[Silencing of signal transducer and activator of transcription 3 gene expression using RNAi enhances the efficacy of radiotherapy for laryngeal carcinoma in vivo].
OBJECTIVE
To study the inhibitory effect of signal transducer and activator of transcription 3 (STAT3) shRNA generated by vector pSilence in conjunction with radiotherapy on laryngeal squamous cell carcinoma of nude mice xenograft tumor.


METHODS
The animal models of xenotransplanted human laryngeal carcinoma cell line Hep-2 were set up in 28 nude mice which were divided into 4 groups at random: the negative plasmid control group, the group that received pshSTAT3 (pGPU6/GFP/NeoshSTAT3) transfection, the radiation group, and the group of pshSTAT3 transfection combined with irradiation. Tumor volume was determined regularly. On the fifteenth day after termination of radiation treatment, the mice were sacrificed, the tumor weight was measured in all the groups, the inhibition rate for tumor growth was calculated and tumor growth curve was plotted. Meanwhile, the expressions of p-STAT3, B cell lymphoma 2 (bcl-2), p53, vascular endothelial growth factor (VEGF) protein and intratumor microvessel density (MVD) were observed by immunohistochemistry. Computer-assisted image analysis was used to obtain the results. Flow cytometry was used to detect the cell apoptosis rate.


RESULTS
There was a significant difference in tumor volume among the groups (P<0.01). The rate of tumor inhibition in the pshSTAT3 group, radiation group and pshSTAT3 plus radiation group was 19.68%, 34.76% and 67.70%, respectively. The p-STAT3 protein expression decreased significantly in the group of pshSTAT3 plus simple radiotherapy (P<0.01). The intratumoral MVD in the group of pshSTAT3 plus simple radiotherapy was significantly lower compared to the negative plasmid control group and the radiotherapy group (P<0.01), while the apoptosis rate was much higher (P<0.01). There was a positive correlation between the expressing of p-STAT3 and bcl-2, p53, VEGF and MVD (r value was 0.738, 0.727, 0.735, 0.691, all P<0.01), and there was a negative correlation concerning cell apoptosis rate. Moreover, a statistically positive association was present between MVD and p53, VEGF protein expression, respectively (r value was 0.784, 0.641, all P<0.01); and the correlation was negative between expression of bcl-2 and apoptosis rate (r=-0.883, P<0.01).


CONCLUSIONS
Using pshSTAT3 in conjunction with radiotherapy can significantly inhibit the growth of laryngeal carcinoma.
Wang
Hai-Ru
HR
Department of Otorhinolaryngology Head and Neck Surgery, Bethune International Peace Hospital of People's Liberation Army, Shijiazhuang 050082, China.
Li
Xiao-Ming
XM
Lu
Xiu-Ying
XY
D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000235:genetics / Q000378:metabolism / Q000532:radiotherapy*; D045744:Cell Line, Tumor; D006801:Humans; D007822:Laryngeal Neoplasms / Q000235:genetics / Q000378:metabolism / Q000532:radiotherapy*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D034622:RNA Interference; D050796:STAT3 Transcription Factor / Q000235:genetics*; D015398:Signal Transduction; D014162:Transfection; D023041:Xenograft Model Antitumor Assays
D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human