Gonadotropin-releasing hormone analogues alter gene expression of metalloproteinases and their tissue inhibitors in human breast cancer epithelial cells.

Luteinizing hormone-releasing hormone (LHRH or GnRH) is not only produced by hypothalamus, but also by other normal and cancer tissues. GnRH peptide agonists and antagonists inhibit the proliferation of breast cancer cells, but their effect on the expression of metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) has not been studied despite the fact that growth and invasiveness of breast cancer cells in adjacent and distant sites is associated with the expression of MMPs. In the present study, the effects of [D-Leu6, desGly10]GnRH-NHEt (commercially available) and [D-Tic3, Deg6, desGlyl0]GnRH-NHEt on gene expression of MMPs and TIMPs in the breast cancer cell line MCF-7 were examined with semi-quantitative RT-PCR. Results showed that incubation of MCF-7 cells with 30 microM of the synthetic GnRH analogues for 48 h in serum-containing medium resulted in a decrease of MMP-9 expression and increase in MT1- and MT2-MMP mRNA levels. Furthermore, both synthetic analogues induced a significant decrease in TIMP-1 and TIMP-3 mRNA levels and increase in TIMP-2 mRNA levels. The impact of the observed changes on the expression of MMPs and TIMPs warrants further investigation on the effects of GnRH analogues on the invasiveness and metastatic potential of breast cancer cells.