Involvement of annexin V in antiproliferative effects of gonadotropin-releasing hormone agonists on human endometrial cancer cell line

We studied the involvement of annexin V in the antiproliferative effects of gonadotropin-releasing hormone (GnRH) agonists on human endometrial cancer cell line HHUA. HHUA cell line expressed mRNA for GnRH receptors as assessed by reverse transcriptase-PCR with oligonucleotide primers. In the presence of buserelin, the proliferation of this cell line was significantly (P < 0.01) reduced to 60% of control after 72 hr. Peak intracellular concentrations of annexin V, equivalent to about twice the control value, were obtained after 48 hr exposure to buserelin. Intracellular annexin V concentration was increased not only by buserelin, but also by protein kinase C (PKC) activator. However, there was no increase in intracellular annexin V concentration when cells were incubated with PKC inhibitor before the addition of buserelin. The results suggest that GnRH agonists inhibit cell proliferation by increasing intracellular concentrations of annexin V, an effect mediated by the activation of PKC. (C) 1997 Academic Press.