Interconnections between autophagy and the coagulation cascade in hepatocellular carcinoma

Abstract

Autophagy has an important role in tumor biology of hepatocellular carcinoma (HCC). Recent studies demonstrated that tissue factor (TF) combined with coagulation factor VII (FVII) has a pathological role by activating a G-protein-coupled receptor called protease-activated receptor 2 (PAR2) for tumor growth. The present study aimed to investigate the interactions of autophagy and the coagulation cascade in HCC. Seventy HCC patients who underwent curative liver resection were recruited. Immunohistochemical staining and western blotting were performed to determine TF, FVII, PAR2 and light chain 3 (LC3A/B) expressions in tumors and their contiguous normal regions. We found that the levels of autophagic marker LC3A/B-II and coagulation proteins (TF, FVII and PAR2) were inversely correlated in human HCC tissues. Treatments with TF, FVII or PAR2 agonist downregulated LC3A/B-II with an increased level of mTOR in Hep3B cells; in contrast, knockdown of TF, FVII or PAR2 increased LC3A/B. Furthermore, mTOR silencing restored the impaired expression of LC3A/B-II in TF-, FVII- or PAR2-treated Hep3B cells and activated autophagy. Last, as an in vivo correlate, we administered TF, FVII or PAR2 agonist in a NOD/severe combined immunodeficiency xenograft model and showed decreased LC3A/B protein levels in HepG2 tumors with treatments. Overall, our present study demonstrated that TF, FVII and PAR2 regulated autophagy mainly via mTOR signaling. The interaction of coagulation and autophagic pathways may provide potential targets for further therapeutic application in HCC.

Tissue factor at the crossroad of coagulation and cell signaling

“…Spontaneous breast cancer development is delayed in both strains and to a similar extent in double‐deficient mice, indicating that PAR2 and downstream TF cytoplasmic domain phosphorylation cooperate in cancer progression, consistent with human pathology data in breast cancer . TF‐FVIIa‐PAR2 signaling has also been linked to human hepatocellular carcinoma (HCC) progression independent of downstream coagulation . In addition, TF ΔCT and PAR2‐deficient mice were similarly protected from carbon tetrachloride (CCl 4 ) damage leading to hepatic fibrosis involving transforming growth factor (TGF) β and macrophage activation.…”

Targeting clotting proteins in cancer therapy – progress and challenges

“…While IGFR cross-activation protects tumor cells from apoptosis through activation of the PI-3 kinase pathway, this pathway may participate in PI-3 kinase-Akt signaling dependent weight gain regulation by TF-FVIIa signaling (64). Cancer cell signaling of the TF-FVIIa-FXa coagulation initiation complex induces PI-3 kinase-mTOR signaling (65), which may be related to the finding that autophagy is suppressed by TF-PAR2 signaling in hepatocellular carcinoma (66). In addition to growth factor transactivation, TF-FVIIa influences tyrosine receptor signaling by direct proteolysis of the ephrin tyrosine kinase receptors B2 and A2 (67).…”

Autophagy and Coagulation in Liver Cancer and Disorders

“…Studies that target the TF/FVIIa signaling pathway with specific inhibitor or RNA interference provide a logical path for the development of potential therapeutics [44,45]. In our clinical observations in HCC, we were the first to demonstrate that the expressions of FVII and PAR2 were inversely correlated with the amount of autophagic effector proteins LC3A/B-II [46]. We have also demonstrated that the treatment with recombinant TF (rTF), rFVII, or PAR2 agonist decreased expression of LC3A/B-II protein in cultured Hep3B cells suggesting a crucial impact of the TF/FVII/PAR2 coagulation pathway on tumor malignancy under certain circumstances.…”