Induction of apoptosis in human breast cancer cells by nimbolide through extrinsic and intrinsic pathway.

We aimed to investigate the cytotoxic effects of nimbolide, a limonoid present in leaves and flowers of the neem tree (Azadirachta indica) on human breast cancer cells. The molecular mechanisms involved in the apoptotic activity exerted by nimbolide were studied on the estrogen dependent (MCF-7) and estrogen independent (MDA-MB-231) human breast cancer cell lines. The growth inhibitory effect of nimbolide was assessed by MTT assay. Apoptosis induction by nimbolide treatment was determined by JC-1 mitochondrial membrane potential staining, cytochrome c release, caspase activation, cleavage of PARP and AO/EtBr dual staining. The modulation of apoptotic proteins (intrinsic pathway: Bax, bad, Bcl-2, Bcl-xL, Mcl-1, XIAP-1 and caspase-3, 9; extrinsic pathway: TRAIL, FasL, FADDR and Caspase-8) were studied by western blot and real time PCR analysis. Treatment with nimbolide resulted in dose and time-dependent inhibition of growth of MCF-7 and MDA-MB-231 cells. The occurrence of apoptosis in these cells was indicated by JC-1 staining, modulation of both intrinsic and extrinsic apoptotic signaling molecules expression and further apoptosis was confirmed by AO/EtBr dual staining. These events were associated with: increased levels of proapoptotic proteins Bax, Bad, Fas-L, TRAIL, FADDR, cytochrome c and reduced levels of the anti-apoptotic proteins Bcl-2, Bcl-xL, Mcl-1 and XIAP-1. Nimbolide induces the cleavage of pro-caspase-8, pro-caspase-3 and PARP. The above data suggest that nimbolide induces apoptosis by both the intrinsic and extrinsic pathways. With evidence of above data it is suggested that nimbolide exhibit anticancer effect through its apoptosis-inducing property. Thus, nimbolide raises new hope for its use in anticancer therapy.

Effect of diallyl disulfide on insulin-like growth factor signaling molecules involved in cell survival and proliferation of human prostate cancer cells in vitro and in silico approach through docking analysis.

PURPOSE: Diallyl Disulfide (DADS) is one of the major components of garlic, which inhibits the proliferation of various cancer cells. Our previous studies showed that DADS inhibits cell growth and induces apoptosis on prostate cancer cells. Insulin like growth factor signaling pathway plays a significant role on prostate cancer cell growth and survival and it's over expression also identified in human prostate cancers. The molecular mechanism of IGF mediated PI3K/Akt signaling remains to be elucidated. The present study was designed to evaluate the effects of diallyl disulfide on IGF signaling in androgen independent prostate cancer cells (PC-3). METHODS: DADS (10-50 µM) caused dose-dependent inhibition of PC-3 cells, were analyzed by MTT, IC50 value of PC-3 cells was 40 µM for 24h. Interestingly, DADS also altered the mRNA and protein expressions of IGF signaling and apoptotic molecules which were confirmed by semi quantitative PCR and western blot method. Further the docking study of DADS with IGF receptor was carried out by Ligand Fit of Discovery studio. Accord Excel Package was used for the prediction of ADME properties of the compound. RESULTS: The results suggests that DADS decreases the survival rate of androgen independent prostate cancer cells by modulating the expression of IGF system, which leads to inhibition of phosphorylation of Akt, thereby inhibits cell cycle progression and survival by lowering the expression of cyclin D1, NFkB and anti-apoptotic Bcl-2 molecule and increasing the level of pro-apoptotic (Bad and Bax) signaling molecules which leads to apoptosis. CONCLUSION: The present investigation showed downregulation of Akt and a concomitant increase in apoptosis in DADS treated prostate cancer cells. Since inhibition of this Akt pathway by DADS leads to inhibition in cancer cell progression, it is highly suggested that DADS has the potential use as a therapy for prostate cancer.

Chemopreventive effects of zinc on prostate carcinogenesis induced by N-methyl-N-nitrosourea and testosterone in adult male Sprague-Dawley rats.

PURPOSE: Zinc is an important micronutrient involved in structural and regulatory functions in mammalian cells. It inhibits proliferation of both androgen-dependent and -independent prostate cancer in vitro. However, no report is available on the chemopreventive role of zinc on prostate cancer initiation in in vivo model. The main purpose of this study was to assess the chemopreventive effects of zinc on prostate carcinogenesis induced by a single dose of N-methyl-N-nitrosourea (MNU) and continuous testosterone administration in Sprague-Dawley rats. METHODS: In this study, prostate cancer was induced in Sprague-Dawley rats using MNU+ testosterone (MNU + T). Rats were simultaneously treated with zinc (100 ppm) thrice a week. Serum and tissue activity of prostatic acid phosphatase (PAcP) was measured using biochemical analysis. Serum and tissue zinc levels were assessed by atomic absorption spectrophotometry. The ventral prostatic citrate level, phase I drug-metabolizing enzymes such as cytochrome P450, cytochrome b(5), cytochrome b(5) reductase, cytochrome C reductase, phase II enzyme like glutathione-S-transferase, lipid peroxidation, hydrogen peroxide (H(2)O(2)), and reduced glutathione were also analyzed by biochemical assays. Protein expressions of p53, proliferating cell nuclear antigen (PCNA), caspase-3, and B-cell lymphoma protein-X(L) (Bcl-X(L)) were detected by Western blot analysis. Histopathological evaluation of ventral prostate was studied using hematoxylin and eosin staining method. RESULTS: MNU + T-treated rats showed 60, 50, and 30% of hyperplastic, dysplastic, and prostatic intraepithelial neoplastic changes, respectively, in ventral prostate, whereas MNU + T along with zinc-treated rats showed an incidence of each 10% of hyperplasia, dysplasia, and prostatic intraepithelial neoplasia in the ventral prostate. Serum zinc level and PAcP activity were significantly increased in MNU + T-treated rats, whereas these were decreased in zinc-treated rats. The ventral prostatic PAcP and glutathione-S-transferase activities, zinc, citrate, reduced glutathione levels, and protein levels of p53, caspase-3 were significantly decreased in MNU + T-treated rats, whereas increased in zinc-treated rats. Phase I drug-metabolizing enzyme activities, lipid peroxidation, H(2)O(2) levels, PCNA, and Bcl-X(L) levels were increased in MNU + T-treated rats, whereas these levels were restored to within normal limits in zinc-treated rats. CONCLUSION: This study suggests that zinc may have a beneficial effect against MNU and testosterone-induced prostate carcinogenesis. Thus, it may act as a potential chemopreventive agent in targeting the prostate cancer.

Antioxidant effect of ascorbic acid on PCB (Aroclor 1254) induced oxidative stress in hypothalamus of albino rats.

BACKGROUND: PCBs are one of the environmental toxicants and neurotoxic compounds which induce the production of free radicals leading to oxidative stress. Vitamin C is well known as an outstanding antioxidant. We determined the protective role of ascorbate on hypothalamic antioxidant system of Aroclor 1254 exposed rats. METHODS: The rats were injected Aroclor 1254 at a dose of 2 mg/kg bw/day intraperitoneally for 30 days. One group of rats received vitamin C (100 mg/kg bw/day) orally simultaneously with Aroclor 1254 for 30 days. Twenty-four hours after last treatment, the animals were killed and hypothalamic region was separated from brain tissue. Enzymatic and non-enzymatic antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR) and vitamin C were estimated. Hydrogen peroxide (H(2)O(2)), lipid peroxidation (LPO) and acetylcholine esterase (AchE) activity were determined. Serum gonadotropins such as luteinizing hormone (LH) and follicle stimulating hormone (FSH) were also assayed. RESULTS: Activities of SOD, CAT, GPx, GR, AchE and the concentration of vitamin C were decreased while an increase in H(2)O(2) and LPO were observed in hypothalamus of PCB treated animals. LH and FSH concentrations were also decreased in serum of PCB exposed animals. Vitamin C administration retrieved all the parameters significantly except serum hormonal profiles. CONCLUSION: PCB induces oxidative stress in hypothalamus by decreasing the activities of antioxidant enzymes, which can be protected by vitamin C treatment.

Antiproliferative effect of diallyl disulfide (DADS) on prostate cancer cell line LNCaP.

Garlic has been used throughout the world to treat coughs, toothache, earache, dandruff, hypertension, hysteria, diarrhoea, dysentery, diptheria, vaginitis and many other conditions. Garlic contains a complex mixture of oil and water-soluble organosulfur compounds. Diallyl disulfide (DADS), an oil-soluble constituent of garlic seems to be effective in reducing tumour cells originating from colon, lung and skin. Hence our present study focuses on the dose-dependent effect of DADS on an androgen-dependent prostate cancer cell line. Various concentrations of DADS ranging from 25 to 100 microM were given to LNCaP cells and the activity of lactate dehydrogenase (LDH) prostatic acid phosphatase (PAcP) and the level of prostate specific antigen were studied. DADS reduced the secretory activity of LNCaP cells with the gradual increase in dosage. DADS was found to act as a good antiproliferative agent, which was confirmed by proliferation assay. DADS also induced apoptosis and nuclear segmentation in the higher doses.

Effect of Aroclor 1254 on Sertoli cellular antioxidant system, androgen binding protein and lactate in adult rat in vitro.

Polychlorinated biphenyls (PCBs) are persistent and bioaccumulative environmental toxicants. Previous studies suggested that PCBs (Aroclor 1254) induce toxic effects including reproductive toxicity. The present study was designed to investigate the impact of Aroclor 1254 on Sertoli cellular function and antioxidant system of adult rat in vitro. Sertoli cells were isolated from adult rat testes and treated with various concentrations (10(-10) to 10(-7) M) of Aroclor 1254 for 6, 12 and 24 h. After the treatment period, cell viability was assessed and the Sertoli cellular antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), gamma-glutamyl transpeptidase (gamma-GT) and glutathione reductase (GR) and lipid peroxidation (LPO) were assayed. In addition, androgen binding protein (ABP) and lactate secretions were also quantified in Sertoli cell culture medium. Sertoli cellular viability and activity of antioxidant enzymes were significantly reduced in Aroclor 1254 (10(-10) to 10(-7) M) treatment for 6, 12 and 24 h whereas, the Sertoli cellular lipid peroxidation was significantly increased in a dose and duration dependent manner. In addition, ABP secretion diminished and lactate secretion was significantly elevated in the same manner. To conclude, the present study suggested that Aroclor 1254 disrupts Sertoli cellular metabolic functions such as ABP, lactate secretions and activity of antioxidant enzymes.