ABSTRACT
@# Objective: The present study was aimed to explore the role and distinctive mechanism of SPIDR, the key regulatory protein of homologous recombination pathway, in progression of small cell lung cancer (SCLC). Methods: 60 SCLC specimens and 44 normal lung tissues were collected from the patients undergoing tumor resection and bronchoscopic puncture in Shanghai Pulmonary Hospital Affiliated to Tongji University from January 2013 to January 2015. The expression of SPIDR in clinical samples and NCIH446 (SCLC cell line) and MRC-5 (normal cell line) were assayed by Real-time PCR. The role of SPIDR in SCLC was investigated in vivo and in vitro by the expression of SPIDR were artificially modified in NCI-H446. Results: Smoking was significantly associated with the occurrence of SCLC (P<0.01). The expression of SPIDR mRNAin SCLC tissues was lower than that of normal lung tissues (P <0.01), and the SPIDR transcriptional and translational levels of NCI-H446 cells were also lower than that of MRC-5.Although there is no significant changes of cell growth rate and susceptibility to cisplatin and etoposide in the NCI-H446 cells overexpressing SPIDR. However, the volume of xenograft tumors of overexpressed SPIDR group decreased by 58.99% (P<0.01) and 61.84% (P<0.01) than that of the original NCI-H446 cells and the NCI-H446 cells transfected with vector (pMSCV) and the average tumor mass decreased by 61.70% (P<0.01) and 70.25% (P<0.01) respectively. When the fetal bovine serum content in the medium was reduced to 3%, the growth rate of NCI-H446 cells overexpressing SPIDR was 22.33% (P<0.01) and 20.24% (P<0.05) lower than that of the original NCIH446 cells and control group, the similar results were obtained from the 1% serum concentration experiment as well. Conclusion: The expression of SPIDR, the key regulatory protein in the DNAdouble strand break homologous recombination repair pathway, was significantly suppressed in SCLC tissues, which markedly accelerated the growth of NCI-H446 cells in vivo and reduced the reliance of NCIH446 cells to the serum. The detailed mechanism is worthy of further investigation.
ABSTRACT
Objective To establish a radiation-resistant cell subline from a human small cell lung cancer ( SCLC) cell line NCI-H446, providing a pairing research tool for investigating mechanism of radiation tolerance and the reverse strategy in lung cancer .Methods The NCI-H446 cell was radiated repeatedly by increased dose of radiation gradually (total 7500cGy) and a radiation-resistant cell substrain was induced and selected from the survival of cells .The doubling time and cell cycle distribution of the substrain were detected by ATP kit and flow cytometry Assay respectively ;Radiation biology parameters were calculated and analyzed by cell survival curve fitting from multi -target model, SF=1-(1-e-D/D0) N.Results Comparing with the control , The resistant substrain radiobiology parameter values were D 0 ( 1.9673, 2.2756), N(1.0016,2.6008), Dq (0.6783,1.6860)and SF2(0.3623,0.7134) respectively.Cell morphology is more slender and has more tentacles .The SF2 value of radiation-resistant subline is 1.97 times more than that of wild cell line . The proportion of radiation-resistant cells in G2/M-phase was down to 7.84%, compared with the 18.52%of wild cells. Conclusions A radiation-resistant SCLC subline NCI-H446-R is established and may be a useful tool for studying resistant to radiation of SCLC in the future .
ABSTRACT
Objective:To construct K-ras-targeted siRNAs (K-ras siRNA) and to investigate the inhibitory effects of K-ras siRNAs on the growth and migration of lung cancer A549 cells (containing mutant K-ras gene) and NCI-H446 cells (containing wild-type K-ras gene). Methods: Four K-ras siRNAs (K-ras siRNA1～K-ras siRNA3 targeting wild-type K-ras and K-ras siRNA4 targeting mutant K-ras) were designed and artificially synthesized; they were used to transfect A549 cells and NCI-H446 cells. The expressions of Ras mRNA and protein were examined by RT-PCR and Western blot-ting. The inhibitory effects of K-ras siRNAs on the proliferations of A549 and NCI-H446 cells were determined by MTT assay. The effects of K-ras siRNAs on the cell migration and apoptosis were observed by Transwell assay and Hoechst 33258 staining, respectively. Results: Mutant K-ras-targeted siRNA (K-ras siRNA4) specifically inhibited the K-ras ex-pression but had no influence on H-ras and N-ras expression in A549 cells. K-ras siRNA4 inhibited the proliferation of A549 cells but did not inhibit that of NCI-H446 cells, which contained wild type K-ras gene. K-ras siRNA4 also induced apoptosis and inhibited migration of A549 cells. Conclusion: Mutant K-ras-targeted siRNA4 can inhibit the proliferation, migration and induce apoptosis of A549 cells. It may be a potential and personalized drug for the treatment against lung cancer containing mutant K-ras gene.