Knock down of Fas-Associated Protein with Death Domain (FADD) Sensitizes Osteosarcoma to TNFα-induced Cell Death

Abstract

Fas-associated protein with death domain (FADD) was first identified for its role in linking death receptors to the apoptotic signaling pathway with subsequent cell death. Later studies reported non-apoptotic functions for FADD in normal cells and cancer cells. Non-apoptotic functions for FADD in osteosarcoma (OS) have not been reported. In this study, FADD protein expression was knocked down in human CCHOSD, LM7, and SaOS2 OS cell lines followed by assessment of sensitivity to TNFα-or TRAIL-induced cell death. Knock down of FADD significantly increased TNFα-induced cell death in LM7 and SaOS2 cell lines. The mode of TNFα-induced cell death was apoptosis and not necroptosis. Inhibition of nuclear factor kappa B (NFκB) in wildtype cells increased TNFα-induced cell death to similar levels observed in FADD knockdown cells, suggesting a role for FADD in NFκB pro-survival cell signaling. In addition, knock down of FADD increased SMAC mimetic-mediated TNFα-induced cell death in all cell lines studied. The results of this study indicate that FADD has a pro-survival function in OS following TNFα treatment that involves NFκB signaling. The results also indicate that the pro-survival function of FADD is associated with XIAP activity.

Fas regulates the apoptosis and migration of trophoblast cells by targeting NF‑κB

“…By contrast, the knockdown of Fas suppressed the apoptosis of trophoblast cells, and significantly increased trophoblast viability and migration. These results are consistent with the role served by Fas in osteosarcoma ( 30 ), cervical cancer ( 31 ), lung cancer ( 32 ) and breast cancer ( 33 ). The knockdown of Fas decreased the expression of TNF-α, IL-2 and Bax, and increased the expression of Bcl-2.…”

COLEC12 regulates apoptosis of osteosarcoma through Toll‐like receptor 4–activated inflammation

“…hFOB is human osteoblast cell line, and 143B, MG‐63, Saos‐2, and HOS are human osteosarcoma cell lines. Cells were cultured in DMEM containing 10% FBS and supplemented with an antibiotic, non‐essential amino acid solution, and MEM vitamin mixture and cultured in an incubator maintained at 5% CO 2 and 37°C, as described previously 19 …”

FADD as a key molecular player in cancer progression

“…They discovered that FADD knockdown facilitated cell apoptosis in osteosarcoma LM7 or SaOS2 cells treated with TNFα. Further analysis revealed that the inhibition of NF-κB in wildtype LM7 cells significantly increased TNFα-induced apoptosis to similar levels observed in the FADD knockdown of LM7 cells, indicating that FADD plays a role in NF-κB pro-survival signaling (Hollomon et al 2020). Wang et al conducted qRT-PCR and WB to detect FADD expression and found that FADD was downregulated in GBM tissues and cell lines SC189, u251, and SHG44.…”

“…FADD is a well-known adaptor protein for DR-mediated extrinsic apoptosis (Zhou et al 2022b). A large number of studies have shown that FADD is involved in cancer progression by regulating apoptosis (Hollomon et al 2020;Mrkvova et al 2021;Wang et al 2017). For instance, Hollomorn et al performed trypan blue exclusion and WB assays to examine the effect of FADD on TNFα-induced cell death.…”