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Identifying the Effects of BRCA1 Mutations on Homologous Recombination using Cells that Express Endogenous Wild-type BRCA1
Published on: February 17, 2011
The tumor suppressor activity induced by adenovirus-mediated BRCA1 overexpression is not restricted to breast cancers
D Marot1, P Opolon, S Brailly-Tabard
1UMR 8121 CNRS, Vectorologie et Transfert de gènes, Institut Gustave Roussy, Villejuif Cedex, France. marot@igr.fr
Abstract:
The BRCA1 (breast cancer 1) breast cancer susceptibility gene is recognized as responsible for most familial breast and ovarian cancers and is suggested to be a tissue-specific tumor suppressor gene. In this report, we investigated the tissue specificity of tumor inhibitory activities induced by a recombinant adenovirus coding for wild-type BRCA1 (wtAdBRCA1). We demonstrated a pronounced in vitro antiproliferative effect on H1299 lung and HT29 colon cells upon infection with AdBRCA1. We describe a prolonged G1 cell cycle arrest associated with a decrease in the hyperphosphorylated form of Rb, suggesting that the Rb/E2F pathway is implicated in BRCA1-induced cell growth arrest. We also observed a significant antitumor effect in these pre-established subcutaneous tumors after in situ delivery of AdBRCA1, although these two tumors do not express wt p53, and also estrogen alpha and beta, progesterone and androgen receptors. Moreover, BRCA1 can induce a strong prolonged cell cycle arrest and apoptotic cell death but no significant antiangiogenic effect in H1299 tumors. Finally, our data indicate that intratumor administration of wtAdBRCA1 significantly inhibits growth of lung and colon steroid hormone-independent tumors.
Insights
The breast cancer susceptibility gene BRCA1 (breast cancer 1) effectively inhibits lung and colon tumor growth. Adenovirus-mediated delivery of BRCA1 induces cell cycle arrest and apoptosis, offering a potential therapy for steroid hormone-independent tumors.
Area of Science:
- Oncology
- Molecular Biology
- Gene Therapy
Background:
- BRCA1 (breast cancer 1) is a key gene linked to hereditary breast and ovarian cancers.
- It is recognized for its role as a tissue-specific tumor suppressor.
- Understanding BRCA1's tumor-inhibitory mechanisms is crucial for developing targeted therapies.
Purpose of the Study:
- To investigate the tissue-specific tumor suppressor activity of wild-type BRCA1 (wtAdBRCA1) delivered via recombinant adenovirus.
- To assess the impact of BRCA1 on cell cycle progression and apoptosis in cancer cells.
- To evaluate the therapeutic potential of BRCA1 in preclinical models of lung and colon cancer.
Main Methods:
- Utilized a recombinant adenovirus encoding wild-type BRCA1 (wtAdBRCA1) for gene delivery.
- Assessed in vitro antiproliferative effects on H1299 lung and HT29 colon cancer cell lines.
- Administered AdBRCA1 intratumorally in established subcutaneous tumors to evaluate in vivo antitumor activity.
- Analyzed cell cycle arrest, apoptosis, and Rb/E2F pathway involvement.
Main Results:
- Demonstrated significant in vitro antiproliferative effects of AdBRCA1 on lung and colon cancer cells.
- Observed a prolonged G1 cell cycle arrest, implicating the Rb/E2F pathway in BRCA1-mediated growth inhibition.
- Showed significant in vivo antitumor effects in established tumors after intratumoral delivery of AdBRCA1.
- Confirmed BRCA1 induces cell cycle arrest and apoptosis but not significant antiangiogenic effects in H1299 tumors.
- Highlighted the efficacy of wtAdBRCA1 against steroid hormone-independent lung and colon tumors.
Conclusions:
- Intratumoral administration of wtAdBRCA1 effectively inhibits the growth of lung and colon tumors.
- BRCA1-induced tumor suppression is mediated through cell cycle arrest and apoptosis, independent of p53 or hormone receptor status.
- These findings support the potential of BRCA1 gene therapy for steroid hormone-independent cancers.
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