Notch signaling in hepatocellular carcinoma: molecular targeting in an advanced disease

Cellular, Molecular and Proteomic Characteristics of Early Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) accounts for the majority of primary liver cancers. Early detection/diagnosis is vital for the prognosis of HCC, whereas diagnosis at late stages is associated with very low survival rate. Early diagnosis is based on 6-month surveillance of the patient and the use of at least two imaging modalities. The aim of this study was to investigate diagnostic markers for the detection of early HCC based on proteome analysis, microRNAs (miRNAs) and circulating tumor cells (CTCs) in the blood of patients with cirrhosis or early or advanced HCC. We studied 89 patients with HCC, of whom 33 had early HCC and 28 were cirrhotic. CTCs were detected by real-time quantitative reverse transcription PCR and immunofluorescence using the markers epithelial cell adhesion molecule (EPCAM), vimentin, alpha fetoprotein (aFP) and surface major vault protein (sMVP). Expression of the five most common HCC-involved miRNAs (miR-122, miR-200a, miR-200b, miR-221, miR-222) was examined in serum using quantitative real time PCR (qRT-PCR). Finally, patient serum was analyzed via whole proteome analysis (LC/MS). Of 53 patients with advanced HCC, 27 (51%) had detectable CTCs. Among these, 10/27 (37%) presented evidence of mesenchymal or intermediate stage cells (vimentin and/or sMVP positive). Moreover, 5/17 (29%) patients with early HCC and 2/28 (7%) cirrhotic patients had detectable CTCs. Patients with early or advanced HCC exhibited a significant increase in miR-200b when compared to cirrhotic patients. Our proteome analysis indicated that early HCC patients present a significant upregulation of APOA2, APOC3 proteins when compared to cirrhotic patients. When taken in combination, this covers the 100% of the patients with early HCC. miR-200b, APOA2 and APOC3 proteins are sensitive markers and can be potentially useful in combination for the early diagnosis of HCC.

Elucidating the Molecular Basis of Sorafenib Resistance in HCC: Current Findings and Future Directions

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related mortality worldwide. Sorafenib is the first multi-tyrosine kinase inhibitor approved for HCC and it has represented the standard of care for advanced HCC for almost 10 years, offering a survival benefit when compared to placebo. However, this benefit is limited, showing rare objective responses and a disease control rate approaching 50–60%, with most patients experiencing disease progression at 6 months. These scant results dictate the urgent need for strategies to overcome both primary and acquired resistance. Herein we report several mechanisms supporting resistance to sorafenib in HCC patients, including activation of oncogenic pathways. Among these, the AKT/mTOR pathway plays a crucial role being at the crossroad of multiple driving events. Autophagy, multidrug-resistant phenotype, hypoxia-related mechanisms and endoplasmic reticulum stress are gaining more and more relevance as crucial events driving the response to anticancer drugs, including sorafenib. Several HCC-specific miRNAs take part to the regulation of these cellular processes. Remarkably, molecularly targeted strategies able to overcome resistance in these settings have also been reported. So far, the vast majority of data has been derived from laboratory studies, which means the need for an extensive validation. Indeed, most of the possible drug associations displaying promising effects in improving sorafenib efficacy herein described derive from preclinical explorations. Notably, data obtained in animal models can be inconsistent with regard to the human disease for efficacy, safety, side effects, best formulation and pharmacokinetics. However, they represent the necessary preliminary step to improve the management of advanced HCC.

Inhibition of NOTCH signaling pathway chemosensitizes HCC CD133+ cells to vincristine and 5-fluorouracil through upregulation of BBC3

In hepatocellular carcinoma (HCC), the poor response to the chemotherapeutic agents is partially attributed to the chemoresistance property of cancer stem cells (CSCs). NOTCH signaling pathway plays a crucial role in the chemoresistance through the maintenance of the CSCs. We observed that the NOTCH pathway was activated in HCC CD133⁺ cells treated with vincristine (VIN)¹ and 5-fluorouracil (5-FU)². Therefore, we examined whether inhibition of the NOTCH can improve sensitization of HCC CD133⁺ cells to VIN and 5-FU. The Huh7 cell line was pre-incubated γ-secretase DAPT, as a NOTCH inhibitor, and then treated with IC₅₀ dose of VIN or 5-FU. The CD133⁺ cells were then isolated and analyzed for the cell viability, apoptosis, migration and spheroid formation capacities, and gene and protein expression. It was observed that pre-incubation with DAPT significantly downregulated the expression of NOTCH-related genes and led to a significant reduction in VIN- and 5-FU-CD133⁺ population. In addition, DAPT pre-incubated VIN- and 5-FU-treated-CD133⁺ cells formed fewer spheroids in 3D culture and had a lesser migration capacity in 2D culture. Importantly, DAPT enhanced the apoptosis rate of VIN- and 5-FU-treated CD133⁺ cells for 3- and 2-fold, which was correlated with the enhanced expression of pro-apoptotic BBC3 (BCL-2-binding component 3) and decreased expression of HES1 that was reported to regulate BBC3 negatively. Collectively, it was observed that NOTCH inhibition sensitized the HCC CD133⁺ cells to VIN and 5-FU through enhancing BBC3-mediated apoptosis. The results highlighted the role of NOTCH/HES1/BBC3 axis in resistance of CD133⁺ cells to VIN and 5-FU. Understanding the molecular mechanisms underlying chemoresistance in HCC CD133⁺ cells may help in designing the novel targeted therapies to chemosensitize them.

Increased Expression of Fibulin-1 Is Associated With Hepatocellular Carcinoma Progression by Regulating the Notch Signaling Pathway

Fibulin-1, a component of the extracellular matrix (ECM), its prognostic, pathophysiologic and diagnostic role in hepatocellular carcinoma (HCC) is still unexplored. We first found that either Fibulin-1 messenger RNA (mRNA) or protein level was highly elevated in HCC tissues compared with normal tissues. Fibulin-1 correlated with poor overall survival, and it was an independent prognostic predictor (p = 0.001). Furthermore, Overexpression or inhibition of Fibulin-1 reduced or sensitized HCC cells to apoptotic signals, and Fibulin-1 silencing suppressed the ability of HCC cells to form tumors in vivo. Moreover, Fibulin-1 inhibited apoptosis via the Notch pathway while Fibulin-1 silencing had no obvious effect on p-MAPK, p-c-jun and p-stat3 expression, and both Mcl-1 and Bcl-xL are targets of Fibulin-1. Furthermore, the stromal and immune score was elevated in high Fibulin-1 tissues, and FBLN1 expression was associated with increased infiltrating macrophages using xCell, TIMER and TISDIB tool based on TCGA HCC database. Importantly, the circulating cell-free RNA (cfRNA) level of Fibulin-1 in the serum were significantly increased in patients with HCC compared with those in healthy controls, individuals with chronic hepatitis B and patients with HBV-induced liver cirrhosis. The area under receiver operating characteristic curves (AUC) was 0.791 for Fibulin-1, 0.640 for α-fetoprotein and 0.868 for the combination of the two tumor markers. Our findings indicate that Fibulin-1 may be a potential prognostic indicator, a promising serum biomarker and a therapeutic target in patients with HCC.

The basics of epithelial-mesenchymal transition (EMT): A study from a structure, dynamics, and functional perspective

Epithelial-mesenchymal transition (EMT) is a key step in transdifferentiation process in solid cancer development. Forthcoming evidence suggest that the stratified program transforms polarized, immotile epithelial cells to migratory mesenchymal cells associated with enhancement of breast cancer stemness, metastasis, and drug resistance. It involves primarily several signaling pathways, such as transforming growth factor-β (TGF-β), cadherin, notch, plasminogen activator protein inhibitor, urokinase plasminogen activator, and WNT/beta catenin pathways. However, current understanding on the crosstalk of multisignaling pathways and assemblies of key transcription factors remain to be explored. In this review, we focus on the crosstalk of signal transduction pathways linked to the current therapeutic and drug development strategies. We have also performed the computational modeling on indepth the structure and conformational dynamic studies of regulatory proteins and analyze molecular interactions with their associate factors to understand the complicated process of EMT in breast cancer progression and metastasis. Electrostatic potential surfaces have been analyzed that help in optimization of electrostatic interactions between the protein and its ligand. Therefore, understanding the biological implications underlying the EMT process through molecular biology with biocomputation and structural biology approaches will enable the development of new therapeutic strategies to sensitize tumors to conventional therapy and suppress their metastatic phenotype.

Evaluation of the role of Notch1 expression in hepatic carcinogenesis with clinico-pathological correlation

The role of Notch pathway in hepatocarcinogenesis is unclear with conflicting results reported from different researchers. This study aimed to investigate the exact role of Notch1 in hepatocarcinogenesis and its influence on survival and to determine the possibility of it being a target therapy. Differential immunohistochemical expression of Notch1 in 100 cases of hepatocellular carcinoma (HCC) and adjacent non-neoplastic liver tissue was performed. The results showed that expression of Notch1 was significantly higher in the non-neoplastic hepatic tissues than in HCC tissues (p < 0.001), but there was no significant difference in Notch1 expression between cirrhotic and non-cirrhotic liver tissue (p = 0.197). Notch1 expression was higher in low grade than in high grade HCC (p = 0.036). Notch1 expression showed reverse correlation with mitotic count (p = 0.008), and necrosis (p = 0.005). The disease free survival was shorter in patients displaying low levels of Notch1 expression (p = 0.045). The overall survival showed no significant difference between high and low levels of Notch1 expression; however, it was somewhat longer in patients with high Notch1 expression (p = 0.220). In conclusion, the tumour suppressor role of Notch1 was supported and the use of Notch1 agonists may have a role in improving the prognosis of HCC.

Notch Signaling Components: Diverging Prognostic Indicators in Lung Adenocarcinoma

Non-small-cell lung cancer (NSCLC) is a lethal and aggressive malignancy. Currently, the identities of prognostic and predictive makers of NSCLC have not been fully established. Dysregulated Notch signaling has been implicated in many human malignancies, including NSCLC. However, the prognostic value of measuring Notch signaling and the utility of developing Notch-targeted therapies in NSCLC remain inconclusive. The present study investigated the association of individual Notch receptor and ligand levels with lung adenocarcinoma (ADC) and squamous cell carcinoma (SCC) prognosis using the Kaplan-Meier plotte database. This online database encompasses 2437 lung cancer samples. Hazard ratios with 95% confidence intervals were calculated. The results showed that higher Notch1, Notch2, JAG1, and DLL1 mRNA expression predicted better overall survival (OS) in lung ADC, but showed no significance in SCC patients. Elevated Notch3, JAG2, and DLL3 mRNA expression was associated with poor OS of ADC patients, but not in SCC patients. There was no association between Notch4 and OS in either lung ADC or SCC patients. In conclusion, the set of Notch1, Notch2, JAG1, DLL1 and that of Notch3, JAG2, DLL3 played opposing prognostic roles in lung ADC patients. Neither set of Notch receptors and ligands was indicative of lung SCC prognosis. Notch signaling could serve as promising marker to predict outcomes in lung ADC patients. The distinct features of lung cancer subtypes and Notch components should be considered when developing future Notch-targeted therapies.