Abstract:

Objective  To investigate the effects and mechanisms of radiosensitising enhancement of Rb94 gene in nude mice xenograft model. Methods  5×106 cells suspension was subcutaneously injected into flanks of 40 nude mice. Then the inoculated mice were devided into 8 groups after tumors reached 180mm3: no treatment group and XRT alone goup treated with PBS, lipofectamine treatment group and lipofectamine with XRT group treated with lipofectamine, pIRES treatment group and pIRES with XRT group treated with pIRES empty vector, pIRESRb94 treatment group and pIRESRb94 with XRT group treated with pIRES-Rb94.  X-ray was given to XRT alone group, lipofectamine with XRT group, pIRES with XRT group and pIRES-Rb94 with XRT group. The tumor inhibiting rate was observed and the expression of Rb94 gene was detected by Real time RT-PCR and Western blot. The number of apoptosis cells was measured by Hoechst staining. Expressions of hTERT and Bcl-2mRNA were detected by Real time RT-PCR. Cell cycle blockage was measured by Immunohistology(IF). Results  The inhibited ratio of pIRES-Rb94 with XRT group tumor was 95.84%, and statistically significant differences in the inhibition ratios were found between the pIRESRb94 with XRT group and the other groups (pIRES-Rb94 treatment group and XRT alone group). Conclusion  It is suggested that Rb94 has inhibitory effects for inoculated tumor in nude mice. The tumor inhibition rate of pIRESRb94 with XRT group seems to be higher than those in other groups. The mechanisms of  radiosensitising enhancement of Rb94 gene may include cell apoptosis, G2/M phase blocking and down-regulation of hTERT and Bcl-2 mRNA expressions.

Key words: Genes, retinoblastoma; A549 cells; Radiosensitivity; Mouse, nude