Apoptosis sensitization by Euphorbia factor L1 in ABCB1-mediated multidrug resistant K562/ADR cells

Euphorbia factor L1 suppresses breast cancer liver metastasis via DDR1-mediated immune infiltration

Euphorbia factor L1 (EFL1), a lathyrane-type diterpenoid from the medicinal herb Euphorbia lathyris L., has been documented to possess various pharmacologic actives. However, the function of EFL1 on breast cancer is not clear. In this study, we explored the effect and mechanism of EFL1 on breast cancer liver metastasis. Female BALB/c mice were subjected to breast cancer-surgical hepatic implantation (SHI) to establish breast cancer liver metastasis model in vivo. At 10 days post-surgery, mice were administrated with EFL1 once daily for a total of 2 weeks. Serum AST and ALT activities, abdominal circumference, peritoneal fluid, tumor weight and volume were determined to assess liver and mesenteric re-metastasis of breast cancer. H&E staining was used to observe morphology changes in tumor, liver and small intestine tissues. ELISA was applied to observe inflammatory levels. Tumor DDR1 expression and immune infiltration were determined using western blotting, immunohistochemistry and flow cytometer methods. Our results showed that EFL1 administration improved liver function (AST and ALT activities), ascites, liver metastasis and mesenteric re-metastasis in SHI mice. Also, SHI-induced inflammatory cell infiltration and IL-1β, IL-6, TNF-α generation in ascites were decreased by EFL1 treatment. Mechanism study revealed that EFL1 intervention enhanced the ratios of CD4+ and CD8+ and CD49b+(NK) T lymphocytes and decreased Treg cells through downregulating DDR1 in the tumor of SHI mice. Furthermore, overexpression of DDR1 abolished the anti-liver metastasis effect and pro-immune infiltration action of EFL1 in SHI mice. Together, our findings suggested that EFL1 protects against breast cancer liver metastasis in vivo by targeting DDR1-mediated immune infiltration.

Microbial and chemical transformations of euphorbia factor L1 and the P-glycoprotein inhibitory activity in zebrafishes

Euphorbia factor L1 (EFL1, 1) is a natural tri-ester of 6,17-epoxylathyrol with cancer multidrug resistance (MDR) reversal activity. Several EFL1 derivatives (2-9) were prepared by chemical and microbial transformations and their ability to inhibit P-glycoprotein (P-gp) activity was estimated. Six de-acylated derivatives (2-7) were obtained through base-hydrolysis of 1, and the base-catalysed hydrolysis via KOH and NaOH yielded different hydrolysed products of 1. Two biotransformed products (8-9) were directly obtained via microbial transformation of 1, and 8 was also formed by microbial conversion of the hydrolysed product 3. The P-gp modulation of 1-9 was assessed by a zebrafish model. The substrate 1 and its biotransformed product 9 as the tri-esters of lathyranes possessed the highest P-gp inhibitory activity with IC₅₀ values of 34.97 and 15.50 µM, respectively, through down-regulating P-gp expression at the protein level rather than at MDR1 mRNA level.

Euphorbia diterpenoids: isolation, structure, bioactivity, biosynthesis, and synthesis (2013-2021)

Covering: 2013 to 2021As the characteristic metabolites of Euphorbia plants, Euphorbia diterpenoids have always been a hot topic in related science communities due to their intriguing structures and broad bioactivities. In this review, we intent to provide an in-depth and extensive coverage of Euphorbia diterpenoids reported from 2013 to the end of 2021, including 997 new Euphorbia diterpenoids and 78 known ones with latest progress. Multiple aspects will be summarized, including their occurrences, chemical structures, bioactivities, and syntheses, in which the structure-activity relationship and biosynthesis of this class will be discussed for the first time.

Construction of magnetic drug delivery system and its potential application in tumor theranostics

Magnetic nanoparticles(NPs) are characterized by a rich variety of properties. Because of their excellent physical and chemical properties, they have come to the fore in biomedicine and other fields. The magnetic NPs were extensively studied in magnetic separation of cells, targeted drug delivery, tumor hyperthermia, chemo-photothermal therapy, magnetic resonance imaging (MRI) and other biomedical fields. Magnetic NPs are increasingly used in magnetic resonance imaging (MRI) based on their inherent magnetic targeting, superparamagnetic enzyme-like catalytic properties and nanoscale size. Poly(lactic-co-glycolic acid) (PLGA) is a promising biodegradable material approved by FDA and EU for drug delivery. Currently, PLGA-based magnetic nano-drug delivery systems have attracted the attention of researchers. Herein, we achieved the effective encapsulation of sized-controlled polyethylene glycol-3,4-dihydroxy benzyl-amine-coated superparamagnetic iron oxide nanoparticles (SPIO NPs) and euphorbiasteroid into PLGA nanospheres via a modified multiple emulsion solvent evaporation method (W₁/O₂/W₂). NPs with narrow size distribution and acceptable magnetic properties were developed that are very useful for applications involving cancer therapy and MRI. Furthermore, SPIO-PLGA NPs enhanced the MRI T₂ relaxation properties of tumor sites.The prepared SPIO NPs and magnetic PLGA nanospheres can be promising magnetic drug delivery systems for tumor theranostics. This study has successfully constructed a tumor-targeting and magnetic-targeting smart nanocarrier with enhanced permeability and retention, multimodal anti-cancer therapeutics and biodegradability, which could be a hopeful candidate for anti-tumor therapy in the future.

The Role of Ingenane Diterpenes in Cancer Therapy: From Bioactive Secondary Compounds to Small Molecules

Diterpenes are a class of critical taxonomic markers of the Euphorbiaceae family, representing small compounds (eg, molecules) with a wide range of biological activities and multi-target therapeutic potential. Diterpenes can exert different activities, including antitumor and multi-drug resistance-reversing activities, and antiviral, immunomodulatory, and anti-inflammatory effects, mainly due to their great structural diversity. In particular, one polycyclic skeleton has been highlighted: ingenane. Besides this natural diterpene, promising polycyclic skeletons may be submitted to chemical modification—by in silico approaches, chemical reactions, or biotransformation—putatively providing more active analogs (eg, ingenol derivatives), which are currently under pre-clinical investigation. This review outlines the current mechanisms of action and potential therapeutic implications of ingenol diterpenes as small cancer molecules.

Pharmacological Potential of Lathyrane-Type Diterpenoids from Phytochemical Sources

Lathyrane diterpenoids are one of the primary types of secondary metabolites present in the genus Euphorbia and one of the largest groups of diterpenes. They are characterized by having a highly oxygenated tricyclic system of 5, 11 and 3 members. These natural products and some synthetic derivatives have shown numerous interesting biological activities with clinical potential against various diseases, such as cytotoxic activity against cancer cell lines, multi-drug resistance reversal, antiviral properties, anti-inflammatory activity and their capability to induce proliferation or differentiation into neurons of neural progenitor cells. The structure of the lathyrane skeleton could be considered privileged because its framework is able to direct functional groups in a well-defined space. The favorable arrangement of these makes interaction possible with more than one target. This review aims to highlight the evidence of lathyranes as privileged structures in medicinal chemistry. Chemical structures of bioactive compounds, the evaluation of biological properties of natural and semisynthetic derivatives, and the exploration of the mechanisms of action as well as target identification and some aspects of their targeted delivery are discussed.

Characterization of diterpene metabolism in rats with ingestion of seed products from Euphorbia lathyris L. (Semen Euphorbiae and Semen Euphorbiae Pulveratum) using UHPLC-Q-Exactive MS

Previous pharmacological studies have indicated that diterpenoids are the primary effective chemical cluster in the seeds of Euphorbia lathyris L. The seed products are used in traditional Chinese medicine in the forms of Semen Euphorbiae (SE) and Semen Euphorbiae Pulveratum (SEP). However, the metabolism of the plant's diterpenoids has not well elucidated, which means that the in vivo metabolites products have not been identified. In the current study, the physiological metabolites of six diterpenes (Euphorbia factor L₁ (L1), L₂ (L2), L₃ (L3), L_7a (L7a), L_7b (L7b), and L₈ (L8) were screened in feces and urine of rats after oral administration of SE and SEP, using UHPLC-Q-Exactive MS. A total of 22 metabolites were detected in feces and eight in urine, indicating that the major elimination route of diterpenoids is via the colon. Hydrolysis, methylation and glucuronidation served as be the primary metabolic pathways of these diterpenoids. To sum up, this study contributed toward the elucidated of new metabolites and metabolic pathways of SE and SEP, and the new chemical identities can be used to guide further pharmacokinetic studies.

Research Progress on Natural Diterpenoids in Reversing Multidrug Resistance

Multidrug resistance (MDR) is one of the main impediments in successful chemotherapy in cancer treatment. Overexpression of ATP-binding cassette (ABC) transporter proteins is one of the most important mechanisms of MDR. Natural products have their unique advantages in reversing MDR, among which diterpenoids have attracted great attention of the researchers around the world. This review article summarizes and discusses the research progress on diterpenoids in reversing MDR.

Effect of lathyrol derivatives on non-small cell lung cancer and the possible mechanism

OBJECTIVES

Non-small cell lung cancer (NSCLC) accounts for 85% of all lung cancer, with highmorbidity and mortality rate. Nove drug development for NSCLC is urgently needed.This study aims to investigate the activity of lathyrol derivatives and the mechanism for its inhibitory effect on the growth of NSCLC cells.

METHODS

Three lathyrol derivatives were synthesized from lathyrol and their structures were verified by nuclear magnetic resonance. MTT assay was used to detect the effects of the lathyrol derivatives on the proliferation activity of NSCLC cells (A549 and H1299 cells), and the compound with the best activity was selected for subsequent experiments. Colony forming assay, wound-healing assay, and transwell assay were applied to detect in vitro cell proliferation, migration and invasion ability in A549 and H1299 cells, respectively. Quantitative real-time RT-PCR and Western blotting were performed to detect mRNA and protein levels of E-cadherin, N-cadherin, β-catenin, and MMP2 in A549 cells, respectively.

RESULTS

Three lathyrol derivatives inhibited the growth of A549 and H1299 cells in a dose-dependent manner, and they showed a weak inhibitory effect on normal cells Beas-2B and 16HBE, indicating that they possessed certain selective toxic effects. Therefore, C-5 benzoylated lathyrol with the best activity was selected as the ideal drug for the subsequent experiments. Compared with the control group, the number and size of cell clusters in the treatment group of A549 and H1299 cells were significantly decreased, the relative mobility were significantly decreased, and the number of invaded cells were significantly decreased (all P<0.05), indicating that the in vitro cell proliferation, migration and invasion ability were decreased. The mRNA levels of integrin α2, integrin β1, MMP2, MMP9, β-catenin, and N-cadherin were decreased, while the expression of E-cadherin was increased (all P<0.05). The protein levels of N-cadherin, β-catenin, MMP2, and integrin αV were decreased, while the expression of E-cadherin was increased (all P<0.05).

CONCLUSIONS

The lathyrol derivatives synthesized in this study possess good inhibitory activity against NSCLC. Among them, C-5 benzoylated lathyrol significantly inhibits the proliferation, migration, and invasion ability of NSCLC cells in vitro through regulating the process of epithelial-mesenchymal transition.

Simultaneous separation and determination of three diterpenoids in Euphorbia lathyris L. and its formulations by hydrophobic interaction electrokinetic chromatography

In this study, a hydrophobic interaction electrokinetic chromatography method has been developed for simultaneous separation and determination of three diterpenoids in Euphorbia lathyris L.: Euphorbia factors L₁ , L₂ , and L₃ . After optimization of separation conditions, the electrolyte solution was 5.0 mM ammonium acetate buffer containing 30 mM sodium dodecyl sulfate in a 60% v/v methanol (pH 6.86), 25 kV of electric field across the capillary was applied at 25°C, and the detection wavelength was at 280 nm. Under optimum conditions, good linearity was achieved with correlation coefficients from 0.9945 to 0.9995. The limits of detection were 2.5, 7.5, and 5.6 μg/mL, and the limits of quantitation were 8.8, 23.9, and 15.3 μg/mL, respectively. Excellent accuracy and precision were obtained. Recoveries of the analytes varied from 98.5 to 103.8%. The established method was novel, simple, and rapid, and it was validated and confirmed to be applicable for the determination of the active ingredients in a quality control analysis.

Analysis of ceRNA networks and identification of potential drug targets for drug-resistant leukemia cell K562/ADR

Background

Drug resistance is the main obstacle in the treatment of leukemia. As a member of the competitive endogenous RNA (ceRNA) mechanism, underlying roles of lncRNA are rarely reported in drug-resistant leukemia cells.

Methods

The gene expression profiles of lncRNAs and mRNAs in doxorubicin-resistant K562/ADR and sensitive K562 cells were established by RNA sequencing (RNA-seq). Expression of differentially expressed lncRNAs (DElncRNAs) and DEmRNAs was validated by qRT-PCR. The potential biological functions of DElncRNAs targets were identified by GO and KEGG pathway enrichment analyses, and the lncRNA-miRNA-mRNA ceRNA network was further constructed. K562/ADR cells were transfected with CCDC26 and LINC01515 siRNAs to detect the mRNA levels of GLRX5 and DICER1, respectively. The cell survival rate after transfection was detected by CCK-8 assay.

Results

The ceRNA network was composed of 409 lncRNA-miRNA pairs and 306 miRNA-mRNA pairs based on 67 DElncRNAs, 58 DEmiRNAs and 192 DEmRNAs. Knockdown of CCDC26 and LINC01515 increased the sensitivity of K562/ADR cells to doxorubicin and significantly reduced the half-maximal inhibitory concentration (IC₅₀) of doxorubicin. Furthermore, knockdown of GLRX5 and DICER1 increased the sensitivity of K562/ADR cells to doxorubicin and significantly reduced the IC₅₀ of doxorubicin.

Conclusions

The ceRNA regulatory networks may play important roles in drug resistance of leukemia cells. CCDC26/miR-140-5p/GLRX5 and LINC01515/miR-425-5p/DICER1 may be potential targets for drug resistance in K562/ADR cells. This study provides a promising strategy to overcome drug resistance and deepens the understanding of the ceRNA regulatory mechanism related to drug resistance in CML cells.

Dual-Target Peptide-Modified Erythrocyte Membrane-Enveloped PLGA Nanoparticles for the Treatment of Glioma

Penetration of the blood–brain barrier (BBB) and the blood–brain tumor barrier (BBTB) remains a significant challenge for the delivery of drugs in the treatment of glioma. Therefore, the development of targeted preparations with the ability to penetrate the BBB and BBTB, and target gliomas, is an important approach if we are to improve the efficacy of glioma treatment. In the current study, an active targeting preparation based on PLGA nanoparticles coated with erythrocyte membranes (RBCNPs) and dual-modified with ^DWSW and NGR peptide ligands (^DWSW/NGR-RBCNPs). Euphorbia factor L1 (EFL1) extracted from euphorbiae semen was used as the model drug. The final nanoparticles were characterized by in vivo and in vitro tests. In vitro results showed that EFL1-loaded ^DWSW/NGR-RBCNPs were taken up by cells and had the ability to penetrate the BBB and BBTB and produce cytotoxic effects. Furthermore, in vivo studies in mice showed that when injected intravenously, these specialized NPs could enter the brain, target tumor tissue, and significantly extend life span. The results showed that dual-targeting EFL1-loaded ^DWSW/NGR-RBCNPs have significant potential as a nanotherapeutic tool for the treatment of brain glioma.

Effect of euphorbia factor L1 on oxidative stress, apoptosis, and autophagy in human gastric epithelial cells

BACKGROUND

Euphorbia factor L1 (EFL1), a lathyrane-type diterpenoid from the medicinal herb Euphorbia lathyris L. (Euphorbiaceae), has been reported for many decades to induce gastric irritation, but the underlying mechanisms remain unclear.

PURPOSE

The objective of this study was to investigate EFL1-induced cytotoxicity and the potential mechanisms of action on the human normal gastric epithelial cell GES-1.

METHODS

GES-1 cells were treated with EFL1 (12.5-200 μM) for different time intervals, and cell survival, LDH release, intracellular reactive oxygen species (ROS), malondialdehyde (MDA) content, and superoxide dismutase (SOD) activity were detected. Mitochondrial membrane potential (MMP) assay, DAPI staining, DNA fragment assay, and annexin V-FITC/PI staining were performed. The interaction between EFL1 and Bcl-2, cytochrome c, caspase-9, caspase-3, PI3K, AKT, and mTOR proteins was simulated by molecular docking. The mRNA and protein expression of apoptosis and autophagy factors were detected by RT-qPCR and Western blotting.

RESULTS

EFL1 decreased survival, increased LDH leakage, and induced abnormal production of ROS, MDA and SOD in GES-1 cells. Mitochondria-mediated apoptosis was characterized by decreased MMP, condensed nuclei, fragmented DNA, and increased apoptosis rate. EFL1 interacted with proteins via hydrogen bonding. The mRNA, total or phosphorylated protein expression of Bcl-2, mitochondrial cytochrome c, PI3K, AKT, mTOR and p62 were downregulated; in contrast, those of cytoplasmic cytochrome c, cleaved caspase-9, cleaved caspase-3, LC3-ll and Beclin-1 were upregulated.

CONCLUSION

These findings indicated that EFL1 decreased the survival of GES-1 cells through EFL1-induced oxidative stress, activation of the mitochondria-mediated apoptosis as well as autophagy via inhibition of the PI3K/AKT/mTOR pathway.

The phytochemistry, pharmacokinetics, pharmacology and toxicity of Euphorbia semen

ETHNOPHARMACOLOGICAL RELEVANCE

Euphorbia semen, the dried and ripe seed of Euphorbia lathyris Linnaeus, is widely cultivated for traditional medicine use. This semen is used to expel water, help with phlegm retention, promote blood circulation, remove blood stasis, cure tinea and scabies, and treat amenorrhea, snakebites, terminal schistosomiasis, anuria and constipation.

AIM OF THE REVIEW

This review provides updated, comprehensive and categorized information on the local and traditional uses, phytochemistry, pharmacokinetics, pharmacological activities and toxicity of Euphorbia semen. Future research to deepen the recognition and utilization of Euphorbia semen is proposed.

MATERIALS AND METHODS

This article conducted a literature review on information about Euphorbia semen in multiple Internet databases, including PubMed, Web of Science, Wiley, Science Direct, Elsevier, ACS publications, SciFinder, Google Scholar and China National Knowledge Internet, until March of 2018. In this manuscript, a number of books, PhD and MSc dissertations, and Chinese Pharmacopeia were also used as references.

RESULTS

Approximately 240 chemical constituents have been isolated and identified from Euphorbia semen, namely, diterpenoids, coumarins, flavonoids, fatty acids, amino acids, and steroids. Pharmacokinetic study focused on investigating absorption, distribution, metabolism and excretion (ADME). The chemical constituents have extensive pharmacological effects, such as diuresis and anti-hyperuricaemia, anti-inflammation, antiviral, anticancer, antioxidant, antipigmentation, anti-platelet aggregation and anti-allergic activities, as well as hepatoprotection and neuroprotection. The toxicity of Euphorbia semen, including acute toxicity, target organ irritation and cocareinogenic effects, have been reported, and the detoxification methods are reviewed.

CONCLUSION

Euphorbia semen has extensive pharmacological activity and excellent clinical value, along with intense intestinal irritation. Although plenty of chemical constituents have been isolated and identified, the exact pharmacological and toxicological mechanisms still need to be explored.

Mechanism of action of cytotoxic compounds from the seeds of Euphorbia lathyris

BACKGROUND

The seeds of Euphorbia lathyris are used in traditional Chinese medicines for the treatment of various medical conditions. E. lathyris contains many natural diterpenes with a lathyrane skeleton.

PURPOSE AND STUDY DESIGN

Five lathyrane-type diterpenoids named Euphorbia factors L₁, L₂, L₃, L₈, and L₉ (1-5), were investigated for cytotoxicity against A549, MDA-MB-231, KB, and MCF-7 cancer cell lines and the KB-VIN multidrug resistant (MDR) cancer cell line. Also, a tetraol derivative (6) of Euphorbia factor L₂ (2) was synthesized to assess the effect of hydroxy moieties.

METHODS

An ethanolic extract of seeds of Euphorbia lathyris was prepared and separated into petroleum ether, EtOAc, n-butanol, and n-hexane extracts. The natural diterpenes were isolated by using silica gel and Sephadex LH-20 column chromatography as well as preparative thin-layer chromatography. Saponification of 2 gave tetraol derivative 6. Cytotoxic activity was determined by the sulforhodamine B (SRB) colorimetric assay. Mechanism of action studies focused on the impact of compounds on the cell cycle progression as well as cell morphology.

RESULTS

Compound 5 exhibited the strongest cytotoxicity against all cell lines, while compound 2 showed selectivity against KB-VIN. In cells treated with 3 and 5, accumulation of G1 to early S phase cells was obvious, while no effect was seen on G2/M phase.

CONCLUSION

Analysis of the screening data compared with compound structures suggested that the substitutions at C-3, C-5, C-7, and C-15 are critical for cytotoxicity, as well as cell type-selectivity. Furthermore, results of cytotoxic mechanism analysis demonstrated for the first time that compounds 3 and 5 disrupted normal cell cycle progression, whereas compounds 2‒5 induced obvious actin filament aggregation, as well as partial interference of the microtubule network.

Towards Comprehension of the ABCB1/P-Glycoprotein Role in Chronic Myeloid Leukemia

Abstract: The introduction of imatinib (IM), a BCR-ABL1 tyrosine kinase inhibitor (TKI), has represented a significant advance in the first-line treatment of chronic myeloid leukemia (CML). However, approximately 30% of patients need to discontinue IM due to resistance or intolerance to this drug. Both resistance and intolerance have also been observed in treatment with the second-generation TKIs-dasatinib, nilotinib, and bosutinib-and the third-generation TKI-ponatinib. The mechanisms of resistance to TKIs may be BCR-ABL1-dependent and/or BCR-ABL1-independent. Although the role of efflux pump P-glycoprotein (Pgp), codified by the ABCB1 gene, is unquestionable in drug resistance of many neoplasms, a longstanding question exists about whether Pgp has a firm implication in TKI resistance in the clinical scenario. The goal of this review is to offer an overview of ABCB1/Pgp expression/activity/polymorphisms in CML. Understanding how interactions, associations, or cooperation between Pgp and other molecules-such as inhibitor apoptosis proteins, microRNAs, or microvesicles-impact IM resistance risk may be critical in evaluating the response to TKIs in CML patients. In addition, new non-TKI compounds may be necessary in order to overcome the resistance mediated by Pgp in CML.

Euphorbia factor L1 inhibits osteoclastogenesis by regulating cellular redox status and induces Fas-mediated apoptosis in osteoclast

Excessive bone resorption caused by increased osteoclast number or activity leads to a variety of bone diseases including osteoporosis, rheumatoid arthritis and periodontitis. Thus, the therapeutic strategy for these diseases has been focused primarily on the inhibition of osteoclast formation and function. This study shows that euphorbia factor L1 (EFL1), a diterpenoid isolated from Euphorbia lathyris, inhibited osteoclastogenesis and induced osteoclast apoptosis. EFL1 suppressed osteoclast formation and bone resorption at both initial and terminal differentiation stages. EFL1 inhibited receptor activator of NF-κB ligand (RANKL)-induced NFATc1 induction with attenuated NF-κB activation and c-Fos expression. EFL1 decreased the level of reactive oxygen species by scavenging them or activating Nrf2, and inhibited PGC-1β that regulates mitochondria biogenesis. In addition, EFL1 induced apoptosis in differentiated osteoclasts by increasing Fas ligand expression followed by caspase activation. Moreover, EFL1 inhibited inflammation-induced bone erosion and ovariectomy-induced bone loss in mice. These findings suggest that EFL1 inhibits osteoclast differentiation by regulating cellular redox status and induces Fas-mediated apoptosis in osteoclast, and may provide therapeutic potential for preventing or treating bone-related diseases caused by excessive osteoclast.

Tomentodione M sensitizes multidrug resistant cancer cells by decreasing P-glycoprotein via inhibition of p38 MAPK signaling

In this study, we investigated the mechanism by which tomentodione M (TTM), a novel natural syncarpic acid-conjugated monoterpene, reversed multi-drug resistance (MDR) in cancer cells. TTM increased the cytotoxicity of chemotherapeutic drugs such as docetaxel and doxorubicin in MCF-7/MDR and K562/MDR cells in a dose- and time-dependent manner. TTM reduced colony formation and enhanced apoptosis in docetaxel-treated MCF-7/MDR and K562/MDR cells, and it enhanced intracellular accumulation of doxorubicin and rhodamine 123 in MDR cancer cells by reducing drug efflux mediated by P-gp. TTM decreased expression of both P-gp mRNA and protein by inhibiting p38 MAPK signaling. Similarly, the p38 MAPK inhibitor SB203580 reversed MDR in cancer cells by decreasing P-gp expression. Conversely, p38 MAPK-overexpressing MCF-7 and K562 cells showed higher P-gp expression than controls. These observations indicate that TTM reverses MDR in cancer cells by decreasing P-gp expression via p38 MAPK inhibition.

Structure Identification and In Vitro Anticancer Activity of Lathyrol-3-phenylacetate-5,15-diacetate

Natural products from the genus Euphorbia show attention-attracting activities, such as anticancer activity. In this article, classical isolation and structure identification were used in a study on Caper Euphorbia Seed. Subsequently, MTT and wound healing assays, flow cytometry, western blotting, Hoechst 33258 staining and fluorescence microscopy examination were applied to investigate the anticancer activity of the obtained compounds. In a result, lathyrol-3-phenyl- acetate-5,15-diacetate (deoxy Euphorbia factor L1, DEFL1) was isolated from Caper Euphorbia Seed. Moreover, the NMR signals were totally assigned. DEFL1 showed potent inhibition against lung cancer A549 cells, with an IC₅₀ value of 17.51 ± 0.85 μM. Furthermore, DEFL1 suppressed wound healing of A549 cells in a concentration-dependent manner. Mechanically, DEFL1 induced apoptosis, with involvement of an increase of reactive oxygen species (ROS), decrease of mitochondrial membrane potential (ΔΨm), release of cytochrome c, activity raise of caspase-9 and 3. Characteristic features of apoptosis were observed by fluorescence microscopy. In summary, DEFL1 inhibited growth and induced apoptosis in lung cancer A549 cells via a mitochondrial pathway.

Bruceine D induces apoptosis in human chronic myeloid leukemia K562 cells via mitochondrial pathway

Chronic myeloid leukemia (CML), an acquired malignant myeloproliferative disorder of hematopoietic stem cells, is one of the three most common forms of leukemia. In this study, we investigated the effects of bruceine D, which have been isolated from Brucea javanica (L.) Merr. on human chronic myeloid leukemia K562 cells. MTT assay was used to evaluate cell growth inhibition. Flow cytometry was performed to analyze mitochondrial membrane potential (ΔΨm). Western blot was applied to detect expression of cytochrome c, caspases-9, -3, PARP and other proteins. Bruceine D exhibited potent cytotoxicity to K562 cells with IC50 of 6.37 ± 0.39 μM. It led to loss of ΔΨm, release of cytochrome c, activation of caspases-9, -3 and cleavage of PARP, which suggested that bruceine D induced apoptosis of K562 cells through mitochondrial pathway. In addition, bruceine D inhibited the phosphorylation of AKT and ERK. It's indicative that the potent anticancer activity of bruceine D be related to MAPK and PI3K pathways.

Combinational Treatment of Curcumin and Quercetin against Gastric Cancer MGC-803 Cells in Vitro

Gastric cancer remains a major health problem worldwide. Natural products, with stronger antitumor activity and fewer side effects, are potential candidates for pharmaceutical development as anticancer agents. In this study, quercetin and curcumin were chosen for testing and were applied separately and in combination to human gastric cancer MGC-803 cells. The MTT assay was used to evaluate cell growth inhibition. Annexin V-FITC/PI was carried out to measure apoptosis rate. Flow cytometry was performed to analyze mitochondrial membrane potential levels. Western blots were applied to detect expression of cytochrome c, total and phosphorylated ERK and AKT. Combined treatment with curcumin and quercetin resulted in significant inhibition of cell proliferation, accompanied by loss of mitochondrial membrane potential (ΔΨm), release of cytochrome c and decreased phosphorylation of AKT and ERK. These results indicate that the combination of curcumin and quercetin induces apoptosis through the mitochondrial pathway. Notably, effect of combined treatment with curcumin and quercetin on gastric cancer MGC-803 cells is stronger than that of individual treatment, indicating that curcumin and quercetin combinations have potential as anti-gastric cancer drugs for further development.

siRNA silencing EZH2 reverses cisplatin-resistance of human non-small cell lung and gastric cancer cells

Clinical resistance to chemotherapeutic agents is one of the major hindrances in the treatment of human cancers. EHZ2 is involved in drug resistance and is overexpressed in drug-resistant cancer cell lines. In this study, we investigated the effects of EHZ2 on cisplatin -resistance in A549/DDP and AGS/DDP cells. EHZ2 mRNA and protein were found to be significantly overexpressed in A549/DDP and AGS/DDP cells, compared to parental cells. EHZ2 siRNA successfully silenced EHZ2 mRNA and protein expression. Proliferation was inhibited and drug resistance to cisplatin was improved. Flow cytometry showed that silencing of EHZ2 arrested A549/DDP and AGS/DDP cells in the G0/G1 phase, increasing apoptosis, rh-123 fluorescence intensity and caspase-3/8 activities. Silencing of EHZ2 also significantly reduced the mRNA and protein expression levels of cyclin D1 and MDR1,while up-regulating p15, p21, p27 and miR-218 in A549/DPP cells. Furthermore, silencing of EHZ2 also significantly increased the expression level of tumor suppressor factor miR-218. We also found down-regulating EHZ2 expression increased methylation in A549/DDP and AGS/DDP cells. This study demonstrates that drug resistance can be effectively reversed in human cisplatin-resistant lung and gastric cancer cells through delivery of siRNAs targeting EHZ2.

Overexpression of E2F1 in human gastric carcinoma is involved in anti-cancer drug resistance

Background

Routine chemotherapy often cannot achieve good therapeutic effects because of multidrug resistance (MDR). MDR is frequently caused by the elevated expression of the MDR1 gene encoding P-glycoprotein (P-gp). E2F1 is a frequently overexpressed protein in human tumor cells that increases the activity of the MDR1 promoter, resulting in higher P-gp levels. The upregulation of P-gp might contribute to the survival of tumor cells during chemotherapy. E2F1 confers anticancer drug resistance; however, we speculate whether E2F1 affects MDR through other pathways. This study investigated the possible involvement of E2F1 in anticancer drug resistance of gastric carcinoma in vitro and in vivo.

Methods

A cisplatin-resistant SGC7901/DDP gastric cancer cell line with stable overexpression of E2F1 was established. Protein expression levels of E2F1, MDR1, MRP, TAp73, GAX, ZEB1, and ZEB2 were detected by western blotting. The influence of overexpression of E2F1 on anticancer drug resistance was assessed by measuring IC50 of SGC7901/DDP cells to cisplatin, doxorubicin, and 5-fluorouracil, as well as the rate of doxorubicin efflux, apoptosis, and cell cycle progression detected by flow cytometry. We determined the in vivo effects of E2F1-overexpression on tumor size in nude mice, and apoptotic cells in tumor tissues were detected by deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling and hematoxylin and eosin staining.

Results

The SGC7901/DDP gastric cancer cell line stably overexpressing E2F1 exhibited significantly inhibited sensitivity to cisplatin, doxorubicin, and 5-fluorouracil. Flow cytometry confirmed that the percentage of apoptotic cells decreased after E2F1 upregulation, and that upregulation of E2F1 potentiated S phase arrest of the cell cycle. Furthermore, upregulation of E2F1 significantly decreased intracellular accumulation of doxorubicin. Western blot revealed that E2F1 upregulation suppressed expression of GAX, and increased the expression of MDR1, MRP, ZEB1, TAp73, and ZEB2.

Conclusions

Overexpression of E2F1 promotes the development of MDR in gastric carcinoma, suggesting that E2F1 may represent an efficacious target for gastric cancer therapy.

Tetramethylpyrazine suppresses transient oxygen-glucose deprivation-induced connexin32 expression and cell apoptosis via the ERK1/2 and p38 MAPK pathway in cultured hippocampal neurons

Tetramethylpyrazine (TMP) has been widely used in China as a drug for the treatment of various diseases. Recent studies have suggested that TMP has a protective effect on ischemic neuronal damage. However, the exact mechanism is still unclear. This study aims to investigate the mechanism of TMP mediated ischemic hippocampal neurons injury induced by oxygen-glucose deprivation (OGD). The effect of TMP on hippocampal neurons viability was detected by MTT assay, LDH release assay and apoptosis rate was measured by flow cytometry. TMP significantly suppressed neuron apoptosis in a concentration-dependent manner. TMP could significantly reduce the elevated levels of connexin32 (Cx32) induced by OGD. Knockdown of Cx32 by siRNA attenuated OGD injury. Moreover, our study showed that viability was increased in siRNA-Cx32-treated-neurons, and neuron apoptosis was suppressed by activating Bcl-2 expression and inhibiting Bax expression. Over expression of Cx32 could decrease neurons viability and increase LDH release. Furthermore, OGD increased phosphorylation of ERK1/2 and p38, whose inhibitors relieved the neuron injury and Cx32 up-regulation. Taken together, TMP can reverse the OGD-induced Cx32 expression and cell apoptosis via the ERK1/2 and p38 MAPK pathways.

Long noncoding RNA MRUL promotes ABCB1 expression in multidrug-resistant gastric cancer cell sublines

Multidrug resistance (MDR) is the most common cause of chemotherapy failure in gastric cancer (GC) treatment; however, the underlying molecular mechanisms remain elusive. Long noncoding RNAs (lncRNAs) can be involved in carcinogenesis, but the effects of lncRNAs on MDR are poorly understood. We show here that the lncRNA MRUL (MDR-related and upregulated lncRNA), located 400 kb downstream of ABCB1 (ATP-binding cassette, subfamily B, member 1), was significantly upregulated in two multidrug-resistant GC cell sublines, SGC7901/ADR and SGC7901/VCR. Furthermore, the relative expression levels of MRUL in GC tissues were negatively correlated with in vitro growth inhibition rates of GC specimens treated with chemotherapeutic drugs and indicated a poor prognosis for GC patients. MRUL knockdown in SGC7901/ADR and SGC7901/VCR cells led to increased rates of apoptosis, increased accumulation, and reduced doxorubicin (Adriamycin [ADR]) release in the presence of ADR or vincristine. Moreover, MRUL depletion reduced ABCB1 mRNA levels in a dose- and time-dependent manner. Heterologous luciferase reporter assays demonstrated that MRUL might positively affect ABCB1 expression in an orientation- and position-independent manner. Our findings indicate that MRUL promotes ABCB1 expression and is a potential target to reverse the MDR phenotype of GC MDR cell sublines.