Expression Levels of Cyclin G2, But Not Cyclin E, Correlate With Gastric Cancer Progression¹

Purpose: Cyclin G2 and cyclin E are important cell-cycle regulators in various cancer tissues. However, little is known about cyclin G2 expression in human gastric cancer tissues, and the role of cyclin E is quite controversial. This study evaluated their clinical significance in gastric cancer tissues. Materials and methods: Immunohistochemical staining using the tissue array method was performed on 166 human gastric carcinomas. The clinicopathological features and prognostic significance were analyzed. Results: Cyclin G2 and cyclin E expressions were positive in 110 (66.3%) and 77 (46.4%) human gastric cancer tissues, respectively. The incidence of cyclin G2 positivity was lower in females and in cancers with the undifferentiated type of histology. Moreover, cyclin G2 expression was inversely correlated with the more advanced stages (P < 0.05), the presence of lymph-node metastasis (P < 0.05), and the presence of perineural invasion (P < 0.05). However, no significant correlation was observed between the expression of cyclin E and all of the clinicopathological factors examined. Cyclin G2 expression was associated with a better overall survival (OS; 5-y OS, 50.6% for cyclin G2-positive versus 35.0% for cyclin G2-negative; P < 0.05). However, multivariate analysis revealed lymph-node metastasis, distant metastasis, and lymphatic invasion to be independent prognostic factors but not cyclin G2 expression. Conclusion: Our study could not demonstrate any significant relationship between cyclin E expression and the clinicopathological variables. However, cyclin G2 appears to be a negative cell-cycle regulator in gastric cancer, and its expression seems to be inversely related to gastric cancer progression.