It has increasingly been considered crucial the understanding of DNA methylation of Tumor Suppressor Gene (TSG) promoters, such as that of retinoblastoma 1 gene (RB1), and its role during carcinogenesis.
The purpose of this research is to assess the methylation status of RB1 gene in GC and IM with or without H. pylori infection, and to discuss the possible role of H. pylori-induced RB1 gene methylation in the mechanism of gastric carcinogenesis.
The two progesterone receptors, PRA and PRB, are co-expressed at equivalent levels in normal breast, but early in carcinogenesis normal levels of PRA:PRB are frequently disrupted, and predominance of one isoform, usually PRA, results.
However, alteration in PRA/PRB expression is often observed in aggressive breast cancer suggesting differential contribution of PR isoforms in carcinogenesis.
Based on these results, it is concluded that somatic mutations of the RB1 gene or CDK4 gene do not appear to play a major role in pituitary tumorigenesis.
The high correlation between chromosome 13 losses and absence of RB1 protein expression and the mutations detected strongly suggest that RB1 gene inactivation is a pivotal event in MFH oncogenesis.
Genetic studies of retinoblastoma have yielded unique insights into familial cancer syndromes and the mechanisms of oncogenesis by tumour suppressor genes such as the RB1 gene.
In contrast to the Knudson hypothesis, which suggests a high risk of a multifocal and bilateral tumor in patients with an inherited mutation of the RB-1 gene, literature data indicate a reduced tumorigenesis in patients with a cytogenetic deletion of the critical Rb region of chromosome 13.