Role of podocalyxin in astrocytoma: Clinicopathological and in vitro evidence

Abstract

The present study examined the expression of podocalyxin (PODX) in surgically-resected astrocytomas, associated the levels of PODX expression with the clinicopathological characteristics and survival outcomes of astrocytoma and assessed how PODX affected the viability of astrocytoma cells following the administration of chemotherapeutic agents. The immunohistochemical analysis of 102 patient samples revealed that a high expression of PODX was significantly associated with high-grade astrocytomas (P<0.001) and a high Ki-67 labeling index (LI; P<0.001). A Kaplan-Meier survival analysis demonstrated that the high PODX expression group had significantly shorter disease-free survival (DFS) and overall survival (OS) rates compared with the low expression group (P<0.001). The multivariate analysis using the Cox's proportional hazards model revealed that a high expression of PODX, a high World Health Organization grade and a high Ki-67 LI were independent factors for shorter DFS and OS times. A subsequent in vitro study using SW1783 and U-87 human astrocytoma cell lines revealed that knocking down PODX decreased astrocytoma cell viability against temozolomide-induced apoptotic stress through the inhibition of the Akt survival signaling pathway. In conclusion, the in vivo findings indicated that a high expression of PODX is predictive of a poor survival outcome and, thus, may be used as a prognostic factor to predict the survival outcomes of astrocytoma patients. The in vitro findings indicated that PODX may promote astrocytoma cell viability against chemotherapeutic agent-induced apoptotic stress through the Akt pathway, indicating that PODX may be a novel target for overcoming chemoresistance in astrocytomas.