Deregulated expression of Notch receptors in human hepatocellular carcinoma

Emerging trends in gastrointestinal cancers: Targeting developmental pathways in carcinogenesis and tumor progression

Gastrointestinal carcinomas are a group of cancers associated with the digestive system and its accessory organs. The most prevalent cancers related to the gastrointestinal tract are colorectal, gall bladder, gastric, hepatocellular, and esophageal cancers, respectively. Molecular aberrations in different signaling pathways, such as signal transduction systems or developmental pathways are the chief triggering mechanisms in different cancers Though a massive advancement in diagnostic and therapeutic interventions results in improved survival of patients with gastrointestinal cancer; the lower malignancy stages of these carcinomas are comparatively asymptomatic. Various gastrointestinal-related cancers are detected at advanced stages, leading to deplorable prognoses and increased rates of recurrence. Recent molecular studies have elucidated the imperative roles of several signaling pathways, namely Wnt, Hedgehog, and Notch signaling pathways, play in the progression, therapeutic responsiveness, and metastasis of gastrointestinal-related cancers. This book chapter gives an interesting update on recent findings on the involvement of developmental signaling pathways their mechanistic insight in gastrointestinalcancer. Subsequently, evidences supporting the exploration of gastrointestinal cancer related molecular mechanisms have also been discussed for developing novel therapeutic strategies against these debilitating carcinomas.

Immunotherapy and the Combination with Targeted Therapies for Advanced Hepatocellular Carcinoma

One of the most important abilities of a tumor is to establish a state of immunosuppression inside the tumor microenvironment. This is made possible through numerous mechanisms of tumor immune escape that have been identified in experimental studies during the last decades. In addition, the hepatic microenvironment is commonly oriented towards a state of immune tolerance because the liver receives blood from the hepatic arteries and portal veins containing a variety of endogenous antigens. Therefore, the hepatic microenvironment establishes an autoimmune tolerance, preventing an autoimmune reaction in the liver. On this basis, hepatic tumor cells may escape the immune system, avoiding being recognized and destroyed by immune cells. Moreover, since the etiology of Hepatocellular Carcinoma (HCC) is often related to cirrhosis, and hepatitis B or C, this tumor develops in the context of chronic inflammation. Thus, the HCC microenvironment is characterized by important immune cell infiltration. Given these data and the poor prognosis of advanced HCC, different immunotherapeutic strategies have been developed and evaluated for these patients. In this review, we describe all the clinical applications of immunotherapy for advanced HCC, from the drugs that have already been approved to the ongoing clinical trials.

Plasma-only circulating tumor DNA analysis detects minimal residual disease and predicts early relapse in hepatocellular carcinoma patients undergoing curative resection

Background

Minimal residual disease (MRD) is considered an essential factor leading to relapse within 2 years (early relapse) after radical surgery, which is challenging to be detected by conventional imaging. Circulating tumor DNA (ctDNA) provides a novel approach for detecting MRD and predicting clinical outcomes. Here, we tried to construct a fixed panel for plasma-only ctDNA NGS to enable tumor-uninformed MRD detection in hepatocellular carcinoma (HCC).

Methods

Here, we performed the followings: (i) profiling genomic alteration spectrum of ctDNA from the Chinese HCC cohort consisting of 493 individuals by NGS; (ii) screening of MRD monitoring genes; and (iii) performance evaluation of MRD monitoring genes in predicting early relapse in the ZJZS2020 cohort comprising 20 HCC patients who underwent curative resection.

Results

A total of 493 plasma samples from the Chinese HCC cohort were detected using a 381/733-gene NGS panel to characterize the mutational spectrum of ctDNA. Most patients (94.1%, 464/493) had at least one mutation in ctDNA. The variants fell most frequently in TP53 (45.1%), LRP1B (20.2%), TERT (20.2%), FAT1 (16.2%), and CTNNB1 (13.4%). By customized filtering strategy, 13 MRD monitoring genes were identified, and any plasma sample with one or more MRD monitoring gene mutations was considered MRD-positive. In the ZJZS2020 cohort, MRD positivity presented a sensitivity of 75% (6/8) and a specificity of 100% (6/6) in identifying early postoperative relapse. The Kaplan-Meier analysis revealed a significantly short relapse-free survival (RFS; median RFS, 4.2 months vs. NR, P=0.002) in the MRD-positive patients versus those with MRD negativity. Cox regression analyses revealed MRD positivity as an independent predictor of poor RFS (HR 13.00, 95% CI 2.60-69.00, P=0.002).

Conclusions

We successfully developed a 13-gene panel for plasma-only MRD detection, which was effective and convenient for predicting the risk of early postoperative relapse in HCC.

Antitumor Effect of Pseudolaric Acid B Involving Regulation of Notch1/Akt Signaling Response in Human Hepatoma Cell In Vitro

Background

Liver cancer, particularly hepatocellular carcinoma (HCC), is the fourth leading cause of cancer-related death worldwide. Sorafenib is a crucial drug for the treatment of advanced HCC, but it is difficult to meet the challenge of increasing clinical demands due to its severe side effects and drug resistance. Hence, development of novel antitumor drugs is urged. Previous studies showed that pseudolaric acid B (PAB) could reduce the expression of protein kinase B (PKB/Akt), a downstream effector of Notch signaling, facilitating cell apoptosis in HCC. The disruption of Notch signaling was verified to exacerbate malignant progression and drug resistance, however, the antitumor effect of PAB on Notch signaling in HCC remains unclear. Thus, this study aims to investigate the anti-HCC effect of PAB in association with the regulation of Notch1/Akt signaling.

Methods

CCK-8 assay and transwell assay were used to examine the cell proliferation and invasion in Huh7 cells after treatment with PAB and a Notch inhibitor DAPT. Moreover, the cell cycle of Huh7 cells after treatment with PAB was analyzed using flow cytometry. Finally, the changes of Notch1, Jagged1, Hes1, and Akt expression at the protein and mRNA level in Notch1/Akt signaling in Huh7 cells after treatment with PAB and DAPT were analyzed using immunofluorescence assay and real-time qPCR.

Results

The proliferation rate of Huh7 cells exposed to PAB of 0.5, 1, 2, 4, 8, 10, 20, 40, 80, 100, and 200 μmol/L revealed a time-and dose-dependent decrease in vitro, showing cell cycle arrest at G2/M phase (P < 0.05). Furthermore, compared with the untreated group, at the concentration of 40 μmol/L, the proliferation rate and invasion rate of Huh7 cells in PAB, DAPT, and PAB-DAPT combination (PAB + DAPT) group were significantly decreased (P < 0.05), but the PAB + DAPT showed no synergistic antiproliferation and anti-invasion effect in comparison with PAB treatment alone (P > 0.05). In addition, compared with the untreated group, PAB and DAPT alone significantly downregulated the expression of Notch1, Jagged1, Hes1, Akt mRNA, or/and protein in Huh7 cells (P < 0.05), but there was no significant difference in synergistic downregulated effect between the PAB + DAPT group and the PAB group (P > 0.05).

Conclusion

PAB can suppress proliferation and invasion of HCC cells through downregulating the expression of Notch1/Akt signaling protein and mRNA, and may be a potential novel antitumor drug candidate for the clinical treatment of HCC in the future.

Valproic acid reverses sorafenib resistance through inhibiting activated Notch/Akt signaling pathway in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common lethal human malignancies worldwide. Sorafenib is the first-line drug approved by the United States Food and Drug Administration for HCC. However, the acquired resistance to sorafenib reduces its beneficial effects and limits clinical use. In this study, we established a sorafenib-resistant HCC cell line HepG2-SR by low-concentration gradient induction. Compared with the parental cell HepG2, the proliferation and anti-apoptosis were increased in drug-resistant cell HepG2-SR. Thorough comparisons of the molecular changes between parental HepG2 and sorafenib-resistant HepG2-SR cells indicated that the Notch signaling pathway and PI3K/Akt signaling pathway were associated with sorafenib resistance mechanisms. Notch1 and Akt were upregulated in sorafenib-resistant cells. However, we surprisingly found that valproic acid (VPA) combined with sorafenib could enhance the sensitivity of drug-resistant cells and reverse the increased levels of Notch1 and Akt in sorafenib-resistant HCC cells. Moreover, Akt inhibitor could suppress Notch1 expression, whereas the level of Akt phosphorylation decreased along with increasing dose of Notch inhibitor. Besides, we found that knockdown of Akt resulted in Notch1 reduction, whereas Notch1 reduction also led to a significant reduction in the phosphorylation of Akt. Collectively, our results indicated that Notch1 and Akt might play vital roles in sorafenib resistance in HCC cells and VPA might overcome the drug resistance to enhance the sensitivity of HCC cells to sorafenib through suppressing Notch/Akt signaling pathway. VPA combined with sorafenib may provide a potential targeting therapeutic regimen for clinically to solve the problem of sorafenib resistance.

Novel molecular targets in hepatocellular carcinoma

Globally, hepatocellular carcinoma (HCC) is a leading cause of cancer and cancer-related deaths. The therapeutic efficacy of locoregional and systemic treatment in patients with advanced HCC remains low, which results in a poor prognosis. The development of sorafenib for the treatment of HCC has resulted in a new era of molecular targeted therapy for this disease. However, the median overall survival was reported to be barely higher in the sorafenib treatment group than in the control group. Hence, in this review we describe the importance of developing more effective targeted therapies for the management of advanced HCC. Recent investigations of molecular signaling pathways in several cancers have provided some insights into developing molecular therapies that target critical members of these signaling pathways. Proteins involved in the Hedgehog and Notch signaling pathways, Polo-like kinase 1, arginine, histone deacetylases and Glypican-3 can be potential targets in the treatment of HCC. Monotherapy has limited therapeutic efficacy due to the development of inhibitory feedback mechanisms and induction of chemoresistance. Thus, emphasis is now on the development of personalized and combination molecular targeted therapies that can serve as ideal therapeutic strategies for improved management of HCC.

Inhibition of EZH2 Attenuates Sorafenib Resistance by Targeting NOTCH1 Activation-Dependent Liver Cancer Stem Cells via NOTCH1-Related MicroRNAs in Hepatocellular Carcinoma

Acquired resistance and intrinsic to sorafenib therapy represents a major hurdle in improving the management of advanced hepatocellular carcinoma (HCC), which has been recently shown to be associated with the emergence of liver cancer stem cells (CSCs). However, it remains largely unknown whether and how histone posttranslational modifications, especially H3K27me3, are causally linked to the maintenance of self-renewal ability in sorafenib-resistant HCC. Here, we found that NOTCH1 signaling was activated in sorafenib-resistant HCC cells and NOTCH1 activation conferred hepatoma cells sorafenib resistance through enhanced self-renewal and tumorigenecity. Besides, the overexpression of EZH2 was required for the emergence of cancer stem cells following prolonged sorafenib treatment. As such, modulating EZH2 expression or activity suppressed activation of NOTCH1 pathway by elevating the expression of NOTCH1-related microRNAs, hsa-miR-21-5p and has-miR-26a-1-5p, via H3K27me3, and consequently weakened self-renewal ability and tumorigenecity and restored the anti-tumor effects of sorafenib. Overall, our results highlight the role of EZH2/NICD1 axis, and also suggest that EZH2 and NOTCH1 pathway are rational targets for therapeutic intervention in sorafenib-resistant HCC.

Salidroside suppresses the metastasis of hepatocellular carcinoma cells by inhibiting the activation of the Notch1 signaling pathway

Salidroside (SDS) is a phenylpropanoid glycoside isolated from Rhodiola rosea L. It exhibits multiple pharmacological properties in clinical medicine and has been commonly used in traditional Chinese medicine. The present study investigated the inhibitory effects of SDS on tumor invasion and migration, and the expression of metastasis‑related genes in highly metastatic hepatocellular carcinoma (HCC) cells (MHCC97H) in vitro. The underlying mechanisms of SDS on the tumor metastasis were also explored. SDS was found to significantly reduce wound closure areas and inhibit cell migration. In addition, SDS markedly inhibited the invasion of these cells into Matrigel‑coated membranes. SDS markedly downregulated the expression of Notch1, Snail, COX‑2, MMP‑2, MMP‑9 genes and upregulated the expression of E‑cadherin in a dose‑dependent manner. Furthermore, SDS inhibited the expression of the Notch signaling target genes, Hey1, Hes1 and Hes5. On the whole, the findings of this study suggest that SDS inhibits HCC cell metastasis by modulating the activity of the Notch1 signaling pathway.

The Carcinogenic Role of the Notch Signaling Pathway in the Development of Hepatocellular Carcinoma

The Notch signaling pathway, known to be a highly conserved signaling pathway in embryonic development and adult tissue homeostasis, participates in cell fate decisions that include cellular differentiation, cell survival and cell death. However, other studies have shown that aberrant in Notch signaling is pro-tumorigenic, particularly in hepatocellular carcinoma (HCC). HCC is one of the most common malignant tumors in the world and has a high mortality rate. Growing evidence supports that Notch signaling plays a critical role in the development of HCC by regulating the tumor microenvironment, tumorigenesis, progression, angiogenesis, invasion and metastasis. Accordingly, overexpression of Notch is closely associated with poor prognosis in HCC. In this review, we focus on the pro-tumorigenic role of Notch signaling in HCC, summarize the current knowledge of Notch signaling and its role in HCC development, and outline the therapeutic potential of targeting Notch signaling in HCC.

Upregulated MMP28 in Hepatocellular Carcinoma Promotes Metastasis via Notch3 Signaling and Predicts Unfavorable Prognosis

MMP28 belongs to the matrix metalloproteinases (MMPs) family and functions in tissue homeostasis and development. Although many other MMPs have been reported to regulate tumor progression, the roles of MMP28 in cancer remain largely elusive. In this study, we investigated the potential roles of MMP28 in hepatocellular carcinoma (HCC). The upregulation of MMP28 was first determined by the analysis on different public datasets. Further quantitative real-time PCR (qPCR) analysis, western blot (WB) assay and immunohistochemistry (IHC) assay on tumor and tumor-adjacent samples from HCC patients confirmed the aberrant elevation of MMP28 in HCC. Pathological analysis showed that increased MMP28 was associated with tumor size, vascular invasion, TNM stage and overall survival in HCC patients. Meanwhile, upregulated MMP28 was identified as an independent prognosis factor in multivariate analysis, and the incorporation of MMP28 expression with TNM staging system established a novel model to improve the accuracy of the predictions. In vivo and in vitro data revealed that MMP28 promoted migration and invasion of HCC cells, and enhanced epithelial-mesenchymal transition (EMT) via elevating zinc finger E-box binding homeobox (ZEB) homologues levels. Furthermore, we determined that Notch3 signaling was critical for the functions of MMP28 in HCC. In conclusion, upregulated MMP28 in HCC promoted migration and invasion and predicted poor prognosis for HCC patients, and the effects of MMP28 depended on Notch3 signaling.

Relationship between the upregulation of Notch1 signaling and the clinical characteristics of patients with papillary thyroid carcinoma in East Asia: a systematic review and meta-analysis

Background

Many studies have aimed to clarify the relationship between Notch1 signaling and papillary thyroid carcinoma (PTC), but the results have been inconsistent to date. In the present study, a systematic review and meta-analysis were performed to analyze the relationship between Notch1 signaling and the clinical characteristics of PTC.

Methods

Literature databases, including PubMed (Medline), Embase and China National Knowledge Infrastructure, were searched for relevant studies from inception to April 2018. A total of five studies, including 421 patients with PTC from China and South Korea, were included in the meta-analysis.

Results

The results revealed that the upregulation of Notch1 signaling was positively correlated with lymph node metastasis in patients with PTC (OR = 3.25, 95% CI 1.14–9.23, P = 0.03). Additionally, positive correlations were found between Notch1 signaling and tumor size (OR = 4.34, 95% CI 1.66–11.38, P = 0.003), capsular invasion (OR = 3.49, 95% CI 1.90–6.41, P < 0.0001) and clinical stage of PTC (OR = 2.31, 95% CI 1.05–5.11, P = 0.04).

Conclusions

The Notch1 signaling pathway may play a catalytic role in the progression of PTC, and upregulation of Notch1 signaling may have significant predictive value for the clinical prognosis of PTC.

MicroRNA-760 Inhibits Doxorubicin Resistance in Hepatocellular Carcinoma through Regulating Notch1/Hes1-PTEN/Akt Signaling Pathway

Accumulating studies have suggested that microRNA-760 (miR-760) plays an important role in chemoresistance of various cancer cells. However, whether miR-760 regulates the chemoresistance of hepatocellular carcinoma (HCC) remains unclear. In this study, we found that miR-760 was decreased in HCC cell lines, and doxorubicin (Dox) treatment significantly decreased miR-760 expression in HCC cells. Overexpression of miR-760 sensitized HCC cells to Dox-induced cytotoxicity and apoptosis, whereas miR-760 inhibition showed the opposite effects. Notch1 was predicted as a target gene of miR-760. miR-760 negatively regulated Notch1 expression and Notch1/Hes1 signaling. Overexpression of miR-760 increased PTEN expression and decreased the phosphorylation of Akt. Activation of Notch signaling significantly reversed the inhibitory effect of miR-760 on Dox-resistance and abrogated the effect of miR-760 on the PTEN/Akt signaling pathway in HCC cells. Overall, our results demonstrate that miR-760 inhibits Dox-resistance in HCC cells through inhibiting Notch1 and promoting PTEN expression.

Bioinformatics functional analysis of let-7a, miR-34a, and miR-199a/b reveals novel insights into immune system pathways and cancer hallmarks for hepatocellular carcinoma

Let-7a, miR-34a, and miR-199 a/b have gained a great attention as master regulators for cellular processes. In particular, these three micro-RNAs act as potential onco-suppressors for hepatocellular carcinoma. Bioinformatics can reveal the functionality of these micro-RNAs through target prediction and functional annotation analysis. In the current study, in silico analysis using innovative servers (miRror Suite, DAVID, miRGator V3.0, GeneTrail) has demonstrated the combinatorial and the individual target genes of these micro-RNAs and further explored their roles in hepatocellular carcinoma progression. There were 87 common target messenger RNAs (p ≤ 0.05) that were predicted to be regulated by the three micro-RNAs using miRror 2.0 target prediction tool. In addition, the functional enrichment analysis of these targets that was performed by DAVID functional annotation and REACTOME tools revealed two major immune-related pathways, eight hepatocellular carcinoma hallmarks-linked pathways, and two pathways that mediate interconnected processes between immune system and hepatocellular carcinoma hallmarks. Moreover, protein-protein interaction network for the predicted common targets was obtained by using STRING database. The individual analysis of target genes and pathways for the three micro-RNAs of interest using miRGator V3.0 and GeneTrail servers revealed some novel predicted target oncogenes such as SOX4, which we validated experimentally, in addition to some regulated pathways of immune system and hepatocarcinogenesis such as insulin signaling pathway and adipocytokine signaling pathway. In general, our results demonstrate that let-7a, miR-34a, and miR-199 a/b have novel interactions in different immune system pathways and major hepatocellular carcinoma hallmarks. Thus, our findings shed more light on the roles of these miRNAs as cancer silencers.

Vasculogenic mimicry in hepatocellular carcinoma contributes to portal vein invasion

Portal vein invasion (PVI) is common in hepatocellular carcinoma (HCC) and largely contributes to tumor recurrence after radical tumor resection or liver transplantation. Vasculogenic mimicry (VM) was an independent vascular system lined with tumor cells and associated with poor prognosis of HCC. The present study was conducted to evaluate the relationship between VM and portal vein invasion. A total of 44 HCC cases receiving anatomic liver resection were included in the study and were divided into groups with and without PVI. The prevalence of VM in each group was examined by CD34-PAS dual staining. The regulatory molecules of VM formation such as Notch1, Vimentin and matrix metalloproteinases (MMPs) were investigated by immunohistochemical staining. Analysis was performed to explore the association of PVI, VM and the VM regulatory molecules. PVI was found in 40.91% (18/44) cases and VM was found in 38.64% (17/44) cases in total samples. The incidence of VM was 72.22% (13/18) in PVI group while it was 15.38% (4/26) in non-PVI group (P<0.001), VM formation was positively correlated with PVI (r=0.574, P<0.001). The VM forming regulatory molecules such as Notch1, Vimentin, MMP-2 and MMP-9 were found to be correlated with PVI in HCC patients. Taken together, our results suggested that VM formation, alone with its regulatory molecules, is the promoting factor of PVI in hepatocellular carcinoma.

The Recent Advances on Liver Cancer Stem Cells: Biomarkers, Separation, and Therapy

As the third major reason of mortality related to cancer in the world, liver cancer is also the fifth most frequent cancer. Unluckily, a majority of patients succumb and relapse though many progresses have been made in detection and therapy of liver cancer. It has been put forward that in liver cancer, cancer stem cells (CSCs) hold main responsibility for the formation, invasion, metastasis, and recurrence of tumor. Strategies that are intended to target liver CSCs are playing a more and more significant role in supervising the development of liver cancer treatment and assessing new therapeutic methods. Herein, a brief review about molecule markers, signal pathways, separation, and treatment on liver cancer stem cells (LCSCs) is provided in this paper.

Hepatitis B virus X protein and hypoxia‑inducible factor-1α stimulate Notch gene expression in liver cancer cells

Increasing evidence has demonstrated that Notch genes, including Notch1, Notch2, Notch3 and Notch4, are involved in carcinogenesis. However, the expression and regulation of Notch genes in hepatocellular carcinoma (HCC) tissues have not been fully investigated. In the present study, immunohistochemical and quantitative real-time PCR (qPCR) analyses were performed to examine the expression of Notch genes in normal human liver, HBV-related HCC and paired peritumoral tissues. Additionally, qPCR and western blotting were utilized to investigate the impact of hepatitis B virus X protein (HBx) and hypoxia‑inducible factor-1α (HIF-1α) on the regulation of Notch gene expression. The immunohistochemical and qPCR results showed that the expression levels of Notch1, Notch3 and Notch4 were significantly higher in HCC tissues than the levels in peritumoral and normal liver tissues. However, no significant difference in Notch2 expression was found between HCC and peritumoral tissues. Among the four Notch genes, immunohistochemical analyses found that only the increased level of Notch3 in HCC tissues was positively correlated with vascular invasion of liver cancer (P<0.05). Moreover, we found that overexpression of both HBx and HIF-1α increased the expression of Notch1, Notch3 and Notch4 in HepG2 and Bel-7404 cell lines. In summary, the present study demonstrated that Notch1, Notch3 and Notch4 were upregulated in HCC tissues and that HBx and HIF-1α may be the factors that cause the overexpression of Notch genes. Furthermore, the increased expression of Notch3 was closely related to the vascular invasiveness of HCC.

Targeting Notch3 in Hepatocellular Carcinoma: Molecular Mechanisms and Therapeutic Perspectives

The Notch signaling pathway is a very conserved system that controls embryonic cell fate decisions and the maintenance of adult stem cells through cell to cell communication. Accumulating evidence support the relevance of Notch signaling in different human diseases and it is one of the most commonly activated signaling pathways in cancer. This review focuses mainly on the role of Notch3 signaling in hepatocellular carcinoma and its potential therapeutic applications against this malignancy. In this regard, the crosstalk between Notch and p53 may play an important role.

Expression of activated Notch1 and Hey1 in papillary thyroid carcinoma

AIMS

The Notch signalling pathway is involved in normal development as well as tumorigenesis. However, it is unclear whether Notch activation is related to diverse clinicopathological factors in papillary thyroid carcinoma (PTC).

METHODS AND RESULTS

We examined the relationship between clinicopathological factors and the expression of activated Notch1 and Hey1, which are indicators of Notch signalling pathway activation, in 109 PTC cases. Activated Notch1 showed strong, moderate and weak expression in 23, 48 and 36 cases, respectively. Its expression was related significantly to histopathological variants (P = 0.007), lymph node metastasis (P = 0.016), BRAF mutation (P = 0.036) and extent of surgery (P = 0.014). Hey1 immunostaining could be divided into two groups: positive and negative, with 26 and 83 cases, respectively. Its expression was related significantly to histopathological variants (P = 0.026), extrathyroidal extension (P = 0.005), BRAF mutation (P = 0.048) and recurrence or soft tissue metastasis (P = 0.000). Multivariate analysis revealed that tumour size (>1 cm), Hey1 immunoreactivity and the presence of lymph node metastasis were associated significantly with recurrence or soft tissue metastasis (odds ratio = 7.38, 4.28 and 12.00, respectively).

CONCLUSIONS

Thus, we found that activation of Notch signalling was correlated significantly with clinicopathological parameters. Therefore, Notch signalling could be a useful prognostic marker in patients with PTC.

Notch2 is a crucial regulator of self-renewal and tumorigenicity in human hepatocellular carcinoma cells

The Notch pathway plays an important role in both stem cell biology and cancer. Notch2 was reported to be upregulated in human hepatocellular carcinoma (HCC) tissues. However, the biological function of Notch2 in human HCC cells has not yet been documented. The aim of this study was to investigate its possible function on the progression of human HCC cells. The expression of Notch2 was detected in four human HCC cell lines by western blotting. Next, Notch2 was knocked down by small interference RNA (siRNA) in human HCC cells. The role of Notch2 in human HCC cells was investigated by cell proliferation assay, colony formation assay, chemoresistance and xenograft formation assay. In the present study, western blotting revealed that the expression of Notch2 was upregulated in human HCC cell lines. Genetic depletion of Notch2 in HCC cells not only resulted in significantly inhibited proliferation, cell cycle progression and colony formation ability but also increased its sensitivity to 5-fluorouracil (5-FU) compared with controls. In addition, upregulation of Notch2 was discovered in CD90 positive HCC cells, CD90 is a marker of hepatic stem cells. Most importantly, knockdown of Notch2 in HCC cells impaired the tumor formation in vivo. Taken together, our findings indicate that Notch2 may confer stemness properties in HCC; downregulation of Notch2 inhibited the proliferation and tumor formation of HCC cells and increase their sensitivity to 5-FU, suggesting Notch2 as a potential therapeutic target for HCC.

Hepatitis B virus X protein activates Notch signaling by its effects on Notch1 and Notch4 in human hepatocellular carcinoma

Deregulated expression of Notch receptors and abnormal activity of Notch signaling have been observed in a growing number of malignant tumors, however, the expression and activity of Notch in hepatitis B virus (HBV)-associated hepatocellular carcinoma (HCC) and their relationship with HBV X protein (HBx) are still not fully elucidated. To address this, we examined the overall expression of Notch receptors in HBV-associated HCC tissues, analyzed their relationship with HBx, and further investigated the role of Notch signaling in HBx stable transfected HepG2 cells (HepG2X). The results showed that Notch signaling could be activated by HBx in HepG2 cells. The expression of cytoplasmic Notch1 or nuclear Notch4 was correlated with the expression of HBx in HBV-associated HCC tissues. The expression of cytoplasmic Notch1 or nuclear Notch4 could also be upregulated by HBx in HepG2X cells. The upregulation of Notch1 by HBx was through p38 MAPK pathway. Moreover, HBx was found to directly interact with Notch1, whereas, not with Notch4 in HepG2X cells. Suppression of Notch signaling by γ-secretase inhibitor (GSI) decreased cell growth, blocked cell cycle progression and induced cell apoptosis in HepG2X cells. The present study indicates that HBx activates Notch signaling by its effects on Notch1 and Notch4, and therefore, recruits Notch signaling as a downstream pathway contributing to its carcinogenic role in HBV-associated HCC.

NOTCH2 signaling confers immature morphology and aggressiveness in human hepatocellular carcinoma cells

The NOTCH family of membranous receptors plays key roles during development and carcinogenesis. Since NOTCH2, yet not NOTCH1 has been shown essential for murine hepatogenesis, NOTCH2 rather than NOTCH1 may be more relevant to human hepatocarcinogenesis; however, no previous studies have supported this hypothesis. We therefore assessed the role of NOTCH2 in human hepatocellular carcinoma (HCC) by immunohistochemistry and cell culture. Immunohistochemically, 19% of primary HCCs showed nuclear staining for NOTCH2, indicating activated NOTCH2 signaling. NOTCH2-positive HCCs were on average in more advanced clinical stages, and exhibited more immature cellular morphology, i.e. higher nuclear-cytoplasmic ratios and nuclear densities. Such features were not evident in NOTCH1‑positive HCCs. In human HCC cell lines, abundant NOTCH2 expression was associated with anaplasia, represented by loss of E-cadherin. When NOTCH2 signaling was stably downregulated in HLF cells, an anaplastic HCC cell line, the cells were attenuated in potential for in vitro invasiveness and migration, as well as in vivo tumorigenicity accompanied by histological maturation. Generally, inverse results were obtained for a differentiated HCC cell line, Huh7, manipulated to overexpress activated NOTCH2. These findings suggested that the NOTCH2 signaling may confer aggressive behavior and immature morphology in human HCC cells.

Xanthohumol inhibits Notch signaling and induces apoptosis in hepatocellular carcinoma

Despite improvement in therapeutic strategies, median survival in advanced hepatocellular carcinoma (HCC) remains less than one year. Therefore, molecularly targeted compounds with less toxic profiles are needed. Xanthohumol (XN), a prenylated chalcone has been shown to have anti-proliferative effects in various cancers types in vitro. XN treatment in healthy mice and humans yielded favorable pharmacokinetics and bioavailability. Therefore, we determined to study the effects of XN and understand the mechanism of its action in HCC. The effects of XN on a panel of HCC cell lines were assessed for cell viability, colony forming ability, and cellular proliferation. Cell lysates were analyzed for pro-apoptotic (c-PARP and cleaved caspase-3) and anti-apoptotic markers (survivin, cyclin D1, and Mcl-1). XN concentrations of 5μM and above significantly reduced the cell viability, colony forming ability and also confluency of all four HCC cell lines studied. Furthermore, growth suppression due to apoptosis was evidenced by increased expression of pro-apoptotic and reduced expression of anti-apoptotic proteins. Importantly, XN treatment inhibited the Notch signaling pathway as evidenced by the decrease in the expression of Notch1 and HES-1 proteins. Ectopic expression of Notch1 in HCC cells reverses the anti-proliferative effect of XN as evidenced by reduced growth suppression compared to control. Taken together these results suggested that XN mediated growth suppression is appeared to be mediated by the inhibition of the Notch signaling pathway. Therefore, our findings warrants further studies on XN as a potential agent for the treatment for HCC.

Notch1 ligand signaling pathway activated in cervical cancer: poor prognosis with high-level JAG1/Notch1

OBJECTIVE

Notch signalings are regulated multiple cellular processes during cancer progression. We aimed to investigate the significance and prognostic value of expression of Notch1 and JAG1 in cervical cancer to determine whether they could serve as prognostic predictors.

METHODS/MATERIALS

The expression of Notch1/JAGD1 was investigated by real-time PCR, western blot assay and its association with overall survival of patients was analyzed by statistical analysis.

RESULTS

Notch1 and JAGD1 expression level were significantly elevated in cervical cancer in comparison to normal specimens and other types of Notch receptors and ligands. It is also proved that Notch1 and JAGD1 expression were to be associated with cervical cancer invasion, lymph node metastasis, and FIGO system. In addition, survival analysis proved that elevated Notch1 and JAGD1 expression were associated with poor overall survival of patients (P = 0.01, P = 0.02 log-rank test), respectively.

CONCLUSIONS

The present data proved the over-expression of Notch1/JAGD1 and its association with tumor progression in human cervical cancer, which might be a potential valuable biomarker for cervical cancer and further studies need.

Heterogeneity of hepatocellular carcinoma contributes to cancer progression

Hepatocellular carcinoma (HCC) is a highly heterogeneous disease displaying differences in angiogenesis, extracellular matrix proteins, the immune microenvironment and tumor cell populations. Additionally, genetic variations and epigenetic changes of HCC cells could lead to aberrant signaling pathways, induce cancer stem cells and enhance tumor progression. Thus, the heterogeneity in HCC contributes to disease progression and a better understanding of its heterogeneity will greatly aid in the development of strategies for the HCC treatment.

Impact of microenvironment and stem-like plasticity in cholangiocarcinoma: molecular networks and biological concepts

Clinical complexity, anatomic diversity and molecular heterogeneity of cholangiocarcinoma (CCA) represent a major challenge in the assessment of effective targeted therapies. Molecular and cellular mechanisms underlying the diversity of CCA growth patterns remain a key issue of clinical concern. Crucial questions comprise the nature of the CCA-origin, the initial target for cellular transformation as well as the relationship with the cancer stem cells (CSC) concept. Additionally, since CCA often develops in the context of an inflammatory milieu (cirrhosis and cholangitis), the stromal compartment or tumour microenvironment (TME) likely promotes initiation and progression of this malignancy, contributing to its heterogeneity. This review will emphasize the dynamic interplay between stem-like intrinsic and TME-extrinsic pathways, which may represent novel options for multi-targeted therapies in CCA.

RBP-J-interacting and tubulin-associated protein induces apoptosis and cell cycle arrest in human hepatocellular carcinoma by activating the p53-Fbxw7 pathway

Aberrant Notch signaling is observed in human hepatocellular carcinoma (HCC) and has been associated with the modulation of cell growth. However, the role of Notch signaling in HCC and its underlying mechanism remain elusive. RBP-J-interacting and tubulin-associated (RITA) mediates the nuclear export of RBP-J to tubulin fibers and downregulates Notch-mediated transcription. In this study, we found that RITA overexpression increased protein expression of p53 and Fbxw7 and downregulated the expression of cyclin D1, cyclin E, CDK2, Hes-1 and NF-κB p65. These changes led to growth inhibition and induced G0/G1 cell cycle arrest and apoptosis in SMMC7721 and HepG2 cells. Our findings indicate that RITA exerts tumor-suppressive effects in hepatocarcinogenesis through induction of G0/G1 cell cycle arrest and apoptosis and suggest a therapeutic application of RITA in HCC.

RITA inhibits growth of human hepatocellular carcinoma through induction of apoptosis

RBP-J-interacting and tubulin-associated (RITA) is a novel RBP-J-interacting protein that downregulates Notch-mediated transcription. The current study focuses on the antitumor effect of RITA in human hepatocellular carcinoma (HCC) and aims to explore its molecular mechanism. Thirty paired HCC and adjacent non-tumoral liver samples were analyzed by real-time quantitative reverse transcriptase polymerase chain reaction (qRT-PCR). RITA overexpression was induced by transfection of a pcDNA3.1-Flag-RITA plasmid into HepG2 cells. RITA knockdown was achieved by siRNA transfection. mRNA and protein expression of target genes were quantified by qRT-PCR and Western blotting, respectively. Cell proliferation and apoptosis were measured using MTT assay and flow cytometry. Our results demonstrate that adjacent nontumoral liver samples exhibited increased RITA expression compared to HCC tissues (p < 0.05); RITA levels were associated with tumor differentiation status. Overexpression of RITA suppressed cell proliferation and promoted early apoptosis, while its silencing promoted cell growth dramatically (p < 0.05). RITA overexpression upregulated p53 and reduced cyclin E levels, whereas silencing of RITA had the opposite effect on p53 and cyclin E expression. Our in vitro results represent the first evidence that RITA might suppress tumor growth and induce apoptosis in HCCs, and may be a potent antitumoral agent for HCC treatment that deserves further exploration.

Effect of mesenchymal stem cells and a novel curcumin derivative on Notch1 signaling in hepatoma cell line

This study was conducted to evaluate the effect of mesenchymal stem cells (MSCs) and a novel curcumin derivative (NCD) on HepG2 cells (hepatoma cell line) and to investigate their effect on Notch1 signaling pathway target genes. HepG2 cells were divided into HepG2 control group, HepG2 cells treated with MSC conditioned medium (MSCs CM), HepG2 cells treated with a NCD, HepG2 cells treated with MSCs CM and NCD, and HepG2 cells treated with MSCs CM (CM of MSCs pretreated with a NCD). Expression of Notch1, Hes1, VEGF, and cyclin D1 was assessed by real-time, reverse transcription-polymerase chain reaction (RT-PCR) in HepG2 cells. In addition, HepG2 proliferation assay was performed in all groups. Notch1 and its target genes (Hes1 and cyclin D1) were downregulated in all treated groups with more suppressive effect in the groups treated with both MSCs and NCD. Also, treated HepG2 cells showed significant decrease in cell proliferation rate. These data suggest that modulation of Notch1 signaling pathway by MSCs and/or NCD can be considered as a therapeutic target in HCC.

Notch1 and Notch4 are markers for poor prognosis of hepatocellular carcinoma

BACKGROUND

Notch signaling is critical to physiologic angiogenesis and has been implicated in tumor angiogenesis and metastasis. Notch signaling was reported to exert either oncogenic or tumor-suppressive function in hepatocellular carcinoma (HCC) tumorigenesis. However, the prognostic significance of Notch receptors in HCC remains uncertain. In this study, we investigated the roles of Notch receptors in the prognosis of HCC.

METHODS

We investigated the expressions of Notch receptors in tumor tissue microarrays of 288 patients with primary HCC who had undergone curative resection using immunohistochemistry. Additionally, prognostic factors of HCC were examined by univariate and multivariate analyses. The median follow-up period was 97.1 months. Tumor recurrence was detected in 189 patients (65.6%), and 99 (34.4%) died of HCC.

RESULTS

Cytoplasmic expression of Notch1, cytoplasmic expression of Notch3, coexistent nuclear expression of Notch3, and cytoplasmic Notch4 overexpression were observed in 145 (50.3%), 60 (20.8%), 17 (5.9%), and 172 (59.7%) of the 288 HCCs, respectively. Multivariate analyses revealed that Notch1 expression (P=0.029), Edmondson grade III (P=0.038), and higher BCLC stage (P<0.001) were independent predictors of shorter disease-free survival. Cytoplasmic Notch3 expression tended to be an independent predictor of shorter disease-free survival (P=0.055). Notch1 expression (P=0.039), Notch4 overexpression (P=0.012), and higher BCLC stage (P<0.001) were independent predictors of shorter disease-specific survival. On univariate analysis, Notch1 expression tended to show an unfavorable influence on disease-specific survival (P=0.063) and Notch4 overexpression did not show an unfavorable influence on disease-specific survival (P=0.103).

CONCLUSIONS

Notch1 expression might be an independent predictor of both shorter disease-free survival and shorter disease-specific survival in HCC patients after curative resection. Notch4 overexpression might be an independent predictor of shorter disease-specific survival. Notch1 could be used as an immunohistochemical biomarker to detect patients with a high-risk of recurrence. Notch1 and Notch4 could be used as immunohistochemical biomarkers to detect patients with a shorter disease-specific survival.

The down-regulation of Notch1 inhibits the invasion and migration of hepatocellular carcinoma cells by inactivating the cyclooxygenase-2/Snail/E-cadherin pathway in vitro

BACKGROUND

The Notch signaling pathway plays an important role in cancer, but the mechanism by which Notch1 participates in invasion and migration of hepatocellular carcinoma (HCC) cells is unclear.

AIMS

Our purpose is to confirm the anti-invasion and anti-migration effects of the down-regulation of Notch1 in HCC cells.

METHODS

The invasion and migration capacities of HCC cells were detected with Transwell cell culture chambers. The expressions of Notch1, Notch1 intracellular domain (N1ICD), E-cadherin, Snail, and cyclooxygenase-2 (COX-2) were analyzed by RT-PCR and/or western blotting. Notch1 and Snail were down-regulated by RNA interference, and COX-2 was inhibited by NS-398. Cell apoptosis was analyzed by MTT and flow cytometry.

RESULTS

In HCC cells, Snail, Notch1, and COX-2 were up-regulated, and E-cadherin was down-regulated in mRNA and/or protein levels. The down-regulation of Snail or Notch1 or the inhibition of COX-2, respectively, can increase the mRNA and protein expressions of E-cadherin and decrease the invasion and migration capabilities of HCC cell. Down-regulated Notch1 or inhibited COX-2 can reduce the mRNA and protein expressions of Snail. The down-regulation of Notch1 can also reduce the protein expression of COX-2. However, exogenous PGE2 can reverse the role of down-regulated Notch1. The results of MTT and flow cytometry showed that down-regulated Notch1 did not affect HCC cell viability.

CONCLUSIONS

Down-regulated Notch1 may be an effective approach to inactivating Snail/E-cadherin by regulating COX-2, which results in inhibiting the invasion and migration of HCC cells. The inhibitory effects of down-regulated Notch1 on cell invasion and migration were independent of apoptosis.

Deregulation of signalling pathways in prognostic subtypes of hepatocellular carcinoma: novel insights from interspecies comparison

Hepatocellular carcinoma is a frequent and fatal disease. Recent researches on rodent models and human hepatocarcinogenesis contributed to unravel the molecular mechanisms of hepatocellular carcinoma dedifferentiation and progression, and allowed the discovery of several alterations underlying the deregulation of cell cycle and signalling pathways. This review provides an interpretive analysis of the results of these studies. Mounting evidence emphasises the role of up-regulation of RAS/ERK, P13K/AKT, IKK/NF-kB, WNT, TGF-ß, NOTCH, Hedgehog, and Hippo signalling pathways as well as of aberrant proteasomal activity in hepatocarcinogenesis. Signalling deregulation often occurs in preneoplastic stages of rodent and human hepatocarcinogenesis and progressively increases in carcinomas, being most pronounced in more aggressive tumours. Numerous changes in signalling cascades are involved in the deregulation of carbohydrate, lipid, and methionine metabolism, which play a role in the maintenance of the transformed phenotype. Recent studies on the role of microRNAs in signalling deregulation, and on the interplay between signalling pathways led to crucial achievements in the knowledge of the network of signalling cascades, essential for the development of adjuvant therapies of liver cancer. Furthermore, the analysis of the mechanisms involved in signalling deregulation allowed the identification of numerous putative prognostic markers and novel therapeutic targets of specific hepatocellular carcinoma subtypes associated with different biologic and clinical features. This is of prime importance for the selection of patient subgroups that are most likely to obtain clinical benefit and, hence, for successful development of targeted therapies for liver cancer.

The significance of Notch1 compared with Notch3 in high metastasis and poor overall survival in hepatocellular carcinoma

BACKGROUND

The prognosis for patients with hepatocellular carcinoma (HCC) is poor, and the mechanisms underlying the development of HCC remain unclear. Notch1 and Notch3 may be involved in malignant transformation, although their roles remain unknown.

MATERIALS AND METHODS

HCC tissues were stained with anti-Notch1 or -Notch3 antibody. The migration and invasion capacities of the cells were measured with transwell cell culture chambers. RT-PCR was used to measure the expression of Notch1 and Notch3 mRNA. Additionally, western blot analysis was used to assess the protein expression of Notch1, Notch3, CD44v6, E-cadherin, matrix metalloproteinase-2 (MMP-2), MMP-9, and urokinase-type plasminogen activator (uPA). RNA interference was used to down-regulate the expression of Notch1 and Notch3. Cell viability was assessed using MTT.

RESULTS

Based on immunohistochemistry, high Notch1 expression was correlated with tumor size, tumor grade, metastasis, venous invasion and AJCC TNM stage. High Notch3 expression was only strongly correlated with metastasis, venous invasion and satellite lesions. Kaplan-Meier curves demonstrated that patients with high Notch1 or Notch3 expression were at a significantly increased risk for shortened survival time. In vitro, the down-regulation of Notch1 decreased the migration and invasion capacities of HCC cells by regulating CD44v6, E-cadherin, MMP-2, MMP-9, and uPA via the COX-2 and ERK1/2 pathways. Down-regulation of Notch3 only decreased the invasion capacity of HCC cells by regulating MMP-2 and MMP-9 via the ERK1/2 pathway.

CONCLUSIONS

Based on the migration and invasion of HCC, we hypothesize that targeting Notch1 may be more useful than Notch3 for designing novel preventive and therapeutic strategies for HCC in the near future.

Instigation of Notch signaling in the pathogenesis of Kaposi's sarcoma-associated herpesvirus and other human tumor viruses

The Notch pathway is a highly conserved signaling circuit with a critical role in cell-fate determination and tumor initiation. Notch is reported to regulate various key events in tumor progression, such as angiogenesis, maintenance of cancer stem cells, resistance to therapeutic agents and metastasis. This review describes the intimate interplay of human tumor viruses with the Notch signaling pathway. Special attention is paid to Kaposi's sarcoma-associated herpesvirus, the etiological agent of Kaposi's sarcoma and rare lymphoproliferative disorders. The past decade of active research has led to significant advances in understanding how Kaposi's sarcoma-associated herpesvirus exploits the Notch pathway to regulate its replication phase and to modulate the host cellular microenvironment to make it more favorable for viral persistence and spreading.

CHD1L Is a Marker for Poor Prognosis of Hepatocellular Carcinoma after Surgical Resection

BACKGROUND

The gene for chromodomain helicase/ATPase DNA binding protein 1-like (CHD1L) was recently identified as a target oncogene within the 1q21 amplicon, which occurs in 46% to 86% of primary hepatocellular carcinoma (HCC) cases. However, the prognostic significance of CHD1L in HCC remains uncertain. In this study, we investigated the roles of CHD1L in the prognosis of HCC.

METHODS

We investigated the expressions of CHD1L in tumor tissue microarrays of 281 primary HCC patients who underwent surgical resection using immunohistochemistry. Prognostic factors of HCC were examined by univariate and multivariate analyses. The median follow-up period was 75.6 months.

RESULTS

CHD1L expression was observed in 48 of the 281 HCCs (17.1%). CHD1L expression was associated with a younger age (p=0.033), higher Edmondson grade (p=0.019), microvascular invasion (p<0.001), major portal vein invasion (p=0.037), higher American Joint Committee on Cancer T stage (p=0.001), lower albumin level (p=0.047), and higher α-fetoprotein level (p=0.002). Multivariate analyses revealed that CHD1L expression (p=0.027), Edmondson grade III (p=0.034), and higher Barcelona Clinic Liver Cancer stage (p<0.001) were independent predictors of shorter disease-free survival.

CONCLUSIONS

CHD1L expression might be a prognostic marker of shorter disease-free survival in HCC patients after surgical resection.

FAM172A induces S phase arrest of HepG2 cells via Notch 3

Our previous results revealed that FAM172A was significantly downregulated in liver tissue from hepatocellular carcinoma or cirrhotic patients. The present study was designed to elucidate the regulatory role of FAM172A in HepG2 cells. In order to determine the expression of the FAM172A protein, western blot analysis was performed. Confocal laser scanning technique was used to observe the localization of FAM172A in HepG2 cells. Surface plasmon resonance experiments were used to determine the binding activity of FAM172A and active single sugar and Ca2+. The cell cycle progression of HepG2 cells was assessed by flow cytometry. The FAM172A protein was localized in the endoplasmic reticulum of HepG2 cells. This protein was moderately expressed in normal liver tissue, but was significantly decreased in liver tissue of patients with chronic hepatitis B When co-cultured with the FAM172A recombinant protein, HepG2 cells exhibited complete cell cycle arrest in the S phase at a high concentration (100 ng/ml). Proliferation of HepG2 cells treated with the FAM172A recombinant protein was prominently inhibited compared with that of the control cells. Western blot analysis showed that upregulation of Notch 3 and cyclin E may be related with the cell cycle control. Our results indicate that FAM172A may be a novel tumor-suppressor gene, which plays an important role in cell cycle control and tumor cell proliferation. G1/S phase arrest may be mediated, at least partially, by the Notch 3 signaling pathway.

GSI-I has a better effect in inhibiting hepatocellular carcinoma cell growth than GSI-IX, GSI-X, or GSI-XXI

Current studies are ongoing to find new drugs for the treatment of hepatocellular carcinoma (HCC). The discovery of drugs depends on the identification of molecules that can play essential roles in the development of liver cancer, for example, Notch pathway molecules. γ-Secretase inhibitors (GSIs) can inhibit the cleavage of intramembranous substrates of all Notch receptors and subsequently suppress Notch signaling. However, whether the inhibition of the Notch pathway can suppress or promote HCC growth is still under debate. In this study, we examined the expression of Notch pathway molecules in 20 pairs of HCC tissue with their normal counterparts and a panel of eight HCC cell lines. We also determined the effects of different types of GSI treatments on the cell growth of those HCC cell lines. Our results showed that the molecules of the Notch pathway were expressed in six of the eight HCC cell lines. Those six HCC cell lines were more sensitive to GSI-I treatment than the nonexpression ones. Among the four inhibitors, GSI-X and GSI-XXI exerted no effect on HCC cells growth at all. GSI-IX inhibited the growth of four HCC cell lines at 40 μmol/l. In contrast, most of these HCC cell lines were susceptible to a low concentration of GSI-I (1.2 μmol/l) treatment. The suppressive effect of GSI-I on cell growth was because of the inhibition of C-Myc, a Notch target gene. In addition, 80% (16/20) of the specimens showed either an increased expression of at least one Notch receptor or an augmented expression of Jagged1 compared with their normal counterparts. Our study reports for the first time that different kinds of GSIs can block the growth of several HCC cell lines. Our finding suggests that GSI-I is a potential chemical reagent and warrants additional testing in liver cancer therapeutics.

The Notch1/cyclooxygenase-2/Snail/E-cadherin pathway is associated with hypoxia-induced hepatocellular carcinoma cell invasion and migration

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide; however, the prognosis of HCC patients remains poor. This poor prognosis is mainly attributed to the high rate of intrahepatic and distant metastasis. HCC often occurs in a hypoxic environment and hypoxia can activate metastatic programs, ultimately leading to tumor recurrence or metastasis. Thus, the discovery and subsequent development of novel agents to block HCC invasion and migration are the primary objectives of hepatic cancer research. The Notch1 signaling pathway might be involved in hypoxia-induced carcinoma metastasis. However, the mechanisms by which Notch1 mediates cell metastasis, particularly in hepatocellular carcinoma, are not yet entirely clear. The results of the present study show that hypoxia increases the invasion and migration capacities of different HCC cells. Activation of the Notch1 signaling pathway contributes to hypoxia-induced invasion and migration in HCC cells. The activated Notch1 signaling pathway can regulate Snail/E-cadherin through cyclooxygenase-2 (COX-2) under hypoxic conditions. The above results suggest that the Notch1/COX-2/Snail/E-cadherin pathway is possibly associated with hypoxia-induced invasion and migration in HCC cells. Thus, targeting Notch1 may be useful for devising novel preventive and therapeutic strategies for HCC.

Notch1 activation contributes to tumor cell growth and proliferation in human hepatocellular carcinoma HepG2 and SMMC7721 cells

Notch signaling controls cellular differentiation and proliferation. Recent studies have shown that Notch signaling plays an important role in the carcinogenesis and progression of a growing number of malignant tumors. We investigated the effect of Notch1 activation on human hepatocellular carcinoma (HCC). In five human HCC cell lines, it was found that SMMC7721 had relatively high while HepG2 relatively low expression of Notch1 and the activity of Notch signaling. Notch1 activation by transfection of active intracellular region of Notch1 (ICN1) into HCC HepG2 cells enhanced cell growth and proliferation, including in vitro single cell colony formation, anchorage-independent proliferation, and in vivo tumorigenicity. Notch1 activation also promoted HepG2 cell cycle progression. Suppression of Notch1 activation by RNAi of Notch1 or by γ-secretase inhibitor (GSI) in HCC SMMC7721 cells decreased cell growth capability and blocked cell cycle progression. Moreover, it was found that suppression of Notch1 activation induced SMMC7721 cell apoptosis, as demonstrated by apoptosis assays. These findings indicate that Notch1 activation promotes human HCC cell growth and proliferation, which may contribute to the progression of this type of malignant carcinoma.

Adult hepatoblastoma: learning from children

Hepatoblastoma is the most common malignant liver tumour in infants and young children. Its occurrence in the adult population is debated and has been questioned. The aim of this paper is to review the histological and clinical features of adult hepatoblastoma as described in the adult literature, and to compare the findings with those of paediatric hepatoblastoma. The developmental and molecular aspects of hepatoblastoma are reviewed and their potential contribution to diagnosis of adult hepatoblastoma discussed. Case reports of adult hepatoblastoma identified by a PubMed search of the English, French, German, Italian, and Spanish literature through March 2011 were reviewed. Forty-five cases of hepatoblastoma were collected. Age at presentation was variable. Survival was uniformly poor, except for the rare patients who presented with the relatively differentiated, foetal type. The common denominator between adult and paediatric cases is the occurrence of embryonal or immature aspect of the tumours. Whether the adult cases of hepatoblastoma represent blastemal tumours, stem cell tumours, or unusual differentiation patterns in otherwise more frequent adult liver tumours remains to be established. Adult tumours labelled as hepatoblastoma are characterised by malignant appearing mesenchymal components. Surgical management is the cornerstone of therapy in children and also appears to confer an improved prognosis in adults. Whether adult hepatoblastoma exists, remains controversial. Indeed, several features described in adult cases are markedly different from hepatoblastoma as it is understood in children, and other differential diagnoses should also be entertained. Nonetheless, hepatoblastoma should be considered in adults presenting with primary liver tumours in the absence of pre-existing liver disease. Adult and paediatric patients with immature hepatoblastoma appear to have worse outcomes, and adults presenting with presumed hepatoblastoma have an overall poorer prognosis than children with hepatoblastoma. In all patients, surgery should be the treatment of choice, neoadjuvant chemotherapy is advisable.

Targeted therapy for hepatocellular carcinoma: novel agents on the horizon

Hepatocellular carcinoma (HCC) is the most common liver cancer, accounting for 90% of primary liver cancers. In the last decade it has become one of the most frequently occurring tumors worldwide and is also considered to be the most lethal of the cancer systems, accounting for approximately one third of all malignancies. Although the clinical diagnosis and management of early-stage HCC has improved significantly, HCC prognosis is still extremely poor. Furthermore, advanced HCC is a highly aggressive tumor with a poor or no response to common therapies. Therefore, new effective and well-tolerated therapy strategies are urgently needed. Targeted therapies have entered the field of anti-neoplastic treatment and are being used on their own or in combination with conventional chemotherapy drugs. Molecular-targeted therapy holds great promise in the treatment of HCC. A new therapeutic opportunity for advanced HCC is the use of sorafenib (Nexavar). On the basis of the recent large randomized phase III study, the Sorafenib HCC Assessment Randomized Protocol (SHARP), sorafenib has been approved by the FDA for the treatment of advanced HCC. Sorafenib showed to be able to significantly increase survival in patients with advanced HCC, establishing a new standard of care. Despite this promising breakthrough, patients with HCC still have a dismal prognosis, as it is currently the major cause of death in cirrhotic patients. Nevertheless, the successful results of the SHARP trial underscore the need for a comprehensive understanding of the molecular pathogenesis of this devastating disease. In this review we summarize the most important studies on the signaling pathways implicated in the pathogenesis of HCC, as well as the newest emerging drugs and their potential use in HCC management.

The biology of cancer stem cells and its clinical implication in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a highly malignant tumor with limited treatment options in its advanced state. The molecular mechanisms underlying HCC remain unclear because of the complexity of its multi-step development process. Cancer stem cells (CSCs) are defined as a small population of cells within a tumor that possess the capability for self-renewal and the generation of heterogeneous lineages of cancer cells. To date, there have been two theories concerning the mechanism of carcinogenesis, i.e., the stochastic (clonal evolution) model and the hierarchical (cancer stem cell-driven) model. The concept of the CSC has been established over the past decade, and the roles of CSCs in the carcinogenic processes of various cancers, including HCC, have been emphasized. Previous experimental and clinical evidence indicated the existence of liver CSCs; however, the potential mechanistic links between liver CSCs and the development of HCC in humans are not fully understood. Although definitive cell surface markers for liver CSCs have not yet been found, several putative markers have been identified, which allow the prospective isolation of CSCs from HCC. The identification and characterization of CSCs in HCC is essential for a better understanding of tumor initiation or progression in relation to signaling pathways. These markers could be used along with clinical parameters for the prediction of chemoresistance, radioresistance, metastasis and survival and may represent potential targets for the development of new molecular therapies against HCC. This review describes the current evidence for the existence and function of liver CSCs and discuss the clinical implications of CSCs in patients demonstrating resistance to conventional anti-cancer therapies, as well as clinical outcomes. Such data may provide a future perspective for targeted therapy in HCC.

Clinicopathological significance of altered Notch signaling in extrahepatic cholangiocarcinoma and gallbladder carcinoma

AIM: To investigate the role and clinicopathological significance of aberrant expression of Notch receptors and Delta-like ligand-4 (DLL4) in extrahepatic cholangiocarcinoma and gallbladder carcinoma.

METHODS: One hundred and ten patients had surgically resected extrahepatic cholangiocarcinoma (CC) and gallbladder carcinoma specimens examined by immunohistochemistry of available paraffin blocks. Immunohistochemistry was performed using anti-Notch receptors 1-4 and anti-DLL4 antibodies. We scored the immunopositivity of Notch receptors and DLL4 expression by percentage of positive tumor cells with cytoplasmic expression and intensity of immunostaining. Coexistent nuclear localization was evaluated. Clinicopathological parameters and survival data were compared with the expression of Notch receptors 1-4 and DLL4.

RESULTS: Notch receptor proteins showed in the cytoplasm with or without nuclear expression in cancer cells, as well as showing weak cytoplasmic expression in non-neoplastic cells. By semiquantitative evaluation, positive immunostaining of Notch receptor 1 was detected in 96 cases (87.3%), Notch receptor 2 in 97 (88.2%), Notch receptor 3 in 97 (88.2%), Notch receptor 4 in 103 (93.6), and DLL4 in 84 (76.4%). In addition, coexistent nuclear localization was noted [Notch receptor 1; 18 cases (18.8%), Notch receptor 2; 40 (41.2%), Notch receptor 3; 32 (33.0%), Notch receptor 4; 99 (96.1%), DLL4; 48 (57.1%)]. Notch receptor 1 expression was correlated with advanced tumor, node, metastasis (TNM) stage (P = 0.043), Notch receptor 3 with advanced T stage (P = 0.017), tendency to express in cases with nodal metastasis (P = 0.065) and advanced TNM stage (P = 0.052). DLL4 expression tended to be related to less histological differentiation (P = 0.095). Coexistent nuclear localization of Notch receptor 3 was related to no nodal metastasis (P = 0.027) and Notch receptor 4 with less histological differentiation (P = 0.036), while DLL4 tended to be related inversely with T stage (P = 0.053). Coexistent nuclear localization of DLL4 was related to poor survival (P = 0.002).

CONCLUSION: Aberrant expression of Notch receptors 1 and 3 play a role during cancer progression, and cytoplasmic nuclear coexistence of DLL4 expression correlates with poor survival in extrahepatic CC and gallbladder carcinoma.

Notch signalling is off and is uncoupled from HES1 expression in Ewing's sarcoma

Notch can act as an oncogene or as a tumour suppressor and thus can either promote or inhibit tumour cell growth. To establish Notch status in Ewing's sarcoma family of tumours (ESFT), we investigated the Notch pathway by gene expression profiling meta-analysis or immunohistochemistry in samples obtained from 96 and 24 ESFT patients, respectively. We found that although Notch receptors were highly expressed, Notch did not appear to be active, as evidenced by the absence of Notch receptors in cell nuclei. In contrast, we show that Notch receptors known to be active in colon adenocarcinoma, hepatocarcinoma, and pancreatic carcinoma stain cell nuclei in these tumours. High expression of the Notch effector HES1 transcription factor, usually used as a surrogate marker for active Notch, was also restricted to outside of the nucleus in the majority of ESFT, and analysis of HES1 gene targets indicated HES1 to be transcriptionally inactive. Neither forced activation nor pharmacological or genetic blocking of Notch affected HES1 expression in ESFT cells, indicating HES1 expression to be uncoupled from the Notch pathway. Additional functional studies in ESFT cell lines confirmed Notch to be switched off. Finally, unlike experiments in which HES1 expression was modulated, experimental activation of Notch in ESFT cell lines via several means blocked cell proliferation and reduced their clonogenic potential in soft agar. These indicate that HES1 is uncoupled from Notch in ESFT, that EWS-FLI1-mediated inhibition of Notch contributes to ESFT aggressive cell growth, and support a role for Notch in ESFT tumour suppression, at least partly through the Notch effector HEY1.

Hepatitis C virus NS3 protein can activate the Notch-signaling pathway through binding to a transcription factor, SRCAP

Persistent infections of hepatitis C virus (HCV) are known to be a major risk factor for causing hepatocellular carcinomas. Nonstructural protein 3 (NS3) of HCV has serine protease and RNA helicase domains, and is essential for the viral replication. Further, NS3 is also considered to be involved in the development of HCV-induced hepatocellular carcinomas. In this report, we focus on the function of NS3 protein, and propose a novel possible molecular mechanism which is thought to be related to the tumorigenesis caused by the persistent infection of HCV. We identified SRCAP (Snf2-related CBP activator protein) as a NS3 binding protein using yeast two-hybrid screening, and a co-immunoprecipitation assay demonstrated that NS3 can bind to SRCAP in mammalian cells. The results of a reporter gene assay using Hes-1 promoter which is known to be a target gene activated by Notch, indicate that NS3 and SRCAP cooperatively activate the Hes-1 promoter in Hep3B cells. In addition, we show in this report that also p400, which is known as a protein closely resembling SRCAP, would be targeted by NS3. NS3 exhibited binding activity also to the 1449–1808 region of p400 by a co-immunoprecipitation assay, and further the activation of the Notch-mediated transcription of Hes-1 promoter by NS3 decreased significantly by the combined silencing of SRCAP and p400 mRNA using short hairpin RNA. These results suggest that the HCV NS3 protein is involved in the activation of the Notch-signaling pathway through the targeting to both SRCAP and p400.