2012-08-012024-05-13https://scholars.lib.ntu.edu.tw/handle/123456789/645534摘要：大腸直腸癌已躍居世界上癌症死亡率第二名，屬於固體型腫瘤，缺氧常見於此類腫瘤，並誘發HIF-1α 表現而導致抗藥性及預後較差，因此抑制HIF-1α 被視為新的抗癌策略。Zebularine (Zeb)是較穩定之DNA methyltransferase (DNMT)抑制劑，可殺死癌細胞而不影響正常細胞，對小鼠也不具毒性。我們初步結果顯示，Zeb 可抑制人類大腸癌細胞株HCT116 之HIF-1α表現，代表Zeb 是治療大腸直腸癌之潛力藥物。我們的初步也證明Zeb對HCT116具毒殺性，對小鼠大腸癌也有療效。細胞自我吞噬(autophagy)是指細胞在惡劣環境下，經由吞噬細胞內物質產生能量渡過外界壓力的一種保護機制；也有研究報導指出，藥物會誘導癌細胞產生autophagy，造成細胞過度吞噬其內容物而死亡，因此，autophagy在癌細胞為保護或是引發毒殺作用，目前仍無定論。缺氧也會透過HIF-1α 導致autophagy 而促進細胞存活，但嚴重缺氧或無氧狀態則可透過活化AMPK及unfolded protein response (UPR)造成autophagic cell death。我們初步結果顯示，除抑制HIF-1α 表現外，Zeb 也可活化AMPK、UPR/ER stress、以及autophagy，因此我們推測Zeb 可在缺氧狀態下，促進autophagic cell death。3 年內我們將執行4 項目標：(1) 探討Zeb 在各種癌細胞及活體模式之抗癌作用。（第一年）(2) 研究Zeb 抑制HIF-1α表現之分子機轉。（第一年到第二年）(3) 研究Zeb 誘發autophagy之分子機轉。（第二年到第三年）(4) 探討Zeb 對缺氧導致抗藥性之作用。（第三年）<br> Abstract: Colorectal cancer (CRC) is the second leading cause of cancer-related death in malesand females in the world. Hypoxia and accumulation of hypoxia-inducible factor HIF-1α insolid tumor tissues, including CRC, have been reported to associate with resistance toanticancer therapy and poor prognosis. Therefore, targeting HIF-1α might provide clinicalbenefits to CRC. Zebularine (Zeb), a stable DNA methyltransferase (DNMT) inhibitor, hasbeen shown to preferentially kill cancer cells and exhibits low toxicity in normal cells andmice. Our preliminary results demonstrated that Zeb inhibit HIF-1α expression humancolorectal HCT116 cells, suggesting that Zeb might have clinical activity toward CRC.Indeed, Zeb showed anticancer effect in HCT116 cells and in mice colitis-associated coloncancer. Autophagy is a physiological process involved in the turnover of proteins orintracellular organelles. It serves as a temporary survival mechanism during starvation whereself-digestion becomes an alternative energy source. It has been recently reported thatHIF-1α-dependent autophagy protects cells from anticancer drug-induced apoptosis inhypoxia. However, severe hypoxia or anoxia could induce HIF-1α-independent autophagiccell death through activation of AMPK and unfolded protein response (UPR). In addition toHIF-1α inhibition, Zeb also induced AMPK activation, UPR/ER stress and autophagy inHCT116 cells. Therefore, we hypothesized that Zeb treatment will switch HIF-1α-dependentcytoprotective autophagy to HIF-1α-independent autophagic cell death in hypoxia, whichcould abrogate hypoxia-induced anticancer drug resistance. In this four-year research project,we plan to incorporate the preliminary results to test the following SPECIFIC AIMS:(1) To investigate the in vitro and in vivo anticancer effect of Zeb toward colorectal cancers.(Year 1)(2) To elucidate the molecular mechanisms of Zeb-mediated HIF-1α inhibition. (Year 1~2)(3) To elucidate the molecular mechanisms of Zeb-induced autophagy. (Year 2~3)(4) To investigate the effect of Zeb on hypoxia-mediated drug resistance. (Year 3)