Previous Article | Next Article ![]()
Molecular and Cellular Biology, October 2001, p. 6895-6905, Vol. 21, No. 20
Laboratory of Molecular Carcinogenesis,
National Institute of Environmental Health Sciences, National
Institutes of Health, Research Triangle Park, North Carolina
277091; Department of Internal Medicine,
Saitama Medical Center, Kawagoe, Saitama 350, Japan2; and Division of Basic Medical
Sciences, Mercer University School of Medicine, Macon, Georgia
312073
Received 28 September 2000/Returned for modification 1 December
2000/Accepted 19 July 2001
An in vitro transformation system of carcinogen-treated Syrian
hamster embryo (SHE) cell cultures represents multistep genetic and
nongenetic changes that develop during the neoplastic progression of
normal cells to tumor cells in vivo. During this neoplastic progression, SHE cells demonstrate an altered response to
epidermal growth factor (EGF). In the present report, we examined the
role of the adapter protein Gab1 (Grb2-associated binder-1) in the neoplastic progression of SHE cells. We used two asbestos-transformed SHE cell clones in different neoplastic stages: a 10W+8 clone, which is
immortal and retains the ability to suppress the tumorigenicity of
tumor cells in cell-cell hybrid experiments, and a 10W
0270-7306/01/$04.00+0 DOI: 10.1128/MCB.21.20.6895-6905.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Expression of Gab1 Lacking the Pleckstrin
Homology Domain Is Associated with Neoplastic Progression
1 clone, which has lost this tumor suppressor ability. 10W+8 cells expressed full-length 100-kDa Gab1 and associated 5.2-kb mRNA. Upon repeated cell passaging, 10W
1 cells showed increasing expression of a novel
87-kDa form of Gab1 as well as 4.6-kb mRNA with diminishing expression
of the original 100-kDa Gab1. cDNA encoding the 87-kDa Gab1
predicts a form of Gab1 lacking the amino-terminal 103 amino acids
(Gab1
1-103), which corresponds to loss of most of the
pleckstrin homology (PH) domain. Gab1
1-103 retains the
ability to be phosphorylated in an EGF-dependent manner and to
associate with the EGF receptor and SHP-2 upon EGF stimulation. The
endogenous expression of Gab1
1-103 in 10W
1 cells
appeared closely related to EGF-dependent colony formation in soft
agar. Moreover, transfection and expression of
Gab1
1-103, but not Gab1, in 10W+8 cells enhanced their
EGF-dependent colony formation in soft agar. These results demonstrate
that Gab1 is a target of carcinogen-induced transformation of SHE cells
and that the expression of a Gab1 variant lacking most of the PH domain plays a specific role in the neoplastic progression of SHE cells.
*
Corresponding author. Mailing address: Laboratory of
Molecular Carcinogenesis, National Institute of Environmental Health Sciences/NIH, P.O. Box 12233, Research Triangle Park, NC 27709. Phone:
(919) 541-3911. Fax: (919) 541-0146. E-mail:
Eling{at}niehs.nih.gov.
This article has been cited by other articles:
| J. Bacteriol. | J. Virol. | Eukaryot. Cell |
|---|
| Microbiol. Mol. Biol. Rev. | Clin. Vaccine Immunol. | All ASM Journals |
|---|