Resistance to the tubulin-binding agents in renal cell carcinoma: no mutations in the class I beta-tubulin gene but changes in tubulin isotype protein expression.
OBJECTIVE
The primary purpose of this study was to determine whether mutations of the class I beta-tubulin gene may be implicated in the inherent resistance to tubulin-binding agents (TBA) in renal cancer, with a small number of samples and cell lines also being examined for class I and III beta-tubulin isotype protein expression.


METHODS
DNA was extracted from 90 renal tumors and the class I beta-tubulin gene analyzed for mutations. For each sample, eight PCRs were used to cover the complete coding sequence with intronic primers ensuring highly homologous pseudogenes were not coamplified. Additionally, expression levels of class I and III beta-tubulin isotypes in 17 matched normal and malignant renal samples and a panel of renal cell carcinoma cell lines with differing intrinsic resistance to the TBAs was examined by Western blotting.


RESULTS
Four polymorphic sequence changes of the class I beta-tubulin gene were identified with no mutations. Class I protein expression levels were higher in tumor tissue versus normal tissue, whereas class III expression showed no consistent change. In renal cancer cell lines, a significant correlation between class III isotype expression and vinblastine sensitivity was observed.


CONCLUSIONS
These results do not support a role for mutations in the class I beta-tubulin gene in the intrinsic resistance of renal cancer to TBAs. Class III isotype expression may be implicated in resistance in vitro but in vivo, changes in class I isotype expression in renal cell carcinoma tissue may support a role in resistance to the TBAs and warrants further investigation.
Ferguson
Roisean E
RE
Cancer Research UK Clinical Centre at Leeds, United Kingdom.
Taylor
Claire
C
Stanley
Anthea
A
Butler
Elizabeth
E
Joyce
Adrian
A
Harnden
Patricia
P
Patel
Poulam M
PM
Selby
Peter J
PJ
Banks
Rosamonde E
RE
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000378:metabolism / Q000494:pharmacology*; D015153:Blotting, Western; D002292:Carcinoma, Renal Cell / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D045744:Cell Line, Tumor; D004252:DNA Mutational Analysis; D004273:DNA, Neoplasm / Q000737:chemistry / Q000235:genetics; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D005260:Female; D006801:Humans; D007680:Kidney Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009154:Mutation; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D014404:Tubulin / Q000235:genetics* / Q000378:metabolism
D000970:Antineoplastic Agents; D004273:DNA, Neoplasm; D020033:Protein Isoforms; D014404:Tubulin