Development of Novel Therapeutic Agents for Breast Cancer through Targeting Nicotinic Acetylcholine Receptors.

Our recent study (J Natl Cancer Inst, 102, 1322-1335, 2010) demonstrated that thealpha 9-nicotinic receptor (alpha 9-nAChR) was detected at a higher level in breast tumor tissues (tumor/normal >8 fold, n=276). Our data show that higher levels of alpha 9-nAChR were detected in advanced tumor (stages 3-4) tissues. Previous studies indicated that poor response to anticancer drugs, such as Trastuzumab (Herceptin®), was preferentially found in advanced-stage patients. Our preliminary data demonstrated that an alpha 9-nAChR/HER-2 complex, detected by Förster resonance energy transfer (FRET), was found in the SK-BR3-Rcells. Such results motivated us to study the potential mechanisms of alpha 9-nAChR /HER-2 complex formation in Herceptin resistant tumor cells, which could potentially be used to overcome drug resistance in Herceptin-treated patients. Three steps of alpha 9-nAChR targeted drugs were set for breast cancer therapeutic application. First step, we found small interring RNA (siRNA) of alpha 9-nAChR significant reduced breast cancer growth in vivo and in vitro. Secondly, in the first year of this study, RgIA (a small peptide alpha 9-nAChR antagonist) was proved to inhibit nicotine induced breast tumor proliferation through obtaining alpha 9-nAChR activity regulation. In the third step, we want to develop humanized alpha 9-nAChR-specific antibody to provide a novel breast cancer therapy for either breast cancer or Herceptin resistance breast cancer patients. Our three-year proposal will be completed in the following aims: Year 1: Searching for therapeutic agents that will overcome alpha 9-nAChR/HER-2 complex formation in Herceptin-resistant breast cancer cells Aim 1: Investigation the relationship between alpha 9-nAChR expression and Herceptin resistance breast cancers. Aim 2: Investigation the mechanism of RgIA inhibits breast cancer stem cells population. Year 2: Animal model for studying the antitumor effects of alpha 9-nAChR antibody on breast cancer and Herceptin-resistant breast cancer tumors. Aim 3: alpha 9-nAChR specific anti breast tumor antibody construction and humanization development. 1.Discoverying the the most effective anti breast tumor alpha 9-nAChR-specific antibody from antibody clones. 2.Buding the correlaction of antibody binding affinity and anti tumor effect on various breast cancer cells. 3.Optimizing monoclonal alpha 9-nAChR antibody to reduced immune response by using selective modification and humanized process. 4.Using highly complicity human antibody library as a tool to screen humanized alpha 9-nAChR antibody. 5.Complete the assessments of acute-toxicity of 14/28 days and tumor efficacy test.