[Influence of long-term treatment with MPA on the biological character of endometrial carcinoma Ishikawa cell].

The study was undertaken to investigate the effect of long-term treatment with MPA on the growth and invasiveness of endometrial carcinoma Ishikawa cells and the expression of the subtype of estrogen receptor and progesterone receptor. The human endometrial carcinoma Ishikawa cells were continually exposed to 2.5 micromol/L step-wise increase of MPA. MTT assay, flow cytometry and Matrigel invasion assay were used to detect the effect of MPA on the growth, cell cycle distribution and the invasion capability of the cells respectively. RT-PCR was performed to detect the changes of CyclinD1, MMP2 and MMP9 over different time treatment of MPA. Immunocytochemistry was used to examine the expression of estrogen receptor subtype and progesterone receptor subtype. Endometrial carcinoma Ishikawa cells became resistant to the inhibitory effect of MPA over ten months MPA treatment. The cells resistant to the growth inhibitory effect were named progestin-resistant Ishikawa cells and the cells which the progestin-resistant originated from were named the parent Ishikawa cells. The effects of MPA shifted from growth and invasiveness inhibitory effects on the parent Ishikawa cells to stimulatory effect on the progestin-resistant Ishikawa cells. Consistent with the phenomena, the treatment with MPA on Ishikawa cells resulted in statistically significant decreases of CyclinD1, MMP2 and MMP9 gene expression, reversely, the treatment with MPA on the progestin-resistant Ishikawa cell resulted in statistically significant increases of CyclinD1, MMP2, MMP9 gene expression. Immunocytochemical analysis showed reduced ERalpha and PR-B expression and increased ERbeta expression in the progestin-resistant Ishikawa cells compared with parental Ishikawa cells. From the experiment, it was concluded that the prolonged treatment with MPA on Ishikawa cell could give rise of the resistant effect of MPA, the effect of MPA on the growth and invasiveness capability of endometrial carcinoma shifted from inhibitory to stimulatory. The imbalance of ER subtype and PR subtype might contribute to the mechanisms involved in the progesterone resistance over long-term MPA treatment.