Expression Of OCT1 Research Articles

DNA methylation integratedly modulates the expression of Pit-Oct-Unt transcription factors in esophageal squamous cell carcinoma.

Background: Dysregulation of Pit-Oct-Unc family transcription factors has been implicated in esophageal squamous cell carcinoma (ESCC). In this study, we evaluated the expression and promoter methylation status of Octamer (OCT) transcription factor genes in human ESCC clinical specimens to investigate the mechanism underlying this observation along with the clinical significance.Methods: Total DNA or RNA was extracted from ESCC tissue specimens and the mRNA level of genes encoding the transcription factors OCT1, OCT2, OCT3/OCT4, OCT5, OCT7, OCT9, and OCT11 were evaluated by quantitative PCR. The DNA methylation status of gene promoters was assessed by bisulfite pyrosequencing and next-generation sequencing. The relationship between the expression of these transcription factors and ESCC proliferation was investigated in vitro and in vivo with the colony formation assay and a mouse xenograft tumor model, respectively. We also examined the correlation between OCT gene expression and promoter methylation and clinicopathologic characteristics of ESCC.Results: OCT1 was upregulated whereas OCT4, OCT6, and OCT11 were downregulated in ESCC compared to non-tumor tissue. OCT2, OCT7, and OCT9 were undetected in all samples. OCT1, OCT6, and OCT11 levels were negatively correlated with the methylation of their respective promoters, but there was no relationship between OCT4 expression and promoter methylation status.Conclusion: Changes in promoter methylation rate underlie the observed alterations in OCT1, OCT6, and OCT11 expression in ESCC, whereas another mechanism is likely responsible for the dysregulation of OCT4.

Rosai-Dorfman Disease Displays a Unique Monocyte-Macrophage Phenotype Characterized by Expression of OCT2.

Rosai-Dorfman disease (RDD) is a rare histiocytosis with heterogenous clinical features. In this study, we characterized the histologic and phenotypic features in 33 RDD patients to better define the pathologic diagnosis. Cases included 24 patients with extracutaneous disease ("R" group), and 9 patients with lesions limited to the skin or subcutaneous tissue ("C" group). We identified OCT2 as a novel marker for the monocyte-macrophage phenotype of RDD, expressed in 97% of RDD cases. In contrast, OCT2 expression was seen in 0% of Erdheim-Chester disease cases and 6.7% of Langerhans cell histiocytosis cases. Other markers useful in the diagnosis of RDD included S100 (100%), CD163 (88%), and cyclin D1 (97%). In a subset of cases, RDD showed moderate to strong expression of factor 13a (30%), p16 (64%), and phosphorylated extracellular signal-regulated kinase (45%); RDD was uniformly negative for ZBTB46, CD1a, and langerin. Within the "R group" of RDD, increased expression of factor 13a or phosphorylated extracellular signal-regulated kinase showed a statistically significant association with multifocal disease (P<0.05). Identification of the unique monocyte-macrophage phenotype of RDD with OCT2 expression furthers our understanding of this complex disease and allows for more uniform classification.

Overexpression of the OCT-1 Gene Is a Biomarker Associated with Poor Outcomes in Diffuse Large B-Cell Lymphoma (DLBCL) - Data from a Retrospective Cohort from Latin America: Defining a Very High-Risk Clinical-Molecular Subgroup

Introduction: Diffuse large B-cell lymphoma (DLBCL) is the most frequent lymphoid malignancy, representing 30-40% of all non-Hodgkin's lymphomas (NHLs). They comprise a group of aggressive and heterogeneous neoplasms in terms of clinical presentation, response to therapy and prognosis. The OCT-1 gene is a member of the homodomain-POU family of transcriptional regulators of B-lymphoid differentiation. OCT-1 acts by controlling the expression of specific B-cell genes, such as BCL-2, a potent inhibitor of apoptosis that is essential for the differentiation of B-cells in the germinal center. These genes can be expressed in DLBCL, but the role of BCL-2 in its prognosis has been contradictory and the prognostic impact of the OCT-1 gene has not yet been tested in this lymphoma. Methods: In this observational, retrospective, single-center study, we investigated the prognostic impact of BCL-2 and OCT-1 gene expression in Brazilian patients with DLCBL treated with immunopolychemotherapy R-CHOP in a real-world context. The BCL-2 and OCT-1 genes were assessed in 78.5% (77/98) DLBCL patients, and the RNA for quantitative real-time PCR (qRT-PCR) was isolated from formalin-fixed and paraffin-embedded (FFPE) samples. The values obtained for gene expression were transformed into categorical variables according to their medians (6.27 for BCL-2 and 24.5 for OCT-1). The association between clinical and laboratory variables and results of gene expression was verified by the Fischer test. Overall survival (OS) and progression-free survival (PFS) were estimated using the Kaplan-Meier method. Univariate analysis was performed using Cox's bivariate regression method and multivariate analysis using Cox multiple regression methodology. Results: The median age of the cohort was 54.5 years (15-84), 50% (49/98) were male, 49.4% (38/77) and 51.4% (40/77) showed expression of OCT-1 and BCL- 2 ≥ median, respectively. The clinical characteristics of the 98 Brazilian patients with DLBCL that comprised our cohort are summarized in Table 1. The overall response rate (ORR) in all patients was 68.4% (67/98), 65.3% (64/98) showed a complete response (CR), and 3.1% (3/98) showed partial response (PR), while 6.1% (6/98) were primary refractory. With a median follow-up of 3.77 years (95% CI: 3.2-4.1), the median overall survival (OS) was 5.43 years (95% CI: 2.2-NR) and the median progression-free survival (PFS) was 5.15 years (95% CI: 2.9-NR). The 5-year OS and PFS was 54.2% (42.2% -64.8%) and 52.0% (40.1-62.6%), respectively. In the univariate analysis OCT-1 ≥ median was associated with shortened OS (HR: 2.45, 95% CI: 1.21-4.96, p = 0.013) and PFS (HR: 2.27, 95% CI: 1.14-4.51, p = 0.019). Overexpression of BCL-2 was associated with worse PFS (HR: 2.00, 95% CI: 1.02-3.95, p = 0.043). Subgroup analysis showed that OCT-1 overexpression predominated in elderly individuals (≥ 60 years) in a statistically significant mode (29/38 cases - 76.3%, p = 0.029). It was also observed that overexpression of OCT-1 was associated with worse OS in the high-risk adjusted International Prognostic Index (aIPI) subgroup (p = 0.048) - Figure 1, and worse PFS in patients ≥ 60 years old (p = 0.025) - Figure 2. In the multivariate analysis, overexpression of OCT-1 was associated with poor PFS (HR: 2.22, 95% CI: 1.06-4.76, p = 0.035). Conclusion: In this study, we demonstrated that overexpression of the OCT-1 gene was an independent prognostic factor associated with adverse outcomes in Brazilian patients with DLCBL. We also show that in patients with unfavorable risk, such as the elderly and those with intermediate-high and high-risk IPI, overexpression of OCT-1 contributed to the identification of a very high-risk clinical-molecular subgroup, where the results with standard R-CHOP therapy are unsatisfactory, and they may benefit from intensified therapeutic strategies. Our results are preliminary and need to be validated in subsequent studies of prospective nature and with an expanded sample. Disclosures No relevant conflicts of interest to declare.

Overexpression of OCT-1 gene is a biomarker of adverse prognosis for diffuse large B-cell lymphoma (DLBCL): data from a retrospective cohort of 77 Brazilian patients

BackgroundOCT-1 gene is a member of the POU-homeodomain family of transcriptional regulators of B-lymphocyte differentiation by controlling expression of B-cell specific genes. BCL-2 gene is a potent inhibitor of apoptosis and it is essential during B-cell differentiation into germinal center. These genes may be expressed in diffuse large B-cell lymphoma (DLBCL), but the role of BCL-2 in its prognosis has been contradictory, and OCT-1 has yet to be tested.MethodsIn this study, we aimed to investigate the prognostic impact of OCT-1 and BCL-2 expression in DLBCL treated in the real world with immunochemotherapy in a single center. BCL-2 and OCT-1 genes were available in 78.5% (77/98) DLBCL patients, and the RNA for quantitative real-time PCR was isolated from formalin-fixed paraffin-embedded samples. The values obtained for gene expression were transformed in categorical variable according to their median.ResultsCohort median age was 54.5 years (15–84), 49 (50%) were male, 38/77 (49.4%) and 40/77 (51.9%) presented OCT-1 and BCL-2 expression ≥ median, respectively. The overall response rate (ORR) in all patients was 68.4% (67/98), 65,3% (64/98) of patients acquired complete response, and 3.1% (3/98) partial response, while 6.1% (6/98) were primary refractory. The median follow-up was 3.77 years (95% CI: 3.2–4.1), with 5.43 (95% CI: 2.2-NR) of overall survival (OS) and 5.15 years (95% CI: 2.9-NA) of progression free survival (PFS). OCT-1 ≥ median was associated with shorter OS at univariate analysis (p = 0.013; [HR] 2.450, 95% CI: 1.21–4.96) and PFS (p = 0.019; [HR] 2.270, 95%CI: 1.14–4.51) and BCL-2 gene overexpression presented worse PFS (p = 0.043, [HR] 2.008, 95% CI: 1.02–3.95). At multivariate analysis, OCT-1 overexpression was associated with poor PFS (p = 0.035, [HR] 2.22, 95% CI: 1.06–4.67).ConclusionIn this study, we showed that overexpression of OCT1 gene was an independent prognostic factor of adverse outcomes in DLBCL.

Effect of Genetic Polymorphisms of Human SLC22A3 in the 5’-flanking Region on OCT3 Expression and Sebum Levels in Human Skin

BackgroundHuman organic cation transporter 3 (OCT3,SLC22A3) mediates the uptake of many important endogenous substances and basic drugs, and has been identified as one of the transporters that are highly expressed in human skin. However, the mechanisms responsible for variability in mRNA expression, and the role of SLC22A3 in human skin is not clear. ObjectiveWe examined the effects of the single nucleotide polymorphisms ofSLC22A3 on the variability in SLC22A3 expression and sebum levels in humans. MethodsImmunostaining of OCT3 in human skin was performed. We analyzed the association of promoter variants with the SLC22A3 mRNA expression levels in human skins. Luciferase, knockdown, chromatin immunoprecipitation (ChIP), electrophoretic mobility shift assay were employed to investigate transcriptional regulation of SLC22A3 expression. Effects of the identified variant on sebum levels were evaluated in healthy volunteers. ResultsImmunohistochemistry revealed marked expressions of OCT3 in the basal epidermis, sebaceous glands, hair follicles, and sweat glands of human skin. SLC22A3 mRNA levels were significantly lower in skin samples with homozygotes for –1603A/A than in those for −1603 G/G. The analysis of p53 binding to −1603 G > A in the promoter ofSLC22A3 suggested that −1603 G > A down-regulates SLC22A3 gene expression by decreased p53 binding in the vicinity of the –1603 site. In humans, squalene levels in samples from the back at the baseline were significantly lower in homozygotes for –1603A/A than in those for −1603 G/G. ConclusionThese results suggest that the genetic variant contributes to the variability of expression and activities of OCT3 in human skin.

CP-25 improves nephropathy in collagen-induced arthritis rats by inhibiting the renal inflammatory response

Paeoniflorin-6′-O-benzene sulfonate (CP-25) is a derivative of paeoniflorin. We previously confirmed that CP-25 inhibits inflammatory responses in several arthritis animal models. The aim of the present study was to investigate the beneficial effects of CP-25 on renal damage in rats with collagen-induced arthritis (CIA). CIA was induced in rats, which were orally administered CP-25 (25, 50 and 100 mg/kg/day) for 24 days. The levels of plasma blood urea nitrogen (BUN) and urine protein in CIA rats were measured. Pathological changes in renal tissues and joints were observed, and inflammatory cell infiltration was evaluated by immunohistochemistry. Moreover, renal inflammatory mediators and transporters were measured by western blotting. We found that CP-25 not only inhibited arthritis manifestations but also improved renal pathological manifestations and kidney injury by decreasing serum BUN and urine protein levels. Further study revealed that CP-25 treatment reduced the number of renal CD68+ cells and downregulated the levels of MCP-1, TNF-α and IL-6 in CIA rats. On the other hand, we noted that CP-25 decreased the ratios of phosphorylated NF-κB p65 (p-p65) to total p65 and p-IκBα to total IκBα in CIA rats, suggesting that CP-25 blocked NF-κB activation. Finally, we observed that CP-25 restored the abnormal expression of OAT1 and OCT1 in the renal tissues of CIA rat. Our data indicate that CP-25 ameliorates kidney damage in CIA rats, and this beneficial effect is closely related to inhibiting renal inflammation and the abnormal expression of transporters.

Farnesoid X Receptor Activation Stimulates Organic Cations Transport in Human Renal Proximal Tubular Cells.

Farnesoid X receptor (FXR) is a ligand-activated transcription factor highly expressed in the liver and kidneys. Activation of FXR decreases organic cation transporter (OCT) 1-mediated clearance of organic cation compounds in hepatocytes. The present study investigated FXR regulation of renal clearance of organic cations by OCT2 modulation and multidrug and toxin extrusion proteins (MATEs). The role of FXR in OCT2 and MATEs functions was investigated by monitoring the flux of 3H–MPP+, a substrate of OCT2 and MATEs. FXR agonists chenodeoxycholic acid (CDCA) and GW4064 stimulated OCT2-mediated 3H–MPP+ uptake in human renal proximal tubular cells (RPTEC/TERT1 cells) and OCT2-CHO-K1 cells. The stimulatory effect of CDCA (20 µM) was abolished by an FXR antagonist, Z-guggulsterone, indicating an FXR-dependent mechanism. CDCA increased OCT2 transport activity via an increased maximal transport rate of MPP+. Additionally, 24 h CDCA treatment increased MATEs-mediated 3H-MPP+ uptake. Moreover, CDCA treatment increased the expression of OCT2, MATE1, and MATE2-K mRNA compared with that of the control. OCT2 protein expression was also increased following CDCA treatment. FXR activation stimulates renal OCT2- and MATE1/2-K-mediated cation transports in proximal tubules, demonstrating that FXR plays a role in the regulation of OCT2 and MATEs in renal proximal tubular cells.

TGF-β is associated with poor prognosis and promotes osteosarcoma progression via PI3K/Akt pathway activation

ABSTRACT Transforming growth factor beta (TGF-β) is a multifunctional cytokine with important functions in cell proliferation and differentiation. TGF-β is highly expressed in several types of cancers and promotes tumor invasion and metastasis. However, the role of TGF-β in osteosarcoma progression is poorly understood. In the present study, we found that TGF-β is highly expressed in osteosarcoma cells and tissues, and is associated with high Ennecking stage (P = 0.033), metastasis, and recurrence. TGF-β-knockdown osteosarcoma cell lines were established using siRNA (si-TGF-β). Cells transfected with si-TGF-β exhibited significantly reduced proliferation, migration/invasion, and colony formation abilities, and increased levels of cell apoptosis. In addition, si-TGF-β treatment reduced spheroid size, the ratio of CD133-positive cells, and expression of SOX-2, Nanog, and Oct-3/4 in osteosarcoma cells. Mechanistically, PI3K/mTOR phosphorylation is inhibited by TGF-β knockdown. Pretreatment with 25 µM LY294002, a PI3K-specific inhibitor, further enhanced the si-TGF-β-induced suppression of osteosarcoma progression. Taken together, these results reveal a novel role for TGF-β in osteosarcoma progression and modulation of stemness-related traits and indicate that TGF-β may be of value as a therapeutic target for the treatment of osteosarcoma.

Drug Elimination Alteration in Acute Lymphoblastic Leukemia Mediated by Renal Transporters and Glomerular Filtration.

Drug elimination alteration has been well reported in acute lymphoblastic leukemia (ALL). Considering that transporters and glomerular filtration influence, to different extents, the drug disposition, and possible side effects, we evaluated the effects of ALL on major renal transporters and glomerular filtration mediated pharmacokinetic changes, as well as expression of renal drug transporters. ALL xenograft models were established and intravenously injected with substrates of renal transporters and glomerular filtration separately in NOD/SCID mice. The plasma concentrations of substrates, after single doses, were determined using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). With the development of ALL, protein expression of MDR1, OAT3 and OCT2 were increased by 2.62-fold, 1.70-fold, and 1.45-fold, respectively, whereas expression of MRP2 and MRP4 were significantly decreased by 30.98% and 45.28% in the kidney of ALL groups compared with control groups. Clearance of MDR1-mediated digoxin, OAT3-mediated furosemide, and OCT2-mediated metformin increased by 3.04-fold, 1.47-fold, and 1.26-fold, respectively. However, clearance of MRPs-mediated methotrexate was reduced by 39.5%. These results are consistent with mRNA expression. Clearance of vancomycin and amikacin, as markers of glomerular filtration rate, had a 2.14 and 1.64-fold increase in ALL mice, respectively. The specific alteration of renal transporters and glomerular filtration in kidneys provide a rational explanation for changes in pharmacokinetics for ALL.

Altered Cisplatin Pharmacokinetics during Nonalcoholic Steatohepatitis Contributes to Reduced Nephrotoxicity

Cisplatin is an alkylating antineoplastic agent that is indicated for the treatment of solid malignancies. Cisplatin is preferentially eliminated from systemic circulation via tubular secretion, whereby it exhibits dose‐limiting nephrotoxicity. Interindividual variability in xenobiotic transporter expression is a known contributor to differential cisplatin toxicity and efficacy, and may be the result of genetic, environmental, and pathological contributions. In this study, we aimed to determine if nonalcoholic steatohepatitis (NASH) alters cisplatin pharmacokinetics and if this change elicits differential nephrotoxicity. Sprague Dawley rats fed a control or methionine and choline deficient (MCD) diet to model NASH were given a single bolus dose of cisplatin and sacrificed after 72 h. The MCD diet resulted in a NASH hepatic phenotype that remained unchanged following cisplatin exposure. Drug‐naïve NASH rats also displayed no evidence of differential renal pathology relative to control rats. However, renal necrosis and inflammation were reduced in NASH by 40 and 63% following cisplatin treatment, respectively, relative to healthy controls. Furthermore, kidney weights of cisplatin‐treated control rats were increased by 31%, compared to an 18% increase in NASH. Plasma cisplatin clearance was reduced from 6.78 (control) to 4.04 mL/min in NASH, and cisplatin plasma AUC was significantly increased by 44% in NASH, relative to control. Cumulative urinary elimination of cisplatin was decreased from 73 to 34% of total dose and renal clearance was reduced from 4.64 to 1.49 mL/min in NASH, compared to control. Subsequently, renal intracellular accumulation of cisplatin after 6 h was reduced by 34% in NASH, relative to control. Supporting these findings, expression of proximal tubule cisplatin uptake transporters, Ctr1 and Ctr2, were reduced by 24 and 64%, respectively compared to healthy control rats, whereas expression of Oct1, Oct2, and Oct3 were unchanged. Interestingly, expression of cisplatin efflux transporters Mate1 and Atp7a were reduced by 52 and 31%, respectively, in NASH compared to control. Taken together, these data suggest that NASH alters renal uptake and efflux transporter expression, thereby attenuating cisplatin uptake and clearance in the kidney with a corresponding reduction in renal cell exposure and nephrotoxicity during NASH. As such, this study demonstrates that NASH can influence pharmacokinetics of drugs cleared by renal elimination, which may contribute to adverse drug reactions.Support or Funding InformationThis work is supported by a NIH grant [R01 ES028668] and the Southwest Environmental Health Sciences Center [P30 ES006694]. JLJ is supported by an institutional training grant [T32 ES007091].

An Interspecies Molecular and Functional Study of Organic Cation Transporters at the Blood-Brain Barrier: From Rodents to Humans.

Organic cation transporters (OCTs) participate in the handling of compounds in kidneys and at the synaptic cleft. Their role at the blood-brain barrier (BBB) in brain drug delivery is still unclear. The presence of OCT1,2,3 (SLC22A1-3) in mouse, rat and human isolated brain microvessels was investigated by either qRT-PCR, quantitative proteomics and/or functional studies. BBB transport of the prototypical substrate [3H]-1-methyl-4-phenylpyridinium ([3H]-MPP+) was measured by in situ brain perfusion in six mouse strains and in Sprague Dawley rats, in primary human brain microvascular endothelial cells seeded on inserts, in the presence or absence of OCTs and a MATE1 (SLC49A1) inhibitor. The results show negligible OCT1 (SLC22A1) and OCT2 (SLC22A2) expression in either mice, rat or human brain microvessels, while OCT3 expression was identified in rat microvessels by qRT-PCR. The in vitro human cellular uptake of [3H]-MPP+ was not modified by OCTs/MATE-inhibitor. Brain transport of [3H]-MPP+ remains unchanged between 2- and 6-month old mice, and no alteration was observed in mice and rats with inhibitors. In conclusion, the evidenced lack of expression and/or functional OCTs and MATE at the BBB allows the maintenance of the brain homeostasis and function as it prevents an easy access of their neurotoxicant substrates to the brain parenchyma.

Influence of MRP3 Genetics and Hepatic Expression Ontogeny for Morphine Disposition in Neonatal and Pediatric Patients.

We have previously reported the influences of OCT1 ontogeny and genetic variation on morphine clearance in neonatal and pediatric patients. In the latter study, plasma morphine-glucuronide levels correlated with patient genotype for the rs4793665 single-nucleotide polymorphism (SNP) at the locus of MRP3, an efflux transporter of morphine glucuronides between hepatocytes and circulating blood. The link between MRP3 activity and overall morphine clearance has not been thoroughly investigated however, and the developmental profile of hepatic MRP3 protein expression remains thinly defined between neonates and adults. In the current study, previously determined morphine clearance values for neonatal (24-58 weeks postmenstrual age, N = 57) and pediatric (5-16 years, n = 85) patients were reanalyzed for correlation to the SNP genotype of patient rs4793665. Among OCT1 wild-type patients, pediatric morphine clearance showed a significant decreasing trend by MRP3 genotypes in the order of CC > CT > TT (P = .014), whereas for neonates, an identical but nonsignificant trend was observed. Pharmacogenetic differences in MRP3 and OCT1 ontogeny were evaluated by Western blot of hepatic membrane fractions from 50 subjects aged 1 day postnatal to 33 years old. Hepatic MRP3 protein level did not vary by rs4793665 genotype, and followed an atypical developmental pattern of increase up to 1-2 years of age, thereafter decreasing during preadolescence before increasing again to adult levels at maturity (17-33 years). By comparison, OCT1 expression was significantly decreased in OCT1 *1/*3 genotyped patients older than 1 year and followed a trajectory consistent with prior studies. Our results suggest that consideration of MRP3 pharmacogenetics and ontogeny may aid in identifying pediatric patients having different/atypical morphine requirements.

Neurochemical characterization of mouse dorsal root ganglion neurons expressing organic cation transporter 2.

Organic cation transporters (OCTs) are poly-specific carriers for endogenous and exogenous cationic compounds. These are widely distributed in the nervous system and mediate neuronal activities. As antineoplastic cationic drugs accumulate in the dorsal root ganglion (DRG), OCT function has been studied mainly in cultured DRG neurons. However, the histological distribution of OCTs in the DRG is unclear. This study investigated the localization of OCT2 (a member of OCTs) in mouse DRG neurons and determined their histochemical properties. OCT2 expression was found in about 20% of DRG neurons, which were small to medium size. OCT2-expressing neurons were labeled with markers for peptidergic nociceptive (substance P or calcitonin gene-related peptide) and tactile/proprioceptive (neurofilament 200 or tropomyosin receptor kinase B or C) neurons. OCT2 was also expressed in cholinergic DRG neurons identified by choline acetyltransferase promoter-derived Cre expression. In the spinal dorsal horn, OCT2 was distributed in superficial to deep laminae. OCT2 immunoreactivity was punctate in appearance and localized in the nerve terminals of sensory afferents with labeling of neurochemical markers. Our findings suggest that OCT2 as a low-affinity, high-capacity carrier may take up substrates including cationic neurotransmitters and drugs from the extracellular space around cell bodies in DRG neurons.

PPARα-Dependent Modulation by Metformin of the Expression of OCT-2 and MATE-1 in the Kidney of Mice.

Metformin is the first-line drug for type 2 diabetes mellitus control. It is established that this drug traffics through OCT-2 and MATE-1 transporters in kidney tubular cells and is excreted in its unaltered form in the urine. Hereby, we provide evidence that points towards the metformin-dependent upregulation of OCT-2 and MATE-1 in the kidney via the transcription factor proliferator-activated receptor alpha (PPARα). Treatment of wild type mice with metformin led to the upregulation of the expression of OCT-2 and MATE-1 by 34% and 157%, respectively. An analysis in a kidney tubular cell line revealed that metformin upregulated PPARα and OCT-2 expression by 37% and 299% respectively. MK-886, a PPARα antagonist, abrogated the OCT-2 upregulation by metformin and reduced MATE-1 expression. Conversely, gemfibrozil, an agonist of PPARα, elicited the increase of PPARα, OCT-2, and MATE-1 expression by 115%, 144%, and 376%, respectively. PPARα knockout mice failed to upregulate both the expression of OCT-2 and MATE-1 in the kidney upon metformin treatment, supporting the PPARα-dependent metformin upregulation of the transporters in this organ. Taken together, our data sheds light on the metformin-induced mechanism of transporter modulation in the kidney, via PPARα, and this effect may have implications for drug safety and efficacy.

Relationship between changes in the exon-recognition machinery and SLC22A1 alternative splicing in hepatocellular carcinoma

Changes in the phenotype that characterizes cancer cells are partly due to altered processing of pre-mRNA by the spliceosome. We have previously reported that aberrant splicing plays an essential role in the impaired response of hepatocellular carcinoma (HCC) to sorafenib by reducing the expression of functional organic cation transporter type 1 (OCT1, gene SLC22A1) that constitutes the primary way for HCC cells to take up this and other drugs. The present study includes an in silico analysis of publicly available databases to investigate the relationship between alternative splicing of SLC22A1 pre-mRNA and the expression of genes involved in the exon-recognition machinery in HCC and adjacent non-tumor tissue. Using Taqman Low-Density Arrays, the findings were validated in 25 tumors that were resected without neoadjuvant chemotherapy. The results supported previous reports showing that there was a considerable degree of alternative splicing of SLC22A1 in adjacent non-tumor tissue, which was further increased in the tumor in a stage-unrelated manner. Splicing perturbation was associated with changes in the profile of proteins determining exon recognition. The results revealed the importance of using paired samples for splicing analysis in HCC and confirmed that aberrant splicing plays an essential role in the expression of functional OCT1. Changes in the exon recognition machinery may also affect the expression of other proteins in HCC. Moreover, these results pave the way to further investigations on the mechanistic bases of the relationship between the expression of spliceosome-associated genes and its repercussion on the appearance of alternative and aberrant splicing in HCC.

Stem cells from trabecular meshwork cells can secrete extracellular matrix

Isolation of trabecular meshwork stem cells in vitro provides the foundation of a novel treatment for glaucoma. Trabecular meshwork stem cells (TMSCs) of the fetal calve were extracted and cultured for this experiment. TMSCs were isolated through side population cell sorting. TMSCs were then identified using immunofluorescent staining. Extracellular matrix (ECM) expression in TM cells derived from TMSCs was evaluated with Western blot. Our results showed a positive expression of stem cell markers Notch1 and OCT-3/4 in TMSCs, but no TM cells markers TIMP3 or AQP1. In contrast, primary TM cells expressed these TM cell markers but no stem cell markers. Our result confirmed that there are expression of ECM components, such as fibronectin, laminin, collagen I and collagen IV in TM cells differentiated from TMSCs. ConclusionTM cells derived from TMSCs can secrete ECM components which is important for sustain the physiological function.

Abundant Expression of OCT2, MATE1, OAT1, OAT3, PEPT2, BCRP, MDR1, and xCT Transporters in Blood-Arachnoid Barrier of Pig and Polarized Localizations at CSF- and Blood-Facing Plasma Membranes.

The physiologic and pharmacologic roles of the blood-arachnoid barrier (BAB) remain unclear. Therefore, the purpose of the present study was to comprehensively evaluate and compare the absolute protein expression levels of transporters in the leptomeninges and plexus per cerebrum, and to determine the localizations of transporters at the cerebrospinal fluid (CSF)-facing and blood (dura)-facing plasma membranes of the BAB in pig. Using multidrug resistance protein 1 (MDR1) and organic anion transporter (OAT) 1 as blood (dura)-facing and CSF-facing plasma membrane marker proteins, respectively, we established that breast cancer resistance protein (BCRP), multidrug resistance-associated protein (MRP) 4, organic anion-transporting polypeptide (OATP) 2B1, multidrug and toxin extrusion protein 1 (MATE1), and glucose transporter 1 (GLUT1) are localized at the blood-facing plasma membrane, and OAT3, peptide transporter (PEPT) 2, MRP3, organic cation transporter (OCT) 2, xCT, monocarboxylate transporter (MCT) 1, MCT4, and MCT8 are localized at the CSF-facing plasma membrane of the BAB. The absolute protein expression levels of OAT1, OAT3, MDR1, BCRP, PEPT2, xCT, MATE1, OCT2, and 4f2hc in the whole BAB surrounding the entire cerebrum were much larger than those in the total of the choroid plexuses forming the blood-cerebrospinal fluid barrier (BCSFB). Although MRP4, OATP2B1, MCT8, GLUT1, and MCT1 were also statistically significantly more abundant in the BAB than in the choroid plexuses per porcine cerebrum, these transporters were nevertheless almost equally distributed between the two barriers. In contrast, OATP1A2, MRP1, OATP3A1, and OCTN2 were specifically expressed in the choroid plexus. These results should be helpful in understanding the relative overall importance of transport at the BAB compared with that at the BCSFB, as well as the rank order of transport capacities among different transporters at the BAB, and the directions of transport mediated by individual transporters. SIGNIFICANCE STATEMENT: We found that BCRP, MRP4, OATP2B1, MATE1, and GLUT1 localize at the blood-facing plasma membrane of the blood-arachnoid barrier (BAB), while OAT3, PEPT2, MRP3, OCT2, xCT, MCT1, MCT4, and MCT8 localize at the CSF-facing plasma membrane. 4F2hc is expressed in both membranes. For OAT1, OAT3, MDR1, BCRP, PEPT2, xCT, MATE1, OCT2, and 4f2hc, the absolute protein expression levels in the whole BAB surrounding the entire cerebrum are much greater than the total amounts in the choroid plexuses.

Pharmacokinetic Interaction of Green Rooibos Extract With Atorvastatin and Metformin in Rats.

An aspalathin-rich green rooibos extract (Afriplex GRT™) has demonstrated anti-diabetic and hypolipidemic properties, while also moderately inhibiting CYP3A4 activity, suggesting a potential for herb–drug interaction. The present study, therefore, evaluated the effects of orally administered GRT on the pharmacokinetics of atorvastatin and metformin in Wistar rats. Wistar rats were orally treated with GRT (50 mg/kg BW), atorvastatin (40 mg/kg BW) or metformin (150 mg/kg BW) alone or 50 mg/kg BW GRT in combination with 40 mg/kg BW atorvastatin or 150 mg/kg BW metformin. Blood samples were collected at 0, 10, and 30 min and 1, 2, 4, 6, and 8 h and plasma samples obtained for Liquid chromatography-mass spectrometry (LC-MS/MS) analyses. Non-compartment and two-compartment pharmacokinetic parameters of atorvastatin and metformin in the presence or absence of GRT were determined by PKSolver version 2.0 software. Membrane transporter proteins, ATP-binding cassette sub-family C member 2 (Abcc2), solute carrier organic anion transporter family, member 1b2 (Slco1b2), ATP-binding cassette, sub-family B (MDR/TAP), member 1A (Abcb1a), and organic cation transporter 1 (Oct1) mRNA expression were determined using real-time PCR expression data normalized to β-actin and hypoxanthine-guanine phosphoribosyltransferase (HPRT), respectively. Co-administration of GRT with atorvastatin substantially increased the maximum plasma concentration (Cmax) and area of the plasma concentration–time curve (AUC0-8) of atorvastatin by 5.8-fold (p = 0.03) and 5.9-fold (p = 0.02), respectively. GRT had no effect on the plasma levels of metformin. GRT increased Abcc2 expression and metformin downregulated Abcb1a expression while the combination of GRT with atorvastatin or metformin did not significantly alter the expression of Slco1b1 or Oct1 did not significantly alter the expression of Sclo1b2 or Oct1. Co-administration of GRT with atorvastatin in rats may lead to higher plasma concentrations and, therefore, to an increase of the exposure to atorvastatin.

Fisetin, via CKIP-1/REGγ, limits oxidized LDL-induced lipid accumulation and senescence in RAW264.7 macrophage-derived foam cells

To test the hypothesis that the flavonoid compound, fisetin, protects macrophages from lipid accumulation and senescence through regulation of casein kinase 2-interacting protein-1 (CKIP-1)/REGγ (11S regulatory particles, 28 kDa proteasome activator, proteasome activator subunit 3) signaling. RAW264.7 macrophage cells were exposed to 100 μg/ml oxidized low-density lipoprotein (ox-LDL) with or without 20 μg/ml fisetin for 24 h. Cell viability was detected by CCK-8 after 1 h. Intracellular lipid accumulation was measured using Oil Red O staining. Total cholesterol (TC) and free cholesterol (FC) contents were measured using assay kits, and cell senescence was inferred by β-gal staining. Protein expression levels of CKIP-1, REGγ, organic cation transporter 1 (Oct-1), lectin-like oxidized LDL receptor-1 (LOX-1), tumor suppressor protein p53 (p53), cell cycle regulatory protein p21 (p21), and multiple tumor suppressor-1 (p16) were detected by immunofluorescence and confirmed by Western blot. Stimulating RAW264.7 macrophage cells with 100 μg/ml ox-LDL for 24 h induced the formation of foam cells, increased intracellular lipid accumulation, increased TC and FC content, and promoted cell senescence. Furthermore, cells induced with 100 μg/ml ox-LDL for 24 h showed decreased CKIP-1 and REGγ protein, while the expressions of Oct-1, LOX-1, p53, p21 and p16 were increased. In contrast, treatment with 20 μg/ml fisetin reversed 100 μg/ml ox-LDL effects to increase cell viability, and decrease β-gal staining, intracellular lipid levels and TC and FC levels. These beneficial effects were associated with increased CKIP-1 and REGγ and decreased Oct-1, LOX-1, p53, p21, and p16 protein expression. Results indicated that fisetin limited ox-LDL-mediated lipid accumulation and senescence in RAW264.7 macrophage-derived foam cells. The mechanism underlying these effects may involve regulation of CKIP-1/REGγ signaling.

Key role of organic cation transporter 2 for the nephrotoxicity effect of triptolide in rheumatoid arthritis

Tripterygium wilfordii Hook. F. (TwHF), a traditional Chinese Medicine, is effective in treating rheumatoid arthritis (RA), but its severe nephrotoxicity limits its extensive application. The nephrotoxic mechanism of Triptolide (TP), the main pharmacological and toxic component of TwHF, has not been fully revealed. This study was designed to explore the nephrotoxicity of TP in the RA state and the potential molecular mechanism. A rat collagen-induced arthritis (CIA) model was constructed and administered with TP for 28 days in vivo. Results showed that the kidney injury induced by TP was aggravated in the CIA state, the concentration of TP in the renal cortex was higher than that of the medulla after TP administration in the CIA rats, and the expression of organic cation transporter 2 (Oct2) in kidney was up-regulated under CIA condition. Besides, rat kidney slice study demonstrated that TP was transported by Oct2 and this was confirmed by transient silencing and overexpression of OCT2 in HEK-293T cells. Furthermore, cytoinflammatory models on HK-2 and HEK-293T cell lines were constructed by exposure of TNF-α or IL-1β to further explore the TP’s renal toxicity. Results suggested that TNF-α exposure aggravated TP’s toxicity and up-regulated the protein expression of OCT2 in both cell lines. TNF-α treatment also increased the function of OCT2 and finally OCT2 silencing confirmed OCT2 mediated nephrotoxicity of TP in HEK-293T cells. In summary, the exposure of TNF-α in RA state induced the expression of OCT2, which transported more TP into kidney cortex, subsequently exacerbated the kidney injury.