Human equilibrative nucleoside transporter 1 (hENT1) protein is associated with short survival in resected ampullary cancer

Prognostic and predictive value of human equilibrative nucleoside transporter 1 (hENT1) in extrahepatic cholangiocarcinoma: a translational study

Introduction: Effective (neo) adjuvant chemotherapy for cholangiocarcinoma is lacking due to chemoresistance and the absence of predictive biomarkers. Human equilibrative nucleoside transporter 1 (hENT1) has been described as a potential prognostic and predictive biomarker. In this study, the potential of rabbit-derived (SP120) and murine-derived (10D7G2) antibodies to detect hENT1 expression was compared in tissue samples of patients with extrahepatic cholangiocarcinoma (ECC), and the predictive value of hENT1 was investigated in three ECC cell lines. Methods: Tissues of 71 chemonaïve patients with histological confirmation of ECC were selected and stained with SP120 or 10D7G2 to assess the inter-observer variability for both antibodies and the correlation with overall survival. Concomitantly, gemcitabine sensitivity after hENT1 knockdown was assessed in the ECC cell lines EGI-1, TFK-1, and SK-ChA-1 using sulforhodamine B assays. Results: Scoring immunohistochemistry for hENT1 expression with the use of SP120 antibody resulted in the highest interobserver agreement but did not show a prognostic role of hENT1. However, 10D7G2 showed a prognostic role for hENT1, and a potential predictive role for gemcitabine sensitivity in hENT1 in SK-ChA-1 and TFK-1 cells was found. Discussion: These findings prompt further studies for both preclinical validation of the role of hENT1 and histochemical standardization in cholangiocarcinoma patients treated with gemcitabine-based chemotherapy.

Is age just a number? A population pharmacokinetic study of gemcitabine

PURPOSE

Pharmacokinetic exposure to gemcitabine and its metabolite, 2',2'-difluorodeoxyuridine (dFdU), might be altered in elderly compared to their younger counterparts. It is unknown if age-based dose adjustments are necessary to reduce the development of treatment-induced adverse events. The aim of this study was to assess the impact of age on the pharmacokinetics of gemcitabine and dFdU.

METHODS

Pharmacokinetic sampling following a flexible limited sampling strategy was performed in patients ≥ 70 years after gemcitabine infusion. The data were supplemented with pharmacokinetic data in patients included in four previously conducted clinical trials. Nonlinear mixed effects modelling was performed on the pooled dataset to assess the impact of age on the pharmacokinetics of gemcitabine and dFdU.

RESULTS

In total, pharmacokinetic data were available of 197 patients, of whom 83 patients were aged ≥ 70 years (42%). A two-compartment model for both gemcitabine and dFdU with linear clearances from the central compartments described the data best. Age, tested as continuous and categorical (< 70 years versus ≥ 70 years) covariate, did not statistically affect the pharmacokinetics of gemcitabine and dFdU.

CONCLUSION

Age was not of influence on the pharmacokinetics of gemcitabine or its metabolite, dFdU. Age-related dose adjustments for gemcitabine based on pharmacokinetic considerations are not recommended.

TRIAL REGISTRATION NUMBER

NL39647.048.12, registered on May 3rd 2012.

Roles for hENT1 and dCK in gemcitabine sensitivity and malignancy of meningioma

Background

High-grade meningiomas are aggressive tumors with high morbidity and mortality rates that frequently recur even after surgery and adjuvant radiotherapy. However, limited information is currently available on the biology of these tumors, and no alternative adjuvant treatment options exist. Although we previously demonstrated that high-grade meningioma cells were highly sensitive to gemcitabine in vitro and in vivo, the underlying molecular mechanisms remain unknown.

Methods

We examined the roles of hENT1 (human equilibrative nucleoside transporter 1) and dCK (deoxycytidine kinase) in the gemcitabine sensitivity and growth of meningioma cells in vitro. Tissue samples from meningiomas (26 WHO grade I and 21 WHO grade II/III meningiomas) were immunohistochemically analyzed for hENT1 and dCK as well as for Ki-67 as a marker of proliferative activity.

Results

hENT1 and dCK, which play critical roles in the intracellular transport and activation of gemcitabine, respectively, were responsible for the high gemcitabine sensitivity of high-grade meningioma cells and were strongly expressed in high-grade meningiomas. hENT1 expression was required for the proliferation and survival of high-grade meningioma cells and dCK expression. Furthermore, high hENT1 and dCK expression levels correlated with stronger tumor cell proliferative activity and shorter survival in meningioma patients.

Conclusions

The present results suggest that hENT1 is a key molecular factor influencing the growth capacity and gemcitabine sensitivity of meningioma cells and also that hENT1, together with dCK, may be a viable prognostic marker for meningioma patients as well as a predictive marker of their responses to gemcitabine.

Organic Cation Transporters in Health and Disease

The organic cation transporters (OCTs) OCT1, OCT2, OCT3, novel OCT (OCTN)1, OCTN2, multidrug and toxin exclusion (MATE)1, and MATE kidney-specific 2 are polyspecific transporters exhibiting broadly overlapping substrate selectivities. They transport organic cations, zwitterions, and some uncharged compounds and operate as facilitated diffusion systems and/or antiporters. OCTs are critically involved in intestinal absorption, hepatic uptake, and renal excretion of hydrophilic drugs. They modulate the distribution of endogenous compounds such as thiamine, L-carnitine, and neurotransmitters. Sites of expression and functions of OCTs have important impact on energy metabolism, pharmacokinetics, and toxicity of drugs, and on drug-drug interactions. In this work, an overview about the human OCTs is presented. Functional properties of human OCTs, including identified substrates and inhibitors of the individual transporters, are described. Sites of expression are compiled, and data on regulation of OCTs are presented. In addition, genetic variations of OCTs are listed, and data on their impact on transport, drug treatment, and diseases are reported. Moreover, recent data are summarized that indicate complex drug-drug interaction at OCTs, such as allosteric high-affinity inhibition of transport and substrate dependence of inhibitor efficacies. A hypothesis about the molecular mechanism of polyspecific substrate recognition by OCTs is presented that is based on functional studies and mutagenesis experiments in OCT1 and OCT2. This hypothesis provides a framework to imagine how observed complex drug-drug interactions at OCTs arise. Finally, preclinical in vitro tests that are performed by pharmaceutical companies to identify interaction of novel drugs with OCTs are discussed. Optimized experimental procedures are proposed that allow a gapless detection of inhibitory and transported drugs.

Human equilibrative nucleoside transporter 1 (hENT1) expression as a predictive biomarker for gemcitabine chemotherapy in biliary tract cancer

Gemcitabine is a principal chemotherapeutic agent for biliary tract cancer (BTC). Expression of human equilibrative nucleoside transporter 1 (hENT1) is regarded as a potential predictive biomarker for a gemcitabine response in some cancers. This study was conducted to investigate the association between hENT1 expression and the effects of gemcitabine on BTC cell lines and on patients with advanced BTC receiving gemcitabine-based chemotherapy. A total of four BTC cell lines, HuCCT1, SNU-478, SNU-1079, and SNU-1196, were tested. mRNA and protein expression levels of hENT1 were measured by quantitative reverse-transcription polymerase chain reaction and western blotting, respectively. Cell viability after gemcitabine treatment was measured in a chemosensitivity assay. For clinical assessment, 40 patients with unresectable or recurrent BTC who were treated with gemcitabine (1000 mg/m²) and cisplatin (25 mg/m²) between June 2012 and May 2014 were enrolled. Among the four cell lines, SNU1196 showed the highest mRNA and protein levels of hENT1. Expression of hENT1 showed a linear correlation with the log value of the half-maximal inhibitory concentration of gemcitabine. During incubation with gemcitabine, pretreatment with hENT1-specific small interfering RNA (siRNA) resulted in higher cell viability than that in samples pretreated with control siRNA. In a clinical evaluation, the median progression-free survival was 24 and 11 weeks among patients with strong and weak intratumoral hENT1 immunohistochemical staining (P = 0.05), and the median overall survival was 52 and 26 weeks (P = 0.15), respectively. In conclusion, this study showed that increased hENT1 expression is associated with a stronger toxic effect of gemcitabine on BTC cell lines. The clinical outcomes in this study suggest that increased intratumoral hENT1 immunohistochemical staining is a possible biomarker predicting better therapeutic effects of gemcitabine on patients with advanced BTC. Further studies are needed to determine the precise role of hENT1 in BTC.

Membrane human equilibrative nucleoside transporter 1 is associated with a high proliferation rate and worse survival in resected intrahepatic cholangiocarcinoma patients not receiving adjuvant treatments

Human equilibrative nucleoside transporter 1 (hENT-1) is a membrane nucleoside transporter mediating the intracellular uptake of nucleosides and their analogues. hENT-1 was recently reported to have a predictive role in intrahepatic cholangiocarcinoma (iCC) patients receiving adjuvant gemcitabine-based chemotherapy, but its biological and clinical significance in iCC remains unsettled. This study investigated the role of hENT-1 in regulating tumour growth and predicting the survival of 40 resected iCC patients not receiving adjuvant treatments. hENT-1 expression was found to be significantly higher in iCC than in the matched non-tumoural liver. Patients harbouring hENT-1 localised on the tumour cell membrane had a worse overall survival than membrane hENT-1-negative patients (median 21.2 months vs 30.3 months, p = 0.031), with an adjusted hazard ratio of 2.8 (95% confidence interval 1.01-7.76). Moreover, membrane hENT-1-positive patients had a higher percentage of Ki67-positive cells in tumour tissue than membrane hENT-1-negative patients (median 23% vs 5%, p < 0.0001). Functional analyses in iCC cell lines revealed that hENT-1 silencing inhibited cell proliferation and induced apoptosis in HUH-28 cells expressing hENT-1 on the cell membrane, but not in SNU-1079 cells expressing the transporter only in the cytoplasm. Overall, these findings suggest that membrane hENT-1 is involved in iCC proliferation and associated with worse survival in resected iCC patients. Further prospective studies on larger cohorts are required to confirm these results and better define the potential prognostic role of membrane hENT-1 in this setting of patients.

Gemcitabine-Based Chemotherapy in Adrenocortical Carcinoma: A Multicenter Study of Efficacy and Predictive Factors

CONTEXT

Adrenocortical carcinoma (ACC) is rare and confers an unfavorable prognosis in advanced stages. Other than combination chemotherapy with cisplatin, etoposide, doxorubicin, and mitotane, the second- and third-line regimens are not well-established. Gemcitabine (GEM)-based chemotherapy was suggested in a phase 2 clinical trial with 28 patients. In other solid tumors, human equilibrative nucleoside transporter type 1 (hENT1) and/or ribonucleotide reductase catalytic subunit M1 (RRM1) expression have been associated with resistance to GEM.

OBJECTIVE

To assess the efficacy of GEM-based chemotherapy in ACC in a real-world setting and the predictive role of molecular parameters.

DESIGN

Retrospective multicenter study.

SETTING

Referral centers of university hospitals.

PATIENTS AND MATERIALS

A total of 145 patients with advanced ACC were treated with GEM-based chemotherapy (132 with concomitant capecitabine). Formalin-fixed paraffin-embedded tumor material was available for 70 patients for immunohistochemistry.

OUTCOME MEASURES

The main outcome measures were progression-free survival (PFS) and an objective response to GEM-based chemotherapy. The secondary objective was the predictive role of hENT1 and RRM1.

RESULTS

The median PFS for the patient population was 12 weeks (range, 1 to 94). A partial response or stable disease was achieved in 4.9% and 25.0% of cases, with a median duration of 26.8 weeks. Treatment was generally well tolerated, with adverse events of grade 3 or 4 occurring in 11.0% of cases. No substantial effect of hENT1 and/or RRM1 expression was observed in response to GEM-based chemotherapy.

CONCLUSIONS

GEM-based chemotherapy is a well-tolerated, but modestly active, regimen against advanced ACC. No reliable molecular predictive factors could be identified. Owing to the scarce alternative therapeutic options, GEM-based chemotherapy remains an important option for salvage treatment for advanced ACC.

Human equilibrative nucleoside transporter 1 gene expression is associated with gemcitabine efficacy in advanced leiomyosarcoma and angiosarcoma

Background:

The expression of human equilibrative nucleoside transporter 1 (hENT1), the major gemcitabine transporter into cells, has been thoroughly investigated as a predictive marker of response to gemcitabine in pancreatic cancer and biliary tract cancers. Since gemcitabine is widely used in the treatment of leiomyosarcoma and angiosarcoma, we investigated the correlation between hENT1 expression and gemcitabine efficacy in these sarcoma subtypes.

Methods:

We retrospectively identified 71 patients affected by advanced angiosarcoma (26) or leiomyosarcoma (45) treated within five Italian referral centres for sarcoma; among them, 49 patients (15 angiosarcoma, 34 leiomyosarcoma) were treated with gemcitabine. All tumour samples were analysed for hENT1 expression by real-time PCR. Median 2^–ΔCt value was used as the cutoff to dichotomise patients into ‘high’ expression and ‘low’ expression groups. Kaplan–Meier analysis was performed to estimate progression-free survival (PFS) and overall survival (OS).

Results:

We found a significant association between high hENT1 expression levels and favourable outcome in terms of PFS and OS compared to cases with low hENT1 expression in leiomyosarcoma treated with gemcitabine (PFS: 6.8 vs 3.2 months, P=0.004; OS: 14.9 vs 8.5 months, P=0.007). In addition, hENT1 overexpression correlated with a significant improvement in PFS (9.3 vs 4.5 months; P=0.02) and OS (20.6 vs 10.8 months; P=0.001) in angiosarcoma patients treated with gemcitabine.

Conclusions:

Our study suggests that higher hENT1 expression are associated to gemcitabine efficacy both in patients with advanced leiomyosarcoma and angiosarcoma.

Membrane Localization of Human Equilibrative Nucleoside Transporter 1 in Tumor Cells May Predict Response to Adjuvant Gemcitabine in Resected Cholangiocarcinoma Patients

BACKGROUND

The use of gemcitabine as an adjuvant modality for cholangiocarcinoma (CC) is increasing, but limited data are available on predictive biomarkers of response. Human equilibrative nucleoside transporter 1 (hENT-1) is the major transporter involved in gemcitabine intracellular uptake. This study investigated the putative predictive role of hENT-1 localization in tumor cells of CC patients undergoing treatment with adjuvant gemcitabine.

METHODS

Seventy-one consecutive patients with resected CC receiving adjuvant gemcitabine at our center were retrospectively analyzed by immunohistochemistry for hENT-1 localization in tumor cells. The main outcome measure was disease-free survival (DFS). Hazard ratios (HRs) of relapse and associated 95% confidence intervals (CIs) were obtained from proportional hazards regression models stratified on quintiles of propensity score.

RESULTS

Twenty-three (32.4%) cases were negative for hENT-1, 22 (31.0%) were positive in the cytoplasm only, and 26 (36.6%) showed concomitant cytoplasm/membrane staining. Patients with membrane hENT-1 had a longer DFS (HR 0.49, 95% CI 0.24-0.99, p = .046) than those who were negative or positive only in the cytoplasm of tumor cells. Notably, the association between DFS and membrane hENT-1 was dependent on the number of gemcitabine cycles (one to two cycles: HR 0.96, 95% CI 0.34-2.68; three to four cycles: HR 0.99, 95% CI 0.34-2.90; five to six cycles: HR 0.27, 95% CI 0.10-0.77).

CONCLUSION

hENT-1 localization on tumor cell membrane may predict response to adjuvant gemcitabine in CC patients receiving more than four cycles of chemotherapy. Further prospective randomized trials on larger populations are required to confirm these preliminary results, so that optimal gemcitabine-based chemotherapy may be tailored for CC patients in the adjuvant setting.

IMPLICATIONS FOR PRACTICE

Gemcitabine is becoming an increasingly used adjuvant modality in cholangiocarcinoma (CC), but limited data are available on predictive biomarkers of response. In this study, patients receiving more than four cycles of adjuvant gemcitabine and harboring Human equilibrative nucleoside transporter 1 (hENT-1, the major transporter involved in gemcitabine intracellular uptake) on tumor cell membrane had a longer disease-free survival compared with patients negative or positive for hENT-1 only in the cytoplasm of tumor cells. Overall these results may lay the basis for further prospective randomized trials based on a larger population of patients and may prove useful for tailoring appropriate gemcitabine-based chemotherapy for CC patients in the adjuvant setting.

Low expression of equilibrative nucleoside transporter 1 is associated with poor prognosis in chemotherapy-naïve pT2 gallbladder adenocarcinoma patients

AIMS

Equilibrative nucleoside transporter 1 (ENT1) is the major transporter of the chemotherapeutic drug gemcitabine, the current therapy for advanced gallbladder cancer (GBC). ENT1 expression has been proposed as a predictive marker for gemcitabine-treated pancreatic cancer patients. The aim of study was to explore the value of ENT1 measurement in chemotherapy-naïve patients with advanced GBC.

MATERIALS AND RESULTS

Immunohistochemistry for ENT1 was performed on 214 GBC samples from patients who had never undergone co-adjuvant or neo-adjuvant chemotherapy. Advanced GBC cases were divided into groups with low or high ENT1 expression. Kaplan-Meier tests were used for survival analyses. The Cox regression method was used to assess the association of ENT1 expression with overall survival (OS). Low ENT1 expression was associated with younger patient age (P = 0.03) and moderate-to-poor histological differentiation (P = 0.01). pT2 patients with low ENT1 expression had shorter median survival (17.3 versus 28.7 months) and lower OS (17.3% versus 33.3%, P < 0.05) than patients with high ENT1 expression. Low ENT1 expression was an independent prognostic factor for OS (P = 0.036).

CONCLUSIONS

ENT1 is a prognostic marker for pT2 GBC patients. Additional studies are needed to determine whether ENT1 has predictive value for gemcitabine response in GBC.

Prognostic effect of hENT1, dCK and HuR expression by morphological type in periampullary adenocarcinoma, including pancreatic cancer

BACKGROUND

Putative biomarkers of gemcitabine response have been extensively studied in pancreatic cancer, but less so in other types of periampullary adenocarcinoma. The most studied biomarker is human equilibrative nucleoside transporter 1 (hENT1), and the activating enzyme deoxycytidine kinase (dCK) has also been linked to treatment response. The RNA-binding protein human antigen R (HuR) has been demonstrated to confer increased dCK levels in vitro and to predict gemcitabine response in vivo. Here, we investigated the prognostic impact of hENT1, dCK and HuR in pancreatobiliary (PB) and intestinal (I) type periampullary cancers, respectively.

MATERIAL AND METHODS

Immunohistochemical expression of hENT1, dCK and HuR was evaluated in tissue microarrays with all primary tumours and 103 paired lymph node metastases from a consecutive retrospective cohort of 175 patients with resected periampullary adenocarcinomas.

RESULTS

In patients with PB-type tumours, neither hENT1 nor dCK expression was prognostic. A high HuR cytoplasmic/nuclear ratio was associated with a significantly reduced five-year overall survival (OS) in patients receiving adjuvant gemcitabine (HR 2.07, 95% CI 1.03-4.17) but not in untreated patients (pinteraction = 0.028). In patients with I-type tumours receiving adjuvant chemotherapy, high dCK expression was significantly associated with a prolonged recurrence-free survival (RFS) (HR 0.09, 95% CI 0.01-0.73, pinteraction = 0.023). Furthermore, HuR expression was associated with a prolonged OS and RFS in unadjusted but not in adjusted analysis and hENT1 expression was an independent predictor of a prolonged RFS (HR 0.24, 95% CI 0.10-0.59), regardless of adjuvant treatment.

CONCLUSION

hENT1 expression is a favourable prognostic factor in I-type, but not in PB-type tumours. High dCK expression is a favourable prognostic factor in patients with I-type tumours receiving adjuvant treatment and a high cytoplasmic/nuclear HuR ratio is a negative prognostic factor in gemcitabine-treated PB-type tumours. Morphological subtype should always be considered in biomarker studies on periampullary cancer.

Nucleoside transporter proteins as biomarkers of drug responsiveness and drug targets

Nucleoside and nucleobase analogs are currently used in the treatment of solid tumors, lymphoproliferative diseases, viral infections such as hepatitis and AIDS, and some inflammatory diseases such as Crohn. Two gene families are implicated in the uptake of nucleosides and nucleoside analogs into cells, SCL28 and SLC29. The former encodes hCNT1, hCNT2, and hCNT3 proteins. They translocate nucleosides in a Na⁺ coupled manner with high affinity and some substrate selectivity, being hCNT1 and hCNT2 pyrimidine- and purine-preferring, respectively, and hCNT3 a broad selectivity transporter. SLC29 genes encode four members, being hENT1 and hENT2 the only two which are unequivocally implicated in the translocation of nucleosides and nucleobases (the latter mostly via hENT2) at the cell plasma membrane. Some nucleoside-derived drugs can also interact with and be translocated by members of the SLC22 gene family, particularly hOCT and hOAT proteins. Inter-individual differences in transporter function and perhaps, more importantly, altered expression associated with the disease itself might modulate the transporter profile of target cells, thereby determining drug bioavailability and action. Drug transporter pharmacology has been periodically reviewed. Thus, with this contribution we aim at providing a state-of-the-art overview of the clinical evidence generated so far supporting the concept that these membrane proteins can indeed be biomarkers suitable for diagnosis and/or prognosis. Last but not least, some of these transporter proteins can also be envisaged as drug targets, as long as they can show “transceptor” functions, in some cases related to their role as modulators of extracellular adenosine levels, thereby providing a functional link between P1 receptors and transporters.

Gene expression profiling of ampullary carcinomas classifies ampullary carcinomas into biliary-like and intestinal-like subtypes that are prognostic of outcome

BACKGROUND

Adenocarcinomas of the ampulla of Vater are classified as biliary cancers, though the exact epithelium of origin for these cancers is not known. We sought to molecularly classify ampullary adenocarcinomas in comparison to known adenocarcinomas of the pancreas, bile duct, and duodenum by gene expression analysis.

METHODS

We analyzed 32 fresh-frozen resected, untreated periampullary adenocarcinomas (8 pancreatic, 2 extrahepatic biliary, 8 duodenal, and 14 ampullary) using the Affymetrix U133 Plus 2.0 genome array. Unsupervised and supervised hierarchical clustering identified two subtypes of ampullary carcinomas that were molecularly and histologically characterized.

RESULTS

Hierarchical clustering of periampullary carcinomas segregated ampullary carcinomas into two subgroups, which were distinctly different from pancreatic carcinomas. Non-pancreatic periampullary adenocarcinomas were segregated into two subgroups with differing prognoses: 5 year RFS (77% vs. 0%, p = 0.007) and 5 year OS (100% vs. 35%, p = 0.005). Unsupervised clustering analysis of the 14 ampullary samples also identified two subgroups: a good prognosis intestinal-like subgroup and a poor prognosis biliary-like subgroup with 5 year OS of 70% vs. 28%, P = 0.09. Expression of CK7+/CK20- but not CDX-2 correlated with these two subgroups. Activation of the AKT and MAPK pathways were both increased in the poor prognostic biliary-like subgroup. In an independent 80 patient ampullary validation dataset only histological subtype (intestinal vs. pancreaticobiliary) was significantly associated with OS in both univariate (p = 0.006) and multivariate analysis (P = 0.04).

CONCLUSIONS

Gene expression analysis discriminated pancreatic adenocarcinomas from other periampullary carcinomas and identified two prognostically relevant subgroups of ampullary adenocarcinomas. Histological subtype was an independent prognostic factor in ampullary adenocarcinomas.

A retrospective study of ampullary adenocarcinomas: overall survival and responsiveness to fluoropyrimidine-based chemotherapy

BACKGROUND

Whether carcinomas of the ampulla of Vater should be classified with biliary tract tumors and treated in a similar manner remains unknown. We sought to compare the outcomes of similarly staged periampullary adenocarcinomas (AAs) and analyze the chemotherapy responsiveness of AAs.

PATIENTS AND METHODS

A total of 905 patients with resected periampullary adenocarcinomas were identified from a prospective surgical registry from 1988 to 2010. A second cohort of 64 metastatic AA patients from 1992 to 2009 who received either front-line fluoropyrimidine-based or gemcitabine-based chemotherapy was also identified.

RESULTS

Overall survival (OS) for AAs was similar to survival with duodenal adenocarcinomas, but was significantly different from both extrahepatic biliary and pancreatic adenocarcinomas (P < 0.001 for each comparison). In multivariate analysis, AAs had a significantly improved OS in comparison with extrahepatic biliary adenocarcinomas (HR = 1.97, P = 0.006). Fluoropyrimidine-based as opposed to gemcitabine-based chemotherapy for metastatic AAs resulted in a significant improvement in time to progression (P = 0.001) but only a trend toward benefit for OS (P = 0.07) in multivariate analysis.

CONCLUSIONS

Differences in the natural history of ampullary and extrahepatic biliary adenocarcinomas exist. Analyses of metastatic ampullary adenocarcinomas suggest that fluoropyrimidine-based chemotherapy may represent a more appropriate front-line chemotherapy approach.

Human equilibrative nucleoside transporter 1 level does not predict prognosis in pancreatic cancer patients treated with neoadjuvant chemoradiation including gemcitabine

BACKGROUND

Gemcitabine is a key drug for the treatment of pancreatic cancer. Human equilibrative nucleoside transporter 1 (hENT1) is a major transporter responsible for gemcitabine uptake into cells. This study was conducted to elucidate the association between expression level of hENT1 and outcome for pancreatic cancer patients treated with neoadjuvant therapy including gemcitabine.

METHODS

Sixty-three patients who underwent neoadjuvant chemoradiation followed by curative surgery for pancreatic ductal adenocarcinomas were included. Immunohistochemistry was performed using resected specimens and the staining intensity of hENT1 was scored as having no staining, low staining, or high staining; the former two were defined as negative expression of hENT1. The association between expression level of hENT1 and overall survival was evaluated by Cox proportional regression model.

RESULTS

Expression level of hENT1 was evaluated as positive in 22 (35%) patients, and as negative in 41 (65%) patients. Univariate analysis showed that regional lymph node metastasis, vascular permeation, and perineural invasion are prognostic factors; however, expression level of hENT1 did not reach statistical significance. Multivariate analysis showed only vascular permeation as a prognostic factor.

CONCLUSIONS

Expression level of hENT1 was not associated with prognosis for pancreatic cancer patients who were treated with neoadjuvant chemoradiation including gemcitabine.

3'-Deoxy-3'-[(18)F]-fluorothymidine ([(18)F]-FLT) transport in newly diagnosed glioma: correlation with nucleoside transporter expression, vascularization, and blood-brain barrier permeability

3'-Deoxy-3'-[(18)F]-fluorothymidine ([(18)F]-FLT), a marker of cellular proliferation, has been used in positron emission tomography (PET) examination of gliomas. The aim of this study was to investigate whether the uptake of [(18)F]-FLT in glioma correlates with messenger RNA (mRNA) levels of the equilibrative nucleoside transporter 1 (ENT1), microvascular density (assessed by CD34 immunohistochemistry), and the blood-brain barrier (BBB) breakdown. A total of 21 patients with newly diagnosed glioma were examined with [(18)F]-FLT PET. Tumor lesions were identified as areas of focally increased [(18)F]-FLT uptake, exceeding that of surrounding normal tissue. Dynamic analysis of [(18)F]-FLT PET revealed correlations between the phosphorylation rate constant k 3 and ENT1 expression; however there was no correlation between the kinetic parameters and CD34 score. There was a good correlation between the gadolinium (Gd) enhancement score (evaluating BBB breakdown) and ENT1 expression, CD34 score, and Ki-67 index. This preliminary study suggests that ENT1 expression might not reflect accumulation of [(18)F]-FLT in vivo due to BBB permeability in glioma.

Carcinoma of the ampulla of Vater: morphological and immunophenotypical classification predicts overall survival

OBJECTIVES

The objective of the study was to verify if histopathological differentiation of ampullary carcinoma after surgical resection may be related to survival.

METHODS

The prognostic role of an accurate histological and immunohistochemical classification has been investigated in a multicentric series of carcinoma of the ampulla of Vater. Immunohistochemical expression of cytokeratin 7 (CK7) and CK20 were analyzed in the different morphological histotypes of ampullary cancers, and results were compared with overall survival.

RESULTS

Of 72 ampullary cancers, 48.6% were classified as pancreaticobiliary-type carcinomas, 43.1% were classified as intestinal-type carcinomas, and 8.3% were classified as "unusual"-type carcinomas. Cytokeratin 20 was expressed in 28 (90.3%) of the 31 intestinal-type carcinomas, whereas it was always negative in the pancreaticobiliary histotype; CK7 was expressed in 32 (91.4%) of the 35 pancreaticobiliary-type carcinomas and in 18 (58.1%) of the 31 intestinal-type carcinomas. By univariate analysis, overall survival was influenced significantly by pathological T factor, lymph node involvement, and histological/immunohistochemical subtyping. Furthermore, using a multivariate Cox regression model, lymph node metastasis and CK20 were identified as significant independent factors related to prognosis.

CONCLUSION

Our results prove the clinical use of ampullary cancer subclassification based on different histotypes and indicate the useful role of the CK7/CK20 expression profile for consistent histopathological classification and prognostic relevance.

Human equilibrative nucleoside transporter 1 expression predicts survival of advanced cholangiocarcinoma patients treated with gemcitabine-based adjuvant chemotherapy after surgical resection

OBJECTIVE

The aim of this study was to evaluate whether intratumoral human equilibrative nucleoside transporter 1 (hENT1) expression can predict the survival of advanced cholangiocarcinoma patients treated with adjuvant gemcitabine-based chemotherapy (AGC) after surgical resection.

BACKGROUND

There have been no reports concerning a useful predictive biomarker in patients with cholangiocarcinoma treated with adjuvant gemcitabine chemotherapy.

METHODS

Intratumoral hENT1 expression was investigated immunohistochemically in 105 patients with resected advanced cholangiocarcinoma. Relationships between intratumoral hENT1 expression and clinicopathological factors were evaluated by univariate and multivariate analyses. This study was a retrospective analysis on retrospectively collected tissue and data.

RESULTS

Fifty-one patients received AGC, and 54 did not. High and low intratumoral hENT1 expression was found in 74 (70%) and 31 patients (30%), respectively. There were no significant differences in clinicopathological factors between patients with high hENT1 expression and those with low hENT1 expression. Survival patients with high hENT1 expression were significantly better than those with low hENT1 expression among patients who received AGC (P = 0.008), but not among patients who did not (P = 0.894). Moreover, a significant difference in survival between patients who received AGC and those who did not was observed among patients with high hENT1 expression (P = 0.002), but not among patients with low hENT1 expression (P = 0.525). Intratumoral hENT1 expression was only an independent predictive factor for patients treated with AGC by multivariate analysis (P = 0.027).

CONCLUSIONS

Intratumoral hENT1 expression may be a potent predictive marker for advanced cholangiocarcinoma patients treated with AGC.

Expression characteristics of ENT1 in human hepatocellular carcinoma cells

AIM: To investigate the expression characteristics of equilibrative nucleoside transporter 1 (ENT1) in human hepatocellular carcinoma (HCC) cell lines.

METHODS: Human HCC cell lines HuH-7, HepG2 and Hep3B, and the breast cancer cell line MCF7 were used in this study. ENT1 was localized by immunofluorescence staining. Before and after treatment with roscovitine, a cyclin-dependent kinase inhibitor, the expression of ENT1 mRNA in the above cell lines was detected by reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS: ENT1 could be detected on the membrane of the three human HCC cell lines. The expression levels of ENT1 mRNA in HCC cell lines were higher than that in the breast cancer cell line (HuH-7: 0.756 ± 0.019; HepG2: 0.469 ± 0.041; Hep3B: 0.580 ± 0.030; MCF-7: 0.356 ± 0.029). The expression level of ENT1 mRNA differed significantly among the three human HCC cell lines. Treatment with roscovitine increased the expression level of ENT1 mRNA (0.737 ± 0.017 vs 0.345 ± 0.027, P < 0.05).

CONCLUSION: ENT1 was localized to the membrane of HCC cells. The expression levels of ENT1 mRNA vary among different HCC cell lines. Treatment with roscovitine increased the expression level of ENT1 mRNA in HCC cell lines.

Predictors of clinical outcomes of resected ampullary adenocarcinoma: a single-institution experience

BACKGROUND

In the absence of prospective data, the use of adjuvant therapy in ampullary adenocarcinoma is contingent upon the clinicopathological features which can correlate to 5-year post-operative survival and disease relapse.

METHODS

We investigated the factors associated with clinical outcomes among 72 patients who underwent pancreatoduodenectomy at the Cleveland Clinic from 1995 to 2007 for histologically confirmed adenocarcinoma of the ampulla of Vater.

RESULTS

R0 resection was achieved in 96% of patients (median age, 72 years; 58% males, 89% Caucasians). Nineteen patients experienced disease relapse after surgery and 61% were alive within 5 years of follow up. Thirty five percent of patients received some form of adjuvant therapy. Perineural tumor invasion (p < 0.01) and presence of ulcerated tumor on histopathology (p < 0.01) were associated with higher rates of tumor relapse and poor 5-year overall survival in multivariable analysis. Lymph node involvement (p = 0.02) also portended poor overall survival after adjustment for other covariates. Although adjuvant therapy was associated with poor clinical outcomes in univariate analysis, it demonstrated a favorable albeit non-significant trend in multivariable analysis.

CONCLUSIONS

Factors associated with poor clinical outcomes in this contemporary single-institution study, included perineural invasion, tumor ulceration, and lymph node involvement. No definite conclusion could be made in regards to adjuvant treatment.

Integrating pharmacogenetics into gemcitabine dosing--time for a change?

Increasing the efficacy of anticancer agents and avoiding toxic effects is a critical issue in clinical oncology. Identifying biomarkers that predict clinical outcome would ensure improved patient care. Gemcitabine is widely used to treat various solid tumors as a single agent or in combination with other drugs. The therapeutic index of gemcitabine is narrow, and abnormal pharmacokinetics leading to changes in plasma exposure is a major cause of adverse effects. A number of biomarkers have been proposed to predict efficacy of gemcitabine, focusing on molecular determinants of response identified at the tumor level. Genetic and functional deregulations that affect the disposition of a drug could be the reason for life-threatening adverse effects or treatment failure. In particular, deregulation of cytidine deaminase, the enzyme responsible for detoxification of most nucleotide analogs, should be examined. Identifying and validating biomarkers for pharmacogenetic testing before administration of gemcitabine is a step towards personalized medicine.

Prognostic roles of human equilibrative transporter 1 (hENT-1) and ribonucleoside reductase subunit M1 (RRM1) in resected pancreatic cancer

BACKGROUND

Pancreatic adenocarcinoma is a malignancy with a dismal prognosis. Previous studies have suggested that in pancreatic cancer, human equilibrative nucleoside transporter 1 (hENT-1) and ribonucleoside reductase subunit M1 (RRM1) expression may have prognostic value as well as predictive value with sensitivity to gemcitabine. This study investigated the prognostic value of hENT-1 and RRM1 expression in resected pancreatic cancer.

METHODS

Eighty-four patients who underwent pancreaticoduodenectomy from 2000 to 2005 were included in this study. Patients were followed for a median of 60 months (range, 44-110). Total RNA was isolated from macrodissected paraffin-embedded tumors. hENT-1 and RRM1 expression levels in tumors were evaluated by quantitative reverse transcription-polymerase chain reaction (QRT-PCR), normalized to 2 reference genes, and expressed as ΔCt (low ΔCt means high expression). Univariate and multivariable prognostic factors for overall survival (OS) and progression-free survival (PFS) were identified via Cox proportional hazards analysis.

RESULTS

Univariate analysis identified hENT-1, overall stage, lymphovascular invasion, perineural invasion, and adjuvant therapy as prognostic factors for both PFS and OS. Multivariate analysis confirmed the association of low expression of hENT-1 (ΔCt > 0.2027) (P = .007), perineural invasion (P = .021), and lack of adjuvant treatment (P < 0.001) with worse OS. Multivariate analysis also confirmed the association of low expression of hENT-1 (ΔCt > 0.5391) with worse PFS (P = .016) in addition to overall stage (P = .013), perineural invasion (P = .042), and lack of adjuvant treatment (hazard ratio 2.31, P = .029). RRM1 expression was not associated with OS or PFS in the current cohort.

CONCLUSIONS

Low expression of hENT-1 was associated with worse OS and PFS in patients with resected pancreatic adenocarcinoma independent of gemcitabine therapy.

Human equilibrative nucleoside transporter 1 and carcinoma of the ampulla of Vater: expression differences in tumour histotypes

The human equilibrative nucleoside transporter 1 (hENT1) is the major means by which gemcitabine enters human cells; recent evidence exists that hENT1 is expressed in carcinoma of the ampulla of Vater and that it should be considered as a molecular prognostic marker for patients with resected ampullary cancer. Aim of the present study is to evaluate the variations of hENT1 expression in ampullary carcinomas and to correlate such variations with histological subtypes and clinicopathological parameters. Forty-one ampullary carcinomas were histologically classified into intestinal, pancreaticobiliary and unusual types. hENT1 and Ki67 expression were evaluated by immunohistochemistry, and apoptotic cells were identified by the terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate biotin nick end labelling (TUNEL) method. hENT1 overexpression was detected in 63.4% ampullary carcinomas. A significant difference in terms of hENT1 and Ki67 expression was found between intestinal vs. pancreaticobiliary types (P=0.03 and P=0.009 respectively). Moreover, a significant statistical positive correlation was found between apoptotic and proliferative Index (P=0.036), while no significant correlation was found between hENT1 and apoptosis. Our results on hENT1 expression suggest that classification of ampullary carcinoma by morphological subtypes may represent an additional tool in prospective clinical trials aimed at examining treatment efficacy; in addition, data obtained from Ki67 and TUNEL suggest a key role of hENT1 in tumour growth of ampullary carcinoma.

Drug transporter pharmacogenetics in nucleoside-based therapies

This article focuses on the different types of transporter proteins that have been implicated in the influx and efflux of nucleoside-derived drugs currently used in the treatment of cancer, viral infections (i.e., AIDS) and other conditions, including autoimmune and inflammatory diseases. Genetic variations in nucleoside-derived drug transporter proteins encoded by the gene families SLC15, SLC22, SLC28, SLC29, ABCB, ABCC and ABCG will be specifically considered. Variants known to affect biological function are summarized, with a particular emphasis on those for which clinical correlations have already been established. Given that relatively little is known regarding the genetic variability of the players involved in determining nucleoside-derived drug bioavailability, it is anticipated that major challenges will be faced in this area of research.

Human nucleoside transporters: biomarkers for response to nucleoside drugs

This review describes recent advances in developing human nucleoside transporters (hNTs) as biomarkers to predict response to nucleoside analog drugs with clinical activity. Understanding processes that contribute to drug response or lack thereof will provide strategies to potentiate efficacy or avoid toxicities of nucleoside analog drugs. hNT abundance, evaluated by immunohistochemical methods, has shown promise as a predictive marker to assess clinical drug response that could be used to identify patients who would most likely benefit from nucleoside analog drug treatment.

Prognostic role of human equilibrative transporter 1 (hENT1) in patients with resected gastric cancer

Nucleoside transporter proteins are specialized proteins that mediate the transport of nucleosides and nucleoside analog drugs across the plasma membrane. The human equilibrative nucleoside transporter 1 (hENT1) is a member of these proteins and mediates cellular entry of gemcitabine, cytarabine, and fludarabine. The hENT1 expression has been demonstrated to be related with prognosis and activity of gemcitabine-based therapy in breast, ampullary, lung, and pancreatic cancer. We investigated the immunohistochemical expression of hENT in tumor samples from 111 patients with resected gastric adenocarcinoma, correlating these data with clinical parameters and disease outcomes. None of the patients received chemotherapy or radiation therapy before or after surgery as a part of an adjuvant or neoadjuvant program. On univariate survival analysis, the hENT1 expression was associated with overall survival (OS) and disease free survival (DFS). Specifically, those patients with overexpression of hENT1 showed a shorter OS (P = 0.021) and a shorter DFS (P = 0.033). Considering only the node positive patients, higher hENT levels were associated with significantly shorter median DFS (21.7 months; 95% CI 11.1-32.4) compared with patients with low expression of hENT1. The hENT1 expression was defined, in the lymph-node positive patients, as an independent prognostic factor (P = 0.019). Furthermore, considering only patients with diffuse or mixed tumors and lymph-node positive, the expression of hENT1 was strongly related with DFS and OS. Immunohistochemistry for the hENT1 protein carries prognostic information in patients with resected gastric cancer and holds promise as a predictive factor in chemotherapy decisions.

Establishment of six new human biliary tract carcinoma cell lines and identification of MAGEH1 as a candidate biomarker for predicting the efficacy of gemcitabine treatment

The aim of this study was to establish new biliary tract carcinoma (BTC) cell lines and identify predictive biomarkers for the potential effectiveness of gemcitabine therapy. Surgical specimens of BTC were transplanted directly into immunodeficient mice to establish xenografts, then subjected to in vitro cell culture. The gemcitabine sensitivity of each cell line was determined and compared with the genome-wide gene expression profile. A new predictive biomarker candidate was validated using an additional cohort of gemcitabine-treated BTC cases. From 55 BTC cases, we established 19 xenografts and six new cell lines. Based on their gemcitabine sensitivity, 10 BTC cell lines (including six new and four publicly available ones) were clearly categorized into two groups, and MAGEH1 mRNA expression in the tumor cells showed a significant negative correlation with their sensitivity to gemcitabine. Immunohistochemically, MAGEH1 protein was detected in three (50%) out of six sensitive cell lines, and four (100%) out of four resistant cell lines. In the validation cohort of gemcitabine-treated recurrence cases, patients were categorized into "effective" and "non-effective" groups according to the RECIST guidelines for assessment of chemotherapeutic effects. MAGEH1 protein expression was detected in two (40%) out of five "effective" cases and all four (100%) "non-effective" cases. We have established a new BTC bioresource that covers a wide range of biological features, including drug sensitivity, and is linked with clinical information. Negative expression of MAGEH1 protein serves as a potential predictive marker for the effectiveness of gemcitabine therapy in BTC.

Bone and brain metastases from ampullary adenocarcinoma

Ampullary carcinoma is the second most common cancer of the peri-ampullary area after pancreatic carcinoma and metastasizes mostly intra-abdominally and to the liver. Extra-abdominal metastases are less frequent. In this report we describe the case of a patient with resected adenocarcinoma of the ampulla of Vater who developed skeletal metastases in the lower extremity and brain metastases. We briefly discuss aspects of this comparatively rare gastrointestinal malignancy.

Changes in mRNA expression levels of solute carrier transporters in inflammatory bowel disease patients

Inflammatory bowel disease (IBD) is an inflammatory condition that affects the gastrointestinal tract. The solute carrier (SLC) superfamily of transporters comprise proteins involved in the uptake of drugs, hormones, and other biologically active compounds. The purpose of this study was to determine the mRNA expression levels of 15 solute carrier transporters in two regions of the intestine in IBD patients. Endoscopic biopsy specimens were taken from two locations (terminal ileum and colon) for histological examination and RNA extraction. We quantitatively measured the mRNA expression of 15 SLC transporters in 107 IBD patients (53 with Crohn's disease and 54 with ulcerative colitis) and 23 control subjects. mRNA expression was evaluated using the quantitative reverse transcription-polymerase chain reaction technique. We observed that in the ileum of IBD patients, mRNA levels for serotonin transporter, equilibrative nucleoside transporter (ENT) 1, ENT2, and organic anion-transporting polypeptide (OATP) 2B1 were significantly elevated, whereas levels for apical sodium-dependent bile acid transporter (ASBT) and organic zwitterion/cation transporter (OCTN) 2 were significantly lower. In colon, mRNA levels for ENT1, ENT2, concentrative nucleoside transporter (CNT) 2, OATP2B1, and OATP4A1 were significantly higher, whereas mRNA levels for OCTN2 were significantly decreased. In inflamed colon of IBD patients the mRNA expression levels of ENT1, ENT2, CNT2, OATP2B1, OATP4A1, and peptide transporter 1 were significantly higher. We conclude that intestinal SLC mRNA levels are dysregulated in IBD patients, which may be linked to the inflammation of the tissue and provides an indication about the role of inflammatory signaling in regulation of SLC expression.