Ajda Çoker Gürkan

Multiple sclerosis: association with the interleukin-1 gene family polymorphisms in the Turkish population

Background: Multiple Sclerosis (MS) is a neurodegenerative disease. It involves inflammation and demyelination. Since cytokines play an important role in the development of MS, genes encoding cytokines such as the Interleukin (IL)-1 family are candidate genes for MS susceptibility. Objective: To determine the relationship between IL-1 gene family and MS in the Turkish population. Methods: A total of 409 MS patients and 256 healthy controls were included in the study. IL-1A −889 (rs1800587), IL-1 RN variable number tandom repeat (VNTR), IL-1B −511 (rs 16944) and IL-1B +3953 (rs 1143634) polymorphisms were investigated from the genomic DNA, obtained via blood samples. Results: No association was found between IL-1A and IL-1RN polymorphisms and susceptibility to MS. However, we have found significantly decreased frequency of IL-1B −511 genotype (p = 0.004) in MS patients compared to controls. In addition, there was a significant association between IL-1B −511 (1/2) genotype and early onset MS (EOMS) (p = 0.0001). Conclusions: Individuals with the 2/2 genotype of IL-1B −511 have significantly decreased incidence of MS, suggesting a protective role for this genotype in the Turkish population. Additionally, IL-1B −511 (1/2) genotype was determined as a possible risk factor for EOMS.

Roscovitine-treated HeLa cells finalize autophagy later than apoptosis by downregulating Bcl‑2

The cell cycle is tightly regulated by the family of cyclin-dependent kinases (CDKs). CDKs act as regulatory factors on serine and threonine residues by phosphorylating their substrates and cyclins. CDK‑targeting drugs have previously demonstrated promising effects as cancer therapeutics both in vitro and in vivo. Roscovitine, a purine‑derivative and specific CDK inhibitor, has been demonstrated to arrest the cell cycle and induce apoptosis in a number of different cancer cell lines, including HeLa cervical cancer cells. In the present study, roscovitine was able to decrease both the cell viability and cell survival as well as induce apoptosis in a dose‑dependent manner in HeLa cells by modulating the mitochondrial membrane potential. The decrease of anti‑apoptotic B-cell lymphoma 2 (Bcl‑2) and Bcl-2 extra large protein expression was accompanied by the increase in pro‑apoptotic Bcl-2-associated X protein and P53-upregulated modulator of apoptosis expression. The marked decrease in Bcl‑2 following exposure to roscovitine (20 µM) for 48 h prompted us to determine the autophagic regulation. The outcome revealed that roscovitine triggered Beclin‑1 downregulation and microtubule-associated light chain 3 cleavage starting from 12 h of incubation. Another biomarker of autophagy, p62, a crucial protein for autophagic vacuole formation, was diminished following 48 h. In addition, monodansyl cadaverin staining of autophagosomes also confirmed the autophagic regulation by roscovitine treatment. The expression levels of different Bcl‑2 family members determined whether apoptosis or autophagy were induced following incubation with roscovitine for different time periods. Downregulation of pro‑apoptotic Bcl‑2 family members indicated induction of apoptosis, while the downregulation of anti‑apoptotic Bcl‑2 family members rapidly induced autophagosome formation in HeLa cells.

Polyamines modulate the roscovitine-induced cell death switch decision autophagy vs. apoptosis in MCF-7 and MDA-MB-231 breast cancer cells

Current clinical strategies against breast cancer mainly involve the use of anti‑hormonal agents to decrease estrogen production; however, development of resistance is a major problem. The resistance phenotype depends on the modulation of cell‑cycle regulatory proteins, cyclins and cyclin‑dependent kinases. Roscovitine, a selective inhibitor of cyclin‑dependent kinases, shows high therapeutic potential by causing cell‑cycle arrest in various cancer types. Autophagy is a type of cell death characterized by the enzymatic degradation of macromolecules and organelles in double‑ or multi‑membrane autophagic vesicles. This process has important physiological functions, including the degradation of misfolded proteins and organelle turnover. Recently, the switch between autophagy and apoptosis has been proposed to constitute an important regulator of cell death in response to chemotherapeutic drugs. The process is regulated by several proteins, such as the proteins of the Atg family, essential for the initial formation of the autophagosome, and PI3K, important at the early stages of autophagic vesicle formation. Polyamines (PAs) are small aliphatic amines that play major roles in a number of eukaryotic processes, including cell proliferation. The PA levels are regulated by ornithine decarboxylase (ODC), the rate‑limiting enzyme in PA biosynthesis. In this study, we aimed to investigate the role of PAs in roscovitine‑induced autophagic/apoptotic cell death in estrogen receptor‑positive MCF‑7 and estrogen receptor‑negative MDA‑MB‑231 breast cancer cells. We show that MDA‑MB‑231 cells are more resistant to roscovitine than MCF‑7 cells. This difference was related to the regulation of autophagic key molecules in MDA‑MB‑231 cells. In addition, we found that exogenous PAs have a role in the cell death decision between roscovitine‑induced apoptosis or autophagy in MCF‑7 and MDA‑MB‑231 breast cancer cells.

Association between IL-1RN VNTR, IL-1β -511 and IL-6 (-174, -572, -597) gene polymorphisms and urolithiasis.

Urolithiasis is a common multifactorial urological disorder that is characterized by stone formation. Interleukin (IL)-1 and IL-6 are pro-inflammatory cytokines that might be linked with urolithiasis. The single nucleotide polymorphisms within the IL-1 and IL-6 cytokine genes altered the cytokine expression levels. Our aim was to investigate the potential of IL-1β (-511 C>T), IL-6 (-174 G>C, -572 G>C, -597 G>A) and IL-1RN VNTR gene polymorphisms to be a genetic marker for urinary stone disease. The polymorphisms studied in the promoter regions of IL-1β and IL-6 genes did not reveal a strong association with urolithiasis when compared to the control group (p = 0.293, 0.871, 0.921, 0.536, respectively). However, a significant difference was observed between control and patient groups for IL-1RN VNTR gene polymorphism (χ2 = 6.131, d.f. = 2, p = 0.047). Our data provide evidence that IL-1RN VNTR gene polymorphism may be involved in the pathogenesis of urinary stone formation, contributing to genetic susceptibility for urolithiasis.

Inhibition of extracellular signal-regulated kinase potentiates the apoptotic and antimetastatic effects of cyclin-dependent kinase inhibitors on metastatic DU145 and PC3 prostate cancer cells: RENCÜZOĞULLARI et al.

Purvalanol and roscovitine are specific cyclin‐dependent kinase (CDK) inhibitors, which have antiproliferative and apoptotic effects on various types of cancer. Although, the apoptotic accomplishment of purvalanol and roscovitine was elucidated at the molecular level, the underlying exact of drug‐induced apoptosis through mitogen‐activated protein kinase (MAPK) signaling still speculative. In addition, the role of CDK inhibitors in the downregulation of extracellular signal–regulated kinase 1/2 (ERK1/2)‐mediated epithelial‐mesenchymal transition (EMT) remains unclear. Here, we investigated the potential effect of each CDK inhibitors on cell proliferation, migration, and generation of reactive oxygen species due to the inhibition of MAPKs in metastatic DU145 and PC3 prostate cancer cells. We reported that purvalanol and roscovitine induced mitochondria membrane potential loss–dependent apoptotic cell death, which was also characterized by activation of several caspases, cleavage of poly (ADP‐ribose) polymerase‐1 in DU145 and PC3 cells. Cotreatment of either purvalanol or roscovitine with ERK1/2 inhibitor, U0126, synergistically suppressed cell proliferation, and induced apoptotic action. Also, ERK1/2 inhibition potentiated the effect of each CDK inhibitor on the downregulation of EMT processes via increasing the epithelial marker and decreasing mesenchymal markers through reduction of Wnt signaling regulators in DU145 cells. This study provides biological evidence about purvalanol and roscovitine have apoptotic and antimetastatic effects via MAPK signaling on prostate cancer cell by activation of GSK3β signaling and inhibition of phosphoinositide‐3‐kinase/AKT (PI3K/AKT) pathways involved in the EMT process.

Inhibition of autophagy enhances DENSpm-induced apoptosis in human colon cancer cells in a p53 independent manner

PurposeOne of the recently developed polyamine (PA) analogues, N1,N11-diethylnorspermine (DENSpm), has been found to act as an apoptotic inducer in melanoma, breast, prostate and colon cancer cells. Also, its potential to induce autophagy has been established. Unfolded protein responses and starvation of amino acids are known to trigger autophagy. As yet, however, the molecular mechanism underlying PA deficiency-induced autophagy is not fully clarified. Here, we aimed to determine the apoptotic effect of DENSpm after autophagy inhibition by 3-methyladenine (3-MA) or siRNA-mediated Beclin-1 silencing in colon cancer cells.MethodsThe apoptotic effects of DENSpm after 3-MA treatment or Beclin-1 silencing were determined by PI and AnnexinV/PI staining in conjunction with flow cytometry. Intracellular PA levels were measured by HPLC, whereas autophagy and the expression profiles of PA key players were determined in HCT116, SW480 and HT29 colon cancer cells by Western blotting.ResultsWe found that DENSpm-induced autophagy was inhibited by 3-MA treatment and Beclin-1 silencing, and that apoptotic cell death was increased by PA depletion and spermidine/spermine N1-acetyltransferase (SSAT) upregulation. We also found that autophagy inhibition led to DENSpm-induced apoptosis through Atg5 down-regulation, p62 degradation and LC3 lipidation in both HCT116 and SW480 cells. p53 deficiency did not alter the response of the colon cancer cells to DENSpm-induced apoptotic cell death under autophagy suppression conditions.ConclusionsFrom our results we conclude that DENSpm-induced apoptotic cell death is increased when autophagy is inhibited by 3-MA or Beclin-1 siRNA through PA depletion and PA catabolic activation in colon cancer cells, regardless p53 mutation status.