术前化疗对胃癌组织上皮钙黏附素表达的影响

目的 :揭示上皮钙黏附素 (epithelialcadherin ,E cd)在化疗后的胃癌组织及癌旁组织中表达的变化 ,探讨术前化疗的意义。方法 :以 5 FU 15mg (kg·d)对进展期胃癌患者行术前化疗 ,术中取胃癌组织及癌旁组织 ,应用免疫组织化学法 (S P法 )检测E cd在 32例化疗后标本中的表达 ,与对照组 30例进行比较。结果 :5 FU术前化疗可明显提高E cd阳性表达率 (与对照组相比P <0 0 1)而且 5 FU >3 0组与 5 FU <3 0组之间差异有显著性 (P <0 0 2 5 ) ,在癌旁组织中 5 FU >3 0组与非化疗组之间差异有显著性 (P <0 0 2 5 ) ,而E cd在不同细胞分化及病期中表达差异无显著性。结论 :5 FU术前化疗可以提高胃癌组织及癌旁组织的E cd阳性表达水平 ,术前化疗可能减弱胃癌的侵袭转移性     

Regulatory mechanisms of osteoclast differentiation and function

Our understanding of the molecular mechanisms responsible for osteoclast generation, differentiation, and bone resorption have improved dramatically in recent years. In part, this has been due to studies in osteopetrosis, the disease characterized by impairment of osteoclast action, and to improved techniques for isolation of osteoclasts and their precursors. This review will discuss some of these mechanisms.This paper was presented at a satellite symposium of the 13th annual meeting of the Japanese Society for Bone and Mineral Research, sponsored by Asahi Chemical Co. Ltd. The subject of the symposium was differentiated function of the osteoclast.     

Validation of molecular targets in prostate cancer

As prostate cancer is not a single disease, it is important to identify the pivotal pathway in the patient being treated. The molecular environment is the site of current oncological research to define new therapeutic targets for hormone-refractory disease, offering the potential to eventually individualize treatment through stratification of pathways. Targets may be validated either phenotypically (e.g. androgen receptor, cadherin) or functionally (e.g. prostate cancer-specific genes). In addition, several other candidates are potentially suitable, while others await discovery. Important initial steps have been made in the search for prostate cancer stem cells; identifying stem cells and the stromal, hormonal, and other signalling molecules that influence their behaviour would have important implications for managing prostate cancer. Although individual therapeutic pathways might be ineffective in a particular molecular environment, combinations of approaches might be capable of producing synergistic effects. A multimodal approach thus might be the best solution. Determining where best to search for a molecular target, and validating whether the target is associated with a sufficiently aggressive malignant process to justify further study is difficult, but the potential benefits are enormous.     

Differential expression of p120 catenin in glial cells of the adult rat brain

p120 catenin (p120ctn) is involved in the regulation of cadherin-mediated adhesion and the dynamic organization of the actin cytoskeleton by modulating RhoGTPase activity. We have previously described the distribution of p120ctn during rat brain development and provided substantial evidence for the potential involvement of p120ctn in morphogenetic events and plasticity in the central nervous system. Here, we analyzed the cellular and ultrastructural distribution of p120ctn in glial cells of the adult rat forebrain. The highest intensity of immunostaining for p120ctn was found in cells of the choroid plexus and ependyma and was mainly restricted to the plasma membrane. However, p120ctn was almost absent from astrocytes. In contrast, in tanycytes, a particular glial cell exhibiting remarkable morphological plasticity, p120ctn, was localized at the plasma membrane and also in the cytoplasm. We show that a large subpopulation of oligodendrocytes expressed multiple isoforms, whereas other neural cells predominantly expressed isoform 1, and that p120ctn immunoreactivity was distributed through the cytoplasm and at certain portions of the plasma membrane. Finally, p120ctn was expressed by a small population of cortical NG2-expressing cells, whereas it was expressed by a large population of these cells in the white matter. However, in both regions, proliferating NG2-positive cells consistently expressed p120ctn. The expression of p120ctn by cells of the oligodendrocyte lineage suggests that p120ctn may participate in oligodendrogenesis and myelination. Moreover, the expression of p120ctn by various cell types and its differential subcellular distribution strongly suggest that p120ctn may serve multiple functions in the central nervous system.     

Hypermethylation of GSTP1, CD44, and E-cadherin genes in prostate cancer among US Blacks and Whites

BACKGROUND: In the US, the incidence and mortality of prostate cancer is about twofold higher among US Blacks compared to Whites, suggesting racial differences in prostate tumor occurrence and aggressiveness. The reason for these racial differences is unknown. Epigenetic events such as promoter-region gene hypermethylation may be influenced by environmental exposures and have been implicated in prostate carcinogenesis (by the silencing of tumor suppressors and other regulatory genes). METHODS: Using real-time methylation-sensitive PCR, we assessed differences in DNA hypermethylation of GSTP1, CD44, and E-cadherin (three genes thought to be important in the progression of prostate cancer) in archival tumor tissue of black (n = 47) and white men (n = 64). RESULTS: We found a high prevalence of GSTP1 hypermethylation overall (84%) but no differences by race (89 and 83% in black vs. white men, respectively), tumor stage, or grade. Although CD44 hypermethylation was less prevalent overall (found in 32% of tumors), we observed a 1.7-fold higher frequency among black men (43 vs. 25% in black vs. white men, P = 0.05) and a correlation with tumor grade (CD44 was hypermethylated in 10, 42, and 52% of well, moderate, and poorly differentiated tumors, respectively, P = 0.003) but not disease stage. The E-cadherin gene was not hypermethylated in any of the tumors. In summary, of the three genes examined, only CD44 hypermethylation differed by race and correlated with tumor grade, independent of race. CONCLUSIONS: These preliminary findings suggest that differences in gene promoter hypermethylation may potentially underlie racial differences in prostate cancer pathogenesis and should be explored in larger studies.     

Epigenetic and genetic alterations of APC and CDH1 genes in lobular breast cancer: relationships with abnormal E-cadherin and catenin expression and microsatellite instability

The causes and functional consequences of E-cadherin (E-CD) loss in breast cancer are poorly understood. E-CD loss might act in concert with alterations in the APC/beta-catenin pathway to permit oncogenic beta-catenin signaling. To test this hypothesis, we have analyzed the presence of genetic and epigenetic alterations affecting E-CD (CDH1), APC and beta-catenin (CTNNB1) genes and the immunohistochemical expression of E-CD, beta- and gamma-catenin in a series of 46 infiltrating lobular breast carcinomas (ILCs). Since 80% of ILCs featured complete loss of E-CD expression, we analyzed the molecular alterations responsible for E-CD inactivation in these tumors. We found that 10 of 46 (22%) cases harbored mutations in CDH1, including 1 case with 2 different mutations (1 of which was germline). CDH1 was also inactivated by loss of heterozygosity (LOH; 30/41, 73%) and promoter hypermethylation (19/46, 41%). Interestingly, LOH and mutations were also detected in the corresponding in situ lesions of the ILCs, implying that these alterations are early events in lobular cancer tumorogenesis. Additionally, the presence of a polymorphism in the CDH1 promoter was found to be inversely correlated with CDH1 mutations, but not with E-CD levels. We next examined whether alterations in the APC/beta-catenin pathway also occurred in the same series of ILCs. Although no CTNNB1 or APC mutations were detected, promoter methylation (25/46, 52%) and LOH (7/30, 23%) of APC were found. Moreover, methylation of APC and CDH1 occurred concordantly. However, beta- and gamma-catenin were severely reduced or absent in 90% of these tumors, implying that alterations in CDH1 and APC genes do not promote beta-catenin accumulation in ILC. These molecular alterations were not associated with microsatellite instability. In summary, several different mechanisms (mutations, LOH, methylation) are involved in the frequent CDH1 inactivation in invasive and in situ lobular breast cancer. The same tumors also show genetic and epigenetic alterations of APC gene. However, altered CDH1 and APC genes do not promote beta-catenin accumulation in this tumor type.     

Cyclic AMP inhibits TGFbeta1-induced cell-scattering and invasiveness in murine-transformed keratinocytes

Mouse-transformed keratinocytes cultured in the presence of transforming growth factor beta1 (TGF-beta1) acquire an array of morphologic and functional properties that give rise to a migratory phenotype that expresses mesenchymal molecular markers. This cellular conversion involves activation of the Ras-ERK pathway, enhancement of urokinase (uPA) and matrix metalloproteinase-9 (MMP-9) expression and induction of invasiveness. In our present work, we demonstrate that cAMP and forskolin are able to prevent the expression of these mesenchymal properties, probably due to blockade of the Ras-ERK pathway. Our results also show that cAMP and forskolin are able to abolish the TGF-beta1-induced reorganization of the actin cytoskeleton that is characteristic of the mesenchymal phenotype and also inhibits the disruption of the E-cadherin cell to cell interactions. The latter responses seem to depend on the activity of protein kinase A, as demonstrated by the activation of the Ras-ERK pathway by specific protein kinase A inhibitors.     

Overexpression of cadherins suppresses pulmonary metastasis of osteosarcoma in vivo

Osteosarcoma by nature shows aggressive pulmonary metastasis; however, the underlying molecular mechanisms remain unclear. We previously showed that N-cadherin and cadherin-11 (OB-cadherin), which are highly expressed in normal osteoblasts, are anomalously expressed in human osteosarcoma (Kashima et al., Am J Pathol 1999;155:1549-55). In the present study, we examined the role of cadherins in osteosarcoma metastasis using the mouse osteosarcoma cell line Dunn and its highly metastatic subline LM8. Oligonucleotide array and RT-PCR analyses demonstrated that Dunn and LM8 cells did not express appreciable levels of several members of the cadherin family, and Western blot analysis confirmed that Dunn and LM8 cells did not express P-cadherin, E-cadherin, N-cadherin or cadherin-11 protein. We therefore investigated the functional consequences of cadherin overexpression on cell migration and in vivo metastatic potential of LM8 cells. Several LM8 clones were isolated which expressed exogenous N-cadherin and cadherin-11 localized to the cell membrane and able to bind to beta-catenin. Overexpression of N-cadherin or cadherin-11 in LM8 cells did not affect cell proliferation but caused an inhibitory effect on cell migration in vitro. In vivo analysis showed that N-cadherin- and cadherin-11-overexpressing cells exhibited a marked reduction in their ability to form pulmonary metastases, with significant decreases in lung weight and the number and weight of metastatic lesions, as well as the size and weight of primary lesions at the s.c.-inoculated site. These observations demonstrate that disruption of N-cadherin- and cadherin-11-mediated cell-cell adhesion is critical in the pulmonary metastasis of osteosarcoma.