Combination treatment of tetraiodothyroacetic acid (tetrac), an antagonist of integrin αvβ3, and cetuximab, an EGFR monoclonal antibody, on triple negative breast cancer cells in a perfusion bellows cell culture system has shown promising anti-proliferative activity compared to that of single agent. Mutations of the adenomatous polyposis coli (APC), K-ras, and β-catenin genes are defined as early events in colorectal tumorigenesis. However, the relationship among them is unclear. Using the combination treatment of two agents which are involved in different mechanisms of anti-proliferation against colorectal cancer, we will investigate the relationships among K-ras, APC and β–catenin and explore new regime of treatment of colorectal cancer. Outstanding issues to be addressed in the present studies are: a) signal transduction pathways and patterns of gene expression (gene signatures) in colorectal cancer cells with different APC status in vitro during cetuximab treatment in the presence or absence of tetrac; b) mechanisms of tetrac facilitating cetuximab-induced anti-proliferation; c) establishment of pharmacodynamic modeling of cetuximab and Tetrac in a new in vitro perfusion cell culture system; d) confirmation of observations from (a) to (c) in xenografted human colorectal cancer cells and utilization of the results from (c) to determine the initial dosing regimens. The SPECIFIC AIMS are: 1. To establish mechanisms by which tetrac treatment enhances cetuximab-induced anti-proliferation in human colorectal cancer cells with different APC status; 2. To develop pharmacodynamic (PD) modeling for tetrac- and cetuximab-induced anti-proliferation in colorectal cancer cells with different APC status; and 3. To verify that the observed potentiation effects of tetrac on cetuximab-induced anti-proliferation are also demonstrated in murine xenografts. The Methods used in support of the Aims will include: (i) suppression of integrin αvβ3 expression by siRNA to identify the critical role of integrin αvβ3 in cetuximab-induced anti-proliferation. Phosphorylation statuses of signal proteins will be examined; (ii) RT-PCR and immunoblotting of integrin αvβ3 and signal proteins in cetuximab-treated cells with or without tetrac as well as TUNEL (iii) RT-PCR, immunoblotting, and ChIP assays to identify expression levels/interactions with PTEN, and HIF-1α after suppression of CBY1 expression (Aims 1 and 2); (iv) Affymetrix arrays to identify gene signatures in cells treated with tetrac and/or cetuximab; (v) determination of PD of cetuximab, tetrac and their combination treatment in a perfusion cell culture system (Aim 2) in preparation for (vi) xenograft studies to confirm the effects of cetuximab on tetrac-induced anti-proliferation (Aim 3). By understanding the mechanisms behind the anti-proliferative actions of cetuximab and tetrac, both separately and combined, we can advance new treatment approaches to colorectal cancers with different APC status.
|Effective start/end date||8/1/14 → 7/31/15|
- colorectal cancer
- combination treatment
- Adenomatous polyposis coli (APC)
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