Targeting the Activin Receptor Signaling to Counteract the Multi-Systemic Complications of Cancer and Its Treatments

Structure-bioactivity relationship study on anticancer Pd and Pt complexes with aliphatic glycine derivative ligands

To investigate the structure and bioactivity relationship, six Pd(II)/Pt(II) complexes with N-isobutylglycine (L1) and cyclohexylglycine (L2) as N^O amino acid bidentate ligands, 1,10'-phenanthroline (phen) and 2,2'-bipyridine (bipy) as N^N donor ligands, and [Pd(L1)(bipy)]NO3 (1), [Pd(L2)(bipy)]NO3 (2), [Pd(L1)(phen)]NO3 (3), [Pd(L2)(phen)]NO3·2H2O (4), [Pt(L1)(phen)]NO3 (5), along with [Pt(L2)(phen)]NO3 (6) were prepared and then characterized. The geometry of each compound was validated by doing a DFT calculation. Furthermore, tests were conducted on the complexes' water solubilities and lipophilicity. All bipy complexes had superior aqueous solubility and less lipophilicity in comparison with phen complexes, as well as complexes containing cyclohexyl-glycine compared to isobutyl-glycine complexes, probably because of the steric effects and polarity of cyclohexylglycine. The in-vitro anticancer activities of these compounds were examined against HCT116, A549, and MCF7 cancerous cell lines. Data revealed that all Pd/Pt complexes demonstrate higher anticancer activity than carboplatin, and complexes 3 and 4 are more cytotoxic than cisplatin against the HCT116 cell line, particularly against MCF7 cancerous cells. In addition, among all compounds, complex 4 has more anticancer ability than oxaliplatin. Due to different solubility and lipophilicity behavior, the accumulation of Pt complexes and clinical Pt drugs in each cancerous cell was investigated. The binding capabilities of these complexes to DNA, as the main target in chemotherapy, occur through minor grooves and intercalate into DNA, which was done using absorption, fluorescence, and circular dichroism spectroscopy. Finally, the docking simulation study showed the mode of DNA bindings is in good agreement with the spectral binding data.

KLF10: a point of convergence in cancer cachexia

PURPOSE OF THE REVIEW

Cancer-associated cachexia is a wasting syndrome entailing loss in body mass and a shortened life expectancy. There is currently no effective treatment to abrogate this syndrome, which leads to 20-30% of deaths in patients with cancer. While there have been advancements in defining signaling factors/pathways in cancer-induced muscle wasting, targeting the same in the clinic has not been as successful. Krüppel-like factor 10 (KLF10), a transcription factor implicated in muscle regulation, is regulated by the transforming growth factor-beta signaling pathway. This review proposes KLF10 as a potential convergence point of diverse signaling pathways involved in muscle wasting.

RECENT FINDINGS

KLF10 was discovered as a target of transforming growth factor-beta decades ago but more recently it has been shown that deletion of KLF10 rescues cancer-induced muscle wasting. Moreover, KLF10 has also been shown to bind key atrophy genes associated with muscle atrophy in vitro .

SUMMARY

There is an elevated need to explore targets in cachexia, which will successfully translate into the clinic. Investigating a convergence point downstream of multiple signaling pathways might hold promise in developing effective therapies for cachexia.

Activin receptors in human cancer: Functions, mechanisms, and potential clinical applications

Activins are members of the transforming growth factor-β (TGF-β) superfamily and act as key regulators in various physiological processes, such as follicle and embryonic development, as well as in multiple human diseases, including cancer. They have been established to signal through three type I and two type II serine/threonine kinase receptors, which, upon ligand binding, form a final signal-transducing receptor complex that activates downstream signaling and governs gene expression. Recent research highlighted the dysregulation of the expression or activity of activin receptors in multiple human cancers and their critical involvement in cancer progression. Furthermore, expression levels of activin receptors have been associated with clinicopathological features and patient outcomes across different cancers. However, there is currently a paucity of comprehensive systematic reviews of activin receptors in cancer. Thus, this review aimed to consolidate existing knowledge concerning activin receptors, with a primary emphasis on their signaling cascade and emerging biological functions, regulatory mechanisms, and potential clinical applications in human cancers in order to provide novel perspectives on cancer prognosis and targeted therapy.

The Reign of Follistatin in Tumors and Their Microenvironment: Implications for Drug Resistance

Follistatin (FST) is a potent neutralizer of the transforming growth factor-β superfamily and is associated with normal cellular programs and various hallmarks of cancer, such as proliferation, migration, angiogenesis, and immune evasion. The aberrant expression of FST by solid tumors is a well-documented observation, yet how FST influences tumor progression and therapy response remains unclear. The recent surge in omics data has revealed new insights into the molecular foundation underpinning tumor heterogeneity and its microenvironment, offering novel precision medicine-based opportunities to combat cancer. In this review, we discuss these recent FST-centric studies, thereby offering an updated perspective on the protean role of FST isoforms in shaping the complex cellular ecosystem of tumors and in mediating drug resistance.

Inactivating the Uninhibited: The Tale of Activins and Inhibins in Pulmonary Arterial Hypertension

Advances in technology and biomedical knowledge have led to the effective diagnosis and treatment of an increasing number of rare diseases. Pulmonary arterial hypertension (PAH) is a rare disorder of the pulmonary vasculature that is associated with high mortality and morbidity rates. Although significant progress has been made in understanding PAH and its diagnosis and treatment, numerous unanswered questions remain regarding pulmonary vascular remodeling, a major factor contributing to the increase in pulmonary arterial pressure. Here, we discuss the role of activins and inhibins, both of which belong to the TGF-β superfamily, in PAH development. We examine how these relate to signaling pathways implicated in PAH pathogenesis. Furthermore, we discuss how activin/inhibin-targeting drugs, particularly sotatercep, affect pathophysiology, as these target the afore-mentioned specific pathway. We highlight activin/inhibin signaling as a critical mediator of PAH development that is to be targeted for therapeutic gain, potentially improving patient outcomes in the future.

The Roles of MicroRNA in Pancreatic Cancer Progression

Pancreatic Ductal Adenocarcinoma (PDAC) has a poor patient survival rate in comparison with other cancer types, even after targeted therapy, chemotherapy, and immunotherapy. Therefore, a great deal needs to be done to gain a better understanding of the biology and identification of prognostic and predictive markers for the development of superior therapies. The microRNAs (miRNAs) belong to small non-coding RNAs that regulate post-transcriptional gene expression. Several shreds of evidence indicate that miRNAs play an important role in the pathogenesis of pancreatic cancer. Here we review the recent developments in miRNAs and their target role in the development, metastasis, migration, and invasion.

Transforming Growth Factor-Beta Signaling in Cancer-Induced Cachexia: From Molecular Pathways to the Clinics

Cachexia is a metabolic syndrome consisting of massive loss of muscle mass and function that has a severe impact on the quality of life and survival of cancer patients. Up to 20% of lung cancer patients and up to 80% of pancreatic cancer patients are diagnosed with cachexia, leading to death in 20% of them. The main drivers of cachexia are cytokines such as interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), macrophage inhibitory cytokine 1 (MIC-1/GDF15) and transforming growth factor-beta (TGF-β). Besides its double-edged role as a tumor suppressor and activator, TGF-β causes muscle loss through myostatin-based signaling, involved in the reduction in protein synthesis and enhanced protein degradation. Additionally, TGF-β induces inhibin and activin, causing weight loss and muscle depletion, while MIC-1/GDF15, a member of the TGF-β superfamily, leads to anorexia and so, indirectly, to muscle wasting, acting on the hypothalamus center. Against this background, the blockade of TGF-β is tested as a potential mechanism to revert cachexia, and antibodies against TGF-β reduced weight and muscle loss in murine models of pancreatic cancer. This article reviews the role of the TGF-β pathway and to a minor extent of other molecules including microRNA in cancer onset and progression with a special focus on their involvement in cachexia, to enlighten whether TGF-β and such other players could be potential targets for therapy.

Blocking ActRIIB and restoring appetite reverses cachexia and improves survival in mice with lung cancer

Cancer cachexia is a common, debilitating condition with limited therapeutic options. Using an established mouse model of lung cancer, we find that cachexia is characterized by reduced food intake, spontaneous activity, and energy expenditure accompanied by muscle metabolic dysfunction and atrophy. We identify Activin A as a purported driver of cachexia and treat with ActRIIB-Fc, a decoy ligand for TGF-β/activin family members, together with anamorelin (Ana), a ghrelin receptor agonist, to reverse muscle dysfunction and anorexia, respectively. Ana effectively increases food intake but only the combination of drugs increases lean mass, restores spontaneous activity, and improves overall survival. These beneficial effects are limited to female mice and are dependent on ovarian function. In agreement, high expression of Activin A in human lung adenocarcinoma correlates with unfavorable prognosis only in female patients, despite similar expression levels in both sexes. This study suggests that multimodal, sex-specific, therapies are needed to reverse cachexia.

Myostatin and its Regulation: A Comprehensive Review of Myostatin Inhibiting Strategies

Myostatin (MSTN) is a well-reported negative regulator of muscle growth and a member of the transforming growth factor (TGF) family. MSTN has important functions in skeletal muscle (SM), and its crucial involvement in several disorders has made it an important therapeutic target. Several strategies based on the use of natural compounds to inhibitory peptides are being used to inhibit the activity of MSTN. This review delivers an overview of the current state of knowledge about SM and myogenesis with particular emphasis on the structural characteristics and regulatory functions of MSTN during myogenesis and its involvements in various muscle related disorders. In addition, we review the diverse approaches used to inhibit the activity of MSTN, especially in silico approaches to the screening of natural compounds and the design of novel short peptides derived from proteins that typically interact with MSTN.

Activin-A impairs CD8 T cell-mediated immunity and immune checkpoint therapy response in melanoma

Background

Activin-A, a transforming growth factor β family member, is secreted by many cancer types and is often associated with poor disease prognosis. Previous studies have shown that Activin-A expression can promote cancer progression and reduce the intratumoral frequency of cytotoxic T cells. However, the underlying mechanisms and the significance of Activin-A expression for cancer therapies are unclear.

Methods

We analyzed the expression of the Activin-A encoding gene INHBA in melanoma patients and the influence of its gain- or loss-of-function on the immune infiltration and growth of BRAF-driven YUMM3.3 and iBIP2 mouse melanoma grafts and in B16 models. Using antibody depletion strategies, we investigated the dependence of Activin-A tumor-promoting effect on different immune cells. Immune-regulatory effects of Activin-A were further characterized in vitro and by an adoptive transfer of T cells. Finally, we assessed INHBA expression in melanoma patients who received immune checkpoint therapy and tested whether it impairs the response in preclinical models.

Results

We show that Activin-A secretion by melanoma cells inhibits adaptive antitumor immunity irrespective of BRAF status by inhibiting CD8⁺ T cell infiltration indirectly and even independently of CD4 T cells, at least in part by attenuating the production of CXCL9/10 by myeloid cells. In addition, we show that Activin-A/INHBA expression correlates with anti-PD1 therapy resistance in melanoma patients and impairs the response to dual anti-cytotoxic T-Lymphocyte associated protein 4/anti-PD1 treatment in preclinical models.

Conclusions

Our findings suggest that strategies interfering with Activin-A induced immune-regulation offer new therapeutic opportunities to overcome CD8 T cell exclusion and immunotherapy resistance.

Emerging signaling mediators in the anorexia-cachexia syndrome of cancer

The cachexia syndrome in cancer is characterized by weight loss resulting from the combination of anorexia and atrophy of adipose and skeletal muscle. For decades, inflammatory circulatory factors have been identified to regulate wasting, but inhibitors of these factors have not yielded the same clinical benefit as in animal models. Therefore, additional mediators of cachexia likely regulate this syndrome, and such factors might be more suitable for targeted intervention. We highlight several anorexia-cachexia signaling mediators, including activin A, myostatin, GDF15, and lipocalin-2. We discuss current evidence that these factors associate with cachexia in cancer patients, and summarize translational efforts including essential early-phase clinical trials. We conclude with thoughts on targeted and personalized approaches for future anti-cachexia treatments.

Cardiac Cachexia: Unaddressed Aspect in Cancer Patients

Tumor-derived cachectic factors such as proinflammatory cytokines and neuromodulators not only affect skeletal muscle but also affect other organs, including the heart, in the form of cardiac muscle atrophy, fibrosis, and eventual cardiac dysfunction, resulting in poor quality of life and reduced survival. This article reviews the holistic approaches of existing diagnostic, pathophysiological, and multimodal therapeutic interventions targeting the molecular mechanisms that are responsible for cancer-induced cardiac cachexia. The major drivers of cardiac muscle wasting in cancer patients are autophagy activation by the cytokine-NFkB, TGF β-SMAD³, and angiotensin II-SOCE-STIM-Ca²⁺ pathways. A lack of diagnostic markers and standard treatment protocols hinder the early diagnosis of cardiac dysfunction and the initiation of preventive measures. However, some novel therapeutic strategies, including the use of Withaferin A, have shown promising results in experimental models, but Withaferin A’s effectiveness in human remains to be verified. The combined efforts of cardiologists and oncologists would help to identify cost effective and feasible solutions to restore cardiac function and to increase the survival potential of cancer patients.

Chemotherapy-Induced Myopathy: The Dark Side of the Cachexia Sphere

Simple Summary

In addition to cancer-related factors, anti-cancer chemotherapy treatment can drive life-threatening body wasting in a syndrome known as cachexia. Emerging evidence has described the impact of several key chemotherapeutic agents on skeletal muscle in particular, and the mechanisms are gradually being unravelled. Despite this evidence, there remains very little research regarding therapeutic strategies to protect muscle during anti-cancer treatment and current global grand challenges focused on deciphering the cachexia conundrum fail to consider this aspect—chemotherapy-induced myopathy remains very much on the dark side of the cachexia sphere. This review explores the impact and mechanisms of, and current investigative strategies to protect against, chemotherapy-induced myopathy to illuminate this serious issue.

Abstract

Cancer cachexia is a debilitating multi-factorial wasting syndrome characterised by severe skeletal muscle wasting and dysfunction (i.e., myopathy). In the oncology setting, cachexia arises from synergistic insults from both cancer–host interactions and chemotherapy-related toxicity. The majority of studies have surrounded the cancer–host interaction side of cancer cachexia, often overlooking the capability of chemotherapy to induce cachectic myopathy. Accumulating evidence in experimental models of cachexia suggests that some chemotherapeutic agents rapidly induce cachectic myopathy, although the underlying mechanisms responsible vary between agents. Importantly, we highlight the capacity of specific chemotherapeutic agents to induce cachectic myopathy, as not all chemotherapies have been evaluated for cachexia-inducing properties—alone or in clinically compatible regimens. Furthermore, we discuss the experimental evidence surrounding therapeutic strategies that have been evaluated in chemotherapy-induced cachexia models, with particular focus on exercise interventions and adjuvant therapeutic candidates targeted at the mitochondria.

Cancer cachexia: molecular mechanism and pharmacological management

Cancer cachexia often occurs in malignant tumors and is a multifactorial and complex symptom characterized by wasting of skeletal muscle and adipose tissue, resulting in weight loss, poor life quality and shorter survival. The pathogenic mechanism of cancer cachexia is complex, involving a variety of molecular substrates and signal pathways. Advancements in understanding the molecular mechanisms of cancer cachexia have provided a platform for the development of new targeted therapies. Although recent outcomes of early-phase trials have showed that several drugs presented an ideal curative effect, monotherapy cannot be entirely satisfactory in the treatment of cachexia-associated symptoms due to its complex and multifactorial pathogenesis. Therefore, the lack of definitive therapeutic strategies for cancer cachexia emphasizes the need to develop a better understanding of the underlying mechanisms. Increasing evidences show that the progression of cachexia is associated with metabolic alternations, which mainly include excessive energy expenditure, increased proteolysis and mitochondrial dysfunction. In this review, we provided an overview of the key mechanisms of cancer cachexia, with a major focus on muscle atrophy, adipose tissue wasting, anorexia and fatigue and updated the latest progress of pharmacological management of cancer cachexia, thereby further advancing the interventions that can counteract cancer cachexia.