Abstract
<div>Abstract<p><b>Purpose:</b> While effective targeted therapies exist for estrogen receptor–positive and HER2-positive breast cancer, no such effective therapies exist for triple-negative breast cancer (TNBC); thus, it is clear that additional targets for radiosensitization and treatment are critically needed.</p><p><b>Experimental Design:</b> Expression microarrays, qRT-PCR, and Western blotting were used to assess MELK RNA and protein expression levels. Clonogenic survival assays were used to quantitate the radiosensitivity of cell lines at baseline and after MELK inhibition. The effect of MELK knockdown on DNA damage repair kinetics was determined using γH2AX staining. The <i>in vivo</i> effect of MELK knockdown on radiosensitivity was performed using mouse xenograft models. Kaplan–Meier analysis was used to estimate local control and survival information, and a Cox proportional hazards model was constructed to identify potential factors impacting local recurrence-free survival.</p><p><b>Results:</b> MELK expression is significantly elevated in breast cancer tissues compared with normal tissue as well as in TNBC compared with non-TNBC. MELK RNA and protein expression is significantly correlated with radioresistance in breast cancer cell lines. Inhibition of MELK (genetically and pharmacologically) induces radiation sensitivity <i>in vitro</i> and significantly delayed tumor growth <i>in vivo</i> in multiple models. Kaplan–Meier survival and multivariable analyses identify increasing MELK expression as being the strongest predictor of radioresistance and increased local recurrence in multiple independent datasets.</p><p><b>Conclusions:</b> Here, we identify MELK as a potential biomarker of radioresistance and target for radiosensitization in TNBC. Our results support the rationale for developing clinical strategies to inhibit MELK as a novel target in TNBC. <i>Clin Cancer Res; 22(23); 5864–75. ©2016 AACR</i>.</p></div>
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
