Maxizyme-mediated specific inhibition on mutant-type p53 in vitro

Functional repair of p53 mutation in colorectal cancer cells using trans-splicing

Mutation in the p53 gene is arguably the most frequent type of gene-specific alterations in human cancers. Current p53-based gene therapy contains the administration of wt-p53 or the suppression of mutant p53 expression in p53-defective cancer cells. We hypothesized that trans-splicing could be exploited as a tool for the correction of mutant p53 transcripts in p53-mutated human colorectal cancer (CRC) cells. In this study, the plasmids encoding p53 pre-trans-splicing molecules (PTM) were transfected into human CRC cells carrying p53 mutation. The plasmids carrying p53-PTM repaired mutant p53 transcripts in p53-mutated CRC cells, which resulted in a reduction in mutant p53 transcripts and an induction of wt-p53 simultaneously. Intratumoral administration of adenovirus vectors carrying p53 trans-splicing cassettes suppressed the growth of tumor xenografts. Repair of mutant p53 transcripts by trans-splicing induced cell-cycle arrest and apoptosis in p53-defective colorectal cancer cells in vitro and in vivo. In conclusion, the present study demonstrated for the first time that trans-splicing was exploited as a strategy for the repair of mutant p53 transcripts, which revealed that trans-splicing would be developed as a new therapeutic approach for human colorectal cancers carrying p53 mutation.

Maxizyme against mtp53 transfected by adenovirus enhanced transferrin receptor-mediated gene delivery systeminduced apoptosis of hepatoma cells

AIM: To evaluate the influence of introduction of maxizyme against mtp53 by adenovirus enhanced transferrin receptor-mediated gene delivery system on MHCC97 cells.

METHODS: Hepatoma cell line MHCC97 containing mutated p53 gene was served as a model. The maxizyme against mtp53 was transfected to the cells by adenovirus enhanced transferrin receptor-mediated gene delivery system. The level of mtp53-mRNA was detected by means of semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). The apoptosis of the hepatoma cells was measured by DNA ladder assay and FCM.

RESULTS: After 48 hours of transfection by AVET system, RT-PCR results indicated the expression of mtp53 mRNA in pEGFP-Maxizyme group was significantly lower than that in control group. And DNA "ladder" with agarose gel electrophoresis was observed in pEGFP-maxizyme group. The result of flow cytometry exhibited apoptotic index in pEGFP-maxizyme group was 22.95%, which was higher than those in blank control group and pEGFP group.

CONCLUSION: The recombinant ribozyme cDNA eukaryotic expression vector pEGFP-maxizyme can be efficiently transfected into MHCC97 cell by adenovirus enhanced transferrin receptor-mediated gene delivery system and the expression of maxizyme may inhibit the mtp53 gene expression and promote apoptosis of MHCC97 cells. The AVET system may be a useful tool in gene delivery for gene therapy of human HCC.