Dysadherin expression facilitates cell motility and metastatic potential of human pancreatic cancer cells

Dysadherin is a membrane glycoprotein expressed strongly in several human cancers. Overexpression of dysadherin in tumor cells is closely associated with malignant phenotype (e.g., metastasis) and poor prognosis. In our analysis, six pancreatic cancer cell lines showed a positive correlation between dysadherin expression and cell motility. Introduction of small interfering RNA (siRNA) against dysadherin into the Panc-1 cell line caused reduction of dysadherin expression and suppression of cell motility. In contrast, stable transfection of a dysadherin expression vector into the Capan-1 cell line increased cell motility. In vivo, the metastatic potential of orthotopically transplanted Capan-1 tumor cells in severe combined immunodeficient mice was increased by dysadherin overexpression. Cell morphology and actin organization were also influenced by modulation of dysadherin expression. Cells transfected with dysadherin siRNA tended to have a relatively larger, more spread shape and increased transverse actin stress fibers compared with parent cells and cells transfected with control siRNA. Our study suggests that dysadherin is able to modulate actin structures, stimulate cell motility, and contribute directly to the metastatic potential of human pancreatic cancer cells.     

Hormone resistance,invasiveness, and metastatic potential in breast cancer

Summary Critical phenotypic changes that occur during the progression of breast cancer include the loss of hormone-dependence, acquired resistance to systemic therapies, and increased metastatic potential. We have isolated a series of MCF-7 human breast cancer variants which exhibit hormone-independent growth, antiestrogen resistance, and increased metastatic potential. Analysis of the phenotypes of these variants strongly suggests that changes in the expression of specific genes may be critical to the generation of phenotypic diversity in the process of malignant progression in breast cancer. Epigenetic changes may contribute significantly to the generation of these phenotypic changes observed during breast cancer progression. Many of the characteristics of the progressed phenotypes appear to have arisen in response to appropriate selective pressures (growth in ovariectomized nude mice; growth in the presence of antiestrogens). These observations are consistent with the concept of clonal selection and expansion in the process of malignant progression.     

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.     

Heparanase expression in primary and metastatic pancreatic cancer.

The human endoglycosidase heparanase (hpa) degrades heparan-sulfate proteoglycans, which constitute prominent components of basement membranes and extracellular matrix. Due to the critical function of hpa in cancer cell invasion and metastasis, we have analyzed the expression of hpa in human primary and metastatic pancreatic cancer as well as in the normal pancreas and in chronic pancreatic inflammation. By real-time quantitative PCR, there was a 7.9- and 30.2-fold increase of hpa mRNA in chronic pancreatitis and pancreatic cancer tissue samples, respectively, in comparison with normal pancreatic tissues. There was a significant correlation between enhanced hpa mRNA expression and shorter postoperative patient survival. hpa mRNA and protein localized in the cancer cells of primary and metastatic pancreatic cancer, with a preferentially higher expression at the primary tumor site. Cultured pancreatic cancer cells transfected with a full-length hpa construct displayed enhanced invasiveness in an invasion chamber assay. These results suggest that hpa overexpression in human pancreatic cancers facilitates cancer cell invasion, thereby enhancing the metastatic potential of the tumors.     

CXCL14 expression and potential function in pancreatic cancer

LAPTM4B was proven to overexpress in hepatocellular carcinoma and relate to differentiation. We immunohistochemically investigated the expression and potential clinicopathological and prognostic significance of LAPTM4B encoded protein, LAPTM4B-35, in extrahepatic cholangiocarcinoma (EHCC) for specimens from consecutive 81 patients. LAPTM4B-35 staining was positive in cancer tissues from 59 patients (72.8%), including 12 with score 1, 22 with score 2 and 25 with score 3. No positive staining was found in non-cancer epithelia. The staining score in cancer tissues was not only significantly associated with TNM staging, histological grade, perineural and lymph node invasion (P < 0.05), but also of comprehensive prognostic implications, including integrated estimation with CA19-9. These data established that LAPTM4B-35 positively expressed in a great portion of EHCC and might be a novel molecular maker of progression, invasiveness and poor prognosis.     

Epidermal growth factor-mediated NF-kappaB activation promotes uPA expression and invasiveness in pancreatic cancer cells

OBJECTIVE: To determine the effect of EGF on the invasiveness of pancreatic cancer cells and its related regulatory mechanism. METHODS: The effects of EGF on the proliferation, adhesion and invasion of pancreatic cancer cells were detected by WST-1 proliferation assay, adhesion assay and invasive assay. The expression of uPA was assayed by Western blot and RT-PCR. The activity of NF-kappaB was examined by EMSA. RESULTS: EGF significantly increased the invasiveness of pancreatic cancer cells but did not affect cell proliferation or adhesion. Increased invasiveness was associated with the induction of uPA at both mRNA and protein levels. Furthermore, EGF stimulated the NF-kappaB binding activity, and pretreatment of cells with a NF-kappaB inhibitor, pyrrolidine dithiocarbamate, markedly attenuated EGF-induced NF-kappaB activation. Subsequently, the EGF-induced uPA expression and invasiveness were also inhibited by NF-kappaB inhibitor. CONCLUSION: Our findings indicated that NF-kappaB-mediated up-regulation of uPA expression is responsible for EGF-induced invasiveness in pancreatic cancer cells, and implicate that such anti-NF-kappaB therapy with NF-kappaB inhibitors may contribute to the reduction of invasiveness of pancreatic cancer.     

Treatment of metastatic pancreatic cancer

Pancreatic adenocarcinoma represents the fourth-leading cause of cancer-related mortality in the United States. The vast majority of patients are diagnosed at advanced stages of the disease when surgery is no longer an option. For these patients, systemic therapy remains the mainstay of care. Although single-agent gemcitabine has remained the standard of care since its approval in 1997, improvements in patient outcomes may potentially be realized by (1) applying pharmacokinetic principles to optimize drug delivery, such as the administration of gemcitabine at a "fixed-dose rate" infusion; (2) combining gemcitabine with other cytotoxic agents for which evidence of synergy exists, such as platinum compounds; and (3) integrating novel targeted agents such as bevacizumab, erlotinib, and cetuximab into treatment paradigms, based on an increasing understanding of the molecular pathways that govern pancreatic tumor growth and maintenance. This article provides the evidence to support each of these approaches and highlights future directions in the management of metastatic pancreatic cancer.     

RECK expression in pancreatic cancer: its correlation with lower invasiveness and better prognosis.

BACKGROUND: The reversion-inducing cysteine-rich protein with Kazal motifs (RECK) gene was initially isolated as a transformation suppressor gene. The RECK gene is expressed widely in normal organs but is undetectable in many tumor-derived cell lines. When artificially expressed in such cell lines, RECK negatively regulates at least matrix metalloprotease (MMP)-9, MMP-2, and MT1-MMP activation and suppresses the invasive and metastatic potentials of these cells. Clinical relevance of these observations, however, is yet to be established. The aim of this study was to examine RECK expression in pancreatic cancer, where intensive invasiveness and metastasis are frequently observed, and investigate its clinical significance. We also analyzed the correlation between RECK expression and MMP activation. METHODS: (a) RECK expression in surgically resected tissue samples of invasive ductal carcinomas of the pancreas (n = 50) was examined immunohistochemically, and its correlation with clinicopathological factors was analyzed; and (b) gelatin zymography was used for the detection of latent and activated forms of MMP-2 and MMP-9 in some of the tissue samples (n = 33). The gelatinase activity was quantified by densitometory, and the ratio of intensity of the active MMP-2 band to the total intensity of the pro- and active MMP-2 bands was evaluated as an indicator of MMP-2 activation. The MMP-9 activation was also studied. RESULTS: Among the 50 ductal carcinoma samples, 26 (52%) were stained positive for RECK. In the normal pancreas, both acinar and beta cells were stained positive, but ductal cells did not. Tumors with positive RECK staining were significantly less invasive as compared with RECK-negative tumors (P = 0.0438). Importantly, patients who had tumors with high RECK expression showed significantly better prognosis than those who had RECK-negative tumors (P = 0.0463, by Log-rank test). Zymographic analysis indicated significant inverse correlation between the level of RECK expression and extent of MMP-2 activation (P = 0.0374). CONCLUSIONS: Our findings support the hypothesis that the RECK protein has negative effects on the invasiveness of pancreatic cancer by inhibiting MMP-2 activation and suggest the potential value of RECK as a prognostic molecular marker for pancreatic cancer.     

黏蛋白4在胰腺上皮内瘤变和胰腺癌中的表达差异性分析

目的 探讨黏蛋白4（MUC4）在胰腺上皮内瘤变（PanINs）和胰腺导管腺癌（PDAC）中的表达及临床意义。方法 收集2009年3月1日至2011年12月31日第二军医大学附属长征医院的胰腺组织蜡块标本共85例。采用免疫组化SP法检测MUC4在48例正常胰腺导管（NP）、17例PanINs及20例PDAC组织中的表达情况。分析MUC4的表达与PDAC临床病理特征及预后的关系。结果 MUC4在NP组织中不表达;随着胰腺组织异型程度的增加,MUC4的表达逐渐增强;MUC4在NP、PanIN-1、PanIN-2、PanIN-3及PDAC组织中的阳性表达率分别为0、17.4%、52.6%、84.6%和90.0%;免疫组化评分分别为0、1.30±089、2.58±1.76、4.54±1.64和7.68±2.34,组间比较差异有统计学意义（P＜0.001）。MUC4在PDAC组织中的表达与神经浸润（P=0.028）、淋巴结转移（P=0.020）和CA19-9（P=0.028）有关。20例PDAC患者的中位总生存时间为17.0个月（95%CI：14.809～19.191个月）;MUC4高表达者（免疫组化评分≥8.8分）为13.0个月（95%CI：7.456～18.544个月）,MUC4低表达者（免疫组化评分＜8.8分）为20.0个月（95%CI：15.521～24.479个月）,差异有统计学意义（P=0.003）。结论 MUC4可能参与了PDAC的发生、发展,其表达升高可能是PDAC演进的早期事件,MUC4高表达可能对PDAC的浸润和转移均有影响并提示预后不良。     

EGF介导的NF-κB促进体外胰腺癌细胞的uPA表达与侵袭力

目的探讨表皮生长因子(EGF)促进胰腺癌细胞侵袭和转移的分子机制。方法用WST-1细胞增殖实验、细胞黏附实验和Transwell体外侵袭实验检测EGF对胰腺癌细胞系NOR-P1的增殖、黏附及侵袭能力的影响。采用Western blot和逆转录-聚合酶链反应(RT-PCR)检测uPA的表达。用凝胶电泳迁移实验检测核因子-κB(NF-κB)活性。结果EGF能够明显促进胰腺癌细胞的侵袭能力,但对胰腺癌细胞的黏附力及增殖并无明显影响。EGF明显上调胰腺癌细胞的NF-κB活性和尿激酶型纤溶酶原激活物(uPA)表达。NF-κB抑制物四氢化吡咯二硫代氨基甲酸酯(PDTC)能够明显抑制EGF所诱导的NF-κB活性,同时也抑制EGF所诱导的uPA表达及胰腺癌细胞的侵袭力。结论EGF通过活化NF-κB促进胰腺癌细胞的uPA表达和侵袭力,采用NF-κB抑制剂阻断NF-κB通路有利于胰腺癌的综合治疗。     

Claudin-4在胃癌中的表达及临床病理意义

目的探讨Claudin-4在胃癌中的表达及其临床病理意义。方法收集福建医科大学附属厦门第一医院2007年9月至2009年9月部分胃癌手术标本共68例。其中20例分别制成石蜡切片和留取新鲜冰冻标本,分别应用免疫组织化学染色方法和实时定量PCR方法检测该20例胃癌标本中Claudin-4蛋白和mRNA在胃癌组织、正常胃组织中的表达情况。另48例胃癌手术标本仅制成石蜡切片,采用免疫组织化学染色方法检测Claudin-4蛋白在胃癌组织中的表达情况。分析Clau-din-4表达情况与胃癌分化、浸润、转移和组织分型间的相关性。结果胃癌组织中Claudin-4的表达显著高于正常胃上皮组织（P〈0.05）;Claudin-4在Lauren分型肠型胃癌和BorrmannⅠ型、Ⅱ型胃癌组织中的表达分别显著高于弥漫型胃癌和BorrmannⅢ型、Ⅳ型胃癌（P〈0.05）;Claudin-4的表达与胃癌分化相关,胃癌分化越好,Claudin-4表达越高（P〈0.05）。结论 Claudin-4与胃癌的发生、发展及胃癌的生物学行为密切相关,并可能成为预测胃癌生物学行为的重要指标。