Cleavage of L1 in exosomes and apoptotic membrane vesicles released from ovarian carcinoma cells.

PURPOSE: The L1 adhesion molecule (CD171) is overexpressed in human ovarian and endometrial carcinomas and is associated with bad prognosis. Although expressed as a transmembrane molecule, L1 is released from carcinoma cells in a soluble form. Soluble L1 is present in serum and ascites of ovarian carcinoma patients. We investigated the mode of L1 cleavage and the function of soluble L1. EXPERIMENTAL DESIGN: We used ovarian carcinoma cell lines and ascites from ovarian carcinoma patients to analyze soluble L1 and L1 cleavage by Western blot analysis and ELISA. RESULTS: We find that in ovarian carcinoma cells the constitutive cleavage of L1 proceeds in secretory vesicles. We show that apoptotic stimuli like C2-ceramide, staurosporine, UV irradiation, and hypoxic conditions enhance L1-vesicle release resulting in elevated levels of soluble L1. Constitutive cleavage of L1 is mediated by a disintegrin and metalloproteinase 10, but under apoptotic conditions multiple metalloproteinases are involved. L1 cleavage occurs in two types of vesicles with distinct density features: constitutively released vesicles with similarity to exosomes and apoptotic vesicles. Both types of L1-containing vesicles are present in the ascites fluids of ovarian carcinoma patients. Soluble L1 from ascites is a potent inducer of cell migration and can trigger extracellular signal-regulated kinase phosphorylation. CONCLUSIONS: We suggest that tumor-derived vesicles may be an important source for soluble L1 that could regulate tumor cell function in an autocrine/paracrine fashion.     

Secretion of soluble complement inhibitors factor H and factor H-like protein (FHL-1) by ovarian tumour cells

We observed that the soluble complement regulators factor H and factor H-like protein were abundantly present in ascites samples as well as in primary tumours of patients with ovarian cancer. RT-PCR and immunoblotting analyses showed that the two complement inhibitors were constitutively produced by the ovarian tumour cell lines SK-OV-3 and Caov-3, but not PA-1 or SW626 cells. The amounts of factor H-like protein secreted were equal to those of factor H. This is exceptional, because e.g. in normal human serum the concentration of factor H-like protein is below 1/10th of that of factor H. In ascites samples the mean level of factor H-like protein (130+/-55 microg ml(-1)) was 5.5-fold higher than in normal human serum (24+/-3 microg ml(-1)). Ovarian tumour cells thus preferentially synthesise factor H-like protein, the alternatively spliced short variant of factor H. The tumour cells were found to bind both (125)I-labelled factor H and recombinant factor H-like protein to their surfaces. Surprisingly, the culture supernatants of all of the ovarian tumour cell lines studied, including those of PA-1 and SW626 that did not produce factor H/factor H-like protein, promoted factor I-mediated cleavage of C3b to inactive iC3b. Subsequently, the PA-1 and SW626 cell lines were found to secrete a soluble form of the membrane cofactor protein (CD46). Thus, our studies reveal two novel complement resistance mechanisms of ovarian tumour cells: (i) production of factor H-like protein and factor H and (ii) secretion of soluble membrane cofactor protein. Secretion of soluble complement inhibitors could protect ovarian tumour cells against humoral immune attack and pose an obstacle for therapy with monoclonal antibodies.     

Marker profile of mesothelial cells versus ovarian carcinoma cells

We investigated the marker profile of human ascitic and cultured mesothelial cells, and compared it to that of ovarian carcinoma cells which are related in terms of their histogenesis, unrelated colon carcinomas being used as reference. Mesothelial and ovarian carcinoma cells could not be distinguished by (intermediate) filament typing, using monoclonal antibodies (MAbs) to keratins, vimentins and desmins. Colon carcinomas differed from mesothelial cells and ovarian carcinomas by the absence of keratin-7 filaments. The epithelial marker BW 495/36 was completely negative on mesothelial cells and positive on all ovarian and colon carcinoma cells. While CEA was found on about 85% of all colon carcinomas, CEA expression on mesothelial cells and ovarian carcinoma cells was below 20%. The ovarian carcinoma markers (OV-TL 3, OV-TL 10, OC 125, MOV 18) were strongly positive on ovarian carcinomas and negative on colon carcinomas (or limited to traces of immunofluorescence on some samples). Although the mesothelial cells showed weak or negative reactivity with these markers, OC 125 antigen was found by immunoelectron microscopy on the surface of cultured mesothelial cells, and was shed in the culture supernatant at concentrations of 50, 28, and 25 CA 125 U/ml/10(4) positive cells. This suggests that mesothelial cells may be responsible for the synthesis of CA 125 in ascitic fluid. The data indicate that ovarian carcinomas, mesothelial cells and colon carcinomas can be distinguished using a combination of anti-keratin antibodies with BW 495/36 and anti-ovarian carcinoma markers.     

L1 augments cell migration and tumor growth but not beta3 integrin expression in ovarian carcinomas

L1 is a neural cell adhesion molecule involved in cell migration, axon growth and guidance. Recent data have shown that L1 is overexpressed in ovarian and endometrial tumors and is associated with bad prognosis. How L1 promotes tumor progression is presently unknown. Here we show that L1 expression is predominantly confined to the invasive front of ovarian carcinomas. Overexpression of L1 in carcinoma cell lines by adenovirus-mediated gene transfer enhanced the haptotactic cell migration on extracellular matrix proteins. Expression of L1 augmented tumor growth of carcinomas xenografted in nonobese diabetic/severe combined immunodeficient mice (NOD/SCID). A recent report has demonstrated L1-dependent upregulation of beta3 integrin involving activation of the extracellular signal-regulated kinase (erk) pathway. We find that L1 and beta3 integrin are not coexpressed in ovarian carcinoma tissues. Overexpression of L1 did not upregulate beta3 integrin in ovarian carcinoma cell lines but could do so in HEK293 cells. Our results suggest that L1 could drive progression by enhancing cell migration and tumor growth but that L1 dependent and erk-regulated gene expression requires cell-type specific elements.     

NRP-1单克隆抗体对乳腺癌裸鼠移植瘤生长的影响

 目的 探讨NRP-1单克隆抗体（NRP-1 MAb）的特异性，以及不同剂量的NRP-1 MAb治疗乳腺癌裸鼠移植瘤的疗效。方法 Western blot和共聚焦免疫荧光法检测NRP-1 MAb是否识别MCF7细胞上NRP-1蛋白。将MCF7细胞接种于BALB/c裸鼠皮下建立乳腺癌细胞移植瘤模型，并进行瘤组织传代。传代的肿瘤体积生长至300~500 mm3时，随机分为对照组、NRP-1 MAb低剂量组、中剂量组和高剂量组，每组6只，给药7次。观察荷瘤裸鼠一般状况，测量瘤体大小及裸鼠体重。实验结束时剥离瘤体称重，提取组织蛋白，Western blot检测组织中VEGF蛋白和NRP-1蛋白的表达量。结果 NRP-1MAb成功识别MCF7细胞上的NRP-1蛋白；NRP-1 MAb能够有效抑制MCF7细胞裸鼠移植瘤的生长，低剂量组（1 mg/kg）抑瘤率为47.01%，中剂量组（5 mg/kg）抑瘤率为65.70%，高剂量组（10 mg/kg）抑瘤率为69.19%。。结论 NRP-1 MAb能够识别并有效结合MCF7细胞膜上的NRP-1蛋白，且可抑制MCF7细胞移植瘤的生长，NRP-1 MAb抑制移植瘤的增长可能与下调NRP-1和VEGF表达有关。     

Neuropilin-1 is differentially expressed in myoepithelial cells and vascular smooth muscle cells in preneoplastic and neoplastic human breast: a possible marker for the progression of breast cancer

The expression and distribution of neuropilin-1 (NRP-1) was examined in the samples of normal human breast tissues and in non-neoplastic and neoplastic areas of breast tissue removed for carcinoma using RT-PCR as well as conventional and tissue microarrays immunohistochemical analyses. The NRP-1 mRNA expression was significantly higher in neoplastic tissues as compared to normal breast samples. Immunohistochemically, the myoepithelial cells of the mammary ducts and lobules display positive reactions for NRP-1, whereas the inner ductal and lobular epithelial cell layers failed to react. The myoepithelial cells of ducts and lobules in both neoplastic and non-neoplastic tissue specimens displayed a stronger positive reaction for NRP-1 than those in the normal breast. A positive reaction for NRP-1, but with a gradual reduction in intensity, was observed in the myoepithelial cells of ducts with atypical epithelial hyperplasia and ductal carcinoma in situ (DCIS). The reaction was undetected or minimally detected in the areas of invasive carcinoma. NRP-1 positive immunolabeling was also localized in the vascular smooth muscle cells and in some endothelial cells of the blood vessels in normal, non-neoplastic and neoplastic breast tissue samples. In areas of breast carcinoma, NRP-1 immunolabeling was more prominent in both vascular smooth muscle cells and in some endothelial cells than in similar cells in normal breast. The specificity of the newly developed antibody for NRP-1 was confirmed by in situ hybridization with DIG-labeled PCR generated probe. These results suggest that NRP-1 may be a multiple function protein in human breast and may be involved in the induction of local invasiveness of neoplasia and angiogenesis and have direct relevance to the progression of breast cancer.     

Reduced expression of death-associated protein kinase in human uterine and ovarian carcinoma cells

The expression of the death-associated protein kinase (DAPK) protein and promoter methylation in 11 human uterine and ovarian carcinoma cell lines originally established from histopathologically-different carcinoma tissues were examined to investigate the relationship between DAPK and carcinogenesis in female reproductive tissues. The 11 cell lines included three cervical carcinomas, three endometrial carcinomas and five ovarian carcinomas. Western blot analysis showed no detectable expression of DAPK protein in 4 cell lines (ME180, HOKUG, MCAS and OVK-18) while moderate levels of DAPK protein were readily detected in normal human endometrium, and normal murine uterus and ovary. Methylation-specific PCR of the 11 cell lines revealed that 5 carcinoma cell lines (ME180, HOKUG, MCAS, OVK-18 and HEC-1) expressed hypermethylated promoters in the DAPK genes, while DAPK promoters in the other 6 carcinoma cell lines remained unmethylated. These results indicate that DAPK protein expression is reduced or silenced in some human uterine and ovarian carcinoma cells by methylation of the DAPK gene promoter region. Therefore, reduced DAPK expression and methylation of the DAPK promoter may be involved in carcinogenesis of human uterine and ovarian tissues.     

Proteolytic activation of heparin-binding EGF-like growth factor by membrane-type matrix metalloproteinase-1 in ovarian carcinoma cells

Increased expression of heparin-binding EGF-like growth factor (HB-EGF) and membrane-type matrix metalloproteinase-1 (MT1-MMP) is frequently associated with various types of malignant tumor. HB EGF-like growth factor has been reported to promote the malignant progression of ovarian carcinoma. Based on this finding, inhibition of HB-EGF activity with CRM197 is now under phase I clinical evaluation. On the other hand, MT1-MMP expressed in ovarian carcinoma cells is thought to promote invasion and growth of tumor cells by degrading the extracellular matrix. However, we recently demonstrated that co-expression of MT1-MMP and HB-EGF in gastric carcinoma cells leads to cleavage of HB-EGF within its N-terminal heparin-binding region, converting it into a potent heparin-independent growth factor. In this study, we evaluated the importance of regulation of HB-EGF by MT1-MMP in clinical samples of ovarian carcinoma. We detected co-expression of HB-EGF and MT1-MMP in clear cell ovarian carcinoma tissues, particularly at the invasion front and in tumor cells that had disseminated into the ascites, whereas HB-EGF alone was expressed in non-invasive borderline ovarian tumor tissue. Furthermore, a soluble HB-EGF fragment that corresponds to that processed by MT1-MMP was detected in malignant ascites obtained from patients with metastatic ovarian carcinoma. Ovarian carcinoma cells that express MT1-MMP and HB-EGF exhibited enhanced cell growth in a 3D-collagen matrix and anchorage-independent growth in suspension. These results indicate that MT1-MMP co-expressed with HB-EGF in ovarian carcinoma cells potentiates the activity of HB-EGF to promote invasive tumor growth and spreading in vivo.     

Neuropilin-1 在胰腺癌组织及细胞系中的表达

 目的 了解Neuropilin-1在胰腺癌组织、癌旁组织及胰腺癌细胞系中的表达情况。方法 运用免疫组化法和RT-PCR法分别检测Neuropilin-1及其mRNA在胰腺癌组织、癌旁组织及细胞系中的表达。结果 免疫组化检测发现18例胰腺癌组织标本中Neuropilin-1均呈高表达，而癌旁组织中无一例表达；RT-PCR检测rnRNA的表达结果显示14例胰腺癌组织中有9例表达，癌旁组织中无一例表达，Panc-1、Asps-1、Bxp-3细胞系中均表达。结论 Neuropilin-1表达于大多数胰腺癌组织及细胞系中，而在癌旁组织中不表达，提示Neuropilin-1的表达可能与胰腺癌的发生发展密切相关。     

Increased expression of dipeptidyl peptidase IV in human mesothelial cells by malignant ascites from ovarian carcinoma patients

Cell surface aminopeptidases play an important role in biological processes through degradation of small peptides. There are many bioactive peptides in ascites and these peptides are involved in carcinoma cell dissemination and infiltration. In human mesothelial cells dipeptidyl peptidase IV (DPPIV) shows the highest expression mostly in four cell surface aminopeptidases: aminopeptidase A, neutral endopeptidase 24-11, aminopeptidase N and DPPIV. Since mesothelial cells are always in contact with ascites, we examined the influence of malignant ascites on DPPIV. DPPIV enzyme activity in mesothelial cells was enhanced by the addition of ascites obtained from ovarian carcinoma patients in a time- and concentration-dependent manner, and flow cytometry and immunocytochemistry also revealed an increased expression of DPPIV on the cell surface of mesothelial cells. The <3-kD fraction of malignant ascites increased the DPPIV enzyme activity to the same level as the total ascites. Northern hybridization demonstrated that DPPIV mRNA was increased 3-fold by the addition of the <3-kD malignant ascites. In conclusion, DPPIV is highly expressed in human mesothelial cells and was regulated by ascites.     

NRP-1过表达对乳腺癌细胞MDA-MB-231、SK-BR-3生物学行为的影响

目的 通过上调乳腺癌细胞MDA-MB-231、SK-BR-3中NRP-1的表达,观察NRP-1对细胞增殖、凋亡、迁移及侵袭能力的影响。方法 构建pcDNA3.1-NRP-1表达载体,脂质体介导NRP-1 表达质粒转染MDA-MB-231、SK-BR-3细胞,用G418筛选出稳定转染的乳腺癌细胞株。利用RTqPCR、Western blot法分别检测NRP-1基因mRNA及其蛋白表达;CCK-8法、AnnexinⅤ-APC/7-AAD法、Transwell小室分别检测转染细胞增殖率、凋亡率及侵袭、迁移能力。结果 成功构建pcDNA3.1- NRP-1表达载体,转染MDA-MB-231、SK-BR-3细胞并筛选稳定表达系。与对照组相比,过表达组细胞的NRP-1 mRNA及蛋白表达水平明显升高（均P<0.05）;NRP-1过表达组的细胞较对照组增殖率增加、凋亡率降低、侵袭及迁移能力增强（均P<0.05)。结论 NRP-1在乳腺癌发展、浸润、转移中起着一定的作用,它可促进乳腺癌细胞增殖、迁移和侵袭,抑制其凋亡。     

Monoclonal antibodies against mesothelial membrane antigen discriminate between malignant mesothelioma and lung adenocarcinoma

Monoclonal antibodies (MAbs) were generated by immunizing mice with the mesothelioma cell line SPC111 and selected by indirect immunofluorescence on viable cells. Indirect immunofluorescence staining and radioimmunoassays demonstrated selective binding of the antibodies ME1 and ME2 with the surface membrane of mesothelioma, but not with lung adenocarcinoma cell lines. Lung small-cell carcinoma cell lines were unreactive, while staining was seen in a proportion of lung squamous-cell carcinoma cell lines. The antibodies were unreactive with other cell lines, including breast, colon, ovarian, and renal-cell carcinoma, leukemia, and lung fibroblast. The antibodies stained normal mesothelial cells, but were unreactive with normal bronchial epithelial cells in primary cultures, or peripheral blood cells. Immunohistochemical staining of cryostat sections of tumor tissues confirmed the ability of the antibodies to distinguish between mesothelioma and lung adenocarcinoma. All 12 mesothelioma tissues, but none of 9 lung adenocarcinomas or large-cell carcinomas, stained with the MAbs. Staining of malignant mesothelioma tissues was very homogeneous. Some lung squamous-cell carcinomas and breast carcinomas were stained focally by both, and some ovarian carcinomas by one antibody. Solid-phase radioimmunoassays demonstrated antigen sensitivity to chymotrypsin digestion and binding competition between the antibodies. The antibodies ME1 and ME2 identify a surface membrane antigen with preferential expression on normal and malignant mesothelial cells. They distinguish malignant mesothelioma from lung adenocarcinoma on cryostat sections and promise to be useful tools in biological studies of mesothelial cells.     

Selectivity of TAG-72-targeted adenovirus gene transfer to primary ovarian carcinoma cells versus autologous mesothelial cells in vitro.

Efficient gene transfer by recombinant adenovirus (Ad) vectors depends on expression of CAR and alpha(v) integrin on target cells. Because Ad may also infect nearby nontarget cells expressing these receptors, such as peritoneal mesothelial cells after i.p. injection, we hypothesized that targeting Ad gene delivery to a receptor overexpressed on most ovarian carcinoma cells, such as TAG-72, would enhance the selectivity of Ad gene transfer when used in this context. A monoclonal antibody that has been investigated clinically for immunotherapy and immunodetection of ovarian carcinomas, namely CC49, was used to construct a bispecific conjugate with the Fab fragment of a neutralizing anti-knob mAb to target Ad binding via TAG-72. This conjugate facilitated TAG-72-specific, CAR-independent Ad reporter gene transfer to both ovarian cancer cell lines and primary ovarian cancer cells cultured from malignant ascites fluid. Fab-CC49 was very selective for tumor cells, augmenting Ad gene transfer to primary ovarian cancer cells 2- to 28-fold relative to untargeted Ad, while also decreasing gene transfer to autologous cultured mesothelial cells 4- to 9-fold. These data suggest that targeting Ad via TAG-72 may improve the selectivity of Ad gene transfer for ovarian tumors 8- to 252-fold on i.p. vector injection. These results also define the requirements for a candidate target receptor in the rational design of a targeted Ad vector for ultimate clinical utility, one that selectively infects tumor cells and spares normal cells on i.p. injection. Such a vector may increase gene transfer and decrease the toxicity of Ad vectors, which would improve the therapeutic index of cytotoxic gene therapy for ovarian cancer in clinical trials.     

NRP-1mAb对胃癌细胞BGC 823增殖的影响

目的 观察自主研发的抗NRP-1 b1／b2 IgG单克隆抗体（NRP 1mAb）对胃癌BGC 823细胞生长的影响,并初步探讨可能的作用机制。方法 实验室制备NRP-1mAb,采用SDS-PAGE检测纯度。采用0、25、100、200、400 μg／ml NRP-1 mAb培养胃癌BGC-823细胞,光学显微镜下观察细胞形态学变化;采用MTT法、集落形成实验、流式细胞术观察胃癌细胞BGC-823的增殖、集落形成和凋亡的情况;Western blotting法检测NRP 1mAb作用后Akt、p38、ERK、JNK信号蛋白磷酸化情况。结果 SDS-PAGE检测显示,NRP-1mAb的纯度在95％以上。光学显微镜观察显示,NRP-1mAb作用后,BGC-823细胞形态呈凋亡改变。MTT实验显示,NRP-1mAb抑制BGC-823细胞的增殖作用呈浓度和时间依赖性（P＜0.01）。集落形成实验显示,不同浓度NRP-1mAb均能显著抑制BGC-823细胞的集落形成,其抑制率呈浓度依赖性（P＜0.01）。流式细胞术检测显示,不同浓度NRP-1mAb均明显促进BGC-823细胞凋亡,且大部分集中在早期凋亡。Western blotting检测显示,BGC-823细胞的Akt磷酸化受到抑制, ERK、p38、JNK的磷酸化水平无明显变化。结论NRP-1mAb能抑制胃癌细胞BGC-823的生长、促进凋亡,可能与抑制Akt磷酸化有关。     

Efficient inhibition of intra-peritoneal tumor growth and dissemination of human ovarian carcinoma cells in nude mice by anti-L1-cell adhesion molecule monoclonal antibody treatment

The L1 cell adhesion molecule is implicated in the control of proliferation, migration, and invasion of several tumor cell types in vitro. Recently, L1 overexpression was found to correlate with tumor progression of ovarian carcinoma, one of the most common causes of cancer-related deaths in gynecologic malignant diseases. To evaluate L1 as a potential target for ovarian cancer therapy, we investigated the effects of anti-L1 monoclonal antibodies (chCE7 and L1-11A) on proliferation and migration of L1-positive human SKOV3ip ovarian carcinoma cells in vitro and the therapeutic efficacy of L1-11A against i.p. SKOV3ip tumor growth in nude mice. In vitro, both anti-L1 antibodies efficiently inhibited the proliferation of SKOV3ip cells as well as other L1-expressing tumor cell lines (renal carcinoma, neuroblastoma, and colon carcinoma). On two cell lines, hyper-cross-linking of L1-11A with a secondary antibody was necessary for significant inhibition of proliferation, indicating that cross-linking of L1 is required for the antiproliferative effect. L1-negative prostate carcinoma cells were not influenced by antibody treatment. Biweekly treatment of ovarian carcinoma-bearing mice with L1-11A led to a dose-dependent and significant reduction of tumor burden (up to -63.5%) and ascites formation (up to -75%). This effect was associated with reduced proliferation within the tumors. L1-directed antibody-based inhibition of peritoneal growth and dissemination of human ovarian carcinoma cells represents important proof-of-principle for the development of a new therapy against one of the leading gynecologic malignant diseases.     

D2-40在转移性癌及间皮细胞浆膜腔积液中的表达

背景与目的：浆膜腔积液中癌细胞与反应性间皮细胞有时从细胞形态上难以鉴别。本文旨在观察D2-40在浆膜腔积液间皮细胞及转移性癌细胞中的表达,评价其用于鉴别诊断的价值。方法：用细胞块技术对99例浆膜腔积液标本进行免疫组化检测,观察D2-40的表达情况。99例标本中包括肺癌62例,乳腺癌4例,胃癌7例,卵巢癌9例,恶性间皮瘤1例,间皮反应性增生4例以及其他来源的转移性癌12例。反应性间皮细胞也存在于恶性浆膜腔积液中（88/95）,同时作为自身对照进行分析。结果：D2-40标记间皮细胞的敏感度为46.2%,特异度为89.4%。转移性癌标本中约33%的卵巢癌,4%的肺癌,14%的胃癌及20%的其他转移性癌呈D2-40阳性表达。结论：D2-40标记间皮细胞的特异度高,敏感度较低,可试用于原发灶不是卵巢癌的浆膜腔积液癌细胞与间皮细胞的辅助鉴别,其应用的可行性有待更大样本的观察。     

Mesothelial cells induce the motility of human ovarian carcinoma cells

The dissemination of ovarian carcinoma cells within the abdominal cavity involves interaction of tumor cells with the peritoneal mesothelium. The aim of our study was to investigate whether mesothelial cells might directly affect the spreading of this tumor by inducing motility and invasiveness of human ovarian carcinoma cells. Serum‐free supernatants of cultured human mesothelial cells [conditioned medium (CM)] induced chemotaxis and invasiveness of the human ovarian carcinoma cell lines SK‐OV‐3, OVCAR‐5 and A2780 in a Boyden chamber. Checkerboard analysis indicated that the stimulated motility was prevalently directional. Most of the chemotactic activity was retained by a heparin affinity column, indicating that the motility factor(s) is a heparin‐binding protein. Using different monoclonal antibodies (MAbs) directed against chemotactic factors that are secreted by mesothelial cells, we found that chemotaxis was partially prevented (64.8% inhibition) by antibodies against fibronectin (FN). CM also induced haptotactic migration of ovarian carcinoma cells, and anti‐FN antibodies significantly inhibited haptotaxis. The presence of FN in the CM was confirmed by Western blot analysis. Our findings suggest that mesothelium plays an active role in inducing the intraperitoneal spread of ovarian carcinoma cells, and point to FN as being one of the main mediators of mesothelium‐induced ovarian carcinoma cell motility. Int. J. Cancer 80:303–307, 1999. © 1999 Wiley‐Liss, Inc.