Protocadherin B9 Is Associated with Human Esophageal Squamous Cell Carcinoma Progression

Abstract

Introduction: Esophageal cancer is the sixth leading cause of cancer-related death worldwide. However, molecular targeted therapy and novel therapeutic targets are needed for esophageal squamous cell cancer (ESCC). In a previous study, we reported that protocadherin (PCDH) B9 plays an important role in several cancers. Therefore, in this study, we examined the clinical significance of PCDHB9 expression in ESCC. Methods: PCDHB9 expression was examined using immunohistochemistry in 128 cases and using quantitative reverse transcription-polymerase chain reaction in 16 cases of ESCC. PCDHB9 function in ESCC cells was examined using RNA interference. Results: High PCDHB9 expression was identified in 5 of 16 (31.3%). In total, 51 (40%) ESCC cases showed strong PCDHB9 expression, whereas nonneoplastic mucosa rarely showed its expression. High PCDHB9 expression was significantly associated with T classification, N grade, and stage in ESCC. In ESCC cell lines, PCDHB9 knockdown affected cell growth, migration, and adhesion. Further, the expression of integrin (ITG) A3, ITGA4, ITGA5, ITGB1, ITGB6, vimentin, snail family transcriptional repressor 1, and cadherin 2 (NCAD) was significantly reduced and cadherin 1 was significantly increased in PCDHB9 knockdown ESCC cells. Conclusion: These results suggest that PCDHB9 plays a tumor-promoting role and is a potential biomarker and therapeutic target in ESCC.