Mechanisms of Action of MicroRNAs in Infantile Hemangioma Tissue and Vascular Endothelial Cells in Different Periods

Hemangioma Endothelial Cells and Hemangioma Stem Cells in Infantile Hemangioma

BACKGROUND

Hemangioma is one of the most common benign tumors in infants and young children. The 2 most important cells in the course of infantile hemangioma (IH) are hemangioma stem cells (HemSCs) and hemangioma endothelial cells (HemECs). Infantile hemangioma is characterized by massive proliferation of HemECs, but current studies indicate that HemSCs play an important role in pathogenesis of IH.

OBJECTIVE

This review aimed to identify molecules that influence HemSC differentiation and HemEC proliferation and apoptosis to help clarify the pathogenesis of IH and provide novel drug targets for the treatment of IH.

METHODS

Relevant basic science studies related to IH were identified by searching Google Scholar, Embase, PubMed, MEDLINE, and peer-reviewed journal articles.

RESULT

Hemangioma stem cells can differentiate into HemECs, pericytes, and adipocytes. In the proliferating phase of IH, HemSCs mainly differentiate into HemECs and pericytes to promote angiogenesis. In the regressive phase, they mainly differentiate into adipocytes. Therefore, increasing the proportion of HemSCs differentiating into adipocytes, inhibiting the proliferation of HemECs, and promoting the apoptosis of HemECs can facilitate the regression of IH.

Propranolol inhibits infantile hemangioma by regulating the miR-424/vascular endothelial growth factor-A (VEGFA) axis

BACKGROUND

Infantile hemangioma (IHA) is the most common tumor in infancy. We aimed to explore the effect of propranolol on the expression of microRNA (miR)-424 in IHA tissues and XPTS-1 cells, as well as its molecular mechanism of inhibiting XPTS-1 cell activity.

METHODS

Tumor tissues and peritumoral tissue were collected from 13 IHA patients in Lishui Municipal Central Hospital. The level of miR-424 were detected using real-time quantitative reverse transcription polymerase chain reaction (RT-PCR). Cell counting kit-8 (CCK-8) was used to measure XPTS-1 cell viability. Flow cytometry and transwell were used to detect the apoptosis level and invasion ability of XPTS-1 cells. Western blot was used to measure the protein level of vascular endothelial growth factor-A (VEGFA). The luciferase reporter gene assay detected the targeting relationship between miR-424 and VEGFA.

RESULTS

Compared with normal tissues and human umbilical vein endothelial cells, the expression level of miR-424 in IHA tissues and XPTS-1 cells was significantly reduced (P<0.05). As the concentration of propranolol increased, XPTS-1 cell viability gradually decreased (P<0.05), and the expression level of VEGFA decreased (P<0.05). The expression of miR-424 increased with the time of propranolol treatment (P<0.05). Compared with the control group, treatment with an miR-424 inhibitor resulted in a significant increase in XPTS-1 cell viability and invasion ability (P<0.05), and a decrease in apoptosis (P<0.05). However, both propranolol and miR-424 inhibitor treatment resulted in a partial decrease in XPTS-1 cell viability (P<0.05), and a partial increase in the level of apoptosis (P<0.05). MiR-424 directly targeted VEGFA; the overexpression of miR-424 resulted in a decrease in the VEGFA protein level (P<0.05), while inhibition of miR-424 resulted in an increase in the VEGFA protein level (P<0.05). Compared with the propranolol group, the XPTS-1 cell viability and invasion ability in the propranolol + VEGFA-si group were significantly decreased (P<0.05), while the level of apoptosis increased (P<0.05). Meanwhile, simultaneous miR-424 inhibitor treatment resulted in no difference in cell viability and apoptosis levels compared with the propranolol group, and the invasion ability was partially restored (P<0.05).

CONCLUSIONS

Propranolol affects the malignant biological behavior of IHA cells by regulating the miR-424/VEGFA axis.

Infantile hemangiomas: what have we learned from propranolol?

PURPOSE OF REVIEW

Infantile hemangiomas are the most common vascular tumor of infancy. Treatment of infantile hemangiomas was revolutionized when propranolol, a nonselective β-blocker, was reported to be effective therapy. In this review, we highlight the lessons learned using propranolol to treat infantile hemangiomas. We also describe the ongoing effort to understand the mechanism of action of propranolol.

RECENT FINDINGS

Although the pathogenesis of infantile hemangiomas is not fully understood, maternal hypoxic stress and embolization of placental tissue are suggested to be critical components in their development. The mechanism of action of propranolol remains unclear, however various molecular mechanisms are detailed in this review. Propranolol treatment remains a well tolerated therapy, with low risk of adverse events or long-term neurocognitive effects. Dosing recommendations and optimal treatment duration vary among studies, and should be altered in patients with certain medical conditions such as Posterior fossa anomalies, Hemangioma, Arterial lesions, Cardiac abnormalities/coarctation of the aorta, Eye anomalies (PHACE) syndrome.

SUMMARY

Propranolol is a well tolerated and effective treatment for infantile hemangiomas. The efficacy of propranolol for infantile hemangiomas is clear, however questions pertaining to mechanism of action, pretreatment risk stratification, and optimal dosing remain unanswered. The guidelines for managing infantile hemangiomas with propranolol will continue to adapt as research catches up to clinical experience.