Immunohistochemical Evaluation of mTOR and Beclin-1 Protein Expression in Human Breast Cancer and Adjacent Normal Tissues, A Study in Malaysian Patients

Abstract

Autophagy is a protein degradation process within the cell and its deregulation has been linked to various diseases and the formation of cancer. Both mTOR and Beclin-1 are important proteins involved in the regulation of autophagy process and tumorigenesis. The aims of the study were to assess the expression of autophagic-related proteins in breast cancer tissues and normal breast tissues adjacent to the tumor. Immunohistochemical staining with anti-mTOR, anti-p-mTOR and anti-Beclin-1 antibody was carried out on tissue samples of 24 patients from our local hospitals. The results showed that mTOR and Beclin-1 proteins were present in both types of tissues in all the cases. However, a significant majority of the adjacent normal breast tissues were found to have stronger immunoreactivity towards phosphorylated mTOR (p-mTOR) as compared to the corresponding tumor tissues. Since increased expression of p- mTOR is known to be correlated with tumorigenesis, this may indicate the presence of molecular changes in these cells adjacent to the tumor tissues. Patients with mTOR positive tumors may benefit from use of mTOR inhibitors as part of their pharmacotherapy management.