|Title:||Identification of MCAK inhibitors that induce aneuploidy in Triple Negative Breast Cancer Models|
Smith, John, Medical Sciences, Indiana University Bloomington; Stefan Husted, Indiana University – Bloomington; Jay Pilrose, Indiana University Bloomington; Disha Kuchangi, Department of Biology, Indiana University Bloomington; Richard Carpenter, Indiana University Bloomington; Claire Walczak, Indiana University Bloomington
Background/Significance/Rationale: Standard of care for triple negative breast cancer (TNBC), is chemotherapy using a combination of microtubule poisons and DNA damaging agents. Microtubule poisons, like paclitaxel, have been proposed to induce lethal levels of aneuploidy in tumor cells. While these drugs are initially effective, patients often relapse with drug resistant tumors. Developing agents against targets that limit aneuploidy may be a valuable approach for therapeutic development. One potential target is the microtubule-depolymerizing kinesin, MCAK, which reduces aneuploidy.
Methods: TCGA and GSE47561 databases were probed for MCAK expression and versus subtype and survival statistics. Knockdown studies were performed to test whether MCAK can sensitize cells to taxanes. FRET and image-based screens were used to identify MCAK inhibitors from two drug libraries. Inhibitors were tested using micronucleus, clonogenic growth, and MTT assays for potency.
Results/Findings: MCAK is upregulated in TNBC and associated with reduced survival and distant metastasis free survival. Knockdown of MCAK caused a two-five fold IC50 reduction of paclitaxel in cancer lines, with no change in normal RPE-1 cells. Paclitaxel treatment and MCAK knockdown increased aneuploidy induction, with no additive effect between the two. Our screen identified three putative MCAK inhibitors, which induced aneuploidy regardless of taxane-resistance. These inhibitors also reduced clonogenic growth, and the most potent, C4 caused an approximate five-fold reduction in paclitaxel IC50 in MTT assays.
Conclusions/Discussion: Based on bioinformatics data, MCAK can serve as a powerful biomarker of prognosis. MCAK knockdown and inhibition appears to sensitize cancer cells to taxanes, without sensitizing normal cells, making it valuable as part of a combination therapy. MCAK inhibitors also appear to reduce growth as single agents, giving them potential use as second-line therapies in resistant, relapse disease.
Translational/Human Health Impact: Our work will expand the field of precision medicine to include aneugenic drugs, while giving treatment options to cancer patients with relapsed or drug-resistant disease.