LncRNA SNHG17 interacts with LRPPRC to stabilize c-Myc protein and promote G1/S transition and cell proliferation

Oncogenic c-Myc is a master regulator of G1/S transition. Long non-coding RNAs (lncRNAs) emerge as new regulators of various cell activities. Here, we found that lncRNA SnoRNA Host Gene 17 (SNHG17) was elevated at the early G1-phase of cell cycle. Both gain- and loss-of function studies disclosed that SNHG17 increased c-Myc protein level, accelerated G1/S transition and cell proliferation, and consequently promoted tumor cell growth in vitro and in vivo. Mechanistically, the 1-150-nt of SNHG17 physically interacted with the 1035-1369-aa of leucine rich pentatricopeptide repeat containing (LRPPRC) protein, and disrupting this interaction abrogated the promoting role of SNHG17 in c-Myc expression, G1/S transition, and cell proliferation. The effect of SNHG17 in stimulating cell proliferation was attenuated by silencing c-Myc or LRPPRC. Furthermore, silencing SNHG17 or LRPPRC increased the level of ubiquitylated c-Myc and reduced the stability of c-Myc protein. Analysis of human hepatocellular carcinoma (HCC) tissues revealed that SNHG17, LRPPRC, and c-Myc were significantly upregulated in HCC, and they showed a positive correlation with each other. High level of SNHG17 or LRPPRC was associated with worse survival of HCC patients. These data suggest that SNHG17 may inhibit c-Myc ubiquitination and thus enhance c-Myc level and facilitate proliferation by interacting with LRPPRC. Our findings identify a novel SNHG17-LRPPRC-c-Myc regulatory axis and elucidate its roles in G1/S transition and tumor growth, which may provide potential targets for cancer therapy.Subject terms: Oncogenes, Cell growth, Long non-coding RNAs     

LncRNA OGFRP1 promotes cell proliferation and suppresses cell radiosensitivity in gastric cancer by targeting the miR-149-5p/MAP3K3 axis

Journal of Molecular Histology - Gastric cancer (GC) is an aggressive malignancy with high incidence and mortality. Radiotherapy is a common treatment for patients with advanced GC. Many long...     

LncRNA KCNQ1OT1 acts as miR-216b-5p sponge to promote colorectal cancer progression via up-regulating ZNF146

Journal of Molecular Histology - Long non-coding RNAs (lncRNAs) have shown to act as important regulators in cancer biology. The aim of this study was to investigate the role and mechanism of...     

Tumor-derived extracellular vesicles shuttle c-Myc to promote gastric cancer growth and metastasis via the KCNQ1OT1/miR-556-3p/CLIC1 axis

Gastric cancer (GC) is a heterogeneous disease with poor prognosis. Tumor-derived extracellular vesicles (EVs) assume a role in intercellular communication by carrying various molecules, including proteins, RNA, and DNAs, which has been identified to exhibit oncogenic effect in GC. Therefore, this research aimed to figure out whether tumor-derived EVs transmit c-Myc to orchestrate the growth and metastasis of GC. KCNQ1OT1, microRNA (miR)-556-3p and CLIC1 expression of GC tissues was detected through RT-qPCR. EVs were isolated from GC cells, followed by RT-qPCR and Western blot analysis of c-Myc expression in EVs and GC cells. Next, GC cells were incubated with EVs or transfected with a series of mimic, inhibitor, or siRNAs to assess their effects on cell viability, migrative, invasive, and apoptotic potential. Relationship among c-Myc, KCNQ1OT1, miR-556-3p, and CLIC1 was evaluated by dual-luciferase reporter assay. PI3K/AKT pathway-related proteins were assessed through Western blot analysis. KCNQ1OT1 and CLIC1 were highly expressed but miR-556-3p in GC tissues. c-Myc was high-expressed in tumor-derived EVs and GC cells. Mechanistically, c-Myc could induce KCNQ1OT1 expression, and KCNQ1OT1 bound to miR-556-3p that negatively targeted CLIC1 to inactivate PI3K/AKT pathway. Tumor-derived EVs, EVs-c-Myc, KCNQ1OT1 or CLIC1 overexpression, or miR-556-3p inhibition promoted GC cell proliferative, invasive, and migrative capacities but repressed their apoptosis through activating PI3K/AKT pathway. Collectively, tumor-derived EVs carrying c-Myc activated KCNQ1OT1 to downregulate miR-556-3p, thus elevating CLIC1 expression to activate the PI3K/AKT pathway, which facilitated the growth and metastasis of GC.Subject terms: Cancer, Biotechnology     

LncRNA HOXB-AS1 promotes cell growth in multiple myeloma via FUT4 mRNA stability by ELAVL1

Multiple myeloma (MM) is defined as the second most common hematological tumor in the globe. Long noncoding RNAs (lncRNAs) have been reported to play stimulative or suppressive role in the progression of different carcinomas. The investigation of lncRNAs in MM is still inadequate. LncRNA HOXB cluster antisense RNA 1 (HOXB-AS1) was once revealed to facilitate glioma progression by affecting cellular activities of glioma cells. However, whether HOXB-AS1 participates in the development of MM still remains an enigma. In this study, we unveiled that HOXB-AS1 was highly expressed in MM and loss-of-function assays certified that HOXB-AS1 obstruction suppressed MM cell proliferation, and stimulated cell apoptosis. In addition, HOXB-AS1 could modulate fucosyltransferase 4 (FUT4) and FUT4-mediated Wnt/β-catenin pathway. In subsequence, it was observed from mechanism assays that HOXB-AS1 enhanced the interaction between ELAVL1 and FUT4 so as to stabilize FUT4 messenger RNA. In the end, rescue experiments affirmed that HOXB-AS1 affected the cell growth through FUT4 in MM. In conclusion, the whole modulation mechanism of HOXB-AS1/ELAVL1/FUT4 axis in MM was validated in this study, which suggested that HOXB-AS1 might function as a powerful and promising therapeutic biomarker for the clinical treatment of patients with MM.     

IL1RN promotes osteoblastic differentiation via interacting with ITGB3 in osteoporosis

The occurrence and progress of osteoporosis(OP)are partially caused by impaired osteoblast differentiation.Interleukin-I receptor antagonist(IL1RN)is an immune ...     

Yak OXGR1 promotes fibroblast proliferation via the PI3K/AKT pathways

Oxoglutarate receptor 1 (OXGR1), as one of the intermediates in G protein-coupled receptors (GPCRs), plays a crucial role in the citric acid cycle receptor of α-ketoglutarate and metabolism. GPCR can control the cell proliferation by regulating the downstream signaling of G protein signaling pathways. The PI3K/AKT pathway transmits the downstream signals of GPCRs and receptor tyrosine kinases. However, the specific role of OXGR1 promoting cell proliferation and differentiation are still unknown. In current study, the over-expression vector and knockdown sequence of yak OXGR1 were transfected into yak fibroblasts, and the effects were detected by a series of assays. The results revealed that OXGR1 expression in yak lung parenchyma tissue was significantly higher than that of other tissues. In yak fibroblasts, the upregulated expression of OXGR1 resulted in activating the PIK3CG (downstream signal) of the PI3K/AKT1 pathway that can upregulated the expression of proliferation genes ( CDK1, PCNA, and CyclinD1) and promote cell proliferation. Conversely, the downregulated expression of OXGR1 inhibited cell proliferation via PI3K/AKT1 pathway. Cell cycle and cell proliferation assays demonstrated that over-expression of OXGR1 can enhanced the DNA synthesis and promoted yak fibroblasts proliferation. While the conversely, knockdown of OXGR1 can decreased DNA synthesis and inhibited cell proliferation. These results illustrated that changes of OXGR1 expression can trigger the fibroblasts proliferation via PI3K/AKT signaling pathway, which indicating that OXGR1 is a novel regulator for cell proliferation and differentiation. Furthermore, these results provide evidence supporting the functional role of GPCRs-PI3K-AKT1 and OXGR1 in cell proliferation.     

LncRNA KCNQ1OT1 enhanced the methotrexate resistance of colorectal cancer cells by regulating miR‐760/PPP1R1B via the cAMP signalling pathway

We aimed to explore the mechanism of the KCNQ1OT1/miR‐760/PPP1R1B axis acting to regulate methotrexate (MTX) resistance of colorectal cancer (CRC). Differentially expressed mRNAs and lncRNAs in MTX‐sensitive CRC cell lines and MTX‐resistant cell lines were determined through microarray analysis. Application of bioinformatics analysis was aimed to uncover the relationships among the lncRNAs/miRNAs/mRNAs, and to demonstrate the effects of cAMP signalling pathway in MTX‐resistant CRC. The expression level of RNA and proteins was, respectively, detected using qRT‐PCR and Western blot assays, whereas the dual‐luciferase reporter gene assay was implemented to verify the targeted relationship. The influence of the lncRNA/miRNA/mRNA axis on biological functions of MTX‐resistant cells and on the growth of tumours determined through both vitro and vivo experiments. LncRNA KCNQ1OT1 and PPP1R1B mRNA were overexpressed in MTX‐resistant CRC tumour cells. KCNQ1OT1 functioned as a sponge of miR‐760, which targeted PPP1R1B. Knockdown of KCNQ1OT1 enhanced chemosensitivity towards MTX through the sponging of miR‐760. MiR‐760 expressed at low levels targeted PPP1R1B in the activated cAMP signalling pathway under MTX treatment. Knockdown of KCNQ1OT1 dampened the proliferation of MTX‐resistant (HT29/MTX) cells by regulating the miR‐760/PPP1R1B axis, which also induced cell cycle arrest together with apoptosis. KCNQ1OT1 regulated the expression of PPP1R1B and the downstream genes CREB and CBP in the cAMP signalling pathway. MTX showed a suppressive function on CRC progression. KCNQ1OT1 enhanced the MTX resistance of CRC cells by regulating miR‐760‐mediated PPP1R1B expression via the cAMP signalling pathway.     

Fibronectin promotes brain capillary endothelial cell survival and proliferation through alpha5beta1 and alphavbeta3 integrins via MAP kinase signalling

We showed previously that blood vessel maturation in the CNS is associated with a developmental switch in brain capillary endothelial cells (BCEC), from fibronectin signalling during angiogenesis to laminin signalling in the adult. To investigate the functional significance of this switch, we have examined the response of BCEC to different extracellular matrix (ECM) proteins. This showed that BCEC proliferation was significantly promoted by fibronectin (28.2 +/- 4.0%) and by vitronectin (14.8 +/- 2.1%) compared with uncoated glass (7.2 +/- 0.7%), while BCEC survival was significantly promoted by fibronectin (1130 +/- 131 cells), vitronectin (830 +/- 63 cells), collagen IV (703 +/- 77 cells) and laminin (680 +/- 34 cells) compared with the uncoated glass (367 +/- 48 cells). Biochemical studies showed that BCEC express a limited repertoire of integrins, including the beta1 integrins, alpha3beta1, alpha5beta1 and alpha6beta1, and the alphavbeta3 integrin. Function-blocking studies showed that the response to fibronectin was mediated equally by the alpha5beta1 and alphavbeta3 integrins. Analysis of signalling pathways revealed that fibronectin stimulated activation of the p44/p42 MAP kinase signalling pathway and pharmacological inhibitors of this pathway blocked BCEC proliferation on fibronectin. Taken together, these findings show that fibronectin exerts a strong angiogenic influence on endothelial cells (EC) in the CNS, and that this is mediated through the alpha5beta1 and alphavbeta3 integrins via MAP kinase signalling. In addition to a fundamental role in development, these findings may also have implications in pathological conditions of the CNS where fibronectin is re-expressed.