Evaluating the prognostic significance of FBXW7 expression level in human breast cancer by a meta-analysis of transcriptional profiles.

The tumor suppressor gene FBXW7 is mutated in numerous types of human cancers leading to loss of its function and/or expression. However the clinic significance of FBXW7 alterations remains largely unknown. Here, we carried out a meta-analysis of 10 gene expression microarray studies for a total 1900 patients of breast cancer with clinic information to evaluate the prognostic impact of FBXW7 mRNA expression. The FBXW7 mRNA levels significantly reduced in breast cancer compared to normal tissues. In addition, significant difference in the FBXW7 mRNA levels was found among molecular subtypes (normal-like, luminal A, luminal B, ERBB2 and basal). ERBB2 and basal tumors had significantly lower average FBXW7 mRNA level than normal-like tumors, whereas luminal A and B tumors have the lowest average FBXW7 mRNA level. The patients with higher FBXW7 mRNA level significantly increased disease-free survival, particularly in the group of patients with ER negative and basal subtype tumors. Moreover, higher FBXW7 mRNA level also significantly increased overall survival in the patients with ER negative tumors. But we strikingly found opposite effect of FBXW7 expression on overall survival in different subtypes. The patients with higher FBXW7 mRNA level significantly decreased overall survival in normal-like subtype while the patients with higher FBXW7 mRNA level significantly increased overall survival in ERBB2 and Basal subtype. Taken together, our results suggest that FBXW7 mRNA levels were a prognostic factor for disease-free and overall survival according to ER status and molecular subtypes.