肝细胞癌中ZHX2基因启动子甲基化增强AFP的表达

目的探讨肝细胞癌中锌指和同源框2(ZHX2)基因启动子甲基化表达与血清AFP水平的关系,分析AFP基因的表达调控机制。方法以0.5、1.0及5.0μmol/L甲基化抑制剂5-氮杂脱氧胞苷(5-Aza-Dc)培养人肝癌细胞株HepG2,采用RT-PCR及Western blot法检测用药前后ZHX2及AFP基因的mRNA和蛋白表达差异。运用甲基化特异性PCR检测肝细胞癌组织38例中ZHX2基因启动子表达情况,分析其与血清AFP水平的关系。结果 HepG2可见少量ZHX2 mRNA扩增,未检测到ZHX2蛋白表达,而AFP却高表达;应用终浓度为1.0μmol/L和5.0μmol/L的5-Aza-Dc处理肝癌细胞6 d,ZHX2表达明显增加,而AFP却表达下调。血清AFP高于25 ng/mL肝细胞癌组织中ZHX2启动子甲基化51.6%,明显高于血清AFP小于25 ng/mL组(P<0.05)。结论 ZHX2基因启动子甲基化与AFP基因的表达有关。     

Promoter hypermethylation and expression of sprouty 2 in endometrial carcinoma

Sprouty 2 is a key antagonist regulator of receptor tyrosine kinases, and downstream signaling pathways, like fibroblastic growth factor (FGF) and Ras-mitogen-activated protein kinase (RAS-MAPK). By controlling these pathways, sprouty 2 is involved in regulation of cell proliferation, differentiation, and angiogenesis. Alterations in fibroblastic growth factor receptor (FGFR) and members of the RAS-MAPK pathway are frequent in endometrial carcinoma. The expression of sprouty 2 has been found to be decreased in several types of human cancer, by mechanisms of promoter methylation. In the present study, we have assessed the expression of sprouty 2 in endometrial carcinoma, in correlation with sprouty 2 promoter methylation. Sprouty 2 immunohistochemical expression was assessed using 3 different tissue microarrays: one constructed from paraffin blocks of 80 samples of normal endometrium and 2 tissue microarrays containing samples of 157 endometrial carcinoma (1 tissue microarray constructed with 95 endometrial carcinomas previously studied for microsatellite instability and alterations in phosphatase and tensin homolog (PTEN), k-ras, and b-catenin, and 1 tissue microarray containing 62 endometrial carcinoma, which were also subjected to sprouty 2 promoter methylation analysis). The immunohistochemical expression of sprouty 2 was correlated with cellular proliferation (Ki67) and clinicopathologic data. Sprouty 2 promoter methylation was assessed by methylation-specific polymerase chain reaction, with DNA obtained from fresh-frozen samples of endometrial carcinoma and corresponding normal tissues, and correlated with promoter methylation of RAS association domain family-1A (RASSF1A). A highly significant decrease in sprouty 2 immunoexpression was seen in the proliferative phase of normal endometrium (P < .001). Differences were detected between types I and II endometrial carcinoma, but they were not statistically significant. Reduced immunoexpression of sprouty 2 was seen in 19.85% of endometrial carcinoma and was strongly and inversely associated with increased cell proliferation (Ki67; r = -0.367; P = .001). Sprouty 2 promoter methylation was detected in 31 (53.4%) of 58 endometrial carcinomas. Results from our study show that alterations in sprouty 2 may be involved in endometrial carcinogenesis by controlling cell proliferation.     

Promoter hypermethylation of the RB1 gene in glioblastomas

Loss of expression of the retinoblastoma gene (RB1) has been shown to occur in up to 25% of glioblastomas (WHO Grade IV). To elucidate the underlying mechanism, we assessed RB1 promoter hypermethylation using methylation-specific polymerase chain reaction and RB1 expression by immunohistochemistry in 35 primary (de novo) glioblastomas and in 21 secondary glioblastomas that had progressed from low-grade diffuse astrocytoma (WHO Grade II) or anaplastic astrocytoma (WHO Grade III). Promoter hypermethylation was significantly more frequent in secondary (9 of 21, 43%) than in primary glioblastomas (5 of 35, 14%; p = 0.0258). There was a clear correlation between loss of RB1 expression and promoter hypermethylation. In the majority of glioblastomas with loss of RB1 expression, there was promoter hypermethylation (11 of 13, 85%), whereas 93% of tumors with RB1 expression had a normal RB1 gene status (p < 0.0001). In three glioblastomas, areas with and without RB1 expression were microdissected; promoter hypermethylation was detected only in areas lacking RB1 expression. In patients with multiple biopsies, methylation of the RB1 promoter was not detectable in the less malignant precursor lesions, ie, low-grade diffuse and anaplastic astrocytoma. These results indicate that promoter hypermethylation is a late event during astrocytoma progression and is the major mechanism underlying loss of RB1 expression in glioblastomas.     

Promoter hypermethylation and inactivation of hMLH1, a DNA mismatch repair gene, in head and neck squamous cell carcinoma.

Head and neck squamous cell carcinoma (HNSCC) is a multistage process during which adverse genetic alterations accumulate resulting in loss of cell cycle control, selective cell overgrowth, and ultimately formation of malignancy. Among various genetic alterations in HNSCC is increased microsatellite instability (MSI). hMLH1 is one of the major mismatch DNA repair genes, the inactivation of which caused increased MSI in a variety of human cancers including HNSCC. While somatic mutation is a major mechanism of the hMLH1 gene inactivation in hereditary form of human cancer, promoter hypermethylation appears to be primarily involved in the inactivation of the hMLH1 gene in sporadic form of human cancers. In the current study, we analyzed 78 cases of HNSCC for hMLH1 protein expression and promoter hypermethylation by IHC and methylation-specific PCR (MSP). Twenty-four of 78 cases (31%) of HNSCC contained markedly reduced levels of the hMLH1 protein. Based on the IHC results, 8 cases without and 8 with hMLH1 protein expression (total of 16) were further analyzed by MSP. Seven of 8 cases (88%) that were negative for the hMLH1 protein displayed promoter hypermethylation, whereas 7 of 7 cases (100%) strongly positive for the protein were free of promoter methylation. This study confirms our previous conclusion that promoter hypermethylation represents a major mechanism of the hMLH1 gene inactivation in HNSCC.     

Juvenile hemochromatosis and hepatocellular carcinoma in a patient with a novel mutation in the HJV gene

Juvenile hemochromatosis is a rare but the most severe form of hereditary hemochromatosis which develops due to mutations in the HJV or HAMP genes. It presents in the early adulthood mainly as cardiomyopathy, hypogonadism and liver fibrosis. Unlike hereditary hemochromatosis due to HFE mutation, hepatocellular carcinoma is not known to be associated with juvenile hemochromatosis. Here, we report a patient of Arab ancestry who presented with severe cardiomyopathy. Sequence analysis of the HJV gene followed by homozygosity mapping, identified a previously undescribed homozygous missense variation in exon 3 (c.497A > G; p.H166R) in both the proband and his clinically asymptomatic brother. The former, later developed hepatocellular carcinoma. To the best of our knowledge, neither the mutation identified in our patient, nor a case of juvenile hemochromatosis with hepatocellular carcinoma has been reported before.     

结直肠癌中ZHX2蛋白表达的检测及其临床病理意义

目的检测结直肠癌中ZHX2蛋白的表达情况,探讨ZHX2与结直肠癌的关系。方法利用免疫组化法分别检测73例结直肠癌组织及其对应的癌旁正常组织中的ZHX2蛋白的表达情况。结果 73例结直肠癌组织中ZHX2蛋白的阳性率为82.2%(60/73),癌旁正常组织中ZHX2蛋白的阳性率为94.5%(69/73),差异具有统计学意义(P<0.05)。在结直肠癌组织中,ZHX2蛋白的阳性表达与肿瘤的发生部位及分化程度有关(P<0.05),与性别、年龄、肿瘤大小、浸润深度、淋巴结转移及Dukes分期无关(P>0.05)。ZHX2(+)组患者的生存时间长于ZHX2(-)组(P<0.05)。结论 ZHX2作为一种转录抑制因子,可能参与结直肠癌的发生与演进,并有助于患者预后的判断。     

ZHX2的研究进展

新型转录抑制因子ZHX2（zinc-fingers and homeoboxes 2,ZHX2）属于锌指和同源框（zinc-fingers and homeoboxes,ZHX）家族,广泛存在于各种组织细胞核内,发挥转录抑制作用。ZHX2与多发性骨髓瘤（multiple mye-loma,MM）和肝细胞癌（hepatocellular carcinoma,HCC）的发生发展密切相关。此外,ZHX2对肾脏疾病发展过程中基因表达的转录调控有重要作用。ZHX2亦参与大脑皮层发育过程中神经前体细胞维持的调控。     

Parkin gene alterations in hepatocellular carcinoma

The Parkin gene is an extremely large gene (1.5 Mb) within the highly unstable FRA6E common fragile site (CFS) region, which is frequently altered in ovarian, breast, and hepatocellular carcinomas. Because Parkin/FRA6E has genomic similarities to FHIT/FRA3B and WWOX/FRA16D, two other large tumor-suppressor genes that are within CFS regions, we were interested in characterizing Parkin gene alterations and their possible association with cancer. After analyzing 50 cancer-derived cell lines including 11 hepatocellular carcinoma (HCC) cell lines, we found that one HCC cell line, PLC/PRF/5, had a detectable homozygous deletion encompassing exon 3. Using quantitative duplex PCR and fluorescence in situ hybridization analysis to characterize the copy number changes of Parkin exons in HCC cell lines, we found that 4 of 11 HCC cell lines had heterozygous deletions of Parkin exons and one, Hep3B, had an exon duplication. Parkin protein expression was significantly decreased or absent in all 11 HCC cell lines. Furthermore, more than 50% of HCC primary tumors had decreased Parkin expression compared to that in normal liver tissue. Parkin gene-transfected PLC5 and Hep3B cells grew more slowly than vector-only transfectants and also showed increased sensitivity to apoptosis induced by cell-cycle inhibitors. Therefore, we suggest that Parkin may be involved in tumor suppression and that the loss of Parkin contributes to the development of hepatocarcinoma.     

家族性腺瘤性息肉病患者APC基因启动子区异常甲基化及大片段结构异常

目的 研究3个家族性腺瘤性息肉病(familial adenomatous polyposis,FAP)家系的腺瘤样息肉病(adenomatus polyposis coli)基因(APC)启动子1A区异常甲基化及DNA大片段结构异常.方法 对3个FAP家系成员的肿瘤组织标本和正常组织标本DNA进行化学修饰,应用甲基化特异PCR(methylation-speeif-ic PCR,MsP)和DNA序列分析方法筛查APC基因启动子1A区甲基化情况.采用多重连接依赖性探针扩增(multiplex ligation-dependent probe amplification,MIPA)分析系统检测5例FAP患者肿瘤组织标本和正常标本的APC基因的15个外显子及启动子区DNA大片段结构异常.结果 在1个家系中发现2例患者存在APC基因启动子1A区异常甲基化.同一个家系中另1例患者存在APC基因全基因杂合性缺失.结论 APC基因启动子1A区异常甲基化可影响APC功能,可能是结直肠癌进展过程中的早期事件;大片段缺失可能是导致典型FAP的一个因素.     

Promoter hypermethylation and loss of heterozygosity of the APC gene in patients with familial adenomatous polyposis

OBJECTIVE: To investigate the status of hypermetne in 3 familial adenomatous polyposis (FAP) pedigrees and to screen large fragment deletions in the APC gene. METHODS: DNA from tumor tissues and corresponding normal tissues of 5 FAP patients was modified by sodium bisulfite. Then the methylation status of the APC gene was analyzed by methylation specific-PCR (MSP) and DNA sequencing. Multiplex ligation-dependent probeamplification (MLPA) was used to screen aberrations involving large fragments from all the 15 exons and promoter region of APC gene. RESULTS: No methylation was present in normal tissues. Hypermethylation was found in tumor tissues of one proband and her son. Loss of heterozygosity was observed in another patient from the same FAP family. CONCLUSION: Aberrantmethylation of the APC promoter region provides an important mechanism for impairing APC function and may occur early during colon neoplasia progression. Loss of heterozygosity may play a role in patients with classical polyposis.     

Circulating prostaglandin E2: a novel potential prognostic biomarker in patients with hepatocellular carcinoma

Clinical and Experimental Medicine - We aimed to explore the activation of monoacylglycerol lipase (MAGL)/cyclooxygenase-2 (COX-2)/prostaglandin E2 (PGE2) axis in hepatocellular carcinoma (HCC),...     

Loss of RhoGDI is a novel independent prognostic factor in hepatocellular carcinoma

RhoGDI (Rho GDP-dissociation inhibitor alpha or RhoGDIα) has been identified as a regulator of Rho GTPases, which are essential for tumor progression, but its role in cancer remains controversial and little is known in hepatocellular carcinoma (HCC). Using immunohistochemistry, we analyzed RhoGDI expression in 147 clinicopathologically characterized HCC cases. RhoGDI expression was detected in cytoplasm of HCC tissues. Statistical analysis showed that there was no relationship between RhoGDI expression and clinicopathological features. Importantly, a significant trend was identified between loss of RhoGDI expression in HCC and worsening clinical prognosis. Multivariate survival analysis showed that negative RhoGDI expression was recognized as an independent prognostic factor of patient’s survival. Our results suggest that RhoGDI protein is a valuable marker of prognosis for patients with HCC.     

Analysis of alterations of WFDC1, a new putative tumour suppressor gene,in hepatocellular carcinoma

WFDC1 is a recently isolated human gene identified as a tumour suppressor gene candidate. It is not known whether alterations in this gene are associated with human cancers. The WFDC1 gene maps in human chromosome 16q24, an area of frequent loss of heterozygosity (LOH) in several tumour types, in particular in hepatocellular carcinoma (HCC). We investigated its role in 46 European HCC by means of the detection of LOH at the WFDC1 locus. We describe here an assay for the detection of loss of heterozygosity at this locus using two dinucleotide repeat polymorphisms identified in WFDC1 introns, with a combined informativity of 86%. LOH was observed in 4/40 informative HCC samples. We further investigated the role of WFDC1 as a tumour suppressor gene candidate in five hepatocellular cell lines and in tumours exhibiting LOH by means of mutation, promoter methylation and gene expression analysis. In HCC samples showing LOH, no mutation of the remaining allele was observed. No significant up or down gene expression was observed in tumour samples comparatively to normal liver and gene expression did not seem related to promoter methylation. These results suggest a minor role, if any, of WFDC1 in hepatocarcinogenesis. However, this approach might be useful for investigating the role of this candidate tumour suppressor gene in other tumour types.     

Promoter hypermethylation and reduced expression of RASSF1A are frequent molecular alterations of endometrial carcinoma.

Alterations in the regulation of the RAS-MAPK pathway are frequent in endometrial carcinoma. RASSF1A is a tumor-suppressor gene that can regulate this pathway negatively. RASSF1A has been found to be inactivated by promoter methylation in some human tumors. The aim of the study was to assess the immunohistochemical expression of RASSF1A in normal endometrium and endometrial carcinoma, and to correlate its expression with K-RAS mutations, presence of microsatellite instability, RASSF1A promoter methylation, and clinicopathological data. RASSF1A immunostaining was evaluated in one tissue microarray constructed from 80 paraffin-embedded samples of normal endometrium, and two tissue microarrays constructed with a total of 157 endometrial carcinomas (one constructed with 95 endometrial carcinomas previously evaluated for K-RAS mutations, and microsatellite instability, and another one containing 62 endometrial carcinomas that were also subjected to RASSF1A promoter methylation analysis). RASSF1A immunostaining was correlated with cell proliferation (Ki67), Cyclin D1 expression and clinicopathological data. Promoter methylation of RASSF1A was assessed by methylation-specific PCR. RASSF1A immunostaining was variable during the menstrual cycle in normal endometrium. RASSF1A expression was significantly reduced in 48% of endometrial carcinomas, particularly in tumors exhibiting microsatellite instability. RASSF1A-promoter methylation was very frequent in endometrial carcinoma (74%), and was frequently associated with reduced expression of RASSF1A. RASSF1A-promoter hypermethylation was common in advanced-stage endometrial carcinoma. The results suggest that reduced expression of RASSF1A may play a role in endometrial carcinogenesis by controlling cell proliferation and apoptosis through the MAPK-signaling pathway.     

Adult-type hepatocellular carcinoma in the center of a fibrolamellar hepatocellular carcinoma

A large hepatic tumor was detected in the noncirrhotic liver of a 27-year-old female patient. The tumor was radiologically characterized by a peripheral mass encircling a central ovoid tumor, and was resected by an extended right hemihepatectomy. Histologic examination revealed that the peripheral and major component of the tumor represented a fibrolamellar hepatocellular carcinoma, whereas the central, well-demarcated tumor was a less well-differentiated adult-type hepatocellular carcinoma completely encircled by the former. Cells of the peripheral tumor mass abundantly expressed cytokeratin-7, typically present in the fibrolamellar variant, whereas no cytokeratin-7 immunoreactivity was found in the central tumor. To our knowledge, this is the first reported case of a not admixed but clearly separated evolution of these 2 histologic patterns within the same tumor, and suggests that the 2 types of hepatocellular carcinoma may share a common pathogenic pathway.     

胎儿性RNA结合蛋白p62在肝细胞癌中表达的意义

目的　探讨表达p6 2的肝癌组织的病理形态学特点 ,以及 p6 2与癌细胞增殖和转移等生物学特性的关系。方法　用免疫组织化学方法检测 4 0例原发性肝细胞肝癌 p6 2和Ki 6 7的表达。结果　p6 2阳性率是 6 7.5 % (2 7/ 4 0 ) ,其中 p6 2强阳性表达的 12例中 9例为肝癌病理学分级为Ⅲ级的病例。p6 2表达强阳性的癌组织往往间质有大量的纤维组织或有大片坏死癌细胞 ,其增殖活性也高 ,Ki 6 7标记指数为 2 8 3%± 15 1% ,与 p6 2表达阴性组 (7 5 %± 9 8% )比较 ,差异具有显著性意义 (t=3 0 87,P =0 0 0 5 ) ;5例有肺转移或腹腔淋巴结转移的病例 ,其中 3例p6 2表达强阳性。结论　p6 2的表达与癌细胞的增殖和转移有一定的关系 ,和间质纤维组织较多的微环境有关