BackgroundIncreased liver stiffness exerts a detrimental role in driving hepatocellular carcinoma (HCC) malignancy and progression, and indicates a high risk of unfavorable outcomes. However, it remains largely unknown how liver matrix stiffness as an independent cue triggers epithelial-mesenchymal transition (EMT) and facilitates HCC metastasis.MethodsBuffalo rat HCC models with different liver stiffness backgrounds and an in vitro Col I-coated cell culture system with tunable stiffness were used in the study to explore the effects of matrix stiffness on EMT occurrence and its underlying molecular mechanism. Clinical significance of liver stiffness and key molecules required for stiffness-induced EMT were validated in HCC cohorts with different liver stiffness.ResultsHCC xenografts grown in higher stiffness liver exhibited worse malignant phenotypes and higher lung metastasis rate, suggesting that higher liver stiffness promotes HCC invasion and metastasis. Cell tests in vitro showed that higher matrix stiffness was able to strikingly strengthen malignant phenotypes and independently induce EMT occurrence in HCC cells, and three signaling pathways converging on Snail expression participated in stiffness-mediated effect on EMT including integrin-mediated S100A11 membrane translocation, eIF4E phosphorylation, and TGF β1 autocrine. Additionally, the key molecules required for stiffness-induced EMT were highly expressed in tumor tissues of HCC patients with higher liver stiffness and correlated with poor tumor differentiation and higher recurrence.ConclusionsHigher matrix stiffness as an initiator triggers epithelial-mesenchymal transition (EMT) in HCC cells independently, and three signaling pathways converging on Snail expression contribute to this pathological process. This work highlights a significant role of biomechanical signal in triggering EMT and facilitating HCC invasion and metastasis.

BackgroundHigher matrix stiffness affects biological behavior of tumor cells, regulates tumor-associated gene/miRNA expression and stemness characteristic, and contributes to tumor invasion and metastasis. However, the linkage between higher matrix stiffness and pre-metastatic niche in hepatocellular carcinoma (HCC) is still largely unknown.MethodsWe comparatively analyzed the expressions of LOX family members in HCC cells grown on different stiffness substrates, and speculated that the secreted LOXL2 may mediate the linkage between higher matrix stiffness and pre-metastatic niche. Subsequently, we investigated the underlying molecular mechanism by which matrix stiffness induced LOXL2 expression in HCC cells, and explored the effects of LOXL2 on pre-metastatic niche formation, such as BMCs recruitment, fibronectin production, MMPs and CXCL12 expression, cell adhesion, etc.ResultsHigher matrix stiffness significantly upregulated LOXL2 expression in HCC cells, and activated JNK/c-JUN signaling pathway. Knockdown of integrin β1 and α5 suppressed LOXL2 expression and reversed the activation of above signaling pathway. Additionally, JNK inhibitor attenuated the expressions of p-JNK, p-c-JUN, c-JUN and LOXL2, and shRNA-c-JUN also decreased LOXL2 expression. CM-LV-LOXL2-OE and rhLOXL2 upregulated MMP9 expression and fibronectin production obviously in lung fibroblasts. Moreover, activation of Akt pathway contributed to LOXL2-induced fibronectin upregulation. LOXL2 in CM as chemoattractant increased motility and invasion of BMCs, implicating a significant role of LOXL2 in BMCs recruitment. Except that, CM-LV-LOXL2-OE as chemoattractant also increased the number of migrated HCC cells, and improved chemokine CXCL12 expression in lung fibroblasts. The number of HCC cells adhered to surface of lung fibroblasts treated with CM-LV-LOXL2-OE was remarkably higher than that of the control cells. These results indicated that the secreted LOXL2 facilitated the motility of HCC cells and strengthened CTCs settlement on the remodeled matrix “soil”.ConclusionIntegrin β1/α5/JNK/c-JUN signaling pathway participates in higher matrix stiffness-induced LOXL2 upregulation in HCC cells. The secreted LOXL2 promotes fibronectin production, MMP9 and CXCL12 expression and BMDCs recruitment to assist pre-metastatic niche formation.Electronic supplementary materialThe online version of this article (10.1186/s13046-018-0761-z) contains supplementary material, which is available to authorized users.

Purpose: Cytokeratin 10 (CK10) was found to be expressed differently in human hepatocellular carcinoma (HCC) cell lines with different metastatic potentials in our previous research.The aim of this study was to assess the value of CK10 alone or in combination with cytokeratin 19 (CK19) in predicting tumor recurrence after curative resection in HCC patients. Experimental Design: CK10 expression in stepwise metastatic HCC cell lines and tumor tissues from 50 HCC patients was investigated using immunofluorescence assay, quantitative real-time reverse transcription-PCR, and Western blot analyses. Tumor tissue microarrays of 300 HCC patients who underwent curative resection between 1997 and 2000 were used to detect the expressions of CK10 and CK19. Clinicopathologic data for these patients were evaluated. The prognostic significance was assessed using Kaplan-Meier survival estimates and log-rank tests. Results: CK10 was overexpressed in the high metastatic HCC cell line and in tumor tissues of recurrent patients. Both univariate and multivariate analyses revealed that CK10 was a significant predictor for overall survival (OS) and disease-free survival, and that CK19 was a significant predictor for OS. CK10 expression was correlated with poor prognosis regardless of a-fetoprotein, tumor-node-metastasis stage, and vascular invasion. The 7-year OS and diseasefree survival rates in CK10 + and/or CK19 + patients were 30.0% and 37.6%, respectively, which were significantly lower than that of CK10 -/CK19 -patients (56.1% and 60.0%, respectively;Conclusion: CK10 is associated with HCC invasiveness. CK10 alone, or in combination with CK19, can be a novel predictor for poor prognosis of HCC patients after curative resection.Hepatocellular carcinoma (HCC) is one of the most prevalent tumor types; its incidence and mortality rates have increased in recent years (1).The high rate of recurrence or metastases after curative resection has hindered improvements in HCC survival (2, 3). Molecular signatures that define the risk of recurrence and metastatic potential of HCC have been difficult to identify. Such markers would allow appropriate therapeutic regimens to be applied earlier in the disease course. Although several prognostic biomarkers in HCC have been reported recently (4 -7), there still remains a lack of ideal biomarkers available that can be widely used in clinical settings (8, 9). Cytokeratins are typical epithelial cell markers expressed in a tissue-specific and differentiation-dependent manner. It has been reported that cytokeratins were extensively present in many malignant epithelial cells (10 -13) and tended to be altered in association with increases in metastatic ability and malignancy (14). Several cytokeratins were proven to be present in HCC (15,16) and relate with poor prognosis and metastatic potential (17 -22).In our previous research, cytokeratin 10 (CK10) expression was detected by in vitro phage display and proteomics technology in MHCC97-H but not in MHCC97-L, two human HCC cell lines created at ...