Molecular profiling of docetaxel cytotoxicity in breast cancer cells: uncoupling of aberrant mitosis and apoptosis

Abstract

Among microtubule-targeting agents, docetaxel has received recent interest owing to its good therapeutic index. Clinical trials have underlined its potential for the treatment of advanced breast cancer, although little is known about its molecular mode of action in this context. We characterized the molecular changes induced by docetaxel in two well-known human breast carcinoma cell lines. Two mechanisms of action according to drug concentration were suggested by a biphasic sensitivity curve, and were further validated by cell morphology, cell cycle and cell death changes. Two to four nanomolar docetaxel induced aberrant mitosis followed by late necrosis, and 100 nM docetaxel induced mitotic arrest followed by apoptosis. Passing through mitosis phase was a requirement for hypodiploidy to occur, as shown by functional studies in synchronized cells and by combining docetaxel with the proteasome inhibitor MG132. Transcriptional profiling showed differences according to cell line and docetaxel concentration, with cell cycle, cell death and structural genes commonly regulated in both cell lines. Although p53 targets were mainly induced with low concentration of drug in MCF7 cells, its relevance in the dual mechanism of docetaxel cytotoxicity was ruled out by using an isogenic shp53 cell line. Many of the genes shown in this study may contribute to the dual mechanism by which docetaxel inhibits the growth of breast cancer cells at different concentrations. These findings provide a basis for rationally enhancing docetaxel therapy, considering lower concentrations, and better drug combinations.

AMG 900, a Small-Molecule Inhibitor of Aurora Kinases, Potentiates the Activity of Microtubule-Targeting Agents in Human Metastatic Breast Cancer Models

“…Although the cell-cycle profiles were largely similar for each cell line treated with ixabepilone or paclitaxel, the P-gp-expressing DU4475 and MDA-MB-231 (F 11 ) PTX-r cells were more sensitive to ixabepilone. Consistent with previous reports, the cell-death response observed at lower concentrations of MTAs was likely driven by a transient mitotic arrest and not a sustained mitotic arrest (27).…”

Pharmacometabolomics of docetaxel-treated human MCF7 breast cancer cells provides evidence of varying cellular responses at high and low doses

“…No long-lasting cell cycle arrest in MCF7 cells exposed to low dose of DTX was observed, and DNA content was reduced but to a lesser extend than at high dose, without significant cell death in attached cells at 72 h. These findings are in agreement with literature reports. Low dose of DTX was shown to induce aberrant mitosis followed by aneuploidy and necrosis, whereas high dose induced mitotic arrest followed by mitotic slippage into tetraploid or ''pseudo-G1'' phase then apoptosis [10,26]. Our DNA content measurements, reflecting cell proliferation and DNA ploidy although consistent with literature, underestimated antiproliferative effects of DTX at high dose because of cell tetraploidy.…”

“…At low concentration (10 nM), DTX was shown to activate diacylglycerol (DAG) kinase, a lipid kinase that phosphorylates DAG into phosphatidic acid (PA) [18]. Recently, the dose dependence of the response of human breast carcinoma cells to DTX has been reported [10]. Like paclitaxel [19], DTX provoked striking differences in cell cycle according to the dose.…”

“…DTX is used as the neoadjuvant or adjuvant standard treatment in association with anthracyclines [3] and also as a monotherapy in anthracycline-refractory metastatic breast cancer patients [4,5]. DTX was shown to interrupt the normal mitotic process through the disruption of microtubules [6], to have antiangiogenic effect [7], to activate several apoptotic cellular signals such as protein kinases and caspases [8,9], and to decrease structural and antioxidative gene expression [10,11]. Reactive oxygen and nitrogen species have been reported to be involved in taxane cytotoxicity [12,13], resulting from activation of NADPH oxidase [14].…”

Docetaxel-loaded solid lipid nanoparticles suppress breast cancer cells growth with reduced myelosuppression toxicity

“…5,6 Docetaxel suppresses tumor cell growth in two different modes: at high concentration, docetaxel induces G2/M cell cycle arrest and apoptosis, whereas a very low level of docetaxel causes aberrant mitosis followed by necrosis. 7,8 Although docetaxel has many advantages in cancer therapy, it can cause serious side effects, such as neutropenia, myelosuppression, anemia, and hypersensitivity reaction, which limit its clinical applications. [9][10][11] Some of these side effects are simply induced by The authors' previous work showed that docetaxel-loaded solid lipid nanoparticles (DSNs) have many advantages compared with other nanoformulations, including easier preparation, better stability, component materials safety, and controlled release.…”