Plasma Levels of Heat Shock Protein 90 Alpha Associated with Lung Cancer Development and Treatment Responses

Abstract Purpose: Altered expression of heat shock protein 90 alpha (Hsp90α) was associated with tumor development, progression, and metastasis. This study explored plasma levels of Hsp90α protein in patients with lung cancer and other controls to assess its diagnostic value and monitor treatment responses for patients with lung cancer. Experimental Design: A total of 2,247 individuals were recruited and assigned into two cohorts as static and dynamic groups. ELISA analysis and confirmation of plasma Hsp90α protein levels for association with tumor stages and treatment responses, respectively, were performed. Results: The average plasma levels of Hsp90α protein in patients with lung cancer were significantly higher than in healthy controls (P < 0.0001). Plasma levels of Hsp90α protein in patients with advanced lung cancer (stage III–IV) were higher than in patients with early-stage lung cancer (stage I–II; P < 0.001). Using a cutoff value of 56.33 ng/mL to separate lung cancer from other controls, the sensitivity and specificity reached 72.18% (95% CI, 0.695–0.749) and 78.70% (95% CI, 0.761–0.813), respectively. To confirm the different levels in the second cohort, plasma levels of Hsp90α protein showed a statistically significant difference between preoperative and postoperative patients in surgical patient groups (P < 0.007). There was also a statistically significant difference between the disease progressive group and stable disease group, with regard to partial response after chemotherapy (P < 0.0001). Conclusions: This study demonstrated that plasma Hsp90α protein levels are useful as a diagnostic biomarker in lung cancer and predict the responses of patients with lung cancer to chemotherapy. Clin Cancer Res; 20(23); 6016–22. ©2014 AACR.