Validation of PRKCB Immunohistochemistry as a Biomarker for the Diagnosis of Ewing Sarcoma

Abstract

Background: Ewing sarcoma (ES) can be confirmed by identifying the EWSR1-FLI1 fusion transcript. This study is to investigate whether immunostaining (IHC) of PRKCB—a protein directly regulated by EWSR1-FLI1 is a surrogate maker for diagnosing ES in routine practice. Methods: Microarray gene expression analyses were conducted. RKCB IHC was applied to 69 ES confirmed by morphology and molecular methods, and 41 non-Ewing small round cell tumors. EWSR1 rearrangement, EWSR1-FLI1 fusion or t(11;22)(q24;q12) were identified by fluorescence in situ hybridization, reverse transcriptase polymerase chain reaction, or cytogenetic analysis, respectively. Results: Gene array analyses showed significant overexpression of the PRKCB in ES. PRKCB IHC was positive in 19 cases of ES with EWSR1-FLI1 fusion, 3 cases with cytogenetic 11:22 translocation and 59 cases with EWSR1 rearrangement while negative in only one EWSR1 rearranged case. PRKCB IHC is sensitive (98%) and specific (96%) in detecting EWSR1 rearranged ES. Conclusions: PRKCB is a reliable antibody for diagnosing ES in routine practice.

Keywords:

• PRKCB
• Ewing sarcoma
• immunohistochemistry
• molecular testing
• EWSR1
• FLI1
• diagnosis
• biomarker
• validation

Acknowledgments

The authors are grateful that editorial assistance was provided by the Moffitt Cancer Center’s Office of Scientific Publishing by Dr. Paul Fletcher & Daley Drucker. No compensation was given beyond their regular salaries. The collaborating institutions include the Departments of Pathology and Genetics, University of Alabama at Birmingham, AL, Department of Pathology and Laboratory, Children’s of Alabama, University of Alabama at Birmingham, AL, and Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE.

Additional information

Funding

This work has been supported in part by the Tissue Core, the Analytic Microscopy Core, and Histology Laboratory at the H. Lee Moffitt Cancer Center & Research Institute, a comprehensive cancer center designated by the National Cancer Institute and funded in part by Moffitt’s Cancer Center Support Grant (P30-CA076292).