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Identification of circulating protein biomarkers for pancreatic cancer cachexia

ABSTRACT: Over 80% of patients with pancreatic ductal adenocarcinoma (PDAC) suffer from cachexia, characterized by severe muscle and fat loss and yet, there are no biomarkers identified for this debilitating condition. Our objective was to identify circulating protein biomarkers using serum for human PDAC cachexia and understand their biological functions. Serum from 30 patients with PDAC was collected and protein profiles were generated using SOMAscan. The protein profiles were correlated with clinical variables such as Cancer associated weight loss (CAWL), body composition measurements of skeletal muscle index (SMI), skeletal muscle density (SMD), total adipose index (TAI) using Spearman’s correlation. Overall, 110 proteins of 1294 correlated with these clinical measures - 47 proteins for CAWL, 19 for SMI, 14 for SMD, and 30 for TAI (r-value 0.5, p<0.05). LYVE1, a homolog of CD44 implicated in tumor metastasis, was the top CAWL-associated protein (r= 0.67, p=0.0001). Protein co-expression network analysis identified immune system related pathways such as B-cell signaling, natural killer cell signaling, IL6 signaling in addition to identifying other known pathways in cachexia. Taken together, these data identify both immune system molecules and additional secreted factors and pathways not previously associated with PDAC and confirm the activation of previously identified pathways.

ORGANISM(S): Homo sapiens

PROVIDER: GSE119483 | GEO | 2020/12/31

REPOSITORIES: GEO

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Project description:Background. Pancreatic Ductal AdenoCarcinoma (PDAC), the most frequent pancreatic cancer, is a deadly cancer since often diagnosed late and resistant to current therapies. A high proportion of PDAC patients are affected by cachexia induced by the tumor. This cachexia, characterized by loss of muscle mass and strength, contributes to patient frailty and poor therapeutic response. We showed that mitochondrial metabolism is reprogrammed in PDAC tumor cell and constitutes a vulnerability, opening novel therapeutic avenues. The objective of the present work was to investigate the molecular mechanisms underlying mitochondrial remodeling in PDAC cachectic skeletal muscle. Methods. Our study focused on the gastrocnemius muscle of genetically-engineered mice developing spontaneously a PDAC associated with cachexia (KIC GEMM). We compared KIC mice developing a pancreatic tumor in 9-10 weeks to control littermates. We did an integrative study combining in vivo functional analyses by non-invasive Magnetic Resonance, and ex-vivo histology, Seahorse, RNA-sequencing, and proteomic mass spectrometry and western blotting analyses. Results. The cachectic KIC PDAC mice show a severe sarcopenia with loss of muscle mass and strength associated with a diminution in muscle fiber’s size and induction of protein degradation processes. Mitochondria in PDAC atrophic muscles show decreased respiratory capacities and structural alterations (“hyperfused” mitochondria), associated with deregulation of oxidative phosphorylation and mitochondrial dynamics pathways at the molecular level. Increased expression of multiple reactive oxygen species (ROS) defense genes suggests oxidative stress prone to affect mitochondrial macromolecules and homeostasis. Interestingly, multiple genes and proteins involved in DNA metabolism pathways, such as DNA damage, degradation of DNA, nucleotide synthesis, and folate pathway were found altered in sarcopenic mitochondria. While the number of mitochondria was not changed, the mitochondrial mass was decreased by a factor of 2 and the mitochondrial DNA by a factor of 3, suggesting a defect in mitochondrial genome homeostasis. Conclusions. We unveiled that mitochondrial alterations in skeletal muscle play a central role in PDAC-induced cachexia. Muscle atrophy is associated with strong mitochondrial metabolic defects that are not limited to carbohydrates and protein, but concern also lipids, ROS and nucleic acids. Our data provide a frame to guide towards the most relevant molecular markers that would be affected at the start of tumor development and could be targets in the clinic to limit PDAC-induced cachexia at early stages of the pathology.

Project description:Background Loss of skeletal muscle mass in advanced cancer is recognized as an independent predictor of mortality. Mechanisms involved in this wasting process and parameters for early diagnosis are still lacking. As skeletal muscle is considered as a secretory organ, the aim of this present experimental work was to characterize the changes in muscle proteome and secretome associated with cancer-induced cachexia to better understand cellular mechanisms involved in this wasting process and to identify secreted proteins which might reflect the ongoing muscle atrophy process. Methods We investigated first the changes in the muscle proteome associated with cancer-induced cachexia by using differential label-free proteomic analysis on muscle of the C26 mouse model. The differentially abundant proteins were submitted to sequential bioinformatic secretomic analysis in order to identify potentially secreted proteins. Selected reaction monitoring and Western blotting were used to verify the presence of candidate proteins at the circulating level. Their muscle source was demonstrated by assessing their gene expression in skeletal muscle and in cultured myotubes. Finally, we also investigated their regulation in muscle cells. Alterations in several molecular pathways potentially involved in muscle atrophy were highlighted using Gene ontology enrichment analyses. Results Our results revealed a dramatic increased production (2-to 25-fold) by the muscle of several acute phase reactants (APR: Haptoglobin, Serpina3n, Complement C3, Serum amyloid A1) which are also released in the circulation during C26 cancer cachexia. Their production was confirmed in other preclinical models of cancer cachexia as well as in cancer patients. The muscular origin of these APR was demonstrated by their increased expression in skeletal muscle and myotubes. Glucocorticoids and pro-inflammatory cytokines contribute directly to their increased expression in muscle cells in vitro, while the role of IL-6 in the muscular induction of these APR was demonstrated in vivo. Conclusions Cancer is associated with marked changes in muscle secretome during muscle wasting. Our study demonstrates a marked increased production of APR by skeletal muscle in pre-clinical models of cancer cachexia and in cancer patients. Further studies are required to unravel the potential role of these proteins in muscle atrophy and their interest as biomarkers of cancer cachexia.

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Identification of circulating protein biomarkers for pancreatic cancer cachexia

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