In the past funding period we confirmed our major hypothesis that progastrin peptides (PG) exert proliferative/anti-apoptotic/co-carcinogenic effects on intestinal/colonic epithelial cell lines, in vitro and in vivo, and increase the risk of colon carcinogenesis in response to azoxymethane (AOM). Additionally, we made the novel discovery that Annexin II (ANXII) functions as a high affinity receptor for PG and is required for mediating growth factor effects of PG on target cells. An important role of ?-catenin, c-Src, PI3K/Akt, MAPK/ERK and NFkB in mediating growth factor effects of PG on normal and neoplastic intestinal epithelial cells was also identified. Based on these findings, the major hypothesis of our current grant proposal is that ANXII facilitates the activation of one or more of the above indicated kinases/transcription factors in response to PG. Experiments in Aims 1 and 2 will examine this hypothesis.
In Aim 1, PG responsive cell lines, altered for ANX-II expression will be used, as an in vitro model of investigation. For the in vivo studies, we will either use transgenic mice over-expressing PG (Fabp-PG), before or after modulation of ANXII expression. We will either use ANX-II knock out mice, or use specific siRNA for down regulating ANXII expression. In preliminary studies co-localization of PG with ANXII in situ, in cells over-expressing autocrine PG or responsive to exogenous PG was observed. Therefore in Aim 2, pathways mediating intracellular translocation of ANXII/PG, in response to binding of PG to extracellular ANXII (and its functional significance) will be examined;fluorescence based detection techniques and biochemical analysis will be used.
In Aim 3 the clinical relevance of our findings will be examined in a pilot correlative study with samples obtained from patients, consented at the time of colonoscopy or at the time of surgical resection of colonic tumors, at different stages of colon carcinogenesis. Our initial studies strongly implicate PG peptides in the progression of the colon cancer disease. Therefore, understanding the role of ANX-II and the various signaling molecules in mediating the actions of PG are clinically important goals. Data obtained from the above studies will facilitate the development of more effective strategies for targeting the actions of PG for preventative and treatment purposes.
Using mouse models, we observed that high levels of progastrin peptides in the blood increase the risk of developing colon cancer. Annexin 2 was identified as a molecule required for exerting growth effects of progastrin on the cells lining the colons. In the current studies, we will conduct several experiments to confirm if Annexin 2 helps progastrin molecules exert growth effects on colonic cells and if it increases the risk of colon cancer. if we confirm an important role of Annexin 2, then in future studies we will target both Annexin 2 and progastrin for reducing the risk of colon cancer and reducing the growth of established colon tumors in patients.
|Hsu, Chia Wei; Sowers, Mark L; Hsu, Willie et al. (2017) How does inflammation drive mutagenesis in colorectal cancer? Trends Cancer Res 12:111-132|
|Sarkar, Shubhashish; Popov, Vsevolod L; O'Connell, Malaney R et al. (2017) A novel antibody against cancer stem cell biomarker, DCLK1-S, is potentially useful for assessing colon cancer risk after screening colonoscopy. Lab Invest 97:1245-1261|
|Sarkar, Shubhashish; O'Connell, Malaney R; Okugawa, Yoshinaga et al. (2017) FOXD3 Regulates CSC Marker, DCLK1-S, and Invasive Potential: Prognostic Implications in Colon Cancer. Mol Cancer Res 15:1678-1691|
|Huynh, Phuong T; Beswick, Ellen J; Coronado, Yun A et al. (2016) CD90(+) stromal cells are the major source of IL-6, which supports cancer stem-like cells and inflammation in colorectal cancer. Int J Cancer 138:1971-81|
|Singh, Pomila; O'Connell, Malaney; Shubhashish, Sarkar (2016) Epigenetic regulation of human DCLK-1 gene during colon-carcinogenesis: clinical and mechanistic implications. Stem Cell Investig 3:51|
|Kantara, Carla; Moya, Stephanie M; Houchen, Courtney W et al. (2015) Novel regenerative peptide TP508 mitigates radiation-induced gastrointestinal damage by activating stem cells and preserving crypt integrity. Lab Invest 95:1222-33|
|Kantara, Carla; O'Connell, Malaney Ravae; Luthra, Gurinder et al. (2015) Methods for detecting circulating cancer stem cells (CCSCs) as a novel approach for diagnosis of colon cancer relapse/metastasis. Lab Invest 95:100-12|
|O'Connell, Malaney R; Sarkar, Shubhashish; Luthra, Gurinder K et al. (2015) Epigenetic changes and alternate promoter usage by human colon cancers for expressing DCLK1-isoforms: Clinical Implications. Sci Rep 5:14983|
|Kantara, Carla; O'Connell, Malaney; Sarkar, Shubhashish et al. (2014) Curcumin promotes autophagic survival of a subset of colon cancer stem cells, which are ablated by DCLK1-siRNA. Cancer Res 74:2487-98|
|Andey, Terrick; Marepally, Srujan; Patel, Apurva et al. (2014) Cationic lipid guided short-hairpin RNA interference of annexin A2 attenuates tumor growth and metastasis in a mouse lung cancer stem cell model. J Control Release 184:67-78|
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