Erin E. Talbert

Modeling human cancer cachexia in colon 26 tumor-bearing adult mice.

BackgroundMuscle wasting is a profound side effect of advanced cancer. Cancer-induced cachexia decreases patient quality of life and is associated with poor patient survival. Currently, no clinical therapies exist to treat cancer-induced muscle wasting. Although cancers commonly associated with cachexia occur in older individuals, the standard animal models used to elucidate the causes of cachexia rely on juvenile mice.MethodsIn an effort to better model human cancer cachexia, we determined whether cachectic features seen in young mice could be achieved in adult, pre-sarcopenic mice following colon 26 (C-26) tumor cell inoculation.ResultsBoth young and adult mice developed similar-sized tumors and progressed to cachexia with similar kinetics, as evidenced by losses in body mass, and adipose and skeletal muscle tissues. Proteolytic signaling, including proteasome and autophagy genes, was also increased in muscles from both young and adult tumor-bearing animals. Furthermore, tumor-associated muscle damage and activation of Pax7 progenitor cells was induced in both young and adult mice.ConclusionsAlthough cancer cachexia generally occurs in older individuals, these data suggest that the phenotype and underlying mechanisms can be effectively modeled using the currently accepted protocol in juvenile mice.

MyoD Regulates Skeletal Muscle Oxidative Metabolism Cooperatively with Alternative NF-κB

MyoD is a key regulator of skeletal myogenesis that directs contractile protein synthesis, but whether this transcription factor also regulates skeletal muscle metabolism has not been explored. In a genome-wide ChIP-seq analysis of skeletal muscle cells, we unexpectedly observed that MyoD directly binds to numerous metabolic genes, including those associated with mitochondrial biogenesis, fatty acid oxidation, and the electron transport chain. Results in cultured cells and adult skeletal muscle confirmed that MyoD regulates oxidative metabolism through multiple transcriptional targets, including PGC-1β, a master regulator of mitochondrial biogenesis. We find that PGC-1β expression is cooperatively regulated by MyoD and the alternative NF-κB signaling pathway. Bioinformatics evidence suggests that this cooperativity between MyoD and NF-κB extends to other metabolic genes as well. Together, these data identify MyoD as a regulator of the metabolic capacity of mature skeletal muscle to ensure that sufficient energy is available to support muscle contraction.

Impaired regeneration: A role for the muscle microenvironment in cancer cachexia

While changes in muscle protein synthesis and degradation have long been known to contribute to muscle wasting, a body of literature has arisen which suggests that regulation of the satellite cell and its ensuing regenerative program are impaired in atrophied muscle. Lessons learned from cancer cachexia suggest that this regulation is simply not a consequence, but a contributing factor to the wasting process. In addition to satellite cells, evidence from mouse models of cancer cachexia also suggests that non-satellite progenitor cells from the muscle microenvironment are also involved. This chapter in the series reviews the evidence of dysfunctional muscle repair in multiple wasting conditions. Potential mechanisms for this dysfunctional regeneration are discussed, particularly in the context of cancer cachexia.

Predictors of Pancreatic Cancer–Associated Weight Loss and Nutritional Interventions

Objectives Pancreatic ductal adenocarcinoma (PDAC) is often accompanied by weight loss. We sought to characterize factors associated with weight loss and observed nutritional interventions, as well as define the effect of weight loss on survival. Methods Consecutive subjects diagnosed with PDAC (N = 123) were retrospectively evaluated. Univariate analysis was used to compare subjects with and without substantial (>5%) weight loss. Multivariate logistic regression was performed to identify factors associated with weight loss, and survival analyses were performed using Kaplan-Meier curves and Cox survival models. Results Substantial weight loss at diagnosis was present in 71.5% of subjects and was independently associated with higher baseline body mass index, longer symptom duration, and increased tumor size. Recommendations for nutrition consultation and pancreatic enzyme replacement therapy occurred in 27.6% and 36.9% of subjects, respectively. Weight loss (>5%) was not associated with worse survival on multivariate analysis (hazard ratio, 1.32; 95% confidence interval, 0.76–2.30), unless a higher threshold (>10%) was used (hazard ratio, 1.77; 95% confidence interval, 1.09–2.87). Conclusions Despite the high prevalence of weight loss at PDAC diagnosis, there are low observed rates of nutritional interventions. Weight loss based on current criteria for cancer cachexia is not associated with poor survival in PDAC.

Dual Inhibition of MEK and PI3K/Akt Rescues Cancer Cachexia through Both Tumor Extrinsic and Intrinsic Activities.

Involuntary weight loss, a part of the cachexia syndrome, is a debilitating comorbidity of cancer and currently has no treatment options. Results from a recent clinical trial at our institution showed that biliary tract cancer patients treated with a MEK inhibitor exhibited poor tumor responses but surprisingly gained weight and increased their skeletal muscle mass. This implied that MEK inhibition might be anticachectic. To test this potential effect of MEK inhibition, we utilized the established Colon-26 model of cancer cachexia and the MEK1/2 inhibitor MEK162. Results showed that MEK inhibition effectively prevented muscle wasting. Importantly, MEK162 retained its ability to spare muscle loss even in mice bearing a Colon-26 clone resistant to the MEK inhibitor, demonstrating that the effects of blocking MEK are at least in part independent of the tumor. Because single-agent MEK inhibitors have been limited as a first-line targeted therapy due to compensatory activation of other oncogenic signaling pathways, we combined MEK162 with the PI3K/Akt inhibitor buparlisib. Results showed that this combinatorial treatment significantly reduced tumor growth due to a direct activity on Colon-26 tumor cells in vitro and in vivo, while also preserving skeletal muscle mass. Together, our results suggest that as a monotherapy, MEK inhibition preserves muscle mass, but when combined with a PI3K/Akt inhibitor exhibits potent antitumor activity. Thus, combinatorial therapy might serve as a new approach for the treatment of cancer cachexia. Mol Cancer Ther; 16(2); 344–56. ©2016 AACR. See related article by Kobayashi et al., p. 357

NF-κB regulates GDF-15 to suppress macrophage surveillance during early tumor development

Macrophages are attracted to developing tumors and can participate in immune surveillance to eliminate neoplastic cells. In response, neoplastic cells utilize NF-κB to suppress this killing activity, but the mechanisms underlying their self-protection remain unclear. Here, we report that this dynamic interaction between tumor cells and macrophages is integrally linked by a soluble factor identified as growth and differentiation factor 15 (GDF-15). In vitro, tumor-derived GDF-15 signals in macrophages to suppress their proapoptotic activity by inhibiting TNF and nitric oxide (NO) production. In vivo, depletion of GDF-15 in Ras-driven tumor xenografts and in an orthotopic model of pancreatic cancer delayed tumor development. This delay correlated with increased infiltrating antitumor macrophages. Further, production of GDF-15 is directly regulated by NF-κB, and the colocalization of activated NF-κB and GDF-15 in epithelial ducts of human pancreatic adenocarcinoma supports the importance of this observation. Mechanistically, we found that GDF-15 suppresses macrophage activity by inhibiting TGF-β-activated kinase (TAK1) signaling to NF-κB, thereby blocking synthesis of TNF and NO. Based on these results, we propose that the NF-κB/GDF-15 regulatory axis is important for tumor cells in evading macrophage immune surveillance during the early stages of tumorigenesis.

Crosstalk between autophagy and oxidative stress regulates proteolysis in the diaphragm during mechanical ventilation

ABSTRACT Mechanical ventilation (MV) results in the rapid development of ventilator‐induced diaphragm dysfunction (VIDD). While the mechanisms responsible for VIDD are not fully understood, recent data reveal that prolonged MV activates autophagy in the diaphragm, which may occur as a result of increased cellular reactive oxygen species (ROS) production. Therefore, we tested the hypothesis that (1) accelerated autophagy is a key contributor to VIDD; and that (2) oxidative stress is required to increase the expression of autophagy genes in the diaphragm. Our findings reveal that targeted inhibition of autophagy in the rat diaphragm prevented MV‐induced muscle atrophy and contractile dysfunction. Attenuation of VIDD in these animals occurred as a result of increased diaphragm concentration of the antioxidant catalase and reduced mitochondrial ROS emission, which corresponded to reductions in the activity of calpain and caspase‐3. To determine if increased ROS production is required for the upregulation of autophagy biomarkers in the diaphragm, rats that were administered the mitochondrial‐targeted peptide SS‐31 during MV. Results from this study demonstrated that mitochondrial ROS production in the diaphragm during MV is required for the increased expression of key autophagy genes (i.e. LC3, Atg7, Atg12, Beclin1 and p62), as well as for increased activity of cathepsin L. Together, these data reveal that autophagy is required for VIDD, and that autophagy inhibition reduces MV‐induced diaphragm ROS production and prevents a positive feedback loop whereby increased autophagy is stimulated by oxidative stress, resulting in further increases in ROS and autophagy. Graphical abstract Figure. No caption available. HighlightsMechanical ventilation induces increased autophagic signaling and oxidative stress in the diaphragm.Inhibition of autophagy is sufficient to prevent ventilator‐induced diaphragm dysfunction.Mechanical ventilation‐induced autophagy is required for diaphragm mitochondrial dysfunction and oxidative stress.Mitochondrial reactive oxygen species emission promotes autophagosome formation in the diaphragm.

Circulating monocyte chemoattractant protein-1 (MCP-1) is associated with cachexia in treatment-naïve pancreatic cancer patients: A biomarker analysis in pancreatic adenocarcinoma-induced cachexia

Cancer‐associated wasting, termed cancer cachexia, has a profound effect on the morbidity and mortality of cancer patients but remains difficult to recognize and diagnose. While increases in circulating levels of a number of inflammatory cytokines have been associated with cancer cachexia, these associations were generally made in patients with advanced disease and thus may be associated with disease progression rather than directly with the cachexia syndrome. Thus, we sought to assess potential biomarkers of cancer‐induced cachexia in patients with earlier stages of disease.

Perioperative cytokine levels portend early death after pancreatectomy for ductal adenocarcinoma

Soluble signaling molecules may play an important role in malignant pathogenesis. We hypothesize that perioperative cytokine levels are associated with outcomes in patients with pancreatic adenocarcinoma (PDAC) undergoing surgical resection.

Abstract 4695: Dual targeting of MEK and PI3K pathways can act via tumor-intrinsic mechanisms to overcome resistance and tumor-extrinsic mechanisms to modulate immunity and limit cancer cachexia

Prior studies by our group have shown that single-agent MEK inhibitors have clinical activity in cholangiocarcinoma (CC), including objective responses. Yet no relationship was found between clinical benefit, and oncogenic driver mutations such as KRAS or BRAF. Strategies to expand upon MEKi have focused on combinations with agents targeting resistance, such as the PI3K/Akt pathway. CC patients treated with MEKi also had reduced pro-inflammatory cytokines and weight gain with restoration of muscle mass. These findings are clinically significant, and led us to hypothesize that MEKi act via tumor-extrinsic mechanisms to modulate immunity and limit cancer cachexia, while overcoming tumor-intrinsic resistance. We used the colon-26 adenocarcinoma model to evaluate the effect of single and combined treatment with MEK162 (30mg/kg) and buparlisib (25mg/kg) on muscle wasting, tumor growth, and immune modulation. This murine model depends on interleukin-6 (IL-6) and recapitulates the cancer cachexia syndrome. Single agent MEK162 inhibited growth initially, but after 14 days, tumor volume was comparable between MEKi and vehicle treated mice, possibly from acquired MEK162 resistance. Despite these data, reduced serum IL-6 and splenic Gr1+CD11b+ cells were evident compared to control mice (mean = 358 pg/mL to 43 pg/mL, and 13.8% to 8.4%, respectively), while body weight from MEK162 treated mice was spared (mean = 24.0g to 20.5g in control mice). In addition, markers of muscle catabolism, including the E3 ubiquitin ligases Atrogin-1 (from 1 to 0.043 in combo) and MuRF1 (from 1 to 0.03 in combo), and the autophagy gene, Bnip3, were all reduced in tibialis anterior muscles from tumor-bearing mice treated with MEK162. Similar to our clinical data, these results suggest MEK162 modulates immune biomarkers, and acts as an anti-cachexia agent. Since cross talk between MAPK and PI3K/AKT pathways promotes resistance to monotherapy, we next investigated the effects of MEK162 combined with buparlisib in the colon-26 model. As before, single agent MEK162 had a modest growth inhibitory effect, yet rescued body weight. Consistent with in vitro studies, single agent buparlisib was cytostatic, but not as effective as MEK162 in rescuing weight loss. However, dual treatment with MEK162 + buparlisib significantly inhibited tumor growth. This combination also significantly reduced splenic MDSC (mean = 37% to 9% in control mice) and increased CD4+ and CD8+ (mean = 24% to 6%, and 7.7% to 2%, respectively) T cells. These results suggest that dual inhibition of MEK and PI3K has efficacy, while MEKi may have under-appreciated tumor-extrinsic mechanisms of activity that can be leveraged to benefit patients with advanced malignancy. This treatment combination will be evaluated in CC patients in the setting of a Phase II clinical trial. Citation Format: Jennifer Yang, Erin Talbert, Omar Elnaggar, Priyani Rajasekera, Thomas Mace, Matthew Farren, Zheng Che, Benjamin Swanson, Gregory Young, Ericka Haverick, Cynthia Timmers, Mark Bloomston, Tanios Bekaii-Saab, Denis Guttridge, Gregory Lesinski. Dual targeting of MEK and PI3K pathways can act via tumor-intrinsic mechanisms to overcome resistance and tumor-extrinsic mechanisms to modulate immunity and limit cancer cachexia. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4695. doi:10.1158/1538-7445.AM2015-4695