Dihydroartemisinin accelerates c-MYC oncoprotein degradation and induces apoptosis in c-MYC-overexpressing tumor cells

Unlocking the power of nanomedicine: the future of nutraceuticals in oncology treatment

Cancer, an intricate and multifaceted disease, is characterized by the uncontrolled proliferation of cells that can lead to serious health complications and ultimately death. Conventional therapeutic strategies mainly target rapidly dividing cancer cells, but often indiscriminately harm healthy cells in the process. As a result, there is a growing interest in exploring novel therapies that are both effective and less toxic to normal cells. Herbs have long been used as natural remedies for various diseases and conditions. Some herbal compounds exhibit potent anti-cancer properties, making them potential candidates for nutraceutical-based treatments. However, despite their promising efficacy, there are considerable limitations in utilizing herbal preparations due to their poor solubility, low bioavailability, rapid metabolism and excretion, as well as potential interference with other medications. Nanotechnology offers a unique platform to overcome these challenges by encapsulating herbal compounds within nanoparticles. This approach not only increases solubility and stability but also enhances the cellular uptake of nutraceuticals, allowing for controlled and targeted delivery of therapeutic agents directly at tumor sites. By harnessing the power of nanotechnology-enabled therapy, this new frontier in cancer treatment presents an opportunity to minimize toxicity while maximizing efficacy. In conclusion, this manuscript provides compelling evidence for integrating nanotechnology with nutraceuticals derived from herbal sources to optimize cancer therapy outcomes. We explore the roadblocks associated with traditional herbal treatments and demonstrate how nanotechnology can help circumvent these issues, paving the way for safer and more effective cancer interventions in future oncological practice.

Targeting Transcription Factors in Cancer: From "Undruggable" to "Druggable"

Deregulation of transcription factors is critical to hallmarks of cancer. Genetic mutations, gene fusions, amplifications or deletions, epigenetic alternations, and aberrant post-transcriptional modification of transcription factors are involved in the regulation of various stages of carcinogenesis, including cancer initiation, progression, and metastasis. Thus, targeting the dysfunctional transcription factors may lead to new cancer therapeutic strategies. However, transcription factors are conventionally considered as "undruggable." Here, we summarize the recent progresses in understanding the regulation of transcription factors in cancers and strategies to target transcription factors and co-factors for preclinical and clinical drug development, particularly focusing on c-Myc, YAP/TAZ, and β-catenin due to their significance and interplays in cancer.

Centella asiatica Modulates Nrf-2 Antioxidant Mechanisms and Enhances Reactive Oxygen Species-Mediated Apoptotic Cell Death in Leukemic (THP-1) Cells

Centella asiatica is commonly used in traditional medicine owing to its many therapeutic properties including but not limited to antioxidant and antitumor potential. This study examined the antioxidant and antiproliferative effects of its crude (C) and fractionated (C3) ethanolic leaf extracts in THP-1 cells. In THP-1 cells, C and C3 cytotoxicity was evaluated (WST-1 viability assay; 24 h; [0.2-3 mg/mL]) and half maximal inhibitory concentration was obtained. Malondialdehyde (MDA; spectrophotometry), mitochondrial depolarization (Δψ_m), intracellular reactive oxygen species (IROS; flow cytometry), glutathione (GSH), oxidized GSH (GSSG) concentrations, adenosine triphosphate (ATP) levels, caspase activities (luminometry) and DNA fragmentation (single cell gel electrophoresis assay) were evaluated. Protein expression and gene expression was quantified by Western blotting and quantitative polymerase chain reaction, respectively. THP-1 cell viability was dose-dependently reduced by C and C3. MDA, IROS, GSH, and Δψ_m were increased and ATP was decreased by C and C3 (P < .01). Antioxidant gene expression, Nrf-2 protein expression, and GSSG levels (P < .01) were increased by C, but were decreased by C3. C and C3 elevated caspase activity and DNA damage (P < .0001), whereas they decreased glutathione peroxidase and Bcl-2 protein expressions (P < .003). c-PARP protein expression and c-myc gene expression was decreased by C, whereas they were increased by C3 (P < .002). C3 reduced OGG-1 gene expression (P < .0003). Antioxidant responses were increased by C, whereas they were decreased by C3. Both C and C3 exerted antiproliferative effects in THP-1 cells by enhancing apoptosis. Of note, C3 more effectively induced apoptosis.

Artemisinin and its derivatives: a promising cancer therapy

The world is experiencing a cancer epidemic and an increase in the prevalence of the disease. Cancer remains a major killer, accounting for more than half a million deaths annually. There is a wide range of natural products that have the potential to treat this disease. One of these products is artemisinin; a natural product from Artemisia plant. The Nobel Prize for Medicine was awarded in 2015 for the discovery of artemisinin in recognition of the drug's efficacy. Artemisinin produces highly reactive free radicals by the breakdown of two oxygen atoms that kill cancerous cells. These cells sequester iron and accumulate as much as 1000 times in comparison with normal cells. Generally, chemotherapy is toxic to both cancerous cells and normal cells, while no significant cytotoxicity from artemisinin to normal cells has been found in more than 4000 case studies, which makes it far different than conventional chemotherapy. The pleiotropic response of artemisinin in cancer cells is responsible for growth inhibition by multiple ways including inhibition of angiogenesis, apoptosis, cell cycle arrest, disruption of cell migration, and modulation of nuclear receptor responsiveness. It is very encouraging that artemisinin and its derivatives are anticipated to be a novel class of broad-spectrum antitumor agents based on efficacy and safety. This review aims to highlight these achievements and propose potential strategies to develop artemisinin and its derivatives as a new class of cancer therapeutic agents.

Induction of GNMT by 1,2,3,4,6-penta-O-galloyl-beta-D-glucopyranoside through proteasome-independent MYC downregulation in hepatocellular carcinoma

Glycine-N-methyl transferase (GNMT) a tumor suppressor for hepatocellular carcinoma (HCC) plays a crucial role in liver homeostasis. Its expression is downregulated in almost all the tumor tissues of HCC while the mechanism of this downregulation is not yet fully understood. Recently, we identified 1,2,3,4,6-penta-O-galloyl-beta-D-glucopyranoside (PGG) as a GNMT promoter enhancer compound in HCC. In this study, we aimed to delineate the mechanism by which PGG enhances GNMT expression and to investigate its effect on GNMT suppression in HCC. Microarray and pathway enrichment analysis revealed that MYC was a major target of PGG. PGG suppressed MYC mRNA and protein expression in Huh7 and Hep G2 cells in a dose- and time-dependent fashion. Furthermore, MYC expression was also reduced in xenograft tumors in PGG treated mice. Moreover, shRNA-mediated knocked-down or pharmacological inhibition of MYC resulted in a significant induction of GNMT promoter activity and endogenous GNMT mRNA expression in Huh7 cells. In contrast, overexpression of MYC significantly inhibited GNMT promoter activity and endogenous GNMT protein expression. In addition, antibodies against MYC effectively precipitated the human GNMT promoter in a chromatin immunoprecipitation assay. Lastly, GNMT expression was negatively correlated with MYC expression in human HCC samples. Interestingly, PGG not only inhibited MYC gene expression but also promoted MYC protein degradation through proteasome-independent pathways. This work reveals a novel anticancer mechanism of PGG via downregulation of MYC expression and establishes a therapeutic rationale for treatment of MYC overexpressing cancers using PGG. Our data also provide a novel mechanistic understanding of GNMT regulation through MYC in the pathogenesis of HCC.

Therapeutic Inhibition of Myc in Cancer. Structural Bases and Computer-Aided Drug Discovery Approaches

Myc (avian myelocytomatosis viral oncogene homolog) represents one of the most sought after drug targets in cancer. Myc transcription factor is an essential regulator of cell growth, but in most cancers it is overexpressed and associated with treatment-resistance and lethal outcomes. Over 40 years of research and drug development efforts did not yield a clinically useful Myc inhibitor. Drugging the "undruggable" is problematic, as Myc inactivation may negatively impact its physiological functions. Moreover, Myc is a disordered protein that lacks effective binding pockets on its surface. It is well established that the Myc function is dependent on dimerization with its obligate partner, Max (Myc associated factor X), which together form a functional DNA-binding domain to activate genomic targets. Herein, we provide an overview of the knowledge accumulated to date on Myc regulation and function, its critical role in cancer, and summarize various strategies that are employed to tackle Myc-driven malignant transformation. We focus on important structure-function relationships of Myc with its interactome, elaborating structural determinants of Myc-Max dimer formation and DNA recognition exploited for therapeutic inhibition. Chronological development of small-molecule Myc-Max prototype inhibitors and corresponding binding sites are comprehensively reviewed and particular emphasis is placed on modern computational drug design methods. On the outlook, technological advancements may soon provide the so long-awaited Myc-Max clinical candidate.

Dihydroartemisinin triggers c-Myc proteolysis and inhibits protein kinase B/glycogen synthase kinase 3β pathway in T-cell lymphoma cells

Recent studies have revealed a positive therapeutic effect of dihydroartemisinin (DHA) on tumor cells. However, the underlying mechanism of this has not yet been elucidated. The present study examined the potential therapeutic role and mechanism of DHA in T-cell lymphoma cells. It was revealed that DHA inhibited the proliferation of Jurkat and HuT-78 T-cell lymphoma cells in a concentration- and time-dependent manner. Furthermore, DHA reduced c-Myc protein expression at the transcriptional level, and induced the phosphorylation of c-Myc and the degradation of c-Myc oncoprotein levels. DHA treatment resulted in decreased phosphorylation of protein kinase B (Akt) and glycogen synthase 3β (GSK3β) in T-cell lymphoma cells. In addition, DHA treatment induced cell apoptosis, which was accompanied by an increased ratio of Bax/Bcl-2. Taken together, the results of the present study suggested that DHA may exert its antitumor role by accelerating c-Myc proteolysis and inhibiting the Akt/GSK3β pathway in T-cell lymphoma cells.

Centella asiatica Fraction-3 Suppresses the Nuclear Factor Erythroid 2-Related Factor 2 Anti-Oxidant Pathway and Enhances Reactive Oxygen Species-Mediated Cell Death in Cancerous Lung A549 Cells

Centella asiatica is a tropical medicinal plant that is commonly used in traditional medicine. Medicinal properties of C. asiatica include anti-oxidant, anti-inflammatory, and anti-cancer activity. We investigated the anti-oxidant and anti-proliferative/cytotoxic effects of a semi-purified fraction of C. asiatica ethanolic leaf extract (C3) in cancerous lung A549 cells. C3 was obtained by silica column fractionation and identified by using thin-layer chromatography and gas chromatography mass spectrometry. Cytotoxicity of C3 in A549 cells was evaluated (cell viability assay-WST-1; 24 h; [0.2-3 mg/mL]) to determine an inhibitory concentration (IC₅₀). Intracellular reactive oxygen species (IROS), mitochondrial membrane potential (flow cytometry), malondialdehyde (MDA), lactate dehydrogenase (LDH) (spectrophotometry), glutathione (GSH), oxidised glutathione (GSSG), adenosine triphosphate levels, caspase activity (luminometry), and DNA damage (comet assay) were evaluated. Protein expression (Nrf-2, p53, Bax, Bcl-2, and HSP-70) and gene expression (Nrf-2, GPx, SOD, CAT, c-myc, and OGG-1) were quantified by western blotting and quantitative polymerase chain reaction (qPCR), respectively. C3 dose dependently decreased A549 cell viability. The IC₅₀ of C3 increased MDA, IROS, mitochondrial depolarization, LDH, caspase (-8, -9, -3/7) activity, DNA damage, GSH levels, Nrf-2 protein expression, HSP-70 protein expression, and OGG-1 gene expression (P < .05). GSSG levels, anti-oxidant (Nrf-2, GPx, SOD) gene expression, p53, Bax, and Bcl-2 protein expression were decreased by C3 (P < .02). C3 diminished the anti-oxidant gene expression and induced anti-proliferative/cytotoxic effects in A549 cells.

Effect of dihydroarteminin combined with siRNA targeting Notch1 on Notch1/c-Myc signaling in T-cell lymphoma cells

The effectiveness of therapy combining dihydroartemisinin (DHA) and small interfering RNA targeting Notch1 (siNotch1) in T-cell lymphoma remains unknown. The present study explored the potential and possible mechanisms of combined dihydroarteminin, and siNotch1 therapy for T-cell lymphoma. It was demonstrated that the viability rates of siRNA-DHA-treated cells was significantly suppressed in comparison with those in control cells, control siRNA cells, siRNA-treated cells and DHA-treated cells (P<0.01). Additionally, there was a significant increase in cell apoptosis of siRNA-DHA-treated cells in comparison with those of control cells, control siRNA cells, siRNA-treated cells, DHA-treated cells (P<0.05). Furthermore, Notch1 and c-Myc mRNA and protein expression were decreased in siRNA-DHA-treated cells (P<0.05). The present study demonstrated that DHA combined with siNotch1 is able to suppress proliferation and promote apoptosis, and downregulate the expression of Notch1 and c-Myc mRNA and protein in T-cell lymphoma cells. Targeting Notch1/c-Myc signaling with siRNA and DHA may represent a novel strategy for treating human T-cell lymphoma.

More insights into the pharmacological effects of artemisinin

Artemisinin is one of the most widely prescribed drugs against malaria and has recently received increased attention because of its other potential biological effects. The aim of this review is to summarize recent discoveries of the pharmaceutical effects of artemisinin in basic science along with its mechanistic action, as well as the intriguing results of recent clinical studies, with a focus on its antitumor activity. Scientific evidence indicates that artemisinin exerts its biological activity by generating reactive oxygen species that damage the DNA, mitochondrial depolarization, and cell death. In the present article review, scientific evidence suggests that artemisinin is a potential therapeutic agent for various diseases. Thus, this review is expected to encourage interested scientists to conduct further preclinical and clinical studies to evaluate these biological activities.

Dihydroartemisinin Induces Apoptosis in Human Bladder Cancer Cell Lines Through Reactive Oxygen Species, Mitochondrial Membrane Potential, and Cytochrome C Pathway

Background:

Dihydroartemisinin (DHA) is a semisynthetic derivative of artemisinin and has antiproliferative effect. However, such effects of DHA have not yet been revealed for bladder cancer cells.

Methods:

We used as bladder cancer cell lines to examine the effect of DHA on the cell viability, cell apoptosis, and monitoring of mitochondrial membrane potential (ΔΨm) changes. Furthermore, the effect of DHA on the reactive oxygen species (ROS) production and cytochrome c release were also detected. We employed MTT assay to investigate the cell proliferation effect of DHA on the EJ-138 and HTB-9 human bladder cancer cells. Annexin/PI staining, caspase-3 activity assay, Bcl-2/Bax protein expression, mitochondrial membrane potential assay, cytochrome c release, and ROS analysis were used for apoptosis detection.

Results:

DHA significantly reduced cell viability in a dose-dependent manner. Cytotoxicity of DHA was suppressed by N-acetylcysteine. The growth inhibition effect of DHA was related to the induction of cell apoptosis, which were manifested by annexin V-FITC staining, activation of caspase-3. DHA also increased ROS generation, cytochrome c release, and loss of mitochondrial transmembrane potential (ΔΨm) in cells. In addition, the downregulation of regulatory protein Bcl-2 and upregulation of Bax protein by DHA were also observed.

Conclusions:

These findings demonstrated that DHA induces apoptosis through mitochondrial signaling pathway. These suggest that DHA may be a potential agent for induction of apoptosis in human bladder cancer cells.

Artemether suppresses cell proliferation and induces apoptosis in diffuse large B cell lymphoma cells

Artemether (ART), a derivative of the well-known anti-malaria drug artemisinin, demonstrates potent anti-cancer activity in various cancer cells, however its effects on lymphoma remain unknown. The present study demonstrated that ART significantly inhibited proliferation of diffuse large B cell lymphoma (DLBCL) in vivo and in vitro, and led to G0/G1 phase arrest. Mechanistic studies demonstrated that ART suppressed the expression of the cell cycle proteins cyclin dependent kinase (CDK) 2, 4, and Cyclin D1, and specifically repressed the proto-oncogene c-Myc, rather than regulating the extracellular signal-regulated kinase or protein kinase B signaling pathways (two key pathways involved in regulating cell proliferation). In addition, high-concentration ART treatment significantly induced the apoptosis of DLBCL cells by promoting the cleavage of Caspase-3 and Poly (ADP-ribose) polymerase (PARP) 1. Overall, the data indicated that ART exhibited anti-cancer activity by inhibiting the expression of cell cycle genes and c-Myc, and promoting Caspase-3 and PARP1 cleavage, which suggested that ART may serve as a dual pharmaceutical for the treatment DLBCL.

Macrocyclic peptides decrease c-Myc protein levels and reduce prostate cancer cell growth

The oncoprotein c-Myc is often overexpressed in cancer cells, and the stability of this protein has major significance in deciding the fate of a cell. Thus, targeting c-Myc levels is an attractive approach for developing therapeutic agents for cancer treatment. In this study, we report the anti-cancer activity of the macrocyclic peptides [D-Trp]CJ-15,208 (cyclo[Phe-D-Pro-Phe-D-Trp]) and the natural product CJ-15,208 (cyclo[Phe-D-Pro-Phe-Trp]). [D-Trp]CJ-15,208 reduced c-Myc protein levels in prostate cancer cells and decreased cell proliferation with IC50 values ranging from 2.0 to 16 µM in multiple PC cell lines. [D-Trp]CJ-15,208 induced early and late apoptosis in PC-3 cells following 48 hours treatment, and growth arrest in the G2 cell cycle phase following both 24 and 48 hours treatment. Down regulation of c-Myc in PC-3 cells resulted in loss of sensitivity to [D-Trp]CJ-15,208 treatment, while overexpression of c-Myc in HEK-293 cells imparted sensitivity of these cells to [D-Trp]CJ-15,208 treatment. This macrocyclic tetrapeptide also regulated PP2A by reducing the levels of its phosphorylated form which regulates the stability of cellular c-Myc protein. Thus [D-Trp]CJ-15,208 represents a new lead compound for the potential development of an effective treatment of prostate cancer.

Shikonin suppresses proliferation and induces apoptosis in human leukemia NB4 cells through modulation of MAPKs and c‑Myc

Acute promyelocytic leukemia (APL) is a special subtype of acute myeloid leukemia that responds to treatment with all-trans retinoic acid and arsenic trioxide. However, severe side effects and drug resistance limit the effectiveness of these treatments. Hence, new drugs for APL are required urgently. Shikonin, an active naphthoquinone derived from the Chinese medical herb Zi Cao exerts antitumor activity in several cancers. In the present study, the effects of shikonin on proliferation and apoptosis in NB4 cells, as well as related mechanisms were assessed. Treatment of NB4 cells with shikonin inhibited proliferation in a concentration- and time-dependent manner. The cell cycle was arrested in the G1 phase. NB4 cells treated with shikonin exhibited more apoptosis and higher levels of cleaved caspase-3 and poly ADP-ribose polymerase than control cells. Western blotting results demonstrated that the expression of p-p38 mitogen-activated protein kinase (p-p38MAPK) and p-c-Jun N-terminal kinase (p-JNK) was increased significantly by shikonin treatment, while the expression of p-ERK and c-Myc was decreased. In summary, these findings indicated that shikonin inhibited cell proliferation and induced apoptosis partly through modulation of the MAPKs and downregulation of c-Myc.

Design of Drug Delivery Systems Containing Artemisinin and Its Derivatives

Artemisinin and its derivatives have been reported to be experimentally effective for the treatment of highly aggressive cancers without developing drug resistance, they are useful for the treatment of malaria, other protozoal infections and they exhibit antiviral activity. However, they are limited pharmacologically by their poor bioavailability, short half-life in vivo, poor water solubility and long term usage results in toxicity. They are also expensive for the treatment of malaria when compared to other antimalarials. In order to enhance their therapeutic efficacy, they are incorporated onto different drug delivery systems, thus yielding improved biological outcomes. This review article is focused on the currently synthesized derivatives of artemisinin and different delivery systems used for the incorporation of artemisinin and its derivatives.

Artemisinin and Its Derivatives as a Repurposing Anticancer Agent: What Else Do We Need to Do?

Preclinical investigation and clinical experience have provided evidence on the potential anticancer effect of artemisinin and its derivatives (ARTs) in the recent two decades. The major mechanisms of action of ARTs may be due to toxic-free radicals generated by an endoperoxide moiety, cell cycle arrest, induction of apoptosis, and inhibition of tumor angiogenesis. It is very promising that ARTs are expected to be a new class of antitumor drugs of wide spectrum due to their detailed information regarding efficacy and safety. For developing repurposed drugs, many other characteristics of ARTs should be studied, including through further investigations on possible new pathways of anticancer effects, exploration on efficient and specific drug delivery systems-especially crossing biological barriers, and obtaining sufficient data in clinical trials. The aim of this review is to highlight these achievements and propose the potential strategies to develop ARTs as a new class of cancer therapeutic agents.

Structurally diverse c-Myc inhibitors share a common mechanism of action involving ATP depletion

The c-Myc (Myc) oncoprotein is deregulated in a large proportion of diverse human cancers. Considerable effort has therefore been directed at identifying pharmacologic inhibitors as potential anti-neoplastic agents. Three such groups of small molecule inhibitors have been described. The first is comprised of so-called “direct” inhibitors, which perturb Myc's ability to form productive DNA-binding heterodimers in association with its partner, Max. The second group is comprised of indirect inhibitors, which largely function by targeting the BET-domain protein BRD4 to prevent the proper formation of transcriptional complexes that assemble in response to Myc-Max DNA binding. Thirdly, synthetic lethal inhibitors cause the selective apoptosis of Myc over-expressing either by promoting mitotic catastrophe or altering Myc protein stability. We report here a common mechanism by which all Myc inhibitors, irrespective of class, lead to eventual cellular demise. This involves the depletion of ATP stores due to mitochondrial dysfunction and the eventual down-regulation of Myc protein. The accompanying metabolic de-regulation causes neutral lipid accumulation, cell cycle arrest, and an attempt to rectify the ATP deficit by up-regulating AMP-activated protein kinase (AMPK). These responses are ultimately futile due to the lack of functional Myc to support the requisite anabolic response. Finally, the effects of Myc depletion on ATP levels, cell cycle arrest, differentiation and AMPK activation can be mimicked by pharmacologic inhibition of the mitochondrial electron transport chain without affecting Myc levels. Thus, all Myc inhibitors promote a global energy collapse that appears to underlie many of their phenotypic consequences.

Phospho-TCTP as a therapeutic target of Dihydroartemisinin for aggressive breast cancer cells

Upregulation of Translationally Controlled Tumor Protein (TCTP) is associated with poorly differentiated aggressive tumors, including breast cancer, but the underlying mechanism(s) are still debated. Here, we show that in breast cancer cell lines TCTP is primarily localized in the nucleus, mostly in the phosphorylated form.

The effects of Dihydroartemisinin (DHA), an anti-malaria agent that binds TCTP, were tested on breast cancer cells. DHA decreases cell proliferation and induces apoptotic cell death by targeting the phosphorylated form of TCTP. Remarkably, DHA enhances the anti-tumor effects of Doxorubicin in triple negative breast cancer cells resulting in an increased level of apoptosis. DHA also synergizes with Trastuzumab, used to treat HER2/neu positive breast cancers, to induce apoptosis of tumor cells.

Finally, we present new clinical data that nuclear phospho-TCTP overexpression in primary breast cancer tissue is associated with high histological grade, increase expression of Ki-67 and with ER-negative breast cancer subtypes. Notably, phospho-TCTP expression levels increase in trastuzumab-resistant breast tumors, suggesting a possible role of phospho-TCTP as a new prognostic marker.

In conclusion, the anti-tumor effect of DHA in vitro with conventional chemotherapeutics suggests a novel therapeutic strategy and identifies phospho-TCTP as a new promising target for advanced breast cancer.

Dihydroartemisinin as a Putative STAT3 Inhibitor, Suppresses the Growth of Head and Neck Squamous Cell Carcinoma by Targeting Jak2/STAT3 Signaling

Developing drugs that can effectively block STAT3 activation may serve as one of the most promising strategy for cancer treatment. Currently, there is no putative STAT3 inhibitor that can be safely and effectively used in clinic. In the present study, we investigated the potential of dihydroartemisinin (DHA) as a putative STAT3 inhibitor and its antitumor activities in head and neck squamous cell carcinoma (HNSCC). The inhibitory effects of DHA on STAT3 activation along with its underlying mechanisms were studied in HNSCC cells. The antitumor effects of DHA against HNSCC cells were explored both in vitro and in vivo. An investigation on cooperative effects of DHA with cisplatin in killing HNSCC cells was also implemented. DHA exhibited remarkable and specific inhibitory effects on STAT3 activation via selectively blocking Jak2/STAT3 signaling. Besides, DHA significantly inhibited HNSCC growth both in vitro and in vivo possibly through induction of apoptosis and attenuation of cell migration. DHA also synergized with cisplatin in tumor inhibition in HNSCC cells. Our findings demonstrate that DHA is a putative STAT3 inhibitor that may represent a new and effective drug for cancer treatment and therapeutic sensitization in HNSCC patients.

Dihydroartemisinin prevents breast cancer-induced osteolysis via inhibiting both breast caner cells and osteoclasts

Bone is the most common site of distant relapse in breast cancer, leading to severe complications which dramatically affect the patients’ quality of life. It is believed that the crosstalk between metastatic breast cancer cells and osteoclasts is critical for breast cancer-induced osteolysis. In this study, the effects of dihydroartemisinin (DHA) on osteoclast formation, bone resorption, osteoblast differentiation and mineralization were initially assessed in vitro, followed by further investigation in a titanium-particle-induced osteolysis model in vivo. Based on the proved inhibitory effect of DHA on osteolysis, DHA was further applied to MDA-MB-231 breast cancer-induced mouse osteolysis model, with the underlying molecular mechanisms further investigated. Here, we verified for the first time that DHA suppressed osteoclast differentiation, F-actin ring formation and bone resorption through suppressing AKT/SRC pathways, leading to the preventive effect of DHA on titanium-particle-induced osteolysis without affecting osteoblast function. More importantly, we demonstrated that DHA inhibited breast tumor-induced osteolysis through inhibiting the proliferation, migration and invasion of MDA-MB-231 cells via modulating AKT signaling pathway. In conclusion, DHA effectively inhibited osteoclastogenesis and prevented breast cancer-induced osteolysis.

Dihydroartemisinin targets VEGFR2 via the NF-κB pathway in endothelial cells to inhibit angiogenesis

The anti-malarial agent dihydroartemisinin (DHA) has strong anti-angiogenic activity. This study aimed to investigate the molecular mechanism underlying this effect of DHA on angiogenesis. We found that DHA shows a dose-dependent inhibition of proliferation and migration of in HUVECs. DHA specifically down-regulates the mRNA and protein expression of VEGFR2 in endothelial cells. Treatment with DHA increases IκB-α protein and blocks nuclear translocation of NF-κB p65. In addition, DHA directly regulates VEGFR2 promoter activity through p65 binding motif, and decreases the binding activity of p65 and VEGFR2 promoter, suggesting defective NF-κB signaling may underlie the observed effects of DHA on VEGFR2 expression. In the presence of the NF-κB inhibitor PDTC, DHA could not further repress VEGFR2. Co-treatment with PDTC and DHA produced minimal changes compared to the effects of either drug alone in in vitro angiogenesis assays. Similar findings were found in vivo through a mouse retinal neovascularization model examining the effects of PDTC and DHA. Our data suggested that DHA inhibits angiogenesis largely through repression of the NF-κB pathway. DHA is well tolerated, and therefore may be an ideal candidate to use clinically as an angiogenesis inhibitor for cancer treatment.

Direct and indirect targeting of MYC to treat acute myeloid leukemia

Purpose

Acute myeloid leukemia (AML) is the most common acute leukemia in adults and is often resistant to conventional therapies. The MYC oncogene is commonly overexpressed in AML but has remained an elusive target. We aimed to examine the consequences of targeting MYC both directly and indirectly in AML overexpressing MYC/Myc due to trisomy 8/15 (human/mouse), FLT3-ITD mutation, or gene amplification.

Methods

We performed in vivo knockdown of Myc (shRNAs) and both in vitro and in vivo experiments using four drugs with indirect anti-MYC activity: VX-680, GDC-0941, artemisinin, and JQ1.

Results

shRNA knockdown of Myc in mice prolonged survival, regardless of the mechanism underlying MYC overexpression. VX-680, an aurora kinase inhibitor, demonstrated in vitro efficacy against human MYC-overexpressing AMLs regardless of the mechanism of MYC overexpression, but was weakest against a MYC-amplified cell line. GDC-0941, a PI3-kinase inhibitor, demonstrated efficacy against several MYC-overexpressing AMLs, although only in vitro. Artemisinin, an antimalarial, did not demonstrate consistent efficacy against any of the human AMLs tested. JQ1, a bromodomain and extra-terminal bromodomain inhibitor, demonstrated both in vitro and in vivo efficacy against several MYC-overexpressing AMLs. We also confirmed a decrease in MYC levels at growth inhibitory doses for JQ1, and importantly, sensitivity of AML cell lines to JQ1 appeared independent of the mechanism of MYC overexpression.

Conclusions

Our data support growing evidence that JQ1 and related compounds may have clinical efficacy in AML treatment regardless of the genetic abnormalities underlying MYC deregulation.

Electronic supplementary material

The online version of this article (doi:10.1007/s00280-015-2766-z) contains supplementary material, which is available to authorized users.

Anticancer Effect of AntiMalarial Artemisinin Compounds

The anti-malarial drug artemisinin has shown anticancer activity in vitro and animal experiments, but experience in human cancer is scarce. However, the ability of artemisinins to kill cancer cells through a variety of molecular mechanisms has been explored. A PubMed search of about 127 papers on anti-cancer effects of antimalarials has revealed that this class of drug, including other antimalarials, have several biological characteristics that include anticancer properties. Experimental evidences suggest that artemisinin compounds may be a therapeutic alternative in highly aggressive cancers with rapid dissemination, without developing drug resistance. They also exhibit synergism with other anticancer drugs with no increased toxicity toward normal cells. It has been found that semisynthetic artemisinin derivatives have much higher antitumor activity than their monomeric counterparts via mechanisms like apoptosis, arrest of cell cycle at G₀/G₁, and oxidative stress. The exact mechanism of activation and molecular basis of these anticancer effects are not fully elucidated. Artemisinins seem to regulate key factors such as nuclear factor-kappa B, survivin, NOXA, hypoxia-inducible factor-1α, and BMI-1, involving multiple pathways that may affect drug response, drug interactions, drug resistance, and associated parameters upon normal cells. Newer synthetic artemisinins have been developed showing substantial antineoplastic activity, but there is still limited information regarding the mode of action of these synthetic compounds. In view of the emerging data, specific interactions with established chemotherapy need to be further investigated in different cancer cells and their phenotypes and validated further using different semisynthetic and synthetic artemisinin derivatives.

Novel multiarm polyethylene glycol-dihydroartemisinin conjugates enhancing therapeutic efficacy in non-small-cell lung cancer

The clinical application of dihydroartemisinin (DHA) has been hampered due to its poor water-solubility. To overcome this hurdle, we devised a novel polymer-drug conjugate, multiarm polyethylene glycol-dihydroartemisinin (PEG-DHA), made by linking DHA with multiarm polyethylene glycol. Herein, we investigated PEG-DHA on chemical structure, hydrolysis, solubility, hemolysis, cell cytotoxicity in vitro, and efficacy in vivo. The PEG-DHA conjugates have showed moderate drug loadings (2.82 ~ 8.14 wt%), significantly good water-solubilities (82- ~ 163-fold of DHA), excellent in vitro anticancer activities (at concentrations ≥8 μg/ml, showed only 15–20% cell viability) with potency similar to that of native DHA, and long blood circulation half-time (5.75- ~ 16.75-fold of DHA). Subsequent tumor xenograft assays demonstrated a superior therapeutic effect of PEG-DHA on inhibition of tumor growth compared with native DHA. The novel PEG-DHA conjugates can not only improve the solubility and efficacy of DHA but also show the potential of scale-up production and clinical application.

DJ-1 mediates the resistance of cancer cells to dihydroartemisinin through reactive oxygen species removal

Dihydroartemisinin (DHA), one of the main metabolites of artemisinin and its derivatives, presents anti-cancer potential in vitro and in vivo. To explore the mechanisms of resistance toward DHA, a DHA-resistant cell line, HeLa/DHA, was established with a resistance factor of 7.26 in vitro. Upon DHA treatment, apoptotic cells were significantly elicited in parental HeLa cells but minimally induced in HeLa/DHA cells. HeLa/DHA cells also displayed much less sensitivity to DHA-induced tumor suppression in cancer xenograft models than HeLa cells. Intriguingly, DHA-resistant cells did not display a multidrug-resistant phenotype. Based on a proteomic study employing LC-ESI-MS/MS together with pathway analysis, DJ-1 (PARK7) was found to be highly expressed in HeLa/DHA cells. Western blot and immunofluorescence assays confirmed the higher expression of DJ-1 in HeLa/DHA cells than in parental cells in both cell line and xenograft models. DJ-1 is translocated to the mitochondria of HeLa/DHA cells and oxidized, providing DJ-1 with stronger cytoprotection activity. Further study revealed that DJ-1 knockdown in HeLa/DHA cells abolished the observed resistance, whereas overexpression of DJ-1 endowed the parental HeLa cells with resistance toward DHA. Reactive oxygen species (ROS) were also significantly induced by either DHA or hydrogen peroxide in HeLa cells but not in resistant HeLa/DHA cells. When the cells were pretreated with N-acetyl-l-cysteine, the effect of DJ-1 knockdown on sensitizing HeLa/DHA cells to DHA was significantly attenuated. In summary, our study suggests that overexpression and mitochondrial translocation of DJ-1 provides HeLa/DHA cells with resistance to DHA-induced ROS and apoptosis.

Effect of dihydroartemisinin combined with gemcitabine for treatment of pancreatic cancer in mice

AIM: To investigate the anticancer effect of dihydroartemisinin combined with gemcitabine against pancreatic cancer in mice and the possible mechanisms involved.

METHODS: A xenograft model of SW1990 pancreatic cancer was developed in nude mice. Model mice were randomized into four groups according to the drug(s) injected: C (normal saline), D (dihydroartemisinin), G (gemcitabine), and D + G (dihydroartemisinin + gemcitabine). All groups underwent intraperitoneal injection of the corresponding drug(s) once every 4 days for a total of 5 times. Tumor volume was measured during the drug therapy. The mice were sacrificed 4 d after the last drug injection. TUNEL assay was used to detect the apoptosis of tumor cells. Western blot was used to detect the protein expression of Bcl-2 and C-myc.

RESULTS: The average tumor volume in group D + G was significantly decreased compared with the other groups. TUNEL assay showed that group D + G presented with apparently more apoptosis than the other groups. Western blot analysis showed the expression of Bcl-2 and C-myc in group D + G was significantly down-regulated compared with the other groups.

CONCLUSION: Dihydroartemisinin combined with gemcitabine can significantly decrease pancreatic cancer xenograft growth in nude mice possibly via mechanisms related to the down-regulation of Bcl-2 and C-myc expression.

Small-molecule inhibitors of the Myc oncoprotein

The c-Myc (Myc) oncoprotein is among the most attractive of cancer targets given that it is de-regulated in the majority of tumors and that its inhibition profoundly affects their growth and/or survival. However, its role as a seldom-mutated transcription factor, its lack of enzymatic activity for which suitable pharmaceutical inhibitors could be crafted and its expression by normal cells have largely been responsible for its being viewed as "undruggable". Work over the past several years, however, has begun to reverse this idea by allowing us to view Myc within the larger context of global gene regulatory control. Thus, Myc and its obligate heterodimeric partner, Max, are integral to the coordinated recruitment and post-translational modification of components of the core transcriptional machinery. Moreover, Myc over-expression re-programs numerous critical cellular functions and alters the cell's susceptibility to their inhibition. This new knowledge has therefore served as a framework upon which to develop new pharmaceutical approaches. These include the continuing development of small molecules which act directly to inhibit the critical Myc-Max interaction, those which act indirectly to prevent Myc-directed post-translational modifications necessary to initiate productive transcription and those which inhibit vital pathways upon which the Myc-transformed cell is particularly reliant. This article is part of a Special Issue entitled: Myc proteins in cell biology and pathology.

Synergistic anti-cancer activity of the combination of dihydroartemisinin and doxorubicin in breast cancer cells

BACKGROUND

Dihydroartemisinin (DHA) exhibits potent anti-malarial and anti-cancer activities. This study aimed to investigate the anti-proliferative effects of a combination of DHA and doxorubicin (DOX) on human breast cancer cells.

METHODS

MTT assay and the combination index (CI) were used to show the anti-proliferative effects and calculate the synergism potential, respectively. Flow cytometry assay was used to detect apoptosis and the intracellular accumulation of DOX. JC-1 staining was used to determine the mitochondrial membrane potential. Western blot analysis was used to detect the protein expression of some apoptosis-related molecules.

RESULTS

Asynergistic anti-proliferative effect was found, and the enhanced anti-cancer activity was observed to be accompanied by the prompt onset of apoptosis in MCF-7 cells. The combinative treatment remarkably decreased the mitochondrial membrane potential and activated caspase cascades more than the mono-treatment. Pretreatment with DHA also did not influence the accumulation of DOX in MCF-7 cells.

CONCLUSION

This study presented a new opportunity to enhance the effectiveness of future treatment regimens of breast cancer using DOX.

Enhanced apoptotic effects of dihydroartemisinin-aggregated gelatin and hyaluronan nanoparticles on human lung cancer cells

Recent studies suggest that dihydroartemisinin (DHA), a derivative of artemisinin isolated from the traditional Chinese herb Artemisia annua L., has anticancer properties. Due to poor water solubility, poor oral activity, and a short plasma half-life, large doses of DHA have to be injected to achieve the necessary bioavailability. This study examined increasing DHA bioavailability by encapsulating DHA within gelatin (GEL) or hyaluronan (HA) nanoparticles via an electrostatic field system. Observations from transmission electron microscopy show that DHA in GEL and HA nanoparticles formed GEL/DHA and HA/DHA aggregates that were approximately 30-40 nm in diameter. The entrapment efficiencies for DHA were approximately 13 and 35% for the GEL/DHA and HA/DHA aggregates, respectively. The proliferation of A549 cells was inhibited by the GEL/DHA and HA/DHA aggregates. Fluorescent annexin V-fluorescein isothiocyanate (FITC) and propidium iodide (PI) staining displayed low background staining with annexin V-FITC or PI on DHA-untreated cells. In contrast, annexin V-FITC and PI stains dramatically increased when the cells were incubated with GEL/DHA and HA/DHA aggregates. These results suggest that DHA-aggregated GEL and HA nanoparticles exhibit higher anticancer proliferation activities than DHA alone in A549 cells most likely due to the greater aqueous dispersion after hydrophilic GEL or HA nanoparticles aggregation. These results demonstrate that DHA can aggregate with nanoparticles in an electrostatic field environment to form DHA nanosized aggregates.

A screening-based approach to circumvent tumor microenvironment-driven intrinsic resistance to BCR-ABL+ inhibitors in Ph+ acute lymphoblastic leukemia

Signaling by the BCR-ABL fusion kinase drives Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL) and chronic myelogenous leukemia (CML). Despite their clinical activity in many patients with CML, the BCR-ABL kinase inhibitors (BCR-ABL-KIs) imatinib, dasatinib, and nilotinib provide only transient leukemia reduction in patients with Ph+ ALL. While host-derived growth factors in the leukemia microenvironment have been invoked to explain this drug resistance, their relative contribution remains uncertain. Using genetically defined murine Ph+ ALL cells, we identified interleukin 7 (IL-7) as the dominant host factor that attenuates response to BCR-ABL-KIs. To identify potential combination drugs that could overcome this IL-7-dependent BCR-ABL-KI-resistant phenotype, we screened a small-molecule library including Food and Drug Administration-approved drugs. Among the validated hits, the well-tolerated antimalarial drug dihydroartemisinin (DHA) displayed potent activity in vitro and modest in vivo monotherapy activity against engineered murine BCR-ABL-KI-resistant Ph+ ALL. Strikingly, cotreatment with DHA and dasatinib in vivo strongly reduced primary leukemia burden and improved long-term survival in a murine model that faithfully captures the BCR-ABL-KI-resistant phenotype of human Ph+ ALL. This cotreatment protocol durably cured 90% of treated animals, suggesting that this cell-based screening approach efficiently identified drugs that could be rapidly moved to human clinical testing.

Lymphoma and myeloma cells are highly sensitive to growth arrest and apoptosis induced by artesunate

OBJECTIVES

The use of new drugs has improved the treatment of multiple myeloma and diffuse large B-cell lymphoma (DLBCL). Nevertheless, over time many patients relapse and develop resistance to treatment, and efforts are needed to overcome drug resistance. The widely used malaria drug artesunate has been reported to have antitumor activity, and we aimed to test the effects of artesunate on a panel of myeloma and lymphoma cells.

METHODS

Myeloma and DLBCL cell lines were treated with artesunate in vitro. The effects of artesunate treatment were evaluated using ATP content measurements for proliferation and annexin V/propidium iodide labeling for apoptosis. Western blotting was used to look for artesunate-induced protein changes. In addition, we measured artesunate effects on patient myeloma cells in the presence of bone marrow stromal cells.

RESULTS

Artesunate treatment efficiently inhibited cell growth and induced apoptosis in cell lines. Apoptosis was induced concomitantly with downregulation of MYC and anti-apoptotic Bcl-2 family proteins, as well as with cleavage of caspase-3. The IC50 values of artesunate in cell lines varied between 0.3 and 16.6 μm. Furthermore, some primary myeloma cells were also sensitive to artesunate at doses around 10 μm. Concentrations of this order are pharmacologically relevant as they can be obtained in plasma after intravenous administration of artesunate for malaria treatment.

CONCLUSION

Our findings indicate that artesunate is a potential drug for treatment of multiple myeloma and DLBCL at doses of the same order as currently in use for treatment of malaria without serious adverse effects.

Dihydroartemisinin inhibits the mammalian target of rapamycin-mediated signaling pathways in tumor cells

Dihydroartemisinin (DHA), an antimalarial drug, has previously unrecognized anticancer activity, and is in clinical trials as a new anticancer agent for skin, lung, colon and breast cancer treatment. However, the anticancer mechanism is not well understood. Here, we show that DHA inhibited proliferation and induced apoptosis in rhabdomyosarcoma (Rh30 and RD) cells, and concurrently inhibited the signaling pathways mediated by the mammalian target of rapamycin (mTOR), a central controller for cell proliferation and survival, at concentrations (<3 μM) that are pharmacologically achievable. Of interest, in contrast to the effects of conventional mTOR inhibitors (rapalogs), DHA potently inhibited mTORC1-mediated phosphorylation of p70 S6 kinase 1 and eukaryotic initiation factor 4E binding protein 1 but did not obviously affect mTORC2-mediated phosphorylation of Akt. The results suggest that DHA may represent a novel class of mTORC1 inhibitor and may execute its anticancer activity primarily by blocking mTORC1-mediated signaling pathways in the tumor cells.

Inhibitory effect of herbal remedy PERVIVO and anti-inflammatory drug sulindac on L-1 sarcoma tumor growth and tumor angiogenesis in Balb/c mice

Anticancer activity of many herbs was observed for hundreds of years. They act as modifiers of biologic response, and their effectiveness may be increased by combining multiple herbal extracts . PERVIVO, traditional digestive herbal remedy, contains some of them, and we previously described its antiangiogenic activity. Numerous studies documented anticancer effects of nonsteroidal anti-inflammatory drugs. We were the first to show that sulindac and its metabolites inhibit angiogenesis. In the present paper the combined in vivo effect of multicomponent herbal remedy PERVIVO and nonsteroidal anti-inflammatory drug sulindac on tumor growth, tumor angiogenesis, and tumor volume in Balb/c mice was studied. These effects were checked after grafting cells collected from syngeneic sarcoma L-1 tumors into mice skin. The strongest inhibitory effect was observed in experimental groups treated with PERVIVO and sulindac together. The results of our investigation showed that combined effect of examined drugs may be the best way to get the strongest antiangiogenic and antitumor effect.

Preparation and optimization of transferrin-modified-artemether lipid nanospheres based on the orthogonal design of emulsion formulation and physically electrostatic adsorption

Artemether has been used for a long time in the treatment of malaria as safe and non expensive drug. It possesses potent anticancer effects in cancer cell lines. Our aim was to develop transferrin-modified-artemether lipid nanospheres as targeted anticancer drug delivery system. In this study, artemether intravenous delivery system was prepared by emulsifying method as lipid nanospheres containing mixture of soya oil and crodamol as the core and soya lecithin and Tween 80 as coating layer. According to the physicochemical characterization, the process and formulation variables were optimized by orthogonal design and ANOVA analysis. Based on the electrostatic interaction, transferrin (TR) was physically adsorbed onto the coating layer; the effect of medium pH and the charge of the nanocarriers on the adsorption were investigated. The in vitro characterizations were carried out including, the zeta potential, AFM, TEM, FTIR, (1)H NMR and gel filtration. ART-LNSs with high entrapment efficiency, small size of about 50 nm and monodispersity were formulated. Optimized and stable TR-LNSs, a lipoprotein like structure and size, were produced. We showed a method by which TR can be bound to lipid nanospheres without the need for chemical modification as a base for the development of safe, effective and non expensive anticancer drug delivery system.

Ionizing radiation potentiates dihydroartemisinin-induced apoptosis of A549 cells via a caspase-8-dependent pathway

This report is designed to explore the molecular mechanism by which dihydroartemisinin (DHA) and ionizing radiation (IR) induce apoptosis in human lung adenocarcinoma A549 cells. DHA treatment induced a concentration- and time-dependent reactive oxygen species (ROS)-mediated cell death with typical apoptotic characteristics such as breakdown of mitochondrial membrane potential (Δψm), caspases activation, DNA fragmentation and phosphatidylserine (PS) externalization. Inhibition of caspase-8 or -9 significantly blocked DHA-induced decrease of cell viability and activation of caspase-3, suggesting the dominant roles of caspase-8 and -9 in DHA-induced apoptosis. Silencing of proapoptotic protein Bax but not Bak significantly inhibited DHA-induced apoptosis in which Bax but not Bak was activated. In contrast to DHA treatment, low-dose (2 or 4 Gy) IR induced a long-playing generation of ROS. Interestingly, IR treatment for 24 h induced G2/M cell cycle arrest that disappeared at 36 h after treatment. More importantly, IR synergistically potentiated DHA-induced generation of ROS, activation of caspase-8 and -3, irreparable G2/M arrest and apoptosis, but did not enhance DHA-induced loss of Δψm and activation of caspase-9. Taken together, our results strongly demonstrate the remarkable synergistic efficacy of combination treatment with DHA and low-dose IR for A549 cells in which IR potentiates DHA-induced apoptosis largely by enhancing the caspase-8-mediated extrinsic pathway.

Alkaloids isolated from natural herbs as the anticancer agents

Alkaloids are important chemical compounds that serve as a rich reservoir for drug discovery. Several alkaloids isolated from natural herbs exhibit antiproliferation and antimetastasis effects on various types of cancers both in vitro and in vivo. Alkaloids, such as camptothecin and vinblastine, have already been successfully developed into anticancer drugs. This paper focuses on the naturally derived alkaloids with prospective anticancer properties, such as berberine, evodiamine, matrine, piperine, sanguinarine, and tetrandrine, and summarizes the mechanisms of action of these compounds. Based on the information in the literature that is summarized in this paper, the use of alkaloids as anticancer agents is very promising, but more research and clinical trials are necessary before final recommendations on specific alkaloids can be made.

Qinghaosu (artemisinin): chemistry and pharmacology

Qinghaosu and its derivatives are widely used in the world as a new generation of antimalarial drug. Up to now, some important progresses of Qinghaosu research have been made, including synthesis of new qinghaosu derivatives and analogs, investigation on their bioactivities and mode of actions. The present review briefly describes these efforts made by researchers in China, particularly in this Institute.

Addiction to c-MYC in multiple myeloma

In multiple myeloma, c-MYC is activated and contributes to the malignant phenotype. Targeting MYC by short hairpin RNA induced cell death in myeloma cell lines; however, cell lines are generated from samples taken in advanced stages of the disease and may not reflect patient cells adequately. In this study, we used the selective small molecule inhibitor of MYC-MAX heterodimerization, 10058-F4, on myeloma cell lines as well as primary myeloma cells, and we show that inhibition of c-MYC activity efficiently induces myeloma cell death. Moreover, in cocultures of cell lines with bone marrow stromal cells from myeloma patients, the inhibitor still induces apoptosis. Our results provide further evidence that myeloma cells are addicted to c-MYC activity and that c-MYC is a promising therapeutic target in multiple myeloma.

Histone deacetylase inhibitors facilitate dihydroartemisinin-induced apoptosis in liver cancer in vitro and in vivo

Liver cancer ranks in prevalence and mortality among top five cancers worldwide. Accumulating interests have been focused in developing new strategies for liver cancer treatment. We have previously showed that dihydroartemisinin (DHA) exhibited antitumor activity towards liver cancer. In this study, we demonstrated that histone deacetylase inhibitors (HDACi) significantly augmented the antineoplastic effect of DHA via increasing apoptosis in vitro and in vivo. Inhibition of ERK phosphorylation contributed to DHA-induced apoptosis, due to the fact that inhibitor of ERK phosphorylation (PD98059) increased DHA-induced apoptosis. Compared with DHA alone, the combined treatment with DHA and HDACi reduced mitochondria membrane potential, released cytochrome c into cytoplasm, increased p53 and Bak, decreased Mcl-1 and p-ERK, activated caspase 3 and PARP, and induced apoptotic cells. Furthermore, we showed that HDACi pretreatment facilitated DHA-induced apoptosis. In Hep G2-xenograft carrying nude mice, the intraperitoneal injection of DHA and SAHA resulted in significant inhibition of xenograft tumors. Results of TUNEL and H&E staining showed more apoptosis induced by combined treatment. Immunohistochemistry data revealed the activation of PARP, and the decrease of Ki-67, p-ERK and Mcl-1. Taken together, our data suggest that the combination of HDACi and DHA offers an antitumor effect on liver cancer, and this combination treatment should be considered as a promising strategy for chemotherapy.

Dihydroartemisinin-induced inhibition of proliferation in BEL-7402 cells: an analysis of the mitochondrial proteome

Artemisinin, the active ingredient of the Chinese medicinal herb Artemisia annua L., and its derivatives (ARTs) are currently widely used as anti-malarial drugs around the world. In this study, we found that dihydroartemisinin (DHA), one of the main active metabolites of ARTs, inhibited the proliferation of human hepatocarcinoma BEL-7402 cells in a concentration-dependent manner. To interpret the mechanisms involved, an analysis of the mitochondrial proteome was performed employing two-dimensional gel electrophoresis and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Seven mitochondrial proteins including fumarate hydratase, 60 kDa heat shock protein, enoyl-CoA hydratase, 3-hydroxyacyl-CoA dehydrogenase, two subunits of ATP synthase and NADPH:adrenodoxin oxidoreductase were identified to be differentially expressed between the control and DHA-treated groups. Our results indicate that the imbalance of energy metabolism induced by DHA may contribute, at least in part, to its anti-cancer potential in BEL-7402 cells.

Induction of apoptosis by 3-amino-6-(3-aminopropyl)-5,6-dihydro-5,11-dioxo-11H-indeno[1,2-c]isoquinoline via modulation of MAPKs (p38 and c-Jun N-terminal kinase) and c-Myc in HL-60 human leukemia cells

Recently, we reported that 3-amino-6-(3-aminopropyl)-5,6-dihydro-5,11-dioxo-11H-indeno[1,2-c]isoquinoline (AM6-36), sharing structural similarity with naturally occurring isoquinolines, induced activities mediated by retinoid X receptor (RXR) response element accompanied by antiproliferative effects on breast cancer cells. To further characterize the biologic potential of AM6-36, we currently report studies conducted with HL-60 human leukemia cells. AM6-36 significantly inhibited cellular proliferation in a dose- and time-dependent manner with an IC(50) value of 86 nM. When evaluated at low test concentrations (≤0.25 μM), AM6-36 induced arrest in the G2/M phase of the cell cycle. At higher concentrations (1 and 2 μM), the response shifted to apoptosis, which was consistent with the effect of AM6-36 on other apoptotic signatures including an increase of apoptotic annexin V(+) 7-AAD(-) cells, loss of mitochondrial membrane potential, induction of poly(ADP-ribose) polymerase cleavage, and activation of several caspases. These apoptotic effects are potentially due to up-regulation of p38 MAPK and JNK phosphorylation and down-regulation of c-Myc oncogene expression. Taken together, AM6-36 might serve as an effective anticancer agent by inducing G2/M cell cycle arrest and apoptosis through the activation of MAPKs and inhibition of c-Myc.