Bclaf1 is an important NF-κB signaling transducer and C/EBPβ regulator in DNA damage-induced senescence

Abstract

Inducing senescence in cancer cells is an effective approach to suppress cancer growth, and it contributes significantly to the efficacy of therapeutic drugs. Previous studies indicated that transcription factors NF-κB (nuclear factor κ-light-chain-enhancer of activated B cells) and C/EBPβ (CCAAT/enhancer-binding protein-β) play a critical role in the establishment of senescence by upregulating proinflammatory cytokines, notably interleukin-6 (IL-6) and interleukin-8 (IL-8). However, it is not clear how these two factors are activated in response to senescence-inducing stimuli and subsequently regulate gene transcription. Here, we reveal Bcl-2-associated transcription factor 1 (Bclaf1) as a novel player in the therapeutic drug doxorubicin-induced senescence (TIS) in multiple cancer cells. Bclaf1 is upregulated through the ATM/Nemo/NF-κB pathway during TIS and is a direct target of p65 and c-Rel. The induction of Bclaf1 by NF-κB is essential for C/EBPβ upregulation and IL-6/IL-8 transcription during TIS. Bclaf1 can interact with the leucine zipper region of C/EBPβ and cooperate with C/EBPβ to upregulate IL-8. Furthermore, we show that Bclaf1 is required for the effectiveness of doxorubicin (Dox) treatment-induced tumor suppression in a xenograft tumor model. These finding suggest that Bclaf1 plays a crucial role in transducing the senescence-inducing signal from NF-κB to C/EBPβ during TIS, thus amplifying the signals for the establishment of senescence. Given the recent revelation that Bclaf1 is involved in tumorigenesis, our data indicate that the responsiveness of Bclaf1 to NF-κB may determine the effectiveness of therapeutic drugs.

Effect of BCLAF1 on HDAC inhibitor LMK-235-mediated apoptosis of diffuse large B cell lymphoma cells and its mechanism

“…32 To date, some studies have shown that BCLAF1 as associated with NF-kB, and A-W Shao et al demonstrated that BCLAF1 was regulated by the ATM/Nemo/NF-kB pathway and that it was a direct target of p65 and c-Rel. 26,28,32 We found that both LMK-235 and si-HDAC4 inhibited the activation of NF-kB and enhanced BCLAF1 expression. However, although the NF-kB inhibitor Bay11-7082 increased the expression of BCLAF1, it did not alter HDAC4, suggesting that HDAC4 was located upstream of NF-kB and regulated BCLAF1 through NF-kB.…”

“…24,25 Previous reports have confirmed that BCLAF1 was located directly downstream of NF-kB. 26 In the present study, we use a method involving knockdown of the target gene by siRNA and inhibition of the NF-kB signaling pathway by Bay11-7082, focusing on whether BCLAF1 overexpression plays an apoptotic role in DLBCL, and to explore its possible mechanism of action.…”

Bclaf1 critically regulates the type I interferon response and is degraded by alphaherpesvirus US3

“…Thus, one conceivable role of Bclaf1 in ISGF3 mediated 308 transcription is acting as a mediator attracting ISGF3 to its prebound ISGs promoters for 309 efficient transcription. A similar mode of action is also observed in Bclaf1-regulated C/EBPβ 310 transcription (Shao et al, 2016). Bclaf1 has a DNA-binding ability (Kasof et al, 1999), and we 311 found that the binding between Bclaf1 and the promoter of the ISGs was likely to be a direct 312 event.…”

“…vector with an N-terminal Flag tag. pRK5-Flag-PRV UL50, pRK5-Flag-HSV-1 UL50 and 378 pRK5-Flag-Bclaf1 were previously described(Shao et al, 2016.Bclaf1 379 truncations were amplified by PCR from pRK5-Flag-Bclaf1 and were cloned into the pRK5 380 vector with an N-terminal Flag vector. pRK5-Ha-STAT1/STAT2/IRF9 were constructed by 381 amplifying STAT1/STAT2/IRF9 ORFs by PCR from cDNA synthesized from the total RNA of 382 IFNα-stimulated HeLa cells and cloning it into the pRK5 vector with an N-terminal Ha tag 383 extracted using TRIzol (Invitrogen) following the manufacturer's protocol.…”

Inhibition of tryptophan 2,3-dioxygenase impairs DNA damage tolerance and repair in glioma cells

“…4F). We also observed loss of the NF-kB signal transducer Bcl2-associated transcription factor 1 (Bclaf1), which is upregulated through the ATM/Nemo/NF-kB axis in response to doxorubicin-induced senescence (60).…”