Robert Newman - Academia.edu (original) (raw)

Papers by Robert Newman

PubMed, Dec 15, 2000

We previously found (I. Shureiqi et al., Carcinogenesis (Lond.), 20: 1985-1995, 1999; I. Shureiqi... more We previously found (I. Shureiqi et al., Carcinogenesis (Lond.), 20: 1985-1995, 1999; I. Shureiqi et al, J. Natl. Cancer Inst., 92: 1136-1142, 2000) that (a) 15-lipoxygenase-1 (15-LOX-1) protein and its product 13-S-hydroxyoctadecadienoic acid (13-S-HODE) are decreased; and (b) nonsteroidal anti-inflammatory drug (NSAID)-induced 15-LOX-1 expression is critical to NSAID-induced apoptosis in colorectal cancer cells expressing cyclooxygenase-2 (COX-2). We used the NSAIDs sulindac sulfone (COX-2-independent) and NS-398 (a COX-2 inhibitor) to assess NSAID upregulation of 15-LOX-1 in relation to COX-2 inhibition during NSAID-induced apoptosis in the DLD-1 (COX-2-negative) colon cancer cell line. We found that: (a) NSAIDs up-regulated 15-LOX-1, which preceded apoptosis; and (b) 15-LOX-1 inhibition blocked NSAID-induced apoptosis, which was restored by 13-S-HODE but not by its parent, linoleic acid. NSAIDs can induce apoptosis in colon cancer cells via up-regulation of 15-LOX-1 in the absence of COX-2.

Biomedicine & Pharmacotherapy, 2021

With continued expansion of the coronavirus disease (COVID-19) pandemic, caused by severe acute r... more With continued expansion of the coronavirus disease (COVID-19) pandemic, caused by severe acute respiratory syndrome 2 (SARS-CoV-2), both antiviral drugs as well as effective vaccines are desperately needed to treat patients at high risk of life-threatening disease. Here, we present in vitro evidence for significant inhibition of SARS-CoV-2 by oleandrin and a defined extract of N. oleander (designated as PBI-06150). Using Vero cells, we found that prophylactic (pre-infection) oleandrin (as either the pure compound or as the active principal ingredient in PBI-06150) administration at concentrations as low as 0.05 µg/ml exhibited potent antiviral activity against SARS-CoV-2, with an 800-fold reduction in virus production, and a 0.1 µg/ml concentration resulted in a greater than 3000-fold reduction in infectious virus production. The half maximal effective concentration (EC 50) values were 11.98 ng/ml when virus output was measured at 24 h post-infection, and 7.07 ng/ ml measured at 48 h post-infection. Therapeutic (post-infection) treatment up to 24 h after SARS-CoV-2 infection of Vero cells also reduced viral titers, with 0.1 µg/ml and 0.05 µg/ml concentrations causing greater than 100fold reduction as measured at 48 h, and the 0.05 µg/ml concentration resulting in a 78-fold reduction. Concentrations of oleandrin up to 10 µg/ml were well tolerated in Vero cells. We also present in vivo evidence of the safety and efficacy of defined N. oleander extract (PBI-06150), which was administered to golden Syrian hamsters in a preparation containing as high as 130 µg/ml of oleandrin. In comparison to administration of control vehicle, PBI-06150 provided a statistically significant reduction of the viral titer in the nasal turbinates (nasal conchae). The potent prophylactic and therapeutic antiviral activities demonstrated here, together with initial evidence of its safety and efficacy in a relevant hamster model of COVID-19, support the further development of oleandrin

Journal of Experimental Pharmacology, 2020

Over the past 15 years, investigators have reported on the utility and safety of cardiac glycosid... more Over the past 15 years, investigators have reported on the utility and safety of cardiac glycosides for numerous health benefits including those as treatments for malignant disease, stroke-mediated ischemic injury and certain neurodegenerative diseases. In addition to those, there is a growing body of evidence for novel antiviral effects of selected cardiac glycoside molecules. One unique cardiac glycoside, oleandrin derived from Nerium oleander, has been reported to have antiviral activity specifically against 'enveloped' viruses including HIV and HTLV-1. Importantly, a recent publication has presented in vitro evidence for oleandrin's ability to inhibit production of infectious virus particles when used for treatment prior to, as well as after infection by SARS-CoV-2/COVID-19. This review will highlight the known in vitro antiviral effects of oleandrin as well as present previously unpublished effects of this novel cardiac glycoside against Ebola virus, Cytomegalovirus, and Herpes simplex viruses.

Clinical Cancer Research, Jul 15, 2008

Pancreatic cancer is almost always lethal, and the only U.S. Food and Drug Administration^approve... more Pancreatic cancer is almost always lethal, and the only U.S. Food and Drug Administration^approved therapies for it, gemcitabine and erlotinib, produce objective responses in <10% of patients.We evaluated the clinical biological effects of curcumin (diferuloylmethane), a plant-derived dietary ingredient with potent nuclear factor-nB (NF-nB) and tumor inhibitory properties, against advanced pancreatic cancer. Experimental Design: Patients received 8 g curcumin by mouth daily until disease progression, with restaging every 2 months. Serum cytokine levels for interleukin (IL)-6, IL-8, IL-10, and IL-1 receptor antagonists and peripheral blood mononuclear cell expression of NF-nB and cyclooxygenase-2 were monitored. Results:Twenty-five patients were enrolled, with 21evaluable for response. Circulating curcumin was detectable as drug in glucuronide and sulfate conjugate forms, albeit at low steady-state levels, suggesting poor oral bioavailability. Two patients showed clinical biological activity. One had ongoing stable disease for >18 months; interestingly, one additional patient had a brief, but marked, tumor regression (73%) accompanied by significant increases (4-to 35-fold) in serum cytokine levels (IL-6, IL-8, IL-10, and IL-1 receptor antagonists). No toxicities were observed. Curcumin down-regulated expression of NF-nB, cyclooxygenase-2, and phosphorylated signal transducer and activator of transcription 3 in peripheral blood mononuclear cells from patients (most of whom had baseline levels considerably higher than those found in healthy volunteers). Whereas there was considerable interpatient variation in plasma curcumin levels, drug levels peaked at 22 to 41ng/mL and remained relatively constant over the first 4 weeks. Conclusions: Oral curcumin is well tolerated and, despite its limited absorption, has biological activity in some patients with pancreatic cancer.

Journal of the National Cancer Institute, Jul 19, 2000

Background: Nonsteroidal anti-inflammatory drugs (NSAIDs) appear to act via induction of apoptosi... more Background: Nonsteroidal anti-inflammatory drugs (NSAIDs) appear to act via induction of apoptosisprogrammed cell death-as potential colorectal cancer chemopreventive agents. NSAIDs can alter the production of different metabolites of polyunsaturated fatty acids (linoleic and arachidonic acids) through effects on lipoxygenases (LOXs) and cyclooxygenases. 15-LOX-1 is the main enzyme f o r m e t a b o l i z i n g c o l o n i c l i n o l e i c a c i d t o 1 3-Shydroxyoctadecadienoic acid (13-S-HODE), which induces apoptosis. In human colorectal cancers, the expression of this enzyme is reduced. NSAIDs can increase 15-LOX enzymatic activity in normal leukocytes, but their effects on 15-LOX in neoplastic cells have been unknown. We tested the hypothesis that NSAIDs induce apoptosis in colorectal cancer cells by increasing the protein expression and enzymatic activity of 15-LOX-1. Methods: We assessed 15-LOX-1 protein expression and enzymatic activity, 13-S-HODE levels, and 15-LOX-1 inhibition in association with cellular growth inhibition and apoptosis induced by NSAIDs (primarily sulindac and NS-398) in two colorectal cancer cell lines (RKO and HT-29). All P values are two-sided. Results: Sulindac and NS-398 progressively increased 15-LOX-1 protein expression in RKO cells (at 24, 48, and 72 hours) in association with subsequent growth inhibition and apoptosis. Increased 13-S-HODE levels and the formation of 15-hydroxyeicosatetraenoic acid on incubation of the cells with the substrate arachidonic acid confirmed the enzymatic activity of 15-LOX-1. Inhibition of 15-LOX-1 in RKO cells by treatment with caffeic acid blocked NS-398-induced 13-S-HODE production, cellular growth inhibition, and apoptosis (P = .007, P<.0001, and P<.0001, respectively); growth inhibition and apoptosis were restored by adding exogenous 13-S-HODE (P<.0001 for each) but not its parent compound, linoleic acid (P = 1.0 for each). Similar results occurred with other NSAIDs and in HT-29 cells. Conclusions: These data identify 15-LOX-1 as a novel molecular target of NSAIDs for inducing apoptosis in colorectal carcinogenesis. [

Sweet gum (Liquidambar styraciflua L., family Hamamelidaceae) fruit extract was discovered to pos... more Sweet gum (Liquidambar styraciflua L., family Hamamelidaceae) fruit extract was discovered to possess potent ac tivities against multiple targets of the PBK (phosphatidylinositide 3-kinase) pathway, especially the PI3K/Akt and mTOR pathways. At a very low concentration of 1.85 µg/ml (IC50), sweet gun extract showed the ability of simultaneously blocking the pathways of PI3K/Akt (upstream), mTOR (mammalian target of rapamycin) (downstream), as well as its downstream protein products S6K and S6. It was also able to block 5-HETE, a lipoxygenase product that contributes to inflammation and activation of PI3K/Akt. The sweet gum fruit extract was prepared with 50% methanol (47: 1; raw to extract) and concentrated to an organic fraction (210: 1 raw to extract) referred as LIS-100 via reverse-phase column chromatography using a bioassay directed fractionation approach. The extract is a new targeted therapeutic agent for numerous disorders known to be treated by mTOR inhibitors, including cancer, diabetes, obesity, and inflammation.

The Prostate, 2003

Branched-chain fatty acids or fatty alcohols have been reported to possess anti-tumor activity in... more Branched-chain fatty acids or fatty alcohols have been reported to possess anti-tumor activity in various tumor models. Here we study 12-methyltetradecanoic acid (12-MTA), a branched-chain fatty acid, isolated from a sea cucumber extract, on the growth of prostate cancer cells and investigate the underlying mechanisms of its effect. 12-MTA was evaluated by MTT assay for its ability to inhibit cell proliferation in various cancer types. The ability of 12-MTA to induce apoptosis of PC3 cells was examined by morphologic changes, propidium iodide (PI) staining, and caspase-3 activation. Furthermore, alteration of eicosanoid metabolism by 12-MTA was examined in PC3 and RBL-1 cells and in purified lipoxygenase (LOX) and cyclooxygenase (COX) enzymes. 12-MTA inhibited proliferation of various cell lines, with IC50s ranging from 17.99 to 35.44 microg/ml. PI staining clearly showed that 12-MTA caused PC3 cell death through induction of apoptosis. At 50 microg/ml, 12-MTA increased caspase-3 activity four to seven-fold compared with that in control cells. Examination of cellular arachidonate metabolism showed that at 25 microg/ml, 12-MTA reduced the level of 5-hydroxyeicosatetraenoic acid (5-HETE) by 45%. Furthermore, exogenous 5-HETE protects PC3 cells from 12-MTA induced cell death. 12-MTA inhibited proliferation of cancer cells via apoptosis, in which caspase-3 may play a role. At relevant concentrations, 12-MTA can selectively inhibit the formation of 5-HETE, a metabolite of 5-lipoxygenase. This agent may be a novel adjunctive therapy for selected malignancies including prostate cancer.

Free Radical Biol Med, 2011

Fifth AACR International Conference on Frontiers in Cancer Prevention Research, Nov 12-15, 2006 A... more Fifth AACR International Conference on Frontiers in Cancer Prevention Research, Nov 12-15, 2006 A80 We continue to explore extracts and pure molecules derived from the holothurian (sea cucumber) Cucumaria frondosa . With support from the NCI's RAPID Program, we investigated Frondanol® A5, for indications of therapeutic and preventive effects against cancer. We have shown that Frondanol A5 and its glycoside components inhibit growth of pancreatic cancer cells through induction of apoptosis. Research indicated that Frondanol® A5 mediated cell death was associated with an increase in p-21Cip1, phosphorylation of p38 kinase, and triggered the apoptotic caspase cascade. Isolated crude glycosides from Frondanol A5 were found to inhibit COX-1 and COX-2 in a conc.-dependent manner, while the non-saponifiable fraction from Frondanol® A5 exhibited strong inhibition of the 5-lipoxygenase pathway. We have also previously shown that glycosides of Frondanol® A5 appear to block the G-coupled prostaglandin EP-1 receptor and show an inhibitory activity in an arachidonic acid-induced mouse ear inflammation model. We now show that in a DMBA Mouse Mammary Organ Culture assay, Frondanol A5 inhibits development of breast cancer ductal lesions by 75% using very low drug conc. In the B[ a ]P-induced Rat Tracheal Epithelial foci inhibition assay, Frondanol® A5 significantly inhibited (86.4% decrease) transformation at 0.3 u g/ml. A 98% pure glycoside component of Frondanol® A5, designated Frondoside A, inhibited microtubule formation by 88% (at 1 u M) in a HUVEC based angiogenesis assay. Pure Frondoside A has also been shown to have immunomodulatory effects. Frondoside A, was injected subcutaneously to Staph. aureus infected mice. Saline controls showed 10% survival, while Frondoside A treated mice showed 40% survival which was considered to be a significant survival improvement in this difficult test. Finally, microarray analyses of the effect of Frondoside A in the pancreatic cancer cell line S2-013 has shown increased expression of anti-oxidant genes associated with modulation of free radical damage (SOD and AKR1C1) and down-regulation of several pro-inflammatory genes and genes involved in cyclin dependent kinase pathways. Our data thus indicate the multi-mechanistic potential of Frondanol® A5 and its subcomponent glycoside Frondoside A as potentially useful novel chemopreventive agents. As a popular Oriental delicacy for more than 1,000 years, we suggest that sea cucumber glycosidic compounds are a safe cancer nutrapreventive food supplement with pronounced beneficial effects in biochemical and genomic pathways now known to contribute to cancer initiation, progression and metastatic pathology. This has been supported by the National Cancer Institute, Division of Chemoprevention RAPID Program, American Institute for Cancer Research, Maine Technology Institute and the Russian Academy of Science in Vladivostok, Russia.

Annals of the New York Academy of Sciences, 2008

Pancreatic cancer cells are resistant to the growth-inhibitory and apoptosis-inducing effects of ... more Pancreatic cancer cells are resistant to the growth-inhibitory and apoptosis-inducing effects of conventional chemotherapeutic agents. There are multiple genetic and epigenetic events during the process of carcinogenesis that enable the cancer cells to avoid normal growth constraints and apoptosis. Investigation of the mechanisms involved has led to multiple strategies that encourage cell death and apoptosis to occur. The pathways involved are summarized in this review, together with some recently developed strategies to promote cell death in this cancer and with a particular focus on the frondoside A, a novel triterpenoid glycoside isolated from the Atlantic sea cucumber, Cucumaria frondosa. Frondoside A inhibited proliferation of AsPC-1 human pancreatic cancer cells in a concentration-and time-dependent manner, as measured by 3 H-thymidine incorporation and cell counting. In concert with inhibition of cell growth, frondoside A induced significant morphological changes consistent with apoptosis. Propidium iodide DNA staining showed an increase of sub-G0/G1 cell population of apoptotic cells induced by frondoside A. Frondoside A-induced apoptosis was confirmed by annexin V binding and TUNEL assay. Furthermore, western blotting showed a decrease in expression of Bcl-2 and Mcl-1, an increase in Bax expression, activation of caspases 3, 7, and 9, and an increase in the expression of the cyclin-dependent kinase inhibitor, p21. These findings show that frondoside A induced apoptosis in human pancreatic cancer cells through the mitochondrial pathway and activation of the caspase cascade. Finally, a very low concentration of frondoside A (10 μg/kg/day) inhibited growth of AsPC-1 xenografts in athymic mice. In conclusion, new chemotherapeutic agents are desperately needed for pancreatic cancer because of the poor responsiveness to currently available treatment options. Frondoside A has potent growth inhibitory effects on human pancreatic cancer cells, and the inhibition of proliferation is accompanied by marked

Cancer Research, 2001

We previously found (I.

Marine drugs, Jan 17, 2016

The frondosides are triterpenoid glycosides from the Atlantic sea cucumber Cucumaria frondosa. Fr... more The frondosides are triterpenoid glycosides from the Atlantic sea cucumber Cucumaria frondosa. Frondoside A inhibits growth, invasion, metastases and angiogenesis and induces apoptosis in diverse cancer types, including pancreatic cancer. We compared the growth inhibitory effects of three frondosides and their aglycone and related this to the pharmocokinetics and route of administration. Frondoside A potently inhibited growth of pancreatic cancer cells with an EC50 of ~1 µM. Frondoside B was less potent (EC50 ~2.5 µM). Frondoside C and the aglycone had no effect. At 100 µg/kg, frondoside A administered to CD₂F₁ mice as an i.v. bolus, the Cpmax was 129 nM, Cltb was 6.35 mL/min/m², and half-life was 510 min. With i.p. administration the Cpmax was 18.3 nM, Cltb was 127 mL/min/m² and half-life was 840 min. Oral dosing was ineffective. Frondoside A (100 µg/kg/day i.p.) markedly inhibited growth cancer xenografts in nude mice. The same dose delivered by oral gavage had no effect. No evide...

Journal of Pharmaceutical and Biomedical Analysis, 1994

Peplomycin, an antitumour antibiotic analogue of bleomycin, was measured in mouse tissues using a... more Peplomycin, an antitumour antibiotic analogue of bleomycin, was measured in mouse tissues using a rapid radioimmunoassay. Antiserum, obtained by immunizing rabbits with peplomycin-bovine serum albumin conjugate, showed no significant cross-reactivity with the closely related peplomycin analogues bleomycin and liblomycin, nor with a number of other structurally unrelated antitumour drugs. The assay is sensitive and can detect peplomycin levels as low as 2 ng ml-1. The relative intra- and inter-assay standard deviation is < or = 5%, indicating good assay reproducibility. Peplomycin levels in mouse tissues were easily determined without extraction. Fifteen minutes after administration of a single intraperitoneal dose of peplomycin at 8.5 mg kg-1 (1/10 of LD50), high drug levels were found in plasma (46 micrograms ml-1), kidneys (38 micrograms g-1), urine and bladder (32 micrograms ml-1), followed by gastrointestinal tract (13 micrograms g-1), lung (8 micrograms g-1), spleen (3.7 micrograms g-1), heart (3.6 micrograms g-1), gall bladder (2.7 micrograms g-1), liver (2 micrograms g-1), and brain (0.6 microgram g-1). The total amount of drug in all these organs accounted for more than 80% of the dose administered. We conclude that the radioimmunoassay is sensitive and reproducible and is an ideal tool for measuring peplomycin in tissues and biofluids for pharmacological studies.

Molecular Cancer Therapeutics - MOL CANCER THER, 2007

The marine ecosystem is a vast but largely untapped resource for potential naturally based medici... more The marine ecosystem is a vast but largely untapped resource for potential naturally based medicines. We tested 15 compounds derived from organisms found in the Caribbean Sea (14 gorgonian octocoral-derived compounds and one sponge-derived compound) for their anticancer effects on human malignant glioma U87-MG and U373-MG cells. Eupalmerin acetate (EPA) was chosen as the lead compound based on its longer-term stability and greater cytotoxicity than those of the other compounds we tested in these cell types. EPA induced G 2-M cell cycle arrest and apoptosis via the mitochondrial pathway; it translocated Bax from the cytoplasm to the mitochondria and dissipated the mitochondrial transmembrane potential in both cell types. EPA was found to increase phosphorylated c-Jun NH 2-terminal kinase (JNK) by >50% in both U87-MG and U373-MG cells. A specific JNK inhibitor, SP600125, inhibited EPA-induced apoptosis, confirming the involvement of the JNK pathway in EPA-induced apoptotic cell death. Furthermore, 7 days of daily intratumoral injections of EPA significantly suppressed the growth of s.c. malignant glioma xenografts (P < 0.01, on day 19). These results indicate that EPA is therapeutically effective against malignant glioma cells in vitro and in vivo and that it, or a similar marine-based compound, may hold promise as a clinical anticancer agent.

Clinical, cosmetic and investigational dermatology, 2016

To evaluate a blend of two natural ingredients on immune parameters relevant for their current to... more To evaluate a blend of two natural ingredients on immune parameters relevant for their current topical use and potential support of microcirculation in skin tissue. A blend (BL) of Aloe vera-based Nerium oleander extract (NAE-8i, oleandrin-free) and hydrolyzed water-soluble egg membrane (WSEM) was applied to human whole-blood cultures for 24 hours, with each separate ingredient serving as a control. Immune-cell subsets were analyzed for expression levels of the activation markers CD69 and CD25. Culture supernatants were analyzed for cytokines, chemokines, and immunoregulating peptides. BL increased CD69 expression on lymphocytes, monocytes, and CD3(-)CD56(+) natural killer cells, and CD25 expression on natural killer cells. The number of CD69(+)CD25(+) lymphocytes increased in cultures treated with BL and the separate ingredients. BL triggered production of multiple cytokines and chemokines, where CC chemokines MIP1α and MIP3α, as well as cytokines involved in wound healing - Groα, ...

Cardiac glycosides such as digitoxin and ouabain have previously been shown to be selectively cyt... more Cardiac glycosides such as digitoxin and ouabain have previously been shown to be selectively cytotoxic to tumor as opposed to normal cells. Moreover, this class of agents has also been shown to act as potent radiosensitizers. In the present study we explored the relative radiosensitization potential of oleandrin, a cardiac glycoside contained within the plant extract known as Anvirzele that

Scientific reports, May 12, 2016

We previously reported neuroprotective activity of the botanical anti-cancer drug candidate PBI-0... more We previously reported neuroprotective activity of the botanical anti-cancer drug candidate PBI-05204, a supercritical CO2 extract of Nerium oleander, in brain slice and in vivo models of ischemic stroke. We showed that one component of this neuroprotective activity is mediated through its principal cardiac glycoside constituent, oleandrin, via induction of the potent neurotrophic factor brain-derived neurotrophic factor (BDNF). However, we also noted that the concentration-relation for PBI-05204 in the brain slice oxygen-glucose deprivation (OGD) model is considerably broader than that for oleandrin as a single agent. We thus surmised that PBI-05204 contains an additional neuroprotective component(s), distinct from oleandrin. We report here that neuroprotective activity is also provided by the triterpenoid constituents of PBI-05204, notably oleanolic acid. We demonstrate that a sub-fraction of PBI-05204 (Fraction 0-4) containing oleanolic and other triterpenoids, but without cardia...

Research communications in chemical pathology and pharmacology, 1990

LY195448(R) (a phenethanolamine derivative that has demonstrated cytotoxic activity against cell ... more LY195448(R) (a phenethanolamine derivative that has demonstrated cytotoxic activity against cell cultures in vitro but that exhibited a hypotensive side effect during phase I trials), its p-hydroxy and acid metabolites, and a noncytotoxic S-stereoisomer were evaluated with respect to competitive binding against the beta-adrenergic antagonist [3H]dihydroalprenolol in rat brain cortex and human cardiac tissues. When IC50 and Ki values were compared, the R-isomer of LY195448 in general was more potent than the S-stereoisomer. While LY195448(R) was about 10-fold more active than the p-hydroxy metabolite in cardiac tissues, the two compounds were nearly equipotent both in blocking the binding of radioligand to the brain and in reducing blood pressure in rats. In the cerebral preparation, the binding of the acid metabolite was weak, with its activity being equal to that of the S-stereoisomer.

Clinical, cosmetic and investigational dermatology, 2015

The goal for this study was to evaluate the effects of an Aloe vera-based Nerium oleander extract... more The goal for this study was to evaluate the effects of an Aloe vera-based Nerium oleander extract (NAE-8(®)), compared to an extract of A. vera gel alone (ALOE), and to an aqueous extract of N. oleander (AQ-NOE) in bioassays pertaining to dermatologic potential with respect to antioxidant protection, anti-inflammatory effects, and cytokine profiles in vitro. Cellular antioxidant protection was evaluated in three separate bioassays: The cellular antioxidant protection of erythrocytes (CAP-e) assay, protection of cellular viability and prevention of apoptosis, and protection of intracellular reduced glutathione levels, where the last two assays were performed using human primary dermal fibroblasts. Reduction of intracellular formation of reactive oxygen species (ROS) was tested using polymorphonuclear cells in the absence and presence of oxidative stress. Changes to cytokine and chemokine profiles when whole blood cells and human primary dermal fibroblasts were exposed to test product...