Local injection of lentivirus-delivered livinshRNA suppresses lung adenocarcinoma growth by inducing a G0/G1 phase cell cycle arrest.

The inhibitor of apoptosis protein (IAP) plays an important role in tumorigenesis and may be a potential target for cancer therapy. Livin, which belongs to this family, is highly expressed in various tumors. The previous study demonstrated that silencing Livin gene promoted lung cancer cell apoptosis; however, the effects on tumor growth suppression by targeting this gene in vivo, to thereby determine the efficacy of targeting Livin for patient therapy, have not been determined. This study injected lentivirus-delivered livinshRNA into established xenograft tumors derived from the lung adenocarcinoma cell line SPC-A-1 in BALB/C nude mice, the result showed that LivinshRNA down-regulated Livin expression effectively, induced tumor cell apoptosis, reduced tumor cell proliferation, and suppressed tumor growth dramatically, with a tumor volume inhibitory rate of (58.65±4.82)% and a tumor weight inhibitory rate of (47.44±1.64)%, but with less severe adverse reaction to the mouse. This study further demonstrated that Livin gene silencing induced a G0/G1-phase cell cycle arrest and cyclin D1 downregulation, which is a key regulator of the G0/G1- to S-phase transition. These findings suggest that LivinshRNA local injection may serve as a therapeutic method for patient treatment, and that LivinshRNA may suppress tumor growth by arresting the cell cycle in the G0/G1-phase.

[Effects of human Livin gene down-regulation by RNA interference on xenograft of transplantation tumor induced by SPC-A1 in nude mice].

OBJECTIVE: To explore the in vivo inhibitory effect of Livin gene silencing by RNA interference on xenograft of lung adenocarcinoma SPC-A-1 cells in BALB/C nude mice. METHODS: Three different BALB/C nude mice models were established by subcutaneously inoculating differently treated SPC-A-1 cells into 3 nude mice groups: the blank control group was inoculated with blank SPC-A-1 cells, while the negative group was inoculated with cells transfected with lentivirus-delivered negative shRNA, the experimental group was inoculated with cells with lentivirus-delivered Livin shRNA. Then the growth of tumors was observed, and the volume and weight of the tumors were measured at different time points. The curve of tumor growth was then described, and the inhibition rate was calculated. Livin gene expression in the tumor tissues was determined by RT-PCR and Immunohistochemistry. Cell apoptosis of tumor tissues was detected by TUNEL. RESULTS: Slower tumor growth, smaller tumor volume and lighter tumor weight were observed in the experimental group as compared to the blank and negative groups (F = 70.509, P < 0.01; F = 12.821, P < 0.01). The inhibition rate of tumor volume was (59.5 ± 3.4)%, and the inhibition rate of tumor weight was (71.1 ± 5.6)%. Livinα mRNA and Livinß mRNA expressions in the experimental group were significantly lower than the 2 control groups [(37.2 ± 1.6)% versus (63.3 ± 3.8)%, (66.1 ± 2.6)%; (29.4 ± 1.1)% versus (53.2 ± 3.4)%, (52.3 ± 3.1)% (F(α) = 45.309, P < 0.01; F(ß) = 30.076, P < 0.01)]. Livin protein expression level was also significantly lower than the blank and the negative groups [(15.3 ± 2.8)% versus (51.3 ± 2.1)%, (52.5 ± 2.5)%, F = 78.92, P < 0.01]. The apoptosis rate in the experimental group was significantly higher than that in the 2 control groups [(35.4 ± 3.2)% versus (5.4 ± 1.3)%, (8.6 ± 1.5)%, F = 14.509, P < 0.01]. CONCLUSION: The lentivirus-delivered Livin shRNA was shown to inhibit the proliferation of transplantation tumor of lung carcinoma effectively, and Livin may be a target for gene therapy in lung cancer.