Internalization of FITC-albumin in Human Adipose-derived Stem Cells: Involvement of Clathrin and Caveolin.

Adipose tissue-derived stem cells (AdSCs) are one of the most promising cell types for cell-based therapies. In addition, AdSCs systematically injected into the body have been reported to localize to damaged tissues and certain types of tumor. As an important part of establishing a potent drug delivery system with AdSCs, the mechanism and efficiency of uptake into AdSCs has drawn much research attention.

Pharmacokinetic-pharmacodynamic modelling of the hypoglycaemic effect of pulsatile administration of human insulin in rats.

The relationship between the plasma insulin (INS) concentration-time course and plasma glucose concentration-time course during and after pulsatile INS administration to rats was characterized using a pharmacokinetic-pharmacodynamic (PK-PD) model. A total INS dose of 0.5 IU/kg was intravenously injected in 2 to 20 pulses over a 2-h period.

Effect of riboflavin deficiency on development of the cerebral cortex in Slc52a3 knockout mice.

Riboflavin transporter 3 (RFVT3), encoded by the SLC52A3 gene, is important for riboflavin homeostasis in the small intestine, kidney, and placenta. Our previous study demonstrated that Slc52a3 knockout (Slc52a3-/-) mice exhibited neonatal lethality and metabolic disorder due to riboflavin deficiency. Here, we investigated the influence of Slc52a3 gene disruption on brain development using Slc52a3-/- embryos.

Fatty acids bound to albumin induce prostaglandin E production in human renal proximal tubular epithelial cell line HK-2.

Fatty acids bound to albumin have been reported to be involved in various responses in renal proximal tubular cells following albumin overload, leading to progression of tubulointerstitial damage in the kidneys. In addition, it has been reported that prostaglandin E (PGE) plays an important role in nephrotoxicity. The aim of this study was to examine whether albumin-bound fatty acids induce PGE production in human renal proximal tubular epithelial cell line HK-2.

Pioglitazone induces hypoxia-inducible factor 1 activation in human renal proximal tubular epithelial cell line HK-2.

We previously reported that fatty acid-bearing albumin but not fatty acid-depleted albumin induces hypoxia-inducible factor-1 (HIF-1) activation in human renal proximal tubular epithelial cell line HK-2. Then, an increase in mRNA expression of peroxisome proliferator-activated receptor gamma (PPARγ) was observed on treatment with fatty acid-bearing albumin but not fatty acid-depleted albumin. The aim of this study was to determine whether a PPARγ agonist, pioglitazone, induces HIF-1 activation or not.

Cobalt Chloride Induces Expression and Function of Breast Cancer Resistance Protein (BCRP/ABCG2) in Human Renal Proximal Tubular Epithelial Cell Line HK-2.

The human breast cancer resistance protein (BCRP/ABCG2), a member of the ATP-binding cassette transporter family, is a drug transporter restricting absorption and enhancing excretion of many compounds including anticancer drugs. The cis-regulatory elements in the BCRP promoter include a hypoxia response element, i.e.

Cisplatin resistance in human lung cancer cells is linked with dysregulation of cell cycle associated proteins.

Aims: Cisplatin (CDDP) is a platinum-based drug that is widely used in cancer chemotherapy, but the development of resistance in tumor cells is a major weakness of these treatments. Several mechanisms have been proposed to explain cisplatin resistance, and disruption of certain cellular pathways could modulate drug sensitivity to cisplatin. A lower level of cross-resistance to cisplatin leads to better outcomes in clinical use.

Fatty acid-bearing albumin but not fatty acid-depleted albumin induces HIF-1 activation in human renal proximal tubular epithelial cell line HK-2.

Recently, we found that albumin overload induces expression of the transcription factor hypoxia-inducible factor-1α (HIF-1α) protein and several HIF-1 target genes in human renal proximal tubular epithelial cell line HK-2. In this study, the role of albumin-bound fatty acids in the albumin-induced HIF-1 activation was studied. The enhancing effect of fatty acid-bearing human serum albumin [FA(+)HSA] treatment on HIF-1α protein expression was much greater than that of fatty acid-depleted human serum albumin [FA(-)HSA] treatment.

Entry of aminoglycosides into renal tubular epithelial cells via endocytosis-dependent and endocytosis-independent pathways.

Aminoglycoside antibiotics such as gentamicin and amikacin are well recognized as a clinically important antibiotic class because of their reliable efficacy and low cost. However, the clinical use of aminoglycosides is limited by their nephrotoxicity and ototoxicity. Nephrotoxicity is induced mainly due to high accumulation of the antibiotics in renal proximal tubular cells.

Characterization of protamine uptake by opossum kidney epithelial cells.

Protamine, a mixture of polypeptides that is rich in arginine, has been used clinically as an antidote to heparin overdoses and a complexing agent in a long-acting insulin preparation. When protamine is administered intravenously, its abundant accumulation in the kidneys has been reported. However, the renal uptake mechanism for protamine is not clear.

Expression and function of PEPT2 during transdifferentiation of alveolar epithelial cells.

Aims: The purpose of this study was to clarify the expression and function of peptide transporter 2 (PEPT2) in primary cultured alveolar type II epithelial cells and in transdifferentiated type I-like cells.

Main Methods: Real-time PCR analysis, uptake study of [(3)H]Gly-Sar, and immunostaining were performed in alveolar epithelial cells.

Key Findings: The expression of PEPT2 mRNA in type II cells isolated from rat lungs was highest at day 0, and decreased rapidly during culture of the cells.

Enhancing effect of poly(amino acid)s on albumin uptake in human lung epithelial A549 cells.

The clearance of albumin from the alveolar space is a critical process in the recovery from edema. In this study, we investigated the effect of poly(amino acid)s such as poly-l-ornithine (PLO) on albumin uptake in the cultured lung epithelial cell line A549. FITC-albumin uptake as well as cell surface binding was markedly stimulated by co-incubation with PLO, and there was a good correlation between them.

Albumin overload induces expression of hypoxia-inducible factor 1α and its target genes in HK-2 human renal proximal tubular cell line.

The aim of this study was to investigate the effect of human serum albumin (HSA) overload on the expression of the transcription factor hypoxia-inducible factor-1α (HIF-1α) in human renal proximal tubular cell line HK-2. First, the cell viability and cytotoxic activity were examined to assess the cellular conditions in HK-2 cells with HSA treatment employed in this study. HSA treatment for 48h decreased the cell viability and increased the leakage of lactate dehydrogenase (LDH) into the medium in a concentration-dependent manner, but the toxicity was relatively mild.

Effect of protamine on the accumulation of gentamicin in opossum kidney epithelial cells.

Objectives: The purpose of this study was to examine whether or not protamine, an arginine-rich basic protein mixture, inhibits the accumulation of gentamicin, a nephrotoxic drug, in cultured opossum kidney (OK) epithelial cells.

Methods: The effect of protamine from salmon on accumulation and binding of [(3) H]gentamicin was investigated in OK cells.

Key Findings: Protamine inhibited the binding and accumulation of [(3) H]gentamicin in a concentration-dependent manner.

Effect of cigarette smoke extract on insulin transport in alveolar epithelial cell line A549.

Background: The main purpose of this study was to evaluate the effect of cigarette smoke extract (CSE) on insulin transport in alveolar epithelial cells.

Methods: We first examined the effect of CSE pretreatment on cell viability, mRNA expression, and lamellar body structures in A549 cells. Then the effect of CSE pretreatment on FITC-insulin transport was examined.

Flow cytometry analysis of cancer cell death induced by the extract of Thai plant Ellipeiopsis cherrevensis.

  The mechanism of cancer cell death induced by KP018, an ethanol extract of the Thai plant Ellipeiopsis cherrevensis, was examined in paclitaxel-resistant HepG2 (PR-HepG2) and colon-26 cells using flow cytometry. In PR-HepG2 cells, KP018 induced necrosis in a concentration-dependent manner. Necrosis of PR-HepG2 cells induced by KP018 as well as by hydrogen peroxide was suppressed by co-treatment of the cells with N-acetylcysteine.

Enhancement effect of poly(amino acid)s on insulin uptake in alveolar epithelial cells.

In this study, we elucidated the effect of poly(amino acid)s such as poly-L-ornithine (PLO) on FITC-insulin uptake in cultured alveolar type II epithelial cells, RLE-6TN. FITC-insulin uptake by RLE-6TN cells as well as its cell surface binding was markedly increased by PLO without cytotoxicity. The uptake of FITC-insulin in the presence of PLO was shown to be mediated by endocytosis, but in contrast to the uptake in the absence of PLO, the contribution of macropinocytosis emerged.

Gadolinium modulates gentamicin uptake via an endocytosis-independent pathway in HK-2 human renal proximal tubular cell line.

The aim of this study was to characterize the uptake mechanism of gentamicin, an aminoglycoside antibiotic, in human renal proximal tubular cell line HK-2. Sodium-dependent uptake of D-[(3)H]glucose and L-[(3)H]alanine was observed in HK-2 cells, indicating that the cells employed in this study retain functional characteristics of the renal proximal tubular cells. On the other hand, mRNA and protein expression of megalin, an endocytic receptor which is responsible for the internalization of gentamicin into the renal proximal tubular cells, was very faint in HK-2 cells.

Endocytic uptake of FITC-albumin by human alveolar epithelial cell line A549.

The uptake mechanism of FITC-labeled albumin (FITC-albumin) was examined in human alveolar epithelial cell line A549. FITC-albumin uptake by A549 cells was time- and temperature-dependent, and was markedly suppressed at 4°C compared with that at 37°C. The uptake was saturable, and was mediated by a high-affinity, low-capacity system and by a low-affinity, high-capacity system.

Nanoparticulation of probucol, a poorly water-soluble drug, using a novel wet-milling process to improve in vitro dissolution and in vivo oral absorption.

To improve the dissolution and oral absorption properties of probucol, a novel wet-milling process using the ULTRA APEX MILL was investigated. The particle size of bulk probucol powder was 17.1 µm.

Mechanism underlying insulin uptake in alveolar epithelial cell line RLE-6TN.

For the development of efficient pulmonary delivery systems for protein and peptide drugs, it is important to understand their transport mechanisms in alveolar epithelial cells. In this study, the uptake mechanism for FITC-insulin in cultured alveolar epithelial cell line RLE-6TN was elucidated. FITC-insulin uptake by RLE-6TN cells was time-dependent, temperature-sensitive, and concentration-dependent.

Megalin/cubilin-mediated uptake of FITC-labeled IgG by OK kidney epithelial cells.

In this paper, we characterize the uptake mechanism of fluorescein isothiocyanate-labeled human immunoglobulin G (FITC-hIgG) in opossum kidney (OK) epithelial cells, which have been shown to express megalin and cubilin. Confocal immunofluorescence microscopy showed the punctate expression of the neonatal Fc receptor FcRn in the cytoplasm, but not on the cell surface membrane. Temperature- and energy-dependent uptake of FITC-hIgG was observed at pH 7.

Accumulation and photodynamic activity of chlorin e6 in cisplatin-resistant human lung cancer cells.

Cisplatin or cis-diamminedichloroplatinum (II) (CDDP) is one of the most potent anticancer drugs, but the emergence of acquired resistance to CDDP is a major problem in clinical settings. The purpose of this study was to investigate and compare the cellular accumulation and photodynamic activity of chlorin e6, a photosensitizer, in human lung cancer A549 cell line and its CDDP-resistant subline. First, we established the CDDP-resistant (A549/CDDP) cell subline with fourfold greater half-maximal inhibitory concentration value of CDDP on cell growth than that of the parent A549 cells.

Human erythrocyte nucleoside transporter ENT1 functions at ice-cold temperatures.

The functionality of human erythrocyte nucleoside transporter ENT1 was examined at ice-cold temperatures (ICT; measured temperature, 0.5-0.7 degrees C) using rightside-out membrane vesicles (ROVs).

Molecular-targeted approaches to reduce renal accumulation of nephrotoxic drugs.

Importance Of The Field: Nephrotoxicity limits the clinical use of some antibiotics, cancer chemotherapeutics and diagnostic agents. Some nephrotoxic drugs are highly accumulated in the kidney via specific transport systems expressed in renal proximal tubular cells. The concentrated and retained accumulation often leads to nephrotoxicity.