Rajani Ravi - Academia.edu (original) (raw)

Papers by Rajani Ravi

Solid phononic crystal (PnC) lenses were made active on infiltration with thermosensitive polymer... more Solid phononic crystal (PnC) lenses were made active on infiltration with thermosensitive polymers to produce a thermoactuated hybrid solid lens with variable focusing. Acoustic lenses, both solid state and PnCbased, are passive elements with a fixed focal length. Their focal characteristics are functions of the lens structure or the arrangement of the PnC unit cell. Dispersion effects, liquidfilled membranes, and phase delay in a multi-element emitter have been used for variable focusing. The high thermal, electric, and electromagnetic sensitivity of the elastic properties of poly(vinyl alcohol) (PVA) poly(N-isopropylacrylamide) (PNIPAm)-based hydrogels enable them to operate as tunable solids. However, these solids do not have strong enough contrast with water or well-controlled shape parameters to function as standalone lenses. Here, a tunable hybrid solid ultrasonic lens is realized by combining a PnC lens with PVA-PNIPAm thermoacoustic hydrogel to modify the transmission and dispersion properties of transient acoustic waves. Variable focusing is demonstrated from 40 to 50 mm using the anomalous thermosensitivity of the elasticity and speed of sound of the hydrogel.

Cancer research, Jan 1, 2010

The p53 family gene p63 plays an instrumental role in cellular stress responses including respons... more The p53 family gene p63 plays an instrumental role in cellular stress responses including responses to DNA damage. In addition to encoding a full-length transcriptional activator, p63 also encodes several dominant inhibitory isoforms including the isoform ΔNp63α, the function of which is not fully understood. ΔNp63α is degraded in response to DNA damage, thereby enabling an effective cellular response to genotoxic agents. Here, we identify a key molecular mechanism underlying regulation of ΔNp63α expression in response to chemotherapeutic agents or tumor necrosis factor-α. We found that ΔNp63α interacts with IκB kinase (IKK), a multisubunit protein kinase that consists of two catalytic subunits, IKKα and IKKβ, and a regulatory subunit, IKKγ. The IKKβ kinase promotes ubiquitin-mediated proteasomal degradation of ΔNp63α, whereas a kinasedeficient mutant IKKβ-K44A fails to do so. Cytokine-or chemotherapy-induced stimulation of IKKβ caused degradation of ΔNp63α and augmented transactivation of p53 family-induced genes involved in the cellular response to DNA damage. Conversely, IKKβ inhibition attenuated cytokine-or chemotherapy-induced degradation of ΔNp63α. Our findings show that IKKβ plays an essential role in regulating ΔNp63α in response to extrinsic stimuli. IKK activation represents one mechanism by which levels of ΔNp63α can be reduced, thereby rendering cells susceptible to cell death in the face of cellular stress or DNA damage.

Cancer Research, 2004

The majority of colorectal cancers have lost/inactivated the p53 tumor suppressor gene. Using iso... more The majority of colorectal cancers have lost/inactivated the p53 tumor suppressor gene. Using isogenic human colon cancer cells that differ only in their p53 status, we demonstrate that loss of p53 renders tumor cells relatively resistant to the topoisomerase I inhibitor, irinotecan. Whereas irinotecan-induced up-regulation of the proapoptotic proteins PUMA and Noxa requires p53, we find that irinotecan inhibits Janus kinase 2 (JAK2)signal transducer and activator of transcription 3 and 5 (STAT3/5) signaling in both p53-proficient and p53-deficient tumor cells. We show that irinotecan inhibits JAK2-STAT3/5-dependent expression of survival proteins (Bcl-x L and XIAP) and cooperates with Apo2 ligand/tumor necrosis factor-related apoptosis-inducing ligand (Apo2L/TRAIL) to facilitate p53independent apoptosis of colon cancer cells. Whereas xenografts of p53deficient colon cancer cells are relatively resistant to irinotecan compared with their p53-proficient counterparts, combined treatment with irinotecan and Apo2L/TRAIL eliminates hepatic metastases of both p53-proficient and p53-deficient cancer cells in vivo and significantly improves the survival of animals relative to treatment with either agent alone. Although the synergy between chemotherapy and Apo2L/TRAIL has been ascribed to p53, our data demonstrate that irinotecan enhances Apo2L/TRAILinduced apoptosis of tumor cells via a distinct p53-independent mechanism involving inhibition of JAK2-STAT3/5 signaling. These findings identify a novel p53-independent channel of cross-talk between topoisomerase I inhibitors and Apo2L/TRAIL and suggest that the addition of Apo2L/TRAIL can improve the therapeutic index of irinotecan against both p53-proficient and p53-deficient colorectal cancers, including those that have metastasized to the liver.

Methods in molecular medicine, 2003

Novartis Foundation Symposia, 2001

Otto Warburg's classic treatise on the reprogramming of tumour metabolism from oxidative ... more Otto Warburg's classic treatise on the reprogramming of tumour metabolism from oxidative to glycolytic metabolism was published in London in 1930. Although the Warburg effect is one of the most universal characteristics of solid tumours, the molecular basis for this phenomenon has only recently been elucidated by studies indicating that increased expression of genes encoding glucose transporters and glycolytic enzymes in tumour cells is mediated by the transcription factors c-MYC and HIF-1. Whereas c-myc is a direct target for oncogenic mutations, expression of hypoxia-inducible factor 1 (HIF-1) is indirectly up-regulated via gain-of-function mutations in oncogenes and loss-of-function mutations in tumour suppressor genes that result increased HIF-1alpha protein expression and/or increased HIF-1 transcriptional activity in a cell-type-specific manner. As a result of genetic alterations and intratumoral hypoxia, HIF-1alpha is overexpressed in the majority of common human cancers relative to the surrounding normal tissue. In human breast cancer and brain tumours, HIF-1alpha overexpression is strongly correlated with tumour grade and vascularity.

Oral oncology, Jan 12, 2015

A combination of cetuximab and sorafenib in patients with recurrent and/or metastatic (R/M) head ... more A combination of cetuximab and sorafenib in patients with recurrent and/or metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) were assessed for potential benefit. In a randomized phase II study, R/M HNSCC patients were treated with cetuximab 400mg/m(2) IV on day 1 followed by 250mg/m(2) IV weekly (Arm A), or cetuximab at the same dose/schedule plus sorafenib 400mg PO twice-a-day (Arm B). Each cycle was 21days. Tumor p16 and HPV status, and plasma immunomodulatory cytokine levels were assessed. Of 55 patients enrolled (Arm A-27, Arm B-28), 52 patients received assigned treatments and 43 were evaluable for response. Overall response rate was 8% for both arms. Median overall survival (OS) and progression-free survival (PFS) were 9.0 and 3.0months in Arm A, and 5.7 and 3.2months in Arm B, respectively. Forty-four patients had tumors available for p16 staining (35-negative, 9-positive). Three of nine p16-positive tumors were also HPV positive. The p16-negative patients had si...

Hepatology, 2007

In nonalcoholic fatty liver disease, the pathogenesis of progression from simple steatosis to ste... more In nonalcoholic fatty liver disease, the pathogenesis of progression from simple steatosis to steatohepatitis has not been fully clarified. Many factors, including oxidative stress and hepatic immune regulation, contribute to the inflammation in steatosis. Because regulatory T cells (Tregs) are important components of immune regulation, we have now investigated their role in the pathogenesis of nonalcoholic steatohepatitis. Wild-type C57BL/6 mice were fed a high-fat (HF) diet to induce steatosis, and the hepatic lymphocyte population was analyzed by flow cytometry. HF-induced steatosis was associated with the depletion of hepatic Tregs and led to up-regulation of the inflammatory tumor necrosis factor-␣ signaling pathway. When challenged by exogenous lipopolysaccharide, the HF-fed mice developed liver inflammation. In contrast, the adoptive transfer of Tregs decreased inflammation in HF-fed mice. In comparison with effector T cells, Tregs had a lower expression of Bcl-2 and, therefore, increased susceptibility to oxidative stress-induced apoptosis. The treatment of mice with the antioxidant Mn(III)tetrakis(4-benzoic acid)porphyrin chloride reduced Treg apoptosis, increased the number of hepatic Tregs, and decreased hepatic inflammation in HF-fed mice. Conclusion: Our results indicate that increased oxidative stress in a fatty liver causes the apoptosis of Tregs, reduces the number of hepatic Tregs, and leads to a lowered suppression of inflammatory responses. This scenario is likely one of the pathogenetic mechanisms that facilitate the transformation of simple steatosis into steatohepatitis when a fatty liver is exposed to second or third hits. (HEPATOLOGY 2007;46:1519-1529

British Journal of Urology, 1993

From 1962 to 1990, 231 inguinal and 174 ilio-inguinal lymphadenectomies were performed on 234 pat... more From 1962 to 1990, 231 inguinal and 174 ilio-inguinal lymphadenectomies were performed on 234 patients with penile carcinoma. The morbidity of inguinal lymphadenectomy included wound infection in 18%, skin edge necrosis in 61%, seroma formation in 5% of dissections, and lymphoedema in 25% of limbs. The morbidity of ilio-inguinal lymphadenectomy included wound infection in 14%, skin edge necrosis in 64%, seroma formation in 9% of dissections, and lymphoedema in 29% of limbs. Pre-operative radiation to the groin significantly increased the healing complications. The routine use of a myocutaneous flap for primary reconstruction of the groin following ilio-inguinal lymphadenectomy resulted in 100% primary wound healing and significantly reduced the post-operative hospital stay to a mean of 10 days.

Page 1. Chapter 14 / Implications for Cancer Therapy 231 From: Cancer Drug Discovery and Developm... more Page 1. Chapter 14 / Implications for Cancer Therapy 231 From: Cancer Drug Discovery and Development: Death Receptors in Cancer Therapy Edited by: WS El-Deiry © Humana Press Inc., Totowa, NJ 231 14 Regulation of Death Receptor-Induced Apoptosis ...

Cancer Research, Oct 15, 1998

Thf /)5J tumor suppressor gene plays an instrumental role in transcriptional regulation of target... more Thf /)5J tumor suppressor gene plays an instrumental role in transcriptional regulation of target genes involved in cellular stress responses. p53-dependent transactivation and transrepression require its interaction with p300/CBP, a coactivator that also interacts with the RelA subunit of nuclear factor-KB. We find that p53 inhibits RelA-dependent transacti vation without altering RelA expression or inducible KB-DNA binding. p53-mediated repression of RelA is relieved by p300 overexpression and the increased RelA activity conferred by p53-deficiency is counteracted by either transactivation domain-deficient p300 fragments that bind RelA or a transdominant mutant of lidt«. Our results suggest that p53 can regulate diverse KB-dependent cellular responses.

Cancer Research, 2010

... hygro (Invitrogen). Flag-IKKβ and IKKα were provided by Dr. Karin (University of California, ... more ... hygro (Invitrogen). Flag-IKKβ and IKKα were provided by Dr. Karin (University of California, San Diego, CA). HA-IKKβ and HA-IKKα were provided by Dr. Zandi (University of South California, Los Angeles, CA). Mutant HA-IKKα ...

Therapy of B-cell chronic lymphocytic leukemia (CLL) has been limited by both the nonselectivity ... more Therapy of B-cell chronic lymphocytic leukemia (CLL) has been limited by both the nonselectivity of therapeutic agents toward normal residual immune cells and inherent drug resistance. Identification of agents that spare normal immune effector cells, thus facilitating addition of immune-based therapies, and that modulate factors associated with drug resistance in CLL might represent a major therapeutic advance. Depsipeptide (FR901228) is a novel agent entering clinical trials that has selective in vitro activity against resistant leukemia cell lines. To assess its in vitro activity in CLL, we exposed peripheral mononuclear cells from CLL patients (n = 10) to varying concentrations of this agent. Viability of the CLL cells was reduced by 50% (LC(50)) at 4 hours, 24 hours, and 4 days at depsipeptide concentrations of 0.038, 0.024, and 0.015 micromol/L, respectively. Depsipeptide had marked selective cytotoxicity when compared with normal blood mononuclear cells, in which the LC(50) was 3.44 micromol/L at 4 hours (P =.03), 0.965 micromol/L at 24 hours (P =.01), and 0.0318 micromol/L at 96 hours (P =.04). Inhibition of bone marrow progenitor cell growth was also minimal after incubation with 0.015 micromol/L (19% inhibition of colony forming unit-granulocyte-macrophage [CFU-GM]; 17% inhibition burst forming unit-erythroid [BFU-E]) and 3.44 micromol/L (24% inhibition of CFU-GM; 57% inhibition BFU-E) of depsipeptide for 4 hours, followed by a 14-day incubation period. Expression of apoptotic proteins after depsipeptide exposure (0.015 micromol/L) included no change in bcl-2, elevation of bax, and decreased expression of p27. These data demonstrate that depsipeptide has significant selective in vitro activity against human CLL cells concurrent with favorable alterations of the bcl-2:bax protein ratio and decrease in p27 expression. Such findings strongly support the early introduction of depsipeptide into clinical trials for patients with CLL.

Drug Resistance Updates, 2004

Cancer Research

Gene therapy of B16 tumors with a dominant-negative signal transducer and activator of transcript... more Gene therapy of B16 tumors with a dominant-negative signal transducer and activator of transcription (Stat3) variant, designated Stat3␤, results in inhibition of tumor growth and tumor regression. Although only 10 -15% of the tumor cells are transfected in vivo, the Stat3␤-induced antitumor effect is associated with massive apoptosis of B16 tumor cells, indicative of a potent bystander effect. Here, we provide evidence that blocking Stat3 signaling in B16 cells results in release of soluble factors that are capable of inducing apoptosis and cell cycle arrest of nontransfected B16 cells. RNase protection assays using multi-template probes specific for key physiological regulators of apoptosis reveal that overexpression of Stat3␤ in B16 tumor cells induces the expression of the apoptotic effector, tumor necrosis factor-related apoptosis-inducing ligand. These in vitro results suggest that the observed in vivo bystander effect leading to tumor cell growth inhibition is mediated, at least in part, by soluble factors produced as a result of overexpression of Stat3␤ in tumor cells.

Cancer Research

Activation of the nuclear factor (NF)-KB transcription factor is instru mental for the immune res... more Activation of the nuclear factor (NF)-KB transcription factor is instru mental for the immune response and the survival of peripheral activated T cells. We demonstrate that ligation of CD95 (Fas/APOl), a potent apoptotic stimulus in lymphocytes, results in repression of NF-KB activity in Jurkat T cells by inducing the proteolytic cleavage of NF-KB p65 (Rei A) and p50. Inhibition of caspase-3-related proteases by a specific acetylated aldehyde (Ac-DEVD-CHO) prevented CD95-induced cleavage of p65 (RelA) or p50 and restored the inducibility of NF-KB in cells treated with an antibody against CD95. The addition of recombinant caspase-3 also resulted in proteolytic cleavage of RelA p65 and p50 in vitro. INI-« treatment, unlike CD95 ligation, did not result in the death of Jurkat cells but did so in the presence of Ih-HuM. a transdominant inhibitor of NF-KB. These results suggest that intact, functional NF-KB maintains the survival of activated T cells, and that CD95-induced cleavage of NF-KB subunits sensitizes T cells to apoptosis and, hence, facilitates the decay of an immune response.

Genes & Development

The switch to an angiogenic phenotype is a fundamental determinant of neoplastic growth and tumor... more The switch to an angiogenic phenotype is a fundamental determinant of neoplastic growth and tumor progression. We demonstrate that homozygous deletion of the p53 tumor suppressor gene via homologous recombination in a human cancer cell line promotes the neovascularization and growth of tumor xenografts in nude mice. We find that p53 promotes Mdm2-mediated ubiquitination and proteasomal degradation of the HIF-1␣ subunit of hypoxia-inducible factor 1 (HIF-1), a heterodimeric transcription factor that regulates cellular energy metabolism and angiogenesis in response to oxygen deprivation.

Nature communications, 2015

Lungs resected for adenocarcinomas often harbour minute discrete foci of cytologically atypical p... more Lungs resected for adenocarcinomas often harbour minute discrete foci of cytologically atypical pneumocyte proliferations designated as atypical adenomatous hyperplasia (AAH). Evidence suggests that AAH represents an initial step in the progression to adenocarcinoma in situ (AIS), minimally invasive adenocarcinoma (MIA) and fully invasive adenocarcinoma. Despite efforts to identify predictive markers of malignant transformation, alterations driving this progression are poorly understood. Here we perform targeted next-generation sequencing on multifocal AAHs and different zones of histologic progression within AISs and MIAs. Multiregion sequencing demonstrated different genetic drivers within the same tumour and reveal that clonal expansion is an early event of tumorigenesis. We find that KRAS, TP53 and EGFR mutations are indicators of malignant transition. Utilizing droplet digital PCR, we find alterations associated with early neoplasms in paired circulating DNA. This study provide...

Science

Caspases are a family of cysteine proteases implicated in the biochemical and morphological chang... more Caspases are a family of cysteine proteases implicated in the biochemical and morphological changes that occur during apoptosis (programmed cell death). The loop domain of Bcl-2 is cleaved at Asp34 by caspase-3 (CPP32) in vitro, in cells overexpressing caspase-3, and after induction of apoptosis by Fas ligation and interleukin-3 withdrawal. The carboxyl-terminal Bcl-2 cleavage product triggered cell death and accelerated Sindbis virus-induced apoptosis, which was dependent on the BH3 homology and transmembrane domains of Bcl-2. Inhibitor studies indicated that cleavage of Bcl-2 may further activate downstream caspases and contribute to amplification of the caspase cascade. Cleavage-resistant mutants of Bcl-2 had increased protection from interleukin-3 withdrawal and Sindbis virus-induced apoptosis. Thus, cleavage of Bcl-2 by caspases may ensure the inevitability of cell death.

The HER-2/neu receptor is a member of the epidermal growth factor family and is amplified in mult... more The HER-2/neu receptor is a member of the epidermal growth factor family and is amplified in multiple cancers. It is under intense investiga- tion both as a prognostic marker and for therapy, using monoclonal antibodies targeted against the receptor. We have developed a novel two-component gadolinium-based MR contrast agent to image the HER- 2/neu receptor. Positive T1 contrast in MR

Solid phononic crystal (PnC) lenses were made active on infiltration with thermosensitive polymer... more Solid phononic crystal (PnC) lenses were made active on infiltration with thermosensitive polymers to produce a thermoactuated hybrid solid lens with variable focusing. Acoustic lenses, both solid state and PnCbased, are passive elements with a fixed focal length. Their focal characteristics are functions of the lens structure or the arrangement of the PnC unit cell. Dispersion effects, liquidfilled membranes, and phase delay in a multi-element emitter have been used for variable focusing. The high thermal, electric, and electromagnetic sensitivity of the elastic properties of poly(vinyl alcohol) (PVA) poly(N-isopropylacrylamide) (PNIPAm)-based hydrogels enable them to operate as tunable solids. However, these solids do not have strong enough contrast with water or well-controlled shape parameters to function as standalone lenses. Here, a tunable hybrid solid ultrasonic lens is realized by combining a PnC lens with PVA-PNIPAm thermoacoustic hydrogel to modify the transmission and dispersion properties of transient acoustic waves. Variable focusing is demonstrated from 40 to 50 mm using the anomalous thermosensitivity of the elasticity and speed of sound of the hydrogel.

Cancer research, Jan 1, 2010

The p53 family gene p63 plays an instrumental role in cellular stress responses including respons... more The p53 family gene p63 plays an instrumental role in cellular stress responses including responses to DNA damage. In addition to encoding a full-length transcriptional activator, p63 also encodes several dominant inhibitory isoforms including the isoform ΔNp63α, the function of which is not fully understood. ΔNp63α is degraded in response to DNA damage, thereby enabling an effective cellular response to genotoxic agents. Here, we identify a key molecular mechanism underlying regulation of ΔNp63α expression in response to chemotherapeutic agents or tumor necrosis factor-α. We found that ΔNp63α interacts with IκB kinase (IKK), a multisubunit protein kinase that consists of two catalytic subunits, IKKα and IKKβ, and a regulatory subunit, IKKγ. The IKKβ kinase promotes ubiquitin-mediated proteasomal degradation of ΔNp63α, whereas a kinasedeficient mutant IKKβ-K44A fails to do so. Cytokine-or chemotherapy-induced stimulation of IKKβ caused degradation of ΔNp63α and augmented transactivation of p53 family-induced genes involved in the cellular response to DNA damage. Conversely, IKKβ inhibition attenuated cytokine-or chemotherapy-induced degradation of ΔNp63α. Our findings show that IKKβ plays an essential role in regulating ΔNp63α in response to extrinsic stimuli. IKK activation represents one mechanism by which levels of ΔNp63α can be reduced, thereby rendering cells susceptible to cell death in the face of cellular stress or DNA damage.

Cancer Research, 2004

The majority of colorectal cancers have lost/inactivated the p53 tumor suppressor gene. Using iso... more The majority of colorectal cancers have lost/inactivated the p53 tumor suppressor gene. Using isogenic human colon cancer cells that differ only in their p53 status, we demonstrate that loss of p53 renders tumor cells relatively resistant to the topoisomerase I inhibitor, irinotecan. Whereas irinotecan-induced up-regulation of the proapoptotic proteins PUMA and Noxa requires p53, we find that irinotecan inhibits Janus kinase 2 (JAK2)signal transducer and activator of transcription 3 and 5 (STAT3/5) signaling in both p53-proficient and p53-deficient tumor cells. We show that irinotecan inhibits JAK2-STAT3/5-dependent expression of survival proteins (Bcl-x L and XIAP) and cooperates with Apo2 ligand/tumor necrosis factor-related apoptosis-inducing ligand (Apo2L/TRAIL) to facilitate p53independent apoptosis of colon cancer cells. Whereas xenografts of p53deficient colon cancer cells are relatively resistant to irinotecan compared with their p53-proficient counterparts, combined treatment with irinotecan and Apo2L/TRAIL eliminates hepatic metastases of both p53-proficient and p53-deficient cancer cells in vivo and significantly improves the survival of animals relative to treatment with either agent alone. Although the synergy between chemotherapy and Apo2L/TRAIL has been ascribed to p53, our data demonstrate that irinotecan enhances Apo2L/TRAILinduced apoptosis of tumor cells via a distinct p53-independent mechanism involving inhibition of JAK2-STAT3/5 signaling. These findings identify a novel p53-independent channel of cross-talk between topoisomerase I inhibitors and Apo2L/TRAIL and suggest that the addition of Apo2L/TRAIL can improve the therapeutic index of irinotecan against both p53-proficient and p53-deficient colorectal cancers, including those that have metastasized to the liver.

Methods in molecular medicine, 2003

Novartis Foundation Symposia, 2001

Otto Warburg's classic treatise on the reprogramming of tumour metabolism from oxidative ... more Otto Warburg's classic treatise on the reprogramming of tumour metabolism from oxidative to glycolytic metabolism was published in London in 1930. Although the Warburg effect is one of the most universal characteristics of solid tumours, the molecular basis for this phenomenon has only recently been elucidated by studies indicating that increased expression of genes encoding glucose transporters and glycolytic enzymes in tumour cells is mediated by the transcription factors c-MYC and HIF-1. Whereas c-myc is a direct target for oncogenic mutations, expression of hypoxia-inducible factor 1 (HIF-1) is indirectly up-regulated via gain-of-function mutations in oncogenes and loss-of-function mutations in tumour suppressor genes that result increased HIF-1alpha protein expression and/or increased HIF-1 transcriptional activity in a cell-type-specific manner. As a result of genetic alterations and intratumoral hypoxia, HIF-1alpha is overexpressed in the majority of common human cancers relative to the surrounding normal tissue. In human breast cancer and brain tumours, HIF-1alpha overexpression is strongly correlated with tumour grade and vascularity.

Oral oncology, Jan 12, 2015

A combination of cetuximab and sorafenib in patients with recurrent and/or metastatic (R/M) head ... more A combination of cetuximab and sorafenib in patients with recurrent and/or metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) were assessed for potential benefit. In a randomized phase II study, R/M HNSCC patients were treated with cetuximab 400mg/m(2) IV on day 1 followed by 250mg/m(2) IV weekly (Arm A), or cetuximab at the same dose/schedule plus sorafenib 400mg PO twice-a-day (Arm B). Each cycle was 21days. Tumor p16 and HPV status, and plasma immunomodulatory cytokine levels were assessed. Of 55 patients enrolled (Arm A-27, Arm B-28), 52 patients received assigned treatments and 43 were evaluable for response. Overall response rate was 8% for both arms. Median overall survival (OS) and progression-free survival (PFS) were 9.0 and 3.0months in Arm A, and 5.7 and 3.2months in Arm B, respectively. Forty-four patients had tumors available for p16 staining (35-negative, 9-positive). Three of nine p16-positive tumors were also HPV positive. The p16-negative patients had si...

Hepatology, 2007

In nonalcoholic fatty liver disease, the pathogenesis of progression from simple steatosis to ste... more In nonalcoholic fatty liver disease, the pathogenesis of progression from simple steatosis to steatohepatitis has not been fully clarified. Many factors, including oxidative stress and hepatic immune regulation, contribute to the inflammation in steatosis. Because regulatory T cells (Tregs) are important components of immune regulation, we have now investigated their role in the pathogenesis of nonalcoholic steatohepatitis. Wild-type C57BL/6 mice were fed a high-fat (HF) diet to induce steatosis, and the hepatic lymphocyte population was analyzed by flow cytometry. HF-induced steatosis was associated with the depletion of hepatic Tregs and led to up-regulation of the inflammatory tumor necrosis factor-␣ signaling pathway. When challenged by exogenous lipopolysaccharide, the HF-fed mice developed liver inflammation. In contrast, the adoptive transfer of Tregs decreased inflammation in HF-fed mice. In comparison with effector T cells, Tregs had a lower expression of Bcl-2 and, therefore, increased susceptibility to oxidative stress-induced apoptosis. The treatment of mice with the antioxidant Mn(III)tetrakis(4-benzoic acid)porphyrin chloride reduced Treg apoptosis, increased the number of hepatic Tregs, and decreased hepatic inflammation in HF-fed mice. Conclusion: Our results indicate that increased oxidative stress in a fatty liver causes the apoptosis of Tregs, reduces the number of hepatic Tregs, and leads to a lowered suppression of inflammatory responses. This scenario is likely one of the pathogenetic mechanisms that facilitate the transformation of simple steatosis into steatohepatitis when a fatty liver is exposed to second or third hits. (HEPATOLOGY 2007;46:1519-1529

British Journal of Urology, 1993

From 1962 to 1990, 231 inguinal and 174 ilio-inguinal lymphadenectomies were performed on 234 pat... more From 1962 to 1990, 231 inguinal and 174 ilio-inguinal lymphadenectomies were performed on 234 patients with penile carcinoma. The morbidity of inguinal lymphadenectomy included wound infection in 18%, skin edge necrosis in 61%, seroma formation in 5% of dissections, and lymphoedema in 25% of limbs. The morbidity of ilio-inguinal lymphadenectomy included wound infection in 14%, skin edge necrosis in 64%, seroma formation in 9% of dissections, and lymphoedema in 29% of limbs. Pre-operative radiation to the groin significantly increased the healing complications. The routine use of a myocutaneous flap for primary reconstruction of the groin following ilio-inguinal lymphadenectomy resulted in 100% primary wound healing and significantly reduced the post-operative hospital stay to a mean of 10 days.

Page 1. Chapter 14 / Implications for Cancer Therapy 231 From: Cancer Drug Discovery and Developm... more Page 1. Chapter 14 / Implications for Cancer Therapy 231 From: Cancer Drug Discovery and Development: Death Receptors in Cancer Therapy Edited by: WS El-Deiry © Humana Press Inc., Totowa, NJ 231 14 Regulation of Death Receptor-Induced Apoptosis ...

Cancer Research, Oct 15, 1998

Thf /)5J tumor suppressor gene plays an instrumental role in transcriptional regulation of target... more Thf /)5J tumor suppressor gene plays an instrumental role in transcriptional regulation of target genes involved in cellular stress responses. p53-dependent transactivation and transrepression require its interaction with p300/CBP, a coactivator that also interacts with the RelA subunit of nuclear factor-KB. We find that p53 inhibits RelA-dependent transacti vation without altering RelA expression or inducible KB-DNA binding. p53-mediated repression of RelA is relieved by p300 overexpression and the increased RelA activity conferred by p53-deficiency is counteracted by either transactivation domain-deficient p300 fragments that bind RelA or a transdominant mutant of lidt«. Our results suggest that p53 can regulate diverse KB-dependent cellular responses.

Cancer Research, 2010

... hygro (Invitrogen). Flag-IKKβ and IKKα were provided by Dr. Karin (University of California, ... more ... hygro (Invitrogen). Flag-IKKβ and IKKα were provided by Dr. Karin (University of California, San Diego, CA). HA-IKKβ and HA-IKKα were provided by Dr. Zandi (University of South California, Los Angeles, CA). Mutant HA-IKKα ...

Therapy of B-cell chronic lymphocytic leukemia (CLL) has been limited by both the nonselectivity ... more Therapy of B-cell chronic lymphocytic leukemia (CLL) has been limited by both the nonselectivity of therapeutic agents toward normal residual immune cells and inherent drug resistance. Identification of agents that spare normal immune effector cells, thus facilitating addition of immune-based therapies, and that modulate factors associated with drug resistance in CLL might represent a major therapeutic advance. Depsipeptide (FR901228) is a novel agent entering clinical trials that has selective in vitro activity against resistant leukemia cell lines. To assess its in vitro activity in CLL, we exposed peripheral mononuclear cells from CLL patients (n = 10) to varying concentrations of this agent. Viability of the CLL cells was reduced by 50% (LC(50)) at 4 hours, 24 hours, and 4 days at depsipeptide concentrations of 0.038, 0.024, and 0.015 micromol/L, respectively. Depsipeptide had marked selective cytotoxicity when compared with normal blood mononuclear cells, in which the LC(50) was 3.44 micromol/L at 4 hours (P =.03), 0.965 micromol/L at 24 hours (P =.01), and 0.0318 micromol/L at 96 hours (P =.04). Inhibition of bone marrow progenitor cell growth was also minimal after incubation with 0.015 micromol/L (19% inhibition of colony forming unit-granulocyte-macrophage [CFU-GM]; 17% inhibition burst forming unit-erythroid [BFU-E]) and 3.44 micromol/L (24% inhibition of CFU-GM; 57% inhibition BFU-E) of depsipeptide for 4 hours, followed by a 14-day incubation period. Expression of apoptotic proteins after depsipeptide exposure (0.015 micromol/L) included no change in bcl-2, elevation of bax, and decreased expression of p27. These data demonstrate that depsipeptide has significant selective in vitro activity against human CLL cells concurrent with favorable alterations of the bcl-2:bax protein ratio and decrease in p27 expression. Such findings strongly support the early introduction of depsipeptide into clinical trials for patients with CLL.

Drug Resistance Updates, 2004

Cancer Research

Gene therapy of B16 tumors with a dominant-negative signal transducer and activator of transcript... more Gene therapy of B16 tumors with a dominant-negative signal transducer and activator of transcription (Stat3) variant, designated Stat3␤, results in inhibition of tumor growth and tumor regression. Although only 10 -15% of the tumor cells are transfected in vivo, the Stat3␤-induced antitumor effect is associated with massive apoptosis of B16 tumor cells, indicative of a potent bystander effect. Here, we provide evidence that blocking Stat3 signaling in B16 cells results in release of soluble factors that are capable of inducing apoptosis and cell cycle arrest of nontransfected B16 cells. RNase protection assays using multi-template probes specific for key physiological regulators of apoptosis reveal that overexpression of Stat3␤ in B16 tumor cells induces the expression of the apoptotic effector, tumor necrosis factor-related apoptosis-inducing ligand. These in vitro results suggest that the observed in vivo bystander effect leading to tumor cell growth inhibition is mediated, at least in part, by soluble factors produced as a result of overexpression of Stat3␤ in tumor cells.

Cancer Research

Activation of the nuclear factor (NF)-KB transcription factor is instru mental for the immune res... more Activation of the nuclear factor (NF)-KB transcription factor is instru mental for the immune response and the survival of peripheral activated T cells. We demonstrate that ligation of CD95 (Fas/APOl), a potent apoptotic stimulus in lymphocytes, results in repression of NF-KB activity in Jurkat T cells by inducing the proteolytic cleavage of NF-KB p65 (Rei A) and p50. Inhibition of caspase-3-related proteases by a specific acetylated aldehyde (Ac-DEVD-CHO) prevented CD95-induced cleavage of p65 (RelA) or p50 and restored the inducibility of NF-KB in cells treated with an antibody against CD95. The addition of recombinant caspase-3 also resulted in proteolytic cleavage of RelA p65 and p50 in vitro. INI-« treatment, unlike CD95 ligation, did not result in the death of Jurkat cells but did so in the presence of Ih-HuM. a transdominant inhibitor of NF-KB. These results suggest that intact, functional NF-KB maintains the survival of activated T cells, and that CD95-induced cleavage of NF-KB subunits sensitizes T cells to apoptosis and, hence, facilitates the decay of an immune response.

Genes & Development

The switch to an angiogenic phenotype is a fundamental determinant of neoplastic growth and tumor... more The switch to an angiogenic phenotype is a fundamental determinant of neoplastic growth and tumor progression. We demonstrate that homozygous deletion of the p53 tumor suppressor gene via homologous recombination in a human cancer cell line promotes the neovascularization and growth of tumor xenografts in nude mice. We find that p53 promotes Mdm2-mediated ubiquitination and proteasomal degradation of the HIF-1␣ subunit of hypoxia-inducible factor 1 (HIF-1), a heterodimeric transcription factor that regulates cellular energy metabolism and angiogenesis in response to oxygen deprivation.

Nature communications, 2015

Lungs resected for adenocarcinomas often harbour minute discrete foci of cytologically atypical p... more Lungs resected for adenocarcinomas often harbour minute discrete foci of cytologically atypical pneumocyte proliferations designated as atypical adenomatous hyperplasia (AAH). Evidence suggests that AAH represents an initial step in the progression to adenocarcinoma in situ (AIS), minimally invasive adenocarcinoma (MIA) and fully invasive adenocarcinoma. Despite efforts to identify predictive markers of malignant transformation, alterations driving this progression are poorly understood. Here we perform targeted next-generation sequencing on multifocal AAHs and different zones of histologic progression within AISs and MIAs. Multiregion sequencing demonstrated different genetic drivers within the same tumour and reveal that clonal expansion is an early event of tumorigenesis. We find that KRAS, TP53 and EGFR mutations are indicators of malignant transition. Utilizing droplet digital PCR, we find alterations associated with early neoplasms in paired circulating DNA. This study provide...

Science

Caspases are a family of cysteine proteases implicated in the biochemical and morphological chang... more Caspases are a family of cysteine proteases implicated in the biochemical and morphological changes that occur during apoptosis (programmed cell death). The loop domain of Bcl-2 is cleaved at Asp34 by caspase-3 (CPP32) in vitro, in cells overexpressing caspase-3, and after induction of apoptosis by Fas ligation and interleukin-3 withdrawal. The carboxyl-terminal Bcl-2 cleavage product triggered cell death and accelerated Sindbis virus-induced apoptosis, which was dependent on the BH3 homology and transmembrane domains of Bcl-2. Inhibitor studies indicated that cleavage of Bcl-2 may further activate downstream caspases and contribute to amplification of the caspase cascade. Cleavage-resistant mutants of Bcl-2 had increased protection from interleukin-3 withdrawal and Sindbis virus-induced apoptosis. Thus, cleavage of Bcl-2 by caspases may ensure the inevitability of cell death.

The HER-2/neu receptor is a member of the epidermal growth factor family and is amplified in mult... more The HER-2/neu receptor is a member of the epidermal growth factor family and is amplified in multiple cancers. It is under intense investiga- tion both as a prognostic marker and for therapy, using monoclonal antibodies targeted against the receptor. We have developed a novel two-component gadolinium-based MR contrast agent to image the HER- 2/neu receptor. Positive T1 contrast in MR