[Down-regulation of TopI by RNA interference reduces the drug-sensitivity of small cell lung cancer cell lines to topotecan].
OBJECTIVE
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).


METHODS
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.


RESULTS
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).


CONCLUSIONS
siRNAs can silence the expression of TopI and decrease the drug-sensitivity of H446 cells to TPT.
Liu
Xiu-ju
XJ
Department of Chemotherapy, Shandong Tumor Hospital, Jinan 250117, China.
Guo
Qi-sen
QS
Zhang
Qiong
Q
Song
Xian-rang
XR
Liu
Yong-lei
YL
Guo
Chen
C
D000970:Antineoplastic Agents / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004264:DNA Topoisomerases, Type I / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation; D019008:Drug Resistance, Neoplasm; D006801:Humans; D008175:Lung Neoplasms / Q000378:metabolism / Q000473:pathology*; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics*; D055752:Small Cell Lung Carcinoma / Q000378:metabolism / Q000473:pathology; D019772:Topotecan / Q000494:pharmacology*; D014162:Transfection
D000970:Antineoplastic Agents; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D019772:Topotecan; D004264:DNA Topoisomerases, Type I