Quantitative comparison of immunohistochemical and PCR analysis of midkine expression in breast cancer types and serum midkine level.

BACKGROUND/AIM Midkine (MK), a heparin-binding growth factor, has an important role in cancer progression. The aim of this study was to determine MK expression in breast tissue and the preoperative and postoperative serum levels of patients with breast cancer. MATERIALS AND METHODS Sixty-one patients with breast cancer participated in our study. The MK serum levels were measured pre- and postoperatively for these patients. We also analyzed breast tissues of the 61 patients immunohistochemically. We examined serum midkine levels in 49 healthy volunteers. RESULTS MK expression was observed in 44 (72.1%) of 61 breast cancer patients. In breast cancer patients the serum MK levels (3.68 ± 2.13 ng/mL (mean ± SD)) were significantly higher than in the control group (1.77 ± 0.38 ng/mL) before tumor removal (P = 0.000). After tumor removal, serum MK levels (2.47 ± 1.00 ng/mL) were significantly (P = 0.000) decreased according to preoperative levels. Increased serum levels of MK were related with tumor stages when clinical parameters were analyzed. CONCLUSION We found that increased serum MK levels and protein expressions were associated with the carcinogenesis of breast cancer. MK levels decreased after tumor removal. According to our findings, MK might be a useful tumor marker for patients with breast cancer.