Objective To investigate the function and mechanism of embryonic stem cells against Lewis non-small cell lung cancer in vivo. Methods Based on the mouse Lewis non-small cell lung cancer model, we have tested some tumor growth indexes and investigated the immune response of embryonic stem cells against cancer cells. Results Compared with the mice in control group, mice in experimental group received obvious antitumor immunity, which means more activated lymphocytes and antitumor cytokines, resulted in the effective control and inhibition of tumor development. Conclusion Besides the antitumor effect in vitro, embryonic stem cells can also generates immune response in vivo, which could effectively inhibit and/or delay the development of cancer.

Objective To clone cathepsin L (CTSL) gene and construct the eukaryotic expression plasmid pcDNA3. 1-CTSL and study the relationship between CTSL and invasion and metastasis in ovarian cancer cells in vitro. Methods The total RNA was extracted from the ovarian cancer tissue and the intact cDNA of CTSL was applied by reverse transcription (RT)-PCR. The product of RT-PCR was cloned to pMD18-T vector, and subcloned to pcDNA3. 1 vector. It was tested by the enzymation and DNA sequencing.The eukaryotic expression plasmid of CTSL was introduced into HO8910 cells by liposome transfection reagent. RT-PCR was used to confirm the recombinant plasmid DNA integrated with the genomic DNA of HO8910 cells. Western blot was used to confirm the CTSL protein expression in positive clones cells. The cell growth curves, clonogenicity efficiency were observed. The cell cycles were measured by flow cytometer.The ability of invasion, metastasis and adhesion of ovarian cancer cells were detected by the matrigel invasion assay, transwell migration assay and adhesion assay, respectively. Results The results from restrictive enzyme analysis and sequencing showed that the CTSL gene was successfully inserted into pcDNA3. 1.Result from RT-PCR and western blot showed that the ovarian cancer cells which transfected by recombinant plasmid could express CTSL gene and protein. There was no difference between HO8910-CTSL and HO8910-pcDNA3. 1 cells in proliferation and adhesion ability (0.16±0.04 versus 0. 19±0. 04) of the cells (P>0.05). There was difference between HO8910-CTSL and HO8910-peDNA3.1 cells in matrigel invasion ability (0.34±0.18 versus 0.17±0.04) and metastasis ability (1.252±0.114 versus 0.486±0.027) of cancer(all P<0.05). Conclusion CTSL maybe increase the ability of invasion and metastasis of ovarian cancer cells in vitro, which may be a molecular target of blocking invasion and metastasis of ovarian cancer.

Objective To explore whether or not multi-drug resistance could be reversed by RNA interference the expression of Topo Ⅱα gene in epithelial ovarian cancer cell lines in vitro. Methods (1) The best silent small interference RNA (siRNA) of Topo Ⅱα gene was designed and chose and cloned into psilencer4, 1-CMV-neo vector. The psilencer4. 1-CMV-neo-Topo Ⅱα was transfected into SKOV3/DDP cell, then Topo Ⅱα siRNA (+) SKOV3/DDP cells was incubated. (2) The Tope Ⅱα mRNA and protein expression of the stability-transfecting cell lines were detected by RT-PCR and western blot method, respectively. The resistance index, the cell cycle and the cellular content of cisplatin were detected by methyl thiazolyl tetrazolium assay, the flow cytometry and high performance liquid chromatography method before and after Topo Ⅱα RNA interference in cells. Results (1) The Topo Ⅱα gene expression level in SKOV3/DDP cells could be inhibited after the plasmid DNA psilencer4, 1-CMV-neo-Topo Ⅱα transfeced. The expression level of Tope Ⅱα mRNA in Topo Ⅱα siRNA(+)SKOV3/DDP and SKOV3/DDP cells were 0 and 0.92±0.08; the expression level of Topo Ⅱα protein in Topo Ⅱα siRNA (+) SKOV3/DDP and SKOV3/DDP cells were 0.51±0. 04 and 1.95±0.09 (P<0.01). (2) The multi-drug resistance index of Topo Ⅱα siRNA (+) SKOV3/DDP cell was significantly lower compared with that in SKOV3/DDP cell (3.46 vs 5.05, P<0.05). (3) The percentage of G_0/G_1 and G_2/M phase cell in Topo Ⅱα siRNA(+) SKOV3/DDP cells were higher than that in SKOV3/DDP cells (P<0.05). (4) The content of cisplatin in Topo Ⅱα siRNA(+)SKOV3/DDP cells treated with cisplatin for 24 hours was significantly higher than that in SKOV3/DDP cell (157.20 vs 63.99 ng, P<0.05). Conclusion The results showed that the tolerance of cisplatin would be reversed by blocking the Topo Ⅱα gene expression in cisplatin-resistant epithelial ovarian cancer cells.

BACKGROUNDKu70, Ku80 and DNA-PKcs proteins take part in the repairment of DNA double-strand breaks as regulatory subunits of DNA-dependent protein kinase. The aim of this study is to investigate the expression and clinical significance of Ku70, Ku80 and DNA-PKcs proteins in patients with stage I-II non-small cell lung cancer (NSCLC).

METHODSA total of 86 patients with stage I-II NSCLC who received adjuvant chemotherapy after radical surgery were retrospectively analyzed. The expression of Ku70, Ku80 and DNA-PKcs proteins was detected by tissue microarray technique and immunohistochemical two-step method.

RESULTSThe positive rate of Ku70, Ku80 and DNA-PKcs in lung cancer tissues was 68.6%, 72.1% and 87.2%, respectively. Their expression was not related to histological classification (P > 0.05). The patients with worse prognosis seemed to have higher expression of Ku70, Ku80 and DNA-PKcs proteins, however there was no statistical significance (P > 0.05).

CONCLUSIONSKu70, Ku80 and DNA-PKcs are overexpressed in stage I-II lung cancer without prior chemotherapy. They may be not good for guidance of postoperative chemotherapy in completely resected stageI-II NSCLC.