Clinical significance of heat shock protein 90α expression as a biomarker of prognosis in patients with gastric cancer

Background: Heat shock protein 90 (HSP90) possesses two major isoforms - HSP90 alpha and HSP90 beta. They have essential roles in the protection against stressful conditions. They are also important for the re-establishment of cellular homeostasis. We investigated the clinical significance of HSP90 alpha and HSP90 beta expression in patients with gastric cancer (GC). Methods: HSP90 alpha and HSP90 beta expression levels were examined immunohistochemically in surgical specimens obtained from 186 GC patients. The correlations between their expression levels and clinicopathological parameters including patient survival were analyzed. Results: The frequencies of larger tumor size (maximum diameter >= 4 cm) and more prominent tumor invasion (>= pT3) in the high intensity HSP90 alpha expression group were 73.4% and 68.8% higher, respectively, than those in the low intensity group (both P = 0.001). High HSP90 alpha expression level was also significantly associated with lymphatic invasion, lymph node metastasis, and advanced stage (TNM stage >= III) disease (P = 0.047, P = 0.046, and P = 0.004, respectively). Patients with high HSP90 alpha expression levels demonstrated significantly worse survival than those with low HSP90 alpha expression levels (P = 0.047). In contrast, survival did not differ significantly according to the intensity of HSP90 beta expression. Conclusions: Our results showed that HSP90 alpha overexpression might be associated with disease progression and poorer survival in patients with GC. Therefore, HSP90 alpha could be used as possible biomarker for the prognosis of GC.