RMP promotes venous metastases of hepatocellular carcinoma through promoting IL-6 transcription

Exploring the oncogenic and tumor-suppressive roles of Circ-ADAM9 in cancer

Circular RNAs (circRNAs) constitute a recently identified category of closed continuous loop RNA transcripts, serving as a subset of competing endogenous RNAs (ceRNAs) with the capacity to modulate genes by acting as microRNA sponges. In the context of cancer growth, numerous investigations have explored the potential functions of circRNAs, revealing their diverse functions either as oncogenes, promoting cancer progression, or as tumor suppressors, mitigating disease development. Among these, circRNA ADAM9 (Circ-ADAM9) is now recognized as an important player in a variety of mechanisms, both physiological and pathological, especially in cancer. The aberrant expression of Circ-ADAM9 has been observed across multiple human malignancies, implying a significant involvement in tumorigenesis. This comprehensive review aims to synthesize recent findings elucidating the function of Circ-ADAM9 in many malignancies. Additionally, the review explores the possibility of Circ-ADAM9 as a valuable biomarker, offering insights into its prognostic, diagnostic, and therapeutic implications. By summarizing the latest discoveries in this field, the review contributes to our understanding of the multifaceted contribution of Circ-ADAM9 in tumor biology and its potential applications in clinical settings.

URI alleviates tyrosine kinase inhibitors-induced ferroptosis by reprogramming lipid metabolism in p53 wild-type liver cancers

The clinical benefit of tyrosine kinase inhibitors (TKIs)-based systemic therapy for advanced hepatocellular carcinoma (HCC) is limited due to drug resistance. Here, we uncover that lipid metabolism reprogramming mediated by unconventional prefoldin RPB5 interactor (URI) endows HCC with resistance to TKIs-induced ferroptosis. Mechanistically, URI directly interacts with TRIM28 and promotes p53 ubiquitination and degradation in a TRIM28-MDM2 dependent manner. Importantly, p53 binds to the promoter of stearoyl-CoA desaturase 1 (SCD1) and represses its transcription. High expression of URI is correlated with high level of SCD1 and their synergetic expression predicts poor prognosis and TKIs resistance in HCC. The combination of SCD1 inhibitor aramchol and deuterated sorafenib derivative donafenib displays promising anti-tumor effects in p53-wild type HCC patient-derived organoids and xenografted tumors. This combination therapy has potential clinical benefits for the patients with advanced HCC who have wild-type p53 and high levels of URI/SCD1.

Progress on the molecular mechanism of portal vein tumor thrombosis formation in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors, with poor prognosis and high mortality. Early-stage HCC has no obvious clinical symptoms, and most patients are already at an advanced stage when they are diagnosed. Portal vein tumor thrombus (PVTT) is the most common complication and a poor prognostic factor for HCC, which frequently leads to portal vein hypertension, ascites, gastrointestinal bleeding, and tumor metastasis. The formation of PVTT is related to the complex structure and hemodynamic changes of the portal vein and is closely related to changes at the cellular and molecular levels. The differentially-expressed genes (DEGs) between PVTT and primary tumor (PT) suggest that the two tissues may have different clonal origins. Epigenetic and proteomic analyses also suggest complex and diverse mechanisms for the formation of PVTT. In addition, the tumor microenvironment and energy metabolism pathways are interrelated in regulating the invasion and progression of PVTT. Aerobic glycolysis and the tumor immune microenvironment have been the focus of recent studies on PVTT. In this review, we summarize the mechanism of PVTT formation at the cellular and molecular levels to provide information to guide better prevention and treatment of PVTT in the clinic.

Portal vein tumor thrombosis in hepatocellular carcinoma: molecular mechanism and therapy

Portal vein tumor thrombosis (PVTT), a common complication of advanced hepatocellular carcinoma (HCC), remains the bottleneck of the treatments. Liver cancer cells potentially experienced multi-steps during PVTT process, including cancer cells leave from cancer nest, migrate in extracellular matrix, invade the vascular barrier, and colonize in the portal vein. Accumulated evidences have revealed numerous of molecular mechanisms including genetic and epigenetic regulation, cancer stem cells, immunosuppressive microenvironment, hypoxia, et al. contributed to the PVTT formation. In this review, we discuss state-of-the-art PVTT research on the potential molecular mechanisms and experimental models. In addition, we summarize PVTT-associated clinical trials and current treatments for PVTT and suppose perspectives exploring the molecular mechanisms and improving PVTT-related treatment for the future.

Discovery of synthetic lethal interactions from large-scale pan-cancer perturbation screens

The development of cancer therapies is limited by the availability of suitable drug targets. Potential candidate drug targets can be identified based on the concept of synthetic lethality (SL), which refers to pairs of genes for which an aberration in either gene alone is non-lethal, but co-occurrence of the aberrations is lethal to the cell. Here, we present SLIdR (Synthetic Lethal Identification in R), a statistical framework for identifying SL pairs from large-scale perturbation screens. SLIdR successfully predicts SL pairs even with small sample sizes while minimizing the number of false positive targets. We apply SLIdR to Project DRIVE data and find both established and potential pan-cancer and cancer type-specific SL pairs consistent with findings from literature and drug response screening data. We experimentally validate two predicted SL interactions (ARID1A-TEAD1 and AXIN1-URI1) in hepatocellular carcinoma, thus corroborating the ability of SLIdR to identify potential drug targets.

Macrophage Rmp Ameliorates Myocardial Infarction by Modulating Macrophage Polarization in Mice

Background

Inflammation plays important roles during myocardial infarction (MI). Macrophage polarization is a major factor that drives the inflammatory process. Our previous study found that RNA polymerase II subunit 5-mediating protein (RMP) knockout in cardiomyocytes caused heart failure by impairing mitochondrial structure and function. However, whether macrophage RMP plays a role in MI has not been investigated.

Methods

Macrophage RMP-knockout in combination with a mouse model of MI was used to study the function of macrophage RMP in MI. Next, we modified bone marrow-derived macrophages (BMDMs) by plasmid transfection, and the BMDMs were administered to LysM-Cre/DTR mice by tail vein injection. Immunoblotting and immunofluorescence were used to detect macrophage polarization, fibrosis, angiogenesis, and the p38 signaling pathway in each group.

Results

Macrophage RMP deficiency aggravates cardiac dysfunction, promotes M1 polarization, and inhibits angiogenesis after MI. However, RMP overexpression in macrophages promotes M2 polarization and angiogenesis after MI. Mechanistically, we found that RMP regulates macrophage polarization through the heat shock protein 90- (HSP90-) p38 signaling pathway.

Conclusions

Macrophage RMP plays a significant role in MI, likely by regulating macrophage polarization via the HSP90-p38 signaling pathway.

Exosomal S100A4 derived from highly metastatic hepatocellular carcinoma cells promotes metastasis by activating STAT3

Intercellular cross-talk plays important roles in cancer progression and metastasis. Yet how these cancer cells interact with each other is still largely unknown. Exosomes released by tumor cells have been proved to be effective cell-to-cell signal mediators. We explored the functional roles of exosomes in metastasis and the potential prognostic values for hepatocellular carcinoma (HCC). Exosomes were extracted from HCC cells of different metastatic potentials. The metastatic effects of exosomes derived from highly metastatic HCC cells (HMH) were evaluated both in vitro and in vivo. Exosomal proteins were identified with iTRAQ mass spectrum and verified in cell lines, xenograft tumor samples, and functional analyses. Exosomes released by HMH significantly enhanced the in vitro invasion and in vivo metastasis of low metastatic HCC cells (LMH). S100 calcium-binding protein A4 (S100A4) was identified as a functional factor in exosomes derived from HMH. S100A4^rich exosomes significantly promoted tumor metastasis both in vitro and in vivo compared with S100A4^low exosomes or controls. Moreover, exosomal S100A4 could induce expression of osteopontin (OPN), along with other tumor metastasis/stemness-related genes. Exosomal S100A4 activated OPN transcription via STAT3 phosphorylation. HCC patients with high exosomal S100A4 in plasma also had a poorer prognosis. In conclusion, exosomes from HMH could promote the metastatic potential of LMH, and exosomal S100A4 is a key enhancer for HCC metastasis, activating STAT3 phosphorylation and up-regulating OPN expression. This suggested exosomal S100A4 to be a novel prognostic marker and therapeutic target for HCC metastasis.

Identification of prognostic biomarkers associated with the occurrence of portal vein tumor thrombus in hepatocellular carcinoma

The occurrence of portal vein tumor thrombus (PVTT) is strongly correlated to the staging and poor prognosis of hepatocellular carcinoma (HCC) patients. However, the mechanisms of PVTT formation remain unclear. This study aimed to investigate differentially expressed genes (DEGs) between primary tumor (PT) and PVTT tissues and comprehensively explored the underlying mechanisms of PVTT formation. The DEGs between PT and paired PVTT tissues were analyzed using transcriptional data from the Gene Expression Omnibus (GEO) database. The expression, clinical relevance, prognostic significance, genetic alternations, DNA methylation, correlations with immune infiltration, co-expression correlations, and functional enrichment analysis of the DEGs were explored using multiple databases. As result, 12 DEGs were commonly down-expressed in PVTT compared with PT tissues among three datasets. The expression of DCN, CCL21, IGJ, CXCL14, FCN3, LAMA2, and NPY1R was progressively decreased from normal liver, PT, to PVTT tissues, whose up-expression associated with favorable survivals of HCC patients. The genetic alternations and DNA methylation of the DEGs frequently occurred, and several methylated CpG sites of the DEGs significantly correlated with outcomes of HCC patients. The immune infiltration in the tumor microenvironment of HCC was correlated with the expression level of the DEGs. Besides, the DEGs and their co-expressive genes participated in the biological processes of extracellular matrix (ECM) organization and focal adhesion. In summary, this study indicated the dysregulation of ECM and focal adhesion might contribute to the formation of PVTT. And the above seven genes might serve as potential biomarkers of PVTT occurrence and prognosis of HCC patients.

Transcriptome sequencing-based personalized analysis of hepatocellular carcinoma patients with portal vein tumor thrombus

Background

The mechanism of portal vein tumor thrombus (PVTT) in hepatocellular carcinoma (HCC) has been widely studied, and numerous diagnostic and prognostic biomarkers for HCC with PVTT have been identified. We aimed to evaluate the extent to which these biomarkers may aid the personalized precision therapy of HCC with PVTT.

Methods

Matched tissue specimens [primary HCC tumor (PT), adjacent normal (N) liver, and PVTT tissues] were acquired from 3 Chinese HCC patients who underwent surgery at Sun Yat-sen University Cancer Centre between 2019 and 2020. Ribonucleic acid (RNA) sequencing was performed on the 9 tissue samples. GFOLD (generalized fold change) algorithm was used to analyze the differently expressed genes (DEGs) between the PVTT, PT, and normal tissues from each patient. Genes with a P<0.01 and a |GFOLD value| >1 were identified as having significantly different expression.

Results

In total, 3,543, 32,472, and 12,901 tumorigenesis-associated genes, and 2,919, 17,679, and 14,825 metastasis-associated genes, were detected in Patient 1 (P1), Patient 2 (P2), and Patient 3 (P3), respectively. We analyzed the expression levels of genes associated with hypoxia, macrophage recruitment and cancer stem cells (CSCs). The results showed that hypoxia and CSCs may have contributed to tumorigenesis but not to metastasis in P1. We also found the hypoxia microenvironment played an important role in tumorigenesis and metastasis in P2, and CSCs may have contributed to metastasis. Additionally, we found that CSCs played critical roles in metastasis but not in tumorigenesis in P3. The results also showed that the long non-coding RNA (lncRNA) Metastasis-Associated Lung Adenocarcinoma Transcript 1 (MALAT1) was greatly overexpressed in the PTs and PVTT in all 3 patients, and Heart and Neural Crest Derivatives Expressed 2-antisense RNA 1 (HAND2-AS1) was downregulated in PVTT compared with PTs in all 3 patients. Thus, MALAT1 and HAND2-AS1 may be robust biomarkers for metastasis in HCC patients with PVTT.

Conclusions

Tumor-associated macrophages (TAMs)-targeted immunotherapy is a promising therapy for HCC patients with PVTT. LncRNAs MALAT1, and HAND2-AS1 may be promising targets for HCC therapy.

An Overview of ADAM9: Structure, Activation, and Regulation in Human Diseases

ADAM9 (A disintegrin and a metalloprotease 9) is a membrane-anchored protein that participates in a variety of physiological functions, primarily through the disintegrin domain for adhesion and the metalloprotease domain for ectodomain shedding of a wide variety of cell surface proteins. ADAM9 influences the developmental process, inflammation, and degenerative diseases. Recently, increasing evidence has shown that ADAM9 plays an important role in tumor biology. Overexpression of ADAM9 has been found in several cancer types and is correlated with tumor aggressiveness and poor prognosis. In addition, through either proteolytic or non-proteolytic pathways, ADAM9 promotes tumor progression, therapeutic resistance, and metastasis of cancers. Therefore, comprehensively understanding the mechanism of ADAM9 is crucial for the development of therapeutic anti-cancer strategies. In this review, we summarize the current understanding of ADAM9 in biological function, pathophysiological diseases, and various cancers. Recent advances in therapeutic strategies using ADAM9-related pathways are presented as well.

Epstein-Barr virus-encoded miR-BART11 promotes tumor-associated macrophage-induced epithelial-mesenchymal transition via targeting FOXP1 in gastric cancer

Gastric carcinoma (GC) is an Epstein-Barr virus (EBV)-associated malignancy characterized by early metastasis. Unlike that of cellular micro(mi)RNAs, the role of viral miRNAs in epithelial-mesenchymal transition (EMT) and metastasis in cancers has not been fully investigated. In this study, we elucidated the involvement of miR-BART11, an EBV-encoded viral miRNA, in the EMT and metastasis of GC cells. EBV-miR-BART11 upregulation can lead to downregulation of forkhead box protein P1 (FOXP1) in both tissues and cell lines of gastric carcinoma. Downregulation of FOXP1 might trigger the secretion of interleukin 1β (IL-1β), IL-6, and 1L-10 in cancer cells, resulting in poor survival of GC patients. We found that the observed EMT phenotypes resulted from the EBV-miR-BART11 overexpression-induced FOXP1 downregulation, which impacted the expression of the EMT-transcription factors E-cadherin and snail. We further demonstrated that conditioned medium-derived tumor-associated macrophages (TAMs) promoted phenotypic changes and expression of EMT-related molecules in GC cells. Additionally, EMT changes were significantly promoted in GC cells cultured in conditioned medium from TAMs infected with EBV-miR-BART11-containing lentivirus. On the contrary, GC cells cultured in conditioned medium from TAMs infected with FOXP1-carrying lentivirus showed little or no EMT change. Taken together, our results suggest that EBV-encoded viral miRNA BART11 downregulates the FOXP1 transcription factor, and promotes EMT by directly influencing gastric tumor cells or indirectly affecting the tumor microenvironment, which might, in turn, accelerate cancer invasion and metastasis, thereby affecting the survival and prognosis of patients.

RPB5-Mediating Protein Promotes Cholangiocarcinoma Tumorigenesis and Drug Resistance by Competing With NRF2 for KEAP1 Binding

BACKGROUND AND AIMS

Cancer cell survival depends on the balance between reactive oxygen species production and scavenging, which is regulated primarily by NRF2 during tumorigenesis. Here, we demonstrate that deletion of RBP5-mediating protein (RMP) in an autonomous mouse model of intrahepatic cholangiocarcinoma (ICC) delays tumor progression.

APPROACH AND RESULTS

RMP-overexpressing tumor cells exhibited enhanced tolerance to oxidative stress and apoptosis. Mechanistically, RMP competes with NRF2 for binding to the Kelch domain of KEAP1 (Kelch-like ECH-associated protein 1) through the E**E motif, leading to decreased NRF2 degradation via ubiquitination, thus increasing NRF2 nuclear translocation and downstream transactivation of antioxidant genes. This RMP-KEAP1-NRF2 axis promotes ICC tumorigenesis, metastasis, and drug resistance. Consistent with these findings, the RMP level in human ICC is positively correlated with the protein level of NRF2 and is associated with poor prognosis.

CONCLUSION

These findings reveal that RMP is involved in the oxidative stress defense program and could be exploited for targeted cancer therapies.

Systematic review of the roles of interleukins in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a primary liver cancer with high morbidity and mortality that is often accompanied by immune system disorders and local lymphocyte infiltration. Tumor-infiltrating lymphocytes, cancer cells, stromal cells, and the numerous cytokines they produce, such as chemokines, interferons, tumor necrosis factors, and interleukins, collectively constitute the tumor microenvironment. As a main type of immune effector, interleukin plays opposing roles in regulating tumor cell progression, adhesion, and migration according to its different subtypes. Many reports have concentrated on the roles that interleukins play in HCC, but understanding them systematically remains challenging. This study reviewed the current data to comprehensively summarize the relationships between HCC progression and human interleukin gene families.

HBx and c-MYC Cooperate to Induce URI1 Expression in HBV-Related Hepatocellular Carcinoma

Unconventional prefoldin RNA polymerase II subunit 5 interactor (URI1) has emerged as an oncogenic driver in hepatocellular carcinoma (HCC). Although the hepatitis B virus (HBV) represents the most common etiology of HCC worldwide, it is unknown whether URI1 plays a role in HBV-related HCC (HCC-B). In the present study, we investigated URI1 expression and its underlying mechanism in HCC-B tissues and cell lines. URI1 gene-promoter activity was determined by a luciferase assay. Human HCC-B samples were used for a chromatin immunoprecipitation assay. We found that c-MYC induced URI1 expression and activated the URI1 promoter through the E-box in the promoter region while the HBx protein significantly enhanced it. The positivity of URI1 expression was significantly higher in HCC-B tumor tissues than in non-HBV-related HCC tumor tissues, suggesting that a specific mechanism underlies URI1 expression in HCC-B. In tumor tissues from HCC-B patients, a significantly higher level of c-MYC was recruited to the E-box than in non-tumor tissues. These results suggest that HBx and c-MYC are involved in URI1 expression in HCC-B. URI1 expression may play important roles in the development and progression of HCC-B because HBx and c-MYC are well-known oncogenic factors in the virus and host, respectively.

RMP/URI inhibits both intrinsic and extrinsic apoptosis through different signaling pathways

The evading apoptosis of tumor cells may result in chemotherapy resistance. Therefore, investigating what molecular events contribute to drug-induced apoptosis, and how tumors evade apoptotic death, provides a paradigm to explain the relationship between cancer genetics and treatment sensitivity. In this study, we focused on the role of RMP/URI both in cisplatin-induced endogenous apoptosis and in TRAIL-induced exogenous apoptosis in HCC cells. Although flow cytometric analysis indicated that RMP overexpression reduced the apoptosis rate of HCC cells treated with both cisplatin and TRAIL, there was a difference in mechanism between the two treatments. Western blot showed that in intrinsic apoptosis induced by cisplatin, the overexpression of RMP promoted the Bcl-xl expression both in vitro and in vivo. Besides, RMP activated NF-κB/p65(rel) through the phosphorylation of ATM. However, in TRAIL-induced extrinsic apoptosis, RMP significantly suppressed the transcription and expression of P53. Moreover, the forced expression of P53 could offset this inhibitory effect. In conclusion, we presumed that RMP inhibited both intrinsic and extrinsic apoptosis through different signaling pathways. NF-κB was distinctively involved in the RMP circumvention of intrinsic apoptosis, but not in the extrinsic apoptosis of HCC cells. RMP might play an important role in defects of apoptosis, hence the chemotherapeutic resistance in hepatocellular carcinoma. These studies are promising to shed light on a more rational approach to clinical anticancer drug design and therapy.

Cardiomyocyte-specific loss of RNA polymerase II subunit 5-mediating protein causes myocardial dysfunction and heart failure

AIMS

Myocardial dysfunction is an important cause of heart failure (HF). RNA polymerase II subunit 5 (RPB5)-mediating protein (RMP) is a transcriptional mediating protein which co-ordinates cellular processes including gene expression, metabolism, proliferation, and genome stability. However, its role in cardiac disease remains unknown. We aimed to determine the role and regulatory mechanisms of RMP in cardiomyocyte function and the development of HF.

METHODS AND RESULTS

Myocardial RMP expression was examined in human heart tissues from healthy controls and patients with advanced HF. Compared to normal cardiac tissues, RMP levels were significantly decreased in the myocardium of patients with advanced HF. To investigate the role of RMP in cardiac function, Cre-loxP recombinase technology was used to generate tamoxifen-inducible cardiomyocyte-specific Rmp knockout mice. Unexpectedly, cardiomyocyte-specific deletion of Rmp in mice resulted in contractile dysfunction, cardiac dilatation, and fibrosis. Furthermore, the lifespan of cardiac-specific Rmp-deficient mice was significantly shortened when compared with littermates. Mechanistically, we found that chronic HF in Rmp-deficient mice was associated with impaired mitochondrial structure and function, which may be mediated via a transforming growth factor-β/Smad3-proliferator-activated receptor coactivator1α (PGC1α)-dependent mechanism. PGC1α overexpression partially rescued chronic HF in cardiomyocyte-specific Rmp-deficient mice, and Smad3 blockade protected against the loss of PGC1α and adenosine triphosphate content that was induced by silencing RMP in vitro.

CONCLUSIONS

RMP plays a protective role in chronic HF. RMP may protect cardiomyocytes from injury by maintaining PGC1α-dependent mitochondrial biogenesis and function. The results from this study suggest that RMP may be a potential therapeutic agent for treating HF.

Identification of portal vein tumor thrombus with an independent clonal origin in hepatocellular carcinoma via multi-omics data analysis

Objective

Multiple mechanisms underlying the development of portal vein tumor thrombus (PVTT) in hepatocellular carcinoma (HCC) have been reported recently. However, the origins of PVTT remain unknown. Increasing multi-omics data on PVTTs in HCCs have made it possible to investigate whether PVTTs originate from the corresponding primary tumors (Ts).

Methods

The clonal relationship between PVTTs and their corresponding primary Ts was investigated using datasets deposited in public databases. One DNA copy number variations dataset and three gene expression datasets were downloaded for the analyses. Clonality analysis was performed to investigate the clonal relationship between PVTTs and Ts from an individual patient. Differential gene expression analysis was applied to investigate the gene expression profiles of PVTTs and Ts.

Results

One out of 19 PVTTs had no clonal relationship with its corresponding T, whereas the others did. The PVTTs with independent clonal origin showed different gene expression and enrichment in biological processes from the primary Ts. Based on the unique gene expression profiles, a gene signature including 24 genes was used to identify pairs of PVTTs and primary Ts without any clonal relationship. Validation in three datasets showed that these types of pairs of PVTTs and Ts can be identified by the 24-gene signature.

Conclusions

Our findings show a direct evidence for PVTT origin and consolidate the heterogeneity of PVTTs observed in clinic. The results suggest that PVTT investigation at a molecular level is clinically necessary for diagnosis and treatment.

Comprehensive treatments for hepatocellular carcinoma with portal vein tumor thrombosis

Portal vein tumor thrombosis (PVTT) is one of the most common complications in hepatocellular carcinoma (HCC). HCC with PVTT usually indicates poor prognosis, which has a number of characteristics including a rapidly progressive disease course, worse liver function, complications connected with portal hypertension, and poorer tolerance to treatment. The exact mechanisms of PVTT remain unknown, even though some concerned signal transduction or molecular pathways have been identified. In western countries, sorafenib is the only recommended therapeutic strategy regardless of PVTT types. However, multiple treatment options including transhepatic arterial chemoembolization, hepatectomy, radiotherapy, and sorafenib available in the clinic. In this review, we enumerate and discuss therapeutics against patients with HCC having PVTT available in the clinic and put forward directions for future research.

RMP promotes epithelial-mesenchymal transition through NF-κB/CSN2/Snail pathway in hepatocellular carcinoma

Epithelial-mesenchymal transition (EMT) is a significant risk factor for metastasis in hepatocellular carcinoma (HCC) patients and with poor prognosis. In this study, we demonstrate the key role of RPB5-mediating protein (RMP) in EMT of HCC cells and the mechanism by which RMP promote EMT. RMP increases migration, invasion, and the progress of EMT of HCC cells, which facilitates the accumulation of Snail, a transcriptional repressor involved in EMT initiation. NF-κB is activated by RMP, which directly promotes the expression of COP9 signalosome 2 (CSN2) to repress the degradation of Snail. Pulmonary metastases mouse model demonstrates that RMP induces metastasis in vivo. Immunohistochemical analysis of human HCC tissues confirms the correlation of RMP with the expression of E-cadherin, p65, CSN2 and Snail in vivo. Collectively, these findings indicate that RMP promotes EMT and HCC metastasis through NF-κB/CSN2/Snail pathway. These results suggest that RMP and p65 may serve as potential candidates of the targets in the treatment of metastatic HCC.

ADAM9 mediates the interleukin-6-induced Epithelial-Mesenchymal transition and metastasis through ROS production in hepatoma cells

Interleukin (IL)-6 has been implicated in the invasion and metastasis of hepatocellular carcinoma (HCC). However, the molecular events that mediate this process are poorly understood. Here, we showed that IL-6 promoted the epithelial-mesenchymal transition (EMT) in HCC cell lines, and upregulated a disintegrin and metalloprotease 9 (ADAM9) expression by activating the JNK signaling pathway. ADAM9 was upregulated in human HCCs which promoted HCC cell invasion and the EMT by interacting with NADPH oxidase 1 and inducing reactive oxygen species generation. Knockdown of ADAM9 inhibited the IL-6-induced EMT. Additionally, ADAM9 expression was positively correlated with IL-6 and Snail expression in human HCC specimens. Taken together, our results showed that ADAM9 is an important mediator of IL-6-induced HCC cell migration and invasion, and may provide a novel therapeutic target for HCC management.

Role of the PAQosome in Regulating Arrangement of Protein Quaternary Structure in Health and Disease

The PAQosome, formerly known as the R2TP/PFDL complex, is an eleven-subunit cochaperone complex that assists HSP90 in the assembly of numerous large multisubunit protein complexes involved in essential cellular functions such as protein synthesis, ribosome biogenesis, transcription, splicing, and others. In this review, we discuss possible mechanisms of action and role of phosphorylation in the assembly of client complexes by the PAQosome as well as its potential role in cancer, ciliogenesis and ciliopathies.

Roles and Functions of the Unconventional Prefoldin URI

Almost 15 years ago, the URI prefoldin-like complex was discovered by Krek and colleagues in immunoprecipitation experiments conducted in mammalian cells with the aim of identifying new binding partners of the E3 ubiquitin-protein ligase S-phase kinase-associated protein 2 (SKP2) (Gstaiger et al. Science 302(5648):1208-1212, 2003). The URI prefoldin-like complex is a heterohexameric chaperone complex comprising two α and four β subunits (α2β4). The α subunits are URI and STAP1, while the β subunits are PFDN2, PFDN6, and PFDN4r, one of which is probably present in duplicate. Elucidating the roles and functions of these components in vitro and in vivo will help to clarify the mechanistic behavior of what appears to be a remarkably important cellular machine.

14-3-3ζ promotes hepatocellular carcinoma venous metastasis by modulating hypoxia-inducible factor-1α

Portal vein tumor thrombus (PVTT) is a type of intrahepatic metastasis arising from hepatocellular carcinoma (HCC) and is highly correlated with a poor prognosis. Hypoxia is common in solider tumors, including HCC, where it alters the behavior of HCC cells. We asked whether and how hypoxia contributes to PVTT formation. We demonstrated that increased intratumoral hypoxia is strongly associated with PVTT formation in HCC. We also showed that 14-3-3ζ is induced by hypoxia in HCC cells and correlates with PVTT formation in clinical HCC samples. In addition, 14-3-3ζ up-regulates HIF-1α expression by recruiting HDAC4, which prevents HIF-1α acetylation, thereby stabilizing the protein. Under hypoxic conditions in vitro, 14-3-3ζ knockdown inhibits hypoxia-induced HCC invasion by the HIF-1α/EMT pathway. Blockade of 14-3-3ζ in HCC cells reduces PVTT formation and distant lung metastasis in vivo. Moreover, a combination of 14-3-3ζ and HIF-1α expression is more prognostic for HCC patients than either protein alone. These results suggest that the hypoxia/14-3-3ζ/HIF-1α pathway plays an important role in PVTT formation and HCC metastasis.

Secretion of interleukin-6 by bone marrow mesenchymal stem cells promotes metastasis in hepatocellular carcinoma

Mesenchymal stem cells (MSCs) interact with tumor cells and regulate tumorigenesis and metastasis. As one of the important components of the tumor microenvironment, MSC-secreted cytokines play a critical role in cancer development. However, whether and how bone marrow MSCs (BMSCs) and their secreted cytokines participate in hepatocellular carcinoma (HCC) progression, still remains largely unknown. In the present study, we first measured the concentration of interleukin-6 (IL-6) in BMSC conditioned medium (BMSC-CM). Next, we assessed the changes of invasion ability in response to treatment of BMSC-CM or recombinant IL-6 in two human HCC cell lines Bel-7404 and HepG2. Then we analyzed the level of key components of the IL-6 signal pathway, including IL-6 receptor and signal transducer (i.e. IL-6R and gp130), a transcription factor STAT3 (signal transducer and activator of transcription 3), as well as its target genes BCL2, CCND1, MCL1 and MMP2, in BMSC-CM or recombinant IL-6 treated Bel-7404 and HepG2 cells. Results showed that a considerable amount of IL-6 was secreted by BMSCs, and BMSC-CM markedly elevated Bel-7404 cell invasion rate and stimulated the signal transduction of IL-6/STAT3 pathway. Neutralizing the secreted IL-6 bioactivity by the anti-IL-6 antibody diminished the invasion-promoting effect and down-regulated IL-6/STAT3 pathway of BMSC-CM treated Bel-7404 cells. In conclusion, we found that BMSCs may activate the IL-6/STAT3 signaling pathway and promote cell invasion in Bel-7404 cells, suggesting that this protumor effect should be seriously considered before clinical application of MSC-mediated cancer therapy.

Colorectal cancer cells display chaperone dependency for the unconventional prefoldin URI1

Chaperone dependency of cancer cells is an emerging trait that relates to the need of transformed cells to cope with the various stresses associated with the malignant state. URI1 (unconventional prefoldin RPB5 interactor 1) encodes a member of the prefoldin (PFD) family of molecular chaperones that acts as part of a heterohexameric PFD complex, the URI1 complex (URI1C), to promote assembly of multiprotein complexes involved in cell signaling and transcription processes. Here, we report that human colorectal cancer (CRCs) cell lines demonstrate differential dependency on URI1 and on the URI1 partner PFD STAP1 for survival, suggesting that this differential vulnerability of CRC cells is directly linked to URI1C chaperone function. Interestingly, in URI1-dependent CRC cells, URI1 deficiency is associated with non-genotoxic p53 activation and p53-dependent apoptosis. URI1-independent CRC cells do not exhibit such effects even in the context of wildtype p53. Lastly, in tumor xenografts, the conditional depletion of URI1 in URI1-dependent CRC cells was, after tumor establishment, associated with severe inhibition of subsequent tumor growth and activation of p53 target genes. Thus, a subset of CRC cells has acquired a dependency on the URI1 chaperone system for survival, providing an example of 'non-oncogene addiction' and vulnerability for therapeutic targeting.

RMP predicts survival and adjuvant TACE response in hepatocellular carcinoma

Adjuvant transcatheter arterial chemoembolization (TACE) protects against hepatocellular carcinoma (HCC) and is associated with reduced disease recurrence and improved outcome after surgery. However, deterioration of liver function after TACE negatively impacts the patient prognosis and limits it use as an option to prolong survival. We analyzed two independent cohorts that included a total of 510 patients with HCC who had undergone tumor resection. Immunohistochemistry assay was used to measure RPB5-mediating protein (RMP) expression and assessed their association with recurrence rate and response to therapy with adjuvant TACE. In patients with HCC, the expression of RMP in tumor is associated with age, gender, tumor size, portal venous invasion, TNM stages, BCLC stages and overall survival. Among patients with high RMP expression, adjuvant TACE after resection was associated with early recurrence. Even in the patients with small tumor size (no more than 5 cm) or no venous invasion, RMP status is associated with response to adjuvant TACE. RMP status in tumors may be a useful marker in estimating prognosis in patients with HCC and in assisting in the selection of patients who are likely to benefit from adjuvant TACE to prevent relapse.

A prognostic model predicts the risk of distant metastasis and death for patients with nasopharyngeal carcinoma based on pre-treatment interleukin 6 and clinical stage

Because inflammation plays a critical role in nasopharyngeal carcinoma (NPC), this study aims to investigate the correlation between the pro-inflammation cytokine interleukin-6 (IL6) and the prognosis of NPC and develop a new prognostic model. IL6 levels were measured in the serum of 290 NPC patients by ELISA and the correlation between IL6 and prognosis of NPC was evaluated by Kaplan-Meier analysis and multivariate analysis. The results showed that elevated IL6 levels were positively correlated with poorer 9-year overall survival (OS), disease-free survival (DFS), distant metastasis-free survival (DMFS) and lung metastasis-free survival (lung-MFS). IL6 level was an independent prognostic factor for OS, DFS, DMFS and lung-MFS. The CI-model based on TNM stage and IL6 level could better predict the OS, DFS, DMFS and lung-MFS of NPC patients. Here, the newly developed prognostic CI-model for predicting distant metastasis and death of NPC patients could facilitate patients consulting and individualized immunotherapy.

A splicing variant of Merlin promotes metastasis in hepatocellular carcinoma

Merlin, which is encoded by the tumour suppressor gene Nf2, plays a crucial role in tumorigenesis and metastasis. However, little is known about the functional importance of Merlin splicing forms. In this study, we show that Merlin is present at low levels in human hepatocellular carcinoma (HCC), particularly in metastatic tumours, where it is associated with a poor prognosis. Surprisingly, a splicing variant of Merlin that lacks exons 2, 3 and 4 (^Δ2–4Merlin) is amplified in HCC and portal vein tumour thrombus (PVTT) specimens and in the CSQT2 cell line derived from PVTT. Our studies show that ^Δ2–4Merlin interferes with the capacity of wild-type Merlin to bind β-catenin and ERM, and it is expressed in the cytoplasm rather than at the cell surface. Furthermore, ^Δ2–4Merlin overexpression increases the expression levels of β-catenin and stemness-related genes, induces the epithelium–mesenchymal-transition phenotype promoting cell migration in vitro and the formation of lung metastasis in vivo. Our results indicate that the ^Δ2–4Merlin variant disrupts the normal function of Merlin and promotes tumour metastasis.

Merlin plays a crucial role as a tumour suppressor in liver tumorigenesis. Here, the authors show that a splicing variant of Merlin that lacks exons 2,3 and 4 (^Δ2–4Merlin) is highly expressed in hepatocarcinoma and promotes tumour metastasis by interfering with the binding of wild-type Merlin to ß-catenin.

Comparative transcriptome analysis reveals that the extracellular matrix receptor interaction contributes to the venous metastases of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common type of liver cancer in the world. Portal vein tumor thrombus (PVTT) is one of the most serious complications of HCC and is strongly correlated with a poor prognosis for HCC patients. However, the detailed mechanism of PVTT development remains to be explored. In this study, we present a large-scale transcriptome analysis, by RNA sequencing, of 11 patients diagnosed with HCC with PVTT. The dysregulated genes between HCC and PVTT suggested that the extracellular matrix receptor interaction was correlated with the venous metastases of HCC. Among all of the recurrent alternative splicing events, we identified exon 6 skipping of RPS24, which is likely to be a cancer driver. We also identified five common fusion genes between HCC and its corresponding PVTT samples, including ARID1A-GPATCH3, MDM1-NUP107, PTGES3-RARG, PRLR-TERT, and C9orf3-TMC1. All of these findings broaden our knowledge of PVTT development and may also contribute to the diagnosis and treatment of HCC patients with PVTT.