Expression of gastrin-releasing peptide receptors in endometrial cancer

The Bombesin (BBS)-related peptide, gastrin-releasing peptide, and its cognate receptor are ectopically expressed by many cancers, in which they regulate tumor proliferation and metastasis. But, their role in endometrial cancers is unknown. The purpose of this study was to determine whether endometrial cancer cell lines express functional BBS receptors and to determine whether they were coupled to the regulation of vascular endothelial growth factor (VEGF-A) expression.

Endometrial cancer cell lines (HEC-1A, KLE, and AN3CA) were cultured according to the recommendations of the American Tissue Culture Collection. Ishikawa cells were maintained in Dulbecco's modified Eagle's medium plus 10% fetal bovine serum. Before BBS treatment, all cell lines were placed in serum-free, phenol-free media for 24 hours. BBS-stimulated increases in intracellular Ca(2+) ([Ca(2+)]i) were used to assess functional BBS receptor status. VEGF-A mRNA expression was determined by Northern blotting.

BBS (100 nM) stimulated an increase in [Ca(2+)]i in HEC-1A, Ishikawa, and KLE cells, indicating the presence of functional BBS receptors. This increase did not occur in AN3CA cells. BBS stimulated a time-dependent increase in VEGF-A mRNA expression in Ishikawa and KLE cells. Ishikawa cells exhibited a peak of VEGF-A mRNA expression between 8 and 12 hours with a partial decline by 24 hours. KLE cells showed a relatively small increase at 12 hours. In contrast, HEC-1A cells exhibited a high baseline level of VEGF-A mRNA expression and did not show a response to BBS.

These data demonstrate that endometrial cancer cell lines express functional BBS receptors. In Ishikawa, KLE, and HEC-1A cells, BBS receptors are coupled to the regulation of VEGF-A mRNA expression.