Fn14·TRAIL fusion protein is oligomerized by TWEAK into a superefficient TRAIL analog

The Role of TRAIL Signaling in Cancer: Searching for New Therapeutic Strategies

Cancer continues to pose a significant threat to global health, with its status as a leading cause of death remaining unchallenged. Within the realm of cancer research, the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) stands out as a critical player, having been identified in the 1990s as the tenth member of the TNF family. This review examines the pivotal role of TRAIL in cancer biology, focusing on its ability to induce apoptosis in malignant cells through both endogenous and exogenous pathways. We provide an in-depth analysis of TRAIL's intracellular signaling and intercellular communication, underscoring its potential as a selective anticancer agent. Additionally, the review explores TRAIL's capacity to reshape the tumor microenvironment, thereby influencing cancer progression and response to therapy. With an eye towards future developments, we discuss the prospects of harnessing TRAIL's capabilities for the creation of tailored, precision-based cancer treatments, aiming to enhance efficacy and improve patient survival rates.

Dual targeting of DR5 and VEGFR2 molecular pathways by multivalent fusion protein significantly suppresses tumor growth and angiogenesis

Destroying tumor vasculature is a relevant therapeutic strategy due to its involvement in tumor progression. However, adaptive resistance to approved antiangiogenic drugs targeting VEGF/VEGFR pathway requires the recruitment of additional targets. In this aspect, targeting TRAIL pathway is promising as it is an important component of the immune system involved in tumor immunosurveillance. For dual targeting of malignant cells and tumor vascular microenvironment, we designed a multivalent fusion protein SRH-DR5-B-iRGD with antiangiogenic VEGFR2-specific peptide SRH at the N-terminus and a tumor-targeting and -penetrating peptide iRGD at the C-terminus of receptor-selective TRAIL variant DR5-B. SRH-DR5-B-iRGD obtained high affinity for DR5, VEGFR2 and αvβ3 integrin in nanomolar range. Fusion of DR5-B with effector peptides accelerated DR5 receptor internalization rate upon ligand binding. Antitumor efficacy was evaluated in vitro in human tumor cell lines and primary patient-derived glioblastoma neurospheres, and in vivo in xenograft mouse model of human glioblastoma. Multivalent binding of SRH-DR5-B-iRGD fusion efficiently stimulated DR5-mediated tumor cell death via caspase-dependent mechanism, suppressed xenograft tumor growth by >80 %, doubled the lifespan of xenograft animals, and inhibited tumor vascularization. Therefore, targeting DR5 and VEGFR2 molecular pathways with SRH-DR5-B-iRGD protein may provide a novel therapeutic approach for treatment of solid tumors.

Homer1 promotes the conversion of A1 astrocytes to A2 astrocytes and improves the recovery of transgenic mice after intracerebral hemorrhage

Background

Inflammation induced by intracerebral hemorrhage (ICH) is one of the main causes of the high mortality and poor prognosis of patients with ICH. A1 astrocytes are closely associated with neuroinflammation and neurotoxicity, whereas A2 astrocytes are neuroprotective. Homer scaffolding protein 1 (Homer1) plays a protective role in ischemic encephalopathy and neurodegenerative diseases. However, the role of Homer1 in ICH-induced inflammation and the effect of Homer1 on the phenotypic conversion of astrocytes remain unknown.

Methods

Femoral artery autologous blood from C57BL/6 mice was used to create an ICH model. We use the A1 phenotype marker C3 and A2 phenotype marker S100A10 to detect astrocyte conversion after ICH. Homer1 overexpression/knock-down mice were constructed by adeno-associated virus (AAV) infection to explore the role of Homer1 and its mechanism of action after ICH. Finally, Homer1 protein and selumetinib were injected into in situ hemorrhage sites in the brains of Homer1^flox/flox/Nestin-Cre^+/− mice to study the efficacy of Homer1 in the treatment of ICH by using a mouse cytokine array to explore the potential mechanism.

Results

The expression of Homer1 peaked on the third day after ICH and colocalized with astrocytes. Homer1 promotes A1 phenotypic conversion in astrocytes in vivo and in vitro. Overexpression of Homer1 inhibits the activation of MAPK signaling, whereas Homer1 knock-down increases the expression of pathway-related proteins. The Homer1 protein and selumetinib, a non-ATP competitive MEK1/2 inhibitor, improved the outcome in ICH in Homer1^flox/flox/Nestin-Cre^+/− mice. The efficacy of Homer1 in the treatment of ICH is associated with reduced expression of the inflammatory factor TNFSF10 and increased expression of the anti-inflammatory factors activin A, persephin, and TWEAK.

Conclusions

Homer1 plays an important role in inhibiting inflammation after ICH by suppressing the A1 phenotype conversion in astrocytes. In situ injection of Homer1 protein may be a novel and effective method for the treatment of inflammation after ICH.

TWEAK-Fn14 as a common pathway in the heart and the kidneys in cardiorenal syndrome

There is a complex relationship between cardiac and renal disease, often referred to as the cardiorenal syndrome. Heart failure adversely affects kidney function, and both acute and chronic kidney disease are associated with structural and functional changes to the myocardium. The pathological mechanisms and contributing interactions that surround this relationship remain poorly understood, limiting the opportunities for therapeutic intervention. The cytokine tumor necrosis factor-like weak inducer of apoptosis (TWEAK) and its receptor, fibroblast growth factor-inducible 14 (Fn14), are abundantly expressed in injured kidneys and heart. The TWEAK-Fn14 axis promotes responses that drive tissue injury such as inflammation, proliferation, fibrosis, and apoptosis, while restraining the expression of tissue protective factors such as the anti-aging factor Klotho and the master regulator of mitochondrial biogenesis peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α). High levels of TWEAK induce cardiac remodeling, and promote inflammation, tubular and podocyte injury and death, fibroblast proliferation, and, ultimately, renal fibrosis. Accordingly, targeting the TWEAK-Fn14 axis is protective in experimental kidney and heart disease. TWEAK has also emerged as a biomarker of kidney damage and cardiovascular outcomes and has been successfully targeted in clinical trials. In this review, we update our current knowledge of the roles of the TWEAK-Fn14 axis in cardiovascular and kidney disease and its potential contribution to the cardiorenal syndrome. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

TWEAK/Fn14 axis is an important player in fibrosis

Fibrosis is a common pathological condition associated with abnormal repair after tissue injury. However, the etiology and molecular mechanisms of fibrosis are still not well-understood. Tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) belongs to the TNF superfamily and acts by binding to its receptor, fibroblast growth factor-inducible 14 (Fn14), thereby activating a variety of intracellular signal transduction pathways in various types of cells. Besides promoting the expression of growth factors, activation of TWEAK/Fn14 signaling after tissue injury can promote the expression of pro-inflammatory cytokines, which trigger the immune response, thereby exacerbating the injury. Severe or repetitive injury leads to a dysregulated tissue repair process, in which the TWEAK/Fn14 axis promotes the activation and proliferation of myofibroblasts, induces the secretion of the extracellular matrix, and regulates profibrotic mediators to further perpetuate and sustain the fibrotic process. In this review, we summarize the available experimental evidence on the underlying molecular mechanisms by which the TWEAK/Fn14 pathway mediates the development and progression of fibrosis. In addition, we discuss the therapeutic potential of the TWEAK/Fn14 pathway in fibrosis-associated diseases based on evidence derived from multiple models and cells from injured tissue and fibrotic tissue.

TWEAK Promotes the Proliferation of Squamous Cell Carcinoma Cells Through Activating cIAP1 Signals

Recent studies showed that tumor necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK) induces the proliferation of squamous cell carcinoma (SCC) cells. However, the precise mechanism underlying such effect of TWEAK remains unclear. This study was designed to elucidate the role of cellular inhibitor of apoptosis 1 (cIAP1) in TWEAK-induced proliferation of SCC cells. Human SCC cells (SCC-13, A431, and SCC-9) were cultured in vitro, receiving the stimulation of TWEAK or TNF-related apoptosis-inducing ligand (TRAIL). We found that TWEAK induced cytoplasmic cIAP1 importation and RIP1 ubiquitination in cells, followed by the activation of canonical nuclear factor kappa B signals. MV1, a cIAP1 inhibitor, abrogated TWEAK-induced proliferation of these cells. Moreover, the interaction between TWEAK and its receptor, fibroblast growth factor-inducible 14 (Fn14), enhanced the expression of TRAIL receptor types 3 and 4 (TRAIL-R3/4). Furthermore, the transfection of TRAIL-R3/4 siRNA abrogated the promotion effect of TWEAK on SCC-13 cell proliferation and cIAP1 expression. Therefore, TWEAK/Fn14 interaction promotes the proliferation of SCC cells through activating cIAP1 signals. Targeting the downstream cIAP1 signals might attenuate the effect of TWEAK on SCC cells.

Molecular Mode of Action of TRAIL Receptor Agonists-Common Principles and Their Translational Exploitation

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and its death receptors TRAILR1/death receptor 4 (DR4) and TRAILR2/DR5 trigger cell death in many cancer cells but rarely exert cytotoxic activity on non-transformed cells. Against this background, a variety of recombinant TRAIL variants and anti-TRAIL death receptor antibodies have been developed and tested in preclinical and clinical studies. Despite promising results from mice tumor models, TRAIL death receptor targeting has failed so far in clinical studies to show satisfying anti-tumor efficacy. These disappointing results can largely be explained by two issues: First, tumor cells can acquire TRAIL resistance by several mechanisms defining a need for combination therapies with appropriate sensitizing drugs. Second, there is now growing preclinical evidence that soluble TRAIL variants but also bivalent anti-TRAIL death receptor antibodies typically require oligomerization or plasma membrane anchoring to achieve maximum activity. This review discusses the need for oligomerization and plasma membrane attachment for the activity of TRAIL death receptor agonists in view of what is known about the molecular mechanisms of how TRAIL death receptors trigger intracellular cell death signaling. In particular, it will be highlighted which consequences this has for the development of next generation TRAIL death receptor agonists and their potential clinical application.

Importance of TRAIL Molecular Anatomy in Receptor Oligomerization and Signaling. Implications for Cancer Therapy

(TNF)-related apoptosis-inducing ligand (TRAIL) is able to activate the extrinsic apoptotic pathway upon binding to DR4/TRAIL-R1 and/or DR5/TRAIL-R2 receptors. Structural data indicate that TRAIL functions as a trimer that can engage three receptor molecules simultaneously, resulting in receptor trimerization and leading to conformational changes in TRAIL receptors. However, receptor conformational changes induced by the binding of TRAIL depend on the molecular form of this death ligand, and not always properly trigger the apoptotic cascade. In fact, TRAIL exhibits a much stronger pro-apoptotic activity when is found as a transmembrane protein than when it occurs as a soluble form and this enhanced biological activity is directly linked to its ability to cluster TRAIL receptors in supra-molecular structures. In this regard, cells involved in tumor immunosurveillance, such as activated human T cells, secrete endogenous TRAIL as a transmembrane protein associated with lipid microvesicles called exosomes upon T-cell reactivation. Consequently, it seems clear that a proper oligomerization of TRAIL receptors, which leads to a strong apoptotic signaling, is crucial for inducing apoptosis in cancer cells upon TRAIL treatment. In this review, the current knowledge of oligomerization status of TRAIL receptors is discussed as well as the implications for cancer treatment when using TRAIL-based therapies.

TGF3L fusion enhances the antitumor activity of TRAIL by promoting assembly into polymers

TRAIL, a promising antitumor immuno-agent, exerted limited efficacy in clinical trials. The third disulfide loop of TGF-α (TGF3L peptide) with a very low affinity for EGFR has been reported to enhance the activity of fused antigens or cytokines. We wondered whether fusion of this peptide could enhance TRAIL activity and what the underlying mechanism for this enhancement would be. The TGF3L-TRAIL showed greatly enhanced cytotoxicity in a variety of cancer cell lines while spared normal cells unharmed. Typical apoptosis and cellular caspase activation were potently induced by TGF3L-TRAIL at the concentration levels corresponding to its cytotoxicity. TGF3L-TRAIL was able to activate both DR4 and DR5 the same as TRAIL did. It induced complete cell death in Colo205 through only one receptor when the other one was blocked, different from TRAIL-induced cell death (through DR4 dominantly). TGF3L-TRAIL cytotoxicity was not reduced in some cell lines even if both receptors are blocked simultaneously. Surprisingly, TGF3L-TRAIL self-assembled into stable polymers, which was responsible for its enhanced cytotoxicity. In human tumor xenograft mouse models, TGF3L-TRAIL showed anti-tumor activity similar to or better than TRAIL in different cancer cell types, consistent with its differing enhancement of cytotoxicity in vitro. Taken together, TGF3L fusion of TRAIL obviously enhances the anticancer activity of TRAIL by promoting assembly into polymers, which presents a novel fusion strategy for improving TRAIL function.

Antibodies and Derivatives Targeting DR4 and DR5 for Cancer Therapy

Developing therapeutics that induce apoptosis in cancer cells has become an increasingly attractive approach for the past 30 years. The discovery of tumor necrosis factor (TNF) superfamily members and more specifically TNF-related apoptosis-inducing ligand (TRAIL), the only cytokine of the family capable of eradicating selectively cancer cells, led to the development of numerous TRAIL derivatives targeting death receptor 4 (DR4) and death receptor 5 (DR5) for cancer therapy. With a few exceptions, preliminary attempts to use recombinant TRAIL, agonistic antibodies, or derivatives to target TRAIL agonist receptors in the clinic have been fairly disappointing. Nonetheless, a tremendous effort, worldwide, is being put into the development of novel strategic options to target TRAIL receptors. Antibodies and derivatives allow for the design of novel and efficient agonists. We summarize and discuss here the advantages and drawbacks of the soar of TRAIL therapeutics, from the first developments to the next generation of agonistic products, with a particular insight on new concepts.