Human pancreatic cancer xenografts recapitulate key aspects of cancer cachexia

Toyaburgine, a Synthetic N-Biphenyl-Dihydroisoquinoline Inspired by Related N,C-Coupled Naphthylisoquinoline Alkaloids, with High In Vivo Efficacy in Preclinical Pancreatic Cancer Models

Pancreatic cancer is a highly aggressive and lethal malignancy, with a 5-year survival rate below 10%. Traditional chemotherapy, including gemcitabine, has limited efficacy due to chemoresistance and a unique tumor microenvironment characterized by hypovascularity and nutrient deprivation. This study reports on the discovery of a new N-biphenyl-dihydroisoquinoline, named toyaburgine (4), inspired by naturally occurring N,C-coupled naphthylisoquinoline alkaloids. Developed through systematic structural optimization, toyaburgine is a potent anticancer agent, showing promise for pancreatic cancer treatment. It exhibits strong antiausterity activity with low nanomolar PC50 values, effectively inhibiting pancreatic cancer cell viability under nutrient-deprived conditions. In vitro, 4 causes significant morphological changes and cancer cell death in MIA PaCa-2 cells while also inhibiting cell migration and colony formation, which indicates its antimetastatic potential. Mechanistically, toyaburgine disrupts the PI3K/Akt/mTOR pathway, essential for pancreatic cancer cell survival in a stressful microenvironment, and inhibits MIA PaCa-2 spheroid formation. In vivo, toyaburgine, alone or combined with gemcitabine, shows effective tumor suppression in subcutaneous xenograft and clinically relevant orthotopic models, where it also reduces cachexia. These results highlight the potential of toyaburgine as a new therapeutic drug for pancreatic cancer. Its combination with gemcitabine presents a promising treatment approach by targeting both proliferating and gemcitabine-resistant cancer cells.

Local Inflammation Precedes Diaphragm Wasting and Fibrotic Remodelling in a Mouse Model of Pancreatic Cancer

BACKGROUND

Cancer cachexia represents a debilitating muscle wasting condition that is highly prevalent in gastrointestinal cancers, including pancreatic ductal adenocarcinoma (PDAC). Cachexia is estimated to contribute to ~30% of cancer-related deaths, with deterioration of respiratory muscles suspected to be a key contributor to cachexia-associated morbidity and mortality. In recent studies, we identified fibrotic remodelling of respiratory accessory muscles as a key feature of human PDAC cachexia.

METHODS

To gain insight into mechanisms driving respiratory muscle wasting and fibrotic remodelling in response to PDAC, we conducted temporal histological and transcriptomic analyses on diaphragm muscles harvested from mice-bearing orthotopic murine pancreatic (KPC) tumours at time points reflective of precachexia (D8 and D10), mild-moderate cachexia (D12 and D14) and advanced cachexia (endpoint).

RESULTS

During the precachexia phase, diaphragms showed significant leukocyte infiltration (+3-fold to +13-fold; D8-endpoint vs. Sham, p < 0.05) and transcriptomic enrichment of inflammatory processes associated with tissue injury that remained increased through endpoint. Diaphragm inflammation was followed by increases in PDGFR-ɑ+ fibroadipogenic progenitors (+2.5 to +3.8-fold; D10-endpoint vs. Sham, p < 0.05), fibre atrophy (-16% to -24%, D12 to endpoint vs. Sham, p < 0.05), ECM expansion (+1.5 to +1.8-fold; D14-endpoint vs. Sham, p < 0.05), collagen accumulation (+3.8-fold; endpoint vs. Sham, p = 0.0013) and reductions in breathing frequency (-55%, p = 0.0074) and diaphragm excursion (-43%, p = 0.0006). These biological processes were supported by changes in the diaphragm transcriptome. Ingenuity pathway analysis predicted factors involved in inflammatory responses to tissue injury, including TGF-β1, angiotensin and PDGF BB, as top upstream regulators activated in diaphragms prior to and throughout cachexia progression, while PGC-1α and the insulin receptor were among the top upstream regulators predicted to be suppressed. The transcriptomic dataset further revealed progressive disturbances to networks involved in lipid, glucose and oxidative metabolism, activation of the unfolded protein response and neuromuscular junction remodelling associated with denervation.

CONCLUSIONS

In summary, our data support leukocyte infiltration and expansion of PDGFRα mesenchymal progenitors as early events that precede wasting and fibrotic remodelling of the diaphragm in response to PDAC that may also underlie metabolic disturbances, weakness and respiratory complications.

Early adipose tissue wasting in a novel preclinical model of human lung cancer cachexia

Cancer cachexia (CC), a syndrome of skeletal muscle and adipose tissue wasting, reduces responsiveness to therapies and increases mortality. There are no approved treatments for CC, which may relate to discordance between pre-clinical models and human CC. To address the need for clinically relevant models, we generated tamoxifen-inducible, epithelial cell specific Kras G12D/+ ( G12D ) mice. G12D mice develop CC over a protracted time course and phenocopy tissue, cellular, mutational, transcriptomic, and metabolic characteristics of human lung CC. CC in G12D mice is characterized by early loss of adipose tissue, a phenotype confirmed in a large cohort of patients with lung cancer. Tumor-released factors promote adipocyte lipolysis, a driver of adipose wasting in human CC, and adipose tissue wasting was inversely related to tumor burden. Thus, G12D mice model key features of human lung CC and suggest a novel role for early adipose tissue wasting in CC.

Defining and Addressing Research Priorities in Cancer Cachexia through Transdisciplinary Collaboration

For many patients, the cancer continuum includes a syndrome known as cancer-associated cachexia (CAC), which encompasses the unintended loss of body weight and muscle mass, and is often associated with fat loss, decreased appetite, lower tolerance and poorer response to treatment, poor quality of life, and reduced survival. Unfortunately, there are no effective therapeutic interventions to completely reverse cancer cachexia and no FDA-approved pharmacologic agents; hence, new approaches are urgently needed. In May of 2022, researchers and clinicians from Moffitt Cancer Center held an inaugural retreat on CAC that aimed to review the state of the science, identify knowledge gaps and research priorities, and foster transdisciplinary collaborative research projects. This review summarizes research priorities that emerged from the retreat, examples of ongoing collaborations, and opportunities to move science forward. The highest priorities identified include the need to (1) evaluate patient-reported outcome (PRO) measures obtained in clinical practice and assess their use in improving CAC-related outcomes; (2) identify biomarkers (imaging, molecular, and/or behavioral) and novel analytic approaches to accurately predict the early onset of CAC and its progression; and (3) develop and test interventions (pharmacologic, nutritional, exercise-based, and through mathematical modeling) to prevent CAC progression and improve associated symptoms and outcomes.

The uncharacterized transcript KIAA0930 confers a cachexic phenotype on cancer cells

Patients with cancer cachexia have a poor prognosis and impaired quality of life. Numerous studies using preclinical models have shown that inflammatory cytokines play an important role in the development of cancer cachexia; however, no clinical trial targeting cytokines has been successful. Therefore, it is essential to identify molecular mechanisms to develop anti-cachexia therapies. Here we identified the uncharacterized transcript KIAA0930 as a candidate cachexic factor based on analyses of microarray datasets and an in vitro muscle atrophy assay. While conditioned media from pancreatic, colorectal, gastric, and tongue cancer cells caused muscle atrophy in vitro, conditioned medium from KIAA0930 knockdown cells did not. The PANC-1 orthotopic xenograft study showed that the tibialis anterior muscle weight and cross-sectional area were increased in mice bearing KIAA0930 knockdown cells compared to control mice. Interestingly, KIAA0930 knockdown did not cause consistent changes in the secretion of inflammatory cytokines/chemokines from a variety of cancer cell lines. An initial characterization experiment showed that KIAA0930 is localized in the cytosol and not secreted from cells. These data suggest that the action of KIAA0930 is independent of the expression of cytokines/chemokines and that KIAA0930 could be a novel therapeutic target for cachexia.

A novel orthotopic mouse model replicates human lung cancer cachexia

INTRODUCTION

Cancer cachexia, highly prevalent in lung cancer, is a debilitating syndrome characterized by involuntary loss of skeletal muscle mass and is associated with poor clinical outcome, decreased survival and negative impact on tumour therapy. Various lung tumour-bearing animal models have been used to explore underlying mechanisms of cancer cachexia. However, these models do not simulate anatomical and immunological features key to lung cancer and associated muscle wasting. Overcoming these shortcomings is essential to translate experimental findings into the clinic. We therefore evaluated whether a syngeneic, orthotopic lung cancer mouse model replicates systemic and muscle-specific alterations associated with human lung cancer cachexia.

METHODS

Immune competent, 11 weeks old male 129S2/Sv mice, were randomly allocated to either (1) sham control group or (2) tumour-bearing group. Syngeneic lung epithelium-derived adenocarcinoma cells (K-rasG12D ; p53R172HΔG ) were inoculated intrapulmonary into the left lung lobe of the mice. Body weight and food intake were measured daily. At baseline and weekly after surgery, grip strength was measured and tumour growth and muscle volume were assessed using micro cone beam CT imaging. After reaching predefined surrogate survival endpoint, animals were euthanized, and skeletal muscles of the lower hind limbs were collected for biochemical analysis.

RESULTS

Two-third of the tumour-bearing mice developed cachexia based on predefined criteria. Final body weight (-13.7 ± 5.7%; P < 0.01), muscle mass (-13.8 ± 8.1%; P < 0.01) and muscle strength (-25.5 ± 10.5%; P < 0.001) were reduced in cachectic mice compared with sham controls and median survival time post-surgery was 33.5 days until humane endpoint. Markers for proteolysis, both ubiquitin proteasome system (Fbxo32 and Trim63) and autophagy-lysosomal pathway (Gabarapl1 and Bnip3), were significantly upregulated, whereas markers for protein synthesis (relative phosphorylation of Akt, S6 and 4E-BP1) were significantly decreased in the skeletal muscle of cachectic mice compared with control. The cachectic mice exhibited increased pentraxin-2 (P < 0.001) and CXCL1/KC (P < 0.01) expression levels in blood plasma and increased mRNA expression of IκBα (P < 0.05) in skeletal muscle, indicative for the presence of systemic inflammation. Strikingly, RNA sequencing, pathway enrichment and miRNA expression analyses of mouse skeletal muscle strongly mirrored alterations observed in muscle biopsies of patients with lung cancer cachexia.

CONCLUSIONS

We developed an orthotopic model of lung cancer cachexia in immune competent mice. Because this model simulates key aspects specific to cachexia in lung cancer patients, it is highly suitable to further investigate the underlying mechanisms of lung cancer cachexia and to test the efficacy of novel intervention strategies.

Effects of Monoamino-Oxidase-A (MAO-A) Inhibition on Skeletal Muscle Inflammation and Wasting through Pancreatic Ductal Adenocarcinoma in Triple Transgenic Mice

Cancer cachexia describes a syndrome of muscle wasting and lipolysis that is still largely untreatable and negatively impacts prognosis, mobility, and healthcare costs. Since upregulation of skeletal muscle monoamine-oxidase-A (MAO-A), a source of reactive oxygen species, may contribute to cachexia, we investigated the effects of the MAO-inhibitor harmine-hydrochloride (HH, intraperitoneal, 8 weeks) on muscle wasting in a triple-transgenic mouse model of pancreatic ductal adenocarcinoma (PDAC) and wild type (WT) mice. Gastrocnemius and soleus muscle cryo-cross-sections were analyzed for fiber type-specific cross-sectional area (CSA), fraction and capillarization using ATPase- and lectin-stainings. Transcripts of pro-apoptotic, -atrophic, and -inflammatory signals were determined by RT-qPCR. Furthermore, we evaluated the integrity of neuromuscular junction (NMJ, pre-/post-synaptic co-staining) and mitochondrial ultrastructure (transmission electron microscopy). MAO-A expression in gastrocnemius muscle was increased with PDAC vs. WT (immunohistochemistry: p < 0.05; Western blot: by trend). PDAC expectedly reduced fiber CSA and upregulated IL-1β in both calf muscles, while MuRF1 expression increased in soleus muscle only. Although IL-1β decreased, HH caused an additional 38.65% (p < 0.001) decrease in gastrocnemius muscle (IIBX) fiber CSA. Moreover, soleus muscle CSA remained unchanged despite the downregulation of E3-ligases FBXO32 (p < 0.05) and MuRF1 (p < 0.01) through HH. Notably, HH significantly decreased the post-synaptic NMJ area (quadriceps muscle) and glutathione levels (gastrocnemius muscle), thereby increasing mitochondrial damage and centronucleation in soleus and gastrocnemius type IIBX fibers. Moreover, although pro-atrophic/-inflammatory signals are reversed, HH unfortunately fails to stop and rather promotes PDAC-related muscle wasting, possibly via denervation or mitochondrial damage. These differential adverse vs. therapeutic effects warrant studies regarding dose-dependent benefits and risks with consideration of other targets of HH, such as the dual-specificity tyrosine phosphorylation regulated kinases 1A and B (DYRK1A/B).

Progressive development of melanoma-induced cachexia differentially impacts organ systems in mice

Cachexia is a systemic wasting syndrome that increases cancer-associated mortality. How cachexia progressively and differentially impacts distinct tissues is largely unknown. Here, we find that the heart and skeletal muscle undergo wasting at early stages and are the tissues transcriptionally most impacted by cachexia. We also identify general and organ-specific transcriptional changes that indicate functional derangement by cachexia even in tissues that do not undergo wasting, such as the brain. Secreted factors constitute a top category of cancer-regulated genes in host tissues, and these changes include upregulation of the angiotensin-converting enzyme (ACE). ACE inhibition with the drug lisinopril improves muscle force and partially impedes cachexia-induced transcriptional changes, although wasting is not prevented, suggesting that cancer-induced host-secreted factors can regulate tissue function during cachexia. Altogether, by defining prevalent and temporal and tissue-specific responses to cachexia, this resource highlights biomarkers and possible targets for general and tissue-tailored anti-cachexia therapies.

Impact of cancer cachexia on respiratory muscle function and the therapeutic potential of exercise

Cancer cachexia is defined as a multi-factorial syndrome characterised by an ongoing loss of skeletal muscle mass and progressive functional impairment, estimated to affect 50-80% of patients and responsible for 20% of cancer deaths. Elevations in the morbidity and mortality rates of cachectic cancer patients has been linked to respiratory failure due to atrophy and dysfunction of the ventilatory muscles. Despite this, there is a distinct scarcity of research investigating the structural and functional condition of the respiratory musculature in cancer, with the majority of studies exclusively focusing on limb muscle. Treatment strategies are largely ineffective in mitigating the cachectic state. It is now widely accepted that an efficacious intervention will likely combine elements of pharmacology, nutrition and exercise. However, of these approaches, exercise has received comparatively little attention. Therefore, it is unlikely to be implemented optimally, whether in isolation or combination. In consideration of these limitations, the current review describes the mechanistic basis of cancer cachexia and subsequently explores the available respiratory- and exercise-focused literature within this context. The molecular basis of cachexia is thoroughly reviewed. The pivotal role of inflammatory mediators is described. Unravelling the mechanisms of exercise-induced support of muscle via antioxidant and anti-inflammatory effects in addition to promoting efficient energy metabolism via increased mitochondrial biogenesis, mitochondrial function and muscle glucose uptake provide avenues for interventional studies. Currently available pre-clinical mouse models including novel transgenic animals provide a platform for the development of multi-modal therapeutic strategies to protect respiratory muscles in people with cancer.

Review of the endocrine organ-like tumor hypothesis of cancer cachexia in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the most fatal types of solid tumors, associated with a high prevalence of cachexia (~80%). PDAC-derived cachexia (PDAC-CC) is a systemic disease involving the complex interplay between the tumor and multiple organs. The endocrine organ-like tumor (EOLT) hypothesis may explain the systemic crosstalk underlying the deleterious homeostatic shifts that occur in PDAC-CC. Several studies have reported a markedly heterogeneous collection of cachectic mediators, signaling mechanisms, and metabolic pathways, including exocrine pancreatic insufficiency, hormonal disturbance, pro-inflammatory cytokine storm, digestive and tumor-derived factors, and PDAC progression. The complexities of PDAC-CC necessitate a careful review of recent literature summarizing cachectic mediators, corresponding metabolic functions, and the collateral impacts on wasting organs. The EOLT hypothesis suggests that metabolites, genetic instability, and epigenetic changes (microRNAs) are involved in cachexia development. Both tumors and host tissues can secrete multiple cachectic factors (beyond only inflammatory mediators). Some regulatory molecules, metabolites, and microRNAs are tissue-specific, resulting in insufficient energy production to support tumor/cachexia development. Due to these complexities, changes in a single factor can trigger bi-directional feedback circuits that exacerbate PDAC and result in the development of irreversible cachexia. We provide an integrated review based on 267 papers and 20 clinical trials from PubMed and ClinicalTrials.gov database proposed under the EOLT hypothesis that may provide a fundamental understanding of cachexia development and response to current treatments.

Patient-Derived Pancreatic Cancer Cells Induce C2C12 Myotube Atrophy by Releasing Hsp70 and Hsp90

Pancreatic cancer (PC) patients are highly prone to cachexia, a lethal wasting syndrome featuring muscle wasting with an undefined etiology. Recent data indicate that certain murine cancer cells induce muscle wasting by releasing Hsp70 and Hsp90 through extracellular vesicles (EVs) to activate p38β MAPK-mediated catabolic pathways primarily through Toll-like receptor 4 (TLR4). However, whether human PC induces cachexia through releasing Hsp70 and Hsp90 is undetermined. Here, we investigated whether patient-derived PC cells induce muscle cell atrophy directly through this mechanism. We compared cancer cells isolated from patient-derived xenografts (PDX) from three PC patients who had cachexia (PCC) with those of three early-stage lung cancer patients without cachexia (LCC) and two renal cancer patients who were not prone to cachexia (RCC). We observed small increases of Hsp70 and Hsp90 released by LCC and RCC in comparison to non-cancer control cells (NCC). However, PCC released markedly higher levels of Hsp70 and Hsp90 (~ 6-fold on average) than LCC and RCC. In addition, PCC released similarly increased levels of Hsp70/90-containing EVs. In contrast to RCC and LCC, PCC-conditioned media induced a potent catabolic response in C2C12 myotubes including the activation of p38 MAPK and transcription factor C/EBPβ, upregulation of E3 ligases UBR2 and MAFbx, and increase of autophagy marker LC3-II, resulting in the loss of the myosin heavy chain (MHC ~50%) and myotube diameter (~60%). Importantly, the catabolic response was attenuated by Hsp70- and Hsp90-neutralizing antibodies in a dose-dependent manner. These data suggest that human PC cells release high levels of Hsp70 and Hsp90 that induce muscle atrophy through a direct action on muscle cells.

The myokine Fibcd1 is an endogenous determinant of myofiber size and mitigates cancer-induced myofiber atrophy

Decline in skeletal muscle cell size (myofiber atrophy) is a key feature of cancer-induced wasting (cachexia). In particular, atrophy of the diaphragm, the major muscle responsible for breathing, is an important determinant of cancer-associated mortality. However, therapeutic options are limited. Here, we have used Drosophila transgenic screening to identify muscle-secreted factors (myokines) that act as paracrine regulators of myofiber growth. Subsequent testing in mouse myotubes revealed that mouse Fibcd1 is an evolutionary-conserved myokine that preserves myofiber size via ERK signaling. Local administration of recombinant Fibcd1 (rFibcd1) ameliorates cachexia-induced myofiber atrophy in the diaphragm of mice bearing patient-derived melanoma xenografts and LLC carcinomas. Moreover, rFibcd1 impedes cachexia-associated transcriptional changes in the diaphragm. Fibcd1-induced signaling appears to be muscle selective because rFibcd1 increases ERK activity in myotubes but not in several cancer cell lines tested. We propose that rFibcd1 may help reinstate myofiber size in the diaphragm of patients with cancer cachexia.

Human pancreatic tumour organoid-derived factors enhance myogenic differentiation

BACKGROUND

Most patients with pancreatic cancer develop cachexia, which is characterized by progressive muscle loss. The mechanisms underlying muscle loss in cancer cachexia remain elusive. Pancreatic tumour organoids are 3D cell culture models that retain key characteristics of the parent tumour. We aimed to investigate the effect of pancreatic tumour organoid-derived factors on processes that determine skeletal muscle mass, including the regulation of muscle protein turnover and myogenesis.

METHODS

Conditioned medium (CM) was collected from human pancreatic cancer cell lines (PK-45H, PANC-1, PK-1, and KLM-1), pancreatic tumour organoid cultures from a severely cachectic (PANCO-9a) and a non-cachectic patient (PANCO-12a), and a normal pancreas organoid culture. Differentiating C2C12 myoblasts and mature C2C12 myotubes were exposed to CM for 24 h or maintained in control medium. In myotubes, NF-kB activation was monitored using a NF-κB luciferase reporter construct, and mRNA expression of E3-ubiquitin ligases and REDD1 was analysed by RT-qPCR. C2C12 myoblast proliferation and differentiation were monitored by live cell imaging and myogenic markers and myosin heavy chain (MyHC) isoforms were assessed by RT-qPCR.

RESULTS

Whereas CM from PK-1 and KLM-1 cells significantly induced NF-κB activation in C2C12 myotubes (PK-1: 3.1-fold, P < 0.001; KLM-1: 2.1-fold, P = 0.01), Atrogin-1/MAFbx and MuRF1 mRNA were only minimally and inconsistently upregulated by the CM of pancreatic cancer cell lines. Similarly, E3-ubiquitin ligases and REDD1 mRNA expression in myotubes were not altered by exposure to pancreatic tumour organoid CM. Compared with the control condition, CM from both PANCO-9a and PANCO-12a tumour organoids increased proliferation of myoblasts, which was accompanied by significant downregulation of the satellite cell marker paired-box 7 (PAX7) (PANCO-9a: -2.1-fold, P < 0.001; PANCO-12a: -2.0-fold, P < 0.001) and myogenic factor 5 (MYF5) (PANCO-9a: -2.1-fold, P < 0.001; PANCO-12a: -1.8-fold, P < 0.001) after 48 h of differentiation. Live cell imaging revealed accelerated alignment and fusion of myoblasts exposed to CM from PANCO-9a and PANCO-12a, which was in line with significantly increased Myomaker mRNA expression levels (PANCO-9a: 2.4-fold, P = 0.001; PANCO-12a: 2.2-fold, P = 0.004). These morphological and transcriptional alterations were accompanied by increased expression of muscle differentiation markers such as MyHC-IIB (PANCO-9a: 2.5-fold, P = 0.04; PANCO-12a: 3.1-fold, P = 0.006). Although the impact of organoid CM on myogenesis was not associated with the cachexia phenotype of the donor patients, it was specific for tumour organoids, as CM of control pancreas organoids did not modulate myogenic fusion.

CONCLUSIONS

These data show that pancreatic tumour organoid-derived factors alter the kinetics of myogenesis, which may eventually contribute to impaired muscle mass maintenance in cancer cachexia.

Pancreatic cancer cachexia: three dimensions of a complex syndrome

Cancer cachexia is a multifactorial syndrome that is characterised by a loss of skeletal muscle mass, is commonly associated with adipose tissue wasting and malaise, and responds poorly to therapeutic interventions. Although cachexia can affect patients who are severely ill with various malignant or non-malignant conditions, it is particularly common among patients with pancreatic cancer. Pancreatic cancer often leads to the development of cachexia through a combination of distinct factors, which, together, explain its high prevalence and clinical importance in this disease: systemic factors, including metabolic changes and pathogenic signals related to the tumour biology of pancreatic adenocarcinoma; factors resulting from the disruption of the digestive and endocrine functions of the pancreas; and factors related to the close anatomical and functional connection of the pancreas with the gut. In this review, we conceptualise the various insights into the mechanisms underlying pancreatic cancer cachexia according to these three dimensions to expose its particular complexity and the challenges that face clinicians in trying to devise therapeutic interventions.

FoxP1 is a transcriptional repressor associated with cancer cachexia that induces skeletal muscle wasting and weakness

BACKGROUND

Skeletal muscle wasting is a devastating consequence of cancer that affects up to 80% of cancer patients and associates with reduced survival. Herein, we investigated the biological significance of Forkhead box P1 (FoxP1), a transcriptional repressor that we demonstrate is up-regulated in skeletal muscle in multiple models of cancer cachexia and in cachectic cancer patients.

METHODS

Inducible, skeletal muscle-specific FoxP1 over-expressing (FoxP1iSkmTg/Tg ) mice were generated through crossing conditional Foxp1a transgenic mice with HSA-MCM mice that express tamoxifen-inducible Cre recombinase under control of the skeletal muscle actin promoter. To determine the requirement of FoxP1 for cancer-induced skeletal muscle wasting, FoxP1-shRNA was packaged and targeted to muscles using AAV9 delivery prior to inoculation of mice with Colon-26 Adenocarcinoma (C26) cells.

RESULTS

Up-regulation of FoxP1 in adult skeletal muscle was sufficient to induce features of cachexia, including 15% reduction in body mass (P < 0.05), and a 16-27% reduction in skeletal muscle mass (P < 0.05) that was characterized by a 20% reduction in muscle fibre cross-sectional area of type IIX/B muscle fibres (P = 0.020). Skeletal muscles from FoxP1iSkmTg/Tg mice also showed significant damage and myopathy characterized by the presence of centrally nucleated myofibres, extracellular matrix expansion, and were 19-26% weaker than controls (P < 0.05). Transcriptomic analysis revealed FoxP1 as a potent transcriptional repressor of skeletal muscle gene expression, with enrichment of pathways related to skeletal muscle structure and function, growth signalling, and cell quality control. Because FoxP1 functions, at least in part, as a transcriptional repressor through its interaction with histone deacetylase proteins, we treated FoxP1iSkmTg/Tg mice with Trichostatin A, and found that this completely prevented the loss of muscle mass (p = 0.007) and fibre atrophy (P < 0.001) in the tibialis anterior. In the context of cancer, FoxP1 knockdown blocked the cancer-induced repression of myocyte enhancer factor 2 (MEF2)-target genes critical to muscle differentiation and repair, improved muscle ultrastructure, and attenuated muscle fibre atrophy by 50% (P < 0.05).

CONCLUSIONS

In summary, we identify FoxP1 as a novel repressor of skeletal muscle gene expression that is increased in cancer cachexia, whose up-regulation is sufficient to induce skeletal muscle wasting and weakness, and required for the normal wasting response to cancer.

Generation and initial characterization of novel tumour organoid models to study human pancreatic cancer-induced cachexia

BACKGROUND

The majority of patients with pancreatic cancer develops cachexia. The mechanisms underlying cancer cachexia development and progression remain elusive, although tumour-derived factors are considered to play a major role. Pancreatic tumour organoids are in vitro three-dimensional organ-like structures that retain many pathophysiological characteristics of the in vivo tumour. We aimed to establish a pancreatic tumour organoid biobank from well-phenotyped cachectic and non-cachectic patients to enable identification of tumour-derived factors driving cancer cachexia.

METHODS

Organoids were generated from tumour tissue of eight pancreatic cancer patients. A comprehensive pre-operative patient assessment of cachexia-related parameters including nutritional status, physical performance, body composition, and inflammation was performed. Tumour-related and cachexia-related characteristics of the organoids were analysed using histological stainings, targeted sequencing, and real-time-quantitative PCR. Cachexia-related factors present in the circulation of the patients and in the tumour organoid secretome were analysed by enzyme-linked immunosorbent assay.

RESULTS

The established human pancreatic tumour organoids presented typical features of malignancy corresponding to the primary tumour (i.e. nuclear enlargement, multiple nucleoli, mitosis, apoptosis, and mutated KRAS and/or TP53). These tumour organoids also expressed variable levels of many known cachexia-related genes including interleukin-6 (IL-6), TNF-α, IL-8, IL-1α, IL-1β, Mcp-1, GDF15, and LIF. mRNA expression of IL-1α and IL-1β was significantly reduced in organoids from cachectic vs. non-cachectic patients (IL-1α: -3.8-fold, P = 0.009, and IL-1β: -4.7-fold, P = 0.004). LIF, IL-8, and GDF15 mRNA expression levels were significantly higher in organoids from cachectic vs. non-cachectic patients (LIF: 1.6-fold, P = 0.003; IL-8: 1.4-fold, P = 0.01; GDF15: 2.3-fold, P < 0.001). In line with the GDF15 and IL-8 mRNA expression levels, tumour organoids from cachectic patients secreted more GDF15 and IL-8 compared with organoids from non-cachectic patients (5.4 vs. 1.5 ng/mL, P = 0.01, and 7.4 vs. 1.3 ng/mL, P = 0.07, respectively).

CONCLUSIONS

This novel human pancreatic tumour organoid biobank provides a valuable tool to increase our understanding of the mechanisms driving cancer cachexia. Our preliminary characterization of the secretome of these organoids supports their application in functional studies including conditioned medium approaches and in vivo transplantation models.

Lymph Node Subcapsular Sinus Microenvironment-On-A-Chip Modeling Shear Flow Relevant to Lymphatic Metastasis and Immune Cell Homing

A lymph node sinus-on-a-chip adhesion microfluidic platform that recapitulates the hydrodynamic microenvironment of the lymph node subcapsular sinus was engineered. This device was used to interrogate the effects of lymph node remodeling on cellular adhesion in fluid flow relevant to lymphatic metastasis. Wall shear stress levels analytically estimated and modeled after quiescent and diseased/inflamed lymph nodes were experimentally recapitulated using a flow-based microfluidic perfusion system to assess the effects of physiological flow fields on human metastatic cancer cell adhesion. Results suggest that both altered fluid flow profiles and presentation of adhesive ligands, which are predicted to manifest within the lymph node subcapsular sinus as a result of inflammation-induced remodeling, and the presence of lymph-borne monocytic cells may synergistically contribute to the dynamic extent of cell adhesion in flow relevant to lymph node invasion by cancer and monocytic immune cells during lymphatic metastasis.

MEF2c-Dependent Downregulation of Myocilin Mediates Cancer-Induced Muscle Wasting and Associates with Cachexia in Patients with Cancer

Skeletal muscle wasting is a devastating consequence of cancer that contributes to increased complications and poor survival, but is not well understood at the molecular level. Herein, we investigated the role of Myocilin (Myoc), a skeletal muscle hypertrophy-promoting protein that we showed is downregulated in multiple mouse models of cancer cachexia. Loss of Myoc alone was sufficient to induce phenotypes identified in mouse models of cancer cachexia, including muscle fiber atrophy, sarcolemmal fragility, and impaired muscle regeneration. By 18 months of age, mice deficient in Myoc showed significant skeletal muscle remodeling, characterized by increased fat and collagen deposition compared with wild-type mice, thus also supporting Myoc as a regulator of muscle quality. In cancer cachexia models, maintaining skeletal muscle expression of Myoc significantly attenuated muscle loss, while mice lacking Myoc showed enhanced muscle wasting. Furthermore, we identified the myocyte enhancer factor 2 C (MEF2C) transcription factor as a key upstream activator of Myoc whose gain of function significantly deterred cancer-induced muscle wasting and dysfunction in a preclinical model of pancreatic ductal adenocarcinoma (PDAC). Finally, compared with noncancer control patients, MYOC was significantly reduced in skeletal muscle of patients with PDAC defined as cachectic and correlated with MEF2c. These data therefore identify disruptions in MEF2c-dependent transcription of Myoc as a novel mechanism of cancer-associated muscle wasting that is similarly disrupted in muscle of patients with cachectic cancer. SIGNIFICANCE: This work identifies a novel transcriptional mechanism that mediates skeletal muscle wasting in murine models of cancer cachexia that is disrupted in skeletal muscle of patients with cancer exhibiting cachexia.

Promising models for cancer-induced cachexia drug discovery

Introduction: Cachexia is a frequent, multifactorial syndrome associated with cancer afflicting patients' quality of life, their ability to tolerate anti-neoplastic therapies and the therapies efficacy, as well as survival. Currently, there are no approved cancer cachexia treatments other than those for the treatment of the underlying cancer. Cancer cachexia (CC) is poorly understood and hence makes clinical trial design difficult at best. This underlines the importance of well-characterized animal models to further elucidate the pathophysiology of CC and drug discovery/development.Areas covered: This review gives an overview of the available animal models and their value and limitations in translational studies.Expert opinion: Using more than one CC model to test research questions or novel compounds/treatment strategies is strongly advisable. The main reason is that models have unique signaling modalities driving cachexia that may only relate to subgroups of cancer patients. Human xenograph CC models require the use of mice with a compromised immune system, limiting their value for translational experiments. It may prove beneficial to include standard care chemotherapy in the experimental design, as many chemotherapeutic agents can induce cachexia themselves and alter the metabolic and signaling derangements of CC and thus the response to new therapeutic strategies.

Metastasis and cachexia: alongside in clinics, but not so in animal models

Cancer cachexia is a paraneoplastic syndrome characterized by lean mass wasting (with or without fat mass decrease), culminating in involuntary weight loss, which is the key clinical observation nowadays. There is a notable lack of studies involving animal models to mimic the clinical reality, which are mostly patients with cachexia and metastatic disease. This mismatch between the clinical reality and animal models could at least partly contribute to the poor translation observed in the field. In this paper, we retrieved and compared animal models used for cachexia research from 2017 and 10 years earlier (2007) and observed that very little has changed. Especially, clinically relevant models where cachexia is studied in an orthotopic or metastatic context were and still are very scarce. Finally, we described and supported the biological rationale behind why, despite technical challenges, these two phenomena-metastasis and cachexia-should be modelled in parallel, highlighting the overlapping pathways between them. To sum up, this review aims to contribute to rethinking and possibly switching the models currently used for cachexia research, to hopefully obtain better and more translational outcomes.

Modeling Human Cancer-induced Cachexia

Cachexia is a wasting syndrome characterized by pronounced skeletal muscle loss. In cancer, cachexia is associated with increased morbidity and mortality and decreased treatment tolerance. Although advances have been made in understanding the mechanisms of cachexia, translating these advances to the clinic has been challenging. One reason for this shortcoming may be the current animal models, which fail to fully recapitulate the etiology of human cancer-induced tissue wasting. Because pancreatic ductal adenocarcinoma (PDA) presents with a high incidence of cachexia, we engineered a mouse model of PDA that we named KPP. KPP mice, similar to PDA patients, progressively lose skeletal and adipose mass as a consequence of their tumors. In addition, KPP muscles exhibit a similar gene ontology as cachectic patients. We envision that the KPP model will be a useful resource for advancing our mechanistic understanding and ability to treat cancer cachexia.

Racial and ethnic disparities in a state-wide registry of patients with pancreatic cancer and an exploratory investigation of cancer cachexia as a contributor to observed inequities

Pancreatic cancer (PC) is characterized by racial/ethnic disparities and the debilitating muscle-wasting condition, cancer cachexia. Florida ranks second in the number of PC deaths and has a large and understudied minority population. We examined the primary hypothesis that PC incidence and mortality rates may be highest among Black Floridians and the secondary hypothesis that biological correlates of cancer cachexia may underlie disparities. PC incidence and mortality rates were estimated by race/ethnicity, gender, and county using publicly available state-wide cancer registry data that included approximately 2700 Black, 25 200 Non-Hispanic White (NHW), and 3300 Hispanic/Latino (H/L) Floridians diagnosed between 2004 and 2014. Blacks within Florida experienced a significantly (P < 0.05) higher incidence (12.5/100 000) and mortality (10.97/100 000) compared to NHW (incidence = 11.2/100 000; mortality = 10.3/100 000) and H/L (incidence = 9.6/100 000; mortality = 8.7/100 000), especially in rural counties. To investigate radiologic and blood-based correlates of cachexia, we leveraged data from a subset of patients evaluated at two geographically distinct Florida Cancer Centers. In Blacks compared to NHW matched on stage, markers of PC-induced cachexia were more frequent and included greater decreases in core musculature compared to corresponding healthy control patients (25.0% vs 10.1% lower), greater decreases in psoas musculature over time (10.5% vs 4.8% loss), lower baseline serum albumin levels (3.8 vs 4.0 gm/dL), and higher platelet counts (332.8 vs 268.7 k/UL). Together, these findings suggest for the first time that PC and cachexia may affect Blacks disproportionately. Given its nearly universal contribution to illness and PC-related deaths, the early diagnosis and treatment of cachexia may represent an avenue to improve health equity, quality of life, and survival.

MyD88 signalling is critical in the development of pancreatic cancer cachexia

BACKGROUND

Up to 80% of pancreatic cancer patients suffer from cachexia, a devastating condition that exacerbates underlying disease, reduces quality of life, and increases treatment complications and mortality. Tumour-induced inflammation is linked to this multifactorial wasting syndrome, but mechanisms and effective treatments remain elusive. Myeloid differentiation factor (MyD88), a key component of the innate immune system, plays a pivotal role in directing the inflammatory response to various insults. In this study, we tested whether MyD88 signalling is essential in the development of pancreatic cancer cachexia using a robust mouse tumour model.

METHODS

Sex, age, and body weight-matched wide type (WT) and MyD88 knockout (MyD88 KO) mice were orthotopically or intraperitoneally implanted with a pancreatic tumour cell line from a syngeneic C57BL/6 KRAS^G12D/+ P53^R172H/+ Pdx-Cre (KPC) mouse. We observed the effects of MyD88 signalling during pancreatic ductal adenocarcinoma progression and the cachexia development through behavioural, histological, molecular, and survival aspects.

RESULTS

Blocking MyD88 signalling greatly ameliorated pancreatic ductal adenocarcinoma-associated anorexia and fatigue, attenuated lean mass loss, reduced muscle catabolism and atrophy, diminished systemic and central nervous system inflammation, and ultimately improved survival. Our data demonstrate that MyD88 signalling plays a critical role in mediating pancreatic cancer-induced inflammation that triggers cachexia development and therefore represents a promising therapeutic target.

CONCLUSIONS

MyD88-dependent inflammation is crucial in the pathophysiology of pancreatic cancer progression and contributes to high mortality. Our findings implicate the importance of innate immune signalling pathways in pancreatic cancer cachexia and a novel therapeutic target.

Development and characterization of a cancer cachexia model employing a rare human duodenal neuroendocrine carcinoma-originating cell line

Cancer cachexia interferes with therapy and worsens patients' quality of life. Therefore, for a better understanding of cachexia, we aimed to establish a reliable cell line to develop a cachexia model. We recently established and characterized the TCC-NECT-2 cell line, derived from a Japanese patient with poorly differentiated neuroendocrine carcinoma of the duodenum (D-NEC). Subcutaneous xenograft of TCC-NECT-2 cells in mice resulted in tumor formation, angiogenesis, and 20% incidence of body weight (BW)-loss. Subsequently, we isolated a potent cachexia-inducing subline using stepwise selection and designated as AkuNEC. Orthotopic and s.c. implantation of AkuNEC cells into mice led to diminished BW, anorexia, skeletal muscle atrophy, adipose tissue loss, and decreased locomotor activity at 100% incidence. Additionally, orthotopic implantation of AkuNEC cells resulted in metastasis and angiogenesis. Serum IL-8 overproduction was observed, and levels were positively correlated with BW-loss and reduced adipose tissue and muscle volumes in tumor-bearing mice. However, shRNA knockdown of the IL-8 gene did not suppress tumor growth and cachexia in the AkuNEC model, indicating that IL-8 is not directly involved in cachexia induction. In conclusion, AkuNEC cells may serve as a useful model to study cachexia and D-NEC.

Local and Systemic Cytokine Profiling for Pancreatic Ductal Adenocarcinoma to Study Cancer Cachexia in an Era of Precision Medicine

Cancer cachexia is a debilitating condition seen frequently in patients with pancreatic ductal adenocarcinoma (PDAC). The underlying mechanisms driving cancer cachexia are not fully understood but are related, at least in part, to the immune response to the tumor both locally and systemically. We hypothesize that there are unique differences in cytokine levels in the tumor microenvironment and systemic circulation between PDAC tumors and that these varying profiles affect the degree of cancer cachexia observed. Patient demographics, operative factors, oncologic factors, and perioperative data were collected for the two patients in the patient derived xenograft (PDX) model. Human pancreatic cancer PDX were created by implanting fresh surgical pancreatic cancer tissues directly into immunodeficient mice. At PDX end point, mouse tumor, spleen and muscle tissues were collected and weighed, muscle atrophy related gene expression measured, and tumor and splenic soluble proteins were analyzed. PDX models were created from surgically resected patients who presented with different degrees of cachexia. Tumor free body weight and triceps surae weight differed significantly between the PDX models and control (P < 0.05). Both PDX groups had increased atrophy related gene expression in muscle compared to control (FoxO1, Socs3, STAT3, Acvr2b, Atrogin-1, MuRF1; P < 0.05). Significant differences were noted in splenic soluble protein concentrations in 14 of 15 detected proteins in tumor bearing mice when compared to controls. Eight splenic soluble proteins were significantly different between PDX groups (P < 0.05). Tumor soluble proteins were significantly different between the two PDX groups in 15 of 24 detected proteins (P < 0.05). PDX models preserve the cachectic heterogeneity found in patients and are associated with unique cytokine profiles in both the spleen and tumor between different PDX. These data support the use of PDX as a strategy to study soluble cachexia protein markers and also further efforts to elucidate which cytokines are most related to cachexia in order to provide potential targets for immunotherapy.

Tumour-derived leukaemia inhibitory factor is a major driver of cancer cachexia and morbidity in C26 tumour-bearing mice

BACKGROUND

Cancer cachexia is a metabolic wasting syndrome that is strongly associated with a poor prognosis. The initiating factors causing fat and muscle loss are largely unknown. Previously, we found that leukaemia inhibitory factor (LIF) secreted by C26 colon carcinoma cells was responsible for atrophy in treated myotubes. In the present study, we tested whether C26 tumour-derived LIF is required for cancer cachexia in mice by knockout of Lif in C26 cells.

METHODS

A C26 Lif null tumour cell line was made using CRISPR-Cas9. Measurements of cachexia were compared in mice inoculated with C26 vs. C26^Lif-/- tumour cells, and atrophy was compared in myotubes treated with medium from C26 vs. C26^Lif-/- tumour cells. Levels of 25 cytokines/chemokines were compared in serum of mice bearing C26 vs. C26^Lif-/- tumours and in the medium from these tumour cell lines.

RESULTS

At study endpoint, C26 mice showed outward signs of sickness while mice with C26^Lif-/- tumours appeared healthy. Mice with C26^Lif-/- tumours showed a 55-75% amelioration of body weight loss, muscle loss, fat loss, and splenomegaly compared with mice with C26 tumours (P < 0.05). The heart was not affected by LIF levels because the loss of cardiac mass was the same in C26 and C26^Lif-/- tumour-bearing mice. LIF levels in mouse serum was entirely dependent on secretion from the tumour cells. Serum levels of interleukin-6 and G-CSF were increased by 79-fold and 68-fold, respectively, in C26 mice but only by five-fold and two-fold, respectively, in C26^Lif-/- mice, suggesting that interleukin-6 and G-CSF increases are dependent on tumour-derived LIF.

CONCLUSIONS

This study shows the first use of CRISPR-Cas9 knockout of a candidate cachexia factor in tumour cells. The results provide direct evidence for LIF as a major cachexia initiating factor for the C26 tumour in vivo. Tumour-derived LIF was also a regulator of multiple cytokines in C26 tumour cells and in C26 tumour-bearing mice. The identification of tumour-derived factors such as LIF that initiate the cachectic process is immediately applicable to the development of therapeutics to treat cachexia. This is a proof of principle for studies that when carried out in human cells, will make possible an understanding of the factors causing cachexia in a patient-specific manner.

Pancreatic Cancer-Induced Cachexia and Relevant Mouse Models

Pancreatic cancer is the third leading cause of cancer death in the United States, with projections that it will become the second leading cause by the year 2030. It carries a dismal prognosis with a 5-year overall survival rate of less than 9% and is associated with numerous comorbidities, the most notable being cachexia. Defined as the loss of muscle mass not reversible by conventional nutritional support, cachexia is seen in over 85% of pancreatic cancer patients and contributes significantly to mortality, where nearly 30% of pancreatic cancer deaths are due to cachexia rather than tumor burden. Therefore, there is an urgent need to identify the mechanisms behind the development of muscle wasting in pancreatic cancer patients and design novel therapeutics targeting cachexia. This review highlights the current understanding surrounding the mechanisms underpinning the development of cachexia in pancreatic cancer, as well as the current mouse models of pancreatic cancer-induced muscle wasting described in the literature.