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: Shirley K Knauer, Britta Unruhe, Sarah Karczewski, Rouven Hecht, Verena Fetz, Carolin Bier, Sandra Friedl, Barbara Wollenberg, Ralph Pries, Negusse Habtemichael, Ulf-Rüdiger Heinrich, Roland H Stauber
• Journal: Human mutation (Hum Mutat) Vol. 34 Issue 2 Pg. 395-404 (Feb 2013) ISSN: 1098-1004 [Electronic] United States
• PMID: 23161837 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2012 Wiley Periodicals, Inc.

Chemical References

• BIRC5 protein, human
• Fatty Acids, Unsaturated
• Inhibitor of Apoptosis Proteins
• Nuclear Export Signals
• Survivin
• Cisplatin
• leptomycin B

Topics

• Active Transport, Cell Nucleus
• Animals
• Apoptosis (drug effects)
• Carcinoma, Squamous Cell (diagnosis, drug therapy)
• Cell Line, Tumor
• Cell Nucleus (genetics, metabolism)
• Cisplatin (therapeutic use)
• Cytoplasm (genetics, metabolism)
• Disease Models, Animal
• Fatty Acids, Unsaturated (pharmacology)
• Female
• Head and Neck Neoplasms (diagnosis, drug therapy)
• Humans
• Immunohistochemistry
• Inhibitor of Apoptosis Proteins (genetics, metabolism)
• Mice
• Mutation
• Nuclear Export Signals (genetics)
• Prognosis
• Survivin