Downregulation of organic cation transporter 1 (SLC22A1) is associated with tumor progression and reduced patient survival in human cholangiocellular carcinoma

In Vitro and In Silico Studies on Cytotoxic Properties of Oxythiamine and 2'-Methylthiamine

It is important to search for cytostatic compounds in order to fight cancer. One of them could be 2'-methylthiamine, which is a thiamine antimetabolite with an additional methyl group at the C-2 carbon of thiazole. So far, the cytostatic potential of 2'-methylthiamine has not been studied. We have come forward with a simplified method of synthesis using commercially available substrates and presented a comparison of its effects, as boosted by oxythiamine, on normal skin fibroblasts and HeLa cancer cells, having adopted in vitro culture techniques. Oxythiamine has been found to inhibit the growth and metabolism of cancer cells significantly better than 2'-methylthiamine (GI50 36 and 107 µM, respectively), while 2'-methylthiamine is more selective for cancer cells than oxythiamine (SI = 180 and 153, respectively). Docking analyses have revealed that 2'-methylthiamine (ΔG -8.2 kcal/mol) demonstrates a better affinity with thiamine pyrophosphokinase than thiamine (ΔG -7.5 kcal/mol ) and oxythiamine (ΔG -7.0 kcal/mol), which includes 2'-methylthiamine as a potential cytostatic. Our results suggest that the limited effect of 2'-methylthiamine on HeLa arises from the related arduous transport as compared to oxythiamine. Given that 2'-methylthiamine may possibly inhibit thiamine pyrophosphokinase, it could once again be considered a potential cytostatic. Thus, research should be carried out in order to find the best way to improve the transport of 2'-methylthiamine into cells, which may trigger its cytostatic properties.

Impact of liver diseases and pharmacological interactions on the transportome involved in hepatic drug disposition

The liver plays a pivotal role in drug disposition owing to the expression of transporters accounting for the uptake at the sinusoidal membrane and the efflux across the basolateral and canalicular membranes of hepatocytes of many different compounds. Moreover, intracellular mechanisms of phases I and II biotransformation generate, in general, inactive compounds that are more polar and easier to eliminate into bile or refluxed back toward the blood for their elimination by the kidneys, which becomes crucial when the biliary route is hampered. The set of transporters expressed at a given time, i.e., the so-called transportome, is encoded by genes belonging to two gene superfamilies named Solute Carriers (SLC) and ATP-Binding Cassette (ABC), which account mainly, but not exclusively, for the uptake and efflux of endogenous substances and xenobiotics, which include many different drugs. Besides the existence of genetic variants, which determines a marked interindividual heterogeneity regarding liver drug disposition among patients, prevalent diseases, such as cirrhosis, non-alcoholic steatohepatitis, primary sclerosing cholangitis, primary biliary cirrhosis, viral hepatitis, hepatocellular carcinoma, cholangiocarcinoma, and several cholestatic liver diseases, can alter the transportome and hence affect the pharmacokinetics of drugs used to treat these patients. Moreover, hepatic drug transporters are involved in many drug-drug interactions (DDI) that challenge the safety of using a combination of agents handled by these proteins. Updated information on these questions has been organized in this article by superfamilies and families of members of the transportome involved in hepatic drug disposition.

Role of organic cation transporter 3 (OCT3) in the response of hepatocellular carcinoma to tyrosine kinase inhibitors

Impaired function of organic cation transporter 1 (OCT1) in hepatocellular carcinoma (HCC) has been associated with unsatisfactory response to sorafenib. However, some patients lacking OCT1 at the plasma membrane (PM) of HCC cells still respond to sorafenib, suggesting that another transporter may contribute to take up this drug. The aim of this study was to investigate whether OCT3 could contribute to the uptake of sorafenib and other tyrosine kinase inhibitors (TKIs) and whether OCT3 determination can predict HCC response to sorafenib. Cells overexpressing OCT3 were used to determine the ability of this carrier to transport sorafenib. Immunostaining of OCT3 was performed in HCC samples obtained in the TRANSFER study. Considering the intensity of staining and the number of OCT3-positive cells, tumors were classified as having absent, weak, moderate, or strong OCT3 expression and were also categorized according to the presence or absence of PM staining. Functional in vitro studies revealed that OCT3 is also able to mediate sorafenib uptake. Other TKIs, such as regorafenib, lenvatinib, and cabozantinib can also interact with this transporter. In silico studies suggested that the expression of OCT3 is better preserved in HCC than that of OCT1. In HCC samples, OCT3 was expressed at the PM of cancer cells, and its presence, detected in 26% of tumors, was associated with better outcomes in patients treated with sorafenib. In conclusion, analysis by immunohistochemistry of OCT3 in the PM of tumor cells may help to predict the response of HCC patients to sorafenib and potentially to other TKIs.

Transcriptome analysis reveals the regulatory effects of Bacillus amyloliquefaciens and Bacillus pumilus on immune and digestive related genes in the spleen of weanling black goats

The aim of the present study was to evaluate the effects of Bacillus amyloliquefaciens fsznc-06 and Bacillus pumilus fsznc-09 on the expressions of spleen genes in weanling Jintang black goats. Bacillus amyloliquefaciens fsznc-06 (BA-treated group) and Bacillus pumilus fsznc-09 (BP-treated group) were directly fed to goats, and the spleens were harvested for transcriptome analysis. The KEGG pathway analysis showed that the differentially expressed genes (DEGs) in BA-treated vs CON group were mainly involved in digestive system and immune system, while those in BP-treated vs CON group were mainly involved in immune system, and those in BA-treated vs BP-treated group were mainly involved in digestive system. In conclusion, Bacillus amyloliquefaciens fsznc-06 might promote the expressions of genes related to immune system and digestive system, reduce the expressions of disease genes related to digestive system and might promote mutual accommodation of some immune genes in weanling black goat. Bacillus pumilus fsznc-09 might promote the expressions of genes related to immune system and mutual accommodation of some immune genes in weanling black goat. Bacillus amyloliquefaciens fsznc-06 has advantages over Bacillus pumilus fsznc-09 in promoting the expressions of genes related to digestive system and mutual accommodation of some immune genes.

The Role of Solute Carrier Transporters in Efficient Anticancer Drug Delivery and Therapy

Transporter-mediated drug resistance is a major obstacle in anticancer drug delivery and a key reason for cancer drug therapy failure. Membrane solute carrier (SLC) transporters play a crucial role in the cellular uptake of drugs. The expression and function of the SLC transporters can be down-regulated in cancer cells, which limits the uptake of drugs into the tumor cells, resulting in the inefficiency of the drug therapy. In this review, we summarize the current understanding of low-SLC-transporter-expression-mediated drug resistance in different types of cancers. Recent advances in SLC-transporter-targeting strategies include the development of transporter-utilizing prodrugs and nanocarriers and the modulation of SLC transporter expression in cancer cells. These strategies will play an important role in the future development of anticancer drug therapies by enabling the efficient delivery of drugs into cancer cells.

The Role of Organic Cation Transporters in the Pharmacokinetics, Pharmacodynamics and Drug-Drug Interactions of Tyrosine Kinase Inhibitors

Tyrosine kinase inhibitors (TKIs) decisively contributed in revolutionizing the therapeutic approach to cancer, offering non-invasive, tolerable therapies for a better quality of life. Nonetheless, degree and duration of the response to TKI therapy vary depending on cancer molecular features, the ability of developing resistance to the drug, on pharmacokinetic alterations caused by germline variants and unwanted drug-drug interactions at the level of membrane transporters and metabolizing enzymes. A great deal of approved TKIs are inhibitors of the organic cation transporters (OCTs). A handful are also substrates of them. These transporters are polyspecific and highly expressed in normal epithelia, particularly the intestine, liver and kidney, and are, hence, arguably relevant sites of TKI interactions with other OCT substrates. Moreover, OCTs are often repressed in cancer cells and might contribute to the resistance of cancer cells to TKIs. This article reviews the OCT interactions with approved and in-development TKIs reported in vitro and in vivo and critically discusses the potential clinical ramifications thereof.

Bile duct ligation differently regulates protein expressions of organic cation transporters in intestine, liver and kidney of rats through activation of farnesoid X receptor by cholate and bilirubin

Body is equipped with organic cation transporters (OCTs). These OCTs mediate drug transport and are also involved in some disease process. We aimed to investigate whether liver failure alters intestinal, hepatic and renal Oct expressions using bile duct ligation (BDL) rats. Pharmacokinetic analysis demonstrates that BDL decreases plasma metformin exposure, associated with decreased intestinal absorption and increased urinary excretion. Western blot shows that BDL significantly downregulates intestinal Oct2 and hepatic Oct1 but upregulates renal and hepatic Oct2. In vitro cell experiments show that chenodeoxycholic acid (CDCA), bilirubin and farnesoid X receptor (FXR) agonist GW4064 increase OCT2/Oct2 but decrease OCT1/Oct1, which are remarkably attenuated by glycine-β-muricholic acid and silencing FXR. Significantly lowered intestinal CDCA and increased plasma bilirubin levels contribute to different Octs regulation by BDL, which are confirmed using CDCA-treated and bilirubin-treated rats. A disease-based physiologically based pharmacokinetic model characterizing intestinal, hepatic and renal Octs was successfully developed to predict metformin pharmacokinetics in rats. In conclusion, BDL remarkably downregulates expressions of intestinal Oct2 and hepatic Oct1 protein while upregulates expressions of renal and hepatic Oct2 protein in rats, finally, decreasing plasma exposure and impairing hypoglycemic effects of metformin. BDL differently regulates Oct expressions via Fxr activation by CDCA and bilirubin.

Allele-specific regulatory effects on the pig transcriptome

BACKGROUND

Allele-specific expression (ASE) refers to the preferential expression of one allele over the other and contributes to adaptive phenotypic plasticity. Here, we used a reciprocal cross-model between phenotypically divergent European Berkshire and Asian Tibetan pigs to characterize 2 ASE classes: imprinting (i.e., the unequal expression between parental alleles) and sequence dependent (i.e., unequal expression between breed-specific alleles). We examined 3 transcript types, including protein-coding genes (PCGs), long noncoding RNAs, and transcripts of unknown coding potential, across 7 representative somatic tissues from hybrid pigs generated by reciprocal crosses.

RESULTS

We identified a total of 92 putative imprinted transcripts, 69 (75.00%) of which are described here for the first time. By combining the transcriptome from purebred Berkshire and Tibetan pigs, we found ∼6.59% of PCGs are differentially expressed between breeds that are regulated by trans-elements (e.g., transcriptional factors), while only ∼1.35% are attributable to cis (e.g., promoters). The higher prevalence of trans-PCGs indicates the dominated effects of trans-regulation in driving expression differences and shaping adaptive phenotypic plasticity between breeds, which were supported by functional enrichment analysis. We also found strong evidence that expression changes mediated by cis-effects were associated with accumulated variants in promoters.

CONCLUSIONS

Our study provides a comprehensive map of expression regulation that constitutes a valuable resource for the agricultural improvement of pig breeds.

Overcome Drug Resistance in Cholangiocarcinoma: New Insight Into Mechanisms and Refining the Preclinical Experiment Models

Cholangiocarcinoma (CCA) is an aggressive tumor characterized by a poor prognosis. Therapeutic options are limited in patients with advanced stage of CCA, as a result of the intrinsic or acquired resistance to currently available chemotherapeutic agents, and the lack of new drugs entering into clinical application. The challenge in translating basic research to the clinical setting, caused by preclinical models not being able to recapitulate the tumor characteristics of the patient, seems to be an important reason for the lack of effective and specific therapies for CCA. So, there seems to be two ways to improve patient outcomes. The first one is developing the combination therapies based on a better understanding of the mechanisms contributing to the resistance to currently available chemotherapeutic agents. The second one is developing novel preclinical experimental models that better recapitulate the genetic and histopathological features of the primary tumor, facilitating the screening of new drugs for CCA patients. In this review, we discussed the evidence implicating the mechanisms underlying treatment resistance to currently investigated drugs, and the development of preclinical experiment models for CCA.

Expression and clinical significance of organic cation transporter family in glioblastoma multiforme

BACKGROUND

Solute carrier (SLC) 22 A1, A2, and A3 are polyspecific transporters transporting organic cations like histamine, serotonin, norepinephrine, dopamine, MPP + , and toxins. The expression of SLC22A1-A3 in cancer is seldom investigated, and the function of SLC22A1-A3 in glioblastoma multiforme (GBM) is never elucidated.

MATERIALS

In our study, we detected the expression of SLC22A1-A3 in 11 fresh GBMs and tumor-adjacent brain tissues with qPCR, and in 129 paraffin-embedded GBMs with immunohistochemistry (IHC). With chi-square test, we investigated the correlation between expression of SLC22A1-A3 and the clinicopathological factors including patients' age, sex, tumor size, and KPS score. With Kaplan-Meier method and Cox-regression model, we estimated the prognostic significance of SLC22A1-A3 in GBM.

RESULTS

SLC22A3 was significantly downregulated in GBMs compared with the tumor-adjacent normal tissues. With univariate survival analyses, we showed that SLC22A3, instead of SLC22A1 and A2, was an independent biomarker predicting favorable prognosis. With multivariate analyses, SLC22A3 was identified as an independent prognostic biomarker indicating the favorable outcome of GBM.

CONCLUSIONS

SLC22A3 is an independent favorable prognostic biomarker of GBM. Patients with low SLC22A3 may be more high-risk and should receive more intensive post-operational supervision and treatments.

A guide to plasma membrane solute carrier proteins

This review aims to serve as an introduction to the solute carrier proteins (SLC) superfamily of transporter proteins and their roles in human cells. The SLC superfamily currently includes 458 transport proteins in 65 families that carry a wide variety of substances across cellular membranes. While members of this superfamily are found throughout cellular organelles, this review focuses on transporters expressed at the plasma membrane. At the cell surface, SLC proteins may be viewed as gatekeepers of the cellular milieu, dynamically responding to different metabolic states. With altered metabolism being one of the hallmarks of cancer, we also briefly review the roles that surface SLC proteins play in the development and progression of cancer through their influence on regulating metabolism and environmental conditions.

Influence of YES1 Kinase and Tyrosine Phosphorylation on the Activity of OCT1

Organic cation transporter 1 (OCT1) is a transporter that regulates the hepatic uptake and subsequent elimination of diverse cationic compounds. Although OCT1 has been involved in drug-drug interactions and causes pharmacokinetic variability of many prescription drugs, details of the molecular mechanisms that regulate the activity of OCT1 remain incompletely understood. Based on an unbiased phospho-proteomics screen, we identified OCT1 as a tyrosine-phosphorylated transporter, and functional validation studies using genetic and pharmacological approaches revealed that OCT1 is highly sensitive to small molecules that target the protein kinase YES1, such as dasatinib. In addition, we found that dasatinib can inhibit hepatic OCT1 function in mice as evidenced from its ability to modulate levels of isobutyryl L-carnitine, a hepatic OCT1 biomarker identified from a targeted metabolomics analysis. These findings provide novel insight into the post-translational regulation of OCT1 and suggest that caution is warranted with polypharmacy regimes involving the combined use of OCT1 substrates and kinase inhibitors that target YES1.

Drug-Drug Interactions at Organic Cation Transporter 1

The interaction between drugs and various transporters is one of the decisive factors that affect the pharmacokinetics and pharmacodynamics of drugs. The organic cation transporter 1 (OCT1) is a member of the Solute Carrier 22A (SLC22A) family that plays a vital role in the membrane transport of organic cations including endogenous substances and xenobiotics. This article mainly discusses the drug-drug interactions (DDIs) mediated by OCT1 and their clinical significance.

Functional inhibition of Oct leads to HNF4α upregulation

Organic cation transporters (human, OCT; mouse, Oct) are responsible for the intracellular uptake and detoxification of a broad spectrum of endogenous and exogenous substrates. The OCT1 gene SLC22A1 (human; mouse, Scl22a1) is transactivated by hepatocyte nuclear factor 4α (human, HNF4α; mouse, Hnf4α). HNF4α is a master regulator of hepatocyte differentiation and is frequently associated with hepatocellular carcinoma (HCC). In addition, the downregulation of HNF4α is associated with enhanced fibrogenesis. Our recent study revealed that hepatocarcinogenesis and fibrosis were enhanced with the loss of Oct3 (gene, Slc22a3). Notably, differences in Hnf4α expression, and in cholestasis and fibrosis were also detected in Oct3-knockout (FVB.Slc22a3tm10pb, Oct3^-/-) mice. To the best of our knowledge, no data exists on an interaction between Oct3 and Hnf4α. We hypothesised that loss of Oct3 may have an impact on Hnf4α expression. In the present study, gene expression analyses were performed in liver tissue from untreated Oct3^-/- and wild type (FVB, WT) mice. C57BL/6, Oct3^-/- and WT mice were treated with pro-fibrotic carbon tetrachloride (CCl₄) or thioacetamide (TAA) for 6 weeks to chemically induce liver fibrosis. Cholestasis-associated fibrosis was mechanically generated in Oct3^-/- and WT mice by bile duct ligation (BDL). Finally, stably OCT1- and OCT3-transfected tumour cell lines and primary murine hepatocytes were treated with the non-selective OCT inhibitor quinine and Hnf4α expression was quantified by qPCR and immunofluorescence. The results revealed that Hnf4α is one of the top upstream regulators in Oct3^-/- mice. Hnf4α mRNA expression levels were downregulated in Oct3^-/- mice compared with in WT mice during cholestatic liver damage as well as fibrogenesis. The downregulation of Hnf4α mRNA expression in fibrotic liver tissue was reversible within 4 weeks. In stably OCT1- and OCT3-transfected HepG2 and HuH7 cells, and primary murine hepatocytes, functional inhibition of OCT led to the upregulation of Hnf4α mRNA expression. Hnf4α was revealed to be located in the cytosol of WT hepatocytes, whereas Oct3^-/- hepatocytes exhibited nuclear Hnf4α expression. In conclusion, Hnf4α was downregulated in response to cholestasis and fibrosis, and functional inhibition of Oct may lead to the upregulation of Hnf4α.

Regulation Mechanisms of Expression and Function of Organic Cation Transporter 1

The organic cation transporter 1 (OCT1) belongs together with OCT2 and OCT3 to the solute carrier family 22 (SLC22). OCTs are involved in the movement of organic cations through the plasma membrane. In humans, OCT1 is mainly expressed in the sinusoidal membrane of hepatocytes, while in rodents, OCT1 is strongly represented also in the basolateral membrane of renal proximal tubule cells. Considering that organic cations of endogenous origin are important neurotransmitters and that those of exogenous origin are important drugs, these transporters have significant physiological and pharmacological implications. Because of the high expression of OCTs in excretory organs, their activity has the potential to significantly impact not only local but also systemic concentration of their substrates. Even though many aspects governing OCT function, interaction with substrates, and pharmacological role have been extensively investigated, less is known about regulation of OCTs. Possible mechanisms of regulation include genetic and epigenetic modifications, rapid regulation processes induced by kinases, regulation caused by protein–protein interaction, and long-term regulation induced by specific metabolic and pathological situations. In this mini-review, the known regulatory processes of OCT1 expression and function obtained from in vitro and in vivo studies are summarized. Further research should be addressed to integrate this knowledge to known aspects of OCT1 physiology and pharmacology.

Cholangiocarcinoma 2020: the next horizon in mechanisms and management

Cholangiocarcinoma (CCA) includes a cluster of highly heterogeneous biliary malignant tumours that can arise at any point of the biliary tree. Their incidence is increasing globally, currently accounting for ~15% of all primary liver cancers and ~3% of gastrointestinal malignancies. The silent presentation of these tumours combined with their highly aggressive nature and refractoriness to chemotherapy contribute to their alarming mortality, representing ~2% of all cancer-related deaths worldwide yearly. The current diagnosis of CCA by non-invasive approaches is not accurate enough, and histological confirmation is necessary. Furthermore, the high heterogeneity of CCAs at the genomic, epigenetic and molecular levels severely compromises the efficacy of the available therapies. In the past decade, increasing efforts have been made to understand the complexity of these tumours and to develop new diagnostic tools and therapies that might help to improve patient outcomes. In this expert Consensus Statement, which is endorsed by the European Network for the Study of Cholangiocarcinoma, we aim to summarize and critically discuss the latest advances in CCA, mostly focusing on classification, cells of origin, genetic and epigenetic abnormalities, molecular alterations, biomarker discovery and treatments. Furthermore, the horizon of CCA for the next decade from 2020 onwards is highlighted.

Uptake Transporters of the SLC21, SLC22A, and SLC15A Families in Anticancer Therapy-Modulators of Cellular Entry or Pharmacokinetics?

Solute carrier transporters comprise a large family of uptake transporters involved in the transmembrane transport of a wide array of endogenous substrates such as hormones, nutrients, and metabolites as well as of clinically important drugs. Several cancer therapeutics, ranging from chemotherapeutics such as topoisomerase inhibitors, DNA-intercalating drugs, and microtubule binders to targeted therapeutics such as tyrosine kinase inhibitors are substrates of solute carrier (SLC) transporters. Given that SLC transporters are expressed both in organs pivotal to drug absorption, distribution, metabolism, and elimination and in tumors, these transporters constitute determinants of cellular drug accumulation influencing intracellular drug concentration required for efficacy of the cancer treatment in tumor cells. In this review, we explore the current understanding of members of three SLC families, namely SLC21 (organic anion transporting polypeptides, OATPs), SLC22A (organic cation transporters, OCTs; organic cation/carnitine transporters, OCTNs; and organic anion transporters OATs), and SLC15A (peptide transporters, PEPTs) in the etiology of cancer, in transport of chemotherapeutic drugs, and their influence on efficacy or toxicity of pharmacotherapy. We further explore the idea to exploit the function of SLC transporters to enhance cancer cell accumulation of chemotherapeutics, which would be expected to reduce toxic side effects in healthy tissue and to improve efficacy.

The human organic cation transporter OCT1 and its role as a target for drug responses

The human organic cation uptake transporter OCT1, encoded by the SLC22A1 gene, is highly expressed in the liver and reported to possess a broad substrate specificity. OCT1 operates by facilitated diffusion and allows the entry of nutrients into cells. Recent findings revealed that OCT1 can mediate the uptake of drugs for treating various diseases such as cancers. The levels of OCT1 expression correlate with the responses towards many drugs and functionally defective OCT1 lead to drug resistance. It has been recently proposed that OCT1 should be amongst the crucial drug targets used for pharmacogenomic analyses. Several single nucleotide polymorphisms exist and are distributed across the entire OCT1 gene. While there are differences in the OCT1 gene polymorphisms between populations, there are at least five variants that warrant consideration in any genetic screen. To date, and despite two decades of research into OCT1 functional role, it still remains uncertain what are the define substrates for this uptake transporter, although studies from mice revealed that one of the substrates is vitamin B1. It is also unclear how OCT1 recognizes a broad array of ligands and whether this involves specific modifications and interactions with other proteins. In this review, we highlight the current findings related to OCT1 with the aim of propelling further studies on this key uptake transporter.

Role of transportome in the pharmacogenomics of hepatocellular carcinoma and hepatobiliary cancer

An important factor determining the pharmacological response to antitumor drugs is their concentrations in cancer cells, which accounts for the net interaction with their intracellular molecular targets. Accordingly, mechanisms leading to reduced intracellular levels of active agents play a crucial role in cancer chemoresistance. These include impaired drug uptake through solute carrier (SLC) proteins and efficient drug export by ATP-dependent pumps belonging to the ATP-binding cassette (ABC) superfamily of proteins. Since the net movement of drugs in-and-out the cells depends on the overall expression of carrier proteins, defining the so-called transportome, special attention has been devoted to the study of transcriptome regarding these proteins. Nevertheless, genetic variants affecting SLC and ABC genes may markedly affect the bioavailability and, hence, the efficacy of anticancer drugs.

Deletion of organic cation transporter Oct3 promotes hepatic fibrosis via upregulation of TGFβ

Organic cation transporters (OCT) are responsible for the intracellular uptake and detoxification of a broad spectrum of endogenous and exogenous substrates. OCTs are downregulated in cholestasis, fibrosis, and hepatocellular carcinoma, but the underlying molecular mechanisms and downstream effects of OCT deletion are unknown. Oct3-knockout (Oct3^-/-; FVB.Slc22a3^tm10pb) and wild-type (WT; FVB) mice were subject to escalating doses of carbon tetrachloride (CCl₄) or thioacetamide (TAA) for 6 wk to induce advanced parenchymal liver fibrosis. Secondary biliary fibrosis was generated by bile duct ligation. Liver fibrosis was assessed by hydroxyproline determination, quantitative Sirius red morphometry, and quantitative real-time PCR for fibrosis and inflammation-related genes. Ductular reaction was assessed by bile duct count per field of view in hematoxylin and eosin staining. General gene expression analyses were performed in liver tissue from untreated Oct3^-/- and WT mice. Finally, primary murine hepatocytes were treated with the nonselective OCT inhibitor quinine, and transforming growth factor-β1 (Tgfβ1) protein expression was quantified by quantitative real-time PCR and Western blot. Oct3^-/- mice developed significantly more fibrosis after bile duct ligation and CCl₄ treatment compared with WT mice. Ductular reaction was enhanced in the long-term model. Concomitantly, Oct1 mRNA expression was downregulated during cholestatic and chemically (TAA and CCl₄) induced fibrogenesis. The downregulation of Oct1 mRNA in fibrotic liver tissue reversed within 4 wk after TAA cessation. Gene expression analysis by next-generation sequencing revealed an enrichment of Tgfβ1 target genes in Oct3^-/- mice. Tgfβ1 mRNA expression was significantly upregulated after chemically induced fibrosis (P < 0.001) in Oct3^-/- compared with WT mice. Accordingly, in primary murine hepatocytes functional inhibition of OCT led to an upregulation of Tgfβ1 mRNA expression. Loss of Oct3 promotes fibrogenesis by affecting Tgfβ-mediated homeostasis in mice with chronic biliary and parenchymal liver damage and fibrosis.NEW & NOTEWORTHY We show for the first time that organic cation transporter 3 (Oct3) is not only downregulated in fibrosis but loss of Oct3 also leads to an upregulation of transforming growth factor-β contributing to fibrosis progression.

Role of OCT1 in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most commonly diagnosed cancers causing death worldwide. It is difficult to detect at an early stage and most patients with advanced HCC rarely achieve satisfying therapeutic results. Accordingly, researchers have been trying to find new biomarkers for diagnosis and new methods of treatment. OCT1, a member of solute carrier super family, is highly expressed in normal liver tissues, and predominantly transports endogenous and exogenous substances, such as metabolites, drugs and toxins to hepatocytes. Studies have demonstrated that the expression of OCT1 is related to the progression and survival of HCC patients. Furthermore, sorafenib, which is regarded as the only effective molecular targeting drug for advanced HCC, is affected by OCT1 variants. In the current review, we summarized the reports about OCT1 and HCC in order to present a comprehensive overview of the relationship between OCT1 and HCC.

Association between Polymorphisms of OCT1 and Metabolic Response to Metformin in Women with Polycystic Ovary Syndrome

Insulin-sensitizer treatment with metformin is widely used in polycystic ovary syndrome (PCOS). However, the treatment effectiveness shows individual differences in PCOS patients. Organic cation transporter (OCT) 1 and 2 have been reported to mediate metformin transport in the liver and kidney, respectively. In this study, we investigated the association between the polymorphisms of OCT1 and OCT2 and the treatment effectiveness of metformin in PCOS patients. The single nucleotide polymorphisms (SNPs) of OCT1 (rs683369 and rs628031) and OCT2 (rs316019) were analyzed in 87 PCOS and 113 control women. Oral glucose tolerance tests (OGTTs), which represented metformin treatment response, were conducted at the start of treatment and after six-month treatment. The results demonstrated that the SNP frequencies of OCT1 and OCT2 were not associated with PCOS pathophysiology, and that the polymorphisms of OCT1 and OCT2 were not associated with the OGTT parameters at baseline. However, PCOS patients with the G allele of OCT1 rs683369 and/or with the A allele of OCT1 rs628031 had increased insulin sensitivity compared to those with wild-type genotype after receiving metformin treatment. Moreover, the interactions of metformin*SNP were significant in both OCT1 rs683369 (p < 0.001) and rs628031 (p = 0.001) during the treatment period. Taken together, genetic polymorphisms of OCT1 contributed to different metformin treatment responses, and further study is needed to establish personalized treatment programs using a pharmacogenomic algorithm approach in PCOS patients.

Identification of prognostic biomarkers for patients with hepatocellular carcinoma after hepatectomy

Hepatocellular carcinoma (HCC) is a lethal malignancy with high morbidity and mortality rates worldwide. The identification of prognosis-associated biomarkers is crucial to improve HCC patient survival. The present study aimed to explore potential predictive biomarkers for HCC. Differentially expressed genes (DEGs) were analyzed in the GSE36376 dataset using GEO2R. Hub genes were identified and further investigated for prognostic value in HCC patients. A risk score model and nomogram were constructed to predict HCC prognosis using the prognosis-associated genes and clinical factors. Pearson's correlation was employed to show interactions among hub genes. Gene enrichment analysis was performed to identify detailed biological processes and pathways. A total of 71 DEGs were obtained and seven (ADH4, CYP2C8, CYP2C9, CYP8B1, SLC22A1, TAT and HSD17B13, all adjusted P≤0.05) of the 10 hub genes were identified as prognosis-related genes for survival analysis in HCC patients, including alcohol dehydrogenase 4 (class II), pi polypeptide (ADH4), cytochrome p450 family 2 subfamily C member 8 (CYP2C8), cytochrome P450 family 2 subfamily C member 9 (CYP2C9), cytochrome P450 family 8 subfamily B member 1 (CYP8B1), solute carrier family 22 member 1 (SLC22A1), tyrosine aminotransferase (TAT) and hydroxysteroid 17-β dehydrogenase 13 (HSD17B13). The risk score model could predict HCC prognosis and the nomogram visualized gene expression and clinical factors of probability for HCC prognosis. The majority of genes showed significant Pearson's correlations with others (41 Pearson correlations P≤0.01, four Pearson correlations P>0.05). GO analysis revealed that terms such as ‘chemical carcinogenesis’ and ‘drug metabolism-cytochrome P450’ were enriched and may prove helpful to elucidate the mechanisms of hepatocarcinogenesis. Hub genes ADH4, CYP2C8, CYP2C9, CYP8B1, SLC22A1, TAT and HSD17B13 may be useful as predictive biomarkers for HCC prognosis.

Solute carrier transporters: potential targets for digestive system neoplasms

Digestive system neoplasms are the leading causes of cancer-related death all over the world. Solute carrier (SLC) superfamily is composed of a series of transporters that are ubiquitously expressed in organs and tissues of digestive systems and mediate specific uptake of small molecule substrates in facilitative manner. Given the important role of SLC proteins in maintaining normal functions of digestive system, dysregulation of these protein in digestive system neoplasms may deliver biological and clinical significance that deserves systemic studies. In this review, we critically summarized the recent advances in understanding the role of SLC proteins in digestive system neoplasms. We highlighted that several SLC subfamilies, including metal ion transporters, transporters of glucose and other sugars, transporters of urea, neurotransmitters and biogenic amines, ammonium and choline, inorganic cation/anion transporters, transporters of nucleotide, amino acid and oligopeptide organic anion transporters, transporters of vitamins and cofactors and mitochondrial carrier, may play important roles in mediating the initiation, progression, metastasis, and chemoresistance of digestive system neoplasms. Proteins in these SLC subfamilies may also have diagnostic and prognostic values to particular cancer types. Differential expression of SLC proteins in tumors of digestive system was analyzed by extracting data from human cancer database, which revealed that the roles of SLC proteins may either be dependent on the substrates they transport or be tissue specific. In addition, small molecule modulators that pharmacologically regulate the functions of SLC proteins were discussed for their possible application in the treatment of digestive system neoplasms. This review highlighted the potential of SLC family proteins as drug target for the treatment of digestive system neoplasms.

Loss of organic cation transporter 3 (Oct3) leads to enhanced proliferation and hepatocarcinogenesis

Background

Organic cation transporters (OCT) are responsible for the uptake of a broad spectrum of endogenous and exogenous substrates. Downregulation of OCT is frequently observed in human hepatocellular carcinoma (HCC) and is associated with a poor outcome. The aim of our current study was to elucidate the impact of OCT3 on hepatocarcinogenesis.

Methods

Transcriptional and functional loss of OCT was investigated in primary murine hepatocytes, derived from Oct3-knockout (Oct3^−/−; FVB.Slc22a3^tm1Dpb) and wildtype (WT) mice. Liver tumors were induced in Oct3^−/− and WT mice with Diethylnitrosamine and Phenobarbital over 10 months and characterized macroscopically and microscopically. Key survival pathways were investigated by Western Blot analysis.

Results

Loss of Oct3^−/− in primary hepatocytes resulted in significantly reduced OCT activity determined by [³H]MPP⁺ uptake in vivo. Furthermore, tumor size and quantity were markedly enhanced in Oct3^−/− mice (p<0.0001). Oct3^−/− tumors showed significant higher proliferation (p<0.0001). Ki-67 and Cyclin D expression were significantly increased in primary Oct3^−/− hepatocytes after treatment with the OCT inhibitors quinine or verapamil (p<0.05). Functional inhibition of OCT by quinine resulted in an activation of c-Jun N-terminal kinase (Jnk), especially in Oct3^−/− hepatocytes.

Conclusion

Loss of Oct3 leads to enhanced proliferation and hepatocarcinogenesis in vivo.

Role of drug-dependent transporter modulation on the chemosensitivity of cholangiocarcinoma

Cholangiocarcinoma (CCA) is a heterogeneous group of malignancies with limited therapeutic options. Curative therapy is limited to surgery whereas chemotherapy treatments are the election option for unresectable or metastatic cholangiocarcinoma. Cisplatin plus gemcitabine is the reference chemotherapy regimen, albeit the contribution to the median overall survival barely reaches one year. Drug transporters are undoubtedly a limiting step for drug bioavailability and have been clearly related to chemoresistance. Several members of the SoLute Carrier (SLC) superfamily involved in the uptake of anticancer drugs used to treat cholangiocarcinoma are downregulated in these tumors. This study shows the increase in the expression of specific drug transporters exerted by cisplatin treatment thereby enhancing their transport activity. Combination treatments of cisplatin with selected drugs as gemcitabine and sorafenib take in by these transporters at the desired combination schedule induced synergy. These data support the concept that proper administration pattern could favor treatment outcome.

Chemoresistance and chemosensitization in cholangiocarcinoma

One of the main difficulties in the management of patients with advanced cholangiocarcinoma (CCA) is their poor response to available chemotherapy. This is the result of powerful mechanisms of chemoresistance (MOC) of quite diverse nature that usually act synergistically. The problem is often worsened by altered MOC gene expression in response to pharmacological treatment. Since CCA includes a heterogeneous group of cancers their genetic signature coding for MOC genes is also diverse; however, several shared traits have been defined. Some of these characteristics are shared with other types of liver cancer, namely hepatocellular carcinoma and hepatoblastoma. An important goal in modern oncologic pharmacology is to develop novel strategies to overcome CCA chemoresistance either by increasing drug specificity, such as in targeted therapies aimed to inhibit receptors with tyrosine kinase activity, or to increase the amounts of active agents inside CCA cells by enhancing drug uptake or reducing efflux through export pumps. This article is part of a Special Issue entitled: Cholangiocytes in Health and Diseaseedited by Jesus Banales, Marco Marzioni, Nicholas LaRusso and Peter Jansen.

Joint analysis of multiple high-dimensional data types using sparse matrix approximations of rank-1 with applications to ovarian and liver cancer

Background

Technological advances enable the cost-effective acquisition of Multi-Modal Data Sets (MMDS) composed of measurements for multiple, high-dimensional data types obtained from a common set of bio-samples. The joint analysis of the data matrices associated with the different data types of a MMDS should provide a more focused view of the biology underlying complex diseases such as cancer that would not be apparent from the analysis of a single data type alone. As multi-modal data rapidly accumulate in research laboratories and public databases such as The Cancer Genome Atlas (TCGA), the translation of such data into clinically actionable knowledge has been slowed by the lack of computational tools capable of analyzing MMDSs. Here, we describe the Joint Analysis of Many Matrices by ITeration (JAMMIT) algorithm that jointly analyzes the data matrices of a MMDS using sparse matrix approximations of rank-1.

Methods

The JAMMIT algorithm jointly approximates an arbitrary number of data matrices by rank-1 outer-products composed of “sparse” left-singular vectors (eigen-arrays) that are unique to each matrix and a right-singular vector (eigen-signal) that is common to all the matrices. The non-zero coefficients of the eigen-arrays identify small subsets of variables for each data type (i.e., signatures) that in aggregate, or individually, best explain a dominant eigen-signal defined on the columns of the data matrices. The approximation is specified by a single “sparsity” parameter that is selected based on false discovery rate estimated by permutation testing. Multiple signals of interest in a given MDDS are sequentially detected and modeled by iterating JAMMIT on “residual” data matrices that result from a given sparse approximation.

Results

We show that JAMMIT outperforms other joint analysis algorithms in the detection of multiple signatures embedded in simulated MDDS. On real multimodal data for ovarian and liver cancer we show that JAMMIT identified multi-modal signatures that were clinically informative and enriched for cancer-related biology.

Conclusions

Sparse matrix approximations of rank-1 provide a simple yet effective means of jointly reducing multiple, big data types to a small subset of variables that characterize important clinical and/or biological attributes of the bio-samples from which the data were acquired.

Electronic supplementary material

The online version of this article (doi:10.1186/s13040-016-0103-7) contains supplementary material, which is available to authorized users.

Expert consensus document: Cholangiocarcinoma: current knowledge and future perspectives consensus statement from the European Network for the Study of Cholangiocarcinoma (ENS-CCA)

Cholangiocarcinoma (CCA) is a heterogeneous group of malignancies with features of biliary tract differentiation. CCA is the second most common primary liver tumour and the incidence is increasing worldwide. CCA has high mortality owing to its aggressiveness, late diagnosis and refractory nature. In May 2015, the "European Network for the Study of Cholangiocarcinoma" (ENS-CCA: www.enscca.org or www.cholangiocarcinoma.eu) was created to promote and boost international research collaboration on the study of CCA at basic, translational and clinical level. In this Consensus Statement, we aim to provide valuable information on classifications, pathological features, risk factors, cells of origin, genetic and epigenetic modifications and current therapies available for this cancer. Moreover, future directions on basic and clinical investigations and plans for the ENS-CCA are highlighted.

Organic Cation Transporter 1 (OCT1) mRNA expression in hepatocellular carcinoma as a biomarker for sorafenib treatment

Background

The polyspecific organ cation transporter 1 (OCT1) is one of the most important active influx pumps for drugs like the kinase inhibitor sorafenib. The aim of this retrospective study was the definition of the role of intratumoral OCT1 mRNA expression in hepatocellular carcinoma (HCC) as a biomarker in systemic treatment with sorafenib.

Methods

OCT1 mRNA expression levels were determined in biopsies from 60 primary human HCC by real time PCR. The data was retrospectively correlated with clinical parameters.

Results

Intratumoral OCT1 mRNA expression is a significant positive prognostic factor for patients treated with sorafenib according to Cox regression analysis (HR 0.653, 95 %-CI 0.430-0.992; p = 0.046). Under treatment with sorafenib, a survival benefit could be shown using the lower quartile of intratumoral OCT1 expression as a cut-off. Macrovascular invasion (MVI) was slightly more frequent in patients with low OCT1 mRNA expression (p = 0.037). Treatment-induced AFP response was not associated with intratumoral OCT1 mRNA expression levels (p = 0.633).

Conclusions

This study indicates a promising role for intratumoral OCT1 mRNA expression as a prognostic biomarker in therapeutic algorithms in HCC. Further prospective studies are warranted on this topic.

The Impacts of SLC22A1 rs594709 and SLC47A1 rs2289669 Polymorphisms on Metformin Therapeutic Efficacy in Chinese Type 2 Diabetes Patients

Background. We aimed to investigate the distributive characteristics of SLC22A1 rs594709 and SLC47A1 rs2289669 polymorphisms and their influence on metformin efficacy in Chinese T2DM patients. Methods. The distributions of SLC22A1 rs594709 and SLC47A1 rs2289669 polymorphisms were determined in 267 T2DM patients and 182 healthy subjects. Subsequently, 53 newly diagnosed patients who received metformin monotherapy were recruited to evaluate metformin efficacy. Results. No significant difference was found between T2DM patients and healthy subjects in SLC22A1 rs594709 and SLC47A1 rs2289669 allele frequencies and genotype frequencies. After metformin treatment, SLC22A1 rs594709 GG genotype patients showed a higher increase in FINS (p = 0.015) and decrease in HOMA-IS (p = 0.001) and QUICKI (p = 0.002) than A allele carriers. SLC47A1 rs2289669 GG genotype patients had a higher decrease in TChol (p = 0.030) and LDL-C (p = 0.049) than A allele carriers. Among SLC22A1 rs594709 AA genotype, patients with SLC47A1 rs2289669 AA genotype showed a higher decrease in FBG (p = 0.015), PINS (p = 0.041), and HOMA-IR (p = 0.014) than G allele carriers. However, among SLC22A1 rs594709 G allele carriers, SLC47A1 rs2289669 AA genotype patients showed a higher decrease in TChol (p = 0.013) than G allele carriers. Conclusion. Our data suggest that SLC22A1 rs594709 and SLC47A1 rs2289669 polymorphisms may influence metformin efficacy together in Chinese T2DM patients.

The role of reduced intracellular concentrations of active drugs in the lack of response to anticancer chemotherapy

A major difficulty in the treatment of cancers is the poor response of many tumors to pharmacological regimens. This situation can be accounted for by the existence of a variety of complex mechanisms of chemoresistance (MOCs), leading to reduced intracellular concentrations of active agents, changes in the molecular targets of the drugs, enhanced repair of drug-induced modifications in macromolecules, stimulation of anti-apoptotic mechanisms, and inhibition of pro-apoptotic mechanisms. The present review focuses on alterations in the expression and appearance of the genetic variants that affect the genes involved in reducing the amount of active agents inside tumor cells. These alterations can occur through two mechanisms: either by lowering uptake or enhancing efflux (so-called MOC-1a and MOC-1b, respectively), or by decreasing the activation of prodrugs or enhancing inactivation of active agents through their biotransformation (MOC-2). The development of chemosensitizers that are useful in implementing the pharmacological manipulation of these processes constitutes a challenge to modern pharmacology. Nevertheless, the important physiological roles of the most relevant genes involved in MOC-1a, MOC-1b, and MOC-2 make it difficult to prevent the side effects of chemosensitizers. A more attainable goal in this area of pharmacological enquiry is the identification of proteomic profiles that will permit oncologists to accurately predict a lack of response to a given regimen, which would be useful for adapting treatment to the personal situation of each patient.

Role of the plasma membrane transporter of organic cations OCT1 and its genetic variants in modern liver pharmacology

Changes in the uptake of many drugs by the target cells may dramatically affect the pharmacological response. Thus, downregulation of SLC22A1, which encodes the organic cation transporter type 1 (OCT1), may affect the response of healthy hepatocytes and liver cancer cells to cationic drugs, such as metformin and sorafenib, respectively. Moreover, the overall picture may be modified to a considerable extent by the preexistence or the appearance during the pathogenic process of genetic variants. Some rare OCT1 variants enhance transport activity, whereas other more frequent variants impair protein maturation, plasma membrane targeting or the function of this carrier, hence reducing intracellular active drug concentrations. Here, we review current knowledge of the role of OCT1 in modern liver pharmacology, which includes the use of cationic drugs to treat several diseases, some of them of great clinical relevance such as diabetes and primary liver cancer (cholangiocarcinoma and hepatocellular carcinoma). We conclude that modern pharmacology must consider the individual evaluation of OCT1 expression/function in the healthy liver and in the target tissue, particularly if this is a tumor, in order to predict the lack of response to cationic drugs and to be able to design individualized pharmacological treatments with the highest chances of success.