Preliminary evaluation of the potential role of β-elemene in reversing erlotinib-resistant human NSCLC A549/ER cells

Natural products reverse cancer multidrug resistance

Cancer stands as a prominent global cause of death. One of the key reasons why clinical tumor chemotherapy fails is multidrug resistance (MDR). In recent decades, accumulated studies have shown how Natural Product-Derived Compounds can reverse tumor MDR. Discovering novel potential modulators to reduce tumor MDR by Natural Product-Derived Compounds has become a popular research area across the globe. Numerous studies mainly focus on natural products including flavonoids, alkaloids, terpenoids, polyphenols and coumarins for their MDR modulatory activity. Natural products reverse MDR by regulating signaling pathways or the relevant expressed protein or gene. Here we perform a deep review of the previous achievements, recent advances in the development of natural products as a treatment for MDR. This review aims to provide some insights for the study of multidrug resistance of natural products.

Preliminary Study on Phytochemical Constituents and Biological Activities of Essential Oil from Myriactis nepalensis Less

In response to the need for novel therapeutic strategies to combat the development of microbial resistance, plant essential oils may represent a promising alternative source. This study set out to characterize the chemical composition and assess the antibacterial potential of Myriactis nepalensis Less. essential oil (MNEO). Essential oil isolated from M. nepalensis by hydrodistillation was analyzed using a GC–MS technique. The antibacterial properties of MNEO alone and combined with antibiotics (chloramphenicol and streptomycin) were tested via the disc diffusion, microbroth dilution, and checkerboard methods. MNEO was represented by oxygenated sesquiterpenes (60.3%) and sesquiterpene hydrocarbons (28.6%), with caryophyllene oxide, spathulenol, humulene epoxide II, β-elemene, neointermedeol, and β-caryophyllene as the main compounds. MNEO exhibited a strong antibacterial effect against Gram-positive bacteria, with MIC and MBC values of 0.039 mg/mL and 0.039–0.156 mg/mL, respectively, and synergistic effects were observed in both combinations with chloramphenicol and streptomycin. Furthermore, the antibiofilm and cytotoxic activities of MNEO were also evaluated. The crystal violet assay was used for quantification of Staphylococcus aureus biofilm formation, and an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay was conducted to determine cell viability. The results revealed MNEO could dose-dependently inhibit Staphylococcus aureus biofilm formation and possessed potential cytotoxic on both normal and cancer cells (IC50 values from 13.13 ± 1.90 to 35.22 ± 8.36 μg/mL). Overall, the results indicate that MNEO may have promising applications in the field of bacterial infections.

β-Elemene Promotes Apoptosis Induced by Hyperthermia via Inhibiting HSP70

Thermotherapy has been presented as a promising strategy to be used as an effective nonsurgical technique for colorectal carcinoma. Although this strategy presents several advantages, including low toxicity and high repeatability, thermotherapy often needs to be combined with other therapies because residual tumor cells that survive hyperthermal treatment often lead to relapse. In this study, we evaluated the effects of β-elemene, which has been proven to have the potential to reverse chemotherapy drug resistance, on promoting the antitumor effects of hyperthermia. β-elemene treatment significantly promoted apoptosis after 2 hours of hyperthermia treatment and blocked cell cycle phases at G1/G0. β-elemene also significantly decreased colony formation and tumor formation abilities after hyperthermia treatment. β-elemene treatment significantly decreased HSP70, but not HSP90 or HSP27, induced by hyperthermia treatment without disturbing HSP70 mRNA. It was also found that β-elemene decreased phosphorylated ERK1/2 induced by hyperthermia. Regain of HSP70 reversed β-elemene-mediated apoptosis, indicating that β-elemene may induce apoptosis by decreasing HSP70. Moreover, β-elemene treatment significantly decreased invasion capacity by decreasing the EMT, which was induced by hyperthermia treatment. Taken together, our results offer a potential strategy for CRC therapy via the combination of hyperthermia and β-elemene.

Preparation, characterization, pharmacokinetics and anticancer effects of PEGylated β-elemene liposomes

Objective: This study aimed to develop a new polyethylene glycol (PEG)ylated β-elemene liposome (PEG-Lipo-β-E) and evaluate its characterization, pharmacokinetics, antitumor effects and safety in vitro and in vivo.

Methods: The liposomes were prepared by ethanol injection and high-pressure micro-jet homogenization. Characterization of the liposomes was conducted, and drug content, entrapment efficiency (EE), in vitro release and stability were studied by ultra-fast liquid chromatography (UFLC) and a liquid surface method. Blood was drawn from rats to establish the pharmacokinetic parameters. The anticancer effect was evaluated in a KU-19-19 bladder cancer xenograft model. Histological analyses were performed to evaluate safety.

Results: The PEG-Lipo-β-E showed good stability and was characterized as 83.31 ± 0.181 nm in size, 0.279 ± 0.004 in polydispersity index (PDI), −21.4 ± 1.06 mV in zeta potential, 6.65 ± 0.02 in pH, 5.024 ± 0.107 mg/mL in β-elemene (β-E) content, and 95.53 ± 1.712% in average EE. The Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) indicated the formation of PEG-Lipo-β-E. Compared to elemene injection, PEG-Lipo-β-E demonstrated a 1.75-fold decrease in clearance, a 1.62-fold increase in half-life, and a 1.76-fold increase in area under the concentration-time curves (AUCs) from 0 hour to 1.5 hours (P < 0.05). PEG-Lipo-β-E also showed an enhanced anticancer effect in vivo. Histological analyses showed that there was no evidence of toxicity to the heart, kidney, liver, lung or spleen.

Conclusions: The present study demonstrates PEG-Lipo-β-E as a new formulation with ease of preparation, high EE, good stability, improved bioavailability and antitumor effects.

New Advances in the Research of Resistance to Neoadjuvant Chemotherapy in Breast Cancer

Breast cancer has an extremely high incidence in women, and its morbidity and mortality rank first among female tumors. With the increasing development of medicine today, the clinical application of neoadjuvant chemotherapy has brought new hope to the treatment of breast cancer. Although the efficacy of neoadjuvant chemotherapy has been confirmed, drug resistance is one of the main reasons for its treatment failure, contributing to the difficulty in the treatment of breast cancer. This article focuses on multiple mechanisms of action and expounds a series of recent research advances that mediate drug resistance in breast cancer cells. Drug metabolizing enzymes can mediate a catalytic reaction to inactivate chemotherapeutic drugs and develop drug resistance. The drug efflux system can reduce the drug concentration in breast cancer cells. The combination of glutathione detoxification system and platinum drugs can cause breast cancer cells to be insensitive to drugs. Changes in drug targets have led to poorer efficacy of HER2 receptor inhibitors. Moreover, autophagy, epithelial–mesenchymal transition, and tumor microenvironment can all contribute to the development of resistance in breast cancer cells. Based on the relevant research on the existing drug resistance mechanism, the current treatment plan for reversing the resistance of breast cancer to neoadjuvant chemotherapy is explored, and the potential drug targets are analyzed, aiming to provide a new idea and strategy to reverse the resistance of neoadjuvant chemotherapy drugs in breast cancer.

Beta-Elemene Reduces the Malignancy of Non-Small Cell Lung Cancer by Enhancing C3orf21 Expression

Background

Beta-elemene has potent anti-tumor effect, but its anti-tumor mechanism remains unclear. Chromosome 3 open reading frame 21 (C3orf21) acts as a tumor suppressor. This study tested whether the anti-tumor effect of beta-elemene was associated with modulating C3orf21 expression in non-small cell lung cancer (NSCLC).

Materials and Methods

The impact of beta-elemene on C3orf21 expression in NSCLC cells was quantified. The stable C3orf21 silencing A549 and over-expressing PC-9 cells were established and their effects on the beta-elemene-attenuated proliferation, wound healing and invasion of NSCLC cells as well as the expression of key regulators and signal events were determined.

Results

Beta-elemene significantly up-regulated C3orf21 expression in NSCLC cells. Beta-elemene treatment significantly attenuated the proliferation, wound healing and invasion of NSCLC cells, which were significantly mitigated by C3orf21 silencing, but enhanced by C3orf21 over-expression. Similar patterns of beta-elemene-modulated cyclinD1, c-Myc, COX2, MMP2, MMP9, VEGF, PTEN and Notch1 expression were detected in NSCLC cells.

Conclusions

Such data indicated that beta-elemene treatment attenuated the malignancy of NSCLC cells by up-regulating C3orf21 expression. Our findings may provide new mechanisms underlying the pharmacological action of beta-elemene.

Metabolic Reprogramming of Chemoresistant Cancer Cells and the Potential Significance of Metabolic Regulation in the Reversal of Cancer Chemoresistance

Metabolic reprogramming is one of the hallmarks of tumors. Alterations of cellular metabolism not only contribute to tumor development, but also mediate the resistance of tumor cells to antitumor drugs. The metabolic response of tumor cells to various chemotherapy drugs can be analyzed by metabolomics. Although cancer cells have experienced metabolic reprogramming, the metabolism of drug resistant cancer cells has been further modified. Metabolic adaptations of drug resistant cells to chemotherapeutics involve redox, lipid metabolism, bioenergetics, glycolysis, polyamine synthesis and so on. The proposed metabolic mechanisms of drug resistance include the increase of glucose and glutamine demand, active pathways of glutaminolysis and glycolysis, promotion of NADPH from the pentose phosphate pathway, adaptive mitochondrial reprogramming, activation of fatty acid oxidation, and up-regulation of ornithine decarboxylase for polyamine production. Several genes are associated with metabolic reprogramming and drug resistance. Intervening regulatory points described above or targeting key genes in several important metabolic pathways may restore cell sensitivity to chemotherapy. This paper reviews the metabolic changes of tumor cells during the development of chemoresistance and discusses the potential of reversing chemoresistance by metabolic regulation.

Co-Encapsulation of Mitoxantrone and β-Elemene in Solid Lipid Nanoparticles to Overcome Multidrug Resistance in Leukemia

Multidrug resistance (MDR) due to P-glycoprotein (P-gp) overexpression is a major obstacle to successful leukemia chemotherapy. The combination of anticancer chemotherapy with a chemosensitizer of P-gp inhibitor is promising to overcome MDR, generate synergistic effects, and maximize the treatment effect. Herein, we co-encapsulated a chemotherapeutic drug of mitoxantrone (MTO) and a P-gp inhibitor of β-elemene (βE) in solid lipid nanoparticles (MTO/βE-SLNs) for reversing MDR in leukemia. The MTO/βE-SLNs with about 120 nm particle size possessed good colloidal stability and sustained release behavior. For the cellular uptake study, doxorubicin (DOX) was used as a fluorescence probe to construct SLNs. The results revealed that MTO/βE-SLNs could be effectively internalized by both K562/DOX and K562 cells through the pathway of caveolate-mediated endocytosis. Under the optimized combination ratio of MTO and βE, the in vitro cytotoxicity study indicated that MTO/βE-SLNs showed a better antitumor efficacy in both K562/DOX and K562 cells than other MTO formulations. The enhanced cytotoxicity of MTO/βE-SLNs was due to the increased cellular uptake and blockage of intracellular ATP production and P-gp efflux by βE. More importantly, the in vivo studies revealed that MTO/βE-SLNs could significantly prolong the circulation time and increase plasma half-life of both MTO and βE, accumulate into tumor and exhibit a much higher anti-leukemia effect with MDR than other MTO formulations. These findings suggest MTO/βE-SLNs as a potential combined therapeutic strategy for overcoming MDR in leukemia.

Lung cancer combination therapy: doxorubicin and β-elemene co-loaded, pH-sensitive nanostructured lipid carriers

Purpose: Co-delivery of drugs to achieve the synergistic anticancer effect is a promising strategy for lung cancer therapy. The purpose of this research is to develop a doxorubicin (DOX) and β-elemene (ELE) co-loaded, pH-sensitive nanostructured lipid carriers (DOX/ELE Hyd NLCs).

Methods: In this study, DOX/ELE Hyd NLCs were produced by a hot homogenization and ultrasonication method and used for lung cancer treatment. In vitro and in vivo efficiency as well as toxicity of the system was evaluated on lung cancer cell lines and lung tumor-bearing mice.

Results: DOX/ELE Hyd NLCs had a particle size of 190 nm, with a PDI lower than 0.2. DOX/ELE Hyd NLCs exhibited a significantly enhanced cytotoxicity (drug concentration causing 50% inhibition was 7.86 μg/mL), synergy antitumor effect (combination index lower than 1), and profound tumor inhibition ability (tumor inhibition ratio of 82.9%) compared with the non pH-responsive NLCs and single-drug-loaded NLCs.

Conclusion: Since the synergistic effect of the drugs was found in this system, it would have great potential to inhibit lung tumor cells and tumor growth.