Differential functions of growth factor receptor-bound protein 7 (GRB7) and its variant GRB7v in ovarian carcinogenesis.
OBJECTIVE
Aberrant overexpression of growth factor receptor-bound protein 7 (GRB7) and its variant GRB7v has been found in numerous human cancers. The goal of this study was to characterize the functions of GRB7 and GRB7v in the ovarian carcinogenesis and to investigate the differential roles of GRB7 and GRB7v in the modulation of signaling pathways.


METHODS
Quantitative reverse transcription-PCR, Western blot, and immunohistochemical analyses were used to evaluate the levels of GRB7 and GRB7v. The cellular localization, functions, and signaling pathways regulated by GRB7 and GRB7v were investigated by enforced expression of GRB7 and GRB7v.


RESULTS
Quantitative reverse transcription-PCR and Western blot analyses showed that GRB7 and GRB7v were frequently upregulated in ovarian cancer samples. The overexpressed GRB7 (P = 0.009) and GRB7v (P = 0.017) were significantly correlated with high-grade ovarian cancer. Immunohistochemical analysis on ovarian cancer tissue array confirmed that the upregulated GRB7 was significantly correlated with high-grade ovarian cancer (P = 0.001). Confocal microscopy analysis showed that GRB7 and GRB7v predominately localized in cytoplasm of ovarian cancer cells, consistent with their roles as signaling adaptors. Enforced expression of GRB7 promoted cell proliferation, migration, and invasion, whereas GRB7v only increased cell proliferation and anchorage-independent growth ability. With the treatment of specific kinase inhibitors, we showed that both GRB7 and GRB7v promoted cell proliferation through activating extracellular signal-regulated kinase signaling, whereas GRB7 enhanced cell migration/invasion by activating c-Jun NH(2) terminal kinase signaling.


CONCLUSIONS
Our studies implicate that the overexpressed GRB7 and GRB7v are associated with high-grade tumors and exert distinct tumorigenic functions through regulating different signaling pathways in ovarian cancer cells.
Wang
Yajun
Y
Department of Obstetrics and Gynecology, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, People's Republic of China.
Chan
David W
DW
Liu
Vincent W S
VW
Chiu
Pm
P
Ngan
Hextan Y S
HY
D017398:Alternative Splicing; D000873:Anthracenes / Q000494:pharmacology; D015153:Blotting, Western; D002070:Butadienes / Q000494:pharmacology; D002460:Cell Line; D045744:Cell Line, Tumor; D002465:Cell Movement; D049109:Cell Proliferation; D002470:Cell Survival; D005260:Female; D051382:GRB7 Adaptor Protein / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D015972:Gene Expression Regulation, Neoplastic; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D018613:Microscopy, Confocal; D008875:Middle Aged; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D009367:Neoplasm Staging; D009570:Nitriles / Q000494:pharmacology; D010051:Ovarian Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D014162:Transfection
D000873:Anthracenes; D002070:Butadienes; C495955:GRB7 protein, human; D009570:Nitriles; D020033:Protein Isoforms; C113580:U 0126; D049452:Green Fluorescent Proteins; D051382:GRB7 Adaptor Protein; C432165:pyrazolanthrone; D051057:Proto-Oncogene Proteins c-akt; D020928:Mitogen-Activated Protein Kinases