Evidence for Tumour Suppressor Function of DOK7 in Human Breast Cancer

Introduction: Downstream of tyrosine kinase 7 (DOK-7) is a member of the DOK family, which has been associated with the development and progression of various humancancers. Previously, identification of CpG hypermethylation in DOK-7 promoter was identified in breast cancer. Method: DOK-7 mRNA extraction and reverse transcription were performed on fresh frozen breast cancer tissue samples and normal background breast tissue. Transcript levels of expression were analyzed against TNM stage, tumour grade and clinical outcome over a 10-year follow-up period. Results: Levels of DOK-7 expression decreased significantly with increasing TNM stage. Higher DOK-7 expression was correlated with longer disease free and overall survival times. Conclusion: To our knowledge, this is the first study to investigate DOK-7 expression in human breast cancer. We identify a potential DOK-7 tumour suppressor role. DOK-7 as a prognostic biomarker in human breast cancer should be included in future validation studies.

Role of p53 suppression in the pathogenesis of hepatocellular carcinoma

In the world,hepatocellular carcinoma(HCC)is among the top 10 most prevalent malignancies.HCC formation has indeed been linked to numerous etiological factors,including alcohol usage,hepatitis viruses and liver cirrhosis.Among the most prevalent defects in a wide range of tumours,notably HCC,is the silencing of the p53 tumour suppressor gene.The control of the cell cycle and the preservation of gene function are both critically important functions of p53.In order to pinpoint the core mechanisms of HCC and find more efficient treatments,molecular research employing HCC tissues has been the main focus.Stimulated p53 triggers necessary reactions that achieve cell cycle arrest,genetic stability,DNA repair and the elimination of DNA-damaged cells’responses to biological stressors(like oncogenes or DNA damage).To the contrary hand,the oncogene protein of the murine double minute 2(MDM2)is a significant biological inhibitor of p53.MDM2 causes p53 protein degradation,which in turn adversely controls p53 function.Despite carrying wt-p53,the majority of HCCs show abnormalities in the p53-expressed apoptotic pathway.High p53 in-vivo expression might have two clinical impacts on HCC:(1)Increased levels of exogenous p53 protein cause tumour cells to undergo apoptosis by preventing cell growth through a number of biological pathways;and(2)Exogenous p53 makes HCC susceptible to various anticancer drugs.This review describes the functions and primary mechanisms of p53 in pathological mechanism,chemoresistance and therapeutic mechanisms of HCC.

miR-139在结直肠癌组织中的表达及其对癌细胞生长的影响

目的探讨miR-139在结直肠癌组织中的表达以及上调miR-139表达对结直肠癌细胞生长的影响。方法应用实时定量PCR法检测miR-139在20例大肠癌组织及癌旁组织中的表达,HT29细胞转染miR-139 mimics后,通过MTT、Softagar方法检测miR-139对大肠癌细胞增殖的影响;Transwell实验检测miR-139对大肠癌细胞迁移和侵袭的影响。结果 miR-139在结直肠癌组织中表达量明显低于癌旁组织(P<0.01)。转染miR-139 mimics的HT29 MTT实验中第1天至第5天的吸光度(OD)值与对照组相比显著减低。Softagar实验中计数对照组每个视野(41±5),miR-139每个视野(72±5),差异有统计学意义(P<0.01)。Transwell小室实验显示,与阴性对照相比,转染miR-139 mimics后,HT29细胞的迁移及侵袭能力明显下降。结论 miR-139在结直肠癌组织中低表达,miR-139表达上调可抑制HT29生长、迁移及侵袭能力,miR-139有潜在抑癌作用。

MicroRNAs, development of Barrett’s esophagus, and progression to esophageal adenocarcinoma

Barrett's esophagus is a premalignant condition caused by gastroesophageal reflux. Once developed, it can progress through varying grades of dysplasia to esoph-ageal adenocarcinoma. Whilst it is well accepted that Barrett's esophagus is caused by gastroesophageal reflux, the molecular mechanisms of its pathogenesis and progression to cancer remain unclear. MicroRNAs (miRNAs) are short segments of RNA that have been shown to control the expression of many human genes. They have been implicated in most cellular processes, and the role of miRNAs in disease development is be-coming increasingly evident. Understanding altered miRNA expression is likely to help unravel the molecular mechanisms that underpin the development of Barrett's esophagus and its progression to cancer.

吸烟与非吸烟肺癌患者中P53基因突变的检测

Ｐ５３基因定位于人类第１７号染色体的短臂，野生型Ｐ５３基因是肿瘤抑制基因。这一基因正成为研究人类肿瘤ＤＮＡ的主要目标。作者运用聚合酶链反应－单链构象多态性技术（ＰＣＲ－ＳＳＣＰ），研究了４５例石蜡包埋的肺癌组织标本中肿瘤抑制基因Ｐ５３基因突变，结果发现在Ｐ５３基因的第５～８外显子中共检测到１９例Ｐ５３基因突变的样本，检出率为４２．２％，并且发现吸烟的肺癌患者中Ｐ５３基因突变的检出频率明显高于非吸烟的肺癌患者。

PCR－SSCP银染法检测胃和结、直肠癌APC基因突变

目的：探讨国人胃癌和结、直肠癌的ＡＰＣ基因突变情况。方法：采用ＰＣＲ－ＳＳＣＰ银染技术，分析了１４例胃癌和１４例散发性结、直肠癌的ＡＰＣ基因第１５外显子第６段和第７段的突变情况。结果：１４份结直肠癌原发灶样品中有１份ＡＰＣ基因第１５外显子第７段出现异常电泳条带，而１４份胃癌及其６份胃癌转移性淋巴结样品中却未观察到ＡＰＣ基因的异常电泳条带。结论：本组胃癌及淋巴结转移灶中未发现ＡＰＣ基因突变，而结、直肠癌的ＡＰＣ基因突变率为７％。

细胞融合对肿瘤细胞转移能力的影响

利用基因转移技术，将新霉素抗性质粒ＰＳＶ２ｎｅｏ转入正常小鼠脾细胞，然后用ＰＥＧ促融，使其与具高转移力人肺巨细胞癌细胞系ＰＬＡ８０ｌ－Ｄ９５细胞融合，经Ｇ４１８筛选后获得１个无转移力克隆细胞系ＰＭＳ－２。染色体分析和以新霉素抗性基因为探针的ＤＮＡ－ＤＮＡ斑点杂交均证实，ＰＭＳ－２为杂种细胞克隆。裸鼠接种亲代肿瘤细胞３×１０６个细胞／只可发生明显的肺及淋巴结等脏器转移，接种ＰＭＳ－２７×１０６个细胞／只后仅能形成有完整包膜的肿瘤结节，无转移灶产生。此外，细胞的一般特性、生长速度、３Ｈ－ＴｄＲ参入率等也有明显的改变。提示正常小鼠脾细胞与肿瘤细胞融合后表现出的肿瘤转移能力抑制，可能由肿瘤转移抑制基因控制或其他水平干预所致。

Review:Mechanisms of inherited cancer susceptibility

A small proportion of many cancers are due to inherited mutations in genes,which result in a high risk to the indi-vidual of developing specific cancers. There are several classes of genes that may be involved: tumour suppressor genes,onco-genes,genes encoding proteins involved in DNA repair and cell cycle control,and genes involved in stimulating the angiogenic pathway. Alterations in susceptibility to cancer may also be due to variations in genes involved in carcinogen metabolism. This review discusses examples of some of these genes and the associated clinical conditions caused by the inheritance of mutations in such genes.

癌细胞侵袭和转移的基因生物学

癌的转移(metastasis)是个极为复杂的过程。首先,转移性癌细胞必须从原发灶脱离出来,然后穿越血管壁,进入血流或淋巴液,此时要逃逸机体细胞免疫与体液免疫的攻击,然后穿出血管,到达靶细胞定居下来,接着增殖而形成继发瘤灶。因此痛细胞侵袭和转移与多种因子有关。事实上,这些都有其分子基础。近年来有关肿瘤转移与侵袭分子生物学研究进展很快,内容丰富。本文就癌细胞转移的分子生物学作一简要综述,包括癌基因、抑癌基因、肿瘤转移相关基因。

散发性结直肠癌组织APC突变的研究

目的结、直肠癌为我国常见的消化道恶性肿瘤,与多个癌基因激活及抑癌基因的失活密切相关,本文旨在探讨中国人散发性结、直肠癌与 APC 突变的关系。方法应用银染 PCR-SSCP 检测41例中国人散发性结、直肠癌 APC 突变。结果 41例患者中,APC 突变16例,占39.0%,其中高分化腺癌8/13例(61.5%).中分化腺癌5/17例(29.4%),低分化腺癌3/11例(27.3%,0.01<P<0.05)。Dukes'分期与 APC 突变的关系:A 期4/13例(30.8%).B 期6/16例(37.5%).C 期3/7例(42.9%),D 期3/5例(60.0%,P>0.05)。伴淋巴结转换 APC 突变率6/12例(50.0%),无淋巴结转换10/29例(34.5%.P>0.05)。CEA 升高 APC 突变率4/8例(50.0%),CEA 正常 APC 突变率12/33例(36.4%,P>0.05)。结论 APC 基因突变为散发性结、直肠癌常见变化基因事件,组织学上多见于分化较好的肿瘤,与肿瘤的临床分期、血清 CEA 水平及有无淋巴结转换无关。

Aberrant Expression of Notch1 in Cervical Cancer

OBJECTIVE To investigate the putative role of the Notch1 receptor in cervical cancer carcinogenesis and progression. METHODS The expression of the Notch1 protein was analyzed by a Western-blotting approach in 40 cervical cancer and 30 normal cervical tissues. Some tissues were examined using RT-PCR to determine mRNA levels. Celluar localization of the Notch1 protein in the paraffin-embedded cervical tissues was also analyzed by immunohistochemistry. RESULTS The Notch1 protein was detected in all 30 normal cervical tissues. In contrast, only 6 samples of 40 cervical cancer tissues showed Notch1 expression. The level of the Notch1 protein expression was significantly lower in cervical cancer tissues than that in normal tissue samples. In agreement with these observations, levels of Notch1 mRNA were found to be substantially down-regulated in cervical cancer tissues. In the immunohistochemistry staining assay, the Notch1 protein was shown to localize predominantly in the cytoplasm and nucleoli of the normal cervical squamous epithelium of the cervix, but no staining was observed in the cervical cancer cells. Notch1 expression was observed to correlate with the clinical disease stage, but there were no correlations with age, tumor size, grade or lymph node metastasis （P〉0.05）. The levels of Notch1 protein expression were significantly higher in early stages （Ⅰ-Ⅱa, 66.7%） compared to those in the advanced stages （Ⅱb～Ⅳ,12.6%）（P=0.001）. CONCLUSION Notch1 may play a role as a tumor suppressor in cervical tumorigenesis. Determination of Notch1 expression may be helpful for preoperative diagnosis and accuracy of staging. But its clinical use for cervical cancer requires further investigation.

ING1基因的生物功能及研究进展

ING1为新近认识的抑癌基因。功能研究发现ING1基因的产物：P33^AsupING 1b^A参与细胞生长和增殖的抑制、凋亡、肿瘤非靶位独立生长、细胞衰老、基因稳定性的维持和细胞周期校验点的调节。认为其P33^AsupING 1b^A表达从细胞核转移至细胞浆可能引起正常蛋白功能丧失。对于一些肿瘤的进展、发展和发生机制来说这个可能起到一个非常关键的作用。

人肝细胞癌中PTEN基因的DNA杂交及突变分析

目的 研究人肝细胞癌中ＰＴＥＮ基因缺失及第５、第８外显子突变。方法 应用Ｓｏｕｔｈｅｒｎ杂交检测人肝细胞癌中ＰＴＥＮ基因限制性片段长度多态性和纯合性缺失、半合性缺失、片段缺失。应用聚合酶链单链构象多态性（ＰＣＲＳＳＣＰ）检查ＰＴＥＮ基因的第５、第８外显子的突变。结果 Ｓｏｕｔｈｅｒｎ杂交结果显示，所有３４例肝细胞癌中ＰＴＥＮ基因未见限制性片段长度多态性或纯合性缺失、半合性缺失、片段缺失。ＰＣＲＳＳＣＰ检测发现，２例肝细胞癌第５外显子ＰＣＲ产物均显示１条额外电泳迁移带，突变率为５．９％（２／３４）。另２例肝细胞癌第８外显子ＰＣＲ产物呈现额外电泳迁移带，突变率为５．９％（２／３４），合计突变率为１１．８％（４／３４）。结论 所检３４例人肝细胞癌中ＰＴＥＮ基因未见纯合性缺失、半合性缺失、片段缺失，但存在突变。

抑癌基因PTEN非基因调控的研究进展

抑癌基因PTEN的缺失和突变常常和肿瘤的发生发展密切相关。而除了基因的缺失和突变,PTEN也受到许多非基因机制的调控,如转录调控、表观沉默、非编码RNA的转录后调控、翻译后修饰。

p53蛋白在大肠癌中过度表达与组织学类型及分级的关系

目的：探讨大肠癌的发生与组织学的类型及分化程度的关系。方法：用免疫组织化学及常规病理学方法检测55例大肠癌中抑癌基因，p53蛋白的过度表达。结果：p53蛋白的过度表达在大肠癌中为8%，而在正常组织及良性肿瘤中为无表达。按Turbull分期，不同分期大肠癌中p53蛋白过度表达阳性率不同，早期癌（Ⅰ～Ⅱ期）中为32.1%。（9/28），晚期癌（Ⅲ～Ⅵ期）中为48.1%（13/27）（P＜0.015），p53蛋白过度表达在不同组织类型中阳性率不同，如粘液腺癌为41.6%，明显低于管状腺癌的66.6%和乳头状腺癌的53.3%的阳性率。其粘液腺癌与管状腺癌的差异显著（P＜0.05）。p53蛋白的过度表达在不同分化程度的大肠癌中阳性率亦不同，高分化癌为37.5%；而低分化癌为75.4%，（P＜0.05）。结论：p53蛋白过度表达可能发生于大肠癌病理过程的晚期阶段，可作为大肠癌有参考价值的预后指标之一。

癌基因c-myc抑癌基因p53在涎腺肿瘤中的表达

方法：本文采用免疫组化（ＳＰ）法，研究了３０例涎腺肿瘤。目的：观察ｃ－ｍｙｃ癌基因和ｐ５３抑癌基因在涎腺肿瘤中的表达。结果：多形性腺瘤中，ｃ－ｍｙｃ和ｐ５３阳性率分别为５０．０％和２５．０％，均分别低于恶性肿瘤的阳性率７５％和５０．８％，两组比较均有高度显著性差异（Ｐ＜０．０１）。结论：ｃ－ｍｙｃ抑癌基因ｐ５３表达与涎腺上皮细胞增殖速度加快和突变有关，ｐ５３阳性率升高，虽与细胞恶变关系密切，但仅为判断细胞分化程度的一个参考指标。

mRNA expression of DOK1-6 in human breast cancer

AIM:To examine the expression of downstream of tyrosine kinase(DOK)1-6 genes in normal and breast cancer tissue and correlated this with several clinicopathological and prognostic factors.METHODS:DOK1-6 m RNA extraction and reverse transcription were performed on fresh frozen breast cancer tissue samples(n = 112) and normal background breast tissue(n = 31). Tissues were collected between 1991 and 1996 at two centres and all patients underwent mastectomy and ipsilateral axillary node dissection. All tissues were randomly numbered and the details were only made known after all analyses were completed. Transcript levels of expression were determined using real-time polymerase chain reaction and analyzed against TNM stage, tumour grade and clinical outcome over a 10-year follow-up period.RESULTS:DOK-2 and DOK-6 expression decreased with increasing TNM stage. DOK-6 expression decreased with increasing Nottingham Prognostic Index(NPI) [NPI-1 vs NPI-3(mean copy number 15.4 vs 0.22, 95%CI:2.7-27.6, P = 0.018) and NPI-2 vs NPI-3(mean copy number 7.6 vs 0.22, 95%CI:0.1-14.6, P = 0.048)]. After a median follow up period of 10 years, higherlevels of DOK-2 expression were found among patients who remained disease-free compared to those who developed local or distant recurrence(mean copy number 3.94 vs 0.0000096, 95%CI:1.0-6.85, P = 0.0091), and distant recurrence(mean copy number 3.94 vs 0.0025, 95%CI:1.0-6.84, P = 0.0092). Patients who remained disease-free had higher levels of DOK-6 expression compared to those who died from breast cancer.CONCLUSION:Decreasing expression levels of DOK-2 and DOK-6 with increased breast tumour progression supports the notion that DOK-2 and DOK-6 behave as tumour suppressors in human breast cancer.

Kiss-1基因抑制肿瘤转移的研究进展

肿瘤转移抑制基因Kiss-1广泛存在于人体各种组织,其编码的蛋白质Kisspeptins与人类孤儿G蛋白偶联受体结合后,不仅可以使细胞发生局灶性粘附进而使其运动能力受抑制,而且可以抑制MMP-9的表达以维持基底膜的完整,从而达到抑制肿瘤细胞侵袭和转移的作用。Kiss-1基因在肿瘤侵袭和转移过程中的作用目前尚未完全清楚,还有待于进一步研究证实。

抑癌因子DNA高甲基化与肿瘤

肿瘤DNA甲基化的异常包括基因组整体甲基化水平降低或和某些基因启动子区域甲基化水平异常升高。前者可导致原癌基因活化及基因组不稳定等,而基因启动子区域发生异常高甲基化则可导致基因转录沉默,使重要基因如抑癌基因等低表达或不表达及增加点突变,并通过影响多条细胞信号转导通路来干预细胞周期和细胞凋亡等,从而影响肿瘤的发生发展及预后和治疗。了解抑癌因子DNA高甲基化与肿瘤的研究现状,可望为揭示肿瘤发生机制提供新的思路,为肿瘤诊断和治疗提供新的标记物和靶点。

髓系来源抑制细胞调控肿瘤机制的研究进展

髓系来源抑制细胞(Myeloid-derived suppressor cells,MDSCs)是一群未成熟的髓系来源细胞,参与了肿瘤的增殖、侵润、肿瘤血管生成、免疫抑制等病理过程,促进肿瘤的发生和生长;反过来,肿瘤以及肿瘤微环境也可促使MDSCs进一步增殖。本文就MDSCs的产生以及和肿瘤之间的相互作用以及部分作用机制做一综述。