DESCRIPTION (provided by applicant): Despite recent advances in clinical management, the molecular complexity of triple-negative breast cancers (TNBC) and therapy-associated side effects often limit effectiveness of many therapies. Development of new and improved strategies for TNBC treatment remains urgent. We previously discovered an apoptosis regulatory protein CARP-1/CCAR1. CARP-1 functions to transduce cell growth as well as chemotherapy (adriamycin, etoposide, or Iressa)-dependent inhibitory signaling. CARP-1 expression correlates inversely with breast cancer tumor grades. A yeast-two-hybrid screen together with co-immuno-precipitation analyses revealed that CARP-1 binds with the anaphase-promoting complex (APC/C) E3 ubiquitin ligase subunit APC-2, cytoskeletal scaffold filamin C , and apoptosis-transducing DEDD2 proteins. High-throughput screening of a chemical library yielded inhibitors of CARP-1:APC-2 binding termed CARP-1 functional mimetics (CFMs). Lead compound CFM-4 binds CARP-1, stimulates CARP-1 expression and apoptosis. CFM-4 inhibits TNBC cell growth in vitro and in vivo. CFM-4 also attenuates growth of tamoxifen (TAM) or adriamycin (ADR)-resistant breast cancer cells without inhibiting growth of the non-tumorigenic and immortalized mammary epithelial MCF-10A cells. Our on-going studies further revealed that (1) CARP-1 is a part of filamin/c-jun N-terminal kinase (JNK) proteome, and JNK2 regulates apoptosis by ADR or CFM-4, (2) CFM-4.16, a novel CFM-4 analog, enhances ADR inhibition of TNBC cells, (3) CFM-4 and its analogs function in part by elevating CARP- 1 and DEDD2 levels, and promote apoptosis by activating JNKs and caspases-8/9/3, and attenuate TNBC cell migration and invasion, and (4) CARP-1 depletion blocks breast cancer cell growth inhibition by CFMs or ADR. Hypothesis: CARP-1, a peri-nuclear phospho-protein, is a key regulator of apoptosis by ADR or CFMs, and that modulation CARP-1 and its signaling by these agents is a novel mechanism for treating TNBCs and other breast cancers. Objectives: Elucidation of mechanisms of CARP-1-dependent breast cancer growth inhibition, and exploitation of this knowledge to develop anti-breast cancer agents are our long-term goals. Loss of p53 promotes development of aggressive breast cancers and development of ADR-resistant TNBCs remains a formidable problem in clinic. The facts that CARP-1 is a co-activator of p53 while CFMs that bind and elevate CARP-1 also inhibit ADR-resistant breast cancer cells, apoptosis-stimulating functions of CARP-1 could compensate for loss of p53, especially in TNBCs and their drug-resistant variants that lack functional p53. Together with our brief findings listed above, the current preliminary studies provide a strong rationale to test our hypothesis by: (1) Investigating molecular mechanism(s) of filamin-CARP-1 binding, and determining the extent to which JNK/CARP-1-dependent apoptosis regulates TNBC growth for optimal efficacy of ADR or CF...