5-脱氧杂氮胞苷预防二甲基肼诱发小鼠大肠癌的研究

目的探讨二甲基肼（DMH）诱导小鼠大肠癌模型中5-脱氧杂氮胞苷（5-aza—dC）预防肿瘤发生的作用机制。方法80只ICR小鼠分为4组，每组20只。包括空白对照组、5-aza—dC对照组、DMH诱癌组和5-aza-dC干预组。处理20周后观察其对肿瘤发生率的影响。实时定量PCR检测Dnmt1、Dnmt3a、Dnmt3b基因和抑癌基因p27^Kip1的表达。结果通过5-aza-dC干预能使诱导的大肠肿瘤发生率从95％降至35％，肿瘤数目（个）由9．43±4．21减少到3．98±2．95，肿瘤最大直径（单位：mm）由6．43±5．12缩小到3．44±2．11，差异有统计学意义（P〈0．05）。实时定量PCR检测发现肿瘤组织中存在Dnmt1和Dnmt3b的高表达，而p27^Kip1的表达量降低。5-aza—dC可以通过抑制甲基化酶活性，防止p27^Kip1基因的高甲基化失活。结论5-aza-dC可以显著降低DMH诱发小鼠大肠癌的发生率，阻止抑癌基因的高甲基化失活可能是5-aza-dC预防肿瘤的重要机制。     

SEPT9在结直肠癌早期检测中的研究进展

SEPT9是13个Septin同源基因家族之一,参与调控众多过程,包括细胞分裂、细胞极化、细胞迁移以及线粒体分裂等。研究表明在众多肿瘤中,SEPT9都发挥着作用,尤其在结直肠肿瘤研究领域,外周血SEPT9基因甲基化检测更是研究热点,其检测的敏感度和特异度相对于其他糖蛋白肿瘤标志物、粪便隐血试验和粪便免疫化学测试等更具有优势,相对于结直肠镜等侵入性检查更节约成本,同时有着更好的依从性。本文对SEPT9的功能、与结直肠癌之间的关系以及对结直肠肿瘤的筛查及诊断价值做一综述。     

大肠癌组织端粒酶活性的检测及其意义

目的探讨端粒酶活化在大肠癌发生及发展中的作用。方法采用ＰＣＲ为基础的ＴＲＡＰ技术对３２例大肠癌的手术切除标本及４例大肠腺瘤组织的端粒酶活性进行检测。结果３２例大肠癌患者组织有２５例检出端粒酶活性，阳性率为７８１％。２例绒毛状腺瘤检出端粒酶活性，２例管状腺瘤为阴性。端粒酶活化与肿瘤部位、大小、组织学分级、浸润深度、淋巴结转移及Ｄｕｋｅ分期无显著相关。结论检测大肠癌组织端粒酶活性对阐明大肠癌的发病机制、癌变危险性的预测及早期诊断均可能有重要意义。     

Sporadic Colon Cancer: Mismatch Repair Immunohistochemistry and Microsatellite Instability in Omani Subjects

Background Colorectal carcinoma (CRC) is the most common gastrointestinal malignancy in the world, and there are suggestions of a particularly high incidence in the Middle East, including those of African origin. Defects in DNA mismatch repair (MMR) systems are involved in the carcinogenesis of both sporadic and inherited human cancers. We assessed colonic cancers in an attempt to identify tumors with DNA MMR deficiency and microsatellite instability (MSI). Additionally, we tested the ability of cell cycle regulator p16 that effects cell proliferation and can be abrogated by hypermethylation of the promoter region. Methods We reviewed the charts of 756 patients who were referred to the Oman major colonoscopy unit of the Sultan Qaboos University Hospital and Royal Hospital from the years 2000 to 2004. Colon cancer tissue was assayed using immunohistochemistry for expression of hMLH1 and hMSH2, and a panel of five pairs of microsatellite primers (NR21, NR22, NR24, BAT25, and BAT26) for MSI-H analysis and additional dinucleotide markers (D17S250, D5S346, and D2S123) used for MSI-L. The expression status of MMR genes and MSI was correlated with cancer stage, location, and histology. A total of 49 tumors were analyzed for histopathology, MSI, and hMLH1/hMSH2 protein expression analysis. The methylation status of the p16 promoter was determined by methylation-specific polymerase chain reaction (PCR). Results The mean age for the carcinomas was 52.2 years and 53% of the patients were male. The majority of the tumors were left-sided. The information currently available indicates that there is an incidence of 4.7% colon cancer (49/1036) and 12.1% (126/1290) colon adenoma among the cases who underwent colonoscopy at these centers. The rate of MSI-H was 12.2% (n = 6), which appears to be the same as previously reported in literature. Eight of 49 tumors (16.3%) were MMR defective by IHC. Defects in the mismatch repair genes hMLH1 and hMSH2 were found in four (66.7%) and two (33.3%) of CRCs MSI-H cases, respectively. Defects in hMLH1 expression in tumors were commonly associated with moderate differentiation. The p16 promoter was methylated in 4% of tumors. Conclusion This is the first genetic study of CRC in this region of the world to demonstrate the incidence of MSI, p16 methylation, and hMLH1 and MSH2 expression in the Omani population. In addition, a relatively high frequency of CRC in younger age groups was noted, which is an important observation. The left-sided preponderance of MMR defective tumors was mostly associated with hMLH1, and with possible loss of hMSH2 expression, an observation that differs from studies on other populations. In conclusion, although the overall rate of CRC is unknown in this region, the frequency of MSI in CRC in this region appears to be the same as in Caucasians in the USA.     

错配修复基因突变检测对遗传性非息肉病性结直肠癌患病风险的预测

目的 探讨错配修复(MMR)基因种系突变检测在遗传性非息肉病性结直肠癌(HNPCC)家系成员患癌风险预测中的作用.方法 对43个携带致病性突变的HNPCC家系的316名家庭成员的发病情况进行详细调查,并对结果进行统计学分析.结果 ①突变状态明确的HNPCC家系年龄大于20岁的成员共263例,其中突变携带者144例,非携带者119例;HNPCC相关恶性肿瘤的发生率分别为59.03%(85/144)和2.52%(3/119),二者差异有统计学意义(X2=93.44,P＜0.01).②在144例年龄大于20岁的突变携带者中,男、女HNPCC相关恶性肿瘤发生率分别为72.00%(54/75)和44.93%(31/69),二者差异有统计学意义(χ~2=10.89,P＜0.01).③随着年龄的增加,突变携带者发生HNPCC相关肿瘤的累计风险度逐渐增加.结论 在HNPCC家系中,MMR基因种系突变携带者为发生HNPCC相关肿瘤的高危人群,MMR基因种系突变的检测能很好地预测HNPCC相关肿瘤的发生危险.     

Miniprobe Endoscopic Ultrasonography Has Limitations in Determining the T Stage in Early Colorectal Cancer

Background/Aims

Mini-probe endoscopic ultrasonography (mEUS) is a useful diagnostic tool for accurate assessment of tumor invasion. The aim of this study was to estimate the accuracy of mEUS in patients with early colorectal cancer (ECC).

Methods

Ninety lesions of ECC underwent mEUS for pre-treatment staging. We divided the lesions into either the mucosal group or the submucosal group according to the mEUS findings. The histological results of the specimens were compared with the mEUS findings.

Results

The overall accuracy for assessing the depth of tumor invasion (T stage) was 84.4% (76/90). The accuracy of mEUS was significantly lower for submucosal lesions compared to mucosal lesions (p=0.003) and it was lower for large tumors (≥2 cm) (p=0.034). The odds ratios of large tumors and submucosal tumors affecting the accuracy of T staging were 3.46 (95% confidence interval [CI], 1.05 to 11.39) and 6.25 (95% CI, 1.85 to 25.14), respectively. When submucosal tumors were combined with large size, the odds ratio was 14.67 (95% CI, 1.46 to 146.96).

Conclusions

The overall accuracy of T stage determination with mEUS was considerably high in patients with ECC; however, the accuracy decreased when tumor size was >2 cm or the tumor had invaded the submucosal layer.     

PET/CT Colonography for the Preoperative Evaluation of the Colon Proximal to the Obstructive Colorectal Cancer

Purpose  This study was designed to evaluate the usefulness of 18-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) colonography in preoperative diagnosis of the tumors proximal to obstructive colorectal cancers, which were defined as cancers that cannot be traversed colonoscopically. Methods  A whole-body PET/CT protocol for tumor staging and a protocol for CT colonography were integrated into one examination. No cathartic bowel preparation was used before this examination. Thirteen prospective patients with obstructive cancer were examined. We compared the detection rates for obstructive colorectal cancers and tumors proximal to the obstruction using air-inflated PET/CT colonography to intraoperative examinations, histopathologic outcome, and follow-up colonoscopy. Results  PET/CT colonography correctly identified all 13 primary obstructive colorectal cancers and all 2 synchronous colon cancers proximal to the obstruction. The two synchronous colon cancers detected at PET/CT colonography were confirmed and removed at single-stage surgical procedures. PET/CT colonography was able to localize all colorectal cancers precisely. There were no false-negative or false-positive proximal colorectal cancers by PET/CT colonography. Other preoperative examinations missed the synchronous colon cancers. Conclusions  In patients with obstructive colorectal cancers, preoperative PET/CT colonography provided valuable anatomic and functional information of the entire colon to properly address surgery of colorectal cancer.     

The role of cell-free DNA in predicting colorectal cancer prognosis

Introduction: Colorectal cancer is a cancer of the digestive system with poor prognosis. Cell-free DNA has received much attention with its unique predominance, especially in colorectal cancer.

Areas covered: This study has summarized recent advancements and challenges regarding cell-free DNA in predicting CRC prognosis. Furthermore, the authors make predictions on the potential developments concerning cell-free DNA in future prognosis prediction techniques.

Expert commentary: Cell-free DNA has the value of predicting CRC prognosis as an important biomarke. Further clinical trials should be performed to promote translating cell-free DNA into clinical applications.     

DNA Stool Test for Colorectal Cancer: Hypermethylation of the Secreted Frizzled-Related Protein-1 Gene

Purpose To investigate a potential mode of noninvasive screening for colorectal cancer, we evaluated the hypermethylation of the secreted frizzled-related protein-1 gene promoter in human stool DNA. Methods In stool samples from 36 patients with colorectal neoplasia (7 adenoma, 29 colorectal cancer) and 17 healthy control subjects, isolated DNA was treated with sodium bisulfite and analyzed by methylation-specific polymerase chain reaction with primers specific for methylated or unmethylated promoter sequences of the secreted frizzled-related protein-1 gene. Results Hypermethylation of the secreted frizzled-related protein-1 promoter was present in the stool DNA of patients with adenoma and colorectal cancer. A sensitivity of 89 percent and specificity of 86 percent were achieved in the detection of colorectal neoplasia. The difference in hypermethylation status of the secreted frizzled-related protein-1 promoter between the patients with colorectal neoplasia and the control group was statistically highly significant (P < 0.001). Adenoma and early tumor Stage I (International Union Against Cancer) displayed both unmethylated and methylated secreted frizzled-related protein-1 promoter sequences, whereas advanced tumor stages showed only methylated secreted frizzled-related protein-1 (P = 0.05). Conclusions The results indicate that this DNA stool test of hypermethylation of the secreted frizzled-related protein-1 promoter is a sensitive and specific method. It has the potential of a clinically useful test for the early detection of colorectal cancer. Supported by grants of the Funds for Research and Teaching (Elan-Fonds to W. Zhang) and by the Interdisciplinary Centre of Clinical Research (IZKF, Project A1 to M. Stürzl) of the University of Erlangen-Nuremberg, Germany. Presented at the Research Forum of The American Society of Colon and Rectal Surgeons, Seattle, Washington, June 3 to 7, 2006.     

TIP30基因启动子甲基化与大肠癌细胞5-氟尿嘧啶化疗敏感性的关系

目的探讨TIP30启动子CpG岛甲基化状态与大肠癌细胞对5-氟尿嘧啶(5-Fu)敏感性的关系。方法采用MTT法检测HCT116和HT29大肠癌细胞株对5-Fu的敏感性。应用甲基化特异性PCR(MSP)方法,检测2细胞株对5-Fu敏感性有差异的大肠癌细胞株中TIP30基因启动子CpG岛甲基化状态,并用RT-PCR检测其mRNA的表达水平。结果 TIP30基因在HCT116及HT29癌细胞中甲基化状态有差异,其表达水平与启动子CpG岛甲基化状态有关,并且二者对5-氟尿嘧啶敏感度不同。结论 TIP30基因启动子甲基化状态可能影响大肠癌细胞对化疗药物的敏感性,为大肠癌患者的个体化治疗提供了可能。     

Flat-Type Early Colorectal Cancer Preferentially Develops in Right-Sided Colon in Older Patients

BACKGROUND Flat-type colorectal cancer is frequently reported in Japan and Europe, but its clinical features remain obscure. Thus, we investigated the clinical features of flat-type early colorectal cancer with respect to tumor location and patient age and compared them with those of polypoid-type early and advanced cancer.METHODS Between January 1999 and June 2001, total colonoscopy was performed in 6,178 patients (mean age, 61 years; 4,290 males and 1,888 females). Of these patients, 402 patients with 429 colorectal cancers were found: 202 at advanced stage (invading beyond muscularis propria) and 227 at early stage (carcinoma in situ or invading within submucosa). Early-stage cancer was classified into two macroscopic subgroups: flat-type and polypoid-type.RESULTS Out of 227 early cancers, 44 were flat type and 183 were polypoid. Flat-type early cancer was more frequently located in the right colon (57 percent, 25/44) than polypoid-type cancer (19 percent, 35/183; P < 0.001). Adenomatous component in flat-type early cancer was less frequent than in polypoid-type cancer (23 percent vs. 92 percent, P < 0.001). The proportion of right-sided colon in flat-type early cancer increased with age (33 percent in patients 59 years, 50 percent in patients between 60 and 69 years, and 72 percent in patients 70 years), whereas polypoid-type early cancer showed minimal change (16 percent, 18 percent, and 25 percent, respectively). An increase in the proportion of right-sided colon with age was also found in advanced cancer (20 percent, 38 percent, and 52 percent, respectively).CONCLUSION The incidence of flat-type early cancer in right-sided colon increased with age, similar to the pattern of advanced cancer. This suggests that flat-type early cancer may be a precursor of advanced cancer in the right colon, especially in older people.Presented in part at the meeting of the American Gastroenterological Association, San Diego, California, May 14 to 17, 2000.     

Colonic Vascular Anomalies and Colon Cancer in Neurofibromatosis: Report of a Case

We report a case of neurofibromatosis with synchronous adenocarcinomas in the sigmoid and transverse colon. There was widespread intimal proliferation in arteries in the region of the tumors and also in the cecum. Such vascular lesions are associated with von Recklinghausen’s disease. The cecal lesion produced mural thickening visible on computed tomography. This case supports a possible genetic link between neurofibromatosis and adenocarcinoma of the colon.     

S-腺苷蛋氨酸对人胃癌细胞系增殖及c-myc、uPA基因甲基化的影响

目的 观察S-腺苷蛋氨酸(SAM)对体外培养的人胃癌细胞的细胞周期、凋亡以及侵袭力的影响,及对细胞中c-myc基因和尿激酶型纤溶酶原激活剂(uPA)基因甲基化状态及表达的影响.方法 用不同浓度(0、2、4 mmol/L)SAM处理体外培养的MKN-28、SGC-7901和MKN-45细胞72h,用流式细胞仪检测各组细胞周期分布和细胞凋亡率;Transwell法检测各组细胞侵袭力的改变;RT-PCR法检测各组细胞c-myc基因和uPA基因mRNA表达的变化;甲基化特异性PCR法检测各组细胞中c-myc基因和uPA基因的甲基化状态.结果随SAM浓度增加,3种细胞凋亡率均明显增加(P值均<0.01),侵袭力均受到明显抑制(P值均<0.01).与对照组相比,SGC-7901细胞G0/G1期细胞明显增加[(56.67±1.18)%比(74.53±2.49)%,P<0.01],细胞增殖指数(PI)明显降低[(43.33±1.18)%比(25.50±2.46)%,P<0.01].随SAM浓度增加,SGC-7901细胞c-myc和uPA基因及MKN-45细胞的uPA基因mRNA表达明显减弱(P值分别<0.05和<0.01),经SAM 4mmol/L处理的MKN-28细胞的uPA基因mRNA表达亦明显减弱(P<0.01).经SAM处理的SGC-7901细胞c-myc基因和3种细胞的uPA基因均部分甲基化或完全甲基化.结论 SAM可通过逆转SGC-7901细胞c-myc基因和3种细胞uPA基因的低甲基化状态,从而调控基因的表达,并可通过提供甲基,改善基因的低甲基化状态,达到抑制胃癌细胞生长、增殖和侵袭的作用.     

5-Lipoxygenase is Coexpressed with Cox-2 in Sporadic Colorectal Cancer: A Correlation with Advanced Stage

Purpose It has been extensively documented that the cyclooxygenase inducible form and 15-lipoxygenase are implicated in colorectal carcinogenesis. Nonetheless, the role of other enzymes involved in the arachidonic acid metabolism, such as 5-lipoxygenase, in colorectal neoplasms has not been fully ascertained. This study was designed to evaluate 5-lipoxygenase expression in sporadic colorectal adenocarcinomas by using immunohistochemistry and to analyze its potential correlations with clinicopathologic parameters and with cyclooxygenase-2 expression. Methods Expression of 5-lipoxygenase and cyclooxygenase-2 were evaluated by immunohistochemistry in 50 surgically resected sporadic colorectal adenocarcinomas (28 male and 22 female patients age range, 47–88 (mean age, 69 ± 8) years). The chi-squared and Spearman correlation tests were used to analyze correlations with clinicopathologic characteristics and to evaluate any relationships between expression of the two enzymes. P values <0.05 were considered statistically significant. Results 5-Lipooxygenase and cyclooxygenase-2 immunostaining was found in the cytoplasm of neoplastic cells in 41 (82 percent) and in 43 cases (86 percent), respectively. Spearman correlation test demonstrated a positive correlation in the expression of the two enzymes. A statistically significant correlation also was observed between 5-lipoxygenase expression and tumor stage and lymph node metastasis, whereas no significant correlations emerged regarding cyclooxygenase-2 expression and clinicopathologic parameters. Conclusions Our study demonstrates that 5-lipoxygenase is expressed in colorectal adenocarcinomas in association with cyclooxygenase-2 expression. Moreover, an elevated expression of this enzyme seems to be significantly correlated with tumor aggressiveness. Further studies would clarify the need for target therapies inhibiting both metabolic pathways in such tumors. Supported by the grants from the University of Messina, Messina, Italy. Presented at the meeting of the Italian Society of Anatomic Pathology and Diagnostic Cytopathology (SIAPEC), Venice, Italy, October 4 to 5, 2006.     

前列腺癌组织中多基因异常甲基化检测及临床意义

目的 探讨前列腺癌组织中RARβ2、GSTP1和DAPK基因异常甲基化,与前列腺临床病理特征间的关系,及其在前列腺癌诊断中价值.方法 采用巢式甲基化特异性PCR(nestedmethylationspecificpolymerasechainreaction,NMSP)法对57例前列腺痛组织和35例良性前列腺增生(BPH)组织进行甲基化检测;分析其甲基化的发生与前列腺癌临床病理特征间的关系,以及在前列腺癌诊断中价值.结果 前列腺癌组织中RARβ2、GSTPI和DAPK基因甲基化检出率显著高于BPH组织(RARβ32:52.6%对0%;GSTPl:61.4%对2.9%;DAPK:43.9%对8.6%;均P<0.01).RARβ2基因甲基化率在前列腺癌不同Gleason评分和不同临床分期之间差异有统计学意义(4～7分对8～10分:34.8%对64.7%,B、C期对D期:37.0%对66.7%,x2=4.927和x2=5.004,P=0.026和P=0.025);GSTP1基因甲基化率在不同Gleason评分间差异有统计学意义(4～7分对8～10分:43.5%对73.5%,x2=11.530,P=0.001),而在不同临床分期之间差异无统计学意义(B、C期对D期:51.9%对70.0%,x2=1.975,P=0.16);DAPK基因甲基化率在不同Gleason评分和不同临床分期之间差异均无统计学意义(4～7分对8～lO分:39.1%对50.0%,B、C期对D期:33.3%对53.3%,x2=1.290和x2=2.309,均P>0.05).GSTP1基因诊断敏感度最高为61.4%(35/57),特异度为97.1%(34/35);RARβ2基因特异度最高为100%(35/35),敏感度为52.6%(30/57);DAPK基因的诊断敏感度和特异度分别为43.9%和91.4%(25/57和32/35).而RARβ2、GSTP1和DAPK基因甲基化联合检测能明显提高前列腺癌诊断敏感度,但诊断特异度却有所下降.结论 RARβ2、GSTP1和DAPK基因异常甲基化与前列腺癌的发生与发展相关,可作为前列腺癌的诊断有效指标之一.