Supplementary MaterialsS1 Fig: The correlation between miR-513a and NEDD4L expression levels in TCGA microarray data. arrays, and RNA sequencing data of TCGA glioma patients. Furthermore, a negative correlation Fenofibrate was recognized between miR-513a-5p and NEDD4L in glioma. NEDD4L was also validated as a direct target gene of miR-513a-5p, and it was reduced by IGF-1 treatment. Overexpression of NEDD4L inhibited glioma cell viability and reversed IGF-1-repressed TMZ cytotoxicity. In contrast, miR-513a-5p significantly affected NEDD4L-inhibited WNT signaling and reduced TMZ cytotoxicity. These findings demonstrate a distinct role of IGF-1 signaling through miR-513a-5p-inhibited NEDD4L networks in influencing GBM’s drug sensitivity to TMZ. Introduction Glioblastoma multiforme (GBM) belongs to grade IV main malignant gliomas with poor prognoses and high lethality in adults [1, 2]. Several tumor microenvironmental factors were identified to enhance the risk of brain tumors, including the insulin-like growth factor (IGF) signaling axis [3]. When the circulating IGF-1 ligand binds to its receptor, IGF-1R, this tyrosine kinase receptor is usually activated through an autophosphorylation mechanism. Subsequently, two major downstream pathways, phosphoinositide 3-kinase (PI3K)/AKT and Ras/extracellular signal-regulated kinase (ERK) pathways, are enhanced to prevent cell death or promote cell growth. In gliomas, IGF-1 modulates cell proliferation and strongly stimulates cell migration [4]. IGF-1 also regulates inflammatory responses in glioma cells via influencing hypoxia-inducible factor (HIF)-1-toll-like receptor 9 (TLR9) cross Fenofibrate talk [5]. Furthermore, increasing evidence suggests that IGF-1 signaling is usually involved in drug EIF2B4 resistance mechanisms, resulting in glioma progression [6]. The IGF-1/IGF-1R axis was recognized to underlie resistance to colony-stimulating factor-1 receptor (CSF-1R) inhibition in gliomas [7]. By increasing Bcl-2 expression and decreasing caspase-3 protease activity, IGF-1 significantly decreased the etoposide-induced apoptosis of glioma cells [8]. Taken together, comprehensively investigating IGF-1-mediated gene networks may be helpful in understanding the progression of gliomagenesis and provide innovative therapeutic strategies for glioblastomas. Micro (mi)RNAs are endogenous, small, non-coding RNAs that inhibit gene expressions by binding to the 3 untranslated region (UTR) of their target messenger (m)RNAs. Aberrant miRNA expressions were recognized in GBM development [9]. For example, miR-10b, a highly expressed onco-miR in all GBM subtypes, was suggested as being a potential target for GBM therapy [10]. Elevation of miR-215 levels by hypoxia is necessary Fenofibrate for reprogramming glioma-initiating cells in GBM occurrence and recurrence [11]. miR-513a-5p, an intergenic miRNA, comes from two different gene loci: miR-513a-1 and miR-513a-2. The functions of miR-513a in tumorigenesis are still unclear, especially in GBM. Only one study reported that upregulated miR-513a-5p levels were observed in GBM patients compared to controls [12]. The functions and molecular mechanisms of miR-513a-5p in glioma progression need to be further analyzed. Neural precursor cell-expressed developmentally downregulated 4-like (NEDD4L, also known as NEDD4-2) is an E3 ubiquitin protein ligase belonging to the NEDD4 family and contains a homologous E6-associated protein C-terminus (HECT) domain name [13]. The best known function of NEDD4L is as an ion channel regulator, including the epithelial sodium channel (ENaC) Fenofibrate [14], Na+-Cl? cotransporter (NCC) [15], voltage-gated sodium channels (Navs) [16], and so on. Recently, a role of NEDD4L in carcinogenesis was recognized. NEDD4L negatively regulates canonical WNT signaling in colorectal malignancy [17]. Decreased NEDD4L levels were correlated with poor prognoses in gastric malignancy patients [18]. Similarly, in gliomas, reduced.