The retinoblastoma gene functions as a growth and tumor suppressor in human bladder carcinoma cells.
AUTOR(ES)
Takahashi, R
RESUMO
The product of the human retinoblastoma gene (RB) is a nuclear phosphoprotein that is thought to function as a tumor suppressor. Mutations of RB frequently occur in human bladder carcinoma. To investigate the significance of the functional loss of this gene in bladder cancer, an RB expression plasmid (pBARB) under control of the human beta-actin promoter was transfected into the bladder carcinoma cell line HTB9, which lacks RB expression. Marker-selected transfectants that expressed RB protein were identified by immunoblotting and immunohistochemical staining. In selected clones, stable RB expression has persisted over 1 yr under standard culture conditions with 10% serum. However, RB expression caused major alterations of HTB9 growth properties both in vitro and in vivo. RB+ transfectants lacked the ability to form colonies in semi-solid medium, and their growth rate was significantly decreased in 3% serum. In addition, the tumorigenicity of these transfectants was markedly decreased. Tumors that formed in nude mice were much smaller and had a longer latency period but were indistinguishable microscopically from those produced by parental cells. Slower growing tumors were RB+, as measured by nuclear staining of their RB protein and by a normal RB protein pattern on immunoblots. These findings support the concept that the RB gene acts as both a growth and tumor suppressor in bladder cancer cells.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=51851Documentos Relacionados
- Oncogenes in human tumor cell lines: molecular cloning of a transforming gene from human bladder carcinoma cells.
- Further characterization of retinoblastoma gene-mediated cell growth and tumor suppression in human cancer cells.
- The IL-12Rβ2 gene functions as a tumor suppressor in human B cell malignancies
- Role of a tumor-suppressor gene in the negative control of anchorage-independent growth of Syrian hamster cells.
- Basic fibroblast growth factor as a growth inhibitor for cultured human tumor cells.