Expression of the growth factor granulin in patients with brain tumors: Relevance to prognosis

Abstract

Granulin is a cysteine-rich polypeptide belonging to a family of growth factors that mediate cell cycle progression and motility. Granulin is expressed in several types of brain tumors. However, its clinical significance in terms of patient outcome has not been determined. This study was conducted to investigate the relationships between granulin expression, clinical characteristics, and prognosis in patients with brain tumors. Tumor tissues were obtained from 295 patients whose brain tumors were surgically resected, and the expression of granulin was assessed by reverse transcriptase polymerase chain reaction (RT-PCR). The tumors were classified pathologically according to World Health Organization (WHO) criteria into non-aggressive (WHO grades I and II) or aggressive (WHO grades III and IV and metastatic) tumors, and the prognostic implications of granulin expression were compared between the two groups. Among the 295 tumor specimens, 107 exhibited positive expression of granulin. For both groups, the mortality rate was significantly different between granulin-positive and -negative tumors (p<0.05). By Kaplan-Meier analysis, the survival rate of patients with granulin-positive tumors was lower than that of patients with negative tumors (p=0.028), and the rate of recurrence was higher in patients with positive tumors than in those with negative tumors (p=0.026). This study suggests that granulin is expressed in various brain tumors and that its expression is correlated with patient prognosis. Granulin may therefore be a novel target for the management of intracranial tumors.