Exploring flavonoids as potent SLC46A3 inhibitors: Insights from the structural characteristics of flavonoid-SLC46A3 interactions.

SLC46A3, a transporter for lysosomal steroid conjugates and bile acids, plays a pivotal role in the pharmacological effects of noncleavable antibody-drug conjugates using maytansine as a payload. SLC46A3 may exert negative effects on various phenomena, including copper homeostasis, mitochondrial function in the liver, and the uptake of lipid-based nanoparticles (NPs) in tumor cells. Consequently, inhibiting SLC46A3 may be a promising strategy for treating hepatic disease or enhancing lipid NP delivery to tumor cells, although the underlying mechanisms remain unknown.

Assessment of polymeric mucin-drug interactions.

Mucosal-delivered drugs have to pass through the mucus layer before absorption through the epithelial cell membrane. Although there has been increasing interest in polymeric mucins, a major structural component of mucus, potentially acting as important physiological regulators of mucosal drug absorption, there are no reports that have systematically evaluated the interaction between mucins and drugs. In this study, we assessed the potential interaction between human polymeric mucins (MUC2, MUC5B, and MUC5AC) and various drugs with different chemical profiles by simple centrifugal method and fluorescence analysis.

The Use of Carboxyfluorescein Reveals the Transport Function of MCT6/SLC16A5 Associated with CD147 as a Chloride-Sensitive Organic Anion Transporter in Mammalian Cells.

Oral drug absorption involves drug permeation across the apical and basolateral membranes of enterocytes. Although transporters mediating the influx of anionic drugs in the apical membranes have been identified, transporters responsible for efflux in the basolateral membranes remain unclear. Monocarboxylate transporter 6 (MCT6/SLC16A5) has been reported to localize to the apical and basolateral membranes of human enterocytes and to transport organic anions such as bumetanide and nateglinide in the Xenopus oocyte expression system; however, its transport functions have not been elucidated in detail.

Macrolide and Ketolide Antibiotics Inhibit the Cytotoxic Effect of Trastuzumab Emtansine in HER2-Positive Breast Cancer Cells: Implication of a Potential Drug-ADC Interaction in Cancer Chemotherapy.

Macrolides are widely used for the long-term treatment of infections and chronic inflammatory diseases. The pharmacokinetic features of macrolides include extensive tissue distribution because of favorable membrane permeability and accumulation within lysosomes. Trastuzumab emtansine (T-DM1), a HER2-targeting antibody-drug conjugate (ADC), is catabolized in the lysosomes, where Lys-SMCC-DM1, a potent cytotoxic agent, is processed by proteinase degradation and subsequently released from the lysosomes to the cytoplasm through the lysosomal membrane transporter SLC46A3, resulting in an antitumor effect.

Monocarboxylate Transporter 13 (MCT13/SLC16A13) Functions as a Novel Plasma Membrane Oligopeptide Transporter.

, which encodes the monocarboxylate transporter 13 (MCT13), is a susceptibility gene for type 2 diabetes and is expressed in the liver and duodenum. Some peptidase-resistant oligopeptides are absorbed in the gastrointestinal tract and affect glycemic control in the body. Their efficient absorption is mediated by oligopeptide transporter(s) at the apical and basolateral membranes of the intestinal epithelia; however, the molecules responsible for basolateral oligopeptide transport have not been identified.

The Glycosylated -Terminal Domain of MUC1 Is Involved in Chemoresistance by Modulating Drug Permeation Across the Plasma Membrane.

Mucin 1 (MUC1) is aberrantly expressed in various cancers and implicated in cancer progression and chemoresistance. Although the -terminal cytoplasmic tail of MUC1 is involved in signal transduction, promoting chemoresistance, the role of the extracellular MUC1 domain [-terminal glycosylated domain (NG)-MUC1] remains unclear. In this study, we generated stable MCF7 cell lines expressing MUC1 and cytoplasmic tail-deficient MUC1 (MUC1ΔCT) and show that NG-MUC1 is involved in drug resistance by modulating the transmembrane permeation of various compounds without cytoplasmic tail signaling.

SLC46A3 is a lysosomal proton-coupled steroid conjugate and bile acid transporter involved in transport of active catabolites of T-DM1.

Antibody-drug conjugates (ADCs) represent a new class of cancer therapeutics that enable targeted delivery of cytotoxic drugs to cancer cells. Although clinical efficacy has been demonstrated for ADC therapies, resistance to these conjugates may occur. Recently, SLC46A3, a lysosomal membrane protein, was revealed to regulate the efficacy of trastuzumab emtansine (T-DM1), a noncleavable ADC that has been widely used for treating breast cancer.

Identification of 5-Carboxyfluorescein as a Probe Substrate of SLC46A3 and Its Application in a Fluorescence-Based In Vitro Assay Evaluating the Interaction with SLC46A3.

The therapeutic modalities that involve the endocytosis pathway, including antibody-drug conjugates (ADCs), have recently been developed. Since the drug escape from endosomes/lysosomes is a determinant of their efficacy, it is important to optimize the escape, and the cellular evaluation system is needed. SLC46A3, a lysosomal membrane protein, has been implicated in the pharmacological efficacy of trastuzumab emtansine (T-DM1), a noncleavable ADC used for the treatment of breast cancer, and the cellular uptake efficacy of lipid-based nanoparticles.

The lipophilic cyclic peptide cyclosporin A induces aggregation of gel-forming mucins.

Cyclic peptides are good candidates for orally delivered therapeutics, however, issues remain in their development due to low intestinal permeability. Although some of the biological factors have been reported that regulate intestinal permeation of cyclic peptides, the influence of the mucus barrier, a major hurdle to epithelial drug delivery, on cyclic peptide bioavailability is unclear. In this study, we show that the lipophilic cyclic peptide, cyclosporin A (CsA), interacted with, and likely induced aggregation, of polymeric, gel-forming mucins (MUC2, MUC5AC and MUC5B) which underpin the mucus gel-networks in the gastrointestinal tract.

Mammalian monocarboxylate transporter 7 (MCT7/Slc16a6) is a novel facilitative taurine transporter.

Monocarboxylate transporter 7 (MCT7) is an orphan transporter expressed in the liver, brain, and in several types of cancer cells. It has also been reported to be a survival factor in melanoma and breast cancers. However, this survival mechanism is not yet fully understood due to MCT7's unidentified substrate(s).

Multiple Transport Mechanisms Involved in the Intestinal Absorption of Metformin: Impact on the Nonlinear Absorption Kinetics.

The aim of this study was to investigate the contributions of multiple transport mechanisms to the intestinal absorption of metformin, focusing on OCT3, PMAT, THTR2, SERT and OCTN2. We also assessed the impact of these transporters on the nonlinear absorption of metformin. Uptake studies with MDCKII cells expressing OCT3, PMAT, THTR2 or SERT confirmed that metformin is a substrate of these transporters.

Utilization of Sodium Nitroprusside as an Intestinal Permeation Enhancer for Lipophilic Drug Absorption Improvement in the Rat Proximal Intestine.

As advanced synthetic technology has enabled drug candidate development with complex structure, resulting in low solubility and membrane permeability, the strategies to improve poorly absorbed drug bioavailability have attracted the attention of pharmaceutical companies. It has been demonstrated that nitric oxide (NO), a vital signaling molecule that plays an important role in various physiological systems, affects intestinal drug absorption. However, NO and its oxidants are directly toxic to the gastrointestinal tract, thereby limiting their potential clinical application as absorption enhancers.

Functional characterization of monocarboxylate transporter 12 (SLC16A12/MCT12) as a facilitative creatine transporter.

SLC16A12/MCT12 has been recently identified as a creatine transporter in a Xenopus oocyte expression system; however, the mechanism, by which MCT12 transports creatine, remains unclear. This study was performed to determine the functional and molecular characteristics of MCT12 in mammalian cells. The results showed that the uptake of [C]creatine was not significantly increased in HEK293 cells transiently expressing MCT12 with or without CD147, a molecular chaperone, compared with mock cells.

Mucins are Involved in the Intestinal Permeation of Lipophilic Drugs in the Proximal Region of Rat Small Intestine.

Purpose: Mucins are the principal glycoproteins in mucus and have been implicated in the limitation of intestinal drug absorption; however, the contribution of these molecules to intestinal drug absorption remains unclear. In this study, the relationship between the effect of the mucus layer on intestinal drug permeation and mucin distribution in different parts of the rat gastrointestinal tract was evaluated.

Methods: The intestinal permeability of various lipophilic drugs in rat small intestine was evaluated using the in vitro sac method.

Effect of Osmolality on the Pharmacokinetic Interaction between Apple Juice and Atenolol in Rats.

A recent clinical study reported that the ingestion of apple juice (AJ) markedly reduced the plasma concentration of atenolol; however, our in vitro study showed that atenolol may not be a substrate of organic anion transporting polypeptide 2B1 (OATP2B1), so this AJ-atenolol interaction cannot be explained by inhibition of OATP2B1. On the other hand, we more recently showed that the solution osmolality influences gastrointestinal (GI) water volume, and this may indirectly affect intestinal drug absorption. In this study, we examined whether the osmolality dependence of water dynamics can account for AJ-atenolol interactions by evaluating the GI water volume and the atenolol aborption in the presence of AJ in rats.

Organic anion transporter 1 (OAT1/SLC22A6) enhances bioluminescence based on d-luciferin-luciferase reaction in living cells by facilitating the intracellular accumulation of d-luciferin.

Bioluminescence (BL) imaging based on d-luciferin (d-luc)-luciferase reaction allows noninvasive and real-time monitoring of luciferase-expressing cells. Because BL intensity depends on photons generated through the d-luc-luciferase reaction, an approach to increase intracellular levels of d-luc could improve the detection sensitivity. In the present study, we showed that organic anion transporter 1 (OAT1) is useful, as a d-luc transporter, in boosting the BL intensity in luciferase-expressing cells.

Osmolality of Orally Administered Solutions Influences Luminal Water Volume and Drug Absorption in Intestine.

Intestinal water absorption is reportedly influenced by luminal osmolality. In this study, we examined whether differences in the osmolality of the vehicle used for oral administration of drugs influence luminal water volume and drug absorption in the gastrointestinal (GI) tract, by means of in situ rat intestinal closed loop studies using solutions of fluorescein isothiocyanate dextran 4000 (a non-absorbable compound), atenolol (a low-permeability drug), and antipyrine (a high-permeability drug) in various solvents. Determination of the remaining fraction of water revealed the following rank order for water absorption in rat jejunum: purified water > saline > phosphate buffer = isosmotic mannitol solution.

Absorption-Enhancing Effect of Nitric Oxide on the Absorption of Hydrophobic Drugs in Rat Duodenum.

Nitric oxide (NO), an endogenous gas that plays a versatile role in the physiological system, has the ability to increase the intestinal absorption of water-soluble compounds through the paracellular route. However, it remains unclear whether NO can enhance the absorption of hydrophobic drugs through the transcellular route. In this study, we examined the absorption-enhancing effect of NO on intestinal permeability of hydrophobic drugs in rat intestine.

Changes in the expression levels of tight junction components during reconstruction of tight junction from mucosal lesion by intestinal ischemia/reperfusion.

Tight junction (TJ) is composed of the most apical components of the intercellular junctional complex in epithelial cells; TJ has cell polarity and functions as a major determinant of epithelial barrier function. In this study, to clarify the components of TJ required for its reconstruction and functional acquisition, we examined the changes in intestinal mucosal structure that depended on mucosal lesion by intestinal I/R, that is, the changes in mRNA and protein expression of the claudin family and scaffold proteins. We used an in vivo intestinal I/R model made using the spring scale and surgical sutures, and examined the mRNA and protein expression levels of TJ components by real-time RT-PCR and Western blotting, respectively.

Effects of pharmaceutical excipients on membrane permeability in rat small intestine.

Pharmaceutical excipients should not disturb the effects of drug therapy. In recent years, however, it has been reported that excipients induce some changes to the tight junction (TJ) and P-glycoprotein (P-gp), which can affect drug disposition. In this study, we examined the effects of 20 common pharmaceutical excipients from different classes on mucosal membrane and the differences of such effects among regions of the small intestine.

Characteristics of reversible absorption-enhancing effect of sodium nitroprusside in rat small intestine.

Nitric oxide (NO) donors increase the permeability of water-soluble compounds with neither loss of cell viability nor lactate dehydrogenase release. In addition, the rectal absorption of insulin has been reported to be remarkably enhanced in the presence of NO donors such as 1-Hydroxy-3-(3-aminopropyl)-3-isopropyltriazene 2-oxide (NOC5) and N-Ethyl-2-(1-ethyl-2-hydroxy-2-nitrosohydrazino) ethanamine (NOC12). In this study, we examined the effect of sodium nitroprusside (SNP), which is used in clinical situations as a vasodilator, as a model NO donor on the ileal mucosa of rats.

Changes in absorption and excretion of rhodamine 123 by sodium nitroprusside.

Nitric oxide (NO) donors increase the permeability of water-soluble compounds with neither loss of cell viability nor lactate dehydrogenase release, but the involved mechanism is not fully understood. In this study, we focused on permeation via the transcellular route and P-glycoprotein, which is a typical ABC transporter. We examined the effect of sodium nitroprusside (SNP), which is an NO donor, on the membrane permeation of rhodamine 123 (Rho123), a representative P-gp substrate, and the change in expression level of ileal P-gp.

Changes in protein and mRNA expression levels of claudin family after mucosal lesion by intestinal ischemia/reperfusion.

Ischemia/reperfusion (I/R) injury of the intestine is the leading cause of organ dysfunction after restoration of blood flow after diverse events, including shock and intestinal transplantation. I/R injury must be overcome for successful small intestinal transplantation. Tight junctions (TJ) are the most apical component of the intercellular junctional complex in epithelial cells; they establish cell polarity and functioning as major determinants of epithelial barrier function.

Changes in the localization of ileal P-glycoprotein induced by intestinal ischemia/reperfusion.

P-glycoprotein is one of the most important transporters in the ATP binding cassette transporter. Moreover, it is well known that the efficacy of immunosuppressants, which are used after organ transplantation, is controlled by P-glycoprotein (P-gp). We investigated how ischemia/reperfusion (I/R), which occurs after transplantation, influences the expression level and function of P-gp.

Effects of antioxidants on drug absorption in in vivo intestinal ischemia/reperfusion.

Ischemia/reperfusion (I/R) injury must be overcome in order to succeed in small intestinal transplantation. Reactive oxygen species (ROS) are generated by I/R, and they induce lipid peroxidation which is one of the causes of mucosal lesion. We previously reported the protection effects of antioxidants to I/R injury in the in vitro study.