Abstract
The goal of this study was to determine the prevalence of sequence variants in the class I β-tubulin (clone m40) gene and their occurrence in human tumors and cancer cell lines. DNA was isolated from 93 control individuals representing a wide variety of ethnicities, 49 paclitaxel-naive specimens (16 ovarian cancers, 17 non-small cell lung cancers, and 16 ovarian cancer cell lines), and 30 paclitaxel-resistant specimens (9 ovarian cancers, 9 ovarian cancer cell lines, and 12 ovarian cancer xenografts in nude mice). Denaturing high-performance liquid chromatography and direct sequence analysis detected two silent polymorphisms in exon 4, Leu217Leu (CTG/CTA) and Gly400Gly (GGC/GGT), with minor allele frequencies of 17 and 0.5%, respectively. Five nucleotide substitutions and one single-base deletion were detected in introns 1, 2, and 3 and in the 3′ untranslated region. Analysis of 49 paclitaxel-naive and 30 paclitaxel-resistant specimens revealed no additional polymorphisms in the coding region. In addition, no amino acid replacements were found in chimpanzee, gorilla, and orangutan in comparison to human. Our data demonstrate a very high degree of sequence conservation in class I β-tubulin, suggesting that all residues are important in tubulin structure and function. Individual variation in response to treatment with paclitaxel is not likely to be caused by genetic variations in the β-tubulin drug target. Moreover, acquired mutations in class I β-tubulin are unlikely to be a clinically relevant cause of drug resistance.
Footnotes
↵1 This work was supported by NIH Grants R01 CA 68217 (to B. I. S.) and R01 HG01932 (to P. J. O.), California Cancer Research Program Grant 99-00561V-10091 (to B. I. S.), and the Margaret Fagin and Beatrice Quackenbush Ovarian Cancer Research Funds.
↵2 To whom requests for reprints should be addressed, at Stanford University School of Medicine, Oncology Division, 269 Campus Drive, CCSR-1105, Stanford, CA 94305-5151. Phone: (650) 725-6427; Fax: (650) 736-1454; E-mail: brandy{at}stanford.edu
↵3 The abbreviations used are: SNP, single nucleotide polymorphism; UTR, untranslated region; DHPLC, denaturing high pressure liquid chromatography; MMR, mismatch repair.
↵4 Available at http://insertion.stanford.edu/melt.html.
↵5 Internet address: http://www.ncbi.nlm.nih.gov/LocusLink/list.cgi.
↵6 L. Svensson and P. J. Oefner, unpublished data.
↵7 Internet address: http://www.ncbi.nlm.nih.gov/BLAST/.
- Accepted December 3, 2001.
- Received October 18, 2001.
- Revision received November 29, 2001.
- Molecular Cancer Therapeutics