Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P04626 (erbB-2)
 5,251 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Overexpression of neu (also known as c-erbB-2 or HER-2) commonly occurs in human cancer and is also known to enchance tumor metastasis and chemoresistance. Our earlier reports showed that the adenovirus 5 E1A can suppresss the neu-mediated transformation by repression of neu. Thus, E1A has the potential to be used as a therapeutic agent against the neu-overexpressing human cancers. However, a serious concern to this approach is that E1A is also capable of immortalizing primary culture cells and can co-operate with ras or E1B oncogenes to transform them. The E1A CR2 domain (amino acid residues 120 to 140) necessary for binding to RB is believed to be required for this oncogenic function. Here, we report that deletion of CR2 region did not affect E1A's capability to repress neu. Interestingly, deletion of the amino acid residues 4 to 25 or 40 to 80 completely disrupted E1A-mediated neu repression. By deleting the amino acid residues from 81 to 185, we have successfully generated a mini-E1A mutant that was sufficient to inhibit neu promoter activity and suppress neu-mediated transformation. The mini-E1A mutant does not contain the CR2 domain that is crucial for RB binding and immortalization, and hence, may serve as a more selective tumor suppressor, and a safer therapeutic agent. It may also be a useful tool to further investigate the molecular mechanism(s) of neu overexpression and E1A-mediated transcriptional repression in cancer cells.
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PMID:Mapping of adenovirus 5 E1A domains responsible for suppression of neu-mediated transformation via transcriptional repression of neu. 915 Mar 63

We are currently conducting clinical trials of E1A gene therapy for patients with ovarian cancer. The adenovirus type 5 E1A gene suppresses growth of ovarian cancer cells that overexpress HER-2/neu (HER2) and growth of some--but not all--that express low HER2. In HER2-overexpressing cells, suppression by E1A is predominantly by down-regulation of HER2, but the mechanism in low HER2-expressing cells is not fully understood. The adenoviral E1B protein has sequential and functional homology to Bcl-2 and prolongs the viability of adenovirus host cells by inhibiting E1A-induced apoptosis. Bcl-2 is overexpressed in ovarian cancer and participates in chemoresistance; we hypothesized that Bcl-2 inhibits E1A-induced apoptosis leading to resistance to E1A gene therapy. E1A suppressed colony formation of ovarian cancer cells that express low levels of Bcl-2 and HER2 (OVCAR-3 and OVCA 433), but enhanced colony formation in low HER2-, high Bcl-2-expressing ovarian cancer cells (2774 and HEY). Treating 2774 or HEY cells with antisense oligonucleotide Bcl-2 (Bcl-2-ASO) did not reduce cell viability. E1A combined with Bcl-2-ASO led to significant decreases in cell viability resulting from increased apoptosis relative to cells treated with E1A alone (P < 0.05). The increase in apoptosis was partly due to cytochrome c release and subsequently caspase-9 activation by Bcl-2-ASO. Finally, in an ovarian cancer xenograft model, treatment with Bcl-2-ASO did not prolong survival, but E1A plus Bcl-2-ASO did (P < 0.001). In conclusion, ovarian tumors overexpressing Bcl-2 may not respond well to E1A gene therapy, but treatment with a combination of E1A and Bcl-2-ASO may overcome this resistance.
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PMID:Bcl-2 antisense oligonucleotide overcomes resistance to E1A gene therapy in a low HER2-expressing ovarian cancer xenograft model. 1616 19