Recent Progress on the Human bcl-2 Gene Involved in Follicular Lymphoma: Characterization of the Protein Products

Chromosome translocations involving the immunoglobulin heavy chain gene are common in B cell malignancies (Yunis 1983). The t(14;18) translocation has been extensively studied by us and others for the last several years because this translocation is nearly always associated with follicular lymphoma, one of the most common human B cell malignancies (Fukuhara et al. 1979; Yunis et al. 1982). By molecular cloning of the breakpoint of the t(14;18) translocation, we and others identified a gene, bcl-2, at the breakpoint region (Tsujimoto et al. 1985a; Bakshi et al. 1985; Cleary and Sklar 1985). Since the t(14;18) translocation occurs within or in the close vicinity of the bcl-2 gene (Tsujimoto et al. 1985a,b; Tsujimoto and Croce 1986; Cleary et al. 1986), and since the steady-state level of bcl-2 mRNA is elevated by the translocation (Tsujimoto et al. 1985a), the bcl-2 gene is a strong candidate for the oncogene involved in follicular lymphomagenesis, analogous to the role of the c-myc gene in Burkitt’s lymphomagenesis. The bcl-2 gene consists of two exons (Tsujimoto and Croce 1986; Cleary et al. 1986) and is transcribed into several species of mRNA by splicing and differential usage of the polyA site (Tsujimoto and Croce 1986).