Association of MicroRNA-652 Expression with Radiation Response of Colorectal Cancer : A Study from Rectal Cancer Patients in a Swedish Trial of Preoperative Radiotherapy

Background: Radiotherapy is a standard adjuvant therapy in patients with progressive rectal cancer, but many patients are resistant to radiotherapy, leading to poor prognosis. Our study identified microRNA-652 (miR-652) value on radiotherapy response and outcome in rectal cancer patients. Methods: miR-652 expression was determined by qPCR in primary rectal cancer from 48 patients with and 53 patients without radiotherapy. The association of miR-652 with biological factors and the prognosis was examined. The biological function of miR-652 was identified through TCGA and GEPIA database searches. Two human colon cancer cell lines (HCT116 p53(+/+) and p53(-/-)) were used for in vitro study. The molecular interactions of miR-652 and tumor suppressor genes were studied through a computational approach. Results: In RT patients, miR-652 expression was significantly decreased in cancers when compared to non-radiotherapy cases (P = 0.002). High miR-652 expression in non-RT patients was with increased apoptosis marker (P = 0.036), ATM (P = 0.010), and DNp73 expression (P = 0.009). High miR-652 expression was related to worse disease-free survival of non-radiotherapy patients, independent of gender, age, tumor stage, and differentiation (P = 0.028; HR = 7.398, 95% CI 0.217-3.786). The biological functional analysis further identified the prognostic value and potential relationship of miR-652 with apoptosis in rectal cancer. miR-652 expression in cancers was negatively related to WRAP53 expression (P = 0.022). After miR-652 inhibition, the estimation of reactive oxygen species, caspase activity, and apoptosis in HCT116 p53(+/+ )cells was significantly increased compared with HCT116 p53(-/-) cells after radiation. The results of the molecular docking analysis show that the miR652-CTNNBL1 and miR652-TP53 were highly stable. Conclusion: Our findings suggest the potential value of miR-652 expression as a marker for the prediction of radiation response and clinical outcome in rectal
We would like to thank the Swedish Cancer Foundation, Swedish Research Council, and Health Research Council in the South-East of Sweden for supporting the research. We also thank Chettinad Academy of Research and Education.