Gemma Fuster

Anticachectic effects of formoterol: a drug for potential treatment of muscle wasting.

In cancer cachexia both cardiac and skeletal muscle suffer an important protein mobilization as a result of increased proteolysis. Administration of the β2-agonist formoterol to both rats and mice bearing highly cachectic tumors resulted in an important reversal of the muscle-wasting process. The anti-wasting effects of the drug were based on both an activation of the rate of protein synthesis and an inhibition of the rate of muscle proteolysis. Northern blot analysis revealed that formoterol treatment resulted in a decrease in the mRNA content of ubiquitin and proteasome subunits in gastrocnemius muscles; this, together with the decreased proteasome activity observed, suggest that the main anti-proteolytic action of the drug may be based on an inhibition of the ATP-ubiquitin-dependent proteolytic system. Interestingly, the β2-agonist was also able to diminish the increased rate of muscle apoptosis (measured as DNA laddering as well as caspase-3 activity) present in tumor-bearing animals. The present results indicate that formoterol exerted a selective, powerful protective action on heart and skeletal muscle by antagonizing the enhanced protein degradation that characterizes cancer cachexia, and it could be revealed as a potential therapeutic tool in pathologic states wherein muscle protein hypercatabolism is a critical feature such as cancer cachexia or other wasting diseases.

Cancer cachexia: the molecular mechanisms

Cancer cachexia is a syndrome characterised by a marked weight loss, anorexia, asthenia and anaemia. In fact, many patients who die with advanced cancer suffer from cancer cachexia. The cachectic state is invariably associated with the presence and growth of the tumour and leads to a malnutrition status due to the induction of anorexia or decreased food intake. In addition, the competition for nutrients between the tumour and the host leads to an accelerated starvation state which promotes severe metabolic disturbances in the host, including hypermetabolism which leads to an increased energetic inefficiency. Although, the search for the cachectic factor(s) started a long time ago, and although many scientific and economic efforts have been devoted to its discovery, we are still a long way from knowing the whole truth. The main aim of the present review is to summarise and evaluate the different catabolic mediators (both humoural and tumoural) involved in cancer cachexia since they may represent targets for future promising clinical investigations.

Substance P autocrine signaling contributes to persistent HER2 activation that drives malignant progression and drug resistance in breast cancer

ERBB receptor transmodulation by heterologous G-protein-coupled receptors (GPCR) generates functional diversity in signal transduction. Tachykinins are neuropeptides and proinflammatory cytokines that promote cell survival and cancer progression by activating several GPCRs. In this work, we found that the pain-associated tachykinin Substance P (SP) contributes to persistent transmodulation of the ERBB receptors, EGFR and HER2, in breast cancer, acting to enhance malignancy and therapeutic resistance. SP and its high-affinity receptor NK-1R were highly expressed in HER2(+) primary breast tumors (relative to the luminal and triple-negative subtypes) and were overall correlated with poor prognosis factors. In breast cancer cell lines and primary cultures derived from breast cancer samples, we found that SP could activate HER2. Conversely, RNA interference-mediated attenuation of NK-1R, or its chemical inhibition, or suppression of overall GPCR-mediated signaling, all strongly decreased steady-state expression of EGFR and HER2, establishing that their basal activity relied upon transdirectional activation by GPCR. Thus, SP exposure affected cellular responses to anti-ERBB therapies. Our work reveals an important oncogenic cooperation between NK-1R and HER2, thereby adding a novel link between inflammation and cancer progression that may be targetable by SP antagonists that have been clinically explored.

Are Peroxisome Proliferator-Activated Receptors Involved in Skeletal Muscle Wasting during Experimental Cancer Cachexia? Role of β2-Adrenergic Agonists

Implantation of the Yoshida AH-130 ascites hepatoma to rats resulted in a decrease in muscle weight 7 days after the inoculation of the tumor. These changes were associated with increases in the mRNA content for both peroxisome proliferator-activated receptor (PPAR) gamma and PPAR delta in skeletal muscle. The increase in gene expression for these transcription factors was related to increases in the expression of several genes involved in fatty acid transport, activation, and oxidation. Tumor burden also resulted in increases in PPAR gamma coactivator-1 alpha gene expression and pyruvate dehydrogenase kinase 4. All these changes in lipid metabolism genes suggest that a metabolic shift occurs in skeletal muscle of tumor-bearing rats toward a more oxidative phenotype. Formoterol treatment to tumor-bearing rats resulted in an amelioration of all the changes observed as a result of tumor burden. Administration of this beta(2)-adrenergic agonist also resulted in a decrease in mRNA content of muscle PPAR alpha, PPAR delta, and PPAR gamma, as well as in mRNA levels of many of the genes involved in both lipid and mitochondrial metabolism. All these results suggest an involvement of the different PPARs as transcription factors related with muscle wasting and also indicate that a possible mode of action of the anticachectic compound formoterol may involve a normalization of the levels of these transcription factors.

Heterogeneity of breast cancer: etiology and clinical relevance

Cancer progression is a dynamic process of clonal adaptation to changing microenvironments. From the single founder cell until the clinical detection of tumours, there are consecutive clonal expansions and a constant acquisition of genetic and epigenetic alterations, events that contribute to the generation of intra-tumor heterogeneity. In breast cancer intra-tumor heterogeneity can arise from the differentiation of stem-like cells along with the clonal selection during tumor progression, and represents a major challenge for the design of effective therapies. To infer breast cancer progression and its response to particular treatments it is important to understand the origins of the inter- and intra-tumor heterogeneity and the forces that control tumor evolution. Insights about the evolution of breast cancer heterogeneity would contribute to the design of most effective therapeutic strategies to target the tumors at single clon level. This review is intended to give a general overview about the origins of breast cancer heterogeneity and its impact in the clinical management of the disease.

Effects of IL-15 on Rat Brown Adipose Tissue : Uncoupling Proteins and PPARs

Objectives: Interleukin‐15 (IL‐15) plays an important role in lipid metabolism as its administration to rats causes a marked depletion of white adipose tissue (WAT). This reduction in fat mass seems to be caused by and related to hipotriglyceridemia as a result of a lower hepatic lipogenesis and an increased fatty acid oxidation. We have previously observed that IL‐15 treatment induces the expression of uncoupling proteins (UCPs) in muscle. The aim of this study was to investigate the effects of IL‐15 on brown adipose tissue (BAT), and in particular on genes related to lipid metabolism in this tissue.

Interleukin-15 Affects Differentiation and Apoptosis in Adipocytes: Implications in Obesity

Interleukin-15 (IL-15) is an anabolic factor for skeletal muscle and several reports have described its important role as a regulator of energy homeostasis. In this study, we analyzed the effects of IL-15 on adipocyte differentiation using the 3T3-L1 preadipose cell line. The data show that IL-15 tends to reduce the rate of adipocyte proliferation, induces apoptosis, and partially stops differentiation. The signaling molecules behind these actions of the cytokine on adipose cells are: p42/p44 MAPK (which seem to be associated with the reduced rate of proliferation induced by the cytokine), STAT5 (which is related to the actions of IL-15 on differentiation), and SAPK/JNK (which are related to the increased apoptosis induced by IL-15). In conclusion, using the 3T3-L1 adipocyte cell line, the results presented here show that IL-15 exerts important effects on differentiation, proliferation and apoptosis. Altogether, the results presented here reinforce the idea that IL-15 is an important mediator that regulates adipose size and, therefore, the role of the cytokine in affecting body weight and obesity deserves additional studies.

Effects of CRF2R agonist on tumor growth and cachexia in mice implanted with Lewis lung carcinoma cells.

Previous studies have demonstrated an effect of corticotropin‐releasing factor 2 receptor (CRF2R) agonists in the maintenance of skeletal muscle mass. The aim of this study was to evaluate the effects of a CRF2R agonist in preserving skeletal muscle in a mouse cachexia model. Implantation of a fast‐growing tumor to mice (Lewis lung carcinoma) resulted in a clear cachectic state characterized by a profound muscle wasting. We found that administration of a CRF2R agonist (PG‐873637) at 100 μg/kg/day by means of osmotic minipumps to tumor‐bearing mice resulted in beneficial effects on muscle weight loss. Thus, muscle loss was partially reversed by the CRF2R agonist at different stages of tumor growth (at day 14 after tumor inoculation: 12% in tibialis posterior; 9% in gastrocnemius; and 48% in soleus). Moreover, the CRF2R agonist significantly reduced both the number of metastases and their mass (at day 19 after tumor inoculation: 66% and 61%, respectively). These data suggest a potentially beneficial effect of the CRF2R agonist in preserving skeletal muscle during cancer cachexia and open a line of research for the development of new therapeutic approaches for the treatment of muscle wasting associated with cancer. Muscle Nerve, 2007

Comparison of methods for the isolation of human breast epithelial and myoepithelial cells

Two lineages, epithelial, and myoepithelial cells are the main cell populations in the normal mammary gland and in breast cancer. Traditionally, cancer research has been performed using commercial cell lines, but primary cell cultures obtained from fresh breast tissue are a powerful tool to study more reliably new aspects of mammary gland biology, including normal and pathological conditions. Nevertheless, the methods described to date have some technical problems in terms of cell viability and yield, which hamper work with primary mammary cells. Therefore, there is a need to optimize technology for the proper isolation of epithelial and myoepithelial cells. For this reason, we compared four methods in an effort to improve the isolation and primary cell culture of different cell populations of human mammary epithelium. The samples were obtained from healthy tissue of patients who had undergone mammoplasty or mastectomy surgery. We based our approaches on previously described methods, and incorporated additional steps to ameliorate technical efficiency and increase cell survival. We determined cell growth and viability by phase-contrast images, growth curve analysis and cell yield, and identified cell-lineage specific markers by flow cytometry and immunofluorescence in 3D cell cultures. These techniques allowed us to better evaluate the functional capabilities of these two main mammary lineages, using CD227/K19 (epithelial cells) and CD10/K14 (myoepithelial cells) antigens. Our results show that slow digestion at low enzymatic concentration combined with the differential centrifugation technique is the method that best fits the main goal of the present study: protocol efficiency and cell survival yield. In summary, we propose some guidelines to establish primary mammary epithelial cell lines more efficiently and to provide us with a strong research instrument to better understand the role of different epithelial cell types in the origin of breast cancer.

A differential pattern of gene expression in skeletal muscle of tumor‐bearing rats reveals dysregulation of excitation–contraction coupling together with additional muscle alterations

Introduction: Cachexia is a wasting condition that manifests in several types of cancer. The main characteristic of this condition is a profound loss of muscle mass. Methods: By using a microarray system, expression of several hundred genes was screened in skeletal muscle of rats bearing a cachexia‐inducing tumor, the AH‐130 Yoshida ascites hepatoma. This model induced a strong decrease in muscle mass in the tumor‐bearing animals, as compared with their healthy counterparts. Results: The results show important differences in gene expression in EDL skeletal muscle between tumor‐bearing animals with cachexia and control animals. Conclusions: The differences observed pertain to genes related to intracellular calcium homeostasis and genes involved in the control of mitochondrial oxidative phosphorylation and protein turnover, both at the level of protein synthesis and proteolysis. Assessment of these differences may be a useful tool for the design of novel therapeutic strategies to fight this devastating syndrome. Muscle Nerve 49: 233–248, 2014