The expression and role of glycolysis-associated molecules in infantile hemangioma

ALKBH5 facilitates the progression of infantile hemangioma by increasing FOXF1 expression in a m6A-YTHDF2 dependent manner to activate HK-2 signaling

Alkylation repair homolog protein 5 (ALKBH5) is reported to participate in infantile hemangioma (IH) progression. However, the underlying mechanism of ALKBH5 in IH remains unclear. Using qRT-PCR and Western blotting, ALKBH5, forkhead box F1 (FOXF1) and hexokinase 2 (HK-2) expressions in IH tissues and IH-derived endothelial cells XPTS-1 were assessed. The Me-RIP assay was used to analyze FOXF1 m6A level. CCK8, colony formation, flow cytometry and transwell assays were employed to determine IH cell viability, proliferation, apoptosis, migration and invasion. The interactions between YTH (YT521-B homology) domain 2 (YTHDF2), FOXF1 and HK-2 were analyzed by RIP, dual luciferase reporter gene assay and/or ChIP assay. The in vivo IH growth was evaluated in immunocompromised mice. FOXF1 was overexpressed in IH tissues, and its silencing inhibited IH cell proliferation, migration and invasion whereas promoting cell apoptosis in vitro. ALKBH5 upregulation facilitated FOXF1 mRNA stability and expression in IH cells in a m6A-YTHDF2-dependent manner. FOXF1 downregulation reversed the impact of ALKBH5 upregulation on IH cellular phenotypes. It also turned out that FOXF1 positively regulated HK-2 expression in IH cells through interacting with the HK-2 promoter. HK-2 upregulation abolished FOXF1 knockdown's inhibition on IH cell aggressive behaviors. ALKBH5 or FOXF1 silencing suppressed IH tumor development via HK-2 signaling in immunocompromised mice. ALKBH5 promoted FOXF1 expression m6A-YTHDF2 dependently, which in turn elevated HK-2 expression, thereby accelerating IH development.

Insights into the mechanisms of angiogenesis in infantile hemangioma

Infantile hemangioma (IH) is the most common benign tumor in infants and usually resolves on its own. However, a small portion of IH cases are accompanied by serious complications and other problems, impacting the physical and psychological health of the children affected. The pathogenesis of IH is highly controversial. Studies have shown that abnormal blood vessel formation is an important pathological basis for the development of IH. Compared with that in normal tissues, the equilibrium of blood vessel growth at the tumor site is disrupted, and interactions among other types of cells, such as immune cells, promote the rapid proliferation and migration of vascular tissue cells and the construction of vascular networks. Currently, propranolol is the most common systemic drug used to inhibit the growth of IHs and accelerate their regression. The purpose of this review is to provide the latest research on the mechanisms of angiogenesis in IH. We discuss the possible roles of three major factors, namely, estrogen, hypoxia, and inflammation, in the development of IH. Additionally, we summarize the key roles of tumor cell subpopulations, such as pericytes, in the proliferation and regression of IH considering evidence from the past few years, with an emphasis on the possible mechanisms of propranolol in the treatment of IH. Angiogenesis is an important event during the development of IH, and an in-depth understanding of the molecular mechanisms of angiogenesis will provide new insights into the biology and clinical treatment of IH.

Cell Fate Regulation During the Development of Infantile Hemangioma

As the most common benign vascular tumor in infants, infantile hemangioma (IH) is characterized by rapid growth and vasculogenesis early in infancy, followed by spontaneous involution into fibrofatty tissues over time. Extensive evidence suggests that IH originates from hemangioma stem cells (HemSCs), a group of stem cells with clonal expansion and multi-directional differentiation capacity. However, the intricate mechanisms governing the cell fate transition of HemSCs during IH development remain elusive. Here we comprehensively examine the cellular composition of IH, emphasizing the nuanced properties of various IH cell types and their correlation with the clinical features of the tumor. We also summarize the current understanding of the regulatory pathways directing HemSC differentiation into endothelial cells (ECs), pericytes, and adipocytes throughout the stages of IH progression and involution. Furthermore, we discuss recent advances in unraveling the transcriptional and epigenetic regulation of EC and adipocyte development under physiological conditions, which offer crucial perspectives for understanding IH pathogenesis.

The Role of Natural Extracts in the Management of Infantile Hemangiomas and Vascular Tumors

Hemangiomas are vascular tumors resulting from the proliferation of endothelial-like cells; they are the most common childhood tumors, affecting approximately 5-10% of newborns and infants. Besides hemangiomas, which are definitely benign tumors despite their overgrowth potential, there are other vascular tumors like hemangioendotheliomas, which may display intermediate characteristics between benign hemangiomas and highly malignant angiosarcomas. Standard therapy may be constricted by serious adverse effects, high cost, or traumatic influence. Diet is a major resource for health preservation, disease prevention, and treatment. The therapeutic property of edible berries, marine products, or medicinal plants have long been known and used in traditional medicine; a plant-based nutrition can prevent the development and progression of diseases associated with extensive neo-vascularization. The purpose of our review is to highlight those natural treatments that hemangioma and vascular tumor patients can receive in the future, both for their benefit and that of their families. We performed the review according to the Preferred Reporting Items for Systematic Reviews and Metanalysis Statement. We used the Web of Science, PubMed, and EMBASE engines for the study, and searched for the association of hemangioma with naturopathic treatment/plant extract/plants in published articles. We found that natural extracts from plants and fruits are cost-effective and safe treatments for hemangiomas and vascular tumors, as well as for other forms of cancer. In any case, more in vitro and in vivo studies are needed to confirm the proposed signaling pathways in tumors and validate the improvement parameters after natural products administration. The era of molecularly targeted therapy and personalized medicine is approaching and naturally occurring substances are very useful tools for tumor treatment and prevention. Plant extract substances have strong specificity and pertinence, are non- toxic and have few side effects, and may become an emerging cancer treatment.

Effects of propranolol on glucose metabolism in hemangioma-derived endothelial cells

Infantile hemangioma (IH) is the most common benign tumor in children. Propranolol is the first-line treatment for IH, but the underlying mechanism of propranolol treatment in IH is not completely understood. Integrated transcriptional and metabolic analyses were performed to investigate the metabolic changes in hemangioma-derived endothelial cells (HemECs) after propranolol treatment. The findings were then further validated through independent cell experiments using a Seahorse XFp analyzer, Western blotting, immunohistochemistry and mitochondrial functional assays. Thirty-four differentially expressed metabolites, including the glycolysis metabolites glucose 6-phosphate, fructose 6-phosphate and fructose 1,6-bisphosphate, were identified by targeted metabolomics. A KEGG pathway enrichment analysis showed that the disturbances in these metabolites were highly related to glucose metabolism-related pathways, including the pentose phosphate pathway, the Warburg effect, glycolysis and the citric acid cycle. Transcriptional analysis revealed that metabolism-related pathways, including glycine, serine and threonine metabolism, tyrosine metabolism, and glutathione metabolism, were highly enriched. Moreover, integration of the metabolomic and transcriptomic data revealed that glucose metabolism-related pathways, particularly glycolysis, were altered after propranolol treatment. Cell experiments demonstrated that HemECs exhibited higher levels of glycolysis than human umbilical vein ECs (HUVECs) and that propranolol suppressed glycolysis in HemECs. In conclusion, propranolol inhibited glucose metabolism in HemECs by suppressing glucose metabolic pathways, particularly glycolysis.

Shikonin reverses pyruvate kinase isoform M2-mediated propranolol resistance in infantile hemangioma through reactive oxygen species-induced autophagic dysfunction

Infantile hemangioma (IH) is the most common benign tumor in infancy. Propranolol, a nonselective β-adrenergic receptor blocker, is now the first-line therapy for IH. Recently, low sensitivity to propranolol therapy has become one major reason for the failure of IH treatment. However, the exact underlying mechanisms are yet to be fully elucidated. Here, we reported that pyruvate kinase isoform M2 (PKM2), an essential glycolytic enzyme, played a critical role in regulating the progression of IH and the therapeutic resistance of propranolol treatment. Shikonin reversed the propranolol resistance in hemangioma-derived endothelial cells and in hemangioma animal models. Moreover, shikonin combined with propranolol could induce excessive reactive oxygen species (ROS) accumulation and lead to autophagic dysfunction, which is essential for the enhanced therapeutic sensitivity of propranolol treatment. Taken together, our results indicated that PKM2 has a significant role in hemangiomas progression and therapeutic resistance; it could be a safe and effective therapeutic strategy for those hemangiomas with poor propranolol sensitivity combined with shikonin.

Blockage of glycolysis by targeting PFKFB3 suppresses the development of infantile hemangioma

BACKGROUND

Infantile hemangioma (IH) is the most common tumor among infants, but the exact pathogenesis of IH is largely unknown. Our previous study revealed that glucose metabolism may play an important role in the pathogenesis of IH and that the inhibition of the glycolytic key enzyme phosphofructokinase-1 suppresses angiogenesis in IH. 6-Phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3) is a metabolic enzyme that converts fructose-6-bisphosphate to fructose-2,6-bisphosphate (F-2,6-BP), which is the most potent allosteric activator of the rate-limiting enzyme phosphofructokinase-1. This study was performed to explore the role of PFKFB3 in IH.

METHODS

Microarray analysis was performed to screen the differentially expressed genes (DEGs) between proliferating and involuting IH tissues. PFKFB3 expression was examined by western blot and immunohistochemistry analyses. Cell migration, apoptosis and tube formation were analyzed. Metabolic analyses were performed to investigate the effect of PFKFB3 inhibition by PFK15. Mouse models were established to examine the effect of PFKFB3 inhibition in vivo.

RESULTS

PFKFB3 was identified as one of the most significant DEGs and was more highly expressed in proliferating IH tissues and hemangioma-derived endothelial cells (HemECs) than in involuting IH tissues and human umbilical vein endothelial cells, respectively. PFKFB3 inhibition by PFK15 suppressed HemEC glucose metabolism mainly by affecting glycolytic metabolite metabolism and decreasing the glycolytic flux. Moreover, PFK15 inhibited HemEC angiogenesis and migration and induced apoptosis via activation of the apoptosis pathway. Treatment with the combination of PFK15 with propranolol had a synergistic inhibitory effect on HemECs. Moreover, PFKFB3 knockdown markedly suppressed HemEC angiogenesis. Mechanistically, inhibition of PFKFB3 suppressed the PI3K-Akt signaling pathway and induced apoptotic cell death. More importantly, the suppression of PFKFB3 by PFK15 or shPFKFB3 led to markedly reduced tumor growth in vivo.

CONCLUSIONS

Our findings suggest that PFKFB3 inhibition can suppress IH angiogenesis and induce apoptosis. Thus, targeting PFKFB3 may be a novel therapeutic strategy for IH.

Integrated nontargeted and targeted metabolomics analyses amino acids metabolism in infantile hemangioma

Infantile hemangioma (IH) is the most common benign tumor in children. However, the exact pathogenesis of IH remains unclear. Integrated nontargeted and targeted metabolic analyses were performed to obtain insight into the possible pathogenic mechanism of IH. The results of nontargeted metabolic analysis showed that 216 and 128 differential metabolites (DMs) were identified between hemangioma-derived endothelial cells (HemECs) and HUVECs in positive-ion and negative-ion models, respectively. In both models, these DMs were predominantly enriched in pathways related to amino acid metabolism, including aminoacyl-tRNA biosynthesis and arginine and proline metabolism. Then, targeted metabolic analysis of amino acids was further performed to further clarify HemEC metabolism. A total of 22 amino acid metabolites were identified, among which only 16 metabolites, including glutamine, arginine and asparagine, were significantly differentially expressed between HemECs and HUVECs. These significant amino acids were significantly enriched in 10 metabolic pathways, including 'alanine, aspartate and glutamate metabolism', 'arginine biosynthesis', 'arginine and proline metabolism', and 'glycine, serine and threonine metabolism'. The results of our study revealed that amino acid metabolism is involved in IH. Key differential amino acid metabolites, including glutamine, asparagine and arginine, may play an important role in regulating HemEC metabolism.

CD146+ mural cells from infantile hemangioma display proangiogenic ability and adipogenesis potential in vitro and in xenograft models

Objective

Infantile hemangioma (IH), the most common infantile vascular neoplasm, is uniquely characterized by rapid proliferation followed by slow spontaneous involution lasting for years. In IH lesions, perivascular cells are the most dynamic cell subset during the transition from the proliferation phase to the involution phase, and we aimed to systematically study this kind of cell.

Methods and results

CD146-selective microbeads were used to isolate IH-derived mural-like cells (HemMCs). Mesenchymal markers of HemMCs were detected by flow cytometry, and the multilineage differentiation potential of HemMCs was detected by specific staining after conditioned culture. CD146-selected nonendothelial cells from IH samples showed characteristics of mesenchymal stem cells with distinct angiogenesis-promoting effects detected by transcriptome sequencing. HemMCs spontaneously differentiated into adipocytes 2 weeks after implantation into immunodeficient mice, and almost all HemMCs had differentiated into adipocytes within 4 weeks. HemMCs could not be induced to differentiate into endothelial cells in vitro. However, 2 weeks after implantation in vivo, HemMCs in combination with human umbilical vein endothelial cells (HUVECs) formed GLUT1⁺ IH-like blood vessels, which spontaneously involuted into adipose tissue 4 weeks after implantation.

Conclusions

In conclusion, we identified a specific cell subset that not only showed behavior consistent with the evolution of IH but also recapitulated the unique course of IH. Thus, we speculate that proangiogenic HemMCs may be a potential target for the construction of hemangioma animal models and the study of IH pathogenesis.

Identification of Diagnostic Markers in Infantile Hemangiomas

Background

Infantile Hemangiomas (IHs) are common benign vascular tumors of infancy that may have serious consequences. The research on diagnostic markers for IHs is scarce.

Methods

The "limma" R package was applied to identify differentially expressed genes (DEGs) in developing IHs. Plugin ClueGO in Cytoscape software performed functional enrichment of DEGs. The Search Tool for Retrieving Interacting Genes (STRING) database was utilized to construct the PPI network. The least absolute shrinkage and selection operator (LASSO) regression model and support vector machine recursive feature elimination (SVM-RFE) analysis were used to identify diagnostic genes for IHs. The receiver operating characteristic (ROC) curve evaluated diagnostic genes' discriminatory ability. Single-gene based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) was conducted by Gene Set Enrichment Analysis (GSEA). The chemicals related to the diagnostic genes were excavated by the Comparative Toxicogenomics Database (CTD). Finally, the online website Network Analyst was used to predict the transcription factors targeting the diagnostic genes.

Results

A total of 205 DEGs were singled out from IHs samples of 6-, 12-, and 24-month-old infants. These genes principally participated in vasculogenesis and development-related, endothelial cell-related biological processes. Then we mined 127 interacting proteins and created a network with 127 nodes and 251 edges. Furthermore, LASSO and SVM-RRF algorithms identified five diagnostic genes, namely, TMEM2, GUCY1A2, ISL1, WARS, and STEAP4. ROC curve analysis results indicated that the diagnostic genes had a powerful ability to distinguish IHs samples from normal samples. Next, the results of GSEA for a single gene illustrated that all five diagnostic genes inhibited the "valine, leucine, and isoleucine degradation" pathway in the development of IHs. WARS, TMEM2, and STEAP4 activated the "blood vessel development" and "vasculature development" in IHs. Subsequently, inhibitors targeting TMEM2, GUCY1A2, ISL1, and STEAP4 were mined. Finally, 14 transcription factors regulating GUCY1A2, 14 transcription factors regulating STEAP4, and 26 transcription factors regulating ISL1 were predicted.

Conclusion

This study identified five diagnostic markers for IHs and further explored the mechanisms and targeting drugs, providing a basis for diagnosing and treating IHs.

Three-Dimensional Microtumor Formation of Infantile Hemangioma-Derived Endothelial Cells for Mechanistic Exploration and Drug Screening

Infantile hemangioma (IH) is the most prevalent type of vascular tumor in infants. The pathophysiology of IH is unknown. The tissue structure and physiology of two-dimensional cell cultures differ greatly from those in vivo, and spontaneous regression often occurs during tumor formation in nude mice and has severely limited research into the pathogenesis and development of IH. By decellularizing porcine aorta, we attempted to obtain vascular-specific extracellular matrix as the bioink for fabricating micropattern arrays of varying diameters via microcontact printing. We then constructed IH-derived CD31+ hemangioma endothelial cell three-dimensional microtumor models. The vascular-specific and decellularized extracellular matrix was suitable for the growth of infantile hemangioma-derived endothelial cells. The KEGG signaling pathway analysis revealed enrichment primarily in stem cell pluripotency, RAS, and PI3KAkt compared to the two-dimensional cell model according to RNA sequencing. Propranolol, the first-line medication for IH, was also used to test the model's applicability. We also found that metformin had some impact on the condition. The three-dimensional microtumor models of CD31+ hemangioma endothelial cells were more robust and efficient experimental models for IH mechanistic exploration and drug screening.

Real-time optical imaging of the hypoxic status in hemangioma endothelial cells during propranolol therapy

Infantile hemangioma (IH) is the most common microvascular tumor of infancy involving the area of head and neck. One of the most important independent risk factors of IH is the hypoxia microenvironment. Fluorescent chemosensor provides a noninvasive intervention, high spatiotemporal resolution, ultrasensitive response, and real-time feedback approach to reveal the hypoxic status of cells. Our research group developed an ultrasensitive fluorescent chemosensor, HNT-NTR, and investigated the potential ability of imaging the hypoxic status of hemangioma-derived endothelial cells (HemECs). In this study, we successfully visualized the propranolol (PRN) treatment in HemECs using NHT-NTR with “Turn-off” sensing method. This chemosensor exhibited high sensitivity and selectivity for optical imaging of hypoxic status with fast responsiveness, real-time feedback and durable photostability of the fluorescent signal. It was also confirmed that HNT-NTR could monitor nitroreductase in vivo. Paramountly, we expected this chemosensor to offer an available optical method for imaging of the hypoxic status and visualizing the therapeutic status of PRN therapy in IH with the hypoxia-imaging capability.

Infantile hepatic hemangiomas: looking backwards and forwards

Infantile hepatic hemangiomas (IHHs) are common benign tumors seen in the liver of infants. IHHs are true infantile hemangiomas (IHs) and have phases of proliferation and involution parallel to those of cutaneous IHs. The definition and classification of IHH are still confusing in the literature. The mechanisms during the pathogenesis of IHH have yet to be discovered. The clinical manifestations of IHH are heterogeneous. Although most IHH lesions are asymptomatic, some lesions can lead to severe complications, such as hypothyroidism, consumptive coagulopathy, and high-output congestive cardiac failure. Consequently, some patients can possibly encounter a fatal clinical condition. The heterogeneity of the lesions and the occurrence of disease-related comorbidities can make the treatment of IHH challenging. Oral propranolol is emerging as an effective systemic approach to IHH with obvious responses in tumor remission and symptom regression. However, the precise clinical characteristics and treatment strategies for patients with severe IHH have not yet been well established. Here, we summarize the epidemiology, pathogenic mechanism, clinical manifestations, diagnosis, and treatment of IHH. Recent updates and future perspectives for IHH will also be elaborated.

Morphological, genetic and clinical correlations in infantile hemangiomas and their mimics

Infantile hemangiomas (IHs) are the most frequent pediatric benign vascular tumors, with a reported incidence of 5% to 10%. They have self-limiting evolution pattern divided into a growth phase in the first 12 months and a regression one, that may take up to 10 years. Occasionally, hemangiomas might lead to local or systemic complications, depending on their morphological characteristics. The first line of treatment is β-blockers, such as Propranolol, Timolol, Nadolol, administered either locally or systemically. Newer therapeutic strategies involving laser therapy and angiotensin-converting enzyme inhibitors are being studied, while older treatment modalities like corticosteroids, Imiquimod, Vincristine, Bleomycin and Interferon-α have become second line therapy options. Before establishing the appropriate treatment, clinical, histological, and imaging investigations are required.

Microarray expression profile of mRNAs and long noncoding RNAs and the potential role of PFK-1 in infantile hemangioma

BACKGROUND

Infantile hemangioma (IH) is the most common benign tumor in children. Long noncoding RNAs (lncRNAs) play a critical role in tumorigenesis. However, the expression levels and biological functions of lncRNAs in IH have not been well-studied. This study aimed to analyze the expression profile of lncRNAs and mRNAs in proliferating and involuting IHs.

METHODS

The expression profiles of lncRNAs and mRNAs in proliferating and involuting IHs were identified by microarray analysis. Subsequently, detailed bioinformatics analyses were performed. Finally, quantitative real-time polymerase chain reaction (qRT-PCR) and immunohistochemistry (IHC) analyses were conducted to validate the microarray results.

RESULTS

In total, 146 differentially expressed (DE) lncRNAs and 374 DE mRNAs were identified. The DE mRNAs were enriched mostly in angiogenesis-related biological processes (BPs) and pathways by bioinformatics analysis. In addition, metabolism-related BPs (e.g., "glycogen biosynthetic process" and "metabolic process") and pathways (e.g., "oxidative phosphorylation") were identified. A lncRNA-mRNA co-expression network was constructed from 42 DE lncRNAs and 217 DE mRNAs. Twelve lncRNAs were predicted to have cis-regulated target genes. The microarray analysis results were validated by qRT-PCR using 5 randomly selected lncRNAs and 13 mRNAs. The IHC results revealed that both LOXL2 and FPK-1 exhibited higher protein expression levels in proliferating IH than in involuting IH. Moreover, inhibition of PFK-1 could suppress hemangioma-derived endothelial cell proliferation and migration, induce cell arrest, and reduce glucose uptake and lactate and ATP production.

CONCLUSIONS

The findings suggest that the identified DE lncRNAs and mRNAs may be associated with the pathogenesis of IH. The data presented herein can improve our understanding of IH development and provide direction for further studies investigating the mechanism underlying IH.