Department of Cell Biology, School of Biological Sciences & Biotechnology, Indian Institute of Advanced Research, Koba Institutional Area, Gandhinagar 382 007, Gujarat, India.
Int J Mol Sci. 2020 Sep 19;21(18):6890. doi: 10.3390/ijms21186890.
Dysregulated expression of Fas-associated death domain (FADD) is associated with the impediment of various cellular pathways, including apoptosis and inflammation. The adequate cytosolic expression of FADD is critical to the regulation of cancer cell proliferation. Importantly, cancer cells devise mechanisms to suppress FADD expression and, in turn, escape from apoptosis signaling. Formulating strategies, for direct delivery of FADD proteins into cancer cells in a controlled manner, may represent a promising therapeutic approach in cancer therapy. We chemically conjugated purified FADD protein with cell permeable TAT (transactivator of transcription) peptide, to deliver in cancer cells. TAT-conjugated FADD protein internalized through the caveolar pathway of endocytosis and retained in the cytosol to augment cell death. Inside cancer cells, TAT-FADD rapidly constituted DISC (death inducing signaling complex) assembly, which in turn, instigate apoptosis signaling. The apoptotic competency of TAT-FADD showed comparable outcomes with the conventional apoptosis inducers. Notably, TAT-FADD mitigates constitutive NF-κB activation and associated downstream anti-apoptotic genes , , , and , independent of pro-cancerous TNF-α priming. In cancer cells, TAT-FADD suppresses the canonical NLRP3 inflammasome priming and restricts the processing and secretion of proinflammatory IL-1β. Our results demonstrate that TAT-mediated intracellular delivery of FADD protein can potentially recite apoptosis signaling with simultaneous regulation of anti-apoptotic and proinflammatory NF-κB signaling activation in cancer cells.
Fas 相关死亡结构域（FADD）表达失调与多种细胞通路的抑制有关，包括细胞凋亡和炎症。FADD 的适当细胞内表达对于调节癌细胞增殖至关重要。重要的是，癌细胞会设计机制来抑制 FADD 的表达，从而逃避细胞凋亡信号。以受控方式将 FADD 蛋白直接递送至癌细胞的策略可能代表癌症治疗的一种有前途的治疗方法。我们通过化学方法将纯化的 FADD 蛋白与细胞穿透 TAT（转录激活因子）肽缀合，以递送至癌细胞中。TAT 缀合的 FADD 蛋白通过胞吞作用的小窝途径内化，并保留在细胞质中以增强细胞死亡。在癌细胞内，TAT-FADD 迅速构成 DISC（死亡诱导信号复合物）组装，进而引发细胞凋亡信号。TAT-FADD 的凋亡能力与传统的凋亡诱导剂具有可比的结果。值得注意的是，TAT-FADD 减轻了 NF-κB 的组成性激活和相关的下游抗凋亡基因 、 、 、 和 ，而不依赖于致癌性 TNF-α 引发。在癌细胞中，TAT-FADD 抑制经典的 NLRP3 炎性小体引发，并限制促炎 IL-1β 的加工和分泌。我们的研究结果表明，TAT 介导的 FADD 蛋白的细胞内递送至癌细胞内可能通过同时调节抗凋亡和促炎 NF-κB 信号通路的激活来重新激活细胞凋亡信号。
