神经突起导向因子netrin-1及其受体与肿瘤发生

近年来的研究发现,netrin1和其受体基因在多种肿瘤中表达下调,未与配体netrin1结合的DCC和UNC5H能够诱导细胞凋亡,而在结合配体后则抑制细胞凋亡。在肿瘤细胞中凋亡通路通常被抑制,而且在50%以上的肿瘤中p53是失活的。netrin1与其受体结合后能完全抑制p53诱导的细胞凋亡;同时p53也直接调节netrin1及其受体基因的表达。因此,netrin1及其受体可能在肿瘤发生过程中发挥重要作用。     

miR-93与肿瘤的研究进展

研究表明microRNA与肿瘤的发生发展有着密切关系。其中,miR-93的差异表达在肿瘤细胞的增殖、凋亡、迁移、分化等方面发挥了重要作用。miR-93通过靶向调节PTEN、E2F1、Sixl等基因的表达促进肿瘤增殖,抑制细胞凋亡,增强肿瘤耐药;通过调节Smad7基因诱导肿瘤细胞发生上皮一间质转换,是一个潜在的癌基因。     

CIAPIN1基因的生物学功能及其与肿瘤的相关性

CIAPIN1是近年通过克隆表达方法鉴定的新基因,已证实其主要受细胞因子的调控,是Ras信号通路的重要介导者.CIAPIN1基因存在显著的细胞凋亡抑制效应,在肿瘤细胞中高表达,能抑制肿瘤细胞的凋亡和促进其细胞周期进程.进一步的研究还发现,CIAPIN1可促进肿瘤新生血管的形成和肿瘤多药抵抗的产生等.     

细胞凋亡抑制蛋白:肿瘤治疗的障碍与靶点

细胞凋亡抑制蛋白(inhibitor of apoptosis protein,IAP)主要通过结合并抑制细胞凋亡执行分子caspase蛋白家族而抑制细胞凋亡。肿瘤细胞高表达IAP是其获得抗凋亡特性的原因之一,成为肿瘤传统治疗(放疗,化疗等)的障碍。但特异的在肿瘤细胞内高表达而在正常细胞特别是高分化细胞中低表达或无表达也为肿瘤治疗提供了新靶点。干涉IAP分子在肿瘤细胞内的表达或功能已被作为肿瘤传统治疗方法的辅助治疗方法来研究。     

Caveolin-3是诊断横纹肌肉瘤敏感和特异性标记

Caveolin-3是细胞膜穴样凹陷膜结构域的主要结构蛋白。动物研究显示caveolin-3可在心肌细胞和骨骼肌细胞表达，但在其他细胞不表达。最近研究发现caveolin-3基因的异常与某些类型肌营养不良密切相关，而在caveolin-3转基因或敲除鼠中可见骨骼肌异常。这些结果表明caveolin-3在骨骼肌分化和功能中发挥重要的作用。     

细胞凋亡与肿瘤

细胞凋亡是一种细胞主动性死亡，与组织自稳机制有关。近年来，细胞凋亡在肿瘤发生发展过程中的生物学作用得到普遍重视。研究表明，不仅肿瘤细胞凋亡可受抗癌化疗、放疗等多种因素和途径诱导产生，而且某些肿瘤基因或肿瘤抑制基因，如ｂｃｌ┐２，ｐ５３等对细胞凋亡起重要调控作用     

基因Hath1表达对结肠癌细胞的抑制作用

目的研究Hath1基因对结肠癌细胞体外增殖的抑制作用。方法用trizol试剂提取肿瘤细胞总RNA,定量逆转录PCR法检测Hath1在结肠癌细胞和正常组织细胞中的表达;MTS和流式细胞仪法分别检测Hath1在结肠癌细胞中的增殖率和凋亡百分率;构建IEC-6稳定表达Hath1siRNA细胞系,检测Hath1siRNA对IEC-6细胞生长的影响。结果在正常人的小肠与结肠组织及大鼠小肠上皮细胞IEC-6中有着比较高水平的Hath1的表达,而在4株结肠癌细胞中Hath1的表达都很低。在表达Hath1的4株结肠癌细胞SW480、HT29、LS174T、SW620中,其细胞增殖率分别被抑制了38.5%、23.4%、55%、35.6%。在LS174T细胞中Hath1不能有效地诱导肿瘤细胞发生凋亡,但是可以显著地提高肿瘤细胞对化疗药物的敏感性。siRNA干扰试验进一步证明了Hath1起到肿瘤抑制基因的作用。结论 Hath1不能有效地诱导肿瘤细胞发生凋亡,但是可以显著地提高肿瘤细胞对化疗药物的敏感性。     

凋亡抑制蛋白LIVIN的研究与应用（文献综述）

凋亡抑制蛋白（IAP）家族首先由Crook等发现，是一类新的独立于B型淋巴瘤细胞因子2（Bcl-2）家族的抗凋亡蛋白。细胞凋亡是由多种因子介导的细胞主动死亡的过程，对机体或组织维持内环境的稳定和生物体的生长发育、生命周期、衰老死亡都有着重要的作用。凋亡抑制也是肿瘤发生的重要机制，凋亡通路的紊乱、促进凋亡因子的抑制、凋亡抑制因子过表达以及凋亡基因的表达失控都会导致肿瘤的发生、发展。而且，凋亡紊乱还导致肿瘤细胞对化疗药物的抵抗，在肿瘤的治疗过程中如何促进肿瘤细胞凋亡已经引起了人们极大的研究兴趣。     

肿瘤抑制基因与细胞凋亡

肿瘤抑制基因ｐ５３，Ｒｂ，ｐ１６，ｎｍ２３等参与调控肿瘤细胞等多种细胞的凋亡。它们既具有单一的调节作用，又具有复杂的协同效应。研究这些基因在细胞凋亡中的调控机制，对利用基因治疗技术治疗恶性肿瘤具有重要意义     

LKB1／STK11研究进展

LKB1 STK1 1基因是PJS患者的主要致病基因 ,为一种肿瘤抑制基因 ,编码一种功能未知的丝氨酸 苏氨酸蛋白激酶。LKB1基因的失活性表达以低频率事件广泛存在于全身多种肿瘤中 ,并在细胞生长抑制和p53依赖性细胞凋亡 ,以及胚胎和血管发育中具有重要作用     

Quantification of caveolin isoforms using quantitative real-time RT-PCR, and analysis of promoter CpG methylation of caveolin-1alpha in human T cell leukemia cell lines

Caveolin-1, an essential structural component of caveolae, functions as a negative regulator for signal transduction and has been suggested to be a candidate tumor suppressor. Lack of caveolin-1 expression has been implicated in the pathogenesis of oncogenic cell transformation and tumorigenesis in many cancers. On the other hand, over-expression has also been associated with tumor progression and metastasis in prostate cancers. Hence, alteration of caveolin-1 expression has been proposed as a clinical marker for diagnosis and prognosis in various cancers. For precise analyses of the caveolin expression in human T cell leukemia cell lines, we measured the mRNA levels of caveolin isoforms, caveolin-1alpha, -1beta, -2, and -3 with real-time RT-PCR using external standards for each isoform. In the panel of human T cell leukemia cell lines tested, four cell lines expressed caveolin-1alpha, -1beta and -2, but not -3, which was consistent with the protein levels. The expression profiles in most cell lines are caveolin-1alpha > caveolin-1beta > caveolin-2. Two cell lines did not express either of the caveolin mRNAs. Methylation analyses for the CpG sites in the promoter region of a positive and a negative cell line did not show a clear correlation with the expression status, suggesting that mechanisms other than CpG methylation are involved in the regulation of caveolin-1alpha expression in human T cell leukemia cell lines.     

Down-regulation of caveolin-1, a candidate tumor suppressor gene, in sarcomas

Caveolae are plasma membrane microdomains that have been implicated in the regulation of several intracellular signaling pathways. Previous studies suggest that caveolin-1, the main structural protein of caveolae, could function as a tumor suppressor. Caveolin-1 is highly expressed in terminally differentiated mesenchymal cells including adipocytes, endothelial cells, and smooth muscle cells. To study whether caveolin-1 is a possible tumor suppressor in human mesenchymal tumors, we have analyzed the expression using immunohistochemistry in normal mesenchymal tissues, 22 benign and 79 malignant mesenchymal tumors. Caveolin-1 was found to be expressed in fibromatoses, leiomyomas, hemangiomas, and lipomas at high levels comparable to normal mesenchymal tissues. The expression of caveolin-1 was slightly reduced in four of six well-differentiated liposarcomas and strongly reduced or lost in three of three fibrosarcomas, 17 of 20 leiomyosarcomas, 16 of 16 myxoid/round cell/pleomorphic liposarcomas, five of eight angiosarcomas, 15 of 18 malignant fibrous histiocytomas, and eight of eight synovial sarcomas. The immunohistochemical findings were confirmed by Western blot analysis in a number of tumors. High levels of both the 24-kd [alpha]- and the 21-kd [beta]-isoform of caveolin-1 were detected in the nontumorigenic human fibroblast cell line IMR-90. In contrast, in HT-1080 human fibrosarcoma cells, caveolin-1 is strongly down-regulated. We show that the [alpha]-isoform of caveolin-1 is potently up-regulated in HT-1080 cells by inhibition of the mitogen-activated protein kinase-signaling pathway with the specific inhibitor PD 98059, whereas the specific inhibitor of DNA methylation 5-aza-2'-deoxycytidine only marginally up-regulates caveolin-1. In addition, re-expression of caveolin-1 in HT-1080 fibrosarcoma cells potently inhibited colony formation. From these we conclude that caveolin-1 is likely to act as a tumor suppressor gene in human sarcomas.     

Up-regulated caveolin-1 accentuates the metastasis capability of lung adenocarcinoma by inducing filopodia formation

Caveolin-1, a 21- to 24-kd integral membrane protein, is primarily implicated as a tumor suppressor gene. Transformed cells normally contain reduced or no caveolin-1. Re-expression of caveolin-1 is found in advanced human and mouse prostate adenocarcinomas. To explore its potential role in tumorigenesis and tumor progression of human lung cancers, we used the well-characterized cell line (CL) series of lung adenocarcinoma cells with increasing cellular invasiveness to show that expression of caveolin-1 mRNA and protein was up-regulated with enhanced invasion/metastatic capability of CL cells. Reintroducing the caveolin-1 gene into the less invasive, caveolin-1-negative CL cells enhanced their invasive capability at least by twofold, as revealed by an in vitro chamber invasion assay. Thus, a correlation exists for both constitutive and induced expression of caveolin-1 in CL cells. Immunohistochemical examination of caveolin-1 was performed in 95 specimens obtained retrospectively from patients who had lung adenocarcinoma either with (35 patients) or without (60 patients) ipsilateral hilar/peribronchial tumor-metastasized lymph nodes. Caveolin-1 immunoreactivity was either totally absent or just barely detectable in a few lung adenocarcinoma cells from cases diagnosed as lung adenocarcinoma without regional lymph node metastasis. In contrast, increased caveolin-1 immunoreactivity both in number and intensity was detected in primary lung adenocarcinoma cells as well as in cancer cells that metastasized to regional lymph nodes from the cases diagnosed as advanced lung adenocarcinoma with nodal metastases. Multivariate analysis considering caveolin-1 immunoreactivity in addition to the established prognostic parameters such as pT stage, pN in these patients confirmed that caveolin-1 is an independent functional predictor of poor survival. We further revealed that up-regulated caveolin-1 in CL cells is necessary for mediating filopodia formation, which may enhance the invasive ability of lung adenocarcinoma cells.     

Caveolin-1 is down-regulated and inversely correlated with HER2 and EGFR expression status in invasive ductal carcinoma of the breast

AIMS: To evaluate the caveolin-1 status of invasive ductal carcinoma and its correlation with other important parameters of breast carcinogenesis. Caveolin-1, the main structural protein of caveolae, is involved in the regulation of several intracellular signalling pathways and also functions as a tumour suppressor in breast carcinogenesis. METHODS AND RESULTS: One hundred and thirty cases of invasive ductal carcinomas with matched normal breast tissue were evaluated immunohistochemically for caveolin-1 expression. Using a tissue microarray, caveolin-1 expression was also correlated with the expression of other antigens such as eostrogen receptor, progesterone receptor, epidermal growth factor receptor (EGFR), HER2, beta-catenin, E-cadherin, p53, Ki67 and with clinicopathological parameters. Immunohistochemical results showed strong expression of caveolin-1 in all normal breast epithelial cells, but a reduction of caveolin-1 expression in 56 cases (43.1%) of invasive ductal carcinoma. Furthermore, a statistically significant inverse correlation between caveolin-1 and EGFR and HER2 was noted (P < 0.001). CONCLUSIONS: Our results indicate a reduction in caveolin-1 expression in invasive ductal carcinoma of the breast, which supports in vitro studies of its role as a tumour suppressor. Caveolin-1 also shows an inverse correlation with EGFR and HER2, which fits with its function as a negative regulator of signal transduction.     

Increased expression of caveolin-1 and -2 in the hearts of Lewis rats with experimental autoimmune myocarditis

The expression of caveolin-1, -2 and -3 was studied in the hearts of rats with experimental autoimmune myocarditis (EAM), to elucidate the involvement of caveolins in the pathogenesis of EAM. Western blot analysis showed that levels of caveolin-1 and -2 were significantly increased in the hearts of rats with EAM on day 14 post-immunization (pi), as compared to the hearts of normal controls (p < 0.05, normal controls vs. EAM). Caveolin-3 is already at a high level in control animals, so it does not increase further.Immunohistochemistry showed that caveolin-1 was expressed mainly in ED1-positive macrophages and in some cardiomyocytes and vessels in the EAM lesions. Caveolin-2 was expressed constitutively in the vascular endothelial cells of normal hearts, and its expression was enhanced in EAM rats, as compared with the normal control group. Caveolin-3 was expressed constitutively in the plasma membranes of cardiomyocytes, but not in the vascular endothelial cells and inflammatory cells in the EAM lesions. Our results suggest that the expression of caveolin-1 and -2 is increased in EAM lesions and that the increased expression of caveolin-1 stimulates second signals in affected cells, such as macrophages and some cardiomyocytes, in EAM rats.     

Increased expression of caveolin-1 and -2 in the hearts of Lewis rats with experimental autoimmune myocarditis

The expression of caveolin-1, -2 and -3 was studied in the hearts of rats with experimental autoimmune myocarditis (EAM), to elucidate the involvement of caveolins in the pathogenesis of EAM. Western blot analysis showed that levels of caveolin-1 and -2 were significantly increased in the hearts of rats with EAM on day 14 post-immunization (pi), as compared to the hearts of normal controls (p < 0.05, normal controls vs. EAM). Caveolin-3 is already at a high level in control animals, so it does not increase further.

Immunohistochemistry showed that caveolin-1 was expressed mainly in ED1-positive macrophages and in some cardiomyocytes and vessels in the EAM lesions. Caveolin-2 was expressed constitutively in the vascular endothelial cells of normal hearts, and its expression was enhanced in EAM rats, as compared with the normal control group. Caveolin-3 was expressed constitutively in the plasma membranes of cardiomyocytes, but not in the vascular endothelial cells and inflammatory cells in the EAM lesions. Our results suggest that the expression of caveolin-1 and -2 is increased in EAM lesions and that the increased expression of caveolin-1 stimulates second signals in affected cells, such as macrophages and some cardiomyocytes, in EAM rats.     

Caveolin-1 expression in diffuse gliomas: correlation with the proliferation index, epidermal growth factor receptor, p53, and 1p/19q status

Caveolin-1 (cav-1) has been proposed as an immunohistochemical marker able to distinguish astroglial from oligodendroglial tumors. In addition, it has been suggested that the reduction of caveolin-1 expression in glioblastoma cells increases their proliferative and invasive potential. Accordingly, the present study investigates caveolin-1 immunoexpression and correlation with the 1p/19q status, histologic grade, proliferation index, epidermal growth factor receptor, and p53 expression in a series of 73 diffuse gliomas. A membranous and cytoplasmic immunolabeling for caveolin-1 was detected in neoplastic cells of 60% of cases. No significant differences in terms of caveolin-1 expression were observed between astrocytomas, oligodendrogliomas, and oligoastrocytomas. In addition, caveolin-1 expression was not correlated with 1p/19q status in oligodendrogliomas and mixed oligoastrocytomas. Caveolin-1 was expressed in most high-grade (World Health Organization III and IV) gliomas. Low caveolin-1 expression correlated with a higher Ki-67 labeling index and the absence of p53 overexpression in glioblastomas, and it was significantly associated with epidermal growth factor receptor overexpression in anaplastic astrocytomas. In conclusion, the present study indicates that caveolin-1 is not useful as diagnostic marker to differentiate grade II astrocytomas from oligodendrogliomas.     

Differential caveolin-1 expression in colon carcinoma and its relation to E-cadherin–β-catenin complex

BackgroundColorectal cancer is the third common cancer and the second leading cause of cancer-related death in the Western world. Caveolin-1 is a new emerging prognostic marker and has different expression abilities in different cancers. The expression of caveolin-1 in colon carcinogenesis is still confusing. E-cadherin and β-catenin have a definite role in invasion and progression. Our study is designed to explore the role of caveolin-1 in cancer colon carcinogenesis and tries to elucidate the relation between its expression and E-cadherin and β-catenin expression in colon cancer.Materials and methodsA total of 70 formalin-fixed, paraffin-embedded colon carcinoma specimens were studied for the expression of the 3 proteins, and a correlative study was done between each protein and different clinicopathologic parameters and between the 3 markers.ResultsAs the tumor becomes more aggressive and invasive and as it metastasizes, it losses the stromal caveolin-1 and E-cadherin and gains the cellular caveolin-1 and the abnormal β-catenin expression. Also, there were parallel changes between stromal caveolin-1 and E-cadherin on one side and between the cellular caveolin-1 and β-catenin on another side.ConclusionsOur findings link caveolin-1 to the power of infiltration and spread, aggressiveness, and differentiation of cancer colon, and this may be happen through E-cadherin–β-catenin complex.