Oncogenic potential of histone-variant H2AZ1 and its regulatory role in cell cycle and epithelial-mesenchymal transition in liver cancer
ONCOTARGET
Authors: Yang, Hee Doo; Kim, Pum-Joon; Eun, Jung Woo; Shen, Qingyu; Kim, Hyung Seok; Shin, Woo Chan; Ahn, Young Min; Park, Won Sang; Lee, Jung Young; Nam, Suk Woo
Abstract
H2A.Z is a highly conserved H2A variant, and two distinct H2A.Z isoforms, H2A.Z.1 and H2A.Z.2, have been identified as products of two non-allelic genes, H2AFZ and H2AFV.H2A.Z has been reported to be overexpressed in breast, prostate and bladder cancers, but most studies did not clearly distinguish between isoforms. One recent study reported a unique role for the H2A.Z isoform H2A.Z.2 as a driver of malignant melanoma. Here we first report that H2A.Z. 1 plays a pivotal role in the liver tumorigenesis by selectively regulating key molecules in cell cycle and epithelial-mesenchymal transition (EMT). H2AFZ expression was significantly overexpressed in a large cohort of hepatocellular carcinoma (HCC) patients, and high expression of H2AFZ was significantly associated with their poor prognosis. H2A.Z.1 overexpression was demonstrated in a subset of human HCC and cell lines. H2A.Z.1 knockdown suppressed HCC cell growth by transcriptional deregulation of cell cycle proteins and caused apoptotic cell death of HCC cells. We also observed that H2A.Z.1 knockdown reduced the metastatic potential of HCC cells by selectively modulating epithelial-mesenchymal transition regulatory proteins such as E-cadherin and fibronectin. In addition, H2A.Z.1 knockdown reduced the in vivo tumor growth rate in a mouse xenograft model. In conclusion, our findings suggest the oncogenic potential of H2A.Z.1 in liver tumorigenesis and that it plays established role in accelerating cell cycle transition and EMT during hepatocarcinogenesis. This makes H2A.Z.1 a promising target in liver cancer therapy.
Identification of differentially expressed genes in mouse embryonic stem cell under hypoxia
GENES & GENOMICS
Authors: Hwang, Su Jung; Lee, Hyo-Jong
Abstract
Background Under hypoxia, mouse embryonic stem cells (mESCs) lose the ability to self-renew and begin to differentiate through down-regulation of LIFR-STAT3 pathway via hypoxia-inducible factor-1 alpha (HIF-1 alpha). However, it remains largely unknown what kinds of factors are involved in hypoxia-induced differentiation of mESCs. Purpose This study aims to identify the differentially expressed genes (DEGs) in early differentiation of mESCs under hypoxia. Methods Here we utilized a Genefishing technique (TM) to discover the new DEGs during hypoxia-induced early differentiation in CCE mESCs. Next, we investigated the role of DEGs using morphological observation, alkaline phosphatase (ALP) assay, STAT3 activation analysis, and biomarkers analysis for stemness. Results We detected 19 DEGs under hypoxia and performed cloning with sequencing in six genes. We confirmed the expression patterns of five DEGs including H2afz and GOT1 by realtime PCR assay. Among them, H2afz was significantly decreased under hypoxia, depending on HIF-1 alpha. H2afz-overexpressing CCE mESCs maintained their ALP activity and stem cell markers (Nanog and Rex1), even in hypoxic condition. On the other hand, the early differentiation markers such as FGF5 and STAT5a, which had been increased in hypoxic conditions, were reduced by H2afz overexpression. Conclusion We discovered that H2afz could be a new target gene that functions in hypoxia-induced differentiation in mESCs and have revealed that it is involved in maintaining the pluripotency of mESCs in the early stages of differentiation. These findings will provide insights into mechanisms of hypoxia-mediated differentiation of mESCs during early development.