Abstract 4097: Significance of glypican-1 expression on tumor stromal cells in gastric carcinoma

Background: Glypican1 (GPC1) is a cell surface heparan sulfate proteoglycan that acts as a co-receptor for heparin-binding growth factors, and it plays a crucial role in cancer growth. Recently, it has been reported that GPC1 enriched on cancer-derived exosomes, and GPC1-positive exosomes in the circulation was frequently found in the patients with early pancreatic cancer. However role of GPC1-positive exosomes derived from tumor stromal cells remains to be unclear. The aim of this study is to clarify the significance of GPC1 expression on stromal cells in gastric carcinoma. Methods: A total of 597 patients with gastric cancer was enrolled in this study. An anti-GPC1 antibody was used for immunohistochemical staining. GPC1 expression was scored by the intensity of staining and the percentage of positive cells. GPC1 expression on cancer cells or stromal cells was evaluated. The corelation between GPC1 expression and clinicopathological features was statistically analyzed. Results: GPC1 expression on cancer cells was found in 473 (79%) of 597 cases. GPC1 expression on stromal cells was found in 147 (75%) of 597 cases. A Kaplan-Meier survival curve showed that overall survival of patients with GPC1-positive stromal cells was significantly better (log-rank p = 0.0028) than that with GPC1-negative stromal cells (5-year survival rate; 72.5% vs 57.9%, respectively). In contrast, overall survival was not statistically different (log rank p = 0.090) between patients with GPC1-positive tumor cells and GPC1-negative tumor cells (5-year survival rate; 71.8% vs. 64.6%, respectively). GPC1 expression on stromal cells was significantly correlated with T stage, lymph node metastasis, lymphatic vessel invasion, and clinical stage. Conclusions: GPC1 expression on stromal cells was associated with the good prognosis of patients with gastric cancer. GPC1-positive exosomes in stromal cells might be correlated with the progression of gastric cancer. Citation Format: Yuichiro Miki, Masakazu Yashiro, Kishu Kitayama, Hiroaki Kasashima, Go Masuda, Naoshi Kubo, Katsunobu Sakurai, Takahiro Toyokawa, Hiroaki Tanaka, Kazuya Muguruma, Masaichi Ohira, Kosei Hirakawa. Significance of glypican-1 expression on tumor stromal cells in gastric carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4097.