Journal Article

PBK/TOPK interacts with the DBD domain of tumor suppressor p53 and modulates expression of transcriptional targets including p21

Fang, H-B, Hu, F, Eichberg, D, Gartenhaus, R B, Liu, Z, Rapoport, A P

2010

Overview

PBK/TOPK (PDZ-binding kinase, T-LAK-cell-originated protein kinase) is a serine-threonine kinase that is overexpressed in a variety of tumor cells but its role in oncogenesis remains unclear. Here we show, by co-immunoprecipitation experiments and yeast two-hybrid analysis, that PBK/TOPK physically interacts with the tumor suppressor p53 through its DNA-binding (DBD) domain in HCT116 colorectal carcinoma cells that express wild-type p53. PBK also binds to p53 mutants carrying five common point mutations in the DBD domain. The PBK–p53 interaction appears to downmodulate p53 transactivation function as indicated by PBK/TOPK knockdown experiments, which show upregulated expression of the key p53 target gene and cyclin-dependent kinase inhibitor p21 in HCT116 cells, particularly after genotoxic damage from doxorubicin. Furthermore, stable PBK/TOPK knockdown cell lines (derived from HCT116 and MCF-7 cells) showed increased apoptosis, G 2 /M arrest and slower growth as compared to stable empty vector-transfected control cell lines. Gene microarray studies identified additional p53 target genes involved in apoptosis or cell cycling, which were differentially regulated by PBK knockdown. Together, these data suggest that increased levels of PBK/TOPK may contribute to tumor cell development and progression through suppression of p53 function and consequent reductions in the cell-cycle regulatory proteins such as p21. PBK/TOPK may therefore be a valid target for antineoplastic kinase inhibitors to sensitize tumor cells to chemotherapy-induced apoptosis and growth suppression.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 631/67/581 / 631/92/612/1223 / 692/699/67/1504/1885 / Apoptosis / Apoptosis - genetics / Binding proteins / Biochemistry / Biological and medical sciences / Blotting, Western / Cell Biology / Cell Cycle - genetics / Cell physiology / Cell Separation / Cell transformation and carcinogenesis. Action of oncogenes and antioncogenes / Chemotherapy / Chromatin Immunoprecipitation / Colorectal cancer / Colorectal carcinoma / Cyclin-dependent kinase / Cyclin-dependent kinase inhibitor p21 / Cyclin-Dependent Kinase Inhibitor p21 - biosynthesis / Cyclin-Dependent Kinase Inhibitor p21 - genetics / Cyclin-dependent kinases / DNA microarrays / Dosage and administration / Doxorubicin / Enzyme inhibitors / Flow Cytometry / Fundamental and applied biological sciences. Psychology / Gene Expression / Gene Expression Regulation, Neoplastic / Gene Knockdown Techniques / Genetic transcription / Genetics / Genotoxicity / GTP-binding protein / HCT116 Cells / Human Genetics / Humans / Immunoprecipitation / Internal Medicine / Kinases / Medicine / Medicine & Public Health / Mitogen-Activated Protein Kinase Kinases / Molecular and cellular biology / Molecular genetics / Mutation / Oligonucleotide Array Sequence Analysis / Oncology / original-article / p53 Protein / Physiological aspects / Properties / Protein Interaction Domains and Motifs / Protein kinase / Protein-Serine-Threonine Kinases - genetics / Protein-Serine-Threonine Kinases - metabolism / Protein-serine/threonine kinase / Regulatory proteins / Reverse Transcriptase Polymerase Chain Reaction / Signal Transduction / Transcription / Transcription, Genetic / Transcription. Transcription factor. Splicing. Rna processing / Tumor cells / Tumor suppressor genes / Tumor Suppressor Protein p53 - genetics / Tumor Suppressor Protein p53 - metabolism / Tumorigenesis / Two-Hybrid System Techniques