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Anticancer effects of an extract from the scallop Patinopecten yessoensis on MCF-7 human breast carcinoma cells.

ABSTRACT: Patinopecten yessoensis, is a species of scallop and a marine bivalve mollusk. In traditional East Asian medicine, scallop meat is used as a drug for the treatment of diabetes, pollakisuria, and indigestion. The present study was conducted in order to examine the potential anticancer effects of scallop flesh extract (SE) on MCF-7 human breast cancer cells. An MTT assay was used to evaluate cell viability and flow cytometry was used for the assessment of cell cycle distribution and apoptosis. The alteration in protein expression level was determined by western blot analysis, and the amounts of docosahexaenoic acid and eicosapentaenoic acid in the SE were measured by gas chromatography. SE inhibited the growth of MCF-7 human breast cancer cells in a dose-dependent manner by inducing G0/G1 phase arrest. The cell cycle arrest was associated with the upregulation of p53 and p21, and downregulation of G1 phase-associated cyclin D1/cyclin-dependent kinase (Cdk) 4 and cyclin E1/Cdk 2. In addition, SE-mediated cell cycle arrest was associated with the promotion of apoptosis, as indicated by the expression of apoptosis-associated proteins and changes in nuclear morphology. SE appeared to induce the mitochondrial apoptotic cascade, as indicated by a decreased expression of Bcl-2, activation of Bcl-2 associated X protein, release of cytochrome c, decrease in procaspase-3, and an increase in cleaved-poly (ADP-ribose) polymerase (PARP). Furthermore, the expression levels of Fas-associated via death domain and cleaved caspase-8 were increased in a SE dose-dependent manner. Taken together, these results suggest that the intrinsic and extrinsic pathways of apoptosis are associated with the anticancer effects of SE on MCF-7 cells. Thus, SE may be a suitable candidate for the treatment and prevention of human breast cancer.

SUBMITTER: Lee C

PROVIDER: S-EPMC5530092 | biostudies-other | 2017 Aug

REPOSITORIES: biostudies-other

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Project description:INTRODUCTION:Rapamycin, an inhibitor of the serine/threonine kinase target of rapamycin, induces G1 arrest and/or apoptosis. Although rapamycin and its analogues are attractive candidates for cancer therapy, their sensitivities with respect to growth inhibition differ markedly among various cancer cells. Using human breast carcinoma cell line MCF-7 as an experimental model system, we examined the growth-inhibitory effects of combinations of various agents and rapamycin to find the agent that most potently enhances the growth-inhibitory effect of rapamycin. METHOD:We evaluated the growth-inhibitory effect of rapamycin plus various agents, including cotylenin A (a novel inducer of differentiation of myeloid leukaemia cells) to MCF-7 cells, using either MTT assay or trypan blue dye exclusion test. The cell cycle was analyzed using propidium iodide-stained nuclei. Expressions of several genes in MCF-7 cells with rapamycin plus cotylenin A were studied using cDNA microarray analysis and RT-PCR. The in vitro results of MCF-7 cells treated with rapamycin plus cotylenin A were further confirmed in vivo in a mouse xenograft model. RESULTS:We found that the sensitivity of rapamycin to MCF-7 cells was markedly affected by cotylenin A. This treatment induced growth arrest of the cells at the G1 phase, rather than apoptosis, and induced senescence-associated beta-galactosidase activity. We examined the gene expression profiles associated with exposure to rapamycin and cotylenin A using cDNA microarrays. We found that expressions of cyclin G2, transforming growth factor-beta-induced 68 kDa protein, BCL2-interacting killer, and growth factor receptor-bound 7 were markedly induced in MCF-7 cells treated with rapamycin plus cotylenin A. Furthermore, combined treatment with rapamycin and cotylenin A significantly inhibited the growth of MCF-7 cells as xenografts, without apparent adverse effects. CONCLUSION:Rapamycin and cotylenin A cooperatively induced growth arrest in breast carcinoma MCF-7 cells in vitro, and treatment with rapamycin and cotylenin A combined more strongly inhibited the growth of MCF-7 cells as xenografts in vivo than treatment with rapamycin or cotylenin A alone, suggesting that this combination may have therapeutic value in treating breast cancer. We also identified several genes that were markedly modulated in MCF-7 cells treated with rapamycin plus cotylenin A.

Project description:IntroductionA subpopulation of cancer cells, tumor-initiating cells, is believed to be the driving force behind tumorigenesis and resistance to radiation and chemotherapy. The persistence of tumor-initiating cells may depend on altered regulation of DNA damage and checkpoint proteins, as well as a reduced propensity to undergo apoptosis or senescence.MethodsTo test this hypothesis, we isolated CD24-/low/CD44+ tumor-initiating cells (as mammospheres) from MCF-7 breast cancer cells grown in adherent monolayer culture, and carried out a comprehensive comparison of cell death and DNA damage response pathways prior to and after exposure to ionizing radiation in mammospheres and monolayer MCF-7 cells. Single and double-strand break repair was measured by single-cell gel electrophoresis. The latter was also examined by phosphorylation of histone H2AX and formation of 53BP1 and Rad51 foci. Apoptosis was quantified by flow-cytometric analysis of annexin V-binding and senescence was analyzed on the basis of cellular beta-galactosidase activity. We employed the telomeric repeat amplification protocol to quantify telomerase activity. Expression of key DNA repair and cell cycle regulatory proteins was detected and quantified by western blot analysis.ResultsOur data demonstrate that in comparison to the bulk population of MCF-7 cells (predominantly CD24+/CD44+), the MCF-7 mammosphere cells benefit from a multifaceted approach to cellular protection relative to that seen in monolayer cells, including a reduced level of reactive oxygen species, a more active DNA single-strand break repair (SSBR) pathway, possibly due to a higher level of expression of the key SSBR protein, human AP endonuclease 1 (Ape1), and a significantly reduced propensity to undergo senescence as a result of increased telomerase activity and a low level of p21 protein expression. No significant difference was seen in the rates of double-strand break repair (DSBR) between the two cell types, but DSBR in mammospheres appears to by-pass the need for H2AX phosphorylation.ConclusionsEnhanced survival of MCF-7 tumor-initiating cells in response to ionizing radiation is primarily dependent on an inherent down-regulation of the senescence pathway. Since MCF-7 cells are representative of cancer cells that do not readily undergo apoptosis, consideration of senescence pathways may play a role in targeting stem cells from such tumors.

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Anticancer effects of an extract from the scallop Patinopecten yessoensis on MCF-7 human breast carcinoma cells.

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