A Mechanism of Cellular Resistance to Drugs that Interfere with Microtubule Assemblya

“…The properties of the resistant cells are consistent with our previously proposed model for drug resistance; that is, mutations that confer resistance to stabilizing drugs reduce microtubule stability (i.e., decrease the assembly of the polymer), whereas mutations that confer resistance to destabilizing drugs increase microtubule stability (i.e., increase the assembly of the polymer; refs. 19,38). Although our studies measured microtubule polymer in interphase cells, the changes in microtubule assembly also affect spindle function, the main target of antimitotic drugs.…”

Section: Discussionmentioning

confidence: 99%

“…Similarly, cells selected for resistance to inhibitors of microtubule assembly frequently exhibit increased sensitivity to paclitaxel and other drugs that stabilize microtubules (19,38). To determine whether mutants with alterations in P220 follow a similar pattern, a clonogenic assay was used to determine encoding each of the indicated amino acid substitutions and selected in the presence of 2 mg/mL G418 and 1 Ag/mL tetracycline to obtain stably transfected cells.…”

Section: Cells Resistant To One Drug Show Collateral Sensitivity To Tmentioning

confidence: 99%

Amino acid substitutions at proline 220 of β-tubulin confer resistance to paclitaxel and colcemid

Yin

Cabral

Veeraraghavan³

2007

Molecular Cancer Therapeutics

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Chinese hamster ovary cells selected for resistance to paclitaxel have a high incidence of mutations affecting L215, L217, and L228 in the H6/H7 loop region of B1-tubulin. To determine whether other mutations in this loop are also capable of conferring resistance to drugs that affect microtubule assembly, saturation mutagenesis of the highly conserved P220 codon in B1-tubulin cDNA was carried out. Transfection of a mixed pool of plasmids encoding all possible amino acid substitutions at P220 followed by selection in paclitaxel produced cell lines containing P220L and P220V substitutions. Similar selections in colcemid, on the other hand, yielded cell lines with P220C, P220S, and P220T substitutions. Site-directed mutagenesis and retransfection confirmed that these mutations were responsible for drug resistance. Expression of tubulin containing the P220L and P220V mutations reduced microtubule assembly, conferred resistance to paclitaxel and epothilone A, but increased sensitivity to colcemid and vinblastine. In contrast, tubulin with the P220C, P220S, and P220T mutations increased microtubule assembly, conferred resistance to colcemid and vinblastine, but increased sensitivity to paclitaxel and epothilone A. The results are consistent with molecular modeling studies and support a drug resistance mechanism based on changes in microtubule assembly that counteract the effects of drug treatment. These studies show for the first time that different substitutions at the same amino acid residue in B1-tubulin can confer cellular resistance to either microtubule-stabilizing or microtubule-destabilizing drugs. [Mol Cancer Ther 2007; 6(10):2798 -806]

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“…These studies have extended to several antimicrotubule agents in various carcinoma cell lines. Early studies showed mutations and alterations in the steady state soluble and polymerized α and β tubulin fractions in drug resistant cell lines Cabral et al, 1986;Minotti et al, 1991). Although the existence of different α and β tubulin isotypes and their tissue specific expression was reported in the past, only recently demonstrated were the effects of individual β tubulin isotypes on overall microtubule functions including assembly, dynamics, drug sensitivity and drug binding.…”

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confidence: 99%

Modulation of endogenous β -tubulin isotype expression as a result of human βIIIcDNA transfection into prostate carcinoma cells

et al. 2001

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In the past several years many laboratories have studied the significance of α and β tubulin proteins in antimicrotubule drug resistance. These studies have extended to several antimicrotubule agents in various carcinoma cell lines. Early studies showed mutations and alterations in the steady state soluble and polymerized α and β tubulin fractions in drug resistant cell lines Cabral et al, 1986;Minotti et al, 1991). Although the existence of different α and β tubulin isotypes and their tissue specific expression was reported in the past, only recently demonstrated were the effects of individual β tubulin isotypes on overall microtubule functions including assembly, dynamics, drug sensitivity and drug binding. Banerjee et al (1990) have shown that β III isotype depleted tubulin assembles into microtubules at a faster rate than unfractioned tubulin. These microtubules are also more sensitive to paclitaxel-induced assembly compared to unfractioned tubulin (Lu and Luduena, 1993). Subsequent studies revealed alterations in the expression of specific β tubulin isotypes as result of antimicrotubule drug resistance (Haber et al, 1995;Ranganathan et al, 1996;1998a;1998b;Kavallaris et al, 1997;Kavallaris et al, 1999). In addition, combination studies have shown that cyclosporin A enhances paclitaxel efficacy in lung carcinoma cell lines by modulating β tubulin isotype composition (Ross and Antoniono, 1999). Recently, Kavallaris et al, (1999) have shown that antisense oligonucleotides to β III isotype sensitized the drug resistant cells to paclitaxel. In addition, mutations in β I isotype were reported in paclitaxel resistant human ovarian carcinoma cells (Giannakakou et al, 1997), breast carcinoma cells (Wiesen and Horwitz, 2000) and non-small-cell lung cancer patients (Monzo et al, 1999) with tumours that were unresponsive to paclitaxel therapy.Antimicrotubule drug resistance associated changes in tubulin isotypes prompted several investigators to determine the contribution of individual isotypes by transfecting cells and examining their antimicrotubule drug response. Wu et al (1998) have shown that transfection of β IVa isotype into human leukemic cell line failed to confer resistance to paclitaxel. Blade et al (1999) have over-expressed rodent β I , β II or β IVb isotypes in CHO cells and shown that these isotypes do not confer resistance to paclitaxel. Our previous work demonstrated increases in β III and β IVa isotypes in human prostate carcinoma cells that were made resistant to estramustine or paclitaxel (Ranganathan et al, 1996(Ranganathan et al, , 1998a. In addition, acute exposures to these agents resulted in elevations of β III levels. To further understand the function of β III isotype in antimicrotubule drug response, parental DU145 human carcinoma cells were transfected with the human β III cDNA. The results presented herein indicate that regulation of tubulin in cells is complex and that attempts to increase levels of a single isotype may lead to compensatory changes in the expression of other isotypes. Sum...

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A Mechanism of Cellular Resistance to Drugs that Interfere with Microtubule Assemblya

Cited by 70 publications

References 19 publications

Paclitaxel-resistant Human Ovarian Cancer Cells Have Mutant β-Tubulins That Exhibit Impaired Paclitaxel-driven Polymerization

Paclitaxel-resistant Human Ovarian Cancer Cells Have Mutant β-Tubulins That Exhibit Impaired Paclitaxel-driven Polymerization

Amino acid substitutions at proline 220 of β-tubulin confer resistance to paclitaxel and colcemid

Modulation of endogenous β -tubulin isotype expression as a result of human βIIIcDNA transfection into prostate carcinoma cells

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