Mechanism Of E-cadherin-mediated Ophiopogonin B’s Regulation Of Hippo Pathway In NSCLC

Background and Purpose:Driven by the growing wealth of knowledge on how tumor develops, selectively targeting the key molecular steps emerges as one of the leading anticancer therapies. Hippo signaling pathway, highly conserved, is found in recent years to coordinate cell proliferation, death and differentiation, regulate tissue growth. YAP and TAZ, are two major downstream effectors of the Hippo pathway. When dephosphorylated, YAP/TAZ translocate into the nucleus and interact with TEAD1-4 and other transcription factors to induce expression of genes that promote cell proliferation and inhibit apoptosis. Numerous studies have confirmed that, Hippo pathway plays an important role in the tumor process. "Ke Jinyan Prescription" which comes from State Medical Master Zhou Zhongying is verified to have significant inhibition effect on tumor growth in transplanted nude mice. After screening at the cellular level, we found that ophiopogonins were the main components inhibiting the NSCLC cell proliferation. And the further investigation revealed OP-B’s regulation on the crossing networks of Hippo pathway. In this study, we attempt to discover and clarify the regulation of OP-B on Hippo pathway and its role in the network system to provide a strong experimental basis for its clinical cancer therapy.Research contents:The major part of the research was launched on NSCLC, a leading systemic malignant disease in both incidence and mortality worldwide. The first chapter investigated OP-B’s regulation on Hippo pathway. In the second chapter, we analyzed the effect of OP-B on E-cadherin and related catenins and explored their function on the regulation of YAP by OP-B. Finally, in the third chapter, we verified the importance of the Hippo signaling pathway in the anti-tumor effect of OP-B.Key results:(1) OP-B induced an increase in the phosphorylation of S127 residue of YAP and decrease its nuclear accumulation in a dose-dependent manner. (2) OP-B’s effect of proliferation inhibition of cancer cell is E-cadherin-dependent. (3) OP-B can promote the formation of E-cadherin/β-catenin complex, which functioned as an upstream regulator of the Hippo signaling pathway and regulated the activity of YAP. (4) Depletion of E-cadherin-bound β-catenin induced a decrease in the phosphorylation of S127 residue of YAP and its nuclear accumulation, and blocked OP-B’s anti-tumor effect. (5) Hippo signaling pathway components were required for E-cadherin mediated OP-B-induced proliferation inhibition of cancer cell. Knockdown of the Hippo signaling components or overexpression of YAP inhibits the decrease in cell proliferation caused by OP-B.Conclusion and highlights:Our study demonstrated that OP-B regulated the Hippo signaling pathway through promoting the formation of E-cadherin/β-catenin complex, resulting as an increase in the phosphorylation of S127 residue of YAP and decrease of its nuclear accumulation, which then induced the effect of growth inhibition and proliferation inhibition.In our study, we linked E-cadherin to the Hippo signaling pathway to explore the regulation mechanism of OP-B, which adds an important new aspect of cadherin function and may help explain how its adhesive functions and other signaling interactions are integrated to regulate cell growth in various developmental processes or adult tissue homeostasis. It has a positive meaning for the search for new anti-tumor therapeutic target and the further study of the molecular mechanisms of OP-B’s anti-tumor effect.