Modulation of drug resistance by alpha-tubulin in paclitaxel-resistant human lung cancer cell lines.
Beta(beta)-tubulin isotype variation has recently been implicated in the modulation of resistance to paclitaxel in human lung cancer cells and in primary human ovarian tumour samples. Whether alpha-tubulin is involved in drug resistance has not been reported. We have generated a paclitaxel-resistant cell line (H460/T800) from the sensitive human lung carcinoma parental cell line NCI-H460. The resistant cells are more than 1000-fold resistant to taxol and overexpress P-glycoprotein. Interestingly, H460/T800 cells also overexpress alpha- and beta-tubulin as detected by Western blot analysis. From Northern blot analysis, the mechanism of tubulin overexpression appears to be post-transcriptional. To understand whether alpha-tubulin plays a role in drug resistance, we transfected antisense human kalpha1 cDNA construct into the H460/T800 paclitaxel-resistant cells. The antisense clones displayed a reduced alpha-tubulin expression, and the cells were 45-51% more sensitive to paclitaxel and other known antimitotic drugs, compared with vector transfected controls. Complementary experiments of transfecting the sense kalpha1 cDNA into H460 cells conferred a 1.8- to 3.3-fold increase in the IC(50) of several antimitotic agents. Our study suggests that alpha-tubulin is one of the factors that contributes to drug resistance.
Pharmaceutical Products Division, Cancer Research, Dept. 4N6, Bldg. AP9, Abbott Laboratories, IL 60064-3500, Abbott Park, USA.
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EK
Han
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Kyu-Ho Han
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L
Gehrke
S K
SK
Tahir
R B
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Credo
S P
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Cherian
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Sham
S H
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Rosenberg
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Ng
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism; D000972:Antineoplastic Agents, Phytogenic / Q000627:therapeutic use*; D015152:Blotting, Northern; D015153:Blotting, Western; D002453:Cell Cycle; D002455:Cell Division; D016373:DNA, Antisense / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D019008:Drug Resistance, Neoplasm; D005434:Flow Cytometry; D006801:Humans; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D017239:Paclitaxel / Q000627:therapeutic use*; D014162:Transfection; D014404:Tubulin / Q000378:metabolism / Q000502:physiology*; D014407:Tumor Cells, Cultured
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000972:Antineoplastic Agents, Phytogenic; D016373:DNA, Antisense; D018076:DNA, Complementary; D014404:Tubulin; D017239:Paclitaxel