Loss of 4.1N in epithelial ovarian cancer results in EMT and matrix-detached cell death resistance

Dandan Wang,Yan Liu,Ningning Du,Letian Zhang,Ajin Hu,Congrong Liu,Yuxiang Wang,Jing Yang,Congying Wu,Xiuli An

doi:10.1007/s13238-020-00723-9

Abstract

Epithelial ovarian cancer (EOC) is one of the leading causes of death from gynecologic cancers and peritoneal dissemination is the major cause of death in patients with EOC. Although the loss of 4.1N is associated with increased risk of malignancy, its association with EOC remains unclear. To explore the underlying mechanism of the loss of 4.1N in constitutive activation of epithelial-mesenchymal transition (EMT) and matrix-detached cell death resistance, we investigated samples from 268 formalin-fixed EOC tissues and performed various in vitro and in vivo assays. We report that the loss of 4.1N correlated with progress in clinical stage, as well as poor survival in EOC patients. The loss of 4.1N induces EMT in adherent EOC cells and its expression inhibits anoikis resistance and EMT by directly binding and accelerating the degradation of 14-3-3 in suspension EOC cells. Furthermore, the loss of 4.1N could increase the rate of entosis, which aggravates cell death resistance in suspension EOC cells. Moreover, xenograft tumors in nude mice also show that the loss of 4.1N can aggravate peritoneal dissemination of EOC cells. Single-agent and combination therapy with a ROCK inhibitor and a 14-3-3 antagonist can reduce tumor spread to varying degrees. Our results not only define the vital role of 4.1N loss in inducing EMT, anoikis resistance, and entosis-induced cell death resistance in EOC, but also suggest that individual or combined application of 4.1N, 14-3-3 antagonists, and entosis inhibitors may be a promising therapeutic approach for the treatment of EOC.

Highlights

Ovarian cancer is the leading cause of death from gynecologic cancers globally, with 13,980 deaths occurring accounting for about 5% of total cancer deaths in females (Siegel et al, 2019)
Complement and coagulation cascades, ECM-receptor interaction, and focal adhesion were identified as the top three terms identified by Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis; some extracellular-related pathways, including extracellular region, extracellular region part, extracellular matrix, proteinaceous extracellular matrix, and extracellular space (Fig. 1F and 1G), were likewise revealed by Gene Ontology (GO) pathway analysis
We investigated the effect of 4.1N loss on the epithelial-mesenchymal transition (EMT), which is a critical step for Epithelial ovarian cancer (EOC) cells to transition from a 3D environment into 2D metastasis. qRT-PCR analysis showed an approximately 1.2-fold increase in E-cadherin expression, 2.8-fold increase in zona occludens 1 (ZO-1) expression, 32.3-fold decrease in N-cadherin, 4.9-fold decrease in Fibronectin, 1.3-fold decrease in Snail, and 1.9-fold decrease in MMP2 in A2780 OE cells; while 4.1N depletion in SKOV3 cells revealed an approximately 9.6-fold increase in N-cadherin, 8.1-fold increase in Fibronectin, 4.3fold increase in Snail, 2.7-fold increase in MMP2, 32.3fold decrease in E-cadherin, and 10.1-fold decrease in ZO-1 expression (Fig. 2F)

Summary

Introduction

Ovarian cancer is the leading cause of death from gynecologic cancers globally, with 13,980 deaths occurring accounting for about 5% of total cancer deaths in females (Siegel et al, 2019). Our previous investigation confirmed that the decrease or loss of 4.1N expression was highly common in ovarian cancer cell lines and tissues; EOC patients with 4.1N down-regulation showed an increased risk of tumor malignancy, including ascites, intraperitoneal dissemination, poor histological differentiation, and short progression-free survival (PFS) (Xi et al, 2013). By changing the cellular localization of hypoxia‐induced factor 1α (HIF-1α), 4.1N can inhibit hypoxia-induced epithelial-mesenchymal transition (EMT) in EOCs (Zhang et al, 2016). These results implied that 4.1N plays a crucial role in inhibiting tumor occurrence and development in EOC; little is known about the precise molecular mechanisms underlying the role of 4.1N on EOC progression

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