ABSTRACT
<p><b>OBJECTIVE</b>To investigate the biological behaviors and chemosensitivity of non-small cell lung cancer (NSCLC) cell line A549 after IGF-IR gene silencing by RNA interference (RNAi) in vitro.</p><p><b>METHODS</b>Two plasmids siRNA 1 and 2 expressing IGF-IR siRNA with human U6 promoter were constructed,and an unrelated siRNA was used as negative control. NSCLC A549 cells were transfected with sequence-specific siRNA or unrelated siRNA as control. Quantitative RT-PCR and Western blot were used to detect the expression of IGF-IR. NSCLC A549 cells were transfected with siRNA and treated with DDP. MTT assay and flow cytometry were used to assess the effects of IGF-IR silencing on tumor cell proliferation and chemosensitivity.</p><p><b>RESULT</b>Transfection of NSCLC cells with siRNA resulted in reduction of IGF-IR mRNA expression by 78.9 % and protein production by 89.8%. The decrease in IGF-IR levels caused significant growth inhibition of A549 cells both at 48 h and at 72 h, and decrease of the IC50 of DDP at 24 h, 48 h and at 72 h. Flow cytometry showed that 77.5% of A549 cells retained in G0/G1 phase.</p><p><b>CONCLUSION</b>The sequence specific suppression of IGF-IR gene expression by RNAi enhances sensitivity to DDP in NSCLC cell.</p>
Subject(s)
Humans , Carcinoma, Non-Small-Cell Lung , Genetics , Metabolism , Pathology , Cell Line, Tumor , Cell Proliferation , Gene Silencing , Lung Neoplasms , Genetics , Metabolism , Pathology , Plasmids , Genetics , RNA Interference , RNA, Messenger , Metabolism , RNA, Small Interfering , Genetics , Receptor, IGF Type 1 , Metabolism , TransfectionABSTRACT
<p><b>OBJECTIVE</b>To study the effect on synthesis of nitric oxide in myocardium by local cryoablation and to investigate its mechanism.</p><p><b>METHODS</b>Myocardium was cryoablated locally by a probe cooled to -60 degrees C and rewarmed by normal salt solution, nitric oxide and its synthesis enzyme were measured before and after cryoablation. L-arginine or methylene blue was added before and during cryoablation and the effect of these drugs on synthesis of nitric oxide was studied.</p><p><b>RESULTS</b>Nitric oxide and its synthesis enzyme decreased after cryoablation; L-arginine preserved the synthesis of nitric oxide and methylene blue inhibited the synthesis of nitric oxide. However, nitric oxide in serum did not change.</p><p><b>CONCLUSION</b>Nitric oxide and its synthesis enzyme in myocardium decrease after cryoablation.</p>