Cyclin E1 Inhibition can Overcome Sorafenib Resistance in Hepatocellular Carcinoma Cells Through Mcl-1 Suppression

Clinical Implication of E2F Transcription Factor 1 in Hepatocellular Carcinoma Tissues

Background: To date, the clinical management of advanced hepatocellular carcinoma (HCC) patients remains challenging and the mechanisms of E2F transcription factor 1 (E2F1) underlying HCC are obscure. Materials and Methods: Our study integrated datasets mined from several public databases to comprehensively understand the deregulated expression status of E2F1. Tissue microarrays and immunohistochemistry staining was used to validate E2F1 expression level. The prognostic value of E2F1 was assessed. In-depth subgroup analyses were implemented to compare the differentially expressed levels of E2F1 in HCC patients with various tumor stages. Functional enrichments were used to address the predominant targets of E2F1 and shedding light on their potential roles in HCC. Results: We confirmed the elevated expression of E2F1 in HCC. Subgroup analyses indicated that elevated E2F1 level was independent of various stages in HCC. E2F1 possessed moderate discriminatory capability in differentiating HCC patients from non-HCC controls. Elevated E2F1 correlated with Asian race, tumor classification, neoplasm histologic grade, eastern cancer oncology group, and plasma AFP levels. Furthermore, high E2F1 correlated with poor survival condition and pooled HR signified E2F1 as a risk factor for HCC. Enrichment analysis of differentially expressed genes, coexpressed genes, and putative targets of E2F1 emphasized the importance of cell cycle pathway, where CCNE1 and CCNA2 served as hub genes. Conclusions: We confirmed the upregulation of E2F1 and explored the prognostic value of E2F1 in HCC patients. Two putative targeted genes (CCNE1 and CCNA2) of E2F1 were identified for their potential roles in regulating cell cycle and promote antiapoptotic activity in HCC patients.

Inhibition of Dickkopf-1 enhances the anti-tumor efficacy of sorafenib via inhibition of the PI3K/Akt and Wnt/β-catenin pathways in hepatocellular carcinoma

BACKGROUND

Sorafenib improves the overall survival in patients with advanced hepatocellular carcinoma (HCC). Dickkopf-1 (DKK1) is commonly overexpressed in HCC. In this study, we investigated whether the inhibition of DKK1 enhances the anti-tumor efficacy of sorafenib in HCC.

METHODS

HCC cells were treated with sorafenib and WAY-262611, which is an inhibitor of DKK1. Transgenic mouse models were also developed using hydrodynamic tail vein injection. Mice were orally administered with sorafenib (32 mg/kg), WAY-262611 (16 mg/kg), or sorafenib + WAY-262611 for 10 days. Mechanisms of sorafenib and WAY-262611 were explored via western blotting, immunostaining, and RNA sequencing.

RESULTS

DKK1 was significantly overexpressed in patients with HCC than in the healthy controls and patients with liver diseases except HCC (all P < 0.05). Compared with sorafenib alone, sorafenib + WAY-262611 significantly inhibited the cell viability, invasion, migration, and colony formation by promoting apoptosis and altering the cell cycles in HCC cells (all P < 0.05). Moreover, sorafenib + WAY-262611 decreased the p110α, phospho-Akt (all P < 0.05), active β-catenin (all P < 0.05) and phospho-GSK-3β (Ser9) expression levels, while increasing the phospho-GSK-3β (Tyr216) expression levels compared with those in the sorafenib alone in vitro and in vivo. In addition, sorafenib + WAY-262611 inhibited tumor progression by regulating cell proliferation and apoptosis, significantly better than sorafenib alone in mouse models.

CONCLUSIONS

Our results indicate that DKK1 inhibition significantly enhances the anti-tumor efficacy of sorafenib by inhibiting the PI3K/Akt and Wnt/β-catenin pathways via regulation of GSK3β activity, suggesting a novel therapeutic strategy for HCC. Video Abstract.

Anti-hepatocellular carcinoma activity of the cyclin-dependent kinase inhibitor AT7519

Hepatocellular carcinoma (HCC) is one of the most common cancerous tumors and one of the leading causes of death among cancer-related disorders. Chemotherapy is ineffective in HCC patients, and the number of drugs that are in use is limited. Thus, new molecules are needed that could increase the effectiveness of anti-HCC regimens. Here, we show that AT7519, a CDK inhibitor, exerts positive effects on HCC cells: it inhibits proliferation, migration and clonogenicity. Detailed analysis of the transcriptomes of cells treated with this compound indicated that AT7519 affects a substantial portion of genes that are associated with HCC development and progression. Moreover, we showed that the concomitant use of AT7519 with gefitinib or cabozantinib sensitized HCC cells to these drugs. Thus, our research indicates that AT7519 is worth considering in monotherapy for hepatocellular carcinoma patients or in combination with other drugs, e.g., gefitinib or cabozantinib.

Erratum: Drug resistance mechanism of kinase inhibitors in the treatment of hepatocellular carcinoma

[This corrects the article DOI: 10.3389/fphar.2023.1097277.].

SN-38, an active metabolite of irinotecan, enhances anti-PD-1 treatment efficacy in head and neck squamous cell carcinoma

Anti-programmed cell death 1 (anti-PD-1) therapy shows definite but modest activity in patients with advanced/metastatic head and neck squamous cell carcinoma (HNSCC). Preliminary evidence suggests that SN-38, an activated form of irinotecan that increases expression of the transcription factor FoxO3a, can suppress programmed cell death ligand-1 (PD-L1) expression in breast and ovarian tumor models. We analyzed the SN-38-mediated activation of natural killer cells in vitro and explored the efficacy of SN-38 in combination with anti-PD-1 for treatment in vivo. In vitro, SN-38 enhanced the expression of FoxO3a and reduced the expression of c-Myc and PD-L1 dose-dependently in tumor cells. Low-dose SN-38 increased interferon-γ secretion by NK cells and promoted NK cell-mediated cytotoxicity in tumor cells. In vivo studies revealed that at non-cytotoxic drug concentrations, SN-38 significantly enhanced anti-PD-1 activity in suppressing murine tumor growth. We found increased NK cell and CD8⁺ T-cell infiltration in post-treatment tumors. RNA-seq analysis indicated that SN-38 increased the enrichment of immune cells and biological function genes related to the immune responses. SN-38 is a potentially beneficial adjunct to checkpoint inhibitor therapy in HNSCC. Further studies exploring its mechanism of action and possible applications are necessary. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Drug resistance mechanism of kinase inhibitors in the treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common form of primary liver cancer, and it usually occurs following chronic liver disease. Although some progress has been made in the treatment of HCC, the prognosis of patients with advanced HCC is not optimistic, mainly because of the inevitable development of drug resistance. Therefore, multi-target kinase inhibitors for the treatment of HCC, such as sorafenib, lenvatinib, cabozantinib, and regorafenib, produce small clinical benefits for patients with HCC. It is necessary to study the mechanism of kinase inhibitor resistance and explore possible solutions to overcome this resistance to improve clinical benefits. In this study, we reviewed the mechanisms of resistance to multi-target kinase inhibitors in HCC and discussed strategies that can be used to improve treatment outcomes.

Inhibition of USP1 activates ER stress through Ubi-protein aggregation to induce autophagy and apoptosis in HCC

The deubiquitinating enzyme USP1 (ubiquitin-specific protease 1) plays a role in the progression of various tumors, emerging as a potential therapeutic target. This study aimed to determine the role of USP1 as a therapeutic target in hepatocellular carcinoma (HCC). We detected USP1 expression in the tumor and adjacent tissues of patients with HCC using immunohistochemical staining. We evaluated the effect of the USP1 inhibitor ML-323 on HCC cell proliferation and cell cycle using a CCK-8 cell-counting kit and plate cloning assays, and propidium iodide, respectively. Apoptosis was detected by annexin V-FITC/Propidium Iodide (PI) staining and caspase 3 (casp3) activity. Transmission electron microscopy and LC3B immunofluorescence were used to detect autophagy. Western blotting was used to detect the accumulation of ubiquitinated proteins, the expression of endoplasmic reticulum (ER) stress-related proteins, and the AMPK-ULK1/ATG13 signaling pathway. We demonstrated that ML-323 inhibits the growth of HCC cells and induces G1 phase cell cycle arrest by regulating cyclin expression. ML-323 treatment resulted in the accumulation of ubiquitinated proteins, induced ER stress, and triggered Noxa-dependent apoptosis, which was regulated by the Activating Transcription Factor 4(ATF4). Moreover, active ER stress induces protective autophagy by increasing AMPK phosphorylation; therefore, we inhibited ER stress using 4-Phenylbutyric acid (4-PBA), which resulted in ER stress reduction, apoptosis, and autophagy in ML-323-treated HCC cells. In addition, blocking autophagy using the AMPK inhibitor compound C (CC), chloroquine (CQ), or bafilomycin A1 (BafA1) enhanced the cytotoxic effect of ML-323. Our findings revealed that targeting USP1 may be a potential strategy for the treatment of HCC.

Effects of Sulforaphane-Induced Cell Death upon Repeated Passage of Either P-Glycoprotein-Negative or P-Glycoprotein-Positive L1210 Cell Variants

The expression of the membrane ABCB1 transporter in neoplastic cells is one of the most common causes of reduced sensitivity to chemotherapy. In our previous study, we investigated the effect of a single culture of ABCB1-negative (S) and ABCB1-positive variants of L1210 cells (R and T) in the presence of sulforaphane (SFN). We demonstrated that SFN induces the onset of autophagy more markedly in S cells than in R or T cells. In the current study, we focused on the effect of the repeated culture of S, R and T cells in SFN-containing media. The repeated cultures increased the onset of autophagy compared to the simple culture, mainly in S cells and to a lesser extent in R and T cells, as indicated by changes in the cellular content of 16 and 18 kDa fragments of LC3B protein or changes in the specific staining of cells with monodansylcadaverine. We conclude that SFN affects ABCB1-negative S cells more than ABCB1-positive R and T cells during repeated culturing. Changes in cell sensitivity to SFN appear to be related to the expression of genes for cell-cycle checkpoints, such as cyclins and cyclin-dependent kinases.

Mouse Models for Immune Checkpoint Blockade Therapeutic Research in Oral Cancer

The most prevalent oral cancer globally is oral squamous cell carcinoma (OSCC). The invasion of adjacent bones and the metastasis to regional lymph nodes often lead to poor prognoses and shortened survival times in patients with OSCC. Encouraging immunotherapeutic responses have been seen with immune checkpoint inhibitors (ICIs); however, these positive responses to monotherapy have been limited to a small subset of patients. Therefore, it is urgent that further investigations into optimizing immunotherapies are conducted. Areas of research include identifying novel immune checkpoints and targets and tailoring treatment programs to meet the needs of individual patients. Furthermore, the advancement of combination therapies against OSCC is also critical. Thus, additional studies are needed to ensure clinical trials are successful. Mice models are advantageous in immunotherapy research with several advantages, such as relatively low costs and high tumor growth success rate. This review paper divided methods for establishing OSCC mouse models into four categories: syngeneic tumor models, chemical carcinogen induction, genetically engineered mouse, and humanized mouse. Each method has advantages and disadvantages that influence its application in OSCC research. This review comprehensively surveys the literature and summarizes the current mouse models used in immunotherapy, their advantages and disadvantages, and details relating to the cell lines for oral cancer growth. This review aims to present evidence and considerations for choosing a suitable model establishment method to investigate the early diagnosis, clinical treatment, and related pathogenesis of OSCC.

The Mechanism of Rac1 in Regulating HCC Cell Glycolysis Which Provides Underlying Therapeutic Target for HCC Therapy

Aim

To explore the role of Rac1 on sorafenib resistance in hepatocellular carcinoma.

Methods

CCK-8, wound healing assay, Transwell, and cell cycle assay were used to detect the tumor cells development. Cell viability was assessed by MTT. The glycolytic pathway was revealed by cellular metabolism assays.

Result

We recovered that Rac1 upregulation was related to HCC patients' poorer prognosis. Forced expression of Rac1 promoted cell development and sorafenib chemoresistance in HCC cells. Rac1 inhibitor EHop-016 and sorafenib combination markedly prevented cell viability, G2/M phase cycle arrest, and apoptosis than single therapy. Furthermore, combination therapy decreased glycolysis in HCC cells. In vivo, the tumor growth was significantly prevented by combination therapy single therapy.

Conclusion

Our research declares that Rac1 inhibition could block sorafenib resistance in HCC by decreasing glycolysis, which would provide an underlying target for HCC therapy.

Low miR-10b-3p associated with sorafenib resistance in hepatocellular carcinoma

BACKGROUND

Sorafenib is one of the standard first-line therapies for advanced hepatocellular carcinoma (HCC). Unfortunately, there are currently no appropriate biomarkers to predict the clinical efficacy of sorafenib in HCC patients. MicroRNAs (miRNAs) have been studied for their biological functions and clinical applications in human cancers.

METHODS

In this study, we found that miR-10b-3p expression was suppressed in sorafenib-resistant HCC cell lines through miRNA microarray analysis.

RESULTS

Sorafenib-induced apoptosis in HCC cells was significantly enhanced by miR-10b-3p overexpression and partially abrogated by miR-10b-3p depletion. Among 45 patients who received sorafenib for advanced HCC, those with high miR-10b-3p levels, compared to those with low levels, exhibited significantly longer overall survival (OS) (median, 13.9 vs. 3.5 months, p = 0.021), suggesting that high serum miR-10b-3p level in patients treated with sorafenib for advanced HCC serves as a biomarker for predicting sorafenib efficacy. Furthermore, we confirmed that cyclin E1, a known promoter of sorafenib resistance reported by our previous study, is the downstream target for miR-10b-3p in HCC cells.

CONCLUSIONS

This study not only identified the molecular target for miR-10b-3p, but also provided evidence that circulating miR-10b-3p may be used as a biomarker for predicting sorafenib sensitivity in patients with HCC.

microRNA-106b-5p Promotes Cell Growth and Sensitizes Chemosensitivity to Sorafenib by Targeting the BTG3/Bcl-xL/p27 Signaling Pathway in Hepatocellular Carcinoma

microRNAs (miRNAs) and miRNA-mediated regulatory networks are promising candidates in the prevention and treatment of cancer, but the role of specific miRNAs involved in hepatocellular carcinoma (HCC) remains to be elusive. Herein, we found that miR-106b-5p is upregulated in both HCC patients' tumor tissues and HCC cell lines. The miR-106b-5p expression level was positively correlated with α-fetoprotein (AFP), hepatitis B surface antigen (HBsAg), and tumor size. Overexpression of miR-106b-5p promoted cell proliferation, migration, cell cycle G1/S transition, and tumor growth, while decreased miR-106b-5p expression had opposite effects. Mechanistic studies showed that B-cell translocation gene 3 (BTG3), a known antiproliferative protein, was a direct target of miR-106b-5p, whose expression level is inversely correlated with miR-106b-5p expression. Moreover, miR-106b-5p positively regulates cell proliferation in a BTG3-dependent manner, resulting in upregulation of Bcl-xL, cyclin E1, and CDK2, as well as downregulation of p27. More importantly, we also demonstrated that miR-106b-5p enhances the resistance to sorafenib treatment in a BTG3-dependent manner. The in vivo findings showed that mice treated with a miR-106b-5p sponge presented a smaller tumor burden than controls, while the mice injected cells treated with miR-106b-5p had more considerable tumor burden than controls. Altogether, these data suggest that miR-106b-5p promotes cell proliferation and cell cycle and increases HCC cells' resistance to sorafenib through the BTG3/Bcl-xL/p27 signaling pathway.

Implications of Stemness Features in 1059 Hepatocellular Carcinoma Patients from Five Cohorts: Prognosis, Treatment Response, and Identification of Potential Compounds

Simple Summary

Cancer stemness has been reported to drive hepatocellular carcinoma (HCC) tumorigenesis and treatment resistance. However, comprehensive interpretations of transcriptomic stemness features in HCC patients have not been conducted in multiple cohorts. Our aim was to interpret clinical and therapeutic implications of transcriptional stemness features and explore potential compounds for HCC treatment. We found that transcriptional stemness indexes (mRNAsi) were independently associated with worse HCC prognosis. The HCC stemness risk model (HSRM) developed in this study significantly predicted prognosis and treatment response in various HCC cohorts. Analysis of two stemness subtypes suggested several liver-specific metabolic pathways, and mutations of TP53 and RB1 were associated with HCC transcriptional stemness. Moreover, we also identified potential compounds that target HCC transcriptional stemness. Our findings comprehensively characterized transcriptional stemness as a risk factor in HCC progression and treatment.

Abstract

Cancer stemness has been reported to drive hepatocellular carcinoma (HCC) tumorigenesis and treatment resistance. In this study, five HCC cohorts with 1059 patients were collected to calculate transcriptional stemness indexes (mRNAsi) by the one-class logistic regression machine learning algorithm. In the TCGA-LIHC cohort, we found mRNAsi was an independent prognostic factor, and 626 mRNAsi-related genes were identified by Spearman correlation analysis. The HCC stemness risk model (HSRM) was trained in the TCGA-LIHC cohort and significantly discriminated overall survival in four independent cohorts. HSRM was also significantly associated with transarterial chemoembolization treatment response and rapid tumor growth in HCC patients. Consensus clustering was conducted based on mRNAsi-related genes to divide 1059 patients into two stemness subtypes. On gene set variation analysis, samples of subtype I were found enriched with pathways such as DNA replication and cell cycle, while several liver-specific metabolic pathways were inhibited in these samples. Somatic mutation analysis revealed more frequent mutations of TP53 and RB1 in the subtype I samples. In silico analysis suggested topoisomerase, cyclin-dependent kinase, and histone deacetylase as potential targets to inhibit HCC stemness. In vitro assay showed two predicted compounds, Aminopurvalanol-a and NCH-51, effectively suppressed oncosphere formation and impaired viability of HCC cell lines, which may shed new light on HCC treatment.

Potential Role of CXCL13/CXCR5 Signaling in Immune Checkpoint Inhibitor Treatment in Cancer

Simple Summary

Immunotherapy is currently the backbone of new drug treatments for many cancer patients. CXC chemokine ligand 13 (CXCL13) is an important factor involved in recruiting immune cells that express CXC chemokine receptor type 5 (CXCR5) in the tumor microenvironment and serves as a key molecular determinant of tertiary lymphoid structure (TLS) formation. An increasing number of studies have identified the influence of CXCL13 on prognosis in patients with cancer, regardless of the use of immunotherapy treatment. However, no comprehensive reviews of the role of CXCL13 in cancer immunotherapy have been published to date. This review aims to provide an overview of the CXCL13/CXCR5 signaling axis to summarize its mechanisms of action in cancer cells and lymphocytes, in addition to effects on immunity and cancer pathobiology, and its potential as a biomarker for the response to cancer immunotherapy.

Abstract

Immune checkpoint inhibitors (ICIs), including antibodies that target programmed cell death protein 1 (PD-1), programmed death-ligand 1 (PD-L1), or cytotoxic T lymphocyte antigen 4 (CTLA4), represent some of the most important breakthroughs in new drug development for oncology therapy from the past decade. CXC chemokine ligand 13 (CXCL13) exclusively binds CXC chemokine receptor type 5 (CXCR5), which plays a critical role in immune cell recruitment and activation and the regulation of the adaptive immune response. CXCL13 is a key molecular determinant of the formation of tertiary lymphoid structures (TLSs), which are organized aggregates of T, B, and dendritic cells that participate in the adaptive antitumor immune response. CXCL13 may also serve as a prognostic and predictive factor, and the role played by CXCL13 in some ICI-responsive tumor types has gained intense interest. This review discusses how CXCL13/CXCR5 signaling modulates cancer and immune cells to promote lymphocyte infiltration, activation by tumor antigens, and differentiation to increase the antitumor immune response. We also summarize recent preclinical and clinical evidence regarding the ICI-therapeutic implications of targeting the CXCL13/CXCR5 axis and discuss the potential role of this signaling pathway in cancer immunotherapy.

ERK/AKT Inactivation and Apoptosis Induction Associate With Quetiapine-inhibited Cell Survival and Invasion in Hepatocellular Carcinoma Cells

BACKGROUND/AIM

Quetiapine, an atypical antipsychotic, has been encountered as a potential protective agent to suppress various types of tumor growth. However, the inhibitory mechanism of quetiapine in hepatocellular carcinoma (HCC) still remains unclear. The purpose of present study was to investigate the inhibitory mechanism of quetiapine on cell survival and invasion in HCC.

MATERIALS AND METHODS

Changes of apoptotic signaling, migration/invasion ability, and signaling transduction involved in cell survival and invasion were evaluated with flow cytometry, migration/invasion, and western blot assays.

RESULTS

Quetiapine inhibited cell proliferation and migration/invasion in SK-Hep1 and Hep3B cells. Quetiapine induced extrinsic and intrinsic apoptotic pathways. Activation of extracellular signal-regulated kinases (ERK), protein kinase B (AKT), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-ĸB), expression of anti-apoptotic, and metastasis-associated proteins were decreased by quetiapine.

CONCLUSION

The apoptosis induction, the decreased expression of ERK/AKT-mediated anti-apoptotic and the metastasis-associated proteins were associated with quetiapine-inhibited cell survival and invasion in HCC in vitro.

Marine Natural Products: A Potential Source of Anti-hepatocellular Carcinoma Drugs

Hepatocellular carcinoma (HCC) has high associated morbidity and mortality rates. Although chemical medication represents a primary HCC treatment strategy, low response rates and therapeutic resistance serve to reduce its efficacy. Hence, identifying novel effective drugs is urgently needed, and many researchers have sought to identify new anti-cancer drugs from marine organisms. The marine population is considered a "blue drug bank" of unique anti-cancer compounds with diverse groups of chemical structures. Here, we discuss marine-derived compounds, including PM060184 and bryostatin-1, with demonstrated anti-cancer activity in vitro or in vivo. Based on the marine source (sponges, algae, coral, bacteria, and fungi), we introduce pharmacological parameters, compound-induced cytotoxicity, effects on apoptosis and metastasis, and potential molecular mechanisms. Cumulatively, this review provides insights into anti-HCC research conducted to date in the field of marine natural products and marine-derived compounds, as well as the potential pharmacological mechanisms of these compounds and their status in drug development.

Targeting MCL-1 in cancer: current status and perspectives

Myeloid leukemia 1 (MCL-1) is an antiapoptotic protein of the BCL-2 family that prevents apoptosis by binding to the pro-apoptotic BCL-2 proteins. Overexpression of MCL-1 is frequently observed in many tumor types and is closely associated with tumorigenesis, poor prognosis and drug resistance. The central role of MCL-1 in regulating the mitochondrial apoptotic pathway makes it an attractive target for cancer therapy. Significant progress has been made with regard to MCL-1 inhibitors, some of which have entered clinical trials. Here, we discuss the mechanism by which MCL-1 regulates cancer cell apoptosis and review the progress related to MCL-1 small molecule inhibitors and their role in cancer therapy.

Regorafenib enhances antitumor immunity via inhibition of p38 kinase/Creb1/Klf4 axis in tumor-associated macrophages

BACKGROUND

Regorafenib and other multikinase inhibitors may enhance antitumor efficacy of anti-program cell death-1 (anti-PD1) therapy in hepatocellular carcinoma (HCC). Its immunomodulatory effects, besides anti-angiogenesis, were not clearly defined.

METHODS

In vivo antitumor efficacy was tested in multiple syngeneic liver cancer models. Murine bone marrow-derived macrophages (BMDMs) were tested in vitro for modulation of polarization by regorafenib and activation of cocultured T cells. Markers of M1/M2 polarization were measured by quantitative reverse transcription PCR (RT-PCR), arginase activity, flow cytometry, and ELISA. Knockdown of p38 kinase and downstream Creb1/Klf4 signaling on macrophage polarization were confirmed by using knockdown of the upstream MAPK14 kinase, chemical p38 kinase inhibitor, and chromatin immunoprecipitation.

RESULTS

Regorafenib (5 mg/kg/day, corresponding to about half of human clinical dosage) inhibited tumor growth and angiogenesis in vivo similarly to DC-101 (anti-VEGFR2 antibody) but produced higher T cell activation and M1 macrophage polarization, increased the ratio of M1/M2 polarized BMDMs and proliferation/activation of cocultured T cells in vitro, indicating angiogenesis-independent immunomodulatory effects. Suppression of p38 kinase phosphorylation and downstream Creb1/Klf4 activity in BMDMs by regorafenib reversed M2 polarization. Regorafenib enhanced antitumor efficacy of adoptively transferred antigen-specific T cells. Synergistic antitumor efficacy between regorafenib and anti-PD1 was associated with multiple immune-related pathways in the tumor microenvironment.

CONCLUSION

Regorafenib may enhance antitumor immunity through modulation of macrophage polarization, independent of its anti-angiogenic effects. Optimization of regorafenib dosage for rational design of combination therapy regimen may improve the therapeutic index in the clinic.

A combination of sorafenib and radiotherapy reduces NF-κB activity and growth of hepatocellular carcinoma in an orthotopic mouse model

Hepatocellular carcinoma (HCC) is difficult to diagnose at an early stage, and its prognosis is generally poor. Sorafenib is the primary treatment for unresectable advanced HCC and targets multiple receptor tyrosine kinases. However, sorafenib only extends the average survival time by 3 months. This observation indicates that sorafenib may need to be combined with other treatments to further improve outcomes. We previously showed that combination of sorafenib with radiotherapy (RT) enhances tumor inhibition in subcutaneous HCC mouse models compared with monotherapy. The present study demonstrated that combining sorafenib and RT could suppress tumor growth in an orthotopic HCC model by regulating apoptosis and NF-κB-related pathways. Moreover, decreased numbers of visible liver tumors and a smaller percentage of spleen metastases were found in the combination group. A transient drop in body weight was initially observed after RT, but progressive recovery of body weight occurred. The current study showed that the combination of sorafenib and RT could be a safe strategy for HCC treatment.

LncRNA TTN-AS1 intensifies sorafenib resistance in hepatocellular carcinoma by sponging miR-16-5p and upregulation of cyclin E1

Drug resistance has always been an important problem affecting the therapeutic effect of hepatocellular carcinoma (HCC). To investigate the potential role of lncRNA TTN-AS1 in HCC cells with sorafenib (SOR) resistance, and explore the underlying pathways, quantitative real time polymerase chain reaction (qRT-PCR) was used to test the expression of TTN-AS1 in HCC tissues and cells. Then, the expression of TTN-AS1 was down-regulated by shRNA, the activity changes, apoptosis and related protein expression in HCC cells with/without SOR treatment were observed in succession. Expression levels of the downstream target of TTN-AS1, miR-16-5p were studied by dual-luciferase binding assay, cell proliferation, and western blotting analysis. Nude mice models of human HCC with TTN-AS1 gene knockdown were established to observe the tumor growth. As the results revealed, TTN-AS1 silencing in HCC cells induced apoptosis by enhancing the sensitivity of cells to SOR, and the tumor in nude mice became smaller. The mechanism study showed that miR-16-5p was affected by TTN-AS1 sponge, up-regulated cyclin E1 expression, and regulated PTEN/Akt signaling pathway, thereby significantly alleviating the inhibition of apoptosis of HCC cells induced by TTN-AS1 gene. Collectively, our results provided TTN-AS1 as a potential therapeutic target for sorafenib resistance in HCC.

Targeted therapy for hepatocellular carcinoma

The last 3 years have seen the emergence of promising targeted therapies for the treatment of hepatocellular carcinoma (HCC). Sorafenib has been the mainstay of treatment for a decade and newer modalities were ineffective and did not confer any increased therapeutic benefit until the introduction of lenvatinib which was approved based on its non-inferiority to sorafenib. The subsequent success of regorafenib in HCC patients who progress on sorafenib treatment heralded a new era of second-line treatment and was quickly followed by ramucirumab, cabozantinib, and the most influential, immune checkpoint inhibitors (ICIs). Over the same period combination therapies, including anti-angiogenesis agents with ICIs, dual ICIs and targeted agents in conjunction with surgery or other loco-regional therapies, have been extensively investigated and have shown promise and provided the basis for exciting clinical trials. Work continues to develop additional novel therapeutic agents which could potentially augment the presently available options and understand the underlying mechanisms responsible for drug resistance, with the goal of improving the survival of patients with HCC.

Protein Kinase B Inactivation Is Associated with Magnolol-Enhanced Therapeutic Efficacy of Sorafenib in Hepatocellular Carcinoma In Vitro and In Vivo

Although sorafenib, an oral multikinase inhibitor, was approved as a treatment drug of advance hepatocellular carcinoma (HCC), treatment efficacy still requires improvement. Searching for the adjuvant reagent for enhancing sorafenib efficacy remains as a critical issue. Sorafenib has been proved to suppress extracellular signal-regulated kinases (ERK) in HCC; however, protein kinase B (AKT) was not affected by it. Targeting AKT in combination with sorafenib could be an important breakthrough point of HCC treatment. Many herbal compounds and composite formulas have been shown to enhance anti-HCC activity of sorafenib. Magnolol is a bioactive compound extracted from the bark of the Magnolia officinalis and has been shown to induce apoptosis and inhibit cell invasion in HCC in vitro. However, whether magnolol sensitizes HCC to sorafenib is ambiguous. In this study, we indicated that magnolol significantly enhanced sorafenib-diminished tumor cell growth, expression of anti-apoptotic proteins, and migration/invasion ability compared to sorafenib alone. Magnolol significantly boosted sorafenib-induced extrinsic/intrinsic dependent apoptosis pathways in HCC. Notably sorafenib could not reduce protein level of AKT (Ser473), but expression of AKT (Ser473) was significantly decreased by magnolol or magnolol combined with sorafenib. LY294002 as specific AKT inhibitor was used to confirm that AKT inactivation may promote anticancer effect of sorafenib. Taken together, AKT inhibition is associated with magnolol-enhanced the therapeutic effect of sorafenib in HCC. We suggested magnolol as the potential adjuvant which may enhance therapeutic benefits of sorafenib in patients with HCC.

Mitochondrial metabolic study guided by proteomics analysis in hepatocellular carcinoma cells surviving long-term incubation with the highest dose of sorafenib

Sorafenib is the standard first-line systemic therapy for hepatocellular carcinoma (HCC). However, the low objective response rates in clinical studies suggest the existence of certain HCC cells that are inherently insensitive to sorafenib. To understand the molecular basis of insensitivity of HCC cells to sorafenib, this study developed 3 kinds of insensitive HCC cells through exposure to various concentrations of sorafenib and performed a quantitative proteome analysis of the surviving HepG2 cells. 520 unique proteins were concentration-dependently upregulated by sorafenib. Bioinformatics-assisted analysis of 520 proteins revealed that the metabolic pathways involved in central carbon metabolism were significantly enriched, and 102 mitochondrial proteins, especially components of the electron transport chain (ETC), were incrementally upregulated in the 3 kinds of insensitive cells. Conversely, we identified a rapid holistic inhibitory effect of sorafenib on mitochondrial function by the direct targeting of the complex I-linked electron transport and the uncoupling of mitochondrial oxidative phosphorylation (OXHPOS) in HCC cells. Core metabolic reprogramming involved in a compensatory upregulation of OXHPOS combined with elevated glycolysis supports the survival of HCC cells under the highest dose of sorafenib treatment. Altogether, our work thus elaborates an ETC inhibitor and unveils the proteomic landscape of metabolic reprogramming in drug insensitivity.

PMPCB Silencing Sensitizes HCC Tumor Cells to Sorafenib Therapy

Hepatocellular carcinoma (HCC) tumors invariably develop resistance to cytotoxic and targeted agents, resulting in failed treatment and tumor recurrence. Previous in vivo short hairpin RNA (shRNA) screening evidence revealed mitochondrial-processing peptidase (PMPC) as a leading gene contributing to tumor cell resistance against sorafenib, a multikinase inhibitor used to treat advanced HCC. Here, we investigated the contributory role of the β subunit of PMPC (PMPCB) in sorafenib resistance. Silencing PMPCB increased HCC tumor cell susceptibility to sorafenib therapy, decreased liver tumor burden, and improved survival of tumor-bearing mice receiving sorafenib. Moreover, sorafenib + PMPCB shRNA combination therapy led to attenuated liver tumor burden and improved survival outcome for tumor-bearing mice, and it reduced colony formation in murine and human HCC cell lines in vitro. Additionally, PMPCB silencing enhanced PINK1-Parkin signaling and downregulated the anti-apoptotic protein MCL-1 in sorafenib-treated HCC cells, which is indicative of a healthier pro-apoptotic phenotype. Higher pre-treatment MCL-1 expression was associated with inferior survival outcomes in sorafenib-treated HCC patients. Elevated MCL-1 expression was present in sorafenib-resistant murine HCC cells, while MCL-1 knockdown sensitized these cells to sorafenib. In conclusion, our findings advocate combination regimens employing sorafenib with PMPCB knockdown or MCL-1 knockdown to circumvent sorafenib resistance in HCC patients.

Role of cyclin-dependent kinases (CDKs) in hepatocellular carcinoma: Therapeutic potential of targeting the CDK signaling pathway

Liver cancer is the fourth leading cause of cancer related mortality in the world, with hepatocellular carcinoma (HCC) representing the most common primary subtype. Two-thirds of HCC patients have advanced disease when diagnosed, and for these patients, treatment strategies remain limited. In addition, there is a high incidence of tumor recurrence after surgical resection with the current treatment regimens. The development of novel and more effective agents is required. Cyclin-dependent kinases (CDKs) constitute a family of 21 different protein kinases involved in regulating cell proliferation, apoptosis, and drug resistance, and are evaluated in preclinical and clinical trials as chemotherapeutics. To summarize and discuss the therapeutic potential of targeting CDKs in HCC, recent published articles identified from PubMed were comprehensively reviewed. The key words included hepatocellular carcinoma, cyclin-dependent kinases, and CDK inhibitors. This review focuses on the emerging evidence from studies describing the genetic and functional aspects of CDKs in HCC. We also present an overview of CDK inhibitors that have shown efficacy in laboratory studies of HCC. Although many of the studies assessing CDK-targeting therapies in HCC are at the preclinical stage, there is significant evidence that CDK inhibitors used alone or in combination with established chemotherapy drugs could have significant applications in HCC.

Potent Activity of Composite Cyclin Dependent Kinase Inhibition against Hepatocellular Carcinoma

Alterations in cell cycle regulators are common in hepatocellular carcinoma (HCC). We tested the efficacy of composite inhibition of CDKs 1, 2, 5, and 9 through dinaciclib on HCC. In vitro, dinaciclib exhibited potent antiproliferative activities in HCC cell lines regardless of Rb or c-myc expression levels. Dinaciclib significantly downregulated the phosphorylation of Rb (target of CDKs 1 and 2), ataxia telangiectasia mutated kinase (target of CDK5), and RNA polymerase II (target of CDK9) in the HCC cells. In xenograft studies, mice receiving dinaciclib tolerated the treatment well without significant body weight changes and exhibited a significantly slower tumor growth rate than the mice receiving vehicles. RNA interference (RNAi) of CDKs 1 and 9 was more effective in inhibiting the cell proliferation of HCC cells than RNAi of CDKs 2 and 5. Overexpression of CDK9 significantly reduced the efficacy of dinaciclib in HCC cells, but overexpression of CDK1 did not. In conclusion, composite inhibition of CDKs 1, 2, 5, and 9 through dinaciclib exhibited potent in vitro and in vivo activity against HCC. CDK9 inhibition might be the crucial mechanism.

Inhibition of cyclin E1 sensitizes hepatocellular carcinoma cells to regorafenib by mcl-1 suppression

Background

To clarify the effects of cylcin E1 expression on HCC tumor progression, we studied the expression of cyclin E1 and inhibitory efficacy of regorafenib and sorafenib in HCC cells, and investigated a potential therapy that combines regorafenib treatment with cyclin E1 inhibition.

Methods

Western blotting for caspase-3 and Hoechst 33225 staining was used to measure the expression level of apoptosis-related proteins under drug treatment.

Results

Our results showed that enhanced expression of cyclin E1 after transfection compromised apoptosis in HCC cells induced by regorafenib or sorafenib. Conversely, down-regulation of cyclin E1 gene expression or inhibition of cyclin E1 by the cyclin-dependent kinase (CDK) inhibitors dinaciclib (DIN) or flavopiridol sensitized HCC cells to regorafenib and sorafenib by inducing apoptosis. The expression of Mcl-1, which is modulated by STAT3, plays a key role in regulating the therapeutic effects of CDK inhibitors. Xenograft experiments conducted to test the efficacy of regorafenib combined with DIN showed dramatic tumor inhibitory effects due to induction of apoptosis. Our results suggested that the level of cyclin E1 expression in HCCs may be used as a pharmacodynamic biomarker to assess the antitumor effects of regorafenib or sorafenib.

Conclusions

Combining regorafenib and CDK inhibitors may enhance the clinical efficiency of the treatment of HCCs.

Electronic supplementary material

The online version of this article (10.1186/s12964-019-0398-3) contains supplementary material, which is available to authorized users.

Inhibition of cyclin E1 overcomes temozolomide resistance in glioblastoma by Mcl-1 degradation

Glioblastoma (GBM) is one of the major causes of brain cancer-related mortality worldwide. Temozolomide (TMZ) is an important agent against GBM. Acquired TMZ-resistance severely limits the chemotherapeutic effect and leads to poor GBM patient survival. To study the underlying mechanism of drug resistance, two TMZ resistant GBM cell lines, A172 and U87, were generated. In this study, the TMZ resistant cells have less apoptosis and cell-cycle change in response to the TMZ treatment. Western blot results revealed that cyclin E1 was upregulation in TMZ resistant cells. Inhibition or depletion of cyclin E1 re-sensitized the resistant cells to the TMZ treatment, which indicated the induction of cyclin E1 is the cause of TMZ resistance in GBM cells. Furthermore, we also found the expression of cyclin E1 stabilized the expression of Mcl-1, which contributes to the TMZ resistance in GBM cells. Finally, our in vivo xenograft data showed that the combination of flavopiridol, a cyclin E1/CDK2 inhibitor, overcomes the TMZ resistant by inducing higher apoptosis. Overall, our data provided a rationale to overcome the TMZ resistant in GBM treatment by inhibiting the cyclin E1 activity.

Development of a PD-L1-Expressing Orthotopic Liver Cancer Model: Implications for Immunotherapy for Hepatocellular Carcinoma

BACKGROUND

Anti-programmed cell death-1(anti-PD1) treatment has shown promising antitumor efficacy in patients with advanced hepatocellular carcinoma (HCC). This study sought to explore the functional significance of programmed death ligand-1 (PD-L1) expression in tumor cells in the tumor microenvironment.

METHODS

The mouse liver cancer cell line BNL-MEA was transfected with PD-L1 plasmids and stable clones expressing PD-L1 were selected. An orthotopic HCC model was generated by implanting the cells into the subcapsular space of BALB/c mice. Cell growth features were measured by proliferation assay, colony formation, flow cytometry (in vitro), ultrasonography, and animal survival (in vivo). The changes in T-cell function were examined by cytokine assay, expression of T-cell related genes, and flow cytometry. The efficacy of anti-PD1 therapy was compared between the parental and PD-L1-expressing tumors.

RESULTS

PD-L1 expression did not affect growth characteristics of BNL-MEA cells but downregulated the expression of genes related to T-cell activation in the tumor microenvironment. Co-culture of PD-L1-expressing BNL-MEA cells with CD8+ T cells reduced T-cell proliferation and expression of cytokines IFNγ and TNFα. Tumors with PD-L1 expression showed better response to anti-PD1 therapy and depletion of CD8+ T cells abolished the antitumor effect. The difference in treatment response between parental and PD-L1-expressing tumors disappeared when a combination of anti-PD1 and sorafenib was given.

CONCLUSIONS

PD-L1 expression in HCC cells may inhibit T-cell function in the liver tumor microenvironment. Anti-PD1 therapy appeared more effective in PD-L1-expressing than nonexpressing tumors, but the difference was diminished by the addition of sorafenib.

TARBP2-mediated destabilization of Nanog overcomes sorafenib resistance in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a lethal human malignancy and a leading cause of cancer‐related death worldwide. Patients with HCC are often diagnosed at an advanced stage, and the prognosis is usually poor. The multikinase inhibitor sorafenib is the first‐line treatment for patients with advanced HCC. However, cases of primary or acquired resistance to sorafenib have gradually increased, leading to a predicament in HCC therapy. Thus, it is critical to investigate the mechanism underlying sorafenib resistance. Transactivation response element RNA‐binding protein 2 (TARBP2) is a multifaceted miRNA biogenesis factor that regulates cancer stem cell (CSC) properties. The tumorigenicity and drug resistance of cancer cells are often enhanced due to the acquisition of CSC features. However, the role of TARBP2 in sorafenib resistance in HCC remains unknown. Our results demonstrate that TARBP2 is significantly downregulated in sorafenib‐resistant HCC cells. The TARBP2 protein was destabilized through autophagic–lysosomal proteolysis, thereby stabilizing the expression of the CSC marker protein Nanog, which facilitates sorafenib resistance in HCC cells. In summary, here we reveal a novel miRNA‐independent role of TARBP2 in regulating sorafenib resistance in HCC cells.

Amentoflavone Inhibits Hepatocellular Carcinoma Progression Through Blockage of ERK/NF-ĸB Activation

AIM

The aim of the present study was to confirm therapeutic efficacy and find probable mechanism of action of amentoflavone in hepatocellular carcinoma (HCC) in vivo.

MATERIALS AND METHODS

Luciferase reporter vector pGL4.50_transfected SK-Hep1 (SK-Hep1/luc2) tumor-bearing mice were treated with vehicle or amentoflavone (100 mg/kg/day by gavage) for 14 days. Tumor growth, amentoflavone toxicity, and extracellular signal-regulated kinase (ERK)/nuclear factor-kappaB (NF-ĸB) signaling in tumor progression were evaluated with digital caliper, bioluminescence imaging, computed tomography, body weight, pathological examination of liver, and immunohistochemistry staining.

RESULTS

Amentoflavone significantly inhibited tumor growth, ERK/NF-ĸB activation, and expression of tumor progression-associated proteins as compared to vehicle-treated group. In addition, body weight and liver morphology of mice were not influenced by amentoflavone treatment.

CONCLUSION

These results suggest that amentoflavone inhibits HCC progression through suppression of ERK/NF-ĸB signaling.

RASSF6-mediated inhibition of Mcl-1 through JNK activation improves the anti-tumor effects of sorafenib in renal cell carcinoma

Ras association domain family member 6 (RASSF6) has been shown to act as a tumor suppressor and predictor of poor prognosis in renal cell carcinoma (RCC). However, little is known about the effects of RASSF6 on sorafenib resistance or the underlying mechanism. Here, we show that RASSF6 expression positively correlates with sorafenib sensitivity in RCC cells and human samples. Stable ectopic overexpression of RASSF6 in RCC cell lines reduces resistance to sorafenib in vitro and in vivo. At a molecular level, RASSF6 activates the JNK signaling pathway, which further contributes to Mcl-1 inhibition. Suppression of the JNK pathway can partially restore Mcl-1 expression and sorafenib resistance. Together, these findings suggest that RASSF6 inhibits sorafenib resistance by repressing Mcl-1 through the JNK-dependent pathway. RASSF6 may serve as a novel regulator for sorafenib therapy in RCC.

Cyclin Y Modulates the Proliferation, Invasion, and Metastasis of Hepatocellular Carcinoma Cells

Background

Cyclin Y (CCNY) is a member of the cyclin family of proteins that regulate the cell cycle. The aims of this study were to compare the expression of CCNY in normal liver and human hepatocellular carcinoma (HCC), in normal and HCC cell lines, and in mouse HCC tumor xenografts.

Material/Methods

Tumor tissues from 55 patients diagnosed with HCC were studied for CCNY expression. Human HCC cell lines, SK-Hep1, HepG2, HEP3B, HuH7 and L02 were studied using the MTT cell proliferation assay, cell apoptosis, transwell and wound healing assays. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blot were used to measure CCNY expression. Indirect immunofluorescence was used to assess cell apoptosis. In vivo xenograft mouse model was constructed and examined histologically.

Results

Expression of CCNY in human HCC tumor tissues was significantly increased when compared with adjacent normal liver (all P<0.05). HCC cells grown in vitro showed significantly increased expression of CCNY, cell proliferation, and migration, and a reduced rate of apoptosis, compared with cells with CCNY knockdown (siRNA) (all P<0.05). In the xenograft mouse model, tumor volume and weight in the CCNY overexpression group were significantly increased, compared with CCNY knockdown (siRNA) group (all P<0.05).

Conclusions

In tissue samples of human HCC, and human HCC cell lines, increased expression of CCNY was significantly associated with cell proliferation and migration. Further studies are recommended to evaluate the role of CCNY as a potential diagnostic biomarker or target for treatment in human HCC.

New insights into sorafenib resistance in hepatocellular carcinoma: Responsible mechanisms and promising strategies

It is disappointing that only a few patients with hepatocellular carcinoma (HCC) obtain a significant survival benefit from the sorafenib treatment, which is currently regarded as a first-line chemotherapeutic therapy in patients with advanced HCC. Most patients are highly refractory to this therapy. Therefore, it is necessary to identify resistant factors and explore potential protocols that can be used to overcome the resistance or substitute sorafenib once the resistance is formed. In fact, a growing body of studies has been focusing on the resistance mechanisms or the method to overcome it. The limitation of sorafenib efficacy has been partially but not fully elucidated. Moreover, some protocols have shown encouraging outcomes but still need to be further verified in clinical trials. In this review, we summarize the recent findings on the potential mechanisms that contribute to sorafenib resistance and discuss strategies that can be used to improve the treatment outcome.

Amentoflavone enhances sorafenib-induced apoptosis through extrinsic and intrinsic pathways in sorafenib-resistant hepatocellular carcinoma SK-Hep1 cells in vitro

The present study aimed to evaluate the effects of amentoflavone on sorafenib-induced apoptosis in sorafenib-resistant hepatocellular carcinoma (HCC) cells. The sorafenib-resistant SK-Hep1 (SK-Hep1R) cell line was established for the present study. Initially, the differences in sorafenib-induced cytotoxicity and apoptosis between wild-type SK-Hep1 and SK-Hep1R cells were verified using the MTT assay and flow cytometry. The effects of amentoflavone on sorafenib-induced cytotoxicity and apoptosis were then investigated using MTT, flow cytometry, DNA gel electrophoresis and western blot analysis. The results demonstrated that cell viability of SK-Hep1R cells was increased compared with that of SK-Hep1 cells following treatment with different concentrations of sorafenib for 24 h. Apoptosis of SK-Hep1R cells was lower than that of SK-Hep1 cells following treatment with 20 µM sorafenib for 24 h. Amentoflavone alone did not inhibit cell viability but significantly triggered sorafenib-induced cytotoxicity and apoptosis in SK-Hep1R cells. Amentoflavone not only reversed sorafenib-induced anti-apoptotic protein levels but also enhanced sorafenib-induced pro-apoptotic protein expression in SK-Hep1R cells. In conclusion, amentoflavone may be used as a sorafenib sensitizer to enhance sorafenib-induced cytotoxicity and trigger sorafenib-induced apoptosis through extrinsic and intrinsic pathways in SK-Hep1R cells.

Inhibition of Mitochondrial Matrix Chaperones and Antiapoptotic Bcl-2 Family Proteins Empower Antitumor Therapeutic Responses

Rational therapeutic approaches based on synthetic lethality may improve cancer management. On the basis of a high-throughput drug screen, we provide preclinical proof of concept that targeting the mitochondrial Hsp90 chaperone network (mtHsp90) and inhibition of Bcl-2, Bcl-xL, and Mcl-1 is sufficient to elicit synthetic lethality in tumors recalcitrant to therapy. Our analyses focused on BH3 mimetics that are broad acting (ABT263 and obatoclax) or selective (ABT199, WEHI-539, and A1210477), along with the established mitochondrial matrix chaperone inhibitor gamitrinib-TPP. Drug combinations were tested in various therapy-resistant tumors in vitro and in vivo in murine model systems of melanoma, triple-negative breast cancer, and patient-derived orthotopic xenografts (PDX) of human glioblastoma. We found that combining BH3 mimetics and gamitrinib-TPP blunted cellular proliferation in a synergistic manner by massive activation of intrinsic apoptosis. In like manner, suppressing either Bcl-2, Bcl-xL, or Mcl-1 recapitulated the effects of BH3 mimetics and enhanced the effects of gamitrinib-TPP. Mechanistic investigations revealed that gamitrinib-TPP activated a PERK-dependent integrated stress response, which activated the proapoptotic BH3 protein Noxa and its downstream targets Usp9X and Mcl-1. Notably, in the PDX glioblastoma and BRAFi-resistant melanoma models, this drug combination safely and significantly extended host survival. Our results show how combining mitochondrial chaperone and Bcl-2 family inhibitors can synergize to safely degrade the growth of tumors recalcitrant to other treatments. Cancer Res; 77(13); 3513-26. ©2017 AACR.