Clinical assessement of the 8 genes on chromosome 3 with also MGMT gene promoter regions methylaton status in patients with breast cancer luminal hystotype

Abstract

Background. Epigenetic changes of TSG are supposed as the most fine and active genes regulation mechanism in particular breast cancer (BC) genes pathway development. The most valuable results are awaited for methylation role of genes located on the short arm of chromosome 3 with also MGMT gene (10q26) in BC pathogenesis because of their ambiguous data for methylation status in tumors. Objective: to illustrate the specific methylation role of the RASSF1A, SEMA3B, RARß2, RHOA, GPX1, USP4, DAG1, NKIRAS1 and MGMT genes promoter regions in BC pathogenesis. Materials and methods. Sample set of 174 BC patients consists of tumor and surrounding histologically normal tissue that were collected and clinically characterized in the N.N. Blokhin National Medical Research Center of Oncology. Two substantive methods were used to evaluate DNA methylation status. To analyse RASSF1A, SEMA3B, RARß2 and MGMT genes methylation we used polymerase chain reaction specific for the methylated allele. Whereas for analyses RHOA, GPX1, USP4, DAG1, NKIRAS1 promoter regions genes methylation status was used methyl sensitive restriction analyses with 2 methyl sensitive endonuclaeses HpaII and HhaI with subsequent polymerase chain reaction. Results. A statistically significant high frequency of RASSF1A, SEMA3B, RARß2, and MGMT genes methylation in epithelial breast tumors compared with histologically normal tissue from the same patients was shown. Significant correlation of RARß2 and MGMT genes methylation frequency considering the different clinical and morphological characteristics of the malignant process was revealed. The statistically significant relationship between methylation of RASSF1A, RARß2 and MGMT genes and patient survival is shown for the first time. Conclusion. The findings of epigenetic changes in the luminal BC supplement the “molecular picture” of this cancer and contribute to an understanding of its pathogenesis. The revealed features of investigated genes methylation can find clinical application for the development of modern approaches to prognosis, prevention and choice of tactics for treatment of BC in females of the Moscow region.