Posttranscriptional induction of p21Waf1 mediated by ectopic p16INK4 in human diploid fibroblast

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Abstract

Background

Both p16INK4 and p21Waf1 are tumor suppressors with similar biological functions in the regulation of cellular senescence. Previous reports showed that p16INK4 could be activated by p21Waf1 through transcriptional factor Sp1 in HeLa cells. This study was undertaken to determine the effects of p16INK4 on the expression and functions of p21Waf1.

Methods

Human diploid fibroblast 2BS cells were stably transfected with sense (2BS/p16INK4), antisense p16INK4 (2BS/asp16INK4) or empty vector (2BS/neo) Then they were assayed by reverse-transcription polymerase chain reaction (RT-PCR), fluorescence activated cell sorting (FACS) and Western blot.

Results

2BS/p16INK4 cells exhibited cell cycle arrest in both G1 and G2/M phases. Endogenous p21Waf1 protein levels increased twofold in the 2BS/p16INK4 cells, but not decreased in the 2BS/asp16INK4 cells. p21Waf1 mRNA levels were not affected in neither 2BS/p16INK4 nor 2BS/asp16INK4 cells.

Conclusion

p16INK4 may play an important role in the regulation of cellular senescence by modulating the p21Waf1 protein level via the posttranscriptional mechanism.

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