MicroRNAs in prostate cancer following radiotherapy: towards predicting response to radiation treatement

Prostate cancer (PCa) is the second most frequently diagnosed male cancer worldwide. Early diagnosis of PCa, response to therapy, and prognosis still represent a challenge. Nearly 60% of PCa patients undergo radiation therapy (RT) which might cause side effects. Despite numerous researches in this field, predictive biomarkers for radiation toxicity are still not elucidated. MicroRNAs as posttranscriptional regulators of gene expression are shown to be changed during and after irradiation. MicroRNA level changes might be utilized to predict response to RT in the near future, which might help clinicians to make the decision on treatment regimens if needed. Individual radiation response results from the interactions among radiation treatment parameters and the biological background of each patient. In this review, we have listed and described miRNAs involved in response to RT in PCa and highlighted potential candidates for future biological tests predicting radiation response to RT, with the special focus on side effects of RT. According to described literature, we concluded that let-7, miR-21, miR-34a, miR-146a, miR-155, and members of miR-17/92 cluster might be promising candidates for biological tests predicting radiosensitivity of PCa patients undergoing radiation treatment. Predictive miRNA panels, especially for acute and late side effects of RT, can serve as a starting point for decisions for individualized RT planning. We believe that this review might be one step closer to understanding molecular mechanisms underlying individual radiation response of patients with PCa.