Drug resistance associated with loss of p53 involves extensive alterations in microtubule composition and dynamics

Abstract

In the present study, we compared the dynamics and composition of microtubules in cell lines derived from the human breast adenocarcinoma MCF-7 containing either the wild-type p53 (wt-p53; MN1) or a dominant-negative variant of p53 gene (mut-p53; MDD2). Mut-p53 cells were significantly resistant to the cytotoxicity of the microtubule-targeted drugs (vinca alkaloids and taxanes), as compared with wt-p53 cells. Studies by high-resolution time-lapse fluorescence microscopy in living cells indicated that the dynamics of microtubules of mut-p53 cells were altered in complex ways and were significantly increased as compared with microtubules in wt-p53 cells. The percentage of time microtubules spent in growing and shortening phases increased significantly, their catastrophe frequency increased, and their overall dynamicity increased by 33%. In contrast, their shortening rate and the mean length shortened decreased. Cells containing mut-p53 displayed increased polymerisation of tubulin, increased protein levels of the class IV b-tubulin isotype, STOP and survivin, and reduced protein levels of class II b-tubulin isotype, MAP4 and FHIT. We conclude that p53 protein may contribute to the regulation of microtubule composition and function, and that alterations in p53 function may generate complex microtubule-associated mechanisms of resistance to tubulin-binding agents.

Microtubules in 3D cell motility

“…Cip1 and p27 Kip1 , which is frequently found in cancers, has been associated with alterations in microtubule dynamics (Baldassarre et al, 2005;Bouchet et al, 2011;Galmarini et al, 2003). The expression or function of other microtubule regulators, such as survivin Rosa et al, 2006), ATIP3 (Molina et al, 2013;Velot et al, 2015) and the +TIPs EB1 (Liu et al, 2009;Stypula-Cyrus et al, 2014) and APC (Etienne-Manneville, 2009), was found to be altered in certain cancers, but the exact role of these proteins in 3D cell migration is still unclear.…”

Regulation of Class II β-Tubulin Expression by Tumor Suppressor p53 Protein in Mouse Melanoma Cells in Response toVincaAlkaloid

“…Taken together with EMSA results, p53 protein is thought to usually bind to this region to suppress mTUBB2 expression and that vincristine inhibits the binding of p53 to the response element, allowing for increased expression of class II h-tubulin. Other studies found that p53 transcriptionally downregulated microtubule-associated protein 4 (43) and that human breast adenocarcinoma cells harboring a mutated p53 gene displayed an increased level of class IV h-tubulin isotype and reduced levels of class I and II isotypes, suggesting that the p53 gene may differentially regulate expression of h-tubulin isotypes (28,29,32). These findings suggest that p53 could transcriptionally regulate components of the microtubule system.…”

“…It is well known that altered h-tubulin expression is associated with resistance to antimicrotubule drugs (7,8,18,29,37). Vinca alkaloid-resistant leukemia cells have been shown to display decreased class III h-tubulin isotype expression (8), whereas increased mRNA expression of class I, III, and IVa h-tubulin isotypes in Taxol-resistant sublines of epithelial ovarian tumors (22) and significant increases in class IVa h-tubulin isotype expression in Taxol-resistant canine osteosarcoma (37) have been reported.…”

“…Although these molecular mechanisms are not fully understood, in vitro studies have indicated that the isotypic composition of h-tubulin affects sensitivity to antimicrotubule drugs (7,25,26). On the other hand, the effect of tumor suppressor p53 protein on sensitivity to microtubule-targeted drugs has been investigated, with mutations in the p53 gene being shown to confer resistance to microtubule-targeted drugs (27)(28)(29). Patients with tumors having p53 mutation often have worse prognosis than those with wild-type p53 (29)(30)(31)(32).…”

“…On the other hand, the effect of tumor suppressor p53 protein on sensitivity to microtubule-targeted drugs has been investigated, with mutations in the p53 gene being shown to confer resistance to microtubule-targeted drugs (27)(28)(29). Patients with tumors having p53 mutation often have worse prognosis than those with wild-type p53 (29)(30)(31)(32). Recently, two genes coding for proteins homologous to p53 (i.e., p73 and p63/p51) have been identified (33).…”