LTβR signalling preferentially accelerates oncogenic AKT-initiated liver tumours

Objectives The relative contributions of inflammatory signalling and sequential oncogenic dysregulation driving liver cancer pathogenesis remain incompletely understood. Lymphotoxin-beta receptor (LT beta R) signalling is critically involved in hepatitis and liver tumorigenesis. Therefore, we explored the interdependence of inflammatory lymphotoxin signalling and specific oncogenic pathways in the progression of hepatic cancer. Design Pathologically distinct liver tumours were initiated by hydrodynamic transfection of oncogenic V-Akt Murine Thymoma Viral Oncogene Homolog 1 (AKT)/beta-catenin or AKT/Notch expressing plasmids. To investigate the relationship of LT beta R signalling and specific oncogenic pathways, LT beta R antagonist (LT beta R-Fc) or agonist (anti-LT beta R) were administered post oncogene transfection. Initiated livers/tumours were investigated for changes in oncogene expression, tumour proliferation, progression, latency and pathology. Moreover, specific LT beta R-mediated molecular events were investigated in human liver cancer cell lines and through transcriptional analyses of samples from patients with intrahepatic cholangiocarcinoma (ICC). Results AKT/beta-catenin-transfected livers displayed increased expression of LT beta and LT beta R, with antagonism of LT beta R signalling reducing tumour progression and enhancing survival. Conversely, enforced LT beta R-activation of AKT/beta-catenin-initiated tumours induced robust increases in proliferation and progression of hepatic tumour phenotypes in an AKT-dependent manner. LT beta R-activation also rapidly accelerated ICC progression initiated by AKT/Notch, but not Notch alone. Moreover, LT beta R-accelerated development coincides with increases of Notch, Hes1, c-MYC, pAKT and beta-catenin. We further demonstrate LT beta R signalling in human liver cancer cell lines to be a regulator of Notch, pAKTser473 and beta-catenin. Transcriptome analysis of samples from patients with ICC links increased LT beta R network expression with poor patient survival, increased Notch1 expression and Notch and AKT/PI3K signalling. Conclusions Our findings link LT beta R and oncogenic AKT signalling in the development of ICC.