Project description:Myeloid-derived suppressor cells (MDSC) include immature monocytic (M-MDSC) and granulocytic (PMN-MDSC) cells that share the ability to suppress adaptive immunity and hinder the effectiveness of anti-cancer treatments. Of note, in response to interferon-γ (IFNγ) M-MDSC release the tumor-promoting and immunosuppressive molecule nitric oxide (NO), whereas macrophages largely express anti-tumor properties. Investigating these opposing activities, we found that tumor-derived prostaglandin E2 (PGE2) induces nuclear accumulation of p50 NF-κB in M-MDSC, diverting their response to IFNγ towards NO-mediated immunosuppression and reducing TNFα expression. At the genome level, p50 NF-κB promoted binding of STAT1 to regulatory regions of selected IFNγ-dependent genes, including inducible nitric oxide synthase (Nos2). In agreement, ablation of p50 as well as pharmacological inhibition of either the PGE2 receptor EP2 or NO production reprogrammed M-MDSC towards a NOS2low/TNFαhigh phenotype, restoring the in vivo antitumor activity of IFNγ. Our results indicate that inhibition of the PGE2/p50/NO axis prevents MDSC suppressive functions and restores the efficacy of anticancer immunotherapy.
Project description:CD95 expression is preserved in triple-negative breast cancers (TNBCs) and CD95 loss in these cells triggers the induction of a pro-inflammatory program promoting the recruitment of cytotoxic NK cells impairing tumor growth. Herein, we identify a novel interaction partner of CD95, Kip1 ubiquitination-promoting complex protein 2 (KPC2) using an unbiased proteomic approach. Independently of CD95L, CD95/KPC2 interaction contributes to the partial degradation of p105 (NFκB1) and the subsequent generation of p50 homodimers, which transcriptionally represses NF-κB-driven gene expression. Mechanistically, KPC2 interacts with the C-terminal region of CD95 and serves as an adaptor to recruit RelA (p65) and KPC1, which acts as E3 ubiquitin-protein ligase promoting the degradation of p105 into p50. Loss of CD95 in TNBC cells releases KPC2, limiting the formation of the NF-κB inhibitory homodimer complex (p50/p50), promoting NF-κB activation and the production of pro-inflammatory cytokines, that could account for the immune landscape remodeling in TNBC cells
Project description:Pro-inflammatory cytokines were shown to promote growth and survival of cancerous cells. TNF induced RelA:p50 NF-κB dimer via the canonical pathway is thought to link inflammation with cancer. Integrating biochemical and computational studies we identify that deficiency of non-canonical signal transducer p100 triggers a positive autoregulatory loop, which instead perpetuates an alternate RelB:p50 containing NF-κB activity upon TNF treatment. TNF stimulated RelB:p50 dimer is sufficient for mediating NF-κB target gene-expressions and suppressing apoptotic cellular death independent of principal NF-κB subunit RelA. We further demonstrate that activating mutations in non-canonical NF-κB module deplete multiple myeloma cells of p100, thereby, provoking autoregulatory RelB:p50 activation. Finally, autoregulatory control reinforces protracted pro-survival NF-κB response, albeit comprising of RelB:p50, upon TNF priming that protects myeloma cells with dysfunctional p100 from subsequent apoptotic insults. In sum, we present evidence for positive autoregulation mediated through the NF-κB system and its potential involvement in human neoplasm.
Project description:Skeletal muscle atrophy is a debilitating condition associated with weakness, fatigue, and reduced functional capacity. Nuclear factor-kappaB (NF-κB) transcription factors play a critical role in atrophy. Knockout of genes encoding p50 or the NF-κB co-transactivator, Bcl-3, abolish disuse atrophy and thus they are NF-κB factors required for disuse atrophy. We do not know however, the genes targeted by NF-κB that produce the atrophied phenotype. Here we identify the genes required to produce disuse atrophy using gene expression profiling in wild type compared to Nfkb1 (gene encodes p50) and Bcl-3 deficient mice. There were 185 and 240 genes upregulated in wild type mice due to unloading, that were not upregulated in Nfkb1-/- and Bcl-3-/- mice, respectively, and so these genes were considered direct or indirect targets of p50 and Bcl-3. All of the p50 gene targets were contained in the Bcl-3 gene target list. Most genes were involved with protein degradation, signaling, translation, transcription, and transport. To identify direct targets of p50 and Bcl-3 we performed chromatin immunoprecipitation of selected genes previously shown to have roles in atrophy. Trim63 (MuRF1), Fbxo32 (MAFbx), Ubc, Ctsl, Runx1, Tnfrsf12a (Tweak receptor), and Cxcl10 (IP-10) showed increased Bcl-3 binding to κB sites in unloaded muscle and thus were direct targets of Bcl-3. p50 binding to the same sites on these genes either did not change or increased, supporting the idea of p50:Bcl-3 binding complexes. p65 binding to κB sites showed decreased or no binding to these genes with unloading. Fbxo9, Psma6, Psmc4, Psmg4, Foxo3, Ankrd1 (CARP), and Eif4ebp1 did not show changes in p65, p50, or Bcl-3 binding to κB sites, and so were considered indirect targets of p50 and Bcl-3. This work represents the first study to use a global approach to identify genes required to produce the atrophied phenotype with disuse. 24 mice were used based on 4 mice per group, 3 mouse genotypes (wild type, Nfkb1-/-, Bcl3-/-) and 2 conditions (weight-bearing and unloaded).
Project description:The transcription factor, NF-кB, plays a central role in the response to DNA damage. This ubiquitous family of proteins is made up of five subunits: p50 (NF-κB1, p105), p52 (NF-κB2, p100), p65 (relA), relB, and crel that appear in their mature form as dimers. Following stimulation, NF-κB dimers translocate to the nucleus where they bind specific consensus elements (κB-sites) in the promoter region of genes involved in cell survival, inflammation and the immune system. While there is a general propensity of NF-кB to mediate survival, this is not always the case and several reports note the pro-apoptotic nature of the NF-кB pathway. In examining the NF-кB response to DNA damage, we have found that the p50 subunit plays a central role in modulating cytotoxicity following TMZ treatment in malignant glioma. In the current study, given the importance of p50 to the cytotoxic response to TMZ, we set out to identify NF-кB-dependent factors that modulate the response to TMZ. U-87 glioma cells stably transfected with either control-shRNA or p105-shRNA and subsequently treated with temozolomide (TMZ) were selected for RNA extraction and hybridization on Affymetrix microarrays. Each category contains 3 biologic replicates.
Project description:RNA N6-methyladenosine (m6A) modification is implicated in cancer progression. However, the impact of m6A on the antitumor effects of radiotherapy and the related mechanisms are unknown. Here we show that ionizing radiation (IR) induces immunosuppressive myeloid-derived suppressor cell (MDSC) expansion and YTHDF2 expression in both murine models and humans. Following IR, loss of Ythdf2 in myeloid cells augments antitumor immunity and overcomes tumor radioresistance by altering MDSC differentiation and inhibiting MDSC infiltration and suppressive function. The remodeling of the landscape of MDSC populations by local IR is reversed by Ythdf2 deficiency. IR-induced YTHDF2 expression relies on NF-κB signaling; YTHDF2 in turn leads to NF-κB activation by directly binding and degrading transcripts encoding negative regulators of NF-κB signaling, resulting in an IR-YTHDF2-NF-κB circuit. Pharmacological inhibition of YTHDF2 overcomes MDSC-induced immunosuppression and improves combined IR and/or anti-PD-L1 treatment. Thus, YTHDF2 is a promising target to improve radiotherapy (RT) and RT/immunotherapy combinations.
Project description:RNA N6-methyladenosine (m6A) modification is implicated in cancer progression. However, the impact of m6A on the antitumor effects of radiotherapy and the related mechanisms are unknown. Here we show that ionizing radiation (IR) induces immunosuppressive myeloid-derived suppressor cell (MDSC) expansion and YTHDF2 expression in both murine models and humans. Following IR, loss of Ythdf2 in myeloid cells augments antitumor immunity and overcomes tumor radioresistance by altering MDSC differentiation and inhibiting MDSC infiltration and suppressive function. The remodeling of the landscape of MDSC populations by local IR is reversed by Ythdf2 deficiency. IR-induced YTHDF2 expression relies on NF-κB signaling; YTHDF2 in turn leads to NF-κB activation by directly binding and degrading transcripts encoding negative regulators of NF-κB signaling, resulting in an IR-YTHDF2-NF-κB circuit. Pharmacological inhibition of YTHDF2 overcomes MDSC-induced immunosuppression and improves combined IR and/or anti-PD-L1 treatment. Thus, YTHDF2 is a promising target to improve radiotherapy (RT) and RT/immunotherapy combinations.
Project description:RNA N6-methyladenosine (m6A) modification is implicated in cancer progression. However, the impact of m6A on the antitumor effects of radiotherapy and the related mechanisms are unknown. Here we show that ionizing radiation (IR) induces immunosuppressive myeloid-derived suppressor cell (MDSC) expansion and YTHDF2 expression in both murine models and humans. Following IR, loss of Ythdf2 in myeloid cells augments antitumor immunity and overcomes tumor radioresistance by altering MDSC differentiation and inhibiting MDSC infiltration and suppressive function. The remodeling of the landscape of MDSC populations by local IR is reversed by Ythdf2 deficiency. IR-induced YTHDF2 expression relies on NF-κB signaling; YTHDF2 in turn leads to NF-κB activation by directly binding and degrading transcripts encoding negative regulators of NF-κB signaling, resulting in an IR-YTHDF2-NF-κB circuit. Pharmacological inhibition of YTHDF2 overcomes MDSC-induced immunosuppression and improves combined IR and/or anti-PD-L1 treatment. Thus, YTHDF2 is a promising target to improve radiotherapy (RT) and RT/immunotherapy combinations.
Project description:RNA N6-methyladenosine (m6A) modification is implicated in cancer progression. However, the impact of m6A on the antitumor effects of radiotherapy and the related mechanisms are unknown. Here we show that ionizing radiation (IR) induces immunosuppressive myeloid-derived suppressor cell (MDSC) expansion and YTHDF2 expression in both murine models and humans. Following IR, loss of Ythdf2 in myeloid cells augments antitumor immunity and overcomes tumor radioresistance by altering MDSC differentiation and inhibiting MDSC infiltration and suppressive function. The remodeling of the landscape of MDSC populations by local IR is reversed by Ythdf2 deficiency. IR-induced YTHDF2 expression relies on NF-κB signaling; YTHDF2 in turn leads to NF-κB activation by directly binding and degrading transcripts encoding negative regulators of NF-κB signaling, resulting in an IR-YTHDF2-NF-κB circuit. Pharmacological inhibition of YTHDF2 overcomes MDSC-induced immunosuppression and improves combined IR and/or anti-PD-L1 treatment. Thus, YTHDF2 is a promising target to improve radiotherapy (RT) and RT/immunotherapy combinations.
Project description:The transcription factor, NF-кB, plays a central role in the response to DNA damage. This ubiquitous family of proteins is made up of five subunits: p50 (NF-κB1, p105), p52 (NF-κB2, p100), p65 (relA), relB, and crel that appear in their mature form as dimers. Following stimulation, NF-κB dimers translocate to the nucleus where they bind specific consensus elements (κB-sites) in the promoter region of genes involved in cell survival, inflammation and the immune system. While there is a general propensity of NF-кB to mediate survival, this is not always the case and several reports note the pro-apoptotic nature of the NF-кB pathway. In examining the NF-кB response to DNA damage, we have found that the p50 subunit plays a central role in modulating cytotoxicity following TMZ treatment in malignant glioma. In the current study, given the importance of p50 to the cytotoxic response to TMZ, we set out to identify NF-кB-dependent factors that modulate the response to TMZ.