PT  - JOURNAL ARTICLE
AU  - Jaffer A Ajani
AU  - Yan Xu
AU  - Longfei Huo
AU  - Ruiping Wang
AU  - Yuan Li
AU  - Ying Wang
AU  - Melissa Pool Pizzi
AU  - Ailing Scott
AU  - Kazuto Harada
AU  - Lang Ma
AU  - Xiaodan Yao
AU  - Jiankang Jin
AU  - Wei Zhao
AU  - Xiaochuan Dong
AU  - Brian D Badgwell
AU  - Namita Shanbhag
AU  - Ghia Tatlonghari
AU  - Jeannelyn Santiano Estrella
AU  - Sinchita Roy-Chowdhuri
AU  - Makoto Kobayashi
AU  - Jody V Vykoukal
AU  - Samir M Hanash
AU  - George Adrian Calin
AU  - Guang Peng
AU  - Ju-Seog Lee
AU  - Randy L Johnson
AU  - Zhenning Wang
AU  - Linghua Wang
AU  - Shumei Song
TI  - YAP1 mediates gastric adenocarcinoma peritoneal metastases that are attenuated by YAP1 inhibition
AID  - 10.1136/gutjnl-2019-319748
DP  - 2020 Apr 26
TA  - Gut
PG  - gutjnl-2019-319748
4099  - http://gut.bmj.com/content/early/2020/04/27/gutjnl-2019-319748.short
4100  - http://gut.bmj.com/content/early/2020/04/27/gutjnl-2019-319748.full
AB  - Objective Peritoneal carcinomatosis (PC; malignant ascites or implants) occurs in approximately 45% of advanced gastric adenocarcinoma (GAC) patients and associated with a poor survival. The molecular events leading to PC are unknown. The yes-associated protein 1 (YAP1) oncogene has emerged in many tumour types, but its clinical significance in PC is unclear. Here, we investigated the role of YAP1 in PC and its potential as a therapeutic target.Methods Patient-derived PC cells, patient-derived xenograft (PDX) and patient-derived orthotopic (PDO) models were used to study the function of YAP1 in vitro and in vivo. Immunofluorescence and immunohistochemical staining, RNA sequencing (RNA-Seq) and single-cell RNA-Seq (sc-RNA-Seq) were used to elucidate the expression of YAP1 and PC cell heterogeneity. LentiCRISPR/Cas9 knockout of YAP1 and a YAP1 inhibitor were used to dissect its role in PC metastases.Results YAP1 was highly upregulated in PC tumour cells, conferred cancer stem cell (CSC) properties and appeared to be a metastatic driver. Dual staining of YAP1/EpCAM and sc-RNA-Seq revealed that PC tumour cells were highly heterogeneous, YAP1high PC cells had CSC-like properties and easily formed PDX/PDO tumours but also formed PC in mice, while genetic knockout YAP1 significantly slowed tumour growth and eliminated PC in PDO model. Additionally, pharmacologic inhibition of YAP1 specifically reduced CSC-like properties and suppressed tumour growth in YAP1high PC cells especially in combination with cytotoxics in vivo PDX model.Conclusions YAP1 is essential for PC that is attenuated by YAP1 inhibition. Our data provide a strong rationale to target YAP1 in clinic for GAC patients with PC.