Bis Expression in Patients with Surgically Resected Lung Cancer and its Clinical Significance

Background: Bis, also known as BAG3, has been identified as a Bcl-2-interacting protein that enhances cellular anti-apoptotic activity. It is involved in cellular differentiation, angiogenesis, migration, and invasion in various tumors. The purpose of this study was to investigate the Bis expression pattern, and the clinical significance thereof, in patients with resected lung cancer. Methods: We studied 121 lung cancer patients who underwent curative surgical resection. Patient clinicopathological characteristics were reviewed retrospectively from medical records, including tumor recurrence and survival. The expression of Bis protein in lung cancer tissues was evaluated by immunohistochemical staining and was assessed using a four-tiered intensity score system (negative, weak, moderate, strong). Enhanced Bis expression at the periphery of a tumor facing the adjacent nontumor region was referred as “marginal activity.” Results: Although Bis expression was higher in squamous cell carcinoma than in adenocarcinoma, marginal activity was higher in adenocarcinoma than in squamous cell carcinoma. All of the small cell carcinomas and lung cancer with neuroendocrine differentiation examined were negative for Bis expression. Compared with stage I lung cancer, patients with stage II and IIIA lung cancer exhibited higher Bis protein levels in lung tissues. Recurrence and survival rates did not differ significantly according to Bis expression intensity score or marginal activity. Conclusions: Our study demonstrated that Bis expression differed according to the histological type and pathological stage of the lung cancer. Further studies are needed to assess its use as a biomarker and its role in the molecular pathogenesis of lung cancer.