Casitas B-lineage lymphoma (CBL) protein family functions as multifunctional adaptor proteins and E3 ubiquitin ligases that are implicated as regulators of signaling in various cell types. Recent discovery revealed mutations of proto-oncogenic CBL in the linker region and RING finger domain in human acute myeloid neoplasm, and these transforming mutations induced carcinogenesis. However, the adaptor function of CBL mediated signaling pathway during tumorigenesis has not been well characterized. Here, we show that CBL is highly expressed in breast cancer cells and significantly inhibits transforming growth factor-b (TGF-b) tumor suppressive activity. Knockdown of CBL expression resulted in the increased expression of TGF-b target genes, PAI-I and CDK inhibitors such as p15 INK4b and p21 Cip1 . Furthermore, we demonstrate that CBL is frequently overexpressed in human breast cancer tissues, and the loss of CBL decreases the tumorigenic activity of breast cancer cells in vivo. CBL directly binds to Smad3 through its proline-rich motif, thereby preventing Smad3 from interacting with Smad4 and blocking nuclear translocation of Smad3. CBL-b, one of CBL protein family, also interacted with Smad3 and knockdown of both CBL and CBL-b further enhanced TGF-b transcriptional activity. Our findings provide evidence for a previously undescribed mechanism by which oncogenic CBL can block TGF-b tumor suppressor activity.
Sorafenib, which is approved for treatment of HCC, has also shown promising antifibrotic activity, and therefore refinement of its dosing requirements and window of efficacy are important goals prior to antifibrotic clinical trials. Aim To determine the minimal effective dose and optimal timing of sorafenib therapy in cultured human stellate cells and in rats with experimental hepatic fibrosis. Methods Effects of sorafenib were assessed in a human stellate cell line (LX-2). In vivo, rats were treated for 8 wks with TAA three times pre week (150 mg/kg IP), and with either PBS, or sorafenib administered daily at doses of 1.25, 5 or 7 mg/kg/day gavage either at the beginning of TAA adminstration for 8 wks, during weeks 4–8, or from weeks 8–12. Results Sorafenib treatment significantly inhibited LX-2 proliferation by > 75% (7.5 or 15 µM). Treatment with 7.5 µM sorafenib for 12 hours markedly inhibited expression of TGFβ1, TIMP-1, collagen I, and MMP2 mRNAs, but not of β-PDGFR or type I TGFβR. In vivo, sorafenib significantly inhibited liver fibrosis when started concurrently with TAA and during weeks 4–8 with TAA. In contrast, there was no significant effect of sorafenib on fibrogenic gene expression or fibrosis when begun after cirrhosis was already established. Conclusion Sorafenib is anti-proliferative and antifibrotic towards human HSCs in culture, and is a potent antifibrotic agent in TAA-induced hepatic fibrosis in rats. The drug is effective at relatively low doses at the early stage of liver fibrosis, but is not effective when cirrhosis is already established.
Previously, we reported that Helicobacter pylori-associated gastritis and gastric cancer are closely associated with increased levels of hydrogen sulfide (H2S) and that Korean red ginseng significantly reduced the severity of H. pylori-associated gastric diseases by attenuating H2S generation. Because the incubation of endothelial cells with H2S has been known to enhance their angiogenic activities, we hypothesized that the amelioration of H2S-induced gastric inflammation or angiogenesis in human umbilical vascular endothelial cells (HUVECs) might explain the preventive effect of Korean red ginseng on H. pylori-associated carcinogenesis. The expression of inflammatory mediators, angiogenic growth factors, and angiogenic activities in the absence or presence of Korean red ginseng extracts (KRGE) were evaluated in HUVECs stimulated with the H2S generator sodium hydrogen sulfide (NaHS). KRGE efficiently decreased the expression of cystathionine β-synthase and cystathionine γ-lyase, enzymes that are essential for H2S synthesis. Concomitantly, a significant decrease in the expression of inflammatory mediators, including cyclooxygenase-2 and inducible nitric oxide synthase, and several angiogenic factors, including interleukin (IL)-8, hypoxia inducible factor-1a, vascular endothelial growth factor, IL-6, and matrix metalloproteinases, was observed; all of these factors are normally induced after NaHS. An in vitro angiogenesis assay demonstrated that NaHS significantly increased tube formation in endothelial cells, whereas KRGE pretreatment significantly attenuated tube formation. NaHS activated p38 and Akt, increasing the expression of angiogenic factors and the proliferation of HUVECs, whereas KRGE effectively abrogated this H2S-activated angiogenesis and the increase in inflammatory mediators in vascular endothelial cells. In conclusion, KRGE was able to mitigate H2S-induced angiogenesis, implying that antagonistic action against H2S-induced angiogenesis may be the mechanism underlying the gastric cancer preventive effects of KRGE in H. pylori infection.
Colitis-associated cancer (CAC) is one of clear examples of inflammation-carcinogenesis sequence, by which the strict control of colitis with potent anti-inflammatory or antioxidative agent offers the chance of cancer prevention. Supported with the facts that Rac1 binds and activates STAT3, which are significantly upregulated in inflammatory bowel disease (IBD) as well as CAC, but 8-hydroxydeoxyguanosine (8-oxo-7,8-dihydrodeoxyguanosine or 8-OHdG) paradoxically can block Rac1 activation and subsequent NADPH oxidase (NOX) inactivation in various inflammation models, we hypothesized that attenuated Rac1-STAT3 and COX-NF-kB pathway by exogenous 8-OHdG administration may ameliorate inflammatory signaling in dextran sodium sulfate (DSS)-induced colitis and can prevent CAC. Before commencing carcinogenesis model, we checked whether exogenous 8-OHdG can alleviate IBD, for which interleukin (IL)-10 knockout mice were designed to ingest 5% DSS for 1 week, and 8-OHdG is given through intraperitoneal route daily. 8-OHdG treatment groups significantly reduced pathologic grade of DSSinduced colitis as well as various inflammatory mediators such as TNF-a, IL-6, COX-2, and iNOS in a dose-dependent manner. To document the cancer prevention effects of 8-OHdG, mice were injected azoxymethane followed by drinking 2.5% DSS for 1 week, after which 8-OHdG-containing diets were given for 20 weeks. As results, mice that consumed 8-OHdG-containing diet significantly reduced both tumor incidence and multiplicity. Rac1 activity and phosphorylated STAT3 level were significantly attenuated in the 8-OHdG-treated group. Significantly decreased levels of malondialdehyde, monocyte chemotactic protein-1, matrix metalloproteinasess, COX-2, NOX4, and b-catenin nuclear accumulation were responsible for cancer prevention effects of exogenous 8-OHdG. In conclusion, we clearly showed cancer-preventive effect of exogenous 8-OHdG against CAC. Cancer Prev Res; 4(9); 1507-21. Ó2011 AACR.
Wernicke encephalopathy (WE) is characterized by eye signs, cerebellar dysfunction, and confusion. Epileptic seizures are rare in nonalcoholic WE. We reviewed the clinical, laboratory, radiological, and prognostic characteristics of nonalcoholic WE accompanied by epileptic seizures. We reported 1 case and searched similar cases using PubMed, WoK, Ovid, and Embase. WE was diagnosed according to dietary deficiencies, clinical symptoms and brain magnetic resonance imaging (MRI). We reviewed 13 patients (median age, 27 years; 5 men) with clear histories of thiamine deficiency and symptoms of typical WE. The type of epileptic seizures reported in the 13 cases reviewed was generically reported as seizures or convulsions in 4 patients; 7 patients had generalized tonic-clonic seizures, 1 partial seizure, and 1 generalized convulsive status epileptics. Two patients had epileptic seizures as the first symptom of WE. Laboratory tests mainly indicated metabolic acidosis and electrolyte disturbances. Electroencephalography may present as normal patterns, increased slow waves or epileptic discharge. Six patients had cortical lesions on brain MRI. These lesions were usually diffuse and band-like, and sometimes involved all lobes either symmetrically or asymmetrically, with the frontal lobe as the most susceptible area. All cortical lesions were accompanied by non-cortical lesions typical of WE. Brain MRI abnormalities, after thiamine treatment, mostly disappeared on follow-up MRIs. The patients had good prognoses. Only 1 patient had repeated seizures, and there were no comas or deaths. Patients with nonalcoholic WE accompanied by seizures are young and generally have good prognoses. Most patients experienced generalized convulsive seizures, which may have been related to abnormal cerebral cortical metabolism due to subacute thiamine deficiency.
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