HSET overexpression fuels tumor progression via centrosome clustering-independent mechanisms in breast cancer patients
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Vaishali Pannu1, Padmashree C.G. Rida1, Angela Ogden1, Ravi Chakra Turaga1, Shashikiran Donthamsetty1, Nathan J. Bowen2, Katie Rudd3, Meenakshi V. Gupta4, Michelle D. Reid5, Guilherme Cantuaria6, Claire E. Walczak7 and Ritu Aneja1
1 Department of Biology, Georgia State University, Atlanta, GA, USA
2 Center for Cancer Research and Therapeutic Development, Clark Atlanta University, Atlanta, GA, USA
3 Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, USA
4 Clinical Pathology & Anatomic Pathology, West Georgia Hospitals, LaGrange, GA, USA
5 Department of Pathology, Emory University School of Medicine, Atlanta, GA, USA
6 Department of Gynecologic Oncology, Northside Hospital Cancer Institute, Atlanta, GA, USA
7 Department of Medical Sciences, Indiana University, Bloomington, IN, USA
Ritu Aneja, email:
Keywords: HSET, centrosome clustering, microtubule motor, cell-cycle kinetics, tumor progression
Received: December 22, 2014 Accepted: January 20, 2015 Published: February 28, 2015
Human breast tumors harbor supernumerary centrosomes in almost 80% of tumor cells. Although amplified centrosomes compromise cell viability via multipolar spindles resulting in death-inducing aneuploidy, cancer cells tend to cluster extra centrosomes during mitosis. As a result cancer cells display bipolar spindle phenotypes to maintain a tolerable level of aneuploidy, an edge to their survival. HSET/KifC1, a kinesin-like minus-end directed microtubule motor has recently found fame as a crucial centrosome clustering molecule. Here we show that HSET promotes tumor progression via mechanisms independent of centrosome clustering. We found that HSET is overexpressed in breast carcinomas wherein nuclear HSET accumulation correlated with histological grade and predicted poor progression-free and overall survival. In addition, deregulated HSET protein expression was associated with gene amplification and/or translocation. Our data provide compelling evidence that HSET overexpression is pro-proliferative, promotes clonogenic-survival and enhances cell-cycle kinetics through G2 and M-phases. Importantly, HSET co-immunoprecipitates with survivin, and its overexpression protects survivin from proteasome-mediated degradation, resulting in its increased steady-state levels. We provide the first evidence of centrosome clustering-independent activities of HSET that fuel tumor progression and firmly establish that HSET can serve both as a potential prognostic biomarker and as a valuable cancer-selective therapeutic target.
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