The potential role of plasma fibroblast growth factor 21 as a diagnostic biomarker for abdominal aortic aneurysm presence and development

The Complexity and Significance of Fibroblast Growth Factor (FGF) Signaling for FGF-Targeted Cancer Therapies

Fibroblast growth factors (FGFs) have diverse functions in the regulation of cell proliferation and differentiation in development, tissue maintenance, wound repair, and angiogenesis. The goal of this review paper is to (i) deliberate on the role of FGFs and FGF receptors (FGFRs) in different cancers, (ii) present advances in FGF-targeted cancer therapies, and (iii) explore cell signaling mechanisms that explain how FGF expression becomes dysregulated during cancer development. FGF is often mutated and overexpressed in cancer and the different FGF and FGFR isoforms have unique expression patterns and distinct roles in different cancers. Among the FGF members, the FGF 15/19 subfamily is particularly interesting because of its unique protein structure and role in endocrine function. The abnormal expression of FGFs in different cancer types (breast, colorectal, hepatobiliary, bronchogenic, and others) is examined and correlated with patient prognosis. The classification of FGF ligands based on their mode of action, whether autocrine, paracrine, endocrine, or intracrine, is illustrated, and an analysis of the binding specificity of FGFs to FGFRs is also provided. Moreover, the latest advances in cancer therapeutic strategies involving small molecules, ligand traps, and monoclonal antibody-based FGF inhibitors are presented. Lastly, we discuss how the dysregulation of FGF and FGFR expression affects FGF signaling and its role in cancer development.

Affinity-Enriched Plasma Proteomics for Biomarker Discovery in Abdominal Aortic Aneurysms

Abdominal aortic aneurysm (AAA) is a life-threatening condition characterized by the weakening and dilation of the abdominal aorta. Few diagnostic biomarkers have been proposed for this condition. We performed mass spectrometry-based proteomics analysis of affinity-enriched plasma from 45 patients with AAA and 45 matched controls to identify changes to the plasma proteome and potential diagnostic biomarkers. Gene ontology analysis revealed a significant upregulation of the proteins involved in inflammation, coagulation, and extracellular matrix in AAA patients, while proteins related to angiogenesis were among those downregulated. Using recursive feature elimination, we identified a subset of 10 significantly regulated proteins that were highly predictive of AAA. A random forest classifier trained on these proteins achieved an area under the curve (AUC) of 0.93 [95% CI: 0.91-0.95] using cross-validation. Further validation in a larger cohort is necessary to confirm these results.

FGF21 promotes angiotensin II-induced abdominal aortic aneurysm via PI3K/AKT/mTOR pathway

BACKGROUND

Abdominal aortic aneurysm (AAA) is a potentially fatal vascular disorder with a high mortality rate. It was previously reported that fibroblast growth factor 21 (FGF21) was highly expressed in AAA patients. Nonetheless, its underlying mechanism in AAA progression is unclarified.

METHODS

Angiotensin II (Ang-II) was used to induce AAA in human aortic vascular smooth muscle cells (HASMCs) and mouse models. Western blotting and RT-qPCR were utilized for measuring protein and RNA levels. Immunofluorescence staining was utilized for detecting LC3B expression in HASMCs. Elastica van Gieson staining was conducted for histological analysis of the abdominal aortas of mice.

RESULTS

FGF21 displayed a high level in Ang-II-stimulated HASMCs and AAA mice. FGF21 depletion ameliorated abdominal aorta dilation and Ang-II-triggered pathological changes in mice. FGF21 silencing hindered autophagy and PI3K/AKT/mTOR pathway.

CONCLUSIONS

FGF21 contributes to AAA progression by enhancing autophagy and activating PI3K/AKT/mTOR pathway.

Plasma Lipidomics Analysis Reveals the Potential Role of Lysophosphatidylcholines in Abdominal Aortic Aneurysm Progression and Formation

Abdominal aortic aneurysm (AAA) is hallmarked by irreversible dilation of the infrarenal aorta. Lipid deposition in the aortic wall and the potential importance of a lipid disorder in AAA etiology highlight the need to explore lipid variation during AAA development. This study aimed to systematically characterize the lipidomics associated with AAA size and progression. Plasma lipids from 106 subjects (36 non-AAA controls and 70 AAA patients) were comprehensively analyzed using untargeted lipidomics. An AAA animal model was established by embedding angiotensin-II pump in ApoE^-/- mice for four weeks and blood was collected at 0, 2 and 4 weeks for lipidomic analysis. Using a false-discovery rate (FDR) < 0.05, a group of lysophosphatidylcholines (lysoPCs) were specifically decreased in AAA patients and mice. LysoPCs were principally lower in the AAA patients with larger diameter (diameter > 50 mm) than those with a smaller size (30 mm < diameter < 50 mm), and levels of lysoPCs were also found to be decreased with modelling time and aneurysm formation in AAA mice. Correlation matrices between lipids and clinical characteristics identified that the positive correlation between lysoPCs and HDL-c was reduced and negative correlations between lysoPCs and CAD rate, lysoPCs and hsCRP were converted to positive correlations in AAA compared to control. Weakened positive correlations between plasma lysoPCs and circulating HDL-c in AAA suggested that HDL-lysoPCs may elicit instinctive physiological effects in AAA. This study provides evidence that reduced lysoPCs essentially underlie the pathogenesis of AAA and that lysoPCs are promising biomarkers for AAA development.

Blood immunological profile of abdominal aortic aneurysm based on autoimmune injury

Abdominal aortic aneurysm (AAA) occupies a large part of aorta aneurysm, and if there's no timely intervention or treatment, the risks of rupture and death would rise sharply. With the depth of research in AAA, more and more evidence showed correlations between AAA and autoimmune injury. Currently, a variety of bioactive peptides and cells have been confirmed to be related with AAA progression. Despite the tremendous progress, more than half researches were sampling from lesion tissues, which would be difficult to obtain. Given that the intrusiveness and convenience, serological test take advantages in initial diagnosis. Here we review blood biomarkers associated with autoimmune injury work in AAA evolution, aiming to make a profile on blood immune substances of AAA and provide a thought for potential clinical practice.

Activating transcription factor 4 aggravates angiotensin II-induced cell dysfunction in human vascular aortic smooth muscle cells via transcriptionally activating fibroblast growth factor 21

Abdominal aortic aneurysm (AAA) is a life-threatening disorder worldwide. Fibroblast growth factor 21 (FGF21) was shown to display a high level in the plasma of patients with AAA; however, its detailed functions underlying AAA pathogenesis are unclear. An in vitro AAA model was established in human aortic vascular smooth muscle cells (HASMCs) by angiotensin II (Ang-II) stimulation. Cell counting kit-8, wound healing, and Transwell assays were utilized for measuring cell proliferation and migration. RT-qPCR was used for detecting mRNA expression of FGF21 and activating transcription factor 4 (ATF4). Western blotting was utilized for assessing protein levels of FGF21, ATF4, and markers for the contractile phenotype of HASMCs. ChIP and luciferase reporter assays were implemented for identifying the binding relation between AFT4 and FGF21 promoters. FGF21 and ATF4 were both upregulated in Ang-II-treated HASMCs. Knocking down FGF21 attenuated Ang-II-induced proliferation, migration, and phenotype switch of HASMCs. ATF4 activated FGF21 transcription by binding to its promoter. FGF21 overexpression reversed AFT4 silencing-mediated inhibition of cell proliferation, migration, and phenotype switch. ATF4 transcriptionally upregulates FGF21 to promote the proliferation, migration, and phenotype switch of Ang-II-treated HASMCs.

miR-124a Involves in the Regulation of Wnt/β-Catenin and P53 Pathways to Inhibit Abdominal Aortic Aneurysm via Targeting BRD4

BACKGROUND

Abdominal aortic aneurysm (AAA) belongs to a progressive, gradual aortic rupture, which can lead to death without surgical intervention. The key factors regulating the occurrence and progress of AAA are not clear. Increasing studies have indicated that microRNA (miRNA) plays an important role in cancer development. miR-124a serves as a tumor suppressor in several neoplasms, and its upregulation can greatly inhibit the life activities such as malignant growth and migration of tumor cells.

AIM

The objective of this study is to explore the association of miR-124a with AAA and to uncover the regulated mechanism of miR-124a on AAA progression.

METHODS

The specimens from the AAA patients were used for observing the miR-124a expression, and human aortic endothelial cells (hAoECs) were treated with AngII to establish the AAA cell models. The quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR), CCK-8, transwell assay, flow cytometry assay, and western blot were conducted to unearth the regulation mechanism of miR-124a on AAA, and the dual-luciferase reporter assay was employed to investigate the downstream target of miR-124a.

RESULTS

miR-124a was significantly downregulated in the whole blood of the patients, and the decreased miR-124a was also observed in AAA cell models. Overexpressing miR-124a could effectively inhibit the proliferation and migration and promote the apoptosis of the AAA cells. The dual-luciferase reporter assay confirmed that BRD4 was a downstream target of miR-124a, and BRD4 upregulation could obviously reverse the effects of miR-124a on the phenotype of AAA cells. Moreover, it was found that miR-124a could regulate the activities of Wnt/β-catenin and P53 pathways via targeting the BRD4.

CONCLUSION

Our data suggested that miR-124a could regulate the activities of Wnt/β-catenin and P53 to suppress the AAA progression via targeting the BRD4.

Biomarkers in EndoVascular Aneurysm Repair (EVAR) and Abdominal Aortic Aneurysm: Pathophysiology and Clinical Implications

Circulating biomarkers have been recently investigated among patients undergoing endovascular aortic aneurysm repair (EVAR) for abdominal aortic aneurysm (AAA). Considering the plethora of small descriptive studies reporting potential associations between biomarkers and clinical outcomes, this review aims to summarize the current literature considering both the treated disease (post EVAR) and the untreated disease (AAA before EVAR). All studies describing outcomes of tissue biomarkers in patients undergoing EVAR and in patients with AAA were included, and references were checked for additional sources. In the EVAR scenario, circulating interleukin-6 (IL-6) is a marker of inflammatory reaction which might predict postoperative morbidity; cystatin C is a promising early marker of post-procedural acute kidney injury; plasma matrix metalloproteinase-9 (MMP-9) concentration after 3 months from EVAR might help in detecting post-procedural endoleak. This review also summarizes the current gaps in knowledge and future direction of this field of research. Among markers used in patients with AAA, galectin and granzyme appear to be promising and should be carefully investigated even in the EVAR setting. Larger prospective trials are required to establish and evaluate prognostic models with highest values with these markers.