Inactivation of the lamin A/C gene by CpG island promoter hypermethylation in hematologic malignancies, and its association with poor survival in nodal diffuse large B-cell lymphoma.
OBJECTIVE
Lamins support the nuclear envelope and provide anchorage sites for chromatin, but they are also involved in DNA synthesis, transcription, and apoptosis. Although the lack of expression of A-type lamins in lymphoma and leukemia has been reported, the mechanism was unknown. We investigated the possible role of CpG island hypermethylation in lamin A/C silencing and its prognostic relevance.


METHODS
The promoter CpG island methylation status of the lamin A/C gene, encoding the A-type lamins, was analyzed by bisulfite genomic sequencing and methylation-specific polymerase chain reaction in human cancer cell lines (n = 74; from 17 tumor types), and primary leukemias (n = 60) and lymphomas (n = 80). Lamin A/C expression was determined by reverse-transcription polymerase chain reaction, Western blot, immunohistochemistry, and immunofluorescence.


RESULTS
seven (50%) of 14 leukemia- and five (42%) of 13 lymphoma cell lines. The presence of hypermethylation was associated with the loss of gene expression while a demethylating agent restored expression. In primary malignancies, lamin A/C hypermethylation was present in 18% (nine of 50) of acute lymphoblastic leukemias and 34% (14 of 41) of nodal diffuse large B-cell lymphomas. The presence of lamin A/C hypermethylation in nodal diffuse large B-cell lymphomas correlated strongly with a decrease in failure-free survival (Kaplan-Meier, P = .0001) and overall survival (Kaplan-Meier, P = .0005).


CONCLUSIONS
Epigenetic silencing of the lamin A/C gene by CpG island promoter hypermethylation is responsible for the loss of expression of A-type lamins in leukemias and lymphomas. The finding that lamin A/C hypermethylation is associated with poor outcome in diffuse large B-cell lymphomas suggests important clinical implications.
Agrelo
Ruben
R
Cancer Epigenetics and Lymphoma Laboratories, Molecular Pathology Program, Spanish National Cancer Centre, Madrid, Spain.
Setien
Fernando
F
Espada
Jesus
J
Artiga
Maria Jesus
MJ
Rodriguez
Maria
M
Pérez-Rosado
Alberto
A
Sanchez-Aguilera
Abel
A
Fraga
Mario F
MF
Piris
Miguel Angel
MA
Esteller
Manel
M
D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology; D001374:Azacitidine / Q000494:pharmacology; D018899:CpG Islands; D019175:DNA Methylation; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D006801:Humans; D034904:Lamin Type A / Q000235:genetics*; D008198:Lymph Nodes / Q000473:pathology; D016393:Lymphoma, B-Cell / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D016403:Lymphoma, Large B-Cell, Diffuse / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D011379:Prognosis; D011401:Promoter Regions, Genetic / Q000235:genetics; D015996:Survival Rate; D014407:Tumor Cells, Cultured
D000964:Antimetabolites, Antineoplastic; D034904:Lamin Type A; C440308:lamin C; D001374:Azacitidine