Pancreatic Adenocarcinoma Therapeutic Targets Revealed by Tumor-Stroma Cross-Talk Analyses in Patient-Derived Xenografts.
ABSTRACT: Preclinical models based on patient-derived xenografts have remarkable specificity in distinguishing transformed human tumor cells from non-transformed murine stromal cells computationally. We obtained 29 pancreatic ductal adenocarcinoma (PDAC) xenografts from either resectable or non-resectable patients (surgery and endoscopic ultrasound-guided fine-needle aspirate, respectively). Extensive multiomic profiling revealed two subtypes with distinct clinical outcomes. These subtypes uncovered specific alterations in DNA methylation and transcription as well as in signaling pathways involved in tumor-stromal cross-talk. The analysis of these pathways indicates therapeutic opportunities for targeting both compartments and their interactions. In particular, we show that inhibiting NPC1L1 with Ezetimibe, a clinically available drug, might be an efficient approach for treating pancreatic cancers. These findings uncover the complex and diverse interplay between PDAC tumors and the stroma and demonstrate the pivotal role of xenografts for drug discovery and relevance to PDAC.
Project description:We generated novel patient derived xenograft (PDX) and cell line -derived xenograft models for pancreatic ductal adenocarcinoma (PDAC) which reflect different molecular subtypes. Pancreatic ductal adenocarcinoma is currently the tumor with the fourth highest mortality rate. Recently, subtypes of PDAC have been reported by Collisson et al (Nat. Med. 17(4) 2011. DOI: 10.1038/nm.2344). However current fetal calf serum (FCS) cultured cell lines do not accurately model these subtypes. We thus generated novel serum-free cell lines derived from primary patient xenografts. We here analyse the gene-expression profiles of the xenografts and the derived cell lines. We show that indeed three different subtypes can be separated in our models based on gene-expression data. Further, we identify upregulation of a drug-detoxification pathway specifically in xenografts and cell lines of one of the subtypes. These models and data will help to better understand inter-patient heterogeneity in PDAC and identify novel drug targets and diagnostic markers.
Project description:As a main component of the tumor microenvironment, the stroma is critical in development, progression, and metastasis of pancreatic ductal adenocarcinoma (PDAC). The genomic status and its relationship of neoplastic and stromal components remain unclear in PDAC. We performed targeted sequencing for 1,021 cancer-suspected genes on parallel microdissected stromal and neoplastic components from 50 operable PDAC patients. Clonality analysis of mutations was conducted to reconstruct the evolutionary trajectory, and then molecular subtypes were established. Multi-lineage differentiation potential and mesenchymal transformation of KRAS-mutant cell line Panc1 were evaluated using RT-PCR and immunofluorescence staining. In this study, 39 (78.0%) were genomically altered in stroma, with KRAS (71.8%), TP53 (61.5%), and CDKN2A (23.1%) as the most commonly mutated genes. The majority of stromal mutations (89.8%) were detected in matched neoplastic components. Patients with KRAS/TP53-mut stroma demonstrated a higher tumor cell fraction (TCF) than did those with wild-type (WT) stroma (p = 0.0371, p = 0.0014). In both components, mutants KRAS and TP53 often occurred as clonal events, and the allele frequencies presented linear correlation in the same specimen. All neoplasm-like stroma (characterized with all or initial neoplastic clones and driver events in stroma) harbored KRAS or TP53 mutations. Neoplasm-like and KRAS-mutant stroma was associated with shorter disease-free survival. It is a new finding for the existence of driver gene mutations in PDAC stroma. These data suggest that genomic features of stromal components may serve as prognostic biomarkers in resectable PDAC and might help to guide a more precise treatment paradigm in therapeutic options.
Project description:Ezetimibe is a potent inhibitor of cholesterol absorption that has been approved for the treatment of hypercholesterolemia, but its molecular target has been elusive. Using a genetic approach, we recently identified Niemann-Pick C1-Like 1 (NPC1L1) as a critical mediator of cholesterol absorption and an essential component of the ezetimibe-sensitive pathway. To determine whether NPC1L1 is the direct molecular target of ezetimibe, we have developed a binding assay and shown that labeled ezetimibe glucuronide binds specifically to a single site in brush border membranes and to human embryonic kidney 293 cells expressing NPC1L1. Moreover, the binding affinities of ezetimibe and several key analogs to recombinant NPC1L1 are virtually identical to those observed for native enterocyte membranes. KD values of ezetimibe glucuronide for mouse, rat, rhesus monkey, and human NPC1L1 are 12,000, 540, 40, and 220 nM, respectively. Last, ezetimibe no longer binds to membranes from NPC1L1 knockout mice. These results unequivocally establish NPC1L1 as the direct target of ezetimibe and should facilitate efforts to identify the molecular mechanism of cholesterol transport.
Project description:Pancreatic ductal adenocarcinoma (PDAC) has dismal 5-year survival (<9%). We hypothesize that exposure of tumors to conventional therapies may preferentially modulate immune biomarkers in the tumor microenvironment in PDAC. PDAC patients who underwent upfront surgical resection or who received neoadjuvant FOLFIRINOX with or without neoadjuvant radiotherapy followed by surgical resection were selected for study. Total expression of immunologically relevant transcripts and spatially resolved expression of immunologically relevant proteins was quantitated using multiplexed methods (NanoString nCounter and GeoMX platforms). This analysis identified numerous differentially expressed transcripts associated with the type of neoadjuvant therapy received. Moreover, we identified significant alterations in the expression and/or spatial distribution of immunologically relevant proteins in different regions (tumor cell rich, immune cell rich, stromal cell rich) of the tumor microenvironment. These data provide insight into the immunological effects of clinically relevant neoadjuvant therapy for resectable/borderline-resectable PDAC by describing significant differences in the expression of key immunologic biomarkers within the PDAC microenvironment that were associated with the type of treatment patients received prior to surgical resection. This represents a comprehensive analysis of numerous biomarkers conducted on the PDAC microenvironment. This work may guide strategic new combination therapies for pancreatic cancer.
Project description:Recently, increasing evidence has indicated that the presence of tumor infiltrating immune cells has shown predictive significance for many solid tumors. Present study was performed to evaluate the predictive value of stromal tumor-infiltrating lymphocytes (TILs) for the presence of liver metastasis and overall survival in PDAC (pancreatic ductal adenocarcinoma) patients after complete resection and to explore the potential role of lymphocytes in PDAC. A total of 155 resectable patients with PDAC were enrolled in our study. Stromal TIL density was investigated in hematoxylin and eosin-stained sections of surgical specimens and scored. The effect and possible mechanism of lymphocytes on cancer cells was evaluated using co-culture techniques and ELISA test. Stromal TIL negative status (HR = 2.80, 95% CI 1.75-4.48, P < 0.01) was not only an independent predictor of worse OS (HR = 2.7, 95% CI 1.80-4.06, P = <0.01) but also a significant independent predictor of liver metastasis. Higher CEA (P = 0.01) or CA19-9 (P = 0.01) levels were associated with low stromal TIL density. Stromal TIL negative patients appeared to develop tumors with a higher CEA (P = 0.01), larger diameter (P = 0.05) and advanced stage (P = 0.02). The co-culture experiment suggests that lymphocytes can inhibit pancreatic cancer cell proliferation. Further ELISA and cell culture test indicate that lymphocytes may cause pancreatic cancer cells apoptosis through TNF-alpha secretion. Our data suggest a potential favorable role of stromal TILs in predicting liver metastasis and overall survival of patients with PDAC after complete resection. Lymphocytes may inhibit the growth of PDAC through TNF-alpha secretion, which suggest a potential therapeutic approach against PDAC.
Project description:Niemann-Pick C1-like 1 (NPC1L1) is required for cholesterol absorption. Intestinal NPC1L1 appears to be a target of ezetimibe, a cholesterol absorption inhibitor that effectively lowers plasma LDL-cholesterol in humans. However, human liver also expresses NPC1L1. Hepatic function of NPC1L1 was previously unknown, but we recently discovered that NPC1L1 localizes to the canalicular membrane of primate hepatocytes and that NPC1L1 facilitates cholesterol uptake in hepatoma cells. Based upon these findings, we hypothesized that hepatic NPC1L1 allows the retention of biliary cholesterol by hepatocytes and that ezetimibe disrupts hepatic function of NPC1L1. To test this hypothesis, transgenic mice expressing human NPC1L1 in hepatocytes (L1-Tg mice) were created. Hepatic overexpression of NPC1L1 resulted in a 10- to 20-fold decrease in biliary cholesterol concentration, but not phospholipid and bile acid concentrations. This decrease was associated with a 30%-60% increase in plasma cholesterol, mainly because of the accumulation of apoE-rich HDL. Biliary and plasma cholesterol concentrations in these animals were virtually returned to normal with ezetimibe treatment. These findings suggest that in humans, ezetimibe may reduce plasma cholesterol by inhibiting NPC1L1 function in both intestine and liver, and hepatic NPC1L1 may have evolved to protect the body from excessive biliary loss of cholesterol.
Project description:Despite the uniform mortality in pancreatic adenocarcinoma (PDAC), clinical disease heterogeneity exists with limited genomic differences. A highly aggressive tumor subtype termed basal-like was identified to show worse outcomes and higher inflammatory responses. Here, we focus on the microbial effect in PDAC progression and present a comprehensive analysis of the tumor microbiome in different PDAC subtypes. Tumors from 62 resectable PDAC patients were subjected to metagenomic sequencing and RNA-seq. Overall design: Analysis of the landscape of gene expression in pancreatic adenocarcinoma. Data include 62 primary PDAC tumors.
Project description:Hypercholesterolemia is one of the key risk factors for coronary heart disease, a major cause of death in developed countries. Suppression of NPC1L1-mediated dietary and biliary cholesterol absorption is predicted to be one of the most effective ways to reduce the risk of hypercholesterolemia. In a screen for natural products that inhibit ezetimibe glucuronide binding to NPC1L1, we found a novel compound, fomiroid A, in extracts of the mushroom Fomitopsis nigra. Fomiroid A is a lanosterone derivative with molecular formula C30H48O3. Fomiroid A inhibited ezetimibe glucuronide binding to NPC1L1, and dose-dependently prevented NPC1L1-mediated cholesterol uptake and formation of esterified cholesterol in NPC1L1-expressing Caco2 cells. Fomiroid A exhibited a pharmacological chaperone activity that corrected trafficking defects of the L1072T/L1168I mutant of NPC1L1. Because ezetimibe does not have such an activity, the binding site and mode of action of fomiroid A are likely to be distinct from those of ezetimibe.
Project description:Background Pancreatic ductal adenocarcinoma (PDAC) is one of the most fatal malignancies worldwide. The JAK/STAT signaling pathway is involved in pancreatic cancer tumorigenesis. However, the prognostic value of JAK2 expression in resectable PDAC is unclear. Method In this study, we performed a clinicopathological analysis of 62 resectable PDAC cases with a primary focus on survival. JAK2 expression was examined by immunohistochemistry. The relationship between JAK2 expression and clinicopathological features and prognosis was analyzed. Results Survival curve analyses revealed that high levels of JAK2 expression predict a poor prognosis in resectable PDAC patients. Multivariate analysis confirmed that JAK2 expression can predict the prognosis of PDAC. Conclusions Assessment of JAK2 protein expression may be a promising method to predict prognosis in patients with resectable PDAC.
Project description:The intestinal absorption of cholesterol is mediated by a multipass membrane protein, Niemann-Pick C1-Like 1 (NPC1L1), the molecular target of a cholesterol lowering therapy ezetimibe. While ezetimibe gained Food and Drug Administration approval in 2002, its mechanism of action has remained unclear. Here, we present two cryo-electron microscopy structures of NPC1L1, one in its apo form and the other complexed with ezetimibe. The apo form represents an open state in which the N-terminal domain (NTD) interacts loosely with the rest of NPC1L1, leaving the NTD central cavity accessible for cholesterol loading. The ezetimibe-bound form signifies a closed state in which the NTD rotates ~60°, creating a continuous tunnel enabling cholesterol movement into the plasma membrane. Ezetimibe blocks cholesterol transport by occluding the tunnel instead of competing with cholesterol binding. These findings provide insight into the molecular mechanisms of NPC1L1-mediated cholesterol transport and ezetimibe inhibition, paving the way for more effective therapeutic development.