结直肠癌发生的分子机制研究进展

结直肠癌发病呈上升趋势,在西方发达国家结直肠癌仅次于肺癌列恶性肿瘤的第2位。我国上海结直肠癌已是第3位常见肿瘤。在发病率上升的同时,其发病年龄趋向老龄化,发病部位趋向近侧结肠。近10余年来,结直肠癌发生分子模型的提出、遗传性非息肉病性结直肠癌(ＨＮＰＣＣ)发病机理的阐明和ＡＰＣβｃａｔｅｎｉｎＴｃｆ通路改变在结直肠癌发生中的作用的确定是结直肠癌研究具有影响的3大进展。尽管这些分子机制的阐明,并且在结直肠癌筛查、诊断和治疗方面取得了显著的成绩,但对结直肠癌的临床处理和患者预后没有实质性的影响。结直肠癌死亡率仍…     

结直肠癌分子病理诊断进展及其对治疗的指导意义

结直肠癌是一组具有一系列基因组和表观基因组改变的常见恶性肿瘤。其分子病理学的进展可以更好地从发病机制角度理解该肿瘤,从而更加精准地指导治疗。该文旨在概述结直肠癌的分子病理进展及其生物标志物对治疗的指导意义,并讨论了具有临床价值的结直肠癌的分子分型,以便读者更好地理解结直肠癌的分子病理进展及其临床意义。     

微卫星不稳定的人类结直肠癌细胞系对5-氟尿嘧啶的敏感性

目的：探讨人类结直肠癌细胞系对化疗药物的敏感性。方法：用MTT方法测定LoVo,SW480和SW1116细胞对5－氟尿嘧啶（5－FU）的敏感性；用免疫细胞化学方法检测3细胞系hMSH2、hMLH1表达水平；用PCR－SSLP－银染法分别分析了3个细胞系基因组中10个微卫星位点状况。结果：比较3个细胞系MTT分析获得的IC50结果发现，对5－FU LoVo细胞系较SW480和SW1116更加敏感（分别为：0．8μmol/L，2.2μmol/L和1．9μmol/L，P＜0．01）。免疫细胞化学检测结果显示hMSH 2在SW480和SW1116阳性，而在LoVo阳性；hMLH1在3个细胞系均阳性。PCR－SSLP－银染法结果显示LoVo细胞系在8／10个位点和其余两个细胞系不同，电泳条带有不同程度的增加或位移，而另外的2／10个位点则具有相同的电泳带型。结论：该组微卫星位点和错配修复状况一起可以作为离体人类结直肠癌细胞系对5－FU敏感性的指标之一，为了深入阐明它们能否作为临床结直肠癌化疗病人药物筛选和预后评价的有效指标，进一步的在体研究和临床资料总结分析很有意义。     

RAS突变和微卫星不稳定与Ⅲ期结直肠癌患者临床病理特征及预后的相关性分析

目的:检测Ⅲ期结直肠癌患者中RAS和BRAF基因突变以及微卫星不稳定(microsatellite instability,MSI)状态,并分析其临床病理关系及预后。方法:收集2010~2015年广东省人民医院共281例经病理学证实的Ⅲ期结直肠癌组织标本,采用PCR-Sanger测序法和免疫组织化学法对石蜡切片进行分析,检测RAS/BRAF基因突变和MSI状态,并探讨其与结直肠癌临床病理特征和预后的关系。结果:281例患者中,RAS/BRAF突变率为48.4%(136/281),其中KRAS突变率最高(116/281,41.3%)。RAS/BRAF基因突变与癌胚抗原水平密切相关(P0.05)。免疫组织化学法检测到高度MSI(MSI-H)患者18例(6.4%),MSI-H状态在淋巴结转移N2b期患者中更为常见(P0.05)。BRAF基因在MSI-H肿瘤中的突变率较高(P0.01)。RAS/BRAF野生型或者MSI-H患者的总生存期和无进展生存期均明显高于突变型或低度MSI/微卫星稳定患者。结论:RAS/BRAF突变和MSI检测有助于结直肠癌生物学行为分析和患者预后判断。     

结直肠癌个体化治疗的研究进展

化疗在晚期大肠癌的治疗中具有重要地位。不同化疗药物的选择影响疗效和预后。以药物基因组学为基础的大肠癌个体化治疗开始得到重视,本文就分子标记对大肠癌化疗药物包括氟脲嘧啶类、奥沙利铂、伊立替康及分子靶向药物疗效影响的研究现状进行综述,探讨大肠癌个体化治疗发展。     

微卫星不稳定、HER2与结直肠癌恶性程度相关

目的探究结直肠癌中微卫星不稳定(MSI)、人表皮生长因子受体2(HER2)表达情况与其恶性程度的相关性,以及二者联合检测在结直肠癌中可能的临床应用价值。方法对大连医科大学附属第二医院胃肠外科诊治的425例术前未接受任何形式辅助治疗的结直肠癌患者临床资料进行回顾性分析。并应用统计学方法对MSI、HER2表达情况与临床资料间相关性进行分析。结果结直肠癌中HER2高表达与肿瘤分化程度、侵袭深度相关(P0. 05); MSI-H与MSS/MSI-L在肿瘤大小、部位、分化程度、组织类型、侵袭深度、贫血和CA199表达方面存在差异(P0. 05)。MSI与HER2表达情况存在相关性(P0. 05)。结论 HER2、MSI在结直肠癌恶性程度评估方面具有一定协同性,将两者联合检测对结直肠癌恶性程度评估或有一定指导作用。     

结直肠癌中肿瘤浸润性淋巴细胞与微卫星不稳定的相关性分析及预后价值评估

目的在结直肠癌中分析肿瘤浸润性淋巴细胞（TILs）与微卫星不稳定（MSI）的相关性,并评估肿瘤浸润性淋巴细胞对结直肠癌的预后价值。方法120例原发性结直肠癌样本中,通过HE染色、免疫组织化学染色检测肿瘤组织中TILs的数量、CD4⁺TILs及CD8+TILs及CD8⁺TILs的数量,应用实时荧光定量PCR检测微卫星稳定状况,采用SPSS20进行TILs与MSI的相关性分析,并进一步评估TILs对患者预后生存的影响。结果120例结肠癌组织中,MSI-H与临床T分期具有显著负相关性,H-TILs与TNM分期有显著负相关性,并且MSI-H与CD8+TILs的数量,应用实时荧光定量PCR检测微卫星稳定状况,采用SPSS20进行TILs与MSI的相关性分析,并进一步评估TILs对患者预后生存的影响。结果120例结肠癌组织中,MSI-H与临床T分期具有显著负相关性,H-TILs与TNM分期有显著负相关性,并且MSI-H与CD8⁺TILs呈显著正相关性。H-TILs组、H-CD4+TILs呈显著正相关性。H-TILs组、H-CD4⁺TILs组及H-CD8+TILs组及H-CD8⁺TILs组结直肠癌患者具有较高总体生存率。结论肿瘤浸润性淋巴细胞可作为辅助指标对结肠癌患者的预后预测及评估提供依据。     

全反式维甲酸对结直肠癌LOVO、SW480细胞系增殖、凋亡及受体表达的影响

目的探讨全反式维甲酸(all-trans retinoic acid,ATRA)对微卫星稳定(microsatellite stable,MSS)和微卫星不稳定(mic-rosatellite instability,MSI)结直肠癌细胞系的生长抑制作用,以及对LOVO、SW480和维甲酸受体α(retinoic acid receptor-α,RAR-α)表达的影响。方法体外培养MSI结直肠癌细胞系LOVO及MSS结直肠癌细胞系SW480,应用不同浓度的ATRA进行刺激,并设置空白对照组和RAR-α抑制剂对照组。用MTT法分析两种细胞系肿瘤细胞的增殖变化,用RT-PCR技术及平均光密度比值分析RAR-αmRNA表达,用Western blot技术及平均光密度比值分析细胞凋亡蛋白Caspase-3、Caspase-8表达。结果与对照组相比,ATRA对两种细胞系的增殖均有抑制作用,并能有效刺激两种细胞系RAR-αmRNA和凋亡蛋白Caspase-3、Caspase-8的表达(P<0.05)。ATRA刺激后,MSS细胞系RAR-αmRNA、凋亡蛋白Caspase-3、Caspase-8表达高于MSI细胞系(P<0.05)。结论 ATRA能抑制结直肠癌细胞系MSS和MSI肿瘤细胞的增殖,促进这两种特性细胞系的凋亡并增加RAR-α的表达,其对MSS细胞系作用高于MSI细胞系。实验结果间接提示RAR-α减少可能与锯齿状病变广基途径发病机制有关。     

结直肠癌分子靶向治疗的研究进展

结直肠癌发病率和病死率在国内外有逐年上升趋势。世界范围内，每年约有120万新发和60万死亡病例[1]。在我国，结直肠癌的发病率现在年平均增长4%，估计每年有40万新发病例。2004-2005年全国第三次死因回顾抽样调查显示，结直肠癌占恶性肿瘤死亡原因第五位，死亡率达到7.42/10万[2]。手术后的复发和转移是导致治疗失败的主要原因，传统的放、化疗效率低，毒副作用大，远远不能满足临床需求。近半个世纪，结直肠癌的治疗方式已经从单纯的手术切除转向由手术治疗为主，放、化疗和生物治疗等为辅助治疗手段的多学科联合治疗[3]。     

Oncogenic mutations and microsatellite instability phenotype predict specific anatomical subsite in colorectal cancer patients

In colorectal cancer (CRC) oncogenic mutations such as KRAS alterations, are considered standard molecular biomarkers that predict the clinical benefit for targeted intervention with epidermal growth factor receptor (EGFR) inhibitors. In addition, these mutations are associated with specific anatomical area in colon tumor development, as BRAF mutations with the microsatellite instability (MSI). In this translational study, we aimed to assess the mutation frequencies of the EGFR (hotspot area and polyadenine deletions A13_del), KRAS, BRAF^V600E, and PIK3CA oncogenes in a series of 280 CRC patients. MSI phenotypes are also considered in this series. All patients'' clinicopathological data were assessed for statistical analysis and its associations were validated. We verified multiple associations between oncogenic mutations and determined clinicopathological tumor features (1) EGFR A13_deletions are associated with right colon carcinoma (P<0.005), mucinous histotype (P=0.042), G3 grading (P=0.024), and MSI status (P<0.005); (2) PIK3CA mutations are related mucinous histotype (P=0.021); (3) KRAS^G12 and KRAS^G13 mutations are correlated, respectively, with the left and right colon cancer development (P<0.005), and finally (4) MSI is associated with right colon tumors (P<0.005). Mostly, we verified a higher frequency rate of the KRAS^G13 and EGFR A13_del oncogene mutations in right colon cancer; whereas KRAS^G12 codon mutation occurs more frequently in left colon cancers. In particular, we assessed that right vs left colon cancer are associated with specific molecular characteristics. These evidences, in association with clinicopathological data, can delineate novel approaches for the CRC classification and targeted intervention.     

An appendix carcinoid tumor in a patient with hereditary nonpolyposis colorectal cancer

Gastrointestinal carcinoid tumors are often associated with other tumors, particularly colon adenocarcinomas; but the association between carcinoid tumors and hereditary nonpolyposis colorectal cancer (HNPCC) syndrome has not yet been explored. We report an unusual case of a 28-year-old woman with HNPCC who underwent surgery for a transverse colon adenocarcinoma in whom an appendix carcinoid tumor was incidentally found. To assess whether the carcinoid tumor displayed the characteristic molecular features of HNPCC tumors, we investigated the expression of mismatch-repair (MMR) proteins and microsatellite instability (MSI) status in both tumors. Both tumors demonstrated normal expression of the MMR proteins hMLH1, hMSH2, hMSH6, and hPMS2. Interestingly, the adenocarcinoma exhibited an MSI phenotype but the carcinoid tumor did not, indicating that these 2 tumors arose through different molecular pathways.     

Molecular detection of minimal residual disease in colorectal and breast cancer

Recent developments in the field of molecular biology enable us to detect tumour cells at a submicroscopical level. In colorectal and breast cancer the most important prognostic factor is dissemination of malignant cells to locoregional lymph nodes. An important issue is whether molecular 'super'-staging augments the accuracy by which the prognosis of individual patients can be assessed. Over the past few years numerous studies have reported the use of different PCR-based techniques in various types of cancer. The reported incidence of micrometastases and specificity of different assays varies tremendously. This clearly indicates the need for uniformity in protocols. For colorectal cancer the use of molecular techniques may improve staging and guide clinical decisions. For breast cancer there is still need to prove the clinical implication of finding occult metastatic disease. Nevertheless, PCR-based techniques are a powerful tool in the staging of common solid tumours and are likely to find their way into the daily practice of diagnostic histopathologists in the near future.     

Microsatellite instability in young patients with colorectal cancer

Genetic instability Is closely correlated to the pathogenesis of hereditary non-palyposis colon cancer (HNPCC), which is clinicaily characterized by a family history and early onset. To investigate the role of genetic instabllity in young patients with colorectal cancer (CRC), 22 CRC patients, who were aged younger than 30 at the time of diagnosis, were studied. Patients with famllial adenomatous polyposis were excluded. Among the 22 cases, seven were identifled as microsateillte instability posltive (MI+), and more than five microsatellite markers among the 15 tested markers showed an additlonal band pattern in the tumor tissue. None of the remaining 15 cases showed instability in any microsatellite marker. Two of seven MI+ cases were classic HNPCC. While all MI+ cases had one or no metastatic lymph node, 53.3% of MI- cases showed metastasls in two or more reglonal lymph nodes. Allelic deletion of the 17p12–13 chromosome around the p53 locus occurred in 16.7% of MI+ cases, and 80.0% of MI- cases showed loss of het-erozygosity at that locus. hMSH2 Protein expression, assessed by immunohistochemistry, was absent in two cases, both of which were MI+. When we tested two to four sites of MI+ tumors, transforming growth factor β receptor type II was mutated in a homogeneous pattern in five MI+ cases. in addition, frame-shift mutations of BAX , insulin-like growth factor II receptor, hMSH3 and hMSH6 were found in three cases, five cases, five cases and one case, respectively. In contrast to the consistent mutatlon of the transforming growth factor-β receptor type II gene, mutations of other genes varied in different portions of the tumors.     

Molecular assessment of colorectal cancer through Lynch syndrome screening

Since 2017, the National Institute for Health and Care Excellence (NICE) has recommended molecular testing of all patients with newly diagnosed colorectal cancer (CRC) to identify those with suspected Lynch syndrome who should be referred to clinical genetics for germline testing. The pathway involves firstly determining the mismatch repair (MMR) expression status by immunohistochemistry (IHC) or performing microsatellite instability testing. This may be followed by BRAF V600E mutation testing and then MLH1 promoter hypermethylation analysis depending on the result. This approach identifies patients that are most likely to have underlying germline mutations in the MMR genes as opposed to somatic causes of deficient MMR. Here we demonstrate a case with loss of MLH1 protein expression and discuss the subsequent testing strategy according to NICE guidance.     

DNA mismatch repair deficiency in sporadic colorectal cancer and Lynch syndrome

Poulogiannis G, Frayling I M & Arends M J
(2010) Histopathology 56, 167–179 DNA mismatch repair deficiency in sporadic colorectal cancer and Lynch syndrome DNA mismatch repair (MMR) deficiency is one of the best understood forms of genetic instability in colorectal cancer (CRC), and is characterized by the loss of function of the MMR pathway. Failure to repair replication‐associated errors due to a defective MMR system allows persistence of mismatch mutations all over the genome, but especially in regions of repetitive DNA known as microsatellites, giving rise to the phenomenon of microsatellite instability (MSI). A high frequency of instability at microsatellites (MSI‐H) is the hallmark of the most common form of hereditary susceptibility to CRC, known as Lynch syndrome (LS) (previously known as hereditary non‐polyposis colorectal cancer syndrome), but is also observed in ～15–20% of sporadic colonic cancers (and rarely in rectal cancers). Tumour analysis by both MMR protein immunohistochemistry and DNA testing for MSI is necessary to provide a comprehensive picture of molecular abnormality, for use in conjunction with family history data and other clinicopathological features, in order to distinguish LS from sporadic MMR‐deficient CRC. Identification of the gene targets that become mutated in MMR‐deficient tumours may explain, at least in part, some of the clinical, pathological and biological features of MSI‐H CRCs and holds promise for developing novel therapeutics.     

转移性结直肠癌的维持治疗

转移性结直肠癌治疗已从单纯化学药物治疗向与分子靶向药物联合的方向转化,传统持续给药至疾病进展或患者不能耐受的维持治疗策略也受到许多新策略的挑战。维持治疗不仅可以巩固一线治疗的疗效,而且可以减轻化学治疗药物的累积性毒性,有效提高患者生活质量,延缓疾病进展,并最终延长总生存期。维持治疗已成为转移性结直肠癌化学治疗的研究热点。     

Classification of colorectal cancer based on correlation of clinical, morphological and molecular features

Over the last 20 years it has become clear that colorectal cancer (CRC) evolves through multiple pathways. These pathways may be defined on the basis of two molecular features: (i) DNA microsatellite instability (MSI) status stratified as MSI-high (MSI-H), MSI-low (MSI-L) and MS stable (MSS), and (ii) CpG island methylator phenotype (CIMP) stratified as CIMP-high, CIMP-low and CIMP-negative (CIMP-neg). In this review the morphological correlates of five molecular subtypes are outlined: Type 1 (CIMP-high/MSI-H/BRAF mutation), Type 2 (CIMP-high/MSI-L or MSS/BRAF mutation), Type 3 (CIMP-low/MSS or MSI-L/KRAS mutation), Type 4 (CIMP-neg/MSS) and Type 5 or Lynch syndrome (CIMP-neg/MSI-H). The molecular pathways are determined at an early evolutionary stage and are fully established within precancerous lesions. Serrated polyps are the precursors of Types 1 and 2 CRC, whereas Types 4 and 5 evolve through the adenoma-carcinoma sequence. Type 3 CRC may arise within either type of polyp. Types 1 and 4 are conceived as having few, if any, molecular overlaps with each other, whereas Types 2, 3 and 5 combine the molecular features of Types 1 and 4 in different ways. This approach to the classification of CRC should accelerate understanding of causation and will impact on clinical management in the areas of both prevention and treatment.     

瘦素与结直肠癌的关系

肥胖是结直肠癌发病的危险因素,瘦素是ob基因的表达产物,主要来源于脂肪细胞,是重要的脂肪因子之一,被认为是肥胖和结直肠癌之间联系的重要角色。近年来对瘦素在结直肠癌的形成和进展中的作用及机制的研究对结直肠癌的诊断和治疗具有重要意义。