乳腺癌细胞体外摄取2-脱氧葡萄糖荧光类似物

目的 观察2-脱氧葡萄糖(2-DG)荧光类似物2-N[7-硝基苯-2-乙二酸,34羟氨基]-2-脱氧葡萄糖(2-NBDG)被高表达葡萄糖转运蛋白1(GLUT-1)的乳腺癌细胞靶向摄取的情况.方法 应用逆转录聚合酶链反应(RT-PCR)法和免疫组化法检测乳腺癌MDA-MB-231细胞GLUT-1 mRNA和蛋白的表达,采用Western blot法比较乳腺癌MDA-MB-231细胞和MCF-7细胞GLUT-1的蛋白表达量.应用2-NBDG孵育人乳腺癌MDA-MB-231细胞,采用荧光显微镜及流式细胞仪观察、分析对2-NBDG的摄取情况,比较MDA-MB-231和MCF-7细胞吸收2-NBDG量的差异.结果 RT-PCR和免疫组化检测结果显示,MDA-MB-231细胞高表达GLUT-1;Western blot检测结果进一步显示,MDA-MB-231细胞的GLUT-1表达(0.946 4±0.007)高于MCF-7(0.833±0.010).荧光成像及流式细胞仪分析结果显示,MDA-MB-231细胞能快速摄取2-NBDG,且加入50 mmol/L D-葡萄糖后,荧光强度降低了46.0%.2-NBDG孵育乳腺癌细胞20 min后,MDA-MB-231细胞荧光强度(25.10±0.57)明显高于MCF-7细胞(10.12±0.62).结论 2-NBDG能迅速被高表达GLUT-1的乳腺癌MDA-MB-231细胞靶向吸收.     

Diverse regulations of albumin gene expression by hepatocyte growth factor in HepG2 human hepatoma cells and primary culture of rat hepatocytes

The effects of HGF on albumin gene expression in HepG2 human hepatoma cells and rat hepatocytes were investigated. HGF reduced the levels of albumin mRNA in HepG2 cells but the level was augmented in rat hepatocytes. By the transfection assay, HGF stimulated albumin promoter activity but repressed alpha-fetoprotein (AFP) enhancer activity regulating both AFP and albumin promoters in HepG2 cells. In contrast, HGF stimulated albumin promoter and AFP enhancer activities in rat hepatocytes. These results suggest that HGF elicits diverse responses of albumin gene expression in HepG2 cells and rat hepatocytes through the different biological actions on AFP enhancer in these cells.     

Ganglioside GD1a inhibits HGF-induced motility and scattering of cancer cells through suppression of tyrosine phosphorylation of c-Met.

We previously reported that ganglioside GD1a, which is highly expressed in poorly metastatic FBJ-S1 cells, inhibits the serum-induced motility of FBJ-LL cells and that the metastatic potential of FBJ-LL cells is completely suppressed by enforced GD1a expression (Hyuga et al., Int J Cancer 1999;83:685-91). We recently discovered that hepatocyte growth factor (HGF) induces FBJ-LL cell motility. In the present study, the HGF-induced motility of FBJ-S1 cells was found to be one-thirtieth that of FBJ-LL cells. This motility of GD1a-expressing transfectants, which were produced by transfection of FBJ-LL cells with GM2/GD2 synthase cDNA, decreased with increases in their GD1a expression and HGF induced almost no motility in GD1a-pretreated FBJ-LL cells, indicating that GD1a inhibits the HGF-induced motility of FBJ-LL cells. The expression of the HGF receptor c-Met on FBJ-S1 cells, FBJ-LL cells, transfectants and a mock-transfectant was almost the same. The level of tyrosine phosphorylation of c-Met after HGF stimulation in FBJ-S1 cells, GD1a-pretreated FBJ-LL cells and a GD1a-expressing transfectant was significantly lower than in FBJ-LL cells and a mock-transfectant. These findings suggested that GD1a inhibits the HGF-induced motility of FBJ-LL cells through suppression of tyrosine phosphorylation of c-Met. HepG2 cells, a human hepatoma cell line, were used to investigate whether GD1a interferes with other cancer cells expressing c-Met. HepG2 cells did not express GD1a. HGF induced cell scattering of HepG2 cells and the scattering was inhibited by pretreating the cells with GD1a. The c-Met in the cells was autophosphorylated by stimulation with HGF, but after treating the cells with GD1a, the HGF-induced autophosphorylation of c-Met was suppressed. These results suggest that GD1a acts as a negative regulator of c-Met in cancer cells.     

Glucose Transporter-1 (GLUT-1) Immunoreactivity in Benign,Premalignant and Malignant Lesions of the Gallbladder

GLUT-1 is a transmembrane glucose transport protein that allows the facilitated transport of glucose into cells, normally expressed in tissues which depend mainly on glucose metabolism. Enhanced expression of GLUT-1 can also be found in a large spectrum of carcinomas. This study aimed to investigate GLUT-1 expression in gallbladder tissue: from normal tissue samples, hyperplasias, low-grade and high-grade dysplasias to gallbladder carcinomas. In all, 115 archived samples of gallbladder tissue from 68 patients, presented after cholecystectomy, were immunohistochemically stained for GLUT-1. According to the intensity of GLUT-1 immunoreactivity, samples were divided into negative (stained 0–10% of cells stained), positive with weak to moderate (10–50%) and positive with strong (>50%) GLUT-1 expression. The GLUT-1 immunoreactivity of the samples showed a characteristic increase from premalignant lesions to carcinomas. Normal gallbladder tissue samples did not express GLUT-1 (100%). Weak expression was shown only focally in hyperplasias, but to a greater extent with low-grade dysplasias (20%), high-grade dysplasias (40%) and carcinomas (51.8%). Normal gallbladder tissue is GLUT-1 negative. GLUT-1 expression in carcinoma tissue is significantly higher than in dysplastic lesions. Strong GLUT-1 expression indicates 100% specificity for detecting gallbladder carcinomas. Therefore, GLUT-1 is a candidate as a diagnostic as well as a tissue prognostic marker in gallbladder carcinoma patients.     

沉默GLUT-1表达对食管鳞癌细胞株TE-13增殖和迁移的影响

目的：研究沉默葡萄糖转运蛋白-1（glucose transporter protein-1,GLUT-1）的表达对食管鳞癌TE-13细胞增殖、周期及迁移的影响及可能的作用机制。方法采用慢病毒感染的方法将特异性针对GLUT-1基因的GLUT-1-shRNA转入TE-13细胞,建立稳定干扰GLUT-1表达的TE-13细胞株,分成GLUT-1-shRNA组和阴性对照组进行对比研究。采用实时荧光定量PCR和蛋白质印迹法检测GLUT-1-shRNA对TE-13细胞GLUT-1 mRNA及其蛋白表达的影响。CCK-8法、FCM法和Transwell小室迁移实验分别检测沉默GLUT-1表达后对TE-13细胞增殖、细胞周期和迁移的影响;同时采用蛋白质印迹法检测细胞迁移以及乏氧相关蛋白的表达情况。结果采用慢病毒将GLUT-1-shRNA转入TE-13细胞后,可明显下调GLUT-1蛋白（t=6.713,P<0.01）和mRNA的表达水平（t=4.181,P<0.05）。与阴性对照组相比,GLUT-1干扰后细胞的增殖至72 h（t=3.097,P<0.05）和96 h（t=3.497,P<0.05）明显被抑制,同时细胞的迁移能力可见下降,但是细胞周期至24 h未见影响;基质金属蛋白酶的MMP-9（t=6.895,P<0.01）和缺氧诱导因子HIF-1α（t=13.74,P<0.001）的表达明显下调,但是MMP-2的表达没有变化（t=2.582,P>0.05）。结论沉默GLUT-1的表达可抑制食管磷癌细胞株TE-13细胞的增殖和迁移,并明显下调细胞内MMP-9和HIF-1α蛋白的表达,为寻找靶向治疗食管癌新靶点提供了初步的实验基础。     

葡萄糖转运蛋白-1在不同骨肿瘤中的表达

目的研究葡萄糖转运蛋白-1（GLUT-1）在正常骨组织及不同骨肿瘤标本中的表达情况。方法收集我院临床骨肉瘤标本30例，骨巨细胞瘤标本15例，骨样骨瘤标本10例及正常骨组织标本10例，采用免疫组化染色检测GLUT-1的分布。体外培养骨肉瘤细胞系MG63、临床骨肉瘤细胞、临床骨巨细胞瘤细胞及成骨细胞，RT-PCR检测GLUT-1基因的表达。结果免疫组化显示，骨肉瘤标本GLUT-1染色强阳性占总例数的53％；骨巨细胞瘤切片GLUT-1染色，阳性占总例数的60％；骨样骨瘤标本多为阴性，阴性占总例数的80％；正常骨组织中未见GLUT-1阳性表达。骨肉瘤明显高于与其余3组标本（χ^2=1．622，P=0．009；χ^2=34．667，P〈0．001，χ^2=40．000，P〈0．001）。RT-PCR显示，GLUT-1基因表达存在于MG63细胞、临床骨肉瘤细胞及骨巨细胞瘤中，而正常成骨细胞内并无GLUT-1表达。结论骨肿瘤中存在GLUT-1表达，且GLUT—1与骨肿瘤的恶性程度有较密切的关系。GLUT-1有可能作为判断骨肿瘤恶性程度参考指标及骨肿瘤治疗的新靶点。     

GLUT-1和DNA-PKcs在卵巢浆液性肿瘤组织中的表达及其意义

背景与目的:已知肿瘤细胞生长所需能量是通过葡萄糖转运体蛋白1(glucose transporter protein 1,GLUT-1)完成的葡萄糖代谢来提供的.另外,参与基因损伤修复的催化亚单位--DNA蛋白激酶(DNA-dependent protein kinase catalytic subunit,DNA-PKcs)在肿瘤形成中也起着非常重要的作用.本研究旨在探讨GLUT-1和DNA-PKcs在卵巢浆液性肿瘤组织中的表达及其与肿瘤生物学行为的关系和意义.方法:免疫组化方法检测80例卵巢浆液性肿瘤组织中GLUT-1、DNA-PKcs的表达,分析其异常表达与临床病理参数之间的相关性.以正常卵巢组织20例为对照.结果:正常卵巢组织GLUT-1表达全阴性,DNA-PKcs表达全阳性.GLUT-1在良性、交界性、恶性卵巢浆液性肿瘤中的表达呈增高的趋势,与卵巢浆液性肿瘤的发生发展呈正相关(rs=0.943,P＜0.01);在恶性肿瘤中的阳性率(100%)明显高于交界性(55%).DNA-PKcs在良性、交界性和恶性卵巢浆液性肿瘤中的阳性率分别为95%、90%、60%,差异有统计学意义(P＜0.01).GLUT-1与DNA-PKcs的表达呈负相关(rs=-0.270,P＜0.01).GLUT-1表达与临床分期、腹腔种植、腹水、淋巴结转移均相关(P＜0.05);DNA-PKcs仅与临床分期和淋巴结转移相关(P＜0.05),与腹水、腹腔种植无关(P＞0.05).结论:GLUT-1的异常表达和DNA-PKcs的丢失与卵巢浆液性肿瘤恶变相关.     

缺氧对喉癌Hep-2细胞HIF-1α、GLUT-1、MMP-2表达的影响

目的 探讨缺氧对喉癌Hep-2细胞增殖、迁移和侵袭以及缺氧诱导因子-1α（HIF-1α）、葡萄糖转运蛋白-1（GLUT-1）和基质金属蛋白酶-2（MMP-2）表达的影响。方法 MTT法检测缺氧不同时间点细胞增殖状况;Transwell和划痕实验分别检测缺氧对喉癌Hep-2细胞侵袭和迁移能力的影响;Western blot和实时定量反转录聚合酶链反应（RT-PCR）检测缺氧后不同时间点HIF-1α、GLUT-1、MMP-2蛋白及mRNA表达的情况。结果 在缺氧条件下（1％O2、5％CO2和94％N2）,Hep-2细胞的存活率随缺氧时间的延长逐渐升高,迁移和侵袭能力增强;随缺氧时间延长,Hep-2细胞HIF-1α蛋白表达水平明显增加,mRNA水平变化不明显;随缺氧时间延长,GLUT-1、MMP-2的mRNA水平和蛋白水平均明显增加。 结论 缺氧环境下,喉癌肿瘤细胞通过上调HIF-1α、GLUT-1、MMP-2的表达,强化其增殖、侵袭、转移的能力,促进喉癌的发展。     

TSLC1基因真核表达载体的构建及在HepG2细胞中的表达

Objective： To construct the eukaryotic expression vector for human TSLC1 gene, and to express TSLC1 in HepG2 cells for investigating its effect on HepG2 cell growth. Methods： Full length of TSLC1 cDNA was amplified from RNA of normal human liver by RT-PCR, and cloned into pCI-neo expression vector. The recombinant plasmid pCI-TSLC1 was identified with restriction enzyme and sequenced, and then was stably transfected into HepG2 cells with lipofectamine 2000. The positive clones were examined by western-blotting and immunofluorescence, cell growth was analyzed with MTT assay. Results： The eukaryotic expression vector pCI-TSLC1 was successfully constructed and the stable cell line highly expressing TSLC1 protein was obtained. The growth of TSLCl-transfected cells was significantly suppressed in vitro. Conclusion： The HepG2 stable cell line could highly express TSLC1 protein, which provided a basis for further exploring the roles of TSLC1 in hepatocellular carcinoma.     

Involvement of hepatocyte growth factor in increased integrin expression on HepG2 cells triggered by adhesion to endothelial cells.

Adhesion of cancer cells to vascular endothelium is an important step in haematogenous metastasis of cancer. A human hepatocellular carcinoma cell line, HepG2, strongly adheres to human umbilical vein endothelial cells (HUVECs) through the interaction of E-selectin and its carbohydrate ligand sialyl Lewis X. In this study, we investigated alteration in integrin expression on HepG2 cells, which follows the selectin-mediated initial adhesion of HepG2 cells to HUVECs. Expression of alpha2beta1 integrin was markedly increased when the HepG2 cells adhered to HUVECs. Among the tested cytokines that are known to be produced by endothelial cells, recombinant hepatocyte growth factor (rHGF) could replace the effect of HUVECs, and a similar increase in integrin expression was observed by the addition of 20 ng ml-1 rHGF to HepG2. The increment of alpha2beta1 integrin expression was significantly inhibited by anti-HGF neutralizing antibody treatment. HepG2 cells expressed alpha2, alpha6, beta1, and beta4 integrin subunits, but expression of integrins other than alpha2beta1 was not affected by the rHGF treatment. The rHGF treatment of HepG2 cells resulted in augmented adhesion to immobilized collagen. This augmentation in adhesion to collagen was completely blocked by the addition of anti-alpha2- or anti-beta1-integrin antibody. In double-chamber chemoinvasion experiments, transmigration of the HepG2 cells through extracellular matrix (ECM) gel was significantly accelerated by co-cultivation with HUVECs. A similar level of enhancement in transmigration activity of the cancer cells was observed by the addition of rHGF. Our interpretation of the results described above is that the cancer cells received stimulation from cytokines, such as HGF, presented by vascular endothelial cells, following the initial adhesion of cancer cells via selectins. This resulted in the secondary increment in the expression of cell adhesion molecules, such as the alpha2beta1 integrin, and led to the augmented adhesive activities of cancer cells towards extracellular matrices at vascular walls. We suggest that this sequence of events is involved in the facilitated migration of some cancer cells to extravascular tissues.     

Immunohistochemical Evaluation of Glucose Transporter Type 1 in Epithelial Dysplasia and Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is the most common malignancy of the oral cavity and some of these have been documented in association or preceded by oral epithelial dysplasia (OED). Aggressive cancers with fast growth have demonstrated overexpression of some glucose transporters (GLUTs). Thus, the aim of this study was to analyze the immunohistochemical expression of the glucose transporter, GLUT-1, in OEDs and OSCCs, seeking to better elucidate the biological behavior of neoplasias. Fifteen cases were selected this research of both lesions. Five areas were analyzed from each case by counting the percentage of positive cells at 400x magnification. Immunoreactivity of GLUT-1 was observed in 100% of the samples ranging from 54.2% to 86.2% for the OSCC and 73.9% to 97.4% for the OED. Statistical test revealed that there was greater overexpression of GLUT-1 in OED than the OSCC (p=0.01). It is believed the high expression of GLUT-1 may reflect the involvement of GLUT-1 in early stages of oral carcinogenesis.     

Role for glucose transporter 1 protein in human breast cancer

Glycolysis is increased in cancer cells compared with normal cells. It has been shown that glucose enters cells via a family of five functional glucose transporters (GLUT). However, GLUT expression appears to be altered in human breast cancer, which may serve as a selective advantage and facilitate the metastatic potential of these cells. The relationship of GLUT isoform expression and breast cancer cell invasiveness has not been adequately addressed. Thus, the purpose of this study was to investigate whether an association exists between GLUT expression and human breast cancer cell invasiveness. Invasiveness of the human breast cancer lines MCF-7, MDA-MB-435 and MDA-MB-231 was measured using anin vitro assay and compared with cellular GLUT isoform expression, assessed by Western blot analysis and verified by immunohistochemistry in a poorly differentiated human ductal breast cancer. Cell surface GLUT-1 expression was associated with the invasive ability of MCF-7 (2.0 ± 0.02%), MDA-MB-435 (6.4 ±0.4%), and MDA-MB-231 (19.3 ± 2.0%). However, GLUT-2 and GLUT-5 were inversely associated with invasiveness; GLUT-3 expression was variable; and GLUT-4 was undetected. In a poorly differentiated human ductal breast cancer,in situ GLUT-1 staining was intense. GLUT-1 expression was associated with the in vitro invasive ability of human breast cancer cells which was validatedin situ. If this relationship is found to exist in a larger number of human breast cancer tissues, it may be possible to develop diagnostic and therapeutic strategies based on targeted GLUT isoform expression.     

Progressive increase of glucose transporter-3 (GLUT-3) expression in estrogen-induced breast carcinogenesis

Introduction

Increased glucose uptake and glycolysis are main metabolic characteristics of malignant cells. A family of glucose transporters (GLUTs) facilitates glucose movement across the plasma membranes in a tumor-specific manner. Glucose transporter-1 (GLUT-1), GLUT-3 and recently GLUT-12, have been previously shown in breast cancer cells and are found to be associated with poor prognosis. In addition, it has been shown that estrogen plays critical roles in GLUT regulation, however, the stage-specific GLUT regulation of mammary carcinogenesis is unclear.

Methods

GLUT expression patterns were investigated in an in vitro–in vivo progressive, estrogen-induced, mammary carcinogenesis model which consisted of four cell lines, with same genetic background. In this model, different stages of tumor initiation and progression are represented, MCF-10F being the normal stage, E2 cells the transformed stage by estrogen, C5 cells, the invasive stage, and T4 cells the tumorigenic stage. In addition, loss of ductulogenesis and solid mass formation in collagen matrix and invasiveness of the cells were counted.

Results

Real time PCR showed that GLUT1 expression was downregulated in MCF10F after treatment with 17β-estradiol (E2), and in the invasive cell type (C5), but not in the tumor cells (T4), which had no changes compared to MCF10F. C5 and T4 cells showed the highest rate of GLUT-3 expression. These cells were also found to be associated with loss of ductulogenesis, solid mass formation and higher invasive capacity, whereas, GLUT-12 was downregulated in C5 and T4 cells.

Conclusion

Estrogen-induced malignant transformation is associated with remarkable and progressive GLUT-3 expression, GLUT-1 re-expression at further stages, as well as GLUT-12 downregulation.