When good transforming growth factor-β turns bad in hepatocellular carcinoma: Axl takes the stage

A novel epithelial-mesenchymal transition gene signature for the immune status and prognosis of hepatocellular carcinoma

Background

This study clarified whether EMT-related genes can predict immunotherapy efficacy and overall survival in patients with HCC.

Methods

The RNA-sequencing profiles and patient information of 370 samples were derived from the Cancer Genome Atlas (TCGA) dataset, and EMT-related genes were obtained from the Molecular Signatures database. The signature model was constructed using the least absolute shrinkage and selection operator Cox regression analysis in TCGA cohort. Validation data were obtained from the International Cancer Genome Consortium (ICGC) dataset of patients with HCC. Kaplan–Meier analysis and multivariate Cox analyses were employed to estimate the prognostic value. Immune status and tumor microenvironment were estimated using a single-sample gene set enrichment analysis (ssGSEA). The expression of prognostic genes was verified using qRT-PCR analysis of HCC cell lines.

Results

A signature model was constructed using EMT-related genes to determine HCC prognosis, based on which patients were divided into high-risk and low-risk groups. The risk score, as an independent factor, was related to tumor stage, grade, and immune cells infiltration. The results indicated that the most prognostic genes were highly expressed in the HCC cell lines, but GADD45B was down-regulated. Enrichment analysis suggested that immunoglobulin receptor binding and material metabolism were essential in the prognostic signature.

Conclusion

Our novel prognostic signature model has a vital impact on immune status and prognosis, significantly helping the decision-making related to the diagnosis and treatment of patients with HCC.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12072-022-10354-3.

Role of the receptor tyrosine kinase Axl in hepatocellular carcinoma and its clinical relevance

The receptor tyrosine kinase Axl and its ligand Gas6 regulate fundamental biological processes, including cell proliferation, survival and motility, through multiple downstream signaling pathways. Evidence to date suggests that aberrant Axl expression frequently occurs in many malignancies, including hepatocellular carcinoma, and that this is critical for promoting cell proliferation, migration, angiogenesis and metastasis. Moreover, deregulated Axl expression or activation is reportedly associated with resistance to cancer drugs and targeted cancer therapies. Thus, Axl inhibitors may represent a novel therapeutic approach for cancer treatment. This Review summarizes the latest advances concerning the biological role of Axl in hepatocellular carcinoma and its potential clinical relevance.

Role of epithelial to mesenchymal transition in hepatocellular carcinoma

The epithelial to mesenchymal transition (EMT) is a multistep biological process whereby epithelial cells change in plasticity by transient de-differentiation into a mesenchymal phenotype. EMT and its reversal, mesenchymal to epithelial transition (MET), essentially occur during embryogenetic morphogenesis and have been increasingly described in fibrosis and cancer during the last decade. In carcinoma progression, EMT plays a crucial role in early steps of metastasis when cells lose cell-cell contacts due to ablation of E-cadherin and acquire increased motility to spread into surrounding or distant tissues. Epithelial plasticity has become a hot issue in hepatocellular carcinoma (HCC), as strong inducers of EMT such as transforming growth factor-β are able to orchestrate both fibrogenesis and carcinogenesis, showing rising cytokine levels in cirrhosis and late stage HCC. In this review, we consider the significance of EMT-MET in malignant hepatocytes as well as changes in the plasticity of hepatic stellate cells for cellular heterogeneity of HCC, and further aim at explaining the current limiting insights into EMT by snapshot analyses of HCC tissues. Recent advances in the identification of clinically relevant mechanisms that impinge on important EMT-transcription factors, as well as on miRNAs causing EMT signatures and HCC progression are highlighted. In addition, we draw particular attention to framing EMT in the context of potential clinical relevance for HCC patients. We conclude that some aspects of EMT are still elusive and further studies are required to better link the clinical management of HCC with biomarkers and targeted therapies related to EMT.

The rationale for targeting TGF-β in chronic liver diseases

BACKGROUND

Transforming growth factor (TGF)-β is a pluripotent cytokine that displays several tissue-specific biological activities. In the liver, TGF-β is considered a fundamental molecule, controlling organ size and growth by limiting hepatocyte proliferation. It is involved in fibrogenesis and, therefore, in worsening liver damage, as well as in triggering the development of hepatocellular carcinoma (HCC). TGF-β is known to act as an oncosuppressor and also as a tumour promoter in HCC, but its role is still unclear.

DESIGN

In this review, we discuss the potential role of TGF-β in regulating the tumoural progression of HCC, and therefore the rationale for targeting this molecule in patients with HCC.

RESULTS

A considerable amount of experimental preclinical evidence suggests that TGF-β is a promising druggable target in patients with HCC. To support this hypothesis, a phase II clinical trial is currently ongoing using a TGF-β pathway inhibitor, and results will soon be available.

CONCLUSIONS

The identification of new TGF-β related biomarkers will help to select those patients most likely to benefit from therapy aimed at inhibiting the TGF-β pathway. New formulations that may provide a more controlled and sustained delivery of the drug will improve the therapeutic success of such treatments.

Facing the enigma of the vascular network in hepatocellular carcinomas in cirrhotic and non-cirrhotic livers

AIMS

In this paper we aimed to analyse the typology and the phenotype of the different vascular modifications in human hepatocellular carcinomas (HCCs) with a new immunomorphological and gene expression approach. We also attempted to correlate these modifications with the histological parameters of tumour aggressiveness and the surrounding liver parenchyma.

METHODS

Ninety-six HCCs (from 80 patients) were retrospectively enrolled, 46 occurring in non-cirrhotic livers, and 50 in livers transplanted for cirrhosis. Histopathological analysis, immunohistochemistry for CD34, Nestin and WT1 and RT-PCR for Nestin, transforming growth factor-β1 (TGFβ1) and insulin-like growth factor 1 (IGF1R) mRNA were performed in all nodules.

RESULTS

By correlating the CD34 and Nestin immunoreactivity in HCC vasculature with the tumorous architecture, we identified four vascular patterns (named from 'a' to 'd'). Each of them was characterised by different expressions of TGFβ1 and IGF1R mRNA. Pattern a showed CD34-positive/Nestin-negative sinusoids, and was prevalent in microtrabecular lesions. Pattern b showed similar morphology and architecture as pattern a, but with Nestin-positive sinusoids and a significant 'boost' in IGF1R and TGFβ1 mRNAs. In patterns c and d a progressive sinusoid loss and a gain of newly formed arterioles were seen. Notably, HCCs with pattern a arose more frequently in cirrhosis (p=0.024), and showed lower incidence of microvascular invasion (p=0.002) and infiltration (p=0.005) compared with HCCs with other patterns.

CONCLUSIONS

Although future studies are surely required, the identification of different vascular profiles in HCCs from cirrhotic and non-cirrhotic livers may help clarify the relationship between HCC progression and aggressiveness.