Growth hormone-releasing hormone antagonist induces apoptosis of human endometrial cancer cells through PKCδ-mediated activation of p53/p21

Hsien Ming Wu, Andrew V. Schally, Jung Chien Cheng, Marta Zarandi, Jozsef Varga, Peter C.K. Leung

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

The growth hormone-releasing hormone (GHRH) antagonists have been shown to inhibit growth of human cancer cells, but the underlying molecular mechanisms and their actions have not been fully investigated. In this study, we first showed that GHRH-R splice variant 1 (SV1) was expressed in two human endometrial cancer cell lines, Ishikawa and ECC-1. By using MTT assay, immunoblotting for cleaved caspase-3 and TUNEL assays, we found that cell growth inhibition and apoptosis were induced in GHRH antagonist, JMR-132-treated cells by activating PKCδ and could be inhibited by treatment with PKC inhibitor, GF109203X. In addition, activation and protein expression of p53 as well as the expression of its downstream effector, p21, were increased by JMR-132 treatment. Moreover, JMR-132-induced p53 and p21 expression were diminished by treatment with PKC inhibitor. Knockdown of endogenous p53 and p21 by siRNAs abolished the JMR-132-induced cell growth inhibition and apoptosis. This study demonstrates a novel mechanism in which GHRH antagonist-induced cell growth inhibition and apoptosis through PKCδ-mediated activation of p53/p21 in human endometrial cancer cells. These findings may suggest the feasibility of GHRH antagonists as a therapeutic approach for human cancer.

Original languageEnglish (US)
Pages (from-to)16-25
Number of pages10
JournalCancer letters
Volume298
Issue number1
DOIs
StatePublished - Dec 1 2010

Keywords

  • Apoptosis
  • Endometrial cancer
  • Growth hormone-releasing hormone
  • P21
  • P53
  • PKCδ

ASJC Scopus subject areas

  • Cancer Research
  • Oncology

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