Abstract 3018: Gonadotropin-releasing hormone type II (GnRH-II) agonist regulates the invasiveness of endometrial cancer cells through GnRH-I receptor and mitogen-activated protein kinases (MAPKs)-dependent activation of matrix metalloproteinase (MMP)-2
Authors: Wu Hsien-Ming , Chao Angel , Wang Tzu-Hao , Wang Hsin-Shih , Huang Hong-Yuan , Lee Chyi-Long , Soong Yung-Kuei , Leung Peter C.K. 
Published: August 2012

Introduction: More than 25% of patients diagnosed with endometrial carcinoma have an invasive primary cancer accompanied by metastases. The GnRH has an important role in reproduction. In mammals, GnRH-II is more widely identified than GnRH-I in peripheral tissues. GnRH-II may regulate tumor progression of endometrial cancer. MAPKs have been considered important components of GnRH-induced signaling pathways. MMPs are largely implicated in promoting angiogenesis and tumor metastasis. In the present study, we examined the action of GnRH-II agonist-promoted motility of endometrial cancer cells and the mechanisms of the action in endometrial cancer. Materials and methods: Endometrial cancer cell line Ishikawa and ECC-1 were derived from an endometrial adenocarcinoma. D-Arg6, AzaGly10-GnRH II was a synthetic decapeptide. Cell motility was estimated by invasion and migration assay. The activities of MMP-2 was assessed by gelatin zymography. Immunoblot analysis was done to study the expression of GnRH-I receptor and the effects of GnRH-II agonist in the activation of ERK1/2, JNK and MMP-2. ERK1/2 inhibitor (U0126), and JNK inhibitor (SP600125) were pretreated for 30 min to evaluate the effects of MAPKs. MMP-2 inhibitor (OA-Hy) was pretreated for 30 min to evaluate the effects of MMP-2 in cell motility. Human GnRH-I receptor siRNA was used to knock down the expression of GnRH-I receptor. Results: The GnRH-I receptor was expressed in endometrial cancer cells. The GnRH-II agonist promoted cell motility in a dose-dependent manner. GnRH-II agonist activated the phosphorylation of ERK1/2 and JNK signaling and the phosphorylation was abolished by 1μM U0126 and 1μM SP600125. GnRH-II agonist-promoted cell motility was suppressed in cells pretreated with U0126 and SP600125. Moreover, U0126 and SP600125 abolished GnRH-II agonist-induced activation of MMP-2. Inhibition of MMP-2 with 10μM OA-Hy suppressed cell motility in response to GnRH-II agonist. GnRH-II agonist-mediated cell motility was suppressed by knockdown of endogenous GnRH-I receptor with siRNA. Conclusion: Our results confirmed that GnRH-I receptor may be a common receptor that mediates the effects of both GnRH-I and GnRH-II in endometrial cancer cells. Our study shows that the GnRH-II agonist promoted the cell motility of endometrial cancer cells through the GnRH-I receptor, and the phosphorylation of ERK1/2 and JNK-dependent activation of MMP-2. Our findings represent a new concept regarding the mechanisms of GnRH-II-promoted cell motility in endometrial cancer cells, suggesting the possibility of GnRH-II as a potential therapeutic intervention for the treatment of human endometrial cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3018. doi:1538-7445.AM2012-3018