Complex regulation of acetylcholinesterase gene expression in human brain tumors

Abstract

To study the regulation of acetylcholinesterase (AChE) gene expression in human brain tumors, 3' splice variants of AChE mRNA and potentially relevant transcription factor mRNAs were labeled in primary astrocytomas and melanomas. AChE-S and AChE-R mRNA, as well as Runx1/AML1 mRNA accumulated in astrocytomas in correlation with tumor aggressiveness, but neither HNF3b nor c-fos mRNA was observed in melanoma and astrocytomas. Immunohistochemistry demonstrated nuclear Runx1/AML1 and cellular AChE-S and AChE-R in melanomas, however, only AChE-S, and not the secreted AChE-R variant, was retained in astrocyte tumor cells. Runx1/AML1 revealed weak linkage with ACHE promoter sequences, yet enhanced ACHE gene expression in co-transfected COS1 cells. The p300 coactivator and the ACHE promoter's distal enhancer facilitated this effect, which was independent of much of the Runx1/AML1 trans-activation domain. Surprisingly, GASP, a fusion product of green fluorescence protein (GFP) and ASP 67 , a peptide composed of the 67 Cterminal amino acid residues of AChE-S, localized to COS1 cell nuclei. However, GARP, the corresponding fusion product of GFP with a peptide having the 51 Cterminal residues of AChE-E or GFP alone, remained cytoplasmic. Runx1/AML1 exhibited improved nuclear retention in GASP-expressing COS1 cells, suggesting modulated nuclear localization processes. Together, these findings reveal brain tumor-specific regulation of both expression and cellular retention of variant ACHE gene products.

Regulation of TGFβ1-mediated growth inhibition and apoptosis by RUNX2 isoforms in endothelial cells

“…Conversely, VEGF, along with several angiogenic factors including FGF-1 and insulin-like growth factor-1 (IGF-1), stimulate RUNX2 expression and migration of EC in vitro and in vivo (Namba et al, 2000;Sun et al, 2001). Reports of RUNX1 expression in human vascular EC and brain tumor cells in vivo also indicate that Runx genes are upregulated in highly vascularized malignant tumors (Perry et al, 2002).…”

Differential localization of acetylcholinesterase in neuronal and non‐neuronal cells

“…Most isoforms are found in the central and peripheral nervous systems [Taylor and Radic, 1994;Soreq and Seidman, 2001]. Isoforms have also been characterized in hematopoietic cells, as well as in tumor cells [Karpel et al, 1994;Nechushtan et al, 1996;Perry et al, 2002]. The different isoforms have been shown by reverse-transcriptase polymerase chain reaction (RT-PCR) to result from alternative splicing of AChE mRNA leading to isoforms of AChE protein differing in their 3′ exon composition [Karpel et al, 1994;Perry et al, 2002].…”

“…Isoforms have also been characterized in hematopoietic cells, as well as in tumor cells [Karpel et al, 1994;Nechushtan et al, 1996;Perry et al, 2002]. The different isoforms have been shown by reverse-transcriptase polymerase chain reaction (RT-PCR) to result from alternative splicing of AChE mRNA leading to isoforms of AChE protein differing in their 3′ exon composition [Karpel et al, 1994;Perry et al, 2002]. Although long thought that the transcriptional processing of AChE is complex and cell-regulated, additional isoforms continue to be demonstrated [Meshorer et al, 2004].…”

Acetylcholinesterase/C terminal binding protein interactions modify Ikaros functions, causing T lymphopenia

“…13 In situ hybridization and intracellular localization of AChE-S mRNA were performed as detailed. 9,18 AChE catalytic activity was determined as detailed. 11 Cell cultures K562 and human embryonic kidney (HEK) 293 cells were grown in RPMI and Dulbecco's modified Eagle's medium (DMEM, Biological Industries, Beit Ha'emek, Israel; Sigma, Jerusalem, Israel), both supplemented with 10% fetal calf serum (FCS) and 2 mM L-glutamine (Biological Industries) at 371C, in a humidified chamber with 5% CO 2 .…”