Modulation Of P-glycoprotein Expression Research Articles

Study on the reversal of epileptic drug resistance by tetramethylpyrazine in combination with carbamazepine through modulation of P-Glycoprotein expression in rat brain microvessel endothelial cell.

The purpose of this study was to detect the changes of P-Glycoprotein (P-GP) expression in rat brain microvessel endothelial cell line RBE4 after the action of Tetramethylpyrazine (TMP) on Carbamazepine (CBZ), so as to clarify the potential mechanism of TMP combined with CBZ against intractable epilepsy drug resistance. The RBE4 cell line was utilized for in vitro analysis. Cells were divided into control, CBZ, and CBZ-TMP group. The expression of P-GP was assessed using Western blot and reverse transcription polymerase chain reaction (RT-PCR). Intracellular concentration of CBZ was measured through high-performance liquid chromatography (HPLC). The differential expression of mRNA was evaluated by RNA sequencing. The intracellular concentration of CBZ in the CBZ-TMP group was significantly higher than that in other groups. The expression of P-GP in the CBZ group was significantly higher than that in the control group, while in the CBZ&TMP group, it was significantly lower than that in the other groups. Comparative analysis also revealed some differentially expressed genes. Compared with the CBZ group, FAM106A, SLC3A2, TENM2, etc. were upregulated most significantly in the CBZ&TMP group. ZBTB10, WDR7, STARD13, etc. were downregulated most significantly. Results suggest that TMP increases the intracellular concentration of CBZ, downregulates the expression of P-GP increased by CBZ, and modulates related cellular metabolism and signaling pathways, thus reversing the drug resistance mechanism of intractable epilepsy, providing a theoretical basis for the combination of traditional Chinese medicine and antiepileptic drugs.

Galectin-1 confers resistance to doxorubicin in hepatocellular carcinoma cells through modulation of P-glycoprotein expression

Galectin-1 (GAL1), a β-galactoside-binding protein abundantly expressed in the tumor microenvironment, has emerged as a key mechanism of chemoresistance developed by different tumors. Although increased expression of GAL1 is a hallmark of hepatocellular carcinoma (HCC) progression, aggressiveness and metastasis, limited information is available on the role of this endogenous lectin in HCC resistance to chemotherapy. Moreover, the precise mechanisms underlying this effect are uncertain. HCC has evolved different mechanisms of resistance to chemotherapy including those involving the P-glycoprotein (P-gp), an ATP-dependent drug efflux pump, which controls intracellular drug concentration. Here, we investigated the molecular mechanism underlying GAL1-mediated chemoresistance in HCC cells, particularly the involvement of P-gp in this effect. Our results show that GAL1 protected HepG2 cells from doxorubicin (DOX)- and sorafenib-induced cell death in vitro. Accordingly, GAL1-overexpressing HepG2 cells generated DOX-resistant tumors in vivo. High expression of GAL1 in HepG2 cells reduced intracellular accumulation of DOX likely by increasing P-gp protein expression rather than altering its membrane localization. GAL1-mediated increase of P-gp expression involved activation of the phosphatidylinositol-3 kinase (PI3K) signaling pathway. Moreover, ‘loss-of-function’ experiments revealed that P-gp mediates GAL1-driven resistance to DOX, but not to sorafenib, in HepG2 cells. Conversely, in PLC/PRF/5 cells, P-gp protein expression was undetectable and GAL1 did not control resistance to DOX or sorafenib, supporting the critical role of P-gp in mediating GAL1 effects. Collectively, our findings suggest that GAL1 confers chemoresistance in HCC through mechanisms involving modulation of P-gp, thus emphasizing the role of this lectin as a potential therapeutic target in HCC.

Modulation of P-glycoprotein Expression and Function under Disease States in Rats and Humans

Modulation of P-glycoprotein Expression and Function under Disease States in Rats and Humans

Modulation of P-glycoprotein expression by triptolide in adriamycin-resistant K562/A02 cells

Multidrug resistance is a serious obstacle encountered in leukemia treatment. Previous studies have found drug resistance in human leukemia is mainly associated with overexpression of the multidrug resistance gene 1 (MDR1). The aim of the present study was to investigate the modulation of P-glycoprotein expression by triptolide in adriamycin-resistant K562/A02 cells. The reverse effects of triptolide on drug resistance in K562/A02 cells were assessed by 3-[4,5-dimethylthiazol-2-yl]-2, 5-diphenyl-tetrazolium bromide (MTT) assay. The percentage of apoptotic cells was obtained from annexin V/fluorescein isothiocyanate (FITC) and propridium iodide (PI) double-staining. The effects of triptolide on P-glycoprotein activity were evaluated by measuring intracellular adriamycin accumulation. The expression of P-glycoprotein was determined by flow cytometry. A luciferase reporter gene assay was used to detect the transcriptional activity of the MDR1 promoter. Results revealed that triptolide decreased the degree of resistance of K562/A02 cells, and significantly inhibited P-glycoprotein expression and drug-transport function, and increased the accumulation of adriamycin in K562/A02 cells as measured by flow cytometry. A luciferase reporter gene assay demonstrated that triptolide was capable of inhibiting the transcriptional activity of the MDR1 promoter. Triptolide may effectively reverse the adriamycin resistance in K562/A02 cells via modulation of the P-glycoprotein expression and by increasing intracellular adriamycin accumulation.

Influencing Oral Prednisolone Absorption in Beagle Dogs by Modulation of P-glycoprotein Expression in the Intestinal Tract

Influencing Oral Prednisolone Absorption in Beagle Dogs by Modulation of P-glycoprotein Expression in the Intestinal Tract

PKD2 mediates multi-drug resistance in breast cancer cells through modulation of P-glycoprotein expression

Multi-drug resistance (MDR) represents a major obstacle for chemotherapeutic treatment of a wide variety of human cancers. Increased expression of drug efflux pumps, such as the P-glycoprotein (P-gp) have been linked to development of MDR. Herein, we have identified protein kinase D isoform 2 (PKD2) as an important regulator of MDR and P-gp expression in paclitaxel-treated breast cancer cell lines. PKD2 was expressed with the highest phosphorylated activation status in the MDA-MB-231 cell line. MDA-MB-231 cells were also found to exhibit the highest level of resistance to an array of chemotherapeutic drugs. To further characterize the relationship between PKD2 activation and MDR, we next focused on the effects of the chemotherapeutic agent paclitaxel in MDA-MB-231 cells. Treatment with paclitaxel was shown to induce both PKD2 phosphorylation and P-gp expression in a time-dependent manner. Importantly, shRNA-mediated knockdown of PKD2 in MDA-MB-231 cells resulted in a significant decrease in resistance to paclitaxel, evident as significant decreases in both the IC50 value and the resistance index (RI). Concurrent with the decrease in drug resistance, paclitaxel-induced expression of P-gp was also significantly reduced in PKD knockdown cells. These results indicate that PKD2 is required for paclitaxel-induced MDR and expression of P-gp. Therefore, modulation of PKD2 activity represents an attractive therapeutic strategy for improvement of the clinical effectiveness of chemotherapy.

Abstract 2260: Modulation of P-glycoprotein expression by a novel nutrient mixture in multidrug-resistant human uterine sarcoma cell line MES-SA/Dx5 but not in drug-sensitive MES-SA cell line

Abstract Introduction: We have characterized a nutrient mixture containing lysine, proline, ascorbic acid and green tea extract as a novel antineoplastic agent with a broad spectrum of antitumor activity against a number of cancer cell lines. Objective: We investigated the effect of NM on modulation of P-glycoprotein (Pgp) in the drug-resistant human uterine sarcoma cell line MES-SA/Dx5 and compared it with the effect on drug-sensitive cell line MES-SA. In addition we also studied the effect of NM on MMP expression and Rhodamine-123 accumulation and efflux. Material and Methods: Human drug insensitive uterine sarcoma cell line MES-SA/Dx5 and drug sensitive cell line MES-SA (ATCC) were grown in RPMI 1640 medium supplemented with fetal bovine serum and antibiotics. At near confluence, the cells were tested with NM at 0, 50, 100, 250, 500 and 1000 mcg/ml, in triplicate at each dose. Cell proliferation was evaluated by MTT assay, MMPs by gelatinase zymography, and Pgp expression by Western blot and immunodetection using FITC-conjugated antibody and rhodamine-123 (Rh-123) accumulation and efflux assays. Results: NM exhibited antiproliferative effect on MES-SA/Dx5, by 20% at 50 and 100 mcg/ml and by 40% at 25, 500 and 1000 mcg/ml, whereas in MES-SA cell line, NM showed dose-response toxicity of 40% at 50 and 30% at 1000 mcg/ml. In both cell lines, zymography demonstrated a band corresponding to MMP-2 in normal cells and MMP-9 with PMA treatment. Both MMPs showed dose-response inhibition by NM. NM treatment also showed diminished dose-dependent Pgp expression by MES-SA/Dx5 cell line by Western blot and by immunodetection, whereas MES-SA did not exhibit Pgp by Western blot or by immunostaining. NM enhanced the accumulation and efflux of Pgp substrate Rh-123 in MES-SA/Dx5 uterine sarcoma cell line but not in the drug-sensitive cell line MES-SA. Conclusions: In summary, this study demonstrated that Pgp is modulated by NM, which may be an attractive potential agent for therapeutic use in cancer treatment Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2260.

Modulation of P-glycoprotein expression and function by curcumin in multidrug-resistant human KB cells

Multidrug resistance (MDR) is a phenomenon that is often associated with decreased intracellular drug accumulation in the tumor cells of a patient, resulting from enhanced drug efflux. It is often related to the overexpression of P-glycoprotein (Pgp) on the surface of tumor cells, thereby reducing drug cytotoxicity. In this study, curcumin was tested for its potential ability to modulate the expression and function of Pgp in the multidrug-resistant human cervical carcinoma cell line KB-V1. Western blot analysis and reverse transcription–polymerase chain reaction (RT–PCR) showed that treatment with 1, 5, and 10 μM curcumin for up to 72 hr was able to significantly lower Pgp expression in KB-V1 cells. Curcumin (1–10 μM) decreased Pgp expression in a concentration-dependent manner and was also found to have the same effect on MDR1 mRNA levels. The effect of curcumin on Pgp function was demonstrated by rhodamine 123 (Rh123) accumulation and efflux in Pgp-expressing KB-V1 cells. Curcumin increased Rh123 accumulation in a concentration-dependent manner (1–55 μM) and inhibited the efflux of Rh123 from these cells, but did not affect the efflux of Rh123 from the wild-type drug-sensitive KB-3-1 cells. Treatment of drug-resistant KB-V1 cells with curcumin increased their sensitivity to vinblastine, which was consistent with an increased intracellular accumulation of Rh123. In addition, curcumin inhibited verapamil-stimulated ATPase activity and the photoaffinity labeling of Pgp with the prazosin analog [ 125 I ]iodoarylazidoprazosin in a concentration-dependent manner, demonstrating that curcumin interacts directly with the transporter. Thus, curcumin seems to be able to modulate the in vitro expression and function of Pgp in multidrug-resistant human KB-V1 cells. In summary, this study describes the duel modulation of MDR1 expression and Pgp function by the phytochemical curcumin, which may be an attractive new agent for the chemosensitization of cancer cells.

Modulation of P-glycoprotein expression by cytochrome P450 3A inducers in male and female rat livers

A strong overlap between P-glycoprotein (Pgp) and cytochrome P450 3A (CYP3A) substrates and modulators has been reported. To test the hypothesis that CYP3A and Pgp are coordinately regulated, we examined the effects of known inducers of CYP3A (triacetyloleandomycin, rifampicin, dexamethasone, pregnenolone 16α-carbonitrile) on Pgp expression in rat liver. We also investigated the gender-specific expression of Pgp and compared its response to dexamethasone between male and female rats. In male rats, western blot analyses showed that rifampicin and dexamethasone caused 50% and 5-fold increases in Pgp levels, respectively. RNase protection assays using gene-specific probes for the three Pgp isoforms revealed a 3-fold increase in mdr2 mRNA levels after dexamethasone administration and a 2-fold increase following rifampicin treatment. Triacetyloleandomycin and pregnenolone 16α-carbonitrile had no effect on Pgp expression and mRNA levels. We also observed that the basal level of Pgp was 40% lower in male rats than in females and that mdr2 mRNA levels in male rats were one-half those in females. As opposed to the results in male rats, dexamethasone reduced Pgp expression by approximately 60% and caused a 30% decrease in mdr2 mRNA levels in female rats. Mdr1a was not affected and mdr1b was not detected in female or male rats. We conclude that, at the dosage regimen used, CYP3A and Pgp responses to CYP3A inducers are regulated independently in rat liver. In addition, this study shows that Pgp expression and regulation are gender specific.

Synergism between Gamma Interferon and Doxorubicin in a Human MDR Colon Adenocarcinoma Cell Line

Recent interest in cancer therapy derives from the ability of interferons to synergistically increase the activity of chemotherapeutic agents. To understand the biological basis of this synergism we evaluated the effects of human recombinant IFN-gamma on the expression of the mdr1 gene and on the cellular growth of a human colon adenocarcinoma cell line (LoVo) and its MDR subline (LoVo/Dx) after coincubation with doxorubicin. Treatment with IFN-gamma showed unchanged levels of MDR1-glycoprotein, no perturbation on cell cycle distribution and a significant reduction of colony formation in both lines (P < 0.05) starting from 100 U/ml. A synergistic effect was observed in the LoVo/Dx cell line when doxorubicin was added after exposure to 0.1-10 U/ml of IFN-gamma. Our data indicate that the effects of IFN-gamma, independent from action on cell proliferation and from modulation of p-glycoprotein expression, are a cause of the synergistic activity between this lymphokine and conventional chemotherapeutic agents such as doxorubicin.