Frequent methylation of p16INK4A/p14ARF promoters in tumorigenesis of Epstein-Barr virus transformed lymphoblastoid cell lines.
BACKGROUND
The data that the p16INK4A gene is frequently inactivated in Burkitt lymphoma (BL) and that this event often accompanies the inactivation of p14ARF in several tumours prompted us to examine the genetic and methylation status of both genes in BL and B-lymphoblastoid cell lines (LCLs).


METHODS
The existence of gene deletion, mutation and promoter methylation was investigated by single-strand conformational polymorphism, direct sequencing and methylation-specific PCR (MSP) analysis, respectively.


RESULTS
Sequencing of each exon of both tumour suppressor genes revealed p16INK4A mutation only in 3 out of 11 BL, but 1 of them also affected the p14ARF gene. MSP analysis of promoters showed p16INK4A to be methylated and p14ARF not to be methylated in each Epstein-Barr virus-positive BL cell line. Primary B-cells and de novo established LCLs had no genetic changes or methylated promoter of either gene. LCLs achieving the stage of immortalization usually showed methylation of both p16INK4A and p14ARF promoters.


CONCLUSIONS
Our results suggest that, in contrast to p161NK4A, inactivation of p14ARF by either genetic change or promoter methylation has no importance in the development of BL cell lines, while its methylation has a central role in the immortalization of LCLs.
Nagy
Etelka
E
Institute of Medical Microbiology, Medical and Health Science Center, University of Debrecen, Nagyerdei krt. 98, H-4012 Debrecen, Hungary.
Veress
György
G
Szarka
Krisztina
K
Csoma
Eszter
E
Beck
Zoltán
Z
D001402:B-Lymphocytes / Q000502:physiology* / Q000821:virology; D002051:Burkitt Lymphoma / Q000235:genetics* / Q000821:virology*; D002461:Cell Line, Transformed; D045744:Cell Line, Tumor; D002472:Cell Transformation, Viral / Q000235:genetics*; D019941:Cyclin-Dependent Kinase Inhibitor p16 / Q000235:genetics*; D019175:DNA Methylation; D017353:Gene Deletion; D020868:Gene Silencing; D004854:Herpesvirus 4, Human / Q000502:physiology*; D006801:Humans; D016133:Polymerase Chain Reaction; D018807:Polymorphism, Single-Stranded Conformational; D011401:Promoter Regions, Genetic; D025803:Tumor Suppressor Protein p14ARF / Q000235:genetics*
D019941:Cyclin-Dependent Kinase Inhibitor p16; D025803:Tumor Suppressor Protein p14ARF