Colon cancer (CRC) is the second leading cause of cancer related deaths in the United States. CRC is marked by aberrantly activated signaling of the nuclear factor of kappaB (NF-kB), a family of transcription factors which regulate wide varieties of cellular processes. Despite recent advances in comprehension of players of NF-kB signaling, deeper understanding of its regulation is imperative for the development of novel cancer therapeutics. Using the powerful validation-based insertional mutagenesis (VBIM) technique, we recently discovered APCLP as a novel negative regulator of NF-kB. The objective of this study is to elucidate the role APCLP in regulating NF-kB signaling in CRC at the molecular and biological levels and to understand the mechanism by which this regulation occurs. To determine the biological effect of APCLP on NF-kB signaling, we used lentiviral vectors to either overexpress or knockdown (shRNA) APCLP in human CRC cell lines (HT-29, HCT116, DLD-1). We show that overexpression of APCLP decreased the NF-kB activity, reduced cellular proliferation, migratory ability, as well as anchorage-independent growth of cells while knockdown of APCLP had an inverse effect. Furthermore, in vivo experiments in a xenograft mouse model confirmed that APCLP overexpression impeded whereas shRNA knockdown promoted tumor growth. To study the mechanism by which APCLP regulated NF-kB signaling, we conducted co-Immunoprecipitation experiments and confirmed that APCLP and the major subunit of NF-kB, p65, may complex or bind directly to each other. Studies are ongoing regarding the mechanism of interaction between APCLP and p65. In summary, discovery of APCLP and understanding of its molecular mechanism and biological function are significant because the knowledge acquired from this study could lead to utilization of APCLP as a potential biomarker and therapeutic target in CRC as well as other cancers that are driven by hyperactivated NF-kB.

Citation Format: Matthew Martin, Rasika Mundade, Tao Lu. Adenomatous polyposis coli like protein (APCLP) functions as a novel negative regulator of NF-kB signaling in colon cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4475.