ABSTRACT
RNA splicing is a dynamic molecular process in response to environmental stimuli and is strictly regulated by the spliceosome. Sm proteins, constituents of the spliceosome, are key components that mediate splicing reactions; however, their potential role in hepatocellular carcinoma (HCC) is poorly understood. In the study, SNRPD2 (PD2) is found to be the most highly upregulated Sm protein in HCC and to act as an oncogene. PD2 modulates DDX39A intron retention together with HNRNPL to sustain the DDX39A short variant (39A_S) expression. Mechanistically, 39A_S can mediate MYC mRNA nuclear export to maintain high MYC protein expression, while MYC in turn potentiates PD2 transcription. Importantly, digitoxin can directly interact with PD2 and has a notable cancer-suppressive effect on HCC. The study reveals a novel mechanism by which DDX39A senses oncogenic MYC signaling and undergoes splicing via PD2 to form a positive feedback loop in HCC, which can be targeted by digitoxin.
ABSTRACT
Transforming growth factor-ß (TGF-ß) is considered to be one of the main factors responsible for glioblastoma tumorigenesis. MicroRNAs have recently been shown to regulate cell proliferation, differentiation, and apoptosis. However, the involvement of miRNA-146a in TGF-ß1-induced glioblastoma development remains largely unknown. Here, miRNA-164a transfection was used to overexpress miRNA-164a in U87, and then real-time quantitative PCR and Western blot were applied to detect the gene transcription and protein expression. In addition, MTT and wound healing assay were also used to observe cell proliferation and migration. Our data revealed that miRNA-146a was downregulated by TGF-ß1 treatment, but upregulated by miRNA-164a transfection. MiRNA-146a overexpression significantly reduced SMAD4 protein expression instead of p-SMAD2. Besides, miRNA-146a overexpression also decreased the messenger RNA (mRNA) and protein expression of epidermal growth factor receptor (EGFR) and MMP9 as well as the p-ERK1/2 level. Furthermore, the upregulation of miRNA-146a suppressed TGF-ß1-mediated U87 proliferation and migration. These results demonstrate that miRNA-146a acts as a novel regulator to modulate the activity and transduction of TGF-ß signaling pathways in glioblastoma, and the downregulation of miRNA-146a is required for overexpression of EGFR and MMP9, which can be considered an efficiently therapeutic target and a better understanding of glioblastoma pathogenesis.
Subject(s)
Glioblastoma/pathology , MicroRNAs/genetics , RNA, Neoplasm/genetics , Signal Transduction/genetics , Transforming Growth Factor beta/physiology , Cell Division/genetics , Cell Line, Tumor , Cell Movement/genetics , Down-Regulation , ErbB Receptors/biosynthesis , Genes, erbB-1 , Glioblastoma/genetics , Glioblastoma/metabolism , Humans , MAP Kinase Signaling System/genetics , Matrix Metalloproteinase 9/biosynthesis , Matrix Metalloproteinase 9/genetics , MicroRNAs/biosynthesis , Neoplasm Proteins/biosynthesis , Neoplasm Proteins/genetics , RNA, Neoplasm/biosynthesis , Smad Proteins/physiology , TransfectionABSTRACT
Papillary thyroid microcarcinoma (PMC) is the most common subtype of thyroid carcinomas with satisfactory prognosis. Crk-like (CrkL) adaptor protein was identified in the development of many carcinomas. However, the clinical implications of CrkL protein in PMC were still unknown. Here, we conducted immunohistochemistry to test and analyze CrkL expression in papillary thyroid carcinoma (PTC) (50 cases), PMC (50 cases), and nodular goiter (50 cases), and then western blot further identified the expression of CrkL proteins. In our present study, the positive rate and the mean optical density (MOD) value of CrkL expression in PTC and PMC tissues were statistically significantly different, compared with nodular goiter (p = 0.021, 0.037) and normal thyroid tissues (p = 0.003, 0.009), respectively. In addition, CrkL expression was not associated with age, gender, and tumor number. Conversely, significant differences between CrkL expression and metastasis (p < 0.01) and violation of capsule (p < 0.01) were observed. Notably, western blot indeed identified that the metastasis group of either PTC or PMC tissues had about twofold increased expression of CrkL compared with their non-metastasis groups (p < 0.05). In conclusion, CrkL is highly expressed in papillary thyroid carcinoma and papillary thyroid microcarcinoma and closely correlated to metastasis. Therefore, it is essential to carry out neck lymph node clearance in patients with papillary thyroid microcarcinoma.
