Cellular mechanisms of growth inhibition of human endometrial cancer cell line by an antagonist of growth hormone-releasing hormone.
The expression of growth hormone-releasing hormone (GHRH) and its receptors has been demonstrated in peripheral tissues as well as CNS. Recently, the functional splice variant SV1 of GHRH receptor was identified in various human cancers and cancer cell lines. Although antineoplastic activity of GHRH antagonists has been clearly demonstrated, the mechanism of action is incompletely understood. The objective of this study was the investigation of direct anti-proliferative effect of GHRH antagonist MZ-5-156 on HEC-1A human endometrial cancer cell line and the elucidation of underlying mechanisms. RT-PCR revealed the expression of mRNA for GHRH and SV1 of GHRH receptor in HEC-1A cells. MZ-5-156, at concentrations between 10(-7) and 10(-5) M, had a dose-dependent antiproliferative effect on HEC-1A cells, as determined by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, (MTS) assay. Hoechst 33342 staining and flow cytometric analysis indicated that MZ-5-156, at 10(-6) M, induced apoptosis in HEC-1A cells after 48 h of treatment. Western blot analysis of apoptosis-related proteins demonstrated that treatment with MZ-5-156 (10(-6) M) for 48 h significantly increased the protein levels of Fas, phospho-p53 (Ser46), p53AIP1 (p53-regulated Apoptosis-Inducing Protein 1), and caspase-8, -9, and -3, and decreased the protein level of Bcl-2. These results demonstrate that MZ-5-156 can directly inhibit the proliferation of human endometrial cancer cells, which express mRNA for GHRH and SV1 of GHRH receptor, presumably through the induction of p53-dependent apoptosis coupled with the up-regulation of Fas, phospho-p53 (Ser46), p53AIP1, and caspase-8, -9, and -3, and the down-regulation of Bcl-2.
Zhao
Lin
L
Department of Obstetrics and Gynecology, Faculty of Medicine, The University of Tokyo, Tokyo 113-8655, Japan.
Yano
Tetsu
T
Osuga
Yutaka
Y
Nakagawa
Shunsuke
S
Oishi
Hajime
H
Wada-Hiraike
Osamu
O
Tang
Xiaohui
X
Yano
Naomi
N
Kugu
Koji
K
Schally
Andrew V
AV
Taketani
Yuji
Y
D000231:Adenocarcinoma, Papillary / Q000235:genetics / Q000473:pathology*; D000368:Aged; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D020169:Caspases / Q000235:genetics; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D004353:Drug Evaluation, Preclinical; D016889:Endometrial Neoplasms / Q000235:genetics / Q000473:pathology*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D019254:Genes, bcl-2; D016158:Genes, p53; D013007:Growth Hormone-Releasing Hormone / Q000037:antagonists & inhibitors* / Q000235:genetics; D006801:Humans; D012333:RNA, Messenger / Q000378:metabolism; D018013:Receptors, Neuropeptide / Q000235:genetics / Q000378:metabolism; D018017:Receptors, Pituitary Hormone-Regulating Hormone / Q000235:genetics / Q000378:metabolism; D017337:Sermorelin / Q000031:analogs & derivatives* / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics
D000970:Antineoplastic Agents; C106656:MZ 5-156; D012333:RNA, Messenger; D018013:Receptors, Neuropeptide; D018017:Receptors, Pituitary Hormone-Regulating Hormone; D017337:Sermorelin; D013007:Growth Hormone-Releasing Hormone; D020169:Caspases; C048250:somatotropin releasing hormone receptor