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Video 3. N+/E- cells 3D reconstruction animation shows localization of ENT1 (red) and DAPI (blue)

Epithelial–mesenchymal transition (EMT) in cancer cells drives cancer chemoresistance, yet the molecular events of EMT that underpin the acquisition of chemoresistance are poorly understood. Here, we demonstrate a loss of gemcitabine chemosensitivity facilitated by human equilibrative nucleoside transporter 1 (ENT1) during EMT in pancreatic cancer and identify that cadherin switching from the epithelial (E) to neuronal (N) type, a hallmark of EMT, contributes to this loss. Our findings demonstrate that N-cadherin decreases ENT1 expression, membrane localization, and gemcitabine transport, while E-cadherin augments each of these. Besides E- and N-cadherin, another epithelial cell adhesion molecule, EpCAM, played a more prominent role in determining ENT1 membrane localization. Forced expression of EpCAM opposed cadherin switching with restored ENT1 expression, membrane localization, and gemcitabine transport in EMT-committed pancreatic cancer cells. In gemcitabine-treated mice, EpCAM-positive tumors had high ENT1 expression and reduced metastasis, whereas tumors with N-cadherin expression resisted gemcitabine treatment and formed extensive secondary metastatic nodules. Tissue microarray profiling and multiplexed IHC analysis of pancreatic cancer patient-derived primary tumors revealed EpCAM and ENT1 cell surface coexpression is favored, and ENT1 plasma membrane expression positively predicted median overall survival times in patients treated with adjuvant gemcitabine. Together, our findings identify ENT1 as an inadvertent target of EMT signaling mediated by cadherin switching and provide a mechanism by which mesenchymal pancreatic cancer cells evade gemcitabine therapy during EMT.

Video 2. Animation displays 3D reconstruction of PANC-1 cells grown in monolayer immunostained for ENT1 (red) and DAPI (blue)

Video 4. E+/N- cells animation displays 3D reconstruction of ENT1 (red) and DAPI (blue)

Video 5. PANC-1 cells stably overexpressing EpCAM are shown in this animation of a 3D reconstruction of compiled z-stack images. ENT1 (red), EpCAM (green), DAPI (blue).

Video 1. PANC-1 cells stably overexpressing E-cadherin are shown in this animation of a 3D reconstruction of compiled z-stack images. ENT1 (red), E-cadherin (green), DAPI (blue).

Highlights • We report a case of a 52-year-old male patient who presented with features of mass per rectum, which on first look appeared to be a full thickness prolapse of the rectum. • On careful examination, it turned out to be intussusception of colonic growth through anal canal. • Contrast Enhanced Computed Tomography showed features of colonic obstruction. • Sigmoidal growth intussuscepting through anal canal is extremely rare with only 9 cases being reported in Literature till date. • He underwent sigmoidectomy with Hartman’s procedure uneventfully. • A high index of suspicion is imperative to diagnose & treat such a case in timely manner to avoid lethal outcomes., Introduction – In adults, protrusion of intussuscepted sigmoid growth through the anal canal is exceedingly rare, with only 9 cases being reported till date. Case Report – A 52-year old man presented to emergency department with what appeared to be an episode of rectal prolapse following straining while defaecating. On examination, he had a prolapsed 8 × 8 cm bowel, with a 2 × 2 cm friable villous growth as the lead point, with space between the mass and the perianal skin. Computed Tomography of the abdomen was done which was suggestive of telescoping of the sigmoid into the rectum protruding out through the anal canal with features of intestinal obstruction. He underwent exploratory laparotomy with sigmoidectomy with Hartman’s Procedure. Post-operative period was uneventful. Histopathology was suggestive of moderately differentiated carcinoma. Discussion – In colo-anal intussusception, as was in our patient, the preferred approach is to reduce the intussusception before resection, to perform a sphincter saving operation as compared to an Abdominoperineal Resection (APR) otherwise. Conclusion -A high index of suspicion is important to diagnose and treat such cases early to avoid lethal outcomes by misdiagnosing it as simple rectal prolapse.

Mutations exclusively in equilibrative nucleoside transporter 3 (ENT3), the only intracellular nucleoside transporter within the solute carrier 29 (SLC29) gene family, cause an expanding spectrum of human genetic disorders (e.g., H syndrome, PHID syndrome, and SHML/RDD syndrome). Here, we identify adult stem cell deficits that drive ENT3-related abnormalities in mice. ENT3 deficiency alters hematopoietic and mesenchymal stem cell fates; the former leads to stem cell exhaustion, and the latter leads to breaches of mesodermal tissue integrity. The molecular pathogenesis stems from the loss of lysosomal adenosine transport, which impedes autophagy-regulated stem cell differentiation programs via misregulation of the AMPK-mTOR-ULK axis. Furthermore, mass spectrometry-based metabolomics and bioenergetics studies identify defects in fatty acid utilization, and alterations in mitochondrial bioenergetics can additionally propel stem cell deficits. Genetic, pharmacologic and stem cell interventions ameliorate ENT3-disease pathologies and extend the lifespan of ENT3-deficient mice. These findings delineate a primary pathogenic basis for the development of ENT3 spectrum disorders and offer critical mechanistic insights into treating human ENT3-related disorders., Mutations in equilibrative nucleoside transporter 3 (ENT3), encoded by SLC29A3, cause a spectrum of human genetic disorders. Here, the authors show altered haematopoietic stem cell and mesenchymal stem cell fates in ENT3-deficient mice, due to misregulation of the AMPK-mTOR-ULK axis.

Mutations in human equilibrative nucleoside transporter 3 (ENT3) encoded by SLC29A3 results in anemia and erythroid hypoplasia, suggesting that ENT3 may regulate erythropoiesis. Here, we demonstrate that lysosomal ENT3 transport of taurine-conjugated bile acids (TBA) facilitates TBA chemical chaperone function and alleviates endoplasmic reticulum (ER) stress in expanding mouse hematopoietic stem and progenitor cells (HSPCs). Slc29a3−/− HSPCs accumulate less TBA despite elevated levels of TBA in Slc29a3−/− mouse plasma and have elevated basal ER stress, reactive oxygen species (ROS), and radiation-induced apoptosis. Reintroduction of ENT3 allows for increased accumulation of TBA into HSPCs, which results in TBA-mediated alleviation of ER stress and erythroid apoptosis. Transplanting TBA-preconditioned HSPCs expressing ENT3 into Slc29a3−/− mice increase bone marrow repopulation capacity and erythroid pool size and prevent early mortalities. Together, these findings suggest a putative role for a facilitative lysosomal transporter in the bile acid regulation of ER stress in mouse HSPCs which may have implications in erythroid biology, the treatment of anemia observed in ENT3-mutated human genetic disorders, and nucleoside analog drug therapy., Mutations in ENT3, encoded by SLC29A3, result in anaemia and erythroid hypoplasia, suggesting roles in erythropoiesis. Here the authors show that ENT3 acts as a lysosomal bile acid transporter, and mutation compromises taurine conjugated bile acid transport in erythroid progenitors leading to ER stress, and anaemia.

Epithelial–mesenchymal transition (EMT) in cancer cells drives cancer chemoresistance, yet the molecular events of EMT that underpin the acquisition of chemoresistance are poorly understood. Here, we demonstrate a loss of gemcitabine chemosensitivity facilitated by human equilibrative nucleoside transporter 1 (ENT1) during EMT in pancreatic cancer and identify that cadherin switching from the epithelial (E) to neuronal (N) type, a hallmark of EMT, contributes to this loss. Our findings demonstrate that N-cadherin decreases ENT1 expression, membrane localization, and gemcitabine transport, while E-cadherin augments each of these. Besides E- and N-cadherin, another epithelial cell adhesion molecule, EpCAM, played a more prominent role in determining ENT1 membrane localization. Forced expression of EpCAM opposed cadherin switching with restored ENT1 expression, membrane localization, and gemcitabine transport in EMT-committed pancreatic cancer cells. In gemcitabine-treated mice, EpCAM-positive tumors had high ENT1 expression and reduced metastasis, whereas tumors with N-cadherin expression resisted gemcitabine treatment and formed extensive secondary metastatic nodules. Tissue microarray profiling and multiplexed IHC analysis of pancreatic cancer patient-derived primary tumors revealed EpCAM and ENT1 cell surface coexpression is favored, and ENT1 plasma membrane expression positively predicted median overall survival times in patients treated with adjuvant gemcitabine. Together, our findings identify ENT1 as an inadvertent target of EMT signaling mediated by cadherin switching and provide a mechanism by which mesenchymal pancreatic cancer cells evade gemcitabine therapy during EMT.

Combination antiretroviral drug treatments depend on 3'-deoxy-nucleoside analogs such as 3'-azido-3'-deoxythymidine (AZT) and 2'3'-dideoxyinosine (DDI). Despite being effective in inhibiting human immunodeficiency virus replication, these drugs produce a range of toxicities, including myopathy, pancreatitis, neuropathy, and lactic acidosis, that are generally considered as sequelae to mitochondrial damage. Although cell surface-localized nucleoside transporters, such as human equilibrative nucleoside transporter 2 (hENT2) and human concentrative nucleoside transporter 1 (hCNT1), are known to increase the carrier-mediated uptake of 3'-deoxy-nucleoside analogs into cells, another ubiquitously expressed intracellular nucleoside transporter (namely, hENT3) has been implicated in the mitochondrial transport of 3'-deoxy-nucleoside analogs. Using site-directed mutagenesis, generation of chimeric hENTs, and 3H-permeant flux measurements in mutant/chimeric RNA-injected Xenopus oocytes, here we identified the molecular determinants of hENT3 that dictate membrane translocation of 3'-deoxy-nucleoside analogs. Our findings demonstrated that whereas hENT1 had no significant transport activity toward 3'-deoxy-nucleoside analogs, hENT3 was capable of transporting 3'-deoxy-nucleoside analogs similar to hENT2. Transport analyses of hENT3-hENT1 chimeric constructs demonstrated that the N-terminal half of hENT3 is primarily responsible for the hENT3-3'-deoxy-nucleoside analog interaction. In addition, mutagenic studies identified that 225D and 231L in the N-terminal half of hENT3 partially contribute to the ability of hENT3 to transport AZT and DDI. The identification of the transporter segment and amino acid residues that are important in hENT3 transport of 3'-deoxy-nucleoside analogs may present a possible mechanism for overcoming the adverse toxicities associated with 3'-deoxy-nucleoside analog treatment and may guide rational development of novel nucleoside analogs.

Highlights • Castleman disease: heterogeneous group of hyperimmune lymphoproliferative disorders. • Unicentric type: localized disease; surgery is primary treatment; good prognosis. • Multicentric type: Serious systemic disease; 70% linked to HHV8; antiviral therapy. • Idiopathic Multicentric type: diagnosis by exclusion; Interleukin-6 blockade useful., Castleman Disease (CD) is a rare, heterogeneous group of hyperimmune lymphoproliferative disorders, not very familiar to surgeons. Unicentric Castleman Disease (UCCD) at one end of the spectrum is a localized disease, with little or no systemic symptoms. It may be an incidental radiological finding or detected while investigating for a symptomatic lymph node mass. Surgery is the primary treatment and has good long term prognosis. Multicentric Castleman Disease (MCCD) is a more serious systemic condition, often associated with constitutional symptoms. Exaggerated systemic inflammatory response secondary to “Cytokine storm” involving Interleukin-6 (IL-6) may cause multi-organ dysfunction. In addition, immunosuppression or malignant transformation can prove lethal. Human Herpes Simplex Virus 8 (HHV8) associated MCCD is a major subgroup occurring in immunocompromised individuals due to the viral trigger. Antiviral therapy is important in its treatment. Idiopathic MCCD (IMCCD) has no known biomarker and is diagnosed after excluding infective, autoimmune and malignant conditions of lymphoid tissue. IMCCD requires systemic therapy. We report a patient of UCCD who presented as a retroperitoneal mass in right iliac fossa causing pressure on femoral nerve. Following successful surgical excision she had good recovery. We report another patient who had large inguinal lymph node mass with constitutional symptoms. IMCCD was diagnosed after excision biopsy and comprehensive work up. Patient was started on corticosteroids followed by CD-20 targeted therapy. These two cases showcase the two ends of the clinical spectrum of CD requiring different management protocols. Awareness among surgeons and diligent work-up is imperative for early diagnosis and best outcome.

Epithelial-mesenchymal transition (EMT) in cancer cells drives cancer chemoresistance, yet the molecular events of EMT that underpin the acquisition of chemoresistance are poorly understood. Here, we demonstrate a significant loss of gemcitabine chemosensitivity facilitated by human equilibrative nucleoside transporter 1 (ENT1) during EMT in pancreatic cancer and identify that cadherin switching from the epithelial (E) to neuronal (N) type, a hallmark of EMT, contributes to this loss. Our findings demonstrate that N-cadherin decreases ENT1 expression, basolateral membrane localization and gemcitabine transport, while E-cadherin augments each of these. Besides E- and N-cadherin, another epithelial cell adhesion molecule, EpCAM, played a more prominent role in determining ENT1 membrane localization. Forced expression of EpCAM opposed cadherin switching with restored ENT1 expression, basolateral localization and gemcitabine transport in EMT-committed pancreatic cancer cells. In gemcitabine-treated mice, EpCAM positive tumors had high ENT1 expression and reduced metastasis, whereas tumors with N-cadherin expression resisted gemcitabine treatment and formed extensive secondary metastatic nodules. Tissue microarray profiling and multiplexed immunohistochemical analysis of pancreatic cancer patient-derived primary tumors revealed EpCAM and ENT1 cell surface co-expression is favored, and ENT1 plasma membrane expression positively predicted median overall survival times in patients treated with adjuvant gemcitabine. Together, our findings identify ENT1 as an inadvertent target of EMT signaling mediated by cadherin switching and provide a mechanism by which mesenchymal pancreatic cancer cells evade gemcitabine therapy during EMT. Citation Format: Brenna Weadick, Debasis Nayak, Avinash K. Persaud, Sau Wai Hung, Radhika Raj, Wei Chen, Junan Li, Terence M. Williams, Rajgopal Govindarajan. EMT-induced gemcitabine resistance in pancreatic cancer involves the functional loss of equilibrative nucleoside transporter 1 [abstract]. In: Proceedings of the AACR Virtual Special Conference on Pancreatic Cancer; 2020 Sep 29-30. Philadelphia (PA): AACR; Cancer Res 2020;80(22 Suppl):Abstract nr PO-062.