Pratibha V. Nerurkar

Well-done red meat, metabolic phenotypes and colorectal cancer in Hawaii.

Heterocyclic amines (HAAs) and polycyclic hydrocarbons are suspected colorectal cancer (CRC) carcinogens that are found in well-done meat. They require metabolic activation by phase I enzymes, such as the smoking-inducible CYP1A isoenzymes. N-acetyltransferase 2 (NAT2) also play a role in the further activation of HAAs. We conducted a population-based case-control study in Hawaii to test the associations of preference for well-done red meat and HAA intake with colon and rectal cancers, as well as the modifying effects of NAT2 and CYP1A2. We interviewed 727 Japanese, Caucasian or Native Hawaiian cases and 727 controls matched on sex, age, and ethnicity. HAA intake was estimated based on consumption of meat and fish for each of several cooking methods and doneness levels. A subgroup of 349 cases and 467 controls was phenotyped for CYP1A2 by a caffeine test. We found that preference for well-done red meat was associated with a 8.8-fold increased risk of CRC (95% CI: 1.7-44.9) among ever-smokers with the NAT2 and CYP1A2 rapid phenotypes, compared to ever-smokers with low NAT2 and CYP1A2 activities and who preferred their red meat rare or medium. A dose-dependent association was also found between the HAA intake estimates and male rectal cancer, with a two- to three-fold increase in risk from the low (T(1)) to high (T(3)) tertile of intake for each HAA. This association was strongest for MeIQx. HAA intake was not associated with male colon cancer or colon or rectal cancer in women. These data provide support to the hypothesis that exposure to pyrolysis products through consumption of well-done meat increases the risk of CRC, particularly in individuals who smoke and are genetically susceptible (as determined by a rapid phenotype for both NAT2 and CYP1A2). An attempt to examine the risk associated with specific HAAs suggested that the main HAAs increase risk of rectal cancer in men and that they do not appreciably affect risk of rectal cancer in women or of colon cancer in either sex.

Bitter Melon (Momordica charantia) Extract Inhibits Breast Cancer Cell Proliferation by Modulating Cell Cycle Regulatory Genes and Promotes Apoptosis

Breast cancer is one of the most common cancers among women in the United States. Although there are effective drugs for treating advanced stages of breast cancers, women eventually develop resistance. One of the approaches to control breast cancer is prevention through diet, which inhibits one or more neoplastic events and reduces cancer risk. In this study, we have used human breast cancer cells, MCF-7 and MDA-MB-231, and primary human mammary epithelial cells as an in vitro model to assess the efficacy of bitter melon (Momordica charantia) extract (BME) as an anticancer agent. BME treatment of breast cancer cells resulted in a significant decrease in cell proliferation and induced apoptotic cell death. Apoptosis of breast cancer cells was accompanied by increased poly(ADP-ribose) polymerase cleavage and caspase activation. Subsequent studies showed that BME treatment of breast cancer cells inhibited survivin and claspin expression. Fluorescence-activated cell sorting analysis suggested that MCF-7 cells treated with BME accumulated during the G2-M phase of the cell cycle. Further studies revealed that BME treatment enhanced p53, p21, and pChk1/2 and inhibited cyclin B1 and cyclin D1 expression, suggesting an additional mechanism involving cell cycle regulation. Together, these results show that BME modulates signal transduction pathways for inhibition of breast cancer cell growth and can be used as a dietary supplement for prevention of breast cancer.

Momordica charantia (bitter melon) attenuates high-fat diet-associated oxidative stress and neuroinflammation

BackgroundThe rising epidemic of obesity is associated with cognitive decline and is considered as one of the major risk factors for neurodegenerative diseases. Neuroinflammation is a critical component in the progression of several neurological and neurodegenerative diseases. Increased metabolic flux to the brain during overnutrition and obesity can orchestrate stress response, blood-brain barrier (BBB) disruption, recruitment of inflammatory immune cells from peripheral blood and microglial cells activation leading to neuroinflammation. The lack of an effective treatment for obesity-associated brain dysfunction may have far-reaching public health ramifications, urgently necessitating the identification of appropriate preventive and therapeutic strategies. The objective of our study was to investigate the neuroprotective effects of Momordica charantia (bitter melon) on high-fat diet (HFD)-associated BBB disruption, stress and neuroinflammatory cytokines.MethodsC57BL/6 female mice were fed HFD with and without bitter melon (BM) for 16 weeks. BBB disruption was analyzed using Evans blue dye. Phosphate-buffered saline (PBS) perfused brains were analyzed for neuroinflammatory markers such as interleukin-22 (IL-22), IL-17R, IL-16, NF-κB1, and glial cells activation markers such as Iba1, CD11b, GFAP and S100β. Additionally, antioxidant enzymes, ER-stress proteins, and stress-resistant transcription factors, sirtuin 1 (Sirt1) and forkhead box class O transcription factor (FoxO) were analyzed using microarray, quantitative real-time RT-PCR, western immunoblotting and enzymatic assays. Systemic inflammation was analyzed using cytokine antibody array.ResultsBM ameliorated HFD-associated changes in BBB permeability as evident by reduced leakage of Evans blue dye. HFD-induced glial cells activation and expression of neuroinflammatory markers such as NF-κB1, IL-16, IL-22 as well as IL-17R were normalized in the brains of mice supplemented with BM. Similarly, HFD-induced brain oxidative stress was significantly reduced by BM supplementation with a concomitant reduction in FoxO, normalization of Sirt1 protein expression and up-regulation of Sirt3 mRNA expression. Furthermore, plasma antioxidant enzymes and pro-inflammatory cytokines were also normalized in mice fed HFD with BM as compared to HFD-fed mice.ConclusionsFunctional foods such as BM offer a unique therapeutic strategy to improve obesity-associated peripheral inflammation and neuroinflammation.

Bitter melon: antagonist to cancer.

ABSTRACTThe incidence of cancer is increasing worldwide, in spite of substantial progress in the development of anti-cancer therapies. One approach to control cancer could be its prevention by diet, which inhibits one or more neoplastic events and reduces cancer risk. Dietary compounds offer great potential in the fight against cancer by inhibiting the carcinogenesis process through the regulation of cell homeostasis and cell-death machineries. For centuries, Ayurveda (Indian traditional medicine) has recommended the use of bitter melon (Momordica charantia) as a functional food to prevent and treat diabetes and associated complications. It is noteworthy to mention that bitter melon extract has no-to-low side effects in animals as well as in humans. The anti-tumor activity of bitter melon has recently begun to emerge. This review focuses on recent advancements in cancer chemopreventive and anti-cancer efficacy of bitter melon and its active constituents. Several groups of investigators have reported that treatment of bitter-melon-related products in a number of cancer cell lines induces cell cycle arrest and apoptosis without affecting normal cell growth. Therefore, the effect of bitter melon should be beneficial for health, and use of the non-modified dietary product is cost effective.

Momordica charantia (bitter melon) inhibits primary human adipocyte differentiation by modulating adipogenic genes

BackgroundEscalating trends of obesity and associated type 2 diabetes (T2D) has prompted an increase in the use of alternative and complementary functional foods. Momordica charantia or bitter melon (BM) that is traditionally used to treat diabetes and complications has been demonstrated to alleviate hyperglycemia as well as reduce adiposity in rodents. However, its effects on human adipocytes remain unknown. The objective of our study was to investigate the effects of BM juice (BMJ) on lipid accumulation and adipocyte differentiation transcription factors in primary human differentiating preadipocytes and adipocytes.MethodsCommercially available cryopreserved primary human preadipocytes were treated with and without BMJ during and after differentiation. Cytotoxicity, lipid accumulation, and adipogenic genes mRNA expression was measured by commercial enzymatic assay kits and semi-quantitative RT-PCR (RT-PCR).ResultsPreadipocytes treated with varying concentrations of BMJ during differentiation demonstrated significant reduction in lipid content with a concomitant reduction in mRNA expression of adipocyte transcription factors such as, peroxisome proliferator-associated receptor γ (PPARγ) and sterol regulatory element-binding protein 1c (SREBP-1c) and adipocytokine, resistin. Similarly, adipocytes treated with BMJ for 48 h demonstrated reduced lipid content, perilipin mRNA expression, and increased lipolysis as measured by the release of glycerol.ConclusionOur data suggests that BMJ is a potent inhibitor of lipogenesis and stimulator of lipolysis activity in human adipocytes. BMJ may therefore prove to be an effective complementary or alternative therapy to reduce adipogenesis in humans.

Momordica charantia (bitter melon) reduces plasma apolipoprotein B-100 and increases hepatic insulin receptor substrate and phosphoinositide-3 kinase interactions

Aqueous extracts or juice from unripened fruit of Momordica charantia (bitter melon) has traditionally been used in the treatment of diabetes and its complications. Insulin resistance is characterized by significant down-regulation of hepatic insulin signalling as documented by attenuated phosphorylation of insulin receptor (IR), IR substrates 1 and 2, phosphoinositide-3 kinase, protein kinase B, and over-expression of phosphotyrosine phosphatase 1B. We recently demonstrated that bitter melon juice (BMJ) is a potent inhibitor of apoB secretion and TAG synthesis and secretion in human hepatoma cells, HepG2, that may be involved in plasma lipid- and VLDL-lowering effects observed in animal studies. The aim of this study was to evaluate the effects of BMJ on plasma apoB levels and hepatic insulin signalling cascade in mice fed high-fat diet (HFD). Female C57BL/6 mice (4-6 weeks old) were randomized into three groups receiving regular rodent chow, HFD and HFD+BMJ. The data indicate that BMJ not only improves glucose and insulin tolerance but also lowers plasma apoB-100 and apoB-48 in HFD-fed mice as well as modulates the phosphorylation status of IR and its downstream signalling molecules. Investigating the biochemical and molecular mechanisms involved in amelioration of diabetic dyslipidaemia by BMJ may lead to identification of new molecular targets for dietary/alternative therapies.

Bitter melon extract impairs prostate cancer cell cycle progression and delays prostatic intraepithelial neoplasia in TRAMP model

Prostate cancer remains the second leading cause of cancer deaths among American men. Earlier diagnosis increases survival rate in patients. However, treatments for advanced disease are limited to hormone ablation techniques and palliative care. Thus, new methods of treatment and prevention are necessary for inhibiting disease progression to a hormone refractory state. One of the approaches to control prostate cancer is prevention through diet, which inhibits one or more neoplastic events and reduces the cancer risk. For centuries, Ayurveda has recommended the use of bitter melon (Momordica charantia) as a functional food to prevent and treat human health related issues. In this study, we have initially used human prostate cancer cells, PC3 and LNCaP, as an in vitro model to assess the efficacy of bitter melon extract (BME) as an anticancer agent. We observed that prostate cancer cells treated with BME accumulate during the S phase of the cell cycle and modulate cyclin D1, cyclin E, and p21 expression. Treatment of prostate cancer cells with BME enhanced Bax expression and induced PARP cleavage. Oral gavage of BME, as a dietary compound, delayed the progression to high-grade prostatic intraepithelial neoplasia in TRAMP (transgenic adenocarcinoma of mouse prostate) mice (31%). Prostate tissue from BME-fed mice displayed approximately 51% reduction of proliferating cell nuclear antigen expression. Together, our results suggest for the first time that oral administration of BME inhibits prostate cancer progression in TRAMP mice by interfering cell-cycle progression and proliferation. Cancer Prev Res; 4(12); 2122–30. ©2011 AACR.

Effects of Marinating With Asian Marinades or Western Barbecue Sauce on PhIP and MeIQx Formation in Barbecued Beef

Heterocyclic aromatic amines (HAAs), a group of chemicals formed during high-temperature cooking of meat and fish, are potent mutagens and are suspected to play a role in colorectal cancer. A recent study suggested that marinating meat may offer a way to reduce HAA formation. Hawaiis diverse ethnic populations, which are at various risks of colorectal cancer, often use traditional marinades when cooking meat. We compared the HAA content of beef steaks marinated overnight with teriyaki sauce, turmeric-garlic sauce, or commercial honey barbecue sauce with that of unmarinated steaks. The levels of 2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine (PhIP) and 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) were determined by liquid-liquid extraction and gas chromatography-mass spectrometry. Beef steaks marinated with teriyaki sauce had 45% and 67% lower PhIP level at 10 minutes (p = 0.002) and 15 minutes (p = 0.001) of cooking time as well as 44% and 60% lower MeIQx levels at 10 minutes (p = 0.008) and 15 minutes (p = 0.001), respectively, than unmarinated meat. Lower levels of PhIP and MeIQx were also observed in meat marinated with turmeric-garlic sauce. In contrast, marinating with barbecue sauce caused a 2.9- and 1.9-fold increase in PhIP (p < or = 0.005) and a 4- and 2.9-fold increase in MeIQx (p < or = 0.001) at 10 and 15 minutes, respectively. Differences in the mutagenic activities of marinated and unmarinated steaks, as measured by the Ames assay, paralleled the differences in PhIP and MeIQx levels. Future studies should test the effects of specific ingredients, including the water content of marinades, and the effect of reapplying barbecue sauce during cooking (to reduce charring) on HAA formation.

Lipid lowering effects of Momordica charantia (Bitter Melon) in HIV-1-protease inhibitor-treated human hepatoma cells, HepG2

1 Hyperlipidemic effects of HIV‐1‐protease inhibitors (PI) are associated with increased hepatic production of triglyceride (TG)‐rich lipoproteins, rather than lipoprotein clearance. PI are known to increase apolipoprotein B (apoB) secretion, apoC‐III mRNA expression and decrease apoA‐1 secretion. Nutritional therapy remains an important strategy to manage PI‐associated hyperlipidemia. 2 This study investigated the in vitro efficacy of Asian vegetable, Momordica charantia or bitter melon (BM) to ameliorate PI‐associated apoB and lipid abnormalities in HepG2 cells. 3 Our study demonstrates that bitter melon juice (BMJ) significantly reduced apoB secretion and apoC‐III mRNA expression and normalized apoA‐I expression in PI‐treated HepG2 cells. BMJ also significantly reduced cellular TG and microsomal TG transfer protein, suggesting that lipid bioavailability and lipidation of apoB assembly may play a role in decreased apoB secretion. 4 Identifying molecular targets of BM may offer alternative dietary strategies to decrease PI‐associated hyperlipidemia and improve quality of life among HIV‐1‐infected patients.

Regulation of glucose metabolism via hepatic forkhead transcription factor 1 (FoxO1) by Morinda citrifolia (noni) in high-fat diet-induced obese mice

Renewed interest in alternative medicine among diabetic individuals prompted us to investigate anti-diabetic effects of Morinda citrifolia (noni) in high-fat diet (HFD)-fed mice. Type 2 diabetes is associated with increased glucose production due to the inability of insulin to suppress hepatic gluconeogenesis and promote glycolysis. Insulin inhibits gluconeogenesis by modulating transcription factors such as forkhead box O (FoxO1). Based on microarray analysis data, we tested the hypothesis that fermented noni fruit juice (fNJ) improves glucose metabolism via FoxO1 phosphorylation. C57BL/6 male mice were fed a HFD and fNJ for 12 weeks. Body weights and food intake were monitored daily. FoxO1 expression was analysed by real-time PCR and Western blotting. Specificity of fNJ-associated FoxO1 regulation of gluconeogenesis was confirmed by small interfering RNA (siRNA) studies using human hepatoma cells, HepG2. Supplementation with fNJ inhibited weight gain and improved glucose and insulin tolerance and fasting glucose in HFD-fed mice. Hypoglycaemic properties of fNJ were associated with the inhibition of hepatic FoxO1 mRNA expression, with a concomitant increase in FoxO1 phosphorylation and nuclear expulsion of the proteins. Gluconeogenic genes, phosphoenolpyruvate C kinase (PEPCK) and glucose-6-phosphatase (G6P), were significantly inhibited in mice fed a HFD+fNJ. HepG2 cells demonstrated more than 80 % inhibition of PEPCK and G6P mRNA expression in cells treated with FoxO1 siRNA and fNJ. These data suggest that fNJ improves glucose metabolism via FoxO1 regulation in HFD-fed mice.