Propranolol inhibits growth of hemangioma-initiating cells but does not induce apoptosis

β-Adrenergic Blockers Increase cAMP and Stimulate Insulin Secretion Through a PKA/RYR2/TRPM5 Pathway in Pancreatic β-Cells In Vitro

β-adrenergic blockers (β-blockers) are extensively used to inhibit β-adrenoceptor activation and subsequent cAMP production in many cell types. In this study, we characterized the effects of β-blockers on mouse pancreatic β-cells. Unexpectedly, high concentrations (100 μM) of β-blockers (propranolol and bisoprolol) paradoxically increased cAMP levels 5-10 fold, enhanced Ca2+ influx, and stimulated a 2-4 fold increase in glucose- and glimepiride-induced insulin secretion in MIN6-K8 clonal β-cells and isolated mouse pancreatic islets. These effects were observed despite minimal expression of β-adrenoceptors in these cells. Mechanistically, the cAMP increase led to ryanodine receptor 2 (RYR2) phosphorylation via protein kinase A (PKA), triggering Ca2+-induced Ca2+ release (CICR). CICR then activates transient receptor potential cation channel subfamily M member 5 (TRPM5), resulting in increased Ca2+ influx via voltage-dependent Ca2+ channels. These effects contradict the conventional understanding of the pharmacology of β-blockers, highlighting the variability in β-blocker actions depending on the experimental context.

Overview of the Head and Neck Hemangiomas: a 5-year Retrospective Study

Background

Infantile hemangiomas (IHs) are benign vascular tumors commonly observed in children. The pathogenesis of hemangiomas is complex and poorly understood. IH occur most commonly on the head and neck. There are different classification of them according to the depth, number, distribution and locations. A multidisciplinary approach is needed for the diagnosis and treatment of hemangiomas because it is easy to misdiagnose or decide on a wrong treatment in the existing single-treatment system.

Objective

In this retrospective study between 2018 and 2022 we provided an overview of the hemangiomas located in the head and neck in 232 patients, and the different treatment approaches used.

Results

Of the 232 patients 60.3 % were females and 38.7% males. The youngest age was 10 weeks old and the oldest age who underwent treatment was 79 years old. The most common lesion sites were the mid-cheek, the upper lip and the upper eyelid. 104 patients (53.4 %) underwent surgical intervention due to the location of the lesion, size and functional reasons. Meanwhile 128 patients (46.6 %) were observed and treated with propranolol and pulsed dye laser.

Conclusion

Hemangiomas are generally benign tumors. Hemangiomas present a number of diagnostic and therapeutic challenges; thus, early diagnosis by a specialist clinic is key in preventing associated morbidity with these vascular tumors.

Infantile hemangiomas β3-adrenoceptor overexpression is associated with nonresponse to propranolol

BACKGROUND

Propranolol (antagonist of β₁-/β₂-AR but minimally active against β₃-AR) is currently the first-line treatment for infantile hemangiomas (IH). Its efficacy is attributed to the blockade of β₂-AR. However, its success rate is ~60%. Considering the growing interest in the angiogenic role of β₃-ARs, we evaluated a possible relationship between β₃-AR expression and response to propranolol.

METHODS

Fifteen samples of surgical biopsies were collected from patients with IH. Three were taken precociously from infants and then successfully treated with propranolol (responder group). Twelve were taken later, from residual lesions noncompletely responsive to propranolol (nonresponder group). A morphometrical analysis of the percentage of β₁-, β₂-, and β₃-ARs positively stained area was compared between the two groups.

RESULTS

While no difference was found in both β₁- and β₂-AR expression level, a statistically significant increase of β₃-AR positively stained area was observed in the nonresponder group.

CONCLUSIONS

Although the number of biopsies is insufficient to draw definitive conclusions, and the different β-AR pattern may be theoretically explained by the different timing of samplings, this study suggests a possible correlation between β₃-AR expression and the reduced responsiveness to propranolol treatment. This study could pave the way for new therapeutic perspectives to manage IH.

IMPACT

Propranolol (unselective antagonist of β₁ and β₂-ARs) is currently the first-line treatment for IHs, with a success rate of ~60%. Its effectiveness has been attributed to its ability to block β₂-ARs. However, β₃-ARs (on which propranolol is minimally active) were significantly more expressed in hemangioma biopsies taken from patients nonresponsive to propranolol. This study suggests a possible role of β₃-ARs in hemangioma pathogenesis and a possible new therapeutic target.

Epithelial-mesenchymal transition: a hallmark in pancreatic cancer stem cell migration, metastasis formation, and drug resistance

Metastasis, tumor progression, and chemoresistance are the major causes of death in patients with pancreatic ductal adenocarcinoma (PDAC). Tumor dissemination is associated with the activation of an epithelial-to-mesenchymal transition (EMT) process, a program by which epithelial cells lose their cell polarity and cell-to-cell adhesion, and acquire migratory and invasive abilities to become mesenchymal stem cells (MSC). These MSCs are multipotent stromal cells capable of differentiating into various cell types and trigger the phenotypic transition from an epithelial to a mesenchymal state. Therefore, EMT promotes migration and survival during cancer metastasis and confers stemness features to particular subsets of cells. Furthermore, a major problem limiting our ability to treat PDAC is the existence of rare populations of pancreatic cancer stem cells (PCSCs) or cancer-initiating cells in pancreatic tumors. PCSCs may represent sub-populations of tumor cells resistant to therapy which are most crucial for driving invasive tumor growth. These cells are capable of regenerating the cellular heterogeneity associated with the primary tumor when xenografted into mice. Therefore, the presence of PCSCs has prognostic relevance and influences the therapeutic response of tumors. PCSCs express markers of cancer stem cells (CSCs) including CD24, CD133, CD44, and epithelial specific antigen as well as the drug transporter ABCG2 grow as spheroids in a defined growth medium. A major difficulty in studying tumor cell dissemination and metastasis has been the identification of markers that distinguish metastatic cancer cells from cells that are normally circulating in the bloodstream or at sites where these cells metastasize. Evidence highlights a linkage between CSC and EMT. In this review, The current understanding of the PCSCs, signaling pathways regulating these cells, PDAC heterogeneity, EMT mechanism, and links between EMT and metastasis in PCSCs are summarised. This information may provide potential therapeutic strategies to prevent EMT and trigger CSC growth inhibition and cell death.

Unrelenting facial segmental hemangiomas: A case series of late growth and recurrent ulcerations

Late growth of infantile hemangiomas is an uncommon complication. We report three patients with segmental facial hemangiomas who experienced late growth and recurrent ulceration predominantly of the lower lip. These patients shared common clinical features including involvement of the S3 facial segment, oral and airway hemangiomas, and vascular anomalies associated with PHACE syndrome. This report highlights a clinical presentation at-risk for late growth and recurrent ulceration.

NOTCH pathway activation in infantile hemangiomas

OBJECTIVE

The objective of this study was to characterize the role of NOTCH signaling cascade activation in the angiogenic drive of infantile hemangioma (IH) tissue.

METHODS

Both IH tissue and normal skin were collected from 55 surgical patients. Of these, 14 were proliferating hemangiomas, 14 were stationary, 14 were involuted, and 13 had been treated with propranolol. Protein and RNA were extracted from all tissues and subjected to Western blotting and reverse transcription-polymerase chain reaction, respectively, for components of the NOTCH signaling pathway.

RESULTS

Compared with normal skin from the same patients, proliferating IHs contained higher levels of messenger RNA and protein for the majority of NOTCH receptors and ligands as well as the downstream coactivator MAML1. Expression of NOTCH receptor ligand messenger RNA and protein was significantly lower in involuting and propranolol-treated IHs.

CONCLUSIONS

Perturbations in NOTCH signaling follow the natural course and treatment outcome of IHs, suggesting a critical role in their pathogenesis.

Drug repositioning for rare diseases: Knowledge-based success stories

While more than 7000 rare diseases have been identified, only about 5 percent benefit from a licensed treatment. As the majority of these diseases is life threatening, these facts underscore the need for new drugs. Drug repositioning is an alternative strategy in drug development, which represents an attractive opportunity for rare diseases. Drug repositioning (also called drug repurposing, drug reprofiling or drug re-tasking) consists in identifying for an already approved or investigational drug a new use outside the scope of the original medical indication. Drug repositioning is considered in the field of orphan drugs as being a faster and somehow less costly strategy than traditional new drug development for pharmaceutical companies. While several successful repositioning cases have been discovered by serendipity, most successes straightly derive from the molecular characterization of the concerned disease. This short commentary is mainly dedicated to these rationally-based success stories.

Effect of combined low-dose oral prednisone with beta-adrenergic receptor antagonists for refractory infantile hemangiomas: retrospective cohort study in 76 patients

Background

Beta-adrenergic receptor antagonists have been the first-line treatment for infantile hemangiomas (IHs); however, monotherapy may fail to achieve sufficient efficacy for certain patients, especially for refractory IHs. The aim of this study was to evaluate the efficacy and safety of the combination of prednisone and beta-adrenergic receptor antagonists for refractory IHs.

Methods

We studied 76 patients with refractory IHs. After more than one month of insufficient oral propranolol therapy, forty-four patients received additional treatment of prednisone, while thirty-two patients continued to receive beta-adrenergic receptor antagonists monotherapy. The response to treatment was assessed according to hemangioma score values.

Results

The outcomes of patients after combined treatment were significantly better than those with monotherapy of beta-adrenergic receptor antagonists. The age to initiate prednisone was significantly negatively correlated with the improvement in the combination treatment group. The age at initiate treatment showed significant correlation with score variation percentage in both groups. There was no significant difference in the treatment duration observed between the two groups. Multivariable logistic regression analysis for all patients showed prednisone administration was the most important factor to better overall outcomes.

Conclusions

Short-term addition of low-dose oral prednisone is an effective and safe adjunctive treatment for oral propranolol in contributing to refractory IH. Both early administration and long enough duration would be necessary.

Oral propranolol in the treatment of proliferating infantile haemangiomas: British Society for Paediatric Dermatology consensus guidelines

BACKGROUND

Infantile haemangiomas (IH) are the most common vascular tumours of infancy. Despite their frequency and potential complications, there are currently no unified U.K. guidelines for the treatment of IH with propranolol. There are still uncertainties and diverse opinions regarding indications, pretreatment investigations, its use in PHACES (posterior fossa malformations-haemangiomas-arterial anomalies-cardiac defects-eye abnormalities-sternal cleft and supraumbilical raphe) syndrome and cessation of treatment.

OBJECTIVES

To provide unified guidelines for the treatment of IH with propranolol.

METHODS

This study used a modified Delphi technique, which involved an international treatment survey, a systematic evidence review of the literature, a face-to-face multidisciplinary panel meeting and anonymous voting.

RESULTS

The expert panel achieved consensus on 47 statements in eight categories, including indications and contraindications for starting propranolol, pretreatment investigations, starting and target dose, monitoring of adverse effects, the use of propranolol in PHACES syndrome and how to stop treatment.

CONCLUSIONS

These consensus guidelines will help to standardize and simplify the treatment of IH with oral propranolol across the U.K. and assist in clinical decision-making.

The beta adrenergic receptor antagonist propranolol alters mitogenic and apoptotic signaling in late stage breast cancer

Background

Substantial evidence supports the use of inexpensive β-AR antagonists (beta blockers) against a variety of cancers, and the β-AR antagonist propranolol was recently approved by the European Medicines Agency for the treatment of soft tissue sarcomas. Prospective and retrospective data published by our group and others suggest that non-selective β-AR antagonists are effective at reducing proliferative rates in breast cancers, however the mechanism by which this occurs is largely unknown.

Methods

In this study, we measured changes in tumor proliferation and apoptosis in a late stage breast cancer patient treated with neoadjuvant propranolol. We expounded upon these clinical findings by employing an in vitro breast cancer model, where we used cell-based assays to evaluate propranolol-mediated molecular alterations related to cell proliferation and apoptosis.

Results

Neoadjuvant propranolol decreased expression of the pro-proliferative Ki-67 and pro-survival Bcl-2 markers, and increased pro-apoptotic p53 expression in a patient with stage III breast cancer. Molecular analysis revealed that β-AR antagonism disrupted cell cycle progression and steady state levels of cyclins. Furthermore, propranolol treatment of breast cancer cells increased p53 levels, enhanced caspase cleavage, and induced apoptosis.

Conclusion

Collectively, these data provide support for the incorporation of β-AR antagonists into the clinical management of breast cancer, and elucidate a partial molecular mechanism explaining the efficacy of β-AR antagonists against this disease.

Propranolol-Loaded Mesoporous Silica Nanoparticles for Treatment of Infantile Hemangiomas

Infantile hemangioma (IH) is one of the most common neoplasm of infancy. Although with the potential to involute slowly after proliferation, IH has several subsets that could develop severe complications and lead to functional impairment or permanent disfigurement. In the present study, a novel propranolol (PRN) delivery system is developed that encapsulated in mesoporous silica nanoparticles (MSN). The primary nanoparticles are further treated with polyvinyl alcohol (PVA) to form PVA-MSN-PRN nanoparticles. The encapsulation efficiency is 58.8% ± 7.2%, and nanoparticles could release PRN in a controlled-release way. It is discovered that PVA-MSN-PRN could significantly suppress hemangioma stem cell (Hemsc) proliferation, promote Hemsc apoptosis in vitro, and inhibit the growth of hemangiomain xenografts in vivo. A conclusion could be made that this novel nanodrug delivery system has high therapeutic efficacy, low cytotoxicity, low administration frequency, and provides an attractive strategy for efficient IH therapy.

Propranolol induces hemangioma endothelial cell apoptosis via a p53‑BAX mediated pathway

The use of propranolol for the treatment of infantile hemangioma (IH) has been widely investigated in recent years. However, the underlying therapeutic mechanism of propranolol for the treatment of IH remains poorly understood. The aim of the present study was to investigate the expression of proteins regulated by cellular tumor antigen p53 (p53) in associated apoptosis pathways in IH endothelial cells (HemECs) treated with propranolol. Furthermore, the present study aimed to investigate the exact apoptotic pathway underlying the therapeutic effect of propranolol against IH. In the present study, HemECs were subcultured and investigated using an inverted phase contrast microscope, immunocytochemical staining and a scanning electron microscope (SEM). Experimental groups and blank control groups were prepared. All groups were subjected to drug treatment. A high p53 expression model of HemECs was successfully established via transfection, and a low p53 expression model of HemECs was established using pifithrin-α. The apoptosis rate of each group was determined using Annexin V-fluorescein isothiocyanate/propidium iodide double staining and flow cytometry. The expression levels of downstream proteins regulated by p53 [tumour necrosis factor receptor superfamily member 6 (FAS), p53-induced death domain-containing protein (PIDD), death receptor 5 (DR5), BH3-interacting domain death agonist (BID), apoptosis regulator BAX (BAX), p53 unregulated modulator of apoptosis (PUMA), phosphatidylinositol-glycan biosynthesis class S protein (PIGS), and insulin-like growth factor-binding protein 3 (IGF-BP3)] were revealed in the experimental and control groups via western blotting. Microscopic observation revealed the growth of an adherent monolayer of cells, which were closely packed and exhibited contact inhibition. Immunocytochemical staining demonstrated increased expression of clotting factor VIII. SEM analysis revealed presence of Weibel-Palade bodies. The results of the analyses verified that the cultured cells were HemECs. The staining of the samples resulted in a significantly increased rate of apoptosis in experimental groups compared with the blank control group. This result suggested that there is an association between p53 expression and the rate of apoptosis of propranolol-treated HemECs. The results of the western blot analysis demonstrated an upregulation of BAX expression and a downregulation of IGF-BP3 expression in the HemECs treated with propranolol. There were no significant differences in the expression levels of FAS, DR5, PIDD, BID, PUMA and PIGS between experimental and control groups. This result suggests that p53 has an important role in HemEC apoptosis. The results of the present study additionally suggest that the propranolol-induced HemEC apoptosis pathway is a mitochondrial apoptosis pathway and is regulated by p53-BAX signaling.

Molecular and immunohistochemical expression of apoptotic proteins Bax, Bcl-2 and Caspase 3 in infantile hemangioma tissues as an effect of propranolol treatment

BACKGROUND

Infantile hemangiomas (IHs) are the most common benign tumors of childhood. They are characterized by a unique clinical course with two phases, proliferation and involution, which are followed by regression. The therapy of infantile hemangiomas was revolutionized in 2008 by the introduction of propranolol, however, the mechanism of its influence on hemangiomas remains unclear.

METHODS

The study included 71 patients with IHs, 27 of whom were treated with propranolol while the remaining 44 were used as a comparative group. The expression of Bcl-2, Bax and Caspase3 was determined with immunohistochemistry and mRNA of Bax, Bcl-2 and Caspase3 were assessed with the use of RT-PCR.

RESULTS

Both methods revealed a statistically significant decrease in Bcl-2 expression and an increase in Bax in IHs tissues after propranolol treatment.

CONCLUSIONS

The results obtained for Bax and Bcl-2 proteins may indicate a link between the effect of propranolol and apoptosis. Higher Bax and lower Bcl-2 expression in the propranolol treated group indicates a strong pro- apoptotic action countering any anti-apoptotic activity; apoptosis was indicted in IH tissue as a potential result of propranolol treatment, with potential clinical impact in other tumors.

Approach to Infantile Hemangiomas

Infantile hemangiomas are a group of vascular tumors and are considered to be one of the most common tumors in infancy. Ambiguity still prevails over its origin, etiopathogenesis, and optimal management.

Rebound Growth of Infantile Hemangiomas After Propranolol Therapy

BACKGROUND AND OBJECTIVES

Propranolol is first-line therapy for problematic infantile hemangiomas (IHs). Rebound growth after propranolol discontinuation is noted in 19% to 25% of patients. Predictive factors for rebound are not completely understood and may alter the management approach. The goal of the study was to describe a cohort of patients with IHs treated with propranolol and to identify predictors for rebound growth.

METHODS

A multicenter retrospective cohort study was conducted in patients with IHs treated with propranolol. Patient demographic characteristics, IH characteristics, and specifics of propranolol therapy were obtained. Episodes of rebound growth were recorded. Patients' responses to propranolol were evaluated through a visual analog scale.

RESULTS

A total of 997 patients were enrolled. The incidence of rebound growth was 231 of 912 patients (25.3%). Mean age at initial rebound was 17.1 months. The odds of rebound among those who discontinued therapy at <9 months was 2.4 (odds ratio [OR]: 2.4; 95% confidence interval [CI]: 1.3 to 4.5; P = .004) compared with those who discontinued therapy between 12 to 15 months of life. Female gender, location on head and neck, segmental pattern, and deep or mixed skin involvement were associated with rebound on univariate analysis. With multivariate analysis, only deep IHs (OR: 3.3; 95% CI: 1.9 to 6.0; P < .001) and female gender (OR: 1.7; 95% CI: 1.1 to 2.6; P = .03) were associated. Of those with rebound growth, 83% required therapeutic modification including 62% of patients with modifications in their propranolol therapy.

CONCLUSIONS

Rebound growth occurred in 25% of patients, requiring modification of systemic therapy in 15%. Predictive factors for rebound growth included age of discontinuation, deep IH component, and female gender. Patients with these predictive factors may require a prolonged course of therapy.

Propranolol versus captopril in the treatment of infantile hemangioma (IH): A randomized controlled trial

BACKGROUND

Renin-angiotensin system components have been demonstrated in the biology of infantile hemangioma (IH). Captopril, an angiotensin-converting enzyme inhibitor, is proposed as a therapeutic alternative to oral propranolol.

OBJECTIVES

We sought to compare the benefit of propranolol and captopril in the treatment of IH, and to assess angiotensin-converting enzyme gene polymorphism in patients with IH and in control subjects.

METHODS

Thirty patients with IH and 35 healthy control subjects were enrolled in this study. Patients were randomly assigned to treatment with either propranolol or captopril. Assessment was done clinically and by measurement of serum vascular endothelial growth factor and angiotensin II in patients and control subjects. Angiotensin-converting enzyme gene polymorphism was also studied.

RESULTS

Clinical improvement was significantly better and faster in the patients treated with propranolol. Both groups showed reduced vascular endothelial growth factor and angiotensin II levels posttreatment, with a significantly higher percentage reduction in the propranolol-treated group. Cardiac side effects were reported only in the captopril-treated group. Baseline vascular endothelial growth factor level was significantly higher, and baseline angiotensin II level was significantly lower, in patients than control subjects.

LIMITATIONS

We studied a relatively small number of patients and control subjects.

CONCLUSION

Propranolol shows greater benefit than captopril in the treatment of IH.

Propranolol: Effectiveness and Failure in Infantile Cutaneous Hemangiomas

Infantile hemangiomas (IHs) occur in early infancy and are considered to be one of the most frequent childhood tumors. Poor responsiveness to the treatment and complications are reported in about 10 % of patients. For years, the most common treatments for cutaneous and complicated IHs were corticosteroids, interferon-α, vincristine, laser therapy, or surgical intervention. More recently, treatment with propranolol has been reported with high success rates, both in the cutaneous and complicated form of IHs, and it is now considered to be the first-line treatment for IHs. Herein we report five cases of cutaneous IHs who presented at our unit between January 2011 and June 2012: in three of five patients, the lesion improved soon after the beginning of propranolol treatment; one case presented slow but complete resolution; and in one patient the treatment was unsuccessful. Patients who do not respond to propranolol have been seldom reported in the literature. However, the failure of propranolol treatment in childhood hemangiomas has been more frequent in our experience than that reported in previous case series. More attention should be given to the cases that poorly or negatively respond to treatment, and to the mechanisms underlying the failure to respond to treatment with propranolol.

Propranolol Targets Hemangioma Stem Cells via cAMP and Mitogen-Activated Protein Kinase Regulation

Infantile hemangiomas (IHs) are the most common vascular tumor and arise from a hemangioma stem cell (HemSC). Propranolol has proved efficacious against IHs. A selective β2-adrenergic receptor (AR) antagonist mirrored propranolol’s effects on HemSCs. These results show that propranolol acts on HemSCs in IH to suppress proliferation and promote apoptosis in a dose-dependent fashion via β2AR perturbation.

Infantile hemangiomas (IHs) are the most common vascular tumor and arise from a hemangioma stem cell (HemSC). Propranolol has proved efficacious for problematic IHs. Propranolol is a nonselective β-adrenergic receptor (βAR) antagonist that can lower cAMP levels and activate the mitogen-activated protein kinase (MAPK) pathway downstream of βARs. We found that HemSCs express β1AR and β2AR in proliferating IHs and determined the role of these βARs and the downstream pathways in mediating propranolol’s effects. In isolated HemSCs, propranolol suppressed cAMP levels and activated extracellular signal-regulated kinase (ERK)1/2 in a dose-dependent fashion. Propranolol, used at doses of <10⁻⁴ M, reduced cAMP levels and decreased HemSC proliferation and viability. Propranolol at ≥10⁻⁵ M reduced cAMP levels and activated ERK1/2, and this correlated with HemSC apoptosis and cytotoxicity at ≥10⁻⁴ M. Stimulation with a βAR agonist, isoprenaline, promoted HemSC proliferation and rescued the antiproliferative effects of propranolol, suggesting that propranolol inhibits βAR signaling in HemSCs. Treatment with a cAMP analog or a MAPK inhibitor partially rescued the HemSC cell viability suppressed by propranolol. A selective β2AR antagonist mirrored propranolol’s effects on HemSCs in a dose-dependent fashion, and a selective β1AR antagonist had no effect, supporting a role for β2AR signaling in IH pathobiology. In a mouse model of IH, propranolol reduced the vessel caliber and blood flow assessed by ultrasound Doppler and increased activation of ERK1/2 in IH cells. We have thus demonstrated that propranolol acts on HemSCs in IH to suppress proliferation and promote apoptosis in a dose-dependent fashion via β2AR perturbation, resulting in reduced cAMP and MAPK activation.

Significance

The present study investigated the action of propranolol in infantile hemangiomas (IHs). IHs are the most common vascular tumor in children and have been proposed to arise from a hemangioma stem cell (HemSC). Propranolol, a nonselective β-adrenergic receptor (βAR) antagonist, has proven efficacy; however, understanding of its mechanism of action on HemSCs is limited. The presented data demonstrate that propranolol, via βAR perturbation, dose dependently suppresses cAMP levels and activated extracellular signal-regulated kinase 1/2. Furthermore, propranolol acts via perturbation of β2AR, and not β1AR, although both receptors are expressed in HemSCs. These results provide important insight into propranolol’s action in IHs and can be used to guide the development of more targeted therapy.

Diagnosis and Management of Infantile Hemangioma

Infantile hemangiomas (IHs) are the most common tumors of childhood. Unlike other tumors, they have the unique ability to involute after proliferation, often leading primary care providers to assume they will resolve without intervention or consequence. Unfortunately, a subset of IHs rapidly develop complications, resulting in pain, functional impairment, or permanent disfigurement. As a result, the primary clinician has the task of determining which lesions require early consultation with a specialist. Although several recent reviews have been published, this clinical report is the first based on input from individuals representing the many specialties involved in the treatment of IH. Its purpose is to update the pediatric community regarding recent discoveries in IH pathogenesis, treatment, and clinical associations and to provide a basis for clinical decision-making in the management of IH.

Educational paper: therapy of infantile haemangioma--history and current state (part II)

Infantile haemangioma (IH) is the most frequent tumour of infancy. Although it is benign and self-limiting, severe complications can arise due to localisation and fast tumour growth. Also, IHs leave scars after regression in more than half of the cases. Management and therapy of IH have changed greatly after 2008. This update provides an overview of the older therapy options before 2008, which mainly consisted of the administration of corticosteroids, and discusses the modern management with new therapy options such as β-blockers (both systemically and topically).

CONCLUSION

β-blockers are promising and are currently preferred above corticosteroids, but β-blockers still do not give a definitive treatment.

Mechanisms of propranolol action in infantile hemangioma

Infantile hemangioma is a common tumor of infancy. Although most hemangiomas spontaneously regress, treatment is indicated based on complications, risk to organ development and function, and disfigurement. The serendipitous discovery of propranolol, a non-selective β-adrenergic receptor blocker, as an effective means to regress hemangiomas has made this a first-line therapy for hemangioma patients. Propranolol has shown remarkable response rates. There are, however, some adverse effects, which include changes in sleep, acrocyanosis, hypotension, and hypoglycemia. Over the last few years, researchers have focused on understanding the mechanisms by which propranolol causes hemangioma regression. This has entailed study of cultured vascular endothelial cells including endothelial cells isolated from hemangioma patients. In this article, we review recent studies offering potential mechanisms of how various cell types found in hemangioma may respond to propranolol.

The use of propranolol in the treatment of infantile haemangiomas: an update on potential mechanisms of action

Currently, propranolol is the preferred treatment for problematic proliferating infantile haemangiomas (IHs). The rapid action of propranolol has been shown to be especially dramatic in IHs involving dyspnoea, haemodynamic compromise, palpebral occlusion or ulceration. Another remarkable aspect of propranolol treatment revealed that the growth of the IHs was not only stabilized, but also that the improvement continued until complete involution was achieved, leading to a considerable shortening of the natural course of IH. However, the mechanisms underlying the effects of propranolol have not been fully elucidated. Recent studies have offered evidence of a variety of mechanisms. These include the promotion of pericyte-mediated vasoconstriction, the inhibition of vasculogenesis and catecholamine-induced angiogenesis, the disruption of haemodynamic force-induced cell survival, and the inactivation of the renin-angiotensin system. This review summarizes these mechanisms and the new concepts that are emerging in this area of research. Moreover, several molecular mechanisms by which propranolol may modify neovascularization in IH have also been proposed. The antihaemangioma effect of propranolol may not be attributable to a single mechanism, but rather to a combination of events that have not yet been elucidated or understood. Further studies are needed to evaluate and verify these mechanisms to gain a greater understanding of the effects of the intake of propranolol on haemangioma involution.

Infantile hemangiomas, retinopathy of prematurity and cancer: a common pathogenetic role of the β-adrenergic system

The serendipitous demonstration that the nonselective β-adrenergic receptor (β-AR) antagonist propranolol promotes the regression of infantile hemangiomas (IHs) aroused interest around the involvement of the β-adrenergic system in angiogenic processes. The efficacy of propranolol was related to the β2-AR blockade and the consequent inhibition of the production of vascular endothelial growth factor (VEGF), suggesting the hypothesis that propranolol could also be effective in treating retinopathy of prematurity (ROP), a retinal pathology characterized by VEGF-induced neoangiogenesis. Consequent to the encouraging animal studies, a pilot clinical trial showed that oral propranolol protects newborns from ROP progression, even though this treatment is not sufficiently safe. Further, animal studies clarified the role of β3-ARs in the development of ROP and, together with several preclinical studies demonstrating the key role of the β-adrenergic system in tumor progression, vascularization, and metastasis, prompted us to also investigate the participation of β3-ARs in tumor growth. The aim of this review is to gather the recent findings on the role of the β-adrenergic system in IHs, ROP, and cancer, highlighting the fact that these different pathologies, triggered by different pathogenic noxae, share common pathogenic mechanisms characterized by the presence of hypoxia-induced angiogenesis, which may be contrasted by targeting the β-adrenergic system. The mechanisms characterizing the pathogenesis of IHs, ROP, and cancer may also be active during the fetal-neonatal development, and a great contribution to the knowledge on the role of β-ARs in diseases characterized by chronic hypoxia may come from research focusing on the fetal and neonatal period.

Adhesion molecule-mediated hippo pathway modulates hemangioendothelioma cell behavior

Hemangioendotheliomas are categorized as intermediate-grade vascular tumors that are commonly localized in the lungs and livers. The regulation of this tumor cell's proliferative and apoptotic mechanisms is ill defined. We recently documented an important role for Hippo pathway signaling via endothelial cell adhesion molecules in brain microvascular endothelial cell proliferation and apoptosis. We found that endothelial cells lacking cell adhesion molecules escaped from contact inhibition and exhibited abnormal proliferation and apoptosis. Here we report on the roles of adherens junction molecule modulation of survivin and the Hippo pathway in the proliferation and apoptosis of a murine hemangioendothelioma (EOMA) cell. We demonstrated reduced adherens junction molecule (CD31 and VE-cadherin) expression, increased survivin and Ajuba expression, and a reduction in Hippo pathway signaling resulting in increased proliferation and decreased activation of effector caspase 3 in postconfluent EOMA cell cultures. Furthermore, we confirmed that YM155, an antisurvivin drug that interferes with Sp1-survivin promoter interactions, and survivin small interference RNA (siRNA) transfection elicited induction of VE-cadherin, decreased Ajuba expression, increased Hippo pathway and caspase activation and apoptosis, and decreased cell proliferation. These findings support the importance of the Hippo pathway in hemangioendothelioma cell proliferation and survival and YM155 as a potential therapeutic agent in this category of vascular tumors.

Propranolol enhanced adipogenesis instead of induction of apoptosis of hemangiomas stem cells

Propranolol has been widely used in treating infantile hemangiomas (IHs). But recurrence of IHs was found in some cases on cessation of propranolol treatment. The other is that Chinese individuals reacted to propranolol differently from American Whites. Whether the difference of sensitivity is due to the β adrenoceptor (β-AR) expression pattern of hemangioma initiating cells remains unclear. In the present study, we isolated hemangioma-derived stem cells (hemSCs) from proliferative IHs and analyzed the biological characteristics and β-AR expression pattern of hemSCs by immunostaining, Western blotting and multilineage differentiation assay as well. We also tested the effects of propranolol on hemSCs by evaluating VEGF expression, proliferation and apoptosis related parameters. Our results indicated that CD133(+) hemSCs located pre-vascular in proiferative IH tissues. Both β1 and β2-AR were expressed, while β2-AR was dominant on hemSCs. Propranolol at 100-150 μM inhibited proliferation of hemSCs, not did 50 μM. Propranolol down-regulated VEGF expression of hemSCs, instead of inducing apoptosis. The adipogenic potential was enhanced by propranolol. Therefore, our current results suggested propranolol could not induce apoptosis of hemSCs, but played a curative role though suppressing VEGF synthesis and enhancement of adipogenesis of hemSCs. Our results might partially provide the insight of mechanism of relapse in some cases on cessation of propranolol treatment.