Abstract: Objective To observe the effect of P53 shRNA on the proliferation and expression of P21 protein in SMMC-7721 cell line. Methods Design short hairpin RNA(shRNA) sequences targeting human wild type P53 gene and construct recombinant plasmid pGPU6/GFP/Neo-P53 shRNA. SMMC-7721 cells were transfected with the recombinant plasmid and negative control vector respectively. Stably expressing clones were selected using G418. The proliferation was detected with clone form assay. The expression of P53 and P21 mRNA and protein were detected by RT-PCR and Western blot, respectively. SMMC-7721 cells were transplanted by subcutaneous injection to form transplantation tumor in nude mice. Then pGPU6/GFP/Neo-P53 shRNA or negative control shRNA were injected into implanted tumors directly, and tomor volume and weight were detected. Results P53 shRNAs, including P1, P2 and P3, can severely decrease P53 mRNA levels(P<0.05, P<0.05 or P<0.01). The clone form efficiency was increased significantly after interfering P53 function in SMMC-7721 cells(P<0.05), and the expression of P21 mRNA and protein were obviously decreased following the interference of P53 (P<0.05). After P53 was silenced, tomor volume and weight were increased significantly(P<0.05). Conclusion P53 shRNA silencing P53 to lower P21 protein expression may make SMMC-7721 hepatic carcinomas cells malignant proliferation.

Key words: RNA interference, P53, P21, hepatoma