Blockade of STAT3 activation by sorafenib derivatives through enhancing SHP-1 phosphatase activity

Spatial‒temporal heterogeneities of liver cancer and the discovery of the invasive zone

Solid tumours are intricate and highly heterogeneous ecosystems, which grow in and invade normal organs. Their progression is mediated by cancer cells' interaction with different cell types, such as immune cells, stromal cells and endothelial cells, and with the extracellular matrix. Owing to its high incidence, aggressive growth and resistance to local and systemic treatments, liver cancer has particularly high mortality rates worldwide. In recent decades, spatial heterogeneity has garnered significant attention as an unfavourable biological characteristic of the tumour microenvironment, prompting extensive research into its role in liver tumour development. Advances in spatial omics have facilitated the detailed spatial analysis of cell types, states and cell‒cell interactions, allowing a thorough understanding of the spatial and temporal heterogeneities of tumour microenvironment and informing the development of novel therapeutic approaches. This review illustrates the latest discovery of the invasive zone, and systematically introduced specific macroscopic spatial heterogeneities, pathological spatial heterogeneities and tumour microenvironment heterogeneities of liver cancer.

Discovery of imidazopyridine-pyrazoline-hybrid structure as SHP-1 agonist that suppresses phospho-STAT3 signaling in human breast cancer cells

Signal transducer and activator of transcription 3 (STAT3) promotes breast cancer malignancy and controls key processes including proliferation, differentiation, and survival in breast cancer cells. Although many methods for treating breast cancer have been improved, there is still a need to discover and develop new methods for breast cancer treatment. Therefore, we synthesized a new compound 2-(4-(2,3-dichlorophenyl)piperazin-1-yl)-1-(3-(2,6-dimethylimidazo[1,2-a]pyridin-3-yl)-5-(3-nitrophenyl)-4,5-dihydro-1H-pyrazol-1-yl)ethanone (DIP). We aimed to evaluate the anti-cancer effect of DIP in breast cancer cells and clarify its mode of action. We noted that DIP abrogated STAT3 activation and STAT3 upstream kinases janus-activated kinase (JAK) and Src kinases. In addition, DIP promoted the levels of SHP-1 protein and acts as SHP-1 agonist. Further, silencing of SHP-1 gene reversed the DIP-induced attenuation of STAT3 activation and apoptosis. DIP also induced apoptosis through modulating PARP cleavage and oncogenic proteins. Moreover, DIP also significantly enhanced the apoptotic effects of docetaxel through the suppression of STAT3 activation in breast cancer cells. Overall, our data indicated that DIP may act as a suppressor of STAT3 cascade, and it could be a new therapeutic strategy in breast cancer cells.

Sorafenib-Based Drug Delivery Systems: Applications and Perspectives

As a Food and Drug Administration (FDA)-approved molecular-targeted chemotherapeutic drug, sorafenib (SF) can inhibit angiogenesis and tumor cell proliferation, leading to improved patient overall survival of hepatocellular carcinoma (HCC). In addition, SF is an oral multikinase inhibitor as a single-agent therapy in renal cell carcinoma. However, the poor aqueous solubility, low bioavailability, unfavorable pharmacokinetic properties and undesirable side effects (anorexia, gastrointestinal bleeding, and severe skin toxicity, etc.) seriously limit its clinical application. To overcome these drawbacks, the entrapment of SF into nanocarriers by nanoformulations is an effective strategy, which delivers SF in a target tumor with decreased adverse effects and improved treatment efficacy. In this review, significant advances and design strategies of SF nanodelivery systems from 2012 to 2023 are summarized. The review is organized by type of carriers including natural biomacromolecule (lipid, chitosan, cyclodextrin, etc.); synthetic polymer (poly(lactic-co-glycolic acid), polyethyleneimine, brush copolymer, etc.); mesoporous silica; gold nanoparticles; and others. Co-delivery of SF and other active agents (glypican-3, hyaluronic acid, apolipoprotein peptide, folate, and superparamagnetic iron oxide nanoparticles) for targeted SF nanosystems and synergistic drug combinations are also highlighted. All these studies showed promising results for targeted treatment of HCC and other cancers by SF-based nanomedicines. The outlook, challenges and future opportunities for the development of SF-based drug delivery are presented.

Inhibition of stress proteins TRIB3 and STC2 potentiates sorafenib sensitivity in hepatocellular carcinoma

Sorafenib resistance is one of the main obstacles to the treatment of advanced hepatocellular carcinoma (HCC). Stress proteins TRIB3 and STC2 confer cell resistance to a variety of stresses, including hypoxia, nutritional deprivation, and other perturbations, which induce endoplasmic reticulum stress. However, the role of TRIB3 and STC2 in sorafenib sensitivity to HCC remains unclear. In this study, our results indicated that the common differentially expressed genes (DEGs) in sorafenib-treated HCC cells obtained from the NCBI-GEO database (Huh7 and Hep3B cells; GSE96796) included TRIB3, STC2, HOXD1, C2orf82, ADM2, RRM2, and UNC93A. The most significantly upregulated DEGs were TRIB3 and STC2, which were both stress protein genes. Bioinformatic analysis in NCBI public databases indicated that TRIB3 and STC2 were highly expressed in HCC tissues and closely associated with poor prognoses in HCC patients. Further investigation showed that inhibition of TRIB3 or STC2 with siRNA could enhance the anti-cancer effect of sorafenib in HCC cell lines. In conclusion, our study showed that stress proteins TRIB3 and STC2 are closely associated with sorafenib resistance in HCC. The combination of TRIB3 or STC2 inhibition and sorafenib may be a promising therapeutic strategy for HCC.

Regorafenib induces damage-associated molecular patterns, cancer cell death and immune modulatory effects in a murine triple negative breast cancer model

Damage associated molecular patterns (DAMPs), including calreticulin (CRT) exposure, high-mobility group box 1 protein (HMGB1) elevation, and ATP release, characterize immunogenic cell death (ICD) and may play a role in cancer immunotherapy. Triple negative breast cancer (TNBC) is an immunogenic subtype of breast cancer with higher lymphocyte infiltration. Here, we found that regorafenib, a multi-target angiokinase inhibitor previously known to suppress STAT3 signaling, induced DAMPs and cell death in TNBC cells. Regorafenib induced the expression of HMGB1 and CRT, and the release of ATP. Regorafenib-induced HMGB1 and CRT were attenuated following STAT3 overexpression. In a 4T1 syngeneic murine model, regorafenib treatment increased HMGB1 and CRT expression in xenografts, and effectively suppressed 4T1 tumor growth. Immunohistochemical staining revealed increased CD4⁺ and CD8⁺ tumor-infiltrating T cells in 4T1 xenografts following regorafenib treatment. Regorafenib treatment or programmed death-1 (PD-1) blockade using anti-PD-1 monoclonal antibody reduced lung metastasis of 4T1 cells in immunocompetent mice. While regorafenib increases the proportion of MHC II high expression on dendritic cells in mice with smaller tumors, the combination of regorafenib and PD-1 blockade did not show a synergistic effect on anti-tumor activity. These results suggest that regorafenib induces ICD and suppresses tumor progression in TNBC. It should be carefully evaluated when developing a combination therapy with an anti-PD-1 antibody and a STAT3 inhibitor.

Oncogenic metabolic reprogramming in breast cancer: focus on signaling pathways and mitochondrial genes

Oncogenic metabolic reprogramming impacts the abundance of key metabolites that regulate signaling and epigenetics. Metabolic vulnerability in the cancer cell is evident from the Warburg effect. The research on metabolism in the progression and survival of breast cancer (BC) is under focus. Oncogenic signal activation and loss of tumor suppressor are important regulators of tumor cell metabolism. Several intrinsic and extrinsic factors contribute to metabolic reprogramming. The molecular mechanisms underpinning metabolic reprogramming in BC are extensive and only partially defined. Various signaling pathways involved in the metabolism play a significant role in the modulation of BC. Notably, PI3K/AKT/mTOR pathway, lactate-ERK/STAT3 signaling, loss of the tumor suppressor Ras, Myc, oxidative stress, activation of the cellular hypoxic response and acidosis contribute to different metabolic reprogramming phenotypes linked to enhanced glycolysis. The alterations in mitochondrial genes have also been elaborated upon along with their functional implications. The outcome of these active research areas might contribute to the development of novel therapeutic interventions and the remodeling of known drugs.

Systemic lupus erythematosus: From non-coding RNAs to exosomal non-coding RNAs

Systemic lupus erythematosus (SLE), as an immunological illness, frequently impacts young females. Both vulnerabilities to SLE and the course of the illness's clinical symptoms have been demonstrated to be affected by individual differences in non-coding RNA expression. Many non-coding RNAs (ncRNAs) are out of whack in patients with SLE. Because of the dysregulation of several ncRNAs in peripheral blood of patients suffering from SLE, these ncRNAs to be showed valuable as biomarkers for medication response, diagnosis, and activity. NcRNAs have also been demonstrated to influence immune cell activity and apoptosis. Altogether, these facts highlight the need of investigating the roles of both families of ncRNAs in the progress of SLE. Being aware of the significance of these transcripts perhaps elucidates the molecular pathogenesis of SLE and could open up promising avenues to create tailored treatments during this condition. In this review we summarized various non-coding RNAs and Exosomal non-coding RNAs in SLE.

Role of lncRNAs in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is among the deadliest cancer in human malignancies. It is the most common and severe type of primary liver cancer. However, the molecular mechanisms underlying HCC pathogenesis remain poorly understood. Long non-coding RNAs (lncRNAs), a new kind of RNA and epigenetic factors, play a crucial role in tumorigenesis and the progression of HCC. LncRNAs are capable of promoting the autophagy, proliferation, and migration of tumor cells by targeting and modulating the expression of downstream genes in signaling pathways related to cancer; these transcripts modify the activity and expression of various tumor suppressors and oncogenes. LncRNAs could act as biomarkers for treatment approaches such as immunotherapy, chemotherapy, and surgery to effectively treat HCC patients. Improved knowledge regarding the aetiology of HCC may result from an advanced understanding of lncRNAs. Enhanced oxidative stress in the mitochondrial and Endoplasmic reticulum leads to the activation of unfolded protein response pathway that plays a crucial role in the pathophysiology of hepatocellular carcinoma. The mutual regulation between LncRNAs and Endoplasmic reticulum (ER) stress in cancer and simultaneous activation of the unfolded protein response (UPR) pathway determines the fate of tumor cells in HCC. Mitochondria-associated lncRNAs work as essential components of several gene regulatory networks; abnormal regulation of mitochondria-associated lncRNAs may lead to oncogenesis, which provides further insight into the understanding of tumorigenesis and therapeutic strategies.

Anterior gradient 2 induces resistance to sorafenib via endoplasmic reticulum stress regulation in hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) accounts for almost 80% of all liver cancer cases and is the sixth most common cancer and the second most common cause of cancer-related death worldwide. The survival rate of sorafenib-treated advanced HCC patients is still unsatisfactory. Unfortunately, no useful biomarkers have been verified to predict sorafenib efficacy in HCC.

RESULTS

We assessed a sorafenib resistance-related microarray dataset and found that anterior gradient 2 (AGR2) is highly associated with overall and recurrence-free survival and with several clinical parameters in HCC. However, the mechanisms underlying the role of AGR2 in sorafenib resistance and HCC progression remain unknown. We found that sorafenib induces AGR2 secretion via posttranslational modification and that AGR2 plays a critical role in sorafenib-regulated cell viability and endoplasmic reticulum (ER) stress and induces apoptosis in sorafenib-sensitive cells. In sorafenib-sensitive cells, sorafenib downregulates intracellular AGR2 and conversely induces AGR2 secretion, which suppresses its regulation of ER stress and cell survival. In contrast, AGR2 is highly intracellularly expressed in sorafenib-resistant cells, which supports ER homeostasis and cell survival. We suggest that AGR2 regulates ER stress to influence HCC progression and sorafenib resistance.

CONCLUSIONS

This is the first study to report that AGR2 can modulate ER homeostasis via the IRE1α-XBP1 cascade to regulate HCC progression and sorafenib resistance. Elucidation of the predictive value of AGR2 and its molecular and cellular mechanisms in sorafenib resistance could provide additional options for HCC treatment.

Roles of protein tyrosine phosphatases in hepatocellular carcinoma progression (Review)

Hepatocellular carcinoma (HCC) represents almost 80% of all liver cancers, is the sixth most common cancer and is the second‑highest cause of cancer‑related deaths worldwide. Protein tyrosine phosphatases (PTPs), which are encoded by the largest family of phosphatase genes, play critical roles in cellular responses and are implicated in various signaling pathways. Moreover, PTPs are dysregulated and involved in various cellular processes in numerous cancers, including HCC. Kinases and phosphatases are coordinators that modulate cell activities and regulate signaling responses. There are multiple interacting signaling networks, and coordination of these signaling networks in response to a stimulus determines the physiological outcome. Numerous issues, such as drug resistance and inflammatory reactions in the tumor microenvironment, are implicated in cancer progression, and the role of PTPs in these processes has not been well elucidated. Therefore, the present review focused on discussing the relationship of PTPs with inflammatory cytokines and chemotherapy/targeted drug resistance, providing detailed information on how PTPs can modulate inflammatory reactions and drug resistance to influence progression in HCC.

Comparative Analysis of the Cytotoxic Effect of a Complex of Selenium Nanoparticles Doped with Sorafenib, "Naked" Selenium Nanoparticles, and Sorafenib on Human Hepatocyte Carcinoma HepG2 Cells

Despite the use of sorafenib as one of the most effective drugs for the treatment of liver cancer, its significant limitations remain-poor solubility, the need to use high doses with the ensuing complications on healthy tissues and organs, and the formation of cell resistance to the drug. At the same time, there is more and more convincing evidence of the anticancer effect of selenium-containing compounds and nanoparticles. The aim of this work was to develop a selenium-sorafenib nanocomplex and study the molecular mechanisms of its anticancer effect on human hepatocyte carcinoma cells, where nanoselenium is not only a sorafenib transporter, but also an active compound. We have created a selenium-sorafenib nanocomplex based on selenium nanoparticles with size 100 nm. Using vitality tests, fluorescence microscopy, and PCR analysis, it was possible to show that selenium nanoparticles, both by themselves and doped with sorafenib, have a pronounced pro-apoptotic effect on HepG2 cells with an efficiency many times greater than that of sorafenib (So). "Naked" selenium nanoparticles (SeNPs) and the selenium-sorafenib nanocomplex (SeSo), already after 24 h of exposure, lead to the induction of the early stages of apoptosis with the transition to the later stages with an increase in the incubation time up to 48 h. At the same time, sorafenib, at the studied concentrations, began to exert a proapoptotic effect only after 48 h. Under the action of SeNPs and SeSo, both classical pathways of apoptosis induction and ER-stress-dependent pathways involving Ca2+ ions are activated. Thus, sorafenib did not cause the generation of Ca2+ signals by HepG2 cells, while SeNPs and SeSo led to the activation of the Ca2+ signaling system of cells. At the same time, the selenium-sorafenib nanocomplex turned out to be more effective in activating the Ca2+ signaling system of cells, inducing apoptosis and ER stress by an average of 20-25% compared to "naked" selenium nanoparticles. Our data on the mechanisms of action and the created nanocomplex are promising as a platform for the creation of highly selective and effective drugs with targeted delivery to tumors.

ABCC5 facilitates the acquired resistance of sorafenib through the inhibition of SLC7A11-induced ferroptosis in hepatocellular carcinoma

Sorafenib is a first-line molecular-target drug for advanced hepatocellular carcinoma (HCC), and reducing sorafenib resistance is an important issue to be resolved for the clinical treatment of HCC. In the current study, we identified that ABCC5 is a critical regulator and a promising therapeutic target of acquired sorafenib resistance in human hepatocellular carcinoma cells. The expression of ABCC5 was dramatically induced in sorafenib-resistant HCC cells and was remarkably associated with poor clinical prognoses. The down-regulation of ABCC5 expression could significantly reduce the resistance of sorafenib to HCC cells. Importantly, activation of PI3K/AKT/NRF2 axis was essential for sorafenib to induce ABCC5 expression. ABCC5 increased intracellular glutathione (GSH) and attenuated lipid peroxidation accumulation by stabilizing SLC7A11 protein, which inhibited ferroptosis. Additionally, the inhibition of ABCC5 enhanced the anti-cancer activity of sorafenib in vitro and in vivo. These findings demonstrate a novel molecular mechanism of acquired sorafenib resistance and also suggest that ABCC5 is a new regulator of ferroptosis in HCC cells.

MiR-125b-5p Is Involved in Sorafenib Resistance through Ataxin-1-Mediated Epithelial-Mesenchymal Transition in Hepatocellular Carcinoma

The mechanism of resistance to sorafenib in hepatocellular carcinoma (HCC) remains unclear. We analyzed miRNA expression profiles in sorafenib-resistant HCC cell lines (PLC/PRF5-R1/R2) and parental cell lines (PLC/PRF5) to identify the miRNAs responsible for resistance. Drug sensitivity, migration/invasion capabilities, and epithelial-mesenchymal transition (EMT) properties were analyzed by biochemical methods. The clinical relevance of the target genes to survival in HCC patients were assessed using a public database. Four miRNAs were significantly upregulated in PLC/PRF5-R1/-R2 compared with PLC/PRF5. Among them, miR-125b-5p mimic-transfected PLC/PRF5 cells (PLC/PRF5-miR125b) and showed a significantly higher IC50 for sorafenib compared with controls, while the other miRNA mimics did not. PLC/PRF5-miR125b showed lower E-cadherin and higher Snail and vimentin expression-findings similar to those for PLC/PRF5-R2-which suggests the induction of EMT in those cells. PLC/PRF5-miR125b exhibited significantly higher migration and invasion capabilities and induced sorafenib resistance in an in vivo mouse model. Bioinformatic analysis revealed ataxin-1 as a target gene of miR-125b-5p. PLC/PRF5 cells transfected with ataxin-1 siRNA showed a significantly higher IC50, higher migration/invasion capability, higher cancer stem cell population, and an EMT phenotype. Median overall survival in the low-ataxin-1 patient group was significantly shorter than in the high-ataxin-1 group. In conclusion, miR-125b-5p suppressed ataxin-1 and consequently induced Snail-mediated EMT and stemness, leading to a poor prognosis in HCC patients.

Circular RNA-0007059 protects cell viability and reduces inflammation in a nephritis cell model by inhibiting microRNA-1278/SHP-1/STAT3 signaling

Background

Increasing evidence has indicated that circular RNAs (circRNAs) play a role in various diseases. However, the influence of circRNAs in nephritis remains unknown.

Methods

Microarray analysis and RT-qPCR were used to detect the expression of circRNA. Type I IFN were administrated to RMC and HEK293 cells to establish a nephritis cell model. CCK-8, MTT assay, and flow cytometry were used to assess cell proliferation, viability, and apoptosis of cells. Bioinformatics analysis and dual luciferase reporter assay detect the interaction of circ_0007059, miRNA-1278, and SHP-1. Glomerulonephritis was performed in a mouse model by administration of IFNα-expressing adenovirus. IHC staining showed the pathogenic changes.

Results

In the present study, the expression of circ_0007059 in type I interferon (IFN)-treated renal mesangial cells (RMCs), lupus nephritis (LN) specimens, and HEK293 cells was downregulated compared with that in normal healthy samples and untreated cells. Circ_0007059 overexpression resulted in increased cell proliferation, cell viability, apoptosis, and inflammation-associated factors (CXCL10, IFIT1, ISG15, and MX1) in RMCs and HEK293 cells. In addition, circ_0007059 overexpression significantly restored cell proliferation and viability and inhibited IFN-induced apoptosis. Further, the increased expression resulted in reduced inflammation and the downregulation of CXCL10, IFIT1, ISG15, and MX1 in RMCs and HEK293 cells. Circ_0007059 serves as a sponge for miR-1278 so that the latter can target the 3′-untranslated region of SHP-1. Overexpressed circ_0007059 inhibited miR-1278 expression and elevated SHP-1 expression, subsequently reducing STAT3 phosphorylation. Meanwhile, miR-1278 was upregulated and SHP-1 was downregulated in LN samples and IFN-treated cells. The restoration of miR-1278 counteracted the effect of circ_0007059 on viability, apoptosis, and inflammation as well as on SHP-1/STAT3 signaling in RMCs and HEK293 cells. We also investigated the role of SHP-1 overexpression in IFN-treated RMCs and HEK293 cells; SHP-1 overexpression resulted in a similar phenotype as that observed with circ_0007059 expression.

Conclusions

The study indicates that circ_0007059 protects RMCs against apoptosis and inflammation during nephritis by attenuating miR-1278/SHP-1/STAT3 signaling.

Supplementary Information

The online version contains supplementary material available at 10.1186/s10020-021-00372-6.

The phosphatase Shp1 interacts with and dephosphorylates cortactin to inhibit invadopodia function

BACKGROUND

Invadopodia are actin-based cell-membrane protrusions associated with the extracellular matrix degradation accompanying cancer invasion. The elucidation of the molecular mechanisms leading to invadopodia formation and activity is central for the prevention of tumor spreading and growth. Protein tyrosine kinases such as Src are known to regulate invadopodia assembly, little is however known on the role of protein tyrosine phosphatases in this process. Among these enzymes, we have selected the tyrosine phosphatase Shp1 to investigate its potential role in invadopodia assembly, due to its involvement in cancer development.

METHODS

Co-immunoprecipitation and immunofluorescence studies were employed to identify novel substrate/s of Shp1AQ controlling invadopodia activity. The phosphorylation level of cortactin, the Shp1 substrate identified in this study, was assessed by immunoprecipitation, in vitro phosphatase and western blot assays. Short interference RNA and a catalytically-dead mutant of Shp1 expressed in A375MM melanoma cells were used to evaluate the role of the specific Shp1-mediated dephosphorylation of cortactin. The anti-invasive proprieties of glycerophosphoinositol, that directly binds and regulates Shp1, were investigated by extracellular matrix degradation assays and in vivo mouse model of metastasis.

RESULTS

The data show that Shp1 was recruited to invadopodia and promoted the dephosphorylation of cortactin at tyrosine 421, leading to an attenuated capacity of melanoma cancer cells to degrade the extracellular matrix. Controls included the use of short interference RNA and catalytically-dead mutant that prevented the dephosphorylation of cortactin and hence the decrease the extracellular matrix degradation by melanoma cells. In addition, the phosphoinositide metabolite glycerophosphoinositol facilitated the localization of Shp1 at invadopodia hence promoting cortactin dephosphorylation. This impaired invadopodia function and tumor dissemination both in vitro and in an in vivo model of melanomas.

CONCLUSION

The main finding here reported is that cortactin is a specific substrate of the tyrosine phosphatase Shp1 and that its phosphorylation/dephosphorylation affects invadopodia formation and, as a consequence, the ability of melanoma cells to invade the extracellular matrix. Shp1 can thus be considered as a regulator of melanoma cell invasiveness and a potential target for antimetastatic drugs. Video abstract.

AG-1024 Sensitizes Sorafenib-Resistant Hepatocellular Carcinoma Cells to Sorafenib via Enhancing G1/S Arrest

PURPOSE

The frequency in resistance to sorafenib accounts for the grim prognosis of advanced hepatocellular carcinoma (HCC). In the present study, we explore the anti-cancer efficacy of co-administration of sub-toxic AG-1024 with sorafenib in HCC cells to enhance the sensitivity of these cells to sorafenib.

MATERIALS AND METHODS

Two acquired sorafenib-resistant HCC cells, SNU-sora-5 and SK-sora-5, were established and verified. The MTT assay, colony formation assay, cell morphology detection and flow cytometric analysis were then used to determine the anti-tumor effects of the co-administration of sub-toxic AG-1024 and sorafenib. Finally, the potential molecular mechanism was preliminarily examined.

RESULTS

Compared to parental cell lines, the acquired sorafenib-resistant cell lines, SNU-sora-5 and SK-sora-5, were more resistant to sorafenib. Sub-toxic AG-1024 markedly enhanced sorafenib-mediated cell inhibition in acquired sorafenib-resistant HCC strains, with a reversal index (RI) of 4.64 in SNU-sora-5 and 4.58 in SK-sora-5 cell lines. Moreover, co-administration of sub-toxic AG-1024 and sorafenib exerted dramatic cytotoxicity compared with sorafenib alone in the intrinsic sorafenib-resistant HCC-LM3 cells. In contrast to high-dose sorafenib, sub-toxic AG-1024 combined with sorafenib had less impact on apoptosis while significantly enhancing G1/S arrest via activation of the mTOR/p21 signaling pathway. The more, pharmacological inhibition of mTOR activity by inhibitor Palomid 529 significantly antagonized the synergistic anti-cancer effects of AG-1024 and sorafenib in HCC cells.

CONCLUSION

The current findings indicate that sub-toxic AG-1024 may be a promising therapeutic agent in enhancing the sensitivity in HCC cells to sorafenib, bringing hope to HCC patients refractory to sorafenib treatment.

Transcriptomic characterization reveals prognostic molecular signatures of sorafenib resistance in hepatocellular carcinoma

Sorafenib is the first-line treatment for patients with advanced unresectable hepatocellular carcinoma (HCC); however, only a small number of patients benefit from sorafenib, and many develop sorafenib resistance (SR) and severe side effects. To identify biomarkers for SR, we systematically analyzed the molecular alterations in both sorafenib-resistant HCC specimens and cultured cells. By combining bioinformatics tools and experimental validation, four genes (C2orf27A, insulin-like growth factor 2 receptor, complement factor B, and paraoxonase 1) were identified as key genes related to SR in HCC and as independent prognostic factors significantly associated with clinical cancer stages and pathological tumor grades of liver cancer. These genes can affect the cytotoxicity of sorafenib to regulate the proliferation and invasion of Huh7 cells in vitro. Additionally, immune-cell infiltration according to tumor immune dysfunction and exclusion, a biomarker integrating the mechanisms of dysfunction and exclusion of T cells showed good predictive power for SR, with an AUC of 0.869. These findings suggest that immunotherapy may be a potential strategy for treating sorafenib-resistant HCC. Furthermore, the results enhance the understanding of the underlying molecular mechanisms of SR in HCC and will facilitate the development of precision therapy for patients with liver cancer.

Cancer Stem Cell-Associated Pathways in the Metabolic Reprogramming of Breast Cancer

Metabolic reprogramming of cancer is now considered a hallmark of many malignant tumors, including breast cancer, which remains the most commonly diagnosed cancer in women all over the world. One of the main challenges for the effective treatment of breast cancer emanates from the existence of a subpopulation of tumor-initiating cells, known as cancer stem cells (CSCs). Over the years, several pathways involved in the regulation of CSCs have been identified and characterized. Recent research has also shown that CSCs are capable of adopting a metabolic flexibility to survive under various stressors, contributing to chemo-resistance, metastasis, and disease relapse. This review summarizes the links between the metabolic adaptations of breast cancer cells and CSC-associated pathways. Identification of the drivers capable of the metabolic rewiring in breast cancer cells and CSCs and the signaling pathways contributing to metabolic flexibility may lead to the development of effective therapeutic strategies. This review also covers the role of these metabolic adaptation in conferring drug resistance and metastasis in breast CSCs.

Long non-coding RNAs as targets for immunosuppressive drug teriflunomide in anti-cancer potential for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common form of liver cancer. Because of the relatively chemotherapy-refractory nature of HCC and significant potential poor hepatic reserve, chemotherapy has not been used consistently in the treatment of HCC. Effective new drugs for HCC are urgently needed. Teriflunomide, which was approved for the treatment of relapsing forms of multiple sclerosis (MS), has been identified as a potential antineoplastic drug. Long noncoding RNAs (lncRNAs) are a novel class of RNA molecules defined as transcripts longer than 200 nucleotides that lack protein coding potential. In this study, we investigated the ability of teriflunomide to act as an antineoplastic drug by examining the effects of teriflunomide treatment on HCC cells. Teriflunomide strongly inhibited the proliferation of HCC cells, induced cell apoptosis and induced cell accumulation in S phases of the cell cycle. LncRNA and mRNA expression profiles of HCC cells treated with teriflunomide compared with controls were performed by using microarray analysis. For comparison, the differentially expressed mRNAs were annotated by using gene ontology (GO) and pathway analyses. The microarray revealed that 2085 lncRNAs and 1561 mRNAs differed in the cells treated with teriflunomide compared with controls. Several GO terms including protein folding, mitochondrial outer membrane, transmembrane receptor protein phosphatase activity, negative regulation of cellular biosynthetic process, DNA packaging complex, and receptor signaling protein activity were enriched in gene lists, suggesting a potential correlation with the action mechanism of teriflunomide. Pathway analysis then demonstrated that JAK-STAT signaling pathway may play important roles in the cell apoptosis induced by teriflunomide. Co-expression network analysis indicated that a number of lncRNAs and mRNAs were included in the co-expression network, and p34710_v4 is the lncRNA with highest degree. Then the mRNAs associated with those differentially expressed lncRNAs were also annotated by using gene ontology (GO) and pathway analyses. The pathway analyses shows that teriflunomide significantly inhibited cell proliferation and promoted cell apoptosis partly by participating in Wnt signaling pathways. These findings suggest that teriflunomide could be a potential drug for chemotherapy and molecularly targeted therapies of HCC.

Berbamine (BBM), a Natural STAT3 Inhibitor, Synergistically Enhances the Antigrowth and Proapoptotic Effects of Sorafenib on Hepatocellular Carcinoma Cells

Sorafenib (SORA), a multi kinase inhibitor, is the standard first-line targeted therapy approved by the Food and Drug Administration for advanced hepatocellular carcinoma (HCC). However, emerging evidence from clinical practice indicates that SORA alone has only moderate antitumor effects and could not completely inhibit the progression of the disease. Therefore, it is very necessary and urgent to develop novel combination therapy to improve the clinical outcomes of SORA. The pharmacological study on the chemosensitizing effects of natural products has become a hotspot in recent years, which is commonly thought to be a potential way to improve the effectiveness of drugs in clinical use. Berbamine (BBM) has potential sensitizing effects in multiple chemotherapies and target therapy. However, it remains unclarified whether the combination of BBM and SORA as a treatment could exert a synergistic effect on HCC cell lines. In this study, we first investigated whether BBM can increase the sensitivity of HCC cell lines to SORA. The results revealed that the combination of BBM and SORA could synergistically inhibit the growth of two HCC cell lines and promoted their apoptosis. Mechanistically, our results showed that BBM exerted a dose-dependent inhibitory effect on the basal and IL-6-induced STAT3 activation of HCC cell lines. In addition, the combined treatment of BBM and SORA synergistically suppressed STAT3 phosphorylation at Tyr705 and knockdown of STAT3 abolished the sensitization effect of BBM, indicating that BBM's sensitization effect is mainly mediated by its inhibition of STAT3. These findings identify a new type of natural STAT3 inhibitor and provide a novel approach to the enhancement of SORA efficacy by blocking the activation of STAT3.

Recent advances of sorafenib nanoformulations for cancer therapy: Smart nanosystem and combination therapy

Sorafenib, a molecular targeted multi-kinase inhibitor, has received considerable interests in recent years due to its significant profiles of efficacy in cancer therapy. However, poor pharmacokinetic properties such as limited water solubility, rapid elimination and metabolism lead to low bioavailability, restricting its further clinical application. Over the past decade, with substantial progress achieved in the development of nanotechnology, various types of smart sorafenib nanoformulations have been developed to improve the targetability as well as the bioavailability of sorafenib. In this review, we summarize various aspects from the preparation and characterization to the evaluation of antitumor efficacy of numerous stimuli-responsive sorafenib nanodelivery systems, particularly with emphasis on their mechanism of drug release and tumor microenvironment response. In addition, this review makes great effort to summarize the nanosystem-based combination therapy of sorafenib with other antitumor agents, which can provide detailed information for further synergistic cancer therapy. In the final section of this review, we also provide a detailed discussion of future challenges and prospects of designing and developing ideal sorafenib nanoformulations for clinical cancer therapy.

Shp1 in Solid Cancers and Their Therapy

Shp1 is a cytosolic tyrosine phosphatase that regulates a broad range of cellular functions and targets, modulating the flow of information from the cell membrane to the nucleus. While initially studied in the hematopoietic system, research conducted over the past years has expanded our understanding of the biological role of Shp1 to other tissues, proposing it as a novel tumor suppressor gene functionally involved in different hallmarks of cancer. The main mechanism by which Shp1 curbs cancer development and progression is the ability to attenuate and/or terminate signaling pathways controlling cell proliferation, survival, migration, and invasion. Thus, alterations in Shp1 function or expression can contribute to several human diseases, particularly cancer. In cancer cells, Shp1 activity can indeed be affected by mutations or epigenetic silencing that cause failure of Shp1-mediated homeostatic maintenance. This review will discuss the current knowledge of the cellular functions controlled by Shp1 in non-hematopoietic tissues and solid tumors, the mechanisms that regulate Shp1 expression, the role of its mutation/expression status in cancer and its value as potential target for cancer treatment. In addition, we report information gathered from the public available data from The Cancer Genome Atlas (TCGA) database on Shp1 genomic alterations and correlation with survival in solid cancers patients.

Identification and validation of potential key long noncoding RNAs in sorafenib-resistant hepatocellular carcinoma cells

As the first-line treatment, sorafenib has been used for advanced hepatocellular carcinoma (HCC), but the chemoresistance commonly restricts to the clinical efficiency. In this study, we intend to investigate the genome-wide expression pattern of long noncoding RNAs (lncRNAs) in sorafenib-resistant HCC. Herein, we identified thousands of differentially expressed lncRNAs in sorafenib-resistant HCC cells by high-throughput sequencing compared to the parental. Besides, based on GO (Gene Ontology) term enrichment analysis, these differentially expressed lncRNAs are mainly related to binding and catalytic activity and biological regulation of metabolic processes in both the sorafenib-resistant Huh7 cells (Huh7-S) and sorafenib-resistant HepG2 cells (HepG2-S) compared to the parental cells. Moreover, when analyzed by KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway, the differentially expressed genes were significantly related to the tight junction. Among them, the expression of TCONS_00284048 and TCONS_00006019 was consistently up-regulated in sorafenib-resistant HCC cell lines, whereas when either was knocked down, the sensitivity of Huh7-S and HepG2-S cells to sorafenib was increased. Taken together, our data demonstrate that the lncRNA expression profile is significantly altered in sorafenib-resistant HCC cells as well as differentially expressed lncRNAs may play crucial functions on HCC sorafenib resistance and HCC progression.

DNMT3b/OCT4 expression confers sorafenib resistance and poor prognosis of hepatocellular carcinoma through IL-6/STAT3 regulation

BACKGROUND

The inflammatory cytokine interleukin-6 (IL-6) is critical for the expression of octamer-binding transcription factor 4 (OCT4), which is highly associated with early tumor recurrence and poor prognosis of hepatocellular carcinomas (HCC). DNA methyltransferase (DNMT) family is closely linked with OCT4 expression and drug resistance. However, the underlying mechanism regarding the interplay between DNMTs and IL-6-induced OCT4 expression and the sorafenib resistance of HCC remains largely unclear.

METHODS

HCC tissue samples were used to examine the association between DNMTs/OCT4 expression levels and clinical prognosis. Serum levels of IL-6 were detected using ELISA assays (n = 144). Gain- and loss-of-function experiments were performed in cell lines and mouse xenograft models to determine the underlying mechanism in vitro and in vivo.

RESULTS

We demonstrate that levels of DNA methyltransferase 3 beta (DNMT3b) are significantly correlated with the OCT4 levels in HCC tissues (n = 144), and the OCT4 expression levels are positively associated with the serum IL-6 levels. Higher levels of IL-6, DNMT3b, or OCT4 predicted early HCC recurrence and poor prognosis. We show that IL-6/STAT3 activation increases DNMT3b/1 and OCT4 in HCC. Activated phospho-STAT3 (STAT-Y640F) significantly increased DNMT3b/OCT4, while dominant negative phospho-STAT3 (STAT-Y705F) was suppressive. Inhibiting DNMT3b with RNA interference or nanaomycin A (a selective DNMT3b inhibitor) effectively suppressed the IL-6 or STAT-Y640F-induced increase of DNMT3b-OCT4 and ALDH activity in vitro and in vivo. The fact that OCT4 regulates the DNMT1 expressions were further demonstrated either by OCT4 forced expression or DNMT1 silence. Additionally, the DNMT3b silencing reduced the OCT4 expression in sorafenib-resistant Hep3B cells with or without IL-6 treatment. Notably, targeting DNMT3b with nanaomycin A significantly increased the cell sensitivity to sorafenib, with a synergistic combination index (CI) in sorafenib-resistant Hep3B cells.

CONCLUSIONS

The DNMT3b plays a critical role in the IL-6-mediated OCT4 expression and the drug sensitivity of sorafenib-resistant HCC. The p-STAT3 activation increases the DNMT3b/OCT4 which confers the tumor early recurrence and poor prognosis of HCC patients. Findings from this study highlight the significance of IL-6-DNMT3b-mediated OCT4 expressions in future therapeutic target for patients expressing cancer stemness-related properties or sorafenib resistance in HCC.

Treatment with a new benzimidazole derivative bearing a pyrrolidine side chain overcomes sorafenib resistance in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a major cause of cancer-related death worldwide. Currently, sorafenib is the standard first-line drug for patients with advanced HCC. However, long-term exposure to sorafenib often results in reduced sensitivity of tumour cells to the drug, leading to acquired resistance. Therefore, developing new compounds to treat sorafenib resistance is urgently needed. Although benzimidazole and its derivatives have been reported to exert antimicrobial and antitumour effects, the anti-drug resistance potential of these molecules is still unknown. In this study, we established sorafenib-resistant (SR) cell lines and an acquired sorafenib resistance xenograft model. We showed that treatment with a benzimidazole derivative bearing a pyrrolidine side chain (compound 9a) inhibited the proliferation of SR cells by blocking the phosphorylation of AKT, p70S6 and the downstream molecule RPS6. In addition, caspase 3/PARP-dependent apoptotic signals were induced in 9a-treated cells. Regarding epithelial-mesenchymal transition (EMT) activities, 9a treatment significantly suppressed the migration of SR cells. In particular, the levels of EMT-related transcription factors (snail, slug and twist) and mesenchymal markers (vimentin and N-cadherin) were downregulated. In the acquired sorafenib resistance xenograft model, compound 9a administration decreased the growth of tumours with acquired sorafenib resistance and the expression of the HCC markers α-fetoprotein, glypican 3 and survivin. In conclusion, treatment with this compound may be a novel therapeutic strategy for patients with sorafenib resistance.

TCDD-mediated suppression of naïve human B cell IgM secretion involves aryl hydrocarbon receptor-mediated reduction in STAT3 serine 727 phosphorylation and is restored by interferon-γ

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a persistent environmental contaminant formed as a byproduct in organic synthesis and burning of organic materials. TCDD has potent immunotoxic effects in B lymphocytes resulting in decreased cellular activation and suppressed IgM secretion following activation with CD40 ligand. Previous work from our lab demonstrated that TCDD treatment of naïve human B cells resulted in significant increases in the levels of the tyrosine phosphatase SHP-1, which corresponded with suppression of IgM secretion. STAT3 is a critical B cell transcription factor for B cell activation and secretion of immunoglobulins (Ig). STAT3 dimerizes and translocates to the nucleus following phosphorylation as a result of cytokine receptor signaling. We hypothesized that TCDD-mediated increases in SHP-1 could result in decreased STAT3 tyrosine phosphorylation. Interestingly, only modest changes in the levels of STAT3 tyrosine phosphorylation were observed. By contrast, TCDD significantly reduced levels of STAT3 serine phosphorylation as early as 12h post B cell activation. These results corresponded with decreased inhibitory phosphorylation of the serine specific phosphatase PP2a, which is regulated by SHP-1. Further, studies revealed that interferon gamma (IFNγ), which signals through the type II interferon receptor, can non-canonically induce STAT3 activation via Src kinase activity. Indeed, treatment of human B cells with IFNγ resulted in increased STAT3 serine phosphorylation and reversed TCDD-mediated suppression of the IgM response. Together, these data putatively identify a key event in the mechanism by which TCDD induces suppression of Ig secretion and demonstrate the potential of IFNγ as a means to reverse this effect in primary human B lymphocytes.

Evolution in medicinal chemistry of sorafenib derivatives for hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors. Traditional chemotherapy drugs are hard to reach a satisfactory therapeutic effect since advanced HCC is highly chemo-resistant. Sorafenib is an oral multikinase inhibitor that can suppress tumor cell proliferation, angiogenesis and induce cancer cell apoptosis. However, the poor solubility, rapid metabolism and low bioavailability of sorafenib greatly restricted its further clinical application. During the past decade, numerous sorafenib derivatives have been designed and synthesized to overcome its disadvantages and improve its clinical performance. This article focuses on the therapeutic effects and mechanisms of various sorafenib derivatives with modifications on the N-methylpicolinamide group, urea group, central aromatic ring or others. More importantly, this review summarizes the current status of the structure-activity relationship (SAR) of reported sorafenib derivatives, which can provide some detailed information of future directions for further structural modifications of sorafenib to discovery new anti-tumor drugs with improved clinical performance.

Negative regulators of STAT3 signaling pathway in cancers

STAT3 is the most ubiquitous member of the STAT family and involved in many biological processes, such as cell proliferation, differentiation, and apoptosis. Mounting evidence has revealed that STAT3 is aberrantly activated in many malignant tumors and plays a critical role in cancer progression. STAT3 is usually regarded as an effective molecular target for cancer treatment, and abolishing the STAT3 activity may diminish tumor growth and metastasis. Recent studies have shown that negative regulators of STAT3 signaling such as PIAS, SOCS, and PTP, can effectively retard tumor progression. However, PIAS, SOCS, and PTP have also been reported to correlate with tumor malignancy, and their biological function in tumorigenesis and antitumor therapy are somewhat controversial. In this review, we summarize actual knowledge on the negative regulators of STAT3 in tumors, and focus on the potential role of PIAS, SOCS, and PTP in cancer treatment. Furthermore, we also outline the STAT3 inhibitors that have entered clinical trials. Targeting STAT3 seems to be a promising strategy in cancer therapy.

Discovery of fluorescent coumarin-benzo[b]thiophene 1, 1-dioxide conjugates as mitochondria-targeting antitumor STAT3 inhibitors

STAT3 has been extensively studied as a potential antitumor target. Though studies on regulating STAT3 mainly focus on the inhibition of STAT3 phosphorylation at Tyr705 residue, the phosphorylation at Ser727 residue of STAT3 protein is also closely associated with the mitochondrial import of STAT3 protein. N, N-diethyl-7-aminocoumarin is a fluorescent mitochondria-targeting probe. In this study, a series of STAT3 inhibitors were developed by connecting N, N-diethyl-7-aminocoumarin fluorophore with benzo [b]thiophene 1, 1-dioxide moiety. All designed compounds displayed potent anti-proliferative activity against cancer cells. The representative compound 7a was mainly accumulated in mitochondria visualized by its fluorescence. STAT3 phosphorylation was inhibited by compound 7a at both Tyr705 and Ser727 residues. Compound 7a inhibited STAT3 phosphorylation whereas had no influence on the phosphorylation levels of STAT1, JAK2, Src and Erk1/2, indicating good selectivity of compound 7a. Moreover, compound 7a down-regulated the expression of STAT3 target genes Bcl-2 and Cyclin D1, increased ROS production and remarkably reduced the mitochondrial membrane potential to induce mitochondrial apoptotic pathway. Furthermore, compound 7ain vivo suppressed breast cancer 4T1 implanted tumor growth. Taken together, these results highlighted that compound 7a might be a promising mitochondria-targeting STAT3 inhibitor for cancer therapy.

Sestrin 2 confers primary resistance to sorafenib by simultaneously activating AKT and AMPK in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the malignancy derived from normal hepatocytes with increasing incidence and extremely poor prognosis worldwide. The only approved first‐line systematic treatment agent for HCC, sorafenib, is capable to effectively improve advanced HCC patients’ survival. However, it is gradually recognized that the therapeutic response to sorafenib could be drastically diminished after short‐term treatment, defined as primary resistance. The present study is aimed to explore the role of stress‐inducible protein Sestrin2 (SESN2), one of the most important sestrins family members, in sorafenib primary resistance. Herein, we initially found that SESN2 expression was significantly up‐regulated in both HCC cell lines and tissues compared to normal human hepatocytes and corresponding adjacent liver tissues, respectively. In addition, SESN2 expression was highly correlated with sorafenib IC₅₀ of HCC cell lines. Thereafter, we showed that sorafenib treatment resulted in an increase of SESN2 expression and the knockdown of SESN2 exacerbated sorafenib‐induced proliferation inhibition and cell apoptosis. Further mechanistic study uncovered that SESN2 deficiency impaired both AKT and AMPK phosphorylation and activation after sorafenib treatment. Moreover, the correlations between SESN2 expression and both phosphor‐AKT and phosphor‐AMPK expression were illustrated in HCC tissues. Taken together, our study demonstrates that SESN2 activates AKT and AMPK signaling as a novel mechanism to induce sorafenib primary resistance in HCC.

Protein Tyrosine Phosphatases as Potential Regulators of STAT3 Signaling

The signal transducer and activator of transcription 3 (STAT3) protein is a major transcription factor involved in many cellular processes, such as cell growth and proliferation, differentiation, migration, and cell death or cell apoptosis. It is activated in response to a variety of extracellular stimuli including cytokines and growth factors. The aberrant activation of STAT3 contributes to several human diseases, particularly cancer. Consequently, STAT3-mediated signaling continues to be extensively studied in order to identify potential targets for the development of new and more effective clinical therapeutics. STAT3 activation can be regulated, either positively or negatively, by different posttranslational mechanisms including serine or tyrosine phosphorylation/dephosphorylation, acetylation, or demethylation. One of the major mechanisms that negatively regulates STAT3 activation is dephosphorylation of the tyrosine residue essential for its activation by protein tyrosine phosphatases (PTPs). There are seven PTPs that have been shown to dephosphorylate STAT3 and, thereby, regulate STAT3 signaling: PTP receptor-type D (PTPRD), PTP receptor-type T (PTPRT), PTP receptor-type K (PTPRK), Src homology region 2 (SH-2) domain-containing phosphatase 1(SHP1), SH-2 domain-containing phosphatase 2 (SHP2), MEG2/PTP non-receptor type 9 (PTPN9), and T-cell PTP (TC-PTP)/PTP non-receptor type 2 (PTPN2). These regulators have great potential as targets for the development of more effective therapies against human disease, including cancer.

SHP-1 Acts as a Tumor Suppressor in Hepatocarcinogenesis and HCC Progression

Src homology region 2 (SH2) domain-containing phosphatase 1 (SHP-1, also known as PTPN6) is a nonreceptor protein tyrosine phosphatase that acts as a negative regulator of inflammation. Emerging evidence indicates that SHP-1 plays a role in inhibiting the progression of hepatocellular carcinoma (HCC). However, the role of SHP-1 in hepatocarcinogenesis remains unknown. Here, we find that levels of SHP-1 are significantly downregulated in human HCC tissues compared with those in noncancerous tissues (P < 0.001) and inversely correlate with tumor diameters (r = -0.4130, P = 0.0002) and serum α-fetoprotein levels (P = 0.047). Reduced SHP-1 expression was associated with shorter overall survival of patients with HCC with HBV infection. Overexpression of SHP-1 suppressed proliferation, migration, invasion, and tumorigenicity of HCC cells, whereas knockdown of SHP-1 enhanced the malignant phenotype. Moreover, knockout of Ptpn6 in hepatocytes (Ptpn6^HKO ) enhanced hepatocarcinogenesis induced by diethylnitrosamine (DEN) as well as metastasis of primary liver cancer in mice. Furthermore, systemic delivery of SHP-1 by an adenovirus expression vector exerted a therapeutic effect in an orthotopic model of HCC in NOD/SCID mice and DEN-induced primary liver cancers in Ptpn6^HKO mice. In addition, SHP-1 inhibited the activation of JAK/STAT, NF-κB, and AKT signaling pathways, but not the MAPK pathway in primary hepatocytes from DEN-treated mice and human HCC cells. Together, our data implicate SHP-1 as a tumor suppressor of hepatocarcinogenesis and HCC progression and propose it as a novel prognostic biomarker and therapeutic target of HCC.Significance: The nonreceptor protein tyrosine phosphatase SHP-1 acts as a tumor suppressor in hepatocellular carcinoma. Cancer Res; 78(16); 4680-91. ©2018 AACR.

Combined treatment with sorafenib and silibinin synergistically targets both HCC cells and cancer stem cells by enhanced inhibition of the phosphorylation of STAT3/ERK/AKT

Silibinin, a nontoxic bioactive component in milk thistle, is used as a liver-protective drug in the clinic mainly because of its antioxidant and anti-inflammation activities. In this study, we studied the cytotoxic effects of silibinin combined with sorafenib on hepatocellular carcinoma (HCC). The results indicated that silibinin combined with sorafenib potently inhibited the proliferation of various HCC cells and induced significant apoptosis. In an HCC subcutaneous transplantation tumor model, the combination of silibinin and sorafenib significantly suppressed tumor growth compared with monotherapy. As determined by fluorescence staining and Western blots, the combination of the two drugs inhibited the phosphorylation of RAC-alpha serine/threonine-protein kinase (AKT) and signal transducer and activator of transcription 3 (STAT3) together with the expression of antiapoptotic proteins including myeloid leukemia cell differentiation protein Mcl-1 (Mcl-1) and apoptosis regulator Bcl-2 (Bcl-2), resulting in the death of cancer cells. We also found that the combination inhibited the formation and self-renewal of HCC stem cells by down-regulating the expression of stemness-related proteins, such as Homeobox protein NANOG (Nanog) and Krueppel-like factor 4 (Klf4). These results suggested that silibinin improved the efficacy of sorafenib in HCC therapy, indicating a clinical promising therapeutic strategy for HCC patients.

Synergistic antitumor effects of tanshinone IIA and sorafenib or its derivative SC-1 in hepatocellular carcinoma cells

Introduction

Hepatocellular carcinoma (HCC) is the most common form of hepatic malignancy in the world. We aimed to determine the effect of tanshinone IIA (Tan-IIA) in combination with sorafenib or its derivative SC-1 on cytotoxicity, apoptosis, and metastasis in human HCC cells.

Materials and methods

Cytotoxicity was detected by MTT assay. Apoptosis and sub-G1 populations were analyzed by flow cytometry. Cell migration and invasion were evaluated by Transwell assay. Protein expression was detected by Western blot.

Results

Tan-IIA combined with sorafenib or SC-1 exerted synergistic cytotoxicity in HCC cells. Elevated proportions of sub-G1 and caspase activation were observed in the combinative treatments; in addition, marked inhibition of cell migration and invasion, which could be mediated by the modulation of epithelial–mesenchymal transition was observed. pSTAT3 levels were significantly reduced as well.

Conclusion

A combination therapy using Tan-IIA and sorafenib or SC-1 could be a promising approach to target HCC, and further preclinical investigations are warranted to establish their synergetic advantage.

The Roles of Protein Tyrosine Phosphatases in Hepatocellular Carcinoma

The protein tyrosine phosphatase (PTP) family is involved in multiple cellular functions and plays an important role in various pathological and physiological processes. In many chronic diseases, for example cancer, PTP is a potential therapeutic target for cancer treatment. In the last two decades, dozens of PTP inhibitors which specifically target individual PTP molecules were developed as therapeutic agents. Hepatocellular carcinoma (HCC) is one of the most common malignant tumors and is the second most lethal cancer worldwide due to a lack of effective therapies. Recent studies have unveiled both oncogenic and tumor suppressive functions of PTP in HCC. Here, we review the current knowledge on the involvement of PTP in HCC and further discuss the possibility of targeting PTP in HCC.

The HNF1α-regulated lncRNA HNF1A-AS1 reverses the malignancy of hepatocellular carcinoma by enhancing the phosphatase activity of SHP-1

BACKGROUND

Our previous study has demonstrated that hepatocyte nuclear factor 1α (HNF1α) exerts potent therapeutic effects on hepatocellular carcinoma (HCC). However, the molecular mechanisms by which HNF1α reverses HCC malignancy need to be further elucidated.

METHODS

lncRNA microarray was performed to identify the long noncoding RNAs (lncRNAs) regulated by HNF1α. Chromatin immunoprecipitation and luciferase reporter assays were applied to clarify the mechanism of the transcriptional regulation of HNF1α to HNF1A antisense RNA 1 (HNF1A-AS1). The effect of HNF1A-AS1 on HCC malignancy was evaluated in vitro and in vivo. RNA pulldown, RNA-binding protein immunoprecipitation and the Bio-Layer Interferometry assay were used to validate the interaction of HNF1A-AS1 and Src homology region 2 domain-containing phosphatase 1 (SHP-1).

RESULTS

HNF1α regulated the expression of a subset of lncRNAs in HCC cells. Among these lncRNAs, the expression levels of HNF1A-AS1 were notably correlated with HNF1α levels in HCC cells and human HCC tissues. HNF1α activated the transcription of HNF1A-AS1 by directly binding to its promoter region. HNF1A-AS1 inhibited the growth and the metastasis of HCC cells in vitro and in vivo. Moreover, knockdown of HNF1A-AS1 reversed the suppressive effects of HNF1α on the migration and invasion of HCC cells. Importantly, HNF1A-AS1 directly bound to the C-terminal of SHP-1 with a high binding affinity (KD = 59.57 ± 14.29 nM) and increased the phosphatase activity of SHP-1. Inhibition of SHP-1 enzymatic activity substantially reversed the HNF1α- or HNF1A-AS1-induced reduction on the metastatic property of HCC cells.

CONCLUSIONS

Our data revealed that HNF1A-AS1 is a direct transactivation target of HNF1α in HCC cells and involved in the anti-HCC effect of HNF1α. HNF1A-AS1 functions as phosphatase activator through the direct interaction with SHP-1. These findings suggest that regulation of the HNF1α/HNF1A-AS1/SHP-1 axis may have beneficial effects in the treatment of HCC.

Targeting multiple oncogenic pathways for the treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common forms of liver cancer diagnosed worldwide. HCC occurs due to chronic liver disease and is often diagnosed at advanced stages. Chemotherapeutic agents such as doxorubicin are currently used as first-line agents for HCC therapy, but these are non-selective cytotoxic molecules with significant side effects. Sorafenib, a multi-targeted tyrosine kinase inhibitor, is the only approved targeted drug for HCC patients. However, due to adverse side effects and limited efficacy, there is a need for the identification of novel pharmacological drugs beyond sorafenib. Several agents that target and inhibit various signaling pathways involved in HCC are currently being assessed for HCC treatment. In the present review article, we summarize the diverse signal transduction pathways responsible for initiation as well as progression of HCC and also the potential anticancer effects of selected targeted therapies that can be employed for HCC therapy.

Identification of novel small molecules that inhibit STAT3-dependent transcription and function

Activation of Signal Transducer and Activator of Transcription 3 (STAT3) has been linked to several processes that are critical for oncogenic transformation, cancer progression, cancer cell proliferation, survival, drug resistance and metastasis. Inhibition of STAT3 signaling has shown a striking ability to inhibit cancer cell growth and therefore, STAT3 has become a promising target for anti-cancer drug development. The aim of this study was to identify novel inhibitors of STAT-dependent gene transcription. A cellular reporter-based system for monitoring STAT3 transcriptional activity was developed which was suitable for high-throughput screening (Z’ = 0,8). This system was used to screen a library of 28,000 compounds (the ENAMINE Drug-Like Diversity Set). Following counter-screenings and toxicity studies, we identified four hit compounds that were subjected to detailed biological characterization. Of the four hits, KI16 stood out as the most promising compound, inhibiting STAT3 phosphorylation and transcriptional activity in response to IL6 stimulation. In silico docking studies showed that KI16 had favorable interactions with the STAT3 SH2 domain, however, no inhibitory activity could be observed in the STAT3 fluorescence polarization assay. KI16 inhibited cell viability preferentially in STAT3-dependent cell lines. Taken together, using a targeted, cell-based approach, novel inhibitors of STAT-driven transcriptional activity were discovered which are interesting leads to pursue further for the development of anti-cancer therapeutic agents.

Alteration of SHP-1/p-STAT3 Signaling: A Potential Target for Anticancer Therapy

The Src homology 2 (SH2) domain-containing protein tyrosine phosphatase 1 (SHP-1), a non-receptor protein tyrosine phosphatase, has been reported as a negative regulator of phosphorylated signal transducer and activator of transcription 3 (STAT3) and linked to tumor development. In this present review, we will discuss the importance and function of SHP-1/p-STAT3 signaling in nonmalignant conditions as well as malignancies, its cross-talk with other pathways, the current clinical development and the potential role of inhibitors of this pathway in anticancer therapy and clinical relevance of SHP-1/p-STAT3 in cancers. Lastly, we will summarize and highlight work involving novel drugs/compounds targeting SHP-1/p-STAT3 signaling and combined strategies that were/are discovered in our and our colleagues’ laboratories.

New knowledge of the mechanisms of sorafenib resistance in liver cancer

Sorafenib is an oral multikinase inhibitor that suppresses tumor cell proliferation and angiogenesis and promotes tumor cell apoptosis. It was approved by the FDA for the treatment of advanced renal cell carcinoma in 2006, and as a unique target drug for advanced hepatocellular carcinoma (HCC) in 2007. Sorafenib can significantly extend the median survival time of patients but only by 3-5 months. Moreover, it is associated with serious adverse side effects, and drug resistance often develops. Therefore, it is of great importance to explore the mechanisms underlying sorafenib resistance and to develop individualized therapeutic strategies for coping with these problems. Recent studies have revealed that in addition to the primary resistance, several mechanisms are underlying the acquired resistance to sorafenib, such as crosstalk involving PI3K/Akt and JAK-STAT pathways, the activation of hypoxia-inducible pathways, and epithelial-mesenchymal transition. Here, we briefly describe the function of sorafenib, its clinical application, and the molecular mechanisms for drug resistance, especially for HCC patients.

Sorafenib analogue SC-60 induces apoptosis through the SHP-1/STAT3 pathway and enhances docetaxel cytotoxicity in triple-negative breast cancer cells

Recurrent triple-negative breast cancer (TNBC) needs new therapeutic targets. Src homology region 2 domain-containing phosphatase-1 (SHP-1) can act as a tumor suppressor by dephosphorylating oncogenic kinases. One major target of SHP-1 is STAT3, which is highly activated in TNBC. In this study, we tested a sorafenib analogue SC-60, which lacks angiokinase inhibition activity, but acts as a SHP-1 agonist, in TNBC cells. SC-60 inhibited proliferation and induced apoptosis by dephosphorylating STAT3 in both a dose- and time-dependent manner in TNBC cells (MDA-MB-231, MDA-MB-468, and HCC1937). By contrast, ectopic expression of STAT3 rescued the anticancer effect induced by SC-60. SC-60 also increased the SHP-1 activity, but this effect was inhibited when the N-SH2 domain (DN1) was deleted or with SHP-1 point mutation (D61A), implying that SHP-1 is the major target of SC-60 in TNBC. The use of SC-60 in combination with docetaxel synergized the anticancer effect induced by SC-60 through the SHP-1/STAT3 pathway in TNBC cells. Importantly, SC-60 also displayed a significant antitumor effect in an MDA-MB-468 xenograft model by modulating the SHP-1/STAT3 axis, indicating the anticancer potential of SC-60 in TNBC treatment. Targeting SHP-1/p-STAT3 and the potential combination of SHP-1 agonist with chemotherapeutic docetaxel is a feasible therapeutic strategy for TNBC.

Discovery of oral-available resveratrol-caffeic acid based hybrids inhibiting acetylated and phosphorylated STAT3 protein

Constitutive activation of STAT3 has been found in a wide variety of cancers and demonstrated as a very attractive therapeutic target. Disrupting both acetylation and phosphorylation of STAT3 protein was hypothesized to greatly deactivate STAT3, therefore, treating cancers. To demonstrate the hypothesis, two series of novel resveratrol-caffeic acid hybrids were designed aiming to regulate both acetylation and phosphorylation of STAT3 protein, which is also the first report of the synthetic inhibitors simultaneously regulating two biological reactions of STAT3 to our knowledge. Most of these compounds were demonstrated with preferential antitumor activity with low IC₅₀ values against two cancer cell lines. Particularly, compound 7d was found as an excellent STAT3 inhibitor with over 50-fold better potency than resveratrol and caffeic acid. Meanwhile, the novel derivatives significantly inhibited the proliferation and induced the apoptosis of tumor cells. Molecular docking further disclosed the binding modes of STAT3 with the inhibitors. In addition, compound 7d orally and significantly suppressed breast cancer 4T1 xenograft tumor growth in vivo, indicating its great potential as an efficacious drug candidate for human cancer therapy.

Pharmacological Targeting SHP-1-STAT3 Signaling Is a Promising Therapeutic Approach for the Treatment of Colorectal Cancer

STAT3 activation is associated with poor prognosis in human colorectal cancer (CRC). Our previous data demonstrated that regorafenib (Stivarga) is a pharmacological agonist of SH2 domain-containing phosphatase 1 (SHP-1) that enhances SHP-1 activity and induces apoptosis by targeting STAT3 signals in CRC. This study aimed to find a therapeutic drug that is more effective than regorafenib for CRC treatment. Here, we showed that SC-43 was more effective than regorafenib at inducing apoptosis in vitro and suppressing tumorigenesis in vivo. SC-43 significantly increased SHP-1 activity, downregulated p-STAT3^Tyr705 level, and induced apoptosis in CRC cells. An SHP-1 inhibitor or knockdown of SHP-1 by siRNA both significantly rescued the SC-43–induced apoptosis and decreased p-STAT3^Tyr705 level. Conversely, SHP-1 overexpression increased the effects of SC-43 on apoptosis and p-STAT3^Tyr705 level. These data suggest that SC-43–induced apoptosis mediated through the loss of p-STAT3^Tyr705 was dependent on SHP-1 function. Importantly, SC-43–enhanced SHP-1 activity was because of the docking potential of SC-43, which relieved the autoinhibited N-SH2 domain of SHP-1 and inhibited p-STAT3^Tyr705 signals. Importantly, we observed that a significant negative correlation existed between SHP-1 and p-STAT3^Tyr705expression in CRC patients (P = .038). Patients with strong SHP-1 and weak p-STAT3^Tyr705 expression had significantly higher overall survival compared with patients with weak SHP-1 and strong p-STAT3^Tyr705 expression (P = .029). In conclusion, SHP-1 is suitable to be a useful prognostic marker and a pharmacological target for CRC treatment. Targeting SHP-1-STAT3 signaling by SC-43 may serve as a promising pharmacotherapy for CRC.

Recent updates of precision therapy for gastric cancer: Towards optimal tailored management

Signaling pathways of gastric carcinogenesis and gastric cancer progression are being avidly studied to seek optimal treatment of gastric cancer. Among them, hepatocyte growth factor (HGF)/c-MET, phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) and janus kinase 2/signal transducer and activator of transcription 3 (JAK2/STAT3) pathways have been widely investigated. Their aberrant expression or mutation has been significantly associated with advanced stage or poor prognosis of gastric cancer. Recently, aberrations of immune checkpoints including programmed cell death-1/programmed cell death ligand-1 (PD-1/PD-L1) have been suggested as an important step in the formation of a microenvironment favorable for gastric cancer. Accomplishments in basic research have led to the development of novel agents targeting these signaling pathways. However, phase III studies of selective anti-HGF/c-MET antibodies and mTOR inhibitor failed to show significant benefits in terms of overall survival and progression-free survival. Few agents directly targeting STAT3 have been developed. However, this target is still critical issue in terms of chemoresistance, and SH2-containing protein tyrosine phosphatase 1 might be a significant link to effectively inhibit STAT3 activity. Inhibition of PD-1/PD-L1 showed durable efficacy in phase I studies, and phase III evaluation is warranted. Therapeutic strategy to concurrently inhibit multiple tyrosine kinases is a reasonable option, however, lapatinib needs to be further evaluated to identify good responders. Regorafenib has shown promising effectiveness in prolonging progression-free survival in a phase II study. In this topic highlight, we review the biologic roles and outcomes of clinical studies targeting these signaling pathways.

SHP-1 is a target of regorafenib in colorectal cancer

Regorafenib is an inhibitor of multiple protein kinases which exerts antitumor and antimetastatic activities in metastatic colorectal cancer (CRC). SH2 domain-containing phosphatase 1 (SHP-1) is reported to have tumor suppressive potential because it acts as a negative regulator of p-STAT3^Tyr705 signaling. However, little is known about the mechanism regarding regorafenib affects SHP-1 tyrosine phosphatase activity and leads to apoptosis and tumor suppression in CRC. Here, we found that regorafenib triggered apoptotic cell death and significantly enhanced SHP-1 activity, which dramatically decreased the phosphorylated form of STAT3 at Tyr705 (p-STAT3^Tyr705). Importantly, regorafenib augmented SHP-1 activity by direct disruption of the association between N-SH2 and catalytic PTP domain of SHP-1. Deletion of the N-SH2 domain (dN1) or point mutation (D61A) of SHP-1 blocked the effect of regorafenib-induced SHP-1 activity, growth inhibition and a decrease of p-STAT3^Tyr705 expression, suggesting that regorafenib triggers a conformational change in SHP-1 by relieving its autoinhibition. In vivo assay showed that regorafenib significantly inhibited xenograft growth and decreased p-STAT3^Tyr705 expression but induced higher SHP-1 activity. Collectively, regorafenib is a novel SHP-1 agonist exerts superior anti-tumor effects by enhancing SHP-1 activity that directly targets p-STAT3^Tyr705. Small molecule-enhancement of SHP-1 activity may be a promising therapeutic approach for CRC treatment.

Protein tyrosine phosphatase SHP-1 sensitizes EGFR/HER-2 positive breast cancer cells to trastuzumab through modulating phosphorylation of EGFR and HER-2

Background

Trastuzumab resistance in HER-2 positive breast cancer cells is closely related to overexpression of both epidermal growth factor receptor (EGFR) and human epidermal receptor (HER-2). SHP-1 has been demonstrated to downregulate tyrosine kinase activity including EGFR via its phosphatase function, but its effect on HER-2 activity is still unknown. Here, we examined the hypothesis that SHP-1 enhances the anticancer efficacy of trastuzumab in EGFR/HER-2 positive breast cancer cells through combining dual inhibition of EGFR and HER-2.

Methods

Trastuzumab-resistant breast cancer SKBr-3 cells were generated by long-term in vitro culture of SKBr-3cells in the presence of trastuzumab. The SHP-1 was ectopically expressed by stable transfection. The activity and expression of EGFR, HER-2, and downstream signaling pathways were tested by Western blot. Cell viability was examined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, and apoptosis was examined by flow cytometry. The binding between SHP-1 and EGFR/HER-2 was evaluated by immunoprecipitation assay and bimolecular fluorescence complementation. The effects of SHP-1 on tumorigenicity and trastuzumab sensitivity were confirmed via in vivo xenograft model.

Results

Trastuzumab-resistant SKBr-3 cells showed aberrant co-expression of EGFR and HER-2. Introduction of wild-type SHP-1 inhibited cell proliferation, clone formation, and promoted the apoptosis induced by trastuzumab. Meanwhile, SHP-1 overexpression reduced phosphorylation levels of EGFR and HER-2 both in parental and trastuzumab-resistant SKBr-3 cells. In vivo study showed an increased antitumor effect of trastuzumab in SHP-1 overexpressed xenografts. At last, we discovered that SHP-1 can make complexes with both EGFR and HER-2, and both phospho-EGFR and phosphor-HER-2 levels in wild-type SHP-1 immunoprecipitates were less than those in phosphatase-inactive SHP-1 (C453S) immunoprecipitates, indicating that EGFR and HER-2 are potential substrates of SHP-1.

Conclusion

Taken together, we have demonstrated that the SHP-1 is a negative regulatory factor of the tyrosine kinase activity of HER-2 and EGFR through inhibiting phosphorylation. Dual targeting of EGFR and HER-2, by combining trastuzumab with SHP-1 overexpression, may improve response in HER-2 overexpressing breast cancer cells that also express high levels of EGFR.

Sorafenib Action in Hepatitis B Virus X-Activated Oncogenic Androgen Pathway in Liver through SHP-1

BACKGROUND

Hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) shows a higher incidence in men, mainly because of hepatitis B X (HBx)-mediated enhancement of androgen receptor (AR) activity. We aimed to examine this pathway in hepatocarcinogenesis and to identify drug(s) specifically blocking this carcinogenic event in the liver.

METHODS

HBx transgenic mice that spontaneously develop HCC (n = 28-34 per group) were used, either by knockout of hepatic AR or by castration. Efficacy of several HCC-targeted drugs in suppressing HBx-induced AR activity was evaluated, and cellular factors mediating suppression were investigated in cultured cells. Tissue specificity of the candidate drug was validated using mouse tissues. Data were analyzed with Chi-square and Student's t tests. All statistical tests were two-sided.

RESULTS

The androgen pathway was shown to be important in early stage hepatocarcinogenesis of HBx transgenic mice. The tumor incidence was decreased from 80% to 32% by AR knockout (P < .001) and from 90% to 25% by early castration (P < .001). Sorafenib markedly inhibited the HBx-enhanced AR activity through activating the SHP-1 phosphatase, which antagonized the activation of Akt/GSK3β and c-Src by HBx. Moreover, SHP-1 protein level was much higher in the liver than in testis, which enabled sorafenib to inhibit aberrant AR activity in the HBx-expressing liver, while not affecting the physiological AR function in normal liver or testis.

CONCLUSIONS

The androgen pathway may be a druggable target for the chemoprevention of HBV-related HCC, and sorafenib might be used as a tissue- and disease-specific regimen for the chemoprevention of HBV-related HCC.

Treatment of Liver Cancer

Primary liver cancer, mostly hepatocellular carcinoma, remains a difficult-to-treat cancer. Incidence of liver cancer varies geographically and parallels with the geographic prevalence of viral hepatitis. A number of staging systems have been developed, reflecting the heterogeneity of primary liver cancer, regional preferences, and regional variations in resectability or transplant eligibility. Multimodality treatments are available for this heterogeneous malignancy, and there are variations in the management recommendations for liver cancers across specialties and geographic regions. Novel treatment strategies have merged with the advance of new treatment modalities. This work focuses on reviewing the incidence, staging, and treatment of liver cancer.