Expression of lipid metabolism-related proteins in breast phyllodes tumors

The aim of this study was to investigate the expression of lipid metabolism-related proteins and the implications thereof in phyllodes tumor (PT) of the breast. A tissue microarray (TMA) was constructed using paraffin blocks from 194 PT patient tissue samples. Immunohistochemical staining for lipid metabolism-related proteins, namely hormone-sensitive lipase (HSL), perilipin 2, fatty-acid-binding proteins 4 (FABP4), carnitine palmitoyltransferase-1 (CPT-1), acyl-CoA oxidase 1 (ACOX-1), and fatty acid synthase (FASN) was performed, and the immunohistochemical staining results were analyzed with respect to clinicopathologic parameters. The numbers of benign, borderline, and malignant PTs were 151, 27, and 16, respectively. The expression of HSL, perilipin 2, FABP4, CPT-1, and FASN in stromal components was higher in higher grade tumors. On univariate analysis, shorter disease-free survival (DFS) was associated with stromal perilipin 2 positivity (p<0.001) and stromal CPT-1 positivity (p=0.004). Shorter overall survival (OS) was associated with stromal perilipin 2 positivity (p<0.001), stromal FABP4 positivity (p<0.001), stromal CPT-1 positivity (p=0.004), and stromal FASN positivity (p<0.001). Multivariate Cox analysis revealed that stromal perilipin 2 positivity (hazard ratio=31.693, 95% CI: 1.341-748.8, p=0.032) was an independent factor for shorter DFS. In conclusion, higher expressions of HSL, perilipin 2, FABP4, CPT-1 and FASN in the stromal component were observed in higher grade PT.