OBJECTIVETo study the effect of targeted Sox4 gene-knock-down on the growth of xenografts of Xuanwei female lung cancer cell line XWLC-05 cells in nude mice.

METHODSRecombinant plasmid pGFP-V-RS-Sox4 shRNA was constructed and transfected into XWLC-05 cells. Real-time quantitative PCR and Western blot were applied to confirm the effect of Sox4 gene-knock-down. XWLC-05 cells stably transfected with the plasmids were inoculated into nude mice to establish the xenograft model. The nude mouse status, tumor formation and tumor growth were observed, and the tumor inhibition rate was calculated. CT scan was performed to assess the metastasis of xenografts. Immunohistochemical staining was applied to detect Sox4 and ki-67 protein expression.

RESULTSRecombinant plasmid pGFP-V-RS-A-Sox4 shRNA which can effectively knocking-down Sox4 gene was successfully constructed and the stable transfected cells were selected by puromycin-screening. The success rate of tumor cell inoculation was 100% in the mice of all groups except those inoculated with saline. The body weight of all mice inoculated with parental XWLC-05 cells (blank control), pGFP-V-RS-scram shRNA trsfected XWLC-05 cells (negative control), and pGFP-V-RS-Sox4 shRNA transfected XWLC-05 cells was increased to a varying degree, but there was no significant difference among the groups (P > 0.05 ). The growth of xenografts was significantly inhibited after silencing the Sox4 gene expression when compared with that of the blank and negative controls (P < 0.05) . The volume of removed tumors of the Sox4 gene-inhibited mice was (2.30 ± 0.34) cm(3) , significantly smaller than that of the negative control (3.99 ± 0.45) cm(3) and the blank control (4.03 ± 0.42) cm(3) (P < 0.05) . The weight of removed tumors of Sox4 gene-inhibited mice was (0.86 ± 0.14) g, significantly lower than that of the negative control (1.84 ± 0.27) g and blank control (1.86 ± 0.22) g, (P < 0.05). Immunohistochemical staining showed that Sox4 and ki-67 proteins mainly expressed in cell nuclei. The staining was significantly decreased in xenografts of Sox4-inhibited mice when compared with the negative and blank controls (P < 0.05). No distant metastasis was found in any mouse by CT imaging and pathological examination during the observation period.

CONCLUSIONSThe xenograft model of Xuanwei female lung cancer cell line XWLC-05 cells in nude mice is successfully established. Knocking-down of Sox4 gene can suppress the xenograft tumor growth.