Regulation of hepatic P-gp expression and activity by genistein in rats

Study Models of Drug-Drug Interactions Involving P-Glycoprotein: The Potential Benefit of P-Glycoprotein Modulation at the Kidney and Intestinal Levels

P-glycoprotein (P-gp) is a crucial membrane transporter situated on the cell's apical surface, being responsible for eliminating xenobiotics and endobiotics. P-gp modulators are compounds that can directly or indirectly affect this protein, leading to changes in its expression and function. These modulators can act as inhibitors, inducers, or activators, potentially causing drug-drug interactions (DDIs). This comprehensive review explores diverse models and techniques used to assess drug-induced P-gp modulation. We cover several approaches, including in silico, in vitro, ex vivo, and in vivo methods, with their respective strengths and limitations. Additionally, we explore the therapeutic implications of DDIs involving P-gp, with a special focus on the renal and intestinal elimination of P-gp substrates. This involves enhancing the removal of toxic substances from proximal tubular epithelial cells into the urine or increasing the transport of compounds from enterocytes into the intestinal lumen, thereby facilitating their excretion in the feces. A better understanding of these interactions, and of the distinct techniques applied for their study, will be of utmost importance for optimizing drug therapy, consequently minimizing drug-induced adverse and toxic effects.

Impact of tectoridin on the pharmacokinetics of florfenicol via targeting cytochrome P450 and P-glycoprotein of rats

Belamcanda chinensis (L.) DC, commonly used with florfenicol in Chinese veterinary clinics for respiratory tract infections, contains the major effective isoflavone, tectoridin (TEC). This study aimed to investigate the impact of TEC co-administration on the pharmacokinetics of florfenicol in vivo.Male rats received oral TEC (50 mg/kg BW) or sterile water for seven days, followed by a single oral dose of florfenicol (25 mg/kg BW) on the 8th day. Non-compartmental methods analysed the pharmacokinetics of florfenicol, while real-time reverse transcription polymerase chain reaction (RT-PCR), Western blot, and immunohistochemical analyses measured expression levels of cytochrome P450 (CYP) isoforms in the liver and P-glycoprotein (P-gp) in the jejunum.TEC significantly decreased florfenicol's AUC(0-∞), MRT(0-∞), t1/2z, Vz/F, and Cmax by 24.75%, 18.43%, 55.47%, 43.05%, and 19.48%, while increasing CLz/F by 33.33%. TEC also up-regulated hepatic CYP1A2 and CYP3A1 mRNA expression, as well as intestinal MDR1, by 1.39-fold, 1.85-fold, and 1.65-fold. This coincided with a respective increase in protein expression by 1.37-fold, 1.39-fold, and 1.43-fold.These findings suggest that TEC-induced alterations in the pharmacokinetics of florfenicol may be attributed to increased CYP and P-gp expression. Further investigations are warranted to understand the implications of these findings on the clinical effectiveness of florfenicol in veterinary practice.

Bitter taste signaling in cancer

Pharmacoresistance of cancer cells to many drugs used in chemotherapy remains a major challenge for the treatment of cancer. Multidrug resistance transporters, especially ATP-binding cassette (ABC) transporters, are a major cause of cancer drug resistance since they translocate a broad range of drug compounds across the cell membrane, extruding them out of the cells. The regulation of ABC transporters by bitter taste receptors (TAS2Rs), which might be activated by specific bitter tasting compounds, was described in several types of cells/organs, becoming a potential target for cancer therapy. TAS2Rs expression has been reported in many organs and several types of cancer, like breast, ovarian, prostate, and colorectal cancers, where their activation was shown to be involved in various biological actions (cell survival, apoptosis, molecular transport, among others). Moreover, many TAS2Rs' ligands, such as flavonoids and alkaloids, with well-recognized beneficial properties, including several anticancer effects, have been reported as potential adjuvants in cancer therapies. In this review, we discuss the potential therapeutic role of TAS2Rs and bitter tasting compounds in different types of cancer as a possible way to circumvent chemoresistance.

Indole-3-propionic Acid Attenuates HI-Related Blood-Brain Barrier Injury in Neonatal Rats by Modulating the PXR Signaling Pathway

The blood-brain barrier (BBB) is an important physiological barrier of the human body contributing to maintaining brain homeostasis and normal function. Hypoxic-ischemic (HI)-related brain injury is one of the main causes of neonatal acute morbidity and chronic disability. The previous research of our group confirmed that there was serious BBB destruction during HI brain injury. However, at present, the protection strategy of BBB is very limited, and further research on the protection mechanism is warranted. Indole-3-propionic acid (IPA) is a bacterial metabolism with anti-inflammatory and antioxidant properties, having neuroprotective effects and protective effects on the mucosal barrier. However, the role of IPA in BBB is not clear. In this research, we demonstrated the protective effect of IPA on BBB disruption from HI brain injury and hypothesized that it involves the amelioration of inflammation, oxidative stress, and MMP activation, thereby inhibiting apoptosis of rat brain microvascular endothelial cells (rBMECs). We demonstrated that expression levels of several inflammatory markers, including iNOS, TNF-α, IL-6, and IL-1β, were significantly increased from HI damage or OGD injury. However, IPA treatment inhibited the increase significantly. Moreover, we demonstrated that IPA reduced intracellular ROS levels and MMP activation in rBMECs from OGD injury. Further research on the underlying detailed molecular mechanisms suggested that IPA attenuates inflammation by inhibiting NF-κB signaling. Finally, we investigated the mechanism of the relationship between PXR activation and NF-κB inhibition. The results suggested overexpression of PXR in rBMECs could significantly counteract the decrease of junction proteins and downregulate the increased p-IκB-α and p-NF-κB from OGD injury. However, the protective effects of IPA were reversed by antagonists of the PXR. Taken together, IPA might mitigate HI-induced damage of the BBB and the protective effect may be exerted through modulating the PXR signaling pathway.

The critical role of nanoparticle sizes in the interactions between gold nanoparticles and ABC transporters in zebrafish embryos

Despite the increasing evidences for adenosine triphosphate-binding cassette (ABC transporters)-mediated efflux of nanoparticles, the universality of these phenomena and the determining factors for the process remained to be clarified. This paper aimed to systemically investigate the role of nanoparticle size in the interactions between adenosine triphosphate-binding cassette (ABC transporters) and gold nanoparticles (AuNPs, 3 nm, 19 nm, and 84 nm, named as Au-3, Au-19, and Au-84) in zebrafish embryos. The results showed that all the three AuNPs induced significant toxicity as reflected by delayed hatching of embryos, decreased glutathione (GSH) contents, and increased reactive oxygen species (ROS) levels. Under the hindrance of embryo chorions, smaller AuNPs could more easily accumulate in the embryos, causing higher toxicity. Addition of transporter inhibitors enhanced the accumulation and toxicity of Au-3 and Au-19, and these nanoparticles induced the expressions of abcc2 and abcb4, indicating a fact that Au-3 and Au-19 were the potential substrates of ABC transporters, but these phenomena were barely found for Au-84. On the contrary, Au-84 suppressed the gene expressions of various ABC transporters like abcc1, abcg5, and abcg8. With specific suppressors, transcription factors like nuclear factor-erythroid 2-related factor-2 (Nrf2) and pregnane X receptor (Pxr) were found to be important in the induction of ABC transporters by AuNPs. After all, these results revealed a vital role of nanoparticle sizes in the interactions between ABC transporters and AuNPs in zebrafish embryos, and the critical size could be around 19 nm. Such information would be beneficial in assessing the environmental risk of nanoparticles, as well as their interactions with other chemical toxicants.

Effects of Sulforaphane-Induced Cell Death upon Repeated Passage of Either P-Glycoprotein-Negative or P-Glycoprotein-Positive L1210 Cell Variants

The expression of the membrane ABCB1 transporter in neoplastic cells is one of the most common causes of reduced sensitivity to chemotherapy. In our previous study, we investigated the effect of a single culture of ABCB1-negative (S) and ABCB1-positive variants of L1210 cells (R and T) in the presence of sulforaphane (SFN). We demonstrated that SFN induces the onset of autophagy more markedly in S cells than in R or T cells. In the current study, we focused on the effect of the repeated culture of S, R and T cells in SFN-containing media. The repeated cultures increased the onset of autophagy compared to the simple culture, mainly in S cells and to a lesser extent in R and T cells, as indicated by changes in the cellular content of 16 and 18 kDa fragments of LC3B protein or changes in the specific staining of cells with monodansylcadaverine. We conclude that SFN affects ABCB1-negative S cells more than ABCB1-positive R and T cells during repeated culturing. Changes in cell sensitivity to SFN appear to be related to the expression of genes for cell-cycle checkpoints, such as cyclins and cyclin-dependent kinases.

Potential Pharmacokinetic Effect of Chicken Xenobiotic Receptor Activator on Sulfadiazine: Involvement of P-glycoprotein Induction

Studies on pharmacokinetic drug−drug interactions have highlighted the importance of P-glycoprotein (P-gp) because of its involvement in substrate drug transport. This study aimed to investigate the role of chicken xenobiotic receptor (CXR) in the regulation of P-gp and its influences on pharmacokinetics of P-gp substrate sulfadiazine. ALAS1 and CYP2C45, the prototypical target genes of CXR, were used as a positive indicator for CXR activation in this study. Results show that ABCB1 gene expression was upregulated, and transporter activity was increased when exposed to the CXR activator metyrapone. Using ectopic expression techniques and RNA interference to manipulate the cellular CXR status, we confirmed that ABCB1 gene regulation depends on CXR. In vivo experiments showed that metyrapone induced ABCB1 in the liver, kidney, duodenum, jejunum and ileum of chickens. In addition, metyrapone significantly changed the pharmacokinetic behavior of orally administered sulfadiazine, with a Cmax (8.01 vs. 9.61 μg/mL, p < 0.05) and AUC0-t (31.46 vs. 45.59 h·mg/L, p < 0.01), as well as a higher T1/2λ (2.42 vs.1.67 h, p < 0.05), Cl/F (0.62 vs. 0.43 L/h/kg, p < 0.01) and Vz/F (2.16 vs.1.03 L/kg, p < 0.01). Together, our data suggest that CXR is involved in the regulation of P-gp, and, consequently, the CXR activator can affect, at least in part, the pharmacokinetic behavior of orally administered sulfadiazine.

Strategies and Mechanism in Reversing Intestinal Drug Efflux in Oral Drug Delivery

Efflux transporters distributed at the apical side of human intestinal epithelial cells actively transport drugs from the enterocytes to the intestinal lumen, which could lead to extremely poor absorption of drugs by oral administration. Typical intestinal efflux transporters involved in oral drug absorption process mainly include P-glycoprotein (P-gp), multidrug resistance proteins (MRPs) and breast cancer resistance protein (BCRP). Drug efflux is one of the most important factors resulting in poor absorption of oral drugs. Caco-2 monolayer and everted gut sac are sued to accurately measure drug efflux in vitro. To reverse intestinal drug efflux and improve absorption of oral drugs, a great deal of functional amphiphilic excipients and inhibitors with the function of suppressing efflux transporters activity are generalized in this review. In addition, different strategies of reducing intestinal drugs efflux such as silencing transporters and the application of excipients and inhibitors are introduced. Ultimately, various nano-formulations of improving oral drug absorption by inhibiting intestinal drug efflux are discussed. In conclusion, this review has significant reference for overcoming intestinal drug efflux and improving oral drug absorption.

Oxidative stress-mediated up-regulation of ABC transporters in lung cancer cells

This paper aimed to evaluate the role of oxidative stress in the regulation of ABC transporters in human lung cancer (A549) cells facing substrate (doxorubicin, DOX) and non-substrate (ethanol, ETH and hydrogen peroxide, HP) chemicals. After 24-h treatment, all the chemicals caused significant cytotoxicity as reflected by the reduction in cell viability and the increase in reactive oxygen species (ROS) levels. Depending on the rescuing effects of ROS scavenger including glutathione (GSH) and Vitamin C (VC), the toxicity dependence on oxidative stress were found to be HP>ETH>DOX. Addition of transporter inhibitors significantly enhanced the ROS levels and death-inducing effects of chemicals, indicating the universal detoxification function of ABC transporters. At moderate ROS levels (about 3-4 folds of control levels, caused by 10 μM DOX, 400 mM ETH, and 400 μM HP), all the three chemicals induced the gene expressions and activities of ABC transporters, but these values decreased at too high ROS levels (8.36 folds of control levels) caused by HP at LC₅₀ (800 μM). Such induction could be attenuated by GSH and KCZ, and was completely abolished by 50 μM KCZ, indicating an important role of oxidative stress and pregnane X receptor (PXR) in the induction of ABC transporters. After all, this paper revealed a critical role of oxidative stress in the modulation of ABC transporters by either substrate or non-substrate chemicals during 24-h treatment. Such information should be beneficial for overcoming ABC transporter-mediated multidrug resistance (MDR). This article is protected by copyright. All rights reserved.

Induction of P-glycoprotein expression and activity by prolactin in female rat liver

AIM

P-glycoprotein (P-gp) plays a critical role in the excretion of xenobiotics into bile. Previous studies have demonstrated that prolactin (PRL) regulates biotransformation and bile salt transport. Here we investigate whether the capability of the liver to transport xenobiotics into bile is altered in hyperprolactinemic states studying the modulation of hepatic P-gp by PRL.

METHODS

We used lactating post-partum rats (PP), as a model of physiological hyperprolactinemia (15 and 21 days after delivery: PP15 and PP21, respectively), and ovariectomized rats treated with PRL (300 μg/day, 7 days, via osmotic minipumps, OVX + PRL). Hepatic P-gp expression and activity were evaluated by western blotting and using rhodamine 123 as substrate in vivo, respectively. Since P-gp is encoded by Mdr1a and Mdr1b in rodents, we quantified their expression by qPCR in primary hepatocyte cultures exposed to 0.1 μg/ml of PRL after 12 h. To further study the mechanism of hepatic P-gp modulation by PRL, hepatocytes were pretreated with actinomycin D and then exposed to PRL (0.1 μg/ml) for 12 h.

KEY FINDINGS

We found increased hepatic P-gp protein expression and activity in PP15 and OVX + PRL. Also, a significant increase in Mdr1a and Mdr1b mRNA levels was observed in primary hepatocyte cultures exposed to PRL, pointing out the hormone direct action. Actinomycin D prevented these increases, confirming a transcriptional up-regulation of P-gp by PRL.

SIGNIFICANCE

These findings suggest the possibility of an increased biliary excretion of xenobiotics substrates of P-gp, including therapeutic agents, affecting their pharmaco/toxicokinetics in hyperprolactinemic situations.

Evaluation of the Influence of Zhenwu Tang on the Pharmacokinetics of Digoxin in Rats Using HPLC-MS/MS

Digoxin (DIG) is a positive inotropic drug with a narrow therapeutic window that is used in the clinic for heart failure. The active efflux transporter of DIG, P-glycoprotein (P-gp), mediates DIG absorption and excretion in rats and humans. Up to date, several studies have shown that the ginger and Poria extracts in Zhenwu Tang (ZWT) affect P-gp transport activity. This study aimed to explore the effects of ZWT on the tissue distribution and pharmacokinetics of DIG in rats. The deionized water or ZWT (18.75 g/kg) was orally administered to male Sprague–Dawley rats once a day for 14 days as a pretreatment. On day 15, 1 hour after receiving deionized water or ZWT, the rats were given the solution of DIG at 0.045 mg/kg dose, and the collection of blood samples was carried out from the fundus vein or excised tissues at various time points. HPLC-MS/MS was used for the determination of the DIG concentrations in the plasma and the tissues under investigation. The pharmacokinetic interactions between DIG and ZWT after oral coadministration in rats revealed significant reductions in DIG C_max and AUC_0-∞, as well as significant increases in T_1/2 and MRT_0-∞. When coadministered with ZWT, the DIG concentration in four of the investigated tissues statistically decreased at different time points except for the stomach. This study found that combining DIG with ZWT reduced not only DIG plasma exposure but also DIG accumulation in tissues (heart, liver, lungs, and kidneys). The findings of our study could help to improve the drug's validity and safety in clinical applications and provide a pharmacological basis for the combined use of DIG and ZWT.

Anti-inflammatory and antioxidative effects of genistein in a model of spinal cord injury in rats

Background

Neurological damage from spinal cord injury (SCI) is a result of primary mechanical injury and secondary damage from oxidative stress and neuroinflammation. Although genistein has been shown to have potent antioxidant and anti-inflammatory effects in studies of brain injury, its effect on secondary damage in SCI has remained unknown.

Objective

To determine effects of genistein in a model of SCI in rats.

Methods

We divided 21 rats evenly into 3 groups, a control group, in which only a laminectomy was performed; a trauma group in which SCI was induced; and a genistein group in which genistein was administered subcutaneously after SCI. The rats were assessed using a Basso-Beattie and Bresnahan functional score at the 12th hour and on the 1st, 3rd, 5th, and 7th days. Biochemical analyses were conducted at the same time points to determine the serum levels of catalase, ischemia-modified albumin (IMA), disulfide (SS), total thiol (TT), native thiol (NT), disulfide/total thiol (SS/TT), and native thiol/total thiol (NT/TT). Total oxidant and antioxidant capacity, and oxidative stress index were determined in spinal cord tissue obtained on the 7th day together with immunohistochemistry for cyclooxygenase-2 levels.

Result

Catalase activity on the 7th day was significantly (P = 0.001) higher in the genistein-treated rats than in other groups, and IMA levels became stable earlier (3rd day) in the genistein group. SS values were significantly (P = 0.004) lower in the genistein group. NT/TT ratio were significantly (P = 0.049) higher in the genistein-treated rats on the 7th day.

Conclusion

Genistein has antioxidant, anti-inflammatory, and protective effects in a model of SCI in rats and warrants further study.

Protective effect of genistein pre-treatment on paraquat hepatotoxicity in rats

Paraquat (PQ), an herbicide widely used in agriculture, is considered a highly toxic compound. In hepatocytes, P-glycoprotein (P-gp/Abcb1) is a canalicular transporter involved in PQ extrusion from the cell. Previously, we demonstrated that genistein (GNT) induces P-gp in rat liver. In this study, the protective role of GNT pretreatment towards hepatic damage in a model of acute intoxication with PQ in rats, was investigated. Wistar rats were randomized in 4 groups: Control, GNT (5 mg/kg/day sc, 4 days), PQ (50 mg/kg/day ip, last day) and GNT+ PQ. Hepatic lipoperoxidation (LPO) was evaluated by the thiobarbituric acid reactive substances method. Hepatic levels of 4-hydroxynonenal protein adducts (4-HNEp-add) and glutathione-S-transferase alpha (GSTα) protein expression were evaluated by Western blotting. Hepatic glutathione levels and plasma levels of alanine transaminase (ALT) and aspartate transaminase (AST) were also measured. Biliary excretion of PQ was studied in vivo and in isolated perfused liver. PQ was quantified by HPLC. PQ significantly increased AST and ALT activities, malondialdehyde and 4-HNEp-add levels, whereby pretreatment with GNT ameliorated this effect. PQ biliary excretion remained unchanged after treatments in both experimental models. Hepatic GSTα expression was augmented in GNT group. GNT pretreatment increased hepatic glutathione levels in PQ + GNT group. These results agree with the lower content of 4-HNEp-adds in GNT + PQ group respect to PQ group. Unexpectedly, increased activity of P-gp did not enhance PQ biliary excretion. Thus, GNT protective mechanism is likely through the induction of GSTα which results in increased 4-HNE metabolism before formation of protein adducts.