Methylation status of the 3rd exon of the c-MYC oncogene in B-cell malignancies

We examined the methylation status of the third exon of the MYC oncogene in 39 patients with B-cell malignancies. DNA was digested with MspI plus EcoR I or HpaII plus EcoRI and hybridised with a probe specific for the third ex on of MYC. Thirty four patients showed complete methylation of the CCGG sit e. Four patients, one with chronic B-cell, leukaemia and one with pro-lymph ocytic leukaemia (PLL) and two with B-cell lymphoma showed partial hypometh ylation of the CCGG site, while another patient with PLL showed complete hy pomethylation of the CCGG site. These results suggest that hypomethylation of the MYC oncogene is infrequent in B-cell tumours but may be involved in the development of some cases of B-cell malignancies. (C) 1999 Elsevier Sci ence Ltd. All rights reserved.