The alpha2beta1 integrin mediates the malignant phenotype on type I collagen in pancreatic cancer cell lines

Pancreatic cancer is characterised by a hallmark desmoplastic response that includes upregulated expression of the extracellular matrix, and type I collagen in particular. Recent studies indicate that pancreatic cancer cells stimulate type I collagen synthesis in adjacent stellate cells, and that this upregulated type I collagen expression promotes the malignant phenotype in tumour cells as defined by increased proliferation, resistance to chemically induced apoptosis, and increased tumorigenesis. The integrin specificity of this interaction between type I collagen and tumour cells was not identified, however. In the present study, we examined eight pancreatic cancer cell lines for adhesion, proliferation, and migration, on types I and IV collagen, fibronectin, laminin, and vitronectin, as well as integrin expression. Our results indicate, for the overwhelming majority of cell lines, that type I collagen promotes the strongest adhesion, proliferation, and migration relative to the other substrates tested. Utilising function-blocking monoclonal antibodies directed against particular integrin subunits in cell adhesion and migration inhibition assays, we demonstrate further that the malignant phenotype on type I collagen is mediated specifically by the alpha2beta1 integrin. These results identify alpha2beta1 integrin-mediated adhesion to type I collagen as a potential therapeutic target in the treatment of pancreatic cancer.     

Differential gene expression profiles of radioresistant pancreatic cancer cell lines established by fractionated irradiation

Identification of the genes that are differentially-expressed between radiosensitive and radioresistant cancer cells is important to the ability to predict the clinical effectiveness of radiotherapy. We established radioresistant human pancreatic cancer cell lines using fractionated irradiation in order to identify genes that are differentially-expressed between parental lines and radioresistant cell sublines. Six pancreatic cancer cell lines (PK-1, PK-8, PK-9, T3M4, MiaPaCa2 and PANC-1) were treated with 10 Gy fractionated irradiation at approximately two-week intervals (total dose 150-180 Gy). Five radioresistant sublines (PK-1, PK-8, PK-9, T3M4, and MiaPaCa2) were successfully established. Using oligonucleotide microarrays containing 17,086 genes, we identified 73 up-regulated genes and 55 down-regulated genes common to radioresistant sublines. Subsequent analysis by quantitative RT-PCR confirmed the reliability of our microarray strategy. Up-regulated genes were associated with growth factor (example, amphiregulin), cell-cycle check point (MAPKAPK2), intracellular signaling pathway (regucalcin), and angiogenesis stimulation (angiopoietin 2). Down-regulated genes were associated with apoptosis (caspase 8), retinoid esterification (lecithin retinol acyltransferase), and electron transport (calcium-activated chloride channel 1). Some of these genes have known association with response to radiation, such as caspase 8 and MAPKAPK2, but others are novel. Global gene analysis of radioresistant sublines may provide new insights into the mechanisms underlying clinical radioresistance and to improving the efficacy of radiotherapy for pancreatic cancer.     

E-cadherin expression is silenced by DNA methylation in cervical cancer cell lines and tumours

A previous study showed E-cadherin expression was lost in some cervical cancer cell lines and tumours. This study was designed to clarify the significance of DNA methylation in silencing E-cadherin expression. We examined promoter methylation of E-cadherin in five cervical cancer cell lines and 20 cervical cancer tissues using methylation-specific PCR (MSP) and bisulphite DNA sequencing. The correlation of E-cadherin methylation and expression together with methyltransferase (DNMT1) were further studied. We found that hypermethylation of E-cadherin was involved in five cervical cancer cell lines and 40% (8/20) of cervical cancer tissues. E-cadherin protein was lost in 6/8 (75%) samples and 3/5 (60%) cell lines with promoter methylation. E-cadherin methylation was significantly correlated with increased DNMT1. Using an antisense DNMT1 oligo to transfect into SiHa HeLa C33A cell line, E-cadherin protein was re-expressed. We concluded that loss of E-cadherin expression was in part correlated with DNA methylation and DNMT1 expression in cervical cancer.     

Collagen type I-induced Smad-interacting protein 1 expression downregulates E-cadherin in pancreatic cancer

Pancreatic cancer is a devastating disease with poor prognosis. Production of large quantities of extracellular matrix and early metastasis are characteristics of this disease. One important step in the development of various cancers is the loss of E-cadherin gene expression or inactivation of E-cadherin mediated cell-cell adhesion. It has been shown that collagen type I promotes downregulation of E-cadherin expression, which correlates with enhanced cell migration and invasiveness. In this context, we elucidated the role of Smad-interacting protein 1 (SIP1), which has been discussed as a negative regulator of E-cadherin gene expression. We demonstrate that SIP1 upregulation shows an inverse relationship with E-cadherin in advanced pancreatic tumour stages. In Panc-1 cells, SIP1 expression can be induced by exposure to collagen type I in a src-dependent manner. In addition, overexpression of SIP1 reduces E-cadherin mRNA and protein levels. Taken together, these results suggest that SIP1 is involved in the progression of pancreatic cancer and plays a role in mediating signal transduction from collagen type I to downregulate E-cadherin expression.     

Reduced gene expression of E-cadherin and associated catenins in human cervical carcinoma cell lines

Cell–cell adhesion mediated by E-cadherin is often lost or disturbed in human carcinomas. For regular adhesive function, E-cadherin has to form complexes with peripheral cytoplasmic catenins which are multifunctional proteins that are also involved in signal transduction and growth regulation. We have analyzed the expression levels of the genes encoding -catenin, β-catenin and plakoglobin in correlation to the E-cadherin expression levels in cell lines derived from human cervical carcinomas. Reduced mRNA and protein levels were detected for plakoglobin, whereas - and β-catenin showed only reduced protein (but not mRNA) levels. The alterations in catenin gene expression were often associated with absent or reduced E-cadherin. The findings indicate that a reduction of catenin gene expression may contribute to the development of cervical carcinomas.     

Clinical value of serum hyaluronan and propeptide of type III collagen in patients with pancreatic cancer

Hyaluronan (HA) and collagen are highly expressed in pancreatic cancer (PC) stroma. HA and collagen accumulation increase tumor interstitial fluid pressure, compromising blood flow and drug penetration. The aim of this biomarker study was to determine the clinical utility of serum HA and the propeptide of type III collagen (PRO-C3) in patients with PC. A cohort from the Danish BIOPAC study (NCT03311776) including patients with histologically confirmed pancreatic ductal adenocarcinoma (n = 809), ampullary carcinoma (n = 44), distal biliary tract cancer (n = 31), chronic pancreatitis (n = 15), intraductal papillary mucinous neoplasm (n = 41), duodenal adenoma (n = 7) and no cancer (n = 25). Healthy controls were available for serum HA (n = 141) and PRO-C3 (n = 8). The main outcome was overall survival (OS) of patients with PC in relation to pretreatment serum HA and PRO-C3 levels. Patients with PC had higher baseline serum HA and PRO-C3 than healthy subjects and patients with benign conditions. Pretreatment serum baseline HA and PRO-C3 in patients with PC were associated with poorer survival and PRO-C3 remained prognostic also after adjusting for age, performance status, stage, the presence of liver and peritoneum metastasis, and CA19-9. Detection of HA and PRO-C3 may be useful in differentiating between malignant and benign pancreatic conditions. Serum HA and PRO-C3 were prognostic for OS in patients with PC.     

Clinical outcomes of downregulation of E-cadherin gene expression in non-small cell lung cancer

Objective: To investigate the promoter methylation status of the E-cadherin gene in non-small cell lung cancer(NSCLC) and its association with clinical pathological parameters, and to explore the relationship betweendownregulation of E-cadherin gene expression and the methylation status of its promoter region. Methods:Nested methylation-specific PCR was performed to examine CpG methylation within the 5’ CpG island of theE-cadherin gene in lung cancer and para-cancerous tissue from 37 patients with primary non-small cell lungcancer. Quantitative real-time PCR was performed to measure the level of E-cadherin mRNA. Results: Ofthirty-seven cases, 12 (32.4%) samples showed aberrant CpG methylation in tumor tissues compared with thecorresponding normal tissues. In addition, a reduction in E-cadherin mRNA levels was observed in 11 of the12 (91.7%) tumor tissues carrying a methylated E-cadherin gene. However, only 10 (43.5%) cases displayedreduced mRNA levels in tumor tissues from the remaining 23 cases (excluding 2 samples from which mRNA wasunavailable) without methylation events. Downregulation of E-cadherin gene expression significantly correlatedwith the promoter methylation status of this gene. Conclusion: These results provide strong evidence that themethylation status of E-cadherin gene contributes to a reduction in the expression of E-cadherin mRNA, andmay play a role in the development and progression of NSCLC.     

Inhibition of TF gene expression by antisense oligonucleotides in different cancer cell lines

Human tissue factor (TF) is the initiator of blood coagulation. Beside this function it is involved in tumor angiogenesis and metastasis. In the study we have evaluated the efficiency of antisense oligonucleotides (AS-ODNs) against TF selected from computational prediction of TF mRNA structure. Fourteen different AS-ODNs were tested in three cell lines of different origin with a high TF content. In cell line MCF-7 expression of TF gene was inhibited up to 50% by the AS-ODN AS-7 in comparison to reference. To investigate the dependence of inhibition efficiency on the AS-ODN position inside a potential target motive we designed further AS-ODNs shifted 2-3 nt among AS-7. One AS-ODN was found as more effective than AS-7. In cell line T508 were obtained moderate effects in inhibition of TF gene expression of 30% by AS-4. In J82 cells TF protein was inhibited up to 68% by two AS-ODNs. In conclusion, we compared inhibition of TF gene expression in different cancer cell lines and found that all effective AS-ODNs were located in the translated region of TF mRNA. Suitability of a target region of an AS-ODN is relatively independent on cell line. In contrast, optimal transfection conditions are dependent on cell line.     

Smad4 silencing in pancreatic cancer cell lines using stable RNA interference and gene expression profiles induced by transforming growth factor-beta

The transforming growth factor-beta (TGF-beta)-Smad signaling pathway inhibits the growth of human epithelial cells and plays a role in tumor suppression. The Smad4 gene is mutated or deleted in 50% of pancreatic cancers. In this study, we succeeded in establishing Smad4 knockdown (S4KD) pancreatic cancer cell lines using the stable RNA interference (RNAi) method. Smad4 protein expression was reduced dramatically and TGF-beta-Smad signaling was markedly inhibited in the S4KD cell lines. The S4KD and control cells were stimulated with TGF-beta and analysed using a cDNA microarray that contained 3756 genes, in order to screen for target molecules downstream of TGF-beta. The microarray analysis revealed that 187 S4KD genes and 155 genes in the control cells were regulated immediately upon TGF-beta stimulation. Quantitative RT-PCR analysis on several of these genes produced results that corroborated the outcome of the microarray analysis. Most of the genes in the S4KD and control cells identified by the array differed, which suggests signaling pathways that differ according to Smad4 status. Of the identified genes, 246 have not been reported previously as genes that lie downstream of TGF-beta. Genes that are involved in cell proliferation, adhesion, and motility were found to be regulated differentially with respect to S4KD and control cells. Cell migration induced by TGF-beta was inhibited in the S4KD cells, which might be associated with a different regulation of integrin beta7. The knock down of a specific gene using stable RNAi appears to be a promising tool for analysing endogenous gene function.     

Bile acids induce cyclooxygenase-2 expression in human pancreatic cancer cell lines

To investigate a possible link between bile acids and the pathogenesis of pancreatic cancer, we determined whether conjugated or unconjugated bile acids induced cyclooxygenase-2 (COX-2) in two human pancreatic cancer cell lines, BxPC-3 and SU 86.86. Bile acids are known promoters of gastric and colon cancer. We demonstrated previously that COX-2, an enzyme that catalyzes the synthesis of prostaglandins, is over-expressed in human pancreatic adenocarcinoma. Both human pancreatic cell lines were treated with conjugated and unconjugated bile acids. COX-2 mRNA and protein were determined. In addition, prostaglandin E2 (PGE2) synthesis was measured. Treatment with conjugated or unconjugated bile acids for 3 h up-regulated COX-2 mRNA. Chenodeoxycholate (CD) or deoxycholate at concentrations ranging from 12.5 to 100 micro M caused a dose-dependent induction of COX-2 protein with a maximal effect at 100 micro M. Induction of COX-2 protein by CD and deoxycholate was detected after treatment for 6 h with maximal induction at 12 h. Taurochenodeoxycholate, a conjugated bile acid, also caused dose-dependent induction of COX-2 but higher concentrations of bile acid (200-1200 micro M) were required. Levels of cyclooxygenase-1 were unaffected by bile acid treatment. Unconjugated and conjugated bile acids caused 7- and 4-fold increases in PGE2 production, respectively. Taken together, these findings suggest a possible role for bile acids in the pathogenesis of pancreatic cancer.     

BCL2 expression correlates with metastatic potential in pancreatic cancer cell lines

BACKGROUND: Programmed cell death (termed apoptosis) regulates normal tissue homeostasis. Loss of local paracrine signals and intercellular adhesion molecules are potent inducers of apoptosis and thereby eliminate normal cells that may have escaped beyond the confines of the local organ environment. Dysregulation in the expression of the BCL2 gene family, the prototypic regulators of apoptosis, is a common occurrence in cancer and imparts resistance to standard triggers of apoptosis. Therefore, the authors sought to examine whether abnormal BCL2 gene family expression correlated with resistance to apoptosis and increased metastatic potential in pancreatic carcinoma. METHODS: The authors examined BCL2 expression and apoptotic sensitivity in three panels of human pancreatic cancer cell lines that possess varying metastatic potential. Stable transfectants were generated that overexpress BCL2. These transfectants were then analyzed for differences in metastasis formation in athymic mice. RESULTS: Among the isogenic panels of pancreatic cancer cell lines, BCL2 expression levels correlated with metastatic potential. Highly metastatic variants of each family of cell lines were more resistant to induction of apoptosis. Finally, using the BCL2 transfectant in a xenograft model, elevated BCL2 expression led to a higher incidence of metastases. CONCLUSIONS: The authors conclude that increased BCL2 expression correlates with apoptotic resistance and metastatic potential; dysregulation of BCL2 expression may be involved in the metastatic progression of pancreatic carcinoma.     

人乳腺癌和胰腺癌组织及其细胞株Survivin表达定位差异的研究

目的:检测Survivin基因在乳腺癌和胰腺癌组织及其细胞株中的表达,观察其表达定位。方法:采用免疫细胞化学和免疫组织化学技术,分别检测乳腺癌MCF-7细胞、胰腺癌PC-2细胞以及180例乳腺癌组织、30例胰腺癌组织中Survivin的表达,观察其表达定位情况。结果:免疫细胞化学的检测结果表明,Survivin在乳腺癌MCF-7细胞和胰腺癌PC-2细胞中均呈阳性表达,其表达定位于胞质;而免疫组化的检测结果表明,Survivin在乳腺癌组织中的表达定位于胞核,其阳性表达率为66.1%(119/180)。在胰腺癌组织中,Sur-vivin的表达定位主要位于胞核,同时胞质有弱表达,其阳性表达率为73.3%(22/30)。结论:Survivin在肿瘤细胞中可以是胞核表达或胞质表达,也可以是胞核与胞质共表达,不同的表达定位可能代表着Survivin的不同功能。     

ZONAB和E-cadherin在膀胱癌细胞系中的表达及RNA干扰ZONAB表达对癌细胞侵袭力的影响

目的:探讨慢病毒介导ZONAB基因的RNA干扰对膀胱癌侵袭力的影响.方法:用Realtime PCR法分别检测人类尿路上皮永生细胞系sv-huc-1和膀胱尿路上皮癌细胞系UM-UC-3、T24、5637中ZONAB和E-cadherin的mRNA表达水平,用Western blot法分别检测各细胞系中ZONAB蛋白表达水平,设计、合成干扰靶点,构建纯化重组慢病毒,感染人膀胱癌UM-UC-3细胞,根据ZONAB基因的抑制率,筛选最有效的ZONAB基因RNAi靶序列组,验证ZONAB基因的沉默效果,用Transwell侵袭试验检测UM-UC-3细胞体外侵袭力的改变.结果:Realtime PCR法和Western blot法测得UM-UC-3、T24、5637中ZONAB的表达水平高于sv-huc-1,均具有显著性差异(P<0.05);而Realtime PCR法测得UM-UC-3、T24、5637中 E-cadherin的mRNA表达水平低于sv-huc-1(P<0.05).成功构建ZONAB基因RNA干扰慢病毒载体并获得相应的慢病毒,与对照组相比RNA干扰组UM-UC-3细胞ZONAB基因mRNA水平的抑制率为71.4%(P<0.05),蛋白水平抑制率为76.8%,其穿过人工基底膜的平均细胞数为13.1±2.8/HP,明显少于阴性对照组和空白对照组(P<0.05).结论:ZONAB在膀胱癌细胞系中表达上调,慢病毒介导ZONAB基因的RNA干扰能够抑制UM-UC-3细胞侵袭.     

Human UDP-Glucuronosyltransferases: Effects of altered expression in breast and pancreatic cancer cell lines

Increased aerobic glycolysis and de novo lipid biosynthesis are common characteristics of invasive cancers. UDP-glucuronosyltransferases (UGTs) are phase II drug metabolizing enzymes that in normal cells possess the ability to glucuronidate these lipids and speed their excretion; however, de-regulation of these enzymes in cancer cells can lead to an accumulation of bioactive lipids, which further fuels cancer progression. We hypothesize that UGT2B isoform expression is down-regulated in cancer cells and that exogenous re-introduction of these enzymes will reduce lipid content, change the cellular phenotype, and inhibit cancer cell proliferation. In this study, steady-state mRNA levels of UGT isoforms from the 2B family were measured using qPCR in 4 breast cancer and 5 pancreatic cancer cell lines. Expression plasmids for UGT2B isoforms known to glucuronidate cellular lipids, UGT2B4, 2B7, and 2B15 were transfected into MCF-7 and Panc-1 cells, and the cytotoxic effects of these enzymes were analyzed using trypan blue exclusion, annexin V/PI staining, TUNEL assays, and caspase-3 immunohistochemistry. There was a significant decrease in cell proliferation and a significant increase in the number of dead cells after transfection with each of the 3 UGT isoforms in both cell lines. Cellular lipids were also found to be significantly decreased after transfection. The results presented here support our hypothesis and emphasize the important role UGTs can play in cellular proliferation and lipid homeostasis. Evaluating the effect of UGT expression on the lipid levels in cancer cell lines can be relevant to understanding the complex regulation of cancer cells, identifying the roles of UGTs as “lipid-controllers” in cellular homeostasis, and illustrating their suitability as targets for future clinical therapy development.