Risk factors of primary liver cancer initiation associated with tumour initiating cell emergence: novel targets for promising preventive therapies

Reviewing the function of macrophages in liver disease

INTRODUCTION

The liver is a central metabolic organ, but is also hosting a unique immune microenvironment to sustain homeostasis and proper defense measures against injury threats in healthy individuals. Liver macrophages, mostly represented by the tissue-resident Kupffer cells and bone marrow- or monocyte-derived macrophages, are intricately involved in various aspects of liver homeostasis and disease, including tissue injury, inflammation, fibrogenesis and repair mechanisms.

AREAS COVERED

We review recent findings on defining the liver macrophage landscape and their functions in liver diseases with the aim of highlighting potential targets for therapeutic interventions. A comprehensive literature search in PubMed and Google Scholar was conducted to identify relevant literature up to date.

EXPERT OPINION

Liver macrophages orchestrate key homeostatic and pathogenic processes in the liver. Thus, targeting liver macrophages represents an attractive strategy for drug development, e.g. to ameliorate liver inflammation, steatohepatitis or fibrosis. However, translation from fundamental research to therapies remains challenging due to the versatile nature of the liver macrophage compartment. Recent and major technical advances such as single-cell and spatially-resolved omics approaches deepened our understanding of macrophage biology at a molecular level. Yet, further studies are needed to identify suitable, etiology- and stage-dependent strategies for the treatment of liver diseases.

RBM39 Promotes Base Excision Repair to Facilitate the Progression of HCC by Stabilising OGG1 mRNA

Targeting base excision repair (BER) has been an attractive strategy in cancer therapeutics. RNA-binding motif protein 39 (RBM39) modulates the alternative splicing of numerous genes involved in cancer occurrence and progression. However, whether and how RBM39 regulates BER in hepatocellular carcinoma (HCC) remain unclear. Here, we found that under oxidative stress, RBM39 degradation or knockdown decreased BER efficiency in HCC cells using a well-designed BER reporter. Further assays showed that RBM39 promoted HCC cell proliferation, migration, and invasion, enhancing cell survival and inhibiting apoptosis. Mechanistically, RBM39 interacted with the mRNA of the essential glycosidase 8-oxoguanine-DNA glycosylase 1 (OGG1), thereby stabilising OGG1 mRNA. This in turn increases OGG1 expression and promotes BER efficiency in HCC. Moreover, data suggested that RBM39 degradation, combined with oxidative damage, could be more effective for HCC treatment than monotherapy, both in vitro and in xenograft mice models. Overall, we demonstrated that RBM39 regulated OGG1 stabilisation and improved BER efficiency, suggesting that combining the RBM39 degradant indisulam with the oxidising agent KBrO3 could be an emerging strategy for HCC treatment.

The Patatin-Like Phospholipase Domain-Containing 3 148M Variant Exacerbates Alcohol-Induced Liver Injury and Tumorigenesis in Mice

Patatin-like phospholipase domain-containing 3 (PNPLA3) protein 148M variant is strongly associated with cirrhosis and hepatocellular carcinoma (HCC); however, the underlying mechanisms remain elusive. This study aimed to elucidate the role of the PNPLA3148M variant in alcohol-related HCC development. Control and humanized PNPLA3148M transgenic mice were fed with an ethanol-containing diet for 12 weeks. The animals were examined for liver tumors. After the alcohol feeding, the PNPLA3148M mice had twofold higher liver cancer incidence rates and larger tumor sizes than those in the control mice. Cancer stem cell markers in the PNPLA3148M mouse livers were elevated relative to those in the control mouse livers. Alcohol detoxification was impaired in the PNPLA3148M mouse livers. Hepatic oxidative stress and DNA damage were elevated in the PNPLA3148M mice. Wnt/β-catenin and Yes-associated protein (YAP) and WW domain-containing transcription regulator 1 (TAZ) were activated in the PNPLA3148M mouse livers. The data suggest that the PNPLA3148M variant has a strong interaction with alcohol in HCC development through attenuation of alcohol detoxification and promotion of oncogenic pathways. Targeting the PNPLA3148M variant might be useful for the prevention or treatment of alcohol-associated HCC in patients carrying this variant.

Identification and validation of an immune-related miRNA signature for predicting prognosis of hepatocellular carcinoma

MicroRNAs play a significant role in the initiation and progression of hepatocellular carcinoma (HCC); however, their roles in immune regulation of HCC remain unclear. Our study aimed to identify an immune-related miRNA signature and explore its impact on the prognosis and tumor immune microenvironment HCC. Initially, we identified 48 differentially expressed immune-related miRNAs. Using the LASSO regression dimensionality reduction method, we constructed an immune-related miRNA signature from 12 of these miRNAs. This signature has emerged as an independent prognostic marker and is associated with the clinical stage of HCC. To elucidate the roles of the twelve-microRNA signature, we predicted their target genes. Enrichment analysis indicated that these target genes were involved in immune cell infiltration. Notably, the target genes regulated by hsa-miR-139-5p, hsa-miR-551a, and hsa-miR-7-5p showed a partial overlap. We further confirmed the differential expression of miR-7, miR-551a, miR-139-5p, and some of their overlapping target genes in tumor and non-tumor tissues derived from patients with HCC using RT-qPCR. Overall, we identified an immune-related miRNA signature that is strongly correlated with the prognosis and immune microenvironment of HCC; and confirmed the differential expression of the three most important microRNAs and their overlapping target genes in tumor and non-tumor tissues derived from HCC patients.

Alcohol-associated liver cancer

Heavy alcohol intake induces a wide spectrum of liver diseases ranging from steatosis, steatohepatitis, cirrhosis, and HCC. Although alcohol consumption is a well-known risk factor for the development, morbidity, and mortality of HCC globally, alcohol-associated hepatocellular carcinoma (A-HCC) is poorly characterized compared to viral hepatitis-associated HCC. Most A-HCCs develop after alcohol-associated cirrhosis (AC), but the direct carcinogenesis from ethanol and its metabolites to A-HCC remains obscure. The differences between A-HCC and HCCs caused by other etiologies have not been well investigated in terms of clinical prognosis, genetic or epigenetic landscape, molecular mechanisms, and heterogeneity. Moreover, there is a huge gap between basic research and clinical practice due to the lack of preclinical models of A-HCC. In the current review, we discuss the pathogenesis, heterogeneity, preclinical approaches, epigenetic, and genetic profiles of A-HCC, and discuss the current insights into and the prospects for future research on A-HCC. The potential effect of alcohol on cholangiocarcinoma and liver metastasis is also discussed.

CDK4/6 inhibition enhances T-cell immunotherapy on hepatocellular carcinoma cells by rejuvenating immunogenicity

Hepatocellular carcinoma (HCC) poses a significant clinical challenge, necessitating the integration of immunotherapeutic approaches. Palbociclib, a selective CDK4/6 inhibitor, has demonstrated promising efficacy in preclinical HCC models and is being evaluated as a novel therapeutic option in clinical trials. Additionally, CDK4/6 inhibition induces cellular senescence, potentially influencing the tumor microenvironment and immunogenicity of cancer cells. In this study, we conducted comprehensive bioinformatic analyses using diverse HCC transcriptome datasets, including bulk and single-cell RNA-sequencing data from public databases. We also utilized human and mouse HCC cells to investigate functional aspects. Primary T cells isolated from mouse blood were employed to assess T cell immunity against HCC cells. Results revealed that CD8+ T-cell infiltration correlates with improved outcomes in HCC patients with suppressed CDK4/6 expression. Moreover, CDK4/6 expression was associated with alterations in the immune landscape and immune checkpoint expression within the liver tumor microenvironment. Furthermore, we found that treatment with Palbociclib and Doxorubicin induces cellular senescence and a senescence-associated secretory phenotype in HCC cells. Notably, pretreatment with Palbociclib augmented T cell-mediated cytotoxicity against HCC cells, despite upregulation of PD-L1, surpassing the effects of Doxorubicin pretreatment. In conclusion, our study elucidates a novel mechanism by which CDK4/6 inhibition enhances T-cell-associated cancer elimination and proposes a potential therapeutic strategy to enhance T-cell immunotherapy on HCC.

Proteome-wide Mendelian randomization highlights AIF1 and HLA-DQA2 as targets for primary sclerosing cholangitis

BACKGROUND

Primary sclerosing cholangitis (PSC) is a kind of cholestatic liver disease without effective therapies and its pathogenesis is largely unknown.

METHODS

We performed the proteome-wide Mendelian randomization (MR) design to estimate the causal associations of protein levels with PSC risk. Therein, genetic associations with 4,907 plasma protein levels were extracted from a proteome-wide genome-wide association study (GWAS) with 35,559 individuals and those with PSC were obtained from the International PSC Study Group (2,871 cases and 12,019 controls) and the FinnGen study (1,491 cases and 301,383 controls). The colocalization analysis was performed to detect causal variants shared by proteins and PSC. The identified proteins were further enriched in pathways and diseases. A phenome-wide association screening was performed and potential drugs were assessed as well.

RESULTS

The results indicated that genetically predicted plasma levels of 14 proteins were positively associated with an increased risk of PSC and 8 proteins were inversely associated with PSC risk in both PSC GWAS data sets, and they all survived in sensitivity analyses. The colocalization indicated that AIF1 (allograft inflammatory factor 1) and HLA-DQA2 (major histocompatibility complex, class II, DQ alpha 2) were shared proteins with PSC, and they should be direct targets for PSC. The phenome-wide screening suggested that variants located at AIF1 or HLA-DQA2 region were closely associated with several autoimmune diseases, such as rheumatoid arthritis, implicating the shared pathogenesis among them.

CONCLUSIONS

Our study highly pinpointed two candidate targets (AIF1 and HLA-DQA2) for PSC.