Conservation of the class I beta-tubulin gene in human populations and lack of mutations in lung cancers and paclitaxel-resistant ovarian cancers.
The goal of this study was to determine the prevalence of sequence variants in the class I beta-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 beta-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 beta-tubulin drug target. Moreover, acquired mutations in class I beta-tubulin are unlikely to be a clinically relevant cause of drug resistance.
Sale
Sanja
S
Stanford University School of Medicine, 269 Campus Drive, CCSR-1105, Stanford, CA 94305-5151, USA.
Sung
Raphael
R
Shen
Peidong
P
Yu
Kristine
K
Wang
Yan
Y
Duran
George E
GE
Kim
Jong-Hyeok
JH
Fojo
Tito
T
Oefner
Peter J
PJ
Sikic
Branimir I
BI
D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D002289:Carcinoma, Non-Small-Cell Lung / Q000208:ethnology / Q000235:genetics*; D016022:Case-Control Studies; D017124:Conserved Sequence; D004252:DNA Mutational Analysis; D017931:DNA Primers; D004273:DNA, Neoplasm / Q000378:metabolism*; D019008:Drug Resistance, Neoplasm; D005260:Female; D014644:Genetic Variation; D006239:Haplotypes; D006579:Heterozygote; D006801:Humans; D008175:Lung Neoplasms / Q000208:ethnology / Q000235:genetics*; D051379:Mice; D009154:Mutation / Q000235:genetics*; D010051:Ovarian Neoplasms / Q000208:ethnology / Q000235:genetics*; D017239:Paclitaxel / Q000494:pharmacology*; D016133:Polymerase Chain Reaction; D018807:Polymorphism, Single-Stranded Conformational; D014404:Tubulin / Q000145:classification / Q000235:genetics*; D014407:Tumor Cells, Cultured / Q000187:drug effects
D000972:Antineoplastic Agents, Phytogenic; D017931:DNA Primers; D004273:DNA, Neoplasm; D014404:Tubulin; D017239:Paclitaxel