1 Scientific RepoRts | 5:12136 | DOi: 10.1038/srep12136 www.nature.com/scientificreports Regulation of microtubule dynamics by DIAPH3 inluences amoeboid tumor cell mechanics and sensitivity to taxanes samantha Morley 1,2,3 , sungyong You 1 , sara pollan 1 , Jiyoung Choi 2 , Bo Zhou 1 , Martin H Hager 2,3 , Kenneth steadman 1 , Cristiana spinelli 1 , Kavitha Rajendran 4 , Arkadiusz Gertych 1 , Jayoung Kim 1,2,3 , Rosalyn M Adam 2,3 , Wei Yang 1 , Ramaswamy Krishnan 4 , Beatrice s Knudsen 1 , Dolores Di Vizio 1,2,3 & Michael R Freeman 1,2,3 taxanes are widely employed chemotherapies for patients with metastatic prostate and breast cancer. Here, we show that loss of Diaphanous-related formin-3 (DIApH3), frequently associated with metastatic breast and prostate cancers, correlates with increased sensitivity to taxanes. DIApH3 interacted with microtubules (Mt), and its loss altered several parameters of Mt dynamics as well as decreased polarized force generation, contractility, and response to substrate stifness. silencing of DIApH3 increased the cytotoxic response to taxanes in prostate and breast cancer cell lines. Analysis of drug activity for tubulin-targeted agents in the NCI-60 cell line panel revealed a uniform positive correlation between reduced DIApH3 expression and drug sensitivity. Low DIApH3 expression correlated with improved relapse-free survival in breast cancer patients treated with chemotherapeutic regimens containing taxanes. our results suggest that inhibition of Mt stability arising from DIApH3 downregulation enhances susceptibility to Mt poisons, and that the DIApH3 network potentially reports taxane sensitivity in human tumors. Metastatic dissemination is a multistep process that involves cell migration, invasion and growth at distant sites. he ‘amoeboid’ phenotype has emerged as a migratory mechanism that facilitates metas- tasis 1,2 . Amoeboid behavior is prominent at the invasive front of tumors 3,4 , confers rapid migration rates 1,2,5,6 , and enables survival within the vasculature 7 . Collectively, these malignant features suggest that amoeboid cells are highly aggressive tumor cell variants that potentially evolve subsequent to an epithelial-to-mesenchymal transition (EMT 8 ). Tumor cells with amoeboid features display limited dependence on proteolysis and navigate through tissue spaces by rapidly deforming their shape 1,2 . Other characteristics of amoeboid cells include enhanced actomyosin contractility mediated by Rho kinase (ROCK) signaling, diminished adhesion, heightened chemotactic responses, and dynamic membrane blebbing 9–12 . Amoeboid morphology is reg- ulated by growth factor-, cytokine-, and MMP-dependent signaling, transcriptional reprogramming, and cytoskeletal alterations 1,2,9,13–17 . Methods of identifying amoeboid cells in vivo, and an understanding of their vulnerabilities to chemotherapies, could provide novel opportunities for therapeutic intervention. 1 Division of cancer Biology and therapeutics, Departments of Surgery and Biomedical Sciences, Samuel Oschin comprehensive cancer institute, cedars-Sinai Medical center, 8700 Beverly Boulevard, Los Angeles, cA 90048. 2 Urological Diseases Research center, Boston children’s Hospital, Boston, MA 02115. 3 Department of Surgery, Harvard Medical School, Boston, MA 02115. 4 Department of emergency Medicine, Beth israel Deaconess Medical center, Boston, MA 02115. correspondence and requests for materials should be addressed to M.R.f. (email: Michael.freeman@cshs.org) Received: 10 february 2015 Accepted: 05 May 2015 Published: 16 July 2015 opeN