Overexpression of Sig1R is closely associated with tumor progression and poor outcome in patients with hilar cholangiocarcinoma.

Nonopioid Sigma1 receptor (Sig1R), which regulates various metabolism functions, has been implicated in cancers; yet, its role in hilar cholangiocarcinoma remains unclear. In the present study, we examined Sig1R expression in hilar cholangiocarcinoma (HC) tissues and explored its possible clinical values. Tissue microarray blocks containing 92 HC tissues and matched non-cancerous bile duct tissues were examined immunohistochemically for expression of Sig1R protein. Overexpression of Sig1R was found in 43 (46.7%) of the 92 primary tumor tissues. Overexpression of Sig1R was significantly associated with poor/undifferentiation (P = 0.011), tumor invasion (P = 0.001), lymph node metastasis (P = 0.047), and advanced disease stage (P = 0.024) of HC patients. Kaplan-Meier analysis showed that patients overexpressing Sig1R had an earlier recurrence and worse overall survival than those not overexpressing Sig1R. Cox regression analysis revealed that Sig1R was an independent factor to predict HC recurrence and prognosis of HC patients. Our results suggest that Sig1R is frequently activated in human HC tissue and overexpression of Sig1R might serve as a predictor for tumor recurrence and a prognostic biomarker for HC patients.