Fibroblast-Derived Lysyl Oxidase Increases Oxidative Phosphorylation and Stemness in Cholangiocarcinoma

BACKGROUND & AIMS

Metabolic and transcriptional programs respond to extracellular matrix-derived cues in complex environments, such as the tumor microenvironment. Here, we demonstrate how lysyl oxidase (LOX), a known factor in collagen crosslinking, contributes to the development and progression of cholangiocarcinoma (CCA).

METHODS

Transcriptomes of 209 human CCA tumors, 143 surrounding tissues, and single-cell data from 30 patients were analyzed. The recombinant protein and a small molecule inhibitor of the LOX activity were used on primary patient-derived CCA cultures to establish the role of LOX in migration, proliferation, colony formation, metabolic fitness, and the LOX interactome. The oncogenic role of LOX was further investigated by RNAscope and in vivo using the AKT/NICD genetically engineered murine CCA model.

RESULTS

We traced LOX expression to hepatic stellate cells and specifically hepatic stellate cell-derived inflammatory cancer-associated fibroblasts and found that cancer-associated fibroblast-driven LOX increases oxidative phosphorylation and metabolic fitness of CCA, and regulates mitochondrial function through transcription factor A, mitochondrial. Inhibiting LOX activity in vivo impedes CCA development and progression. Our work highlights that LOX alters tumor microenvironment-directed transcriptional reprogramming of CCA cells by facilitating the expression of the oxidative phosphorylation pathway and by increasing stemness and mobility.

CONCLUSIONS

Increased LOX is driven by stromal inflammatory cancer-associated fibroblasts and correlates with diminished survival of patients with CCA. Modulating the LOX activity can serve as a novel tumor microenvironment-directed therapeutic strategy in bile duct pathologies.

Molecular portraits of patients with intrahepatic cholangiocarcinoma who diverge as rapid progressors or long survivors on chemotherapy

OBJECTIVE

Cytotoxic agents are the cornerstone of treatment for patients with advanced intrahepatic cholangiocarcinoma (iCCA), despite heterogeneous benefit. We hypothesised that the pretreatment molecular profiles of diagnostic biopsies can predict patient benefit from chemotherapy and define molecular bases of innate chemoresistance.

DESIGN

We identified a cohort of advanced iCCA patients with comparable baseline characteristics who diverged as extreme outliers on chemotherapy (survival <6 m in rapid progressors, RP; survival >23 m in long survivors, LS). Diagnostic biopsies were characterised by digital pathology, then subjected to whole-transcriptome profiling of bulk and geospatially macrodissected tissue regions. Spatial transcriptomics of tumour-infiltrating myeloid cells was performed using targeted digital spatial profiling (GeoMx). Transcriptome signatures were evaluated in multiple cohorts of resected cancers. Signatures were also characterised using in vitro cell lines, in vivo mouse models and single cell RNA-sequencing data.

RESULTS

Pretreatment transcriptome profiles differentiated patients who would become RPs or LSs on chemotherapy. Biologically, this signature originated from altered tumour-myeloid dynamics, implicating tumour-induced immune tolerogenicity with poor response to chemotherapy. The central role of the liver microenviroment was confrmed by the association of the RPLS transcriptome signature with clinical outcome in iCCA but not extrahepatic CCA, and in liver metastasis from colorectal cancer, but not in the matched primary bowel tumours.

CONCLUSIONS

The RPLS signature could be a novel metric of chemotherapy outcome in iCCA. Further development and validation of this transcriptomic signature is warranted to develop precision chemotherapy strategies in these settings.

FATP5 is indispensable for the growth of intrahepatic cholangiocarcinoma

Altered lipid metabolism is a common hallmark of various cancers, including Intrahepatic Cholangiocarcinoma (ICC), a highly lethal carcinoma that lacks effective treatment options. To elucidate the lipid metabolism changes in ICC, we coupled the expression of the firefly luciferase gene (FFL) to AKT1 (AKT-FFL) via an IRES linker, and then hydrodynamically injected mice with AKT-FFL and Notch1 intracellular cytoplasmic domain (NICD) to establish a luciferase-positive ICC model. This model not only enabled us to monitor and quantify tumor growth by injecting the mice with luciferin, but also allowed us to assess the fatty acid uptake rate by injecting the mice with free fatty acid luciferin (FFA-Luc). The ICC model exhibited robust uptake of exogenous fatty acids compared with the HCC model induced by AKT-FFL/ neuroblastoma Ras (Ras). Lipidomics analysis showed a dramatically higher level of fatty acid in ICC, further supporting the increased fatty acids uptake. Mechanistic studies identified FATP5 as the predominant mediator of fatty acid uptake required for ICC growth using Fatp5 knockout mice and AAV-based shRNA silencing of Fatp5. Our study discovered a novel therapeutic target for the treatment of ICC and shed light on the contributions of lipid metabolism to ICC development. Implications: This study provides the first in vivo evidence that FATP5 is a potential therapeutic target for treating ICC.

Aberrant fucosylation sustains the NOTCH and EGFR/NF-κB pathways and has a prognostic value in human intrahepatic cholangiocarcinoma

BACKGROUND AND AIMS

Intrahepatic cholangiocarcinoma (iCCA) is a lethal malignancy, with increasing incidence worldwide and limited therapeutic options. Aberrant protein glycosylation is a hallmark of cancer. Here, we thoroughly investigated the possible involvement of fucosylation in cholangiocarcinogenesis.

APPROACH AND RESULTS

We discovered that the levels of global fucosylation and members of the fucosylation pathway are ubiquitously upregulated in human iCCA tissues compared to nontumorous surrounding livers and normal biliary cells. In addition, total fucosylation levels correlate with poor patients' prognosis. Furthermore, fucosylation inhibition following 6-alkynylfucose (6AF) administration triggered a dose-dependent decrease in the proliferation and migration of iCCA cell lines. Notably, adding fucose to the cell medium annulled these effects. At the molecular level, 6AF administration or small interfering RNA-mediated silencing of GDP-L-fucose synthetase (FX) and the GDP-fucose transmembrane transporter (SLC35C1), both pivotal players of cellular fucosylation, decreased NOTCH activity, NOTCH1/Jagged1 interaction, NOTCH receptors, and related target genes in iCCA cell lines. In the same cells, EGFR, nuclear factor kappa-light-chain-enhancer of activated B cells p65, and Bcl-xL protein levels diminished, whereas IκBα (a critical cellular NF-κB inhibitor) increased after FX/SLC35C1 knockdown or 6AF administration. In the chick chorioallantoic membrane assay, 6AF treatment profoundly suppresses the growth of iCCA cells.

CONCLUSIONS

Elevated global fucosylation characterizes human iCCA, contributing to cell growth and migration through the upregulation of the NOTCH and EGFR/NF-κB pathways. Thus, aberrant fucosylation is a novel pathogenetic player and a potential therapeutic target for human iCCA.

Identification of DUSP4/6 overexpression as a potential rheostat to NRAS-induced hepatocarcinogenesis

BACKGROUND

Upregulation of the mitogen-activated protein kinase (MAPK) cascade is common in hepatocellular carcinoma (HCC). Neuroblastoma RAS viral oncogene homolog (NRAS) is mutated in a small percentage of HCC and is hitherto considered insufficient for hepatocarcinogenesis. We aimed to characterize the process of N-Ras-dependent carcinogenesis in the liver and to identify potential therapeutic vulnerabilities.

METHODS

NRAS V12 plasmid was delivered into the mouse liver via hydrodynamic tail vein injection (HTVI). The resulting tumours, preneoplastic lesions, and normal tissue were characterized by NanoString® gene expression analysis, Western Blot, and Immunohistochemistry (IHC). The results were further confirmed by in vitro analyses of HCC cell lines.

RESULTS

HTVI with NRAS V12 plasmid resulted in the gradual formation of preneoplastic and neoplastic lesions in the liver three months post-injection. These lesions mostly showed characteristics of HCC, with some exceptions of spindle cell/ cholangiocellular differentiation. Progressive upregulation of the RAS/RAF/MEK/ERK signalling was detectable in the lesions by Western Blot and IHC. NanoString® gene expression analysis of preneoplastic and tumorous tissue revealed a gradual overexpression of the cancer stem cell marker CD133 and Dual Specificity Phosphatases 4 and 6 (DUSP4/6). In vitro, transfection of HCC cell lines with NRAS V12 plasmid resulted in a coherent upregulation of DUSP4 and DUSP6. Paradoxically, this upregulation in PLC/PRF/5 cells was accompanied by a downregulation of phosphorylated extracellular-signal-regulated kinase (pERK), suggesting an overshooting compensation. Silencing of DUSP4 and DUSP6 increased proliferation in HCC cell lines.

CONCLUSIONS

Contrary to prior assumptions, the G12V NRAS mutant form is sufficient to elicit hepatocarcinogenesis in the mouse. Furthermore, the upregulation of the MAPK cascade was paralleled by the overexpression of DUSP4, DUSP6, and CD133 in vivo and in vitro. Therefore, DUSP4 and DUSP6 might fine-tune the excessive MAPK activation, a mechanism that can potentially be harnessed therapeutically.

Loss of TP53 cooperates with c-MET overexpression to drive hepatocarcinogenesis

Hepatocellular carcinoma (HCC) is a deadly malignancy with high genetic heterogeneity. TP53 mutation and c-MET activation are frequent events in human HCCs. Here, we discovered that the simultaneous mutations in TP53 and activation of c-MET occur in ~20% of human HCCs, and these patients show a poor prognosis. Importantly, we found that concomitant deletion of Trp53 and overexpression of c-MET (c-MET/sgp53) in the mouse liver led to HCC formation in vivo. Consistent with human HCCs, RNAseq showed that c-MET/sgp53 mouse HCCs were characterized by activated c-MET and Ras/MAPK cascades and increased tumor cell proliferation. Subsequently, a stably passaged cell line derived from a c-MET/sgp53 HCC and corresponding subcutaneous xenografts were generated. Also, in silico analysis suggested that the MEK inhibitor trametinib has a higher inhibition score in TP53 null human HCC cell lines, which was validated experimentally. We consistently found that trametinib effectively inhibited the growth of c-MET/sgp53 HCC cells and xenografts, supporting the possible usefulness of this drug for treating human HCCs with TP53-null mutations. Altogether, our study demonstrates that loss of TP53 cooperates with c-MET to drive hepatocarcinogenesis in vivo. The c-MET/sgp53 mouse model and derived HCC cell lines represent novel and useful preclinical tools to study hepatocarcinogenesis in the TP53 null background.

Combination of AFP vaccine and immune checkpoint inhibitors slows hepatocellular carcinoma progression in preclinical models

Many patients with hepatocellular carcinoma (HCC) do not respond to the first-line immune checkpoint inhibitor treatment. Immunization with effective cancer vaccines is an attractive alternative approach to immunotherapy. However, its efficacy remains insufficiently evaluated in preclinical studies. Here, we investigated HCC-associated self/tumor antigen, α-fetoprotein-based (AFP-based) vaccine immunization for treating AFP (+) HCC mouse models. We found that AFP immunization effectively induced AFP-specific CD8+ T cells in vivo. However, these CD8+ T cells expressed exhaustion markers, including PD1, LAG3, and Tim3. Furthermore, the AFP vaccine effectively prevented c-MYC/Mcl1 HCC initiation when administered before tumor formation, while it was ineffective against full-blown c-MYC/Mcl1 tumors. Similarly, anti-PD1 and anti-PD-L1 monotherapy showed no efficacy in this murine HCC model. In striking contrast, AFP immunization combined with anti-PD-L1 treatment triggered significant inhibition of HCC progression in most liver tumor nodules, while in combination with anti-PD1, it induced slower tumor progression. Mechanistically, we demonstrated that HCC-intrinsic PD-L1 expression was the primary target of anti-PD-L1 in this combination therapy. Notably, the combination therapy had a similar therapeutic effect in the cMet/β-catenin mouse HCC model. These findings suggest that combining the AFP vaccine and immune checkpoint inhibitors may be effective for AFP (+) HCC treatment.

Differential requirement of Hippo cascade during CTNNB1 or AXIN1 mutation-driven hepatocarcinogenesis

BACKGROUND AND AIMS

Gain-of-function (GOF) mutations of CTNNB1 and loss-of-function (LOF) mutations of AXIN1 are recurrent genetic alterations in hepatocellular carcinoma (HCC). We aim to investigate the functional contribution of Hippo/YAP/TAZ in GOF CTNNB1 or LOF AXIN1 mutant HCCs.

APPROACH AND RESULTS

The requirement of YAP/TAZ in c-Met/β-Catenin and c-Met/sgAxin1-driven HCC was analyzed using conditional Yap , Taz , and Yap;Taz knockout (KO) mice. Mechanisms of AXIN1 in regulating YAP/TAZ were investigated using AXIN1 mutated HCC cells. Hepatocyte-specific inducible TTR-CreER T2KO system was applied to evaluate the role of Yap;Taz during tumor progression. Cabozantinib and G007-LK combinational treatment were tested in vitro and in vivo . Nuclear YAP/TAZ was strongly induced in c-Met/sgAxin1 mouse HCC cells. Activation of Hippo via overexpression of Lats2 or concomitant deletion of Yap and Taz significantly inhibited c-Met/sgAxin1 driven HCC development, whereas the same approaches had mild effects in c-Met/β-Catenin HCCs. YAP is the major Hippo effector in c-Met/β-Catenin HCCs, and both YAP and TAZ are required for c-Met/sgAxin1-dependent hepatocarcinogenesis. Mechanistically, AXIN1 binds to YAP/TAZ in human HCC cells and regulates YAP/TAZ stability. Genetic deletion of YAP/TAZ suppresses already formed c-Met/sgAxin1 liver tumors, supporting the requirement of YAP/TAZ during tumor progression. Importantly, tankyrase inhibitor G007-LK, which targets Hippo and Wnt pathways, synergizes with cabozantinib, a c-MET inhibitor, leading to tumor regression in the c-Met/sgAxin1 HCC model.

CONCLUSIONS

Our studies demonstrate that YAP/TAZ are major signaling molecules downstream of LOF AXIN1 mutant HCCs, and targeting YAP/TAZ is an effective treatment against AXIN1 mutant human HCCs.

Critical evaluation of molecular tumour board outcomes following 2 years of clinical practice in a Comprehensive Cancer Centre

BACKGROUND

Recently, molecular tumour boards (MTBs) have been integrated into the clinical routine. Since their benefit remains debated, we assessed MTB outcomes in the Comprehensive Cancer Center Ostbayern (CCCO) from 2019 to 2021.

METHODS AND RESULTS

In total, 251 patients were included. Targeted sequencing was performed with PCR MSI-evaluation and immunohistochemistry for PD-L1, Her2, and mismatch repair enzymes. 125 treatment recommendations were given (49.8%). High-recommendation rates were achieved for intrahepatic cholangiocarcinoma (20/30, 66.7%) and gastric adenocarcinoma (10/16, 62.5%) as opposed to colorectal cancer (9/36, 25.0%) and pancreatic cancer (3/18, 16.7%). MTB therapies were administered in 47 (18.7%) patients, while 53 (21.1%) received alternative treatment regimens. Thus 37.6% of recommended MTB therapies were implemented (47/125 recommendations). The clinical benefit rate (complete + partial + mixed response + stable disease) was 50.0% for MTB and 63.8% for alternative treatments. PFS2/1 ratios were 34.6% and 16.1%, respectively. Significantly improved PFS could be achieved for m1A-tier-evidence-based MTB therapies (median 6.30 months) compared to alternative treatments (median 2.83 months; P = 0.0278).

CONCLUSION

The CCCO MTB yielded a considerable recommendation rate, particularly in cholangiocarcinoma patients. The discrepancy between the low-recommendation rates in colorectal and pancreatic cancer suggests the necessity of a weighted prioritisation of entities. High-tier recommendations should be implemented predominantly.

Criteria for preclinical models of cholangiocarcinoma: scientific and medical relevance

Cholangiocarcinoma (CCA) is a rare malignancy that develops at any point along the biliary tree. CCA has a poor prognosis, its clinical management remains challenging, and effective treatments are lacking. Therefore, preclinical research is of pivotal importance and necessary to acquire a deeper understanding of CCA and improve therapeutic outcomes. Preclinical research involves developing and managing complementary experimental models, from in vitro assays using primary cells or cell lines cultured in 2D or 3D to in vivo models with engrafted material, chemically induced CCA or genetically engineered models. All are valuable tools with well-defined advantages and limitations. The choice of a preclinical model is guided by the question(s) to be addressed; ideally, results should be recapitulated in independent approaches. In this Consensus Statement, a task force of 45 experts in CCA molecular and cellular biology and clinicians, including pathologists, from ten countries provides recommendations on the minimal criteria for preclinical models to provide a uniform approach. These recommendations are based on two rounds of questionnaires completed by 35 (first round) and 45 (second round) experts to reach a consensus with 13 statements. An agreement was defined when at least 90% of the participants voting anonymously agreed with a statement. The ultimate goal was to transfer basic laboratory research to the clinics through increased disease understanding and to develop clinical biomarkers and innovative therapies for patients with CCA.

Early Subcellular Hepatocellular Alterations in Mice Post Hydrodynamic Transfection: An Explorative Study

Hydrodynamic transfection (HT) or hydrodynamic tail vein injection (HTVi) is among the leading technique that is used to deliver plasmid genes mainly into the liver of live mice or rats. The DNA constructs are composed of coupled plasmids, while one contains the gene of interest that stably integrate into the hepatocyte genome with help of the other consisting sleeping beauty transposase system. The rapid injection of a large volume of DNA-solution through the tail vein induces an acute cardiac congestion that refluxed into the liver, mainly in acinus zone 3, also found through our EM study. Although, HT mediated hydrodynamic force can permeabilizes the fenestrated sinusoidal endothelium of liver, but the mechanism of plasmid incorporation into the hepatocytes remains unclear. Therefore, in the present study, we have hydrodynamically injected 2 mL volume of empty plasmid (transposon vector) or saline solution (control) into the tail vein of anesthetized C57BL/6J/129Sv mice. Liver tissue was resected at different time points from two animal group conditions, i.e., one time point per animal (1, 5, 10-20, 60 min or 24 and 48 hrs after HT) or multiple time points per animal (0, 1, 2, 5, 10, 20 min) and quickly fixed with buffered 4% osmium tetroxide. The tissues fed with only saline solution was also resected and fixed in the similar way. EM evaluation from the liver ultrathin sections reveals that swiftly after 1 min, the hepatocytes near to the central venule in the acinus zone 3 shows cytoplasmic membrane-bound vesicles. Such vesicles increased in both numbers and size to vacuoles and precisely often found in the proximity to the nucleus. Further, EM affirm these vacuoles are also optically empty and do not contain any electron dense material. Although, some of the other hepatocytes reveals sign of cell damage including swollen mitochondria, dilated endoplasmic reticulum, Golgi apparatus and disrupted plasma membrane, but most of the hepatocytes appeared normal. The ultrastructural findings in the mice injected with empty vector or saline injected control mice were similar. Therefore, we have interpreted the vacuole formation as nonspecific endocytosis without specific interactions at the plasma membrane.

Cholangiocarcinoma progression depends on the uptake and metabolization of extracellular lipids

BACKGROUND AND AIMS

Cholangiocarcinoma (CCA) includes a heterogeneous group of biliary cancers with a dismal prognosis. We investigated if lipid metabolism is disrupted in CCA and its role in tumor proliferation.

APPROACH AND RESULTS

The in vitro and in vivo tumorigenic capacity of five human CCA cell lines was analyzed. Proteome, lipid content, and metabolic fluxes were evaluated in CCA cells and compared with normal human cholangiocytes (NHC). The Akt1/NOTCH1 intracellular cytoplasmic domain (Nicd1)-driven CCA mouse model was also evaluated. The proteome of CCA cells was enriched in pathways involved in lipid and lipoprotein metabolism. The EGI1 CCA cell line presented the highest tumorigenic capacity. Metabolic studies in high (EGI1) versus low (HUCCT1) proliferative CCA cells in vitro showed that both EGI1 and HUCCT1 incorporated more fatty acids (FA) than NHC, leading to increased triglyceride storage, also observed in Akt1/Nicd1-driven CCA mouse model. The highly proliferative EGI1 CCA cells showed greater uptake of very-low-density and HDLs than NHC and HUCCT1 CCA cells and increased cholesteryl ester content. The FA oxidation (FAO) and related proteome enrichment were specifically up-regulated in EGI1, and consequently, pharmacological blockade of FAO induced more pronounced inhibition of their tumorigenic capacity compared with HUCCT1. The expression of acyl-CoA dehydrogenase ACADM, the first enzyme involved in FAO, was increased in human CCA tissues and correlated with the proliferation marker PCNA.

CONCLUSIONS

Highly proliferative human CCA cells rely on lipid and lipoprotein uptake to fuel FA catabolism, suggesting that inhibition of FAO and/or lipid uptake could represent a therapeutic strategy for this CCA subclass.

Crenigacestat blocking notch pathway reduces liver fibrosis in the surrounding ecosystem of intrahepatic CCA viaTGF-β inhibition

BACKGROUND

Intrahepatic cholangiocarcinoma (iCCA) is a highly malignant tumor characterized by an intensive desmoplastic reaction due to the exaggerated presence of the extracellular (ECM) matrix components. Liver fibroblasts close to the tumor, activated by transforming growth factor (TGF)-β1 and expressing high levels of α-smooth muscle actin (α-SMA), become cancer-associated fibroblasts (CAFs). CAFs are deputed to produce and secrete ECM components and crosstalk with cancer cells favoring tumor progression and resistance to therapy. Overexpression of Notch signaling is implicated in CCA development and growth. The study aimed to determine the effectiveness of the Notch inhibitor, Crenigacestat, on the surrounding microenvironment of iCCA.

METHODS

We investigated Crenigacestat's effectiveness in a PDX model of iCCA and human primary culture of CAFs isolated from patients with iCCA.

RESULTS

In silico analysis of transcriptomic profiling from PDX iCCA tissues treated with Crenigacestat highlighted "liver fibrosis" as one of the most modulated pathways. In the iCCA PDX model, Crenigacestat treatment significantly (p < 0.001) reduced peritumoral liver fibrosis. Similar results were obtained in a hydrodynamic model of iCCA. Bioinformatic prediction of the upstream regulators related to liver fibrosis in the iCCA PDX treated with Crenigacestat revealed the involvement of the TGF-β1 pathway as a master regulator gene showing a robust connection between TGF-β1 and Notch pathways. Consistently, drug treatment significantly (p < 0.05) reduced TGF-β1 mRNA and protein levels in tumoral tissue. In PDX tissues, Crenigacestat remarkably inhibited TGF-β signaling and extracellular matrix protein gene expression and reduced α-SMA expression. Furthermore, Crenigacestat synergistically increased Gemcitabine effectiveness in the iCCA PDX model. In 31 iCCA patients, TGF-β1 and α-SMA were upregulated in the tumoral compared with peritumoral tissues. In freshly isolated CAFs from patients with iCCA, Crenigacestat significantly (p < 0.001) inhibited Notch signaling, TGF-β1 secretion, and Smad-2 activation. Consequently, Crenigacestat also inactivated CAFs reducing (p < 0.001) α-SMA expression. Finally, CAFs treated with Crenigacestat produced less (p < 005) ECM components such as fibronectin, collagen 1A1, and collagen 1A2.

CONCLUSIONS

Notch signaling inhibition reduces the peritumoral desmoplastic reaction in iCCA, blocking the TGF-β1 canonical pathway.

Therapeutic efficacy of FASN inhibition in preclinical models of HCC

BACKGROUND AND AIMS

Aberrant activation of fatty acid synthase (FASN) is a major metabolic event during the development of HCC. We evaluated the therapeutic efficacy of TVB3664, a FASN inhibitor, either alone or in combination, for HCC treatment.

APPROACH AND RESULTS

The therapeutic efficacy and the molecular pathways targeted by TVB3664, either alone or with tyrosine kinase inhibitors or the checkpoint inhibitor anti-programmed death ligand 1 antibody, were assessed in human HCC cell lines and multiple oncogene-driven HCC mouse models. RNA sequencing was performed to elucidate the effects of TVB3664 on global gene expression and tumor metabolism. TVB3664 significantly ameliorated the fatty liver phenotype in the aged mice and AKT-induced hepatic steatosis. TVB3664 monotherapy showed moderate efficacy in NASH-related murine HCCs, induced by loss of phosphatase and tensin homolog and MET proto-oncogene, receptor tyrosine kinase (c-MET) overexpression. TVB3664, in combination with cabozantinib, triggered tumor regression in this murine model but did not improve the responsiveness to immunotherapy. Global gene expression revealed that TVB3664 predominantly modulated metabolic processes, whereas TVB3664 synergized with cabozantinib to down-regulate multiple cancer-related pathways, especially the AKT/mammalian target of rapamycin pathway and cell proliferation genes. TVB3664 also improved the therapeutic efficacy of sorafenib and cabozantinib in the FASN-dependent c-MYC-driven HCC model. However, TVB3664 had no efficacy nor synergistic effects in FASN-independent murine HCC models.

CONCLUSIONS

This preclinical study suggests the limited efficacy of targeting FASN as monotherapy for HCC treatment. However, FASN inhibitors could be combined with other drugs for improved effectiveness. These combination therapies could be developed based on the driver oncogenes, supporting precision medicine approaches for HCC treatment.

Wnt/β-Catenin-Pathway Alterations and Homologous Recombination Deficiency in Cholangiocarcinoma Cell Lines and Clinical Samples: Towards Specific Vulnerabilities

Cholangiocarcinoma (CCA) features a dismal prognosis with limited treatment options. Genomic studies have unveiled several promising targets in this disease, including fibroblast growth factor receptor (FGFR) fusions and isocitrate dehydrogenase (IDH) mutations. To fully harness the potential of genomically informed therapies in CCA, it is necessary to thoroughly characterize the available model organisms, including cell lines. One parameter to investigate in CCA is homologous recombination deficiency (HRD). While mutations in homologous recombinational repair (HRR)-related genes have been detected, their predictive value remains undetermined. Using a targeted next-generation sequencing approach, we analyzed 12 human CCA cell lines and compared them to 62 CCA samples of the molecular tumor board cohort. The AmoyDx^® HRD Focus Panel was employed to determine corresponding genomic scar scores (GSS). Ten of twelve cell lines harbored alterations in common HRR-related genes, and five cell lines were HRD-positive, although this parameter did not correlate well with Olaparib sensitivity. Moreover, functionally relevant APC and β-catenin mutations were registered, which were also detected in 4/176 (2.3%) samples on a CCA microarray. Although rare, these alterations were exclusive to large duct type CCA with associated intraductal papillary neoplasms of the bile duct (IPNB) in 3 cases, pointing at a distinct form of cholangiocarcinogenesis with potential specific vulnerabilities.

Histone H3K27 demethylase KDM6A is an epigenetic gatekeeper of mTORC1 signalling in cancer

OBJECTIVE

Large-scale genome sequencing efforts of human tumours identified epigenetic modifiers as one of the most frequently mutated gene class in human cancer. However, how these mutations drive tumour development and tumour progression are largely unknown. Here, we investigated the function of the histone demethylase KDM6A in gastrointestinal cancers, such as liver cancer and pancreatic cancer.

DESIGN

Genetic alterations as well as expression analyses of KDM6A were performed in patients with liver cancer. Genetic mouse models of liver and pancreatic cancer coupled with Kdm6a-deficiency were investigated, transcriptomic and epigenetic profiling was performed, and in vivo and in vitro drug treatments were conducted.

RESULTS

KDM6A expression was lost in 30% of patients with liver cancer. Kdm6a deletion significantly accelerated tumour development in murine liver and pancreatic cancer models. Kdm6a-deficient tumours showed hyperactivation of mTORC1 signalling, whereas endogenous Kdm6a re-expression by inducible RNA-interference in established Kdm6a-deficient tumours diminished mTORC1 activity resulting in attenuated tumour progression. Genome-wide transcriptional and epigenetic profiling revealed direct binding of Kdm6a to crucial negative regulators of mTORC1, such as Deptor, and subsequent transcriptional activation by epigenetic remodelling. Moreover, in vitro and in vivo genetic epistasis experiments illustrated a crucial function of Deptor and mTORC1 in Kdm6a-dependent tumour suppression. Importantly, KDM6A expression in human tumours correlates with mTORC1 activity and KDM6A-deficient tumours exhibit increased sensitivity to mTORC1 inhibition.

CONCLUSION

KDM6A is an important tumour suppressor in gastrointestinal cancers and acts as an epigenetic toggle for mTORC1 signalling. Patients with KDM6A-deficient tumours could benefit of targeted therapy focusing on mTORC1 inhibition.

β-Catenin Sustains and Is Required for YES-associated Protein Oncogenic Activity in Cholangiocarcinoma

BACKGROUND & AIMS

YES-associated protein (YAP) aberrant activation is implicated in intrahepatic cholangiocarcinoma (iCCA). Transcriptional enhanced associate domain (TEAD)-mediated transcriptional regulation is the primary signaling event downstream of YAP. The role of Wnt/β-Catenin signaling in cholangiocarcinogenesis remains undetermined. Here, we investigated the possible molecular interplay between YAP and β-Catenin cascades in iCCA.

METHODS

Activated AKT (Myr-Akt) was coexpressed with YAP (YapS127A) or Tead2VP16 via hydrodynamic tail vein injection into mouse livers. Tumor growth was monitored, and liver tissues were collected and analyzed using histopathologic and molecular analysis. YAP, β-Catenin, and TEAD interaction in iCCAs was investigated through coimmunoprecipitation. Conditional Ctnnb1 knockout mice were used to determine β-Catenin function in murine iCCA models. RNA sequencing was performed to analyze the genes regulated by YAP and/or β-Catenin. Immunostaining of total and nonphosphorylated/activated β-Catenin staining was performed in mouse and human iCCAs.

RESULTS

We discovered that TEAD factors are required for YAP-dependent iCCA development. However, transcriptional activation of TEADs did not fully recapitulate YAP's activities in promoting cholangiocarcinogenesis. Notably, β-Catenin physically interacted with YAP in human and mouse iCCA. Ctnnb1 ablation strongly suppressed human iCCA cell growth and Yap-dependent cholangiocarcinogenesis. Furthermore, RNA-sequencing analysis revealed that YAP/ transcriptional coactivator with PDZ-binding motif (TAZ) regulate a set of genes significantly overlapping with those controlled by β-Catenin. Importantly, activated/nonphosphorylated β-Catenin was detected in more than 80% of human iCCAs.

CONCLUSION

YAP induces cholangiocarcinogenesis via TEAD-dependent transcriptional activation and interaction with β-Catenin. β-Catenin binds to YAP in iCCA and is required for YAP full transcriptional activity, revealing the functional crosstalk between YAP and β-Catenin pathways in cholangiocarcinogenesis.

Targeting NAE1-mediated protein hyper-NEDDylation halts cholangiocarcinogenesis and impacts on tumor-stroma crosstalk in experimental models

BACKGROUND & AIMS

Cholangiocarcinoma (CCA) comprises a heterogeneous group of malignant tumors associated with dismal prognosis. Alterations in post-translational modifications (PTMs), including NEDDylation, result in abnormal protein dynamics, cell disturbances and disease. Herein, we investigate the role of NEDDylation in CCA development and progression.

METHODS

Levels and functions of NEDDylation, together with response to pevonedistat (NEDDylation inhibitor) or CRISPR/Cas9 against NAE1 were evaluated in vitro, in vivo and/or in patients with CCA. The development of preneoplastic lesions in Nae1^+/- mice was investigated using an oncogene-driven CCA model. The impact of NEDDylation in CCA cells on tumor-stroma crosstalk was assessed using CCA-derived cancer-associated fibroblasts (CAFs). Proteomic analyses were carried out by mass-spectrometry.

RESULTS

The NEDDylation machinery was found overexpressed and overactivated in human CCA cells and tumors. Most NEDDylated proteins found upregulated in CCA cells, after NEDD8-immunoprecipitation and further proteomics, participate in the cell cycle, proliferation or survival. Genetic (CRISPR/Cas9-NAE1) and pharmacological (pevonedistat) inhibition of NEDDylation reduced CCA cell proliferation and impeded colony formation in vitro. NEDDylation depletion (pevonedistat or Nae1^+/- mice) halted tumorigenesis in subcutaneous, orthotopic, and oncogene-driven models of CCA in vivo. Moreover, pevonedistat potentiated chemotherapy-induced cell death in CCA cells in vitro. Mechanistically, impaired NEDDylation triggered the accumulation of both cullin RING ligase and NEDD8 substrates, inducing DNA damage and cell cycle arrest. Furthermore, impaired NEDDylation in CCA cells reduced the secretion of proteins involved in fibroblast activation, angiogenesis, and oncogenic pathways, ultimately hampering CAF proliferation and migration.

CONCLUSION

Aberrant protein NEDDylation contributes to cholangiocarcinogenesis by promoting cell survival and proliferation. Moreover, NEDDylation impacts the CCA-stroma crosstalk. Inhibition of NEDDylation with pevonedistat may represent a potential therapeutic strategy for patients with CCA.

LAY SUMMARY

Little is known about the role of post-translational modifications of proteins in cholangiocarcinoma development and progression. Herein, we show that protein NEDDylation is upregulated and hyperactivated in cholangiocarcinoma, promoting tumor growth. Pharmacological inhibition of NEDDylation halts cholangiocarcinogenesis and could be an effective therapeutic strategy to tackle these tumors.

The Hippo pathway effector TAZ induces intrahepatic cholangiocarcinoma in mice and is ubiquitously activated in the human disease

Background

Intrahepatic cholangiocarcinoma (iCCA) is a highly aggressive primary liver tumor with increasing incidence worldwide, dismal prognosis, and few therapeutic options. Mounting evidence underlines the role of the Hippo pathway in this disease; however, the molecular mechanisms whereby the Hippo cascade contributes to cholangiocarcinogenesis remain poorly defined.

Methods

We established novel iCCA mouse models via hydrodynamic transfection of an activated form of transcriptional coactivator with PDZ-binding motif (TAZ), a Hippo pathway downstream effector, either alone or combined with the myristoylated AKT (myr-AKT) protooncogene, in the mouse liver. Hematoxylin and eosin staining, immunohistochemistry, electron microscopy, and quantitative real-time RT-PCR were applied to characterize the models. In addition, in vitro cell line studies were conducted to address the growth-promoting roles of TAZ and its paralog YAP.

Results

Overexpression of TAZ in the mouse liver triggered iCCA development with very low incidence and long latency. In contrast, co-expression of TAZ and myr-AKT dramatically increased tumor frequency and accelerated cancer formation in mice, with 100% iCCA incidence and high tumor burden by 10 weeks post hydrodynamic injection. AKT/TAZ tumors faithfully recapitulated many of the histomolecular features of human iCCA. At the molecular level, the development of the cholangiocellular lesions depended on the binding of TAZ to TEAD transcription factors. In addition, inhibition of the Notch pathway did not hamper carcinogenesis but suppressed the cholangiocellular phenotype of AKT/TAZ tumors. Also, knockdown of YAP, the TAZ paralog, delayed cholangiocarcinogenesis in AKT/TAZ mice without affecting the tumor phenotype. Furthermore, human preinvasive and invasive iCCAs and mixed hepatocellular carcinoma/iCCA displayed widespread TAZ activation and downregulation of the mechanisms protecting TAZ from proteolysis.

Conclusions

Overall, the present data underscore the crucial role of TAZ in cholangiocarcinogenesis

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-022-02394-2.

Corrigendum: Pathogenetic, Prognostic, and Therapeutic Role of Fatty Acid Synthase in Human Hepatocellular Carcinoma

[This corrects the article DOI: 10.3389/fonc.2019.01412.].

CD90 is regulated by notch1 and hallmarks a more aggressive intrahepatic cholangiocarcinoma phenotype

BACKGROUND

Intrahepatic Cholangiocarcinoma (iCCA) is characterized by a strong stromal reaction playing a role in tumor progression. Thymus cell antigen 1 (THY1), also called Cluster of Differentiation 90 (CD90), is a key regulator of cell-cell and cell-matrix interaction. In iCCA, CD90 has been reported to be associated with a poor prognosis. In an iCCA PDX model, we recently found that CD90 was downregulated in mice treated with the Notch γ-secretase inhibitor Crenigacestat. The study aims to investigate the role of CD90 in relation to the NOTCH pathway.

METHODS

THY1/CD90 gene and protein expression was evaluated in human iCCA tissues and xenograft models by qRT-PCR, immunohistochemistry, and immunofluorescence. Notch1 inhibition was achieved by siRNA. THY1/CD90 functions were investigated in xenograft models built with HuCCT1 and KKU-M213 cell lines, engineered to overexpress or knockdown THY1, respectively.

RESULTS

CD90 co-localized with EPCAM, showing its epithelial origin. In vitro, NOTCH1 silencing triggered HES1 and THY1 down-regulation. RBPJ, a critical transcriptional regulator of NOTCH signaling, exhibited putative binding sites on the THY1 promoter and bound to the latter, implying CD90 as a downstream NOTCH pathway effector. In vivo, Crenigacestat suppressed iCCA growth and reduced CD90 expression in the PDX model. In the xenograft model, Crenigacestat inhibited tumor growth of HuCCT1 cells transfected to overexpress CD90 and KKU-M213 cells constitutively expressing high levels of CD90, while not affecting the growth of HuCCT1 control cells and KKU-M213 depleted of CD90. In an iCCA cohort, patients with higher expression levels of NOTCH1/HES1/THY1 displayed a significantly shorter survival.

CONCLUSIONS

iCCA patients with higher NOTCH1/HES1/THY1 expression have the worst prognosis, but they are more likely to benefit from Notch signaling inhibition. These findings represent the scientific rationale for testing NOTCH1 inhibitors in clinical trials, taking the first step toward precision medicine for iCCA.

β-Catenin signaling in hepatocellular carcinoma

Deregulated Wnt/β-catenin signaling is one of the main genetic alterations in human hepatocellular carcinoma (HCC). Comprehensive genomic analyses have revealed that gain-of-function mutation of CTNNB1, which encodes β-catenin, and loss-of-function mutation of AXIN1 occur in approximately 35% of human HCC samples. Human HCCs with activation of the Wnt/β-catenin pathway demonstrate unique gene expression patterns and pathological features. Activated Wnt/β-catenin synergizes with multiple signaling cascades to drive HCC formation, and it functions through its downstream effectors. Therefore, strategies targeting Wnt/β-catenin have been pursued as possible therapeutics against HCC. Here, we review the genetic alterations and oncogenic roles of aberrant Wnt/β-catenin signaling during hepatocarcinogenesis. In addition, we discuss the implication of this pathway in HCC diagnosis, classification, and personalized treatment.

Role of Lipogenesis Rewiring in Hepatocellular Carcinoma

Metabolic rewiring is one of the hallmarks of cancer. Altered de novo lipogenesis is one of the pivotal metabolic events deregulated in cancers. Sterol regulatory element-binding transcription factor 1 (SREBP1) controls the transcription of major enzymes involved in de novo lipogenesis, including ACLY, ACACA, FASN, and SCD. Studies have shown the increased de novo lipogenesis in human hepatocellular carcinoma (HCC) samples. Multiple mechanisms, such as activation of the AKT/mechanistic target of rapamycin (mTOR) pathway, lead to high SREBP1 induction and the coordinated enhanced expression of ACLY, ACACA, FASN, and SCD genes. Subsequent functional analyses have unraveled these enzymes' critical role(s) and the related de novo lipogenesis in hepatocarcinogenesis. Importantly, targeting these molecules might be a promising strategy for HCC treatment. This paper comprehensively summarizes de novo lipogenesis rewiring in HCC and how this pathway might be therapeutically targeted.

S-Adenosylmethionine: From the Discovery of Its Inhibition of Tumorigenesis to Its Use as a Therapeutic Agent

Alterations of methionine cycle in steatohepatitis, cirrhosis, and hepatocellular carcinoma induce MAT1A decrease and MAT2A increase expressions with the consequent decrease of S-adenosyl-L-methionine (SAM). This causes non-alcoholic fatty liver disease (NAFLD). SAM administration antagonizes pathological conditions, including galactosamine, acetaminophen, and ethanol intoxications, characterized by decreased intracellular SAM. Positive therapeutic effects of SAM/vitamin E or SAM/ursodeoxycholic acid in animal models with NAFLD and intrahepatic cholestasis were not confirmed in humans. In in vitro experiments, SAM and betaine potentiate PegIFN-alpha-2a/2b plus ribavirin antiviral effects. SAM plus betaine improves early viral kinetics and increases interferon-stimulated gene expression in patients with viral hepatitis non-responders to pegIFNα/ribavirin. SAM prevents hepatic cirrhosis, induced by CCl4, inhibits experimental tumors growth and is proapoptotic for hepatocellular carcinoma and MCF-7 breast cancer cells. SAM plus Decitabine arrest cancer growth and potentiate doxorubicin effects on breast, head, and neck cancers. Furthermore, SAM enhances the antitumor effect of gemcitabine against pancreatic cancer cells, inhibits growth of human prostate cancer PC-3, colorectal cancer, and osteosarcoma LM-7 and MG-63 cell lines; increases genomic stability of SW480 cells. SAM reduces colorectal cancer progression and inhibits the proliferation of preneoplastic rat liver cells in vivo. The discrepancy between positive results of SAM treatment of experimental tumors and modest effects against human disease may depend on more advanced human disease stage at moment of diagnosis.

TAZ is indispensable for c-MYC-induced hepatocarcinogenesis

BACKGROUND & AIMS

Mounting evidence implicates the Hippo downstream effectors Yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ) in hepatocellular carcinoma (HCC). We investigated the functional contribution of YAP and/or TAZ to c-MYC-induced liver tumor development.

METHODS

The requirement for YAP and/or TAZ in c-Myc-driven hepatocarcinogenesis was analyzed using conditional Yap, Taz, and Yap;Taz knockout (KO) mice. An hepatocyte-specific inducible TTR-CreER^T2 KO system was applied to evaluate the role of YAP and TAZ during tumor progression. Expression patterns of YAP, TAZ, c-MYC, and BCL2L12 were analyzed in human HCC samples.

RESULTS

We found that the Hippo cascade is inactivated in c-Myc-induced mouse HCC. Intriguingly, TAZ mRNA levels and activation status correlated with c-MYC activity in human and mouse HCC, but YAP mRNA levels did not. We demonstrated that TAZ is a direct transcriptional target of c-MYC. In c-Myc induced murine HCCs, ablation of Taz, but not Yap, completely prevented tumor development. Mechanistically, TAZ was required to avoid c-Myc-induced hepatocyte apoptosis during tumor initiation. The anti-apoptotic BCL2L12 gene was identified as a novel target regulated specifically by YAP/TAZ, whose silencing strongly suppressed c-Myc-driven murine hepatocarcinogenesis. In c-Myc murine HCC lesions, conditional knockout of Taz, but not Yap, led to tumor regression, supporting the requirement of TAZ for c-Myc-driven HCC progression.

CONCLUSIONS

TAZ is a pivotal player at the crossroad between the c-MYC and Hippo pathways in HCC. Targeting TAZ might be beneficial for the treatment of patients with HCC and c-MYC activation.

LAY SUMMARY

The identification of novel treatment targets and approaches for patients with hepatocellular carcinoma is crucial to improve survival outcomes. We identified TAZ as a transcriptional target of c-MYC which plays a critical role in c-MYC-dependent hepatocarcinogenesis. TAZ could potentially be targeted for the treatment of patients with c-MYC-driven hepatocellular carcinoma.

RASSF1A independence and early galectin-1 upregulation in PIK3CA-induced hepatocarcinogenesis: new therapeutic venues

Aberrant activation of the phosphoinositide 3‐kinase (PI3K)/AKT/mTOR and Ras/mitogen‐activated protein kinase (MAPK) pathways is a hallmark of hepatocarcinogenesis. In a subset of hepatocellular carcinomas (HCCs), PI3K/AKT/mTOR signaling dysregulation depends on phosphatidylinositol‐4,5‐bisphosphate 3‐kinase, catalytic subunit alpha (PIK3CA) mutations, while RAS/MAPK activation is partly attributed to promoter methylation of the tumor suppressor Ras association domain‐containing protein 1 (RASSF1A). To evaluate a possible cocarcinogenic effect of PIK3CA activation and RASSF1A knockout, plasmids expressing oncogenic forms of PIK3CA (E545K or H1047R mutants) were delivered to the liver of RASSF1A knockout and wild‐type mice by hydrodynamic tail vein injection combined with sleeping beauty‐mediated somatic integration. Transfection of either PIK3CA E545K or H1047R mutants sufficed to induce HCCs in mice irrespective of RASSF1A mutational background. The related tumors displayed a lipogenic phenotype with upregulation of fatty acid synthase and stearoyl‐CoA desaturase‐1 (SCD1). Galectin‐1, which was commonly upregulated in preneoplastic lesions and tumors, emerged as a regulator of SCD1. Co‐inhibitory treatment with PIK3CA inhibitors and the galectin‐1 inhibitor OTX008 resulted in synergistic cytotoxicity in human HCC cell lines, suggesting novel therapeutic venues.

Cabozantinib for HCC Treatment, From Clinical Back to Experimental Models

Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer-related mortality worldwide. Patients with early-stage HCC can be treated successfully with surgical resection or liver transplantation. However, the usual late diagnosis of HCC precludes curative treatments, and systemic therapies are the only viable option for inoperable patients. Sorafenib, an orally available multikinase inhibitor, is a systemic therapy approved for treating patients with advanced HCC yet providing limited benefits. Consequently, new drugs have been developed to overcome sorafenib resistance and improve patients' prognoses. A new promising strategy is using c-MET inhibitors, such as cabozantinib, as activation of c-MET occurs in up to 40% of HCC patients. In particular, cabozantinib, in combination with the checkpoint inhibitor atezolizumab, is currently in phase 3 clinical trial for HCC, and the results are eagerly awaited. Herein, we summarize and review the drugs approved for the treatment of advanced HCC, mainly focusing on the clinical and preclinical efficacy evaluation of cabozantinib. Also, we report the available preclinical data on cabozantinib-based combination therapies for HCC, current obstacles for cabozantinib therapy, and the future directions for cabozantinib-based treatment for HCC.

Repeated exposure of the oral mucosa over 12 months with cold plasma is not carcinogenic in mice

Peri-implantitis may result in the loss of dental implants. Cold atmospheric pressure plasma (CAP) was suggested to promote re-osseointegration, decrease antimicrobial burden, and support wound healing. However, the long-term risk assessment of CAP treatment in the oral cavity has not been addressed. Treatment with two different CAP devices was compared against UV radiation, carcinogen administration, and untreated conditions over 12 months. Histological analysis of 406 animals revealed that repeated CAP exposure did not foster non-invasive lesions or squamous cell carcinoma (SCCs). Carcinogen administration promoted non-invasive lesions and SCCs. Molecular analysis by a qPCR screening of 144 transcripts revealed distinct inflammatory profiles associated with each treatment regimen. Interestingly, CAP treatment of carcinogen-challenged mucosa did not promote but instead left unchanged or reduced the proportion of non-invasive lesions and SCC formation. In conclusion, repeated CAP exposure of murine oral mucosa was well tolerated, and carcinogenic effects did not occur, motivating CAP applications in patients for dental and implant treatments in the future.

Hormonally Induced Hepatocellular Carcinoma in Diabetic Wild Type and Carbohydrate Responsive Element Binding Protein Knockout Mice

OBJECTIVE

In the rat, the pancreatic islet transplantation model is an established method to induce hepatocellular carcinomas (HCC), due to insulin-mediated metabolic and molecular alterations like increased glycolysis and de novo lipogenesis and the oncogenic AKT/mTOR pathway including upregulation of the transcription factor Carbohydrate-response element-binding protein (ChREBP). ChREBP could therefore represent an essential oncogenic co-factor during hormonally induced hepatocarcinogenesis.

METHODS

Pancreatic islet transplantation was implemented in diabetic C57Bl/6J (wild type, WT) and ChREBP-knockout (KO) mice for 6 and 12 months. Liver tissue was examined using histology, immunohistochemistry, electron microscopy and Western blot analysis. Finally, we performed NGS-based transcriptome analysis between WT and KO liver tumor tissues.

RESULTS

Three hepatocellular carcinomas were detectable after 6 and 12 months in diabetic transplanted WT mice, but only one in a KO mouse after 12 months. Pre-neoplastic clear cell foci (CCF) were also present in liver acini downstream of the islets in WT and KO mice. In KO tumors, glycolysis, de novo lipogenesis and AKT/mTOR signalling were strongly downregulated compared to WT lesions. Extrafocal liver tissue of diabetic, transplanted KO mice revealed less glycogen storage and proliferative activity than WT mice. From transcriptome analysis, we identified a set of transcripts pertaining to metabolic, oncogenic and immunogenic pathways that are differentially expressed between tumors of WT and KO mice. Of 315 metabolism-associated genes, we observed 199 genes that displayed upregulation in the tumor of WT mice, whereas 116 transcripts showed their downregulated expression in KO mice tumor.

CONCLUSIONS

The pancreatic islet transplantation model is a suitable method to study hormonally induced hepatocarcinogenesis also in mice, allowing combination with gene knockout models. Our data indicate that deletion of ChREBP delays insulin-induced hepatocarcinogenesis, suggesting a combined oncogenic and lipogenic function of ChREBP along AKT/mTOR-mediated proliferation of hepatocytes and induction of hepatocellular carcinoma.

Alpelisib combination treatment as novel targeted therapy against hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the sixth most common primary cancer with an unsatisfactory long-term survival. Gain of function mutations of PIK3CA occur in a subset of human HCC. Alpelisib, a selective PIK3CA inhibitor, has been approved by the FDA to treat PIK3CA mutant breast cancers. In this manuscript, we evaluated the therapeutic efficacy of alpelisib, either alone or in combination, for the treatment of HCC. We tested alpelisib in mouse HCC induced by hydrodynamic injection of c-Met/PIK3CA(H1047R) (c-Met/H1047R), c-Met/PIK3CA(E545K) (c-Met/E545K), and c-Met/sgPten gene combinations. Alpelisib slowed down the growth of c-Met/H1047R and c-Met/E545K HCC but was ineffective in c-Met/sgPten HCC. Mechanistically, alpelisib inhibited p-ERK and p-AKT in c-Met/H1047R and c-Met/E545K HCC progression but did not affect the mTOR pathway or genes involved in cell proliferation. In human HCC cell lines transfected with PIK3CA(H1047R), alpelisib synergized with the mTOR inhibitor MLN0128 or the CDK4/6 inhibitor palbociclib to suppress HCC cell growth. In c-Met/H1047R mice, alpelisib/MLN0128 or alpelisib/palbociclib combination therapy caused tumor regression. Our study demonstrates that alpelisib is effective for treating PIK3CA-mutated HCC by inhibiting MAPK and AKT cascades. Furthermore, combining alpelisib with mTOR or CDK4/6 inhibitors has a synergistic efficacy against PIK3CA-mutated HCC, providing novel opportunities for precision medicine against HCC.

Focal adhesion kinase (FAK) promotes cholangiocarcinoma development and progression via YAP activation

BACKGROUND & AIMS

Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase that is upregulated in many tumor types and is a promising target for cancer therapy. Herein, we elucidated the functional role of FAK in intrahepatic cholangiocarcinoma (iCCA) development and progression.

METHODS

Expression levels and activation status of FAK were determined in human iCCA samples. The functional contribution of FAK to Akt/YAP murine iCCA initiation and progression was investigated using conditional Fak knockout mice and constitutive Cre or inducible Cre mice, respectively. The oncogenic potential of FAK was further examined via overexpression of FAK in mice. In vitro cell line studies and in vivo drug treatment were applied to address the therapeutic potential of targeting FAK for iCCA treatment.

RESULTS

FAK was ubiquitously upregulated and activated in iCCA lesions. Ablation of FAK strongly delayed Akt/YAP-driven mouse iCCA initiation. FAK overexpression synergized with activated AKT to promote iCCA development and accelerated Akt/Jag1-driven cholangiocarcinogenesis. Mechanistically, FAK was required for YAP(Y357) phosphorylation, supporting the role of FAK as a central YAP regulator in iCCA. Significantly, ablation of FAK after Akt/YAP-dependent iCCA formation strongly suppressed tumor progression in mice. Furthermore, a remarkable iCCA growth reduction was achieved when a FAK inhibitor and palbociclib, a CDK4/6 inhibitor, were administered simultaneously in human iCCA cell lines and Akt/YAP mice.

CONCLUSIONS

FAK activation contributes to the initiation and progression of iCCA by inducing the YAP proto-oncogene. Targeting FAK, either alone or in combination with anti-CDK4/6 inhibitors, may be an effective strategy for iCCA treatment.

LAY SUMMARY

We found that the protein FAK (focal adhesion kinase) is upregulated and activated in human and mouse intrahepatic cholangiocarcinoma samples. FAK promotes intrahepatic cholangiocarcinoma development, whereas deletion of FAK strongly suppresses its initiation and progression. Combined FAK and CDK4/6 inhibitor treatment had a strong anti-cancer effect in in vitro and in vivo models. This combination therapy might represent a valuable and novel treatment against human intrahepatic cholangiocarcinoma.

Hepatocellular carcinoma (HCC): the most promising therapeutic targets in the preclinical arena based on tumor biology characteristics

INTRODUCTION

: Hepatocellular carcinoma (HCC) is a malignant liver tumor characterized by high molecular heterogeneity, which has hampered the development of effective targeted therapies severely. Recent experimental data have unraveled novel promising targets for HCC treatment.

AREAS COVERED

: Eligible articles were retrieved from PubMed and Web of Science databases up to July 2021. This review summarizes the established targeted therapies for advanced HCC, focusing on the strategies to overcome drug resistance and the search for combinational treatments. In addition, conventional biomarkers holding the promises for HCC treatments and novel therapeutic targets from the research field are discussed.

EXPERT OPINION

: HCC is a molecularly complex disease, with several and distinct pathways playing critical roles in different tumor subtypes. Experimental models recapitulating the features of each tumor subset would be highly beneficial to design novel and more effective therapies against this disease. Furthermore, a deeper understanding of combinatorial drug synergism and the role of the tumor microenvironment in HCC will lead to improved therapeutic outcomes.

Cabozantinib-based combination therapy for the treatment of hepatocellular carcinoma

OBJECTIVE

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer with limited treatment options. Cabozantinib, an orally bioavailable multikinase inhibitor is now approved by Food and Drug Administration (FDA) for HCC patients. We evaluated the therapeutic efficacy of cabozantinib, either alone or in combination, in vitro and in vivo.

DESIGN

Human HCC cell lines and HCC mouse models were used to assess the therapeutic efficacy and targeted molecular pathways of cabozantinib, either alone or in combination with the pan-mTOR inhibitor MLN0128 or the checkpoint inhibitor anti-PD-L1 antibody.

RESULTS

Cabozantinib treatment led to stable disease in c-Met/β-catenin and Akt/c-Met mouse HCC while possessing limited efficacy on Akt/Ras and c-Myc liver tumours. Importantly, cabozantinib effectively inhibited c-MET and ERK activity, leading to decreased PKM2 and increased p21 expression in HCC cells and in c-Met/β-catenin and Akt/c-Met HCC. However, cabozantinib was ineffective in inhibiting the Akt/mTOR cascade. Intriguingly, a strong inhibition of angiogenesis by cabozantinib occurred regardless of the oncogenic drivers. However, cabozantinib had limited impact on other tumour microenvironment parameters, including tumour infiltrating T cells, and did not induce programmed death-ligand 1 (PD-L1) expression. Combining cabozantinib with MLN0128 led to tumour regression in c-Met/β-catenin mice. In contrast, combined treatment with cabozantinib and the checkpoint inhibitor anti-PD-L1 antibody did not provide any additional therapeutic benefit in the four mouse HCC models tested.

CONCLUSION

c-MET/ERK/p21/PKM2 cascade and VEGFR2-induced angiogenesis are the primary targets of cabozantinib in HCC treatment. Combination therapies with cabozantinib and mTOR inhibitors may be effective against human HCC.

FOSL1 promotes cholangiocarcinoma via transcriptional effectors that could be therapeutically targeted

BACKGROUND & AIMS

Cholangiocarcinoma (CCA) is a neoplasia of the biliary tract driven by genetic, epigenetic and transcriptional mechanisms. Herein, we investigated the role of the transcription factor FOSL1, as well as its downstream transcriptional effectors, in the development and progression of CCA.

METHODS

FOSL1 was investigated in human CCA clinical samples. Genetic inhibition of FOSL1 in human and mouse CCA cell lines was performed in in vitro and in vivo models using constitutive and inducible short-hairpin RNAs. Conditional FOSL1 ablation was done using a genetically engineered mouse (GEM) model of CCA (mutant KRAS and Trp53 knockout). Follow-up RNA and chromatin immunoprecipitation (ChIP) sequencing analyses were carried out and downstream targets were validated using genetic and pharmacological inhibition.

RESULTS

An inter-species analysis of FOSL1 in CCA was conducted. First, FOSL1 was found to be highly upregulated in human and mouse CCA, and associated with poor patient survival. Pharmacological inhibition of different signalling pathways in CCA cells converged on the regulation of FOSL1 expression. Functional experiments showed that FOSL1 is required for cell proliferation and cell cycle progression in vitro, and for tumour growth and tumour maintenance in both orthotopic and subcutaneous xenograft models. Likewise, FOSL1 genetic abrogation in a GEM model of CCA extended mouse survival by decreasing the oncogenic potential of transformed cholangiocytes. RNA and ChIP sequencing studies identified direct and indirect transcriptional effectors such as HMGCS1 and AURKA, whose genetic and pharmacological inhibition phenocopied FOSL1 loss.

CONCLUSIONS

Our data illustrate the functional and clinical relevance of FOSL1 in CCA and unveil potential targets amenable to pharmacological inhibition that could enable the implementation of novel therapeutic strategies.

LAY SUMMARY

Understanding the molecular mechanisms involved in cholangiocarcinoma (bile duct cancer) development and progression stands as a critical step for the development of novel therapies. Through an inter-species approach, this study provides evidence of the clinical and functional role of the transcription factor FOSL1 in cholangiocarcinoma. Moreover, we report that downstream effectors of FOSL1 are susceptible to pharmacological inhibition, thus providing new opportunities for therapeutic intervention.

TBX3 functions as a tumor suppressor downstream of activated CTNNB1 mutants during hepatocarcinogenesis

BACKGROUND & AIMS

Gain of function (GOF) mutations in the CTNNB1 gene are one of the most frequent genetic events in hepatocellular carcinoma (HCC). T-box transcription factor 3 (TBX3) is a liver-specific target of the Wnt/β-catenin pathway and thought to be an oncogene mediating activated β-catenin-driven HCC formation.

METHODS

We evaluated the expression pattern of TBX3 in human HCC specimens. Tbx3 was conditionally knocked out in murine HCC models by hydrodynamic tail vein injection of Cre together with c-Met and ΔN90-β-catenin (c-Met/β-catenin) in Tbx3^flox/flox mice. TBX3 was overexpressed in human HCC cell lines to investigate the functions of TBX3 in vitro.

RESULTS

A bimodal expression pattern of TBX3 in human HCC samples was detected: high expression of TBX3 in GOF CTNNB1 HCC and downregulation of TBX3 in non-CTNNB1 mutant tumors. High expression of TBX3 was associated with increased differentiation and decreased expression signatures of tumor growth. Using Tbx3^flox/flox mice, we found that ablation of Tbx3 significantly accelerates c-Met/β-catenin-driven HCC formation. Moreover, Tbx3(-) HCC demonstrated increased YAP/TAZ activity. The accelerated tumor growth induced by loss of TBX3 in c-Met/β-catenin mouse HCC was successfully prevented by overexpression of LATS2, which inhibited YAP/TAZ activity. In human HCC cell lines, overexpression of TBX3 inhibited HCC cell growth as well as YAP/TAZ activation. A negative correlation between TBX3 and YAP/TAZ target genes was observed in human HCC samples. Mechanistically, phospholipase D1 (PLD1), a known positive regulator of YAP/TAZ, was identified as a novel transcriptional target repressed by TBX3.

CONCLUSION

Our study suggests that TBX3 is induced by GOF CTNNB1 mutants and suppresses HCC growth by inactivating PLD1, thus leading to the inhibition of YAP/TAZ oncogenes.

LAY SUMMARY

TBX3 is a liver-specific target of the Wnt/β-catenin pathway and thought to be an oncogene in promoting liver cancer development. Herein, we demonstrate that TBX3 is in fact a tumor suppressor gene that restricts liver tumor growth. Strategies which increase TBX3 expression and/or activities may be effective for HCC treatment.

Overexpression of Mothers Against Decapentaplegic Homolog 7 Activates the Yes-Associated Protein/NOTCH Cascade and Promotes Liver Carcinogenesis in Mice and Humans

BACKGROUND AND AIMS

Mothers against decapentaplegic homolog (SMAD) 7 is an antagonist of TGF-β signaling. In the present investigation, we sought to determine the relevance of SMAD7 in liver carcinogenesis using in vitro and in vivo approaches.

APPROACH AND RESULTS

We found that SMAD7 is up-regulated in a subset of human HCC samples with poor prognosis. Gene set enrichment analysis revealed that SMAD7 expression correlates with activated yes-associated protein (YAP)/NOTCH pathway and cholangiocellular signature genes in HCCs. These findings were substantiated in human HCC cell lines. In vivo, overexpression of Smad7 alone was unable to initiate HCC development, but it significantly accelerated c-Myc/myeloid cell leukemia 1 (MCL1)-induced mouse HCC formation. Consistent with human HCC data, c-Myc/MCL1/Smad7 liver tumors exhibited an increased cholangiocellular gene expression along with Yap/Notch activation and epithelial-mesenchymal transition (EMT). Intriguingly, blocking of the Notch signaling did not affect c-Myc/MCL1/Smad7-induced hepatocarcinogenesis while preventing cholangiocellular signature expression and EMT, whereas ablation of Yap abolished c-Myc/MCL1/Smad7-driven HCC formation. In mice overexpressing a myristoylated/activated form of AKT, coexpression of SMAD7 accelerated carcinogenesis and switched the phenotype from HCC to intrahepatic cholangiocarcinoma (iCCA) lesions. In human iCCA, SMAD7 expression was robustly up-regulated, especially in the most aggressive tumors, and directly correlated with the levels of YAP/NOTCH targets as well as cholangiocellular and EMT markers.

CONCLUSIONS

The present data indicate that SMAD7 contributes to liver carcinogenesis by activating the YAP/NOTCH signaling cascade and inducing a cholangiocellular and EMT signature.

Fascin1 empowers YAP mechanotransduction and promotes cholangiocarcinoma development

Mechanical forces control cell behavior, including cancer progression. Cells sense forces through actomyosin to activate YAP. However, the regulators of F-actin dynamics playing relevant roles during mechanostransduction in vitro and in vivo remain poorly characterized. Here we identify the Fascin1 F-actin bundling protein as a factor that sustains YAP activation in response to ECM mechanical cues. This is conserved in the mouse liver, where Fascin1 regulates YAP-dependent phenotypes, and in human cholangiocarcinoma cell lines. Moreover, this is relevant for liver tumorigenesis, because Fascin1 is required in the AKT/NICD cholangiocarcinogenesis model and it is sufficient, together with AKT, to induce cholangiocellular lesions in mice, recapitulating genetic YAP requirements. In support of these findings, Fascin1 expression in human intrahepatic cholangiocarcinomas strongly correlates with poor patient prognosis. We propose that Fascin1 represents a pro-oncogenic mechanism that can be exploited during intrahepatic cholangiocarcinoma development to overcome a mechanical tumor-suppressive environment.

YAP Accelerates Notch-Driven Cholangiocarcinogenesis via mTORC1 in Mice

Intrahepatic cholangiocarcinoma (iCCA) is a lethal malignant neoplasm with limited therapeutic options. Previous studies have found that Notch1 overexpression alone suffices to induce iCCA in the mouse, albeit after long latency. The current study found that activation of the Yes-associated protein (Yap) proto-oncogene occurs during Notch1-driven iCCA progression. After co-expressing activated Notch1 intracellular domain (Nicd) and Yap (YapS127A) in the mouse liver, rapid iCCA formation and progression occurred in Nicd/Yap mice. Mechanistically, an increased expression of amino acid transporters and activation of the mammalian target of rapamycin complex 1 (mTORC1) signaling pathway was detected in Nicd/Yap mouse liver tumors. Significantly, the genetic deletion of Raptor, the major mTORC1 component, completely suppressed iCCA development in Nicd/Yap mice. Elevated expression of Notch1, YAP, amino acid transporters, and members of the mTORC1 pathway was also detected ubiquitously in a collection of human iCCA specimens. Their levels were associated with a poor patient outcome. This study demonstrates that Notch and YAP concomitant activation is frequent in human cholangiocarcinogenesis. Notch and YAP synergize to promote iCCA formation by activating the mTORC1 pathway.

Current challenges to underpinning the genetic basis for cholangiocarcinoma

AREAS COVERED

This review provides an overview regarding the current scenario and knowledge of the CCA genomic landscape and the potentially actionable molecular aberrations in each CCA subtype.

EXPERT OPINION

The establishment and advances of high-throughput methodologies applied to genetic and epigenetic profiling are changing many cancer types' therapeutic landscape , including CCA.The large body of data generated must be interpreted appropriately and eventually implemented in clinical practice. The following advancements toward precision medicine in CCA management will require designing better clinical trials with improved methods to stratify biliary tumor patients.

Identification and In-Depth Analysis of the Novel FGFR2-NDC80 Fusion in a Cholangiocarcinoma Patient: Implication for Therapy

Fibroblast growth factor receptor 2 (FGFR2) fusions have emerged as a new therapeutic target for cholangiocarcinoma in clinical practice following the United States Food and Drug Administration (FDA) approval of Pemigatinib in May 2020. FGFR2 fusions can result in a ligand-independent constitutive activation of FGFR2 signaling with a downstream activation of multiple pathways, including the mitogen-activated protein (MAPK) cascade. Until today, only a limited number of fusion partners have been reported, of which the most prevalent is BicC Family RNA Binding Protein (BICC1), representing one-third of all detected FGFR2 fusions. Nonetheless, in the majority of cases rare or yet unreported fusion partners are discovered in next-generation sequencing panels, which confronts clinicians with a challenging decision: Should a therapy be based on these variants or should the course of treatment follow the (limited) standard regime? Here, we present the case of a metastasized intrahepatic cholangiocarcinoma harboring a novel FGFR2-NDC80 fusion, which was discussed in our molecular tumor board. The protein NDC80 kinetochore complex component (NDC80) is an integral part of the outer kinetochore, which is involved in microtubule binding and spindle assembly. For additional therapeutic guidance, an immunohistochemical analysis of the predicted fusion and downstream effector proteins was performed and compared to cholangiocarcinoma samples of a tissue microarray. The FGFR2-NDC80 fusion resulted in strong activation of the FGFR2 signaling pathway. These supporting results led to a treatment recommendation of Pemigatinib. Unfortunately, the patient passed away before the commencement of therapy.

Distinct functions of transforming growth factor-β signaling in c-MYC driven hepatocellular carcinoma initiation and progression

Dysregulation of transforming growth factor-beta (TGFβ) signaling has been implicated in liver carcinogenesis with both tumor promoting and inhibiting activities. Activation of the c-MYC protooncogene is another critical genetic event in hepatocellular carcinoma (HCC). However, the precise functional crosstalk between c-MYC and TGFβ signaling pathways remains unclear. In the present investigation, we investigated the expression of TGFβ signaling in c-MYC amplified human HCC samples as well as the mechanisms whereby TGFβ modulates c-Myc driven hepatocarcinogenesis during initiation and progression. We found that several TGFβ target genes are overexpressed in human HCCs with c-MYC amplification. In vivo, activation of TGFβ1 impaired c-Myc murine HCC initiation, whereas inhibition of TGFβ pathway accelerated this process. In contrast, overexpression of TGFβ1 enhanced c-Myc HCC progression by promoting tumor cell metastasis. Mechanistically, activation of TGFβ promoted tumor microenvironment reprogramming rather than inducing epithelial-to-mesenchymal transition during HCC progression. Moreover, we identified PMEPA1 as a potential TGFβ1 target. Altogether, our data underline the divergent roles of TGFβ signaling during c-MYC induced HCC initiation and progression.

Loss of Apc Cooperates with Activated Oncogenes to Induce Liver Tumor Formation in Mice

Hepatocellular carcinoma (HCC) and hepatoblastoma are the major types of primary liver cancer in adulthood and childhood, respectively. Wnt/β-catenin signaling deregulation is one of the most frequent genetic events in hepatocarcinogenesis. APC regulator of WNT signaling pathway (APC) encodes an inhibitor of the Wnt cascade and acts as a tumor suppressor. Germline defects of the APC gene lead to familial adenomatous polyposis, and its somatic mutations occur in multiple tumor types. However, the contribution of APC in hepatocarcinogenesis remains unclear. Therefore, APC mutations and expression patterns were examined in human HCC and hepatoblastoma samples. Whether loss of Apc alone or in cooperation with other oncogenes triggers liver tumor development in vivo was also investigated. sgApc alone could not drive liver tumor formation, but synergized with activated oncogenes (YapS127A, TazS89A, and c-Met) to induce hepatocarcinogenesis. Mechanistically, Apc deletion induced the activation of β-catenin and its downstream targets in mouse liver tumors. Furthermore, Ctnnb1 ablation or TCF4-mediated transcription blockade completely prevented liver tumor formation, indicating the requirement of a functional β-catenin pathway for loss of Apc-driven hepatocarcinogenesis. This study shows that a subset of HCC patients with loss-of-function APC mutations might benefit from therapeutic strategies targeting the Wnt/β-catenin pathway.

Autopsy findings after long-term treatment of COVID-19 patients with microbiological correlation

Between April and June 2020, i.e., during the first wave of pandemic coronavirus disease 2019 (COVID-19), 55 patients underwent long-term treatment in the intensive care unit at the University Hospital of Regensburg. Most of them were transferred from smaller hospitals, often due to the need for an extracorporeal membrane oxygenation system. Autopsy was performed in 8/17 COVID-19-proven patients after long-term treatment (mean: 33.6 days). Autopsy revealed that the typical pathological changes occurring during the early stages of the disease (e.g., thrombosis, endothelitis, capillaritis) are less prevalent at this stage, while severe diffuse alveolar damage and especially coinfection with different fungal species were the most conspicuous finding. In addition, signs of macrophage activation syndrome was detected in 7 of 8 patients. Thus, fungal infections were a leading cause of death in our cohort of severely ill patients and may alter clinical management of patients, particularly in long-term periods of treatment.