Myofibroblast-derived PDGF-BB promotes Hedgehog survival signaling in cholangiocarcinoma cells

Heterogeneity, crosstalk, and targeting of cancer-associated fibroblasts in cholangiocarcinoma

Cholangiocarcinoma (CCA) comprises diverse tumors of the biliary tree and is characterized by late diagnosis, short-term survival, and chemoresistance. CCAs are mainly classified according to their anatomical location and include diverse molecular subclasses harboring inter-tumoral and intratumoral heterogeneity. Besides the tumor cell component, CCA is also characterized by a complex and dynamic tumor microenvironment where tumor cells and stromal cells crosstalk in an intricate network of interactions. Cancer-associated fibroblasts, one of the most abundant cell types in the tumor stroma of CCA, are actively involved in cholangiocarcinogenesis by participating in multiple aspects of the disease including extracellular matrix remodeling, immunomodulation, neo-angiogenesis, and metastasis. Despite their overall tumor-promoting role, recent evidence indicates the presence of transcriptional and functional heterogeneous CAF subtypes with tumor-promoting and tumor-restricting properties. To elucidate the complexity and potentials of cancer-associated fibroblasts as therapeutic targets in CCA, this review will discuss the origin of cancer-associated fibroblasts, their heterogeneity, crosstalk, and role during tumorigenesis, providing an overall picture of the present and future perspectives toward cancer-associated fibroblasts targeting CCA.

Cancer-Associated Fibroblasts Promote Lymphatic Metastasis in Cholangiocarcinoma via the PDGF-BB/PDGFR-β Mediated Paracrine Signaling Network

Patients with cholangiocarcinoma (CCA) with lymph node metastasis (LNM) have the worst prognosis, even after complete resection; however, the underlying mechanism remains unclear. Here, we established CAF-derived PDGF-BB as a regulator of LMN in CCA. Proteomics analysis revealed upregulation of PDGF-BB in CAFs derived from patients with CCA with LMN (LN+CAFs). Clinically, the expression of CAF-PDGF-BB correlated with poor prognosis and increased LMN in patients with CCA, while CAF-secreted PDGF-BB enhanced lymphatic endothelial cell (LEC)-mediated lymphangiogenesis and promoted the trans-LEC migration ability of tumor cells. Co-injection of LN+CAFs and cancer cells increased tumor growth and LMN in vivo. Mechanistically, CAF-derived PDGF-BB activated its receptor PDGFR-β and its downstream ERK1/2-JNK signaling pathways in LECs to promote lymphoangiogenesis, while it also upregulated the PDGFR-β-GSK-P65-mediated tumor cell migration. Finally, targeting PDGF-BB/PDGFR-β or the GSK-P65 signaling axis prohibited CAF-mediated popliteal lymphatic metastasis (PLM) in vivo. Overall, our findings revealed that CAFs promote tumor growth and LMN via a paracrine network, identifying a promising therapeutic target for patients with advanced CCA.

The role of extracellular vesicles in cholangiocarcinoma tumor microenvironment

Cholangiocarcinoma (CCA) is a highly aggressive malignant tumor that originates from the biliary system. With restricted treatment options at hand, the challenging aspect of early CCA diagnosis leads to a bleak prognosis. Besides the intrinsic characteristics of tumor cells, the generation and progression of CCA are profoundly influenced by the tumor microenvironment, which engages in intricate interactions with cholangiocarcinoma cells. Of notable significance is the role of extracellular vesicles as key carriers in enabling communication between cancer cells and the tumor microenvironment. This review aims to provide a comprehensive overview of current research examining the interplay between extracellular vesicles and the tumor microenvironment in the context of CCA. Specifically, we will emphasize the significant contributions of extracellular vesicles in molding the CCA microenvironment and explore their potential applications in the diagnosis, prognosis assessment, and therapeutic strategies for this aggressive malignancy.

The Tumor Immune Microenvironment plays a Key Role in Driving the Progression of Cholangiocarcinoma

Cholangiocarcinoma (CCA) is an epithelial cancer distinguished by bile duct cell differentiation and is also a fibroproliferative tumor. It is characterized by a dense mesenchyme and a complex tumor immune microenvironment (TME). The TME comprises both cellular and non-cellular components. The celluar component includes CCA cells, immune cells and mesenchymal cells represented by the cancer-associated fibroblasts (CAFs), while the non-cellular component is represented by mesenchymal elements such as the extracellular matrix (ECM). Recent studies have demonstrated the important role of the TME in the development, progression, and treatment resistance of CCA. These cell-associated prognostic markers as well as intercellular connections, may serve as potential therapeutic targets and could inspire new treatment approaches for CCA in the future. This paper aims to summarize the current understanding of CCA's immune microenvironment, focusing on immune cells, mesenchymal cells, ECM, intercellular interactions, and metabolism within the microenvironment.

Identification of the function of FOSB in cholangiocarcinoma using bioinformatics analysis

Background

Exploring the potential mechanism of cholangiocarcinoma (CCA) metabolic reprogramming is significant for guiding clinical treatment. However, related research and exploration are still lacking. Therefore, we aimed to identify a reliable metabolism-related gene or biomarker of CCA using bioinformatics analysis.

Methods

The GSE26566, GSE45001, and GSE132305 datasets were obtained from the Gene Expression Omnibus (GEO) database. Differently expressed genes (DEGs) between CCA tissues and adjacent tissues were screened out. The key gene was identified through enrichment and functional analysis, and its immune and clinical correlation was investigated utilizing the Tumor Immune Evaluation Resource (TIMER2.0), the Tumor-Immune System Interactions Database (TISIDB), the Gene Expression Profiling Interactive Analysis (GEPIA2), and the Kaplan-Meier Plotter. Finally, immunohistochemistry (IHC) was performed to validate the results.

Results

By analysis, the expression of FBJ murine osteosarcoma viral oncogene homolog B (FOSB) was significantly downregulated in CCA tissues when compared with adjacent tissues. Moreover, the expression levels of FOSB positively correlated with tumor-infiltrating immune cells in most tumors, and patients with high FOSB expression tended to have a better prognosis. The FOSB and SIRT3/HIF1A axes have similar expression trends and metabolic functions in CCA cells, and the correlation between of them was preliminarily explored by IHC experiments.

Conclusions

The expression levels of FOSB are closely related to the prognosis of CCA patients, which may be a predictive indicator for prognosis and immunotherapy.

Tumor immune microenvironment and the current immunotherapy of cholangiocarcinoma (Review)

Cholangiocarcinoma (CCA) is a highly heterogeneous malignancy originating from the epithelial system of the bile ducts, and its incidence in recent years is steadily increasing. The immune microenvironment of CCA is characterized by diversity and complexity, with a substantial presence of cancer‑associated fibroblasts and immune cell infiltration, which plays a key role in regulating the distinctive biological behavior of cholangiocarcinoma, including tumor growth, angiogenesis, lymphangiogenesis, invasion and metastasis. Despite the notable success of immunotherapy in the treatment of solid tumors in recent years, patients with CCA have responded poorly to immune checkpoint inhibitor therapy. The interaction of tumor cells with cellular components of the immune microenvironment can regulate the activity and function of immune cells and form an immunosuppressive microenvironment, which may cause ineffective immunotherapy. Therefore, the components of the tumor immune microenvironment appear to be novel targets for immune therapies. Combination therapy focusing on immune checkpoint inhibitors is a promising and valuable first‑line or translational treatment approach for intractable biliary tract malignancies. The present review discusses the compositional characteristics and regulatory factors of the CCA immune microenvironment and the possible immune escape mechanisms. In addition, a summary of the advances in immunotherapy for CCA is also provided. It is hoped that the present review may function as a valuable reference for the development of novel immunotherapeutic strategies for CCA.

A Novel Trojan Horse Nanotherapy Strategy Targeting the cPKM-STMN1/TGFB1 Axis for Effective Treatment of Intrahepatic Cholangiocarcinoma

Intrahepatic cholangiocarcinoma (ICC) is characterized by its dense fibrotic microenvironment and highly malignant nature, which are associated with chemotherapy resistance and very poor prognosis. Although circRNAs have emerged as important regulators in cancer biology, their role in ICC remains largely unclear. Herein, a circular RNA, cPKM is identified, which is upregulated in ICC and associated with poor prognosis. Silencing cPKM in ICC cells reduces TGFB1 release and stromal fibrosis, inhibits STMN1 expression, and suppresses ICC growth and metastasis, moreover, it also leads to overcoming paclitaxel resistance. This is regulated by the interactions of cPKM with miR-199a-5p or IGF2BP2 and by the ability of cPKM to stabilize STMN1/TGFB1 mRNA. Based on these findings, a Trojan horse nanotherapy strategy with co-loading of siRNA against cPKM (si-cPKM) and paclitaxel (PTX) is developed. The siRNA/PTX co-loaded nanosystem (Trojan horse) efficiently penetrates tumor tissues, releases si-cPKM and paclitaxel (soldiers), promotes paclitaxel sensitization, and suppresses ICC proliferation and metastasis in vivo. Furthermore, it alleviates the fibrosis of ICC tumor stroma and reopens collapsed tumor vessels (opening the gates), thus enhancing the efficacy of the standard chemotherapy regimen (main force). This novel nanotherapy provides a promising new strategy for ICC treatment.

Recent Updates on Viral Oncogenesis: Available Preventive and Therapeutic Entities

Human viral oncogenesis is a complex phenomenon and a major contributor to the global cancer burden. Several recent findings revealed cellular and molecular pathways that promote the development and initiation of malignancy when viruses cause an infection. Even, antiviral treatment has become an approach to eliminate the viral infections and prevent the activation of oncogenesis. Therefore, for a better understanding, the molecular pathogenesis of various oncogenic viruses like, hepatitis virus, human immunodeficiency viral (HIV), human papillomavirus (HPV), herpes simplex virus (HSV), and Epstein-Barr virus (EBV), could be explored, especially, to expand many potent antivirals that may escalate the apoptosis of infected malignant cells while sparing normal and healthy ones. Moreover, contemporary therapies, such as engineered antibodies antiviral agents targeting signaling pathways and cell biomarkers, could inhibit viral oncogenesis. This review elaborates the recent advancements in both natural and synthetic antivirals to control viral oncogenesis. The study also highlights the challenges and future perspectives of using antivirals in viral oncogenesis.

Angiotensin receptor blockers retard the progression and fibrosis via inhibiting the viability of AGTR1+ CAFs in intrahepatic cholangiocarcinoma

BACKGROUND

Intrahepatic cholangiocarcinoma (iCCA) is a highly lethal malignancy characterized by massive fibrosis and has ineffective adjuvant therapies. Here, we demonstrate the potential of angiotensin receptor blockers (ARBs) in targeting iCCA.

METHODS

Masson's trichrome staining was used to assess the effect of ARBs in iCCA specimens, CCK8 and gel contraction assays in vitro and in xenograft models in vivo. RNA-seq and ATAC-seq were used for mechanistic investigations.

RESULTS

Patients with iCCA who were administered ARBs had a better prognosis and a lower proportion of tumour stroma, indicating alleviated fibrosis. The presence of AGTR1, the ARBs receptor, is associated with a poor prognosis of iCCA and is highly expressed in tumour tissues and cancer-associated fibroblasts (CAFs). The ARBs strongly attenuated the viability of AGTR1+ CAFs in vitro and retarded tumour progression and fibrosis in xenograft models of co-cultured CAFs and iCCA cells. Still, they did not have a significant effect on AGTR1- CAFs. Moreover, ARBs decreased the secretion of AGTR1+ CAF-derived MFAP5 via the Hippo pathway, weakened the interaction between CAFs and iCCA cells, and impaired the aggressiveness of iCCA cells by attenuating the activation of the Notch1 pathway in iCCA cells.

CONCLUSIONS

ARBs exhibit anti-fibrotic function by inhibiting the viability of AGTR1+ CAFs. These findings support using ARBs as a novel therapeutic option for targeting iCCA.

Cancer-Associated Fibroblasts in Cholangiocarcinoma: Current Knowledge and Possible Implications for Therapy

Cholangiocarcinoma (CCA) is an aggressive neoplasia with an increasing incidence and mortality. It is characterized by a strong desmoplastic stroma surrounding cancer cells. Cancer-associated fibroblasts (CAFs) are the main cell type of CCA stroma and they have an important role in modulating cancer microenvironments. CAFs originate from multiple lines of cells and mainly consist of fibroblasts and alpha-smooth muscle actin (α-SMA) positive myofibroblast-like cells. The continuous cross-talking between CCA cells and desmoplastic stroma is permitted by CAF biochemical signals, which modulate a number of pathways. Stromal cell-derived factor-1 expression increases CAF recruitment to the tumor reactive stroma and influences apoptotic pathways. The Bcl-2 family protein enhances susceptibility to CAF apoptosis and PDGFRβ induces fibroblast migration and stimulates tumor lymphangiogenesis. Many factors related to CAFs may influence CCA prognosis. For instance, a better prognosis is associated with IL-33 expression and low stromal IL-6 (whose secretion is stimulated by microRNA). In contrast, a worst prognosis is given by the expression of PDGF-D, podoplanin, SDF-1, α-SMA high expression, and periostin. The maturity phenotype has a prognostic relevance too. New therapeutic strategies involving CAFs are currently under study. Promising results are obtained with anti-PlGF therapy, nintedanib (BIBF1120), navitoclax, IPI-926, resveratrol, and controlled hyperthermia.

Combined MEK/PD-L1 Inhibition Alters Peripheral Cytokines and Lymphocyte Populations Correlating with Improved Clinical Outcomes in Advanced Biliary Tract Cancer

PURPOSE

Biliary tract cancers (BTC) are aggressive malignancies refractory to chemotherapy and immunotherapy. MEK inhibition (MEKi)-based regimens may have utility in this disease when combined with PD-L1 blockade. We hypothesize that dual MEK/PD-L1 inhibition alters circulating soluble and cellular immune mediators to improve clinical outcomes in patients with advanced BTC.

EXPERIMENTAL DESIGN

We examined immune features in peripheral blood from 77 patients with advanced BTC enrolled in a phase II clinical trial investigating atezolizumab with or without cobimetinib. Plasma and peripheral blood mononuclear cells (PBMC) were isolated from whole blood to evaluate soluble factors and immune cell populations. Baseline blood samples were additionally compared with healthy donors to identify immune signatures unique to BTC.

RESULTS

At baseline, the soluble factors platelet-derived growth factor B (PDGF)-BB, placental growth factor (PlGF)-1, IL5, and IL17A were elevated in patients with BTC compared with healthy adult donors, and higher baseline frequencies of CD8+BTLA+ T cells correlated with better overall survival (OS) in this trial. There were also significant treatment-related alterations in several factors, including decreased PDGF-BB following combination treatment, that correlated with improved OS and progression-free survival (PFS). Higher baseline levels of IL23 and RANTES corresponded to improved clinical outcomes following combination treatment. Dual MEK/PD-L1 inhibition increased populations of CD4+TIM3+ and decreased CD8+VISTA+ T cells, correlating with worse OS and better PFS, respectively.

CONCLUSIONS

This work represents a comprehensive analysis of peripheral immune features in patients with BTC and systemic responses to dual MEK/PD-L1 inhibition. These data support further investigation to understand how MEKi combines with immunotherapeutic approaches to improve clinical outcomes for patients with advanced BTC.

Targeting tumor microenvironment for cholangiocarcinoma: Opportunities for precision medicine

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CCA has a dismal prognosis, and it is usually diagnosed in advanced stage for which available treatments have limited efficacy.

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CCA TME presents an abundant desmoplastic stroma and exhibits a high heterogeneity.

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TME plays a central role in cancer development and in the resistance to treatments.

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Treatments targeting the TME in association with cytotoxic agents could represent a promising therapeutic strategy.

Systemic treatments (e.g., chemotherapy and targeted therapies) have limited efficacy for patients with locally advanced – unresectable – and metastatic cholangiocarcinoma (CCA), with an overall survival of less than a year. Tumor microenvironment (TME) represents the ecosystem surrounding the tumor which comprises immune cells, fibroblasts, endothelial cells, and a wide range of soluble factors. CCA TME is characterized by an abundant desmoplastic stroma, exhibits a high heterogeneity and it plays a central role in cancer onset and progression. There is growing evidence suggesting that it is possible to target TME in association with other treatment modalities, such as cytotoxic chemotherapy or targeted therapies, paving the way to possible combination strategies with a synergistic effect. Herein, we describe the components of CCA TME – such as cancer-associated fibroblasts and other cells of pivotal importance - with their most relevant interactions, focusing on the preclinical rationale for the development of effective anticancer treatments.

Cilia-localized GID/CTLH ubiquitin ligase complex regulates protein homeostasis of sonic hedgehog signaling components

Cilia are evolutionarily conserved organelles that orchestrate a variety of signal transduction pathways, such as sonic hedgehog (SHH) signaling, during embryonic development. Our recent studies have shown that loss of GID ubiquitin ligase function results in aberrant AMP-activated protein kinase (AMPK) activation and elongated primary cilia, which suggests a functional connection to cilia. Here, we reveal that the GID complex is an integral part of the cilium required for primary cilia-dependent signal transduction and the maintenance of ciliary protein homeostasis. We show that GID complex subunits localize to cilia in both Xenopus laevis and NIH3T3 cells. Furthermore, we report SHH signaling pathway defects that are independent of AMPK and mechanistic target of rapamycin (MTOR) activation. Despite correct localization of SHH signaling components at the primary cilium and functional GLI3 processing, we find a prominent reduction of some SHH signaling components in the cilium and a significant decrease in SHH target gene expression. Since our data reveal a critical function of the GID complex at the primary cilium, and because suppression of GID function in X. laevis results in ciliopathy-like phenotypes, we suggest that GID subunits are candidate genes for human ciliopathies that coincide with defects in SHH signal transduction.

Up-to-Date Pathologic Classification and Molecular Characteristics of Intrahepatic Cholangiocarcinoma

Intrahepatic cholangiocarcinoma (iCCA) is an aggressive primary liver malignancy with an increasing incidence worldwide. Recently, histopathologic classification of small duct type and large duct type iCCA has been introduced. Both these types of tumors exhibit differences in clinicopathological features, mutational profiles, and prognosis. Small duct type iCCA is composed of non-mucin-producing cuboidal cells, whereas large duct type iCCA is composed of mucin-producing columnar cells, reflecting different cells of origin. Large duct type iCCA shows more invasive growth and poorer prognosis than small duct type iCCA. The background liver of small duct type iCCA often shows chronic liver disease related to hepatitis B or C viral infection, or alcoholic or non-alcoholic fatty liver disease/steatohepatitis, in contrast to large duct type iCCA that is often related to hepatolithiasis and liver fluke infection. Cholangiolocarcinoma is a variant of small duct type iCCA composed of naïve-looking cuboidal cells forming cords or ductule-like structures, and shows better prognosis than the conventional small duct type. Fibrous tumor stroma, one of the characteristic features of iCCA, contains activated fibroblasts intermixed with innate and adaptive immune cells. The types of stroma (mature versus immature) are related to tumor behavior and prognosis. Low tumor-infiltrating lymphocyte density, KRAS alteration, and chromosomal instability are related to immune-suppressive tumor microenvironments with resistance to programmed death 1/ programmed death ligand 1 blockade. Data from recent large-scale exome analyses have revealed the heterogeneity in the molecular profiles of iCCA, showing that small duct type iCCA exhibit frequent BAP1, IDH1/2 hotspot mutations and FGFR2 fusion, in contrast to frequent mutations in KRAS, TP53, and SMAD4 observed in large duct type iCCA. Multi-omics analyses have proposed several molecular classifications of iCCA, including inflammation class and proliferation class. The inflammation class is enriched in inflammatory signaling pathways and expression of cytokines, while the proliferation class has activated oncogenic growth signaling pathways. Diverse pathologic features of iCCA and its associated multi-omics characteristics are currently under active investigation, thereby providing insights into precision therapeutics for patients with iCCA. This review provides the latest knowledge on the histopathologic classification of iCCA and its associated molecular features, ranging from tumor microenvironment to genomic and transcriptomic research.

Insights into the role of STAT3 in intrahepatic cholangiocarcinoma (Review)

Intrahepatic cholangiocarcinoma (ICC) is a primary malignant liver tumour whose incidence is second only to that of hepatocellular carcinoma. ICC is a highly heterogeneous disease arising from neoplastic transformation of intrahepatic biliary epithelial cells (cholangiocytes), and it is characterized by a very poor prognosis. Signal transducer and activator of transcription 3 (STAT3) is an important oncogene that is widely expressed in numerous cancers. STAT3 is a candidate target for the treatment of ICC. However, studies on STAT3 and the occurrence and development of ICC require improvements. Therefore, the present review summarized the mechanism of STAT3 in ICC and provided a theoretical basis for STAT3 to become an effective target for determining the prognosis and treatment of ICC.

Inflammatory pathways and cholangiocarcinoma risk mechanisms and prevention

Cholangiocarcinoma (CCA), a neoplasm burdened by a poor prognosis and currently lacking adequate therapeutic treatments, can originate at different levels of the biliary tree, in the intrahepatic, hilar, or extrahepatic area. The main risk factors for the development of CCA are the presence of chronic cholangiopathies of various etiology. To date, the most studied prodromal diseases of CCA are primary sclerosing cholangitis, Caroli's disease and fluke infestations, but other conditions, such as metabolic syndrome, nonalcoholic fatty liver disease and obesity, are emerging as associated with an increased risk of CCA development. In this review, we focused on the analysis of the pro-inflammatory mechanisms that induce the development of CCA and on the role of cells of the immune response in cholangiocarcinogenesis. In very recent times, these cellular mechanisms have been the subject of emerging studies aimed at verifying how the modulation of the inflammatory and immunological responses can have a therapeutic significance and how these can be used as therapeutic targets.

PD-L1 promotes myofibroblastic activation of hepatic stellate cells by distinct mechanisms selective for TGF-β receptor I versus II

Intrahepatic cholangiocarcinoma (ICC) contains abundant myofibroblasts derived from hepatic stellate cells (HSCs) through an activation process mediated by TGF-β. To determine the role of programmed death-ligand 1 (PD-L1) in myofibroblastic activation of HSCs, we disrupted PD-L1 of HSCs by shRNA or anti-PD-L1 antibody. We find that PD-L1, produced by HSCs, is required for HSC activation by stabilizing TGF-β receptors I (TβRI) and II (TβRII). While the extracellular domain of PD-L1 (amino acids 19-238) targets TβRII protein to the plasma membrane and protects it from lysosomal degradation, a C-terminal 260-RLRKGR-265 motif on PD-L1 protects TβRI mRNA from degradation by the RNA exosome complex. PD-L1 is required for HSC expression of tumor-promoting factors, and targeting HSC PD-L1 by shRNA or Cre/loxP recombination suppresses HSC activation and ICC growth in mice. Thus, myofibroblast PD-L1 can modulate the tumor microenvironment and tumor growth by a mechanism independent of immune suppression.

Hedgehog Pathway Inhibitors as Targeted Cancer Therapy and Strategies to Overcome Drug Resistance

Hedgehog (Hh) signaling is a highly conserved pathway that plays a vital role during embryonic development. Recently, uncontrolled activation of this pathway has been demonstrated in various types of cancer. Therefore, Hh pathway inhibitors have emerged as an important class of anti-cancer agents. Unfortunately, however, their reputation has been tarnished by the emergence of resistance during therapy, necessitating clarification of mechanisms underlying the drug resistance. In this review, we briefly overview canonical and non-canonical Hh pathways and their inhibitors as targeted cancer therapy. In addition, we summarize the mechanisms of resistance to Smoothened (SMO) inhibitors, including point mutations of the drug binding pocket or downstream molecules of SMO, and non-canonical mechanisms to reinforce Hh pathway output. A distinct mechanism involving loss of primary cilia is also described to maintain GLI activity in resistant tumors. Finally, we address the main strategies to circumvent the drug resistance. These strategies include the development of novel and potent inhibitors targeting different components of the canonical Hh pathway or signaling molecules of the non-canonical pathway. Further studies are necessary to avoid emerging resistance to Hh inhibitors and establish an optimal customized regimen with improved therapeutic efficacy to treat various types of cancer, including basal cell carcinoma.

The Invasive Potential of Hepatoma Cells Induced by Radiotherapy is Related to the Activation of Stellate Cells and Could be Inhibited by EGCG Through the TLR4 Signaling Pathway

Post-radiotherapy recurrence and metastasis of liver cancer were thought to arise from the invasion and metastasis of residual hepatocellular carcinoma cells, but it has now been shown to be closely related to the increased metastatic potential of residual liver cancer cells mediated by radiotherapy. The changes of liver microenvironment after radiotherapy also provide a favorable condition for promoting the metastatic potential of hepatocellular carcinoma. Studies have shown that radiation-induced activation of hepatic stellate cells (HSCs) is one of the main changes in the microenvironment of hepatocellular carcinoma. Therefore, we hypothesized that activated HSCs are involved in regulating the metastatic capacity of residual cancer cells after radiotherapy. The present study observed that 48 h co-culture of three human hepatoma cell lines (MHCC97-L, Hep-3B, LM3) with a irradiated human HSC line (LX-2) in a transwell chamber could significantly improve the invasion of the human hepatoma cells; and the culture supernatant of activated HSCs could also enhance the invasion of the hepatoma cells. In contrast, co-culture with irradiated hepatoma cells enhanced the invasion of LX-2 cells. In vitro, irradiation enhanced the activation phenotype and the toll like receptor 4 (TLR4) signaling pathway of LX-2 cells or primary mouse HSCs, which upregulated intercellular cell adhesion molecule-1 (ICAM1), laminin receptor (67 LR), Interleukin- 6 (IL-6), and CX3C chemokine ligand 1 (CX3CL1) and downregulated toll-interacting proteins. The compound (-)-epigallocatechin-3-gallate (EGCG) inhibited signal transduction of activated TLR4 and radiation-induced invasion of LX-2 cells by binding to 67 LR. These observations indicated that the enhancement of the metastatic potential of hepatoma cells after irradiation was relevant to the activation of HSCs, and the activation of TLR4 signaling pathway was involved in this process, which was inhibited by EGCG. Our results will help enhance the therapeutic efficacy of liver cancer stereotactic body radiation therapy to prevent and decrease the risks of post-radiotherapy recurrence and metastasis.

Placental growth factor promotes tumour desmoplasia and treatment resistance in intrahepatic cholangiocarcinoma

OBJECTIVE

Intrahepatic cholangiocarcinoma (ICC)-a rare liver malignancy with limited therapeutic options-is characterised by aggressive progression, desmoplasia and vascular abnormalities. The aim of this study was to determine the role of placental growth factor (PlGF) in ICC progression.

DESIGN

We evaluated the expression of PlGF in specimens from ICC patients and assessed the therapeutic effect of genetic or pharmacologic inhibition of PlGF in orthotopically grafted ICC mouse models. We evaluated the impact of PlGF stimulation or blockade in ICC cells and cancer-associated fibroblasts (CAFs) using in vitro 3-D coculture systems.

RESULTS

PlGF levels were elevated in human ICC stromal cells and circulating blood plasma and were associated with disease progression. Single-cell RNA sequencing showed that the major impact of PlGF blockade in mice was enrichment of quiescent CAFs, characterised by high gene transcription levels related to the Akt pathway, glycolysis and hypoxia signalling. PlGF blockade suppressed Akt phosphorylation and myofibroblast activation in ICC-derived CAFs. PlGF blockade also reduced desmoplasia and tissue stiffness, which resulted in reopening of collapsed tumour vessels and improved blood perfusion, while reducing ICC cell invasion. Moreover, PlGF blockade enhanced the efficacy of standard chemotherapy in mice-bearing ICC. Conclusion PlGF blockade leads to a reduction in intratumorous hypoxia and metastatic dissemination, enhanced chemotherapy sensitivity and increased survival in mice-bearing aggressive ICC.

CAFs shape myeloid-derived suppressor cells to promote stemness of intrahepatic cholangiocarcinoma through 5-lipoxygenase

BACKGROUND AND AIMS

We previously demonstrated that cancer-associated fibroblasts (CAFs) promote tumor growth through recruitment of myeloid-derived suppressor cells (MDSCs). 5-lipoxygenase (5-LO) is highly expressed in myeloid cells and is critical for synthesizing leukotriene B4 (LTB4), which is involved in tumor progression by activating its receptor leukotriene B4 receptor type 2 (BLT2). In this study, we investigated whether and how CAFs regulate MDSC function to enhance cancer stemness, the driving force of the cancer aggressiveness and chemotherapy refractoriness, in highly desmoplastic intrahepatic cholangiocarcinoma (ICC).

APPROACH AND RESULTS

RNA-sequencing analysis revealed enriched metabolic pathways but decreased inflammatory pathways in cancer MDSCs compared with blood MDSCs from patients with ICC. Co-injection of ICC patient-derived CAFs promoted cancer stemness in an orthotopic ICC model, which was blunted by MDSC depletion. Conditioned media (CM) from CAF-educated MDSCs drastically promoted tumorsphere formation efficiency and stemness marker gene expression in ICC cells. CAF-CM stimulation increased expression and activity of 5-LO in MDSCs, while 5-LO inhibitor impaired the stemness-enhancing capacity of MDSCs in vitro and in vivo. Furthermore, IL-6 and IL-33 primarily expressed by CAFs mediated hyperactivated 5-LO metabolism in MDSCs. We identified the LTB4-BLT2 axis as the critical downstream metabolite signaling of 5-LO in promoting cancer stemness, as treatment with LTB4 was elevated in CAF-educated MDSCs, or blockade of BLT2 (which was preferentially expressed in stem-like ICC cells) significantly reduced stemness-enhancing effects of CAF-educated MDSCs. Finally, BLT2 blockade augmented chemotherapeutic efficacy in ICC patient-derived xenograft models.

CONCLUSIONS

Our study reveals a role for CAFs in orchestrating the optimal cancer stemness-enhancing microenvironment by educating MDSCs, and suggests the 5-LO/LTB4-BLT2 axis as promising therapeutic targets for ICC chemoresistance by targeting cancer stemness.

Cholangiocarcinoma: what are the most valuable therapeutic targets - cancer-associated fibroblasts, immune cells, or beyond T cells?

INTRODUCTION

CCAs are dense and desmoplastic tumors with an abundant tumor microenviroment (TME). The evolving TME is characterized by reciprocal interactions between cancer cells and their environment and is essential in facilitating tumor progression. The TME has nonimmune and immune components. Nonimmune cell types include cancer-associated fibroblasts (CAFs) and endothelial cells accompanying tumor angiogenesis. Immune cell types include elements of the innate and adaptive immune response, and can have pro-tumor or antitumor roles. The TME can shape treatment response and resistance. Therefore, elements of the TME are attractive therapeutic targets. TME targeting therapies have been evaluated in preclinical and clinical studies but only a small subset of patients has a meaningful response.

AREAS COVERED

We discuss the TME components and potential TME targeting strategies. Literature search was performed on PubMed and ClinicalTrials.gov until October 2021.

EXPERT OPINION

Elucidating the CCA TME is essential for developing effective treatment strategies. Preclinical models that recapitulate the disease (such as organoids) are important tools in uncovering the intricate cross talk in the CCA TME. Characterization of patient-derived specimens using multi-omic and single-omic technologies can dissect the cellular interplay in the CCA TME, which can guide development of effective treatment strategies and identify biomarkers for patient stratification.

Role of noninvasive imaging in the evaluation of intrahepatic cholangiocarcinoma: from diagnosis and prognosis to treatment response

INTRODUCTION

Intrahepatic cholangiocarcinoma is the second most common liver cancer. Desmoplastic stroma may be revealed as distinctive histopathologic findings favoring intrahepatic cholangiocarcinoma. Meanwhile, a range of imaging manifestations is often accompanied with rich desmoplastic stroma in intrahepatic cholangiocarcinoma, which can indicate large bile duct ICC, and a higher level of cancer-associated fibroblasts with poor prognosis and weak treatment response.

AREAS COVERED

We provide a comprehensive review of current state-of-the-art and recent advances in the imaging evaluation for diagnosis, staging, prognosis and treatment response of intrahepatic cholangiocarcinoma. In addition, we discuss precursor lesions, cells of origin, molecular mutation, which would cause the different histological classification. Moreover, histological classification and tumor microenvironment, which are related to the proportion of desmoplastic stroma with many imaging manifestations, would be also discussed.

EXPERT OPINION

The diagnosis, prognosis, treatment response of intrahepatic cholangiocarcinoma may be revealed as the presence and the proportion of desmoplastic stroma with a range of imaging manifestations. With the utility of radiomics and artificial intelligence, imaging is helpful for ICC evaluation. Multicentre, large-scale, prospective studies with external validation are in need to develop comprehensive prediction models based on clinical data, imaging findings, genetic parameters, molecular, metabolic, and immune biomarkers.

The Role of the Hedgehog Pathway in Cholangiocarcinoma

Simple Summary

Cholangiocarcinoma (CCA) is one of the most refractory malignancies with a high mortality rate. Among all the pathways involved in CCA development, emerging evidence highlights Hedgehog (HH) signaling as a substantial player in CCA-genesis and development. The pro-tumoral function of HH provides potential therapeutic implications, and recently the use of HH inhibitors has paved the way for clinical application in various solid tumors. Targeting HH members, namely Hedgehog ligands, SMO transmembrane protein and GLI transcription factors may thus confer therapeutic options for the improvement of CCA treatment outcome.

Abstract

Cholangiocarcinoma (CCA) is a poorly treatable type of cancer and, along with hepatocellular carcinoma (HCC), is the predominant type of primitive liver cancer in adults. The lack of understanding of CCA biology has slowed down the identification of novel targets and the development of effective treatments. While tumors share some general characteristics, detailed knowledge of specific features is essential for the development of effectively tailored therapeutic approaches. The Hedgehog (HH) signaling cascade regulates stemness biology, embryonal development, tissue homeostasis, and cell proliferation and differentiation. Its aberrant activation has been associated with a variety of solid and hematological human malignancies. Several HH-inhibiting compounds have been indeed developed as potential anticancer agents in different types of tumors, with Smoothened and GLI inhibitors showing the most promising results. Beside its well-established function in other tumors, findings regarding the HH signaling in CCA are still controversial. Here we will give an overview of the most important clinical and molecular features of cholangiocarcinoma, and we will discuss the available evidence of the crosstalk between the HH signaling pathway and the cholangiocarcinoma cell biology.

Gli2-regulated activation of hepatic stellate cells and liver fibrosis by TGF-β signaling

The Hedgehog (Hh) signaling pathway is correlated with hepatic stellate cells (HSCs) activation and liver fibrosis. Gli2 is a key transcription effector of Hh signaling. However, the role of Gli2 in HSC-mediated liver fibrosis progression is largely unknown. In the present study, we investigated the effect of Gli2 on liver fibrogenesis and its possible mechanism using conditional knockout (cKO) Gli2 mice and HSC models. Wild-type (WT) and GFAP-CreERT;Gli2^flox/flox male mice were exposed to CCl₄ for 1 mo to induce liver fibrosis. Primary HSCs were isolated from mice and the transition of HSCs into a myofibroblastic phenotype was evaluated. Livers from mice underwent histological, immunohistochemical, and immunofluorescence analyses. The expression levels of proteins and genes were evaluated by Western blot (WB) analysis and quantitative real-time polymerase chain reaction (qRT-PCR), respectively. RNA-seq was used to screen differentially expressed genes. Results showed that CCl₄ treatment induced liver fibrosis, promoted HSCs activation and proliferation, and upregulated Hh signaling activity. The cKO of Gli2 in GFAP-CreERT;Gli2^flox/flox mice decreased liver fibrosis as well as HSC activation and proliferation. In vitro studies showed that KO of Gli2 in HSCs blocked cell proliferation and activation by decrease of cyclin D1/D2 expression. The RNA-seq results revealed that the expression levels TGF-β1 ligands were downregulated in Gli2 KO HSCs. Furthermore, overexpression of Gli2 rescued proliferation and activation of HSCs by upregulation of TGF-β signaling activity. Our data demonstrated that Gli2 regulated HSC activation and liver fibrosis by TGF-β signaling, thus providing support for future Gli2-based investigations of liver fibrosis therapy.NEW & NOTEWORTHYGli2 is a key transcription effector of Hh signaling. We found that Hh/Gli2 signaling activity was upregulated in CCl₄-induced liver fibrosis. Conditional deletion of the Gli2 gene in HSCs ameliorated CCl₄-induced liver fibrosis and HSCs activation. Moreover, Gli2 promoted activation of HSCs through upregulation of cyclin expression and TGF-β signaling activity. Thus, our data provide strong support for future investigations on Gli2 inhibition to slow liver fibrosis progression in humans.

TWEAK/Fn14 signalling promotes cholangiocarcinoma niche formation and progression

BACKGROUND & AIMS

Cholangiocarcinoma (CCA) is a cancer of the hepatic bile ducts that is rarely resectable and is associated with poor prognosis. Tumour necrosis factor-like weak inducer of apoptosis (TWEAK) is known to signal via its receptor fibroblast growth factor-inducible 14 (Fn14) and induce cholangiocyte and myofibroblast proliferation in liver injury. We aimed to characterise its role in CCA.

METHODS

The expression of the TWEAK ligand and Fn14 receptor was assessed immunohistochemically and by bulk RNA and single cell transcriptomics of human liver tissue. Spatiotemporal dynamics of pathway regulation were comprehensively analysed in rat and mouse models of thioacetamide (TAA)-mediated CCA. Flow cytometry, qPCR and proteomic analyses of CCA cell lines and conditioned medium experiments with primary macrophages were performed to evaluate the downstream functions of TWEAK/Fn14. In vivo pathway manipulation was assessed via TWEAK overexpression in NICD/AKT-induced CCA or genetic Fn14 knockout during TAA-mediated carcinogenesis.

RESULTS

Our data reveal TWEAK and Fn14 overexpression in multiple human CCA cohorts, and Fn14 upregulation in early TAA-induced carcinogenesis. TWEAK regulated the secretion of factors from CC-SW-1 and SNU-1079 CCA cells, inducing polarisation of proinflammatory CD206+ macrophages. Pharmacological blocking of the TWEAK downstream target chemokine monocyte chemoattractant protein 1 (MCP-1 or CCL2) significantly reduced CCA xenograft growth, while TWEAK overexpression drove cancer-associated fibroblast proliferation and collagen deposition in the tumour niche. Genetic Fn14 ablation significantly reduced inflammatory, fibrogenic and ductular responses during carcinogenic TAA-mediated injury.

CONCLUSION

These novel data provide evidence for the action of TWEAK/Fn14 on macrophage recruitment and phenotype, and cancer-associated fibroblast proliferation in CCA. Targeting TWEAK/Fn14 and its downstream signals may provide a means to inhibit CCA niche development and tumour growth.

LAY SUMMARY

Cholangiocarcinoma is an aggressive, chemotherapy-resistant liver cancer. Interactions between tumour cells and cells that form a supportive environment for the tumour to grow are a source of this aggressiveness and resistance to chemotherapy. Herein, we describe interactions between tumour cells and their supportive environment via a chemical messenger, TWEAK and its receptor Fn14. TWEAK/Fn14 alters the recruitment and type of immune cells in tumours, increases the growth of cancer-associated fibroblasts in the tumour environment, and is a potential target to reduce tumour formation.

Targeting the tumor microenvironment in cholangiocarcinoma: implications for therapy

Introduction: Cholangiocarcinomas (CCAs) are biliary epithelial tumors with rising incidence over the past 3 decades. Early diagnosis of CCAs remains a significant challenge and the majority of patients present at an advanced stage. CCAs are heterogeneous tumors and currently available standard systemic therapy options are of limited effectiveness. Immune checkpoint inhibition (ICI) has transformed cancer therapy across a spectrum of malignancies. However, the response rate to ICI has been relatively disappointing in CCAs owing to its desmoplastic tumor microenvironment (TME).Areas covered: Tumor microenvironment of CCAs consists of innate and adaptive cells, stromal cells, and extracellular components (cytokines, chemokines, exosomes, etc.). This intricate microenvironment has multiple immunosuppressive elements that promote tumor cell survival and therapeutic resistance. Accordingly, there is a need for the development of effective therapeutic strategies that target the TME. Herein, we review the components of the CCA TME, and potential therapies targeting the CCA TME.Expert opinion: CCAs are desmoplastic tumors with a dense tumor microenvironment. An enhanced understanding of the various components of the CCA TME is essential in the effort to develop novel biomarkers for patient stratification as well as combination therapeutic strategies that target the tumor plus the TME.

Hepatic stellate cells promote intrahepatic cholangiocarcinoma progression via NR4A2/osteopontin/Wnt signaling axis

Intrahepatic cholangiocarcinoma (ICC) is a highly fatal malignancy characterized by a vast amount of intra-tumoral fibroblasts. These fibroblasts are potentially implicated in maintaining the high aggressiveness of ICC, whereas its pro-cancer mechanisms remain scarcely reported. Here, by establishing co-culture models of ICC cells and hepatic stellate cells (HSCs), we identified that HSCs triggered the expression of nuclear receptor family 4 subgroup A member 2 (NR4A2), a transcription factor previously reported as a molecular switch between inflammation and cancer, in ICC cells. Functionally, NR4A2 promotes tumor proliferation, metastatic potentiality and represents an independent prognostic indicator for overall survival in ICC patients. Mechanistically, NR4A2 upregulates osteopontin (OPN) expression through transcriptional activation and thereby augments the activity of Wnt/β-catenin signaling. Intriguingly, in the context of co-culture, vascular endothelial growth factor (VEGF), a previously proved NR4A2 stimulus, not only enhances NR4A2 expression, but also can be blunted by the interference of the NR4A2-OPN axis. Altogether, this study suggests the NR4A2/OPN/Wnt signaling axis to be a pivotal executor of HSC-instigated cancer-promoting roles in ICC, and the NR4A2/OPN/VEGF positive feedback loop may help to reinforce the effect.

Cholangiocarcinoma: shedding light on the most promising drugs in clinical development

Introduction: Cholangiocarcinoma (CCA) is a diverse group of fatal malignancies arising from the biliary tract. Surgical resection with negative margin offers the only potentially curative option. The majority of patients present at locally advanced or metastatic stages, when surgical resection is not feasible, highlighting the significance of systemic therapy. Given the limited effectiveness of traditional chemotherapy regimens in CCA, many investigators have focused on developing novel molecular therapies targeting key aberrant signaling pathways.Areas covered: We present the main genomic aberrations known to play a key role in cholangiocarcinogenesis and discuss promising targeted therapies in clinical development.In October of 2020, a review of the English literature was performed utilizing PubMed and Web of Science databases for the keywords of 'cholangiocarcinoma', 'biliary tract cancer', and 'targeted therapy'.Expert opinion: Unfortunately, despite encouraging results in preclinical studies, the outcome of clinical trials with established targeted therapies like anti-EGFR medications have been discouraging. Currently, agents targeting FGFR2 fusion and IDH1/2 mutations hold great promise for improving the management of CCA. Future studies focused on enhancing our understanding of key aberrant signaling pathways of cholangiocarcinogenesis and the design of homogeneous and biomarker-driven cohorts are key elements of establishing precision medicine in CCA.

Targeted therapies for extrahepatic cholangiocarcinoma: preclinical and clinical development and prospects for the clinic

Introduction: Until recently, cholangiocarcinoma (CCA) was a largely overlooked disease, and among CCAs, extrahepatic CCA (eCCA) was even more neglected. Despite the growing impact of molecularly targeted therapies and immunotherapy, prognosis of eCCA is dismal. Therefore, unraveling the complex molecular landscape of eCCA has become an urgent need. Deep phenotyping studies have revealed that eCCA is a heterogeneous tumor, harboring specific alterations categorizable into four classes, 'Mesenchymal', 'Proliferation', 'Immune', 'Metabolic'. Molecular alterations convey the activation of several pro-oncogenic pathways, where either actionable drivers or outcome predictors can be identified.Areas covered: We offer insights on perturbed pathways, molecular profiling, and actionable targets in eCCA and present a perspective on the potential stepping-stones to future progress. A systematic literature search in PubMed/ClinicalTrials.gov websites was performed by authors from different disciplines according to their specific topic knowledge to identify the newest and most relevant advances in precision medicine of eCCA.Expert opinion: eCCA is a distinct entity with unique features in terms of molecular classes, oncogenic drivers, and tumor microenvironment. Since more prevalent mutations are currently undruggable, and immunotherapy can be offered only to a minority of patients, international collaborations are instrumental to improve the understanding of the molecular underpins of this disease.

Inhibition of platelet-derived growth factor receptor synergistically increases the pharmacological effect of tamoxifen in estrogen receptor α positive breast cancer

The platelet-derived growth factor (PDGF) family, a complex and imperative group of proangiogenic factors, acts as strong cell growth chemokines and is essential for the progression of malignancy in humans. In the present study, it was observed that aberrant PDGFB expression is associated with survival rates in patients with estrogen receptor-positive (ER⁺) breast cancer unlike other subtypes, including PDGFA, PDGFC and PDGFD. Accordingly, the effect of specific PDGF receptor (PDGFR) inhibitors on ER-α⁺ breast cancer cells was investigated. To block the PDGF-BB signaling pathway, PDGFR inhibitors (sunitinib or ponatinib) were employed. Sunitinib and ponatinib were found to arrest the cell cycle at the G0-G1 phase. In addition, the two PDGFR inhibitors were revealed to significantly inhibit cell growth and decrease the expression of matrix metalloproteinase-1, which is one of the metastasis-related genes. Finally, the combined effects of the two PDGFR inhibitors with tamoxifen were investigated. The results demonstrated that the combination of two PDGFR inhibitors with tamoxifen inhibited the growth of cells more consistently, compared with the effect mediated by tamoxifen alone. Therefore, it is proposed that PDGFR inhibitors, including sunitinib and ponatinib, should be applied effectively to treat ER-α⁺ breast cancer.

Simultaneously targeting cancer-associated fibroblasts and angiogenic vessel as a treatment for TNBC

Fibrotic tumor stroma plays an important role in facilitating triple-negative breast cancer (TNBC) progression and chemotherapeutic resistance. We previously reported a rationally designed protein (ProAgio) that targets integrin αvβ3 at a novel site. ProAgio induces apoptosis via the integrin. Cancer-associated fibroblasts (CAFs) and angiogenic endothelial cells (aECs) in TNBC tumor express high levels of integrin αvβ3. ProAgio effectively induces apoptosis in CAFs and aECs. The depletion of CAFs by ProAgio reduces intratumoral collagen and decreases growth factors released from CAFs in the tumor, resulting in decreased cancer cell proliferation and apoptotic resistance. ProAgio also eliminates leaky tumor angiogenic vessels, which consequently reduces tumor hypoxia and improves drug delivery. The depletion of CAFs and reduction in hypoxia by ProAgio decreases lysyl oxidase (LOX) secretion, which may play a role in the reduction of metastasis. ProAgio stand-alone or in combination with a chemotherapeutic agent provides survival benefit in TNBC murine models, highlighting the therapeutic potential of ProAgio as a treatment strategy.

The Tumor Microenvironment in Cholangiocarcinoma Progression

Cholangiocarcinoma (CCA) is an aggressive and heterogeneous malignancy of the biliary tree. A typical hallmark of CCA is that cancer cells are embedded into a dense stroma containing fibrogenic cells, lymphatics and a variety of immune cells. Functional roles of the reactive tumor stroma are not fully elucidated; however, recent studies suggest that the tumor microenvironment plays a key role in the progression and invasiveness of CCA. CCA cells exchange autocrine/paracrine signals with other cancer cells and the infiltrating cell types that populate the microenvironment. This crosstalk is under the control of signals mediated by various cytokines, chemokines, and growth factors. In addition, extracellular vesicles (EVs), exosomes and microvesicles, containing cargo mediators, such as proteins and RNAs, play a key role in cell-to-cell communication, and particularly in epigenetic regulation thanks to their content in miRNAs. Both cytokine- and EV-mediated communications between CCA cells and other liver cells provide a potential novel target for the management of CCA. This review summarizes current understandings of the tumor microenvironment and intercellular communications in CCA and their role in tumor progression.

Regorafenib, an investigational agent for the treatment of cholangiocarcinoma

INTRODUCTION

Cholangiocarcinoma is a prevalent gastrointestinal cancer with a high mortality rate. A limited number of cholangiocarcinoma patients are diagnosed with early-stage disease but unfortunately, most patients present with an advanced-stage disease which is not amenable to curative surgical resection.

AREAS COVERED

We discuss regorafenib, a multi-kinase inhibitor, which has been investigated as a therapeutic agent in advanced stage biliary tract cancer patients in phase II trials. We examined the efficacy and toxicity of this agent and its potential in this patient population in the future. We also provide further insights on novel approaches to optimize the efficacy of regorafenib in cholangiocarcinoma patients.

EXPERT OPINION

The recent phase II trials of single-agent regorafenib in advanced stage biliary tumors revealed a modest activity in non enriched patient population and is currently part of the national comprehensive cancer network (NCCN) guidelines (Level 2B) in the refractory setting. However, more opportunities for this agent exist in combination approaches with other therapeutics such as immune checkpoint inhibitors. It is also important to recognize that the paradigm has significantly shifted for targeted therapy to more specific and more potent tyrosine kinase inhibitors targeting specific actionable genes.

Intrahepatic cholangiocarcinoma: Morpho-molecular pathology, tumor reactive microenvironment, and malignant progression

Intrahepatic cholangiocarcinoma (iCCA) is a relatively rare, but highly lethal and biologically complex primary biliary epithelial cancer arising within liver. After hepatocellular carcinoma, iCCA is the second most common primary liver cancer, accounting for approximately 10-20% of all primary hepatic malignancies. Over the last 10-20 years, iCCA has become the focus of increasing concern largely due to its rising incidence and high mortality rates in various parts of the world, including the United States. The challenges posed by iCCA are daunting and despite recent progress in the standard of care and management options for iCCA, the prognosis for this cancer continues to be dismal. In an effort to provide a framework for advancing our understanding of iCCA malignant aggressiveness and therapy resistance, this review will highlight key etiological, biological, molecular, and microenvironmental factors hindering more effective management of this hepatobiliary cancer. Particular focus will be on critically reviewing the cell origins and morpho-molecular heterogeneity of iCCAs, providing mechanistic insights into high risk fibroinflammatory cholangiopathies associated with iCCA development, and notably discussing the deleterious role played by the tumor reactive desmoplastic stroma in regulating iCCA malignant progression, lymphangiogenesis, and tumor immunobiology.

TRAIL of Hope Meeting Resistance in Cancer

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) induces apoptosis selectively via its interaction with the death receptors TRAILR1/DR4 and TRAILR2/DR5 in a wide range of cancers, while sparing normal cells. Despite its tremendous potential for cancer therapeutics, the translation of TRAIL into the clinic has been confounded by TRAIL-resistant cancer populations. We discuss different molecular mechanisms underlying TRAIL-mediated apoptosis and resistance to TRAIL. We also discuss the successes and failures of recent preclinical and clinical studies of TRAIL-induced apoptosis, and current attempts to overcome TRAIL resistance, and we provide a perspective for improving the prospects of future clinical implementation.

Notch signalling pathway in development of cholangiocarcinoma

Cholangiocarcinoma (CCA) comprises of extra-hepatic cholangiocarcinoma and intrahepatic cholangiocarcinoma cancers as a result of inflammation of epithelium cell lining of the bile duct. The incidence rate is increasing dramatically worldwide with highest rates in Eastern and South Asian regions. Major risk factors involve chronic damage and inflammation of bile duct epithelium from primary sclerosing cholangitis, chronic hepatitis virus infection, gallstones and liver fluke infection. Various genetic variants have also been identified and as CCA develops on the background of biliary inflammation, diverse range of molecular mechanisms are involved in its progression. Among these, the Notch signalling pathway acts as a major driver of cholangiocarcinogenesis and its components (receptors, ligands and downstream signalling molecules) represent a promising therapeutic targets. Gamma-Secretase Inhibitors have been recognized in inhibiting the Notch pathway efficiently. A comprehensive knowledge of the molecular pathways activated by the Notch signalling cascade as well as its functional crosstalk with other signalling pathways provide better approach in developing innovative therapies against CCA.

Tumor microenvironment in primary liver tumors: A challenging role of natural killer cells

In the last years, several studies have been focused on elucidate the role of tumor microenvironment (TME) in cancer development and progression. Within TME, cells from adaptive and innate immune system are one of the main abundant components. The dynamic interactions between immune and cancer cells lead to the activation of complex molecular mechanisms that sustain tumor growth. This important cross-talk has been elucidate for several kind of tumors and occurs also in patients with liver cancer, such as hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (iCCA). Liver is well-known to be an important immunological organ with unique microenvironment. Here, in normal conditions, the rich immune-infiltrating cells cooperate with non-parenchymal cells, such as liver sinusoidal endothelial cells and Kupffer cells, favoring self-tolerance against gut antigens. The presence of underling liver immunosuppressive microenvironment highlights the importance to dissect the interaction between HCC and iCCA cells with immune infiltrating cells, in order to understand how this cross-talk promotes tumor growth. Deeper attention is, in fact, focused on immune-based therapy for these tumors, as promising approach to counteract the intrinsic anti-tumor activity of this microenvironment. In this review, we will examine the key pathways underlying TME cell-cell communications, with deeper focus on the role of natural killer cells in primary liver tumors, such as HCC and iCCA, as new opportunities for immune-based therapeutic strategies.

Emerging pathways for precision medicine in management of cholangiocarcinoma

Cholangiocarcinoma (CCA) is the second most common biliary tract malignancy with a dismal prognosis. Surgical resection with a negative microscopic margin offers the only hope for long-term survival. However, the majority of patients present with advanced disease not amenable to curative resection, mainly due to late presentation and aggressive nature of the disease. Unfortunately, due to the heterogeneous nature of CCA as well as limitations of available chemotherapy medications, traditional chemotherapy regimens offer limited survival benefit. Recent advances in genomic studies and next-generation sequencing techniques have assisted in better understanding of cholangiocarcinogenesis and identification of potential aberrant signaling pathways. Targeting the specific genomic abnormalities via novel molecular therapies has opened a new avenue in management of CCA with encouraging results in preclinical studies and early clinical trials. In this review, we present emerging therapies for precision medicine in CCA.

Carcinoma-Associated Mesenchymal Stem Cells Promote Chemoresistance in Ovarian Cancer Stem Cells via PDGF Signaling

Within the ovarian cancer tumor microenvironment, cancer stem-like cells (CSC) interact with carcinoma associated mesenchymal stem/stromal cells (CA-MSC) through multiple secreted cytokines and growth factors. These paracrine interactions have been revealed to cause enrichment of CSC and their chemoprotection; however, it is still not known if platelet-derived growth factor (PDGF) signaling is involved in facilitating these responses. In order to probe this undiscovered bidirectional communication, we created a model of ovarian malignant ascites in the three-dimensional (3D) hanging drop heterospheroid array, with CSC and CA-MSC. We hypothesized that PDGF secretion by CA-MSC increases self-renewal, migration, epithelial to mesenchymal transition (EMT) and chemoresistance in ovarian CSC. Our results indicate that PDGF signaling in the CSC-MSC heterospheroids significantly increased stemness, metastatic potential and chemoresistance of CSC. Knockdown of PDGFB in MSC resulted in abrogation of these phenotypes in the heterospheroids. Our studies also reveal a cross-talk between PDGF and Hedgehog signaling in ovarian cancer. Overall, our data suggest that when the stromal signaling via PDGF to ovarian CSC is blocked in addition to chemotherapy pressure, the tumor cells are significantly more sensitive to chemotherapy. Our results emphasize the importance of disrupting the signals from the microenvironment to the tumor cells, in order to improve response rates. These findings may lead to the development of combination therapies targeting stromal signaling (such as PDGF and Hedgehog) that can abrogate the tumorigenic, metastatic and platinum resistant phenotypes of ovarian CSC through additional investigations.

Impact of liver fibrosis score on prognosis after common therapies for intrahepatic cholangiocarcinoma: a propensity score matching analysis

BACKGROUND

Liver fibrosis or cirrhosis is associated with the dismal prognosis of hepatocellular carcinoma (HCC), and it might also be involved in intrahepatic cholangiocarcinoma (ICC). The effect of hepatic fibrosis on the survival of ICC patients is still unclear. This study aims to explore whether liver fibrosis impacts the overall survival (OS) and disease-specific survival (DSS) of ICC patients.

METHODS

Data of 729 eligible ICC patients receiving different therapies from the Surveillance, Epidemiology, and End Results database (2004-2015) were analyzed. Unmatched, propensity score-matched, and propensity score-weighted cohorts were used to investigate the relationships of different fibrosis scores (low fibrosis score vs. high fibrosis score) and survival. A Cox regression and Kaplan-Meier curves were used to explore the influence of fibrosis score on patients' survival. Stratified analyses based on treatment modality were conducted to compare the survival difference in ICC patients with different fibrosis scores.

RESULTS

Before matching, the one-, three-, and five-year OS were 50.9, 28.0, and 16.1% in the low fibrosis score group (n = 465) and 39.3, 20.1, and 8.0% in the high fibrosis score group (n = 264) (P < 0.001), respectively. After propensity score matching, the one-, three-, and five-year OS were 45.0, 26.0, and 10.2% in the low fibrosis score group and 36.0, 8.1, and 2.3% in the high fibrosis score group (P = 0.008), respectively. The multivariate Cox regression results showed that a high fibrosis score was an independent risk factor of OS. Additionally, patients with high fibrosis scores achieved low DSS after matching (P = 0.032). The survival benefits of the low fibrosis score group were consistent across treatment cohorts.

CONCLUSIONS

High fibrosis scores were associated with poor clinical outcomes of ICC patients receiving different common therapies.

The expression of PDGF-BB predicts curative effect in locally advanced esophageal squamous cell carcinoma treated by radiotherapy

Radiotherapy is the major approach and is well tolerated in locally advanced esophageal squamous cell carcinoma (ESCC). And nowadays, no effective biological markers have been identified for predicting the prognosis of patients with ESCC. Platelet-derived growth factor (PDGF) is associated with a poor prognosis of various malignancies. The present study aimed to assess the effect of PDGF-BB on radiotherapeutic responses of ESCC and the underlying mechanisms of its roles in ESCC. Serum from 68 cases that received neoadjuvant or radical radiotherapy was obtained before and during radiotherapy. Gene expression analyses were validated by enzyme linked immunosorbent assay. The prognosis of patients with significantly reduced PDGF-BB was probably better than that of the others found in the progression-free survival and overall survival groups. Depletion of PDGFB significantly suppressed the proliferation, invasion and migration of cancer cells. Inhibiting PDGFB induced cellular apoptosis and promoted the sensitivity to ionizing radiation (IR). Furthermore, IR inhibited PDGF-BB-induced migration by blocking the PI3K/AKT pathway in ESCC cells. We found that the expression of PDGF-BB provided a possible model for predicting ESCC radiotherapy. It can also be used as a prognostic indicator for locally advanced ESCC that was treated by radiotherapy.

Cancer-associated fibroblasts in cholangiocarcinoma

PURPOSE OF REVIEW

To give a state-of-art knowledge regarding cancer-associated fibroblasts (CAF) in cholangiocarcinoma (CCA) based both on direct evidence and studies on other desmoplastic cancers. High contingency of CAF characterizes CCA, a tumor with a biliary epithelial phenotype that can emerge anywhere in the biliary tree. Current treatments are very limited, the surgical resection being the only effective treatment but restricted to a minority of patients, whereas the remaining patients undergo palliative chemotherapy regimens. In cancer, CAF shape the tumor microenvironment, drive cancer growth and progression, and contribute to drug resistance. All these functions are accomplished through an interplay network between CAF and surrounding cells including tumor and other stromal cells, i.e. immune and endothelial cells.

RECENT FINDINGS

Several studies have pointed out the existence of CAF sub-populations carrying out several and opposite functions, cancer-promoting or cancer-restraining as shown in pancreatic cancer, another prototypic desmoplastic tumor in which heterogeneity of CAF is well demonstrated.

SUMMARY

New CAF functions are now emerging in pancreatic and breast cancers like the modulation of immune responses or tumor metabolism, opening new area for treatments.

Sonic Hedgehog Signaling in Organogenesis, Tumors, and Tumor Microenvironments

During mammalian embryonic development, primary cilia transduce and regulate several signaling pathways. Among the various pathways, Sonic hedgehog (SHH) is one of the most significant. SHH signaling remains quiescent in adult mammalian tissues. However, in multiple adult tissues, it becomes active during differentiation, proliferation, and maintenance. Moreover, aberrant activation of SHH signaling occurs in cancers of the skin, brain, liver, gallbladder, pancreas, stomach, colon, breast, lung, prostate, and hematological malignancies. Recent studies have shown that the tumor microenvironment or stroma could affect tumor development and metastasis. One hypothesis has been proposed, claiming that the pancreatic epithelia secretes SHH that is essential in establishing and regulating the pancreatic tumor microenvironment in promoting cancer progression. The SHH signaling pathway is also activated in the cancer stem cells (CSC) of several neoplasms. The self-renewal of CSC is regulated by the SHH/Smoothened receptor (SMO)/Glioma-associated oncogene homolog I (GLI) signaling pathway. Combined use of SHH signaling inhibitors and chemotherapy/radiation therapy/immunotherapy is therefore key in targeting CSCs.

Fibroblastic FAP promotes intrahepatic cholangiocarcinoma growth via MDSCs recruitment

Desmoplasia is a hallmark of intrahepatic cholangiocarcinoma (ICC), which constitutes a barrier to infiltration of lymphocyte, but not myeloid cells. Given that dense desmoplastic stroma has been reported to be a barrier to infiltration of lymphocyte, but not myeloid cells. We here investigated whether fibroblastic FAP influenced ICC progression via non-T cell-related immune mechanisms. We demonstrated fibroblastic FAP expression was critical for STAT3 activation and CCL2 production, and ICC-CAFs were the primary source of CCL2 in human ICC microenvironment by using ICC-Fbs from six ICC patients. Fibroblastic knockdown of FAP significantly impaired the ability of ICC-CAFs to promote ICC growth, MDSCs infiltration and angiogenesis, which was restored by adding exogenous CCL2. Furthermore, interestingly, the tumor-promoting effect of fibroblastic FAP is dependent on MDSCs via secretion of CCL2, as depletion of Gr-1⁺ cells reversed the restoring effects of exogenous CCL2 on tumor growth and angiogenesis. In vitro migration assay confirmed that exogenous CCL2 could rescue the impaired ability of ICC-Fbs to attract Gr-1⁺ cells caused by fibroblastic FAP knockdown. In contrast, fibroblastic FAP knockdown had no effect on ICC cell proliferation and apoptotic resistance. Depletion MDSCs by anti-Gr-1 monoclonal antibody in subcutaneous transplanted tumor model abrogated tumor promotion by ICC-CAFs suggested that the pro-tumor function of Fibroblastic FAP relied on MDSCs. Mechanical, flow cytometry and chamber migration assay were conducted to find Fibroblastic FAP was required by the ability of ICC-CAFs to promote MDSC migration directly. Moreover, fibroblastic FAP knockdown had no effect on cell proliferation and apoptotic resistance. Here, we revealed the T-cell independent mechanisms underlying the ICC-promoting effect of fibroblastic FAP by attracting MDSCs via CCL2, which was mainly attributed to the ability of FAP to attract MDSCs and suggests that specific targeting fibroblastic FAP may represent a promising therapeutic strategy against ICC.

Multiple Interactions Between Cancer Cells and the Tumor Microenvironment Modulate TRAIL Signaling: Implications for TRAIL Receptor Targeted Therapy

Tumor necrosis factor (TNF) related apoptosis-inducing ligand (TRAIL) signaling is far more complex than initially anticipated and can lead to either anti- or protumorigenic effects, hampering the successful clinical use of therapeutic TRAIL receptor agonists. Cell autonomous resistance mechanisms have been identified in addition to paracrine factors that can modulate apoptosis sensitivity. The tumor microenvironment (TME), consisting of cellular and non-cellular components, is a source for multiple signals that are able to modulate TRAIL signaling in tumor and stromal cells. Particularly immune effector cells, also part of the TME, employ the TRAIL/TRAIL-R system whereby cell surface expressed TRAIL can activate apoptosis via TRAIL receptors on tumor cells, which is part of tumor immune surveillance. In this review we aim to dissect the impact of the TME on signaling induced by endogenous and exogenous/therapeutic TRAIL, thereby distinguishing different components of the TME such as immune effector cells, neutrophils, macrophages, and non-hematopoietic stromal cells. In addition, also non-cellular biochemical and biophysical properties of the TME are considered including mechanical stress, acidity, hypoxia, and glucose deprivation. Available literature thus far indicates that tumor-TME interactions are complex and often bidirectional leading to tumor-enhancing or tumor-reducing effects in a tumor model- and tumor type-dependent fashion. Multiple signals originating from different components of the TME simultaneously affect TRAIL receptor signaling. We conclude that in order to unleash the full clinical potential of TRAIL receptor agonists it will be necessary to increase our understanding of the contribution of different TME components on outcome of therapeutic TRAIL receptor activation in order to identify the most critical mechanism responsible for resistance, allowing the design of effective combination treatments.

TCF21 inhibits tumor-associated angiogenesis and suppresses the growth of cholangiocarcinoma by targeting PI3K/Akt and ERK signaling

Tumor-associated angiogenesis plays a critical role in the pathogenesis of cholangiocarcinoma (CCA). In this study, we examined the biological effects and molecular mechanisms of transcription factor 21 (TCF21) on CCA-associated angiogenesis. TCF21 expression was compared between 15 pairs of peritumor normal tissues and CCA tissues and also between normal bile duct epithelial cells and two CCA cell lines (QBC-939 and TFK-1) using real-time PCR and Western blot. With the use of both CCA cell lines as the model system, we stably expressed TCF21 by lentiviral transduction (Lv-TCF21). In vivo, we monitored xenograft growth from different CCA cells, measured tumor-associated angiogenesis by histological analysis, and determined the expressions and circulatory levels of VEGFA and PDGF-BB by immunohistochemistry and ELISA, respectively. In vitro, we assessed the effects of conditioned medium collected from different CCA cells on the viability, migration, and tube formation of endothelial cells and explored the significance of phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt), as well as ERK1/2 signaling in this process. TCF21 was significantly downregulated in CCA tissues or cell lines. Ectopic expression of TCF21 in CCA cells inhibited xenograft growth or tumor-associated angiogenesis in vivo and targeted the expression and secretion of proangiogenic factors, VEGFA and PDGF-BB. In vitro, the conditioned medium collected from Lv-TCF21 CCA cells significantly reduced the viability, migration, and tube formation of endothelial cells. On the molecular level, the targeting of PI3K/Akt and ERK1/2 signaling mediated the anti-angiogenic activity of TCF21. TCF21 presents growth-inhibitory and anti-angiogenic activities, and thus the elevation of TCF21 expression may provide therapeutic benefits for CCA. NEW & NOTEWORTHY Transcription factor 21 (TCF21) is downregulated in cholangiocarcinoma (CCA) tissues or cells. TCF21 inhibits the growth of xenografts derived from CCA cells. TCF21 suppresses in vivo tumor-associated angiogenesis. TCF21 targets expression and production of proangiogenic factors from CCA cells. The targeting of phosphatidylinositol 3-kinase/protein kinase B and ERK1/2 signaling mediates the anti-angiogenesis of TCF21.

Nuclear GAPDH is vital for hypoxia-induced hepatic stellate cell apoptosis and is indicative of aggressive hepatocellular carcinoma behavior

Background/aim: Hepatic stellate cells (HSCs) are critical determinants of liver tumor behavior such as vascular invasion, cell proliferation and migration. The apoptosis of HSCs can inhibit tumor growth and contribute to repressing hepatocellular carcinoma (HCC) progression. Our study aims to investigate the impact of nuclear glyceraldehyde-3-phosphate dehydrogenase (GAPDH) on HSCs under hypoxic conditions and the association of nuclear GAPDH with HCC patient outcomes and tumor progression.

Patients and methods: Following stable cell passage, 0.3% O₂ was used to induce hypoxia. Cell proliferation and apoptosis were analyzed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assays and flow cytometry, respectively. Proteins expression were detected by extracting nuclear and cytoplasmic proteins and performing Western blots. GAPDH nuclear translocation was blocked by the agent deprenyl. Immunohistochemical staining for GAPDH was investigated in 137 HCC tissue samples from our center. An analysis of the clinicopathological features, Kaplan-Meier analysis and Cox proportional hazards regression analysis were applied.

Results: MTT assays and flow cytometry analyses showed that the nuclear accumulation of GAPDH led to the apoptotic death of HSCs, while blockade of this process with deprenyl significantly decreased apoptosis. Western blots revealed that deprenyl inhibited the nuclear translocation of GAPDH. An analysis of the immunohistochemical staining of HSCs in HCC tissue samples (137) revealed that nuclear GAPDH expression was significantly positively correlated with HIF-1α expression. Overall survival (OS) and time-to-recurrence (TTR) estimated by Kaplan-Meier analyses showed that patients with high HIF-1α or low nuclear GAPDH levels in HSCs had significantly poorer prognosis compared with patients with low HIF-1α or high nuclear GAPDH expression in HSCs. Moreover, patients with combined high HIF-1α/low nuclear GAPDH expression in HSCs had the worst prognosis. The Cox regression analysis revealed that the combination of nuclear GAPDH/HIF-1α expression in HSCs was an independent prognostic factor for OS and TTR in HCC patients.

Conclusions: These findings provide a novel mechanism underlying the involvement of intranuclear GAPDH in hypoxia-induced HSCs apoptosis and a correlation between nuclear GAPDH levels and the clinical prognosis, which may prompt the development of a novel therapeutic strategy for HCC.

The tumour microenvironment and immune milieu of cholangiocarcinoma

Tumour microenvironment is a complex, multicellular functional compartment that, particularly when assembled as an abundant desmoplastic reaction, may profoundly affect the proliferative and invasive abilities of epithelial cancer cells. Tumour microenvironment comprises not only stromal cells, mainly cancer-associated fibroblasts, but also immune cells of both the innate and adaptive system (tumour-associated macrophages, neutrophils, natural killer cells, and T and B lymphocytes), and endothelial cells. This results in an intricate web of mutual communications regulated by an extensively remodelled extracellular matrix, where the tumour cells are centrally engaged. In this regard, cholangiocarcinoma, in particular the intrahepatic variant, has become the focus of mounting interest in the last years, largely because of the lack of effective therapies despite its rising incidence and high mortality rates worldwide. On the other hand, recent studies in pancreatic cancer, which similarly to cholangiocarcinoma, is highly desmoplastic, have argued against a tumour-promoting function of the tumour microenvironment. In this review, we will discuss recent developments concerning the role of each cellular population and their multifaceted interplay with the malignant biliary epithelial counterpart. We ultimately hope to provide the working knowledge on how their manipulation may lead to a therapeutic gain in cholangiocarcinoma.