NOD2 Inhibits Tumorigenesis and Increases Chemosensitivity of Hepatocellular Carcinoma by Targeting LKB1/AMPK/mTORC1 Axis

Abstract

Background: NOD2 is a recognized innate immune sensor which can initiate potent immune response against pathogens. However its role in cancer remains to be clarified. Methods: DEN/CCL4 induced HCC mice model and xenograft tumor model were constructed to define the function of NOD2 in HCC progression. CCK-8, transwell and colony formation assay were performed to detect the malignant behaviors of HCC cells. Immunohistochemical staining, western blot and qRT-PCR were performed to detect the relative expression of NOD2 in clinical HCC specimen. Signaling transduction of HCC cells was defined by western blot. Co-Immunoprecipitation and immunofluorescence were performed to verify the binding between NOD2 and AMPK-LKB1 complex. Findings: NOD2 deficiency promoted hepatocarcinogenesis both in vivo and in vitro. Absent expression of NOD2 in clinical HCC tissues was significantly correlated with advanced disease stages. Further investigation showed that NOD2 inhibited malignant behaviors and enhanced chemosensitivity of HCC cells through activating LKB1/AMPK/mTORC1 signaling pathway by directly binding with AMPK-LKB1 complex. Interpretation: This study showed that NOD2 acted as a tumor suppressor as well as a chemotherapeutic regulator in HCC cells, which indicated a potential therapeutic strategy for HCC treatment by regulating NOD2/LKB1/AMPK/mTORC1 signaling axis. Funding: This study was supported by the National Natural Science Foundation of China (No.81672391 and No.81472269) and the Major Innovation Project of Shandong Province (No.2018CXGC1217). Declaration of Interest: The authors declare no conflict of interests. Ethical Approval: All of the protocols carried out to mice were followed the guidelines of the Institutional Animal Care and Use Committee, and approved by the Medical Ethics Committee of Shandong University. Written informed consents were obtained from all patients before participation. All protocols were in accordance with the Helsinki Declaration and were approved by Shandong University Research Ethics Committee.