PPARδ agonist enhances colitis-associated colorectal cancer

GW501516 facilitated tumor immune escape by inhibiting phagocytosis

The CD47/SIRPα innate immune checkpoint plays a critical role in regulating tumor immune escape. GW501516, a peroxisome proliferator-activated receptor delta (PPARδ) agonist, is known to promote cancer cell metabolism, proliferation, and inflammation; however, its regulatory mechanism in colon tumor immune escape remains unclear. In this study, qPCR analysis revealed that GW501516 treatment upregulated CD47 gene expression in colon cancer cells. Additionally, GW501516 increased membrane-associated CD47 protein levels in these cells. Mechanistically, luciferase reporter assays demonstrated that GW501516 enhanced CD47 gene transcription activity in colon cancer cells. Co-culture experiments with macrophages further showed that GW501516 treatment suppressed macrophage phagocytic capacity. Crucially, PPARδ knockout abolished GW501516-induced CD47 expression, indicating PPARδ dependency. In vivo implanted tumor models demonstrated that GW501516 facilitated tumor immune escape, whereas PPARδ loss reversed this effect. Collectively, these findings suggest that GW501516 activates PPARδ to promote colon tumor immune escape via CD47 upregulation.

Regulatory role of PPAR in colorectal cancer

Colorectal cancer (CRC) is one of the most common tumors in the digestive system, and the majority of patients are found to be in advanced stages, which is a burden to human health all over the world. Moreover, in recent years, CRC has been progressively becoming younger, with an increasing incidence mainly among patients <50 years old. Despite the increase in awareness of CRC and the continuous improvement of medical treatment nowadays, the challenge of CRC still needs to be conquered. By now, the pathogenesis of CRC is complex and not fully understood. With the deepening of research, it has been revealed that PPARs, as a transcription factor, are inextricably linked to CRC. This article outlines the mechanisms by which PPARs are involved in CRC development. An in-depth understanding of the pathways related to PPARs may provide new ways of developing effective therapies for CRC with PPARs as potential targets.

Reversible Gynecomastia and Hypogonadism Due to Usage of Commercial Performance-Enhancing Supplement Use

Commercially available performance-enhancing supplements can contain banned performance-enhancing drugs (PEDs) and undisclosed steroid hormones that can induce hormonal abnormalities with associated clinical signs. We present a case of a 40-year-old male who developed bilateral gynecomastia and biochemical hypogonadotropic hypogonadism with a corresponding 6-month history of consuming commercially available performance-enhancing supplements for gym workouts. These performance-enhancing supplements were found to contain amounts of RAD-140, a selective androgen receptor modulator, MK-677, a GH secretagogue and cardarine, all of which are banned PEDs. In vitro analysis also detected undisclosed hormones testosterone, estradiol, and GH in all 3 supplements, with further steroid analysis using liquid chromatography mass spectrometry identifying an unidentified compound coeluting close to the testosterone peak. Cessation of these supplements led to full resolution of symptoms including normalization of hypogonadotropic hypogonadism. This case highlights the need for clinicians to consider commercially available performance-enhancing supplements as potential sources of PEDs and exogenous steroid hormones that can have adverse clinical consequences.

Delineating the role of nuclear receptors in colorectal cancer, a focused review

Colorectal cancer (CRC) stands as one of the most prevalent form of cancer globally, causing a significant number of deaths, surpassing 0.9 million in the year 2020. According to GLOBOCAN 2020, CRC ranks third in incidence and second in mortality in both males and females. Despite extensive studies over the years, there is still a need to establish novel therapeutic targets to enhance the patients' survival rate in CRC. Nuclear receptors (NRs) are ligand-activated transcription factors (TFs) that regulate numerous essential biological processes such as differentiation, development, physiology, reproduction, and cellular metabolism. Dysregulation and anomalous expression of different NRs has led to multiple alterations, such as impaired signaling cascades, mutations, and epigenetic changes, leading to various diseases, including cancer. It has been observed that differential expression of various NRs might lead to the initiation and progression of CRC, and are correlated with poor survival outcomes in CRC patients. Despite numerous studies on the mechanism and role of NRs in this cancer, it remains of significant scientific interest primarily due to the diverse functions that various NRs exhibit in regulating key hallmarks of this cancer. Thus, modulating the expression of NRs with their agonists and antagonists, based on their expression levels, holds an immense prospect in the diagnosis, prognosis, and therapeutical modalities of CRC. In this review, we primarily focus on the role and mechanism of NRs in the pathogenesis of CRC and emphasized the significance of targeting these NRs using a variety of agents, which may represent a novel and effective strategy for the prevention and treatment of this cancer.

Peroxisome proliferator-activated receptors: A key link between lipid metabolism and cancer progression

Lipids represent the essential components of membranes, serve as fuels for high-energy processes, and play crucial roles in signaling and cellular function. One of the key hallmarks of cancer is the reprogramming of metabolic pathways, especially abnormal lipid metabolism. Alterations in lipid uptake, lipid desaturation, de novo lipogenesis, lipid droplets, and fatty acid oxidation in cancer cells all contribute to cell survival in a changing microenvironment by regulating feedforward oncogenic signals, key oncogenic functions, oxidative and other stresses, immune responses, or intercellular communication. Peroxisome proliferator-activated receptors (PPARs) are transcription factors activated by fatty acids and act as core lipid sensors involved in the regulation of lipid homeostasis and cell fate. In addition to regulating whole-body energy homeostasis in physiological states, PPARs play a key role in lipid metabolism in cancer, which is receiving increasing research attention, especially the fundamental molecular mechanisms and cancer therapies targeting PPARs. In this review, we discuss how cancer cells alter metabolic patterns and regulate lipid metabolism to promote their own survival and progression through PPARs. Finally, we discuss potential therapeutic strategies for targeting PPARs in cancer based on recent studies from the last five years.

Organophosphorus-Catalyzed "Dual-Substrate Deoxygenation" Strategy for C-S Bond Formation from Sulfonyl Chlorides and Alcohols/Acids

A green method to construct C-S bonds using sulfonyl chlorides and alcohols/acids via a P^III/P^V═O catalytic system is reported. The organophosphorus-catalyzed umpolung reaction promotes us to propose the "dual-substrate deoxygenation" strategy. Herein, we adopt the "dual-substrate deoxygenation" strategy, which achieves the deoxygenation of sulfonyl chlorides and alcohols/acids to synthesize thioethers/thioesters driven by P^III/P^V═O redox cycling. The catalytic method represents an operationally simple approach using stable phosphine oxide as a precatalyst and shows broad functional group tolerance. The potential application of this protocol is demonstrated by the late-stage diversification of drug analogues.

Asprosin, irisin, and meteorin-like protein immunoreactivity in different stages of colorectal adenocarcinoma

OBJECTIVE

In this study, we aimed to investigate the immunoreactivity of asprosin, irisin, and meteorin-like protein (METRNL) in different stages of colorectal adenocarcinoma, which is the most common malignancy of the gastrointestinal tract.

MATERIALS AND METHODS

Overall, 60 patients with colorectal adenocarcinoma, including 20 well (Group 1), moderately (Group 2), and poorly differentiated (Group 3) cases, respectively, and 20 with normal colonic mucosa, were examined using light microscopy for immunohistochemical staining of asprosin, METRNL, and irisin.

RESULTS

Compared with the control group, a significant increase in irisin and asprosin immunoreactivity was found in the grade 1 and 2 colorectal adenocarcinoma groups. Moreover, compared with the grade 1 and 2 groups, this immunoreactivity was significantly decreased in the grade 3 colorectal adenocarcinoma group. Although there was no significant difference in METRNL immunoreactivity between the grade 1 and control groups, a statistically significant increase in this immunoreactivity was found in the grade 2 group. In contrast, METRNL immunoreactivity was significantly decreased in the grade 3 group compared with the grade 2 group.

CONCLUSION

We found that in early-stage colorectal adenocarcinoma there was an increase in the immunoreactivity of asprosin and irisin, but in the advanced stage there was a decrease in immunoreactivity. Although METRNL immunoreactivity did not change in the control and grade 1 groups, it was found to increase significantly in the grade 2 group and decrease in the grade 3 group.

Peroxisome Proliferator-Activated Receptors and the Hallmarks of Cancer

Peroxisome proliferator-activated receptors (PPARs) function as nuclear transcription factors upon the binding of physiological or pharmacological ligands and heterodimerization with retinoic X receptors. Physiological ligands include fatty acids and fatty-acid-derived compounds with low specificity for the different PPAR subtypes (alpha, beta/delta, and gamma). For each of the PPAR subtypes, specific pharmacological agonists and antagonists, as well as pan-agonists, are available. In agreement with their natural ligands, PPARs are mainly focused on as targets for the treatment of metabolic syndrome and its associated complications. Nevertheless, many publications are available that implicate PPARs in malignancies. In several instances, they are controversial for very similar models. Thus, to better predict the potential use of PPAR modulators for personalized medicine in therapies against malignancies, it seems necessary and timely to review the three PPARs in relation to the didactic concept of cancer hallmark capabilities. We previously described the functions of PPAR beta/delta with respect to the cancer hallmarks and reviewed the implications of all PPARs in angiogenesis. Thus, the current review updates our knowledge on PPAR beta and the hallmarks of cancer and extends the concept to PPAR alpha and PPAR gamma.

PPARβ/δ Augments IL-1β-Induced COX-2 Expression and PGE2 Biosynthesis in Human Mesangial Cells via the Activation of SIRT1

Peroxisome proliferator-activated receptor β/δ (PPARβ/δ), a ligand-activated nuclear receptor, regulates lipid and glucose metabolism and inflammation. PPARβ/δ can exert an anti-inflammatory effect by suppressing proinflammatory cytokine production. Cyclooxygenase-2 (COX-2)-triggered inflammation plays a crucial role in the development of many inflammatory diseases, including glomerulonephritis. However, the effect of PPARβ/δ on the expression of COX-2 in the kidney has not been fully elucidated. The present study showed that PPARβ/δ was functionally expressed in human mesangial cells (hMCs), where its expression was increased by interleukin-1β (IL-1β) treatment concomitant with enhanced COX-2 expression and prostaglandin E2 (PGE2) biosynthesis. The treatment of hMCs with GW0742, a selective agonist of PPARβ/δ, or the overexpression of PPARβ/δ via an adenovirus-mediated approach significantly increased COX-2 expression and PGE2 production. PPARβ/δ could further augment the IL-1β-induced COX-2 expression and PGE2 production in hMCs. Moreover, both PPARβ/δ activation and overexpression markedly increased sirtuin 1 (SIRT1) expression. The inhibition or knockdown of SIRT1 significantly attenuated the effects of PPARβ/δ on the IL-1β-induced expression of COX-2 and PGE2 biosynthesis. Taken together, PPARβ/δ could augment the IL-1β-induced COX-2 expression and PGE2 production in hMCs via the SIRT1 pathway. Given the critical role of COX-2 in glomerulonephritis, PPARβ/δ may represent a novel target for the treatment of renal inflammatory diseases.

Ligand-activated PPARδ expression promotes hepatocellular carcinoma progression by regulating the PI3K-AKT signaling pathway

Background

Peroxisome proliferator-activated receptor-beta/delta (PPARδ) was considered as the key regulator involved in the evolution of various tumors. Given that PPARδ potential role in hepatocellular carcinoma (HCC) is still obscure, we comprehensively assessed its expression pattern, prognosis, functions and correlation with tumor microenvironment in HCC using public database data and in vitro studies.

Methods

Transcriptional data and clinical data in the TCGA and GEO database were analyzed in R software. Quantitative real-time polymerase chain reaction (qRT-PCR), western blotting and immunohistochemistry were used to detect the expression level of related RNA and proteins. The malignant biological characteristics were explored by cell counting Kit-8 (CCK8), 5-Ethynyl-2ʹ-deoxyuridine (EdU) assay and wound healing assay.

Results

Our results illustrated that PPARδ expression was significantly higher in HCC tissues and HCC cell lines. Elevated expression of PPARδ suggested poor clinical staging and prognosis in HCC. Ligand-activated PPARδ expression promoted the proliferation and invasion of HCC cells via PDK1/AKT/GSK3β signaling pathway. The expression of PPARδ was closely related to the HCC tumor microenvironment.

Conclusions

PPARδ plays an important part in HCC progression, penetrating investigation of the related regulatory mechanism may shed light upon further biological and pharmacological value.

PPARβ/δ Agonist Alleviates Diabetic Osteoporosis via Regulating M1/M2 Macrophage Polarization

Diabetic osteoporosis is a common complication in diabetic patients, leading to increased fracture risk and impaired bone healing. As a member of the peroxisome proliferator-activated receptor (PPAR) family, PPARβ/δ agonist is suggested as a therapeutic target for the treatment of metabolic syndrome, and has been reported to positively regulate bone turnover by improving osteogenesis. However, its regulatory role in diabetic osteoporosis has not been reported yet. Here, we explored the therapeutic effects and potential mechanisms of PPARβ/δ agonist to the osteoporotic phenotypes of diabetic mice. Our results indicated that the osteoporotic phenotypes could be significantly ameliorated in diabetic mice by the administration of PPARβ/δ agonists. In vitro experiments suggested that PPARβ/δ agonist treatment could alleviate the abnormal increase of osteoclast activity in diabetic mice by rectifying high glucose-mediated macrophage dysfunction instead of directly inhibiting osteoclast differentiation. Mechanistically, Angptl4 may act as a downstream target of PPARβ/δ to regulate macrophage polarization. In conclusion, our study demonstrates the potential of PPARβ/δ agonist as a therapeutic target for the treatment of osteoporosis and immune homeostasis disorder in diabetic patients.

Tanshinone IIA attenuates AOM/DSS-induced colorectal tumorigenesis in mice via inhibition of intestinal inflammation

CONTEXT

Tanshinone IIA is a natural extract derived from a Chinese medicinal herb with multiple bioactivities; however, whether and how tanshinone IIA protects against colorectal cancer (CRC) are uncertain.

OBJECTIVE

We investigated the potential beneficial effects of tanshinone IIA in a colitis-associated colorectal tumorigenesis mouse model and its underlying mechanisms.

MATERIALS AND METHODS

Male C57BL/6 mice were treated with azoxymethane (AOM) 10 mg/kg body weight and dextran sulphate sodium (2.5% DSS) to induce a colitis-associated cancer model. Tanshinone IIA (200 mg/kg body weight) was given to the mice intraperitoneally. After 12 weeks, all mice were sacrificed to measure tumour formation, intestinal permeability, neutrophil infiltration, and colonic inflammation. In addition, whether tanshinone IIA has inhibitory effects on neutrophil activation was determined through in vitro investigations.

RESULTS

We observed that tanshinone IIA significantly decreased tumour formation in AOM/DSS-treated mice compared to AOM/DSS-treated alone mice (0.266 ± 0.057 vs. 0.78 ± 0.153, p = 0.013). Tanshinone IIA also decreased intestinal permeability compared to that in AOM/DSS-treated alone mice (3.12 ± 0.369 vs. 5.06 ± 0.597, p = 0.034) and consequently reduced neutrophil infiltration of the colonic mucosa (53.25 ± 8.85 vs. 107.6 ± 13.09, p = 0.014) as well as intestinal inflammation in mice. Mechanistically, tanshinone IIA downregulated the NF-κB signalling pathway in the colonic tumours of AOM/DSS-treated mice. In vitro assays further validated that tanshinone IIA suppressed LPS-induced neutrophil activation.

CONCLUSION

These data suggest that tanshinone IIA alleviates colorectal tumorigenesis through inhibition of intestinal inflammation. Tanshinone IIA may have a therapeutic potential for CRC in clinical practice.

TiaochangXiaoliu decoction inhibits azomethane (AOM)/dextran sulfate sodium (DSS)-induced colorectal cancer by regulating immune response

Background

TiaochangXiaoliu decoction (TXD) has an anti-tumor effect in clinical practice. We further investigated the role of TXD in colorectal cancer (CRC).

Methods

Mouse models of CRC were induced by azomethane (AOM)/dextran sulfate sodium (DSS), with sixty male C57BL/6 mice randomly divided into six groups (10 mice/group): a control group, AOM/DSS group, TXD at low dose (L-dose) group, middle dose (M-dose) group, high dose (H-dose) group, and Celecoxib (Cel) group. The colorectum, serum, and plasma of mice in each group was collected following sacrifice to record the number of tumors. HE staining was utilized for observing pathological damage to colorectal tissues, ELISA used for detecting INF-γ, IL-2, and TNF-α expression in serum, and flow cytometry used for measuring the proportion of CD4⁺, CD8⁺, CD4⁺/CD8⁺, and NK cells in plasma.

Results

Compared with the control group, the AOM/DSS group showed tumor masses in the colorectum and different degrees of pathological damage in the intestine. AOM/DSS induction also resulted in an increase in INF-γ, IL-2, and TNF-α expression in serum, and a decrease in the percentages of CD4⁺, CD8⁺, CD4⁺/CD8⁺, and NK cells(P<0.05). In comparison with the AOM/DSS group, with the increase of TXD dose, the number of tumors decreased significantly, and intestinal structure and mucosal inflammatory cell infiltration also improved. Further, in comparison with the AOM/DSS group, all three doses of TXD and celecoxib caused an increase in the contents of CD4⁺, CD8⁺, CD4⁺/CD8⁺, and NK cells in plasma. In addition, in the M-dose, H-dose, and Cel groups, INF-γ, IL-2, and TNF-α expression showed a marked decrease, and the reduction in these two groups treated with TXD was dose-dependent.

Conclusions

TXD leads to a marked reduction in the number of tumors and inflammatory cell infiltration in CRC mice. This decoction significantly decreased the levels of INF-γ, IL-2, and TNF-α in serum, and increased the contents of CD4⁺, CD8⁺, CD4⁺/CD8⁺, and NK cell in the plasma of mice with AOM/DSS-induced CRC.

AMPK phosphorylates PPARδ to mediate its stabilization, inhibit glucose and glutamine uptake and colon tumor growth

Peroxisome proliferator-activated receptor δ (PPARδ) is a nuclear receptor transcription factor that plays an important role in the regulation of metabolism, inflammation, and cancer. In addition, the nutrient-sensing kinase 5'AMP-activated protein kinase (AMPK) is a critical regulator of cellular energy in coordination with PPARδ. However, the molecular mechanism of the AMPK/PPARδ pathway on cancer progression is still unclear. Here, we found that activated AMPK induced PPARδ-S50 phosphorylation in cancer cells, whereas the PPARδ/S50A (nonphosphorylation mimic) mutant reversed this event. Further analysis showed that the PPARδ/S50E (phosphorylation mimic) but not the PPARδ/S50A mutant increased PPARδ protein stability, which led to reduced p62/SQSTM1-mediated degradation of misfolded PPARδ. Furthermore, PPARδ-S50 phosphorylation decreased PPARδ transcription activity and alleviated PPARδ-mediated uptake of glucose and glutamine in cancer cells. Soft agar and xenograft tumor model analysis showed that the PPARδ/S50E mutant but not the PPARδ/S50A mutant inhibited colon cancer cell proliferation and tumor growth, which was associated with inhibition of Glut1 and SLC1A5 transporter protein expression. These findings reveal a new mechanism of AMPK-induced PPARδ-S50 phosphorylation, accumulation of misfolded PPARδ protein, and inhibition of PPARδ transcription activity contributing to the suppression of colon tumor formation.

Evaluation of Browning Agents on the White Adipogenesis of Bone Marrow Mesenchymal Stromal Cells: A Contribution to Fighting Obesity

Brown-like adipocytes can be induced in white fat depots by a different environmental or drug stimuli, known as "browning" or "beiging". These brite adipocytes express thermogenin UCP1 protein and show different metabolic advantages, such as the ability to acquire a thermogenic phenotype corresponding to standard brown adipocytes that counteracts obesity. In this research, we evaluated the effects of several browning agents during white adipocyte differentiation of bone marrow-derived mesenchymal stromal cells (MSCs). Our in vitro findings identified two compounds that may warrant further in vivo investigation as possible anti-obesity drugs. We found that rosiglitazone and sildenafil are the most promising drug candidates for a browning treatment of obesity. These drugs are already available on the market for treating diabetes and erectile dysfunction, respectively. Thus, their off-label use may be contemplated, but it must be emphasized that some severe side effects are associated with use of these drugs.

Acetonitrilated Unsymmetric BODIPYs having glycine fluorescence responsive quenching: Design, synthesis and spectroscopic properties

A series of novel N≡C-CH₂-B-F system BODIPY were designed and synthesized by introducing aldehyde and acetonitrile units which gave positive influence to spectroscopic and chemical properties of BODIPY derivatives. The effects of glycine (Gly) on the target products were studied via ultraviolet and visible spectrophotometry (UV-Vis) and photoluminescence (PL) under different conditions of the presence and absence of cations (K⁺, Ca²⁺, Zn²⁺). It was showed that glycine has an intense quenching effect on the compounds in both the presence and absence of ions with a dramatic color change from notable red to light orange owing to the addition of Gly. With regard to cells imaging investigation, the products showed the prominent fluorescence in cholangiocarcinoma cells. The luminescent effect of compounds 1 and 3 entering the cells was significantly stronger than that of compound 2. In addition, pertaining to anticancer properties, two human cancer cell lines (RBE, HCCC-9810) and one normal cell line (L-02) were evaluated for in vitro cytotoxicity. The target compounds, 1-3, exhibited moderate antitumor activity, of which compound 1 was found to be the most potent derivative with IC₅₀ values of 119.31 ± 6.25, 114.73 ± 3.25, and 106.33 ± 5.22 against RBE, HCCC-9810, and L-02 cells, respectively, slightly weaker than the positive control 5-FU.

PPARδ is a regulator of autophagy by its phosphorylation

In response to nutrient deficiency, autophagy degrades cytoplasmic materials and organelles in lysosomes, which is nutrient recycling, whereas activation of EGFR mediates autophagy suppression in response to growth factors. It is unclear whether PPARδ could be the regulator of autophagy in response to active EGFR. Here we found that EGFR induced PPARδ phosphorylation at tyrosine-108 leading to increased binding of LC3 to PPARδ by its LIR (LC3 interacting region) motif, consequently, inhibited autophagic flux. Conversely, EGFR inhibitor treatment reversed this event. Furthermore, EGFR-mediated PPARδ phosphorylation at tyrosine-108 led to autophagy inhibition and tumor growth. These findings suggest that PPARδ serves as a regulator of autophagy by its phosphorylation.

PPAR Beta/Delta and the Hallmarks of Cancer

Peroxisome proliferator-activated receptors (PPARs) belong to the nuclear hormone receptor family. Three different isoforms, PPAR alpha, PPAR beta/delta and PPAR gamma have been identified. They all form heterodimers with retinoic X receptors to activate or repress downstream target genes dependent on the presence/absence of ligands and coactivators or corepressors. PPARs differ in their tissue expression profile, ligands and specific agonists and antagonists. PPARs attract attention as potential therapeutic targets for a variety of diseases. PPAR alpha and gamma agonists are in clinical use for the treatment of dyslipidemias and diabetes. For both receptors, several clinical trials as potential therapeutic targets for cancer are ongoing. In contrast, PPAR beta/delta has been suggested as a therapeutic target for metabolic syndrome. However, potential risks in the settings of cancer are less clear. A variety of studies have investigated PPAR beta/delta expression or activation/inhibition in different cancer cell models in vitro, but the relevance for cancer growth in vivo is less well documented and controversial. In this review, we summarize critically the knowledge of PPAR beta/delta functions for the different hallmarks of cancer biological capabilities, which interplay to determine cancer growth.

Design, Synthesis, and Dual Evaluation of Quinoline and Quinolinium Iodide Salt Derivatives as Potential Anticancer and Antibacterial Agents

A series of novel quinoline and quinolinium iodide derivatives were designed and synthesized to discover potential anticancer and antibacterial agents. With regard to anticancer properties, in vitro cytotoxicities against three human cancer cell lines (A-549, HeLa and SGC-7901) were evaluated. The antibacterial properties against two strains, Escherichia coli (ATCC 29213) and Staphylococcus aureus (ATCC 8739), along with minimum inhibitory concentration (MIC) values were evaluated. The target alkyliodine substituted compounds exhibited significant antitumor and antibacterial activity, of which compound 8-((4-(benzyloxy)phenyl)amino)-7-(ethoxycarbonyl)-5-propyl-[1,3]dioxolo[4,5-g]quinolin-5-ium (12) was found to be the most potent derivative with IC₅₀ values of 4.45±0.88, 4.74±0.42, 14.54±1.96, and 32.12±3.66 against A-549, HeLa, SGC-7901, and L-02 cells, respectively, stronger than the positive controls 5-FU and MTX. Furthermore, compound 12 had the most potent bacterial inhibitory activity. The MIC of this compound against both E. coli and S. aureus was 3.125 nmol ⋅ mL^-1 , which was smaller than that against the reference agents amoxicillin and ciprofloxacin.

Over expression of METRN predicts poor clinical prognosis in colorectal cancer

BACKGROUND

The role of meteorin (METRN) in colorectal cancer has not been reported previously. We aimed to explore the relationship between METRN and colorectal cancer (CRC) prognosis.

METHODS

Data were retrieved from the Gene Expression Omnibus database. Gene expression values were log2 transformed and normalized by quantile normalization. Missing values were imputed with the R impute package. Differentially expressed genes were analyzed using the R limma package. METRN expression was compared between normal and CRC tissues and among different stages and subtypes of CRC. We assessed the relationship between METRN and KRAS/BRAF mutations in CRC. Five-year overall (OS), disease-free (DFS), and disease-specific survival (DSS) rates were determined by Kaplan-Meier analysis and analyzed by log-rank test.

RESULTS

METRN was expressed at a higher level in CRC (p = .0011) than in normal tissues, especially in advanced stages (p = .0343). METRN expression levels were higher in the MSI (dMMR) subtype (p < .001) and usually with BRAF mutations (p < .0001). METRN overexpression was associated with poor prognosis and low OS (p = .01014), DFS (p = .0146), and DSS (p < .0001) rates.

CONCLUSION

METRN overexpression is a predictive factor for poor prognosis in patients with CRC.

PPARα agonist alleviates tumor growth and chemo-resistance associated with the inhibition of glucose metabolic pathway

As a nuclear receptor, peroxisome-proliferator-activated receptor α (PPARα) plays a critical role in regulation of metabolism and cancer, while the effect of PPARα agonist on cancer cell glucose metabolism-linked tumor growth is still unclear. Here we found that PPARα agonist (Wy14,643) decreased Glut1 (Glucose transporter 1) gene and protein expressions of colorectal cancer cell lines in response to normoxia or hypoxia. Dual-luciferase analysis showed that Wy14,643 inhibited Glut1 transcription activity. Importantly, ChIP-qPCR analysis showed that Wy14,643 increased the binding of PPARα to Glut1 promoter region. Wy14,643 suppressed Glut1 transcription activity resulting in reduced influx of glucose in cancer cells in response to normoxia or hypoxia. Further analysis showed that Wy14,643-mediated inhibition of tumor growth and chemo-resistance was associated with inhibition of mTOR pathway. Taken together, PPARα agonist Wy14,643 suppressed Glut1 transcription activity, glucose uptake and mTOR pathway in colorectal cancer cells, which was involved in reduced tumor growth and chemo-resistance. These findings provided a novel therapy strategy for cancer progression.