B-cell lymphoma 2 (Bcl-2) (Bcl-2)

B-cell lymphoma 2 (Bcl-2) is a pivotal anti-apoptotic protein and the founding member of the Bcl-2 family, which governs the intrinsic pathway of programmed cell death [1, 4]. It is primarily localized to the outer mitochondrial membrane, where it functions by sequestering pro-apoptotic effector proteins like BAX and BAK, as well as activator BH3-only proteins like BIM [1, 9]. By preventing these proteins from forming pores in the mitochondrial membrane, Bcl-2 inhibits the release of cytochrome c and the subsequent activation of caspases that execute cell death [9, 12]. In many cancers, particularly hematological malignancies like follicular lymphoma and chronic lymphocytic leukemia, Bcl-2 is pathologically overexpressed—often due to the t(14;18) chromosomal translocation—enabling tumor cells to survive despite oncogenic stress or chemotherapy [5, 16]. This makes Bcl-2 a high-value therapeutic target; the development of BH3 mimetics, such as the FDA-approved drug venetoclax, has revolutionized treatment by specifically inhibiting Bcl-2 to restore the apoptotic process [9, 10]. However, clinical use is associated with risks such as tumor lysis syndrome and the potential for acquired resistance through mutations in the Bcl-2 binding site or the upregulation of alternative survival proteins like MCL-1 [9, 13].

Other names

BCL2Apoptosis regulator Bcl-2B-cell CLL/lymphoma 2PPP1R50

BH3 mimetic that binds to the hydrophobic BH3-binding groove of Bcl-2, displacing pro-apoptotic proteins (e.g., BIM, BAX, BAK) to induce mitochondrial outer membrane permeabilization (MOMP) and subsequent apoptosis [2, 7, 9, 12].