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Abstract Background Hepatic lipogenesis dysregulation is essential for the development of non-alcoholic fatty liver disease (NAFLD). Emerging evidence indicates the importance of the involvement of long non-coding RNAs (LncRNAs) in lipogenesis. However, the specific mechanism underlying this process is not clear. Objective This study aimed to investigate the functional implication of LncRNA MEG3 (MEG3) in fatty degeneration of hepatocytes and in the pathogenesis of NAFLD. Methods The expression of MEG3 was analysed in in vitro and in vivo models of NAFLD, which were established by free fatty acid (FFA)-challenged HepG2 cells and high-fat diet-fed mice, respectively. Endogenous MEG3 was over-expressed by a specific pcDNA3.1-MEG3 to evaluate the regulatory function of MEG3 on triglyceride (TG)- and lipogenesis-related genes. Bioinformatic analysis was used to predict the target genes and binding sites, and the targeted regulatory relationship was verified with a dual luciferase assay. Finally, the possible pathway that regulates MEG3 was also evaluated. Results We found that the downregulation of MEG3 in vitro and in vivo models of NAFLD was negatively correlated with lipogenesis-related genes and that overexpression of MEG3 reversed FFA-induced lipid accumulation in HepG2 cells. miR-21 was upregulated in the FFA-challenged HepG2 cells and was physically associated with MEG3 in the process of lipogenesis. Our mechanistic studies demonstrated that MEG3 competitively binds to miR-21 with LRP6, followed by the inhibition of the mTOR pathway, which induces intracellular lipid accumulation. Conclusion Our data are the first to document the working model of MEG3 functions as a potential hepatocyte lipid degeneration suppressor. MEG3 helps to alleviate lipid over-deposition, probably by binding to miR-21 to regulate the expression of LRP6. Our results suggest the potency of MEG3 as a biomarker for NAFLD and as a therapeutic target for treatment. Highlights • Hepatic lipogenesis dysregulation is essential for the development of Non-alcoholic fatty liver disease • The downregulation of MEG3 in vitro and vivo models of NAFLD was negative correlation with lipogenesis related genes • MEG3 helps to alleviate lipid over-deposition via binding to mir-21 to regulate the expression of LRP6 • The activation of mTOR pathway is the key step of the FFA-induced lipid accumulation [ABSTRACT FROM AUTHOR]

Abstract The Wnt/β-catenin signaling pathway has been etiologically implicated in the development and progression of colorectal cancer. We studied thirteen single nucleotide polymorphisms (SNPs) located in SFRP3 (rs7775), CTNNB1 (β-catenin) [rs4135385, rs13072632], APC (rs454886, rs459552), LRP6 (rs2075241, rs2284396), DKK4 (rs3763511), DKK3 (rs6485350), TCF4 (rs12255372) and AXIN2 (rs3923086, rs3923087, rs4791171) in patients with colorectal cancer (n = 122) and controls (n = 110). Evaluation of WNT pathway SNPs showed protective association for rs4135385, located in β-catenin. Additionally, variants in SFRP3 (rs7775) and LRP6 (rs2284396) which did not show any association in the overall analysis were significantly associated with female and old aged colorectal cancer patients, respectively. [ABSTRACT FROM AUTHOR]

Whether and how garlic-derived S -allylmercaptocysteine (SAMC) inhibits hepatocellular carcinoma (HCC) is largely unknown. In the current study, the role of low-density lipoprotein receptor (LDLR)-related protein 6 (LRP6) in HCC progression and the anti-HCC mechanism of SAMC was examined in clinical sample, cell model and xenograft/orthotopic mouse models. We demonstrated that SAMC inhibited cell proliferation and tumorigenesis, while induced apoptosis of human HCC cells without influencing normal hepatocytes. SAMC directly interacted with Wnt-pathway co-receptor LRP6 on the cell membrane. LRP6 was frequently over-expressed in the tumor tissue of human HCC patients (66.7% of 48 patients) and its over-expression only correlated with the over-expression of β -catenin, but not with age, gender, tumor size, stage and metastasis. Deficiency or over-expression of LRP6 in hepatoma cells could partly mimic or counteract the anti-tumor properties of SAMC, respectively. In vivo administration of SAMC significantly suppressed the growth of Huh-7 xenograft/orthotopic HCC tumor without causing undesirable side effects. In addition, stable down-regulation of LRP6 in Huh-7 facilitated the anti-HCC effects of SAMC. In conclusion, LRP6 can be a potential therapeutic target of HCC. SAMC is a promising specific anti-tumor agent for treating HCC subtypes with Wnt activation at the hepatoma cell surface. [ABSTRACT FROM AUTHOR]

OBJECTIVE: MiR-381-3p plays an essential role in the progression of a variety of cancers, but its expression and role in papillary thyroid carcinoma (PTC) progression have not been investigated. The aim of this study was to investigate the expression of miR-381-3p and its function in PTC. PATIENTS AND METHODS: The expression levels of miR-381-3p and low-density lipoprotein receptor-related protein 6 (LRP6) mRNA in PTC tissues and cell lines were measured using RT-PCR. Cell proliferation, migration and invasion were assessed by cell viability assay and transwell assay. Luciferase assays and Western blotting were performed to demonstrate miR-381-3p target gene. RESULTS: We found that miR-381-3p was significantly down-regulated in PTC tissues and cell lines. In vitro assay indicated that up-regulation of miR-381-3p significantly suppressed PTC cell proliferation, migration and invasion. Moreover, luciferase reporter gene assay demonstrated that miR-381-3p could target LRP6 by binding to the 3' UTR. Western blot and Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) showed that miR-381-3p overexpression suppressed the expression of LRP6 at both mRNA and proteins levels. In addition, functional experiment confirmed that LRP6 was involved in the suppressive effect of miR-381-3p-mediated PTC on cell proliferation, migration and invasion. CONCLUSIONS: Our findings suggested, for the first time, that miR-381-3p was lowly expressed in PTC tissues, and its up-regulation inhibited tumorigenesis of PTC by targeting LRP6. [ABSTRACT FROM AUTHOR]

In the nucleus of differentiated osteoblasts, the alpha chain of nascent polypeptide associated complex (αNAC) interacts with cJUN transcription factors to regulate the expression of target genes, including Osteocalcin ( Bglap2 ). PTH induces the phosphorylation of αNAC on serine 99 through a Gαs-PKA dependent pathway. This leads to activation of αNAC and expression of Bglap2 . To identify additional target genes regulated by PTH-activated αNAC, we performed ChIP-Seq against αNAC in PTH-treated MC3T3-E1 cells. This identified Low density lipoprotein receptor-Related Protein 6 ( Lrp6 ) as a potential αNAC target. LRP6 acts as a co-receptor for the PTH receptor to allow optimal activation of PTH signaling. PTH increased Lrp6 mRNA levels in primary osteoblasts. Conventional quantitative ChIP confirmed the ChIP-Seq results. To assess whether αNAC plays a critical role in PTH-stimulated Lrp6 expression, we knocked-down Naca expression in MC3T3-E1 cells. Reduction of αNAC levels decreased basal expression of Lrp6 by 30% and blocked the stimulation of Lrp6 expression by PTH. We cloned the proximal mouse Lrp6 promoter (−2523/+120 bp) upstream of the luciferase reporter. Deletion and point mutations analysis in electrophoretic mobility shift assays and transient transfections identified a functional αNAC binding site centered around −343 bp. ChIP and ChIP-reChIP against JUND and αNAC showed that they cohabit on the proximal Lrp6 promoter. Luciferase assays confirmed that PTH-activated αNAC potentiated JUND-mediated Lrp6 transcription and Jund knockdown abolished this response. This study identified a novel αNAC target gene induced downstream of PTH signaling and represents the first characterization of the regulation of Lrp6 transcription in osteoblasts. [ABSTRACT FROM AUTHOR]

Summary: Objective: To examine the association of genetic variation in key players in the Wnt signaling pathway with aspects of osteoarthritis (OA) in two population-based cohort studies: the Rotterdam Study and the Chingford Study. Methods: Radiographic OA (ROA) was defined as a Kellgren/Lawrence score (K/L) score≥2 for the knee and hip. Total hip replacement (THR) was scored. Hand OA was defined as presence of ROA (K/L≥2) in two out of three hand joint groups [distal interphalangeal (DIPs), proximal interphalangeal (PIPs), first carpometacarpal (CMC1)/trapezio-scaphoid joint (TS)] of each hand. The concentration of urinary C-terminal cross-linked telopeptide of type II collagen (CTX-II) was standardized to the total urine creatinine. Genotypes for the amino acid variants, Arg200Trp and Arg324Gly of Frizzled-Related protein gene (FRZB), Ala1330Val of Low-density lipoprotein receptor-related protein 5 (LRP5) and Ile1062Val of Low-density lipoprotein receptor-related protein 6 (LRP6), were obtained using the Taqman allelic discrimination assay. A meta-analysis was performed for the FRZB Arg324Gly polymorphism and hip- and knee-OA using RevMan version 4.3. Results: No consistent associations were observed between the FRZB, LRP5 and LRP6 amino acid variants and radiographic hip-, knee-, or hand-OA or THR, in either study population. While power was limited for most studies to date, a meta-analysis of all published studies regarding the FRZB Arg324Gly polymorphism was performed for hip- and knee-OA seperately. This showed no significant associations between the Gly324 allele and risk for hip- or knee OA, although there was large heterogeneity between studies for hip OA in females. Conclusion: No association was seen between FRZB, LRP5 and LRP6 variants with radiographic osteoarthritic outcomes in two population-based cohorts. In future studies, increased power and standardization of OA-phenotypes are highly recommended for replication studies and to allow meta-analysis. [Copyright &y& Elsevier]