Disruption of a novel ectodermal neural cortex 1 antisense gene, ENC-1AS and identification of ENC-1 overexpression in hairy cell leukemia.
Karyotypical alteration of chromosome 5 and in particular band 5q13 is a frequent finding in hairy cell leukemia (HCL). We have previously identified a number of candidate genes localized in close proximity to a constitutional inv(5)(p13.1q13.3) breakpoint in one HCL patient. These included beta-hexosaminodase HEXB, frequently mutated in the lysosomal storage disorder Sandhoff disease. We now report that the 5q13.3 breakpoint disrupts a novel evolutionary conserved alternative isoform of HEXB. This isoform directly overlaps, in a cis-antisense fashion, exon 1 of the gene for ectodermal neuronal cortex 1 ENC-1, and was thus named ENC-1AS. ENC-1 has previously been shown to be overexpressed in several malignancies, and is believed to play a critical regulatory role in malignant transformation of various tumors. Importantly, subsequent analysis of ENC-1 in purified primary HCL tumor cells revealed a striking upregulation of ENC-1 in all 26 patients examined, compared with normal peripheral blood lymphocytes from healthy donors. Upon further analysis of the ENC-1/ENC-1AS locus, we identified a complex 5' regulatory mechanism involving an inverse expression of the ENC-1 sense and the ENC-1AS transcripts in several tissues supporting the hypothesis that expression of ENC-1AS regulates ENC-1 levels. In addition, we have also found tissue-specific methylation of a 1.2 kb segment encompassing the overlapping ENC-1/ENC-1AS 5' exons, adding to the complexity of the regulation of this locus. Altogether, these results suggest that upregulation of ENC-1 contributes to the development of HCL and provides new information on the possible dysregulation of ENC-1 including expression of a novel antisense gene, ENC-1AS.
Department of Oncology/Pathology, CCK, Karolinska Hopsital and Institute, Stockholm, Sweden.
Marianne
M
Hammarsund
Mikael
M
Lerner
Chaoyong
C
Zhu
Mats
M
Merup
Monika
M
Jansson
Gösta
G
Gahrton
Hanneke
H
Kluin-Nelemans
Stefan
S
Einhorn
Dan
D
Grandér
Olle
O
Sangfelt
Martin
M
Corcoran
D001483:Base Sequence; D015152:Blotting, Northern; D015139:Blotting, Southern; D002895:Chromosomes, Human, Pair 5; D017931:DNA Primers; D054819:Hexosaminidase B; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D007943:Leukemia, Hairy Cell / Q000201:enzymology / Q000235:genetics*; D008840:Microfilament Proteins / Q000235:genetics*; D009479:Neuropeptides / Q000235:genetics*; D009687:Nuclear Proteins / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D001619:beta-N-Acetylhexosaminidases / Q000235:genetics
D017931:DNA Primers; D008840:Microfilament Proteins; D009479:Neuropeptides; D009687:Nuclear Proteins; C112302:ectodermal-neural cortex 1 protein; D054819:Hexosaminidase B; D001619:beta-N-Acetylhexosaminidases