Related Experiment Videos
Targeting HER-2/neu-overexpressing breast cancer cells by an antisense iron responsive element-directed gene
1Department of Molecular and Cellular Oncology, The University of Texas, M. D. Anderson Cancer Center, 1515 Holcombe Blvd., Houston, TX 77030, USA.
Abstract:
Overexpression of HER-2/neu proto-oncogene is found in many human cancers including 20-30% of breast cancer and is a predictor of poor prognosis. To target breast cancer cells that overexpress HER-2/neu mRNA, we previously described a novel strategy that combines the principle of antisense (AS) and translational inhibitory activity conferred by an iron-responsive element (IRE) (AS-IRE). Here, we showed that three potential AS-IREs, i.e. AS-IRE1, 4, and 5, derived from HER-2/neu antisense sequence could bind endogenous iron regulatory protein (IRP) and, when placed in 5' untranslated region (5'UTR) of a reporter gene, the gene expression could be translationally repressed by recombinant IRP in vitro. Using AS-IRE4 as our model, we demonstrated that it is regulated by iron, and importantly, such regulation is impaired in HER-2/neu-overexpressing breast cancer cells. Furthermore, we showed that AS-IRE4 could preferentially direct the expression of a reporter gene in HER-2/neu-overexpressing breast cancer cells. Interestingly, when AS-IRE4 was placed in 5'UTR of Bax gene, a pro-apoptotic protein in the Bcl-2 protein family, we observed a preferential cell killing in breast cancer cells that overexpress HER-2/neu. Taken together, our results suggest that AS-IRE behaves as a functional IRE and it may direct therapeutic gene expression to preferentially target HER-2/neu-overexpressing breast cancer cells.
Insights
This study introduces a novel antisense-iron-responsive element (AS-IRE) strategy to target HER-2/neu-overexpressing breast cancer cells. AS-IRE4 preferentially directs gene expression and induces cell death in these specific cancer cells.
Area of Science:
- Oncology
- Molecular Biology
- Gene Therapy
Background:
- HER-2/neu proto-oncogene overexpression is prevalent in breast cancer, correlating with poor prognosis.
- Targeting HER-2/neu-overexpressing breast cancer cells remains a critical challenge in oncology.
Purpose of the Study:
- To develop a novel therapeutic strategy targeting breast cancer cells overexpressing HER-2/neu.
- To investigate the potential of antisense-iron-responsive element (AS-IRE) constructs for targeted gene therapy.
Main Methods:
- Designed and synthesized three AS-IRE constructs (AS-IRE1, 4, and 5) from HER-2/neu antisense sequences.
- Evaluated the binding of AS-IREs to iron regulatory protein (IRP) and their translational repression activity in vitro.
- Assessed the iron-regulation of AS-IRE4 and its preferential gene expression in HER-2/neu-overexpressing breast cancer cells.
- Investigated the therapeutic potential of AS-IRE4 by placing it in the 5' untranslated region (5'UTR) of the Bax gene.
Main Results:
- AS-IREs bound endogenous IRP and repressed reporter gene expression in vitro.
- AS-IRE4 demonstrated iron-dependent regulation, which was impaired in HER-2/neu-overexpressing breast cancer cells.
- AS-IRE4 preferentially directed reporter gene expression in HER-2/neu-overexpressing breast cancer cells.
- Expression of Bax via AS-IRE4 led to preferential cell killing in HER-2/neu-overexpressing breast cancer cells.
Conclusions:
- AS-IRE constructs function as effective iron-responsive elements.
- AS-IRE technology offers a promising approach for targeted gene therapy in HER-2/neu-overexpressing breast cancer.
- This strategy may enable preferential therapeutic gene delivery to specific cancer cells.