We demonstrate herein that silibinin, a polyphenolic flavonoid compound isolated from milk thistle (Silybum marianum), inhibits LPS-induced activation of macrophages and production of nitric oxide (NO) in RAW 264.7 cells. Western blot analysis showed silibinin inhibits iNOS gene expression. RT-PCR showed that silibinin inhibits iNOS, TNF-α, and IL1β. We also showed that silibinin strongly inhibits p38 MAPK phosphorylation, whereas the ERK1/2 and JNK pathways are not inhibited. The p38 MAPK inhibitor abrogated the LPS-induced nitrite production, whereas the MEK-1 inhibitor did not affect the nitrite production. A molecular modeling study proposed a binding pose for silibinin targeting the ATP binding site of p38 MAPK (1OUK). Collectively, this series of experiments indicates that silibinin inhibits macrophage activation by blocking p38 MAPK signaling.

ObjectiveThe aim of this prospective study was to evaluate the efficacy of bone cement-augmented percutaneous short segment fixation for treating Kummell's disease accompanied by severe osteoporosis.MethodsFrom 2009 to 2013, ten patients with single-level Kummell's disease accompanied by severe osteoporosis were enrolled in this study. After postural reduction for 1-2 days, bone cement-augmented percutaneous short segment fixation was performed at one level above, one level below, and at the collapsed vertebra. Clinical results, radiological parameters, and related complications were assessed preoperatively and at 1 month and 12 months after surgery.ResultsPrior to surgery, the mean pain score on the visual analogue scale was 8.5±1.5. One month after the procedure, this score improved to 2.2±2.0 and the improvement was maintained at 12 months after surgery. The mean preoperative vertebral height loss was 48.2±10.5%, and the surgical procedure reduced this loss to 22.5±12.4%. In spite of some recurrent height loss, significant improvement was achieved at 12 months after surgery compared to preoperative values. The kyphotic angle improved significantly from 22.4±4.9° before the procedure to 10.1±3.8° after surgery and the improved angle was maintained at 12 months after surgery despite a slight correction loss. No patient sustained adjacent fractures after bone cement-augmented percutaneous short segment fixation during the follow-up period. Asymptomatic cement leakage into the paravertebral area was observed in one patient, but no major complications were seen.ConclusionBone cement-augmented percutaneous short segment fixation can be an effective and safe procedure for Kummell's disease.

MDC1 is critical component of the DNA damage response (DDR) machinery and orchestrates the ensuring assembly of the DDR protein at the DNA damage sites, and therefore loss of MDC1 results in genomic instability and tumorigenicity. However, the molecular mechanisms controlling MDC1 expression are currently unknown. Here, we show that miR-22 inhibits MDC1 translation via direct binding to its 3 0 untranslated region, leading to impaired DNA damage repair and genomic instability. We demonstrated that activated Akt1 and senescence hinder DDR function of MDC1 by upregulating endogenous miR-22. After overexpression of constitutively active Akt1, homologous recombination was inhibited by miR-22-mediated MDC1 repression. In addition, during replicative senescence and stress-induced premature senescence, MDC1 was downregulated by upregulating miR-22 and thereby accumulating DNA damage. Our results demonstrate a central role of miR-22 in the physiologic regulation of MDC1-dependent DDR and suggest a molecular mechanism for how aberrant Akt1 activation and senescence lead to increased genomic instability, fostering an environment that promotes tumorigenesis. Cancer Res; 75(7); 1298-310. Ó2015 AACR.

Terminally differentiated cells have a reduced capacity to repair double-stranded breaks (DSB) in DNA, however, the underlying molecular mechanism remains unclear. Here, we show that miR-22 is upregulated during postmitotic differentiation of human breast MCF-7 cells, hematopoietic HL60 and K562 cells. Increased expression of miR-22 in differentiated cells was associated with decreased expression of MDC1, a protein that plays a key role in the response to DSBs. This downregulation of MDC1 was accompanied by reduced DSB repair, impaired recruitment of the protein to the site of DNA damage following IR. Conversely, inhibiting miR-22 enhanced MDC1 protein levels, recovered MDC1 foci, fully rescued DSB repair in terminally differentiated cells. Moreover, MDC1 levels, IR-induced MDC1 foci, and the efficiency of DSB repair were fully rescued by siRNA-mediated knockdown of c-Fos in differentiated cells. These findings indicate that the c-Fos/miR-22/MDC1 axis plays a relevant role in DNA repair in terminally differentiated cells, which may facilitate our understanding of molecular mechanism underlying the downregulating DNA repair in differentiated cells.

Here, we show that radicicol, a fungal antibiotic, resulted in marked inhibition of inducible nitric oxide synthase (iNOS) transcription by the pancreatic beta cell line MIN6N8a in response to cytokine mixture (CM: TNF-α, IFN-γ, and IL-1β). Treatment of MIN6N8a cells with radicicol inhibited CM-stimulated activation of NF-κB/Rel, which plays a critical role in iNOS transcription, in a dose-related manner. Nitrite production in the presence of PD98059, a specific inhibitor of the extracellular signal-regulated protein kinase-1 and 2 (ERK1/2) pathway, was dramatically diminished, suggesting that the ERK1/2 pathway is involved in CM-induced iNOS expression. In contrast, SB203580, a specific inhibitor of p38, had no effect on nitrite generation. Collectively, this series of experiments indicates that radicicol inhibits iNOS gene expression by blocking ERK1/2 signaling. Due to the critical role that NO release plays in mediating destruction of pancreatic beta cells, the inhibitory effects of radicicol on iNOS expression suggest that radicicol may represent a useful anti-diabetic activity.