Metastatic role of mammalian target of rapamycin signaling activation by chemoradiotherapy in advanced rectal cancer

Abstract

Postoperative distant metastasis dramatically affects rectal cancer patients who have undergone neoadjuvant chemoradiotherapy (NACRT). Here, we clarified the association between NACRT-mediated mammalian target of rapamycin (mTOR) signaling pathway activation and rectal cancer metastatic potential. We performed immunohistochemistry for phosphorylated mTOR (p-mTOR) and phosphorylated S6 (p-S6) on surgical specimen blocks from 98 rectal cancer patients after NACRT (cohort 1) and 80 colorectal cancer patients without NACRT (cohort 2). In addition, we investigated the association between mTOR pathway activity, affected by irradiation, and the migration ability of colorectal cancer cells in vitro. Based on the results of the clinical study, p-mTOR was significantly overexpressed in cohort 1 (with NACRT) as compared to levels in cohort 2 (without NACRT) (P