Abstract:Objective To investigate the role and mechanism of FAT4, CUL4 and YAP in involvement of Hippo pathway in invasion of gastric cancer cells. Methods Immunohistochemistry was used to detect the expressions of FAT4, CUL4 and YAP in gastric cancer tissues and normal gastric tissues, and their relationships with clinicopathological characteristics of the patients with gastric cancer were analyzed. Western blot assay was used to detect the protein expressions of FAT4, CUL4 and YAP in the gastric cancer tissues and the normal gastric tissues. Results There was no significant difference in the positive expression rate of FAT4, CUL4 or YAP between the gastric cancer patients with different sexes and different pathological types (P > 0.05). There were statistically significant differences in the positive expression rates of FAT4, CUL4 and YAP between the gastric cancer patients with different degree of tumor differentiation and between the patients with and without lymph node metastasis (P < 0.05), the positive expression rates of FAT4, CUL4 and YAP were higher in the patients with higher degree of differentiation and without lymph node metastasis. The expressions of CUL4 and YAP in the gastric cancer tissues increased compared with the normal gastric tissues (P < 0.05), while the expression of FAT4 in the gastric cancer tissues was lower than that in the normal gastric tissues (P < 0.05). Conclusions FAT4 inhibits the invasion of gastric cancer cells through regulation of Hippo-YAP signaling pathway. CUL4 promotes gastric cancer cell invasion through regulating Hippo-YAP signaling pathway.