DNA topoisomerase III alpha regulates P53-mediated tumor suppression
Journal
Clinical Cancer Research
Journal Volume
20
Journal Issue
6
Pages
1489-1501
Date Issued
2014
Author(s)
Hsieh, Mei-Yi
Fan, Jia-Rong
Chang, Han-Wen
Chen, Hsiang-Chin
Yeh, Yen-Hsiu
Abstract
Purpose: Human DNA topoisomerase III alpha (hTOP3a) is involved in DNA repair surveillance and cell-cycle checkpoints possibly through formatting complex with tumor suppressors. However, its role in cancer development remained unsolved. Experimental Design: Coimmunoprecipitation, sucrose gradient, chromatin immunoprecipitation (ChIP), real time PCR, and immunoblotting analyses were performed to determine interactions of hTOP3a with p53. Paired cell lines with different hTOP3a levels were generated via ectopic expression and short hairpin RNA (shRNA)-mediated knockdown approaches. Cellular tumorigenic properties were analyzed using cell counting, colony formation, senescence, soft agar assays, and mouse xenograft models. Results: The hTOP3a isozyme binds to p53 and cofractionizes with p53 in gradients differing from fractions containing hTOP3a and BLM. Knockdown of hTOP3a expression (sh-hTOP3a) caused a higher anchorage-independent growth of nontumorigenic RHEK-1 cells. Similarly, sh-hTOP3a and ectopic expression of hTOP3a in cancer cell lines caused increased and reduced tumorigenic abilities, respectively. Genetic and mutation experiments revealed that functional hTOP3a, p53, and p21 are required for this tumor-suppressive activity. Mechanism-wise, ChIP data revealed that hTOP3a binds to the p53 and p21 promoters and positively regulates their expression. Two proteins affect promoter recruitments of each other and collaborate in p21 expression. Moreover, sh-hTOP3aand sh-p53 inAGS cells caused a similar reduction in senescence and hTOP3a mRNA levels were lower in gastric and renal tumor samples. Conclusion: We concluded that hTOP3a interacts with p53, regulates p53 and p21 expression, and contributes to the p53-mediated tumor suppression. ? 2014 American Association for Cancer Research.
SDGs
Other Subjects
Bloom syndrome helicase; DNA topoisomerase; DNA topoisomerase III alpha; messenger RNA; protein p21; protein p53; unclassified drug; cyclin dependent kinase inhibitor 1A; DNA topoisomerase; DNA topoisomerase III; protein p53; TP53 protein, human; animal experiment; animal model; article; cancer inhibition; carcinogenesis; cell level; controlled study; enzyme activity; enzyme binding; gene interaction; gene silencing; human; human cell; in vitro study; in vivo study; kidney tumor; mouse; nonhuman; priority journal; promoter region; protein expression; protein function; protein protein interaction; stomach tumor; tumor cell; animal; chromatin immunoprecipitation; gene expression regulation; immunoblotting; immunoprecipitation; metabolism; nonobese diabetic mouse; physiology; real time polymerase chain reaction; SCID mouse; tumor cell line; xenograft; Animals; Cell Line, Tumor; Chromatin Immunoprecipitation; Cyclin-Dependent Kinase Inhibitor p21; DNA Topoisomerases, Type I; Gene Expression Regulation, Neoplastic; Heterografts; Humans; Immunoblotting; Immunoprecipitation; Mice; Mice, Inbred NOD; Mice, SCID; Real-Time Polymerase Chain Reaction; Tumor Suppressor Protein p53
Publisher
American Association for Cancer Research Inc.
Type
journal article