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.     

Relationship between metastatic ability and H-ras oncogene expression in rat mammary cancer cells transfected with the v-H-ras oncogene

To study the relationship between metastatic ability and activated ras expression, a cloned, low metastatic, dimethylbenz(a)anthracene-induced rat mammary cancer cell line (RMC1) was transfected with the v-H-ras oncogene. Cloned transfectants were characterized as high, medium, or low expressors of the v-H-ras gene, on the basis of Southern, Northern, and Western blot analysis. Following s.c. inoculation in syngeneic rats, all transfectants produced tumors; however, the in vivo growth rate of cloned transfectants which expressed any level of v-H-ras oncogene was significantly higher (approximately 5-fold) than that observed in the untransfected RMC1 cells. Control (neo only) transfectants exhibited no change in growth rate and had a low metastatic ability comparable to that of the parental untransfected cells. Certain cloned v-H-ras expressing transfectants were highly metastatic to the lungs and lymph nodes. These highly metastatic H-ras transfectants differed widely however, in their level of H-ras expression. The lung colonization potential following i.v. inoculation was increased in all transfectants which expressed any level of v-H-ras gene. These studies suggest that while v-H-ras transfection can result in the development of metastatic ability in rat mammary cancer cells, there is no simple dose-response relationship between the level of v-H-ras expression in cloned rat mammary cancer cell transfectants and the development of experimental or spontaneous metastases.     

Reduced sialidase expression in highly metastatic variants of mouse colon adenocarcinoma 26 and retardation of their metastatic ability by sialidase overexpression.

Sialidase expression levels are inversely correlated with the metastatic potential of mouse colon adenocarcinoma 26 sublines, as assessed by activity assays and RT-PCR, irrespective of total and cell surface sialic acid contents. Compared with low metastatic NL4 and NL44 cell lines, the highly metastatic NL17 and NL22 cells exhibit low expression of sialidases, accompanied with higher levels of sialylLe(x) and GM3. To investigate whether these properties of NL17 cells can be altered by sialidase overexpression, we transfected a cytosolic sialidase gene into NL17 cells. The result was markedly inhibited lung metastasis, invasion and cell motility with a concomitant decrease in sialylLe(x) and GM3 levels, in line with the case of spontaneously low metastatic sublines having relatively high endogenous sialidase levels, implying that sialidase level is a determining factor affecting metastatic ability. Treatment of the cells with antibodies against sialylLe(x) and GM3 affected cell adhesion and/or cell motility, providing evidence that desialylation of these molecules, as targets of sialidase, is involved in the suppression of metastasis.     

Regulation of breast cancer cell motility by insulin receptor substrate-2 (IRS-2) in metastatic variants of human breast cancer cell lines.

Insulin-like growth factors (IGFs) regulate breast cancer cell proliferation, protect cells from apoptosis, and enhance metastasis. In this study, we examined the IGF signaling pathway in two breast cancer cell lines selected for metastatic behavior. LCC6 was selected for growth as an ascites tumor in athymic mice from parental MDA-MB-435 cells (435P). The MDA-231BO cell line was derived from osseous metastases that formed after intracardiac injection of the MDA-MB-231 cell line in athymic mice. Compared to the parental cell lines, IGF-I treatment enhanced IRS-2 phosphorylation over IRS-1 in the metastatic variants. IGF-I stimulated cell migration in the variant cells, but not in the parental cells. To determine the role for IRS-2 in IGF-mediated motility, we transfected MDA-231BO cells with an anti-sense IRS-2 construct. Transfected cells had decreased levels of IRS-2 with diminished IGF-mediated motility and anchorage independent growth when compared to control cells. However, adherence to fibronectin was enhanced in the transfected cells compared to MDA-231BO cells. Our data show that breast cancer cells selected for metastatic behavior in vivo have increased IRS-2 activation and signaling. In these cells, IGF-I enhances cell adhesion and motility suggesting that IRS-2 may mediate these aspects of the malignant phenotype.     

CD9 overexpression suppressed the liver metastasis and malignant ascites via inhibition of proliferation and motility of small-cell lung cancer cells in NK cell-depleted SCID mice

CD9, a transmembrane protein known as motility-related protein-1, plays a pivotal role in regulating cell adhesion, motility, and proliferation, and has been regarded as an important metastasis-inhibitory factor of various human cancers. However, little information has been obtained regarding the highly metastatic human small-cell lung cancer (SCLC). In the present study, an SCLC cell line (OS3-R5), lacking CD9 expression, was transfected with human CD9 gene to assess the role of CD9 on the metastatic potential of SCLC. CD9 gene transfection into OS3-R5 cells resulted in cell proliferation and motility in vitro. Parental and mock-transfected OS3-R5 cells developed liver metastasis and malignant ascites when they were intravenously inoculated into NK cell-depleted SCID mice. CD9 gene transfection into OS3-R5 cells caused suppression of the liver metastasis and malignant ascites. Immunohistochemical analysis revealed that the number of proliferating tumor cells was significantly fewer in liver lesions produced by CD9 gene-transfected OS3-R5 cells than those produced by parental or mock control OS3-R5 cells. In addition, no detectable levels of CD9 were expressed in metastatic tumor cells in mice bearing CD9 gene-transfected OS3-R5 cells, as well as those in mice bearing parental or mock control OS3-R5 cells. These results suggest that the restored expression of CD9 in SCLC cells may reduce the metastatic spread of SCLC cells via the inhibition of cell proliferation and motility.     

MTA1基因表达与人骨肉瘤细胞浸润和转移的关系

背景与目的:骨肉瘤具有很高的转移特性,以肺转移多见。尽管能成功控制原发瘤,但5年内仍然有超过30%的患者死于肺转移。肿瘤转移相关基因(MTA1)是新近发现的一个肿瘤转移候选基因,其表达增高与乳腺癌及胃癌、结直肠癌的侵袭转移能力成正相关。MTA1在骨肉瘤中的表达国内外尚未见相关研究报道,通过比较MTA1基因在人骨肉瘤细胞高低转移株的表达水平,探讨MTA1表达与骨肉瘤细胞浸润和转移潜能的相关性。方法:采用半定量逆转录聚合酶链反应(RT-PCR)检测MG-63骨肉瘤细胞高低转移株MTA1的表达情况,用Boyden小室体外侵袭实验检测两株MG-63细胞的体外侵袭力;用脂质体介导的MTA1基因转染MG-63低转移株细胞,通过RT-PCR检测MTA1的表达;Boyden小室体外侵袭实验检测转染前后细胞侵袭力的变化。结果:RT-PCR结果显示MTA1在MG-63低转移细胞株中表达水平低(1.32),在高转移细胞株中表达水平高(6.27)(P<0.05);Boyden小室体外侵袭实验显示MG-63高转移株细胞体外侵袭力强,其穿膜细胞相对百分率为(46.3±2.4)%,低转移株细胞体外侵袭力较弱,其穿膜细胞相对百分率(12.6±1.1)%,两者差异有显著性(P<0.05);转染MTA1基因后,低转移细胞株转移潜能较未转染细胞明显增高。结论:MTA1与人骨肉瘤细胞转移潜能有密切关系,MTA1对肿瘤转移的作用机制以及作为干预肿瘤转移靶基因的可能性值得进一步探讨。     

Altered expression of NM23, a gene associated with low tumor metastatic potential, during adenovirus 2 Ela inhibition of experimental metastasis

NM23, a novel gene associated with low tumor metastatic potential, has been investigated in an experimental system in which metastasis is inhibited by the transfection of viral and cellular oncogenes. The experimental system utilizes transfection of the Adenovirus 2 Ela gene to inhibit metastasis: rat embryo fibroblasts (REF) transfected with c-Ha-ras were highly metastatic, while REF cotransfected with ras and Ela were virtually nonmetastatic. NM23 RNA levels were higher in three independently ras + Ela-cotransfected, low metastatic REF lines than in three independently ras-transfected, highly metastatic REF line. Differences in hybridizable NM23 RNA levels between the two groups of transfected cell lines ranged from 2- to 8-fold. In situ hybridization demonstrated that the relatively high NM23 RNA levels in low metastatic ras + Ela-cotransfected REF cells were not due to overexpression of the NM23 gene by a subpopulation of cells. Thus, the metastasis-inhibitory effect of the exogenously added Ela gene has been associated with increased activation of the cellular NM23 gene. This associated is particularly significant in light of the very few changes observed in translatable steady-state RNA levels between ras- and ras + Ela-transfected REF lines. The data identify NM23 as a candidate for a gene that suppresses the malignant state.     

An in vitro model of neoplastic progression in murine epithelial cells

We have developed an epithelial cell line derived from mouse liver which represents a spectrum of malignant progression. When inoculated into mice at low passage, the cells induced benign cysts; after extensive subcultures, the same line induced low grade adenocarcinomas. A variant of these cells with increased invasive and metastatic potential was selected. In culture, growth in methocel correlated with acquisition of malignant potential while increased homotypic aggregation correlated with metastatic ability. These cultures should be extremely valuable for studies on the nature of epithelial cell malignancy, the most common form of human cancer.     

Heregulin regulates the actin cytoskeleton and promotes invasive properties in breast cancer cell lines

The metastatic process requires changes in tumor cell adhesion properties, cell motility and remodeling of the extracellular matrix. The erbB2 proto-oncogene is overexpressed in approximately 30% of breast cancers and is a major prognostic parameter when present in invasive disease. A ligand for the erbB2 receptor has not yet been identified but it can be activated by heterodimerization with heregulin (HRG)-stimulated erbB3 and erbB4 receptors. The HRGs are a family of polypeptide growth factors that have been shown to play a role in embryogenesis, tumor formation, growth and differentiation of breast cancer cells. The erbB3 and erbB4 receptors are involved in transregulation of erbB2 signaling. The work presented here suggests biological roles for HRG including regulation of the actin cytoskeleton and induction of motility and invasion in breast cancer cells. HRG-expressing breast cancer cell lines are characterized by low erbB receptor levels and a high invasive and metastatic index, while those which overexpress erbB2 demonstrate minimal invasive potential in vitro and are non-tumorigenic in vivo. Treatment of the highly tumorigenic and metastatic HRG-expressing breast cancer cell line MDA-MB-231 with an HRG-neutralizing antibody significantly inhibited proliferation in culture and motility in the Boyden chamber assay. Addition of exogenous HRG to non-invasive erbB2 overexpressing cells (SKBr-3) at low concentrations induced formation of pseudopodia, enhanced phagocytic activity and increased chemomigration and invasion in the Boyden chamber assay. The specificity of the chemomigration response to HRG is demonstrated by inhibition with the anti-HRG neutralizing antibody. These results suggest that either HRG can act as an autocrine or paracrine ligand to promote the invasive behavior of breast cancer cells in vitro or thus may enhance the metastatic process in vivo.     

Silencing of connexin 43 suppresses invasion, migration and lung metastasis of rat hepatocellular carcinoma cells

To reduce cancer mortality, understanding of mechanisms of cancer metastasis is crucial. We have established six rat hepatocellular carcinoma (HCC) cell lines, which exhibit differing metastatic potential to the lung after inoculation into the tail veins of nude mice. In the present experiment, we investigated the process of cell attachment to metastatic sites and possible regulating factors. One hour after inoculation, two of two HCC cell lines with high metastatic potential and one of two HCC cell lines with low metastatic potential exhibited many attached cells in the lung. One day after inoculation, lung metastatic foci were observed only with highly-metastatic cells with elevated connexin 43 (Cx43) expression as assessed by cDNA array analysis. Furthermore, 24 or 48 h after transfection of an siRNA targeting Cx43, in vitro invasion and migration were suppressed by 68% (P < 0.001) and 36% (P < 0.05) compared with control-siRNA transfected cells, despite no differences in cellular morphology, cell proliferation or apoptotic activity. Moreover, the number of metastatic nodules per lung area in nude mice was significantly (P < 0.01) reduced. In conclusion, suppression of Cx43 expression in tumor cells reduced in vitro migration and invasion capacity and in vivo metastatic ability so that Cx43 has potential as a molecular target for prevention of cancer metastasis with Cx43 overexpressing tumors.     

Suppression of intracellular Cu-Zn SOD results in enhanced motility and metastasis of Meth A sarcoma cells

We have previously described an inverse relationship between Cu-Zn superoxide dismutase (SOD) activity and invasiveness of a clone of human tongue cancer cells. In these cells, suppression of Cu-Zn SOD activity by transfection with anti-sense cDNA enhanced motility in vitro. The present studies were undertaken to determine whether the inverse relationship between intracellular Cu-Zn SOD activity and motility is a general property of other tumor cells and whether this enzyme indeed defines in vivo metastatic potential. Murine Meth A sarcoma-derived ML-01 cells, which have low metastatic activity, were transfected with anti-sense Cu-Zn SOD cDNA. Two clones with very different SOD activities—ML-AS2, with the most suppressed, and ML-AS5, with the least suppressed activity—were analyzed for their motility and metastatic capability. Compared to the mock-transfectant ML-neo, the metastatic potential and motility of the ML-AS2 and ML-AS5 were increased 4.5- and 2.1-fold, respectively. Superoxide treatment enhanced the motility of the AS clones but not that of the ML-neo cells. Our results clearly show that there is an inverse relationship between the intracellular level of Cu-Zn SOD, cell motility and in vivo metastatic potential. Int. J. Cancer 73:187–192, 1997. © 1997 Wiley-Liss, Inc.     

SH2-B与结肠癌细胞运动和迁移相关性的研究

目的:分析SH2-B对结肠癌细胞侵袭迁移的影响,探讨结肠癌转移的分子机制。方法:免疫荧光筛选SH2-B低表达结肠癌细胞,用Lipofectamine 2000TM将pcDNA3.1-SH2-B质粒转染至HT-29细胞,细胞划痕实验分析SH2-B对结肠癌细胞HT-29爬行迁移运动的影响,用Boden Chamber分析SH2-B对结肠癌细胞HT-29侵袭运动的影响。结果:HT-29为SH2-B低表达结肠癌系,基因转染后HT-29细胞表达SH2-B显著增高;细胞划痕研究结果表明,SH2-B转染组、空载体转染组和未转染母细胞组迁移细胞数倒置显微镜10个视野分别为867±187、349±121和279±158,SH2-B转染组爬行细胞数显著高于空载体组和未转染细胞组,P均<0.05;Trans-well研究结果显示,转染SH2-B组、空载体转染组和未转染细胞组穿过滤膜细胞数分别为278±107、129±88和112±81,转染SH2-B组透过细胞数显著高于未转染组和空载体转染组,P<0.05。结论:SH2-B可能通过增强结肠癌细胞运动和迁移能力参与结肠癌细胞的侵袭和转移。     

Transforming activity of DNA extracted from BKV-transformed hamster cells after passages in culture

Primary fetal rat fibroblasts (FRF cells) were transfected with DNA extracted from BKV-transformed hamster kidney cells at low passage after transformation (HKBKlp cells) and at high passage after transformation (HKBKhp cells). Two transformed rat cell lines were obtained, FRF-DNA-HKBKlp cells and FRF-DNA-HKBKhp cells, transformed by DNA extracted from HKBKlp cells and HKBKhp cells, respectively. They were characterized by a number of biological properties and by tumorigenicity and metastatic ability in newborn hamsters. The two transformed FRF cell lines exhibited exactly inverted properties in comparison with HKBK cells, in particular FRF-DNA-HKBKlp cells showed a low level of nuclear T antigen and a diffuse appearance of TSTA at the cell surface, whereas FRF-DNA-HKBKhp cells demonstrated a high level of T antigen and the capping of TSTA in the cell membrane. The tumorigencity and the metastatic ability were greater with FRF-DNA-HKBKlp cells, while FRF-DNA-HKBKhp cells appeared to be less tumorigenic and metastatic in newborn hamsters.     

氯离子通道1过表达对小鼠肝癌细胞株Hca-P生物学行为的影响

背景与目的:氯离子通道l(chloride intracellular channel l,CLICl)是CLIC家族中的一员,研究表明CLIC1与肿瘤转移相关。本研究旨在探讨CLICl过表达在体外对小鼠肝癌低淋巴道转移细胞株Hca-P生长、体外迁移和侵袭能力的影响。方法:构建CLIC1过表达真核载体pcDNA3.1(+)-CLIC1表达质粒,将重组的pcDNA3.1(+)-CLIC1基因和空载体pcDNA3.1(+)转染Hca-P母系细胞,通过G418筛选获得稳定表达CLIC1基因的pcDNA3.1(+)-CLIC1-Hca-P细胞株和转染空载体的pcDNA3.1(+)-Hca-P细胞株,RT-PCR和ELISA鉴定CLIC1过表达水平,CCK-8法检测细胞活力和分裂增殖能力,Transwell实验检测细胞的体外迁移能力和侵袭能力。结果:成功建立了稳定表达CLIC1基因的细胞株pcDNA3.1(+)-CLIC1-Hca-P,与空载体对照组相比,pcDNA3.1(+)-CLIC1质粒转染入Hca-P细胞后CLIC1基因表达水平显著升高。pcDNA3.1(+)-CLIC1-Hca-P细胞增殖明显高于Hca-P母系细胞组和空载体对照组,差异有统计学意义(P<0.05),且细胞增殖主要集中在72～96 h;Transwell检测各组肿瘤细胞迁移能力结果显示,pcDNA3.1(+)-CLIC1-Hca-P、pcDNA3.1(+)-Hca-P和Hca-P细胞株迁移到膜下和小室下室的平均细胞数分别为205.43±22.87、132.72±20.45和121.35±19.64。pcDNA3.1(+)-CLIC1-Hca-P与Hca-P、pcDNA3.1(+)-Hca-P细胞株比较差异有统计学意义(P<0.05);Transwell检测各组肿瘤细胞侵袭能力结果显示,pcDNA3.1(+)-CLIC1-Hca-P细胞穿过基膜的细胞数为(76.2±4.62)个,明显多于pcDNA3.1(+)-Hca-P的穿膜细胞数(48.34±3.45)个和Hca-P细胞的穿膜细胞数(49.8±5.51)个,差异有统计学意义(P<0.05)。结论:CLIC1过表达可以显著促进Hca-P细胞增殖、增强其侵袭能力。CLIC1有望成为临床治疗肝癌的基因治疗靶点之一。     

Metastatic potential prediction by a visual grading system of cell motility: prospective validation in the Dunning R-3327 prostatic adenocarcinoma model

A method for accurate prediction of prognosis in individual patients with prostatic carcinoma does not exist. The limitations of pathological grading systems may result from the failure of standard pathological examination of fixed dead tissue to accurately assess the biological and metastatic behavior of live tumor cells. Many of the sublines of the Dunning R-3327 rat prostatic adenocarcinoma are histologically similar yet differ in metastatic potential. Cells from the Dunning model were grown in culture and filmed by time-lapse videomicroscopy. These cells exhibited characteristic membrane ruffling, pseudopodal extension, and cellular translation that could be graded with 80% reproducibility. Individual cells from sublines with high metastatic potential were separated from cells from sublines of low metastatic potential in 96% of cases. We have applied our cell motility grading system to prospectively classify the metastatic potential of neoplastic cells. The mean motility grades of sublines of high and low metastatic potential differed significantly (Mann-Whitney-Wilcoxon, P less than 0.0005). Among seven sublines in which the grading system was developed, individual cells were correctly classified as high or low metastatic in 71% of cases by ruffling or pseudopodal extension, 73% of cases by translation, and 75% of cases by motility index, an average of the three parameters of motility. Among four newly tested sublines, cells from a low metastatic and high metastatic sublines were perfectly classified. Cells from two other low metastatic sublines were misclassified. When all 88 cells from the 11 sublines were classified, high metastatic cells were detected with 94% sensitivity and 50% specificity. The predictive value of a determination of low metastatic was 93%, whereas the predictive value of an assignment of high metastatic was 52%. The ability to detect and accurately classify most highly metastatic cells while rarely erring in a classification of low metastatic potential suggests that a grading system of cancer cell motility should be evaluated in human prostatic carcinoma. The motility of live prostatic carcinoma cells may predict patient prognosis better than standard pathological grading systems.     

ＲｈｏＡ小干扰ＲＮＡ抑制乳腺癌细胞株ＭＣＦ-７及其裸鼠皮下移植瘤的实验研究

目的　观察ＲｈｏＡ小干扰ＲＮＡ（ｓｉＲｈｏＡ）对乳腺癌细胞株ＭＣＦ-７增殖、迁移、周期和凋亡的影响以及对裸鼠移植瘤生长的影响。方法　ｓｉＲｈｏＡＬｉｐｏｆｅｃｔａｍｉｎｅ２０００介导下转染乳腺癌细胞ＭＣＦ-７,转染４８ｈ后,采用Ｗｅｓｔｅｒｎｂｌｏｔ技术检测ＲｈｏＡ蛋白的表达,ＭＴＴ实验检测ｓｉＲｈｏＡ转染细胞的增殖变化,损伤刮擦实验检测ｓｉＲｈｏＡ转染细胞的迁移能力,流式细胞仪检测ｓｉＲｈｏＡ转染细胞的周期和凋亡,裸鼠移植瘤实验检测ｓｉＲｈｏＡ对肿瘤生长的影响。结果　成功转染ｓｉＲｈｏＡ的肿瘤细胞,Ｗｅｓｔｅｒｎｂｌｏｔ显示ＲｈｏＡ蛋白表达在ＭＣＦ-７细胞中明显下降;ｓｉＲｈｏＡ对ＭＣＦ-７细胞的增殖、迁移均有显著的抑制作用并能促进肿瘤细胞凋亡及细胞周期中Ｓ期细胞减少,Ｇ１／Ｇ０期细胞增加;裸鼠移植瘤内重复注射ｓｉＲｈｏＡ后肿瘤生长明显减缓。结论　ｓｉＲｈｏＡ能够明显抑制ＲｈｏＡ基因在乳腺癌细胞ＭＣＦ-７中的表达,部分逆转ＭＣＦ-７的恶性生物学行为并抑制裸鼠移植瘤的生长。     

A BALB/c 3T3-transformed cell line suitable for transfection assay of metastasis-inducing genes

A clonal cell line, 1-1ras1000, transformed by the activated c-Ha-ras oncogene, does not form metastases after i.v. injection into mice (experimental metastasis assay). Here, we show that this cell line is useful as a recipient to detect metastasis-inducing genes, using a transfection assay. Cells (1-1ras1000) were susceptible to metastasis induction by transfection with either v-src or genomic DNA from a v-src- and v-fos-transferred highly metastatic rat cell line (SR202). The susceptibility of 1-1ras1000 cells for lung metastasis induction was suitable for a genomic transfection assay to detect a metastasis-inducing gene in the transfected cells which had incorporated genomic DNA from donor metastatic tumor cells. When DNAs extracted from 7 human tumors were tested for metastasis induction, 2 DNAs from nonmalignant tumor (non-tumorigenic tumors in athymic nude mice) (2/2) were negative and 4 DNAs from malignant tumors (4/5) were positive in 1-1ras1000 cells for primary transfection. In one of the resulting metastases, the ability to metastasize was also transferred in the second and third cycles of genomic DNA transfection at high frequencies. All of the resulting metastases carried the human repetitive A/u sequence. Neither re-arrangements of the endogenous c-Haras nor changes of protein amounts were detected. Recipient 1-1ras1000 cells had a negligible rate of spontaneously metastatic conversion during in vitro cultivation and transfection processes. The resulting metastasized cells were easily isolated from the lung after culturing in selection medium containing G418 (geneticin). Isolated cells stably retained the ability to form metastatic lung nodules when re-injected into mice. Thus, 1-1ras1000 cells appear to be a useful system for the isolation of metastasis-inducing genes from human metastatic tumors. Int. J. Cancer, 71:88–93, 1997. © 1997 Wiley-Liss, Inc.     

Generation of metastatic variants by transfection of a rat non-metastatic epithelial cell line with genomic DNA from rat prostatic carcinoma cells.

Prostate cancer is the second leading cause of male death from malignant disease in Europe and in the USA. Failure to prevent or eliminate metastatic dissemination is a fundamental problem underlying the current inadequate treatment of prostate cancer, and novel therapeutic strategies are required if this disease is to be successfully managed. No independent markers are yet available to predict the behaviour of any individual prostate cancer, particularly its potential to metastasize, and there is now an urgent prerequisite to identify and characterize genes specifically involved in determining the metastatic phenotype of prostate cancer cells before any biologically appropriate treatment modality can be devised. To identify DNA sequences that trophically promote the metastatic phenotype, we have established a new transfection assay with which to monitor activity of prostate cancer genomic DNA. Rat prostatic G and AT6.1 cell lines derived from the same original Dunning R3327 rat prostatic carcinoma exhibit, respectively, low- and high-metastatic phenotypes when grown in syngeneic Copenhagen rats. Rat mammary epithelial cell line ''Rama 37'' derived originally from Wistar-Furth rats yields benign non-metastasizing adenomas when inoculated subcutaneously into syngeneic animals. In this report, the Rama 37 cell line is successfully used as the recipient cell-line for transfected DNA fragments extracted from rat prostatic carcinoma G and AT6.1 cells. New metastatic variants of Rama 37 cells have been generated. Enzymatically fragmented genomic DNA from rat metastatic prostate carcinoma cell lines was co-transfected together with plasmid pSV2neo into parental Rama 37 cells, followed by culture in the presence of Geneticin-G418 to select for the transfected cells. To enable subsequent identification of metastasis-promoting DNA sequences, the fragmented genomic DNA sequences were covalently attached to specifically engineered linker DNA molecules to flank the genomic DNA before transfection. Thereafter, the resulting transfectants were pooled and inoculated into mammary fat pads of female Wistar-Furth rats. Metastases produced by the transfectant cells in vivo were reestablished from secondary tumours and probed for the presence of the specific synthetic oligonucleotide sequences that flanked, and hence identified, the presence of the transfected DNA. These new metastatic cells are shown to provide a sensitive assay system with which to detect DNA sequences responsible for conveying the metastatic phenotype of prostate cancer when inoculated into syngeneic rats.     

MRP-1/CD9与高转移人乳腺癌MDA-MB-231细胞恶性行为相关性的体外研究

目的:观察MRP-1/CD9对高转移人乳腺癌细胞系MDA-MB-231体外增殖和侵袭的抑制效应,并初步探讨其作用机制。方法:应用MRP-1/CD9特异性扩增引物,借助RT-PCR获得MRP-1/CD9全长cDNA片段,正向插入pcDNA3.1表达载体中,并将重组质粒导入MDA-MB-231细胞中,G418稳定筛选;应用CFSE-流式细胞仪检测,单层伤口愈合实验,软琼脂克隆形成实验等方法观察了MDA-MB-231细胞转染前后,细胞体外增殖及侵袭能力等指标的变化。Western blot检测AKT、p-AKT和SRC在转染前后的细胞中的表达变化。结果:成功构建全长MRP-1/CD9真核表达载体,将其转染入MDA-MB-231细胞后获得稳定表达MRP-1/CD9的MDA-MB-231克隆株(MDA-MB-231/CD9)。与空质粒转染后的MDA-MB-231细胞相比,MDA-MB-231/CD9细胞运动能力明显减弱,侵袭能力降低;p-AKT和SRC在MDA-MB-231/CD9细胞中表达明显降低。结论:MRP-1/CD9对细胞的运动和侵袭有抑制作用,这种作用与p-AKT和SRC的下调引起E-cadherin介导的粘附增强有关。