EXPRESSION PATTERN OF miR-125b-2, -155, -221, AND -320a IS ASSOCIATED WITH RESPONSE OF BREAST CANCER PATIENTS TO TAMOXIFEN.

BACKGROUND

Hormonal therapy is one of the main methods of comprehensive treatment of patients with locally advanced breast cancer (BC). Despite the intensive search for molecules associated with the aggressiveness of the tumor process, currently there are no reliable markers predicting response to neoadjuvant hormonal therapy (NHT).

AIM

To investigate the correlation between miR-125b-2, -155, -221, -320a expression in tumor tissue and HER2/neu status and response to tamoxifen treatment in BC patients.

MATERIALS AND METHODS

Expression levels of miR-125b-2, -155, -221, and -320a were analyzed in biopsy samples of 50 BC patients using a real-time polymerase chain reaction.

RESULTS

We found that levels of miR-125b-2, -155, -221, and -320a were 1.72, 1.65, 1.85, and 2.89 times higher in BC biopsy samples expressing estrogen/progesterone receptors and HER2/neu compared with HER2/neu-negative luminal tumors. Patients with a luminal BC showing higher levels of miR-125b-2 and miR-320a expression before therapy demonstrated better response to NHT with tamoxifen. A strong correlation was calculated for miR-221 expression and response to NHT (r = 0.61).

CONCLUSIONS

The high levels of miR-125b-2, -155, -221, and -320a in tumor tissue are associated with the HER2/neu-positive status of luminal BC subtypes. Tumor samples of patients showing the low response to NHT with tamoxifen are characterized by lower expression of miR-125b-2 and -320a. Hence, miR-125b-2 and -320a could be considered as putative predictive biomarkers associated with tamoxifen sensitivity of hormone-dependent BC.