains strong for the development of a noninvasive technique for assessment of regional fatty acid oxidation rate in the myocardium. 18 F-labeled 4-thia palmitate (FTP, 16-[ 18 F]fluoro-4thia-hexadecanoic acid) has been synthesized and preliminarily evaluated as a metabolically trapped probe of myocardial fatty acid oxidation for positron emission tomography (PET). The radiotracer is synthesized by Kryptofix 2.2.2/K 2 CO 3 assisted nucleophilic radiofluorination of an iodo-ester precursor, followed by alkaline hydrolysis and by purification by reverse phase high performance liquid chromatography. Biodistribution studies in rats showed high uptake and long retention of FTP in heart, liver, and kidneys consistent with relatively high fatty acid oxidation rates in these tissues. Inhibition of carnitine palmitoyl-transferase-I caused an 80% reduction in myocardial uptake, suggesting the dependence of trapping on the transport of tracer into the mitochondrion. Experiments with perfused rat hearts showed that the estimates of the fractional metabolic trapping rate (FR) of FTP tracked inhibition of oxidation rate of palmitate with hypoxia, whereas the FR of the 6-thia analog 17-[ 18 F]fluoro-6-thia-heptadecanoic acid was insensitive to hypoxia. In vivo defluorination of FTP in the rat was evidenced by bone uptake of radioactivity. A PET imaging study with FTP in normal swine showed excellent myocardial images, prolonged myocardial retention, and no bone uptake of radioactivity up to 3 h, the last finding suggesting a species dependence for defluorination of the omega-labeled fatty acid. The results support further investigation of FTP as a potential PET tracer for assessing regional fatty acid oxidation rate in the human myocardium. NUCL MED BIOL 27;3:221-231, 2000.
![Research paper thumbnail of Synthesis and Ex Vivo Autoradiographic Evaluation of Ethyl-β-d-galactopyranosyl-(1,4′)-2′-deoxy-2′-[18F]fluoro-β-d-glucopyranoside—A Novel Radioligand for Lactose-Binding Protein: Implications for Early Detection of Pancreatic Carcinomas with PET](https://attachments.academia-assets.com/43633942/thumbnails/1.jpg)
](Molecular Imaging and Biology, 2011
Introduction: Previous studies demonstrated that the lactose-binding protein (hepatocellular carc... more Introduction: Previous studies demonstrated that the lactose-binding protein (hepatocellular carcinoma-intestine-pancreas and pancreatitis-associated proteins (HIP/PAP)) is upregulated 9130 times in peritumoral pancreatic tissue as compared to normal pancreatic tissue. Therefore, we developed a new radiolabeled ligand of HIP/PAP, the ethyl-β-D-galactopyranosyl-(1,4′)-2′deoxy-2′-[ 18 F]fluoro-β-D-glucopyranoside (Et-[ 18 F]FDL) for noninvasive imaging of pancreatic carcinoma using positron emission tomography and computerized tomography (PET/CT). Methods: The novel precursor and radiolabeling methods for synthesis of Et-[ 18 F]FDL produced no isomers; the average decay-corrected radiochemical yield was 68%, radiochemical purity 999%, and specific activity 974 GBq/µmol. The radioligand properties of Et-[ 18 F]FDL were evaluated using an ex vivo autoradiography and immunohistochemistry in pancreatic tissue sections obtained from mice-bearing orthotopic pancreatic tumor xenografts. Results and Discussion: Et-[ 18 F]FDL binding to peritumoral pancreatic tissue sections strongly correlated with HIP/PAP expression (r=0.81) and could be completely blocked by treatment with 1 mM lactose. Conclusion: These results suggest that Et-[ 18 F]FDL is a promising agent which should be evaluated for detection of early pancreatic carcinomas by PET/CT imaging.
Molecular Cancer Therapeutics, 2009
The standard treatment for most advanced cancers is multidrug therapy. Unfortunately, combination... more The standard treatment for most advanced cancers is multidrug therapy. Unfortunately, combinations in the clinic often do not perform as predicted. Therefore, to complement identifying rational drug combinations based on biological assumptions, we hypothesized that a functional screen of drug combinations, without limits on combination sizes, will aid the identification of effective drug cocktails. Given the myriad possible cocktails and inspired by examples of search algorithms in diverse fields outside of medicine, we developed a novel, efficient search strategy called Medicinal Algorithmic Combinatorial Screen (MACS). Such algorithms work by enriching for the fitness of cocktails, as defined by specific attributes through successive generations. Because assessment of synergy was not feasible, we developed a novel alternative fitness function based on the level of inhibition and the number of drugs. Using a WST-1 assay on the A549 cell line, through MACS, we screened 72 combinations of arbitrary size formed from a 19-drug pool across four generations. Fenretinide, suberoylanilide hydroxamic acid, and bortezomib (FSB) was the fittest. FSB performed up to 4.18 SD above the mean of a random set of cocktails or ''too well'' to have been found by chance, supporting the utility of the MACS strategy. Validation studies showed FSB was inhibitory in all 7 other NSCLC cell lines tested. It was also synergistic in A549, the one cell line in which this was evaluated. These results suggest that when guided by MACS, screening larger drug combinations may be feasible as a first step in combination drug discovery in a relatively small number of experiments. [Mol Cancer Ther
Molecular Cancer Therapeutics, 2009
Hypoxia inducible factor-1 (HIF-1) promotes tumor cell adaptation to microenvironmental stress. H... more Hypoxia inducible factor-1 (HIF-1) promotes tumor cell adaptation to microenvironmental stress. HIF-1 is up-regulated in irradiated tumors and serves as a promising target for radiosensitization. We initially confirmed that the orally bioavailable HIF-1 inhibitor PX-478 reduces HIF-1 protein levels and signaling in vitro in a dose-dependent manner and provides direct radiosensitization of hypoxic cancer cells in clonogenic survival assays using C6 glioma, HN5 and UMSCCa10 squamous cells, and Panc-1 pancreatic adenocarcinoma cell lines. However, PX-478 yields striking in vivo tumor sensitization to single-dose irradiation, which cannot be explained by incremental improvement in direct tumor cell killing. We show that PX-478 prevents postradiation HIF-1 signaling and abrogates downstream stromal adaptation in C6 and HN5 reporter xenografts as measured by serial ultrasound, vascular magnetic resonance imaging, and hypoxia response element-specific micro-positron emission tomography imaging. The primacy of indirect PX-478 in vivo effects was corroborated by our findings that (a) either concurrent or early postradiation sequencing of PX-478 provides roughly equivalent sensitization and (b) constitutive vascular endothelial growth factor expression maintains refractory tumor vessel function and progression following combined radiation and PX-478. These results confirm that disruption of postradiation adaptive HIF-1 signaling by PX-478 imparts increased therapeutic efficacy through blockade of HIF-1-dependent reconstitution of tumor stromal function. Successful translation of targeted HIF-1 radiosensitization to the clinical setting will require specific consideration of tumor microenvironmental effects and mechanisms.
Molecular Cancer Research, 2011
Hypoxia-inducible factor 1 (HIF-1) promotes cancer cell survival and tumor progression. The speci... more Hypoxia-inducible factor 1 (HIF-1) promotes cancer cell survival and tumor progression. The specific role played by HIF-1 and tumor-stromal interactions toward determining tumor resistance to radiation treatment remains undefined. We applied a multimodality preclinical imaging platform to mechanistically characterize tumor response to radiation, with a focus on HIF-1-dependent resistance pathways. C6 glioma and HN5 human squamous carcinoma cells were stably transfected with a dual HIF-1 signaling reporter construct (dxHRE-tk/eGFP-cmvRed2XPRT). Reporter cells were serially interrogated in vitro before and after irradiation as monolayer and multicellular spheroid cultures and as subcutaneous xenografts in nu/nu mice. In vitro, single-dose irradiation of C6 and HN5 reporter cells modestly impacted HIF-1 signaling in normoxic monolayers and inhibited HIF-1 signaling in maturing spheroids. In contrast, irradiation of C6 or HN5 reporter xenografts with 8 Gy in vivo elicited marked upregulation of HIF-1 signaling and downstream proangiogenic signaling at 48 hours which preceded recovery of tumor growth. In situ ultrasound imaging and dynamic contrast-enhanced (DCE) MRI indicated that HIF-1 signaling followed acute disruption of stromal vascular function. High-resolution positron emission tomography and dual-contrast DCE-MRI of immobilized dorsal skin window tumors confirmed postradiotherapy HIF-1 signaling to spatiotemporally coincide with impaired stromal vascular function. Targeted disruption of HIF-1 signaling established this pathway to be a determinant of tumor radioresistance. Our results illustrate that tumor radioresistance is mediated by a capacity to compensate for stromal vascular disruption through HIF-1-dependent proangiogenic signaling and that clinically relevant vascular imaging techniques can spatially define mechanisms associated with tumor irradiation.
Lung Cancer, 2005
Posters/Basic science/Ceil S153 e~press~on was the single factor that correlated with advanced di... more Posters/Basic science/Ceil S153 e~press~on was the single factor that correlated with advanced dinical stage (P 0 007) There was no significant difference between E-cadhedn and n,-catehin e0¢pression in squamous call carcinoma compared with adenocarclnoma The decline of both E4.~adberin and n,-catenin expression indicated a poor prognosis (P<00001 and P 00016. resbectively) in univariated analysis Multivariate analysis showed a significantly lower survival probability for patients with reduced E-Cadhedn (P <0 0001). and E-Cadhedn was an independent prognostic factor for survival of NSCLC patients Primarily. our results demensb'ated that E Cadhorln had potential to classify TNM staging system into more detalod subgroq~s. Patients with reduced expression of E Cadhenn. even though in the same stage and histological type. had shorter su~val time compared with patients with preserved E~adhonn expression. Conclusions: This study suggests that dysfunction of E Cadhonn has an important impact in the prograssion of lung cancer. As an independent prog nostio and sub grouping factor, e~prossion of ECadhenn can as=st clinicians to precict outcome of different stages in NSCLS. together with conventional prognostic factors, and subsequently make appropriate management
Journal of Nuclear Medicine, 2009
Imaging 2 different molecular-genetic events in a single subject by PET is essential in a variety... more Imaging 2 different molecular-genetic events in a single subject by PET is essential in a variety of in vivo applications. Using herpes simplex virus-1 thymidine kinase (HSV1-tk) mutants with narrower substrate specificities in combination with wild-type HSV1-tk (wtHSV1-tk) would enable differential imaging with corresponding radiotracers, namely 29-deoxy-29-18 F-fluoro-5ethyl-1-b-D-arabinofuranosyl-uracil ( 18 F-FEAU) and the acycloguanosine derivative 9-(4-18 F-fluoro-3-[hydroxymethyl]butyl)guanine ( 18 F-FHBG). In this study, we evaluated wtHSV1-tk and the A168H mutant, which has been reported to exhibit enhanced acycloguanosine substrate catalytic activity and diminished pyrimidine phosphorylating activity, as PET reporter genes. Methods: Computational analysis was performed to assess the binding mode of FHBG and FEAU to wtHSV1-tk and the A168H variant. U87 cells were stably transduced with wtHSV1-tk or HSV1-tk(A168H) fused with green fluorescent protein and sorted to obtain equivalent transgene expression. In vitro uptake studies were performed to determine rates of substrate accumulation and retention. Nude mice bearing tumors expressing HSV1-tk variants were subsequently imaged using 18 F-FHBG and 18 F-FEAU. Results: Docking results indicate that binding of FHBG to the A168H variant is unaffected whereas the binding of FEAU is hindered because of a steric clash with the bulkier mutant residues. U87 cells expressing HSV1-tk(A168H) accumulated 18 F-FHBG in in vitro uptake studies at a 3-fold higher rate than did cells expressing wtHSV1-tk without any detectable accumulation of 3 H-FEAU. Furthermore, HSV1-tk(A168H) demonstrated no thymidine phosphorylation activity. In contrast, U87 cells expressing wtHSV1-tk preferentially accumulated 3 H-FEAU at an 18-fold higher rate than they did 18 F-FHBG. Tumors expressing wtHSV1-tk or HSV1-tk(A168H) were distinctly imaged with 18 F-FEAU or 18 F-FHBG, respectively. Hence, tumors expressing HSV1-tk(A168H) accumulated 8.4-fold more 18 F-FHBG than did tumors expressing wtHSV1-tk. In addition, wtHSV1-tk tumors, compared with HSV1-tk(A168H)-expressing tumors (which retained baseline levels of the radiotracer), preferentially accumulated 18 F-FEAU. Conclusion: The FEAU and FHBG substrate discrimination capacity of the wtHSV1-tk and HSV1-tk(A168H) reporter enzymes was validated in vivo by PET of mice with tumor xenografts established from U87 cells expressing these different reporters. Thus, HSV1-tk(A168H) may potentially be used as a second reporter gene in combination with wtHSV1-tk to achieve differential PET.
Journal of Biomedical Optics, 2006
Thermal therapy efficacy can be diminished due to heat shock protein (HSP) induction in regions o... more Thermal therapy efficacy can be diminished due to heat shock protein (HSP) induction in regions of a tumor where temperatures are insufficient to coagulate proteins. HSP expression enhances tumor cell viability and imparts resistance to chemotherapy and radiation treatments, which are generally employed in conjunction with hyperthermia. Therefore, an understanding of the thermally induced HSP expression within the targeted tumor must be incorporated into the treatment plan to optimize the thermal dose delivery and permit prediction of the overall tissue response. A treatment planning computational model capable of predicting the temperature, HSP27 and HSP70 expression, and damage fraction distributions associated with laser heating in healthy prostate tissue and tumors is presented. Measured thermally induced HSP27 and HSP70 expression kinetics and injury data for normal and cancerous prostate cells and prostate tumors are employed to create the first HSP expression predictive model and formulate an Arrhenius damage model. The correlation coefficients between measured and model predicted temperature, HSP27, and HSP70 were 0.98, 0.99, and 0.99, respectively, confirming the accuracy of the model. Utilization of the treatment planning model in the design of prostate cancer thermal therapies can enable optimization of the treatment outcome by controlling HSP expression and injury.
PloS one, 2011
The long-term fate of stem cells after intramyocardial delivery is unknown. We used noninvasive, ... more The long-term fate of stem cells after intramyocardial delivery is unknown. We used noninvasive, repetitive PET/CT imaging with [(18)F]FEAU to monitor the long-term (up to 5 months) spatial-temporal dynamics of MSCs retrovirally transduced with the sr39HSV1-tk gene (sr39HSV1-tk-MSC) and implanted intramyocardially in pigs with induced acute myocardial infarction. Repetitive [(18)F]FEAU PET/CT revealed a biphasic pattern of sr39HSV1-tk-MSC dynamics; cell proliferation peaked at 33-35 days after injection, in periinfarct regions and the major cardiac lymphatic vessels and lymph nodes. The sr39HSV1-tk-MSC-associated [(18)F]FEAU signals gradually decreased thereafter. Cardiac lymphography studies using PG-Gd-NIRF813 contrast for MRI and near-infrared fluorescence imaging showed rapid clearance of the contrast from the site of intramyocardial injection through the subepicardial lymphatic network into the lymphatic vessels and periaortic lymph nodes. Immunohistochemical analysis of cardia...
![Research paper thumbnail of Evaluation of 2′-deoxy-2′-[18F]fluoro-5-methyl-1-β-l-arabinofuranosyluracil ([18F]-l-FMAU) as a PET imaging agent for cellular proliferation: comparison with [18F]-d-FMAU and [18F]FLT](https://attachments.academia-assets.com/43633943/thumbnails/1.jpg)
](European Journal of Nuclear Medicine and Molecular Imaging, 2008
Bioorganic & Medicinal Chemistry, 2011
Cannabinoid receptor 2 (CB2) plays an important role in human physiology and the pathophysiology ... more Cannabinoid receptor 2 (CB2) plays an important role in human physiology and the pathophysiology of different diseases, including neuroinflammation, neurodegeneration, and cancer. Several classes of CB2 receptor ligands, including 2-oxoquinoline derivatives, have been previously reported. We report the synthesis and results of in vitro receptor binding of a focused library of new fluorinated 2-oxoquinoline CB2 ligands. Twelve compounds, 13-16 18, 19, 21-24, 27, and 28 were synthesized in good yields in multiple steps. Human U87 glioma cells expressing either hCB1 (control) or hCB2 were generated via lentiviral transduction. In vitro competitive binding assay was performed using [ 3 H]CP-55,940 in U87hCB1 and U87hCB2 cells. Inhibition constant , 27, and 28 for CB2 were >10000, 2.8, 5.0, 2.4, 22, 0.8, 1.4, >10000, 486, 58, 620, and 2400 nM, respectively, and those for CB1 were >10000 nM. Preliminary in vitro results suggest that six of these compounds may be useful for therapy of neuropathic pain, neuroinflammatory diseases and immune disorders. In addition, compound 19, with its subnanomolar Ki value, could be radiolabeled with 18 F and explored for PET imaging of CB2 expression.
Cancer Research, 2008
Aberrant expression and/or activity of members of the Src family of nonreceptor protein tyrosine ... more Aberrant expression and/or activity of members of the Src family of nonreceptor protein tyrosine kinases (SFK) are commonly observed in progressive stages of human tumors. In prostate cancer, two SFKs (Src and Lyn) have been specifically implicated in tumor growth and progression. However, there are no data in preclinical models demonstrating potential efficacy of Src inhibitors against prostate cancer growth and/or metastasis. In this study, we used the small molecule SFK/Abl kinase inhibitor dasatinib, currently in clinical trials for solid tumors, to examine in vitro and in vivo effects of inhibiting SFKs in prostate tumor cells. In vitro, dasatinib inhibits both Src and Lyn activity, resulting in decreased cellular proliferation, migration, and invasion. In orthotopic nude mouse models, dasatinib treatment effectively inhibits expression of activated SFKs, resulting in inhibition of both tumor growth and development of lymph node metastases in both androgen-sensitive and androgen-resistant tumors. In primary tumors, SFK inhibition leads to decreased cellular proliferation (determined by immunohistochemistry for proliferating cell nuclear antigen). In vitro, small interfering RNA (siRNA)-mediated inhibition of Lyn affects cellular proliferation; siRNA inhibition of Src affects primarily cellular migration. Therefore, we conclude that SFKs are promising therapeutic targets for treatment of human prostate cancer and that Src and Lyn activities affect different cellular functions required for prostate tumor growth and progression.
Clinical cancer research : an official journal of the American Association for Cancer Research, Jan 24, 2015
to characterize the prevalence of hypoxia in the leukemic bone marrow (BM), its association with ... more to characterize the prevalence of hypoxia in the leukemic bone marrow (BM), its association with metabolic and transcriptional changes in the leukemic blasts and the utility of hypoxia activated prodrug TH-302 in leukemia models. hyperpolarized magnetic resonance spectroscopy was utilized to interrogate the pyruvate metabolism of the bone marrow in the murine AML model. Nanostring technology was used to evaluate a gene set defining a hypoxia signature in leukemic blasts and normal donors. The efficacy of the hypoxia-activated pro-drug TH-302 was examined in the in vitro and in vivo leukemia models. Metabolic imaging has demonstrated increased glycolysis in the femur of leukemic mice compared to healthy control mice, suggesting metabolic re-programming of hypoxic BM niches. Primary leukemic blasts in samples from AML patients overexpressed genes defining a "hypoxia index" compared to samples from normal donors. TH-302 depleted hypoxic cells, prolonged survival of xenograft ...
Molecular imaging
Tumor spheroids more faithfully mimic tumor biology than monolayer cultures and require three-dim... more Tumor spheroids more faithfully mimic tumor biology than monolayer cultures and require three-dimensional microscopy. Our goal in this study was to overcome the limitations of signal to noise ratio that have traditionally limited three-dimensional imaging to depths of 100 microm or less. We studied the expression of hypoxia-inducible factor 1alpha (HIF-1alpha), the main regulator of cellular hypoxic response in C6 glioma spheroids. In our spheroids, red fluorescent protein is expressed constitutively and green fluorescent protein is expressed conditionally under control of a HIF-1alpha promoter. In this article, we show a series of optimizations that allowed us to obtain excellent quality confocal microscopy images at imaging depths of up to 320 microm. The combined use of special objectives, glass-bottomed culture dishes, and depth-dependent laser output modulation extended our depth range beyond previously accepted limits. This allowed us to image up to the equator of spheroids of...
Molecular Immunology, 1998
Eur J Nucl Med Mol Imaging, 2008
European journal of nuclear medicine and molecular imaging, 2008
Clevudine (L: -FMAU) an un-natural analogue of thymidine, is in clinical trials for the treatment... more Clevudine (L: -FMAU) an un-natural analogue of thymidine, is in clinical trials for the treatment of hepatitis B virus (HBV). L: -FMAU is phosphorylated by cellular kinases such as thymidine kinase 1 and deoxycytidine kinase, and its triphosphate form inhibits HBV deoxyribonucleic acid synthesis. Thus, L: -FMAU, radiolabeled with an appropriate isotope, may be useful for positron emission tomography (PET) imaging of tumor proliferation. We evaluated [18F]-L-FMAU as a PET imaging agent in tumor-bearing mice and compared the results with those of two other radiotracers, [18F]-d-FMAU and [18F]-FLT. Subcutaneous xenografts of the human lung cancer cell lines H441 and H3255 were established in mice. A micro-PET scanner was used to obtain images of the tumor-bearing animals with [18F]-L-FMAU, [18F]-D-FMAU, and [18F]-FLT. At 2 h postinjection, the tumor uptake (% ID/g) of 18F]-L: -FMAU, 18F]-D: -FMAU, and [18F]-FLT in the faster-growing H441 cells was 3.13 +/- 1.11, 7.74 +/- 1.39, and 5.10...
Proceedings of the National Academy of Sciences, 2011
PLoS ONE, 2009
Background: Early diagnosis of pancreatic carcinoma with highly sensitive diagnostic imaging meth... more Background: Early diagnosis of pancreatic carcinoma with highly sensitive diagnostic imaging methods could save lives of many thousands of patients, because early detection increases resectability and survival rates. Current non-invasive diagnostic imaging techniques have inadequate resolution and sensitivity for detection of small size (,2-3 mm) early pancreatic carcinoma lesions. Therefore, we have assessed the efficacy of positron emission tomography and computer tomography (PET/CT) imaging with b-O-D-galactopyranosyl-(1,49)-29-deoxy-29-[ 18 F]fluoroethyl-D-glucopyranose ([ 18 F]FEDL) for detection of less than 3 mm orthotopic xenografts of L3.6pl pancreatic carcinomas in mice. [ 18 F]FEDL is a novel radioligand of hepatocarcinoma-intestine-pancreas/pancreatitis-associated protein (HIP/PAP), which is overexpressed in peritumoral pancreatic acinar cells.
Nuclear Medicine and Biology, 2008
Introduction: [ 18 F]-Labeled analogues of thymidine have demonstrated efficacy for PET imaging o... more Introduction: [ 18 F]-Labeled analogues of thymidine have demonstrated efficacy for PET imaging of cellular proliferation. We have synthesized two [ 18 F]-labeled N 3 -substituted thymidine analogues, N 3 -[ 18 F]fluoroethyl thymidine (N 3 -[ 18 F]-FET) and N 3 -[ 18 F]fluoropropyl thymidine (N 3 -[ 18 F]-FPrT), and performed preliminary PET imaging studies in tumor-bearing mice. Methods: Thymidine was converted to its 3′,5′-O-bis-tetrahydropyranyl ether, which was then converted to the N 3 -ethyl and propylsubstituted mesylate precursors. Reactions of these mesylate precursors with n-Bu 4 N[ 18 F] or K[ 18 F]/kryptofix followed by acid hydrolysis and HPLC purification yielded N 3 -[ 18 F]-FET and N 3 -[ 18 F]-FPrT, respectively. Subcutaneous (sc) xenografts of H441 human non-small cell lung cancer were established in two groups of mice (each n=6). Micro-PET images of the tumor-bearing animals were acquired after intravenous injection of N 3 -[ 18 F]-FET or N 3 -[ 18 F]-FPrT (3700 KBq/animal). Results: The radiochemical yields were 2-12% (d.c.) for N 3 -[ 18 F]-FET and 30-38% (d.c.) for N 3 -[ 18 F]-FPrT. Radiochemical purity was N99% and calculated specific activity was N74 GBq/μmol at the end of synthesis. The accumulation of N 3 -[ 18 F]-FET and N 3 -[ 18 F]-FPrT in the tumor tissue at 2 h postinjection was 1.81±0.78 and 2.95±1
Nuclear Medicine and Biology, 2000
Interest remains strong for the development of a noninvasive technique for assessment of regional... more Interest remains strong for the development of a noninvasive technique for assessment of regional fatty acid oxidation rate in the myocardium. 18 F-labeled 4-thia palmitate (FTP, 16-[ 18 F]fluoro-4thia-hexadecanoic acid) has been synthesized and preliminarily evaluated as a metabolically trapped probe of myocardial fatty acid oxidation for positron emission tomography (PET). The radiotracer is synthesized by Kryptofix 2.2.2/K 2 CO 3 assisted nucleophilic radiofluorination of an iodo-ester precursor, followed by alkaline hydrolysis and by purification by reverse phase high performance liquid chromatography. Biodistribution studies in rats showed high uptake and long retention of FTP in heart, liver, and kidneys consistent with relatively high fatty acid oxidation rates in these tissues. Inhibition of carnitine palmitoyl-transferase-I caused an 80% reduction in myocardial uptake, suggesting the dependence of trapping on the transport of tracer into the mitochondrion. Experiments with perfused rat hearts showed that the estimates of the fractional metabolic trapping rate (FR) of FTP tracked inhibition of oxidation rate of palmitate with hypoxia, whereas the FR of the 6-thia analog 17-[ 18 F]fluoro-6-thia-heptadecanoic acid was insensitive to hypoxia. In vivo defluorination of FTP in the rat was evidenced by bone uptake of radioactivity. A PET imaging study with FTP in normal swine showed excellent myocardial images, prolonged myocardial retention, and no bone uptake of radioactivity up to 3 h, the last finding suggesting a species dependence for defluorination of the omega-labeled fatty acid. The results support further investigation of FTP as a potential PET tracer for assessing regional fatty acid oxidation rate in the human myocardium. NUCL MED BIOL 27;3:221-231, 2000.
Molecular Imaging and Biology, 2011
Introduction: Previous studies demonstrated that the lactose-binding protein (hepatocellular carc... more Introduction: Previous studies demonstrated that the lactose-binding protein (hepatocellular carcinoma-intestine-pancreas and pancreatitis-associated proteins (HIP/PAP)) is upregulated 9130 times in peritumoral pancreatic tissue as compared to normal pancreatic tissue. Therefore, we developed a new radiolabeled ligand of HIP/PAP, the ethyl-β-D-galactopyranosyl-(1,4′)-2′deoxy-2′-[ 18 F]fluoro-β-D-glucopyranoside (Et-[ 18 F]FDL) for noninvasive imaging of pancreatic carcinoma using positron emission tomography and computerized tomography (PET/CT). Methods: The novel precursor and radiolabeling methods for synthesis of Et-[ 18 F]FDL produced no isomers; the average decay-corrected radiochemical yield was 68%, radiochemical purity 999%, and specific activity 974 GBq/µmol. The radioligand properties of Et-[ 18 F]FDL were evaluated using an ex vivo autoradiography and immunohistochemistry in pancreatic tissue sections obtained from mice-bearing orthotopic pancreatic tumor xenografts. Results and Discussion: Et-[ 18 F]FDL binding to peritumoral pancreatic tissue sections strongly correlated with HIP/PAP expression (r=0.81) and could be completely blocked by treatment with 1 mM lactose. Conclusion: These results suggest that Et-[ 18 F]FDL is a promising agent which should be evaluated for detection of early pancreatic carcinomas by PET/CT imaging.
Molecular Cancer Therapeutics, 2009
The standard treatment for most advanced cancers is multidrug therapy. Unfortunately, combination... more The standard treatment for most advanced cancers is multidrug therapy. Unfortunately, combinations in the clinic often do not perform as predicted. Therefore, to complement identifying rational drug combinations based on biological assumptions, we hypothesized that a functional screen of drug combinations, without limits on combination sizes, will aid the identification of effective drug cocktails. Given the myriad possible cocktails and inspired by examples of search algorithms in diverse fields outside of medicine, we developed a novel, efficient search strategy called Medicinal Algorithmic Combinatorial Screen (MACS). Such algorithms work by enriching for the fitness of cocktails, as defined by specific attributes through successive generations. Because assessment of synergy was not feasible, we developed a novel alternative fitness function based on the level of inhibition and the number of drugs. Using a WST-1 assay on the A549 cell line, through MACS, we screened 72 combinations of arbitrary size formed from a 19-drug pool across four generations. Fenretinide, suberoylanilide hydroxamic acid, and bortezomib (FSB) was the fittest. FSB performed up to 4.18 SD above the mean of a random set of cocktails or ''too well'' to have been found by chance, supporting the utility of the MACS strategy. Validation studies showed FSB was inhibitory in all 7 other NSCLC cell lines tested. It was also synergistic in A549, the one cell line in which this was evaluated. These results suggest that when guided by MACS, screening larger drug combinations may be feasible as a first step in combination drug discovery in a relatively small number of experiments. [Mol Cancer Ther
Molecular Cancer Therapeutics, 2009
Hypoxia inducible factor-1 (HIF-1) promotes tumor cell adaptation to microenvironmental stress. H... more Hypoxia inducible factor-1 (HIF-1) promotes tumor cell adaptation to microenvironmental stress. HIF-1 is up-regulated in irradiated tumors and serves as a promising target for radiosensitization. We initially confirmed that the orally bioavailable HIF-1 inhibitor PX-478 reduces HIF-1 protein levels and signaling in vitro in a dose-dependent manner and provides direct radiosensitization of hypoxic cancer cells in clonogenic survival assays using C6 glioma, HN5 and UMSCCa10 squamous cells, and Panc-1 pancreatic adenocarcinoma cell lines. However, PX-478 yields striking in vivo tumor sensitization to single-dose irradiation, which cannot be explained by incremental improvement in direct tumor cell killing. We show that PX-478 prevents postradiation HIF-1 signaling and abrogates downstream stromal adaptation in C6 and HN5 reporter xenografts as measured by serial ultrasound, vascular magnetic resonance imaging, and hypoxia response element-specific micro-positron emission tomography imaging. The primacy of indirect PX-478 in vivo effects was corroborated by our findings that (a) either concurrent or early postradiation sequencing of PX-478 provides roughly equivalent sensitization and (b) constitutive vascular endothelial growth factor expression maintains refractory tumor vessel function and progression following combined radiation and PX-478. These results confirm that disruption of postradiation adaptive HIF-1 signaling by PX-478 imparts increased therapeutic efficacy through blockade of HIF-1-dependent reconstitution of tumor stromal function. Successful translation of targeted HIF-1 radiosensitization to the clinical setting will require specific consideration of tumor microenvironmental effects and mechanisms.
Molecular Cancer Research, 2011
Hypoxia-inducible factor 1 (HIF-1) promotes cancer cell survival and tumor progression. The speci... more Hypoxia-inducible factor 1 (HIF-1) promotes cancer cell survival and tumor progression. The specific role played by HIF-1 and tumor-stromal interactions toward determining tumor resistance to radiation treatment remains undefined. We applied a multimodality preclinical imaging platform to mechanistically characterize tumor response to radiation, with a focus on HIF-1-dependent resistance pathways. C6 glioma and HN5 human squamous carcinoma cells were stably transfected with a dual HIF-1 signaling reporter construct (dxHRE-tk/eGFP-cmvRed2XPRT). Reporter cells were serially interrogated in vitro before and after irradiation as monolayer and multicellular spheroid cultures and as subcutaneous xenografts in nu/nu mice. In vitro, single-dose irradiation of C6 and HN5 reporter cells modestly impacted HIF-1 signaling in normoxic monolayers and inhibited HIF-1 signaling in maturing spheroids. In contrast, irradiation of C6 or HN5 reporter xenografts with 8 Gy in vivo elicited marked upregulation of HIF-1 signaling and downstream proangiogenic signaling at 48 hours which preceded recovery of tumor growth. In situ ultrasound imaging and dynamic contrast-enhanced (DCE) MRI indicated that HIF-1 signaling followed acute disruption of stromal vascular function. High-resolution positron emission tomography and dual-contrast DCE-MRI of immobilized dorsal skin window tumors confirmed postradiotherapy HIF-1 signaling to spatiotemporally coincide with impaired stromal vascular function. Targeted disruption of HIF-1 signaling established this pathway to be a determinant of tumor radioresistance. Our results illustrate that tumor radioresistance is mediated by a capacity to compensate for stromal vascular disruption through HIF-1-dependent proangiogenic signaling and that clinically relevant vascular imaging techniques can spatially define mechanisms associated with tumor irradiation.
Lung Cancer, 2005
Posters/Basic science/Ceil S153 e~press~on was the single factor that correlated with advanced di... more Posters/Basic science/Ceil S153 e~press~on was the single factor that correlated with advanced dinical stage (P 0 007) There was no significant difference between E-cadhedn and n,-catehin e0¢pression in squamous call carcinoma compared with adenocarclnoma The decline of both E4.~adberin and n,-catenin expression indicated a poor prognosis (P<00001 and P 00016. resbectively) in univariated analysis Multivariate analysis showed a significantly lower survival probability for patients with reduced E-Cadhedn (P <0 0001). and E-Cadhedn was an independent prognostic factor for survival of NSCLC patients Primarily. our results demensb'ated that E Cadhorln had potential to classify TNM staging system into more detalod subgroq~s. Patients with reduced expression of E Cadhenn. even though in the same stage and histological type. had shorter su~val time compared with patients with preserved E~adhonn expression. Conclusions: This study suggests that dysfunction of E Cadhonn has an important impact in the prograssion of lung cancer. As an independent prog nostio and sub grouping factor, e~prossion of ECadhenn can as=st clinicians to precict outcome of different stages in NSCLS. together with conventional prognostic factors, and subsequently make appropriate management
Journal of Nuclear Medicine, 2009
Imaging 2 different molecular-genetic events in a single subject by PET is essential in a variety... more Imaging 2 different molecular-genetic events in a single subject by PET is essential in a variety of in vivo applications. Using herpes simplex virus-1 thymidine kinase (HSV1-tk) mutants with narrower substrate specificities in combination with wild-type HSV1-tk (wtHSV1-tk) would enable differential imaging with corresponding radiotracers, namely 29-deoxy-29-18 F-fluoro-5ethyl-1-b-D-arabinofuranosyl-uracil ( 18 F-FEAU) and the acycloguanosine derivative 9-(4-18 F-fluoro-3-[hydroxymethyl]butyl)guanine ( 18 F-FHBG). In this study, we evaluated wtHSV1-tk and the A168H mutant, which has been reported to exhibit enhanced acycloguanosine substrate catalytic activity and diminished pyrimidine phosphorylating activity, as PET reporter genes. Methods: Computational analysis was performed to assess the binding mode of FHBG and FEAU to wtHSV1-tk and the A168H variant. U87 cells were stably transduced with wtHSV1-tk or HSV1-tk(A168H) fused with green fluorescent protein and sorted to obtain equivalent transgene expression. In vitro uptake studies were performed to determine rates of substrate accumulation and retention. Nude mice bearing tumors expressing HSV1-tk variants were subsequently imaged using 18 F-FHBG and 18 F-FEAU. Results: Docking results indicate that binding of FHBG to the A168H variant is unaffected whereas the binding of FEAU is hindered because of a steric clash with the bulkier mutant residues. U87 cells expressing HSV1-tk(A168H) accumulated 18 F-FHBG in in vitro uptake studies at a 3-fold higher rate than did cells expressing wtHSV1-tk without any detectable accumulation of 3 H-FEAU. Furthermore, HSV1-tk(A168H) demonstrated no thymidine phosphorylation activity. In contrast, U87 cells expressing wtHSV1-tk preferentially accumulated 3 H-FEAU at an 18-fold higher rate than they did 18 F-FHBG. Tumors expressing wtHSV1-tk or HSV1-tk(A168H) were distinctly imaged with 18 F-FEAU or 18 F-FHBG, respectively. Hence, tumors expressing HSV1-tk(A168H) accumulated 8.4-fold more 18 F-FHBG than did tumors expressing wtHSV1-tk. In addition, wtHSV1-tk tumors, compared with HSV1-tk(A168H)-expressing tumors (which retained baseline levels of the radiotracer), preferentially accumulated 18 F-FEAU. Conclusion: The FEAU and FHBG substrate discrimination capacity of the wtHSV1-tk and HSV1-tk(A168H) reporter enzymes was validated in vivo by PET of mice with tumor xenografts established from U87 cells expressing these different reporters. Thus, HSV1-tk(A168H) may potentially be used as a second reporter gene in combination with wtHSV1-tk to achieve differential PET.
Journal of Biomedical Optics, 2006
Thermal therapy efficacy can be diminished due to heat shock protein (HSP) induction in regions o... more Thermal therapy efficacy can be diminished due to heat shock protein (HSP) induction in regions of a tumor where temperatures are insufficient to coagulate proteins. HSP expression enhances tumor cell viability and imparts resistance to chemotherapy and radiation treatments, which are generally employed in conjunction with hyperthermia. Therefore, an understanding of the thermally induced HSP expression within the targeted tumor must be incorporated into the treatment plan to optimize the thermal dose delivery and permit prediction of the overall tissue response. A treatment planning computational model capable of predicting the temperature, HSP27 and HSP70 expression, and damage fraction distributions associated with laser heating in healthy prostate tissue and tumors is presented. Measured thermally induced HSP27 and HSP70 expression kinetics and injury data for normal and cancerous prostate cells and prostate tumors are employed to create the first HSP expression predictive model and formulate an Arrhenius damage model. The correlation coefficients between measured and model predicted temperature, HSP27, and HSP70 were 0.98, 0.99, and 0.99, respectively, confirming the accuracy of the model. Utilization of the treatment planning model in the design of prostate cancer thermal therapies can enable optimization of the treatment outcome by controlling HSP expression and injury.
PloS one, 2011
The long-term fate of stem cells after intramyocardial delivery is unknown. We used noninvasive, ... more The long-term fate of stem cells after intramyocardial delivery is unknown. We used noninvasive, repetitive PET/CT imaging with [(18)F]FEAU to monitor the long-term (up to 5 months) spatial-temporal dynamics of MSCs retrovirally transduced with the sr39HSV1-tk gene (sr39HSV1-tk-MSC) and implanted intramyocardially in pigs with induced acute myocardial infarction. Repetitive [(18)F]FEAU PET/CT revealed a biphasic pattern of sr39HSV1-tk-MSC dynamics; cell proliferation peaked at 33-35 days after injection, in periinfarct regions and the major cardiac lymphatic vessels and lymph nodes. The sr39HSV1-tk-MSC-associated [(18)F]FEAU signals gradually decreased thereafter. Cardiac lymphography studies using PG-Gd-NIRF813 contrast for MRI and near-infrared fluorescence imaging showed rapid clearance of the contrast from the site of intramyocardial injection through the subepicardial lymphatic network into the lymphatic vessels and periaortic lymph nodes. Immunohistochemical analysis of cardia...
European Journal of Nuclear Medicine and Molecular Imaging, 2008
Bioorganic & Medicinal Chemistry, 2011
Cannabinoid receptor 2 (CB2) plays an important role in human physiology and the pathophysiology ... more Cannabinoid receptor 2 (CB2) plays an important role in human physiology and the pathophysiology of different diseases, including neuroinflammation, neurodegeneration, and cancer. Several classes of CB2 receptor ligands, including 2-oxoquinoline derivatives, have been previously reported. We report the synthesis and results of in vitro receptor binding of a focused library of new fluorinated 2-oxoquinoline CB2 ligands. Twelve compounds, 13-16 18, 19, 21-24, 27, and 28 were synthesized in good yields in multiple steps. Human U87 glioma cells expressing either hCB1 (control) or hCB2 were generated via lentiviral transduction. In vitro competitive binding assay was performed using [ 3 H]CP-55,940 in U87hCB1 and U87hCB2 cells. Inhibition constant , 27, and 28 for CB2 were >10000, 2.8, 5.0, 2.4, 22, 0.8, 1.4, >10000, 486, 58, 620, and 2400 nM, respectively, and those for CB1 were >10000 nM. Preliminary in vitro results suggest that six of these compounds may be useful for therapy of neuropathic pain, neuroinflammatory diseases and immune disorders. In addition, compound 19, with its subnanomolar Ki value, could be radiolabeled with 18 F and explored for PET imaging of CB2 expression.