K-ras基因突变在内蒙古地区结直肠癌患者中研究

目的检测内蒙地区结直肠癌K-ras基因突变情况,并结合临床病理资料加以分析。方法提取15例结直肠癌患者结直肠癌手术切除标本组织的DNA,对产物进行基因序列癌组织的DNA聚合酶链反应（PCR）扩增、DNA直接测序分析。结果 K-ras基因突变率为0%,几种分化型的结直肠癌均未发现K-ras基因突变类型,包括12密码子（GGT）、13密码子（GGC）。结论我院结直肠癌患者k-ras基因突变率为0%,转移性结直肠癌患者原发肿瘤与转移灶肿瘤k-ras基因型均相同;结直肠癌患者k-ras基因突变与否与年龄、性别、肿瘤浸润深度、肿瘤组织学类型无关。     

中国人大肠癌K-ras基因突变的研究

目的：检测K－ras基因在国人散发性大肠癌中的突变情况,探讨K-ras基因突变在中国人大肠癌中的特点以及与临床病理参数的关系。方法：微解剖取正常粘膜组织15例、癌组织35例、PCR扩增、DNA测序、检测K－ras第12、13和61密码子的突变情况。结果：癌组织K－ras突变率为14．3％（5／35）,均发生在第12密码子（GGT→GAT）。第13和61密码子无突变,正常粘组织无K－ras突变。伴有12密码子突变的大肠癌患者年龄较大,大体以隆起型为主,均分布在C和D期,有较强的侵袭性。结论：中国人大肠癌K-ras突变率为14．3％,低于欧美国家且仅发生在第一外显子的12密码子的第二碱基。大肠正常粘膜无K－ras突变。K-ras突变与患者的年龄、肿瘤的大体形态和Dukes分期等临床病理参数有关。     

Rapid detection of low-abundance K-ras mutation in stools of colorectal cancer patients using chip-based temperature gradient capillary electrophoresis

Mutant K-ras provides an independent negative predictive marker for epidermal growth factor receptor (EGFR)-targeted therapy in colorectal cancers (CRCs). Rapid, sensitive, and cost-effective screening for K-ras status will overarch rational personalized medicine. Stool-based DNA testing offers unique advantages for CRC screening such as noninvasiveness, high specificity, and patient compliance, whereas complicated procedures and the low sensitivity of the present approaches have hampered its application on a wide scale. In this study, a chip-based temperature gradient capillary electrophoresis (TGCE) technique was applied to detect low-abundance K-ras mutations under a pooled experiment and analyze K-ras mutations in 30 paired stool samples and cancer tissues of CRC patients and 15 stool samples of healthy volunteers. The chip-based TGCE results showed that the successful analysis of K-ras status could be achieved within 6?min with an extremely low sample consumption of 14?nl. Detection is sensitive enough to reliably report 0.2% mutant CRC cells in a wild-type background, and 0.5?ng of template DNA was sufficient for chip-based TGCE. Of the 30 stool samples of CRC patients analyzed, 17 (57%) harbored K-ras mutations, and the lowest percentage of the detectable mutant K-ras in stool samples was 2%. The coincidence rate for K-ras mutations between stools and tissues obtained by the chip-based method reached 97% (29/30). One of the 15 stool samples of normal controls carried K-ras mutations, producing a specificity of 93%. Clone sequencing data entirely confirmed the results obtained by chip-based TGCE. The study demonstrates that chip-based TGCE is capable of rapidly screening low-abundance K-ras mutations with high sensitivity, reproducibility, simplicity, and significant savings of time and sample. Application of this method to genotype the K-ras gene in stools would provide a potential means for predicting the effectiveness of EGFR-targeted therapy in CRC patients using noninvasive approaches.     

结直肠癌组织中K-ras基因突变的分子病理学检测分析

目的:应用实时荧光定量PCR方法探讨K-ras基因突变情况及其临床病理意义。方法:收集71例结直肠癌石蜡组织,使用实时荧光定量PCR法检测K-ras基因状态。结果:结直肠癌中K-ras基因突变率为35.22%(25/71),发现7种突变(Gly12Asp,Gly12Val,Gly12Cys,Gly12Ser,Gly12Ala,Gly12Arg和Gly13Asp),其中1例为Gly12Val和Gly12Arg双突变,其中56.00%(14/25)的突变发生在第十二密码子的第二位碱基,且最常见类型为Gly12Asp。K-ras基因突变率在男性组中低于女性组(χ2=7.904,P=0.005),在无淋巴结转移组中低于有淋巴结转移组(χ2=5.851,P=0.016),差异有统计学意义,但K-ras基因突变与其他临床病理参数(年龄、肿瘤位置、浸润深度、组织学类型及Dukes’分期)差异均无统计学意义(P>0.05)。结论:女性或有淋巴结转移结直肠癌患者K-ras基因突变多见,可作为筛查是否进行分子靶向治疗的重点人群。     

A rapid PCR ELISA for the detection of activated K-ras in colorectal cancer

Aims—To develop a rapid PCR ELISA procedure for the detection of mutations in K-ras in a microtitre plate format, and to evaluate the assay for the detection of these mutations in human colorectal cancer.     

Factors affecting KRAS mutation detection in colorectal cancer tissue

Background

With the recent development of molecular tests for various biomarkers, it has become even more important to prepare adequate tissue samples. However, little is known about how the effect of cold ischemia time or formalin fixation time can affect KRAS mutation detection in colorectal cancer.

Chip-based TGCE定量检测大肠癌K-ras基因点突变

目的建立一种定量检测大肠癌中K-ras基因突变比例的方法,并分析其与临床病理参数之间的关系。方法利用微流控温度梯度毛细管电泳(Chip-based temperature gradient electrophoresis,Chip-basedTGCE)对4例代表性大肠癌组织切片中的K-ras基因突变进行检测,通过AutoCAD软件计算出K-ras基因突变比例,结果经克隆测序校正后获得线性回归方程。应用该方法定量检测84例石蜡包埋大肠癌组织中的K-ras基因突变比例,并探讨其与临床病理参数的关系。结果 Chip-based TGCE检测K-ras基因突变比例与克隆测序检测K-ras突变比例的线性回归方程为y=0.993x-1.387,K-ras基因突变比例与肿瘤部位和浸润深度有显著相关性(P0.05),检测获得的最低K-ras突变比例达到2.51%。结论该研究显示Chip-based TGCE是一种快速、灵敏、便捷、经济的基因突变比例定量分析方法。     

TP53 mutation in colorectal cancer

Approximately half of all colorectal cancers show p53 (TP53) gene mutations, with higher frequencies observed in distal colon and rectal tumors and lower frequencies in proximal tumors and those with the microsatellite instability or methylator phenotypes. Alterations to this gene appear to have little or no prognostic value for colorectal cancer patients treated by surgery alone, but are associated with worse survival for patients treated with chemotherapy. There is some evidence that different p53 mutations are associated with different clinical features including prognosis and response to therapy, although further large studies are required to confirm this. Several in vitro, animal and clinical studies have shown that normal p53 is required for the response of colorectal cancers to 5-fluorouracil-based chemotherapy. This should be confirmed by additional retrospective cohort studies and by the incorporation of P53 status in ongoing and future clinical trials. The evaluation of p53 overexpression, using a standardized immunohistochemical (IHC) procedure, could be a clinically useful marker for the identification of colorectal cancer patients likely to benefit from the standard chemotherapy regime currently used for this disease.     

A novel point mutation at codon 146 of the K-ras gene in a human colorectal cancer identified by the polymerase chain reaction

In this report, point mutations of the K-ras gene at codon 146 were analyzed in 25 cases of colon cancer, 4 cases of lung cancer, and 41 cases of lymphoid malignancy. A codon 146 mutation substituting threonine (ACA) for alanine (GCA) was detected in the tumor tissue of a patient with colon cancer and was not detected in the normal tissue of the same patient. Any additional mutations of theras gene family were not detected in this patient. These results suggest that the codon 146 mutation of the K-ras gene could be involved in the development of naturally occurring human malignancies.     

结直肠癌患者循环肿瘤DNA定量KRAS基因突变的检测

目的建立结直肠癌KRAS基因G12D液体活检技术,并探讨其在结直肠癌诊疗中的应用价值。方法用微滴式数字PCR(ddPCR)技术定量检测52例结直肠癌患者和80名健康对照的血浆游离DNA的KRAS基因G12D突变率和突变浓度;以结直肠癌患者肿瘤组织KRAS基因测序结果为金标准评价ddPCR检测的准确性;分析结直肠癌患者KRAS基因G12D突变率、浓度与其临床表征的关系。结果结直肠癌患者血浆KRAS基因G12D突变型检出率(26.92%)和浓度中位数(81.5 copies/m L)显著高于健康对照(8.75%,16 copies/m L);结直肠患者组高分化腺癌的KRAS基因G12D突变浓度显著高于中分化和低分化腺癌(P<0.05),淋巴结转移N2的KRAS基因G12D突变浓度显著高于N0和N1(P<0.05);结直肠癌患者血浆KRAS基因G12D突变与肿瘤组织突变一致性达87.50%。结论ddPCR检测方法是一种快速、无创和准确的检测血浆循环肿瘤DNA(ctDNA)的方法,其检测结果可为临床用药指导和病程监控提供依据。     

K-ras基因状态与结直肠癌临床病理特征的关系

目的观察结直肠癌原发灶K-ras基因的突变,探讨其与临床病理特征的关系。方法运用实时荧光定量PCR法检测230例结直肠癌组织K-ras基因12、13密码子的突变,利用χ2检验分析其与临床病理特征的相关性。结果 230例结直肠癌患者中,84例K-ras基因发生突变,突变率为36.5%,其中12密码子突变65例(28.2%)、13密码子突变19例(8.3%)。结直肠癌肺转移患者K-ras基因突变率较无肺转移患者高(P=0.022),12、13单密码子突变与临床病理特征(患者年龄、性别、肿瘤部位、病理分型、TNM分期、Dukes分期、区域淋巴结及肝肺转移)无关(P>0.05)。结论结直肠癌K-ras基因突变可能与肺转移存在相关性,检测K-ras基因突变对结直肠癌患者临床个体化治疗具有指导意义。     

APC mutation and tumour budding in colorectal cancer

AIM: To determine the frequency of tumour budding and somatic APC mutation in a series of colorectal cancers stratified according to DNA microsatellite instability (MSI) status. Material/Methods: Ninety five colorectal cancers were genotyped for APC mutation in the mutation cluster region (exon 15) and scored for the presence of tumour budding at the invasive margin in haematoxylin and eosin stained sections. A subset was immunostained for beta catenin and p16. RESULTS: The frequency of both somatic APC mutation and tumour budding increased pari passu in cancers stratified as sporadic MSI high (MSI-H), hereditary non-polyposis colorectal cancer (HNPCC), MSI low (MSI-L), and microsatellite stable (MSS). Both budding and APC mutation were significantly less frequent in sporadic MSI-H cancers than in MSI-L or MSS cancers. Tumour buds were characterised by increased immunostaining for both beta catenin and p16. CONCLUSION: Tumour budding is associated with an adverse prognosis. The lack of budding in MSI-H colorectal cancer may account for the improved prognosis of this subset and may be explained by an intact WNT signalling pathway and/or inactivated p16(INK4a).     

Characteristics of plasma DNA and its application for detection of K-ras gene mutation

DNA diagnosis is useful and significant for clinical oncology, but its use is limited due to a difficulty in preparing tumor-derived DNA materials. To overcome this problem, we investigated the characterization of plasma DNA and it application to successfully detecting K-ras mutation at codon 12 in normal persons, hematopoietic neoplasms, and solid tumors. The range of plasma DNA in each group was 15.8 +/- 5.2 ng/ml, 43.3 +/- 29.8 ng/ml, and 26.8 +/- 17.0 ng/ml, respectively. The ranges in patients with solid tumor were gradually decreased to the normal level of around 15 ng/ml in 3 weeks postoperatively. Plasma DNAs consisted of about 200 bp DNA fragmentation and were convenient for PCR amplification of K-ras gene. The mutation at codon 12 by PCR-RFLP analysis was detected in 13(27%) of 49 patients with solid tumors such as pancreatic cancer, breast cancer, colon cancer, and gastric cancer. The diagnostic specificity was 100%. Serial observations by the PCR-RFLP analysis revealed disappearance of the mutant K-ras about 7 days after successful curative surgery in a patient with gastric cancer.     

Hydrogel-microsphere-enhanced surface plasmon resonance for the detection of a K-ras point mutation employing peptide nucleic acid

Highly-sensitive detection of a K-ras point mutation in codon 12, frequently found in pancreatic cancer, based on DNA-carrying hydrogel microspheres as a response enhancer for surface plasmon resonance (SPR), is described. Acrylamide-based microspheres with carboxyl groups were conjugated with DNA probes. Use of the DNA-carrying microsphere in the sandwich method, that is, binding of the microspheres with target DNAs at the sensor surface, enhanced the SPR response as a combined result of increased dielectric constant by the DNA-carrying microspheres. Microspheres lead to response enhancement, as shown by a 100-fold increase in sensitivity compared to that of non-amplified DNA target hybridization. In addition, the advantage of peptide nucleic acid (PNA) in the detection of a K-ras point mutation at the sensor surface by increasing temperature and flow rate is discussed. Results illustrate that the sandwich method through DNA-carrying microspheres for a SPR sensor is a promising approach for ultrasensitive DNA detection.     

BRAF mutation in sporadic colorectal cancer and Lynch syndrome

The aim of the study was to detect mutations of BRAF oncogene in colorectal cancer and to use this information to identify Lynch syndrome patients. Consecutive cases of primary colorectal cancer (n?=?137) were analyzed for MLH1 protein expression using immunohistochemistry (IHC). BRAF V600E mutation was detected by IHC using a specific monoclonal antibody (VE1) and by qPCR. All MLH1 protein-negative cases were subjected to microsatellite instability analysis and MLH1 promoter methylation assay. MLH1 protein expression deficiency and high microsatellite instability (MSI-H) were detected in 18 of the 137 (13.1 %) consecutive colorectal cancer specimens. Detection of the BRAF V600E mutation by IHC was 100 % sensitive and specific as compared to qPCR, and this mutation was frequently present in the MSI-H group (77.8 %; 14/18) and less frequently in the microsatellite-stable group (7.6 %; 9/118). All BRAF V600E mutated cases of the MSI-H group presented with a MLH1 promoter methylation (14/14) as detected by methylation-specific multiplex ligation-dependent probe amplification. When BRAF was wild type in the MSI-H group, only one MLH1 promoter methylation was detected (1/4), and of the remaining three cases without MLH1 methylation, two were identified to harbor an MLH1 mutation consistent with Lynch syndrome. Finally, 11 previously confirmed Lynch syndrome cases were analyzed for BRAF V600E mutation, and all of them were wild type. In conclusion, detection of BRAF V600E in colorectal cancer specimens by IHC is sensitive and specific and may help to identify Lynch syndrome patients.     

胃癌组织中HER-2基因扩增和K-ras基因突变的关系

目的探讨胃癌组织中HER-2蛋白表达和基因扩增与K-ras基因突变的关系及其意义。方法采用免疫组化、FISH和焦磷酸测序技术对67例胃癌组织中HER-2蛋白表达、HER-2基因扩增与K-ras基因的突变率进行了检测。结果 HER-2蛋白阳性率为40.3%(27/67),其中HER-2蛋白3+者9.0%(6/67),HER-2蛋白2+者13.4%(9/67),HER-2蛋白1+者17.9%(12/67)。FISH检测HER-2基因扩增率为18.5%(5/27),HER-2基因拷贝数增加和基因扩增者共48.1%(13/27)。K-ras基因突变定量检测为7.5%(5/67),均为K-ras基因第12密码子突变,其中低于10%低丰度突变2例,高于10%高丰度突变3例(突变数值分别为:17、29、30)。除1例为GGT→GAT突变型外,其它均为GGT→GTT突变型。本组K-ras基因突变5例中除1例既有K-ras基因突变,又有HER-2基因扩增,另外4例HER-2基因均无扩增。结论检测胃癌中HER-2扩增时选用抗肿瘤药物治疗的靶点曲妥珠单抗,同时可选用K-ras基因突变的抗肿瘤药物治疗的靶点西妥昔单抗;联合检测胃癌组织中HER-2基因扩增和K-ras基因突变为靶向抗肿瘤药物治疗过程中受益提供参考指标。