8-60hIPP5^m-Induced G2/M Cell Cycle Arrest Involves Activation of ATM/p53/p21^cip1/waf1Pathways and Delayed Cyclin B1 Nuclear Translocation

Abstract

Protein phosphatase 1 (PP1) is a major serine/threonine phosphatase that controls gene expression and cell cycle progression. The active mutant IPP5 (8-60hIPP5 m ), the latest member of the inhibitory molecules for PP1, has been shown to inhibit the growth of human cervix carcinoma cells (HeLa). In order to elucidate the underlying mechanisms, the present study assessed overexpression of 8-60hIPP5 m in HeLa cells. Flow cytometric and biochemical analyses showed that overexpression of 8-60hIPP5 m induced G2/M-phase arrest, which was accompanied by the upregulation of cyclin B1 and phosphorylation of G2/M-phase proteins ATM, p53, p21 cip1/waf1 and Cdc2, suggesting that 8-60hIPP5 m induces G2/M arrest through activation of the ATM/p53/p21 cip1/waf1 /Cdc2/ cyclin B1 pathways. We further showed that overexpression of 8-60hIPP5m led to delayed nuclear translocation of cyclin B1. 8-60hIPP5 m also could translocate to the nucleus in G2/M phase and interact with pp1α and Cdc2 as demonstrated by co-precipitation assay. Taken together, our data demonstrate a novel role for 8-60hIPP5m in regulation of cell cycle in HeLa cells, possibly contributing to the development of new therapeutic strategies for cervix carcinoma.

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Ionizing radiation triggers mitophagy to enhance DNA damage in cancer cells

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Astragalus Polysaccharide RAP Selectively Attenuates Paclitaxel-Induced Cytotoxicity Toward RAW 264.7 Cells by Reversing Cell Cycle Arrest and Apoptosis

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