Reversal of P-glycoprotein-mediated multidrug resistance in vitro by milbemycin compounds in adriamycin-resistant human breast carcinoma (MCF-7/adr) cells

Repositioning of Antiparasitic Drugs for Tumor Treatment

Drug repositioning is a strategy for identifying new antitumor drugs; this strategy allows existing and approved clinical drugs to be innovatively repurposed to treat tumors. Based on the similarities between parasitic diseases and cancer, recent studies aimed to investigate the efficacy of existing antiparasitic drugs in cancer. In this review, we selected two antihelminthic drugs (macrolides and benzimidazoles) and two antiprotozoal drugs (artemisinin and its derivatives, and quinolines) and summarized the research progresses made to date on the role of these drugs in cancer. Overall, these drugs regulate tumor growth via multiple targets, pathways, and modes of action. These antiparasitic drugs are good candidates for comprehensive, in-depth analyses of tumor occurrence and development. In-depth studies may improve the current tumor diagnoses and treatment regimens. However, for clinical application, current investigations are still insufficient, warranting more comprehensive analyses.

Evaluation of anticancer activities of Poria cocos ethanol extract in breast cancer: In vivo and in vitro, identification and mechanism

ETHNOPHARMACOLOGICAL RELEVANCE

Poria cocos Wolf (P. cocos), a well-known traditional East-Asian medicinal and edible fungus, is one of the most important components in Chinese medicine formulas like "Guizhi fuling wan" to treat hyperplasia of mammary glands and breast cancer.

AIMING OF STUDY

In this study, we attempted to verify the anticancer efficacy of the ethanol extract of P. cocos (PC) on the breast cancer as well as to investigate its most active compound and its underlying molecular mechanism in vivo and in vitro.

MATERIALS AND METHODS

The key anti-cancer components were separated and purified through chromatography and identified by spectral analyses. The in vivo anti-breast cancer efficacy and side effects of PC were evaluated in BALB/c nude mice that have been subcutaneously injected with breast cancer cells MDA-MB-231. Cytotoxicity, apoptosis and cell cycle arrest of PC were evaluated in vitro by cell viability assays and flow cytometry. The protein levels were examined via western blotting.

RESULTS

Pachymic acid (PA), separated and identified as the most active compound, induced the significant cytotoxicity on breast cancer cells MDA-MB-231(IC₅₀ value, 2.13 ± 0.24 μg/mL) and was not active against the normal breast epithelium cells MCF-10A. The in vivo experiment revealed that PC could significantly inhibit the tumor development and the final mean tumor weight of the mice in the PC group (0.51 ± 0.12g) was significantly lower than that in the model group (1.22 ± 0.45g). Notably, compared to the first-line anticancer drug cisplatin, PC showed less side effects on the function of the vital organs and the muscle strength of the mice. Among in vitro study, PC significantly inhibited the cell growth of MDA-MB-231 by inducing cell apoptosis and cell cycle arrested at G₀/G₁ phase in a dose-dependent manner. The expression of cell cycle-associated cyclin D1, cyclin E, CDK2, and CDK4 were downregulated, while p53 and p21 expression were upregulated following the PA treatment. In addition, PA downregulated the apoptotic regulator Bcl-2, increased the expression of pro-apoptotic protein Bax, and promoted the release of cytochrome c and the activation of cleaved caspase-3, -9 and caspase -8 via mitochondria-mediated and death receptor-mediated signaling pathways.

CONCLUSION

This study verified the anticancer efficacy of PC on breast cancer in vivo and in vitro through induction of cell apoptosis and G₀/G₁ cell cycle arrest. The data also suggested that PA could be developed as an efficacious agent for breast cancer treatment with less side effects.

A milbemycin compound isolated from Streptomyces Sp. FJS31-2 with cytotoxicity and reversal of cisplatin resistance activity in A549/DDP cells

Streptomyces Sp FJS31-2 is a strain isolated from special habitat soils in the early stage of our laboratory for producing a new type of halogenated type II polyketide antibiotic with good anti-MRSA activity. In this experiment, a variety of chromatographic and spectroscopic methods was used to isolate and identify a milbemycin compound VM48130 from the ethyl acetate extract of the fermentation products. To investigate its bioactivity, Cell Counting Kit-8 (CCK-8) assay was used to test the cytotoxic activity of the compound against a variety of cancer cells (human liver cancer cell line MHCC97H and SK-Hep1, human nasopharyngeal carcinoma cell line CNE1, mouse melanoma cell line B16, human colon cancer cell line LOVO, human lung adenocarcinoma cell line A549) and normal cells (human bronchial epithelial cell line 16HBE, human normal liver cell line L02, human nasopharyngeal epithelial cell line NP69). The results showed that the compound had significant cytotoxic activity against the above cancer cells, and the IC₅₀ values were 21.96 ± 1.45, 22.18 ± 0.55, 19.42 ± 0.71, 18.61 ± 1.68, 18.62 ± 0.67, 18.52 ± 0.64 μM, respectively. Furthermore, the CCK-8 method was used to evaluate the compound's reversal of cisplatin resistance in multidrug resistant cisplatin-resistant human lung adenocarcinoma (A549/DDP) cells. The results indicated that when the compound concentration was 0.5 μM, the reversal fold (RF) reached 6.25 and showed a dose-dependent effect. At 5 μM, the RF reached 8.35, which was approximately equivalent to the reversal effect of the positive drug verapamil at the same concentration. The expression of MDR1, MRP1, LRP, MAST1 resistance genes and the corresponding proteins were analyzed by quantitative RT-PCR and Western blot assay, and found that the compound could significantly down-regulate the expression of these genes and proteins. These results indicated that VM48130 had the potential of being a lead compound for the treatment or adjuvant treatment of cancer.

Moxidectin inhibits glioma cell viability by inducing G0/G1 cell cycle arrest and apoptosis

Moxidectin (MOX), a broad‑spectrum antiparasitic agent, belongs to the milbemycin family and is similar to avermectins in terms of its chemical structure. Previous research has revealed that milbemycins, including MOX, may potentially function as effective multidrug resistance agents. In the present study, the impact of MOX on the viability of glioma cells was examined by MTT and colony formation assay, and the molecular mechanisms underlying MOX‑mediated glioma cell apoptosis were explored by using flow cytometry and apoptosis rates. The results demonstrated that MOX exerts an inhibitory effect on glioma cell viability and colony formations in vitro and xenograft growth in vivo and is not active against normal cells. Additionally, as shown by western blot assay, it was demonstrated that MOX arrests the cell cycle at the G0/G1 phase by downregulating the expression levels of cyclin‑dependent kinase (CDK)2, CDK4, CDK6, cyclin D1 and cyclin E. Furthermore, it was revealed that MOX is able to induce cell apoptosis by increasing the Bcl‑2‑associated X protein/B‑cell lymphoma 2 ratio and activating the caspase‑3/‑9 cascade. In conclusion, these results suggest that MOX may inhibit the viability of glioma cells by inducing cell apoptosis and cell cycle arrest, and may be able to function as a potent and promising agent in the treatment of glioma.

Consecutive salinomycin treatment reduces doxorubicin resistance of breast tumor cells by diminishing drug efflux pump expression and activity

Chemoresistance is a major challenge for the successful therapy of breast cancer. The discovery of salinomycin as an anticancer stem cell drug provides progress in overcoming chemoresistance. However, it remains to be elucidated whether salinomycin treatment is able to sensitize cancer cells to chemotherapeutic drugs. In the present study, we consecutively treated epithelial MCF-7 and BT-474 breast cancer cells as well as mesenchymal MDA-MB 231 and MDA-MB 436 cells with salinomycin, and analyzed the gene expression of the two prominent multiple drug resistance (MDR) genes, MDR1 and BCRP1. We found that repeated treatment with salinomycin generated resistance against this drug in all cell lines and increased the chemosensitivity towards doxorubicin. Drug efflux pump gene expression and pump activity of MDR1 and BCRP1 were downregulated in almost all cell lines, except for MDR1 in the MDA-MB 231 cells. Consequently, the intracellular doxorubicin accumulation was increased compared to the respective parental cells. Our findings suggest a novel treatment option for MDR tumors by sensitizing these tumors via salinomycin pretreatment.

Essential oil from Zanthoxylum bungeanum Maxim. and its main components used as transdermal penetration enhancers: a comparative study

Our previous studies had confirmed that the essential oil from Zanthoxylum bungeanum Maxim. (Z. bungeanum oil) could effectively enhance the percutaneous permeation of drug molecules as a natural transdermal penetration enhancer. The aim of the present study is to investigate and compare the skin penetration enhancement effect of Z. bungeanum oil and its main components on traditional Chinese medicine (TCM) active components. Toxicities of Z. bungeanum oil and three selected terpene compounds (terpinen-4-ol, 1,8-cineole, and limonene) in epidermal keratinocytes (HaCaT) and dermal fibroblast (CCC-ESF-1) cell lines were measured using an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Five model drugs in TCM external preparations, namely osthole (OT), tetramethylpyrazine (TMP), ferulic acid (FA), puerarin (PR), and geniposide (GP), which were selected based on their lipophilicity denoted by logKo/w, were tested using in vitro permeation studies in which vertical Franz diffusion cells and rat abdominal skin were employed. The secondary structure changes of skin stratum corneum (SC) and drug thermodynamic activities were investigated to understand their mechanisms of action using Fourier transform infrared (FTIR) spectroscopy and saturation solubility studies, respectively. It was found that Z. bungeanum oil showed lower toxicities in both HaCaT cells and CCC-ESF-1 cells compared with three terpene compounds used alone. The enhancement permeation capacities by all tested agents were in the following increasing order: terpinen-4-ol≈1,8-cineole Collapse

Key Words

• Essential oil
• Fourier transform infrared (FTIR) spectroscopy
• HaCaT
• Limonene
• Penetration enhancer
• Zanthoxylum bungeanum Maxim.

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MESH Headings

• Administration, Cutaneous
• Animals
• In Vitro Techniques
• Male
• Oils, Volatile/chemistry
• Oils, Volatile/pharmacology
• Plant Oils/chemistry
• Plant Oils/pharmacology
• Rats
• Rats, Sprague-Dawley
• Skin Absorption/drug effects
• Skin Absorption/physiology
• Terpenes/analysis
• Terpenes/chemistry
• Zanthoxylum/chemistry

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Affiliation(s)

Yi Lan
Hui Li
Yan-yan Chen
Ye-wen Zhang
Na Liu
Qing Zhang
Qing Wu †E-mail:

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Cytotoxicity and enhancement activity of essential oil from Zanthoxylum bungeanum Maxim. as a natural transdermal penetration enhancer

The aim of this present study is to investigate the effect of Zanthoxylum bungeanum oil (essential oil from Z. bungeanum Maxim.) on cytotoxicity and the transdermal permeation of 5-fluorouracil and indomethacin. The cytotoxicity of Z. bungeanum oil on dermal fibroblasts and epidermal keratinocytes was studied using an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. The rat skin was employed to determine the percutaneous penetration enhancement effect of Z. bungeanum oil on hydrophilic and lipophilic model drugs, i.e., 5-fluorouracil and indomethacin. The secondary structure changes of the rat stratum corneum (SC) were determined using attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), and saturated solubilities and SC/vehicle partition coefficients of two model drugs with and without Z. bungeanum oil were also measured to understand its related mechanisms of action. It was found that the half maximal inhibitory concentration (IC50) values of Z. bungeanum oil were significantly lower in HaCaT and CCC-ESF-1 cell lines compared to the well-established and standard penetration enhancer Azone. The Z. bungeanum oil at various concentrations effectively facilitated the percutaneous penetration of two model drugs across the rat skin. In addition, the mechanisms of permeation enhancement by Z. bungeanum oil could be explained with saturated solubility, SC/vehicle partition coefficient, and secondary structure changes of SC.

Icaritin reverses multidrug resistance of HepG2/ADR human hepatoma cells via downregulation of MDR1 and P‑glycoprotein expression

Multidrug resistance (MDR) of tumor cells is a serious obstacle encountered in cancer treatment. In the current study a multiple drug‑resistant HepG2/adriamycin (HepG2/ADR) cell line was established and its MDR was characterized. Icaritin, an active ingredient isolated from the medical plant Herba Epimedium, was observed to reverse MDR in the present model. Icaritin significantly increased the intracellular accumulation of ADR and decreased the expression of the MDR1 gene in HepG2/ADR cells compared with drug‑sensitive HepG2 cells. In addition, the present results showed that icaritin may significantly downregulate the expression of P‑glycoprotein. These results indicate that icaritin is a novel and potent MDR reversal agent and may be a promising drug for tumor chemotherapy.

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

In this article, reversal activities of Euphorbia factor L1 (EFL1) against ABCB1-mediated multidrug resistance (MDR) and apoptosis sensitization in K562/ADR cells are reported. EFL1 decreased the IC50 values of anticancer agents in K562/ADR cells over-expressing ABCB1. However, EFL1 did not affect the IC50 values of anticancer agents in sensitive K562 cells. Additionally, EFL1 increased the intracellular accumulation of rhodamine 123 and doxorubicin in K562/ADR cells without affecting their accumulation in K562 cells. Furthermore, EFL1 sensitized the apoptosis triggered by vincristine in K562/ADR cells via mitochondrial pathway, as confirmed by Annexin V-FITC/PI detection and western blot. At the same time, EFL1 did not influence the apoptosis induced by vincristine in K562 cells. Western blot results showed that EFL1 did not affect the phosphorylation level of AKT and ERK in K562 and K562/ADR cells. Finally, EFL1 did not down-regulate protein expression of ABCB1.

X-ray structure analysis of a solid solution of milbemycins A3 and A4

Milbemycins A3 and A4 are pharmaceutically and agriculturally useful macrolides isolated from Streptomyces species. The molecular structures of the title compounds were unambiguously established by a single crystal X-ray analysis of the solid solution of both compounds. The crystals present trigonal system, space group P32 with Z = 3, unit cell dimensions: a = 12.2211(4), c = 17.5372(7) Å; V = 2268.4(1) Å(3), μ = 0.082 mm(- 1); d = 1.183 g cm(- 3). An interesting system of intramolecular hydrogen bonds and weak intermolecular CH…O type hydrogen bond was observed in the solid state.

Reversal of multidrug resistance by morning glory resin glycosides in human breast cancer cells

Reversal of multidrug resistance (MDR) by thirty resin glycosides from the morning glory family (Convolvulaceae) was evaluated in vinblastine-resistant human breast carcinoma cells (MCF-7/Vin). The effects of these amphipathic compounds on the cytotoxicity and P-glycoprotein (P-gp)-mediated MDR were estimated with the sulforhodamine B colorimetric assay. Active noncytotoxic compounds exerted a potentiation effect of vinblastine susceptibility by 1- to over 1906-fold at tested concentrations of 5 and 25 μg/mL. Murucoidin V (1) enhanced vinblastine activity 255-fold when incorporated at 25 μg/mL and also, based on flow cytometry, significantly increased the intracellular accumulation of rhodamine 123 with the use of reserpine as a positive control for a MDR reversal agent. Incubation of MCF-7/Vin cells with 1 caused an increase in uptake and notably lowered the efflux rate of rhodamine 123. Decreased expression of P-glycoprotein by compound 1 was detected by immunofluorescence flow cytometry after incubation with an anti-P-gp monoclonal antibody. These results suggest that resin glycosides represent potential efflux pump inhibitors for overcoming MDR in cancer therapy.

Reversal effect of Tween-20 on multidrug resistance in tumor cells in vitro

Multidrug resistance (MDR) is a major barrier for chemotherapy of many cancers. Non-ionic surfactants have great potential to reverse the MDR by preventing onset or delay progression of the carcinogenic process. However, the role of Tween-20 in the development of MDR remains unknown. The aim of this study was to explore the reversal effect and potential mechanism of Tween-20 on tumor cells in vitro. Alamar Blue assay was used to examine the reversal index of Tween-20 to vincristine (VCR), doxorubicin (DOX) and 5-fluorouracil (5-FU) in KBv200, HepG2/R and Bel-7402/5-FU, respectively. Morphological change was determined by Gimsa and Hoechst 33258 staining. The acumulation of DOX was confirmed by spectrofluorimetric assay. Cell cycle analysis was performed using flow cytometry. The mRNA and protein expression levels of MDR were assessed by semiquantitative RT-PCR and dot blot, respectively. The results showed that Tween-20 at concentrations of 0.0025%, 0.005%, 0.01% had little cytotoxicity. When combined with the cancer drugs, it significantly promoted the sensitivity of MDR cells. Fluorescence staining confirmed that the percentage of apoptotic cell increased when combined with Tween-20. This notion was further supported by the observation that Tween-20 treatment potentiated VIN-induced G2/M arrest of the cell cycle. Furthermore, Tween-20 treatment increased significantly intracellular accumulation of DOX. RT-PCR and dot blot revealed that Tween-20 could downregulate the expression of MDR and P-glycoprotein. Low concentrations of Tween-20 can efficiently reverse the multidrug resistance phenotype by enhancing accumulation of the anticancer drugs. The potential mechanism may be via inhibiting the multidrug-resistant gene expression.

Reversal effects of two new milbemycin compounds on multidrug resistance in MCF-7/adr cells in vitro

Development of agents to overcome multidrug resistance (MDR) is important in cancer chemotherapy, and the overexpression of P-glycoprotein (P-gp) is one of the major mechanisms of MDR. In this paper, we evaluated the effects of two new milbemycin compounds, milbemycin β(14) and secomilbemycin D, isolated from fermentation broth of S. bingchenggensis on reversing MDR of adriamycin-resistant human breast carcinoma (MCF-7/adr) cells. We observed that the both milbemycins (5 μM) showed strong potency to increase adriamycin cytotoxicity toward MCF-7/adr cells with reversal fold (RF) of 13.5 and 10.59, respectively. In addition, the mechanisms of milbemycins on reversing P-gp-mediated MDR demonstrated that they significantly increased the accumulations of adriamycin and Rh123 via inhibiting P-gp efflux in MCF-7/adr cells. Furthermore, the results also revealed that milbemycin β(14) and secomilbemycin D could regulate down the expression of P-gp, but not affect the expression of MDR1 gene. In conclusion, our observations suggest that the two new milbemycin compounds probably represent the promising agents for reversing MDR in cancer therapy.