MicroRNA-506 upregulation contributes to sirtuin 1 inhibition of osteoclastogenesis in bone marrow stromal cells induced by TNF-α treatment.

As a deacetylase relying on NAD, sirtuin 1 (SIRT1) has been proven to inhibit osteoclastogenesis directly by repressing reactive oxygen species (ROS) production and TRPV1 channel stimulation modulated by TNF-α. MicroRNAs do not have coding functions, but they influence the expression of particular genes after transcription. Nevertheless, the current understanding of the impact of SIRT1 on osteoclastogenesis is insufficient. Our research explored whether and how miRNAs contributed to osteoclast differentiation modulated by SIRT1 in vitro. In osteoclastogenesis induced by RANKL in bone marrow-derived macrophages (BMMs), repression of SIRT1 expression and enhancement of miR-506 expression were discovered. Transfection with an miR-506 inhibitor repressed miR-506 concentration in BMMs treated with RANKL. Additional research revealed that BMMs with repressed miR-506 treated with RANKL displayed phenotypes with suppressed osteoclastogenesis, as demonstrated by TRAP staining, reduced function, decreased expression of osteoclast markers and correlated genes, and reduced multinuclear cell quantity. Bioinformatics prediction outcomes and the dual-luciferase reporter test suggested that miR-506 targeted the SIRT1 3'-UTR for silencing. Decreased miR-506 in BMMs induced by RANKL caused SIRT1 upregulation. Additionally, treatment with EX-527 (SIRT1 repressor) or SIRT1 silencing attenuated repression caused by miR-506 depletion in BMMs treated with RANKL. Furthermore, TNF-α was repressed via miR-506 inhibition but was enhanced following EX-527 incubation as well as SIRT1 depletion. TRPV1 channel stimulation and ROS generation, which was related to osteoclastogenesis, were reduced via miR-506 depletion. miR-506 modulated osteoclastogenesis by targeting SIRT1 expression in part through modulation of the TRPV1 channel, ROS production, and TNF-α.

miR-106b promotes proliferation and invasion by targeting Capicua through MAPK signaling in renal carcinoma cancer.

Background: miR-106b has been reported to play a vital role in pathogenesis of some types of cancer, whilst the role of miR-106b in renal carcinoma cancer (RCC) remains unknown. Purpose: The objective of this study was to identify the mechanism of miR-106b regulating the progression of renal carcinoma. Method: The expression of miR-106b was analyzed in RCC cell lines, RCC and adjacent normal renal tissues through qRT-PCR assays. Target mRNA of miR-106b was predicted with databases and verified by luciferase reporter assays. And the effects of miR-106b or targeted mRNA on cell proliferation, invasion, the process of epithelial-mesenchymal transitions (EMTs) were assessed in vitrothrough CCK-8, transwell cell invasion assays, qRT-PCR and Western blotting assays respectively. In addition, the effects of miR-106b on the growth of xenografts mice were analyzedin vivo. Results: The results demonstrated that miR-106b was significantly increased both in RCC tissues and cell lines. Luciferase reporter assays revealed that miR-106b inhibited Capicua expression by targeting its 3'-UTR sequence. And miR-106b promoted cell proliferation, invasion, EMT progression in RCC cellin vitro, as well as promoted the tumor growth of 786-O cells derived xenografts mice. Additionally, loss of Capicua promoted the activation of MAPK signaling pathway. Conclusion: The study suggested that miR-106b regulated RCC progression through MAPK signaling pathway partly by targeting Capicua, which might provide valuable evidence for therapeutic target development of RCC.

Sirtuin 1 inhibits TNF-α-mediated osteoclastogenesis of bone marrow-derived macrophages through both ROS generation and TRPV1 activation.

Sirtuin 1 (SIRT1), also known as NAD-dependent deacetylase, has been reported to increase in vivo osteoclast-mediated bone resorption. However, its effects on osteoclastogenesis or bone loss in vitro have not been widely examined. Therefore, the effects and underlying mechanism of SIRT1 on osteoclast differentiation in mice in vitro were studied. During RANKL-induced osteoclastogenesis in differentiated bone marrow-derived macrophages (BMMs), SIRT1 downregulation was observed. The use of resveratrol (SIRT1 activator) and SIRT1 overexpression was found to inhibit osteoclastogenesis, which was confirmed by TRAP staining and activity loss, reduced expression of osteoclast markers and related genes, and a decrease in the number of multinuclear cells. In contrast, treatment with EX-527 (SIRT1 inhibitor) as well as SIRT1 silencing promoted osteoclastogenesis. Furthermore, the tumor necrosis factor (TNF)-α level was reduced by resveratrol treatment and SIRT1 overexpression but increased following EX-527 incubation and SIRT1 depletion. TNF-α silencing blocked the osteoclastogenesis of BMMs promoted by SIRT1 depletion. Moreover, transient receptor potential vanilloid 1 (TRPV1) channel activation and reactive oxygen species (ROS) production, which are associated with osteoclastogenesis, were impaired by TNF-α silencing. These data demonstrate that SIRT1 directly inhibits osteoclastogenesis by inhibiting ROS generation and TRPV1 channel activation under mediation of TNF-α.

Chemopreventive effect of mofezolac on beef tallow diet/azoxymethane-induced colon carcinogenesis in rats.

BACKGROUND/AIMS: We have previously shown that long-term consumption of 10% beef tallow diet promotes colon carcinogenesis in both saline- and azoxymethane (AOM)-treated rats. Here, we investigated the effects of mofezolac, a selective COX-1 inhibitor, on beef tallow-fed rats with saline- or AOM treatment. METHODOLOGY: Male SD rats were intraperitoneally injected with saline or AOM and fed 10% beef tallow diet with or without 1200 ppm mofezolac. At 12 weeks, aberrant crypt foci (ACF) were examined. At 44 weeks, tumors were counted, the proliferation and expression of COX-1 and 8-catenin on normal-appearing colonic mucosa was evaluated using the BrdU incorporation assay and Western blotting respectively. RESULTS: Mofezolac decreased the number of ACF at 12 weeks (p < 0.05) and reduced tumor multiplicity and incidence at 44 weeks in beef tallow-fed rats with AOM treatment (p < 0.05). At 44 weeks, reduction of the BrdU-positive cells (p < 0.05) and beneficial distribution changes of these cells within the colon crypts in both groups with mofezolac supplementation were observed. The expression of COX-1 and beta-catenin also reduced in mofezolac-added groups simultaneously (p < 0.05). CONCLUSIONS: This study suggested that mofezolac suppressed beef tallow-promoted colon carcinogenesis in rats, which probably was, appropriate for populations with high fat intake.

Long-term ingestion of reduced glutathione suppressed an accelerating effect of beef tallow diet on colon carcinogenesis in rats.

PURPOSE: We have shown previously that long-term feeding of beef tallow increases colorectal cancer in rats. This study investigated the effects of enzymic antioxidant, reduced glutathione (GSH), on colon carcinogenesis in rats fed with beef tallow. METHODS: Colon carcinogenesis was induced by intraperitoneal injection of azoxymethane (AOM) to rats. Rats were fed with 10% beef tallow supplemented with or without 1% GSH in drinking water. Aberrant crypt foci (ACF) and expression of beta-catenin in colonic mucosa were examined at 12 weeks. Cancers, related substances of oxidative stress and arachidonic acid cascade in plasma and normal colonic mucosa were determined at 44 weeks. RESULTS: GSH attenuated the number of ACF increased by beef tallow, but GSH had no influence on expression of beta-catenin increased by AOM. Incidence of colon cancer was no different with or without GSH, but GSH attenuated the number of colon cancers in each rat. GSH suppressed plasma malondialdehyde concentration. GSH increased GSH concentration and activities of catalase, glutathione peroxidase and superoxide dismutase in colonic mucosa, and decreased cyclooxygenase-2, prostaglandin E2 and thromboxane B2 levels. CONCLUSIONS: This study indicated that GSH suppressed the number of ACF, but the attenuation of colon carcinogenesis was limited to the number of colon cancers, although anti-oxidative effects and suppressive effects of arachidonic acid cascade were demonstrated by several indexes. These results suggested that colon carcinogenesis enhanced by beef tallow was partly caused by oxidative stress and arachidonic acid cascade, which were reduced by GSH.