This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Chang, J.-Y. Articles by Chen, L.-T. Search for Related Content PubMed PubMed Citation Articles by Chang, J.-Y. Articles by Chen, L.-T.

Novel Mutation of Topoisomerase I in Rendering Cells Resistant to Camptothecin

Division of Cancer Research, National Health Research Institutes, 100 Taipei, Taiwan [J-Y. C., J-F. L., S-H. J., T-W. L., L-T. C.], and Division of Gastroenterology, Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan [L-T. C.], Republic of China

To identify mechanisms of camptothecin (CPT) resistance and the relationship between CPT-resistant cells and other anticancer agents, a CPT-resistant cell line (CPT30) and its partial revertant cell line (CPT30R) were established from a human nasopharyngeal carcinoma cell line (HONE-1). CPT30 and CPT30R cells displayed a 14- and 3.5-fold resistance to CPT compared with HONE-1 cells, respectively. The resistant and partial revertant cell lines showed cross-resistance to topotecan and increased sensitivity to cisplatin, carboplatin, and 1,3-bis(chloroethyl)-1-nitrosurea. The topoisomerase (Top) I catalytic activity of CPT30 and CPT30R cells was 30% and 200%, respectively, compared with that of HONE-1 cells. The expression of Top I protein and mRNA levels in CPT30 cells was 40% and 30% less than that in HONE-1 cells, respectively, whereas in CPT30R cells, the levels of Top I protein and mRNA were 50% and 20% higher, respectively, than that in HONE-1 cells. Both the resistant and revertant cell line whole-cell lysates demonstrated different levels of sensitivity to CPT in in vitro assays in comparison with that of HONE-1 cells. Furthermore, CPT exhibited 15- and 7-fold better binding affinity in stabilizing protein-linked DNA breaks in HONE-1 cells than in CPT30 and CPT30R cells, respectively. Direct DNA sequencing of the reverse transcription-PCR product and genomic DNA revealed a point mutation resulting in E418K mutation in the Top I of both CPT30 and CPT30R cells. Wild-type Top I RNA and genomic DNA were also detected in these two cell lines. A yeast system was used to examine whether this mutation could be responsible for CPT resistance. Our results showed that a single amino acid change (E418K) resulted in CPT resistance. Therefore, quantitative and qualitative changes in Top I were responsible for CPT resistance in CPT30 cells. CPT resistance in CPT30R cells was caused by mutation of Top I.

This article has been cited by other articles:

				L.-C. Ma, C.-C. Kuo, J.-F. Liu, L.-T. Chen, and J.-Y. Chang Transcriptional Repression of O6-Methylguanine DNA Methyltransferase Gene Rendering Cells Hypersensitive to N,N'-Bis(2-chloroethyl)-N-nitrosurea in Camptothecin-Resistant Cells Mol. Pharmacol., August 1, 2008; 74(2): 517 - 526. [Abstract] [Full Text] [PDF]

				P. Fiorani, G. Chillemi, C. Losasso, S. Castelli, and A. Desideri The different cleavage DNA sequence specificity explains the camptothecin resistance of the human topoisomerase I Glu418Lys mutant Nucleic Acids Res., October 6, 2006; 34(18): 5093 - 5100. [Abstract] [Full Text] [PDF]

				P. Luo, Q. He, X. He, Y. Hu, W. Lu, Y. Cheng, and B. Yang Potent antitumor activity of 10-methoxy-9-nitrocamptothecin. Mol. Cancer Ther., April 1, 2006; 5(4): 962 - 968. [Abstract] [Full Text] [PDF]

				Y. Arakawa, H. Suzuki, S. Saito, and H. Yamada Novel missense mutation of the DNA topoisomerase I gene in SN-38-resistant DLD-1 cells. Mol. Cancer Ther., March 1, 2006; 5(3): 502 - 508. [Abstract] [Full Text] [PDF]

				C.-C. Kuo, J.-F. Liu, and J.-Y. Chang DNA Repair Enzyme, O6-Methylguanine DNA Methyltransferase, Modulates Cytotoxicity of Camptothecin-Derived Topoisomerase I Inhibitors J. Pharmacol. Exp. Ther., February 1, 2006; 316(2): 946 - 954. [Abstract] [Full Text] [PDF]

				P. Fiorani, A. Bruselles, M. Falconi, G. Chillemi, A. Desideri, and P. Benedetti Single Mutation in the Linker Domain Confers Protein Flexibility and Camptothecin Resistance to Human Topoisomerase I J. Biol. Chem., October 31, 2003; 278(44): 43268 - 43275. [Abstract] [Full Text] [PDF]

				B. L. Staker, K. Hjerrild, M. D. Feese, C. A. Behnke, A. B. Burgin Jr., and L. Stewart The mechanism of topoisomerase I poisoning by a camptothecin analog PNAS, November 26, 2002; 99(24): 15387 - 15392. [Abstract] [Full Text] [PDF]