Expression of serine and glycine-related enzymes in phyllodes tumor

Expression patterns of proteins involved in serine and glycine metabolism, and correlations of these patterns with clinicopathologic factors in phyllodes tumor were investigated. Tissue microarrays were prepared from 203 phyllodes tumors (PT) and stained with antibodies specific for glycine decarboxylase (GLDC), phosphoserine aminotransferase 1 (PSAT1), phosphoserine phosphatase (PSPH), phosphoglycerate dehydrogenase (PHGDH), and serine hydroxymethyltransferase 1 (SHMT1). These immunohistochemical results and clinicopathologic parameters were analyzed for correlation. Numbers of benign, borderline, and malignant tumors were 155, 32, and 16, respectively. Stromal expression of PHGDH, PSAT1, PSPH, SHMT1, and GLDC increased with increasing tumor grade, and epithelial expression of SHMT1 also increased with increasing tumor grade (p<0.001, and p=0.005, respectively). On univariate analysis, positive stainings for stromal PHGDH (p<0.001), stromal PSAT1 (p<0.001), stromal PSPH (p=0.003), epithelial SHMT1 (p=0.001), stromal SHMT1 (p=0.022), and stromal GLDC (p<0.001) were each associated with shorter disease-free survival. Stromal GLDC was associated with shorter overall survival (p<0.001). In conclusion, expression of proteins related to serine and glycine metabolism increased with increasing histologic grade in stromal components of phyllodes tumor.