Melatonin enhances everolimus efficacy in breast cancer by suppressing mTOR pathway activation and promoting apoptosis and mitochondrial function Şeyma Demirkesen, Yakup İriağaç, Erdoğan Selçuk Şeber, Cenk Aral BMC Pharmacology and Toxicology, 2025 BACKGROUND: Everolimus is used in the treatment of breast cancer by targeting the PI3K/AKT/mTOR pathway, particularly during anti-hormonal therapy. The efficacy of everolimus is limited due to a feedback loop that supresses mTOR while simultaneously enhancing Akt activation in endocrine-resistant breast cancer. Melatonin (N-acetyl-5-methoxytryptamine) regulates mitochondrial activity, cell death, and autophagy due to its strong free radical scavenging, antioxidant, and anti-inflammatory characteristics. Melatonin, a naturally occurring oncostatic agent, slows tumor growth in a range of malignancies, including breast cancer. Due to its ability to protect healthy cells from oxidative stress and inflammation, along with its anti-cancer properties, melatonin has the potential to serve asan effective adjuvant in breast cancer therapy. It also inhibits the phosphorylation of mTOR and Akt, two essential pathways implicated in breast cancer growth, which may aid in overcoming resistance to targeted treatments like everolimus. The combination effects of melatonin and everolimus on hormone receptor-positive breast cancer remains unexplored. This study examined the effectiveness of melatonin when combined with everolimus for the treatment of hormone receptor-positive breast cancer. METHODS: To investigate the effects of melatonin and everolimus combination, we divided MCF-7 cells into four experimental groups: the control, Melatonin (3 mM), Everolimus (30 nM), and a combination of Melatonin and Everolimus (3 mM + 30 nM). Cell viability, apoptosis, autophagy activation, and mitochondrial function were evaluated using established techniques. RESULTS: Based on the cell viability test, the combination of 30 nM everolimus and 3 mM melatonin inhibited phosphorylation of 4E-BP1 and p70S6K, which are downstream effectors of the mTOR pathway, and reduced cell growth. In addition, co-administration of melatonin and everolimus increased apoptosis and led to Sub-G1 phase accumulation. LC3 protein expression and LC3 puncta analysis demonstrated autophagic activity. In terms of mitochondrial function, co-administration of melatonin with everolimus did not cause proton leakage or mitochondrial uncoupling, but did restore everolimus-induced respiratory inhibition. CONCLUSIONS: In conclusion, melatonin is thought to improve the effectiveness of everolimus by inhibiting mTOR downstream effectors, enhancing apoptosis, activating autophagy, improving mitochondrial respiration, and reducing MCF-7 growth.
A new approach to DNA isolation from dileptid ciliates (Ciliophora: Litostomatea: Rhynchostomatia) Acta Zoologica Bulgarica, 2020
Melatonin reverses the oxidative stress and mitochondrial dysfunction caused by LETM1 silencing Cenk Aral, Seyma Demirkesen, Rıfat Bircan, Duygu Yasar Sirin Cell Biology International, 2020 LETM1 is a mitochondrial inner‐membrane protein, which is encoded by a gene present in a locus of 4p, which, in turn, is deleted in the Wolf–Hirschhorn Syndrome, and is assumed to be related to its pathogenesis. The cellular damage caused by the deletion is presumably related to oxidative stress. Melatonin has many beneficial roles in protecting mitochondria by scavenging reactive oxygen species, maintaining membrane potential, and improving functions. The aim of this study was to investigate the effects of melatonin administration to LETM1‐silenced mouse embryonic fibroblast cells as a cellular model for LETM1 deficiency. We transfected mouse embryonic fibroblast cells with a pair of siRNA against LETM1 and monitored the oxidative stress and mitochondrial functions with or without melatonin addition. MnSOD expression and aconitase activity decreased and oxidized protein levels increased in LETM1‐silenced cells. LETM1 suppression did not alter the expression of OXPHOS complexes, but the oxygen consumption rates decreased significantly; however, this change was not related to complex I but instead involved complex IV and complex II. Melatonin supplementation effectively normalized the parameters studied, including the oxygen consumption rate. Our findings identified a novel effect of LETM1 deficiency on cellular respiration via complex II as well as a potential beneficial role of melatonin treatment. On the other hand, these effects may be specific to the cell line used and need to be verified in other cell lines.
Novel binuclear antimony(III) halide complexes of 5-methoxy-2-mercaptobenzimidazole: synthesis, structural characterization, and biological studies Ibrahim Ismet Ozturk, Sinem Yarar, Muazzez Gürgan, Deniz Ceyhan, Nikos Panagiotou, Anastasios J. Tasiopoulos, Seyma Demirkesen, Cenk Aral Journal of Coordination Chemistry, 2020 The new binuclear antimony(III) complexes corresponding to the formulas [SbCl3(µ2-S)(MtMBZIM)2]2 (1), {[SbBr2(µ2-Br)(MtMBZIM)2]2·H2O} (2) and {[SbI2(µ2-I)(MtMBZIM)2]2·H2O} (3) (MtMBZIM: 5-methoxy-2-mercaptobenzimidazole) have been synthesized and structurally characterized with regard to their melting point, elemental analysis, molar conductivity, FT-IR, and FT-Raman spectroscopic techniques, and TG-DTA analysis. The crystal structures of 1-3 have been determined by single-crystal X-ray diffraction. Compounds 1-3 are doubly bridged dimers and in each square pyramidal monomeric unit, the equatorial plane is formed by two sulfur and two halogen atoms in trans-S, trans-X arrangement. The monomeric units in 2 and 3 are linked to each other via halogen bridges, but in 1, they are linked to each other via sulfur bridges; to our knowledge, this binding type is the first example of trans-S, trans-X square pyramidal antimony(III) complexes. Newly synthesized complexes with their corresponding ligand have been tested for their in vitro cytotoxic activity against human adenocarcinoma cervix (HeLa) cells as well as for their antimicrobial activity. The influence of 1-3 on the catalytic peroxidation of the linoleic acid by the enzyme lipoxygenase (LOX) has been determined experimentally and theoretically. Graphical Abstract
The Mitochondrial DNA Control Region Might Have Useful Diagnostic and Prognostic Biomarkers for Thyroid Tumors Rıfat Bircan, Hülya Ilıksu Gözü, Esra Ulu, Şükran Sarıkaya, Aylin Ege Gül, Duygu Yaşar Şirin, Serhat Özçelik, Cenk Aral Experimental and Clinical Endocrinology and Diabetes, 2019 The literature suggests that mitochondrial DNA (mtDNA) defects are associated with a large number of diseases including cancers. The role of mtDNA variations in thyroid cancer is a highly controversial topic. Therefore, we investigated the role of mt-DNA control region (CR) variations in thyroid tumor progression and the influence of mtDNA haplogroups on susceptibility to thyroid tumors. For this purpose, in total, 108 hot thyroid nodules (HTNs), 95 cold thyroid nodules (CTNs), 48 papillary thyroid carcinoma (PTC) samples with their surrounding tissues and 104 healthy control subjects’ blood samples were screened for all mtDNA CR variations using Sanger sequencing. We found that MtDNA haplogroup U was significantly associated with susceptibility to benign thyroid entities. In addition, eight single nucleotide polymorphisms (SNPs) (T146C, G185A, C194T, C295T, G16129A, T16304C, A16343G and T16362C) in the mtDNA CR were associated with the occurrence of benign and malign thyroid nodules in the Turkish population. As compared with samples taken from a healthy Turkish population and HTNs, the frequency of C7 repeats in D310 polycytosine sequence was found to be higher in CTNs and the PTC samples. In addition, the frequency of somatic mutations in mtMSI regions including T16189C and D514 CA dinucleotide repeats were found to be higher in PTC samples than benign thyroid nodules. Conversely, the frequency of somatic mutations in D310 was found to be higher in HTNs than CTNs and PTCs. In conclusion, mtDNA D310 instability does not play a role in the tumorigenesis of PTC but the results indicate that it might be used as a diagnostic clonal expansion biomarker for premalignant thyroid tumor cells. In addition, D514 CA instability might be considered as a prognostic biomarker for benign to malign transformation in thyroid tumors.
Impact of glucocorticoid receptor gene (NR3C1) polymorphisms in Turkish patients with metabolic syndrome Z. Kaya, S. Caglayan, M. Akkiprik, C. Aral, G. Ozisik, M. Ozata, A. Ozer Journal of Endocrinological Investigation, 2016 BackgroundThe metabolic syndrome (MetS) is characterized by a cluster of metabolic factors, including insulin resistance and type-2 diabetes, abdominal obesity, dyslipidemia, hypertension and microalbuminuria. Impaired glucocorticoid receptor (GR) activity also plays an important role in the etiology of MetS. The objective of our study is to evaluate the effects of GR gene polymorphisms (BclI, N363S, TthIII1 and ER22/23EK) in Turkish patients with MetS.Materials and methodsSeventy subjects with MetS and 185 healthy controls were enrolled in the study. PCR–RFLP analysis was used for genotyping. Results for each polymorphism have been verified by allele-specific oligonucleotide analysis.ResultsBclI GG genotype was significantly associated with an increased risk of MetS (p = 0.02). Also, only in women, the G allele carriers were significantly associated with higher C-peptide. T allele carriers of TthIII1 polymorphism were significantly associated with higher C-peptide, triglyceride, insulin and C-reactive protein (CRP, p value 0.048, 0.022, 0.005 and 0.022, respectively), and lower fasting blood glucose (FBG, p = 0.02). The combined carriers of BclI polymorphism G allele and TthIII1 polymorphism T allele were significantly associated with higher diastolic blood pressure in all patients, and lower FBG and postprandial blood glucose in only men. All the ER22/23EK polymorphisms coexisted with polymorphic variant of TthIII1 (p = 0.0058).ConclusionThe presence of homozygote polymorphic variant of BclI might be good predictive markers for the disease susceptibility. The BclI and the TthIII1 polymorphism are associated with sex-specific clinical parameters. Our findings also suggest that the combination of BclI and TthIII1 polymorphisms may play a protective role in blood glucose.
Association of ACP1 genotypes and clinical parameters in patients with metabolic syndrome M. Akkiprik, Filiz Özdemir Sertoğlu, S. Çağlayan, C. Aral, Gökhan Özişik, Zehra Atabey, M. Ozata, Sıdıka Ayşe Özer Turkish Journal of Medical Sciences, 2011 Results: When compared to controls, genotypes associated with low enzyme activity were observed at signifi cantly lower frequencies in both sexes. Of note, high enzyme activity genotypes were more common in patients with MS when compared with medium and low enzyme activity genotypes. *A allele frequency was not diff erent between patients and controls even considering sex; however, there was a good correlation of the presence of the allele with body composition, serum cortisol levels and suppressibility of cortisol, particularly in women with MS. Conclusion: Our fi ndings suggest that low enzyme activity genotypes seem to be associated with a protective eff ect for the development of MS. Additionally, *A allele carriage aff ects body composition in women but not in men, and the presence of this allele might modulate serum cortisol levels as well as its suppressibility in both sexes, in an inverse manner.
Effects of lecithin: Cholesterol acyltransferase genotypes, enzyme levels, and activity on high-density lipoprotein levels Deniz Agirbasli, Beyazit Cirakoglu, Fatih Eren, Mutlu Sumerkan, Sukru Aksoy, Cenk Aral, Mehmet Agirbasli Journal of Clinical Lipidology, 2011 BACKGROUND Lecithin:cholesterol acyltransferase (LCAT) is one of the key enzymes controlling cholesterol homeostasis and plays a primary role in high-density lipoprotein cholesterol (HDL-C) maturation. OBJECTIVE The aim of our study was to evaluate the effects of LCAT gene polymorphisms 511C/T (exon4), 4886C/T (rs5923), and 608C/T (rs5922) on LCAT enzyme level, activity, and HDL-C levels. METHODS The study population was selected from consecutive subjects with low (<35 mg/dL) and high HDL-C levels (>65 mg/dL) seen in our lipid clinic. LCAT polymorphisms were analyzed with a restriction fragment length polymorphism assay. LCAT activity and levels were measured by colorimetric enzymatic and enzyme-linked immunoassay methods, respectively. RESULTS The 4886C/T polymorphism was the most commonly observed variant of LCAT gene. T-allele frequencies in subjects with low (n = 50) and high (n = 50) HDL-C were 0.54 and 0.37, respectively (P = .019). TT genotype was more common among low HDL-C group (30% vs 14%, P = .05). The effects of LCAT enzyme appeared to depend on the HDL-C level. In subjects with low HDL-C, LCAT enzyme levels correlated positively with body mass index (P < .001, r = 0.544), HDL-C (P = .006, r = 0.404), triglycerides (P = .001, r = 0.487), total cholesterol (P < .001, r = 0.541), and low-density lipoprotein-cholesterol (P = .001, r = 0.477) levels. LCAT activity correlated positively with fasting glucose levels (P = .008, r = 0.390). CONCLUSION LCAT genotype, enzyme level, and activity modulate HDL-C metabolism, particularly among subjects with low HDL-C levels.
Investigation of relationship of the mitochondrial DNA 16189 T>C polymorphism with metabolic syndrome and its associated clinical parameters in Turkish patients Cenk Aral, Mustafa Akkiprik, Sinan Caglayan, Zehra Atabey, Gokhan Ozişik, Nuray Bekiroglu, Ayşe Ozer Hormones, 2011 OBJECTIVEMitochondrial DNA (mtDNA) polymorphisms have been implicated in the pathophysiology of human diseases. Among them, a T>C nucleotide transition on the 16189 nucleotide position of mtDNA has been studied in several metabolic diseases including diabetes and obesity. In this study we aimed to investigate the association of this polymorphism among Turkish metabolic syndrome patients.DESIGNA total of 220 cases (70 MetS patients and 150 healthy control subjects) were evaluated for their mtDNA 16189 variant by PCR-RFLP technique. In addition, clinical and biochemical variables, such as cholesterol levels, body fat percentage, insulin resistance and presence of type II diabetes, were also evaluated.RESULTSOverall frequency of polymorphic C allele was determined as 0.19 without a significant association with type II diabetes and metabolic syndrome. This may be partly due to ethnical differences of populations studied and may also be related to other genetic and environmental factors. Moreover, there were no significant associations with biochemical variables among metabolic syndrome patients, except LDL and suppressed cortisol (sup-cortisol) levels. Low levels of LDL and sup-cortisol were significantly associated with the mtDNA 16189 variant, though the biochemical mechanism underlying this effect is not clear.CONCLUSIONSThis is the first study involving a Turkish population on the mtDNA 16189 T>C polymorphism. Further studies with larger cohorts will be needed to elucidate its relation with metabolic syndrome as well as lipid metabolism.
Mitochondrial DNA common deletion is not associated with thyroid, breast and colorectal tumors in Turkish patients Cenk Aral, Mustafa Akkiprik, Handan Kaya, Çigdem Ataizi-Çelikel, Sinan Çaglayan, Gökhan Özisik, Hüseyin Baloglu, Ayse Özer Genetics and Molecular Biology, 2010 Recently, efforts have been focused on mitochondrial DNA changes and their relation to human cancers. Among them, a 4977 bp deletion of mitochondrial DNA, named “common deletion”, has been investigated in several types of tumors, with inconsistent results. In this study, we investigated the presence of the common deletion in tissues from 25 breast, 25 colorectal and 50 thyroid tumors and in the adjacent healthy tissues from Turkish patients. Samples from healthy volunteers were also evaluated for comparison. Two PCR-based methods were used for the detection of the common deletion. First, two pairs of primers were used to amplify wild-type and deleted mtDNA. Then, a highly sensitive nested-PCR was performed, to determine low amounts of deleted genomes. By the first method, wild-type mtDNAs were observed in all samples, but a deletion was observed in only six thyroid samples, by using the nested-PCR method. In conclusion, the mitochondrial common deletion was very rare in our study group and did not appear to be not related with cancer.
Preparation and in vitro transfection efficiency of chitosan microspheres containing plasmid DNA:poly(L-lysine) complexes Journal of Pharmacy and Pharmaceutical Sciences, 2003
Transfection efficiency of chitosan microspheres: Effect of DNA topology S T P Pharma Sciences, 2003
Co-encapsulation of two plasmids in chitosan micropheres as a non-viral gene delivery vehicle Journal of Pharmacy and Pharmaceutical Sciences, 2003
Studies of effective factors of plasmid DNA-loaded chitosan microspheres I. Plasmid size, chitosan concentration and plasmid addition techniques S T P Pharma Sciences, 2000
Co-encapsulation of double plasmids in chitosan microspheres as a non-viral gene delivery vehicle Proceedings of the Controlled Release Society, 1999
