Genetic or epigenetic silencing of low density lipoprotein receptor-related protein 1B expression in oral squamous cell carcinoma

Previously, we have reported frequent silencing of the expression of LRP1B by genetic and epigenetic mechanisms in esophageal squamous cell carcinoma. As the same events might be involved in the development/progression of OSCC, we examined intragenic homozygous deletions, expression levels, and methylation status in the CpG island of this gene. Homozygous deletion was detected in only 1 of 18 (5.6%) OSCC lines, whereas the expression of LRP1B mRNA was silenced in 8 of 17 (47.1%) OSCC lines without homozygous deletion. An inverse correlation between mRNA expression and methylation status of the LRP1B CpG island was clearly observed in OSCC lines, and LRP1B mRNA expression was restored by treatment with 5-aza-dCyd. Frequent methylation of the LRP1B promoter was also observed in primary OSCC. Taken together, the results suggested that frequent inactivation of LRP1B mainly occurs by means of epigenetic mechanisms in OSCC, which might play an important role in oral tumorigenesis.     

In vitro invasiveness of human breast cancer cells is promoted by low density lipoprotein receptor-related protein

Low density lipoprotein receptor-related protein/alpha(2)-macroglobulin receptor (LRP) is a surface membrane endocytic receptor, one of whose many functions is the regulation of plasminogen activator-mediated cell migration. LRP is known to have a role in migration and invasion, but its direct involvement has been demonstrated only in non-tumour cells. We investigated six breast cancer cell lines and a normal mammary epithelial cell clone for surface and total cellular LRP expression, and confirmed that its presence corresponds to the ability to invade and migrate in vitro. We showed that LRP in the tumour cell lines is expressed at a wide range of levels: from approximately 300 to approximately 6,300 sites per cell. Four of the breast cancer cell lines expressed LRP at over 1,000 sites/cell and were markedly invasive in our assay, the remainder of the cell lines and the normal clone having far fewer LRP sites and lacking invasive ability. We further showed that the migratory and invasive abilities of a highly invasive breast cancer cell line are both inhibited by receptor-associated protein, a unique LRP ligand which normally has a solely intracellular distribution but which, when added to culture medium, can inhibit all other ligand interactions with this receptor.     

Roles oflow-density lipoprotein receptor-related protein 1 intumors

Low-density lipoprotein receptor-related protein 1 (LRP1, also known as CD91), a multifunctional endocytic and cell signaling receptor, is widely expressed on the surface of multiple cell types such as hepatocytes, ifbroblasts, neu-rons, astrocytes, macrophages, smooth muscle cells, and malignant cells. Emerging invitro and invivo evidence demonstrates that LRP1 is critically involved in many processes that drive tumorigenesis and tumor progression. For example, LRP1 not only promotes tumor cell migration and invasion by regulating matrix metalloproteinase (MMP)-2 and MMP-9 expression and functions but also inhibits cell apoptosis by regulating the insulin receptor, the serine/threonine protein kinase signaling pathway, and the expression of Caspase-3. LRP1-mediated phosphorylation of the extracellular signal-regulated kinase pathway and c-jun N-terminal kinase are also involved in tumor cell proliferation and invasion. In addition, LRP1 has been shown to be down-regulated by microRNA-205 and methylation ofLRP1 CpG islands. Furthermore, a novel fusion gene,LRP1-SNRNP25, promotes osteosarcoma cell invasion and migration. Only by understanding the mechanisms of these effects can we develop novel diagnostic and therapeutic strategies for cancers mediated by LRP1.     

The low-density lipoprotein receptor-related protein regulates cancer cell survival and metastasis development

Low-density lipoprotein receptor-related protein-1 (LRP-1) is a multifunctional receptor involved in receptor-mediated endocytosis and cell signaling. In this study, we show that LRP-1 is abundantly expressed in severe combined immunodeficient (SCID) mouse xenografts by various human cancer cell lines that express very low or undetectable levels of LRP-1 when cultured in 21% O2 in vitro (standard cell culture conditions). To test whether LRP-1 expression in vivo may be explained by hypoxia in the xenografts, CL16 cells, which are derived from the MDA-MB-435 cell line, were cultured in 1.0% O2. A substantial increase in LRP-1 expression was observed. To test the activity of LRP-1 in cancer progression in vivo, LRP-1 expression was silenced in CL16 cells with short hairpin RNA. These cells formed tumors in SCID mice, in which LRP-1 expression remained silenced. Although LRP-1 gene silencing did not inhibit CL16 cell dissemination from the primary tumors to the lungs, the pulmonary metastases failed to enlarge, suggesting compromised survival or growth at the implantation site. In cell culture experiments, significantly increased cell death was observed when LRP-1-silenced CL16 cells were exposed to CoCl2, which models changes that occur in hypoxia. Furthermore, LRP-1-silenced cells expressed decreased levels of vascular endothelial growth factor in response to 1.0% O2. These results suggest mechanisms by which LRP-1 may facilitate the development and growth of cancer metastases in vivo.     

大肠癌组织中EPO-R的表达意义及与MVD的关系

目的:探讨大肠癌组织中EPO-R的表达及其与MVD在血管生成、侵袭和转移中的作用及其相关性.方法:应用免疫组化方法检测48例大肠癌组织及正常大肠组织中EPO-R的表达,并对血管进行CD34相关抗原的免疫组化染色,计数MVD.分析EPO-R与微血管密度(MVD)的关系.结果:EPO-R在大肠癌中的表达率高于癌旁及正常大肠组织,差别有显著统计学意义(P＜0.01),且EPO-R表达及MVD值与肿瘤分化、Dukes分期、淋巴结转移有显著相关性(P＜0.05).EPO-R表达阳性组织中,MVD计数显著高于EPO-R表达阴性者(P＜0.05).结论:结直肠癌组织中存在EPO-R表达且过表达率高,而癌旁结肠组织几乎不表达,可为临床诊断提供依据.EPO-R表达与MVD值紧密相关.血管生成增加,从而影响肿瘤的浸润和转移等生物学行为.     

Human glioblastoma cell lines: levels of low-density lipoprotein receptor and low-density lipoprotein receptor-related protein

The status of the low-density lipoprotein (LDL) receptor and LDL receptor-related protein (LRP) in seven human glioma cell lines was evaluated to extend our knowledge of human glioblastoma multiforme tumor metabolism for future drug design. Cell lines SF-767, SF-763, A-172, U-87 MG, U-251 MG, U-343 MG, and SF-539 were used. Binding of 125I-labeled LDL to these cells at 4 degrees C was carried out to determine the number of LDL receptors on cells and the affinity of LDL for these receptors. The content of LRP was measured by immunoblotting. The presence of specific saturable LDL receptors was proven in six of the cell lines investigated. SF-767 cells revealed high-affinity LDL binding (equilibrium dissociation constant, Kd = 7 nM) and maximum binding capacity approximating 300,000 receptors/cell. Most of the remaining cell lines had relatively lower affinity (Kd = 38-62 nM) but also had very high numbers of receptors (128,000-950,000/cell). All cell lines exhibited LRP, but the expression was variable. The cell lines SF-539, U-87 MG, and U-343 MG were particularly rich in this protein. The data suggest that glioblastoma cells have high numbers of LDL receptors; however, there is considerable variation in binding affinity. Overall, this finding suggests that LDL receptors on glioblastoma cells could potentially be useful for targeting antitumor agents. LRP, a multifunctional receptor expressed on glioblastoma cells, also has the possibility for serving as a therapeutic target.     

Modulation of base excision repair by low density lipoprotein, oxidized low density lipoprotein and antioxidants in mouse monocytes

In the present study, we found that oxidized low density lipoprotein, but not low density lipoprotein, down-regulated base excision repair activity in extracts of mouse monocyte cell line PU5-1.8. An enzyme required in this pathway, DNA polymerase beta, was also down-regulated. In contrast, treatment of monocytes with a combination of ascorbate and alpha-tocopherol up-regulated base excision repair activity and expression of DNA polymerase beta. Co-treatment of monocytes with antioxidants plus oxidized low density lipoprotein prevented down-regulation by oxidized low density lipoprotein. Oxidative DNA damage, as measured by 8-hydroxyguanine accumulation in genomic DNA, was found in cells treated with oxidized low density lipoprotein; 8-hydroxyguanine was not found in the cells treated with low density lipoprotein, antioxidants or oxidized low density lipoprotein plus antioxidants. These results establish a linkage between the DNA base excision repair pathway, oxidative DNA damage and oxidized low density lipoprotein treatment in mouse monocytes. Since oxidized low density lipoprotein is implicated in chronic disease conditions such as atherogenesis, these findings facilitate understanding of genetic toxicology mechanisms related to human health and disease.     

大肠癌组织c-Met和VEGF表达及其与微血管密度关系的初步研究

目的:探讨大肠癌组织c-Met和血管内皮生长因子(VEGF)的表达以及两者与肿瘤血管生成的关系及其临床病理学意义。方法:选取经病理确诊的51例大肠腺癌手术切除组织标本,免疫组化SP法检测c-Met和VEGF的表达及微血管密度(MVD)。结果:大肠癌组织中c-Met和VEGF的阳性表达率分别为72.55%(37/51)和52.94%(27/51);与Dukes分期密切相关,P<0.05。大肠癌组织c-Met、VEGF均为阳性时MVD值为37.94±7.53,单一阳性时分别为30.67±1.45和23.82±7.45,均为阴性时MVD值最小,为13.64±5.33。大肠癌组织中c-Met和VEGF的表达呈显著正相关,rs=0.614,P<0.05。结论:c-Met和VEGF在大肠癌发生、发展和转移过程中起重要作用,并与肿瘤血管生成相关。     

肺耐药蛋白在大肠癌中的表达及临床意义

目的　探讨肺耐药蛋白 (LRP)在大肠癌中的表达及其临床意义。方法　以免疫组化检测 2 4例大肠癌组织中的LRP表达情况。结果　 2 4例大肠癌中 2 0例LRP阳性 ,阳性率为 83 .3 % ,高、中分化腺癌的LRP阳性率 ( 17/17)明显高于低分化腺癌 ( 0 /2 ) ,LRP表达与肿瘤部位、大小、淋巴结转移、浸润深度及Dukes分期无关。结论　LRP在大肠癌原发耐药中具有重要作用 ,LRP的测定有助于化疗药物的选择。     

大肠癌组织中p53蛋白和增殖细胞核抗原表达的临床意义

目的探讨增殖细胞核抗原(PCNA)和p53蛋白在大肠癌中的表达及临床意义.方法应用免疫组化S-P方法检测60例大肠腺癌中的PCNA及p53蛋白的表达.结果大肠癌中p53蛋白阳性表达率为63.3%,PCNA增殖指数为(78.2±24.5)%,p53蛋白表达阳性者其细胞增殖活性为(83.1±18.6)%,明显高于p53蛋白阴性组(61.2±11.3)%(P＜0.01).p53蛋白阳性表达率与PCNA增殖指数随着大肠癌病理分级的上升而增加,且与预后呈负相关.结论同时检测p53蛋白、PCNA对大肠癌的诊断、病理分级及预后的评估有重要的指导意义.     

Preparation of drug-low density lipoprotein complexes for delivery of antitumoral drugs via the low density lipoprotein pathway

The receptor-mediated assimilation of low density lipoprotein (LDL) by many cancer cells is much higher than that of normal cells. This fact suggests that lipoproteins with incorporated cytotoxic drugs may be used as a carrier for chemotherapeutic agents to neoplastic cells. In this study a lipophilic cytotoxic compound is incorporated into reconstituted LDL by two different methods. Both the structure and cellular uptake were found to be similar to those of native LDL. Tests of the cytotoxic activity on cultured cells demonstrated that the drug delivered to the cells via the LDL pathway was able to kill 100% of the cells. Heparin and a low temperature, which are known to inhibit uptake of LDL by the receptor mechanism, abolished the cytotoxic activity of the drug-lipoprotein conjugates. The results suggest that it may be possible to use reconstituted LDL as a vehicle for lipophilic antineoplastic drugs in order to increase the drug accumulation and selectivity in tumor cell populations with high LDL receptor activity.     

散发性结直肠癌组织中FHIT蛋白表达的研究

目的：探讨散发性结直肠癌组织中脆性组氨酸三联体（fragile histidine triad，FHIT）蛋白表达情况及其与临床病理指标之间的关系。方法：采用免疫组化SP法检测84例手术切除的散发性结直肠癌组织中FHIT蛋白的表达。结果：FHIT蛋白在84例散发性结直肠癌中表达阳性率为48．81％。FHIT蛋白低或不表达与患者的年龄、性别、肿瘤部位、组织学类型无关，P〉0．05；而与肿瘤浸润深度和分化程度、Duck’s分期和淋巴结转移有关，P〈0，05。在浸润深度越深、分化程度越低、Duck’s分期越晚和有淋巴结转移的癌组织中，FHIT蛋白低表达就越明显。结论：FHIT蛋白表达缺失可能参与散发性结直肠癌的演化和进展。     

散发性结直肠癌组织中FHIT蛋白表达的研究

目的:探讨散发性结直肠癌组织中脆性组氨酸三联体(fragile histidinetriad,FHIT)蛋白表达情况及其与临床病理指标之间的关系。方法:采用免疫组化SP法检测84例手术切除的散发性结直肠癌组织中FHIT蛋白的表达。结果:FHIT蛋白在84例散发性结直肠癌中表达阳性率为48·81%。FHIT蛋白低或不表达与患者的年龄、性别、肿瘤部位、组织学类型无关,P>0·05;而与肿瘤浸润深度和分化程度、Duck’s分期和淋巴结转移有关,P<0·05。在浸润深度越深、分化程度越低、Duck’s分期越晚和有淋巴结转移的癌组织中,FHIT蛋白低表达就越明显。结论:FHIT蛋白表达缺失可能参与散发性结直肠癌的演化和进展。     

微血管密度在结直肠癌中的表达及意义

目的　探讨微血管密度（ＭＶＤ）在结直肠癌中的表达及其与肿瘤血管生成、临床病理因素和预后的关系。方法　用免疫组化ＳＰ法检测８０例结直肠癌、３０例结直肠腺瘤及３０例正常结直肠组织中ＣＤ３４表达并计算ＭＶＤ值,分析ＭＶＤ值与结直肠癌临床病理因素及预后的关系。结果　结直肠癌ＭＶＤ值为３０.２±６.３,显著高于结直肠腺瘤的１３.１±１.６和正常结直肠组织的６.５±２.７,差异均有统计学意义（Ｐ＜０.０１）。结直肠癌ＭＶＤ值与Ｄｕｋｅｓ分期、肿瘤浸润深度、淋巴结转移显著相关（Ｐ＜０.０１）。结直肠癌高ＭＶＤ值组患者５年生存率为３５.７１％,显著低于低ＭＶＤ值组的７１.０５％,差异有统计学意义（Ｐ＜０.０１）。结论　ＭＶＤ值在结直肠癌中较高,并能够预示肿瘤具有更高的侵袭性及不良预后。     

nm23和E-cadherin在大肠癌的表达及意义

目的探讨nm23和E-cadherin在大肠癌转移进展过程中的作用及相互关系.方法用免疫组化EnVision二步法分别检测186例大肠癌、癌旁组织和20例正常大肠粘膜nm23和E-cadherin蛋白的表达情况,结合临床病理资料进行分析.结果nm23和E-cadherin蛋白在大肠癌组织的阳性表达率分别为52.7%、56.5%,显著低于癌旁组织(分别为90.99%、95.2%)和正常大肠粘膜(分别为95%、100%);nm23和E-cadherin在高分化腺癌的阳性率高于中-低分化腺癌;随着Dukes分期从A期到D期,淋巴结的转移,nm23和E-cadherin的表达显著降低或缺失;nm23和E-cadherin在大肠癌的表达呈正相关.结论nm23和E-cadherin表达的降低或缺失与大肠癌的恶性进展,转移具有密切关系,检测大肠癌组织中的nm23和E-cadherin的表达水平对预测患者的预后具有重要意义.     

多学科综合诊疗直肠癌术后肺转移5例及文献复习

目的:结合文献复习,探讨多学科综合诊疗直肠癌术后肺转移的价值。方法:采用外科手术、新辅助化疗、辅助放化疗及胸腔镜或开胸手术等方法对我院2009年至2012年5例直肠癌原发肿瘤和术后肺转移癌患者进行治疗。直肠癌术后随访17个月以上,肺转移癌术后随访7个月以上,观察无进展生存期(progression-freesurvival,PFS)。结果:5例患者直肠癌和肺转移癌均无复发,至今已生存17个月到34个月。结论:把握适应证,采用多学科综合诊治直肠癌肺转移能够有效地延长患者无进展生存期,提高生存质量。     

DAB2IP基因及蛋白在结直肠癌组织中的表达研究

目的 从mRNA和蛋白两个水平上探讨DAB2IP 在结直肠癌组织中的表达及意义。方法 应用核酸原位杂交和免疫组织化学两种方法分别检测127例结直肠癌组织和36例癌旁正常黏膜组织中DAB2IP的表达情况,分析DAB2IP基因及其蛋白表达与结直肠癌淋巴结转移、分化程度及Dukes分期等临床病理特征的关系。结果 结直肠癌组织中DAB2IP mRNA与蛋白的阳性表达率分别为85.04％、79.53％,低于癌旁正常组织的100.00％、94.45％,差异有统计学意义（P均＜0.001）。高、中分化到低分化结直肠癌组织中,DAB2IP的阳性表达率均逐渐下调,3组间差异有统计学意义 （P＜0.01）。结直肠癌无淋巴结转移组中的DAB2IP阳性表达率高于淋巴结转移组,且其mRNA与蛋白表达水平与淋巴结转移呈负相关（r=-0.2361,r=-0.3060;P均＜0.01）。DAB2IP的表达水平与Dukes分期有关,从A期到D期DAB2IP表达逐渐下调,差异有统计学意义（P＜0.01）; 但DAB2IP表达与结直肠癌患者的年龄、性别、发生部位及肿瘤大小均无关（P＞0.05）。结论 DAB2IP在结直肠癌的发生、发展中具有重要作用,且其表达水平与淋巴结转移呈负相关,可作为预测结直肠癌转移潜能及判断预后的一个重要指标。