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Targeting Human Breast Cancer Cells that Overexpress HER-2/neu mRNA by an Antisense Iron Responsive Element

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Annual rept. 1 Jun 2000-31 May 2001

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In this project, we attempt to establish the utility of an sntisense iron-responsive element AS-IRE-mediated gene expression system to targeting HER-2neu-overexpressing breast cancer cells. During the first two years of funding, we have finished the proposed goal stated in Task 1 by identifying the optimal HER-2neu antisense IRE, i.e., AS-IRE4. We demonstrated that AS-IRE4 could interact with IRP-1 and behave as a translational inhibitor when placed in the 5UTR of a gene. In addition, we showed that, using hTERT-AS-IRE4-luc, AS-IRE4 can be regulated by iron in low HER-2neu-expressing MDA-MB-468 cells but such regulation is impaired in high HER-2neu-expressing MDA-MB-453 cells. Thus, this observation is consistent to our working hypothesis that AS-IRE4IRP interaction would be abolished HER-2neu-overexpressing cells. Therefore, our results strongly suggest that AS-IRE4 behaves as a functional IRE. Importantly, we showed that AS-IRE4 could preferentially direct gene expression in HER-2neu-overexpressing breast cancer cells. In that, we demonstrated a preferential reporter gene expression of hTERT-AS-IRE4-luc. Moreover, we showed preferential cell killing in HER-2neu-overexpressing MDA-MB-453 cells using hTERT-AS-IRE4-Bax as opposed to in low HER-2neu-expressing MDA-MB-468 cells Task 2. The identification of AS-IRE4 also facilitates our progress toward the final goal of this project, i.e., to test the therapeutic efficacy of the hTERT- AS-IRE4-luc in a pre-clinical gene therapy model Task 3. We will use adenoviral vector and liposome as delivery systems to deliver hTERT-AS-IRE4-luc into the tumor-bearing mice. Treatment efficacy will be measured in terms of tumor-specific as well as HER-2neu overexpression-specific targeting, tumor size, survival, and metastatic lesions. Treatment efficacy between liposome- and adenovirus-mediated gene therapy will also be compared.

Subject Categories:

  • Biochemistry
  • Medicine and Medical Research

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