Expression of the angiopoietins and their receptor Tie2 in human renal clear cell carcinomas; regulation by the von Hippel-Lindau gene and hypoxia

Angiogenesis is essential for tumour growth and metastasis, and is co-ordinated by several classes of angiogenic factors. To determine the significance and regulation of the angiopoietin (Ang) pathway in highly vascular human renal cell carcinomas (RCCs), this study has investigated the expression of the Ang-1, Ang-2, Ang-4, and Tie2 genes in a series of normal (n = 26) and neoplastic (n = 45; clear cell n = 35, papillary n = 10) human kidney tissues, examined the pattern of Ang-2 and Tie2 protein expression, and correlated expression with clinicopathological variables. The effect of the von Hippel-Lindau (VHL) gene and hypoxia in the renal cell lines RCC786-0 and RCC4 has also been investigated. Ang-1, Ang-2 and Tie2, but not Ang-4 mRNA, were detected in normal and tumour samples. A significant increase in Ang-2 (p < 0.001) and a decrease in Tie2 receptor mRNA (p = 0.001) were observed, but no significant difference was observed in Ang-1 mRNA abundance between normal kidney and RCC (p = 0.37). Immunohistochemistry for Ang-2 showed strong expression in vascular endothelium and weak expression in tumour cells, whereas Tie2 was expressed exclusively on endothelium. Tie2 gene expression was positively correlated with Ang-2 expression in cancers (p = 0.001) and showed a borderline significant association with Ang-1 (p = 0.06), but there was no significant relationship between Ang-1 and Ang-2 (p = 0.69). No significant relationships were observed in clear cell carcinomas between Ang-1, Ang-2 and Tie2 mRNA abundance and patient sex, patient age, or tumour size (p > 0.05). However, there was significantly greater Ang-1 (p = 0.02), Ang-2 (p = 0.03), and Tie2 (p = 0.04) mRNA abundance in clear cell than in chromophil RCCs. Ang-2 gene expression was down-regulated by hypoxia in VHL wild-type RCC786-0 and RCC4 transfectants (p = 0.0002 and p = 0.04, respectively), mirroring the low expression in human tumour cells. These data suggest that it is endothelial induction of Ang-2 in tumours that regulates vessel stability and supports targeting Tie2 as an effective novel anti-angiogenic therapy in clear cell RCCs.     

Regulation of E2F1 by the von Hippel–Lindau tumour suppressor protein predicts survival in renal cell cancer patients

Biallelic mutations of the von Hippel–Lindau (VHL) gene are the most common cause of sporadic and inherited renal cell carcinoma (RCC). Loss of VHL has been reported to affect cell proliferation by deregulating cell cycle‐associated proteins. We report that the VHL gene product (pVHL) inhibits E2F1 expression at both mRNA and protein level in zebrafish and human RCC cells, while loss of VHL increases E2F1 expression in patient kidney tumour tissue and RCC cells, resulting in a delay of cell cycle progression. RCCs from von Hippel–Lindau patients with known germline VHL mutations express significantly more E2F1 compared to sporadic RCCs with either clear‐cell (cc) or non‐cc histology. Analysis of 138 primary RCCs reveals that E2F1 expression is significantly higher in tumours with a diameter ≤7 cm and with a favourable American Joint Committee on Cancer (AJCC) stage. The expression of E2F1 in RCC significantly correlates with p27 expression, suggesting that increased expression of E2F1 in RCC induces tumour cell senescence via p27. Cox regression analysis shows significant prediction of E2F1 expression for disease‐free survival and overall survival, implying that E2F1 expression in kidney tumour is a novel prognostic factor for patients with RCC. Copyright © 2013 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

SFRP5基因甲基化通过激活Wnt/β-catenin通路调节白血病细胞MDR1/P-gp的表达

 目的:研究分泌型卷曲相关蛋白5（SFRP5）基因甲基化对耐药白血病细胞多药耐药蛋白1/P-糖蛋白（MDR1/P-gp）表达的调节及其可能的信号通路。方法:采用甲基化特异性PCR（MSP）检测白血病患者及白血病细胞系中SFRP5基因启动子区甲基化状态。采用Western blotting检测非磷酸化β-catenin（NP-β-catenin）在SFRP5基因甲基化白血病患者及细胞系中表达。使用去甲基化试剂5-氮杂-2′-脱氧胞嘧啶（DAC）恢复SFRP5表达,采用RT-PCR和real-time PCR检测处理前后MDR1 mRNA表达,采用Western blotting检测P-gp表达。结果:5/12例白血病患者标本及4种白血病细胞系存在SFRP5基因完全甲基化。在5例患者标本中,有3例（L2、L7和L8）NP-β-catenin水平高于其它标本,在4种白血病细胞系中,KG1a中NP-β-catenin水平高于另外3个细胞系。存在NP-β-catenin高水平表达的3例患者（L2、L7和L8）中检出MDR1 mRNA及P-gp表达。在4种细胞系中,KG1a存在MDR1 mRNA及P-gp表达。使用去甲基化试剂DAC处理L2、L7、L8患者标本和KG1a细胞,恢复SFRP5表达,L2、L7、L8和KG1a中MDR1 mRNA水平均显著下降（P<0.01）,P-gp表达水平亦被下调。结论: SFRP5基因甲基化可导致Wnt/β-catenin信号通路被激活,活化的β-catenin激活下游靶基因MDR1转录,编码的药物外排泵P-gp表达增加,促进白血病多药耐药的形成。     

MiR-145-5p在大肠癌中的表达及与多药耐药的关系

目的 探讨大肠癌中miR-145-5p和多药耐药基因(MDR1)蛋白P-糖蛋白（P-gp）的表达及两者的关系。方法 分别在组织、细胞水平采用SP法、Real-time PCR法、Western blotting法检测50例大肠癌 (CRC)患者组织及30例癌旁正常组织患者中P-gp的表达,miR-145-5p的表达变化对MDR1 mRNA及P-gp的影响及两者与临床病理特征之间的相关性。结果 大肠癌组织中miR-145-5p表达量明显低于癌旁正常组织,MDR1 mRNA及P-gp的表达量明显高于癌旁正常组织(r=-0.403,P<0.01)。大肠癌细胞(HCT-15)中miR-145-5p 能够抑制MDR1 mRNA及P-gp的表达(P<0.05)。结论 MiR-145-5p对大肠癌多药耐药基因及蛋白的表达具有调控作用,参与了大肠癌的发生、发展及多药耐药。     

Association of Abl interactor 2, ABI2, with platelet/lymphocyte ratio in patients with renal cell carcinoma: A pilot study

There are many unknown aspects of the pathogenesis of renal cell carcinoma (RCC). The aim of the current study was to define new RCC‐related genes and measure their associations with RCC and clinical parameters, especially platelet/lymphocyte ratio which may be an independent predictor of prognosis in patients with RCC and other forms of cancer. Via in silico analysis upon RCC‐specific deleted genes in chromosome 3, four possible ceRNAs (ATXN3, ABI2, GOLGB1 and SMAD2) were identified. Then, the expression levels of these genes in tumour and adjacent healthy kidney tissues of 19 RCC patients were determined by real‐time PCR. ATXN3 and GOLGB1 gene expression levels increased but ABI2 gene expression level decreased in tumour kidney tissues when compared to normal ones. ATXN3, ABI2 and GOLGB1 gene expression levels were significantly higher in Fuhrman grade 4 than other grades (P < .001). ABI2 gene expression levels were significantly associated with higher platelet/lymphocyte ratio of the patients with RCC (P < .05). ATXN3, ABI2 and GOLGB1 may predict higher RCC grades. Also, ABI2 may regulate platelet/lymphocyte ratio which may be an independent predictor of RCC and other forms of cancer.     

Prognostic significance of multidrug resistance gene 1 (MDR1), multidrug resistance-related protein (MRP) and lung resistance protein (LRP) mRNA expression in acute leukemia

The prognostic significance of multidrug resistance (MDR) gene expression is controversial. We investigated whether multidrug resistance gene 1 (MDR1), multidrug resistance-related protein (MRP) and lung resistance protein (LRP) mRNA expression are associated with outcomes in acute leukemia patients. At diagnosis we examined MDR1, MRP and LRP mRNA expression in bone marrow samples from 71 acute leukemia patients (39 myeloid, 32 lymphoblastic) using nested RT-PCR. The expression of each of these genes was then expressed as a ratio in relation to beta-actin gene expression, and the three genes were categorized as being either 0, 1+, 2+ or 3+. MDR1, MRP and LRP mRNA expression was detected in 23.9%, 83.1% and 45.1 %, respectively. LRP mRNA expression was significantly associated with resistance to induction chemotherapy in acute leukemia patients, and in the AML proportion (p=0.02 and p=0.03, respectively). MRP and high MDR1 mRNA expression was associated with poorer 2-yr survival (p=0.049 and p=0.04, respectively). Patients expressing both MRP and LRP mRNA had poorer outcomes and had worse 2-yr survival. The present data suggest that MDR expression affects complete remission and survival rates in acute leukemia patients. Thus, determination of MDR gene expression at diagnosis appears likely to provide useful prognostic information for acute leukemia patients.     

Quantification of G250 mRNA expression in renal epithelial neoplasms by real-time reverse transcription-PCR of dissected tissue from paraffin sections

AIM: Renal cell carcinoma (RCC) represents the most common malignant tumour in the kidney and is resistant to conventional therapies. G250 is a tumour-associated antigen and is expressed mainly in clear cell RCC. It is a potential therapeutic target as well as a diagnostic marker for RCC. Previous studies relating to G250 protein or G250 mRNA expression in RCC using human tissue have largely been limited to immunohistochemical or conventional RT-PCR approaches that lack reproducibility, are subject to observer bias and are at most semi-quantitative. In this study, we evaluated the feasibility of using real-time RT-PCR in quantifying G250 mRNA expression using tissue dissected from paraffin sections of renal epithelial neoplasms. Using this approach, we performed a preliminary study investigating the relationship between G250 expression and tumor behavior in clear cell RCC. METHODS: A total of 53 radical nephrectomy specimens with renal epithelial neoplasms (nine oncocytoma, seven chromophobe RCC, four papillary RCC and 33 clear cell RCC) were included in this study. SYBR Green real-time RT-PCR was performed using the ABI PRISM 7700 Sequence Detection System. A TATA box-binding protein (TBP) was used as an endogenous reference gene. RESULTS: Our study showed that real-time RT-PCR is a reliable approach in quantifying G250 mRNA expression using paraffin sections. Using this methodology, G250 mRNA was detected in all of the clear cell RCCs, but none of the other types of tumours studied or in normal kidney tissue. Our study also suggested that the expression of G250 mRNA might correlate with tumour stage and overall survival. CONCLUSION: Among common renal epithelial neoplasms, G250 is a specific marker for clear cell RCC. Quantification of G250 mRNA expression by real-time RT-PCR using paraffin sections is a feasible approach for future clinical studies in evaluating the prognostic and predictive value of G250 in clear cell RCC.     

MMP-13 is over-expressed in renal cell carcinoma bone metastasis and is induced by TGF-β1

Bone metastasis occurs frequently in renal cell carcinoma (RCC) patients causing significant morbidity by stimulating excessive osteolysis, yet the mechanisms responsible have been little studied. Matrix metalloproteinases (MMPs) are over-expressed in many cancer types and are believed to play a role in bone metastasis, however, the expression of MMPs in RCC bone metastasis (RBM) has not been investigated. Due to their ability to degrade the main component of organic bone matrix, type I collagen, we investigated the expression of MMP-1, -2, -8, -9, and -13 in RBM. By quantitative (q)RT-PCR, expression of MMP-13 was significantly increased in RBM tissues relative to that in RCC and adjacent normal kidney while no differences in the expression of MMP-1, -2, -8, or -9 mRNA were observed. Correspondingly, increased expression of MMP-13 protein was also observed in RBM relative to RCC by immunohistochemical analysis. Intriguingly, the expression of MMP-13 in the human RBM cell line RBM1-IT4 was stimulated by TGF-β1, a growth factor abundant in the bone microenvironment and known to promote RBM-induced osteolysis in animals. Exposure of RBM1-IT4 cells to TGF-β1 increased MMP-13 mRNA levels as well as the latent and active forms of MMP-13 protein. Further, stable expression of a dominant-negative TGF-β type II receptor in RBM1-IT4 cells inhibited MMP-13 expression following TGF-β1 exposure. These data suggest that MMP-13 expression is elevated in RBM relative to primary RCC and adjacent normal kidney, and is regulated at the cellular level by TGF-β1.     

Modulation of urokinase and urokinase receptor gene expression in human renal cell carcinoma.

In vivo and in vitro experimental models have suggested a major role for the urokinase-type plasminogen activator (uPA) in tumor cell invasion and metastasis. The uPA proteolytic activity of tumor cells has been shown to be largely determined by the extent of the expression and saturation of the uPA receptor. We have analyzed the expression and cellular localization of both uPA and uPA receptor at the protein and mRNA levels in 33 paired samples of renal cell carcinoma (RCC) and non-tumorous kidney tissue. In comparison with adjacent normal non-tumorous kidney tissues RCC tumor cells modestly overexpressed uPA-receptor mRNA and showed significantly decreased uPA mRNA expression. However, the immunoreactive uPA content of tumor cells was comparable to that of the surrounding normal non-tumorous kidney tissue. Assuming constancy of the uPA-receptor affinity for uPA this indicates that a proportion of the RCC-associated uPA may be derived from an exogenous source and subsequently concentrated at the tumor cell surface via uPA receptor expression. The modest increase in uPA receptor expression may lead to a normalization of uPA antigen content in RCC; however, it is not sufficient to substantially increase tumor tissue-uPA content over the level of normal non-tumorous kidney tissue.     

TNFR-associated factor-2 (TRAF-2) in Alzheimer's disease

Levels of tumor necrosis factor-alpha (TNF-alpha) are increased in the brain in Alzheimer's disease (AD). The TNF-alpha/TNF-R signaling pathways involve complex interactions between several proteins, including TNF-receptor-associated factor-2 (TRAF-2). We have examined the distribution and levels of TRAF-2 in AD and control brains and also whether single nucleotide polymorphisms (SNPs) in the TRAF-2 gene are associated with AD and influence TRAF-2 expression. Immunohistochemistry demonstrated TRAF-2 in AD and control cortex in neurons, within plaque-associated neurites and some neurofibrillary tangles. Western blots revealed a band of the expected apparent molecular mass (approximately 50kDa) for TRAF-2, in homogenates of AD and control cortex. RT-PCR showed the levels of TRAF-2 mRNA to be significantly higher in the frontal cortex of AD than control brains (p=0.015). TRAF-2 mRNA expression was not linked to any SNPs. The 3' UTR SNP (rs7852970) GG allele was significantly protective against AD (p=0.030). Our findings suggest that the TRAF-2 pathway is involved AD. The mechanisms are currently unclear and need further examination.     

Renal cell carcinoma risk is associated with the interactions of APOE,VHL and MTHFR gene polymorphisms

Objective: The study was designed to explore the association of renal cell carcinoma (RCC) with VHL (rs779805), MTHFR (rs1801133) and APOE (rs8106822 and rs405509) polymorphisms, investigate the interactions among the single nucleotide polymorphisms (SNPs), and explore roles of the interactions in the pathogenesis of RCC in Chinese Han population. Methods: 81 RCC patients and 80 healthy controls were included in the study. Polymerase chain reaction (PCR) and direct sequencing methods were used in the analysis on the genotypes of APOE, VHL and MTHFR gene polymorphisms. Multifactor dimensionality reduction (MDR) method was adopted to conduct gene-gene interaction analysis. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were utilized to evaluate the correlation between gene-gene interactions and RCC risk. Results: Significant correlations were found between RCC risk and 3 SNPs (rs8106822, rs779805 and rs1801133). Genotype AA and allele A of APOE rs8106822 were significantly associated with RCC susceptibility (OR=2.65, 95% CI=1.05-6.69). Meanwhile, we found that the frequencies of genotype GG and allele G were much higher in case group, compared with controls (P<0.05 for both) and they appeared to be risk factors for RCC (OR=2.90, 95% CI=1.22-6.87; OR=1.78, 95% CI=1.14-2.27). While, allele T of MTHFR rs1801133 could decrease the risk of RCC (OR=0.62, 95% CI=0.40-0.97). MDR analysis showed that gene-gene interactions among APOE, VHL and MTHFR SNPs were closely related with RCC susceptibility. Conclusion: APOE, VHL and MTHFR gene polymorphisms were related to the risk of RCC. The interactions among APOE, VHL and MTHFR genes could increase the risk of RCC.     

The Alzheimer's associated 5' region of the SORL1 gene cis regulates SORL1 transcripts expression

SORL1 has been identified as a major contributor to late onset Alzheimer's disease (LOAD). We test whether genetic variability in the 5' of SORL1 gene modulates the risk to develop LOAD via regulation of SORL1-messenger ribonucleic acid (mRNA) expression and splicing. Two brain structures, differentially vulnerable to LOAD pathology, were examined in 144 brain samples from 92 neurologically normal individuals. The temporal cortex, which is more susceptible to Alzheimer's pathology, demonstrated ～2-fold increase in SORL1-mRNA levels in carriers of the minor alleles at single nucleotide polymorphisms (SNPs), rs7945931 and rs2298525, compared with noncarriers. No genetic effect on total-SORL1-mRNA levels was detected in the frontal cortex. However, rs11600875 minor allele was associated with significantly increased levels of exon-2 skipping, but only in frontal cortex. No correlation of SORL1-mRNAs expression was found between frontal and temporal cortexes. Collectively, these indicate the brain region specificity of the genetic regulation of SORL1 expression. Our results suggest that genetic regulation of SORL1 expression plays a role in disease risk and may be responsible for the reported LOAD associations. Further studies to detect the actual pathogenic variant/s are necessary.     

Expression of regulator of G protein signalling protein 5 (RGS5) in the tumour vasculature of human renal cell carcinoma

The gene expression profiles of tumour and normal vasculature are distinctively different. The altered expression of various angiogenesis-related genes in tumour-derived endothelial cells has been investigated intensively, but there may be as yet unidentified molecules that regulate tumour angiogenesis. In the present study, the distinctive expression of regulator of G protein signalling protein 5 (RGS5) in tumour vessels in human renal cell carcinoma (RCC) has been clarified. RGS5 is a member of the RGS superfamily and acts as a negative regulator of heterotrimeric G protein-mediated signalling through G protein-coupled receptors (GPCRs). RT-PCR showed strong expression of RGS5 in all RCCs examined, but expression was very weak or undetectable in normal kidneys. By real-time RT-PCR, the ratio of RGS5 mRNA in RCC to that in normal kidney was 6.6 : 1 (p = 0.0012). In situ hybridization showed strong expression of RGS5 in vessels within tumour cell nests. It was expressed neither in tumour cells nor in normal renal capillaries. Immunohistochemical staining using serial sections for endothelial cell markers (CD31 and CD34) and smooth muscle cell markers (alpha-SMA and desmin), as well as fluorescence double staining, strongly suggested that tumour endothelial cells were the main location of RGS5 in RCC. These findings suggest that RGS5 may be involved in G protein-mediated signalling in tumour vessels in human RCC.