A novel combination therapy with arsenic trioxide and parthenolide against pancreatic cancer cells

Targeted mitochondrial therapy for pancreatic cancer

Pancreatic cancer (PC) is a highly invasive tumor characterized by delayed diagnosis, rapid progress, and resistance to chemotherapy. Mitochondria, as the "power chamber" of cells, not only play a central role in energy metabolism but also participate in the production of reactive oxygen species (ROS), calcium signaling, regulation, and differentiation of the cell cycle. The abnormal activity of mitochondria is closely related to the development of PC. In this paper, we discussed the key role of mitochondria in PC, including mitochondrial DNA, mitochondrial biogenesis, mitochondrial dynamics, metabolic regulation, ROS generation, and mitochondrial-dependent apoptosis. We elaborated on the importance of these mitochondrial mechanisms in the development of PC and emphasized the potential of targeted mitochondrial therapy strategies for these mechanisms in the treatment of PC. In addition, this article also reviews the latest developments in innovative drug carriers such as cell-penetrating peptides, nucleic acid aptamers, and nanomaterials, which can achieve precise localization of mitochondria and drug delivery. Therefore, this article comprehensively analyzed the important role of mitochondria in the treatment of PC and clarified the effectiveness and necessity of targeting mitochondria in the treatment of PC.

Arsenic trioxide: applications, mechanisms of action, toxicity and rescue strategies to date

Arsenical medicine has obtained its status in traditional Chinese medicine for more than 2,000 years. In the 1970s, arsenic trioxide was identified to have high efficacy and potency for the treatment of acute promyelocytic leukemia, which promoted many studies on the therapeutic effects of arsenic trioxide. Currently, arsenic trioxide is widely used to treat acute promyelocytic leukemia and various solid tumors through various mechanisms of action in clinical practice; however, it is accompanied by a series of adverse reactions, especially cardiac toxicity. This review presents a comprehensive overview of arsenic trioxide from preclinical and clinical efficacy, potential mechanisms of action, toxicities, and rescue strategies for toxicities to provide guidance or assistance for the clinical application of arsenic trioxide.

Albumin conjugation promotes arsenic trioxide transport through alkaline phosphatase-associated transcytosis in MUC4 wildtype pancreatic cancer cells

Pancreatic cancer (PC) has a poor prognosis due to chemotherapy resistance and unfavorable drug transportation. Albumin conjugates are commonly used as drug carriers to overcome these obstacles. However, membrane-bound glycoprotein mucin 4 (MUC4) has emerged as a promising biomarker among the genetic mutations affecting albumin conjugates therapeutic window. Human serum albumin-conjugated arsenic trioxide (HSA-ATO) has shown potential in treating solid tumors but is limited in PC therapy due to unclear targets and mechanisms. This study investigated the transport mechanisms and therapeutic efficacy of HSA-ATO in PC cells with different MUC4 mutation statuses. Results revealed improved penetration of ATO into PC tumors through conjugated with HSA. However, MUC4 mutation significantly affected treatment sensitivity and HSA-ATO uptake both in vitro and in vivo. Mutant MUC4 cells exhibited over ten times higher IC50 for HSA-ATO and approximately half the uptake compared to wildtype cells. Further research demonstrated that ALPL activation by HSA-ATO enhanced transcytosis in wildtype MUC4 PC cells but not in mutant MUC4 cells, leading to impaired uptake and weaker antitumor effects. Reprogramming the transport process holds potential for enhancing albumin conjugate efficacy in PC patients with different MUC4 mutation statuses, paving the way for stratified treatment using these delivery vehicles.

Parthenolide repressed endometriosis induced surgically in rats: Role of PTEN/PI3Kinase/AKT/GSK-3β/β-catenin signaling in inhibition of epithelial mesenchymal transition

AIM

PI3K/AKT/GSK-3β/β-catenin signaling pathway is a triggering factor for epithelial to mesenchymal transition (EMT) which plays a pivotal role in the pathogenesis of endometriosis. Parthenolide is a sesquiterpene lactone extract that has anti-inflammatory, analgesic and anticancer properties. Hence, we investigated the effect of parthenolide against EMT in the endometrial tissue implants and immortalized epithelial endometriotic cell lines 12Z.

MAIN METHODS

Twenty- four female Rats with surgically induced endometriosis were treated with parthenolide (2, 4 mg/kg), for 4 weeks. Endometriotic cell line 12Z was used to identify the effect of parthenolide on the wound healing, cellular migration and invasion properties of endometriotic cells.

KEY FINDINGS

Parthenolide decreased the endometriotic implant tissue expression of total PI3K, PI3K-p85, p-AKT, p/total AKT, p-GSK-3β, P/total GSK-3β, and nβ-catenin, as well as increased E-cadherin and decreased vimentin mRNA expression. Parthenolide upregulated PTEN immunoreactivity as well as the endometriotic tissue caspase-3, caspase-9, BAX levels while reducing Bcl2 level. Additionally, parthenolide decreased endometriotic tissue implants surface area and histopathological score of the epithelial growth.

SIGNIFICANCE

Our findings showed that parthenolide in a dose dependent manner inhibited PI3K/AKT/GSK-3β/nβ-catenin cascade via enhancement of PTEN with subsequent inhibition of EMT evidenced by elevation of the epithelial marker, E-cadherin and reduction of mesenchymal marker, vimentin, of the endometriotic implants in addition to reversal of invasion and migration properties of epithelial endometriotic cell lines. These findings provide a valuable therapeutic approach for treatment of endometriosis.

Parthenolide and arsenic trioxide co-trigger autophagy-accompanied apoptosis in hepatocellular carcinoma cells

Although arsenic trioxide (ATO) shows a strong anti-tumor effect in the treatment of acute promyelocytic leukemia, it does not benefit patients with hepatocellular carcinoma (HCC). Thus, combination therapy is proposed to enhance the efficacy of ATO. Parthenolide (PTL), a natural compound, selectively eradicates cancer cells and cancer stem cells with no toxicity to normal cells. In this study, we chose PTL and ATO in combination and found that nontoxic dosage of PTL and ATO co-treatment can synergistically inhibit the in vitro and in vivo proliferation activity of HCC cells through suppressing stemness and self-renewal ability and inducing mitochondria-dependent apoptosis. More importantly, USP7-HUWE1-p53 pathway is involved in PTL enhancing ATO-induced apoptosis of HCC cell lines. Meanwhile, accompanied by induction of apoptosis, PTL and ATO evoke autophagic activity via inhibiting PI3K/Akt/mTOR pathway, and consciously controlling autophagy can improve the anti-HCC efficacy of a combination of PTL and ATO. In short, our conclusion represents a novel promising approach to the treatment of HCC.

Arsenic: A Global Environmental Challenge

Arsenic is a naturally occurring metalloid and one of the few metals that can be metabolized inside the human body. The pervasive presence of arsenic in nature and anthropogenic sources from agricultural and medical use have perpetuated human exposure to this toxic and carcinogenic element. Highly exposed individuals are susceptible to various illnesses, including skin disorders; cognitive impairment; and cancers of the lung, liver, and kidneys. In fact, across the globe, approximately 200 million people are exposed to potentially toxic levels of arsenic, which has prompted substantial research and mitigation efforts to combat this extensive public health issue. This review provides an up-to-date look at arsenic-related challenges facing the global community, including current sources of arsenic, global disease burden, arsenic resistance, and shortcomings of ongoing mitigation measures, and discusses potential next steps.

Targeting Redox Metabolism in Pancreatic Cancer

Cell metabolism is reprogrammed in cancer cells to meet their high bioenergetics and biosynthetic demands. This metabolic reprogramming is accompanied by alterations in redox metabolism, characterized by accumulation of reactive oxygen species (ROS). Elevated production of ROS, mostly by mitochondrial respiration, is counteracted by higher production of antioxidant defenses (mainly glutathione and antioxidant enzymes). Cancer cells are adapted to a high concentration of ROS, which contributes to tumorigenesis, metastasis formation, resistance to therapy and relapse. Frequent genetic alterations observed in pancreatic ductal adenocarcinoma (PDAC) affect KRAS and p53 proteins, which have a role in ROS production and control, respectively. These observations led to the proposal of the use of antioxidants to prevent PDAC development and relapse. In this review, we focus on the therapeutic strategies to further increase ROS level to induce PDAC cell death. Combining the promotion of ROS production and inhibition of antioxidant capacity is a promising avenue for pancreatic cancer therapy in the clinic.

Arsenic trioxide-induced upregulation of miR-1294 suppresses tumor growth in hepatocellular carcinoma by targeting TEAD1 and PIM1

Recently, Arsenic trioxide (ATO) has been reported as an efficient drug for suppression of cancer cell growth. Existing studies revealed the extensive involvement of microRNAs (miRNAs) in initiation and development of hepatocellular carcinoma (HCC). However, the potential correlation between ATO and miRNAs in HCC progression remains to be explored. To conduct our research, we applied a qRT-PCR analysis to find miRNAs that were upregulated in HCC cells treated with ATO. In our present study, miR-1294 was found to be significantly upregulated in ATO-treated HCC cells. To confirm the function of ATO and miR-1294 in HCC progression, gain-of function assays were designed and conducted. As expected, proliferative ability of ATO-treated HCC cells was markedly weakened compared to DMSO-treated HCC cells. More importantly, proliferation was further suppressed in ATO-induced HCC cells after overexpression of miR-1294. Through bioinformatics analysis, some potential targets of miR-1294 were predicted. Further investigation revealed that Pim-1 proto-oncogene (PIM1) and TEA domain transcription factor 1 (TEAD1) were two downstream targets of miR-1294 and could be negatively regulated by ATO. Functionally, we determined that cell proliferation and apoptosis resistance suppressed by miR-1294 and ATO were recovered by introduction of TEAD1 and PIM1. Collectively, this study revealed that a novel ATO-miR-1294-TEAD1/PIM1 axis regulated HCC cell growth, offering a potential insight into the HCC therapy.

Parthenolide as Cooperating Agent for Anti-Cancer Treatment of Various Malignancies

Primary and acquired resistance of cancer to therapy is often associated with activation of nuclear factor kappa B (NF-κB). Parthenolide (PN) has been shown to inhibit NF-κB signaling and other pro-survival signaling pathways, induce apoptosis and reduce a subpopulation of cancer stem-like cells in several cancers. Multimodal therapies that include PN or its derivatives seem to be promising approaches enhancing sensitivity of cancer cells to therapy and diminishing development of resistance. A number of studies have demonstrated that several drugs with various targets and mechanisms of action can cooperate with PN to eliminate cancer cells or inhibit their proliferation. This review summarizes the current state of knowledge on PN activity and its potential utility as complementary therapy against different cancers.

Cancer Etiology: A Metabolic Disease Originating from Life's Major Evolutionary Transition?

A clear understanding of the origins of cancer is the basis of successful strategies for effective cancer prevention and management. The origin of cancer at the molecular and cellular levels is not well understood. Is the primary cause of the origin of cancer the genomic instability or impaired energy metabolism? An attempt was made to present cancer etiology originating from life's major evolutionary transition. The first evolutionary transition went from simple to complex cells when eukaryotic cells with glycolytic energy production merged with the oxidative mitochondrion (The Endosymbiosis Theory first proposed by Lynn Margulis in the 1960s). The second transition went from single-celled to multicellular organisms once the cells obtained mitochondria, which enabled them to obtain a higher amount of energy. Evidence will be presented that these two transitions, as well as the decline of NAD+ and ATP levels, are the root of cancer diseases. Restoring redox homeostasis and reactivation of mitochondrial oxidative metabolism are important factors in cancer prevention.

Reactive oxygen species generating systems meeting challenges of photodynamic cancer therapy

The reactive oxygen species (ROS)-mediated mechanism is the major cause underlying the efficacy of photodynamic therapy (PDT). The PDT procedure is based on the cascade of synergistic effects between light, a photosensitizer (PS) and oxygen, which greatly favors the spatiotemporal control of the treatment. This procedure has also evoked several unresolved challenges at different levels including (i) the limited penetration depth of light, which restricts traditional PDT to superficial tumours; (ii) oxygen reliance does not allow PDT treatment of hypoxic tumours; (iii) light can complicate the phototherapeutic outcomes because of the concurrent heat generation; (iv) specific delivery of PSs to sub-cellular organelles for exerting effective toxicity remains an issue; and (v) side effects from undesirable white-light activation and self-catalysation of traditional PSs. Recent advances in nanotechnology and nanomedicine have provided new opportunities to develop ROS-generating systems through photodynamic or non-photodynamic procedures while tackling the challenges of the current PDT approaches. In this review, we summarize the current status and discuss the possible opportunities for ROS generation for cancer therapy. We hope this review will spur pre-clinical research and clinical practice for ROS-mediated tumour treatments.

Arsenic trioxide plus PX-478 achieves effective treatment in pancreatic ductal adenocarcinoma

Arsenic trioxide (ATO) has been selected as a promising treatment not only in leukemia but also in solid tumors. Previous studies showed that the cytotoxicity of ATO mainly depends on the induction of reactive oxygen species. However, ATO has only achieved a modest effect in pancreatic ductal adenocarcinoma, suggesting that the existing radical scavenging proteins, such as hypoxia inducible factor-1, attenuate the effect. The goal of this study is to investigate the effect of combination treatment of ATO plus PX-478 (hypoxia-inducible factor-1 inhibitor) and its underlying mechanism. Here, we showed that PX-478 robustly strengthened the anti-growth and pro-apoptosis effect of ATO on Panc-1 and BxPC-3 pancreatic cancer cells in vitro. Meanwhile, in vivo mouse xenograft models also showed the synergistic effect of ATO plus PX-478 compared with any single agent. Further studies showed that the anti-tumor effect of ATO plus PX-478 was derived from the reactive oxygen species-induced apoptosis. We next confirmed that Hypoxia-inducible factor-1 cleared reactive oxygen species by its downstream target, forkhead box O transcription factors, and this effect may justify the strategy of ATO plus PX-478 in the treatment of pancreatic cancer.

Parthenolide induces apoptosis and autophagy through the suppression of PI3K/Akt signaling pathway in cervical cancer

OBJECTIVE

To investigate the effect of parthenolide on apoptosis and autophagy and to study the role of the PI3K/Akt signaling pathway in cervical cancer.

RESULTS

Parthenolide inhibits HeLa cell viability in a dose dependent-manner and was confirmed by MTT assay. Parthenolide (6 µM) induces mitochondrial-mediated apoptosis and autophagy by activation of caspase-3, upregulation of Bax, Beclin-1, ATG5, ATG3 and down-regulation of Bcl-2 and mTOR. Parthenolide also inhibits PI3K and Akt expression through activation of PTEN expression. Moreover, parthenolide induces generation of reactive oxygen species that leads to the loss of mitochondrial membrane potential.

CONCLUSION

Parthenolide induces apoptosis and autophagy-mediated growth inhibition in HeLa cells by suppressing the PI3K/Akt signaling pathway and mitochondrial membrane depolarization and ROS generation. Parthenolide may be a potential therapeutic agent for the treatment of cervical cancer.

Reactive Oxygen Species and Targeted Therapy for Pancreatic Cancer

Pancreatic cancer is the fourth leading cause of cancer-related death in the United States. Reactive oxygen species (ROS) are generally increased in pancreatic cancer cells compared with normal cells. ROS plays a vital role in various cellular biological activities including proliferation, growth, apoptosis, and invasion. Besides, ROS participates in tumor microenvironment orchestration. The role of ROS is a doubled-edged sword in pancreatic cancer. The dual roles of ROS depend on the concentration. ROS facilitates carcinogenesis and cancer progression with mild-to-moderate elevated levels, while excessive ROS damages cancer cells dramatically and leads to cell death. Based on the recent knowledge, either promoting ROS generation to increase the concentration of ROS with extremely high levels or enhancing ROS scavenging ability to decrease ROS levels may benefit the treatment of pancreatic cancer. However, when faced with oxidative stress, the antioxidant programs of cancer cells have been activated to help cancer cells to survive in the adverse condition. Furthermore, ROS signaling and antioxidant programs play the vital roles in the progression of pancreatic cancer and in the response to cancer treatment. Eventually, it may be the novel target for various strategies and drugs to modulate ROS levels in pancreatic cancer therapy.

Arsenic Trioxide Inhibits Cell Growth and Invasion via Down- Regulation of Skp2 in Pancreatic Cancer Cells

Arsenic trioxide (ATO) has been found to exert anti-cancer activity in various human malignancies. However, the molecular mechanisms by which ATO inhibits tumorigenesis are not fully elucidated. In the current study, we explored the molecular basis of ATO-mediated tumor growth inhibition in pancreatic cancer cells. We used multiple approaches such as MTT assay, wound healing assay, Transwell invasion assay, annexin V-FITC, cell cycle analysis, RT-PCR and Western blotting to achieve our goal. We found that ATO treatment effectively caused cell growth inhibition, suppressed clonogenic potential and induced G2-M cell cycle arrest and apoptosis in pancreatic cancer cells. Moreover, we observed a significant down-regulation of Skp2 after treatment with ATO. Furthermore, we revealed that ATO regulated Skp2 downstream genes such as FOXO1 and p53. These findings demonstrate that inhibition of Skp2 could be a novel strategy for the treatment of pancreatic cancer by ATO.

New trends in guided nanotherapies for digestive cancers: A systematic review

Digestive tract tumors are among the most common and deadliest malignancies worldwide, mainly due to late diagnosis and lack of efficient therapeutics. Current treatments essentially rely on surgery associated with (neo)adjuvant chemotherapy agents. Despite an upfront response, conventional drugs often fail to eliminate highly aggressive clones endowed with chemoresistant properties, which are responsible for tumor recurrence and disease dissemination. Synthetic drugs also present severe adverse systemic effects, hampering the administration of biologically effective dosages. Nanoencapsulation of chemotherapeutic agents within biocompatible polymeric or lipid matrices holds great potential to improve the pharmacokinetics and efficacy of conventional chemotherapy while reducing systemic toxicity. Tagging nanoparticle surfaces with specific ligands for cancer cells, namely monoclonal antibodies or antibody fragments, has provided means to target more aggressive clones, further improving the selectivity and efficacy of nanodelivery vehicles. In fact, over the past twenty years, significant research has translated into a wide array of guided nanoparticles, providing the molecular background for a new generation of intelligent and more effective anti-cancer agents. Attempting to bring awareness among the medical community to emerging targeted nanopharmaceuticals and foster advances in the field, we have conducted a systematic review about this matter. Emphasis was set on ongoing preclinical and clinical trials for liver, colorectal, gastric and pancreatic cancers. To the best of our knowledge this is the first systematic and integrated overview on this field. Using a specific query, 433 abstracts were gathered and narrowed to 47 manuscripts when matched against inclusion/exclusion criteria. All studies showed that active targeting improves the effectiveness of the nanodrugs alone, while lowering its side effects. The main focus has been on hepatocarcinomas, mainly by exploring glycans as homing molecules. Other ligands such as peptides/small proteins and antibodies/antibody fragments, with affinity to either tumor vasculature or tumor cells, have also been widely and successfully applied to guide nanodrugs to gastrointestinal carcinomas. Conversely, few solutions have been presented for pancreatic tumors. To this date only three nanocomplexes have progressed beyond pre-clinical stages: i) PK2, a galactosamine-functionalized polymeric-DOX formulation for hepatocarcinomas; ii) MCC-465, an anti-(myosin heavy chain a) immunoliposome for advanced stage metastatic solid tumors; and iii) MBP-426, a transferrin-liposome-oxaliplatin conjugate, also for advanced stage tumors. Still, none has been approved for clinical use. However, based on the high amount of pre-clinical studies showing enthusiastic results, the number of clinical trials is expected to increase in the near future. A more profound understanding about the molecular nature of chemoresistant clones and cancer stem cell biology will also contribute to boost the field of guided nanopharmacology towards more effective solutions.

RIP3 overexpression sensitizes human breast cancer cells to parthenolide in vitro via intracellular ROS accumulation

AIM

Receptor-interacting protein 3 (RIP3) is involved in tumor necrosis factor receptor signaling, and results in NF-κB-mediated prosurvival signaling and programmed cell death. The aim of this study was to determine whether overexpression of the RIP3 gene could sensitize human breast cancer cells to parthenolide in vitro.

METHODS

The expression of RIP3 mRNA in human breast cancer cell lines (MCF-7, MDA-MB-231, MDA-MB-435 and T47D) was detected using RT-PCR. Both MDA-MB-231 and MCF-7 cells were transfected with RIP3 expression or blank vectors via lentivirus. Cell viability was measured with MTT assay; intracellular ROS level and cell apoptosis were analyzed using flow cytometry.

RESULTS

RIP3 mRNA expression was not detected in the four human breast cancer cell lines tested. However, the transfection induced higher levels of RIP3 protein in MCF-7 and MDA-MB-231 cells. Furthermore, overexpression of RIP3 decreased the IC50 values of parthenolide from 17.6 to 12.6 μmol/L in MCF-7 cells, and from 16.6 to 9.9 μmol/L in MDA-MB-231 cells. Moreover, overexpression of RIP3 significantly increased parthenolide-induced apoptosis and ROS accumulation in MCF-7 and MDA-MB-231 cells. Pretreatment with N-acetyl-cysteine abrogated the increased sensitivity of RIP3-transfected MCF-7 and MDA-MB-231 cells to parthenolide.

CONCLUSION

Overexpression of RIP3 sensitizes MCF-7 and MDA-MB-231 breast cancer cells to parthenolide in vitro via intracellular ROS accumulation.

Parthenolide enhances dacarbazine activity against melanoma cells

Dacarbazine induces a clinical response only in 15% of melanoma patients. New treatment strategies may involve combinations of drugs with different modes of action to target the tumor heterogeneity. We aimed to determine whether the combined treatment of heterogeneous melanoma cell populations in vitro with the alkylating agent dacarbazine and the nuclear factor-κB inhibitor parthenolide could be more effective than either drug alone. A panel of melanoma cell lines, including highly heterogeneous populations derived from surgical specimens, was treated with dacarbazine and parthenolide. The effect of drugs on the viable cell number was examined using an acid phosphatase activity assay, and the combination effect was determined by median-effect analysis. Cell death and cell-cycle arrest were assessed by flow cytometry. Gene expression was measured by real-time PCR and changes in the protein levels were evaluated by western blotting. Secretion of vascular endothelial growth factor and interleukin-8 was determined using an enzyme-linked immunosorbent assay. The self-renewing capacity was assessed using a clonogenic assay. Dacarbazine was less effective in heterogeneous melanoma populations than in the A375 cell line. Parthenolide and dacarbazine synergistically reduced the viable cell numbers. Both drugs induced cell-cycle arrest and apoptotic cell death. Importantly, parthenolide abrogated the baseline and dacarbazine-induced vascular endothelial growth factor secretion from melanoma cells in heterogeneous populations, whereas interleukin-8 secretion was not significantly affected by either drug. Parthenolide eradicated melanoma cells with self-renewing capacity also in cultures simultaneously treated with dacarbazine. The combination of parthenolide and dacarbazine might be considered as a new therapeutic modality against metastatic melanoma.

Parthenolide: from plant shoots to cancer roots

Parthenolide (PTL), a sesquiterpene lactone (SL) originally purified from the shoots of feverfew (Tanacetum parthenium), has shown potent anticancer and anti-inflammatory activities. It is currently being tested in cancer clinical trials. Structure-activity relationship (SAR) studies of parthenolide revealed key chemical properties required for biological activities and epigenetic mechanisms, and led to the derivatization of an orally bioavailable analog, dimethylamino-parthenolide (DMAPT). Parthenolide is the first small molecule found to be selective against cancer stem cells (CSC), which it achieves by targeting specific signaling pathways and killing cancer from its roots. In this review, we highlight the exciting journey of parthenolide, from plant shoots to cancer roots.

Targeting mitochondrial STAT3 with the novel phospho-valproic acid (MDC-1112) inhibits pancreatic cancer growth in mice

New agents are needed to treat pancreatic cancer, one of the most lethal human malignancies. We synthesized phospho-valproic acid, a novel valproic acid derivative, (P-V; MDC-1112) and evaluated its efficacy in the control of pancreatic cancer. P-V inhibited the growth of human pancreatic cancer xenografts in mice by 60%–97%, and 100% when combined with cimetidine. The dominant molecular target of P-V was STAT3. P-V inhibited the phosphorylation of JAK2 and Src, and the Hsp90-STAT3 association, suppressing the activating phosphorylation of STAT3, which in turn reduced the expression of STAT3-dependent proteins Bcl-x_L, Mcl-1 and survivin. P-V also reduced STAT3 levels in the mitochondria by preventing its translocation from the cytosol, and enhanced the mitochondrial levels of reactive oxygen species, which triggered apoptosis. Inhibition of mitochondrial STAT3 by P-V was required for its anticancer effect; mitochondrial STAT3 overexpression rescued animals from the tumor growth inhibition by P-V. Our results indicate that P-V is a promising candidate drug against pancreatic cancer and establish mitochondrial STAT3 as its key molecular target.

Sesquiterpene lactones as drugs with multiple targets in cancer treatment: focus on parthenolide

Sesquiterpene lactones (SLs) constitute a large and diverse group of biologically active plant compounds that possess anti-inflammatory and antitumor activity. The subclass germacranolides is one of the major groups of SLs. It includes parthenolide, a highly cytotoxic SL that is being tested in clinical trials as an anti-cancer agent. In this review, we focus on SL antitumor activity related to cell-cycle arrest, differentiation, apoptosis induction through the intrinsic pathway, and sensitization of the extrinsic pathway. We also address the regression of tumors in response to cotreatment with conventional chemotherapeutics. We review the nuclear factor-κB-targeted anti-inflammatory activity in vitro and in vivo and relate it to the SL structural features involved in the molecular mechanisms. It is obvious that SLs are emerging as promising anticancer agents, but more investigations are required to fully understand the molecular mechanisms of known SLs in different cell death modalities and how these mechanisms contribute toward the potent antitumor and anti-inflammatory activities of SLs.

Natural and synthetic α-methylenelactones and α-methylenelactams with anticancer potential

α-Methylene-γ- and δ-lactones, as well as α-methylene-γ- and δ-lactams, are plant-derived compounds often used in traditional medicine for the treatment of inflammatory diseases. In recent years, the anticancer properties of these compounds and the molecular mechanisms of their action have been studied extensively. In the search for modern anticancer drugs, various synthetic analogs of α-methylene-γ- and δ-lactones and lactams have been synthesized and tested for their cytotoxic activity. In this review, we give a brief description of the occurrence and biological activity of such compounds isolated from plants and their diverse synthetic analogs.

Arsenic and its combinations in cancer therapeutics

Arsenic is a metalloid that is considered to be a paradox in terms of its role both as a carcinogen and as a therapeutic agent. Chronic exposure to arsenic in drinking water has been linked with the development of various pathological conditions including cancer. Nevertheless, the therapeutic potential of arsenic and its derivatives in a variety of diseases have been exploited in the past. However, its role and mechanism of action as a therapeutic agent still remain an active area of research and investigation. Our ongoing work also suggests varied responses in cancer cells exposed to lower versus higher concentrations of arsenic. Furthermore, the arsenic combinations with chemopreventive or anticancer agents have been observed to sensitize the cell for cell-cycle arrest and cell death. Here, we have provided the account of recent updates on the mechanism of action of arsenic and its derivatives that lead to various disorders, and its role as a therapeutic agent both as a single agent as well as in combination chemotherapy.

The Feverfew plant-derived compound, parthenolide enhances platelet production and attenuates platelet activation through NF-κB inhibition

INTRODUCTION

Few treatments are available that can safely and effectively stimulate new platelet production for thrombocytopenic patients. Additionally, recipients of transfused platelets may experience an inflammatory response due to stored platelets becoming unnecessarily activated, thus creating the need for suitable agents that will dampen undesirable platelet activation. We investigated the effect of the feverfew plant-derived compound, parthenolide on platelet production and platelet activation because of its well-studied ability to induce apoptosis or differentiation in some types of cancer.

METHODS

Parthenolide was used to treat human megakaryoblastic cell lines, primary human and mouse megakaryocytes. Resulting platelet production and function was measured via flow cytometry. The two most common parthenolide signaling mechanisms, oxidative stress and nuclear factor-κB inhibition, were assessed within the megakaryocytes using reactive oxygen species, glutathione and luciferase reporter assays. The influence of parthenolide on ex vivo platelet activation was tested with parthenolide pretreatment followed by collagen or thrombin activation. The resulting P-selectin surface expression and released soluble CD40 ligand was measured.

RESULTS

Parthenolide stimulates functional platelet production from human megakaryocyte cell lines, and from primary mouse and human megakaryocytes in vitro. Parthenolide enhances platelet production via inhibition of nuclear factor-κB signaling in megakaryocytes and is independent of the parthenolide-induced oxidative stress response. Additionally, parthenolide treatment of human peripheral blood platelets attenuated activation of stimulated platelets.

CONCLUSION

Overall, these data reveal that parthenolide has strong potential as a candidate to enhance platelet production and to dampen undesirable platelet activation.

Nitroglycerin alters matrix remodeling proteins in THP-1 human macrophages and plasma metalloproteinase activity in rats

Several studies suggested that long-term nitrate therapy may produce negative outcomes in patient mortality and morbidity. A possible mechanism may involve nitrate-mediated activation of various extracellular matrix (ECM) proteases, particularly matrix metalloproteinase-9 (MMP-9), and adhesion molecules in human macrophages, leading to the destabilization of atherosclerotic plaques. We examined the gene and protein regulating effects on THP-1 human macrophages by repeated exposure to therapeutically relevant concentrations of nitroglycerin (NTG) and possible involvement of nuclear factor (NF)-κB signaling mechanism in mediating some of these observed effects. THP-1 human macrophages repeatedly exposed to NTG (at 10 nM, added on days 1, 4 and 7) exhibited extensive alterations in the expression of multiple genes encoding ECM proteases and adhesion molecules. These effects were dissimilar to those produced by a direct nitric oxide donor, diethylenetriamine NONOate. NTG exposure significantly up-regulated NF-κB DNA nuclear binding activity and MMP-9 protein expression, and reduced tissue inhibitor of metalloproteinase-1 (TIMP-1) expression; these effects were abrogated in the presence of the NF-κB inhibitor parthenolide (a chemical inhibitor derived from the feverfew plant). Further, we examined whether our in vitro findings (an elevated MMP-9/TIMP-1 ratio and gelatinase activity) can be translated to in vivo effects, in a rat model. Sprague-Dawley rats exposed continuously to NTG subcutaneously for 8 days via mini-osmotic pumps showed significant induction of plasma MMP-9 dimer concentrations and the expression of a complex of MMP-9 with lipocalin-2 or neutrophil gelatinase associated lipocalin (NGAL). Plasma gelatinase activity was significantly increased by NTG over the entire study period, attaining peak elevation at day 6. Plasma TIMP-1 protein was down-regulated significantly by day 2 and days 4-7 in the NTG-treated rats. Pharmacokinetic monitoring of NTG and its dinitrate metabolites indicated that concentrations were well within therapeutic levels observed in humans. Our studies indicate that clinically relevant concentrations of NTG not only altered ECM matrix by changing the expression of multiple genes that govern cellular integrity, affecting cellular MMP-9/TIMP-1 balance in THP-1 human macrophages possibly via NF-κB activation, but also led to systemic changes in MMP-9/TIMP-1 expression and gelatinase activity in rats. These effects may contribute to extracellular matrix degradation and possible atherosclerotic plaque destabilization.

Inhibition of heme oxygenase-1 enhances anti-cancer effects of arsenic trioxide on glioma cells

We have previously reported that arsenic trioxide (ATO) could inhibit glioma growth both in vitro and in vivo, and demonstrated its potent therapeutic effects on gliomas. In this study we showed that ATO induced cell damage and heme oxygenase-1 (HO-1) expression in glioma cells via ROS generation. HO-1 inducer clearly protected from ATO-induced cell death and ROS generation, and HO-1 inhibitor led to a significant increase in cell death and ROS generation induced by ATO. In addition, knockdown of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) strongly inhibited HO-1 expression induced by ATO, and significantly enhanced ATO-induced oxidative damage. Our results demonstrated, for the first time, that HO-1 inhibition or Nrf2 knockdown significantly potentiated ATO's effects on glioma cells. Considering that HO-1 is highly expressed in glioma tissues, administration of ATO in combination with either HO-1 inhibitor or Nrf2 knockdown may act as a new approach to the treatment of glioma.

Tailored α-methylene-γ-butyrolactones and their effects on growth suppression in pancreatic carcinoma cells

A selected series of racemic α-methylene-γ-butyrolactones (AMGBL) were synthesized via allylboration and screened against three human pancreatic cancer cell lines (Panc-1, MIA PaCa-2, and BxPC-3). This systematic study established a discernible relationship between the substitution pattern of AMGBL and their anti-proliferative activity. β,γ-diaryl-AMGBLs, particularly those with a trans-relationship exhibited higher potency than parthenolide and LC-1 against all three cell lines.

Parthenolide induces proliferation inhibition and apoptosis of pancreatic cancer cells in vitro

Background

To explore the anti-tumor effects of parthenolide in human pancreatic cancer.

Methods

BxPC-3 cell, a human pancreatic cancer, was treated with parthenolide at different concentrations. The MTT assay was used to analyze cell viability. Flow cytometry and DNA fragmentation analysis were applied to evaluate apoptosis after parthenolide treatment. The wound closure and cell invasion assay were also employed in the study. Western blotting was used to demonstrate Bad, Bcl-2, Bax, caspase-9 and pro-caspase-3 expression.

Results

The MTT assay indicated that the pancreatic cancer growth could be dose-dependently inhibited by parthenoolide. This phenomenon was confirmed by flow cytometry and DNA fragmentation analysis. The wound closure assay and cell invasion assay showed that BxPC-3 cell was significantly suppressed by parthenolide at 7.5 μM and 15 μM. Western Blotting demonstrated the Bcl-2 and pro-caspase-3 were down-regulated while the Bax and caspase-9 were up-regulated. No alteration in Bad expression was found after treatment.

Conclusions

The parthenolide can inhibit the cell growth, migration, and induce the apoptosis in human pancreatic cancer. These findings may provide a novel approach for pancreatic cancer treatment.