Abacavir is a preferred antiretroviral drug for preventing mother-to-child human immunodeficiency virus transmission; however, mechanisms of its placental transfer have not been satisfactorily described to date. Because abacavir is a nucleoside-derived drug, we hypothesized that the nucleoside transporters, equilibrative nucleoside transporters (ENTs, SLC29A) and/or Na+-dependent concentrative nucleoside transporters (CNTs, SLC28A), may play a role in its passage across the placenta. To test this hypothesis, we performed uptake experiments using the choriocarcinoma-derived BeWo cell line, human fresh villous fragments, and microvillous plasma membrane (MVM) vesicles. Using endogenous substrates of nucleoside transporters, [3H]-adenosine (ENTs, CNT2, and CNT3) and [3H]-thymidine (ENTs, CNT1, and CNT3), we showed significant activity of ENT1 and CNT2 in BeWo cells, whereas experiments in the villous fragments and MVM vesicles, representing a model of the apical membrane of a syncytiotrophoblast, revealed only ENT1 activity. When testing [3H]-abacavir uptakes, we showed that of the nucleoside transporters, ENT1 plays the dominant role in abacavir uptake into placental tissues, whereas contribution of Na+-dependent transport, most likely mediated by CNTs, was observed only in BeWo cells. Subsequent experiments with dually perfused rat term placentas showed that Ent1 contributes significantly to overall [3H]-abacavir placental transport. Finally, we quantified the expression of SLC29A in first- and third-trimester placentas, revealing that SLC29A1 is the dominant isoform. Neither SLC29A1 nor SLC29A2 expression changed over the course of placental development, but there was considerable interindividual variability in their expression. Therefore, drug-drug interactions and the effect of interindividual variability in placental ENT1 expression on abacavir disposition into fetal circulation should be further investigated to guarantee safe and effective abacavir-based combination therapies in pregnancy.

• MeSH
• Adenosine metabolism   MeSH
• Biological Transport physiology   MeSH
• Dideoxynucleosides metabolism   MeSH
• Equilibrative Nucleoside Transporter 1 metabolism   MeSH
• Equilibrative-Nucleoside Transporter 2 metabolism   MeSH
• Rats MeSH
• Anti-HIV Agents metabolism   MeSH
• Humans MeSH
• Membrane Transport Proteins metabolism   MeSH
• Cell Line, Tumor MeSH
• Nucleosides metabolism   MeSH
• Placenta metabolism   MeSH
• Rats, Wistar MeSH
• Nucleoside Transport Proteins metabolism   MeSH
• Pregnancy MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Humans MeSH
• Pregnancy MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

Although systemic chemotherapy significantly improves the overall survival of pancreatic cancer patients, the prognosis remains extremely poor. The development of a drug resistance, either de novo or induced resistance, significantly limits the effectiveness of chemotherapy. SLC29A1 gene encodes human equilibrative nucleoside transporter 1 (hENT1) protein that is mediating the transport of nucleotides, both purines and pyrimidines, into the tumor cells. The aim of this mini-review is to summarize the current information concerning the prognostic and predictive role of SLC29A1 transporter (hENT1) expression in pancreatic cancer. Increased expression of SLC29A1 in vitro has been described as a potential critical factor determining the sensitivity of pancreatic cancer cells to gemcitabine and 5-fluorouracil, the principal cytotoxic agents used in the treatment of pancreatic cancer. The reports on the relationship between SLC29A1 expression and prognosis of patients with pancreatic cancer are currently rather conflicting. However, majority of studies on patients with resected pancreatic cancer have suggested that high SLC29A1expression may be predictive of improved survival in patients treated with gemcitabine. SLC29A1 has not been shown to represent a predictive biomarker for patients treated by 5-fluorouracil. In conclusion, potential prognostic and predictive role of SLC29A1 has been demonstrated for selected subset of patients.

• MeSH
• Deoxycytidine analogs & derivatives   therapeutic use   MeSH
• Equilibrative Nucleoside Transporter 1 analysis   genetics   MeSH
• Humans MeSH
• Biomarkers, Tumor analysis   genetics   MeSH
• Pancreatic Neoplasms drug therapy   metabolism   MeSH
• Prognosis MeSH
• Antimetabolites, Antineoplastic therapeutic use   MeSH
• Antineoplastic Agents therapeutic use   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

Ribavirin is a broad-spectrum nucleoside-derived antiviral drug used in combination pharmacotherapy treatment of hepatitis C virus infection. Current evidence indicates that ribavirin-associated teratogenicity is not significant in humans, but more information about the developmental toxicity and mechanisms involved in ribavirin placental kinetics is required to assure its safe use in pregnancy. Thus, we have investigated potential roles of equilibrative nucleoside transporters (ENTs, SLC29A), Na+-dependent influx-mediating concentrative nucleoside transporters (CNTs, SLC28A), and ATP-binding cassette (ABC) efflux pumps, in ribavirin placental pharmacokinetics. Our data indicate that ENT1 participates in uptake of ribavirin by BeWo cells, fresh human placental villous fragments and microvillous plasma membrane (MVM) vesicles while activity of CNTs (probably CNT2) was only observed in BeWo cells. In situ dual perfusion experiments with rat term placenta in an open circuit setup showed that ENT inhibition significantly decreases total ribavirin maternal-to-foetal and foetal-to-maternal clearances. In contrast, no contribution of ABC transporters, p-glycoprotein (ABCB1), breast cancer resistance protein (ABCG2), or multidrug resistance-associated protein (ABCC2) was detected in assays with MDCKII cells overexpressing them, or in closed circuit dual perfusion experiments with rat term placenta. In summary, our data show that ribavirin placental pharmacokinetics are largely controlled by ENT1 activity and independent of ABCB1, ABCG2, and ABCC2 efflux pumps.

• MeSH
• ATP-Binding Cassette Transporters physiology   MeSH
• Antimetabolites metabolism   pharmacology   MeSH
• Madin Darby Canine Kidney Cells MeSH
• Species Specificity MeSH
• Equilibrative Nucleoside Transporter 1 metabolism   MeSH
• Rats MeSH
• Humans MeSH
• Cell Line, Tumor MeSH
• Nucleosides physiology   MeSH
• Placenta drug effects   metabolism   MeSH
• Rats, Wistar MeSH
• Dogs MeSH
• Ribavirin metabolism   pharmacology   MeSH
• Pregnancy MeSH
• Protein Transport drug effects   physiology   MeSH
• Dose-Response Relationship, Drug MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Humans MeSH
• Dogs MeSH
• Pregnancy MeSH
• Female MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

OBJECTIVES: The aim of this study was to investigate the prognostic significance of fourteen anticancer drug-relevant solute carrier transporters (SLCs) in pancreatic cancer in the context of clinical-pathological characteristics and the KRAS mutation status of tumors. METHODS: Tumors and non-neoplastic pancreatic tissues were obtained from 32 histologically verified patients with pancreatic ductal adenocarcinoma. The transcript profile of SLCs was assessed using quantitative real-time PCR. KRAS mutations in exon 2 were assessed by high-resolution melting analysis and confirmed by sequencing. RESULTS: SLC22A3 and SLC22A18 were upregulated and SLC22A1, SLC22A2, SLC22A11, SLC28A1, SLC28A3 and SLC29A1 were downregulated when compared with non-neoplastic pancreatic tissues. Moreover, significantly lower levels of SLC22A1, SLC22A11 and SLC29A1 were found in tumors with angioinvasion. There was also a significantly higher transcript level of SLC28A1 in tumors with regional lymph nodes affected by metastasis. The study found that a high expression of SLC28A1 was significantly associated with poor overall survival in unselected patients. In contrast, a high expression of SLC22A3 or SLC29A3 was significantly associated with longer overall survival in patients treated with nucleoside analogs. Protein expression of SLC22A1, SLC22A3 and SLC29A3 in tumor tissues of patients with pancreatic carcinoma was observed by immunoblotting for the first time. Finally, SLC levels were not found to be associated with KRAS mutation status in exon 2. CONCLUSIONS: This study identified a number of associations of transcript levels of SLCs with prognosis of pancreatic cancer patients.

• MeSH
• Down-Regulation MeSH
• Carcinoma, Pancreatic Ductal genetics   pathology   MeSH
• Real-Time Polymerase Chain Reaction MeSH
• Middle Aged MeSH
• Humans MeSH
• Lymphatic Metastasis MeSH
• Membrane Transport Proteins genetics   MeSH
• Survival Rate MeSH
• Mutation MeSH
• Pancreatic Neoplasms genetics   pathology   MeSH
• Prognosis MeSH
• Prospective Studies MeSH
• Organic Cation Transport Proteins genetics   MeSH
• Proto-Oncogene Proteins genetics   MeSH
• ras Proteins genetics   MeSH
• Gene Expression Regulation, Neoplastic MeSH
• Sequence Analysis, DNA MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Up-Regulation MeSH
• Check Tag
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

BACKGROUND: This study addresses involvement of major 5-fluorouracil (5-FU) pathway genes in the prognosis of colorectal carcinoma patients. METHODS: Testing set and two validation sets comprising paired tumor and adjacent mucosa tissue samples from 151 patients were used for transcript profiling of 15 5-FU pathway genes by quantitative real-time PCR and DNA methylation profiling by high resolution melting analysis. Intratumoral molecular profiles were correlated with clinical data of patients. Protein levels of two most relevant candidate markers were assessed by immunoblotting. RESULTS: Downregulation of DPYD and upregulation of PPAT, UMPS, RRM2, and SLC29A1 transcripts were found in tumors compared to adjacent mucosa in testing and validation sets of patients. Low RRM2 transcript level significantly associated with poor response to the first-line palliative 5-FU-based chemotherapy in the testing set and with poor disease-free interval of patients in the validation set irrespective of 5-FU treatment. UPP2 was strongly methylated while its transcript absent in both tumors and adjacent mucosa. DPYS methylation level was significantly higher in tumor tissues compared to adjacent mucosa samples. Low intratumoral level of UPB1 methylation was prognostic for poor disease-free interval of the patients (P = 0.0002). The rest of the studied 5-FU genes were not methylated in tumors or adjacent mucosa. CONCLUSIONS: The observed overexpression of several 5-FU activating genes and DPYD downregulation deduce that chemotherapy naïve colorectal tumors share favorable gene expression profile for 5-FU therapy. Low RRM2 transcript and UPB1 methylation levels present separate poor prognosis factors for colorectal carcinoma patients and should be further investigated.

• MeSH
• CpG Islands MeSH
• Fluorouracil pharmacology   MeSH
• Colorectal Neoplasms genetics   metabolism   mortality   pathology   MeSH
• Middle Aged MeSH
• Humans MeSH
• DNA Methylation MeSH
• Promoter Regions, Genetic MeSH
• Antimetabolites, Antineoplastic pharmacology   MeSH
• Gene Expression Regulation, Neoplastic drug effects   MeSH
• Ribonucleoside Diphosphate Reductase genetics   metabolism   MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Signal Transduction drug effects   MeSH
• Neoplasm Staging MeSH
• Gene Expression Profiling * MeSH
• Neoplasm Grading MeSH
• Transcriptome * MeSH
• Check Tag
• Middle Aged MeSH
• Humans MeSH
• Male MeSH
• Aged, 80 and over MeSH
• Aged MeSH
• Female MeSH
• Publication type
• Journal Article MeSH

Východiska: Duktální adenokarcinom pankreatu je vysoce agresivní onemocnění s celkovým 5letým přežitím nepřesahujícím 5 %. V ČR má incidence tohoto nádoru vzestupný trend, dle posledních statistik již patříme celosvětově na první místo ve výskytu této malignity. Pro toto onemocnění je typická pozdní diagnostika vzhledem k asymptomatickému průběhu nemoci v časném stadiu. Cíl: Cílem tohoto článku je podat přehled o nejvýznamnějších faktorech, které dle současných znalostí u adenokarcinomu pankreatu mají prognostický a prediktivní potenciál. Práce popisuje jednak tradiční prognostické faktory, jako je resekabilita nádoru, jeho rozsah a lokalizace, aplikace adjuvantní chemoterapie, mikroskopicky pozitivní resekční okraj, přítomnost metastáz v lymfatických uzlinách, histologický grading, vaskulární a perineurální invaze. Dále uvádí celou řadu různých biologických markerů, které by mohly přispět k včasné detekci nádoru, lepší prognóze a k optimalizaci léčby, např. hENT1 (human equilibrative nucleoside transporter-1), SPARC (secreted protein acidic and rich in cystein), AGR2, Bcl-2, VEGF, Ki-67, COX-2 a další. Zmíněny jsou rovněž genové alterace a význam mikroRNA. Závěr: I přes velké úsilí, které bylo věnováno výzkumu biologických markerů, zatím jediný klinicky akceptovaný a v klinice používaný zůstává nádorový marker CA 19-9. Jeho využití je především u pacientů s již diagnostikovaným adenokarcinomem pankreatu. Velká pozornost je v poslední době zaměřena na další potenciální biomarkery, jejich zavedení do klinické praxe bude ale ještě vyžadovat další výzkum.

Background: Pancreatic ductal adenocarcinoma is a highly aggressive disease with 5-year overall survival not exceeding 5%. In the Czech Republic, the incidence of this tumor has been increasing; according to recent statistics, the Czech Republic is already number one worldwide in the occurrence of this malignancy. Delayed diagnosis due to asymptomatic course of the disease in the early stages is characteristic for this disease. Aim: The objective of this article is to give an overview of the most important factors, which according to current knowledge of pancreatic adenocarcinoma have a prognostic and predictive potential. This work describes both traditional prognostic factors, such as tumor resectability, its extent and localization, application of adjuvant chemotherapy, microscopically positive resection margin, presence of metastases in lymph nodes, histological grade, vascular and perineural invasion. Further, the paper lists a number of different biological markers that could contribute to early detection of cancer, better prognosis and optimization of treatment, for example hENT1 (human equilibrative nucleoside transporter-1), SPARC (secreted protein acidic and rich in cysteine), AGR2, Bcl-2, VEGF, Ki-67, COX-2 and more. Also, genetic mutations and significance of microRNA are discussed. Conclusion: Despite great efforts that have been devoted to the research of biological markers, so far the only clinically accepted and used marker is CA 19-9. Its use is primarily in patients already diagnosed with adenocarcinoma of the pancreas. A lot of attention has recently been focused on other potential biomarkers, their application in clinical practice would however still require further research.

• Keywords
• hENT1, SPARC, BCL2, S100A4, AGR2,
• MeSH
• CA-19-9 Antigen blood   MeSH
• Ki-67 Antigen blood   MeSH
• Cyclooxygenase 2 blood   MeSH
• Carcinoma, Pancreatic Ductal * genetics   blood   MeSH
• Equilibrative Nucleoside Transporter 1 blood   MeSH
• Humans MeSH
• MicroRNAs genetics   MeSH
• Biomarkers, Tumor * genetics   blood   metabolism   MeSH
• Pancreatic Neoplasms * genetics   blood   MeSH
• Osteonectin blood   MeSH
• Prognosis MeSH
• S100 Proteins blood   MeSH
• Proto-Oncogene Proteins c-bcl-2 blood   MeSH
• Proto-Oncogene Proteins p21(ras) blood   MeSH
• Vascular Endothelial Growth Factors blood   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Review MeSH