Expression of the myc-family proto-oncogenes and related genes max and mad in synovial tissue

Objective. To examine the expression of myc proto-oncogenes; c-myc, L-myc, and N-myc, and their related genes max and mad, in the arthritic synovium. Methods. Using reverse transcription-polymerase chain reaction (RT-PCR), Northern and Southern hybridizations, the expression of these genes in the synovial tissue from rheumatoid arthritis (RA) and osteoarthritis (OA) was analyzed. Synovial specimens from cadavers without any joint disease and peripheral blood mononuclear cells (PBMC) from healthy individuals served as controls. Results. As a novel finding, synovial cells were observed to express L-myc, N-myc as well as their related genes max and mad, in addition to the previously described presence of c-myc proto-oncogene in synovium. c-myc, L-myc, N-myc, and mad were expressed in all patient samples studied, including the controls. Instead, max was detected in only 10/12 of RA patients, in 11/13 of OA patients, and in all controls (4/4 cadavers, 5/5 blood donors). Six patients with RA revealed positive s...