Distinct behaviour of sorafenib in experimental cachexia-inducing tumours: the role of STAT3

Angiogenic and molecular diversity determine hepatic melanoma metastasis and response to anti-angiogenic treatment

BACKGROUND

Cutaneous melanoma exhibits heterogeneous metastatic patterns and prognosis. In this regard, liver metastasis, which is detected in ~ 10-20% of stage 4 patients, came to the fore of melanoma research, as it recently evolved as decisive indicator of treatment resistance to immune checkpoint inhibition.

METHODS

Hepatic metastases were induced by intrasplenic injection of five different murine melanoma cell lines. The efficiencies of hepatic colonization, morphologic patterns, gene expression profiles and degree of vascularization were analyzed and Sorafenib was applied as anti-angiogenic treatment.

RESULTS

WT31 melanoma showed the highest efficiency of hepatic colonization, while intermediate efficiencies were observed for B16F10 and RET, and low efficiencies for D4M and HCmel12. RNAseq-based gene expression profiles of high and intermediate metastatic melanomas in comparison to low metastatic melanomas indicated that this efficiency predominantly associates with gene clusters involved in cell migration and angiogenesis. Indeed, heterogeneous vascularization patterns were found in the five models. Although the degree of vascularization of WT31 and B16F10 metastases differed, both showed a strong response to Sorafenib with a successful abrogation of the vascularization.

CONCLUSION

Our data indicate that molecular heterogeneity of melanomas can be associated with phenotypic and prognostic features of hepatic metastasis paving the way for organ-specific anti-angiogenic therapeutic approaches.

Alantolactone ameliorates cancer cachexia-associated muscle atrophy mainly by inhibiting the STAT3 signaling pathway

BACKGROUND

Cancer cachexia is a serious metabolic disorder syndrome that is responsible for the deaths of approximately 30% of patients with cancer, but effective drugs for cancer cachexia are still lacking. Inflammatory cytokines such as TNF-α or IL-6 are involved in the induction of skeletal muscle atrophy and fat depletion in patients with cancer cachexia.

PURPOSE

In this study, we assessed the therapeutic effects of the natural compound alantolactone (AL) on cancer cachexia and tried to clarify the mechanisms by which it ameliorates muscle atrophy.

METHODS

The C26 tumor-bearing cancer cachexia mouse model was used to evaluate the efficacy of AL in alleviating cancer cachexia in vivo. The levels of IL-6 or TNF-α in mouse serum were detected using ELISA kits. Cultured C2C12 myotubes and 3T3-L1 adipocytes treated with conditioned medium of C26 tumor cells, IL-6 or TNF-α were employed as in vitro cancer cachexia models to examine the effects of AL in vitro.

RESULTS

AL (5 or 10 mg/kg, qd, i.p.) protected mice with C26 tumors and cachexia from a loss of body weight and muscle wasting but only slightly ameliorated fat loss. The circulating level of IL-6 but not TNF-α was significantly decreased by AL. AL treatment significantly inhibited STAT3 activation in the gastrocnemius (GAS) muscle of cancer cachexia mice. AL (0.125, 0.25, 0.5 and 1 µM) dose-dependently ameliorated myotube atrophy and STAT3 activation in cultured C2C12 myotubes induced by conditioned medium from C26 tumor cells. AL also ameliorated C2C12 myotube atrophy induced by IL-6 and inhibited IL-6-mediated STAT3 activation. AL exhibited weak effects on ameliorating TNF-α-mediated myotube atrophy and NF-κB activation. Only AL at high doses of more than 5 µM ameliorated lipolysis and STAT3 activation induced in mature 3T3-L1 adipocytes by conditioned medium from C26 tumor cells.

CONCLUSIONS

AL significantly ameliorated muscle atrophy in a cancer cachexia model mainly through the inhibition of the STAT3 pathway. AL might be a promising lead compound in the development of drug candidates for cancer cachexia therapy.

Combined Effects of Exercise and Phytoanabolic Extracts in Castrated Male and Female Mice

Dry extracts from the Eurasian plants, Ajuga turkestanica, Eurycoma longifolia, and Urtica dioica have been used as anabolic supplements, despite the limited scientific data on these effects. To assess their actions on early sarcopenia signs, male and female castrated mice were supplemented with lyophilized extracts of the three plants, isolated or in association (named TLU), and submitted to resistance exercise. Ovariectomy (OVX) led to body weight increase and non-high-density cholesterol (HDL) cholesterol elevation, which had been restored by exercise plus U. dioica extract, or by exercise and TLU, respectively. Orchiectomy (ORX) caused skeletal muscle weight loss, accompanied by increased adiposity, being the latter parameter reduced by exercise plus E. longifolia or U. dioica extracts. General physical activity was improved by exercise plus herbal extracts in either OVX or ORX animals. Exercise combined with TLU improved resistance to fatigue in OVX animals, though A. turkestanica enhanced the grip strength in ORX mice. E. longifolia or TLU also reduced the ladder climbing time in ORX mice. Resistance exercise plus herbal extracts partly altered gastrocnemius fiber size frequencies in OVX or ORX mice. We provide novel data that tested ergogenic extracts, when combined with resistance exercise, improved early sarcopenia alterations in castrated male and female mice.

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

Muscle wasting, i.e., cachexia, frequently occurs in cancer and associates with poor prognosis and increased morbidity and mortality. Anticancer treatments have also been shown to contribute to sustainment or exacerbation of cachexia, thus affecting quality of life and overall survival in cancer patients. Pre-clinical studies have shown that blocking activin receptor type 2 (ACVR2) or its ligands and their downstream signaling can preserve muscle mass in rodents bearing experimental cancers, as well as in chemotherapy-treated animals. In tumor-bearing mice, the prevention of skeletal and respiratory muscle wasting was also associated with improved survival. However, the definitive proof that improved survival directly results from muscle preservation following blockade of ACVR2 signaling is still lacking, especially considering that concurrent beneficial effects in organs other than skeletal muscle have also been described in the presence of cancer or following chemotherapy treatments paired with counteraction of ACVR2 signaling. Hence, here, we aim to provide an up-to-date literature review on the multifaceted anti-cachectic effects of ACVR2 blockade in preclinical models of cancer, as well as in combination with anticancer treatments.

Exercise as an anti-inflammatory therapy for cancer cachexia: a focus on interleukin-6 regulation

Cancer cachexia is a complicated disorder of extreme, progressive skeletal muscle wasting. It is directed by metabolic alterations and systemic inflammation dysregulation. Numerous studies have demonstrated that increased systemic inflammation promotes this type of cachexia and have suggested that cytokines are implicated in the skeletal muscle loss. Exercise is firmly established as an anti-inflammatory therapy that can attenuate or even reverse the process of muscle wasting in cancer cachexia. The interleukin IL-6 is generally considered to be a key player in the development of the microenvironment of malignancy; it promotes tumor growth and metastasis by acting as a bridge between chronic inflammation and cancerous tissue and it also induces skeletal muscle atrophy and protein breakdown. Paradoxically, a beneficial role for IL-6 has also been identified recently, and that is its status as a “founding member” of the myokine class of proteins. Skeletal muscle is an important source of circulating IL-6 in people who participate in exercise training. IL-6 acts as an anti-inflammatory myokine by inhibiting TNFα and improving glucose uptake through the stimulation of AMPK signaling. This review discusses the action of IL-6 in skeletal muscle tissue dysfunction and the role of IL-6 as an “exercise factor” that modulates the immune system. This review also sheds light on the main considerations related to the treatment of muscle wasting in cancer cachexia.

The animal cachexia score (ACASCO)

BACKGROUND

None of the published studies involving cancer cachexia experimental models have included a measure of the severity of the syndrome like the scoring system previously developed for human subjects. The aim of the present investigation was to define and validate a cachexia score usable in both rat and mouse tumor models.

METHODS

In order to achieve this goal, we included in the study one rat model (Yoshida AH-130ascites hepatoma) and two mouse models (Lewis lung carcinoma and Colon26 carcinoma). The Animal cachexia score (ACASCO) includes five components: (a) body and muscle weight loss, (b) inflammation and metabolic disturbances, (c) physical performance, (d) anorexia, and (e) quality of life measured using discomfort symptoms and behavioral tests.

RESULTS

Using the ACASCO values, three cut-off values were estimated by applying hierarchical cluster analysis. Four groups were originally described, one exactly below the observed mean, a second exactly over the mean, and two other groups adjusted to every cue (inferior and superior). The three cut-off values were estimated through maximization of the classification function. This was accomplished by using a similarity matrix based on the metric properties of the variables and assuming multinormal distribution. The results show that the four groups were: no cachexia, mild cachexia, moderate cachexia and advanced cachexia.

CONCLUSIONS

The results obtained allow us to conclude that the score could be very useful as an endpoint in pre-clinical studies involving therapeutic strategies for cancer cachexia. The potential usefulness of ACASCO relates to the primary endpoint in pre-clinical cancer cachexia drug evaluations.

Inhibition of activin-like kinase 4/5 attenuates cancer cachexia associated muscle wasting

Cancer mediated activation of the ActRIIB-ALK4/5 heterodimer by myostatin is strongly associated with muscle wasting. We investigated in vitro and in vivo the efficacy of ALK4/5 receptor blockers SB431542 and GW788388 in preventing muscle wasting, and explored synergy with IGF-I analogue LONG R3 (LR3) IGF-I. In vitro, C2C12 skeletal muscle cells were treated with vehicle, SB431542, GW788388 and LR3 IGF-I. A C26-CD2F1 cachexia model was used to induce cachexia in vivo. Mice were allocated as non-tumour bearing (NTB) or C26 tumour-bearing (C26 TB) vehicle control, treated with SB431542, LR3 IGF-I, SB431542 and LR3 IGF-I, or GW788388 (intraperitoneally or orally). In vitro, differentiation index and mean nuclei count increased using SB431542, GW788388, LR3 IGF-I. In vivo, GW788388 was superior to SB431542 in limiting loss of bodyweight, grip-strength and gastrocnemius weight. and downregulated Atrogin-1 expression comparable to NTB mice. LR3 IGF-I treatment limited loss of muscle mass, but at the expense of accelerated tumour growth. In conclusion, treatment with GW788388 prevented cancer cachexia, and downregulated associated ubiquitin ligase Atrogin-1.

Chronic Treatment with Multi-Kinase Inhibitors Causes Differential Toxicities on Skeletal and Cardiac Muscles

Despite recent progress, chemotherapy remains the preferred treatment for cancer. We have shown a link between anticancer drugs and the development of cachexia, i.e., body wasting accompanied by muscle loss. The multi-kinase inhibitors (MKIs) regorafenib and sorafenib, used as second-line treatment for solid tumors, are frequently accompanied by several side effects, including loss of muscle mass and strength. In the present study we aimed to investigate the molecular mechanisms associated with the occurrence of muscle toxicities in in vivo conditions. Hence, we treated 8-week old healthy CD2F1 male mice with MKIs for up to six weeks and observed decreased skeletal and cardiac muscle mass, consistent with muscle weakness. Modulation of ERK1/2 and GSK3β, as well as increased expression of markers of autophagy, previously associated with muscle atrophy conditions, were shown in skeletal muscle upon treatment with either drug. MKIs also promoted cardiac abnormalities consistent with reduced left ventricular mass, internal diameter, posterior wall thickness and stroke volume, despite unchanged overall function. Notably, different signaling pathways were affected in the heart, including reduced expression of mitochondrial proteins, and elevated AKT, GSK3β, mTOR, MEK1/2 and ERK1/2 phosphorylation. Combined, our data demonstrate detrimental effects on skeletal and cardiac muscle in association with chronic administration of MKIs, although different mechanisms would seem to contribute to the cachectic phenotype in the two tissues.

Understanding the Role of Exercise in Cancer Cachexia Therapy

Cachexia, the unintentional loss of body weight, is prevalent in many cancer types, and the associated skeletal muscle mass depletion increases patient morbidity and mortality. While anorexia can be present, cachexia is not reversible with nutritional therapies alone. Pharmacological agents have been proposed to treat this condition, but there are currently no approved treatments. Nonetheless, the hallmark characteristics associated with cancer cachexia remain viable foundations for future therapies. Regular physical activity holds a promising future as a nonpharmacological alternative to improve patient survival through cachexia prevention. Evidence suggests exercise training is beneficial during cancer treatment and survival. However, the mechanistic examination of cachectic skeletal muscle's response to exercise is both needed and justified. The primary objective of this review is to discuss the role of exercise for the prevention and treatment of cancer-associated muscle wasting. Initially, we provide an overview of systemic alterations induced by cancer and their role in the regulation of wasting processes during cachexia progression. We then discuss how exercise could alter disrupted regulatory pathways related to growth and metabolism during cancer-induced muscle atrophy. Last, we outline current exercise prescription guidelines and how exercise could be a potential behavioral therapy to curtail cachexia development in cancer patients.

Treating cachexia using soluble ACVR2B improves survival, alters mTOR localization, and attenuates liver and spleen responses

BACKGROUND

Cancer cachexia increases morbidity and mortality, and blocking of activin receptor ligands has improved survival in experimental cancer. However, the underlying mechanisms have not yet been fully uncovered.

METHODS

The effects of blocking activin receptor type 2 (ACVR2) ligands on both muscle and non-muscle tissues were investigated in a preclinical model of cancer cachexia using a recombinant soluble ACVR2B (sACVR2B-Fc). Treatment with sACVR2B-Fc was applied either only before the tumour formation or with continued treatment both before and after tumour formation. The potential roles of muscle and non-muscle tissues in cancer cachexia were investigated in order to understand the possible mechanisms of improved survival mediated by ACVR2 ligand blocking.

RESULTS

Blocking of ACVR2 ligands improved survival in tumour-bearing mice only when the mice were treated both before and after the tumour formation. This occurred without effects on tumour growth, production of pro-inflammatory cytokines or the level of physical activity. ACVR2 ligand blocking was associated with increased muscle (limb and diaphragm) mass and attenuation of both hepatic protein synthesis and splenomegaly. Especially, the effects on the liver and the spleen were observed independent of the treatment protocol. The prevention of splenomegaly by sACVR2B-Fc was not explained by decreased markers of myeloid-derived suppressor cells. Decreased tibialis anterior, diaphragm, and heart protein synthesis were observed in cachectic mice. This was associated with decreased mechanistic target of rapamycin (mTOR) colocalization with late-endosomes/lysosomes, which correlated with cachexia and reduced muscle protein synthesis.

CONCLUSIONS

The prolonged survival with continued ACVR2 ligand blocking could potentially be attributed in part to the maintenance of limb and respiratory muscle mass, but many observed non-muscle effects suggest that the effect may be more complex than previously thought. Our novel finding showing decreased mTOR localization in skeletal muscle with lysosomes/late-endosomes in cancer opens up new research questions and possible treatment options for cachexia.

eIF4A inhibition prevents the onset of cytokine-induced muscle wasting by blocking the STAT3 and iNOS pathways

Cachexia is a deadly muscle wasting syndrome that arises under conditions linked to chronic inflammation, such as cancer. Cytokines, including interferon γ (IFNγ), tumor necrosis factor α (TNFα) and interleukin-6 (IL-6), and their downstream effectors such as Signal Transducer and Activator of Transcription 3 (STAT3), have been shown to play a prominent role in muscle wasting. Previously, we demonstrated that Pateamine A (PatA), a compound that targets eukaryotic initiation factor 4A (eIF4A), could prevent muscle wasting by modulating the translation of the inducible Nitric Oxide Synthase (iNOS) mRNA. Here we show that hippuristanol, a compound that impedes eIF4A in a manner distinct from PatA, similarly inhibits the iNOS/NO pathway and cytokine-induced muscle wasting. Furthermore, we show that hippuristanol perturbs the activation of the STAT3 pathway and expression of STAT3-gene targets such as IL-6. The decreased activation of STAT3, which resulted from a decrease in STAT3 protein expression, was due to the inhibition of STAT3 translation as there were no changes in STAT3 mRNA levels. These effects are likely dependent on the inhibition of eIF4A activity since we observed similar results using PatA. Our results identify the inhibition of eIF4A-responsive transcripts, such as STAT3, as a viable approach to alleviate cachexia.

Animal models for cancer cachexia

PURPOSE OF REVIEW

Cancer cachexia is a frequent syndrome that affects patient quality of life, anticancer treatment effectiveness, and overall survival. The lack of anticancer cachexia therapies likely relies on the complexity of the syndrome that renders difficult to design appropriate clinical trials and, conversely, on the insufficient knowledge of the underlying pathogenetic mechanisms. The aim of this review is to collect the most relevant latest information regarding cancer cachexia with a special focus on the experimental systems adopted for modeling the disease in translational studies.

RECENT FINDINGS

The scenario of preclinical models for the study of cancer cachexia is not static and is rapidly evolving in parallel with new prospective treatment options. The well established syngeneic models using rodent cancer cells injected ectopically are now used alongside new ones featuring orthotopic injection, human cancer cell or patient-derived xenograft, or spontaneous tumors in genetically engineered mice.

SUMMARY

The use of more complex animal models that better resemble cancer cachexia, ideally including also the administration of chemotherapy, will expand the understanding of the underlying mechanisms and will allow a more reliable evaluation of prospective drugs for translational purposes.

Adaptive immune cells are necessary for the enhanced therapeutic effect of sorafenib-loaded nanoparticles

Sorafenib is a kinase inhibitor approved for the treatment of primary kidney cancer, advanced primary liver cancer, and radioactive iodine resistant advanced thyroid carcinoma.

Cancer-induced muscle wasting: latest findings in prevention and treatment

Cancer cachexia is a severe and disabling clinical condition that frequently accompanies the development of many types of cancer. Muscle wasting is the hallmark of cancer cachexia and is associated with serious clinical consequences such as physical impairment, poor quality of life, reduced tolerance to treatments and shorter survival. Cancer cachexia may evolve through different stages of clinical relevance, namely pre-cachexia, cachexia and refractory cachexia. Given its detrimental clinical consequences, it appears mandatory to prevent and/or delay the progression of cancer cachexia to its refractory stage by implementing the early recognition and treatment of the nutritional and metabolic alterations occurring during cancer. Research on the molecular mechanisms underlying muscle wasting during cancer cachexia has expanded in the last few years, allowing the identification of several potential therapeutic targets and the development of many promising drugs. Several of these agents have already reached the clinical evaluation, but it is becoming increasingly evident that a single therapy may not be completely successful in the treatment of cancer-related muscle wasting, given its multifactorial and complex pathogenesis. This suggests that early and structured multimodal interventions (including targeted nutritional supplementation, physical exercise and pharmacological interventions) are necessary to prevent and/or treat the devastating consequences of this cancer comorbidity, and future research should focus on this approach.

Dietary Supplementation with Isoflavones Prevents Muscle Wasting in Tumor-Bearing Mice

Proinflammatory cytokines contribute to the progression of muscle wasting caused by ubiquitin-proteasome-dependent proteolysis. We have previously demonstrated that isoflavones, such as genistein and daidzein, prevent TNF-α-induced muscle atrophy in C2C12 myotubes. In this study, we examined the effect of dietary flavonoids on the wasting of muscle. Mice were divided into the following four groups: vehicle-injected (control) mice fed the normal diet (CN); tumor-bearing mice fed the normal diet (TN); control mice fed the isoflavone diet (CI); and tumor-bearing mice fed the isoflavone diet (TI). There were no significant differences in the intake of food or body weight gain among these four groups. The wet weight and myofiber size of gastrocnemius muscle in TN significantly decreased, compared with those in CN. Interestingly, the wet weight and myofiber size of gastrocnemius muscle in TI were nearly the same as those in CN and CI, although isoflavone supplementation did not affect the increased tumor mass or concentrations of proinflammatory cytokines, such as TNF-α and IL-6, in the blood. Moreover, increased expression of muscle-specific ubiquitin ligase genes encoding MAFbx/Atrogin-1 and MuRF1 in the skeletal muscle of TN was significantly inhibited by the supplementation of isoflavones. In parallel with the expression of muscle-specific ubiquitin ligases, dietary isoflavones significantly suppressed phosphorylation of ERK in tumor-bearing mice. These results suggest that dietary isoflavones improve muscle wasting in tumor-bearing mice via the ERK signaling pathway mediated-suppression of ubiquitin ligases in muscle cells.

Differential Bone Loss in Mouse Models of Colon Cancer Cachexia

Cachexia is a distinctive feature of colorectal cancer associated with body weight loss and progressive muscle wasting. Several mechanisms responsible for muscle and fat wasting have been identified, however it is not known whether the physiologic and molecular crosstalk between muscle and bone tissue may also contribute to the cachectic phenotype in cancer patients. The purpose of this study was to clarify whether tumor growth associates with bone loss using several experimental models of colorectal cancer cachexia, namely C26, HT-29, and Apc^Min/+. The effects of cachexia on bone structure and strength were evaluated with dual energy X-ray absorptiometry (DXA), micro computed tomography (μCT), and three-point bending test. We found that all models showed tumor growth consistent with severe cachexia. While muscle wasting in C26 hosts was accompanied by moderate bone depletion, no loss of bone strength was observed. However, HT-29 tumor bearing mice showed bone abnormalities including significant reductions in whole-body bone mineral density (BMD), bone mineral content (BMC), femoral trabecular bone volume fraction (BV/TV), trabecular number (Tb.N), and trabecular thickness (Tb.Th), but no declines in strength. Similarly, cachexia in the Apc^Min/+ mice was associated with significant decreases in BMD, BMC, BV/TV, Tb.N, and Tb.Th as well as decreased strength. Our data suggest that colorectal cancer is associated with muscle wasting and may be accompanied by bone loss dependent upon tumor type, burden, stage and duration of the disease. It is clear that preserving muscle mass promotes survival in cancer cachexia. Future studies will determine whether strategies aimed at preventing bone loss can also improve outcomes and survival in colorectal cancer cachexia.

Selumetinib Attenuates Skeletal Muscle Wasting in Murine Cachexia Model through ERK Inhibition and AKT Activation

Cancer cachexia is a multifactorial syndrome affecting the skeletal muscle. Previous clinical trials showed that treatment with MEK inhibitor selumetinib resulted in skeletal muscle anabolism. However, it is conflicting that MAPK/ERK pathway controls the mass of the skeletal muscle. The current study investigated the therapeutic effect and mechanisms of selumetinib in amelioration of cancer cachexia. The classical cancer cachexia model was established via transplantation of CT26 colon adenocarcinoma cells into BALB/c mice. The effect of selumetinib on body weight, tumor growth, skeletal muscle, food intake, serum proinflammatory cytokines, E3 ligases, and MEK/ERK-related pathways was analyzed. Two independent experiments showed that 30 mg/kg/d selumetinib prevented the loss of body weight in murine cachexia mice. Muscle wasting was attenuated and the expression of E3 ligases, MuRF1 and Fbx32, was inhibited following selumetinib treatment of the gastrocnemius muscle. Furthermore, selumetinib efficiently reduced tumor burden without influencing the cancer cell proliferation, cumulative food intake, and serum cytokines. These results indicated that the role of selumetinib in attenuating muscle wasting was independent of cancer burden. Detailed analysis of the mechanism revealed AKT and mTOR were activated, while ERK, FoxO3a, and GSK3β were inhibited in the selumetinib -treated cachexia group. These indicated that selumetinib effectively prevented skeletal muscle wasting in cancer cachexia model through ERK inhibition and AKT activation in gastrocnemius muscle via cross-inhibition. The study not only elucidated the mechanism of MEK/ERK inhibition in skeletal muscle anabolism, but also validated selumetinib therapy as an effective intervention against cancer cachexia. Mol Cancer Ther; 16(2); 334-43. ©2016 AACR.

The emerging role of skeletal muscle oxidative metabolism as a biological target and cellular regulator of cancer-induced muscle wasting

While skeletal muscle mass is an established primary outcome related to understanding cancer cachexia mechanisms, considerable gaps exist in our understanding of muscle biochemical and functional properties that have recognized roles in systemic health. Skeletal muscle quality is a classification beyond mass, and is aligned with muscle's metabolic capacity and substrate utilization flexibility. This supplies an additional role for the mitochondria in cancer-induced muscle wasting. While the historical assessment of mitochondria content and function during cancer-induced muscle loss was closely aligned with energy flux and wasting susceptibility, this understanding has expanded to link mitochondria dysfunction to cellular processes regulating myofiber wasting. The primary objective of this article is to highlight muscle mitochondria and oxidative metabolism as a biological target of cancer cachexia and also as a cellular regulator of cancer-induced muscle wasting. Initially, we examine the role of muscle metabolic phenotype and mitochondria content in cancer-induced wasting susceptibility. We then assess the evidence for cancer-induced regulation of skeletal muscle mitochondrial biogenesis, dynamics, mitophagy, and oxidative stress. In addition, we discuss environments associated with cancer cachexia that can impact the regulation of skeletal muscle oxidative metabolism. The article also examines the role of cytokine-mediated regulation of mitochondria function, followed by the potential role of cancer-induced hypogonadism. Lastly, a role for decreased muscle use in cancer-induced mitochondrial dysfunction is reviewed.

Novel investigational drugs mimicking exercise for the treatment of cachexia

INTRODUCTION

Cachexia is a syndrome characterized by body weight loss, muscle wasting and metabolic abnormalities, that frequently complicates the management of people affected by chronic diseases. No effective therapy is actually available, although several drugs are under clinical evaluation. Altered energy metabolism markedly contributes to the pathogenesis of cachexia; it can be improved by exercise, which is able to both induce anabolism and inhibit catabolism.

AREAS COVERED

This review focuses on exercise mimetics and their potential inclusion in combined protocols to treat cachexia. The authors pay with particular reference to the cancer-associated cachexia.

EXPERT OPINION

Even though exercise improves muscle phenotype, most patients retain sedentary habits which are quite difficult to disrupt. Moreover, they frequently present with chronic fatigue and comorbidities that reduce exercise tolerance. For these reasons, drugs mimicking exercise could be beneficial to those who are unable to comply with the practice of physical activity. Since some exercise mimetics may exert serious side effects, further investigations should focus on treatments which maintain their effectiveness on muscle phenotype while remaining tolerable at the same time.

Experimental cancer cachexia: Evolving strategies for getting closer to the human scenario

Cancer cachexia is a frequent syndrome that dramatically affects patient quality of life, anti-cancer treatment effectiveness, and overall survival. To date, no effective treatment is available and most of the studies are performed in experimental models in order to uncover the underlying mechanisms and to design prospective therapeutic strategies. This review summarizes the most relevant information regarding the use of animal models for studying cancer cachexia. Technical limitations and degree of recapitulation of the features of human cachexia are highlighted, in order to help investigators choose the most suitable model according to study-specific endpoints.