Treatment development targeting Hippo pathway for scirrhous type gastric cancer.

Abstract

398 Background: Treatment outcome of gastric cancer (GC) has been improved by minimally invasive surgery, and development of new drugs including immune checkpoint inhibitors. However, survival for patients with scirrhous type (SGC, Type4) gastric cancer is dismal. Methods: We collected miRNAs form exosomes released from cancer associated fibroblasts which is developed from resected gastric cancer tissue. Pathway enrichment analysis (PEA) of top miRNAs showed that they are significantly associated with Hippo signaling pathway (Hippo pathway). The molecules relating Hippo pathway was evaluated by Western blotting in cell line, and IHC of tissue array. Results: PEA using top miRNAs showed the significant relationship to Hippo pathway. Yap is a final effector in this pathway, and we found that YAP is not expressed in MKN45 cells (diffuse type), which is supposed to be degraded in cytoplasm. On the contrary, MKN74 cells express both YAP and pYAP. IHC showed that YAP translocation to nucleus is significantly associated with CTGF expression. CTGF low expression is significantly associated with worse prognosis especially in diffuse type GC (Log rank p = 0.022). This trend is similar in the analysis of patients with SGC. Conclusions: The role of Hippo pathway is different between intestinal type and diffuse type of GC. YAP activator could be effective for the treatment of SGC, and we are focusing on the treatment development.