Therapeutic targeting of TRAIL death receptors

Targeting apoptotic pathways for cancer therapy

Apoptosis is a form of programmed cell death that is mediated by intrinsic and extrinsic pathways. Dysregulation of and resistance to cell death are hallmarks of cancer. For over three decades, the development of therapies to promote treatment of cancer by inducing various cell death modalities, including apoptosis, has been a main goal of clinical oncology. Apoptosis pathways also interact with other signaling mechanisms, such as the p53 signaling pathway and the integrated stress response (ISR) pathway. In addition to agents directly targeting the intrinsic and extrinsic pathway components, anticancer drugs that target the p53 and ISR signaling pathways are actively being developed. In this Review, we discuss selected and promising anticancer therapies in various stages of development, including drug targets, mechanisms, and resistance to related treatments, focusing especially on B cell lymphoma 2 (BCL-2) inhibitors, TRAIL analogues, DR5 antibodies, and strategies that target p53, mutant p53, and the ISR.

Unveiling the potential of FOXO3 in lung cancer: From molecular insights to therapeutic prospects

Lung cancer poses a significant challenge regarding molecular heterogeneity, as it encompasses a wide range of molecular alterations and cancer-related pathways. Recent discoveries made it feasible to thoroughly investigate the molecular mechanisms underlying lung cancer, giving rise to the possibility of novel therapeutic strategies relying on molecularly targeted drugs. In this context, forkhead box O3 (FOXO3), a member of forkhead transcription factors, has emerged as a crucial protein commonly dysregulated in cancer cells. The regulation of the FOXO3 in reacting to external stimuli plays a key role in maintaining cellular homeostasis as a component of the molecular machinery that determines whether cells will survive or dies. Indeed, various extrinsic cues regulate FOXO3, affecting its subcellular location and transcriptional activity. These regulations are mediated by diverse signaling pathways, non-coding RNAs (ncRNAs), and protein interactions that eventually drive post-transcriptional modification of FOXO3. Nevertheless, while it is no doubt that FOXO3 is implicated in numerous aspects of lung cancer, it is unclear whether they act as tumor suppressors, promotors, or both based on the situation. However, FOXO3 serves as an intriguing possible target in lung cancer therapeutics while widely used anti-cancer chemo drugs can regulate it. In this review, we describe a summary of recent findings on molecular mechanisms of FOXO3 to clarify that targeting its activity might hold promise in lung cancer treatment.

Circulating cytokines and vascular dementia: A bi-directional Mendelian randomization study

Inflammatory responses are associated with the development of vascular dementia (VaD). Circulating cytokines modulate the inflammatory response and are important for the immune system. To further elucidate the role of the immune system in VaD, we used Mendelian randomization (MR) to comprehensively and bi-directionally assess the role of circulating cytokines in VaD. Using state-of-the-art genome-wide association studies, we primarily assessed whether different genetic levels of 41 circulating cytokines affect the risk of developing VaD and, in turn, whether the genetic risk of VaD affects these circulating cytokines. We used inverse variance weighting (IVW) and several other MR methods to assess the bidirectional causality between circulating cytokines and VaD, and performed sensitivity analyses. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) was inversely associated with VaD risk [odds ratio (OR): 0.74, 95 % confidence interval (CI): 0.60-0.92, P = 0.007, 0.007]. VaD was associated with seven circulating cytokines: macrophage inflammatory protein 1b (MIP-1 beta) [OR: 1.05, 95 % CI: 1.01-1.08, P = 0.009], Interleukin-12p70 (IL-12) [OR: 1.04, 95 % CI: 1.00-1.08, P = 0.047], Interleukin-17 (IL-17) [OR: 1.04, 95 % CI: 1.00-1.07, P = 0.038], Interleukin-7 (IL-7) [OR: 1.07, 95 % CI: 1.02-1.12, P = 0.009], Interferon gamma (IFN-γ) [OR: 1.03, 95 % CI: 1.00-1.07, P = 0.046], Granulocyte-colony stimulating factor (GCSF) [OR: 1.06, 95 % CI: 1.02-1.09, P = 0.001], Fibroblast growth factor (FGF) [P = 0.001], and Fibroblast growth factor (FGF) [P = 0.001]. Fibroblast growth factor basic (FGF-Basic) [OR: 1.04, 95 % CI: 1.01-1.08, P = 0.02] were positively correlated. Circulating cytokines are associated with VaD, and further studies are needed to determine whether they are effective targets for intervention to prevent or treat VaD.

TNF-Related Apoptosis-Inducing Ligand: Non-Apoptotic Signalling

TNF-related apoptosis-inducing ligand (TRAIL or Apo2 or TNFSF10) belongs to the TNF superfamily. When bound to its agonistic receptors, TRAIL can induce apoptosis in tumour cells, while sparing healthy cells. Over the last three decades, this tumour selectivity has prompted many studies aiming at evaluating the anti-tumoral potential of TRAIL or its derivatives. Although most of these attempts have failed, so far, novel formulations are still being evaluated. However, emerging evidence indicates that TRAIL can also trigger a non-canonical signal transduction pathway that is likely to be detrimental for its use in oncology. Likewise, an increasing number of studies suggest that in some circumstances TRAIL can induce, via Death receptor 5 (DR5), tumour cell motility, potentially leading to and contributing to tumour metastasis. While the pro-apoptotic signal transduction machinery of TRAIL is well known from a mechanistic point of view, that of the non-canonical pathway is less understood. In this study, we the current state of knowledge of TRAIL non-canonical signalling.

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.

Studying Signaling Pathway Activation in TRAIL-Resistant Macrophage-Like Acute Myeloid Leukemia Cells

Acute myeloid leukemia (AML) is a malignant neoplasm characterized by extremely low curability and survival. The inflammatory microenvironment and maturation (differentiation) of AML cells induced by it contribute to the evasion of these cells from effectors of antitumor immunity. One of the key molecular effectors of immune surveillance, the cytokine TRAIL, is considered a promising platform for developing selective anticancer drugs. Previously, under in vitro conditions of the inflammatory microenvironment (a three-dimensional high-density culture of THP-1 AML cells), we demonstrated the emergence of differentiated macrophage-like THP-1ad clones resistant to TRAIL-induced death. In the present study, constitutive activation of proinflammatory signaling pathways, associated transcription factors, and increased expression of the anti-apoptotic BIRC3 gene were observed in TRAIL-resistant macrophage-like THP-1ad AML cells. For the first time, a bioinformatic analysis of the transcriptome revealed the main regulator, the IL1B gene, which triggers proinflammatory activation and induces resistance to TRAIL in THP-1ad macrophage-like cells.

The role of the immune response and inflammatory pathways in TNF-related apoptosis-inducing ligand (TRAIL) resistance in triple-negative breast cancer cells

Triple-negative breast cancer (TNBC) is an aggressive form of breast cancer, and the majority of TNBC lacks targeted therapies. Previous studies have shown that TNBC cells are highly sensitive to TNF-related apoptosis-inducing ligand (TRAIL), making it a potentially viable treatment option for TNBC. However, the development of TRAIL resistance limits its potential for clinical use, and the underlying mechanisms are not fully understood. To better understand the mechanism of resistance to TRAIL, we performed RNA sequencing to identify the candidates that are responsible for resistance to TRAIL in two previously established TRAIL-resistant MDA231 and SUM159 cells. This approach led us to identify differentially expressed genes (DEGs) and pathways in TRAIL-resistant MDA231 and SUM159 cells compared to their TRAIL-sensitive counterparts. We showed that several DEGs and pathways were associated with inflammation in TRAIL-resistant cells, including IL-1α and IL6. By downregulating IL-1α and IL6 expression, we showed that TRAIL sensitivity can be significantly restored in TRAIL-resistant cells. Therefore, this study identifies a mechanism by which the inflammation pathway promotes TRAIL resistance, which could be targeted for enhancing TRAIL-based therapies in TNBC cells.

TRAIL and its receptors in cardiac diseases

Cardiovascular disease is a leading cause of death worldwide. Loss of cardiomyocytes that occurs during many types of damage to the heart such as ischemic injury and stress caused by pressure overload, diminishes cardiac function due to their limited regenerative capacity and promotes remodeling, which further damages the heart. Cardiomyocyte death occurs through two primary mechanisms, necrosis and apoptosis. Apoptosis is a highly regulated form of cell death that can occur through intrinsic (mitochondrial) or extrinsic (receptor mediated) pathways. Extrinsic apoptosis occurs through a subset of Tumor Necrosis Receptor (TNF) family receptors termed "Death Receptors." While some ligands for death receptors have been extensively studied in the heart, such as TNF-α, others have been virtually unstudied. One poorly characterized cardiac TNF related ligand is TNF-Related Apoptosis Inducing Ligand (TRAIL). TRAIL binds to two apoptosis-inducing receptors, Death Receptor (DR) 4 and DR5. There are also three decoy TRAIL receptors, Decoy Receptor (DcR) 1, DcR2 and osteoprotegerin (OPG). While TRAIL has been extensively studied in the cancer field due to its ability to selectively induce apoptosis in transformed cell types, emerging clinical evidence points towards a role for TRAIL and its receptors in cardiac pathology. This article will highlight our current understanding of TRAIL and its receptors in normal and pathological conditions in the heart.

The Role of TRAIL in Apoptosis and Immunosurveillance in Cancer

Tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) is a member of the TNF superfamily that selectively induces apoptosis in tumor cells without harming normal cells, making it an attractive agent for cancer therapy. TRAIL induces apoptosis by binding to and activating its death receptors DR4 and DR5. Several TRAIL-based treatments have been developed, including recombinant forms of TRAIL and its death receptor agonist antibodies, but the efficacy of TRAIL-based therapies in clinical trials is modest. In addition to inducing cancer cell apoptosis, TRAIL is expressed in immune cells and plays a critical role in tumor surveillance. Emerging evidence indicates that the TRAIL pathway may interact with immune checkpoint proteins, including programmed death-ligand 1 (PD-L1), to modulate PD-L1-based tumor immunotherapies. Therefore, understanding the interaction between TRAIL and the immune checkpoint PD-L1 will lead to the development of new strategies to improve TRAIL- and PD-L1-based therapies. This review discusses recent findings on TRAIL-based therapy, resistance, and its involvement in tumor immunosurveillance.

Anticancer genes (NOXA, PAR-4, TRAIL) are de-regulated in breast cancer patients and can be targeted by using a ribosomal inactivating plant protein (riproximin)

BACKGROUND

Anticancer genes are an endogenous defense against transformed cells as they impose antineoplastic effects upon ectopic expression. Profiling the expression of these genes is fundamental for exploring their prognostic and therapeutic relevance in cancers. Natural compounds can upregulate anticancer genes in malignant cells and thus be useful for therapeutic purposes. In this study, we identified the expression levels of anticancer genes in breast cancer clinical isolates. In addition, the purified and sequenced plant protein (riproximin) was evaluated for its potential to induce anticancer genes in two breast cancer cell lines.

METHODOLOGY

Expression profiles of three anticancer genes (NOXA, PAR-4, TRAIL) were identified by immunohistochemistry in 45 breast cancer clinical isolates. Breast cancer cells were exposed to riproximin and expression of the anticancer genes was determined by microarray, real-time PCR and western blot methodologies. Lastly, a bioinformatic approach was adopted to highlight the molecular/functional significance of the anticancer genes.

RESULTS

NOXA expression was evenly de-regulated among the clinical isolates, while PAR-4 was significantly down-regulated in majority of the breast cancer tissues. In contrast, TRAIL expression was increased in most of the clinical samples. Expression levels of the anticancer genes followed a distinct trend in accordance with the disease severity. Riproximin showed a substantial potential of inducing expression of the anticancer genes in breast cancer cells at transcriptomic and protein levels. The bioinformatic approach revealed involvement of anticancer genes in multiple cellular functions and signaling cascades.

CONCLUSION

Anticancer genes were de-regulated and showed discrete expression patterns in breast cancer patient samples. Riproximin effectively induced the expression of selected anticancer genes in breast cancer cells.

Recent Advances in the Development of Nanodelivery Systems Targeting the TRAIL Death Receptor Pathway

The TRAIL (TNF-related apoptosis-inducing ligand) apoptotic pathway is extensively exploited in the development of targeted antitumor therapy due to TRAIL specificity towards its cognate receptors, namely death receptors DR4 and DR5. Although therapies targeting the TRAIL pathway have encountered many obstacles in attempts at clinical implementation for cancer treatment, the unique features of the TRAIL signaling pathway continue to attract the attention of researchers. Special attention is paid to the design of novel nanoscaled delivery systems, primarily aimed at increasing the valency of the ligand for improved death receptor clustering that enhances apoptotic signaling. Optionally, complex nanoformulations can allow the encapsulation of several therapeutic molecules for a combined synergistic effect, for example, chemotherapeutic agents or photosensitizers. Scaffolds for the developed nanodelivery systems are fabricated by a wide range of conventional clinically approved materials and innovative ones, including metals, carbon, lipids, polymers, nanogels, protein nanocages, virus-based nanoparticles, dendrimers, DNA origami nanostructures, and their complex combinations. Most nanotherapeutics targeting the TRAIL pathway are aimed at tumor therapy and theranostics. However, given the wide spectrum of action of TRAIL due to its natural role in immune system homeostasis, other therapeutic areas are also involved, such as liver fibrosis, rheumatoid arthritis, Alzheimer's disease, and inflammatory diseases caused by bacterial infections. This review summarizes the recent innovative developments in the design of nanodelivery systems modified with TRAIL pathway-targeting ligands.