Longlong Cao1, Shoumin Zhu2, Heng Lu2, Mohammed Soutto2, Nadeem Bhat2, Zheng Chen2, Dunfa Peng2, Jianxian Lin3, Jun Lu3, Ping Li3, Chaohui Zheng3, Changming Huang4, Wael El-Rifai5. 1. Department of Gastric Surgery, Fujian Medical University Union Hospital, Fuzhou, China; Department of Surgery, University of Miami Miller School of Medicine, Miami, Florida. 2. Department of Surgery, University of Miami Miller School of Medicine, Miami, Florida. 3. Department of Gastric Surgery, Fujian Medical University Union Hospital, Fuzhou, China. 4. Department of Gastric Surgery, Fujian Medical University Union Hospital, Fuzhou, China. Electronic address: hcmlr2002@163.com. 5. Department of Surgery, University of Miami Miller School of Medicine, Miami, Florida; Department of Veterans Affairs, Miami Healthcare System, Miami, Florida; Sylvester Comprehensive Cancer Center, University of Miami Miller School of Medicine, Miami, Florida. Electronic address: welrifai@med.miami.edu.
Abstract
BACKGROUND & AIMS: Helicobacter pylori infection is the predominant risk factor for gastric cancer. RAS protein activator like 2 (RASAL2) is considered a double-edged sword in carcinogenesis. Herein, we investigated the role of RASAL2 in response to H pylori infection and gastric tumorigenesis. METHODS: Bioinformatics analyses of local and public databases were applied to analyze RASAL2 expression, signaling pathways, and clinical significance. In vitro cell culture, spheroids, patient-derived organoids, and in vivo mouse models were used. Molecular assays included chromatin immunoprecipitation, co-immunoprecipitation, Western blotting, quantitative polymerase chain reaction, and immunocyto/histochemistry. RESULTS: H pylori infection induced RASAL2 expression via a nuclear factor-κB (NF-κB)-dependent mechanism whereby NF-κB was directly bound to the RASAL2 promoter activating its transcription. By gene silencing and ectopic overexpression, we found that RASAL2 upregulated β-catenin transcriptional activity. RASAL2 inhibited protein phosphatase 2A activity through direct binding with subsequent activation of the AKT/β-catenin signaling axis. Functionally, RASAL2 silencing decreased nuclear β-catenin levels and impaired tumor spheroids and organoids formation. Furthermore, the depletion of RASAL2 impaired tumor growth in gastric tumor xenograft mouse models. Clinicopathological analysis indicated that abnormal overexpression of RASAL2 correlated with poor prognosis and chemoresistance in human gastric tumors. CONCLUSIONS: These studies uncovered a novel signaling axis of NF-κB/RASAL2/β-catenin, providing a novel link between infection, inflammation and gastric tumorigenesis.
BACKGROUND & AIMS: Helicobacter pylori infection is the predominant risk factor for gastric cancer. RAS protein activator like 2 (RASAL2) is considered a double-edged sword in carcinogenesis. Herein, we investigated the role of RASAL2 in response to H pylori infection and gastric tumorigenesis. METHODS: Bioinformatics analyses of local and public databases were applied to analyze RASAL2 expression, signaling pathways, and clinical significance. In vitro cell culture, spheroids, patient-derived organoids, and in vivo mouse models were used. Molecular assays included chromatin immunoprecipitation, co-immunoprecipitation, Western blotting, quantitative polymerase chain reaction, and immunocyto/histochemistry. RESULTS: H pylori infection induced RASAL2 expression via a nuclear factor-κB (NF-κB)-dependent mechanism whereby NF-κB was directly bound to the RASAL2 promoter activating its transcription. By gene silencing and ectopic overexpression, we found that RASAL2 upregulated β-catenin transcriptional activity. RASAL2 inhibited protein phosphatase 2A activity through direct binding with subsequent activation of the AKT/β-catenin signaling axis. Functionally, RASAL2 silencing decreased nuclear β-catenin levels and impaired tumor spheroids and organoids formation. Furthermore, the depletion of RASAL2 impaired tumor growth in gastric tumor xenograft mouse models. Clinicopathological analysis indicated that abnormal overexpression of RASAL2 correlated with poor prognosis and chemoresistance in human gastric tumors. CONCLUSIONS: These studies uncovered a novel signaling axis of NF-κB/RASAL2/β-catenin, providing a novel link between infection, inflammation and gastric tumorigenesis.
Authors: Sara Koenig McLaughlin; Sarah Naomi Olsen; Benjamin Dake; Thomas De Raedt; Elgene Lim; Roderick Terry Bronson; Rameen Beroukhim; Kornelia Polyak; Myles Brown; Charlotte Kuperwasser; Karen Cichowski Journal: Cancer Cell Date: 2013-09-09 Impact factor: 31.743
Authors: Sarah Naomi Olsen; Ania Wronski; Zafira Castaño; Benjamin Dake; Clare Malone; Thomas De Raedt; Miriam Enos; Yoko S DeRose; Wenhui Zhou; Stephanie Guerra; Massimo Loda; Alana Welm; Ann H Partridge; Sandra S McAllister; Charlotte Kuperwasser; Karen Cichowski Journal: Cancer Discov Date: 2016-12-14 Impact factor: 39.397