Complex formation between mutant p53 and protein p63 in human tumor cell lines

Abstract

Tumor supresorski gen TP53 mutiran je u preko 50% tumora čovjeka. Nakon mutacije može doći do gubitka funkcije p53 u stanici, ali i do promjene funkcije p53, koji može pokazivati onkogena svojstva. Neka onkogena svojstva mutiranih p53 mogu se objasniti interakcijom s drugim članovima obitelji p53, posebice s tumor supresorskim izoformama, TAp63 i TAp73. Na jačinu tih interakcija utječe polimorfizam na kodonu 72 gena TP53. Plazmidni vektori s ugrađenim genom za TAp63α, odnosno s genom za mutirani p53 koji imaju različit polimorfizam na kodonu 72 kotransfecirani su u stanice metastaza karcinoma pluća čovjeka (H1299) koje imaju djelomičnu deleciju gena TP53. Proteinski kompleksi su izolirani iz staničnih lizata metodom ko-imunoprecipitacije i analizirani metodom western blotting. Kompleksi su utvrđeni za mutirane oblike p53 L194F i R282W, te nisu utvrđeni za R175H, R280K i I332A. Ustanovljeno je da se mut p53 72R jače veže za TAp63α nego mut p53 72P.The tumor suppressor gene TP53 is mutated in over 50% of reported human tumor cases. The outcomes of the mutation are either loss of p53 function or gain of function resulting in oncogenic phenotype. Some of the mutant p53 oncogenic features are explained through interactions with other p53 family members, specifically tumor suppressor isoforms TAp63 and TAp73. A common polymorphism on codon 72 affects the strength of these interactions. Expression vectors coding for TAp63α or mutant p53 with different codon 72 polymorphism were cotransfected into H1299 cells, derived from human lung carcinoma metastasis, which have a partial deletion of the TP53 gene. Protein complexes were isolated from cell lysates using the co-immunoprecipitation method, and analysed by western blotting. Complexes have been found between TAp63α and p53 mutants L194F and R282W, but not between TAp63α and R175H, R280K and I332A. It was established that mut p53 72R binds more efficiently to TAp63α