YKL-39 is an independent prognostic factor in gastric adenocarcinoma and is associated with tumor-associated macrophage infiltration and angiogenesis

Background Gastric cancer has a high incidence and mortality rate. Angiogenesis is necessary for tumor infiltration and metastasis and affects patient prognosis. YKL-39 has monocyte chemotactic activity and pro-angiogenic activity in some tumors. In this study, we investigated the relationship between YKL-39 and tumor-associated macrophages and microangiogenesis in gastric cancer to determine its potential as a prognostic biomarker. Materials and methods A total of 119 patients with gastric cancer who had undergone gastrectomy at the 940th Hospital of the Joint Security Force between 2014 and 2018 were included in this study. We assayed the protein expression of YKL-39, CD68, and CD34 by immunohistochemistry in tissues of 119 patients with gastric cancer, as well as the intracellular expression of YKL-39 and CD68 by immunofluorescence. Data were analyzed with SPSS Statistics 25.0 to explore the impact of expression of YKL-39, CD68, and CD34 in gastric cancer patients and the relationship among them. Results Our results show that YKL-39 was expressed in both the nucleus and cytoplasm of gastric cancer cells and tumor mesenchyme. YKL-39 protein expression was associated with the depth of tumor infiltration, lymph node metastasis, and TNM stage; CD68 protein expression was associated with lymph node metastasis and TNM stage; CD34 protein expression was not associated with clinicopathological characteristics. Expression of YKL-39 was positively correlated with CD68 and CD34 ( p < 0.001), and high expression of YKL-39 was associated with poor prognosis ( p < 0.05). Conclusion In gastric cancer, YKL-39 expression is positively correlated with the degree of tumor-associated macrophage infiltration and angiogenesis, and is a potential prognostic marker for gastric cancer.