Browsing by Author "Srinivas, P"

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    Aloe emodin, a natural anthraquinone targeting multiple facets (migration, invasion, angiogenesis) of tumour metastasis
    (EJC SUPPLEMENTS, 2009) Sathiadevan, P; Babykutty, S; Vijayakurup, V; Jayakrishnan, CJ; Gopala, S; Srinivas, P
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    APOPTOSIS INDUCTION OF CENTELLA ASIATICA ON HUMAN BREAST CANCER CELLS
    (AFRICAN JOURNAL OF TRADITIONAL COMPLEMENTARY AND ALTERNATIVE MEDICINES, 2009) Babykutty, S; Padikkala, J; Sathiadevan, PP; Vijayakurup, V; Azis, TKA; Srinivas, P; Gopala, S
    The present study evaluated the ability of methanolic extract of Centella asiatica (Linn) Urban (Umbelliferae) to induce apoptosis in different cancer cell lines. MCF-7 cells emerged as the most sensitive cell line for in vitro growth inhibitory activity. C. asiatica extract induced apoptosis in MCF-7 cells as indicated by nuclear condensation, increased annexin staining, loss of mitochondrial membrane potential and induction of DNA breaks identified by TUNEL reactivity. It is possible that the use of C. asiatica extract as a component in herbal medicines could be justifiable.
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    Genistein induces apoptosis in ovarian cancer cells via different molecular pathways depending on Breast Cancer Susceptibility gene-1 (BRCA1) status
    (EUROPEAN JOURNAL OF PHARMACOLOGY, 2008) Thasni, KAA; Rojini, G; Rakesh, SN; Ratheeshkumar, T; Babu, MS; Srinivas, G; Banerji, A; Srinivas, P
    It has been reported that Breast Cancer Susceptibility gene-1 & 2 (BRCA1 & 2 are potential molecular targets for chemoprevention by isoflavone genistein (4' 5, 7-trihydroxy isoflavone), in breast and prostate cancer cells. It is also known that BRCA1 has inhibitory activity on estrogen receptor-a and genistein's action on cells is mainly through modulation of estrogen receptor activity. The action of genistein with respect to BRCA1 status in ovarian cancer cells has not been reported so far. Therefore in this study, we analyzed the action of genistein on BRCA1 antisense blocked (AS4) and unblocked (NEO) BG-1 ovarian cancer cells. We found that genistein induced comparable cytotoxic effect in both AS4 and NEO cells, but through different pathways. We found that genistein induces caspase 8 dependent apoptotic pathway in NEO cells. Genistein inhibits estrogen receptor-alpha and activates BARD1 in BRCA1 blocked cells and induces estrogen receptor-beta and FAS in presence of BRCA1. It can be concluded that even though there is no difference in the extent of cell death or apoptosis, the molecular mechanism of action of genistein in inducing apoptosis is different in BRCA1 blocked and unblocked cells. This could partially explain the beneficial effects of genistein in both wild type and mutated BRCA1 estrogen receptor positive tumors. (C) 2008 Elsevier B.V. All rights reserved.
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    Increased sensitivity of BRCA defective triple negative breast tumors to plumbagin through induction of DNA Double Strand Breaks (DSB)
    (SCIENTIFIC REPORTS, 2016) Nair, RS; Kumar, JM; Jose, J; Somasundaram, V; Hemalatha, SK; Sengodan, SK; Nadhan, R; Anilkumar, TV; Srinivas, P
    We have earlier shown that Plumbagin (PB) can induce selective cytotoxicity to BRCA1 defective ovarian cancer cells; however, the effect of this molecule in BRCA1 mutated breast cancers has not been analyzed yet. Here, we report that reactive oxygen species (ROS) induced by PB resulted in DNA DSB and activates downstream signaling by ATR/ATM kinases and subsequent apoptosis. PB reduces DNA-dependent protein kinase (DNA-PK) expression and inhibits NHEJ (Non Homologous End Joining) activity in BRCA1 defective breast cancer cells. Also, PB induces apoptosis in two different BRCA1 conditional knock out murine models: MMTV-Cre; BRCA1(Co/Co) and WAP-Cre; BRCA1(Co/Co), at 2 mg/kg body weight, but 32 mg/kg of carboplatin (CN) was needed to induce apoptosis in them. This is the first study where two different tissue specific promoter driven transgenic mice models with BRCA1 exon 11 deletions are used for preclinical drug testing. The apoptosis induced by PB in HR (Homologous Recombination) defective triple negative BRCA1 mutant cell lines and in mouse models occur by inducing ROS mediated DNA DSB. The toxicity profile as compared with CN in transgenic mice provides evidence for PB's safer disposition as a therapeutic lead in breast cancer drug development.
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    Phenethyl caffeate benzo[kl]xanthene lignan with DNA interacting properties induces DNA damage and apoptosis in colon cancer cells
    (Life Sciences, 2012-11) Vijyakurup, V; Carmela, S; Carmelo, D; Corrado, T; Srinivas, P; Gopala, S
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    Phenethyl caffeate benzo[kl]xanthene lignan with DNA interacting properties induces DNA damage and apoptosis in colon cancer cells
    (LIFE SCIENCES, 2012) Vijayakurup, V; Spatafora, C; Daquino, C; Tringali, C; Srinivas, P; Gopala, S
    Aims: Phenethyl caffeate benzoxanthene lignan (PCBL) is a synthetic compound with DNA interacting, antiangiogenic, antiproliferative and tumor cell death inducing abilities. Though PCBL exhibits the qualities of a prospective antitumor agent, the basic mechanism of PCBL induced cell death remains unknown. This study aims to analyze the molecular mechanisms of PCBL induced cell death in tumor cells to further substantiate its antitumor abilities. Main methods: MTT assay was used for finding cell proliferation inhibition, flow cytometric analysis for the detection of cell cycle arrest, comet assay for DNA break detection and immunofluorescence for analyzing H2AX phosphorylation. Western blot analysis was used to detect the activation of different proteins related to DNA damage response and apoptosis. Key findings: PCBL inhibited proliferation of WiDr cells more efficiently than its analog, MCBL Comet analysis of PCBL treated WiDr cells and activity of various DNA damage response proteins such as gamma-H2AX, BRCA1, ATR and Chk1 in PCBL treated cells demonstrated the DNA damaging property of PCBL Effector molecules of apoptosis such as caspase-3, caspase-7 and caspase-9 were found activated along with PARP cleavage in PCBL treated cells, suggesting apoptosis as the main mode of cell death. PCBL induced cell death was found associated with the activation of MAPK signaling. Inhibition of ERK, one of the MAPKs, by U0126 improved the apoptosis inducing ability of PCBL. Significance: In vitro findings suggest that PCBL works by initiating DNA damage and inducing apoptosis in cancer cells and thus could be considered for further preclinical studies. (C) 2012 Elsevier Inc. All rights reserved.
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    Phenethyl caffeate benzoxanthene lignan is a derivative of caffeic acid phenethyl ester that induces bystander autophagy in WiDr cells
    (MOLECULAR BIOLOGY REPORTS, 2014) Vijayakurup, V; Spatafora, C; Tringali, C; Jayakrishnan, PC; Srinivas, P; Gopala, S
    We recently reported that Phenethyl caffeate benzoxanthene lignan (PCBL), a semisynthetic compound derived from Caffeic Acid Phenethyl Ester (CAPE), induces DNA damage and apoptosis in tumor cells. In this study, we further investigated whether PCBL induces autophagy in WiDr cells. We also analyzed the pathways regulating autophagy and the role of autophagy in PCBL-induced cell death. Our acridine orange staining and LC3 II expression results suggest that PCBL induces autophagosomes in WiDr cells. The levels of LC3 II expression we observed after co-treatment of PCBL with bafilomycin A1 and the reductions in p62 expression we observed after PCBL treatment in WiDr cells demonstrate increased autophagic flux, a reliable indicator of autophagic induction. The increased Beclin 1 expression in PCBL-treated cells and the incapacity of PCBL to induce LC3 II in 3-methyladenine (3-MA)-treated cells we observed suggests that PCBL-induced autophagy is class III PI3-kinase dependent. PCBL did not alter phosphorylation of the mTOR substrate p70 S6 kinase, indicating that PCBL-induced autophagy was not mTOR regulated. Two autophagy related proteins, Atg5 and Atg12, also remained uninduced during PCBL treatment. The increased caspase activity and expression levels of LC3 II and p62 we observed in response to PCBL treatment in primary glioma cells demonstrates that PCBL-induced apoptosis and autophagy were not cell line specific. Pharmacological inhibition of autophagy did not alter the antitumor efficacy of PCBL in WiDr cells. This attests to the bystander nature of PCBL-induced autophagy (in terms of cell death). In toto, these data suggest that PCBL induces a class III kinase dependent, but mTOR independent, bystander mode of autophagy in WiDr cells.
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    Progranulin mutation analysis: Identification of one novel mutation in exon 12 associated with frontotemporal dementia
    (NEUROBIOLOGY OF AGING, 2016) Aswathy, PM; Jairani, PS; Raghavan, SK; Verghese, J; Gopala, S; Srinivas, P; Mathuranath, PS
    Progranulin (PGRN) mutations account for an average of 15% of familial frontotemporal dementia (FTD) cases and 20% of total FTD cases worldwide. Here, we investigated the frequency of PGRN mutations in FTD patients (n = 116) from a clinical cohort of south India and detected one novel mutation located on exon 12 in a familial behavioral variant FTD patient (accounting for similar to 1% of total FTD cases and 6% of familial FTD cases). This mutation was found to introduce a premature termination codon and the prematurely terminated messenger RNA may probably undergo nonsense-mediated decay. In enzyme-linked immunosorbent assay, the proband showed significantly reduced level of plasma PGRN (28 ng/mL) compared with controls (150 +/- 38 ng/mL), which implicates haploinsufficiency as the pathogenic mechanism. (C) 2016 Elsevier Inc. All rights reserved.
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    Radiosensitizing effects of plumbagin in cervical cancer cells is through modulation of apoptotic pathway
    (MOLECULAR CARCINOGENESIS, 2008) Nair, S; Nair, RRK; Srinivas, P; Srinivas, G; Pillai, MR
    Radiotherapy is the primary line of cancer treatment for cervical cancer and is known to induce cell death in tumors. Radiotherapy is however limited by the total dose that can be given without damaging normal tissue. Plumbagin, a naturally occurring naphthaquinone, has been reported to have free radical producing properties. Hence we hypothesized that plumbagin could also have properties that could modify effects of radiation on cervical cancer cells. Radiation in combination with plumbagin may thus have treatment augmenting effects. Results from our studies have shown that a lower dose of radiation in combination with plumbagin could induce apoptosis more effectively compared to a higher dose of radiation alone. Plumbagin in combination with 2 Gy of radiation was very effective in inducing apoptosis, when compared to a higher radiation dose of 10 Gy alone. This combination also showed a fivefold increase in the activation of caspase 3 in C33A cells. Activation of effector caspases confirms that the induction of apoptosis by irradiation and plumbagin involves caspase-dependent pathways. Expression of apoptotic regulatory molecules Bcl-2, Bax and Survivin was also modulated by plumbagin in combination with radiation. In summary, this study shows that a combination of plumbagin and radiation augmented cell growth inhibition compared to higher radiation dose alone, thus indicating that plumbagin may be a potential radiosensitizer acting through the induction of apoptosis. (c) 2007 Wiley-Liss, Inc.
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    Structure activity relationship of plumbagin in BRCA1 related cancer cells
    (MOLECULAR CARCINOGENESIS, 2013) Thasni, KA; Ratheeshkumar, T; Rojini, G; Sivakumar, KC; Nair, RS; Srinivas, G; Banerji, A; Somasundaram, V; Srinivas, P
    It has been shown earlier that plumbagin, a naturally occurring naphthaquinone has specific anticancer activity in BRCA1 blocked ovarian cancer cells. Plumbagin can induce estrogen dependent cell signaling and apoptosis in BRCA1 blocked ovarian cancer cells. Being a reactive oxygen species (ROS) generator and apoptosis inducing agent, plumbagin has immense potential as a promising anticancer agent. In this study we analyzed whether there would be increased anticancer activity if the positions of the functional groups on plumbagin were altered and further to analyze the detailed molecular mechanism of action of the lead molecule. Methods like MTT assay, apoptosis analysis by flow cytometry, assessment of mitochondrial membrane potential-m, suppression subtractive hybridization, microarray, molecular docking and estrogen receptorDNA binding activity by electrophoresis mobility shift assay (EMSA) were adopted for assessing the anticancer activity. Consequently we found that, plumbagin was the most potent anticancer agent when compared to structurally related compounds. The anti-cancer activities were in the order plumbagin>1,4-naphthaquinone>juglone>lawsone>menadione. Molecular docking studies showed that plumbagin could be well docked in the receptor ligand complex of TRAILDR5 complexes to activate the extrinsic pathway of apoptosis. Since the antiproliferative activity of plumbagin could be reduced by inhibiting ER, we speculated that plumbagin interferes with the binding of ER to ERE and we confirmed this by EMSA. This study clearly indicates that plumbagin can induce multiple pathways of apoptosis and cell cycle arrest in BRCA1 blocked cells compared to unblocked cells. (c) 2012 Wiley Periodicals, Inc.