核糖核酸酶的抗肿瘤研究进展

核糖核酸酶〔ribonuclease ,RNase〕是一类能够特异性切割RNA的酶 ,既有催化活性 ,又有细胞毒性。它们的生物学活性由激动剂和抑制剂所控制。迄今为止 ,已分离纯化出多种不同种类的RNase ,并对其结构和功能进行了深入的研究。研究表明 ,其中BS RNase、Onconase和RC RNase等具有抗肿瘤作用 ,可作为细胞毒素进入肿瘤细胞 ,抑制肿瘤细胞的生长 ,因此RNase的研究为临床治疗肿瘤提供了新的前景 ,有望成为一类新型的抗肿瘤药物     

反义寡核苷酸作用机制研究进展

近年来 ,由于多种化学修饰的反义寡核苷酸的出现 ,其作用机制已经不仅仅是诱导 RNase H的切割机制 ,多种核酸酶能被修饰的反义寡核苷酸诱导 ,如双链 RNase,RNase P,RNase L 等 ,而且利用反义寡核苷酸可以干扰 m RNA的代谢过程中加帽 ,剪接 ,翻译起始和延长等步骤。随着对反义寡核苷酸作用的分子机制研究的深入 ,会使它有更为广阔的应用前景     

血管生长素与血管生成

血管生长素 (ANG)属于RNase超家族 ,是唯一具有核糖核酸酶活性的血管生成因子。它可通过促进基膜的降解 ,促进内皮细胞增殖、迁移、粘附等作用来促进血管生成。ANG在多种肿瘤中表达增高。在糖尿病、外周动脉阻塞性疾病中其表达水平亦有升高     

表达HPV16 L1、L2和E7蛋白的非复制重组痘苗病毒诱发的抗肿瘤免疫反应

目的:评价表达HPV16 L1、L2E7的非复制重组痘苗病毒疫苗的抗肿瘤免疫反应.方法:采用肿瘤预防、肿瘤治疗和肿瘤切除等方法,观察疫苗NTVJL1/L2E7的抗肿瘤效果,用酶联免疫斑点(ELISPOT)和CTL检测该疫苗在小鼠体内诱发的细胞免疫应答.结果:在肿瘤预防和肿瘤治疗试验中,疫苗可以分别使60%和50%的小鼠免受HPV16阳性的治疗细胞攻击,肿瘤切除试验中,疫苗可以使70%的小鼠免于肿瘤复发,与对照组之间的差异具有显著性.ELISPOT和CTL均检测出强的特异性细胞免疫水平.结论:NTVJL1/L2E7能够在小鼠体内诱发出理想的抗肿瘤免疫反应,可以作为防治宫颈癌的候选疫苗.     

人卵巢癌相关自然反义转录子的系统筛选

目的 高通量地筛选人卵巢癌相关的自然反义转录子,为深入研究自然反义转录子在卵巢癌发生、发展中的作用奠定基础.方法 以人正常卵巢组织和卵巢癌组织为材料,用RNase Ⅰ保护分析法分离出两种组织中的正-反义转录子双链RNA,经逆转录后用抑制性消减杂交特异性扩增两种组织间的差异片段,最后对差异片段克隆、测序.结果 分离出的两种组织的正-反义转录子经克隆和鉴定后,共获得20个测序结果,其中有3个分子与卵巢癌等肿瘤可能密切相关,说明该方法可用于肿瘤相关NAT分子的系统筛选,并为深入研究卵巢癌相关NAT分子提供了靶标.     

M1RNA在基因治疗中的研究进展

E.coli RNase P复合体的 M1RNA亚单位是一类具有催化活性的核酶 ,它切割 t RNA前体分子 (pre-t RNA)的 5′端前导序列 ,产生成熟的 t RNA分子。M1RNA主要通过结构特异性识别底物 ,不需要底物有特定的序列 ,从而可设计修饰过的核酶来抑制靶基因的表达。在消除染色体易位产生的肿瘤相关畸形染色体上 ,M1RNA是一种理想的工具。研究表明 M1RNA作为一种新型核酶有着广阔的应用前景和极大的临床价值     

小剂量美法仑治愈荷瘤小鼠过程中外周血细胞计数的变化及其意义

目的: 观察在小剂量美法仑治愈荷瘤C57BL/6小鼠过程中外周血细胞计数的变化与肿瘤结节缩小之间的关系, 为进一步研究化疗治愈肿瘤的作用机制奠定基础.方法: 野生型C57BL/6小鼠皮下接种小鼠淋巴瘤EL4 细胞, 建立荷EL4 肿瘤的小鼠模型.肿瘤接种后12 d, 12只荷瘤小鼠随机分成2组, 7.5 mg/kg美法仑单次腹腔内注射, 等量生理盐水对照.观察荷瘤小鼠肿瘤结节直径的变化.用药组小鼠分别在7.5 mg/kg美法仑治疗前3 d、治疗后6 h、治疗后第4、 7、 11、 15、 28天内眦静脉取血, 进行血常规检测, 分析荷瘤小鼠外周血象与荷瘤小鼠肿瘤结节缩小之间的相关性.结果: 7.5 mg/kg美法仑治疗后, 荷瘤小鼠肿瘤消退;而对照组荷瘤小鼠肿瘤继续生长.美法仑治疗后6 h外周血白细胞为(10.6±2.3)×109/L, 与治疗前(9.8±0.32)×109/L比较差异无统计学意义(P>0.05);治疗后第4天外周血白细胞降为(2.9±0.97)×109/L, 与治疗前比较差异具统计学意义(P<0.01), 随后尽管白细胞数有所回升, 但在治疗后第28天仍明显低于化疗前水平(P<0.01).Hb含量在美法仑治疗后6 h由化疗前的(132±7) g/L降为(110±14) g/L(P<0.05), 随后Hb含量持续降低, 治疗后第7天达最低点(96±5) g/L, 以后逐渐升高, 治疗后15 d恢复至化疗前水平.用药后6 h荷瘤小鼠血小板计数升至(1502±142)×109/L, 与用药前(914±322)×109/L比较差异具有统计学意义(P<0.01), 随后1周内一直维持在高水平, 治疗后第11天血小板恢复至化疗前水平.结论: 美法仑在使荷瘤小鼠的肿瘤结节缩小的同时可引起外周血白细胞数和血红蛋白浓度的降低, 但对血小板无抑制作用.美法仑化疗后1周内血小板计数的增加可能与美法仑的抗肿瘤作用有关.     

肿瘤患者外周血中抑制性受体LAIR-1表达升高

目的:研究LAIR-1在肿瘤患者中的表达,探讨其在抗肿瘤免疫应答中的作用.方法:应用夹心ELISA检测肿瘤患者血清中可溶型sLAIR-1的水平;应用免疫荧光染色和流式细胞术分析,观察LAIR-1在患者PBMC中NK细胞、CD4 T细胞、CD8 T细胞和B细胞上的表达.结果:肿瘤患者血清sLAIR-1水平为(4.6±3.2) μg/ L,明显高于正常人血清sLAIR-1 水平(3.9±3.0) μg/L,P<0.05.NK细胞,CD4 T细胞及CD8 T细胞表达LAIR-1水平上调.肺癌患者CD4/CD8比值明显低于正常人,B细胞百分率明显高于正常人.NK细胞、CD4 T细胞CD8 T细胞中LAIR-1的表达阳性率高于对照组.结论:在肿瘤患者LAIR-1分子表达水平高于正常人.肿瘤患者抑制性受体LAIR-1 表达水平的上调可能与肿瘤的免疫逃逸有关.     

耐核糖核酸酶内含HCV RNA病毒样颗粒的表达

目的 构建可以表达耐核糖核酸酶(RNase)的内含HCV RNA病毒样颗粒的载体质粒。方法 将表达载体pI NCCL用Hind Ⅲ酶切后，与用相同内切酶酶切的HCV RNA非编码区(5′-UTR)扩增产物，在T4 DNA连接酶的存在下连接，构建一新的表达载体pI NCCL-HCV RNA 5′-UTR，再转化BL21-DE3 E．coli进行原核表达。结果 成功构建得到了新的表达载体pI NCCL-HCV RNA5′-UTR，经原核表达为耐RNase的内含HCV RNA病毒样颗粒。结论 得到的pI NCCL-HCV RNA 5′-UTR表达载体及原核表达系统，可作为一个耐RNase的HCV RNA标准品和质控品的构建和制备表达载体平台。     

免疫共刺激分子CD40在肿瘤临床治疗中的应用

共刺激分子CD40/TNFRSF5隶属肿瘤坏死因子受体超家族,在机体固有免疫应答及适应性免疫应答中均发挥关键作用.CD40生理性表达于专职性抗原提呈细胞、内皮细胞等细胞表面,是T细胞表面CD40L分子的天然糖蛋白受体.CD40-CD40L信号通路的激活参与T淋巴细胞活化、抗体类别转换、抗原提呈细胞激活等一系列免疫相关生物学过程.除免疫细胞等生理性表达外,CD40在血源性及上皮源性恶性肿瘤细胞表面亦存在表达,并通过直接影响肿瘤细胞或间接干预肿瘤微环境参与肿瘤的发生、发展.大量研究表明,CD40激动型抗体可能通过激活宿主抗肿瘤免疫应答或直接促进CD40肿瘤细胞凋亡等途径正向干预实体肿瘤进展,提示CD40可能作为有效的肿瘤免疫治疗靶点.现对CD40分子在肿瘤发生、发展中的生物学作用及CD40-CD40L通路在肿瘤免疫治疗中的应用进展及存在问题予以综述.     

The influence of CD95L expression on tumor rejection in mice

Many tumors express the death ligand CD95L (CD178, APO-1L, FasL) and can kill activated T cells in vitro. This may enable the tumor cells to suppress anti-tumor immune responses, a phenomenon called "tumor counterattack". Preliminary evidence of tumor counterattack in human tumors exists. However, CD95L-expressing tumors are rapidly rejected in mice. In order to clarify this controversial situation we investigated whether the level or the time point of CD95L expression might be critical factors determining tumor counterattack versus tumor rejection. We generated CD95-resistant tumor cell lines expressing different levels of CD95L (LKC-CD95L). In nude mice the CD95L expression level had no influence on the growth of the CD95L(+) tumors. In contrast, a CD95L(-) control tumor cell line (LKC) grew much faster. In addition, we generated a CD95-resistant cell line in which CD95L was induced via the tet system (LKCR-tetCD95L). Induction of CD95Lin established tumors in nude and NOD/SCID mice led to rapid rejection of the tumors. Induction of lower CD95L expression levels delayed tumor rejection only marginally. These results demonstrate that rejection of CD95L-expressing tumors in mice is not a result of overexpression and does not depend on the presence of CD95L at the onset of tumor progression.     

Expression of genes involved with cell cycle control, cell growth and chromatin modification are altered in hepatoblastomas

Hepatoblastoma is a rare pediatric liver tumor. While much progress has been made in the treatment of the disease, very little is known about the moleculer events underlying the pathogenesis of this disease. We sought to investigate a series of hepatoblastomas for alterations in gene expression patterns with emphasis on important cell regulatory genes, including chromatin modifying enzymes, cyclin dependent kinase inhibitors, growth factors, oncogenes and cell cycle regulators. Total RNA was extracted from a series of sporadic hepatoblastomas with matched normal liver, some unmatched tumors and fetal livers, and gene expression was measured for various genes using RNase Protection Analysis (RPA). The results of this analysis show that the expression of many important regulatory genes are distinctly altered in these tumors, and a subset of tumors can be distinguished on the basis of these gene expression differences and histopathological features. Because the molecular events underlying the pathogenesis of this rare tumor are so poorly understood, this study represents a first step in determining some of the possible mechanisms involved which may provide future avenues of research.     

Skin allograft rejection is suppressed in mice lacking the antiviral enzyme, 2',5'-oligoadenylate-dependent RNase L

The 2-5A/RNase L system is a regulated RNA decay pathway that mediates some of the antiviral and tumor suppressor activities of the interferons. Previously, we demonstrated that RNase L-null mice have increased susceptibility to viral infections and are partially deficient in induced and spontaneous apoptosis. To determine if RNase L functions in cellular, as well as innate, immunity, skin allograft rejection and contact hypersensitivity (CHS) experiments were performed in RNase L+/+ and RNase L-/- mice. Although no consistent alterations in CHS were found, we did observe a delay of 5 days in the acute rejection of class II major histocompatibility complex (MHC) disparate skin allografts in mice lacking RNase L. Accordingly, histologic examinations of the allografts harvested from RNase L-/- mice revealed a dramatic reduction in inflammatory infiltrates, suggesting a delay in T-cell priming or a deficiency in immune cell trafficking. Results consistent with a proinflammatory role for RNase L extend the known functions of the 2-5A/RNase L system beyond innate immunity into some, but not all, types of cellular immunity.     

Expression of l1 cell adhesion molecule and morphologic features at the invasive front of colorectal cancer

To obtain the correlation between morphologic features in the invasive fronts of colorectal cancer (CRC) and L1 cell adhesion molecule (L1CAM) expression, 275 CRCs were assessed with L1CAM immunostaining and 29 CRCs were examined for L1CAM messenger RNA (mRNA) expression. Based on immunostaining, the positive rate of L1CAM expression increased according to the grade of tumor budding (P = .0002) and solid cancer nests (SCNs; P = .0046). L1CAM mRNA levels at the invasive front of the tumor were higher than those at the center of the tumor (median, 3.7-fold). The gap of L1CAM mRNA level between the invasive front and the central area was 7.3-fold in tumors having SCN lesions, whereas it was 1.9-fold in tumors having non-SCN lesions (P = .0004). L1CAM expression was correlated with nodal involvement in protein and mRNA levels (P = .0007 and P = .036, respectively). Tumor regulation of L1CAM expression is associated with morphologic features at the invasive front in CRC.     

Depleting ABCE1 expression induces apoptosis and inhibits the ability of proliferation and migration of human esophageal carcinoma cells

Objective: This study aims to explore the clinical characteristics of ABCE1 in esophageal cancers and its roles in the proliferation, invasiveness, migration and apoptosis of the esophageal carcinoma Eca109 cell line. Methods: The expression of ABCE1 and its target protein-RNase L, were first studied in tumor tissues of esophageal carcinoma and adjacent non-tumor tissues. The siRNA green fluorescent protein (GFP) expression vector of ABCE1 was prepared and transfected into the esophageal carcinoma Eca109 cells, then the fluorescence microscope was used to study the transfection efficiency. The MTT assay, cell invasion, the transwell and scratch assay were used to study cell proliferation and migration activity; the apoptosis rate was tested by flow cytometry. Western blot and RT-PCR assay were adopted to measure their silencing efficacy. Results: ABCE1 expression is low in the adjacent non-tumor tissues while the expression is high in the esophageal carcinoma; the expression is reversely proportional to the differentiation degrees. The expression of RNase L was in contrary to ABCE1. After transfected with ABCE1-siRNA, the proliferation, invasiveness and migration capabilities of cells decreased significantly whilst the apoptosis rate enhanced greatly (P<0.01). Meanwhile, the expression of ABCE1 in Eca109 cells was blocked (P<0.01) while the expression of RNase L increased significantly (P<0.01). Conclusion: ABCE1 is closely connected with the pathogenesis and development of esophageal carcinoma, which act through the cellular pathways of 2-5A/RNase L.     

L1 cell adhesion molecule as a predictor for recurrence in pulmonary carcinoids and large‐cell neuroendocrine tumors

Pulmonary neuroendocrine tumors are a distinct subset of neoplasms with indolent to aggressive behavior. This study was conducted to evaluate the prognostic role of L1 cell adhesion molecule (L1CAM) in pulmonary neuroendocrine tumors. We retrospectively analyzed L1 expression in 55 cases of completely resected carcinoids and large‐cell neuroendocrine carcinomas, by the immunohistochemistry with monoclonal antibody A10‐A3 against human L1. L1 immunoreactivity was detected in 34 (61.8%) of 55 specimens. There was a significant correlation between L1 expression and the World Health Organization classification of this tumor (Spearman rank correlation, ρ=0.60, p<0.001). With median follow‐up of 52.0 months, the 5‐year survival rate for patients with low expression of L1 (<20% of tumor cells stained) was significantly better compared with those with high expression of L1 (82.6% vs. 43.7%, p=0.005). L1 was also a significant independent predictor of disease‐free survival, and patients with high L1 expression have a higher risk for recurrence compared with those with low L1 expression (hazard ratio, 3.0; 95% confidence interval, 1.2–8.3; p=0.034). L1 expression is significantly associated with aggressiveness and further studies with larger samples are needed to validate potential prognostic value for pulmonary neuroendocrine tumors.     

Immunohistochemical demonstration of ribonuclease and amylase in normal and neoplastic parotid glands

Antibodies specific for bovine ribonuclease A (antiRNase A) were raised in rabbits, and immunologic cross-reactivity between bovine RNase A and human salivary gland RNase was demonstrated. The antiRNase A served as the primary antibody in the peroxidase-antiperoxidase immunohistochemical technique. Paraffin blocks of five normal human parotids and 20 parotid tumors were examined. In normal parotid and in cases of cystadenoma lymphomatosum, immunoreactive RNase was localized in the ductal epithelium, evidence of the ductal cell origin of these benign tumors. RNase immunoreactivity was noted in the adenomatous structures and in cells isolated in the myxoid matrix of pleomorphic adenomas, which supports recent evidence of an epithelial origin of these tumors. Malignant acinar cells of acinic cell carcinoma were strongly positive for immunoreactive RNase, while acinar cells of normal parotid were uniformly negative. This expression of the gene for RNase A probably represents a loss of differentiation (i.e., control) of the neoplastic acinar cells. Further evidence for this hypothesis was obtained by treating these tumors with an antihuman salivary amylase antibody, which is localized in normal acinar cells. No immunoreactive amylase was observed. The results support the idea that immunoreactivity need not accompany enzyme activity, as the presence of immunoreactive RNase was noted in all neoplastic tissues examined. Immunohistochemical localization of two antigens in the same tissue demonstrates the varied biochemical changes associated with parotid neoplasia.     

L1 (CD171) is highly expressed in gastrointestinal stromal tumors.

The treatment strategy for mesenchymal tumors of the gastrointestinal tract is based upon typing of the tumor. Especially differential diagnosis of gastrointestinal stromal tumors (GISTs) to leiomyomas is crucial for determining radicality of surgery. L1 cell adhesion molecule (CD171) plays an essential role in tumor progression. The aim of this study was to determine expression of L1 in GISTs, smooth muscle tumors, desmoid-type fibromatosis and peripheral nerve sheath tumors (PNSTs). We retrospectively analyzed a total of 129 surgically resected primary tumors or metastases of 72 GISTs, 29 smooth muscle tumors, seven PNSTs and 21 desmoid-type fibromatosis by immunohistochemistry for c-kit, CD34, smooth muscle actin, desmin, vimentin, S-100 and L1 expression. L1 expression was detected in 53 (74%) of 72 GISTs but in none of 29 smooth muscle tumors or 21 desmoid-type fibromatosis (P<0.01 by Fisher's test). In all, four (57%) of seven peripheral nerve sheath tumors were L1-positive. Survival analysis of 55 surgically completely resected GISTs presenting without metastasis at initial diagnosis revealed no tumor-specific death among L1-negative patients (P=0.13 by log-rank test; median follow-up time 41 months) and one recurrence was observed (P=0.12). Interestingly high levels of L1 were seen in tumor vascular endothelial cells of smooth muscle tumors and PNSTs, but not in GISTs. Our data show that L1 is highly expressed in GISTs but not in smooth muscle tumors and desmoid-type fibromatosis being important differential diagnoses. The trend towards a reduced survival of L1-positive patients in this study has to be further evaluated in future trials with higher patient numbers.