Significance of PGP9.5 expression in cancer-associated fibroblasts for prognosis of colorectal carcinoma

To assess the expression of a cancer-associated fibroblasts (CAFs) marker as an indicator of prognosis, we raised anti-protein gene product 9.5 (PGP9.5) monoclonal antibody against cultured fibroblasts. PGP9.5 expression in cultured normal fibroblasts was increased by transforming growth factor β stimulation, indicating the phenotypic alteration to activated fibroblast. We immunohistochemically evaluated PGP9.5 expression with the CAFs of 110 colorectal cancer cases under T3 stage. PGP9.5 immunoreactivity in 30% or more of CAFs was defined as high PGP9.5 expression, and the other cases were considered as having low PGP9.5 expression. Patients with high PGP9.5 expression (42.7%) had significantly shorter survival and a higher incidence of recurrence than the low PGP9.5 expression group (P = .002 and P < .001, respectively). Multivariate analysis indicated PGP9.5 expression as an independent prognostic factor for overall and recurrence-free survival partly as well as lymph node metastasis. These results indicate that PGP9.5 expression in CAFs is a helpful finding to represent the overall biologic behavior of advanced colorectal cancer.