High β-catenin/Tcf-4 activity confers glioma progression via direct regulation of AKT2 gene expression

Recent data suggest that the β-catenin/Tcf-4 signaling pathway plays an important role in human cancer tumorigenesis. However, the mechanism of β-catenin/Tcf-4 signaling in tumorigenesis is poorly understood. In this study, we show that Tcf-4 protein levels were significantly elevated in high-grade gliomas in comparison with low-grade gliomas and that Tcf-4 levels correlated with levels of AKT2. Reduction of β-catenin/Tcf-4 activity inhibited glioma cell proliferation and invasion in vitro and tumor growth in vivo. This effect of β-catenin/Tcf-4 activity was mediated by AKT2, and in vivo binding of β-catenin/Tcf-4 to the AKT2 promoter was validated using the chromatin immunoprecipitation assay and luciferase reporter assays. Taken together, we have demonstrated that Tcf-4 is associated with glioma progression and that AKT2 is a new member of the genes that are regulated by β-catenin/Tcf-4.     

Systemic treatment with murine recombinant interleukin-1β inhibits the growth and progression of malignant glioma in the rat

We investigated the effects of daily subcutaneous (SC) injections of 100, 200, or 400 g/kg murine recombinant interleukin-1 (rIL-1) or its excipient on normal Fischer 344 rats and ones harboring a malignant RT-2 glioma. The tumor model has a predictable course with animals dying on days 14–17 following an intracerebral inoculation of 10⁴ RT-2 glioma cells. Treatments with (rIL-1) or excipient began on day seven post-tumor inoculation and continued for 7 days. We observed no significant effect on core body temperatures although there was a significant (p < 0.05) decrease in body weight in all (rIL-1) treated animals. When tumor-bearing animals became moribund, they received an intraperitoneal injection of bromodeoxyuridine (BUdr) and were sacrificed two hours later. Blood samples were obtained prior to their sacrifice by transcardiac perfusion with a buffered aldehyde solution. Recombinant IL-4ß affected blood differentials; causing neutrophilia, lymphopenia, and slight thrombocythemia. The BUdr labeling index of glioma cells did not significantly differ between treatment groups, although tumors differed histologically at the time of necropsy. Tumors of rIL-1 treated animals had more extensive necrosis and a greater degree of leukocyte infiltration. Survival studies were conducted in which rats were given continuous daily SC injections of (rIL-1) until day of death. Overall survival between the two groups differed significantly in studies using 100 g/kg/d (p < 0.05); (rIL-1ß) treated rats had a mean survival time of 22 (± 3.0) days while excipient controls had a mean survival time of 17 (± 0.5) days. Similarly, at a dose of 200 g rIL-1(3/kg/d), mean survival was significantly (p < 0.05) increased as compared to excipient controls (18.75 ± 1.5 vs. 15.25 ± 1.7 days, respectively). Daily injections of 400 g/kg did not significantly increase the survival of glioma bearing animals, possibly as a consequence of fIL-1ß toxicity at this dose.     

Expression of FRAT1 and β-catenin in human brain glioma and their significances

Objective: To investigate the expression of FRAT1 and β-catenin in human brain glioma, analyze the correlation between the expression and clinical pathological grades and the correlation of the two genes. Methods: FRAT1 and β-catenin were detected by immunohistochemistry in 84 human brain glioma tissues and 6 human normal brain tissues. Results: 66.7% (56/84) and 77.4% (65/84) of human brain glioma tissues expressed FRAT1 and β-catenin protein, whereas no FRAT1 and β-catenin protein expression was detected in human normal brain tissues. The expression levels of FRAT1 and β-catenin increased markedly with the ascending of pathologic grade of tumor specimens (r = 0.55, P < 0.01, r = 0.70, P < 0.01), there was a positive correlation between FRAT1 and β-catenin (r = 0.77, P < 0.01). Conclusion: FRAT1 and β-catenin over-expression maybe closely related with occurrence and development of human brain gliomas. The results provide important supplements for the research of Wnt/β-catenin pathway. Meanwhile, FRAT1 may act as a valuable biomarker for molecular diagnosis of glioma and a potential target for gene therapy of glioma.     

Inhibition of hypoxia inducible factor 1α expression suppresses the progression of esophageal squamous cell carcinoma

Hypoxia inducible factor 1α (HIF-1α) is highly expressed and is implicated in the progression of esophageal squamous cell carcinoma. To investigate the potential mechanism by which HIF-1α contributes to the progression of esophageal squamous cell carcinoma, here we established stable esophageal carcinoma cell lines Eca-109 and TE- 13 in which HIF-1α was depleted by shRNA mediated gene silencing. In additon, we used specific inhibitor YC-1 to inhibit HIF-1α expression. Our in vitro studies demonstrated that shRNA or chemical mediated inhibition of HIF-1α led to reduced proliferation and increased apoptosis of esophageal carcinoma cells, as well as the downregulatuion of HIF-1α targets VEGF, MMP2 and BCL2. Furthermore, we employed xenograft nude mice model to validate the in vitro findings and proved that depletion of HIF-1α suppressed the tumorigenicity of esophageal carcinoma cells in vivo. In conclusion, our results provide new insight into the potential role of HIF-1α in esophageal squamous cell carcinoma and open up the possibility of inhibiting HIF-1α for targeted therapy of esophageal squamous cell carcinoma.     

Silencing of CCDC6 reduces the expression of 14-3-3σ in colorectal carcinoma cells

Coiled-coil domain containing 6 (CCDC6) is frequently rearranged in papillary thyroid carcinomas participating in the formation of RET/PTC1 oncogene. Other rearrangements involving CCDC6 have also been identified demonstrating its high susceptibility to chromosomal recombination. Malignancies bearing CCDC6 fusion genes are developed in a background where CCDC6 is either lost or deregulated. Our aim was to identify interacting proteins which are affected by the silencing of CCDC6 expression and could possibly link CCDC6 deregulation to cancer causality. Therefore, a proteomic approach was adopted using a human cancer cell-line (HCT116) where CCDC6 expression was silenced by lentiviral shRNA constructs. 14-3-3σ down-regulation in the absence of CCDC6 was revealed and verified by western blot analysis and confocal microscopy. Only the levels and not the topology of CCDC6 were altered. The down-regulation of 14-3-3σ in the absence of CCDC6 demonstrated their direct association and supports the notion that CCDC6 contributes to cancer development, possibly through malignant pathways involving 14-3-3σ.     

Roles of cyclin-dependent kinase 8 and β-catenin in the oncogenesis and progression of gastric adenocarcinoma

Gastric adenocarcinoma is a common cause of cancer-related death. The Wnt/β-catenin pathway plays an important role in various cancers. However, relatively little is known about the regulatory mechanism of β-catenin in stomach cancer. To determine the patterns of cyclin-dependent kinase (CDK) 8 and β-catenin expression and the relationship between CDK8 and β-catenin, we conducted a study of immuno-histochemical staining of tumor tissues (12 adenomas, 24 early gastric carcinomas, 24 advanced gastric carcinomas and 21 metastatic lymph nodes), together with Western blot analysis and CDK8 interference studies using gastric cancer cell lines. Gastric adenocarcinomas with CDK8 expression had distinct clinical, prognostic and molecular attributes. CDK8 expression and the delocalization of β-catenin expression showed a significant positive correlation with carcinogenesis and tumor progression, especially lymph node metastasis. Immunohisto-chemically, CDK8 expression in gastric adenocarcinoma was independently associated with β-catenin activation (p<0.05). β-catenin expression was suppressed by CDK8 interference in the gastric adenocarcinoma cell lines, SNU-601 and SNU-638. These data support the potential link between CDK8 and β-catenin, and suggest that CDK8 detection and β-catenin delocalization could be related to a poor prognosis. Moreover, the interference of CDK8 could be a promising therapeutic modality for gastric adenocarcinoma.     

Differential gene expression profile reveals deregulation of pregnancy specific β1 glycoprotein 9 early during colorectal carcinogenesis

Background  

APC (Adenomatous polyposis coli) plays an important role in the pathogenesis of both familial and sporadic colorectal cancer. Patients carrying germline APC mutations develop multiple colonic adenomas at younger age and higher frequency than non-carrier cases which indicates that silencing of one APC allele may be sufficient to initiate the transformation process.     

Neural stem cell markers, nestin and musashi proteins, in the progression of human glioma： correlation of nestin with prognosis of patient survival

BACKGROUND： The IF protein nestin and the RNA-binding protein musashi are expressed by neural progenitor cells during CNS development. Their expression in glial tumors was evaluated by immunohistochemistry, and the histopathological scores correlated with levels of cysteine cathepsins that are known prognostic markers in several tumors. METHODS： The levels of nestin, musashi, and cathepsins B and L were assessed by immunohistochemical analysis of biopsies from 87 patients with primary CNS tumors. To confirm the immunohistochemical data, nestin expression was analyzed by real-time PCR in 12 brain tumor biopsies.[第一段]     

Expression patterns of the tumor suppressor PDCD4 and correlation with β-catenin expression in gastric cancers

The expression patterns of PDCD4, a tumor suppressor, and β-catenin were immunohistologically investigated in gastric carcinoma tissues. In normal gastric tissues, PDCD4 was strongly expressed in the cell nuclei, but weakly expressed in the cytoplasm. In gastric adenocarcinoma tissues, nuclear PDCD4 expression was decreased, while cytoplasmic PDCD4 expression was unchanged or somewhat increased. In gastric signet ring cell carcinoma tissues, PDCD4 expression patterns were different from the expression patterns of the adenocarcinoma tissues, and PDCD4 was localized in the nuclei of the carcinoma cells as a belt in the middle of the epithelial layer. The nuclear localization of PDCD4 in the adenocarcinoma tissues was correlated with the membrane localization of β-catenin, the activation of which stimulates invasion of colon cancer cells. PDCD4 expression was correlated with β-catenin expression in gastric carcinoma cell lines, but not with E-cadherin, as the binding partner in the cell membrane.     

Allelic loss of chromosome 3p24 correlates with tumor progression rather than with retinoic acid receptor β2 expression in breast carcinoma

A tumor suppressor gene, retinoic acid receptor (RAR) 2, has been mapped to chromosome 3p24, a region where loss of heterozygosity (LOH) has been observed commonly in carcinomas of various tumor tissues. RAR 2 expression is reduced or lost in many malignant tumors including breast cancer, however, whether LOH accounts for the loss of expression of RAR 2 in breast cancer is unknown. We, therefore, assessed LOH on chromosome band 3p24 to correlate it with RAR 2 expression and other established prognostic parameters in 52 breast carcinomas. Based on three microsatellites, D3S 1283, D3S 1293 and D3S 1286, all of the tumors were informative, of these, 12 (23%) exhibited LOH. RAR 2 expression was lost in 42% (19/45) of these samples. We found that LOH on chromosome band 3p24 was not correlated with loss of RAR 2, but correlated with higher histological grade, p53-positivity, and loss of estrogen and progesterone receptors. Our findings suggest that LOH of the RAR 2 gene does not account for the frequent loss of RAR 2 expression in breast cancer but the genomic structural alteration at or close to the RAR 2 gene locus are likely to be associated with tumor progression and/or loss of hormonal dependency.     

Overexpression of dopamine receptor D2 promotes colorectal cancer progression by activating the β-catenin/ZEB1 axis

Colorectal cancer (CRC) is a recurring cancer that is often resistant to conventional therapies and therefore requires the development of molecular-based therapeutic approaches. Dopamine receptor D2 (DRD2) is associated with the growth of many types of tumors, but its oncogenic role in CRC is unclear. Here, we observed that elevated DRD2 expression was associated with a poor survival rate among patients with CRC. Depletion of DRD2 suppressed CRC cell growth and motility by downregulating β-catenin/ZEB signaling in vitro and in vivo, whereas overexpression of DRD2 promoted CRC cell progression. Inhibition of DRD2 by the antagonist pimozide inhibited tumor growth and lymph node metastasis in vivo and enhanced the cytotoxic effects of conventional agents in vitro. Taken together, our findings indicate that targeting the DRD2/β-catenin/ZEB1 signaling axis is a potentially promising therapeutic strategy for patients with CRC.