MicroRNAs are endogenous single-stranded non-coding small RNA molecules that can be secreted into the circulation and exist stably. They usually exhibit aberrant expression under different physiological and pathological conditions. Recently, differentially expressed circulating microRNAs were focused on as potential biomarkers for cancer screening. We herein review the role of circulating microRNAs for cancer diagnosis, tumor subtype classification, chemo- or radio-resistance monitoring, and outcome prognosis. Moreover, circulating microRNAs still have several issues hindering their reliability for the practical clinical application. Future studies need to elucidate further potential application of circulating microRNAs as specific and sensitive markers for clinical diagnosis or prognosis in cancers.

In the past few years, exosomes released from adipose-derived stem cells (abbreviated as ADSCs) have shown promises to provide therapeutic benefits in the fields of regenerative medicine. miRNAs, existing in exosomes, are endogenous, small noncoding RNAs that play important roles in a variety of cellular functions and tumor development. Emerging evidences have indicated that miR-21 is one of the important miRNAs associated with tumor angiogenesis. In this study, we identified the role of exosomes from ADSCs overexpressing miR-21 in regulating/promoting vascularization of endothelial cells. Experimental data indicated an elevated miR-21 level in exosomes released by ADSCs overexpressing miR-21. In vitro matrigel angiogenesis assay showed that exosomes secreted by ADSCs overexpressing miR-21 significantly promoted the vascularization of HUVEC cells (an endothelial cell line). Quantitative real-time polymerase chain reaction (qRT-PCR) and western blot (WB) revealed an upregulation of HIF-1α, VEGF, SDF-1, p-Akt, p-ERK1/2 and downregulation of PTEN in response to miR-21 overexpression, indicating that miR-21 enriched exosomes induced angiogenesis through Akt and ERK activation and also HIF-1α and SDF-1 expression. Our work suggests that exosomes from ADSCs that overexpressing miR-21 can potentially promote vascularization and therefore the transplantation of exosomes from their culture may be suitable for clinical effort in regenerative medicine.

Keloids exhibit metabolic reprogramming including enhanced glycolysis and attenuated oxidative phosphorylation. Hypoxia induces a series of protective responses in mammalian cells. However, the metabolic phenotype of keloid fibroblasts under hypoxic conditions remains to be elucidated. The present study aimed to investigate glycolytic activity, mitochondrial function and morphology, and the HIF1α and PI3K/AKT signaling pathways in keloid fibroblasts (KFB) under hypoxic conditions. Our results showed that hypoxia promoted proliferation, migration invasion and collagen synthesis and inhibited apoptosis in KFB. The mRNA levels, protein expressions and enzyme activities of glycolytic enzymes in KFB were higher than those in normal skin fibroblasts (NFB) under normoxia. Moreover, hypoxia remarkedly upregulated glycolysis in KFB. Decreased activities of mitochondrial complexes and abnormal mitochondria were detected in KFB under normoxic conditions and the damage was aggravated by hypoxia. An intracellular metabolic profile assay suggested hypoxia increased glycolytic parameters except glycolytic reserve but inhibited the key parameters of mitochondrial function apart from H + leak. Protein levels of HIF1α and phosphorylation levels of the PI3K/AKT signaling pathway were upregulated in the context of 3% oxygen. Enhanced total reactive oxygen species (ROS), mitochondrial ROS (mitoROS) and antioxidant activities of KFB were observed in response to hypoxia. Additionally, autophagy was induced by hypoxia. Our data collectively demonstrated potentiated glycolysis and attenuated mitochondrial function under hypoxia, indicating that altered glucose metabolism regulated by hypoxia could be a therapeutic target for keloids.

Periostin, a secreted extracellular matrix protein, is involved in the wound healing and pathological process of various human cancers. Keloid scars are fibroproliferative tumor-like lesions and develop under local hypoxia. Using suppression subtractive hybridization, in a previous study, we found that periostin is overexpressed in keloids compared with hypertrophic scars. However, little is known about the regulation and function of periostin in keloids. In this study, we examined the effects of periostin on the bioactivity of keloid fibroblasts (KFs) in order to determine whether periostin is involved in hypoxia-stimulated keloid pathogenesis by measuring the expression levels of periostin in KFs cultured under hypoxic conditions. We also investigated the association between periostin and hypoxia-inducible factor-1α (HIF-1α). The mRNA, intracellular protein and secreted protein level of periostin was examined by RT-PCR (and quantitative PCR), western blot analysis and enzyme-linked immunosorbent assay (ELISA), respectively. We also used shRNA targeting periostin to knockdown its expression in the KFs. We report that hypoxia (2% O(2)) upregulates both HIF-1α and periostin expression in KFs. In addition, hypoxia-upregulated periostin expression was regulated by HIF-1α. The inhibition of periostin by short hairpin RNA decreased the hypoxia-stimulated proliferation, collagen synthesis, migration and invasion of KFs and altered the cell cycle, but did not affect apoptosis; treatment with recombinant human periostin protein reversed these effects. Periostin also activated the αvβ3 integrin-PI3K/Akt pathway in the KFs. These findings suggest that hypoxia initiates hyperplasia of KFs and increases periostin expression under hypoxic conditions; periostin is involved in the pathogenesis of keloids, which indicates that periostin may be a novel therapeutic target for keloids and other fibroproliferative disorders.

Periostin, a secreted extracellular matrix protein, is highly expressed in wound healing and in various types of human cancer and is involved in angiogenesis. Keloids, considered dermal benign tumors, are granulomatous lesions characterized by capillary proliferation. However, the underlying regulatory mechanism of angiogenesis in keloids remains to be elucidated. The present study aimed to examine the effect of periostin on angiogenesis in keloids. The expression of periostin was upregulated and the vessel density was higher in human keloids compared with normal tissue, observed following staining with CD31 and CD105. Periostin demonstrated a markedly positive correlation with blood vessel density, which was assessed using CD31 staining (r=0.711; P<0.01) and a weak correlation was observed using CD105 staining (r=0.251; P<0.01). Conditioned medium from keloid fibroblasts (KFs) promoted the migration and tube formation of human umbilical vein endothelial cells (HUVECs) compared with normal fibroblasts and this effect may have been abrogated by the short hairpin RNA knockdown of periostin. Treatment with recombinant human periostin promoted the migration and tube formation of HUVECs by activating the extracellular signal-regulated kinase 1/2 and focal adhesion kinase signaling pathway. In addition, periostin increased the secretion of vascular endothelial growth factor and angiopoietin-1 in the KFs. In conclusion, these data suggested that upregulation in the level of periostin may promote angiogenesis directly and indirectly in keloids and may be a key factor in keloid development. Periostin may, therefore, be a promising therapeutic target in the treatment of keloids and other angioproliferative diseases.

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Flap necrosis is a common complication after mastectomy, and nitroglycerin (NTG) ointment has been used successfully to treat it. However, it is not clear whether topical NTG can completely prevent the occurrence of flap necrosis after breast cancer surgery, and it is also unclear whether this treatment may cause side effects. Three randomized controlled trials (RCTs) and two retrospective cohort studies (RCSs) were included in our investigation. This meta-analysis was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. We found that NTG significantly reduced the rates of mastectomy flap necrosis, full-thickness flap necrosis, and debridement as well as the rate of early complications other than flap necrosis. However, there was no significant difference in drug-related adverse reactions, explantation, superficial flap necrosis, infection, hematoma or seroma between the NTG and placebo groups. Flap-related complications are extremely common after breast surgery, among them, flap necrosis is the most serious and leads to a poor prognosis. In the literature, the reported rates of mastectomy flap necrosis (MFN) range from 5% to 30% 1-9. The rate may continue to rise as nipple-sparing mastectomy and immediate breast reconstruction (IBR) become more prevalent in young breast cancer patients, although there is some evidence that the risks of flap necrosis and implant failure are higher in IBR than in mastectomy alone 10. Nitroglycerin (NTG) effectively increases local blood flow by dilating arteries and veins without altering the ratio of precapillary to postcapillary resistance. Many studies have shown that NTG treatment may improve the survival of random-pattern skin flaps by increasing local blood flow 11-13. Nonetheless, not all studies confirm the utility of NTG in skin flap preservation. Several scholars have found that daily application of NTG slow-release pads offer no greater flap survival than a control treatment 14-17. Furthermore, some of the side effects of NTG may limit its use. However, Ricci has argued that NTG is safe and effective and does not increase the occurrence of side effects 18. Given the lack of consensus on the use of NTG to prevent MFN, the purpose of this meta-analysis is to determine the efficacy and safety of NTG for the prevention of MFN. Debridement is an important solution to skin flap necrosis, but it causes psychological and physical trauma to patients. Further attention should be paid to the debridement rate after mastectomy, especially after IBR, in which circumstances it may cause the tissue expander/implant to be lost. Unfortunately, some studies have suggested that NTG cannot reduce the rate of debridement after IBR 19-21. Hence, another purpose of this article is to determine whether NTG can reduce the flap debridement rate after mastectomy.