Silencing of TESTIN by dense biallelic promoter methylation is the most common molecular event in childhood acute lymphoblastic leukaemia.
BACKGROUND
Aberrant promoter DNA methylation has been reported in childhood acute lymphoblastic leukaemia (ALL) and has the potential to contribute to its onset and outcome. However, few reports demonstrate consistent, prevalent and dense promoter methylation, associated with tumour-specific gene silencing. By screening candidate genes, we have detected frequent and dense methylation of the TESTIN (TES) promoter.


RESULTS
Bisulfite sequencing showed that 100% of the ALL samples (n = 20) were methylated at the TES promoter, whereas the matched remission (n = 5), normal bone marrow (n = 6) and normal PBL (n = 5) samples were unmethylated. Expression of TES in hyperdiploid, TEL-AML+, BCR-ABL+, and E2A-PBX+ subtypes of B lineage ALL was markedly reduced compared to that in normal bone marrow progenitor cells and in B cells. In addition TES methylation and silencing was demonstrated in nine out of ten independent B ALL propagated as xenografts in NOD/SCID mice.


CONCLUSIONS
In total, 93% of B ALL samples (93 of 100) demonstrated methylation with silencing or reduced expression of the TES gene. Thus, TES is the most frequently methylated and silenced gene yet reported in ALL. TES, a LIM domain-containing tumour suppressor gene and component of the focal adhesion complex, is involved in adhesion, motility, cell-to-cell interactions and cell signalling. Our data implicate TES methylation in ALL and provide additional evidence for the involvement of LIM domain proteins in leukaemogenesis.
Weeks
Robert J
RJ
Cancer Genetics Laboratory, Department of Biochemistry, University of Otago, PO Box 56, Dunedin 9054, New Zealand. rob.weeks@otago.ac.nz
Kees
Ursula R
UR
Song
Sarah
S
Morison
Ian M
IM
D000483:Alleles; D000818:Animals; D045744:Cell Line, Tumor; D003598:Cytoskeletal Proteins; D019175:DNA Methylation; D020868:Gene Silencing; D018398:Homeodomain Proteins / Q000235:genetics*; D006801:Humans; D060588:LIM Domain Proteins; D019656:Loss of Heterozygosity; D051379:Mice; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000235:genetics* / Q000473:pathology; D011401:Promoter Regions, Genetic; D016601:RNA-Binding Proteins; D014183:Transplantation, Heterologous; D025521:Tumor Suppressor Proteins / Q000235:genetics*
D003598:Cytoskeletal Proteins; D018398:Homeodomain Proteins; D060588:LIM Domain Proteins; D016601:RNA-Binding Proteins; C429688:TES protein, human; D025521:Tumor Suppressor Proteins