title: Functional characterization of novel mutations affecting survivin (BIRC5)-mediated therapy resistance in head and neck cancer patients.
abstract: Survivin (BIRC5) is an acknowledged cancer therapy-resistance factor and overexpressed in head and neck squamous cell carcinomas (HNSCC). Driven by its nuclear export signal (NES), Survivin shuttles between the nucleus and the cytoplasm, and is detectable in both cellular compartments in tumor biopsies. Although predominantly nuclear Survivin is considered a favorable prognostic disease marker for HNSCC patients, the underlying molecular mechanisms are not resolved. Hence, we performed immunohistochemical and mutational analyses using laser capture microdissection on HNSCC biopsies from patients displaying high levels of nuclear Survivin. We found somatic BIRC5 mutations, c.278T>C (p.Phe93Ser), c.292C>T (p.Leu98Phe), and c.288A>G (silent), in tumor cells, but not in corresponding normal tissues. Comprehensive functional characterization of the Survivin mutants by ectopic expression and microinjection experiments revealed that p.Phe93Ser, but not p.Leu98Phe inactivated Survivin's NES, resulted in a predominantly nuclear protein, and attenuated Survivin's dual cytoprotective activity against chemoradiation-induced apoptosis. Notably, in xenotransplantation studies, HNSCC cells containing the p.Phe93Ser mutation responded significantly better to cisplatin-based chemotherapy. Collectively, our results underline the disease relevance of Survivin's nucleocytoplasmic transport, and provide first evidence that genetic inactivation of Survivin's NES may account for predominantly nuclear Survivin and increased therapy response in cancer patients.
authors.affiliation: Institute for Molecular Biology, Centre for Medical Biotechnology, ZMB, University of Duisburg-Essen, Germany. shirley.knauer@uni-due.de
authors.forename: Shirley K
authors.initials: SK
authors.lastname: Knauer
authors.forename: Britta
authors.initials: B
authors.lastname: Unruhe
authors.forename: Sarah
authors.initials: S
authors.lastname: Karczewski
authors.forename: Rouven
authors.initials: R
authors.lastname: Hecht
authors.forename: Verena
authors.initials: V
authors.lastname: Fetz
authors.forename: Carolin
authors.initials: C
authors.lastname: Bier
authors.forename: Sandra
authors.initials: S
authors.lastname: Friedl
authors.forename: Barbara
authors.initials: B
authors.lastname: Wollenberg
authors.forename: Ralph
authors.initials: R
authors.lastname: Pries
authors.forename: Negusse
authors.initials: N
authors.lastname: Habtemichael
authors.forename: Ulf-Rüdiger
authors.initials: UR
authors.lastname: Heinrich
authors.forename: Roland H
authors.initials: RH
authors.lastname: Stauber
mesh_terms: D021581:Active Transport, Cell Nucleus; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002294:Carcinoma, Squamous Cell / Q000175:diagnosis* / Q000188:drug therapy; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D002945:Cisplatin / Q000627:therapeutic use; D003593:Cytoplasm / Q000235:genetics / Q000378:metabolism; D004195:Disease Models, Animal; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D005260:Female; D006258:Head and Neck Neoplasms / Q000175:diagnosis* / Q000188:drug therapy*; D006801:Humans; D007150:Immunohistochemistry; D051034:Inhibitor of Apoptosis Proteins / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D009154:Mutation; D049790:Nuclear Export Signals / Q000235:genetics; D011379:Prognosis; D000077022:Survivin
chemical_list: C107489:BIRC5 protein, human; D005231:Fatty Acids, Unsaturated; D051034:Inhibitor of Apoptosis Proteins; D049790:Nuclear Export Signals; D000077022:Survivin; D002945:Cisplatin; C038753:leptomycin B