ABSTRACT
<p><b>OBJECTIVE</b>To investigate the expressions of TopI gene in small cell lung cancer cell line H446, and explore the influence of TopI on the chemosensitivity of the cell line to topotecan (TPT).</p><p><b>METHODS</b>Western blot was performed to detect the TopI expression in H446 cells. Lipofectamine 2000 was used for the transient transfection of H446 cells by siRNA, and the transfection efficacy was detected. TopI mRNA was analyzed by quantitative RT-PCR and TopI protein was detected by Western blot to selected effective siRNA. The drug-sensitivity to topotecan (TPT) was evaluated by MTT assay.</p><p><b>RESULTS</b>TopI gene was expressed in H446 cells. Lipofectamine 2000 mediated the siRNA effectively (88.67%). Compared with its parental cells, RT-PCR results showed that TopI mRNAs in transfected cells were reduced by (95.7 +/- 1.6)%, (90.8 +/- 1.6)%, (96.1 +/- 2.7)% and (96.3 +/- 1.8)%, respectively, and decreased significantly at protein level. By MTT assay, the inhibition rate of TPT to H446 cells transfected by siRNA was lower than that of control group at same concentrations (P < 0.01).</p><p><b>CONCLUSION</b>siRNAs can silence the expression of TopI and decrease the drug-sensitivity of H446 cells to TPT.</p>
Subject(s)
Humans , Antineoplastic Agents , Pharmacology , Cell Line, Tumor , Cell Proliferation , DNA Topoisomerases, Type I , Genetics , Metabolism , Down-Regulation , Drug Resistance, Neoplasm , Lung Neoplasms , Metabolism , Pathology , RNA Interference , RNA, Messenger , Metabolism , RNA, Small Interfering , Genetics , Small Cell Lung Carcinoma , Metabolism , Pathology , Topotecan , Pharmacology , TransfectionABSTRACT
<p><b>OBJECTIVE</b>To investigate the expression and its significance of DNA topoisomerase I (Topo I) in small cell lung cancer (SCLC).</p><p><b>METHODS</b>Topo I expression was detected by immunohistochemical S-P technique on 50 cases of SCLC and 12 cases of normal lung tissues.</p><p><b>RESULTS</b>The total positive rate of Topo I in normal lung tissue was 25.0% (3/12) and 78.0% (39/50) in SCLC. The expression of Topo I does not correlate with age, gender, smoking, tumor size and tumor site (P > 0.05), but significantly correlated with lymph node metastasis and clinical stage (P <0.05).</p><p><b>CONCLUSION</b>High Topo I expression is a rationale indication of Topo I inhibitor treatment of malignancies. It should be possible to predict anti-tumor drug sensitivity by assessment of Topo I expression and help to improve the therapeutic efficacy for cancer patients.</p>