Mining the Prognostic Value of HNRNPAB and Its Function in Breast Carcinoma
INTERNATIONAL JOURNAL OF GENOMICS
Authors: Cao, Yun; Zhang, Wei; Jin, Yi-Ting; Zou, Qiang
Abstract
Heterogeneous nuclear ribonucleoproteins (HNRNPs) are crucial members in the pathogenesis and progression of numerous cancers. However, the expression pattern and clinical significance of HNRNPs in breast carcinoma (BC) remain to be investigated. In the present study, bioinformatic analysis identified HNRNPAB as the only commonly upregulated HNRNP in BC. Elevated expression of HNRNPAB was positively associated with more aggressive diseases and poorer survival rates in BC. Pathway analysis revealed that HNRNPAB coexpressed genes were enriched in the pathway of G2/M phase transition, and the expression level of HNRNPAB was strongly correlated with those of CCNB1, CDK1, CDC25A, and CDC25C. Experiments in vitro demonstrated that HNRNPAB knockdown suppressed cell proliferation and blocked the G2/M phase transition in BC. Taken together, this study provides the initial evidence that HNRNPAB may be employed as an innovative therapeutic target as well as a prognostic biomarker in BC patients.
HBXIP, a binding protein of HBx, regulates maintenance of the G2/M phase checkpoint induced by DNA damage and enhances sensitivity to doxorubicin-induced cytotoxicity
CELL CYCLE
Authors: Fei, Hongrong; Zhou, Yunsheng; Li, Ruotong; Yang, Mingfeng; Ma, Jian; Wang, Fengze
Abstract
To maintain the integrity of the genome, cells need to detect and repair DNA damage before they complete cell division. Hepatitis B x-interacting protein (HBXIP), a binding protein of HBx (Hepatitis B virus x protein), is aberrantly overexpressed in human cancer cells and show to promote cell proliferation and inhibit apoptosis. The present study is designed to investigate the role of HBXIP on the DNA damage response. Our results show that HBXIP acts as an important regulator of G2/M checkpoint in response to DNA damage. HBXIP knockdown increases phospho-histone H2AX expression and foci formation after treatment with ionizing radiation (IR). HBXIP regulates the ATM-Chk2 pathway following DNA damage. Depletion of HBXIP abrogates IR-induced G2/M cell cycle checkpoints, accompanying decrease the expression of phospho-Cdc25C, phospho-Cdc2 (Tyr15) and p27. We also show that downregulation of HBXIP expression sensitizes cancer cells to chemotherapy, as evidenced by an increase in apoptosis and cleavage of caspase-3 and caspase-9. Our data suggest that HBXIP can function as a mediator protein for DNA damage response signals to activate the G2/M checkpoint to maintain genome integrity and prevent cell death.