Site specific hypermethylation of CpGs in Connexin genes 30, 26 and 43 in different grades of glioma and attenuated levels of their mRNAs

AbstractAim: Gliomas, the intracranial tumours are considered the deadliest diseases. The gap junctional Connexins (Cxs) that maintain cellular homeostasis perform a unique function in glial tumour suppression. However, the differential methylation patterns of Cxs were not revealed in glioma so far. The current study attempts to categorize promoter methylation of Cx30 and Cx26 and intron methylation of Cx43 in different grades of human glioma.Materials and methods: Bisulphite-PCR-Single Stranded Conformation analysis(SSCA), Bisulphite sequencing and MeDIP-qPCR were carried out to assess methylation status in samples from patients. Cx mRNA levels were also analysed to evaluate the effect of methylation.Results: We found that promoter CpG islands(CpGs) reside in Sp1 and Ap2 sites of Cx30 & 26 were hypermethylated in high grades (HG) of glioma rather than low grades (LG). The input % of both was significantly increased (p < 0.03) in progressive grades. Interestingly, Cx43 could exhibit a significant increase...