B-cell lymphoma 2 protein and B-cell lymphoma-extra large protein (BCL-2 and BCL-xL)

B-cell lymphoma 2 protein (BCL-2) and B-cell lymphoma-extra large protein (BCL-xL) are central members of the BCL-2 family of proteins, which regulate the intrinsic apoptotic pathway by controlling mitochondrial outer membrane permeabilization and cytochrome c release[1][5]. Both BCL-2 and BCL-xL act as anti-apoptotic factors by sequestering pro-apoptotic proteins (such as BAX and BAK) through a conserved set of BCL-2 homology (BH) domains, thereby preventing cell death in response to various stresses[5][2]. Overexpression of BCL-2 and BCL-xL is commonly observed in a wide range of cancers, where it contributes to tumor cell survival, resistance to chemotherapy, and disease progression[5][7]. Both proteins are therapeutic targets; small-molecule inhibitors (BH3 mimetics) antagonize their function to promote apoptosis in cancer cells, with venetoclax (for BCL-2) used clinically in hematological malignancies[7]. Major safety challenges include the risk of thrombocytopenia (for BCL-xL inhibitors) and tumor lysis syndrome (for potent BCL-2 inhibitors).

Other names

B-cell leukemia/lymphoma 2 (BCL-2)BCL2B-cell lymphoma-extra large (BCL-xL)BCL2L1Bcl2Bcl-xL

Inhibition of anti-apoptotic function (BH3 mimetics block binding to pro-apoptotic partners, releasing apoptogenic factors) Sensitization of cancer cells to apoptosis via displacement of pro-apoptotic proteins (e.g., BAX, BAK)