Significance of calreticulin as a prognostic factor in endometrial cancer

In patients with endometrial cancer, the expression and prognostic significance of calreticulin (CRT) remains to be fully elucidated. To investigate the role of CRT in endometrial cancer, the present study compared its expression status with clinicopathological characteristics and evaluated its prognostic significance. The expression of CRT, PKR-like endoplasmic reticulum kinase (PERK), phosphorylated eukaryotic initiation factor 2 alpha (p-eIF2 alpha), and Ki67 were assessed by immunohistochemistry and/or western blotting in endometrial cancer patients. The association of the expression of CRT, p-eIF2 alpha and Ki67 with patient survival rate was assessed by Kaplan-Meier and Cox regression analyses. Low levels of CRT and an overexpression of Ki67 were significantly associated with the stage, histology, and differentiation of the primary surgery without doxorubicin (DOX) neoadjuvant chemotherapy (NAC) patient group and were significantly correlated with a short progression-free survival and the overall survival. A multivariate analysis revealed that CRT and Ki67 expression were independent prognostic indicators for endometrioid endometrial cancer. Low CRT expression and an overexpression of Ki67 were significantly associated with DOX-NAC and the histology (P<0.05) pre-NAC and post-NAC in the DOX-NAC patient group. Upon treatment of DOX-NAC, CRT, PERK and p-eIF2 alpha protein content were overexpressed in DOX-sensitive endometrial cancer (P<0.05), whereas there was no significant difference in the DOX-resistant group. Low CRT expression in endometrial cancer is significantly associated with aggressive progression and poor prognosis. CRT may therefore serve as a molecular marker for predicting the progression and prognosis in DOX-resistant endometrial cancer patients.