hENT1 Expression Research Articles

IKZF1 gene deletions drive resistance to cytarabine in B-cell precursor acute lymphoblastic leukemia.

IKZF1-deletions occur in 10-15% of patients with B-cell precursor acute lymphoblastic leukemia (BCP-ALL) and predict a poor outcome. However, the impact of IKZF1-loss on sensitivity to drugs used in contemporary treatment protocols has remained underexplored. Here we show in experimental models and in patients that loss of IKZF1 promotes resistance to AraC, a key component of both upfront and relapsed treatment protocols. We attribute this resistance, in part, to diminished import and incorporation of cytarabine (AraC) due to reduced expression of the solute carrier hENT1. Moreover, we find elevated mRNA expression of Evi1, a known driver of therapy resistance in myeloid malignancies. Finally, a kinase directed CRISPR/Cas9-screen identified that inhibition of either mediator kinases CDK8/19 or casein kinase 2 can restore response to AraC. We conclude that this high-risk patient group could benefit from alternative antimetabolites, or targeted therapies that resensitize the cells to AraC.

Abstract 5865: Characterization and resistance mechanisms of PNP inhibitor forodesin-resistant cell lines

Abstract Background: The enzyme purine nucleoside phosphorylase (PNP) is involved in the purine salvage pathway and is present at high levels in lymphoid tissues. Children born with PNP deficiency are known to have significantly reduced T-cell counts but relatively normal B-cell immunity, suggesting PNP as one of the most promising therapeutic targets for T-cell malignancies. Forodesine (For, BCX-1777), a novel PNP inhibitor, was approved in Japan for the treatment of relapsed/refractory PTCL. To understand the cytotoxic effect of For and its mechanism of action, we established a For-resistant (For-R) leukemia cell line and explored the mechanism of resistance. Methods: We established two For-R T-lymphoblastic leukemia cell lines (CCRF-CEM and MOLT4) through repeated escalating exposure to For and 2’-deoxyguanosined(dGuo). Gene expression analysis was performed to identify the mechanisms of resistance. Results: For-R cells showed very high resistance compared to parental cells (IC50 value, CEM/CEM-R 4.2nM/>5x105nM, MOLT4/MOLT4-R 8nM/>5x105nM). When cross-resistance was examined in these For-R cells showed mild resistance to cytarabine. The expression of hENT1, a nucleoside transporter, was examined and found to be upregulated in both CEM-R and MOLT4-R cells, while the expression level of deoxycytidine kinase (dCK) was unchanged in both cells. Next, high performance liquid chromatography was used to assess the intracellular dGTP in each parental and its For-R cells. In the parental cells, intracellular dGTP levels increased promptly 4-6 hours after fosteredin administration, whereas in resistant cells, intracellular dGTP levels were higher than before fosteredin administration, and there was little change in dGTP levels after administration. Conclusion: The established For-R cell line acquired a high resistance to For and showed high intracellular dGTP levels. Imbalance in intracellular GTP levels may be involved in the induction of cell death by For. IC50 value of each cell lines Citation Format: Naoko Hosono, Kana Oiwa, Toshiki Tasaki, Rie Nishi, Luigi Scott, Owen A. O’Connor, Takahiro Yamauchi. Characterization and resistance mechanisms of PNP inhibitor forodesin-resistant cell lines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5865.

The prognostic and predictive role of class III β-Tubulin and hENT1 expression in patients with advanced pancreatic ductal adenocarcinoma

BackgroundFOLFIRINOX and gemcitabine-nabpaclitaxel (GnP) are standard first-line treatment regimens for advanced pancreatic ductal adenocarcinoma (PDAC). However, currently, there is a lack of predictive biomarkers to aid in the treatment selection. We aimed to explore the prognostic and predictive value of class III β-Tubulin (TUBB3) and human equilibrative nucleoside transporter 1 (hENT1) expression, which have previously been shown to be associated with taxane and gemcitabine resistance in advanced PDAC. MethodsWe conducted a retrospective analysis of 106 patients with advanced PDAC treated with GnP and/or FOLFIRINOX at our institution. TUBB3 and hENT1 immunohistochemical staining was performed on tumor specimens and subsequently evaluated based on the intensity and percentage of expression. ResultsIn patients who received the GnP regimen, a high combined score (TUBB3low/hENT1high) was associated with a higher DCR and longer PFS compared to those with intermediate (TUBB3high/hENT1high or TUBB3low/hENT1low) and low score (TUBB3high/hENT1low). In the multivariate analysis, a high combined score was an independent predictor of higher DCR (OR:11.96; 95 % CI:2.61–54.82; p = 0.001) and longer PFS (HR:0.33; 95%CI:0.18–0.60; p < 0.001). However, there was no difference in response rates or PFS based on TUBB3 and hENT1 expression among patients receiving the FOLFIRINOX regimen. ConclusionOur findings indicate that tumor TUBB3 and hENT1 expression may predict the efficacy of the GnP regimen, and low TUBB3 and high hENT1 expression (TUBB3low/hENT1high) are associated with a higher DCR and longer PFS in patients treated with GnP. Evaluating TUBB3 and hENT1 jointly can identify the patients most (as well as least) likely to benefit from GnP chemotherapy.

Nicotine promotes epithelial to mesenchymal transition and gemcitabine resistance via hENT1/RRM1 signalling in pancreatic cancer and chemosensitizing effects of Embelin-a naturally occurring benzoquinone

Pancreatic cancer is lethal due to poor prognosis with 5-year survival rate lesser than 5 %. Gemcitabine is currently used to treat pancreatic cancer and development of chemoresistance is a major obstacle to overcome pancreatic cancer. Nicotine is a known inducer of drug resistance in pancreatic tumor micro-environment. Present study evaluates chemoresistance triggered by nicotine while treating with gemcitabine and chemosensitization using Embelin. Embelin is a naturally occurring benzoquinone from Embelia ribes possessing therapeutic potency. To develop nicotine-induced chemo-resistance, pancreatic cancer cells PANC-1 and MIA PaCa-2 were continuously treated with nicotine followed by exposure to gemcitabine. Gemcitabine sensitivity assay and immunoblotting was performed to assess the chemo-resistance. Antiproliferative assays such as migration assay, clonogenic assay, Mitochondrial Membrane Potential (MMP) assay, dual staining assay, comet assay, Reactive Oxygen Species (ROS) assay, cell cycle analysis and immunoblotting assays were performed to witness the protein expression involved in chemoresistance and chemosensitization. Epithelial to mesenchymal transition was observed in nicotine induced chemoresistant cells. Gemcitabine sensitivity assay revealed that relative resistance was increased to 6.26 (p < 0.0001) and 6.45 (p < 0.0001) folds in resistant PANC-1 and MIA PaCa-2 compared to parental cells. Protein expression studies confirmed resistance markers like hENT1 and dCK were downregulated with subsequent increase in RRM1 expression in resistant cells. Embelin considerably decreased the cell viability with an IC50 value of 4.03 ± 0.08 μM in resistant PANC-1 and 2.11 ± 0.04 μM in resistant MIA PaCa-2. Cell cycle analysis showed Embelin treatment caused cell cycle arrest at S phase in resistant PANC-1 cells; in resistant MIA PaCa-2 cells there was an escalation in the Sub G1. Embelin upregulated Bax, γH2AX, p53, ERK1/2 and hENT1 expression with concomitant down regulation of Bcl-2 and RRM1. Bioactive molecule embelin, its combination with gemcitabine could provide new vistas to overcome chemo resistance in pancreatic 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.

1638P The prognostic and predictive role of class III β-tubulin and hENT1 expression in patients with advanced pancreatic ductal adenocarcinoma

1638P The prognostic and predictive role of class III β-tubulin and hENT1 expression in patients with advanced pancreatic ductal adenocarcinoma

C-reactive protein is a prognostic biomarker in pancreatic ductal adenocarcinoma patients.

The 5-year survival rate of pancreatic ductal adenocarcinoma (PDAC) is approximately 11% and has only improved marginally over the last three decades. For operable PDAC, resection and adjuvant FOLFIRINOX chemotherapy is standard of care. There is growing interest in perioperative regimens to improve outcomes. The non-randomized Phase II study "Gemcitabine and Abraxane for resectable Pancreatic cancer" (GAP) demonstrated the feasibility of perioperative gemcitabine/abraxane. Long-term survival in PDAC requires an effective immune response; hence, we undertook this translational study of the GAP trial cohort to identify immune-oncology biomarkers for clinical use. We combined Nanostring nCounter technology with immunohistochemistry to investigate the correlation between gene expression and overall patient survival. Findings were investigated in samples from the International Cancer Genome Consortium (ICGC, n=88) and the Australian Pancreatic Genome Initiative (APGI, n=227). We confirmed that human equilibrative nucleoside transporter 1 (hENT1) expression was not a prognostic marker in PDAC but patients with high levels of hENT1 were more likely to live longer than 24 months post-surgery. Additionally, CD274 (PD-L1) and two novel biomarkers of survival, cathepsin W (CTSW) and C-reactive protein (CRP), were identified in the GAP cohort (n=19). CRP expression was confirmed in data from the ICGC. Although PD-L1 and CTSW proteins were not significant across all three cohorts, results show that low CRP mRNA and protein expression are associated with longer overall survival in all three patient groups. PDAC patients with long survival have higher hENT1 expression levels. Furthermore, CRP expression is a biomarker of poor prognosis following perioperative chemotherapy and resection in PDAC patients and thus may be useful for identifying patients who could benefit from more aggressive adjuvant strategies.

Gestational Diabetes—Placental Expression of Human Equilibrative Nucleoside Transporter 1 (hENT1): Is Delayed Villous Maturation an Adaptive Pattern?

Gestational diabetes mellitus (GDM) is a metabolic disease that can affect placental villous maturation and villous vascularity. The main effects of GDM on placental growth are a delay of villous maturation (DVM) and decreased formation of vasculo-syncytial membranes (VSM). Human equilibrative nucleoside transporter-1 (hENT1) is an adenosine transporter expressed in the human umbilical vein endothelial cells (HUVEC) and human placental microvascular endothelium cells (hPMEC). Its role is crucial in maintaining physiological fetal adenosine levels during pregnancy, and its reduction has been described in GDM. Twenty-four placentas from pregnancies with a confirmed diagnosis of GDMd and twenty-four matched non-GDM placentas (controls) were retrospectively analyzed to investigate the immunohistochemical expression of hENT1 in HUVEC and hPMEC. The study included the quantitative evaluation of VSM/mm2 in placental tissue and the immunohistochemical quantitative evaluation of Ki-67, PHH3, and p57 in villous trophoblast. hENT1 expression was higher in all the vascular districts of the control cases compared to the GDMd placentas (p &lt; 0.0001). The VSM/mm2 were lower in the GDMd cases, while the Ki-67, PHH3, and p57 were higher when compared to the control cases. To our knowledge, this is the first report of hENT1 expression in the human placentas of GDM patients. The absence/low expression of hENT1 in all the GDMd patients may indicate a potential role in microvascular adaptative mechanisms. The trophoblasts’ proliferative/antiapoptotic pattern (high Ki-67, high PHH3, and high p57 count) may explain the statistically significant lower number of VSM/mm2 found in the GDMd cases.

Abstract 173: Genomic characterization of patient-derived pancreatic cancer organoids

Abstract Pancreatic ductal adenocarcinoma (PDAC) is a leading cause of cancer death with few effective therapies. Patient-derived organoids (PDOs) are a 3-D culture model that allow primary tumour cells to propagate, and have gained considerable traction in many cancer types such as PDAC. However, concerns remain regarding whether these models can predict what occurs in patients. We hypothesize that genomic and transcriptomic drift occurring in PDO models impacts the fidelity of drug response. To investigate, matched WGS and bulk RNAseq was performed on paired PDAC organoids and tumour tissue (n=41). Core biopsies were obtained from in patients with Stage III-IV PDAC enrolled in the COMPASS trial (NCT02750657) and divided for sequencing and organoid generation. Tumour cellularity was enriched by laser capture microdissection. Although alterations in the four major driver genes (KRAS, TP53, SMAD4, CDKN2A) remained consistent, other genomic differences were identified. SNV count was higher in organoids (median 6584 vs 5931, p&amp;lt;0.0001), and enriched in SBS5 mutational signature (p&amp;lt;0.0001). This was not significantly correlated with passage number, and private mutations were identified in both tumours and organoids (median 67% overlap). Two organoids showed significant shifts in ploidy, with both diploid to polyploid shifts and vice versa observed. In the transcriptome, expression of Basal-like genes (KRT5, TP63) was decreased. Bias towards the Classical transcriptomic subtype have previously been observed in PDAC organoid cultures. PDO responses to 5-FU, irinotecan, and oxaliplatin correlated with patient response to FFX (n=22, 72% concordance). However, PDO responses to gemcitabine and paclitaxel were poorly predictive of patient responses to GnP (n=10, 38% concordance), and notably, expression of the biomarker hENT1 was not correlated in matched tumors and PDOs (R=0.17, p=0.40). Despite this, tumour expression of the biomarker hENT1 successfully stratified patient responses to gemcitabine, and organoid hENT1 expression was correlated to gemcitabine response in vitro (R=0.47, p=0.005), indicating that transcriptomic drift may be a major contributor to discrepancies in patient-PDO drug response. In summary, organoids recapitulate major histologic features and driver mutations of patient tumours, but genetic drift and subclonal selection are observed even at lower passages. Further study is required to improve the utility of organoids in translational precision medicine. Citation Format: Irene Y. Xie, Yuanchang Fang, Amy X. Zhang, Karen Ng, Zhen-Mei Liu, Eugenia Flores-Figueroa, Gun Ho Jang, Stephanie Ramotar, Anna Dodd, Julie Wilson, Jennifer J. Knox, Steven Gallinger, Faiyaz Notta. Genomic characterization of patient-derived pancreatic cancer organoids [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 173.

Abstract 392: Targeting drug-resistant acute myeloid leukemia (AML) clone using casein kinase II inhibitor

Abstract Introduction: Resistance to frontline cytotoxic therapy is rampant in AML. Molecular mechanisms promoting drug resistance are being identified to develop an effective strategy to overcome resistance. Protein kinase CK2 (casein kinase II) is a constitutively active, serine-threonine kinase that promotes cell survival and resistance to apoptosis in AML. A selective inhibitor of CK2, CX-4945 shows in vivo therapeutic efficacy in AML patient-derived xenografts. Here we report that CK2 kinase activity is high in AML cells resistant to cytarabine. Cytarabine-resistant cells are enriched for leukemia stem cells (CD34+/38-) and expansion of TP53 mutant clones. Specific inhibitors of CK2, CX4945 show selective cytotoxicity against the cytarabine-resistant cells. Methods: We developed cytarabine-resistant AML cell lines (MOLM-13, MV4-11, U937, Kasumi-1). We used TP53 mutant clone isolated and expanded from cytarabine resistant MV4-11 cell line. Gene expression of cytarabine-resistant AML cells and that of cell lines with and without CX-4945 treatment was analyzed using RNA sequencing. mRNA expression of genes was measured using qPCR and protein level was measured using western blot. Drug response and drug synergy were assessed using MTT assay. AML patient-derived xenograft was used to evaluate in vivo therapeutic efficacy of the combination of cytarabine and CX-4945. Results: Cytarabine-resistant cells have high expression of CK2. Gene expression analysis shows that the cytarabine metabolism gene is significantly altered in cytarabine-resistant cells and CX4945-treated AML cells. NT5C2 is a cytosolic nucleotidase that dephosphorylates monophosphates, preventing cytarabine from being phosphorylated to active form. hENT1 is a nucleoside transporter that brings cytarabine into the cells for metabolism. In cytarabine resistant cells, NT5C2 has been found to be high while hENT1 is low, preventing ideal cytarabine metabolism. CX4945 treatment decreased the expression of NT5C2 and increases expression of hENT1. Cytarabine sensitivity is restored following genetic inhibition (shRNA) or treatment with a CK2 inhibitor. AML xenograft mice treated with a combination of CX-4945 and cytarabine have decreased leukemia burden and prolonged survival compared to either drug alone. Conclusion: These results suggest that: 1) Overactive CK2 promotes AML drug resistance in leukemia stem cells; 2) CK2 inhibitor CX-4945 selectively targets cytarabine-resistant cells; 3) The potential role of CK2 in leukemia stem cell survival and drug resistance in vivo needs further evaluation. Citation Format: Katherine Mercer, Koby Duke, Rajesh Rajaiah, Muhammad Daniyal, Yi Qiu, Sinisa Dovat, Yasin Uzun, Lijun Zhang, Suming Huang, Morgann Klink, Chandrika Gowda. Targeting drug-resistant acute myeloid leukemia (AML) clone using casein kinase II inhibitor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 392.

HENT1’s role in adjuvant intra-arterial gemcitabine-based chemotherapy for resectable pancreatic cancer patients

BackgroundWe aimed to verify the role of hENT1 as a prognostic predictor for patients with resectable pancreatic ductal adenocarcinoma (PDAC) who underwent radical resection followed by intra-arterial infusion of gemcitabine-based regimen.MethodsWe collected surgical samples from 102 patients with resectable PDAC who received radical resection followed by intra-arterial infusion of gemcitabine-based regimen. The hENT1 expression with the help of immunohistochemistry was conducted using formalin-fixed and paraffin embedded tissues. The Kaplan–Meier analyses and Cox regression were used to evaluate the mortality hazard associated with the discrepancy between strong and weak of hENT1 expression. Patients’ clinical and pathological characteristics were compared between the two groups, then the role of hENT1 as a prognostic predictor was further explored.ResultsA total of 102 patients were included to assess the hENT1 expression. 50 patients were classified into high hENT1 expression group, the other 52 patients were attributed into low hENT1 expression group. High hENT1 expression was related to a significantly improved overall survival (OS) (p = 0.014) and disease-free survival (DFS) (p = 0.004). Both univariate (p = 0.001) and multivariate analyses (p < 0.001) indicated that high hENT1 expression was related to a decreased mortality.ConclusionsHigh expression of hENT1 is positive prognostic factor for adjuvant intra-arterial gemcitabine-based chemotherapy in resectable PDAC.

Human equilibrative nucleoside transporter 1 (hENT1) and deoxycytidine kinase (DCK) are predictive biomarkers for Gemcitabine-based chemoradiotherapy in resected pancreatic cancer patients: a retrospective cohort study

Background and Aim Pancreatic cancer is reported to be one of the cancer-related deaths all over the world. Gemcitabine has been identified as one of the important therapies of malignant diseases. Gemcitabine cellular uptake is allowed by the transporter protein, human equilibrative nucleoside transporter 1 (hENT1). Gemcitabine is phosphorylated by deoxycytidine kinase (dCK) to its active metabolites intracellularly. This study aimed to determine retrospectively the correlation between hENT1 and dCK expression by immunohistochemistry and the overall survival outcome in pancreatic cancer patients who underwent resection and received gemcitabine chemotherapy postoperatively. Materials and methods The immunohistochemical analysis was accomplished on samples from 140 patients, who underwent pancreatic cancer resection and was treated by gemcitabine. Immunostaining was done by two expert pathologists and both are blind to patient’s characteristics. The intensity of staining of the tumor determines the scoring for hENT1 and dCK. Results Of the 140 tissue samples, 73 (52.1%) had detectable hENT1 cell membrane immunostaining and 67 samples (47.8%) without detectable hENT1. Patients who showed no significant hENT1 immunostaining had a median survival of 6 months, while patients who showed significant hENT1 staining had a median survival longer by 17 months. Of the 140 tissue samples, 52 (37.1%) had detectable dCK cytoplasmic immunostaining and 88 samples (62.9%) without detectable dCK. Patients who showed no significant dCK immunostaining had a median survival of 6.57 months, while patients who showed significant dCK staining had a median survival longer by 19 months. Conclusion In patients who received gemcitabine after pancreatic resection, a high expression of hENT1 and dCK are significantly correlated with a longer survival. In addition, in patients who underwent pancreatic cancer resection, immunohistochemical analysis of hENT1 and dCK are considered significant predictive markers to choose patients responding to gemcitabine therapy.

Mucin 4 Confers Gemcitabine Resistance and an Unfavorable Prognosis in Patients with Cholangiocarcinoma via AKT Activation.

Cholangiocarcinoma (CCA) exhibits aggressive biological behavior and a poor prognosis. Gemcitabine (GEM)-based chemotherapy is the first-line chemotherapy for advanced CCA but has a response rate of only 20-30%. Therefore, investigating treatments to overcome GEM resistance in advanced CCA is crucial. Among mucin (MUC) family members, MUC4 showed the greatest increase in the resistant versus parental sublines. MUC4 was upregulated in whole-cell lysates and conditioned media from gemcitabine-resistant (GR) CCA sublines. MUC4 mediated GEM resistance by activating AKT signaling in GR CCA cells. The MUC4-AKT axis induced BAX S184 phosphorylation to inhibit apoptosis and downregulated GEM transporter human equilibrative nucleoside transporter 1 (hENT1) expression. The combination of AKT inhibitors and GEM or afatinib overcame GEM resistance in CCA. In vivo, capivasertib (an AKT inhibitor) increased GEM sensitivity in GR cells. MUC4 promoted EGFR and HER2 activation to mediate GEM resistance. Finally, MUC4 expression in patient plasma correlated with MUC4 expression. Paraffin-embedded specimens from non-responders expressed significantly more MUC4 than did those from responders, and this upregulation was associated with poor progression-free survival and overall survival. In GR CCA, high MUC4 expression promotes sustained EGFR/HER2 signaling and AKT activation. The combination of AKT inhibitors with GEM or afatinib might overcome GEM resistance.

Selected Articles from This Issue

Davis and colleagues report the first systematic assessment of the safety and pharmacokinetics of dual immune checkpoint inhibition with ipilimumab and nivolumab in pediatric, adolescent, and young adult patients with relapsed or refractory sarcoma. They establish a recommended phase II dose of nivolumab (3 mg/kg) plus ipilimumab (1 mg/kg) and found the combination to be generally well tolerated. In expanded phase II cohorts, the authors observed two sustained partial responses. They further demonstrate that increased ipilimumab dosing (3 mg/kg) in combination with nivolumab (1 mg/kg) carries higher toxicity without clinical benefit in this population.Advanced stage head and neck squamous cell carcinoma (HNSCC) patients are at a high risk of recurrent disease. Due to dismal 5-year survival rates, such patients are in dire need of effective adjuvant therapy. Everolimus, an mTOR inhibitor, has documented activity in HNSCC and is well tolerated with minimal long-term toxicity. In this placebo-controlled phase II trial, Nathan and colleagues are the first to show promising results using everolimus as adjuvant therapy after complete response to definitive treatment in a subset of HPV-negative patients with advanced stage disease. In particular, HPV-negative TP53 mutated tumors appear to yield the best benefit. Thus, subsequent trials using everolimus in this patient population are warranted.TLR9 agonists demonstrated efficacy in activation of the innate and adaptive immune system in preclinical models. Babiker and colleagues investigated the activity of tilsotolimod, an investigational synthetic TLR9 agonist, in patients with refractory solid tumors after progression on standard of care therapies. This early phase clinical trial established safety, maximum tolerated dose, and demonstrated early signs of efficacy of tilsotolimod. In addition, translational data revealed activation of the innate and adaptive immune system through the type I interferon (IFN) pathway, IFNγ and IFNα gene upregulation, increase in inflammatory chemokines, activation of myeloid dendritic cells and antigen presentation, and an increase in genes for checkpoint and costimulatory proteins. The translational results suggest further investigation of tilsotolimod in combination with checkpoint inhibitors in solid tumors.Biomarkers are urgently needed to select chemotherapy regimens in pancreatic ductal adenocarcinoma (PDAC). In this study, Perera and colleagues investigated whether mRNA expression levels of hENT1 predict responsiveness to gemcitabinenab-paclitaxel (GnP) in patients with advanced PDAC. The results of this prospective observational clinical trial using tumor-enriched RNA sequencing revealed higher response rates and improved survival in patients receiving GnP, when tumors were considered hENT1high compared to those that were hENT1low. No difference in response or survival were seen in patients receiving modified FOLFIRINOX. An interaction analysis confirmed hENT1 as a predictive biomarker for GnP response. This suggests that hENT1 expression can be used to identify patients who will respond to GnP.

Combination treatment with hENT1 and miR-143 reverses gemcitabine resistance in triple-negative breast cancer

BackgroundTriple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer and is susceptible to develop gemcitabine (GEM) resistance. Decreased expression of human equilibrative nucleoside transporter 1 (hENT1) accompanied by compensatory increase of glycolysis is strongly associated with GEM resistance in TNBC. In this study, we investigated the treatment feasibility of combined hENT1 upregulation and miR-143-mediated inhibition of glycolysis for reversing GEM resistance in TNBC.MethodsExperiments were performed in vitro and in vivo to compare the efficacy of GEM therapies. In this study, we established stable drug-resistant cell line, GEM-R cells, from parental cells (MDA-MB-231) through exposure to GEM following a stepwise incremental dosing strategy. Then GEM-R cells were transfected by lentiviral plasmids and GEM-R cells overexpressing hENT1 (GEM-R-hENT1) were established. The viability and apoptosis of wild-type (MDA-MB-231), GEM-R, and GEM-R-hENT1 cells treated with GEM or GEM + miR-143 were analyzed by CCK8 assay and flow cytometry. The RNA expression and protein expression were measured by RT-PCR and western blotting respectively. GEM uptake was determined by multiple reaction monitoring (MRM) analysis. Glycolysis was measured by glucose assay and 18F-FDG uptake. The antitumor effect was assessed in vivo in a tumor xenograft model by evaluating toxicity, tumor volume, and maximum standardized uptake value in 18F-FDG PET. Immunohistochemistry and fluorescence photography were taken in tumor samples. Pairwise comparisons were performed using Student’s t-test.ResultsOur results represented that overexpression of hENT1 reversed GEM resistance in GEM-R cells by showing lower IC50 and higher rate of apoptosis. MiR-143 suppressed glycolysis in GEM-R cells and enhanced the effect of reversing GEM resistance in GEM-R-hENT1 cells. The therapeutic efficacy was validated using a xenograft mouse model. Combination treatment decreased tumor growth rate and maximum standardized uptake value in 18F-FDG PET more effectively.ConclusionsCombined therapy of exogenous upregulation of hENT1 expression and miR-143 mimic administration was effective in reversing GEM resistance, providing a promising strategy for treating GEM-resistant TNBC.

TH2.6 Evaulation of the prognostic utility for hENT 1 transmembranous protein in resected hilar cholangiocarcinoma patients

Abstract Aims Human equilibriative nucleoside transporter protein 1 (hENT1) facilitates nucleoside transport into the cell. Immunohistochemically-detected hENT1 is increased in cholangiocarcinoma tumour cells and in highly metabolising cells. The Mackey 10D7G2 hybridoma has demonstrated prognostic utility in Pancreatic Ductal Adenocarcinoma. The Proteintech Polyclonal hENT1 antibody's prognostic utility has not been assessed. Cellular Ki67 expression is linked to tumour proliferation. This study aims to assess the antibodies’ prognostic utility for resectable hilar cholangiocarcinoma. Methods Between 2009–2016, 54 patients underwent resection for peri-hilar cholangiocarcinoma. Formalin-Fixed Paraffin Embedded blocks from 44 specimens were retrieved. A Tissue-Matched Array was constructed and stained for each antibody. H-scores were utilised to determine expression intensity. Correlation of expression was determined by Pearson correlation co-efficient and Chi-squared. Silencing RNA for transfected HepG2 cell-lines was used to determine accurate hENT1 staining by the Proteintech antibody. Demographic and survival characteristics were acquired from a prospectively held database, and were calculated with global log-rank calculations. Results There was significant correlation between the Mackey and Proteintech antibodies (p&amp;lt;0.001), and between the Proteintech antibody and Ki67 expression (p= 0.02). Knockdown of hENT1 with silencing RNA transfected HepG2 cells was confirmed by Western blot. The antibodies (Mackey; Proteintech; Ki67) showed no significance for predicting OS (p= 0.75; 0.63; 0.22 respectively). Nodal stage (p= 0.03) and tumour differentiation (p= 0.02) showed prognostic utility. Conclusion While the Proteintech antibody demonstrates concordance with the 10D7G2 antibody in determining hENT1 expression, they didn't demonstrate significant prognostic ability. Standard histopathological co-variates retain prognostic utility within the cohort.

Antiproliferative and apoptotic activity of gemcitabine-lauric acid conjugate on human bladder cancer cells.

Objective(s):Gemcitabine is a first-line drug for the treatment of bladder cancer. One of the most important mechanisms of gemcitabine resistance is the low expression of cellular membrane transporter hENT1. Various derivatives containing fatty acid side chains have been developed in order to facilitate gemcitabine uptake and prolong its retention in cells, such as CP-4126. In this study, the anti-tumor effect and mechanism of a new derivative of gemcitabine named SZY-200 on bladder cancer cells were investigated. SZY-200 was assembled from the gemcitabine-lauric acid conjugate.Materials and Methods:Antiproliferative activities of SZY-200 and lauric acid were evaluated using CCK-8 assay and clonogenic survival assay. The hENT1 inhibitor NBMPR was employed to determine the role of hENT1 in the apoptotic activity of GEM, CP-4126, and SZY-200. RT-qPCR, flow cytometry, fluorescence microscope, western blotting, and wound healing assay were used to study the mechanisms of SZY-200. The target genes were predicted using the BATMAN-TCM database.Results:Our data showed that SZY-200 could inhibit the proliferation of bladder cancer cells by inducing cell cycle arrest and apoptosis. The inhibitory effects were comparable to gemcitabine and CP-4126. SZY-200 does not rely on hENT1 to help it enter bladder cancer cells. Also, we found that lauric acid could inhibit the proliferation of bladder cancer cells. SZY-200 could down-regulate the expressions of PPARG and PTGS2 which were related to the occurrence and development of bladder cancer.Conclusion:SZY-200 has the same or more advantages as CP-4126 and could be an ideal candidate drug for further in vivo investigation.

O-L09 Determining the Prognostic Utility of Immuno-histochemically detected Trans-membranous Human Equilibriative Nucleoside Transporter 1 (hENT1) in Patients Undergoing Hilar Cholangiocarcinoma Resection

Abstract Background Human equilibriative nucleoside transporter protein 1 (hENT1) is a trans-membranous protein which facilitates nucleoside transport in to the cell. Immunohistochemically-detected hENT1 abundance is increased in cholangiocarcinoma tumour cells compared to matched non-tumour cells and increased in highly metabolising cells. The privately-held Mackey 10D7G2 hybridoma has demonstrated prognostic utility in Pancreatic Ductal Adenocarcinoma patients. The commercially available Proteintech Polyclonal hENT1 antibody’s prognostic utility has not been previously assessed. Cellular Ki67 expression has been linked to mitotic indices of tumour proliferation. This proof-of-concept study aims to assess the antibodies prognostic utility for hilar cholangiocarcinoma patients undergoing surgical resection. Methods Between February 2009 and February 2016 54 patients underwent resection for peri-hilar cholangiocarcinoma. Formalin-Fixed Paraffin Embedded (FFPE) blocks from a sub-set of 44 resected specimens were retrieved. Appropriate areas of tumour were sampled from the blocks and a Tissue-Matched Array (TMA) was constructed. The TMA underwent staining for each antibody. H-scores were utilised to determine intensity of expression. Correlation of expression between antibodies was determined by Pearson correlation co-efficient and Chi-squared where appropriate. Silencing RNA transfected HepG2 cell-lines was used to determine hENT1 staining by the Proteintech antibody. Demographic and survival characteristics for the patients were acquired from a prospectively held database linked to Hospital Episode Statistics. Survival characteristics were calculated with global log-rank calculations. Results There was significant correlation between the Mackey 10D7G2 and the Proteintech antibodies (p &amp;lt; 0.001). There was significant correlation between the Proteintech hENT1 antibody expression and Ki67 expression (p = 0.02). Knockdown of hENT1 with silencing RNA transfected HepG2 cells was confirmed by Western blot in a time-dependent fashion over 72 hours. The antibodies (Mackey; Proteintech; Ki67) did not achieve significance for predicting OS (p = 0.75; 0.63; 0.22 respectively). Nodal stage (p = 0.03) and grade of tumour differentiation (p = 0.02) were the univariate tumour variables with prognostic utility. Conclusions While the Proteintech antibody demonstrates concordance with the 10D7G2 antibody in determining hENT1 expression the antibodies did not demonstrate significant prognostic ability in this proof-of-concept study. Standard histopathological co-variates retain prognostic utility within the cohort.

ET-7 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.

ET-6 Gemcitabine radiosensitization primes irradiated malignant meningioma cells for senolytic elimination by navitoclax

BACKGROUND: Malignant meningioma is an aggressive tumor that requires adjuvant radiotherapy after surgery, yet there has been no standard systemic therapy established so far. We have demonstrated that malignant meningioma cells are exquisitely sensitive to gemcitabine due to their increased expression of hENT1 and dCK, which play critical roles in the intracellular transport and activation of gemcitabine, respectively (Takeda et al. Oncotarget 8:90996, 2017; Yamamoto et al., Neuro-Oncol 23:945, 2021). Significantly, in support of our findings, the efficacy and safety of gemcitabine have recently been documented in a small case series of patients with recurrent meningiomas, which has further led to a phase 2 clinical trial to evaluate the efficacy of gemcitabine in recurrent high-grade meningiomas (Khaddar et al., South Asian J Cancer 9:261, 2020). Besides its efficacy as a single agent, gemcitabine reportedly has a radiosensitizing effect in pancreatic cancer. However, it remains unknown whether or how gemcitabine interacts with ionizing radiation (IR) in malignant meningioma cells. METHODS: We examined radiosensitization effects of gemcitabine using malignant meningioma cell lines and xenografts (s.c. and i.c.) and explored the underlying mechanisms. RESULTS: Gemcitabine sensitized malignant meningioma cells remarkably to IR through the induction of senescence both in vitro and in vivo. Gemcitabine augmented the intracellular production of reactive oxygen species (ROS) by IR, which, together with cell growth suppression/senescence induced by this combination, was inhibited by N-acetyl-cysteine, suggesting a pivotal role for ROS in these combinatorial effects. Navitoclax, a senolytic drug, further enhanced the effects of the combination of gemcitabine and IR in vitro and in vivo by strongly inducing apoptotic cell death in senescent cells. CONCLUSION: These results suggest that gemcitabine is not only a promising radiosensitizer for malignant meningioma but also creates in combination with IR a therapeutic vulnerability of senescent meningioma cells to senolytics. (submitted for publication)