ABSTRACT
PURPOSE: The repressor element 1 (RE-1) silencing transcription factor (REST) is a transcription factor which represses the expression of neuronal differentiation-related genes including SYN1 gene. CoREST, encoded by RCOR1 gene, binds to the REST protein for remodeling of chromatin structure. Although there is a relation among REST, RCOR1, and SYN1 genes, the role of these genes in glioma tumors is still unclear. In this study, expressions of REST, RCOR1, and SYN1 genes were detected in primary cultures derived from tumor samples of diffuse astrocytoma (DA), anaplastic oligodendroglioma (AO), and glioblastoma multiforme (GBM) cases. METHODS: Expression profiles were analysed by RT-qPCR and the copy number variations were examined with qPCR in primary cultures. ChIP assay was performed to show binding characteristics of REST and CoREST proteins on promoter region of SYN1 gene. RESULTS: Means of relative expression for REST were as follows: 0.7898, 0.7606, and 0.7318 in DA, AO, and GBM groups, respectively. For RCOR1, expression means in DA, AO, and GBM groups were 0.7203, 0.7334, and 0.7230, respectively. SYN1 expression means were as follows: 0.3936, 0.3192, and 0.3197 in DA, AO, and GBM groups, respectively. Neither gain nor loss of copy numbers were detected for REST and RCOR1 genes in all groups. Copy loss for SYN1 was detected in primary culture of a DA case. REST and CoREST presented positive precipitation pattern on promoter region of SYN1 gene. CONCLUSIONS: Expressions of REST and RCOR1 genes may downregulate SYN1 expression in gliomas. Low expression pattern of SYN1 may maintain cancer stem-like phenotype which contributes to development of gliomas.
Subject(s)
Co-Repressor Proteins/genetics , Glioma/genetics , Nerve Tissue Proteins/genetics , Repressor Proteins/genetics , Synapsins/genetics , Transcriptome/genetics , Adolescent , Adult , Aged , Female , Humans , Male , Middle Aged , Young AdultABSTRACT
PURPOSE: Ponatinib (P) has been used for the treatment of chronic myeloid leukemia (CML) and it is known that inhibition of BCR-ABL fusion protein by ponatinib induces apoptosis of CML cells. Epigallocatechin-3-gallate (EGCG), which is a polyphenol in green tea, induces apoptosis in different types of cancer cells. The purpose of this study was to determine the cytotoxic and apoptotic effects of ponatinib and EGCG combination in K562 CML cell line. This study also aimed to detect alterations of the expression levels of cell cycle-regulation related genes after ponatinib and EGCG combination in K562 CML cell line. METHODS: The cytotoxic effects of the compounds on K562 cells were determined in a time-and dose-dependent manner by using WST-1 analysis. The combination index (CI) isobologram was used to analyze the data. Apoptotic effects of P-EGCG were defined by flow cytometry and gene expressions were detected by RT-qPCR. RESULTS: IC50values of ponatinib and EGCG were 87.13 nM and 50µM, respectively. CI value of the P-EGCG was 0.658 and the combination showed synergistic effect (ED90 value: 28.39 nM ponatinib, 117.12 µg/ml EGCG). Ponatinib, EGCG and P-EGCG induced apoptosis compared to control cells. CyclinD1 and CDC25A were downregulated by P-EGCG by 2.49 and 2.63-fold, respectively. TGF-ß2 was upregulated by 4.57-fold. CONCLUSION: EGCG possesses cytotoxic and apoptotic properties and may cooperate with the growth inhibiting activity of ponatinib synergistically against CML cells. P-EGCG mediated apoptosis might be associated with upregulation of TGF-ß2 gene and downregulation of cyclinD1 and CDC25A genes.
