Multidrug-resistant Human Cancer Research Articles

Potential applications of antofine and its synthetic derivatives in cancer therapy: structural and molecular insights.

Cancer is a major global health challenge, being the second leading cause of morbidity and mortality after cardiovascular disease. The growing economic burden and profound psychosocial impact on patients and their families make it urgent to find innovative and effective anticancer solutions. For this reason, interest in using natural compounds to develop new cancer treatments has grown. In this respect, antofine, an alkaloid class found in Apocynaceae, Lauraceae, and Moraceae family plants, exhibits promising biological properties, including anti-inflammatory, anticancer, antiviral, and antifungal activities. Several molecular mechanisms have been identified underlying antofine anti-cancerous effects, including the inhibition of nuclear factor κB (NF-κB) and AKT/mTOR signaling pathways, epigenetic inhibition of protein synthesis, ribosomal targeting, induction of apoptosis, inhibition of DNA synthesis, and cell cycle arrest. This study discusses the molecular structure, sources, photochemistry, and anticancer properties of antofine in relation to its structure-activity relationship and molecular targets. Then, examine in vitro and in vivo studies and analyze the mechanisms of action underpinning antofine efficacy against cancer cells. This review also discusses multidrug resistance in human cancer and the potential of antofine in this context. Safety and toxicity concerns are also addressed as well as current challenges in antofine research, including the need for clinical trials and bioavailability optimization. This review aims to provide comprehensive information for more effective natural compound-based cancer treatments.

Isolation and characterizations of multidrug-resistant human cancer cells by a biodegradable nano-sensor

Multidrug resistance (MDR) remains a significant challenge in cancer therapy, with inherent and acquired resistance distinct. While conventional drug selection processes enable the isolation of cancer cells with acquired multidrug resistance, identifying cancer cells with inherent drug resistance remains challenging. Herein, we proposed a molecular beacon (MB)-based strategy to identify and isolate the inherent MDR cancer cells. A lipid/PLGA core-shell nanoparticulate system (DNCP) was designed to deliver MB for intracellular MDR1 mRNA imaging. DNCP-MB – possess a surface potential of −8 mV and a size of 150 nm – demonstrated effective delivery of MB, remarkable selectivity towards the selected intracellular mRNA targets, and low cytotoxicity. Following DNCP transfection, fluorescence-activated cell sorting (FACS) was employed to differentiate MCF-7 cells into two distinct sub-populations: the Top 10 cells with a high level of MDR gene expression and the Bottom 10 cells with a low level of MDR gene expression, which represent inherent drug-resistant and non-drug-resistant cells, respectively. Intriguingly, we observed a positive correlation between elevated MDR1 mRNA expression and increased migration, enhanced proliferation rate, and tighter spheroid formation. Moreover, we conducted RNA sequencing analysis on the Top 10, Bottom 10, and MCF-7/ADR cells. The findings revealed a notable disparity in the gene ontology enrichment analysis of differentially expressed genes between the Top 10 and Bottom 10 cells when compared to the Bottom 10 and MCF-7/ADR cells. This novel approach provides a promising avenue for isolating inherent drug-resistant cells and holds significant potential in unraveling the mechanisms underlying inherent drug resistance.

Statistical optimization of environmental factors to produce the cytotoxic enniatins H, I and MK1688 against human multidrug resistance cancer cell lines.

The environmental conditions were optimized to produce the enniatin H, I, and MK1688 by Fusarium strain on cereal grain exhibiting anti-carcinogenic potential against MES-SA (human uterine sarcoma cell line), HCT15 (human colorectal carcinoma cancer cell line), and their multidrug resistance sublines. From the statistical optimization by response surface methodology, the optimal condition of independent variables affecting the response variables were 20.85°C (temperature), 46.85% (w/w, initial moisture content), and 18.42days (growth time) for ENN H; 23.31°C, 44.15% (w/w) and 17.23days for ENN I; 23.08°C, 43.97% (w/w) and 17.06days for ENN MK1688. In case of cytotoxic effects, ENNs significantly suppressed growth of cancer cell lines without multidrug resistance, and ENN I inhibited growth of cancer cell lines most strongly. These data will provide valuable point to produce the cyclic hexadepsipeptide exhibiting anti-carcinogenic potential from Fusarium strains.

Abstract 2846: The mitochondrial dynamics of breast cancer regulate P-glycoprotein expression

Abstract Multidrug efflux transporter ABCB1 (MDR1) encodes P-glycoprotein (P-gp), a well-known transporter that is believed to contribute to the development of multidrug resistance (MDR). Furthermore, P-gp plays an important role in drug disposition, pharmacokinetics, and drug development. Thus, P-gp transporter expression, function, and modulation of MDR in human cancers have been extensively studied. In spite of significant progress in understanding P-gp, ABCB1 regulation and its impact on clinical trials remain unclear. Through sequential exposure of SUM159PT to paclitaxel, we created a paclitaxel resistant triple negative breast cancer cell line SUM159PT-PAC200. We observed a significant increase in the phosphorylation of the mitochondrial fission protein dynamin related protein kinase 1 (Drp1) at Ser616 and its upstream kinase ERK1/2a of Drp1. Through the use of CRISPR-Cas9 technology, we knocked out the gene encoding Drp1 in PAC200. When Drp1 is genetically abated (PAC200 Drp1-/-), paclitaxel resistance is significantly reversed. It was also observed that clonogenicity under paclitaxel pressure was significantly decreased in both the PAC200/Drp1-/- line and the partial KO Drp1-/+ line, compared to the PAC200 line. Parallelly, a significant increase in the expression of P-gp transporters was also observed in the PAC200 cell line. As a surprise, genetically targeting Drp1 in PAC200 cells (i.e., PAC200 Drp1/KO) reduced P-gp expression to virtually undetectable levels. Until now, there has been no description of how Drp1 and P-gp are related. Furthermore, PAC200 Drp1/KO cells showed reduced proliferation, migration, and invasion potential, while their soft agar clonogenic capacities were almost nonexistent, suggesting that Drp1 plays a key role in breast cancer proliferation and dissemination. It appears that modulating or targeting Drp1 might be a useful strategy for modulating P-gp in the development and maintenance of the cancer's MDR phenotype, proliferation, and invasion. Understanding how mitochondrial dynamics determine the transactivation and coordination of drug-resistant P-gp phenotypes would make Drp1 an attractive molecular target for cancer treatment. Citation Format: David Terrero, Saloni Malla, Dayanidhi Raman, Jayachandra Babu, Amit Tiwari. The mitochondrial dynamics of breast cancer regulate P-glycoprotein expression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2846.

Salvianolic acid B suppresses hepatic fibrosis by inhibiting ceramide glucosyltransferase in hepatic stellate cells.

UDP-glucose ceramide glucosyltransferase (UGCG) is the first key enzyme in glycosphingolipid (GSL) metabolism that produces glucosylceramide (GlcCer). Increased UGCG synthesis is associated with cell proliferation, invasion and multidrug resistance in human cancers. In this study we investigated the role of UGCG in the pathogenesis of hepatic fibrosis. We first found that UGCG was over-expressed in fibrotic livers and activated hepatic stellate cells (HSCs). In human HSC-LX2 cells, inhibition of UGCG with PDMP or knockdown of UGCG suppressed the expression of the biomarkers of HSC activation (α-SMA and collagen I). Furthermore, pretreatment with PDMP (40 μM) impaired lysosomal homeostasis and blocked the process of autophagy, leading to activation of retinoic acid signaling pathway and accumulation of lipid droplets. After exploring the structure and key catalytic residues of UGCG in the activation of HSCs, we conducted virtual screening, molecular interaction and molecular docking experiments, and demonstrated salvianolic acid B (SAB) from the traditional Chinese medicine Salvia miltiorrhiza as an UGCG inhibitor with an IC50 value of 159 μM. In CCl4-induced mouse liver fibrosis, intraperitoneal administration of SAB (30 mg · kg-1 · d-1, for 4 weeks) significantly alleviated hepatic fibrogenesis by inhibiting the activation of HSCs and collagen deposition. In addition, SAB displayed better anti-inflammatory effects in CCl4-induced liver fibrosis. These results suggest that UGCG may represent a therapeutic target for liver fibrosis; SAB could act as an inhibitor of UGCG, which is expected to be a candidate drug for the treatment of liver fibrosis.

Structural insight into the binding pattern and interaction mechanism of chemotherapeutic agents with Sorcin by docking and molecular dynamic simulation

Sorcin (SOluble Resistance-related Calcium bInding proteiN) is a calcium binding protein that plays a key role in multidrug resistance (MDR) in human cancers. This study aimed at understanding the binding mechanism and structural basis for the interaction of structurally and functionally unrelated chemotherapeutic agent, namely doxorubicin, etoposide, omacetaxine mepesuccinate and paclitaxel with Sorcin by utilizing docking and molecular dynamic simulation approaches. The docking evaluation of etoposide, omacetaxine mepesuccinate and paclitaxel have shown a high affinity binding with Sorcin at the Ca2+-binding C-terminal domain (SCBD) in a comparable mode and affinity of binding to doxorubicin. Moreover, all of the docked compounds were shown to interact both hydrophilically and hydrophobically with the same residues within the active pocket which is located at interface of the Sorcin and collectively formed by EF5 loop, G helix and EF4 loop. However, the MD simulations revealed that the dynamics of Sorcin structure is different in the presence of the compounds when compared and contrasted to the Apo Sorcin, particularly in the first 25 ns, after which each system gained considerable structure stability. The difference in dynamics might be the outcome of high N and C-terminal flexibility that seem not to disturb compounds binding conformation but more likely is affecting chemical interaction network by breaking and establishing old and new hydrogen bonds, respectively. This detailed mechanistic understanding of different chemotherapeutic agents binding to Sorcin might be useful to open windows for designing and developing new inhibitors that are potentially capable of reversing the MDR in human cancers.

Decrease of ABCB1 protein expression and increase of G1 phase arrest induced by oleanolic acid in human multidrug-resistant cancer cells.

Oleanolic acid (OA) is a natural compound that can be found in a number of edible and medicinal plants and confers diverse biological actions. However, the direct target of OA in human tumor cells remains poorly understood, preventing its application in clinical and health settings. A previous study revealed that overexpression of caveolin-1 in human leukemia HL-60 cells can increase its sensitivity to OA. The present study aimed to investigate the effects of OA on the doxorubicin-resistant human breast cancer MCF-7 cell line (MCF-7/DOX), harringtonine-resistant human leukemia HL-60 cells (HL-60/HAR) and their corresponding parental cell lines. Western blotting was performed to measure protein expression levels, whilst Cell Counting Kit-8 (CCK-8) assays, cell cycle analysis (by flow cytometry) and apoptosis assays (with Annexin V/PI staining) were used to assess drug sensitivity. CCK-8 assay results suggested that MCF-7/DOX cells, which overexpress the caveolin-1 protein, have similar OA susceptibility to their parent line. In addition, sensitivity of MCF-7/DOX cells to OA was not augmented by knocking down caveolin-1 using RNA interference. HL-60/HAR cells exhibited a four-fold increased sensitivity to OA compared with that in their parental HL-60 cells according to CCK-8 assay. Both of the resistant cell lines exhibited higher numbers of cells at G1 phase arrest compared with those in their parent lines, as measured via flow cytometry. Treatment of both MCF-7 cell lines with 100 µM OA for 48 h induced apoptosis, with increased effects observed in resistant cells. However, no PARP-1 or caspase-3 cleavage was observed, with some positive Annexin V staining found after HL-60/HAR cells were treated with OA, suggesting that cell death occurred via non-classical apoptosis or through other cell death pathways. It was found that OA was not a substrate of ATP-binding cassette subfamily B member 1 (ABCB1) in drug-resistant cells, as indicated by the accumulation of rhodamine 123 assessed using flow cytometry. However, protein expression of ABCB1 in both of the resistant cell lines was significantly decreased after treatment with OA in a concentration-dependent manner. Collectively, these results suggest that OA could reduce ABCB1 protein expression and induce G1 phase arrest in multidrug-resistant cancer cells. These findings highlight the potential of OA for cancer therapy.

Metformin Derivative HL156A Reverses Multidrug Resistance by Inhibiting HOXC6/ERK1/2 Signaling in Multidrug-Resistant Human Cancer Cells.

Multidrug resistance is a significant clinical crisis in cancer treatment and has been linked to the cellular expression of multidrug efflux transporters. The aim of this study was to examine the effects and mechanisms of the metformin derivative HL156A on human multidrug resistance (MDR) cancer cells. Here, HL156A significantly suppressed cell growth and colony formation through G2/M phase cell cycle arrest in MDR cancer cells. HL156A also reduced the wound closure rate and cell migration and induced caspase-3-dependent apoptosis. We found that HL156A inhibited the expression of MDR1 by inhibiting the HOXC6-mediated ERK1/2 signaling pathway and increased the sensitivity to paclitaxel or doxorubicin in MDR cells. Furthermore, HL156A significantly inhibited angiogenesis in a chicken chorioallantoic membrane (CAM) assay. These results suggest the potential of the metformin derivative HL156A as a candidate therapeutic modality for the treatment of human multidrug-resistant cancers.

Licochalcone A Selectively Resensitizes ABCG2-Overexpressing Multidrug-Resistant Cancer Cells to Chemotherapeutic Drugs.

The overexpression of the ATP-binding cassette (ABC) transporter ABCG2 has been linked to clinical multidrug resistance in solid tumors and blood cancers, which remains a significant obstacle to successful cancer chemotherapy. For years, the potential modulatory effect of bioactive compounds derived from natural sources on ABCG2-mediated multidrug resistance has been investigated, as they are inherently well tolerated and offer a broad range of chemical scaffolds. Licochalcone A (LCA), a natural chalcone isolated from the root of Glycyrrhiza inflata, is known to possess a broad spectrum of biological and pharmacological activities, including pro-apoptotic and antiproliferative effects in various cancer cell lines. In this study, the chemosensitization effect of LCA was examined in ABCG2-overexpressing multidrug-resistant cancer cells. Experimental data demonstrated that LCA inhibits the drug transport function of ABCG2 and reverses ABCG2-mediated multidrug resistance in human multidrug-resistant cancer cell lines in a concentration-dependent manner. Results of LCA-stimulated ABCG2 ATPase activity and the in silico docking analysis of LCA to the inward-open conformation of human ABCG2 suggest that LCA binds ABCG2 in the transmembrane substrate-binding pocket. This study provides evidence that LCA should be further evaluated as a modulator of ABCG2 in drug combination therapy trials against ABCG2-expressing drug-resistant tumors.

Aged garlic extract and its constituent, S-allyl-L-cysteine, induce the apoptosis of neuroblastoma cancer cells due to mitochondrial membrane depolarization.

Aged garlic extract (AGE) has been demonstrated to have therapeutic properties in tumors; however its mechanisms of action have not yet been fully elucidated. A previous study revealed that AGE exerts an anti-proliferative effect on a panel of both sensitive [wild-type (WT)] and multidrug-resistant (MDR) human cancer cells. Following treatment of the cells with AGE, cytofluorimetric analysis revealed the occurrence of dose-dependent mitochondrial membrane depolarization (MMD). In this study, in order to further clarify the mechanisms of action of AGE, the effects of AGE on mitochondria isolated from rat liver mitochondria (RLM) were also examined. AGE induced an effect on the components of the electrochemical gradient (ΔµH+), mitochondrial membrane potential (ΔΨm) and mitochondrial electrochemical gradient (ΔpHm). The mitochondrial membrane dysfunctions of RLM induced by AGE, namely the decrease in both membrane potential and chemical gradient were associated with a higher oxidation of both the endogenous glutathione and pyridine nucleotide content. To confirm the anti-proliferative effects of AGE, experiments were performed on the human neuroblastoma (NB) cancer cells, SJ-N-KP and the MYCN-amplified IMR5 cells, using its derivative S-allyl-L-cysteine (SAC), with the aim of providing evidence of the anticancer activity of this compound and its possible molecular mechanism as regards the induction of cytotoxicity. Following treatment of the cells with SAC at 20 mM, cell viability was determined by MTT assay and apoptosis was detected by flow cytometry, using Annexin V-FITC labeling. The percentages of cells undergoing apoptosis was found to be 48.0% in the SJ-N-KP and 50.1% in the IMR5 cells. By cytofluorimetric analysis, it was suggested that the target of SAC are the mitochondria. Mitochondrial activity was examined by labeling the cells with the probe, 5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylimidacarbocyanine iodide (JC-1). Following treatment with SAC at 50 mM, both NB cell lines exhibited a marked increase in MMD. On the whole, the findings of this study indicate that both natural products, AGE and SAC, cause cytotoxicity to tumor cells via the induction of mitochondrial permeability transition (MPT).

Reversal of Multidrug Resistance in Human Colon Cancer and Human Leukemia Cells by Three Plant Extracts and Their Major Secondary Metabolites.

Background: We studied the effect of three plant extracts (Glycyrrhiza glabra, Paeonia lactiflora, Eriobotrya japonica) and six of their major secondary metabolites (glycyrrhizic acid, 18β glycyrrhetinic acid, liquiritigenin, isoliquiritigenin, paeoniflorin, ursolic acid) on the multidrug resistant human colon cancer cell line Caco-2 and human leukemia cell line CEM/ADR 5000 as compared to the corresponding sensitive cell line CCRF-CEM, and human colon cancer cells HCT-116, which do not over-express ATP-binding cassette (ABC) transporters. Methods: The cytotoxicity of single substances in sensitive and resistant cells was investigated by MTT assay. We also applied combinations of extracts or single compounds with the chemotherapeutic agent doxorubicin or doxorubicin plus the saponin digitonin. The intracellular retention of the ABC transporter substrates rhodamine 123 and calcein was examined by flow cytometry to explore the effect of the substances on the activity of ABC transporters P-glycoprotein and MRP1. Real-time PCR was applied to analyse the gene expression changes of ABCB1, ABCC1, caspase 3, caspase 8, AhR, CYP1A1, and GSTP1 in resistant cells under the treatment of the substances. Results: All the substances moderately inhibited cell growth in sensitive and resistant cells to some degree. Whereas ursolic acid showed IC50 of 14 and 22 µM in CEM/ADR 5000 and Caco-2 cells, respectively, glycyrrhizic acid and paeoniflorin were inactive with IC50 values above 400 μM. Except for liquiritigenin and isoliquiritigenin, all the other substances reversed MDR in CEM/ADR 5000 and Caco-2 cells to doxorubicin. Ue, ga, 18ga, and urs were powerful reversal agents. In CEM/ADR 5000 cells, high concentrations of all the substances, except Paeonia lactiflora extract, increased calcein or rhodamine 123 retention in a dose-dependent manner. In Caco-2 cells, all the substances, except liquiritigenin, retained rhodamine 123 in a dose-dependent manner. We also examined the effect of the plant secondary metabolite (PSM) panel on the expression of ABCB1, ABCC1, caspase 3, caspase 8, AhR, CYP1A1, and GSTP1 genes in MDR cells. Conclusions: The extracts and individual PSM could reverse MDR in CEM/ADR 5000 and Caco-2 cells, which overexpress ABC transporters, in two- and three-drug combinations. Most of the PSM also inhibited the activity of ABC transporters to some degree, albeit at high concentrations. Ue, ga, 18ga, and urs were identified as potential multidrug resistance (MDR) modulator candidates, which need to be characterized and validated in further studies.

Differential Sensitivities of Human Multidrug-resistant Cancer Cells to BIIB021 and Modulation of Hsp90 Inhibitors by NSAIDs and Niclosamide

Differential Sensitivities of Human Multidrug-resistant Cancer Cells to BIIB021 and Modulation of Hsp90 Inhibitors by NSAIDs and Niclosamide

Nitric oxide reverses drug resistance by inhibiting ATPase activity of p-glycoprotein in human multi-drug resistant cancer cells

BackgroundDevelopment of resistance to chemotherapy drugs is a significant problem in treating human malignancies in the clinic. Overexpression of drug efflux proteins, including P-170 glycoprotein (P-gp), an ATP-dependent efflux protein, is one of the main mechanisms responsible for multi-drug resistance (MDR). Because our previous studies have shown that nitric oxide (˙NO) or its related species inhibit the ATPase activities of topoisomerase II, we hypothesized that ˙NO should also inhibit the ATPase activity of P-gp and increase drug accumulation in MDR cells, causing a reversal of drug resistance. ResultsCytotoxicity and cellular accumulation studies showed that ˙NO significantly inhibited the ATPase activity of P-gp in isolated membranes and in NCI/ADR-RES tumor cells, causing an increase in drug accumulation and reversals of adriamycin and taxol resistance in the MDR cells. While ˙NO had no effects on topoisomerase II-induced, adriamycin-dependent DNA cleavage complex formation, it significantly inhibited adriamycin-induced DNA double-strand breaks. Electron spin resonance studies showed an increase in adriamycin-dependent hydroxyl radical formation in the presence of an NO-donor. ConclusionsThe reversal of drug resistance is due to inhibition of the ATPase activity by ˙NO, resulting in enhancement of the drug accumulation in the MDR cells. Furthermore, DNA damage was not responsible for this reversal of adriamycin resistance. However, formation of adriamycin-dependent toxic free radical species and subsequent cellular damage may be responsible for the increased cytotoxicity of adriamycin by ˙NO in NCI/ADR-RES cells. General significanceAppropriately designed NO donors would be ideal for the treatment of P-gp-overexpressing tumors in the clinic.

Abstract 4195: β-elemene inhibits the metastasis of multidrug-resistant gastric cancer cells through the Cbl-b-EGFR-ERK/Akt signaling pathway

Abstract Background/Aims: β-elemene, a Curcuma wenyujin plant extract, has been widely used as an adjuvant therapeutic agent in cancer treatment. The emergence of drug-resistant tumor cells is defined as multidrug resistance (MDR), and is one of the major ways cancer therapy can fail. Our previous study indicated that, compared to chemo-sensitive human gastric cancer cells, drug-resistant cells have a stronger ability for migration. The aim of this study was to explore the anti-metastasis effects and mechanism of β-elemene in multi-drug resistance human gastric cancer cells. Methods: A cell viability assay was used to assess the resistance of adriamycin-resistant human gastric cancer SGC7901 cells (SGC7901/ADR) and the cytotoxic effects of β-elemene on SGC7901/ADR cells. A wound healing assay and transwell assay were used to explore the anti-metastasis effects of β-elemene. Human matrix metalloproteinase (MMP) antibody array and Western blot analysis were used to explore the potential mechanism. A murine tumor metastasis assay was used to confirm the anti-metastasis effects in vivo. Immunohistochemistry analysis was performed to examine the expressions of related proteins in xenograft tumors. Results: At sub-lethal concentrations (1 μg/ml and 5 μg/ml), β-elemene significantly inhibited cell migration and invasion of SGC7901/ADR cells. The human MMP antibody array indicated that β-elemene could regulate almost all proteins of the MMP family, and changes of MMP-2 and MMP-9 were the most obvious. Western blotting showed an increase of E-cadherin and decrease of vimentin in β-elemene-treated cells. Downregulation of transcription factor ZEB1 and ZEB2 was also detected. Treatment of SGC7901/ADR cells with β-elemene led to downregulation of Akt, ERK, and EGFR phosphorylation, and significant upregulation of the E3 ubiquitin ligase, Cbl-b. Changes of these proteins were confirmed in xenograft tumors. Hematoxylin and eosin staining showed significantly decreased numbers of metastatic tumor colonies in the lungs of nude mice injected with SGC7901/ADR cells and β-elemene compared with those only injected with SGC7901/ADR cells. Conclusions: The results strongly suggest that β-elemene inhibits the metastasis of multidrug-resistant gastric cancer cells in vitro and in vivo by regulating the Cbl-b-EGFR-ERK/Akt signaling pathway. β-elemene may be a promising treatment for multidrug resistant human gastric cancer. Citation Format: Ruoxi Yu, Mingming Deng, Huicong Song, Dan Zou, Ling Xu, Xiujuan Qu, Yunpeng Liu, Yuee Teng, Xuejun Hu, Ye Zhang. β-elemene inhibits the metastasis of multidrug-resistant gastric cancer cells through the Cbl-b-EGFR-ERK/Akt signaling pathway [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4195.

The antioxidant, aged garlic extract, exerts cytotoxic effects on wild-type and multidrug-resistant human cancer cells by altering mitochondrial permeability

Aged garlic extract (AGE) has been shown to possess therapeutic properties in cancer; however its mechanisms of action are unclear. In this study, we demonstrate by MTT assay that AGE exerts an anti-proliferative effect on a panel of both sensitive and multidrug-resistant (MDR) human cancer cell lines and enhances the effects of hyperthermia (42˚C) on M14 melanoma cells. The evaluation of the mitochondrial activity in whole cancer cells treated with AGE, performed by cytofluorimetric analysis in the presence of the lipophilic cationic fluorochrome JC-1, revealed the occurrence of dose-dependent mitochondrial membrane depolarization. Membrane potential was measured by the TPP+ selective electrode. In order to shed light on its mechanisms of action, the effects of AGE on isolated rat liver mitochondria were also examined. In this regard, AGE induced a mitochondrial membrane hyperpolarization of approximately 15mV through a mechanism that was similar to that observed with the ionophores, nigericin or salinomycin, by activating an exchange between endogenous K+ with exogenous H+. The prolonged incubation of the mitochondria with AGE induced depolarization and matrix swelling, indicative of mitochondrial permeability transition induction that, however, occurs through a different mechanism from the well-known one. In particular, the transition pore opening induced by AGE was due to the rearrangement of the mitochondrial membranes following the increased activity of the K+/H+ exchanger. On the whole, the findings of this study indicate that AGE exerts cytotoxic effects on cancer cells by altering mitochondrial permeability. In particular, AGE in the mitochondria activates K+/H+ exchanger, causes oxidative stress and induces mitochondrial permeability transition(MPT).

Discovery of antitumor ursolic acid long-chain diamine derivatives as potent inhibitors of NF-κB

A series of inhibitors of NF-κB based on ursolic acid (UA) derivatives containing long-chain diamine moieties were designed and synthesized as well as evaluated the antitumor effects. These compounds exhibited significant inhibitory activity to the NF-κB with IC50 values at micromolar concentrations in A549 lung cancer cell line. Among them, compound 8c exerted potent activity against the test tumor cell lines including multidrug resistant human cancer lines, with the IC50 values ranged from 5.22 to 8.95 μM. Moreover, compound 8c successfully suppressed the migration of A549 cells. Related mechanism study indicated compound 8c caused cell cycle arrest at G1 phase and triggered apoptosis in A549 cells through blockage of NF-κB signalling pathway. Molecular docking study revealed that key interactions between 8c and the active site of NF-κB in which the bulky and strongly electrophilic group of long-chain diamine moieties were important for improving activity.

Chinese herbal medicine Euphorbia esula extract induces apoptosis and inhibits the proliferation, migration and invasion of multidrug resistant gastric carcinoma cells

This paper aims to study the effects of traditional Chinese medicine Euphorbia esula on multidrug resistant human gastric cancer cells in the cell proliferation, migration, invasion and apoptosis, and to study the apoptosis-inducing pathway. Different dilutions of Euphorbia esula extract were used to process human multidrug resistant gastric cancer SGC7901/ADR cells. Cell proliferation inhibition phenomenon was determined by MTT experiment. Nuclear morphological changes of apoptotic cells and apoptotic indexes were observed and determined by Hochest33528 staining followed with fluorescence microscope observing. Flow cytometry was used to detect cell apoptosis rate. Cell migration and invasion ability were observed and determined by Transwell method. Spectrophotometry was used to detect caspase-3 and caspase-9 enzyme activity. Western blotting was used to detect subcellular distribution of cytochrome c. The results showed that Euphorbia esula extract had obvious inhibition effect on proliferation of gastric cancer multidrug resistant SGC7901/ADR cells, which was time- and concentration-dependent. After processing multidrug resistant gastric cancer SGC7901/ADR cells with Euphorbia esula extract, the apoptotic index and apoptosis rate were significantly increased than those in the control group, which showed a time- and dose-dependent mode; but if a caspase inhibitor was added, apoptosis index was not obviously increased. Transwell method showed that migration and invasion ability of the Euphorbia esula extract-processed SGC7901/ADR cells dropped significantly. Spectrophotometry showed that in Euphorbia esula extract-processed SGC7901/ADR cells, caspase-3 and caspase-9 expression were increased, which had significant differences with the control group. Western blotting test showed that the distribution of cytochrome c decreased in mitochondria, while increased in the cytoplasm (i.e., cytochrome c escaped from mitochondria to the cytoplasm). In conclusion, Euphorbia esula extract could inhibit the proliferation, migration and invasion, and induce apoptosis in human gastric cancer multidrug resistant SGC7901/ADR cells; and cytochrome c, caspase-9 and caspase-3 might be involved in cell apoptosis induced by Euphorbia esula extract, suggesting endogenous or mitochondrial apoptotic pathway.

Full extract of Euphorbia esula reversed chemoresistance, inhibited cell migration/invasion, and induced apoptosis of multidrug-resistant SGC7901/VCR cells

Background: The plant Euphorbia esula has been used by ancient Chinese people to treat cancer and other ailments and is used by present doctors or folks as an assistant treatment for some kind of cancers, but the mode of action is unclear. Objective: To investigate the influence of E. esula full extract on chemoresistance, cell migration/invasion, and apoptosis of multidrug-resistant human stomach cancer cells. Materials and Methods: After treating multidrug-resistant human stomach cancer SGC7901/VCR cells with E. esula extract at varying concentrations, the inhibition of cell proliferation was detected using thiazolyl blue. Sensitivity to the chemotherapeutic drugs, adriamycin and paclitaxel, was evaluated using half maximal inhibitory concentration. Cell cycle progression was analyzed by flow cytometry. The inhibitions of cell migration and invasion were examined by Transwell method. The induction of apoptosis and the apoptotic rate were studied by electron microscopy and flow cytometry, respectively. Activation of caspase 3 enzyme was inspected by ultraviolet spectrophotometry. Results: E. esula extract could increase the sensitivity of SGC7901/VCR cells to the chemotherapeutic drugs, adriamycin and paclitaxel. The proliferation, migration, and invasion of SGC7901/VCR cells were significantly inhibited by E. esula extract (P < 0.01 compared with negative control), which showed time- and dose-dependent manners (P < 0.05 and P < 0.01, respectively). Cell cycle was arrest at the S phase. E. esula extract also induced apoptosis in SGC7901/VCR cells, and the apoptotic rate was increased significantly with drug concentration and with treatment time (P < 0.01 compared with negative control, P < 0.05 between concentrations and time points). E. esula extract upregulated enzymatic activity of caspase 3. Conclusion: E. esula extract could reverse SGC7901/VCR cell's resistance to chemotherapeutic drugs and could inhibit cell proliferation, migration, and invasion, interfere with cell cycle progression, and induce apoptosis in SGC7901/VCR cells. Abbreviations used: E. esula: Euphorbia Esula; FCS: fetal calf serum; IC50: half maximal inhibitory concentration; OD: optical density.

Curcumin Co-Treatment Sensitizes Multi-Drug Resistant Ht29 Colon Cancer Cell Line

Colorectal cancer has been confirmed to be the third most dreadful cancer across the world. The latest reports show that the colorectal cancer is increasing in India at a high rate due to food habits, particularly consuming the foods with high fat content. Chemotherapy has been considered as a potential treatment in the control of a wide range of cancers recently, such as gastrointestinal cancers and so on. The scientists are looking to come up with new drugs to treat cancer by regulating the carcinogenesis with minimal toxicity. Curcumin is a phytochemical extracted from turmeric. It is highly effective product of the rhizomes of Curcuma longa L. (Zingiberaceae). It is also considered as a valuable drug for chemotherapeutic treatments in cancer. In case of animal studies, it has been clearly mentioned that curcumin controls carcinogenesis in various other organs as well as colon. Curcumin exhibits the capability to act as anti-mutagenic, anti-inflammatory drug as well. It has also been confirmed that the P-gp expression regulation is carried out by curcumin by inhibiting the COX-2 expression. Also, it has been clearly stated that curcumin down-regulates NF-kB pathway in various cell lines like Colo 205 colon cancer cell line etc. Multi Drug Resistance (MDR) plays a key role in case of the cancer cells to exhibit the resistance against the cytotoxicity of various chemotherapeutic drugs. This type of characteristics in cancer cells is developed due to low levels of the chemotherapeutic drug accumulated inside the cells during repeated exposure to the drug, showing the over-expression of P-glycoprotein (MDR-1). P-glycoprotein, a transporter protein, allows the cells to expel the wide range of chemotherapeutic drugs. The latest reports show that COX-2 expression and P-gp expression possess strong correlation with each other. In this research study, we generated the Multi-Drug Resistant HT29 Human colon cancer cells by treating the cells with increasing concentrations of a chemotherapeutic drug namely Doxorubicin Hydrochloride (DOX) and further we estimated the intracellular drug concentration in treated live as well as dead cells with the help of Doxorubicin Accumulation Assay. Also, the cell morphology change was studied in HT29 cells after every 24 hours of the DOX treatment separately as well as curcumin co-treatment (DOX+Curcumin). The curcumin co-treatment was carried out to observe the effect of curcumin on multi-drug resistant HT29 colon cancer cells and further study can be extended to investigate the various inflammatory genes controlled by NFkB at mRNA and protein level as well as the levels of cytokines which may get down-regulated by treatment. This study will help to completely understand the mechanism of reducing the effect of Multidrug Resistance (a unique property of cancer) by curcumin in case of colon cancer.

Vitexin induces apoptosis by suppressing autophagy in multi-drug resistant colorectal cancer cells.

Cancer treatment is limited due to the diverse multidrug resistance acquired by cancer cells and the collateral damage caused to adjacent normal cells by chemotherapy. The flavonoid compound vitexin exhibits anti-oxidative, anti-inflammatory and anti-tumor activity. This study elucidated the antitumor effects of vitexin and its underlying mechanisms in a multi-drug resistant human colon cancer cell line (HCT-116DR), which exhibits higher levels of multidrug-resistant protein 1 (MDR1) expression as compared with its parental cell line (HCT-116). Here, we observed that vitexin suppressed MDR-1 expression and activity in HCT-116DR cells and showed cytotoxic effect in HCT-116DR cells by inhibiting autophagy and inducing apoptosis in a concentration-dependent manner. Additionally, vitexin treatment caused cleavage of caspase-9 and caspase-3, and upregulated the expression of the pro-apoptotic proteins, BID and Bax. Moreover, the expression of autophagy-related proteins, such as ATG5, Beclin-1 and LC3-II, was markedly reduced by vitexin treatment. Furthermore, in vivo experiments showed that vitexin induced apoptosis and suppressed tumor growth in HCT-116DR xenograft model. These results revealed that vitexin induced apoptosis through suppression of autophagy in vitro and in vivo and provide insight into the therapeutic potential of vitexin for the treatment of chemo-resistant colorectal cancer.