p53 protein overexpression and K-rascodon 12 mutation in pancreatic ductal carcinoma: Correlation with histologic factors

The correlation of p53 protein overexpression and the K-ras codon 12 mutatlon wlth histologlc type, grade of cytologic atypla, depth of lnvasion and other histologlc prognostic factors was studied In paraffin sectlons from 43 ductectatic-and 70 solid-type pancreatic ductal carcinomas. Overexpression of p53 was found in 23.3% (10143) of ductectatic carcinomas (17.2% of intraductal and 35.7% of lnvaslve carclnomas) and in 61.4% (43/70) of solid carcinomas. In ductectatic cancers, p53 overexpression was detected In 14.8% (4/27) of carcinomas wlth lowgrade atypla (CAL), 50.0% (5110) of carcinomas wlth high-grade atypla (CAH) and in 16.7% (In) of mixed low- and hlgh-grade cancers. In the last group, expression was restricted to an area of CAH. In solld cancers, p53 overexpression did not dlffer by histologic type or grade. Overexpresslon of p53 and K-ras mutatlons did not correlate with histologlc prognostic factors (lymphatic, venous and perineural Invasion, and lymph node metastasls) in ductectatlc and solld cancers or depth of invasion of solld carclnomas. Our data suggest that p53 alteratlon occurs at an early intraductal stage of solld carcinoma, irrespectlve of cellular atypla, but Is low in ductectatic CAL and becomes hlgher In ductectatlc CAH. K-ras mutatlon, present In a high percentage of tumors of all groups and not correlating with the factors above, showed no changes In frequency with tumor progression.     

肺癌K-ras基因点突变的研究

目的 :探讨肺癌发生的分子遗传学机理 ,了解肺癌中K ras基因的突变情况。方法 :采用聚合酶链式反应一单链构象多态性 (PCR SSCP)结合银染技术 ,对 3 2例肺癌组织及其相应的癌旁组织中K ras基因第 12、13、61位密码子的突变情况进行检测。结果 :肺癌组织中K ras基因总突变率为 2 5 % ( 8/3 2 ) ,其中腺癌突变率为 40 % ( 4 /10 ) ,鳞癌突变率为 2 3 % ( 3 /13 ) ,大细胞肺癌突变率为 3 3 % ( 1/3 )。小细胞癌突变率为 0 ( 0 /6) ,相应的癌旁组织突变率为 3 1% ( 1/3 2 )。结论 :K ras基因突变与肺癌发生发展有关。     

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。     

Genetic Alterations of Mixed Hyperplastic Adenomatous Polyps in the Colon and Rectum

Some mixed hyperplastic adenomatous polyps (MHAPs) contain dysplastic lesions or even carcinomas. These polyps are considered to be different from ordinary hyperplastic polyps and may have a preneoplastic potential. We investigated APC and K- ras mutations in MHAPs of the colon and rectum, and also in colorectal adenomas and hyperplastic polyps to identify molecular differences between MHAPs, adenomas and hyperplastic polyps, using direct sequencing of mutation cluster regions (MCR) in APC and K- ras . No APC mutations were identified in 12 MHAPs and 8 hyperplastic polyps, whereas 10 of 27 (37.0%) adenomas showed somatic mutations. K- ras mutations were identified in one of 12 (8.3%) MHAPs, one of 8 (12.5%) hyperplastic polyps, and 10 of 27 (37.0%) adenomas. p53 mutation was found in a carcinoma arising in an MHAP. Mutations other than APC mutations may play a role in the development of MHAPs.     

直接测序法检测结肠癌患者K-ras基因的灵敏度及其临床价值分析

目的 探讨结肠癌患者应用直接测序法测定K-ras 基因的灵敏度及其临床价值。方法 选取我院2016 年2 月~2017 年4 月收治的结肠癌患者80 例，随机分为研究组和对照组两组，研究组患者通过直接测序法、对照组患者通过sanger 测序法检测患者体内的K-ras 基因突变情况，分析K-ras 基因突变率与患者肿瘤大小、肿瘤部位、患者年龄等一般资料之间的相关性。结果 研究组患者测定K-ras 基因突变的灵敏度明显高于对照组（P<0.05），肿瘤直径在5 cm 以上患者的K-ras 基因突变率明显低于直径在5 cm 以下的患者（P<0.05）研究组检出率与患者肿瘤部位及分化程度、患者年龄等存在相关性。结论 应用直接测序法检测结肠癌患者K-ras 基因的突变情况具有较高的灵敏度，直接测序法的检出率与患者的肿瘤大小、肿瘤分化程度以及患者的年龄等存在较强的相关性，对于临床上结肠癌等恶性肿瘤疾病的诊断具有较强的应用价值，值得临床上广泛推荐使用。     

The proto-oncogene KRAS is targeted by miR-200c

The GTPase K-ras is involved in a variety of cellular processes such as differentiation, proliferation and survival. However, activating mutations, which frequently occur in many types of cancer, turn KRAS into one of the most prominent oncogenes. Likewise, miR-200c is a key player in tumorigenesis functioning as a molecular switch between an epithelial, non-migratory, chemosensitive and a mesenchymal, migratory, chemoresistant state. While it has been reported that KRAS is modulated by several tumor suppressor miRNAs, this is the first report on the regulation of KRAS by miR-200c, both playing a pivotal role in oncogenesis. We show that KRAS is a predicted target of miR-200c and that the protein expression of KRAS inversely correlates with the miR-200c expression in a panel of human breast cancer cell lines. KRAS was experimentally validated as a target of miR-200c by Western blot analyses and luciferase reporter assays. Furthermore, the inhibitory rffect of miR-200c-dependent KRAS silencing on proliferation and cell cycle was demonstrated in dfferent breast and lung cancer cell lines. Thereby, the particular role of KRAS was dissected from the role of all the other miR-200c targets by specific knockdown experiments using siRNA against KRAS. Cell lines harboring an activating KRAS mutation were similarly affected by miR-200c as well as by the siRNA against KRAS. However, in a cell line with wild-type KRAS only miR-200c was able to change proliferation and cell cycle. Our findings suggest that miR-200c is a potent inhibitor of tumor progression and therapy resistance, by regulating a multitude of oncogenic pathways including the RAS pathway. Thus, miR-200c may cause stronger anti-tumor efffects than a specific siRNA against KRAS, emphasizing the potential role of miR-200c as tumor suppressive miRNA     

Analysis of K-<Emphasis Type="Italic">ras</Emphasis> Codon 12 Mutation in Flat and Nodular Variants of Serrated Adenoma in the Colon

PURPOSE: The developmental process of serrated adenomas is obscure, and the importance of genetic alterations has not been elucidated clearly. The possibility that the developmental process and genetic alterations of serrated adenomas could differ from those of ordinary tubular adenomas was explored in this work. METHODS: Serrated adenomas were obtained by endoscopic resection (n = 57) and divided into two groups: flat (n = 10) and nodular (n = 47). Mutation of the K-ras gene was analyzed by enriched polymerase chain reaction–enzyme-linked mini-sequence assay, which can detect not only the presence of a mutation but also the mutation type of K-ras codon 12 with high sensitivity. Methylation-specific polymerase chain reaction was performed with specific primers for the DNA repair gene O6-methylguanine-DNA methyltransferase. RESULTS: Serrated adenomas located in the rectum were more likely to have a K-ras mutation (9/12, 75 percent), whereas serrated adenomas of the flat type were less likely to have one (1/10, 10 percent). Furthermore, nodular serrated adenomas that occurred in the rectum possessed a high frequency of K-ras gene codon 12 point mutation (8/10, 80 percent) despite an overall frequency of 46.8 percent (22/47). A mutation of the K-ras codon 12 gene was detected in 23 (40.4 percent) of 57 serrated adenomas. Three types of point mutations of codon 12 were detected, with the mutation of GAT being observed most frequently. CONCLUSIONS: This study shows that development of nodular serrated adenomas may depend on the mutation of the K-ras codon 12 gene, whereas development of flat serrated adenomas may not. Additionally, serrated adenomas that occur in the rectum are closely related to the mutation of the K-ras codon 12 gene. K-ras mutations in serrated adenomas may be unaffected by the epigenetic silencing of O6-methylguanine-DNA methyltransferase by promoter hypermethylation.     

Detection of oncogenes in chronic pancreatitis

BACKGROUND: The pathogenesis of chronic pancreatitis (CP) remains poorly understood. Recently, molecular biology has identified the genetic background for many patients with hereditary CP. In addition, a number of studies have focused on the detection of proto-oncogenes and tumour suppressor gene mutations in the pathogenesis of CP. So far, the use of these mutations (with the exception of mutations causing hereditary CP), as diagnostic and prognostic markers is still controversial. DISCUSSION: It is well known that the risk of pancreatic cancer in patients with CP, especially the hereditary form, is high. At present, there is insufficient evidence to show a clear relationship between the development of pancreatic cancer and certain mutations. New biotechnological methods, such as DNA array expression analysis, expand our knowledge of the molecular pathogenesis of this disease and may help to develop specific diagnostic, prognostic and therapeutic tools. However, until long-term studies examine the safety and efficacy of certain genetic markers, long-term follow-up of patients with CP who harbour mutations is needed.     

Ampullary somatostatinoma in a patient with von Recklinghausen's disease

We report a case of somatostatinoma of the ampulla of Vater associated with von Recklinghausen's disease in a 44-year-old woman. On admission the patient was jaundiced, and percutaneous Cholangiodrainage was performed. Cholangiography revealed stenosis of the common bile duct at the lower end Duodenoscopy showed a yellowish tumor of the ampulla of Vater, and the biopsy specimens showed no malignant cells. Pylorus-preserving pancreaticoduodenectomy was performed. Histologically, the tumor was composed of small round cells with a solid or trabecular pattern and with multiple psammoma bodies. Immunohistochemical examination showed that the tumor cells stained for somatostatin. Genomic examination showed neither K-ras nor p53 gene mutations of the resected specimen.