Effect of Livin RNA interference on radiosensitivity of colorectal cancer HT-29 cell xenograft in nude mice / 中华放射医学与防护杂志

ABSTRACT

Objective To explore the effects of silencing Livin gene by RNA interference mediated by lentiviral vector on colorectal cancer HT-29 cell xenograft growth and sensitivity to radiotherapy in nude mice.Methods BALB/c nude mice models were established by subcutaneously inoculating differently treated HT-29 cells into nude mice and the tumor growth situation of tumors was observed by measuring the volume of tumors and the weight of the nude mice at different time points after cell seeding.Livin expression was detected by RT-PCR and immunohistochemistry,respetively.Apoptosis rate was detected by TUNEL.Normal saline,lentivirus carring unrelated sequences,lentivirus caning Livin shRNA were injected intratumorally.All the nude mice were given 10 Gy of 6 MV X-ray irradiation.The changes of mice weight and the tumor volume were measured at different time points and the weight and tumor growth curves were drawn.Results The inhibition rate of tumor volume was(50.04 ± 0.07)％ and the tumor weight of the RNA interfering group was significantly less than that in experimental group compared to the blank and negative groups(F=4.85,P＜0.05),and the inhibition rate of tumor weight was(50.27 ±0.17)％.Relative Livin mRNA expression level in the RNA interfering experimental group was(17.75 ±0.08)％,and was significantly lower than that of the blank group(67.60 ± 0.05)％ and the negative group(68.54 ± 0.03)％(F=89.97,P＜0.01).Livin protein expression level in the RNA inferring group was also significantly lower[(36.00 ± 3.40)％ versus(85.00 ± 3.15)％,(80.33 ± 3.08)％,F=107.32,P＜0.01].The apoptosis rate in the RNA interfering experimental group was significantly higher than that in the blank and the negative groups[(23.67 ± 2.25)％ versus(5.00 ± 1.50)％,(8.33 ± 1.82)％,F=56.94,P＜0.01].Combined with radiotherapy,the tumor volume at different groups had significant difference(F=10.70,P＜0.01),and RNA interfering group was significantly less than negative group and blank group(F=7.01-9.32,P＜0.01).Conclusions Silencing of Livin gene expression by lentiviral vector-mediated RNA interference could inhibit the growth of colorectal HT-29 cell xenograft and increase the sensitivity of the transplanted tumors to radiotherapy.