Expression and prognostic value of the aldehyde dehydrogenase 1 (ALDH1) and N-myc downstream regulated gene 2 (NDRG2) as potential markers in human astrocytomas

In this study, immunohistochemical analysis was used to evaluate the expression of ALDH1 and NDRG2 in astrocytoma tissue samples and normal brain tissues. ALDH1 protein staining displayed that AlDH1 expression was not detectable in eight astrocytoma tissues (8/36) and in all of normal brain tissues. There was a significant difference between ALDH1 expression and WHO grades (P = 0.03). Furthermore, no correlation was determined between expression levels of ALDH1 and other clinicopathological characteristics including age, sex, and tumor size. Immunohistochemistry showed that a high level of NDRG2 protein expression was markedly detected in normal brain tissues and expression of NDRG2 protein was significantly decreased in astrocytoma tissues. There was a significant association between pathological grading and NDRG2 expression level (P < 0.001, Table 1), but no correlation was determined between expression levels of NDRG2 and other clinicopathological characteristics including age, sex, and tumor size. We also obtained detailed follow-up data and evaluated the association of ALDH1/NDRG2 expressions with overall survival. Kaplan-Meier survival and log-rank analysis indicated that the patients with high proportion of ALDH1-positive cells and low proportion of NDRG2-positive had shorter overall survival (P < 0.001; P = 0.001). Univariate analysis indicated that the high proportion of ALDH1-positive cells (P < 0.001), the low proportion of NDRG2-positive cells (P = 0.009), and the advanced grade (P < 0.005) were markedly linked to the prognosis in patients. Furthermore, in the multivariate analysis, ALDH1 cells' expression (P = 0.012), low proportion of NDRG2-positive cells (P = 0.025), and advanced grade (P < 0.03) were linked to poor overall survival. Our results suggest that NDRG2 expression is related to decreased survival rates and NDRG2 may be a potential marker in the astrocytoma prognosis. NDRG2 may be a potential marker in the astrocytoma prognosis. ALDH1 expression was related to advanced pathological grade and survival rate in astrocytoma patients.