Abstract 3865: ATOH8 depletion can reprogram noncancer stem cells into cancer stem cells

Abstract

Abstract Introduction: The development of hepatocellular carcinoma (HCC), one of the most lethal of human malignancies, is caused by the accumulation of multiple genetic and epigenetic alterations. Recent advances in cancer stem cell (CSC) study have associated the poor prognosis of cancer with CSC. ATOH8 is a nucleus factor with an obvious structural similarity to the Drosophila proneural gene atonal. The aim of this study is to investigated the role of ATOH8 in CSC and its therapeutic potentials for HCC treatment. Experimental procedures: The clinical significance of ATOH8 in a cohort of 242 HCC cases was assessed by clinical correlation and Kaplan-Meier survival analyses. ATOH8-overexpressing and scliencing cell model was generated by Lentivirus system to detect its functional roles in HCC both in vivo and in vitro. iPS technology is used to analyze effects of ATOH8 on CSCs. Result: Downregulation of ATOH8 was detected in over 40% of 242 pairs primary HCC cases, which was significantly associated with disease free survival (P=0.031), high level of AFP (P=0.03) and diferentiation (P=0.01). Functional studies demonstrate the tumor suppressive role of ATOH8 in HCC, including the inhibition of cell growth, cell proliferation, tumor formation in SCID mice and cell motility when ATOH8 was introduced into HCC cells. Further study finds that ATOH8 depletion can enhance the stemness of HCC including the tumorigenicity and abilities for self-renewal, differentiation and chemo-resistance by repressing the transcription of stemness-related genes such as OCT4, NANOG, SOX2, AFP, and HCC cancer stem cell (CSC) surface markers such as CD24 and CD133. One interesting finding in this study is that knockdown of ATOH8 could increase CD133+ cell population in QSG7701 and BEL7402 cells. CD133+ cells induced by ATOH8 depletion were flow-sorted and their CSC property was characterized. The results found that flow-sorted CD133+ cells induced by ATOH8 depletion possessed most characteristics of CSC including the capacity to self-renew, differentiation, sustained proliferation and chemoresistance. In addition, ATOH8 depletion could enhance the frequency of pluripotent stem cells (iPSC) generation induced by 4 factors (OCT4, Sox2, Klf4 and cMyc). All these data strongly suggest that a non-CSC could be reprogrammed into a CSC under some circumstance such as downregulation of ATOH8. Conclusion: This study demonstrates that ATOH8 plays an important role in HCC development, and provides a potential new HCC therapeutic approach that ATOH8 could increase the chemosensitivity of HCC cells to chemotherapeutics as demonstrated in this study. Citation Format: Yangyang Song, Xin-Yuan Guan. ATOH8 depletion can reprogram noncancer stem cells into cancer stem cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3865. doi:10.1158/1538-7445.AM2014-3865