K—ras基因与结直肠癌疗效

K—ras基因是一种癌基因,促进细胞生长、分化,基因的突变使ras蛋白丧失GTP酶活性,导致细胞的异常生长、分化,促进癌的发生,同时导致使用抗表皮生长因子受体（EGFR）多克隆抗体药物治疗的结直肠癌患者无明显获益。结直肠癌不同实体肿瘤的K—ras基因突变率不同,K—ras基因野生型或突变型对治疗方案选择及预后具有重要意义,突变型患者使用抗EGFR抗体治疗效果差,对5-Fu、FOLFOX疗效尚无一致定论。     

肺癌组织中p53、K-ras、p15、p16基因的改变

目的　探讨p5 3、K ras、p15、p16基因在肺癌组织中改变情况及多基因联合检测在肺癌诊断中的价值。 方法　对 5 9例肺癌组织和 14例肺部良性组织 ,应用PCR SSCP 银染法检测 p5 3基因第 5～ 8外显子突变情况 ;应用PCR RFLP法对K ras基因突变进行检测 ;并应用PCR法检测 p15、p16基因纯合缺失情况。 结果　肺癌组织中 p5 3、p15、p16基因改变频率分别为 3 7.3 %、11.9%、2 3 .8% ,而在肺部良性组织中只有 1例 p16基因阳性。在 2 5例肺腺癌中 ,K ras基因突变率为 48.0 % ,其它类型肺癌中突变率仅为 8.8% ,而 14例良性组织中未检测出K ras基因突变。另外 ,p5 3基因和K ras基因突变与吸烟存在着密切关系 ,即吸烟者出现突变的频率 ( 4 8.7% ,68.5 % )明显高于非吸烟者 ( 15 .0 % ,11.1% ) ,P <0 .0 1。 4种基因联合检测敏感度为 78.0 % ,明显高于单一基因 (以阳性率最高的 p5 3为例 )的敏感度 3 7.3 %。 结论　p5 3基因、K ras基因和 p16基因在肺癌组织中改变率相对较高 ;多基因的联合检测有助于肺癌的早期诊断和筛查。     

肺癌患者吸烟量与痰液细胞p53和Ki—ras基因突变的关系

目的　了解痰液细胞癌基因突变是否与肺癌患者的吸烟量有相关性。方法　将痰液 0 .5毫升加入痰处理液制备细胞沉淀液 ,酚氯仿提取DNA ;应用SSCP PCR银染和RFLP PCR方法对痰液中p5 3、K ras突变情况进行检测。统计肺癌患者的香烟消耗量 ,分析p5 3、K ras突变与吸烟量的关系。结果　在确诊的 110例肺癌中 ,存在p5 3或K ras基因突变者有 76例 ,突变率达 69.1% ,其中 16例为p5 3和K ras基因均有突变。全组中有 71例重度吸烟者吸烟指数 (≥ 40 0支·年 ) ,71例中 5 5例有p5 3或K ras基因突变 ,突变率达 77.5 % ,显著高于非吸烟组 (P <0 .0 0 1) ;p5 3和K ras突变患者的平均吸烟指数分别达到 861和 63 0支·年 ;而未突变的平均吸烟指数为 2 84和 5 5 4支·年 ,二者之间有显著性差异 ( χ2 =3 6.5 6,P =0 .0 0 2 ,双尾检验 )。结论　痰液细胞癌基因突变检测具有简便、实用、可行的特点 ,吸烟的肺癌患者中癌基因突变率显著高于非吸烟的肺癌患者 ,提示吸烟尤其是重度吸烟可能是支气管癌基因突变的主要原因之一 ,值得临床进一步开展深入的研究。     

直肠癌K—ras基因突变和细胞动力学异常

采用扩增片段限制性长度多态性分析（Amp－RFLP）和流式细胞分析技术（FCM）对直肠癌切除标本、癌旁远端肉眼观察“正常”的肠组织及正常肠粘膜，结合病理资料，比较其细胞DNA倍体性、S期百分比和增殖指数，检测K－ras基因12位密码子点突变，结果表明：直肠癌是进展迅速的恶性肿瘤，细胞增殖活性异常升高；K－ras基因突变是伴随直肠癌的一种基因异常表现，癌旁组织出现基因水平的异常发生在组织形态学和细胞动力学改变之前，是癌变发生的早期行为。     

子宫内膜癌前病变中K-ras与MTS1/p16基因的表达及意义

 目的　探讨K ras激活与MTS1/ p16基因突变 /缺失在子宫内膜癌中的发生发展关系。 方法　对子宫内膜癌及癌前病变组织K ras与MTS1/p16蛋白的免疫组化测定并用PCR技术对MTS1/ p16基因在子宫内膜癌中的纯合性缺失进行检测。结果　K ras、p16蛋白广泛存在于子宫内膜癌和癌前病变组织中 ,癌前病变K ras表达为 11.9% ,癌组为 6 2 .96 % (P <0 .0 5 ) ,而p16表达分别为 76 .5 9%与5 1.85 %。 13例 p16蛋白表达阴性子宫内膜癌PCR扩增 ,7例显示外显子 1缺失。K ras表达与细胞恶性程度呈正相关 ,p16表达则呈负相关。 结论　 (1)K ras基因激活与MTS1/ p16基因突变 /缺失导致细胞周期增殖失控 ,是内膜癌发生发展的一个重要环节 ;(2 )子宫内膜癌中p16基因外显子 1纯合子缺失可能是p16蛋白表达降低的机制之一 ;(3)动态观测内膜增生组织中的p2 1ras表达阳性者 ,对子宫内膜癌的早期发现可能有积极意义     

妊娠滋养细胞疾病c-Ha-ras基因突变及ras p21蛋白表达的研究

目的 :探讨c -Ha -ras基因突变及 p21蛋白表达与妊娠滋养细胞疾病 (GTD)发生发展的关系 ,寻找具有特异性的可预测PTD的诊断标记。方法 :采用PCR -SSCP法及SP免疫组化法 ,对90例GTD组织中c -Ha -ras基因第1外显子点突变及其产物 p21表达进行检测 ,以正常足月新鲜胎盘30例为对照。结果 :所有正常胎盘组织ras突变及p21表达均为阴性。ras基因突变在恶性GTD中为36 7 % ,CM将来发展成为PTD的为43 3 % ,均高于CM无PTD发展的16 7 %。恶性GTD,Ⅰ、Ⅱ、Ⅲ级组织分化者点突变率分别为15 4 %、40 %、71 4 % ,各级间差异有显著性 (P<0 01)。不同转归的CM,p21表达不同 ,CM中发展成为PTD者 ,p21表达率为83 3 % ,明显高于未发展成PTD者的43 3 %(P<0 005) ,亦高于恶性GTD的60%(P<0 05)。结论 :GTD的发展演进与ras基因突变及p21表达有关 ,ras突变及p21表达可考虑作为预测PTD的诊断指标之一。GTD由良性到恶性的发展过程中 ,p21表达量存在由低→高→低的内在变化 ,其原因和机理尚需深入探讨     

胃癌患者血浆p53、K-ras基因突变及临床意义

[目的]研究胃癌患者血浆中基因表达检测的可行性，探讨基因p53和K—ras突变与临床病理间的关系。[方法]应用PCR—SSCP分析技术，检测62例胃癌患者血浆中K—ras癌基因的突变情况。[结果]62例胃癌患者外周血和门静脉血中的p53、K—ras突变阳性率分别为8．06％、4．83％和38．71％、33．87％；无、有肝转移患者p53、K-ras突变阳性率分别为24．49％、22．45％和92.30％、76．92％；门静脉mp53、K—ras突变阳性率分别为38．71％、33．87％和56．45％、62．90％。[结论]胃癌的发生发展与血浆中癌基因K-ras与抑癌基因D53的突变有关。     

PCR-SSCP法检测E-cadherin基因突变与非小细胞肺癌术后预后及淋巴结转移关系的研究

[目的]探讨E—cadherin基因突变在人非小细胞肺癌（NSCLC）中的作用。[方法]采用PCR—SSCP方法检测53例非小细胞肺癌原发灶组织和5例肺部其他良恶性病变组织的E-cadherin基因突变的情况。[结果]3例NSCLC发生E—cadherin基因的突变。E-eadherin基因的突变与NSCLC的淋巴结转移情况有关（P〈0．05），但与肿瘤的病理类型、原发灶情况以及预后无关（P〉0．05），而且在NSCLC与肺部其他病变之间，E—cadherin基因的突变也无显著性差异。[结论]E-eadherin基因能够较好地预测非小细胞肺癌的淋巴结转移情况。     

肺癌发病机理的遗传学及分子学现象观察

对主要癌基因和肿瘤抑制基因的研究表明NSCLC与SCLC在遗传损伤方面有特征性区别,并可以此结合临床加以鉴别。所有肺癌中半数以上具有p53肿瘤抑制基因突变,但并不表明突变与存活之间有关联。约20％NSCLC病人的肿瘤及肿瘤细胞系中发生ras家族癌基因的突变,相反45例SCLC病人的肿瘤及肿瘤细胞系ras基因无一例突变。回顾调查存活的NSCLC病人,发现K-ras基因突变是决定患者预后的一个不利因素。吸烟肿瘤病人K-ras基因突变比非吸烟者更常见,而对接触放射性元素镭的职业性肺癌并未检测出K-ras突变。肺癌的p53和K-ras基因突变几乎都是G→T颠换,而其他癌症则是G→A颠换。从密切随访     

大肠癌中p185~(erbB2)、p21~(ras)、p53的表达及其临床病理意义

目的　研究大肠癌中p185 erbB2 、p2 1ras、p5 3的表达及其临床病理意义。方法　采用S P法检测 80例大肠癌组织中p185 erbB2 、p2 1ras、p5 3的表达。 结果　大肠癌原发病灶中 p185 erbB2 、p2 1ras、p5 3的阳性表达率分别为 5 8.8%、71.3 %及 5 3 .8%。癌组织同时有 2种以上蛋白表达者占 6 3 .7% (5 1/80 ) ,有 3种蛋白同时表达者占 30 % (2 4/80 )。p185 erbB2 的阳性表达与肿瘤组织学类型有关 ;p2 1ras的阳性表达与肿瘤组织学类型、浸润深度、淋巴结转移有关 ;p5 3的阳性表达与临床病理指标无相关性。 结论　c erbB 2、p2 1ras及 p5 3可能与大肠癌的发生有关 ,在大肠癌的发生中可能起协同作用 ,3种蛋白阳性表达与预后无相关性     

Simultaneous mutations in K-ras and TP53 are indicative of poor prognosis in sporadic colorectal cancer

Despite the fact that the mutations in K-ras codon 12 and TP53 are common abnormalities in colorectal cancer, the determination of K-ras mutation combined with TP53 gene mutation, with diagnostic and prognostic purposes is still controversial. We have analyzed K-ras and TP53 mutations in 77 sporadic colorectal adenocarcinomas by means of polymerase chain reaction and sequencing. We observed a negative correlation between both K-ras and TP53 mutations. Patients with mutations in K-ras but not in TP53 exhibited worse survival rates than those with mutations in TP53 and not in K-ras. Moreover, we found the worst outcome in patients with mutations in both K-ras and TP53. These results may relate to the previously published data about primary human and rodent cells, in which transformation by Ras require either a cooperating oncogene or the inactivation of tumor suppressors such as p53 or p16. In conclusion, simultaneous mutations in K-ras and TP53 are indicative of a worse prognosis in sporadic colorectal cancer.     

Detection of mutations of p53 tumor suppressor gene in pancreatic juice and its application to diagnosis of patients with pancreatic cancer: comparison with K-ras mutation.

Because of the difficulty in obtaining biopsy specimens from pancreatic cancer patients, K-ras mutation analysis in pancreatic juice has been used for specific diagnosis. But recently, false positives have been obtained with this method. To improve the genetic diagnosis of pancreatic cancer, detection of p53 gene mutation in pancreatic juice was studied. Pancreatic juice was sampled endoscopically. Single-strand conformation polymorphism analysis was used for p53 mutation analysis. Furthermore, K-ras mutations at codon 12 were also studied in the same pancreatic cancer patients. Of 26 cases of pancreatic cancer, p53 mutations were detected in 11 (42.3%). No mutations were seen in the cases with mucin-producing adenoma nor with chronic pancreatitis. K-ras mutations were detected in 84.0% of cases by RFLP analysis, which has high sensitivity, and in 65.3% by hybridization protection assay, which has high specificity. Using a combination assay with both genes, genetic abnormalities were detected in 92.0% by RFLP and 73.1% by hybridization protection assay including two cases in which p53 alone was positive by both methods. The specificity of p53 mutation for pancreatic cancer is very high. Therefore, simultaneous analysis of p53 and K-ras mutation is suggested to enhance the genetic diagnosis of pancreatic cancer.     

肺癌患者组织和痰液中p53基因、K-ras基因突变

 目的　探讨p53、K-ras基因在肺癌患者癌组织及相应痰液中改变情况及其联合检测在肺癌早期诊断中的价值。方法　对59例肺癌组织和14例肺部良性组织及相应痰液,应用PCR-SSCP-银染法检测了p53基因第5～8外显子突变情况;应用PCR-RFLP法对K-ras基因突变进行了检测。结果　p53基因在肺癌组织中突变率为37.3%,K-ras基因在肺腺癌突变率为48.0%,其它类型肺癌突变率仅为8.8%。相应痰液中两基因突变率分别为33.8%和44.0%,与组织中的突变率无明显差异,P<0.01。良性组织及相应痰液中两基因均无突变。吸烟患者的突变率(48.7%,68.5%)明显高于非吸烟患者的突变率(15.0%,11.1%),P<0.01;两基因的联合检测在肺癌的早期诊断中的价值(54.2%)明显优于单基因的检测,P<0.05。结论　痰液和组织中的基因突变率基本相似,即痰液中脱落细胞的分子遗传学改变能反映肺组织情况。因此以痰液为目标多基因的联合检测可能有助于肺癌的诊断。     

Genetic and biochemical changes in colorectal carcinoma in relation to morphologic characteristics

A distinct genetic pathway may be involved in the development of polypoid and flat colorectal cancers, two morphologically different cancer subtypes. The present study was undertaken to clarify whether different combinations of some genetic alterations commonly involved (such as K-ras and p53 gene mutations) may exist between polypoid and flat types. In addition, to investigate any different proliferative behavior between the two distinct types of colorectal cancer, we tested the enzymatic activity of ornithine decarboxylase (ODC). A total of 29 polypoid type and 21 flat type colorectal cancers were selected for this study. We investigated K-ras and p53 mutations by polymerase chain reaction followed by restriction fragment length polymorphism (PCR-RFLP) and single strand conformational polymorphism (PCR-SSCP) analysis, respectively. A radiometric method was used to evaluate ODC activity. K-ras and p53 gene mutations were present in 30 and 48% of cases, respectively. A significant association between the p53 mutation and the flat type of colorectal cancer was detected; on the contrary, no significant difference in frequency of K-ras mutation between polypoid and flat type colorectal cancer was found. A statistically significant difference in ODC activity levels was observed between polypoid and flat types. Moreover, we found that ODC activity was significantly higher in neoplastic tissue than in surrounding normal mucosa in polypoid type colorectal cancer. Different mutation patterns and proliferative behavior were observed in polypoid and flat colorectal malignant tumors. Further studies will be required to ascertain whether the distinct growth appearance of colorectal cancer can affect the outcome and prognosis of patients with this type of malignant disease.     

Detection of p53 and K-ras mutations in sputum of individuals exposed to smoky coal emissions in Xuan Wei County, China

Lung cancer mortality rates in the Xuan Wei County population are among the highest in China and are associated with exposure to indoor emissions from the burning of smoky coal. Previous studies of lung tumors from both non-smoking women and smoking men in this region showed high frequencies of mutations, consisting mostly of G-->T transversions in the p53 tumor suppressor gene and K-ras oncogene, suggesting that these mutations were caused primarily by polycyclic aromatic hydrocarbons. In this study sputum samples from 92 individuals with no evidence of lung cancer from Xuan Wei County were screened for p53 and K-ras mutations. Sputum cells were collected on glass slides by sputum cytocentrifugation, stained and cytopathologically analyzed. Cytologically non-malignant epithelial cells were taken from each sputum sample using a laser capture microdissection microscope and molecularly analyzed. Cells taken from the sputum of 15 (16.3%) individuals were mutation positive, including 13 (14.1%) individuals each with a p53 mutation, 1 (1.1%) individual with a K-ras mutation and 1 (1.1%) individual with a p53 and a K-ras mutation. p53 mutations were found in both the sputum of individuals with evidence of chronic bronchitis (3 of 46 or 6.5%) and those without evidence of this disease (11 of 46 or 23.9%). Therefore, mutations in the p53 gene and, to a lesser extent, the K-ras gene were frequent in non-malignant epithelial cells taken from the sputum of individuals without evidence of lung cancer who were exposed to smoky coal emissions in Xuan Wei County and were at a high risk for developing the disease.     

p53 and K-ras gene mutations correlate with tumor aggressiveness but are not of routine prognostic value in colorectal cancer.

PURPOSE: p53 gene and K-ras mutations are among the most common genetic alterations present in colorectal cancer. The prognostic utility of such mutations remains controversial. The purpose of this study was to prospectively evaluate the prognostic significance of p53 and K-ras gene mutations in colorectal cancer. PATIENTS AND METHODS: One hundred forty patients were analyzed. Tumors belonging to the microsatellite mutator phenotype were excluded (n = 8). Mutations at the K-ras and p53 genes were detected and characterized by restriction fragment length polymorphism, single-strand conformation polymorphism, and sequencing, as appropriate. RESULTS: p53 mutations were detected in 66 (50%) and K-ras mutations were detected in 54 (41%) of the 132 patients. In 26 cases (20%), ras and p53 mutations coexisted; in 38 cases (29%), neither mutation was found. Multivariate analysis of the whole population analyzed (n = 132) showed that survival was strongly correlated with the presence of p53 mutations alone or in combination with K-ras mutations (P = .002; log-rank test). When only patients undergoing a radical resection were considered (R0; n = 101), p53 mutations were no longer of prognostic significance. CONCLUSION: p53 mutations alone or in combination with K-ras mutations are correlated with a worse outcome. However, the routine use of these mutations as prognostic markers in the clinical setting is not recommended.     

K-ras and p53 mutations are an independent unfavourable prognostic indicator in patients with non-small-cell lung cancer.

We examined 159 consecutive cases of non-small-cell lung cancer (NSCLC) for a mutation at codon 12 of the K-ras gene and for a mutation of the p53 gene occurring in exons 5-8. Eleven (6.9%) had mutations of the K-ras (ras+) and 57 (35.8%) had mutations of the p53 (p53+). There were 95 cases (59.7%) with ras- p53-, seven cases (4.4%) with ras+/p53-, 53 cases (33.3%) with ras-/p53+ and four cases (2.5%) with ras+/p53+. The ras+ group had a worse prognosis than the ras group in all cases and in 107 early-stage cases (stage I-II, P<0.05). The p53+ group had a worse prognosis in 107 early-stage cases (P<0.01), but there was no statistically significant difference when 52 advanced-stage cases (stage III-IV) or all patients were considered. Both ras and p53 mutations were unfavourable prognostic factors in 94 cases with adenocarcinoma, but there was no statistical significance in 57 cases with squamous cell carcinoma. According to Cox''s model, the pathological stage, ras mutation and p53 mutation were found to be independent prognostic factors. Our results suggest that ras and p53 mutations were independent unfavourable prognostic markers especially in the early stage of NSCLC or in adenocarcinoma.     

Analysis of the c-myc, K-ras and p53 genes in methylcholanthrene-induced mouse sarcomas.

We have examined 63 methylcholanthrene (MCA)-induced mouse sarcomas for possible correlations of mutations involving the c-myc, ras and p53 genes. The c-myc gene was found to be amplified in 18 of these sarcomas (29%). Polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis and subsequent direct sequencing identified 18 cases carrying K-ras mutation at codons 12, 13 and 61 (29%). No mutation was detected in the H-ras and N-ras genes. Mutations of the p53 gene in exons 5 to 8 were found in 45 cases (71%). Comparison of these mutations revealed that out of 18 cases with c-myc gene amplifications, 10 carried K-ras mutations (56%) and 14 carried p53 mutations (78%). In contrast, among 45 cases of sarcomas without c-myc gene amplification, 8 were found to have K-ras mutations (18%). The same 45 cases were found to have 31 p53 mutations (69%). The present study suggests a strong correlation between c-myc gene amplification and K-ras gene mutation (P < 0.01). p53 gene mutation was frequently found among MCA-induced mouse sarcomas, indicating the importance of this mutation in the etiology of these tumors. However, p53 mutations were present in sarcomas regardless of the state of c-myc amplification and K-ras mutation. Therefore, a defect in the p53 gene is independent of amplification of the c-myc gene or point mutation of the K-ras gene.     

Somatic mutations of LKB1 and beta-catenin genes in gastrointestinal polyps from patients with Peutz-Jeghers syndrome

Peutz-Jeghers syndrome (PJS) is characterized by multiple gastrointestinal hamartomatous polyps, mucocutaneous melanin deposition, and increased risk of cancer, mainly in the gastrointestinal tract. We examined mutations of the LKB1, beta-catenin, APC, K-ras, and p53 genes in 27 gastrointestinal hamartomatous polyps from 10 patients in nine PJS families. Of these hamartomatous polyps, one intestinal polyp had an adenomatous lesion, and one gastric polyp contained adenomatous and carcinomatous lesions. Germ-line mutations of the LKB1 gene were detected in six PJS families. Somatic mutations of the LKB1 gene were found in 5 polyps, whereas loss of heterozygosity (LOH) at the LKB1 locus at 19p was seen in 14 other polyps. In adenomatous lesions microdissected from hamartomatous polyps, both beta-catenin mutation and 19p LOH were detected. Furthermore, a carcinomatous lesion in a gastric hamartomatous polyp was found to contain a mutation of the p53 gene and LOH at the p53 locus in addition to LOH at the LKB1 locus and a beta-catenin mutation. K-ras mutations were detected in a few polyps, whereas no APC mutation or 5q LOH was detected in hamartomatous polyps. These results suggest that gastrointestinal hamartomatous polyps in PJS patients develop through inactivation of the LKB1 gene by germ-line mutation plus somatic mutation or LOH of the unaffected LKB1 allele, and that additional mutations of the beta-catenin gene and p53 gene convert hamartomatous polyps into adenomatous and carcinomatous lesions.