THE INSULIN EFFECT ON THE PROLIFERATIVE ACTIVITY OF HUMAN BREAST AND PROSTATE CANCER CELLS VARYING IN MALIGNANCY DEGREES IN VITRO

Shlapatska L.M., Lykhova O.O., Shcherbina V.M., Gordiienko I.M.

• R.E. Kavetsky Institute of Experimental Pathology, Oncology and Radiobiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine

Aim: to determine the effect of insulin on the proliferative activity of human breast and prostate cancer cells varying in malignancy degrees in an experimental system in vitro. Object and methods: the study was performed on human breast cancer (BC) T47D, MDA-MB-231, BCC/P and BC/ML and human prostate cancer (PC) LNCap, Du-145, PC-3 cell lines different in malignancy degree. Determination of the IPO-38 and Ki-67 nuclear antigens of proliferating cells expression was performed using an indirect variant of the immunofluorescence method. Results were examined Beckman Coulter DxFLEX fluorescence flow cytometer, followed by processing the results using the program CytExpert for DxFLEX. The effect of insulin on the proliferative activity of BC and PC cell lines was evaluated by the determining expression level of IPO-38 after 72 h of culturing cells with insulin at a concentration of 0.02 μg/ml (corresponds to its physiological concentration), and 0.5, 2 and 5 μg/ml (correspond the conditions of hyperinsulinemia). Results: It was found that insulin at the concentration 0.02 μg/ml stimulate the proliferative activity of low-grade BC cell lines T47D (luminal A subtype) and the androgen-sensitive PC cell line LNCap in 1.5 and 2.6 times respectively. At the same time, insulin’s physiological concentration did not influence on proliferative potential of high-grade BC cell lines — MDA-MB-231, BCC/P, BC/ML, and PC Du-145. Under conditions of hyperinsulinemia, the level of IPO-38 expression significantly increases in the low malignancy degree PC cell line LNCap, whereas in cells lines of high malignancy degree Du-145 and PC-3, the expression of IPO-38 did not differ significantly from those in the control. There was detected a decrease in luminal A subtype BC cell line T47D proliferative activity under hyperinsulinemia, while cells of the basal subtype tended to increase their proliferation only when cultured with insulin at a concentration of 5 μg/ml. Conclusions: proliferative activity of BC and PC cell lines under the action of insulin depends on their malignancy degree and the insulin concentration in the culture medium