Cantharidic acid induces apoptosis through the p38 MAPK signaling pathway in human hepatocellular carcinoma

HO-3867, a curcumin analog, elicits cell apoptosis and p38-mediated caspase activation in hepatocellular carcinoma

HO-3867, a synthetic curcumin analog, has displayed various tumor-suppressive characteristics and improved bioabsorption over its parent compound. However, its influences on the development of hepatocellular carcinoma (HCC) are poorly defined. To address this, we tested the anticarcinogenic impact of HO-3867 and investigated the underlying mechanisms in fighting liver cancer. Our result demonstrated that HO-3867 reduced the viability of HCC cells, accompanied by promotion of cell cycle arrest at the sub-G1 stage and apoptotic responses. Furthermore, a distinctive profile of apoptosis associated proteins, encompassing elevated heme oxygenase-1 (HO-1) level and caspase activation, was detected in HO-3867-stimulated HCC cells. In addition, such HO-3867-mediated elevation in caspase activation was dampened by pharmacological suppression of p38 activities. Taken together, our findings unveiled that HO-3867 triggered cell cycle arrest and apoptotic events in liver cancer, involving a p38-mediated activation of caspase cascades. These data highlighted a usefulness of curcumin or its analogs on the management of hepatocarcinogenesis.

Integrative analysis of the molecular signature of target genes involved in the antitumor effects of cantharidin on hepatocellular carcinoma

BACKGROUND

Cantharidin (CTD) is the active ingredient of Chinese medicine, which has been traditionally used in multiple cancers treatment, especially in hepatocellular carcinoma (HCC). However, a comprehensive analysis of the CTD-related molecular mechanism is still necessary to understand its functions in HCC treatment. This study aimed to reveal the novel molecular targets and regulatory networks of CTD in HCC.

METHODS

A model of H22 tumour-bearing mice was constructed, and the function of CTD in tumour growth was evaluated. An integrated approach of CTD associated transcriptional profiling and biological systems analysis was used to identify key regulators involved in antitumour pathways. The identified differential expression patterns were supported by the results of Gene Ontology (GO) term and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyse, and by protein-protein interaction (PPI) network construction. The relationships between gene expression and tumour immunity were evaluated using Tumour Immune Estimation Resource (TIMER). Prognostic value was analyzed with Kaplan-Meier plotter.

RESULTS

In the present study, the therapeutic effect of CTD on HCC was evaluated in vivo. We obtained the CTD-related transcriptional profiles, systematically and intuitively illustrated its possible pharmacological mechanisms in HCC through multiple targets and signalling pathways. These results revealed that the CTD-related differentially expressed genes were involved in autophagy, transcription factors (TFs) related transcriptional regulation, fatty acid metabolism and immune response in HCC. We found that MAPT, TOP2A, CENPF and MEFV were hub genes of CTD targets involved in autophagy regulation. Totally, 14 TFs have been confirmed to be critical for transcriptional regulation, and 33 TF targets were identified as the hub genes in transcriptional mis-regulation pathway in cancer. These TFs were associated with the immune response and immune cell infiltration. In addition, the downregulated genes were significantly enriched in metabolic regulation pathways, especially fatty acid metabolism after CTD treatment. Furthermore, the network of CTD associated miRNAs with these fatty acid metabolism-related targets was constructed in HCC.

CONCLUSIONS

Taken together, our results comprehensively elucidated that CTD could act on multiple targets in HCC therapy, affecting autophagy, transcriptional regulation, the immune response and fatty acid metabolism. Our results provide a foundation for the study of the molecular mechanistic of CTD and its clinical application in the treatment of HCC.

Hepatotoxic mechanism of cantharidin: insights and strategies for therapeutic intervention

Cantharidin (CTD), a natural compound derived from Mylabris, is widely used in traditional Oriental medicine for its potent anticancer properties. However, its clinical application is restricted due to its high toxicity, particularly towards the liver. This review provides a concise understanding of the hepatotoxic mechanisms of CTD and highlights novel therapeutic strategies to mitigate its toxicity while enhancing its anticancer efficacy. We systematically explore the molecular mechanisms underlying CTD-induced hepatotoxicity, focusing on the involvement of apoptotic and autophagic processes in hepatocyte injury. We further discuss the endogenous and exogenous pathways implicated in CTD-induced liver damage and potential therapeutic targets. This review also summarizes the structural modifications of CTD derivatives and their impact on anticancer activity. Additionally, we delve into the advancements in nanoparticle-based drug delivery systems that hold promise in overcoming the limitations of CTD derivatives. By offering valuable insights into the hepatotoxic mechanisms of CTD and outlining potential avenues for future research, this review contributes to the ongoing efforts to develop safer and more effective CTD-based therapies.

Cantharidin suppresses hepatocellular carcinoma development by regulating EZH2/H3K27me3-dependent cell cycle progression and antitumour immune response

BACKGROUND

Cantharidin (CTD) is a major ingredient of cantharis (Mylabris phalerata Pallas) and has been used extensively in traditional Chinese medicines. It has been shown to exhibit anticancer activity in multiple types of cancer, especially hepatocellular carcinoma (HCC). However, there is no systematic study on the relationships among the regulatory networks of its targets in HCC therapy. We focused on histone epigenetic regulation and the influence of CTD on the immune response in HCC.

METHODS

We performed a comprehensive analysis of novel CTD targets in HCC based on network pharmacology and RNA-seq approaches. The mRNA levels of target genes were analyzed by qRT-PCR, and the corresponding protein levels were confirmed using enzyme-linked immunosorbent assay (ELISA) and immunohistochemical staining (IHC). ChIP-seq data were visualized by IGV software. The associations of gene transcript levels with the cancer immune score and infiltration level were investigated using TIMER. In vivo, the H22 mouse model of hepatocellular carcinoma was established by treatment with CTD and 5-Fu. The immune cell proportions in the blood were elevated in model mice, as shown by flow cytometry.

RESULTS

We identified 58 targets of CTD, which were involved in various pathways in cancer, including apoptosis, the cell cycle, EMT and immune pathways. Moreover, we found that 100 EMT-related genes were differentially expressed after CTD treatment in HCC cells. Interestingly, our results confirmed that the EZH2/H3K27me3 -related cell cycle pathway is a therapeutic target of CTD in antitumour. In addition, we evaluated the influence of CTD on the immune response. Our data showed that the significantly enriched gene sets were positively correlated with the chemokine biosynthetic and chemokine metabolic modules. The proportions of CD4+/CD8 + T cells and B cells were increased, but the proportion of Tregs was decreased after treatment with CTD in vivo. Moreover, we found that the expression of the inflammatory factor and immune checkpoint genes PD-1/PD-L1 was significantly reduced in the mouse model.

CONCLUSION

We performed a novel integrated analysis of the potential role of CTD in HCC treatment. Our results provide innovative insight into the mechanism by which cantharidin exerts antitumour effects by regulating target genes expression to mediate apoptosis, EMT, cell cycle progression and the immune response in HCC. Based on the effect of CTD on the immune response, it can be used as a potential effective drug to activate antitumour immunity for the treatment of liver cancer.

Identification of the molecular targets and mechanisms of compound mylabris capsules for hepatocellular carcinoma treatment through network pharmacology and bioinformatics analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Traditional Chinese herbal formulas have been proven to exert an inhibitory effect on tumor. Compound mylabris capsules (CMC) has been used for treating cancer, especially hepatocellular carcinoma (HCC), for years in China. However, its therapeutic mechanisms on HCC remain unclear.

AIM OF THE STUDY

This research aimed to elucidate the molecular targets and mechanisms of CMC for treating HCC.

MATERIALS AND METHODS

First, the bioactive ingredients and potential targets of CMC, as well as HCC-related targets were retrieved from publicly available databases. Next, the overlapped genes between potential targets of CMC and HCC-related targets were determined using bioinformatics analysis. Then, networks of ingredient-target and gene-pathway were constructed. Finally, cell experiments were carried out to examine the effects of CMC-medicated serum on HCC and validate the core molecular targets.

RESULTS

In total, 151 bioactive ingredients and 255 potential targets of CMC were selected, 982 differentially expressed genes of HCC were identified. Among them, 34 overlapped genes were finally selected. In addition, 20 pathways and 429 GO terms were significantly enriched. Protein-protein interaction and gene-pathway networks indicated that Cyclin B1(CCNB1) and Cyclin Dependent Kinase 1(CDK1) were the core gene targets for the treatment of CMC on HCC. Moreover, in vitro studies showed that CMC-medicated serum significantly inhibited the viability of HepG2 cells. Furthermore, CMC downregulated CCNB1 and CDK1 expressions and induced G2/M phase cell cycle arrest.

CONCLUSIONS

CMC plays a therapeutic role in HCC via multi-component, -target and -pathway mechanisms, in which CCNB1 and CDK1 may be the core molecular targets. This study indicates that the integration of network pharmacology and bioinformatics analysis, followed by experimental validation, can serves as an effective tool for studying the therapeutic mechanisms of traditional Chinese medicine.

Erianin suppresses hepatocellular carcinoma cells through down-regulation of PI3K/AKT, p38 and ERK MAPK signaling pathways

BACKGROUND

Hepatocellular carcinoma (HCC) is the dominant pathological type of primary liver cancer and no effective methods are available for its treatment. Erianin is a natural product extracted from Dendrobium, which possesses multiple pharmacological activities, including antioxidative and antitumor activity.

OBJECTIVE

To evaluate the anti-HCC activities of erianin and explore its underlying mechanism.

METHODS

MTT assay and Crystal Violet staining assay were used to select the non-toxic concentrations for the subsequent experiments. The colony formation assay and PCNA fluorescent staining were used to investigate the antiproliferative effects of erianin on human SMMC-7721 and HepG2 cells. Wound healing and transwell test were used to analyze cell migration and invasion. Caspase3 and Tunel staining were used to detect apoptosis. Western blot was used to examine the expression levels of proteins associated with invasion and key proteins in the phosphatidylinositol-3-kinase/protein kinase B (PI3K/Akt), p38 and ERK mitogen-activated protein kinase (MAPK) signaling pathways.

RESULTS

Erianin inhibited HCC cell proliferation in a dose-dependent manner. Decreased migration rate and invaded cells were observed with erianin supplement. The expression of invasion-associated proteins in the erianin group was also down-regulated. Besides, more apoptotic cells were observed after erianin treatment. For the molecular mechanism, erianin inhibited the phosphorylation of Akt, ERK and P38 in the PI3K/Akt and ERK/P38 pathway.

CONCLUSION

We demonstrated, for the first time, that erianin inhibited the proliferation, migration, invasion and induced the apoptosis of HCC through PI3K/Akt, p38 and ERK MAPK signaling pathway, indicating that erianin is a promising agent for the HCC treatment.

Fufang Banmao Capsule, a Traditional Chinese Medicinal Formulation, Enhances the Survival of Patients with Hepatocellular Carcinoma and Vp3-4 Portal Vein Tumor Thrombosis Undergoing Supportive Treatment

Objectives: Fufang Banmao (FFBM) capsule, a type of Chinese medicinal formulation, has decades of history in treating hepatocellular carcinoma (HCC). This retrospective study aimed to observe the effect of FFBM capsules on the 6-month survival of patients with advanced HCC and Vp3-4 portal vein tumor thrombosis (PVTT) who received supportive therapy alone. Design: In total, 320 HCC/Vp3-4 PVTT patients underwent treatment with supportive therapy, of whom 95 took FFBM capsules and were treated with supportive therapy (FFBM group) and 225 received supportive therapy alone (control group). Comparisons of the 6-month overall survival (OS) rate of the two groups were performed. Propensity score matching (PSM) was used to match the characteristics between individuals in the two groups. A nomogram was built based on independent predictive factors for OS. Results: Cox multivariate analysis revealed that hepatic encephalopathy, aspartate transaminase (AST) and γ-glutamyl transpeptidase levels, Child-Pugh class, prothrombin time, α-fetoprotein level, largest tumor diameter, and use of FFBM capsules were independent predictive factors of OS. Variceal bleeding, alanine transaminase, AST, total bilirubin, and Barcelona Clinic for Liver Cancer stage were different at baseline in the FFBM and control groups. Analysis revealed no significant adverse effects or toxicities relevant to the medications. After PSM (1:1), 95 patient pairs were analyzed as FFBM versus control. The OS probability was remarkably higher for patients in the FFBM group than in those in the control group at 6 months (p < 0.0001). The median survival time was 4 months in the FFBM group and 2.2 months in the control group. Kaplan-Meier analysis showed significant statistical differences in the 6-month OS rates in the patients with total nomogram scores ≥84 (p < 0.0001). Conclusions: Given the satisfying survival outcomes, the results suggested that FFBM capsules should be administered to patients with HCC/Vp3-4 PVTT in the high-risk group (score ≥84). FFBM capsules have the potential for improving patient survival time in those with advanced HCC and Vp3-4 PVTT who receive supportive therapy alone, especially those in the high-risk group (score ≥84).

Cantharidic acid induces apoptosis in human nasopharyngeal carcinoma cells through p38-mediated upregulation of caspase activation

Cantharidic acid (CA) is the hydrolysis product of the acid anhydride cantharidin, which is a natural toxin secreted by several species of blister beetles. Several studies have indicated that as an inhibitor of protein phosphatase 2 (PP2A), CA induces apoptosis in various human cancer cells. However, the effect of CA on human nasopharyngeal carcinoma (NPC) cells and the underlying pathways have not been addressed. In our current study, we tested the hypothesis that CA treatment reduces the viability of human NPC cells (HONE-1, NPC-39, and NPC-BM) by inducing apoptosis. Results indicated that CA markedly reduced cell viability, which was revealed by the upregulation of caspase activation in extrinsic and intrinsic apoptosis pathways as well as the upregulation of extracellular-signal-regulated kinase 1/2 (ERK1/2), p38, and c-Jun N-terminal kinase 1/2 (JNK1/2) pathways. Coadministration of a p38 inhibitor (SB203580) with CA abolished the activation of caspase proteins. These findings indicated that CA treatment leads to apoptosis in human NPC cells through the upregulation of caspase activation, mediated particularly by the p38 pathway. Hence, CA is a promising therapeutic agent for human NPC.

A novel chemoprotective effect of tiopronin against diethylnitrosamine-induced hepatocellular carcinoma in rats: Role of ASK1/P38 MAPK-P53 signalling cascade

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related death worldwide. Oxidative stress contributes significantly to HCC pathogenesis. In this study, we investigated the possible chemoprotective effect of the thiol group-containing compound, tiopronin, against HCC induced chemically by diethylnitrosamine (DENA) in rats. In addition, we elucidated the possible underlying molecular mechanism. Adult male Wistar rats were divided into: Control group, DENA-treated group and tiopronin + DENA-treated group. Liver function tests (ALT, AST, ALP, albumin, total and direct bilirubin) as well as alpha fetoprotein (AFP) concentration were measured in the sera of samples. Oxidative stress biomarkers such as malondialdehyde, nitric oxide, catalase and glutathione peroxidase were measured in the liver tissue homogenates. Determination of the phosphorylated apoptosis signal-regulating kinase 1 (phospho-ASK1), phospho-P38 and phospho-P53 proteins by western blotting, caspase 3 by immunofluorescence in addition to histopathological examination of the liver tissues were performed. Our results showed that tiopronin prevented the DENA-induced elevation of the liver function enzymes and AFP. It also preserved the activities of antioxidant enzymes as well as providing protection from the appearance of HCC histopathological features. Interestingly, tiopronin significantly decreased the expression level of phospho-ASK1, phospho-P38 and phospho-P53, caspase 3 in the liver tissues. These novel findings suggested that tiopronin is an antioxidant drug with a chemoprotective effect against DENA-induced HCC through maintaining the normal activity of ASK1/ P38 MAPK/ P53 signalling pathway.

Thymoquinone suppresses the proliferation of renal cell carcinoma cells via reactive oxygen species-induced apoptosis and reduces cell stemness

Thymoquinone is a phytochemical compound isolated from Nigella sativa and has various biological effects, including anti-inflammation, antioxidation, and anticancer. Here, we further investigated the anticancer effects and associated molecular mechanism of 2-methyl-5-isopropyl-1,4-benzoquinone (thymoquinone) on human renal carcinoma cell lines 786-O and 786-O-SI3 and transitional carcinoma cell line BFTC-909. Results showed that thymoquinone significantly reduced cell viability, inhibited the colony formation of renal cancer cells, and induced cell apoptosis and mitochondrial membrane potential change in both cancer cells. In addition, thymoquinone also triggered the production of reactive oxygen species (ROS) and superoxide and the activation of apoptotic and autophagic cascade. ROS inhibition suppressed the caspase-3 activation and restored the decreased cell viability of 786-O-SI3 in response to thymoquinone. Autophagy inhibition did not restore the cell viability of 786-O-SI3 suppressed by thymoquinone. Moreover, thymoquinone suppressed the cell sphere formation and the expression of aldehyde dehydrogenase, Nanog, Nestin, CD44, and Oct-4 in 786-O-SI3 cells. The tumor-bearing model showed that thymoquinone in vivo inhibited the growth of implanted 786-O-SI3 cell. All these findings indicate that thymoquinone inhibits the proliferation of 786-O-SI3 and BFTC-909 cell possibly due to the induction of ROS/superoxide and the consequent apoptosis, suggesting that thymoquinone may be a potential anticancer supplement for genitourinary cancer.

UPLC-Q-TOF/MS Based Metabolomics Approach to Study the Hepatotoxicity of Cantharidin on Mice

Cantharidin is the major bioactive compound extracted from the blister beetle, a traditional Chinese medicine, and has been proved to be a natural component with widely antitumor activity. However, clinical application of cantharidin is relatively restricted due to its potential toxic effects, especially hepatotoxicity. Although cantharidin-induced liver injury has been reported, the underlying molecular mechanisms remain unclear. In the present study, an UPLC-Q-TOF/MS based metabolomics approach combined with blood biochemical analysis, histopathological examination, and cell apoptosis assay were used to investigate the mechanisms of cantharidin-induced hepatotoxicity. A total of 54 significantly changed metabolites and 14 disturbed metabolic pathways were identified in the cantharidin exposed groups. Among them, four metabolites (oxidized glutathione, glutathione, 3-sulfinoalanine, and deoxycholic acid 3-glucuronide) were selected based on their high impact value and potential biological function in the process of liver injury post cantharidin treatment. Our study provides a deeper understanding of the mechanisms of cantharidin-induced hepatotoxicity and may contribute to reduce the liver injury and gain more effective and safe clinical use of cantharidin. In addition, our results also demonstrated that cantharidin could impair multiple biological processes in liver, and future studies will be necessary to reveal the detailed molecular mechanisms of cantharidin-induced hepatotoxicity.

Effects of adjuvant traditional Chinese medicine therapy on long-term survival in patients with hepatocellular carcinoma

BACKGROUND

Many patients with hepatocellular carcinoma (HCC) in Asian countries seek adjuvant therapy with traditional Chinese medicine (TCM). This study aims to explore the benefits of TCM therapy in the long-term survival of patients with hepatocellular carcinoma in China.

PATIENTS AND METHODS

In total, 3483 patients with HCC admitted to the Beijing Ditan Hospital of Capital Medical University were enrolled in this study. We used 1:1 frequency matching by sex, age, diagnosis time, Barcelona Clinic Liver Cancer staging, and type of treatments to compare the TCM users (n = 526) and non-TCM users (n = 526). A Cox multivariate regression model was employed to evaluate the effects of TCM therapy on the HR value and Kaplan-Meier survival curve for mortality risk in HCC patients. A log-rank test was performed to analyze the effect of TCM therapy on the survival time of HCC patients.

RESULTS

The Cox multivariate analysis indicated that TCM therapy was an independent protective factor for 5-year survival in patients with HCC (adjusted HR = 0.46, 95% CI 0.40-0.52, p < 0.0001). The Kaplan-Meier curve also showed that after PS matching, TCM users had a higher overall survival rate and a higher progression-free survival rate than non-TCM users. TCM users, regardless of the classification of etiology, tumor stage, liver function level, or type of treatment, all benefited significantly from TCM therapy. In addition, it was found that the most commonly used Chinese patent medications are Fufang Banmao Capsule, Huaier Granule, and Jinlong Capsule.

CONCLUSION

Using traditional Chinese medications as adjuvant therapy can probably prolong median survival time and improve the overall survival among patients with HCC. Further scientific studies and clinical trials are needed to examine the efficiency and safety.

Upregulation of microRNA-140-3p inhibits epithelial-mesenchymal transition, invasion, and metastasis of hepatocellular carcinoma through inactivation of the MAPK signaling pathway by targeting GRN

Invasion and metastasis in hepatocellular carcinoma (HCC) results in poor prognosis. Human intervention in these pathological processes may benefit the treatment of HCC. The aim of the present study is to elucidate the mechanism of miR-140-3p affecting epithelial-mesenchymal transition (EMT), invasion, and metastasis in HCC. Microarray analysis was performed for differentially expressed genes screening. The target relationship between miR-140-3p and GRN was analyzed. Small interfering RNA (siRNA) against granulin (GRN) was synthesized. EMT markers were detected, and invasion and migration were evaluated in HCC cells introduced with a miR-140-3p inhibitor or mimic, or siRNA against GRN. A mechanistic investigation was conducted for the determination of mitogen-activated protein kinase (MAPK) signaling pathway-related genes and EMT markers (E-cadherin, N-cadherin, and Vimentin). GRN was highlighted as an upregulated gene in HCC. GRN was a target gene of miR-140-3p. Elevation of miR-140-3p or inhibition of GRN restrained the EMT process and suppressed the HCC cell migration and invasion. HCC cells treated with the miR-140-3p mimic or siRNA-GRN exhibited decreased GRN expression and downregulated the expressions of the MAPK signaling pathway-related genes, N-cadherin, and Vimentin but upregulated the expression of E-cadherin. GRN silencing can reverse the activation of the MAPK signaling pathway and induction of EMT mediated by miR-140-3p inhibition. Taken together, the results show that miR-140-3p confers suppression of the MAPK signaling pathway by targeting GRN, thus inhibiting EMT, invasion, and metastasis in HCC.

Celastrol, a plant-derived triterpene, induces cisplatin-resistance nasopharyngeal carcinoma cancer cell apoptosis though ERK1/2 and p38 MAPK signaling pathway

BACKGROUND

Developing resistance to chemotherapeutic drugs has become a major problem in the management of nasopharyngeal carcinoma (NPC). To overcome this issue, use of natural plant products as chemosensitizers is gaining importance at a fast pace.

HYPOTHESIS/PURPOSE

The present study was designed to evaluate the cytotoxic effect and mode of action of a natural pentacyclic triterpenoid, celastrol, on cisplatin-resistant NPC cells.

RESULTS

Study results revealed that celastrol treatment significantly reduced the viability of NPC cells in dose and time dependent manners, as compared to untreated control cells. The cytotoxic effect of celastrol was mediated by cell cycle arrest at G2/M phase and induction of intrinsic and extrinsic apoptotic pathways. With further analysis, we observed that celastrol-induced activation of caspases was accompanied by increased phosphorylation of MAPK pathway proteins, p38, ERK1/2.

CONCLUSION

Taken together, our observation provides a novel insight on use of a natural plant product, celastrol, in the management of chemoresistant NPC.

Detecting Differentially Variable MicroRNAs via Model-Based Clustering

Identifying differentially variable (DV) genomic probes is becoming a new approach to detect novel genomic risk factors for complex human diseases. The F test is the standard equal-variance test in statistics. For high-throughput genomic data, the probe-wise F test has been successfully used to detect biologically relevant DNA methylation marks that have different variances between two groups of subjects (e.g., cases versus controls). In addition to DNA methylation, microRNA (miRNA) is another important mechanism of epigenetics. However, to the best of our knowledge, no studies have identified DV miRNAs. In this article, we proposed a novel model-based clustering method to improve the power of the probe-wise F test to detect DV miRNAs. We imposed special structures on covariance matrices for each cluster of miRNAs based on the prior information about the relationship between variances in cases and controls and about the independence among them. Simulation studies showed that the proposed method seems promising in detecting DV probes. Based on two real datasets about human hepatocellular carcinoma (HCC), we identified 7 DV-only miRNAs (hsa-miR-1826, hsa-miR-191, hsa-miR-194-star, hsa-miR-222, hsa-miR-502-3p, hsa-miR-93, and hsa-miR-99b) using the proposed method, one (hsa-miR-1826) of which has not yet been reported to be related to HCC in the literature.

Cantharidic acid induces apoptosis of human leukemic HL-60 cells via c-Jun N-terminal kinase-regulated caspase-8/-9/-3 activation pathway

Cantharidin, a natural toxin from blister beetles, has shown potent anticancer activities on many solid tumor cells. Recently, cantharidin and its analogue, norcantharidin, were also shown to suppress nonsolid tumors such as chronic myeloid leukemia, acute myeloid leukemia (AML), and leukemic stem cells. However, there is no available information to address the effects of cantharidic acid (CAC), a hydrolysis product of cantharidin, on human AML cells. The present study showed that CAC, at a range of concentrations (0-20 μM), concentration-dependently inhibited cell proliferation in the HL-60 AML cell line. Western blot and flow cytometric assays demonstrated that CAC induced several features of apoptosis such as sub G1-phase cell increase, phosphatidylserine (PS) externalization, and significantly activated proapoptotic signaling including caspase-8, -9, and -3 activation and poly(ADP-ribose) polymerase (PARP) cleavage in HL-60 AML cells. Moreover, treatment of HL-60 cells with CAC induced concentration- and time- dependent activation of p38 mitogen-activated protein kinase (p38 MAPK) and c-Jun N-terminal kinase (JNK). Only JNK-, but not p38 MAPK-specific inhibitor can reverse the CAC-induced activation of the caspase-8, -9, and -3. We concluded that CAC can induce apoptosis in human leukemic HL-60 cells via a caspases-dependent pathway, and that the apoptosis-inducing effect of CAC can be regulated by JNK activation signaling.