中国人原发性胆囊肿瘤nm23H1基因遗传不稳定性的研究

采用石蜡包埋组织抽提DNA,PCR-单链构象多态性(PCR-SSCP),常规银染,Envision免疫组织化学和Leica-Qwin计算机图像分析等方法,研究人类17号染色体D17S396位点微卫星不稳定性(microsatelliteinstablility,MSI)和杂合性缺失(lossofheterozygosity,LOH),对胆囊肿瘤nm23H1蛋白表达的影响,阐明nm23H1基因遗传不稳定性与胆囊肿瘤进展的关系,为揭示nm23H1基因与肿瘤发生和转移机理提供实验依据。在本实验中,原发性胆囊癌D17S396位点遗传不稳定发生率为42.55%,明显高于良性胆囊肿瘤的13.04%,而在胆囊炎组织中,未见该位点遗传不稳定的发生;其中,LOH的发生率随组织恶性程度的增高而增加(P<0.05)。在胆囊癌中,LOH和MSI发生率与肿瘤组织分化程度具有显著差异(P<0.05);LOH的发生率,在肝脏浸润和淋巴转移组高于无肝脏浸润和无淋巴转移组,在NevinⅣ Ⅴ期高于Ⅰ Ⅱ Ⅲ期(P<0.01);而MSI发生率则相反。nm23H1蛋白阳性率在胆囊癌、胆囊良性肿瘤和炎症组织中差异显著(P<0.05);在胆囊癌中,淋巴转移组低于无淋巴转移组(P<0.01);NevinⅣ Ⅴ期低于Ⅰ Ⅱ Ⅲ期(P<0.05)。此外,计算机图像定量分析显示,在各临床病理参数影响下,nm23H1蛋白的表达强度没有差异。在胆囊癌中,LOH阳性组中nm23H1蛋白阳性率显著低于LOH阴性组,两者差异显著(P<0.05)。实验结果提示,nm23H1基因的遗传不稳定性可能是胆囊肿瘤发生、发展的一个重要机制。nm23H1基因的MSI和LOH,通过相互独立的途径调控胆囊癌的发生和转移,MSI是胆囊癌早期分子指标,LOH可作为胆囊组织恶变的判断指标,可抑制胆囊癌局部nm23H1蛋白的表达,并赋予胆囊癌高淋巴结转移、低预后的特性。提高胆囊癌局部nm23H1蛋白的表达,可减缓肿瘤的浸润转移并提高预后率。     

Polymorphism in protein tyrosine phosphatase receptor delta is associated with the risk of clear cell renal cell carcinoma

Clear cell renal cell carcinoma (ccRCC) is a common urological malignancy. Our previous study has indicated that the protein tyrosine phosphatase receptor type delta (PTPRD) gene may play a role. To determine the effect of PTPRD genetic polymorphisms on ccRCC occurrence and progression, a total of 377 ccRCC cases and 754 matched controls were enrolled in the study. DNA sequencing and genotyping, and immunohistochemistry were conducted to test the associations of genotypes with ccRCC risk and PTPRD expression level in somatic tissues. The C allele of PTPRD rs2279776 was associated with a higher risk of ccRCC (per allele OR = 1.23, P = 0.03). Patients without distant metastasis at the time of surgery were followed for a median of 33.1 months. Overall survival was not different between different rs2279776 genotype groups (P = 0.30). The C allele was associated with a higher percentage of negative immunostaining in adjacent normal renal tissues (P = 0.02). PTPRD rs2279776 SNP may be a novel genetic risk factor of ccRCC.     

Polymorphism of estrogen response element in TFF1 gene promoter is associated with an increased susceptibility to gastric cancer

TFF1 is a cysteine-rich protein that forms a characteristic trefoil domain through disulfide bonds, which render it resistant to vigorous conditions and it involves in maintaining the integrity of the gastric mucosa. Decreased expression of TFF1 gene plays a role in the development of gastric cancer. We examined the association between the promoter polymorphisms of the TFF1 gene and the risk of development of gastric cancer, in a case-control study including 199 controls and 141 patients with gastric cancer. Assessment of single nucleotide polymorphisms in the promoter region of the TFF1 gene was performed by sequencing and polymerase chain reaction-based restriction fragment length polymorphism. We found a statistically significant increased risk of gastric cancer associated with − 394 TT genotypes (OR = 8.78, CI = 2.85-27.05, p < 0.001) and CT (OR = 1.64, CI = 1.04-2.60, p = 0.033). This single nucleotide polymorphism occurs naturally in an estrogen response element. According to induction of the TFF1 gene by estrogen, it is possible that the substitution of C to T results in a decreased estrogen receptor binding affinity to the estrogen response element and in turn it decreases the expression of the TFF1 gene that may be involved in development of gastric cancer over a lifetime.     

Clinical and biological significance of Cdk10 in hepatocellular carcinoma

Cyclin-dependent kinase 10 (Cdk10) is a Cdc2-related kinase and plays an essential role in the progression from the G2 to M phase of the cell cycle. However, relative little is known about its expression pattern, clinical relevance, and biological function in hepatocellular carcinoma (HCC). In the present study, we investigated the mRNA and protein expression levels of Cdk10 in 127 pairs of HCC samples and adjacent nontumorous liver tissues and evaluated its clinical significance. Additionally, we assessed the effects of restoration of Cdk10 on cell proliferation and drug sensitivity in HCC cells. We showed that the Cdk10 mRNA and protein expression was markedly decreased in HCC samples compared to adjacent nontumorous liver tissues. Quantitative real-time polymerase chain reaction and immunohistochemical studies revealed that reduced Cdk10 expression was significantly associated with alpha-fetoprotein levels, tumor size, and tumor stage. Ectopic expression of Cdk10 reduced HCC cell proliferation, blocked the cell cycle at the G0-G1 phase, as well as inhibited cell migration and anchorage-independent growth. Additionally, Cdk10 overexpression enhanced the chemosensitivity of HCC cells to cisplatin and epidoxorubicin, two chemotherapeutic agents commonly used in HCC. These data collectively demonstrate that reduced Cdk10 expression is closely linked to HCC development and progression. Restoration of its expression may have therapeutic benefits in treating this malignancy.     

Somatic recombination in adult tissues: What is there to learn?

Somatic recombination is essential to protect genomes of somatic cells from DNA damage but it also has important clinical implications, as it is a driving force of tumorigenesis leading to inactivation of tumor suppressor genes. Despite this importance, our knowledge about somatic recombination in adult tissues remains very limited. Our recent work, using the Drosophila adult midgut has demonstrated that spontaneous events of mitotic recombination accumulate in aging adult intestinal stem cells and result in frequent loss of heterozygosity (LOH). In this Extra View article, we provide further data supporting long-track chromosome LOH and discuss potential mechanisms involved in the process. In addition, we further discuss relevant questions surrounding somatic recombination and how the mechanisms and factors influencing somatic recombination in adult tissues can be explored using the Drosophila midgut model.     

Identification of different tumor escape mechanisms in several metastases from a melanoma patient undergoing immunotherapy

The cytotoxic activity of T cells selects the outgrowth of tumor cells that escape from immune surveillance by different strategies. The different mechanisms that interfere with immune recognition and limit vaccination efficiency are still poorly understood. We analysed six cell lines established from different metastases of melanoma patient UKRV-Mel-20 for specific characteristics known to have an impact on the tumor-T cell interaction: (1) alterations in the HLA class I phenotype, (2) expression of Fas/CD95, and (3) expression of specific cytokines and chemokines. One of the cell lines, UKRV-Mel-20f, exhibited an HLA class I haplotype loss and just this cell line was also characterised by the expression of Fas/CD95 and of relatively high levels of proinflammatory chemokines suggesting that the cytotoxic activity of tumor-infiltrating T cells might have selected the outgrowth of this tumor cell variant. All other cell lines analysed showed no alterations in HLA class I expression, but, in contrast to UKRV-Mel-20f, expressed much lower levels of Fas/CD95 and of proinflammatory chemokines and some of them produced high levels of immunosuppressive TGF-beta1. These results suggest that in patient UKRV-Mel-20, tumor cells interfere with T cell recognition by different strategies which might partially explain why this patient did not have a clinical response to an autologous tumor cell vaccine.     

Integrative analysis and validation of robust gene signature in lung cancer

We studied robust gene signature (RGS) in lung cancer by using an approach of integrating a highly diverse collection of cancer genome-wide datasets, which were six public microarray datasets, one pair of Suppression Subtractive Hybridization EST library, one pair of Serial Analysis of Gene Expression (SAGE) experiments, and 191 Loss of Heterozygosity (LOH) reports obtained from 388 publications. Among the 109 RGS genes identified from our study, 14 of the 15 reported differentially expressed genes (DEGs) based on literature verification were consistent with our predictions. Out of the remaining 94 genes that were not reported as DEGs in lung cancer by any publication, we randomly picked eight and verified their expression in lung cancer versus normal tissues by semi-quantitative RT-PCR amplification, and all showed consistent expression pattern with our findings. System assessment analysis revealed that our integrative method had an accuracy of 95% and a correlation coefficients value of 0.92.     

Analysis of p16 expression and allelic imbalance / loss of heterozygosity of 9p21 in cutaneous squamous cell carcinomas

Deletions of the short arm of chromosome 9 have been reported in different types of malignancies. This chromosomal region contains a number of known tumour suppressor genes, including the p16INK4A (CDKN2A), p15INK4B and MTAP tumour suppressor genes located at 9p21. In this study twenty-two paraffin embedded invasive cutaneous SCC were examined for allelic imbalance/ loss of heterozygosity (AI/LOH) of the 9p region (in particular 9p21), and for p16 protein expression. DNA was isolated from microdissected sections of normal and tumour cells and analysed for AI/LOH by using six fluorescently labelled microsatellite markers that map to the 9p region. P16 protein expression was examined by immunohistochemistry. At each of the six microsatellite markers the majority of SCC analysed showed AI/LOH. Overall both AI/LOH within the CDKN2A locus and absence of p16 protein expression were frequent among the cutaneous SCC analysed, suggesting that p16 inactivation may play a role in cutaneous SCC development. The majority of the SCC analysed also had AI/LOH of the marker within the MTAP gene, and at markers flanking the CDKN2A gene; thus further investigation as to a possible role for these genes in the development of cutaneous SCC is warranted.