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    Effects of melatonin on apoptosis and cell differentiation in MCF-7 derived cancer stem cells
    (C M B Assoc, 2018) Kocak, Nadir; Donmez, Huseyin; Yildirim, Ibrahim Halil
    Melatonin is a hormone of the pineal gland that has a wide range of biological effects such as antioxidant, anti-inflammatory, and anti-tumor activity. Previous studies have shown that melatonin also affects survival, proliferation, and apoptosis of the cells. In this study, we investigated the effect of melatonin on apoptosis, self-renewal, and differentiation. For this purpose, MCF-7 and HEK293 cells were subjected to melatonin treatment. Expression of genes related to apoptosis (Bax and Bcl2) and self-renewal and differentiation (Oct4, Sox2, and Nanog) analyzed after the sorting of cancer stem cells from MCF-7 cells. Results showed that the effect of melatonin is dependent on the melatonin concentration and treatment periods. Melatonin treatment decreased the cell proliferation rate of MCF-7 in contrast to HEK293. Also, this treatment increased apoptosis in MCF-7 cells and decreased in HEK293 cells. Gene expression of Nanog was decreased and Sox2 was increased in both cell groups after the melatonin treatment. Expression of Oct4 was decreased in MCF-7 cells and increased in HEK293 cells. We determined that melatonin decreases apoptosis and differentiation of stem cells in normal HEK293 stem cells, but increases apoptosis and differentiation in the MCF-7 cancer stem cells.
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    Expression patterns of genes in steroidogenic, cholesterol uptake, and liver x receptor-mediated cholesterol efflux pathway regulating cholesterol homeostasis in natural and PGF2? induced luteolysis as well as early pregnancy in ovine corpus luteum
    (Elsevier, 2022) Hitit, Mustafa; Kose, Mehmet; Kocak, Nadir; Atli, Mehmet Osman
    The aim was to evaluate the expression of genes of steroidogenic, cholesterol uptake, and liver X receptor (LXR) mediated cholesterol efflux pathway in ovine corpus luteum (CL) during natural and prostaglandin F2 alpha (PGF2 alpha) induced luteolysis and early pregnancy. For this study, two experiments were carried out 1); ewes were grouped into two sub-groups as cyclic 12 (C12, n = 4) and 16 (C16, n = 4) and pregnant 12 (P12, n = 4), 16 (P16, n = 4), and 22 (P22, n = 4). Additionally, 2) ewes were grouped into four groups following treatment of PGF2 alpha, the duration of PGF2 alpha challenge at 1 (PG1, n = 4), 4 (PG4, n = 4), and 16 (PG16, n = 4) hours on day 12 of the cycle was compared with 0 h. The corpus luteum tissue samples were collected on the corresponding estrus cycle and pregnancy days, and RNA was extracted using Trizol. mRNA expression levels of the steroidogenic (StAR, CYP11A1, and HSD3B1) and cholesterol uptake receptors (SCARB1 and LDLR) and LXR pathway (NR1H3, NR1H2, ABCA1, and ABCG1) were assessed using quantitative PCR (qPCR), and protein of LXR pathway was investigated using western blot. In-situ hybridization was used to detect mRNA localization. Steroidogenic and cholesterol uptake mRNAs were decreased in C16, while NR1H2 and ABCG1 were increased in C16, compared to C12. Steroidogenic and cholesterol uptake mRNA was greater in P16 than in C16. NR1H2 and ABCA1 protein expression were higher in P16 than in C16. LDLR mRNA was higher in P22 than in P12, while SCARB1 was higher in P16 than in P12. NR1H2 mRNA was greater in P22 than in P12. Steroidogenic and cholesterol uptake mRNA were decreased in PGF2 alpha-induced luteolysis groups against C12. ABCG1 mRNA was higher in PG16 than in PG4 and PG1. The reduction of lipoprotein receptors rather than LXR-mediated reverse transport may contribute to the decline in progesterone (P4) in natural and functional luteolysis.
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    Investigation of autophagic effects of melatonin on breast cancer stem cells
    (Allied Acad, 2017) Donmez, Huseyin; Kocak, Nadir; Yildirim, Ibrahim Halil
    Autophagy plays important roles in physiologic cellular events and also in cancers. It has been reported that cells escaped from death via autophagy and if autophagy inhibited, cells conducted to apoptosis. In some studies, protective effects of the melatonin on induced autophagy in cancer cells reported. In this study, we aimed to evaluate the autophagic effect of melatonin in cancer stem cells. For this purpose, CD44+/CD24-phenotype cells sorted from melatonin-treated and untreated MCF-7 and HEK293 cells. Effect of melatonin on autophagy was analysed by immunofluorescence and western blot analysis. Results showed that melatonin-induced LC3 (Microtubule-associated protein 1A/1B-light chain 3) aggregation and formation of autophagic vacuoles in MCF-7 derived cancer stem cells and also induced LC3-I to LC3-II conversion in these stem cells when compared to untreated control group. In conclusion, melatonin showed a pro-autophagic effect in CD44+/CD24-stem cells derived from MCF-7 cells and anti-autophagic effect in CD44+/CD24-stem cells obtained from HEK293 cells.