Emir Bozkurt

Combination of AT-101/cisplatin overcomes chemoresistance by inducing apoptosis and modulating epigenetics in human ovarian cancer cells

We investigated the effects of AT-101/cisplatin combination treatment on the expression levels of apoptotic proteins and epigenetic events such as DNA methyltransferase (DNMT) and histone deacetylase (HDAC) enzyme activities in OVCAR-3 and MDAH-2774 ovarian cancer cells. XTT cell viability assay was used to evaluate cytotoxicity. For showing apoptosis, both DNA Fragmentation and caspase 3/7 activity measurements were performed. The expression levels of apoptotic proteins were assessed by human apoptosis antibody array. DNMT and HDAC activities were evaluated by ELISA assay and mRNA levels of DNMT1 and HDAC1 genes were quantified by qRT-PCR. Combination of AT-101/cisplatin resulted in strong synergistic cytotoxicity and apoptosis in human ovarian cancer cells. Combination treatment reduced some pivotal anti-apoptotic proteins such as Bcl-2, HIF-1A, cIAP-1, XIAP in OVCAR-3 cells, whereas p21, Bcl-2, cIAP-1, HSP27, Clusterin and XIAP in MDAH-2774 cells. Among the pro-apoptotic proteins, Bad, Bax, Fas, phospho-p53 (S46), Cleaved caspase-3, SMAC/Diablo, TNFR1 and Cytochrome c were induced in OVCAR-3 cells, whereas, Bax, TRAILR2, FADD, p27, phospho-p53 (S46), Cleaved caspase-3, Cytochrome c, SMAC/Diablo and TNFR1 were induced in MDAH-2774 cells. Combination treatment also inhibited both DNMT and HDAC activities and also mRNA levels in both ovarian cancer cells. AT-101 exhibits great potential in sensitization of human ovarian cancer cells to cisplatin treatment in vitro, suggesting that the combination of AT-101 with cisplatin may hold great promise for development as a novel chemotherapeutic approach to overcome platinum-resistance in human ovarian cancer.

A diverse induction of apoptosis by trabectedin in MCF-7 (HER2-/ER+) and MDA-MB-453 (HER2+/ER-) breast cancer cells.

Trabectedin (Yondelis, ET-743), a semi synthetic tetrahydroisoquinoline alkaloid that was originally derived from the marine tunicate Ecteinascidia turbinata. The objective of this study was to investigate whether trabectedin mediated apoptosis shows any diversity in human breast cancer cell lines with different genotypes. Trabectedin induced cytotoxicity and apoptosis in both breast cancer cells in a time and concentration-dependent manner. The expression levels of the death receptor pathway molecules, TRAIL-R1/DR4, TRAIL-R2/DR5, FAS/TNFRSF6, TNF RI/TNFRSF1A, and FADD were significantly increased by 2.6-, 3.1-, 1.7-, 11.2- and 4.0-fold by trabectedin treatment in MCF-7 cells. However, in MDA-MB-453 cells, the mitochondrial pathway related pro-apoptotic proteins Bax, Bad, Cytochrome c, Smac/DIABLO, and Cleaved Caspase-3 expressions were induced by 4.2-, 3.6-, 4.8-, 4.5-, and 4.4-fold, and the expression levels of anti-apoptotic proteins Bcl-2 and Bcl-XL were reduced by 4.8- and 5.2-fold in MDA-MB-453 cells. Moreover, trabectedin treatment increased the generation of ROS in both breast cancer cells. We have shown that trabectedin causes selective activation of extrinsic and intrinsic apoptotic pathways in two genotypically different breast cancer cells. This preliminary data might guide clinicians to choose appropriate combination agents with trabectedin based on different molecular subtypes of breast cancer.

Novel combination of docetaxel and thymoquinone induces synergistic cytotoxicity and apoptosis in DU-145 human prostate cancer cells by modulating PI3K–AKT pathway

BackgroundThe treatment of castrate-resistant prostate cancer (CRPC) still remains as an important challenge of daily oncology practice. Docetaxel significantly prolongs overall survival in men with CRPC. Thymoquinone (TQ), one of the flavonoid compounds isolated from Nigealla sativa, has been shown to possess cytotoxic activity against a variety of cancer cell lines.Materials and MethodsThe aim of the study was to investigate the possible synergistic cytotoxic/apoptotic effects of a novel combination, docetaxel and TQ in DU-145 hormone- and drug-refractory prostate cancer cells and their effects on PI3K and ERK signaling pathways.ResultsWe observed that the combination of docetaxel and TQ resulted in a significant synergistic cytotoxicy and apoptosis as compared to any single agent alone, in a dose-dependent manner. It was found that viability of the combination treated cells was not significantly changed in the presence of LY294002 as compared to inhibitor treated cells. However, in the presence of FR180204, viability of combination treated cells was significantly decreased as compared to inhibitor treated cells. In conclusion, cytotoxic effect of the docetaxel and TQ combination is correlated with the block of the PI3K/Akt signaling pathway in DU-145 cells.ConclusionTherefore, this combination strategy may be an alternative approach for the challenging era of daily oncologic practice. Also, the combination of docetaxel and TQ might allow a reduction in docetaxel doses and diminish adverse effects of docetaxel while maintaining the therapeutic effect in patients with CRPC.

Effects of Thymus serpyllum extract on cell proliferation, apoptosis and epigenetic events in human breast cancer cells.

Thymus (T.) serpyllum (wild thyme) is an aromatic medicinal plant due to its several biological properties, including anticancer activity. Breast cancer is one of the most common malignancies and increasing evidence supports that it is not only a genetic but also an epigenetic disease. Epigenetics investigates changes in gene expression caused by mechanisms that do not involve alterations in DNA sequence. DNA methylation and histone acetylation are the most widely studied epigenetic changes in cancer cells. This study evaluated the effects of T. serpyllum on apoptosis and epigenetic events in breast cancer cells. XTT cell viability assay was used to determine cytotoxicity. DNA fragmentation and caspase 3/7 activity assays were used in the assesment of apoptosis. DNA methyltransferase (DNMT) and histone deacetylase (HDAC) activities were evaluated by ELISA and verified by qRT-PCR. T. serpyllum extract induced significant cytotoxicity in breast cancer cells (MCF-7 and MDA-MB-231) but not in normal cells. It also induced apoptosis and inhibited the DNMT and HDAC activities in MDA-MB-231 cells. In the present study, the first preliminary data on the effects of the methanolic extract of T. serpyllum in normal and breast cancer cells were obtained and suggest that T. serpyllum may be a promising candidate in the development of novel therapeutic drugs for breast cancer treatment.

Apoptotic and anti-angiogenic effects of Salvia triloba extract in prostate cancer cell lines

Plants, due to their remarkable composition, are considered as natural resources of bioactive compounds with specific biological activities. Salvia genus (Lamiaceae) has been used around the world in complementary medicine since ancient times. We investigated the cytotoxic, apoptotic and anti-angiogenic effects of methanolic Salvia triloba extract (STE) in prostate cancer cells. Cell viability was evaluated by XTT; apoptosis was investigated by DNA fragmentation and caspase 3/7 activity assays. Changes in the angiogenic cytokine levels were investigated by human angiogenesis antibody array. Scratch assay was used to determine the cell motility. STE induced cytotoxicity and apoptosis in a concentration-dependent manner in both cancer cells; however, it was not cytotoxic to normal cells. Cell motility was reduced in PC-3, DU-145 and HUVEC cells by STE treatment. ANG, ENA-78, bFGF, EGF, IGF-1 and VEGF-D levels were significantly decreased by −2.9, −3.7, −1.7, −1.7, −2.0 and −1.8 fold in STE-treated DU-145 cells, however, ANG, IL-8, LEP, RANTES, TIMP-1, TIMP-2 and VEGF levels were significantly decreased by −5.1, −2.0, −2.4, −3.1, −1.5, −2.0 and −2.5 fold in PC-3 cells. These data suggest that STE might be a promising candidate for anti-tumor and anti-angiogenic treatment of prostate cancer.

Docetaxel in combination with octreotide shows synergistic apoptotic effect by increasing SSTR2 and SSTR5 expression levels in prostate and breast cancer cell lines.

PurposeDocetaxel (DTX) is widely used for the treatment of metastatic prostate and breast cancers. Despite the clinical success of DTX, drug-related cumulative toxicity restricts its clinical use in cancer therapy. Thus, there is an urgent need for new therapeutic options. Octreotide (OCT) is a synthetic somatostatin analog that induces apoptosis in different cancer cell lines in vitro. In this study, we investigated the possible synergistic apoptotic effects of DTX in combination with OCT in prostate and breast cancer cell lines.MethodsThe XTT cell viability assay was used to determine cytotoxicity. Apoptosis was evaluated by Cell Death Detection ELISAPlus Kit. The expression levels of apoptotic proteins were assessed by human apoptosis antibody array. Levels of SSTR2 and SSTR5 proteins were determined by western blot analysis.ResultsDTX and OCT combination induced apoptosis in both breast and prostate cancer cells in a concentration- and time-dependent manner. Moreover, combination treatment resulted in inhibition of anti-apoptotic proteins such as Bcl-2 and Bcl-xL and induction of pro-apoptotic proteins Bax, Cytochrome c and IAPs in all of the tested cancer cell lines. SSTR2 and SSTR5 protein levels were induced as compared to any agent alone.ConclusionsThese results indicate that this combination treatment is a significant inducer of apoptosis in a synergistic manner in breast and prostate cancer cells. This strong synergism helps to lower the dose of DTX in both types of cancers, thus letting DTX to be used for longer periods by delaying resistance development and lesser side effects.

Evaluation of the gingival inflammation in pregnancy and postpartum via 25-hydroxy-vitamin D3, prostaglandin E2 and TNF-α levels in saliva

BACKGROUND Physiological changes and immunological modifications occur during pregnancy. The clinical and biological features of periodontal infections are affected by pregnancy. The aim of the present study was to evaluate saliva levels of 25-hydroxy-vitamin D3 (25(OH)D3), prostaglandin E2 (PGE2) and TNF-alpha (TNF-α) in pregnancy, postpartum and non-pregnant controls. METHODS Whole saliva samples together with full-mouth clinical periodontal recordings were obtained from 59 pregnant, 47 post partum and 70 systemically healthy non-pregnant women. Groups were also evaluated according to the periodontal health status. 25(OH)D3, PGE2 and TNF-α levels in the saliva samples were determined by enzyme-linked immunoassays. Data were statistically tested by nonparametrical tests. RESULTS Saliva TNF-α and PGE2 levels were significantly lower and 25(OH)D3 levels were significantly higher in the pregnant group than postpartum group (p<0.0001). Saliva TNF-α and 25(OH)D3 levels were significantly higher and PGE2 levels were significantly lower in the control group than postpartum group (p<0.0001). In the pregnant healthy, gingivitis and periodontitis groups saliva TNF-α levels were significantly lower than postpartum and control counterparts (p<0.0001, p=0.032, p=0.003 and p=0.013; p=0.027; p=0.007, respectively). In control healthy, gingivitis and periodontitis groups saliva 25(OH)D3 levels were significantly higher than the postpartum counterparts (p<0.0001, p<0.0001, p=0.002, respectively). In the control healthy and gingivitis groups saliva 25(OH)D3 levels were significantly higher than pregnant healthy and gingivitis (p<0.0001). CONCLUSIONS In conclusion, within the limits of the present study it seems that pregnancy have an effect on parameters in saliva in relation to the periodontal status of the women. Further studies are required for better understanding of the impact of periodontal diseases on pregnancy or otherwise.

Comparative analysis of XTT assay and xCELLigence system by measuring cytotoxicity of resveratrol in human cancer cell lines

Abstract Objective: In vitro preliminary oncological and translational studies are mainly based on evaluating the cytotoxic effects of a specific compound on cultured cells. Resveratrol is a commercially available compound which is originally isolated from the roots of white hellebore and later from Polygonum cuspidatum. The objective of the study was to compare cytotoxicity data of Resveratrol from XTT end point assay with a real-time cell based xCELLigence system in terms of accuracy, sensitivity, speed and reproducibility in a panel of human cancer cell lines. Methods: XTT end point assay and real-time cell based xCELLigence system were used to evaluate cytotoxicity. Cytotoxicity results were verified by monitoring cells under phase-contrast microscope which were treated with IC50 values of resveratrol. Results: Resveratrol decreased cell viability in a time- and concentration-dependent manner in all cancer cell lines when tested by both the XTT assay and xCELLigence system. Standard deviations of the xCELLigence data were found to be lower than the data from XTT assay. Conclusion: The data from this study strongly imply that xCELLigence system has higher precision, more enlightening and more reproducible than XTT end point assay.

AT-101 acts as anti-proliferative and hormone suppressive agent in mouse pituitary corticotroph tumor cells

PurposeGossypol, a naturally occurring compound in cottonseeds, has anticancer effects against several tumor cell lines. It has been extensively studied in clinical trials and is well tolerated with a favorable safety profile. AT-101, a derivative of R (−)-gossypol, binds to Bcl-2 family proteins and induces apoptosis in vitro. Although transsphenoidal surgical excision of the pituitary corticotroph adenoma is the gold standard of care, it is not successful all the time. Medical therapy for Cushing’s disease still remains a challenge for the clinicians. We aimed to investigate the cytotoxic and apoptotic effects of AT-101 in mouse pituitary corticotroph tumor AtT20 cells.MethodsCytotoxic effect of AT-101 was assessed by XTT cell viability assay. Apoptosis was shown by measuring DNA fragmentation and Caspase-3/7 activity. Changes in mRNA expressions of apoptosis-related genes were investigated by qPCR array after treatment with AT-101. ACTH was measured by ACTH-EIA Kit.ResultsAT-101 induced cytotoxicity and apoptosis in AtT20 cells. mRNA levels of pro-apoptotic genes such as TNFR-SF-10B, Bid, PYCARD, Caspase-8, Caspase-3, and Caspase-7 were induced by 2.0-, 1.5-, 1.7-, 1.5-, 1.6-, and 2-fold, respectively, in AtT20 cells by AT-101 treatment. Moreover, some of the anti-apoptotic genes such as BCL2L10, NAIP1, and PAK-7 were reduced by 2.1-, 2.3-, 4.0-fold, respectively, in AtT20 cells. AT-101 also decreased ACTH secretion significantly.ConclusionAT-101 induces apoptosis in mouse pituitary corticotroph tumor cells.

Combination of zoledronic acid and serine/threonine phosphatase inhibitors induces synergistic cytotoxicity and apoptosis in human breast cancer cells via inhibition of PI3K/Akt pathway

The aim of this study was to investigate the cytotoxic and apoptotic effects of zoledronic acid (ZA) in combination with serine/threonine protein phosphatase inhibitors, calyculin-A (CA) and okadaic acid (OA), in human MCF-7 and MDA-MB-231 breast cancer cells. XTT cell viability assay was used to evaluate cytotoxicity. DNA fragmentation and caspase-3/7 activity assays were performed to evaluate apoptosis. Activities of phosphatase 1 (PP1) and phosphatase 2A (PP2A) were measured by serine/threonine phosphatase ELISA kit. Expression levels of PI3K, p-PI3K, Akt, p-Akt, Bcl-2, p-Bcl-2, Bad, and p-Bad proteins were evaluated by Western blot analysis. Combination of ZA with either CA or OA showed synergistic cytotoxicity and apoptosis as compared to any agent alone in both MCF-7 and MDA-MB-231 breast cancer cells. Combination treatment also resulted in inhibition of both PP1 and PP2A activities. Both agents used alone or in combination did not induce significant changes in total PI3K, Akt, Bcl-2, and Bad expressions, while p-PI3K, p-Akt, p-Bcl-2, and p-Bad levels were reduced by the combination treatment as compared to agents alone. Moreover, apoptotic effect of combination treatment was significantly inhibited in the presence of LY294002, a specific PI3K inhibitor, in both breast cancer cell lines. In conclusion, synergistic apoptotic effect of the combination treatment is correlated with the block of the PI3K/Akt signal pathway in breast cancer cells.