Immunomodulatory effects and improved outcomes with cisplatin- versus carboplatin-based chemotherapy plus atezolizumab in urothelial cancer.

In metastatic urothelial cancer (mUC), cisplatin versus carboplatin leads to durable disease control in a subset of patients. The IMvigor130 trial reveals more favorable effects with atezolizumab combined with gemcitabine and cisplatin (GemCis) versus gemcitabine and carboplatin (GemCarbo). This study investigates the immunomodulatory effects of cisplatin as a potential explanation for these observations.

RIP1 post-translational modifications.

Receptor interacting protein 1 (RIP1) kinase is a critical regulator of inflammation and cell death signaling, and plays a crucial role in maintaining immune responses and proper tissue homeostasis. Mounting evidence argues for the importance of RIP1 post-translational modifications in control of its function. Ubiquitination by E3 ligases, such as inhibitors of apoptosis (IAP) proteins and LUBAC, as well as the reversal of these modifications by deubiquitinating enzymes, such as A20 and CYLD, can greatly influence RIP1 mediated signaling.

Immunoblot Analysis of the Regulation of TNF Receptor Family-Induced NF-κB Signaling by c-IAP Proteins.

Proper maintenance of organismal homeostasis, development, and immune defense requires precise regulation of survival and signaling pathways. Inhibitor of apoptosis (IAP) proteins are evolutionarily conserved regulators of cell death and immune signaling that impact numerous cellular processes. Although initially characterized as inhibitors of apoptosis, the ubiquitin ligase activity of IAP proteins is critical for modulating various signaling pathways (e.

Genetic inactivation of RIP1 kinase does not ameliorate disease in a mouse model of ALS.

RIP1 kinase is proposed to play a critical role in driving necroptosis and inflammation in neurodegenerative disorders, including Amyotrophic Lateral Sclerosis (ALS). Preclinical studies indicated that while pharmacological inhibition of RIP1 kinase can ameliorate axonal pathology and delay disease onset in the mutant SOD1 transgenic (SOD1-Tg) mice, genetic blockade of necroptosis does not provide benefit in this mouse model. To clarify the role of RIP1 kinase activity in driving pathology in SOD1-Tg mice, we crossed SOD1-Tgs to RIP1 kinase-dead knock-in mice, and measured disease progression using functional and histopathological endpoints.

The kinase IRAK4 promotes endosomal TLR and immune complex signaling in B cells and plasmacytoid dendritic cells.

The dysregulation of multiple signaling pathways, including those through endosomal Toll-like receptors (TLRs), Fc gamma receptors (FcγR), and antigen receptors in B cells (BCR), promote an autoinflammatory loop in systemic lupus erythematosus (SLE). Here, we used selective small-molecule inhibitors to assess the regulatory roles of interleukin-1 receptor (IL-1R)-associated kinase 4 (IRAK4) and Bruton's tyrosine kinase (BTK) in these pathways. The inhibition of IRAK4 repressed SLE immune complex- and TLR7-mediated activation of human plasmacytoid dendritic cells (pDCs).

RIP1 kinase activity is critical for skin inflammation but not for viral propagation.

Receptor interacting protein kinase 1 (RIP1) is a critical effector of inflammatory responses and cell death activation. Cell death pathways regulated by RIP1 include caspase-dependent apoptosis and caspase-independent necroptosis. The kinase activity of RIP1 has been associated with a number of inflammatory, neurodegenerative, and oncogenic diseases.

RIP1 inhibition blocks inflammatory diseases but not tumor growth or metastases.

The kinase RIP1 acts in multiple signaling pathways to regulate inflammatory responses and it can trigger both apoptosis and necroptosis. Its kinase activity has been implicated in a range of inflammatory, neurodegenerative, and oncogenic diseases. Here, we explore the effect of inhibiting RIP1 genetically, using knock-in mice that express catalytically inactive RIP1 D138N, or pharmacologically, using the murine-potent inhibitor GNE684.

The kinase TPL2 activates ERK and p38 signaling to promote neutrophilic inflammation.

Tumor progression locus 2 (TPL2; also known as MAP3K8) is a mitogen-activated protein kinase (MAPK) kinase kinase (MAP3K) that phosphorylates the MAPK kinases MEK1 and MEK2 (MEK1/2), which, in turn, activate the MAPKs extracellular signal-regulated kinase 1 (ERK1) and ERK2 (ERK1/2) in macrophages stimulated through the interleukin-1 receptor (IL-1R), Toll-like receptors (TLRs), or the tumor necrosis factor receptor (TNFR). We describe a conserved and critical role for TPL2 in mediating the effector functions of neutrophils through the activation of the p38 MAPK signaling pathway. Gene expression profiling and functional studies of neutrophils and monocytes revealed a MEK1/2-independent branch point downstream of TPL2 in neutrophils.

Intracellular regulation of TNF activity in health and disease.

Tumor Necrosis Factor alpha (TNFα, TNF) is a key mediator and regulator of mammalian immune responses in healthy organisms and in diseased conditions. TNF governs development of the immune system, cell survival signaling pathways, proliferation and regulates metabolic processes. Whereas TNF-induced NF-κB and MAP pro-survival kinase activities constitute its major biochemical functions, TNF can also stimulate cell death in certain pathological situations.

Coordinated ubiquitination and phosphorylation of RIP1 regulates necroptotic cell death.

Proper regulation of cell death signaling is crucial for the maintenance of homeostasis and prevention of disease. A caspase-independent regulated form of cell death called necroptosis is rapidly emerging as an important mediator of a number of human pathologies including inflammatory bowel disease and ischemia-reperfusion organ injury. Activation of necroptotic signaling through TNF signaling or organ injury leads to the activation of kinases receptor-interacting protein kinases 1 and 3 (RIP1 and RIP3) and culminates in inflammatory cell death.

Immunoaffinity enrichment coupled to quantitative mass spectrometry reveals ubiquitin-mediated signaling events.

Ubiquitination is one of the most prevalent posttranslational modifications in eukaryotic cells, with functional importance in protein degradation, subcellular localization and signal transduction pathways. Immunoaffinity enrichment coupled with quantitative mass spectrometry enables the in-depth characterization of protein ubiquitination events at the site-specific level. We have applied this strategy to investigate cellular response triggered by two distinct type agents: small molecule inhibitors of the tumor-associated kinases MEK and PI3K or the pro-inflammatory cytokine IL-17.

Roles of c-IAP proteins in TNF receptor family activation of NF-κB signaling.

Precise regulation of survival and signaling pathways is essential for proper maintenance of organismal homeostasis, development, and immune defense. Inhibitor of apoptosis (IAP) proteins are evolutionarily conserved regulators of cell death and immune signaling that impact numerous cellular processes. Initially characterized as inhibitors of apoptosis, the ubiquitin ligase activity of IAP proteins is critical for modulating various signaling pathways (e.

Ubiquitination profiling identifies sensitivity factors for IAP antagonist treatment.

Evasion of cell death is one crucial capability acquired by tumour cells to ward-off anti-tumour therapies and represents a fundamental challenge to sustaining clinical efficacy for currently available agents. Inhibitor of apoptosis (IAP) proteins use their ubiquitin E3 ligase activity to promote cancer cell survival by mediating proliferative signalling and blocking cell death in response to diverse stimuli. Using immunoaffinity enrichment and MS, ubiquitination sites on thousands of proteins were profiled upon initiation of cell death by IAP antagonists in IAP antagonist-sensitive and -resistant breast cancer cell lines.

OTUB1 modulates c-IAP1 stability to regulate signalling pathways.

The cellular inhibitor of apoptosis (c-IAP) proteins are E3 ubiquitin ligases that are critical regulators of tumour necrosis factor (TNF) receptor (TNFR)-mediated signalling. Through their E3 ligase activity c-IAP proteins promote ubiquitination of receptor-interaction protein 1 (RIP1), NF-κB-inducing kinase (NIK) and themselves, and regulate the assembly of TNFR signalling complexes. Consequently, in the absence of c-IAP proteins, TNFR-mediated activation of NF-κB and MAPK pathways and the induction of gene expression are severely reduced.

Characterization of ML-IAP protein stability and physiological role in vivo.

ML-IAP [melanoma IAP (inhibitor of apoptosis)] is an anti-apoptotic protein that is expressed highly in melanomas where it contributes to resistance to apoptotic stimuli. The anti-apoptotic activity and elevated expression of IAP family proteins in many human cancers makes IAP proteins attractive targets for inhibition by cancer therapeutics. Small-molecule IAP antagonists that bind with high affinities to select BIR (baculovirus IAP repeat) domains have been shown to stimulate auto-ubiquitination and rapid proteasomal degradation of c-IAP1 (cellular IAP1) and c-IAP2 (cellular IAP2).

Cellular inhibitors of apoptosis are global regulators of NF-κB and MAPK activation by members of the TNF family of receptors.

Tumor necrosis factor (TNF) family members are essential for the development and proper functioning of the immune system. TNF receptor (TNFR) signaling is mediated through the assembly of protein signaling complexes that activate the nuclear factor κB (NF-κB) and mitogen-activated protein kinase (MAPK) pathways in a ubiquitin-dependent manner. The cellular inhibitor of apoptosis (c-IAP) proteins c-IAP1 and c-IAP2 are E3 ubiquitin ligases that are recruited to TNFR signaling complexes through their constitutive association with the adaptor protein TNFR-associated factor 2 (TRAF2).

Discovery of a potent small-molecule antagonist of inhibitor of apoptosis (IAP) proteins and clinical candidate for the treatment of cancer (GDC-0152).

A series of compounds were designed and synthesized as antagonists of cIAP1/2, ML-IAP, and XIAP based on the N-terminus, AVPI, of mature Smac. Compound 1 (GDC-0152) has the best profile of these compounds; it binds to the XIAP BIR3 domain, the BIR domain of ML-IAP, and the BIR3 domains of cIAP1 and cIAP2 with K(i) values of 28, 14, 17, and 43 nM, respectively. These compounds promote degradation of cIAP1, induce activation of caspase-3/7, and lead to decreased viability of breast cancer cells without affecting normal mammary epithelial cells.

Antagonists induce a conformational change in cIAP1 that promotes autoubiquitination.

Inhibitor of apoptosis (IAP) proteins are negative regulators of cell death. IAP family members contain RING domains that impart E3 ubiquitin ligase activity. Binding of endogenous or small-molecule antagonists to select baculovirus IAP repeat (BIR) domains within cellular IAP (cIAP) proteins promotes autoubiquitination and proteasomal degradation and so releases inhibition of apoptosis mediated by cIAP.

Inhibitor of apoptosis proteins: fascinating biology leads to attractive tumor therapeutic targets.

Cell death inhibition is a very successful strategy that cancer cells employ to combat the immune system and various anticancer therapies. Inhibitor of apoptosis (IAP) proteins possess a wide range of biological activities that promote cancer survival and proliferation. One of them, X-chromosome-linked IAP is a direct inhibitor of proapoptotic executioners, caspases.

Targeting inhibitor of apoptosis proteins for therapeutic intervention.

The inhibitors of apoptosis (IAP) proteins have emerged over the last decade as important targets for therapeutic intervention in human malignancies. Overexpression of IAPs has been implicated in cell survival and resistance against stress-induced apoptosis brought on by radiation and/or chemotherapeutics (currently the standard-of-care in a variety of different cancer diseases). In addition, evasion from death receptor-mediated apoptosis and regulation of NF-κB pathways and cell division have also been associated with IAP proteins.

X chromosome-linked inhibitor of apoptosis regulates cell death induction by proapoptotic receptor agonists.

Proapoptotic receptor agonists cause cellular demise through the activation of the extrinsic and intrinsic apoptotic pathways. Inhibitor of apoptosis (IAP) proteins block apoptosis induced by diverse stimuli. Here, we demonstrate that IAP antagonists in combination with Fas ligand (FasL) or the death receptor 5 (DR5) agonist antibody synergistically stimulate death in cancer cells and inhibit tumor growth.

Antagonism of c-IAP and XIAP proteins is required for efficient induction of cell death by small-molecule IAP antagonists.

The inhibitor of apoptosis (IAP) proteins are critical regulators of cancer cell survival, which makes them attractive targets for therapeutic intervention in cancers. Herein, we describe the structure-based design of IAP antagonists with high affinities and selectivity (>2000-fold) for c-IAP1 over XIAP and their functional characterization as activators of apoptosis in tumor cells. Although capable of inducing cell death and preventing clonogenic survival, c-IAP-selective antagonists are significantly less potent in promoting apoptosis when compared to pan-selective compounds.

Ubiquitin binding modulates IAP antagonist-stimulated proteasomal degradation of c-IAP1 and c-IAP2(1).

A family of anti-apoptotic regulators known as IAP (inhibitor of apoptosis) proteins interact with multiple cellular partners and inhibit apoptosis induced by a variety of stimuli. c-IAP (cellular IAP) 1 and 2 are recruited to TNFR1 (tumour necrosis factor receptor 1)-associated signalling complexes, where they mediate receptor-induced NF-kappaB (nuclear factor kappaB) activation. Additionally, through their E3 ubiquitin ligase activities, c-IAP1 and c-IAP2 promote proteasomal degradation of NIK (NF-kappaB-inducing kinase) and regulate the non-canonical NF-kappaB pathway.