Cancers are usually associated with:: (A) Mutations in intronic genes, (B) Hypomethylation of oncogenes, (C) Methylation of tumor suppressor genes, (D) Loss of heterogenicity
Answer is C. Epigenetic changes include:- alterations of chromatin structure mediated by methylation of cytosine residues in CpG dinucleotides modification of histones by acetylation or methylation. The transcriptional regulatory regions of active genes often contain a high frequency of CpG dinucleotides (referred to as CpG islands), which are normally unmethylated. Acetylation of the amino terminus of the core histones H3 and H4 induces an open chromatin conformation that promotes transcription initiation. Hypermethylation of promoter region is common mechanism by which tumor-supressor loci are epigentically silenced in cancer cells.