Cytosolic and nuclear caspase-8 have opposite impact on survival after liver resection for hepatocellular carcinoma

Cell death shapes cancer immunity: spotlighting PANoptosis

PANoptosis represents a novel type of programmed cell death (PCD) with distinctive features that incorporate elements of pyroptosis, apoptosis, and necroptosis. PANoptosis is governed by a newly discovered cytoplasmic multimeric protein complex known as the PANoptosome. Unlike each of these PCD types individually, PANoptosis is still in the early stages of research and warrants further exploration of its specific regulatory mechanisms and primary targets. In this review, we provide a brief overview of the conceptual framework and molecular components of PANoptosis. In addition, we highlight recent advances in the understanding of the molecular mechanisms and therapeutic applications of PANoptosis. By elucidating the complex crosstalk between pyroptosis, apoptosis and necroptosis and summarizing the functional consequences of PANoptosis with a special focus on the tumor immune microenvironment, this review aims to provide a theoretical basis for the potential application of PANoptosis in cancer therapy.

Caspase-8 and Tyrosine Kinases: A Dangerous Liaison in Cancer

Caspase-8 is a cysteine-aspartic acid protease that has been identified as an initiator caspase that plays an essential role in the extrinsic apoptotic pathway. Evasion of apoptosis is a hallmark of cancer and Caspase-8 expression is silenced in some tumors, consistent with its central role in apoptosis. However, in the past years, several studies reported an increased expression of Caspase-8 levels in many tumors and consistently identified novel "non-canonical" non-apoptotic functions of Caspase-8 that overall promote cancer progression and sustain therapy resistance. These reports point to the ability of cancer cells to rewire Caspase-8 function in cancer and raise the question of which are the signaling pathways aberrantly activated in cancer that may contribute to the hijack of Caspase-8 activity. In this regard, tyrosine kinases are among the first oncogenes ever identified and genomic, transcriptomic and proteomic studies indeed show that they represent a class of signaling molecules constitutively activated in most of the tumors. Here, we aim to review and discuss the role of Caspase-8 in cancer and its interplay with Src and other tyrosine kinases.

Characteristic of molecular subtypes based on PANoptosis-related genes and experimental verification of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a type of liver cancer that originates from liver cells. It is one of the most common types of liver cancer and a leading cause of cancer-related death worldwide. Early detection and treatment can improve the HCC prognosis. Therefore, it is necessary to further improve HCC markers and risk stratification. PANoptosome is a cytoplasmic polymer protein complex that regulates a proinflammatory programmed cell death pathway called "PANoptosis". The role of PANoptosis in HCC remains unclear. In this study, the molecular changes of PANoptosis related genes (PAN-RGs) in HCC were systematically evaluated. We characterized the heterogeneity of HCC by using consensus clustering to identify two distinct subtypes. The two subtypes showed different survival rate, biological function, chemotherapy drug sensitivity and immune microenvironment. After identification of PAN-RG differential expression genes (DEGs), a prognostic model was established by Cox regression analysis using minimum absolute contraction and selection operator (LASSO), and its prognostic value was verified by Cox regression analysis, Kaplan-Meier curve and receiver operating characteristic (ROC) curve. Our own specimens were also used to further validate the prognostic significance and possible clinical value of the selected targets. Subsequently, we conducted a preliminary discussion on the reasons for the influence of the model on the prognosis through TME analysis, drug resistance analysis, TMB analysis and other studies. This study provides a new idea for individualized and precise treatment of HCC.

The interaction of CFLAR with p130Cas promotes cell migration

CASP8 and FADD Like Apoptosis Regulator (CFLAR) is a key anti-apoptotic regulator for resistance to apoptosis mediated by Fas and TRAIL. In addition to its anti-apoptotic function, CFLAR is also an important mediator of tumor growth. High level of CFLAR expression correlates with a more aggressive tumor. However, the mechanism of CFLAR signaling in malignant progression is not clear. Here we report a novel CFLAR-associated protein p130Cas, which is a general regulator of cell growth and cell migration. CFLAR-p130Cas association is mediated by the DED domain of CFLAR and the SD domain of p130Cas. Immunofluorescence observation showed that CFLAR had the colocalization with p130Cas at the focal adhesion of cell membrane. CFLAR overexpression promoted p130Cas phosphorylation and the formation of focal adhesion complex. Moreover, the enhancement of cell migration induced by CFLAR overexpression was obviously inhibited by p130Cas siRNA. In silico analysis on human database suggests high expressions of CFLAR or/and p130Cas are associated with poor prognosis of patients with lung cancer. Together, our results suggest a new mechanism for CFLAR involved in tumor development via association with p130Cas.

High expression of caspase‐8 as a predictive factor of poor prognosis in patients with esophageal cancer

BACKGROUND

Esophageal carcinoma (ESCA) is considered to be one of the most common gastrointestinal cancers. Caspase-8 (CASP8) is a key protein of cross-talk signaling in a variety of cancers. However, the role of CASP8 expression in the prognosis of patients with ESCA has remained unexplored. Hence, it is needed to explore the clinical significance of CASP8 expression in ESCA.

METHODS

The expression and prognosis of CASP8 were investigated in ESCA using the UALCAN, GEDS, TIMER, and OncoLnc databases. The CASP8 genetic variations in ESCA were assessed using the cBioPortal database. The correlation between CASP8 expression and tumor immune invasion and immune cell surface indicators was examined using the TIMER and TISIDTISIDB datasets. Meanwhile, the abundance of the immunological cells in the tumor and healthy tissues was assessed by the CIBERSORT method. Next, information on the co-expressed genes of the differentially expressed genes (DEGs) in ESCA-tumor and ESCA-healthy tissues was obtained using the cBioPortal, UALCAN, and Coexpedia databases. Subsequently, the PPI network was constructed and the GO and KEGG pathways were analyzed using the SIRING database. Finally, CASP8 mRNA and protein expression in the ESCA tissues and matched adjacent healthy tissues were analyzed using qRT-PCR, immune-blotting, and immunohistochemistry. Additionally, the relationship between clinicopathological features and CASP8 expression was assessed.

RESULTS

ESCA tissues had higher levels of CASP8 mRNA and protein expression compared to healthy tissues. patients with an elevated level of CASP8 expression had poor overall survival (OS). CASP8 expression was significantly correlated with the degree of differentiation (P = 0.004) and lymph node metastasis (P = 0.044). There were diverse patterns of association between immunological cell surface biomarkers and CASP8 expression.

CONCLUSION

ESCA showed significant levels of CASP8 expression which may serve as a prognostic biomarker correlated to immune infiltrates in ESCA.

Prognostic Impact of Caspase-8, CDK9 and Phospho-CDK9 (Thr 186) Expression in Patients with Uterine Cervical Cancer Treated with Definitive Chemoradiation and Brachytherapy

Introduction: After primary platinum-based chemoradiation of locally advanced uterine cervical cancer, a substantial proportion of women present with persistent, recurrent or metastatic disease, indicating an unmet need for biomarker development. Methods: We evaluated the clinical records of 69 cervical cancer patients (Federation of Gynecology and Obstetrics, FIGO Stage > IB3) who were subjected to definitive CRT. Immunohistochemical scoring of caspase-8, cyclin dependent kinase 9 (CDK9) and phosphorylated (phospho-)CDK9 (threonine (Thr) 186) was performed on pretreatment samples and correlated with the histopathological and clinical endpoints, including relapse-free survival (RFS), distant metastasis-free survival (DMFS), cancer-specific survival (CSS) and overall survival (OS). Results: Lower levels of caspase-8 were more prevalent in patients with a higher T-stage (p = 0.002) and a higher FIGO stage (p = 0.003), and were significantly correlated with CDK9 expression (p = 0.018) and inversely with pCDK9 detection (p = 0.014). Increased caspase-8 levels corresponded to improved RFS (p = 0.005), DMFS (p = 0.038) and CSS (p = 0.017) in the univariate analyses. Low CDK9 expression was associated with worse RFS (p = 0.008), CSS (p = 0.015) and OS (p = 0.007), but not DMFS (p = 0.083), and remained a significant prognosticator for RFS (p = 0.003) and CSS (p = 0.009) in the multivariate analyses. Furthermore, low pCDK9 staining was significantly associated with superior RFS (p = 0.004) and DMFS (p = 0.001), and increased CSS (p = 0.022), and remained significant for these endpoints in the multivariate analyses. Conclusion: Increased caspase-8 and CDK9 levels correlate with improved disease-related outcomes in cervical cancer patients treated with CRT, whereas elevated pCDK9 levels predict worse survival in this patient population.

A Pyroptosis-Related Gene Signature to Predict Patients’ Prognosis and Immune Landscape in Liver Hepatocellular Carcinoma

Background

Liver hepatocellular carcinoma (LIHC) is a malignance with high incidence and recurrence. Pyroptosis is a programed cell death pattern which both activates the effective immune response and causes cell damage. However, their potential applications of pyroptosis-related genes (PRGs) in the prognostic evaluation and immunotherapy of LIHC are still rarely discussed.

Methods

Comprehensive bioinformatics analyses based on TCGA-LIHC dataset were performed in the current study.

Results

A total of 33 PRGs were selected to perform the current study. Of these 33 PRGs, 26 PRGs with upregulation or downregulation in LIHC tissues were identified. We also summarized the related genetic mutation variation landscape. GO and KEGG pathway analysis demonstrated that these 26 PRGs were primarily associated with pyroptosis, positive regulation of interleukin-1 beta production, and NOD-like receptor signaling pathway. An unfavorable OS appeared in LIHC patients with high CASP3, CASP4, CASP6, CASP8, GPX4, GSDMA, GSDME, NLRP3, NLRP7, NOD1, NOD2, PLCG1, and SCAF11 expression and low NLRP6 expression. A prognostic signature constructed by the above 14 prognostic PRGs had moderate to high accuracy to predict LIHC patients' prognosis. And risk score was correlated with the expression of CASP6, CASP8, GPX4, GSDMA, GSDME, NLRP6, and NOD2. Of these 7 genes, CASP8 was identified as the core gene in PPI network. Moreover, lncRNA MIR17HG/hsa-miRNA-130b-3p/CASP8 regulatory axis in LIHC was also detected.

Conclusions

The current study indicated the crucial role of PRGs in the prognostic evaluation of LIHC patients and their correlations with tumor microenvironment in LIHC.

The role of caspase-8 in the tumor microenvironment of ovarian cancer

Caspase-8 is an aspartate-specific cysteine protease, which is best known for its apoptotic functions. Caspase-8 is placed at central nodes of multiple signal pathways, regulating not only the cell cycle but also the invasive and metastatic cell behavior, the immune cell homeostasis and cytokine production, which are the two major components of the tumor microenvironment (TME). Ovarian cancer often has dysregulated caspase-8 expression, leading to imbalance between its apoptotic and non-apoptotic functions within the tumor and the surrounding milieu. The downregulation of caspase-8 in ovarian cancer seems to be linked to high aggressiveness with chronic inflammation, immunoediting, and immune resistance. Caspase-8 plays therefore an essential role not only in the primary tumor cells but also in the TME by regulating the immune response, B and T lymphocyte activation, and macrophage differentiation and polarization. The switch between M1 and M2 macrophages is possibly associated with changes in the caspase-8 expression. In this review, we are discussing the non-apoptotic functions of caspase-8, highlighting this protein as a modulator of the immune response and the cytokine composition in the TME. Considering the low survival rate among ovarian cancer patients, it is urgently necessary to develop new therapeutic strategies to optimize the response to the standard treatment. The TME is highly heterogenous and provides a variety of opportunities for new drug targets. Given the variety of roles of caspase-8 in the TME, we should focus on this protein in the development of new therapeutic strategies against the TME of ovarian cancer.

Cancer Cells Employ Nuclear Caspase-8 to Overcome the p53-Dependent G2/M Checkpoint through Cleavage of USP28

Cytosolic caspase-8 is a mediator of death receptor signaling. While caspase-8 expression is lost in some tumors, it is increased in others, indicating a conditional pro-survival function of caspase-8 in cancer. Here, we show that tumor cells employ DNA-damage-induced nuclear caspase-8 to override the p53-dependent G2/M cell-cycle checkpoint. Caspase-8 is upregulated and localized to the nucleus in multiple human cancers, correlating with treatment resistance and poor clinical outcome. Depletion of caspase-8 causes G2/M arrest, stabilization of p53, and induction of p53-dependent intrinsic apoptosis in tumor cells. In the nucleus, caspase-8 cleaves and inactivates the ubiquitin-specific peptidase 28 (USP28), preventing USP28 from de-ubiquitinating and stabilizing wild-type p53. This results in de facto p53 protein loss, switching cell fate from apoptosis toward mitosis. In summary, our work identifies a non-canonical role of caspase-8 exploited by cancer cells to override the p53-dependent G2/M cell-cycle checkpoint.

Targeting p53/TRAIL/caspase-8 signaling by adiponectin reverses thioacetamide-induced hepatocellular carcinoma in rats

Given the enormous impact of HCC on the patients' quality of life and healthcare economics, the current study was conducted to investigate the potential ability of adiponectin to reverse established HCC and to investigate the underlying mechanisms which control the chemotherapeutic and hepatoprotective effects. HCC was induced in Male Sprague Dawely rats by I.P. injection of thioacetamide(200 mg/kg) 3 times/week for 14 weeks.HCC development was confirmed by histopathological examination and assessment of serum levels of α-fetoprotein (AFP). Adiponectin was administered (5 μg/kg, I.P.) starting from week 13 of the experiment and for further 4 weeks. Adiponectinadministration revealed a significant antitumor activity with significant improvement in liver functions and oxidative status. Nevertheless, pathological features as cirrhosis, dysplastic changes, and tumoral nodules were significantly attenuated with significant enhancement in hepatic caspase-3 immunostaining. Mechanistically, adiponectin administration was associated with significant restoration of p53 activity; which increased by 133%, with a reduction in HCC-induced expression of-JNK which decreased by 53%as well as a significant enhancement of hepatic TRAIL and caspase-8 activities which increased by 27% and 20% respectively. In conclusion; Adiponectin can be proposed as a promising therapy for HCC. Adiponectin's tumoricidal activity can be partially mediated by blocking HCC-induced reduction in p53 expression as well as reactivation of TRAIL signaling and induction of apoptotic pathway providing more protection for the body against the tumor.

TRAIL Induces Nuclear Translocation and Chromatin Localization of TRAIL Death Receptors

Binding of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) to the plasma membrane TRAIL-R1/-R2 selectively kills tumor cells. This discovery led to evaluation of TRAIL-R1/-R2 as targets for anti-cancer therapy, yet the corresponding clinical trials were disappointing. Meanwhile, it emerged that many cancer cells are TRAIL-resistant and that TRAIL-R1/-R2-triggering may lead to tumor-promoting effects. Intriguingly, recent studies uncovered specific functions of long ignored intracellular TRAIL-R1/-R2, with tumor-promoting functions of nuclear (n)TRAIL-R2 as the regulator of let-7-maturation. As nuclear trafficking of TRAIL-Rs is not well understood, we addressed this issue in our present study. Cell surface biotinylation and tracking of biotinylated proteins in intracellular compartments revealed that nTRAIL-Rs originate from the plasma membrane. Nuclear TRAIL-Rs-trafficking is a fast process, requiring clathrin-dependent endocytosis and it is TRAIL-dependent. Immunoprecipitation and immunofluorescence approaches revealed an interaction of nTRAIL-R2 with the nucleo-cytoplasmic shuttle protein Exportin-1/CRM-1. Mutation of a putative nuclear export sequence (NES) in TRAIL-R2 or the inhibition of CRM-1 by Leptomycin-B resulted in the nuclear accumulation of TRAIL-R2. In addition, TRAIL-R1 and TRAIL-R2 constitutively localize to chromatin, which is strongly enhanced by TRAIL-treatment. Our data highlight the novel role for surface-activated TRAIL-Rs by direct trafficking and signaling into the nucleus, a previously unknown signaling principle for cell surface receptors that belong to the TNF-superfamily.

In vitro cytotoxicity and anticancer effects of citral nanostructured lipid carrier on MDA MBA-231 human breast cancer cells

Very recently, we postulated that the incorporation of citral into nanostructured lipid carrier (NLC-Citral) improves solubility and delivery of the citral without toxic effects in vivo. Thus, the objective of this study is to evaluate anti-cancer effects of NLC-Citral in MDA MB-231 cells in vitro through the Annexin V, cell cycle, JC-1 and fluorometric assays. Additionally, this study is aimed to effects of NLC-Citral in reducing the tumor weight and size in 4T1 induced murine breast cancer model. Results showed that NLC-Citral induced apoptosis and G2/M arrest in MDA MB-231 cells. Furthermore, a prominent anti-metastatic ability of NLC-Citral was demonstrated in vitro using scratch, migration and invasion assays. A significant reduction of migrated and invaded cells was observed in the NLC-Citral treated MDA MB-231 cells. To further evaluate the apoptotic and anti-metastatic mechanism of NLC-Citral at the molecular level, microarray-based gene expression and proteomic profiling were conducted. Based on the result obtained, NLC-Citral was found to regulate several important signaling pathways related to cancer development such as apoptosis, cell cycle, and metastasis signaling pathways. Additionally, gene expression analysis was validated through the targeted RNA sequencing and real-time polymerase chain reaction. In conclusion, the NLC-Citral inhibited the proliferation of breast cancer cells in vitro, majorly through the induction of apoptosis, anti-metastasis, anti-angiogenesis potentials, and reducing the tumor weight and size without altering the therapeutic effects of citral.

Immunomodulatory, Apoptosis Induction and Antitumor Activities of Aqueous and Methanolic Extract of Calvatia Craniiformis in Mice Transfected with Murine Hepatocellular Carcinoma Cells

OBJECTIVES:

To evaluate the Immunomodulatory, apoptosis induction and antitumor effects of aqueous and methanolic extracts of Calvatia craniiformis regarding the size of tumour mass, caspase-8 expression and apoptotic index (AI%) in mice transfected with murine hepatocellular carcinoma cell line (H22) as an experimental therapeutic system for human hepatocellular carcinoma.

MATERIAL AND METHODS:

Forty-eight Balb/C albino mice were transfected in legs with H22 cells. Tumour size was measured twice a week. Caspase-8 protein expression and apoptotic index determination evaluated by Immunohistochemistry.

RESULTS:

Tumor size significantly differed between the two groups of mice transfected with H22 cells; the first was treated with C. craniiformis aqueous extract (0.3, 0.6, 1.2) mg/kg and the second group was treated with C. craniiformis methanolic extract (0.25, 0.5, 1.0) mg/kg compared with control group. The inhibitory activity of aqueous and methanolic extracts was dose and duration dependent. The size of the tumour mass was reduced up to 87.9% when treated with 1.2 mg/kg aqueous extract and 1 mg/kg for methanolic extract. Caspase-8 expression was increased in a dose-dependent manner among H22 bearing mice treated with C. craniiformis aqueous extract (0.3, 0.6, 1.2) mg/kg. At 0.3 mg/kg, the intensity of expression was strong in (33.33%) and very strong in (66.67%). While at 0.6 mg/kg and 1.2 mg/kg the intensity of expression was strong in (33.33%) and very strong in (100%) with a significant difference (P ≤ 0.001). H22 bearing mice treated with (0.25, 0.5, 1.0) mg/kg C. craniiformis methanolic extract shows increased caspase-8 expression in a dose-dependent manner. At 0.25 mg/kg, the intensity of expression was strong in (33.33%) and very strong in (66.67%). While at 0.5 mg/kg, the intensity of expression was strong in (33.33%) and very strong in (100%). At 1.0 mg/kg, the intensity of expression was strong in (16.67%) and very strong in (83.33%) with significant difference (P ≤ 0.001). AI% of H22 bearing mice treated with C. craniiformis aqueous and methanolic extracts were significantly increased (P ≤ 0.05) compared with the untreated control group. No significant difference was reported in AI% between aqueous and methanolic extracts treated groups.

CONCLUSIONS:

Extracts of C. craniiformis were highly efficient in tumour growth inhibition, causing a reduction in the tumour size clinically and increase the expression of caspase-8 gene product in tumour tissue, causing increase apoptotic index of H22 cells taken from the legs of inoculated mice leading to loss of legs due to bone necrosis. Antitumor activity of C. craniiformis aqueous, and the methanolic extract was dose and duration dependent.

The determination of stage in nonmuscle urothelial carcinoma: Staining pattern of caspase-8

Context

Urothelial carcinoma (UC) is one of the most frequent epithelial tumors worldwide.

Aims

We aimed to investigate the protein expressions of caspase-8, p53, murine double minute 2 (mdm2), and p14^ARF in nonmuscle UCs and to correlate the findings with clinicopathological characteristics.

Settings and Design:

A total of 50 patients who had pTa and pT1 tumors were analyzed.

Subjects and Methods

The protein expressions of caspase-8, p53, mdm2, and p14^ARF were analyzed by immunohistochemistry.

Statistical Analysis Used

Chi-square test was done using SPSS version 16.0 (SPSS, Inc., Chicago, IL, USA).

Results

Cytoplasmic caspase-8 expression was significantly higher in pT1 UCs while nuclear caspase-8 expression was significantly higher in pTa UCs (P = 0.005 and P = 0.011, respectively). Cytoplasmic caspase-8 expression was also higher in high-grade UCs (P = 0.035). The expression of p53, mdm2, and p14^ARF was not also related with pathological stage or grade (P > 0.05 for all). The p14^ARF expression was related with nuclear caspase-8 expression in most of the patients. Complete agreement among nonmuscle UCs for immunohistochemical expression of p14 and nuclear caspase-8 was seen in 41 cases, and the pairwise kappa agreement value was substantial (κ =0.614). The patients who had recurrence were positive for both p53 and mdm2 or either p53 or mdm2 (P = 0.025).

Conclusions

These results suggested that the staining pattern of caspase-8 might be helpful for determining of the stages in nonmuscle UC. It was also showed that the expression status of p53 and mdm2 were related with the recurrence.

Isoquercitrin inhibits bladder cancer progression in vivo and in vitro by regulating the PI3K/Akt and PKC signaling pathways

Bladder cancer is the most common malignancy of the urinary system and is also one of the 10 most common cancers of the human body. Currently, clinical treatment of bladder cancer mainly utilizes partial or total cystectomy, supplemented by conventional chemotherapy. However, such treatment has not fully improved the prognosis of patients and is associated with various side effects. Studies have found that flavonoids extracted from plants can be used in radiotherapy and chemotherapy for the prevention of postoperative recurrence and metastasis but also alone for the treatment of advanced tumors. Both applications can ameliorate clinical symptoms, improve the quality of life, and prolong the survival of patients. Based on the above information, the present study investigated the effect of isoquercitrin, a type of flavonoid found in Bidens pilosa L. extracts, on bladder cancer progression, with the goal of understanding the biological characteristics of isoquercitrin by which it participates in bladder cancer progression. Using in vitro experiments, we found that therapeutic doses of isoquercitrin significantly inhibited cell proliferation and induced apoptosis in human bladder cancer cells and that the cell cycle was arrested in the G1 phase. Isoquercitrin inhibited phosphatidylinositol 3-kinase (PI3K) and Akt phosphorylation expression levels, thus inhibiting proliferation and inducing apoptosis in the cancer cells. In addition, we found that isoquercitrin reduced protein kinase C (PKC) protein expression levels in the human bladder cancer cell lines. We also showed via in vivo experiments that isoquercitrin inhibited xenograft tumor growth in nude mice. In conclusion, our study confirmed that isoquercitrin inhibits bladder cancer progression in vivo and demonstrated that the molecular mechanism of this inhibition may be closely associated with the PI3K/Akt and PKC signaling pathways.

Isoquercitrin inhibits the progression of liver cancer in vivo and in vitro via the MAPK signalling pathway

Liver cancer is a malignant tumour with high morbidity and fatality rates that is common worldwide. At present, the clinical approaches to treating primary liver cancer include partial hepatectomy, systemic or local chemotherapy, radiotherapy, radiofrequency ablative surgery and liver transplantation. However, all of these approaches have shortcomings, including poor prognosis and numerous side-effects. A large number of studies have proven that many effective ingredients in traditional Chinese medicine, particularly the flavonoid compounds extracted from plants, have achieved breakthroughs in terms of enhancing the effects and reducing the toxicity of chemotherapy and radiotherapy, preventing tumour metastasis and relapse after surgery, alleviating the clinical symptoms of advanced tumours, improving the quality of life of the patient with tumours and extending patient long‑term survival. The purpose of the present study was to investigate the impact of isoquercitrin, the flavonoid from Bidens bipinnata L. extract, on the progression of liver cancer and to achieve a deeper understanding of the biological characteristics of isoquercitrin's involvement in the progression of liver cancer. In the in vitro experiments, isoquercitrin was found to strongly inhibit the proliferation of human liver cancer cells, promote the apoptosis of human liver cancer cells, and block the cell cycle in the G1 phase. Isoquercitrin activated caspase-3, -8 and -9, inhibited the expression level of ERK and p38MAPK protein phosphorylation, and promoted the phosphorylation of JNK. Additionally, isoquercitrin reduced the expression level of PKC in human liver cancer cells. In the in vivo experiments, isoquercitrin was also found to significantly inhibit the growth of transplanted tumours in nude mice. The present study confirmed that isoquercitrin could inhibit the progression of human liver cancer in vivo and in vitro, and the molecular mechanism of isoquercitrin may be closely associated with the MAPK and PKC signalling pathways.