Molecular Mechanism Study on Different Isoforms of ING1 Family Inhibiting HeLa Cells Proliferation / 生物化学与生物物理进展

ABSTRACT

ING1 family is a candidate for tumor suppressor,which has three splicing isoforms named p47ING1a,p33ING1b,and p24ING1c. Study of the effect of different isoforms of ING1 on HeLa cells proliferation and its molecular mechanism would help further identifying the functional relationship of ING1 isoforms,and finding important genes regulated by ING1. Cell growth curve and cell cycle analysis were used to observe the effect of ING1a,ING1b,and ING1c on HeLa cells growth,and the result indicated that they could all inhibit HeLa cells growth by arresting cell cycle at G0/G1 phase. PCR method was used to construct the PHD domain deletions of ING1a and ING1b. ING1a,ING1b,ING1c and the PHD domain deletions 1a?C and 1b?C were then overexpressed in HeLa cells. p16INK4a,PTEN/p27Kip1 and p53/p21Waf1 protein levels were detected by Western blot. The result showed that ING1a,ING1b,ING1c,and 1a?C except for 1b?C induced p16INK4a protein expression,in which ING1c had the most powerful effect. Luciferase assay identified that overexpression of pcDNA3.1(+)-1a?C facilitated p16INK4a transcription through enhancing p16INK4a promoter activity,while pcDNA3.1(+)-1b?C repressed the p16INK4a promoter activity . In a word,it was found for the first time that except for the p53/p21Waf1 pathway,three splicing isoforms of ING1 family could also inhibit HeLa cells proliferation though upregulation of p16INK4a and PTEN,and the PHD domain deletion of ING1a enhanced p16INK4a transcription. These findings provide new clews to further study on the mechanisms of ING1 family suppressing cancer cells growth.