Institute for Experimental Pediatric Hematology and Oncology, Goethe University Frankfurt, Komturstrasse 3a, 60528, Frankfurt, Germany.
Institute for Pharmaceutical Chemistry, Germany and Structural Genomics Consortium, Buchmann Institute for Life Sciences, Goethe-University Frankfurt, Max-von-Laue- Str. 9, Biozentrum, 60438, Frankfurt am Main, Germany.
Cell Commun Signal. 2024 Aug 27;22(1):415. doi: 10.1186/s12964-024-01782-9.
The antiapoptotic protein BCL2A1 is highly, but very heterogeneously expressed in Diffuse Large B-cell Lymphoma (DLBCL). Particularly in the context of resistance to current therapies, BCL2A1 appears to play an important role in protecting cancer cells from the induction of cell death. Reducing BCL2A1 levels may have therapeutic potential, however, no specific inhibitor is currently available. In this study, we hypothesized that the signaling network regulated by epigenetic readers may regulate the transcription of BCL2A1 and hence that inhibition of Bromodomain and Extra-Terminal (BET) proteins may reduce BCL2A1 expression thus leading to cell death in DLBCL cell lines. We found that the mechanisms of action of acetyl-lysine competitive BET inhibitors are different from those of proteolysis targeting chimeras (PROTACs) that induce the degradation of BET proteins. Both classes of BETi reduced the expression of BCL2A1 which coincided with a marked downregulation of c-MYC. Mechanistically, BET inhibition attenuated the constitutively active canonical nuclear factor kappa-light-chain-enhancer of activated B-cells (NFκB) signaling pathway and inhibited p65 activation. Furthermore, signal transducer of activated transcription (STAT) signaling was reduced by inhibiting BET proteins, targeting another pathway that is often constitutively active in DLBCL. Both pathways were also inhibited by the IκB kinase inhibitor TPCA-1, resulting in decreased BCL2A1 and c-MYC expression. Taken together, our study highlights a novel complex regulatory network that links BET proteins to both NFκB and STAT survival signaling pathways controlling both BCL2A1 and c-MYC expression in DLBCL.
抗凋亡蛋白 BCL2A1 在弥漫性大 B 细胞淋巴瘤 (DLBCL) 中高度表达,但非常异质性。特别是在当前治疗方法耐药的情况下,BCL2A1 似乎在保护癌细胞免受细胞死亡诱导方面发挥重要作用。降低 BCL2A1 水平可能具有治疗潜力,但是,目前没有特定的抑制剂。在这项研究中,我们假设受表观遗传阅读器调节的信号网络可能调节 BCL2A1 的转录,因此抑制溴结构域和末端 (BET) 蛋白可能会降低 BCL2A1 的表达,从而导致 DLBCL 细胞系死亡。我们发现,乙酰化赖氨酸竞争 BET 抑制剂的作用机制与诱导 BET 蛋白降解的蛋白水解靶向嵌合体 (PROTAC) 不同。这两类 BETi 均降低了 BCL2A1 的表达,同时显著下调了 c-MYC。从机制上讲,BET 抑制减弱了固有活性的经典核因子 kappa-轻链增强子激活 B 细胞 (NFκB) 信号通路并抑制了 p65 激活。此外,通过抑制 BET 蛋白抑制信号转导激活转录 (STAT) 信号,靶向另一条在 DLBCL 中经常固有活性的途径。两条途径也被 IκB 激酶抑制剂 TPCA-1 抑制,导致 BCL2A1 和 c-MYC 表达减少。总之,我们的研究强调了一种新的复杂调节网络,该网络将 BET 蛋白与 NFκB 和 STAT 生存信号通路联系起来,控制 DLBCL 中 BCL2A1 和 c-MYC 的表达。