IFN-γ enhances the therapeutic efficacy of MSCs-derived exosome via miR-126-3p in diabetic wound healing by targeting SPRED1

BACKGROUND AND AIMS

The traditional treatment of diabetic wounds is unsatisfactory. Exosomes isolated from bone marrow mesenchymal stem cells (BMSCs) promote the healing of diabetic wounds. However, whether the exosomes secreted by interferon (IFN)-γ-pretreated BMSCs have an enhanced therapeutic effect on diabetic wound healing and the relevant mechanisms remain unclear.

METHODS

In this study, we isolated exosomes from the corresponding supernatants of BMSCs with (IExos) or without IFN-γ treatment (NExos). Human umbilical vein endothelial cells (HUVECs) were used to investigate the proliferation, migration, and tube formation under different treatments in vitro. Diabetic mice were induced by intraperitoneal administration of streptozotocin, and a circular full-thickness dermal defect was then made on the back of each mouse, followed by a multisite subcutaneous injection of phosphate buffered saline or exosomes. Hematoxylin-eosin (H&E) staining, Masson's trichrome staining, and histological analysis were performed to assess the speed and quality of wound healing.

RESULTS

NExos treatment accelerated the healing of diabetic wounds by promoting angiogenesis in vivo and in vitro, and IExos exhibited superior therapeutic efficiency. MicroRNA (miR)-126-3p was significantly increased in IExos, and exosomal miR-126-3p promoted angiogenesis and diabetic wound healing via its transfer to HUVECs. miR-126-3p regulates SPRED1 by directly targeting the 3'-UTR. Mechanistically, IFN-γ-pretreated BMSCs secreted miR-126-3p-enriched exosomes, which enhanced the function of HUVECs and promoted angiogenesis via the SPRED1/Ras/Erk pathway.

CONCLUSION

Exosomal miR-126-3p secreted from IFN-γ-pretreated BMSCs exhibited higher therapeutic efficacy than NExos in diabetic wound healing by promoting angiogenesis via the SPRED1/Ras/Erk axis.

Long noncoding RNA LOC646029 functions as a ceRNA to suppress ovarian cancer progression through the miR-627-3p/SPRED1 axis

Long noncoding RNAs (lncRNAs) play a crucial regulatory role in the development and progression of multiple cancers. However, the potential mechanism by which lncRNAs affect the recurrence and metastasis of ovarian cancer remains unclear. In the current study, the lncRNA LOC646029 was markedly downregulated in metastatic ovarian tumors compared with primary tumors. Gain- and loss-of-function assays demonstrated that LOC646029 inhibits the proliferation, invasiveness, and metastasis of ovarian cancer cells in vivo and in vitro. Moreover, the downregulation of LOC646029 in metastatic ovarian tumors was strongly correlated with poor prognosis. Mechanistically, LOC646029 served as a miR-627-3p sponge to promote the expression of Sprouty-related EVH1 domain-containing protein 1, which is necessary for suppressing tumor metastasis and inhibiting KRAS signaling. Collectively, our results demonstrated that LOC646029 is involved in the progression and metastasis of ovarian cancer, which may be a potential prognostic biomarker.

Circ_TEX2 Functions as a Tumor Suppressor in Hepatoma via miR-96-5p/SPRED1 Axis

Circular RNAs (circRNAs) have been shown to have a vital effect on hepatoma progression. The purpose of this study was to explore the function and mechanism of circRNA testis expressed 2 (circ_TEX2, circ_0004913) in hepatoma pathogenesis. Real-time quantitative polymerase chain reaction (RT-qPCR) was used to detect circ_TEX2, miR-96-5p, and sprouty-related EVH1 domain containing 1 (SPRED1) expression. Western blot analyzed the proliferating cell nuclear antigen (PCNA), SPRED1, and the apoptosis-related protein levels. 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT), 5-ethynyl-2'-deoxyuridine (EdU), and colony formation assays were used to test cell proliferation. Cell migration and invasion were analyzed by transwell assay, and cell apoptosis was detected by flow cytometry. Dual-luciferase reporter assay was done to analyze the target relationship between miR-96-5p and circ_TEX2 or SPRED1. The effects of circ_TEX2 on tumor growth in vivo were verified by xenograft model experiment and immunohistochemistry assay. The levels of circ_TEX2 and SPRED1 were down-regulated in hepatoma tissues and cells, and miR-96-5p expression was up-regulated. Overexpression of circ_TEX2 could inhibit the proliferation, migration, and invasion and boost cell apoptosis of hepatoma cells. Circ_TEX2 affected SPRED1 expression by sponging miR-96-5p. The overexpression of miR-96-5p could overturn the influence of circ_TEX2 up-regulation on malignant behaviors of hepatoma cells, and reduced SPRED1 expression could reverse the function of miR-96-5p knockdown on hepatoma cell malignant behaviors. Circ_TEX2 could suppress the growth of xenograft tumors in vivo. Our study demonstrates the tumor-suppressive role of circ_TEX2 in hepatoma through miR-96-5p/SPRED1 axis, suggesting that strategies directed toward restoring the production of circ_TEX2 might have a therapeutic value for hepatoma treatment.

SPOCK2 and SPRED1 function downstream of EZH2 to impede the malignant progression of lung adenocarcinoma in vitro and in vivo

Enhancer of zeste homolog 2 (EZH2) is an important epigenetic regulator, and is associated with the malignant progression of lung cancer. However, the mechanisms of EZH2 on lung adenocarcinoma (LUAD) remain unclear. The relationship between EZH2 and SPOCK2 or SPRED1 was confirmed by dual-luciferase reporter assay. The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases were analyzed to examine the expression of SPOCK2 and SPRED1 and their prognostic values of LUAD. The effects of SPOCK2 and SPRED1 on the biological characters of LUAD cells were identified on functional assays in vitro and in vivo. Our results showed that EZH2 suppressed the expression and transcriptional activity of SPOCK2 and SPRED1, and these effects were reversed by the EZH2 inhibitor, Tazemetostat. SPOCK2 and SPRED1 were expressed at low levels in LUAD patients, and a high expression level of SPOCK2 or SPRED1 predicted better survival. Moreover, overexpression of SPOCK2 or SPRED1 could inhibit tumoral proliferation, migration ratio, and invasion activity in vitro as well as retard tumor growth in vivo. However, EZH2 elevation could rescue these impacts and accelerate LUAD progression. Our findings reveal that SPOCK2 and SPRED1 are epigenetically suppressed by EZH2 and may act as novel regulators to inhibit the proliferation, migration, and invasion of LUAD cells.

Mechanistic Insights into the Long-range Allosteric Regulation of KRAS Via Neurofibromatosis Type 1 (NF1) Scaffold Upon SPRED1 Loading

Allosteric regulation is the most direct and efficient way of regulating protein function, wherein proteins transmit the perturbations at one site to another distinct functional site. Deciphering the mechanism of allosteric regulation is of vital importance for the comprehension of both physiological and pathological events in vivo as well as the rational allosteric drug design. However, it remains challenging to elucidate dominant allosteric signal transduction pathways, especially for large and multi-component protein machineries where long-range allosteric regulation exits. One of the quintessential examples having long-range allosteric regulation is the ternary complex, SPRED1-RAS-neurofibromin type 1 (NF1, a RAS GTPase-activating protein), in which SPRED1 facilitates RAS-GTP hydrolysis by interacting with NF1 at a distal, allosteric site from the RAS binding site. To address the underlying mechanism, we performed extensive Gaussian accelerated molecular dynamics simulations and Markov state model analysis of KRAS-NF1 complex in the presence and absence of SPRED1. Our findings suggested that SPRED1 loading allosterically enhanced KRAS-NF1 binding, but hindered conformational transformation of the NF1 catalytic center for RAS hydrolysis. Moreover, we unveiled the possible allosteric pathways upon SPRED1 binding through difference contact network analysis. This study not only provided an in-depth mechanistic insight into the allosteric regulation of KRAS by SPRED1, but also shed light on the investigation of long-range allosteric regulation among complex macromolecular systems.

Methylation of SPRED1: A New Target in Acute Myeloid Leukemia

Sprouty-related, EVH1 domain-containing protein 1 (SPRED1) has been identified as a novel tumor suppressor gene in acute myeloid leukemia (AML). Previous studies showed that SPRED1 methylation levels were significantly increased in AML patients, making it an interesting candidate for further investigations. To confirm the association of SPRED1 methylation, clinical parameters, and known molecular prognosticators and to identify the impact of methylation level on treatment outcome, we conducted this study in a larger cohort of 75 AML patients. Significantly increased methylation levels of SPRED1 were detected at four of ten CpG units by quantitative high-resolution mass spectrometry-based approach (MassARRAY) in AML patients. Whereas overall survival (OS) and relapse-free survival (RFS) showed no statistical difference between hypermethylation and hypomethylation subgroups, the relationship between methylation level and treatment response was indicated in paired samples from pre- and post-induction. To determine the possible mechanism of SPRED1 methylation in AML, we performed in vitro experiments using THP-1 cells, as the latter showed the highest methylation level (determined by utilizing bisulfite modification) among the three AML cell lines we tested. When treated with 5-AZA and lentivirus transfection, upregulated SPRED1 expression, decreased cell proliferation, increased cell differentiation and apoptosis, and inactivated phosphorylated extracellular signal-regulated kinase (p-ERK) were detected in THP-1 cells. These results show that demethylation of SPRED1 can inhibit the proliferation of AML cells and promote their differentiation and apoptosis, possibly by the ERK pathway. The hypermethylation of SPRED1 is a potential therapeutic target for AML.

Up-regulated miR-204-5p promoted the migration, invasion, and angiogenesis of endothelial progenitor cells to enhance the thrombolysis of rats with deep venous thrombosis by targeting SPRED1

Deep venous thrombosis (DVT) endangers human health. Endothelial progenitor cells (EPCs) were proven to promote thrombolysis and miR-204-5p was discovered to be low-expressed in DVT patients. This study concentrated on exploring whether miR-204-5p had a regulatory effect on EPCs and DVT. Concretely, the expression of miR-204-5p in DVT patients' blood was detected by qRT-PCR. The target of miR-204-5p was predicted by bioinformatics and verified by dual-luciferase reporter assay. After rat EPCs were isolated, identified, and transfected with miR-204-5p agomiR, antagomiR, or SPRED1 plasmids, the viability, migration, invasion, and tube formation of EPCs were detected by MTT, wound healing, Transwell, and tube formation assays, respectively. MiR-204-5p, SPRED1, p-PI3K, PI3K, p-AKT, AKT, VEGFA, and Ang1 expressions in EPCs were measured by qRT-PCR or Western blot. EPCs transfected with miR-204-5p overexpression lentivirus plasmid were injected into the DVT rat model. The histopathology of the thrombus and the homing of EPCs to thrombus in the DVT rats were observed by hematoxylin-eosin staining and confocal microscopy, respectively. We found that miR-204-5p was low-expressed in DVT patients and SPRED1 was a target gene of miR-204-5p. MiR-204-5p agomiR promoted the viability, migration, invasion, and tube formation of EPCs, the levels of VEGFA and Ang1 and the activation of PI3K/AKT pathway in EPCs, while miR-204-5p antagomiR and SPRED1 worked oppositely. SPRED1 reversed the effect of miR-204-5p agomiR on EPCs. Up-regulated miR-204-5p inhibited thrombosis and promoted EPCs homing to thrombus in DVT rats. Collectively, up-regulated miR-204-5p enhanced the angiogenesis of EPCs and thrombolysis in DVT rats by targeting SPRED1.

Updated Approach to Patients with Multiple Café au Lait Macules

Café au lait macules (CALMs) are a normal and frequent finding in the general population, but multiple CALMs raise the possibility of an underlying neurocutaneous disease like neurofibromatosis type I. Certain features of CALMs like number, size, shape, and distribution are important in identifying children at higher risk of having a neurocutaneous disorder or another genetic disorder. Genetic testing can be especially helpful in establishing a diagnosis in atypical presentations, or when the child is young and other features of the disease aside from CALMs have not manifested.

SPRED2 loss-of-function causes a recessive Noonan syndrome-like phenotype

Upregulated signal flow through RAS and the mitogen-associated protein kinase (MAPK) cascade is the unifying mechanistic theme of the RASopathies, a family of disorders affecting development and growth. Pathogenic variants in more than 20 genes have been causally linked to RASopathies, the majority having a dominant role in promoting enhanced signaling. Here, we report that SPRED2 loss of function is causally linked to a recessive phenotype evocative of Noonan syndrome. Homozygosity for three different variants-c.187C>T (p.Arg63^∗), c.299T>C (p.Leu100Pro), and c.1142_1143delTT (p.Leu381Hisfs^∗95)-were identified in four subjects from three families. All variants severely affected protein stability, causing accelerated degradation, and variably perturbed SPRED2 functional behavior. When overexpressed in cells, all variants were unable to negatively modulate EGF-promoted RAF1, MEK, and ERK phosphorylation, and time-course experiments in primary fibroblasts (p.Leu100Pro and p.Leu381Hisfs^∗95) documented an increased and prolonged activation of the MAPK cascade in response to EGF stimulation. Morpholino-mediated knockdown of spred2a and spred2b in zebrafish induced defects in convergence and extension cell movements indicating upregulated RAS-MAPK signaling, which were rescued by expressing wild-type SPRED2 but not the SPRED2^{Leu381Hisfs∗95} protein. The clinical phenotype of the four affected individuals included developmental delay, intellectual disability, cardiac defects, short stature, skeletal anomalies, and a typical facial gestalt as major features, without the occurrence of the distinctive skin signs characterizing Legius syndrome. These features, in part, characterize the phenotype of Spred2^-/- mice. Our findings identify the second recessive form of Noonan syndrome and document pleiotropic consequences of SPRED2 loss of function in development.

Lisch nodules and iris mammillations in two siblings with familial legius syndrome

Legius syndrome is characterized by numerous café‐au‐lait macules and intertriginous freckling, but typically lacks the distinctive tumor manifestations of neurofibromatosis type 1. We report two siblings with Legius syndrome and Lisch nodules illustrating the importance of eye surveillance in these patients.

Role of SPRED1 in keratinocyte proliferation in psoriasis

Psoriasis is a recurrent inflammatory skin disease, affecting approximately 2% of the population. Previous studies have demonstrated that psoriatic dermal mesenchymal stem cells (DMSC) stimulated keratinocyte (KC) proliferation and that psoriasis exhibited missense SPRED1 mutations. To further investigate the molecular mechanism by which psoriatic DMSC stimulate KC proliferation, and the role of missense SPRED1 mutations in psoriasis, we assessed expression levels of miRNA, and both mRNA and protein of SPRED1 in normal human epidermal keratinocyte cells (NHEK) cocultured with either psoriatic or control DMSC. Expression levels of miRNA and mRNA were determined by RNA sequencing. Expression levels of spred1 protein were assessed using western blot analysis. Moreover, the variation in SPRED1 was also examined by whole-genome sequencing in 665 psoriatic patients, and verified by Sanger sequencing. Our results showed that coculture of NHEK with psoriatic DMSC induced 32 differentially expressed miRNA, in which expression levels of miR-1 increased approximately 16-fold over control DMSC-treated NHEK (P < 0.05). Likewise, expression levels of miR-21-3p increased over twofold (P < 0.05). Moreover, coculture of NHEK with psoriatic DMSC induced marked increase in expression levels of mRNA for MAPK3, CDC25B and CDC25C, while decreasing expression levels of SPRED1 mRNA and protein in comparison with control DMSC treatment (P < 0.05 for all between cocultured with control and psoriatic DMSC). Furthermore, psoriasis displayed non-synonymous mutation of SPRED1 enriched in exon 7: c.A881T:p.Y294F (chr15:38351210). These results suggest that dysregulation and mutations of SPRED1 may participate in the pathogenesis of psoriasis, including epidermal hyperproliferation.

SPRED1 Is Downregulated and a Prognostic Biomarker in Adult Acute Myeloid Leukemia

We report herein that Sprouty-Related EVH1 Domain-Containing Protein1 (SPRED1) is downregulated and a prognostic biomarker in adult acute myeloid leukemia (AML). We determined mRNA levels of SPRED1 in the bone marrow mononuclear cells from adult patients, including 113 AMLs and 22 acute lymphoblastic leukemias (ALLs), as well as in 37 healthy control subjects. Significantly decreased SPRED1 mRNA expression was found in AML patients comparing to those in ALL patients and healthy controls, which was confirmed by immunocytochemistry analysis of SPRED1 protein and ELISA measurement of serum SPRED1 level. Further analysis demonstrated that SPRED1 expression was significantly higher for most patients at complete remission after induction treatment than at diagnosis. Moreover, SPRED1 expression was significantly downregulated in M2 and M3 types. Non-acute promyelocytic leukemia (non-APL) patients with decreased SPRED1 had significantly lower 2-year progression-free survival and event-free survival rates. In vitro, ectopic overexpression of SPRED1 leads to a decrease of extracellular signal-regulated kinase (ERK) phosphorylation, induction of apoptosis and reduction of proliferation of THP-1 cells. Our findings suggest SPRED1 is not only a predictor of treatment response, but also an independent prognostic factor for non-APL, and targeting Ras- Mitogen-activated protein kinase (MAPK) signaling may be a promising strategy for the treatment of AML with downregulation of SPRED1.

Expanding the Noonan spectrum/RASopathy NGS panel: Benefits of adding NF1 and SPRED1

Background

RASopathies are a group of disorders caused by disruptions to the RAS‒MAPK pathway. Despite being in the same pathway, Neurofibromatosis Type 1 (NF1) and Legius syndrome (LS) typically present with phenotypes distinct from Noonan spectrum disorders (NSDs). However, some NF1/LS individuals also exhibit NSD phenotypes, often referred to as Neurofibromatosis‐Noonan syndrome (NFNS), and may be mistakenly evaluated for NSDs, delaying diagnosis, and affecting patient management.

Methods

A derivation cohort of 28 patients with a prior negative NSD panel and either NFNS or a suspicion of NSD and café‐au‐lait spots underwent NF1 and SPRED1 sequencing. To further determine the utility and burden of adding these genes, a validation cohort of 505 patients with a suspected RASopathy were tested on a 14‐gene RASopathy‐associated panel.

Results

In the derivation cohort, six (21%) patients had disease‐causing NF1 or SPRED1 variants. In the validation cohort, 11 (2%) patients had disease‐causing variants and 15 (3%) had variants of uncertain significance in NF1 or SPRED1. Of those with disease‐causing variants, 5/17 only had an NSD diagnosis.

Conclusions

Adding NF1 and SPRED1 to RASopathy panels can speed diagnosis and improve patient management, without significantly increasing the burden of inconclusive results.

Hypoxic mesenchymal stem cell-derived exosomes promote bone fracture healing by the transfer of miR-126

Increasing evidence has suggested that paracrine mechanisms might be involved in the underlying mechanism of mesenchymal stem cells (MSCs) transplantation, and exosomes are an important component of this paracrine role. However, MSCs are usually exposed to normoxia (21% O₂) in vitro but experience large differences in oxygen concentration in the body under hypoxia. Indeed, hypoxic precondition of MSCs can enhance their paracrine effects. The main purpose of this study was to determine whether exosomes derived from MSCs under hypoxia (Hypo-Exos) exhibit greater effects on bone fracture healing than those under normoxia (Exos). Using in vivo bone fracture model and in vitro experiments including cell proliferation assay, cell migration assay and so on, we confirmed that Hypo-Exos administration promoted angiogenesis, proliferation and migration to a greater extent when compared to Exos. Furthermore, utilizing a series in vitro and in vivo gain and loss of function experiments, we confirmed a functional role for exosomal miR-126 in the process of bone fracture healing. Meanwhile, we found that knockdown of hypoxia inducible factor 1 (HIF-1α) resulted in a significant decrease of miR-126 in MSCs and exosomes, thereby abolishing the effects of Hypo-Exos. In conclusion, our results demonstrated a mechanism by which Hypo-Exos promote bone fracture healing through exosomal miR-126. Moreover, hypoxia preconditioning mediated enhanced production of exosomal miR-126 through the activation of HIF-1α. Hypoxia preconditioning represents an effective and promising method for the optimization of the therapeutic actions of MSC-derived exosomes for bone fracture healing. STATEMENT OF SIGNIFICANCE: Studies have confirmed that transplantation of exosomes exhibit similar therapeutic effects and functional properties to directly-transplanted stem cells but have less significant adverse effects. However, during in vitro culture conditions, MSCs are usually exposed to normoxia (21% O₂) which is very different to the oxygen concentrations found in the body under natural physiological conditions. Our results demonstrated a mechanism by which Hypo-Exos promote bone fracture healing through exosomal miR-126 and the SPRED1/Ras/Erk signaling pathway. Moreover, hypoxia preconditioning mediated enhanced production of exosomal miR-126 through the activation of HIF-1α. Hypoxia preconditioning represents an effective and promising method for the optimization of the therapeutic actions of MSC-derived exosomes for bone fracture healing.

One NF1 Mutation may Conceal Another

Neurofibromatosis type 1 (NF1) is an autosomal dominant disease with complete penetrance but high variable expressivity. NF1 is caused by loss-of-function mutations in the NF1 gene, a negative regulator of the RAS-MAPK pathway. The NF1 gene has one of the highest mutation rates in human disorders, which may explain the outbreak of independent de novo variants in the same family. Here, we report the co-occurrence of pathogenic variants in the NF1 and SPRED1 genes in six families with NF1 and Legius syndrome, using next-generation sequencing. In five of these families, we observed the co-occurrence of two independent NF1 variants. All NF1 variants were classified as pathogenic, according to the American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG-AMP) guidelines. In the sixth family, one sibling inherited a complete deletion of the NF1 gene from her mother and carried a variant of unknown significance in the SPRED1 gene. This variant was also present in her brother, who was diagnosed with Legius syndrome, a differential diagnosis of NF1. This work illustrates the complexity of molecular diagnosis in a not-so-rare genetic disease.

A Pilot Study of Aberrant CpG Island Hypermethylation of SPRED1 in Acute Myeloloid Leukemia

Background: Epigenetic silencing of tumor suppressor genes plays important role in acute myeloid leukemia (AML). Recently, SPRED1, a negative regulator of the RAS MAPK pathway, is identified as a tumour suppressor downregulated in AML. However, little is known regarding its underlying dysregulation in AML. In this study, we investigated methylation status of SPRED1 promoters and their association with mRNA levels in AML. Methods: Methylation level were measured in four regions of SPRED1 (#1: 310 bp ~ 723 bp, #2: 810 bp ~ 1299 bp, #3: 1280 bp ~ 1742 bp and #4: 1715 bp ~ 2059 bp) in a total of 16 patients with de novonon-acute promyelocytic leukemia (non-APL) and three patients who got complete remission after induction treatment using the Sequenom MassARRAY platform. Quantitative real-time polymerase chain reaction (q-RT PCR) was used to analyze SPRED1 mRNA levels. Results: AML patients had a significantly higher average methylation level than controls at regions of #1_CpG_1 (p= 0.04) and #1_CpG_11 (p =0.002). The methylation values for #1_CpG_11 were negatively correlated with mRNA levels (r= -0.558, p=0.013) but there was no significant association between #1_CpG_1 methylation status and mRNA levels (r=-0.103, p=0.675) in AML patients. There was no significant difference in the methylation level when comparing with clinical biochemical parameters and treatment response (p>0.05). Mutations of epigenetic regulation genes such as DNMT3A, TET2 and IDH1/2 were most frequently observed in patients with higher methylation levels. Decreased methylation levels were revealed in three patients who got complete remission. Conclusions: Aberrant methylation statuses of the SPRED1 promoter regions are associated with the downregulation of gene transcription in AML. The methylation level is probably associated with the treatment response of AML. Mutations of epigenetic regulation genes might be involved in the epigenetic aberration of SPRED1.

Estrogen-induced miR-196a elevation promotes tumor growth and metastasis via targeting SPRED1 in breast cancer

BACKGROUND

Estrogen plays a critical role in breast cancer (BC) progression through estrogen receptor (ER)-mediated gene regulation. Emerging studies suggest that the malignant progress of BC cells is influenced by the cross talk between microRNAs (miRNAs) and ER-α signaling. However, the mechanism and functional linkage between estrogen and miRNAs remain unclear.

METHODS

The expression levels of miR-196a and SPRED1 in BC were tested by qRT-PCR in 46 paired BC and adjacent tissues and by the GEO datasets. The role of miR-196a in estrogen-induced BC development was examined by CCK-8 assay, wound healing assay, Matrigel invasion assay and tumorigenicity assay in nude mice. The binding site of ER-α in miR-196a promoter region was analyzed by ChIP-seq, ChIP assay and luciferase reporter assay. The potential targets of miR-196a in BC cells were explored using the luciferase reporter assay and western blot analysis, and the correlation between miR-196a and SPRED1 was analyzed by Spearman's correlation analysis in BC specimens and GEO dataset. TCGA BRCA data was used to characterize the ESR1 signatures according to MSigDB gene set.

RESULTS

The expression levels of miR-196a were higher in ER-positive (ER+) breast tumors compared to ER-negative (ER-) tumor tissue samples. Besides, miR-196a was involved in estrogen-induced BC cell proliferation, migration and invasion. Notably, the up-regulation of miR-196a was mediated by a direct interaction with estrogen receptor α (ER-α) but not estrogen receptor β (ER-β) in its promoter region, and miR-196a expression levels were positively correlated to ER-α signature scores. Furthermore, SPRED1 was a new direct target of miR-196a which participated in miR-196a-promoted BC development and was suppressed by ligand-activated ER-α signal pathway. Finally, forced expression of miR-196a induced tumor growth of MCF7 cells, while inhibition of miR-196a significantly suppressed the tumor progress in vivo.

CONCLUSIONS

Overall, the identification of estrogen/miR-196a/SPRED1 cascade will shed light on new molecular mechanism of estrogen signaling in BC development and therapy.

miR182 activates the Ras-MEK-ERK pathway in human oral cavity squamous cell carcinoma by suppressing RASA1 and SPRED1

Purpose

The constitutive activation of the Ras–MEK–ERK signaling pathway in oral cavity squamous cell carcinoma (OSCC) has been found to be tightly controlled at multiple levels under physiological conditions. RASA1 and SPRED1 are two important negative regulators of this pathway, but the exact regulating mechanism remains unclear. In this study, we aimed to explore the potential regulating mechanisms involved in the Ras–MEK–ERK signaling pathway in OSCC.

Materials and methods

MicroRNA (miRNA) expression was detected by quantitative reverse-transcription polymerase chain reaction. The protein levels of RASA1, SPRED1, and signaling proteins were detected by Western blot. Cell growth was determined using CCK-8 reagent, colony formation was stained by crystal violet, and cell invasion was tested using transwell chambers. Cell apoptosis and the cell cycle were then analyzed by flow cytometry. The binding of miR182 with RASA1 or SPRED1 was evaluated by luciferase reporter assays on a dual-luciferase reporter system.

Results

The expression of miR182 was found to be upregulated significantly in malignant oral carcinoma tissues compared with the adjacent nonmalignant tissues, and was inversely correlated with protein levels of RASA1 and SPRED1. Overexpression of miR182 in OSCC cell lines sustained Ras–MEK–ERK signaling-pathway activation, and promoted cell proliferation, cell-cycle progression, colony formation, and invasion capacity, whereas miR182 downregulation alleviated these properties significantly in vitro. Furthermore, we demonstrated that miR182 exerted its oncogenic role in OSCC by directly targeting and suppressing RASA1 and SPRED1.

Conclusion

Our results bring new insights into the important role of miR182 in the activation of the Ras–MEK–ERK signaling pathway, and suggest that miR182 may be used as a potential target for treatment of OSCC, prompting further investigation into miRNA antisense oligonucleotides for cancer therapy.

Legius syndrome: A case report

Legius syndrome is a rare genetic disorder caused by heterozygous germ line loss-of-function SPRED1 mutation. In Japan, a family with Legius syndrome was first described in 2015 by Sakai et al. We described a first solitary case of Legius syndrome identified by next-generation sequencing in Japan. A 37-year-old woman presented with multiple café-au-lait macules and freckles but has no other features of neurofibromatosis type 1 (NF-1). Sequencing results showed the presence of a mutation in exon 2 of SPRED1 c.70C>T, resulting in the protein at position 24 (p.Arg24X). When a dermatological clinician sees an adult patient showing only pigmented lesions and no other specifically diagnostic features of NF-1, it is important to suspect the possibility of Legius syndrome.

Comprehensive RNA Analysis of the NF1 Gene in Classically Affected NF1 Affected Individuals Meeting NIH Criteria has High Sensitivity and Mutation Negative Testing is Reassuring in Isolated Cases With Pigmentary Features Only

Background

The detection rate for identifying the underlying mutation in neurocutaneous syndromes is affected by the sensitivity of the mutation test and the heterogeneity of the disease based on the diagnostic criteria. Neurofibromatosis type (NF1) has been defined for 29 years by the National Institutes for Health (NIH) criteria which include ≥ 6 Café au Lait macules (CAL) as a defining criterion. The discovery of SPRED1 as a cause of Legius syndrome which is manifested by CAL, freckling and learning difficulties has introduced substantial heterogeneity to the NIH criteria.

Methods

We have defined the sensitivity of comprehensive RNA analysis on blood of presumed NF1 patients meeting NIH criteria with at least one nonpigmentary criterion and determined the proportion of children with ≥ 6 CAL and no family history that has an NF1 or SPRED1 genetic variant. RNA analysis was carried out from 04/2009–12/2015 on 361 NF1 patients.

Findings

A presumed causative NF1 mutation was found in 166/171 (97.08%–95% CI 94.56–99.6%) of familial cases and 182/190 (95.8%–95% CI 92.93–98.65%) sporadic de novo cases. Two of thirteen (15%) mutation negative individuals had dysembryoplastic neuroepithelial tumour (DNET) compared to 2/348 (0.6%) with an NF1 variant (p = 0.007). No SPRED1 variants were found in the thirteen individuals with no NF1 variant. Of seventy-one individuals with ≥ 6 CAL and no non-pigmentary criterion aged 0–20 years, 47 (66.2%) had an NF1 variant six (8.5%) a SPRED1 variant and 18 (25.3%) no disease causing variant. Using the 95.8% detection rate the likelihood of a child with ≥ 6 CAL having constitutional NF1 drops from 2/3 to 1/9 after negative RNA analysis.

Interpretation

RNA analysis in individuals with presumed NF1 has high sensitivity and includes a small subset with DNET without an NF1 variant. Furthermore negative analysis for NF1/SPRED1 provides strong reassurance to children with ≥ 6 CAL that they are unlikely to have NF1.

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RNA testing for NF1 mutations has very high sensitivity (c.96%) and is significantly more sensitive than DNA testing.

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Mosaicism is not a major feature in those with classical NF1.

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Around two thirds of children with just 6 or more café au lait spots have NF1, 8% Legius syndrome.

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Patients with normal RNA testing who meet NF1 criteria but also have a DNET may have a fault in a yet to be identified gene.

Identifying the underlying genetic mutation is of benefit to patients and their families as it clarifies the diagnosis, can give information on the likely disease course and allow predictive testing in pregnancy and early childhood. The present study has shown that testing of blood RNA has very high sensitivity (96%) and allows substantial reassurance to parents whose children have multiple Café au lait birthmarks that they are unlikely to have the poorer outcomes of NF1 if they test negative. Furthermore the study suggests that a different mechanism may underlie the association of NF1 features and a rare benign brain tumour called DNET.

Genome-wide association study of HLA-DQB1*06:02 negative essential hypersomnia

Essential hypersomnia (EHS), a sleep disorder characterized by excessive daytime sleepiness, can be divided into two broad classes based on the presence or absence of the HLA-DQB1*06:02 allele. HLA-DQB1*06:02-positive EHS and narcolepsy with cataplexy are associated with the same susceptibility genes. In contrast, there are fewer studies of HLA-DQB1*06:02 negative EHS which, we hypothesized, involves a different pathophysiological pathway than does narcolepsy with cataplexy. In order to identify susceptibility genes associated with HLA-DQB1*06:02 negative EHS, we conducted a genome-wide association study (GWAS) of 125 unrelated Japanese EHS patients lacking the HLA-DQB1*06:02 allele and 562 Japanese healthy controls. A comparative study was also performed on 268 HLA-DQB1*06:02 negative Caucasian hypersomnia patients and 1761 HLA-DQB1*06:02 negative Caucasian healthy controls. We identified three SNPs that each represented a unique locus— rs16826005 (P = 1.02E-07; NCKAP5), rs11854769 (P = 6.69E-07; SPRED1), and rs10988217 (P = 3.43E-06; CRAT) that were associated with an increased risk of EHS in this Japanese population. Interestingly, rs10988217 showed a similar tendency in its association with both HLA-DQB1*06:02 negative EHS and narcolepsy with cataplexy in both Japanese and Caucasian populations. This is the first GWAS of HLA-DQB1*06:02 negative EHS, and the identification of these three new susceptibility loci should provide additional insights to the pathophysiological pathway of this condition.

The SPRED1 Variants Repository for Legius Syndrome

Legius syndrome (LS) is an autosomal dominant disorder caused by germline loss-of-function mutations in the sprouty-related, EVH1 domain containing 1 (SPRED1) gene. The phenotype of LS is multiple café au lait macules (CALM) with other commonly reported manifestations, including intertriginous freckling, lipomas, macrocephaly, and learning disabilities including ADHD and developmental delays. Since the earliest signs of LS and neurofibromatosis type 1 (NF1) syndrome are pigmentary findings, the two are indistinguishable and individuals with LS may meet the National Institutes of Health diagnostic criteria for NF1 syndrome. However, individuals are not known to have an increased risk for developing tumors (compared with NF1 patients). It is therefore important to fully characterize the phenotype differences between NF1 and LS because the prognoses of these two disorders differ greatly. We have developed a mutation database that characterizes the known variants in the SPRED1 gene in an effort to facilitate this process for testing and interpreting results. This database is free to the public and will be updated quarterly.