Functional Polymorphisms Associated with Disease-Free Survival in Resected Carcinoma of the Esophagus

Purpose  

The aim of this study was to determine whether clinical outcome after surgical resection of esophageal adenocarcinoma (EAC) or esophageal squamous cell carcinoma (ESCC) could be predicted by functional polymorphisms in different proto-oncogenes and tumor suppressor genes.     

Mapping of homozygous deletions in verified esophageal adenocarcinoma cell lines and xenografts

Human esophageal adenocarcinoma (EAC) cell lines and xenografts are powerful tools in the search for genetic alterations because these models are composed of pure human cancer cell populations without admixture of normal human cells. In particular detection of homozygous deletions (HDs) is easier using these pure populations of cancer cells. Identification of HDs could potentially lead to the subsequent identification of new tumor suppressor genes (TSGs) involved in esophageal adenocarcinogenesis. Genome wide single nucleotide polymorphism (SNP) arrays were used to identify HDs in 10 verified EAC cell lines and nine EAC xenografts. In total, 61 HDs (range 1-6 per sample) were detected and confirmed by polymerase chain reaction. Besides HDs observed in common fragile genomic regions (n = 26), and gene deserts (n = 8), 27 HDs were located in gene-containing regions. HDs were noted for known TSGs, including CDKN2A, SMAD4 and CDH3/CDH1. Twenty-two new chromosomal regions were detected harboring potentially new TSGs involved in EAC carcinogenesis. Two of these regions of homozygous loss, encompassing the ITGAV and RUNX1 gene, were detected in multiple samples indicating a potential role in the carcinogenesis of EAC. To exclude culturing artifacts, these last two deletions were confirmed by fluorescent in situ hybridization in the primary tumors of which the involved cell lines and xenografts were derived. In summary, in this report we describe the identification of HDs in a series of verified EAC cell lines and xenografts. The deletions documented here are a step forward identifying the key genes involved in EAC development.     

A common variant in ERBB4 regulates GABA concentrations in human cerebrospinal fluid

The neuregulin 1 (NRG1) receptor ErbB4 is involved in the development of cortical inhibitory GABAergic circuits and NRG1-ErbB4 signaling has been implicated in schizophrenia (SCZ). A magnetic resonance spectroscopy ((1)H-MRS) study has demonstrated that a single-nucleotide polymorphism in ERBB4, rs7598440, influences human cortical GABA concentrations. Other work has highlighted the significant impact of this genetic variant on expression of ERBB4 in the hippocampus and dorsolateral prefrontal cortex in human post mortem tissue. Our aim was to examine the association of rs7598440 with cerebrospinal fluid (CSF) GABA levels in healthy volunteers (n=155). We detected a significant dose-dependent association of the rs7598440 genotype with CSF GABA levels (G-allele standardized β=-0.23; 95% CIs: -0.39 to -0.07; P=0.0066). GABA concentrations were highest in A homozygous, intermediate in heterozygous, and lowest in G homozygous subjects. When excluding subjects on psychotropic medication (three subjects using antidepressants), the results did not change (G-allele standardized β=-0.23; 95% CIs: -0.40 to -0.07; P=0.0051). The explained variance in CSF GABA by rs7598440 in our model is 5.2% (P=0.004). The directionality of our findings agrees with the aforementioned (1)H-MRS and gene expression studies. Our observation therefore strengthens the evidence that the A-allele of rs7598440 in ERBB4 is associated with increased GABA concentrations in the human central nervous system (CNS). To our knowledge, our finding constitutes the first confirmation that CSF can be used to study genotype-phenotype correlations of GABA levels in the CNS. Such quantitative genetic analyses may be extrapolated to other CSF constituents relevant to SCZ in future studies.     

Brain accumulation of sunitinib is restricted by P-glycoprotein (ABCB1) and breast cancer resistance protein (ABCG2) and can be enhanced by oral elacridar and sunitinib coadministration

Sunitinib is an orally active, multitargeted tyrosine kinase inhibitor which has been used for the treatment of metastatic renal cell carcinoma and imatinib-resistant gastrointestinal stromal tumors. We aimed to investigate the in vivo roles of the ATP-binding cassette drug efflux transporters ABCB1 and ABCG2 in plasma pharmacokinetics and brain accumulation of oral sunitinib, and the feasibility of improving sunitinib kinetics using oral coadministration of the dual ABCB1/ABCG2 inhibitor elacridar. We used in vitro transport assays and Abcb1a/1b(-/-) , Abcg2(-/-) and Abcb1a/1b/Abcg2(-/-) mice to study the roles of ABCB1 and ABCG2 in sunitinib disposition. In vitro, sunitinib was a good substrate of murine (mu)ABCG2 and a moderate substrate of human (hu)ABCB1 and huABCG2. In vivo, the systemic exposure of sunitinib after oral dosing (10 mg kg(-1) ) was unchanged when muABCB1 and/or muABCG2 were absent. Brain accumulation of sunitinib was markedly (23-fold) increased in Abcb1a/b/Abcg2(-/-) mice, but only slightly (2.3-fold) in Abcb1a/b(-/-) mice, and not in Abcg2(-/-) mice. Importantly, a clinically realistic coadministration of oral elacridar and oral sunitinib to wild-type mice resulted in markedly increased sunitinib brain accumulation, equaling levels in Abcb1a/1b/Abcg2(-/-) mice. This indicates complete inhibition of the blood-brain barrier (BBB) transporters. High-dose intravenous sunitinib could saturate BBB muABCG2, but not muABCB1A, illustrating a dose-dependent relative impact of the BBB transporters. Brain accumulation of sunitinib is effectively restricted by both muABCB1 and muABCG2 activity. Complete inhibition of both transporters, leading to markedly increased brain accumulation of sunitinib, is feasible and safe with a clinically realistic oral elacridar/sunitinib coadministration.     

The C-type lectin receptor CLEC9A mediates antigen uptake and (cross-)presentation by human blood BDCA3+ myeloid dendritic cells

CLEC9A is a recently discovered C-type lectin receptor involved in sensing necrotic cells. In humans, this receptor is selectively expressed by BDCA3(+) myeloid dendritic cells (mDCs), which have been proposed to be the main human cross-presenting mDCs and may represent the human homologue of murine CD8(+) DCs. In mice, it was demonstrated that antigens delivered with antibodies to CLEC9A are presented by CD8(+) DCs to both CD4(+) and CD8(+) T cells and induce antitumor immunity in a melanoma model. Here we assessed the ability of CLEC9A to mediate antigen presentation by human BDCA3(+) mDCs, which represent < 0.05% of peripheral blood leukocytes. We demonstrate that CLEC9A is only expressed on immature BDCA3(+) mDCs and that cell surface expression is lost after TLR-mediated maturation. CLEC9A triggering via antibody binding rapidly induces receptor internalization but does not affect TLR-induced cytokine production or expression of costimulatory molecules. More importantly, antigens delivered via CLEC9A antibodies to BDCA3(+) mDCs are presented by both MHC class I (cross-presentation) and MHC class II to antigen-specific T cells. We conclude that CLEC9A is a promising target for in vivo antigen delivery in humans to increase the efficiency of vaccines against infectious or malignant diseases.