Changes in Levels of MiR-21, MiR-27a, MiR-221, and MiR-429 in the Thymus after Photodynamic Therapy and Surgical Treatment of Breast Cancer in Female Wistar Rats

We studied the expression levels of microRNAs (miR-21, miR-27a, miR-221, and miR-429) in the thymus of female Wistar rats after surgical treatment of breast cancer (BC) and after photodynamic therapy for BC followed by tumor resection. In the group without treatment, the levels of pro-oncogenic miR-21, miR-27a, and miR-221 in the thymus were reduced in comparison with those in the group of intact control. After surgical treatment of BC, the levels of miR-21 and miR-27a in the thymus increased in comparison with those in BC without treatment. Surgical removal of the tumor followed by photodynamic therapy led to an even greater increase in the levels of miR-21 and miR-27a in the thymus in comparison with those in the group of surgical treatment alone. Expression of the tumor-suppressive miR-429 in the thymus significantly exceeds the levels in the BC without treatment and BC+surgery groups.