Bcl-2 expression and allelic loss of thep53 gene in gastric carcinomas

In order to clarify the association betweenbcl-2 protein (Bcl-2) expression and genetic alteration, we investigatedp53 andDCC (deleted in the colon carcinoma gene locus) gene abnormalities in Bcl-2-positive and-negative gastric carcinomas using a polymerase chain reaction/loss of heterozygosity (LOH) assay. Bcl-2 immunoreactivity was found in 25 of 178 (14%) gastric carcinoma cases. With these 25 positive cases, the proportion 18/87 (20.6%) of the total in early stages demonstrating invasion of the mucosa and/or submucosa was significantly greater (P=0.013) than the 7/91 (7.7%) found for advanced tumors exhibiting invasion into or through the muscularis propria. However, there was no statistically significant variation between the proportions for differentiated (17/98 cases, 17.3%) and undifferentiated (8/80 cases, 10%) lesions. Sixteen Bcl-2-positive cases (9 cases were not studied because of insufficient specimen material to allow extraction of DNA) and 31 cases randomly selected from a Bcl-2-negative group were analyzed for the presence ofp53-LOH or DCC-LOH and forp53 by immunohistochemistry. The minority of the Bcl-2-positive group hadp53-LOH and were immunopositive for p53 (P=0.033,P=0.028 respectively), while no association was found in the Bcl-2-negative category. In contrast, there was no correlation at all between Bcl-2 expression and DCC-LOH although the number of informative cases analyzed was too small to allow definite conclusions. These results indicate that Bcl-2 may be predominantly expressed at an early stage in gastric carcinomas, possibly in negative association withp53 gene abnormalities.Abbreviations DCC deleted in colon carcinoma gene locus - LOH loss of heterozygosity - PCR polymerase chain reaction - VNTR variable number of tandem repeats     

Molecular mechanisms of axon guidance in the developing corticospinal tract

The great repertoire of movements in higher order mammals comes courtesy of the corticospinal tract (CST) which is able to initiate precise movement of the entire musculature of the axial and limb muscle groups. It forms the longest axonal trajectory in the mammalian central nervous system and its axons must navigate the entire length of the central nervous system--from its origins in the deeper layers of the cerebral cortex down through the cerebral peduncles and brainstem and along the entire length of the spinal cord. This period of navigation is incredibly complex, and relies upon the coordinated regulation of a collection of molecular guidance cues - coming from all of the known major families of guidance cues - the ephrins, slits, Netrins and Semaphorins - that work together to steer the growing axonal tips through the brain and spinal cord. As such a long tract, the CST forms an excellent experimental model to investigate the nature of molecular cues that sequentially guide axons through the central nervous system. Using the rodent as a model system, this review discusses each step of axonal guidance through the major brain regions--starting from the decision to grow ventrally out of the cortical plate to the eventual activity-dependent refinement of circuitry in the spinal grey matter. In recent years, the identification of these guidance cues and their proposed mode of action is beginning to give us a picture at a molecular level of how the CST is guided so accurately over such a long distance.     

应用组织芯片技术研究DCC蛋白在胰腺癌中的表达及意义

目的:研究结直肠癌缺失(deleted in colorectal cancer,DCC)基因在胰腺癌中表达的意义及其与临床病理学因素的关系。方法:构建胰腺癌组织芯片,使用免疫组化法检测DCC蛋白表达情况,并分析其与肿瘤大小、分化程度、有无淋巴结转移以及TNM分期等临床病理学因素之间的关系。结果:胰腺癌组织芯片免疫组化结果显示,DCC在胰腺癌中表达的阳性率为17%(7/41),明显低于正常胰腺组织中的表达阳性率87%(34/39)(P<0.001)。胰腺癌发生淋巴结转移时DCC蛋白的表达水平0.29±0.768明显低于无淋巴结转移的胰腺癌1.27±2.27(P=0.037)。DCC在Ⅲ和Ⅳ期胰腺癌中的表达水平0.25±0.71显著低于Ⅰ期1.39±2.63和Ⅱ期1.25±2.12胰腺癌的表达水平(P=0.032)。结论:DCC蛋白在胰腺癌中表达降低或缺失是胰腺癌发生发展过程中的一个频繁发生的事件,免疫组化法检测DCC蛋白的表达对胰腺癌的预后评估具有重要意义。     

Serine protease modulation of Dependence Receptors and EMT protein expression

Expression of the tumour suppressor Deleted in Colorectal Cancer (DCC) and the related protein neogenin is reduced by the mammalian serine protease chymotrypsin or the bacterial serine protease subtilisin, with increased cell migration. The present work examines whether these actions are associated with changes in the expression of cadherins, β-catenin and vimentin, established markers of the Epithelial-Mesenchymal Transition (EMT) which has been linked with cell migration and tumour metastasis. The results confirm the depletion of DCC and neogenin and show that chymotrypsin and subtilisin also reduce expression of β-catenin in acutely prepared tissue sections but not in human mammary adenocarcinoma MCF-7 or MDA-MB-231 cells cultured in normal media, or primary normal human breast cells. A loss of β-catenin was also seen in low serum media but transfecting cells with a dcc-containing plasmid induced resistance. E-cadherin was not consistently affected but vimentin was induced by low serum-containing media and was increased by serine proteases in MCF-7 and MDA-MB-231 cells in parallel with increased wound closure. Vimentin might contribute to the promotion of cell migration. The results suggest that changes in EMT proteins depend on the cells or tissues concerned and do not parallel the expression of DCC and neogenin. The increased cell migration induced by serine proteases is not consistently associated with the expression of the EMT proteins implying either that the increased migration may be independent of EMT or supporting the view that EMT is not itself consistently related to migration. (241).     

An imbalance of netrin-1 and DCC during nigral degeneration in experimental models and patients with Parkinson's disease

Aims

Multiple guidance cues, such as netrin-1 (NTN-1)/deleted in colorectal carcinoma (DCC), control the guidance of axons and help establish functional neural circuits during development. However, the function of these guidance molecules during the neurodegenerative process is unclear.

Methods

To access the alterations of NTN-1 and DCC during the onset and progression of PD, we first established two subacute and one chronic PD model. Then, we investigated the relationship between the NTN-1/DCC pathway and cell death in SH-SY5Y cells. Finally, we conducted correlation studies between plasma NTN-1 and parkinsonian symptoms in patients to understand how this pathway contributes to PD.

Results

We found that the imbalance of NTN-1 and DCC was a common feature of nigral DA neuron injury in PD mouse models. We investigated that MPP+ inhibited NTN-1 expression and increased DCC expression in a concentration- and time-dependent manner. We further discovered a significant decrease in plasma NTN-1 levels and a positive correlation with UPDRS scores in PD patients.

Conclusion

Our findings confirmed the imbalance of NTN-1/DCC signaling during nigral degeneration in experimental PD models and found for the first time a correlation of plasma NTN-1 with PD symptoms in patients.