Low expression of ELOVL6 may be involved in fat loss in white adipose tissue of cancer-associated cachexia.

BACKGROUND: Cancer-associated cachexia (CAC) arises from malignant tumors and leads to a debilitating wasting syndrome. In the pathophysiology of CAC, the depletion of fat plays an important role. The mechanisms of CAC-induced fat loss include the enhancement of lipolysis, inhibition of lipogenesis, and browning of white adipose tissue (WAT). However, few lipid-metabolic enzymes have been reported to be involved in CAC. This study hypothesized that ELOVL6, a critical enzyme for the elongation of fatty acids, may be involved in fat loss in CAC. METHODS: Transcriptome sequencing technology was used to identify CAC-related genes in the WAT of a CAC rodent model. Then, the expression level of ELOVL6 and the fatty acid composition were analyzed in a large clinical sample. Elovl6 was knocked down by siRNA in 3T3-L1 mouse preadipocytes to compare with wild-type 3T3-L1 cells treated with tumor cell conditioned medium. RESULTS: In the WAT of patients with CAC, a significant decrease in the expression of ELOVL6 was found, which was linearly correlated with the extent of body mass reduction. Gas chromatographic analysis revealed an increase in palmitic acid (C16:0) and a decrease in linoleic acid (C18:2n-6) in these tissue samples. After treatment with tumor cell-conditioned medium, 3T3-L1 mouse preadipocytes showed a decrease in Elovl6 expression, and Elovl6-knockdown cells exhibited a reduction in preadipocyte differentiation and lipogenesis. Similarly, the knockdown of Elovl6 in 3T3-L1 cells resulted in a significant increase in palmitic acid (C16:0) and a marked decrease in oleic acid (C18:1n-9) content. CONCLUSION: Overall, the expression of ELOVL6 was decreased in the WAT of CAC patients. Decreased expression of ELOVL6 might induce fat loss in CAC patients by potentially altering the fatty acid composition of adipocytes. These findings suggest that ELOVL6 may be used as a valuable biomarker for the early diagnosis of CAC and may hold promise as a target for future therapies.

Phosphatidylethanolamine (18:2e/18:2) may inhibit adipose tissue wasting in patients with cancer cachexia by increasing lysophosphatidic acid receptor 6.

BACKGROUND: Cancer associated cachexia is characterized by the significant loss of adipose tissue, leading to devastating weight loss and muscle wasting in the majority of cancer patients. The effects and underlying mechanisms of degradation metabolites on adipocytes in cachectic patients remain poorly understood. To address this knowledge gap, we conducted a comprehensive study combining lipidomic analysis of subcutaneous and visceral adipose tissue with transcriptomics data from the database to investigate the mechanisms of lipid regulation in adipocytes. METHODS: We collected subcutaneous and visceral adipose tissue samples from cachectic and noncachectic cancer patients. Lipidomic analysis was performed to identify differentially expressed lipids in both types of adipose tissue. Additionally, transcriptomics data from the GEO database were analyzed to explore gene expression patterns in adipocytes. Bioinformatics analysis was employed to determine the enrichment of differentially expressed genes in specific pathways. Furthermore, molecular docking studies were conducted to predict potential protein targets of specific lipids, with a focus on the PI3K-Akt signaling pathway. Western blot analysis was used to validate protein levels of the identified target gene, lysophosphatidic acid receptor 6 (LPAR6), in subcutaneous and visceral adipose tissue from cachectic and noncachectic patients. RESULTS: Significant lipid differences in subcutaneous and visceral adipose tissue between cachectic and noncachectic patients were identified by multivariate statistical analysis. Cachectic patients exhibited elevated Ceramides levels and reduced CerG2GNAc1 levels (P < 0.05). A total of 10 shared lipids correlated with weight loss and IL-6 levels, enriched in Sphingolipid metabolism, GPI-anchor biosynthesis, and Glyceropholipid metabolism pathways. LPAR6 expression was significantly elevated in both adipose tissues of cachectic patients (P < 0.05). Molecular docking analysis indicated strong binding of Phosphatidylethanolamine (PE) (18:2e/18:2) to LPAR6. CONCLUSIONS: Our findings suggest that specific lipids, including PE(18:2e/18:2), may mitigate adipose tissue wasting in cachexia by modulating the expression of LPAR6 through the PI3K-Akt signaling pathway. The identification of these potential targets and mechanisms provides a foundation for future investigations and therapeutic strategies to combat cachexia. By understanding the underlying lipid regulation in adipocytes, we aim to develop targeted interventions to ameliorate the devastating impact of cachexia on patient outcomes and quality of life. Nevertheless, further studies and validation are warranted to fully elucidate the intricate mechanisms involved and translate these findings into effective clinical interventions.

Immune landscape and prognostic gene signatures in gastric cancer: implications for cachexia and clinical outcomes.

Cachexia, a debilitating condition that worsens patient outcomes, often accompanies gastric cancer, a malignancy that is prevalent worldwide. The extensive research explored the interconnected molecular and immune aspects of stomach cancer, with a particular emphasis on cachexia. By employing the GEO database, we identified genes that were expressed differently in gastric cancer patients suffering from cachexia. Following the analysis of Weighted Gene Co-expression Network (WGCNA), gene modules intricately linked to particular immune cells were revealed, indicating a significantly disrupted tumor microenvironment. A strong predictive model was developed, centered around key genes such as CAMK4, SLC37A2, and BCL11B. Surprisingly, this particular model not only showed better predictive abilities in comparison to conventional clinical factors but also exhibited a strong connection with increased infiltration of macrophages and T cells. These discoveries suggest the presence of an immune-suppressing and tumor-promoting atmosphere among individuals at a greater risk. Moreover, the utilization of Gene Set Enrichment Analysis (GSEA) established a connection between the genes linked to our risk score and vital immune-related pathways, thereby strengthening the pivotal involvement of immunity in the development of gastric cancer. To summarize, our discoveries provide a more profound comprehension of the molecular and immune mechanisms that support cachexia in gastric cancer, presenting a hopeful basis for upcoming advancements in treatment.

Sarcopenia and myosteatosis diagnostic tool for gastrointestinal cancer: creatinine to cystatin C ratio as evaluation marker.

OBJECTIVE: This study aimed to develop a simplified diagnostic tool for assessing sarcopenia and myosteatosis in gastrointestinal cancer patients, focusing on the creatinine to cystatin C ratio (CCR) as an evaluation marker. METHODS: 955 patients were split into training (n = 671) and validation (n = 284) cohorts. Using logistic regression, risk factors for sarcopenia and myosteatosis were identified. The predictive capacity of the developed model was examined. The association between CCR and muscle imaging parameters, along with its impact on clinical outcomes, was analyzed. RESULTS: No significant differences were observed in baseline traits between cohorts. CCR emerged as a significant risk factor for both sarcopenia and myosteatosis. Nomograms for diagnosing these conditions demonstrated strong predictive ability, with AUC values indicating high accuracy (sarcopenia AUC: 0.865-0.872; myosteatosis AUC: 0.848-0.849). The clinical utility of the nomograms was confirmed through decision curve analysis. CCR showed significant association with muscle imaging parameters and was a reliable indicator for assessing the risk of sarcopenia, myosteatosis, and cachexia. Moreover, CCR was able to differentiate between patient survival and disease progression rates. CONCLUSION: A diagnostic tool for sarcopenia and myosteatosis in gastrointestinal cancer patients was developed, with CCR being a pivotal biomarker for disease diagnosis and prognosis prediction.

Genome-Wide Analyses of Thaumatin-like Protein Family Genes Reveal the Involvement in the Response to Low-Temperature Stress in Ammopiptanthus nanus.

Thaumatin-like proteins (TLPs), a family of proteins with high sequence similarity to thaumatin, are shown to be involved in plant defense, and are thus classified into the pathogenesis related protein family 5. Ammopiptanthus nanus is a rare evergreen broad-leaved shrub distributed in the temperate zone of Central Asia, which has a high tolerance to low-temperature stress. To characterize A. nanus TLPs and understand their roles in low-temperature response in A. nanus, a comprehensive analysis of the structure, evolution, and expression of TLP family proteins was performed. A total of 31 TLP genes were detected in the A. nanus genome, and they were divided into four groups based on their phylogenetic positions. The majority of the AnTLPs contained the conserved cysteine residues and were predicted to have the typical three-dimensional structure of plant TLPs. The primary modes of gene duplication of the AnTLP family genes were segmental duplication. The promoter regions of most AnTLP genes contain multiple cis-acting elements related to environmental stress response. Gene expression analysis based on transcriptome data and fluorescence quantitative PCR analysis revealed that several AnTLP genes were involved in cold-stress response. We further showed that a cold-induced AnTLP gene, AnTLP13, was localized in apoplast, and heterologous expression of the AnTLP13 in Escherichia coli and yeast cells and tobacco leaves enhanced low-temperature stress tolerance when compared with the control cells or seedlings. Our study provided important data for understanding the roles of TLPs in plant response to abiotic stress.

DUSP1 promotes muscle atrophy by inhibiting myocyte differentiation in cachectic patients.

Background: Skeletal muscle atrophy is the major hallmark of cancer cachexia. The mechanisms underlying muscle wasting remain elusive in cachectic patients. Our research seeks to identify differentially expressed genes (DEGs) between non-cachectic and cachectic cancer patients and elucidate their functions. Methods: We screened the DEGs of skeletal muscle between patients with and without cachexia from microarray data. Biological function of DEGs is analyzed through gene enrichment analysis, while an interaction network is constructed to visualize how genes are related. A Spearman's correlation analysis demonstrated the clinical significance of DUSP1 related to cancer cachexia. Skeletal muscle samples were collected and histomorphology studies were conducted. Function of DUSP1 on myogenesis was clarified by qPCR, western blotting, and immunofluorescence. Results: We screened 324 DEGs in skeletal muscle from patients with and without cachexia. The results of the gene enrichment analysis indicated that inflammatory cytokines and immune responses contribute significantly to the pathological condition of cachexia. DUSP1 was one of the key genes in the regulating network. DUSP1 protein and mRNA levels were increased significantly in skeletal muscle tissues from patients with cancer cachexia. DUSP1 expression in cachectic group was found to have negative correlation with SMA, prealbumin and BMI and positive correlation with TNFα, IL6 and weight loss. Significant changes of myogenesis related genes were observed in myocyte after DUSP1 was overexpressed and knocked down. Conclusion: In skeletal muscle of cachectic patients, DUSP1 expression was observed to be higher and thus DUSP1 promote muscle atrophy by inhibiting myogenesis. DUSP1 is expected to be a specific target in cancer cachexia for preventing and treating muscle atrophy.

Phosphorylation of Dynamin-Related Protein 1 (DRP1) Regulates Mitochondrial Dynamics and Skeletal Muscle Wasting in Cancer Cachexia.

BACKGROUND: Cancer-associated cachexia (CAC) is a syndrome characterized by skeletal muscle atrophy, and the underlying mechanisms are still unclear. Recent research studies have shed light on a noteworthy link between mitochondrial dynamics and muscle physiology. In the present study, we investigate the role of dynamin-related protein 1 (DRP1), a pivotal factor of mitochondrial dynamics, in myotube atrophy during cancer-associated cachexia. METHODS: Seventy-six surgical patients, including gastrointestinal tumor and benign disease, were enrolled in the study and divided to three groups: control, non-cachexia, and cancer-associated cachexia. Demographic data were collected. Their rectus abdominis samples were acquired intraoperatively. Muscle fiber size, markers of ubiquitin proteasome system (UPS), mitochondrial ultrastructure, and markers of mitochondrial function and dynamics were assayed. A cachexia model in vitro was established via coculturing a C2C12 myotube with media from C26 colon cancer cells. A specific DRP1 inhibitor, Mdivi-1, and a lentivirus of DRP1 knockdown/overexpression were used to regulate the expression of DRP1. Muscle diameter, mitochondrial morphology, mass, reactive oxygen species (ROS), membrane potential, and markers of UPS, mitochondrial function, and dynamics were determined. RESULTS: Patients of cachexia suffered from a conspicuous worsened nutrition status and muscle loss compared to patients of other groups. Severe mitochondrial swelling and enlarged area were observed, and partial alterations in mitochondrial function were found in muscle. Analysis of mitochondrial dynamics indicated an upregulation of phosphorylated DRP1 at the ser616 site. In vitro, cancer media resulted in the atrophy of myotube. This was accompanied with a prominent unbalance of mitochondrial dynamics, as well as enhanced mitochondrial ROS and decreased mitochondrial function and membrane potential. However, certain concentrations of Mdivi-1 and DRP1 knockdown rebalanced the mitochondrial dynamics, mitigating this negative phenotype caused by cachexia. Moreover, overexpression of DRP1 aggravated these phenomena. CONCLUSION: In clinical patients, cachexia induces abnormal mitochondrial changes and possible fission activation for the atrophied muscle. Our cachexia model in vitro further demonstrates that unbalanced mitochondrial dynamics contributes to this atrophy and mitochondrial impairment, and rebuilding the balance by regulating of DRP1 could ameliorate these alterations.

Novel noncoding RNA CircPTK2 regulates lipolysis and adipogenesis in cachexia.

OBJECTIVE: Cancer-associated cachexia is a devastating pathological disorder characterized by skeletal muscle wasting and fat storage depletion. Circular RNA, a newly discovered class of noncoding RNAs with important roles in regulating lipid metabolism, has not been fully understood in the pathology of cachexia. We aimed to identify circular RNAs that are upregulated in adipose tissues from cachectic patients and explore their function and mechanism in lipid metabolism. METHODS: Whole transcriptome RNA sequencing was used to screen for differentially expressed circRNAs. Quantitative reverse transcription PCR was applied to detect the expression level of circPTK2 in adipose tissues. The diagnostic value of circPTK2 was evaluated in adipose tissues from patients with and without cachexia. Then, function experiments in vitro and in vivo were performed to evaluate the effects of circPTK2 on lipolysis and adipogenesis. Mechanistically, luciferase reporter assay, RNA immunoprecipitation, and fluorescent in situ hybridization were performed to confirm the interaction between circPTK2 and miR-182-5p in adipocytes. RESULTS: We detected 66 differentially expressed circular RNA candidates and proved that circPTK2 was upregulated in adipose tissues from cachectic patients. Then we identified that circPTK2 was closely related to the pathological process of cachexia and could be used as a diagnostic marker. Mechanistically, circPTK2 bound competitively to miR-182-5p and abrogated the suppression on its target gene JAZF1, which finally led to promotion of lipolysis and inhibition of adipogenesis. In vivo experiments demonstrated that overexpression of circPTK2 inhibited adipogenesis and enhanced lipolysis. CONCLUSIONS: Our findings reveal the novel role of circPTK2 in promoting lipolysis and reducing adipogenesis via a ceRNA mechanism and provide a potential diagnostic biomarker and therapeutic target for cancer-associated cachexia.

Regulation of dynamin-related protein 1 (DRP1) levels modulates myoblast atrophy induced by C26 colon cancer-conditioned medium.

BACKGROUND: Cancer associated-cachexia, which involves progressive skeletal muscle loss, is induced by multiple factors. However, the underlying mechanism remains unclear. Dynamin-related protein 1 (DRP1), a major modulator of mitochondrial fission, has been reported to participate in muscle turnover. This study aimed to explore the role of DRP1 in muscle during the process of cancer associated-cachexia (CAC) via an in vitro model and the mechanisms involved. METHODS: C26 colon cancer cell-conditioned medium (CM) was used to incubate with C2C12 myotubes to simulate cachexia. Myotubes were then transduced with lentiviral vectors of DRP1-small interfering RNA (siRNA), DRP1 overexpression plasmid, or a control plasmid to regulate the DRP1 levels, and their diameters were assessed using a biological microscope. Furthermore, transcriptome sequencing was performed to screen the pathways involved, and real-time polymerase chain reaction (RT-PCR) was used for verification. RESULTS: The cachexia model was successfully established with a decreased myotube diameter and increased DRP1 expression. DRP1 knockdown significantly ameliorated myotube wasting during cachexia, while DRP1 overexpression intensified this phenomenon. Transcriptome sequencing indicated that DRP1 knockdown was associated with the activation of ribosomal biogenesis. However, PCR results showed that compared to the control, one of the ribosomal biogenesis marker's (Ubf) level was decreased by C26 CM, and DRP1 knockdown did not significantly restore its level. CONCLUSIONS: During C26 CM-induced cachexia, DRP1 was activated, while the regulation of DRP1 levels was able to modulate the atrophy of C2C12 myotubes. The underlying mechanism of the alleviated muscle atrophy induced by DRP1 knockdown was likely associated with increased ribosomal activity.

Impact of oral nutritional supplements in post-discharge patients at nutritional risk following colorectal cancer surgery: A randomised clinical trial.

BACKGROUND & AIMS: Guidelines on clinical nutrition recommend the use of appropriate nutritional support therapy for surgical cancer patients at risk of malnutrition both during hospital care and following discharge from the hospital. However, previous studies regarding nutritional interventions have mainly focused on patients during their hospital stay; there is limited evidence supporting the recommendation of nutritional interventions for post-discharge patients after cancer surgery, particularly those who underwent gastrointestinal cancer surgery and at high risk of malnutrition. To clearly address this issue, we designed and conducted two independent studies on two different groups of post-discharge patients at nutritional risk after gastrointestinal cancer surgery. The present study aimed to assess the impact of oral nutritional supplements (ONS) in post-discharge patients at nutritional risk following colorectal cancer surgery. Meanwhile, the sister study on the use of ONS in post-discharge patients following gastric cancer surgery will be reported separately. METHODS: Between January 2017 and June 2019, post-discharge patients following colorectal cancer surgery in our institution were randomised to receive either dietary advice alone (control group) or dietary advice in combination with ONS (ONS group) for three months if they were at nutritional risk based on the tool of Nutritional Risk Screening 2002. The primary endpoints were nutritional outcomes and sarcopenia prevalence. The secondary endpoints were 90-day readmission rate, chemotherapy tolerance, and quality of life (QoL). RESULTS: Of the 232 eligible patients, 212 (107 in the control group and 105 in the ONS group) completed the trial. Their data were then analyzed. The mean ONS intake was 410 mL every day. By the three-month intervention, the skeletal muscle index in the ONS group was significantly higher than that in the control group (39.75 ± 5.83 vs 38.01 ± 6.18 cm2/m2, P = 0.037), but no significant differences between the two groups were noted in weight, weight loss, body mass index, serum albumin and hemoglobin (P > 0.05). In addition, the ONS group had a significantly lower sarcopenia prevalence (28.6% vs 42.1%, P = 0.040). No significant difference between the two groups was found in the 90-day readmission rate (P > 0.05). The number of patients undergoing postoperative chemotherapy in the two groups was similar, but chemotherapy modifications, such as delay, dose reduction, or termination, were significantly reduced in the ONS group (21.2% vs 36.8%, P=0.024). However, ONS had no significant effect on QoL (P > 0.05). CONCLUSIONS: In post-discharge patients at nutritional risk following colorectal cancer surgery, the use of ONS may reduce skeletal muscle loss and sarcopenia prevalence, as well as improve chemotherapy tolerance, compared with dietary advice alone. These findings underline the importance of ONS treatment in post-discharge patients at nutritional risk following colorectal cancer surgery.

Sarcopenia as a predictor of poor surgical and oncologic outcomes after abdominal surgery for digestive tract cancer: A prospective cohort study.

BACKGROUND & AIMS: Sarcopenia has been widely recognized as an important predictor of poor outcomes in patients with cancer after surgery, but the controversy remains, and its impact on surgical and oncologic outcomes in patients after abdominal surgery for digestive tract cancer is poorly described. The aim of this study was to evaluate the prognostic impact of sarcopenia on surgical and oncologic outcomes in patients after abdominal surgery for digestive tract cancer. METHODS: Six thousand four hundred and forty-seven consecutive patients who underwent abdominal surgery for digestive tract cancer in our institution were prospectively included. Sarcopenia was defined as skeletal muscle index below the lowest sex-specific quartile using computed tomography scan at L3 before surgery. The surgical and oncologic outcomes were recorded, and univariate and multivariate analyses were performed. RESULTS: Sarcopenia was present in 1638 of 6447 patients (25.4%) with digestive tract cancer before surgery based on the diagnostic cut-off values (43.13 cm2/m2 for men and 37.81 cm2/m2 for women). The incidence of postoperative total and pulmonary complications, and 30-day readmission were significantly higher in sarcopenic group than in nonsarcopenic group (37.4% vs 12.9%, P < 0.001; 3.1% vs 2.1%, P = 0.026; 1.1% vs 0.4%, P = 0.003, respectively). The postoperative hospital stay was significantly longer in sarcopenic patients (9.42 ± 3.40 vs 8.51 ± 3.17 days, P < 0.001). There were significantly more patients receiving postoperative chemotherapy or radiotherapy in sarcopenic group than in nonsarcopenic group (73.1% vs 69.2%, P = 0.003; 10.6% vs 8.8%, P = 0.038, respectively), and patients with sarcopenia had significantly more chemotherapy modifications including delay, dose reduction, or termination (48.5% vs 44.2%, P = 0.018). In addition, during the follow-up period, sarcopenic patients had significantly lower rate of overall survival and disease-free survival than nonsarcopenic patients (53.9% vs 69.3%, P = 0.002; 36.8% vs 59.7%, P = 0.000, respectively). In multivariate analysis, sarcopenia was found to be a risk factor for postoperative complications [odds ratio (OR) = 5.418, 95% confidence interval (CI) = 2.986-9.828, P < 0.001], and was an unfavorable prognostic factor for poor overall survival [hazard ratio (HR) = 0.649, 95% CI = 0.426-0.991, P = 0.045] and disease-free survival (HR = 0.514, 95% CI = 0.348-0.757, P = 0.001). CONCLUSIONS: Sarcopenia could be used as a strong and independent prognostic factor for poor surgical and oncologic outcomes in patients after abdominal surgery for digestive tract cancer. Identification of preoperative sarcopenia in digestive surgery for cancer and targeted approaches may improve its negative outcomes.