AMIGO2 expression at the invasive front of bladder cancer predicts recurrence-free and overall survival after radical cystectomy.

Bladder cancer is a leading cause of cancer-related mortality worldwide, partly due to the absence of reliable biomarkers for the accurate prediction of patient prognosis. Amphoterin-induced gene and open reading frame 2 (AMIGO2) expression is a prognostic factor in several types of cancer. The present study aimed to clarify whether AMIGO2 expression can predict the prognosis of patients with bladder cancer. This retrospective study included patients with primary bladder cancer who underwent radical cystectomy at Tottori University Hospital (Yonago, Japan) and its affiliated hospitals between January 2010 and December 2017. Tumor tissues and data were collected from 100 patients and immunohistochemical analysis was performed. The independent predictors in multivariate analysis were lymph node metastasis for recurrence-free survival (RFS), and AMIGO2 expression and pathological T stage for overall survival (OS). Furthermore, AMIGO2 expression was evaluated at the invasive tumor front, and it was revealed that AMIGO2 expression was an independent prognostic factor for both RFS and OS, in addition to lymph node metastasis for RFS. Ki-67 expression, a marker of cell proliferation that is also associated with poor prognosis in several types of cancer, was examined, and Ki-67 expression and lymph node metastasis were identified as independent prognostic factors in RFS, but not in OS. However, the co-expression of AMIGO2 and Ki-67 was identified as an independent prognostic factor for OS. In conclusion, AMIGO2 expression may be considered a novel biomarker for the identification of the risk of recurrence and reduced survival in patients with bladder cancer, and could be used as a rationale for initiating treatment, such as radiation therapy, chemotherapy or immunotherapy, after radical cystectomy.