Insulin-like growth factor I: Action and receptor characterization in human prostate cancer cell lines

The role of insulin-like growth factor I (IGF-I) in the growth and development of prostate cancer was studied using established human prostate cancer cell lines. Under steroid and growth factor-free culture conditions, IGF-I significantly stimulated the androgen-independent cell lines PC-3 and DU-145 to incorporate [³H]thymidine into DNA, while the androgen-dependent cell line, LNCaP, was not affected. However, in the presence of dihydrotestosterone (DHT), DNA synthesis of LNCaP cells was stimulated by IGF-1 in a dose-dependent manner. None of the cell lines tested secreted an immunoreactive level of IGF-I into their conditioned medium. Characterization of receptors by ligand binding assays revealed that all prostate cancer cell lines tested express specific binding sites for IGF-I with similar dissociation constants (0.23–0.39 nM). Crosslinking studies supported the suggestion that ¹²⁵1-IGF-I was bound to a receptor on these cells. The IGF-I receptor concentrations of androgen-independent cell lines were significantly higher than those of the androgen-dependent cell line. Androgen appeared to affect neither the expression of IGF-1 receptors nor the secretion of IGF-I. The results suggest that IGF-I may play an important role in stimulating the growth and progression of prostate cancer. © 1993 Wiley-Liss, Inc.     

LIN28A和LAMP1在膀胱癌细胞系中的表达及意义

目的:探讨LIN28A和LAMP1在膀胱癌细胞系中表达情况,以及两者之间的关系,推测其可能临床意义及对肿瘤进展的影响。方法:采用RT-PCR检测膀胱癌细胞系LIN28A、LIN28B和LAMP1表达,免疫荧光检测LIN28A和LAMP1二者蛋白表达定位;LIN28A敲减后通过qRT-PCR检测LAMP1的mRNA表达变化。结果:5个癌细胞系T24、UM-UC3、J82、5637和SW780和正常移行上皮细胞系SV-HUC-1均表达LIN28A,其中J82也表达LIN28B;5个癌细胞系均表达LAMP1,SV-HUC-1不表达LAMP1;LIN28A和LAMP1蛋白均定位在胞浆;LIN28A敲减后对LAMP1的mRNA表达变化无明显影响,相应蛋白变化需要进一步验证。结论:4个膀胱癌细胞系T24、5637、UM-UC3和SW780可以用于LIN28A与肿瘤相关的机制研究,而J82可用于LIN28B的机制研究。LIN28A对肿瘤细胞和干细胞的调控方面可能具有相似性,敲减后对其靶点mRNA表达量无明显影响,LAMP1蛋白可能对肿瘤细胞侵袭转移具有抑制作用。     

Developmentally Imprinted Genes as Markers for Bladder Tumor Progression

Purpose

Developmentally imprinted genes, such as H19 and insulin-like growth factor-II (IGF-II), play an important role during human embryogenesis and also have been implicated in the pathogenesis of embryonal tumors of childhood. Since H19 is expressed in human fetal bladder, we evaluated 35 bladder carcinomas for H19 expression by in situ hybridization analysis and correlated expression with tumor grade. As a prelude to gene transfer studies to determine if H19 is a bladder tumor oncogene, we also evaluated bladder cell lines for expression of H19, IGF-II, IGF-I and the type I IGF receptor.

Materials and Methods

H19 expression was evaluated by in situ hybridization analysis in bladder tumor specimens. Northern analysis was used to evaluate the expression of H19, IGF-II, IGF-I and the type I IGF receptor in bladder cell lines.

Results

H19 was expressed preferentially in advanced stage tumors: 2 of 12 grade I tumors were H19 positive, whereas 9 of 11 grade II and 7 of 10 grade III tumors expressed H19 (p = 0.004). Additionally, 6 of 6 carcinoma in situ tumors were H19 positive, whereas normal bladder mucosa cells were H19 negative. We found that 3 of 11 cell lines (HT-1376, HT-1197 and 5637) express high levels of H19 mRNA, and each of these cell lines and J82 also express IGF-II. All cell lines examined expressed the type I IGF receptor, whereas there was no detectable IGF-I mRNA.

Conclusions

These data demonstrate that H19 is an oncodevelopmental marker of bladder tumor progression and raise the possibility that H19 may have oncogenic properties in bladder cancer.     

Characterization of high-affinity receptors for bombesin/gastrin releasing peptide on the human prostate cancer cell lines PC-3 and DU-145: Internalization of receptor bound 125I-(Tyr4) bombesin by tumor cells

Specific receptors for bombesin/gastrin releasing peptide (GRP) on the androgen-independent human prostate cancer cell lines PC-3 and DU-145 were characterized. No specific binding of ¹²⁵I-[Tyr⁴]-bombesin to the androgen-dependent human prostate cancer cell line LNCaP was detectable. The binding of ¹²⁵I-[Tyr⁴]-bombesin to PC-3 and DU-145 cells was found to be time- and temperature-dependent, saturable, and reversible. Scatchard analysis revealed a single class of binding sites with high affinity (K_d 9.8 × 10^?11 M for PC-3, and 9.1 × 10-¹¹ M for DU-145 cells at 25°C) and with a binding capacity of 44,000 binding sites/cell and 19,000 binding sites/cell, respectively. Bound ¹²⁵I-[Tyr⁴]-bombesin was rapidly internalized by PC-3 cells. The nonhydrolyzable GTP analog GTP-gamma-S caused a dose-dependent inhibition of ¹²⁵I-[Tyr⁴]-bombesin binding to PC-3 and DU-145 cells, indicating that a G-protein (guanine nucleotide-binding protein) couples the bombesin receptor to intracellular effector systems. Bombesin and GRP(14-27) inhibited the binding of ¹²⁵I-[Tyr⁴]-bombesin to both cell lines in a dose-dependent manner with inhibition constants (K_i of 0.5 nM and 0.4 nM, respectively. Both cell lines express the bombesin/GRP preferring bombesin receptor subtype, since, in displacement studies, neuromedin B was more than 200 times less potent than bombesin and GRP(14-27) in inhibiting the binding of ¹²⁵I-[Tyr⁴]-bombesin. Two synthetic bombesin/GRP antagonists, RC-3095 and RC-3110, powerfully inhibited the specific binding of ¹²⁵I-[Tyr⁴]-bombesin with K_i 0.92 nM and 0.26 nM on PC-3 cells, and 3.3 nM and 0.89 nM on DU-145 cells, respectively. These findings indicate that the PC-3 and DU-145 human prostate cancer cell lines possess specific high-affinity receptors for bombesin/GRP, and are suitable models for the evaluation of the antineoplastic activity of new bombesin/GRP antagonists in the treatment of androgen-independent prostate cancer. © 1994 Wiley-Liss, Inc.     

In vitro chemosensitivity of J-82 human bladder cancer cells

Summary While chemotherapy offers a valuable adjunct to surgery in the management of intravesical bladder cancer, an accurate in vitro predictive test for chemosensitivity has yet to be developed. Drug sensitivity of the human bladder cancer cell line J-82 was assessed using monolayer, stem cell and [³H]thymidine incorporation assays. The 72-h monolayer assay provided a rapid reflection of in vitro drug sensitivity and when combined with the labeling index the results generally paralleled those obtained with the soft agar stem cell assay without the associated large commitment of time and labor. It is suggested that 72-h monolayer assay alone or in combination with [³H]thymidine labeling index may offer valuable insight into the chemotherapeutic response of bladder tumors.Supported in part by a grant from the Commission on Academic Excellence and a Cancer Research Fellowship from the University of Louisville     

Permeation of hypericin in spheroids composed of different grade transitional cell carcinoma cell lines and normal human urothelial cells

PURPOSE: We investigated the importance of E-cadherin expression on the selective accumulation of hypericin in superficial bladder cancer after intravesical instillation. MATERIALS AND METHODS: Spheroids obtained from a panel of 3 transitional cell carcinoma cell lines, namely J-82, RT-4 (American Type Culture Collection, Manassas, Virginia) and RT-112 (German Collection of Micro-organisms and Cell Cultures, Braunschweig, Germany), and normal human urothelial (NHU) cells were incubated with hypericin. Accumulation was examined with fluorescence microscopy. Immunohistochemical staining was used to assess E-cadherin expression. RESULTS: Immunohistochemical staining showed E-cadherin expression in NHU (++), RT-112 (+) and RT-4 (+) spheroids, whereas E-cadherin expression was absent in J-82 spheroids. The highest intraspheroidal hypericin accumulation was observed in transitional cell carcinoma spheroids, whereas limited permeation was seen in NHU spheroids. Taken together the data point to an inverse relationship between E-cadherin expression and the permeation of hypericin throughout a 3-dimensional cellular matrix. CONCLUSIONS: Loss of E-cadherin expression correlates with loss of intercellular adhesion, tight junction formation and enhanced paracellular transport. The data show that E-cadherin hampers the permeation of hypericin in spheroids and the loss of intercellular adhesion, present in superficial bladder cancer lesions, can be associated with enhanced hypericin permeation. Therefore, E-cadherin expression seems to have a pivotal role in the selective uptake of hypericin after intravesical instillation in human bladders.     

Expression of survivin in bladder cancer cell lines using quantitative real-time polymerase chain reaction

ObjectivePrevious studies have reported that survivin expression is significantly associated with various malignancies including bladder cancer. However, the relationship between the expression of survivin and the tumor stage and grade of bladder cancer still require further study.MethodsTo determine whether survivin plays a role in the differentiation of bladder cancer cells, we conducted a preliminary study to examine the expression of survivin in bladder cancer cell lines.ResultsIn this study, we observed that the gene expression fold changes of survivin ranged from 3.2 to 16.7 in various tumor grades (G1–G4) of bladder cancer cell lines, which were higher than that in normal human urothelial cell line. With the worse differentiation of bladder cancer cell lines, the gene expression fold changes of survivin increased significantly (3.2-fold in RT4, 5.8-fold in 5637, 6.6-fold in T24, and 16.7-fold in HT1197). In addition, we observed different genotypes among various cell lines (C/C in HUC4449, C/G in RT4, C/G in 5637, G/G in T24, and C/C in HT1197). The relationship between survivin ?31 C/G polymorphism and various bladder cancer cell lines was non-significant. However, the overexpression of survivin may be associated with aggressive features of bladder cancer.ConclusionOur findings suggest that survivin could be a potential therapeutic target through the inhibition of cell proliferation in bladder cancer.     

E-cadherin和CAR在人膀胱癌细胞中的表达及其意义

目的检测上皮型钙黏素（E—cadherin）和柯萨奇-腺病毒受体（coxsackie and adenovirus receptor，CAR）在多种人膀胱癌细胞中的表达情况，初步讨论E-cadherin与CAR在人膀胱癌细胞中表达的意义及两者间的关联。方法用Western印迹法测定人膀胱癌细胞中E—cadherin和CAR的表达情况。结果E—cadherin，CAR在RT4、5637细胞中表达较高，在253J细胞中表达较低；E—cadherin在J82、T24细胞中不表达，CAR在J82细胞中微弱表达，在T24中不表达。结论E-cadherin和CAR在人膀胱癌细胞中的表达趋势一致，两者可能相互协作，共同参与膀胱癌的侵袭转移过程。     

光动力疗法对人膀胱癌细胞胞内游离钙的影响

目的:探讨光动力学作用后的膀胱癌细胞(T-24和SCaBER)胞内钙离子浓度的变化.方法:采用MTT比色分析法判断光动力学对体外人膀胱癌T-24和SCaBER细胞的杀伤效应.同时应用激光共聚焦显微镜和Fluo-3/AM探针技术测定光动力学作用后细胞内钙离子的浓度.结果:T-24和SCaBER细胞内钙离子有明显升高,与对照组比较差异有显著意义(P＜0.001).结论:光动力学作用后细胞内钙离子超载可能在细胞死亡中发挥重要作用.     

Epidermal growth factor receptor targeting of replication competent adenovirus enhances cytotoxicity in bladder cancer

PURPOSE: We evaluated the delivery and oncolytic potential of targeted replication competent adenoviruses in bladder cancer lines. MATERIALS AND METHODS: Seven established human bladder cancer tumor lines (5637, SW800, TCCsup, J82, Scaber, T24 and 253J) were studied for the expression of integrins alpha(v)beta3, alpha(v)beta5, Coxsackievirus and adenovirus receptor, epidermal growth factor receptor (EGF-R) and epithelial cell adhesion molecule antigens using flow cytometry analysis. Bispecific single chain Fv fragments were used to target replication deficient luciferase reporter adenovirus to EGF-R (425-s11) or to epithelial cell adhesion molecule (C28-s11) antigens. Moreover, a fiber modified adenovirus targeting alpha(v)-integrins was studied. Replication competent serotype-5 adenoviruses attenuated to replicate specifically in retinoblastoma pRb (Ad5-d24) or p53 deficient (Ad5-d55K) cells were tested in vitro for oncolytic properties. RESULTS: Low to absent Coxsackievirus and adenovirus receptor expression was found in 5 of the 7 tumor lines (SW800, J82, T24, 5637 and Scaber). EGF-R expression was found in all cell lines, whereas elevated epithelial cell adhesion molecule expression was seen in 3 (5637, Scaber and TCCsup), alpha(v)beta3-integrin was found in 1 (Scaber) and alpha(v)beta5-integrin was found in 3 (TCCsup, 253J and T24). EGF-R targeting using 425-s11 improved transgene expression in all cell lines from 2.1 to 12.5 times over nontargeted viruses. Epithelial cell adhesion molecule and integrin targeting was inferior to EGF-R targeting with a maximal increase in transgene expression of 2 times for epithelial cell adhesion molecule in 5637cells and 1.6 times for integrin targeting in T24 cells. Comparison of the wild-type replication competent virus with conditionally replicating adenoviruses (Ad5-d55K and Ad5-d24) showed superior oncolytic activity for the latter 2 in all lines. Furthermore, improved cytotoxicity (29% to 33%) was obtained in 4 of the 7 lines after pre-incubation of Ad5-d24 with 425-s11. CONCLUSIONS: EGF-R directed bispecific single chain antibodies enhance adenovirus mediated transgene expression and oncolysis in bladder cancer lines.     

Binding of insulin-like growth factors to cultured rat calvarial cells with differing biologic responses.

The insulin-like growth factors (IGFs) are considered important regulators of bone metabolism affecting a number of biologic responses in vitro. Primary fetal rat calvarial cells (PRC) and a cloned adult rat calvarial cell line (C3) both exhibit a concentration-dependent IGF stimulation of [3H]thymidine incorporation into DNA, but the C3 cells show a greater sensitivity and magnitude of response. IGF-I and IGF-II were nearly equipotent in PRC cultures, but IGF-I was more than twice as active as IGF-II in the C3 cultures. This effect of the IGFs on DNA synthesis in two bone cell cultures with different culture histories has been correlated with receptor and binding protein profiles. Specific high-affinity IGF binding sites were found in both cell types. In general, the sites present on PRC cells showed a preference for binding IGF-II over IGF-I, but C3 cells displayed two types of relatively specific binding sites. In both cell types [125I]IGF-I bound primarily to a protein with IGF type I receptor characteristics. However, in PRC cells, [125I]IGF-II cross-linked specifically with proteins that had IGF type II receptor characteristics plus several sites unique to these cells; in C3 cells, [125I]IGF-II bound to a 139 kD protein that could be displaced by either IGF-I or IGF-II. Finally, IGF-II-specific 85 and 67 kD proteins were common to both cell types. From these studies, it is apparent that the IGFs bind to a variety of high-affinity binding sites in bone cells and that these sites differ between a highly responsive and a less responsive bone cell population.     

Adenoviral p53 gene transfer in human bladder cancer cell lines: cytotoxicity and synergy with cisplatin

Mutations of the tumor suppressor gene p53 are common in bladder cancer. To determine whether p53 gene transfer would lead to decreased viability of bladder cancer cells, we studied the effect of p53 gene transfer in human bladder cancer cell lines with either mutant or wild-type p53. Bladder cancer cell lines 5637 and J82 (which express only mutant p53) and 253J-BV (which expresses wild-type p53) were transduced with vectors containing the β-galactosidase gene (Ad5-lacZ), wild-type human p53 gene (Ad5CMV-p53), or no foreign gene (DL312 or Ad5-polyA). X-gal staining of cells exposed to Ad5-lacZ showed that the adenoviral vector was capable of transducing each of the cell lines. Increases in p53, p21^waf1/cip1 and bax protein were demonstrated following exposure to Ad5CMV-p53, and there was a dose-dependent increase in the number of apoptotic cells. Cell viability was decreased in all three cell lines, although J82 was less sensitive than either 5637 or 253J-BV. To determine whether cisplatin increases sensitivity of J82 cells to Ad5CMV-p53, we performed median effect analysis for cisplatin combined with Ad5CMV-p53 or DL312. The combination index for cisplatin plus Ad5CMV-p53 revealed synergy, whereas cisplatin and DL312 were only additive. These results suggest that forced p53 gene expression is cytotoxic to human bladder cancer cells with either p53 mutant or wild-type background, and that combination with cisplatin is a potential method for overcoming resistance.     

LIN28在膀胱癌和膀胱癌细胞系中的表达及意义

目的：探讨LIN28在膀胱癌组织和细胞系中表达情况,以及与mieroRNA初级Let-7g（pri—Lev7g）之间关系,推测其可能临床意义及对肿瘤进展的影响。方法：采用常规RT-PCR、miRNA转录、免疫荧光和免疫组化方法,检测LIN28mRNA和pri-Let-7g表达,以及LIN28蛋白表达定位。结果：2例膀胱癌细胞系均表达LIN28mRNA,T24表达较强,免疫荧光显示这两个细胞系均表达LIN28蛋白,阳性部位位于细胞胞质,T24荧光强度强于5637。所选10例膀胱癌和相应癌旁组织均表达LIN28mRNA,二者并无明显不同,与临床分级也无明确关系。免疫组化显示癌组织LIN28表达阳性并定位于胞质,而癌旁正常组织LIN28表达为阴性。此外,两个细胞系pri—Let-7g表达较强,而癌和癌旁组织的pri—Let-7g表达强度无明显差异,需进一步检测其成熟Let-7g在这些组织中是否存在不同,以明确这些miRNA是否发生生物合成的转录后阻断。结论：明确T24和5637两个膀胱癌细胞系均可作为研究LIN28、Let-7与其相应靶基因关系的体外实验模型。尽管并不确定膀胱癌和癌旁组织LIN28、Let-7g表达强度与临床分级是否相关,但至少明确LIN28／LIN28在膀胱癌中表达,为探讨LIN28和Let-7在泌尿系统来源的其他恶性肿瘤中的作用提供借鉴和实验依据。     

LncRNA DANCR regulates lymphatic metastasis of bladder cancer via the miR-335/VEGF-C axis

BackgroundSubstantial evidence indicate that long non-coding RNA (lncRNA) and microRNA (miRNA) act as key role in bladder cancer. Differentiation antagonistic ncRNA (DANCR) could be used as a biomarker in the occurrence and development of cancer. This study aims to explore the mechanism of DANCR/miR-335/VEGF-C axis affecting lymphatic metastasis of bladder cancer.MethodsqRT-PCR detects the expression of DANCR in bladder cancer cell lines (SW780, 5637, T24, UM-UC-3) and normal bladder cell lines (SV-HUC-1), and selects T24 cell lines for subsequent experiments. The expression levels of DANCR, miR-335 and VEGF were measured by qRT-PCR, and the dual luciferase reporter gene verified the targeted regulation of DANCR on miR-335 and miR-335 on VEGF. CCK-8, Transwell and Wound healing assay detect the proliferation, invasion and migration ability of bladder cancer cells, Endothelial cell adhesion assay and Western blot further prove the lymphatic metastasis of bladder cancer.ResultsIn this study, DANCR was highly expressed in bladder cancer cell lines. Transfection of si-DANCR significantly inhibits the proliferation, migration, invasion and lymphatic metastasis of bladder cancer cells. Dual luciferase assay confirmed that DANCR targets miR-335/VEGF-C. Transfection of miR-335 mimic promotes the proliferation, migration, invasion and lymphatic metastasis of bladder cancer cells, overexpression of DANCR eliminates the promotion of miR-335 mimic on bladder cancer cells. Further experiments proved that inhibition of miR-335 and overexpression of VEGF-C can reverse the inhibitory effect of silencing DANCR on bladder cancer cells.ConclusionsIn bladder cancer, DARCR plays an important role, which regulates the proliferation, migration, invasion and lymphatic metastasis of bladder cancer cells through the miR-335/VEGF-C molecular axis.     

Radiation induces<Emphasis Type="Italic"> p53</Emphasis>-dependent cell apoptosis in bladder cancer cells with wild-type-<Emphasis Type="Italic">p53</Emphasis> but not in<Emphasis Type="Italic"> p53</Emphasis>-mutated bladder cancer cells

Purpose. It has been reported in several studies that the absence in cancer cells of the p53 tumor suppressor gene, mutations of which are frequently found in bladder cancer, increases their resistance to ionizing radiation. Other studies, however, suggest that mutations of the p53 gene could increase the radiosensitivity of cancer cells, although the evidence is still inconclusive. In the present study, we investigated the relationship between p53 status and radiation response in five different bladder cancer cell lines. Materials and Methods. Five different human bladder cancer cell lines (KK47: with wt-p53, RT4: with wt-p53, T24: with mutated p53, 5637: with mutated p53, UM-UC-3: with mutated p53) were used in the study. Cells were irradiated with 0, 2, 4, 6 or 8 Gy, then trypsinized and re-plated for clonogenic survival assay, quantitative RT-PCR assay, flow-cytometry analysis and TUNEL assay. Results. The clonogenic assay demonstrated that KK47 and RT4 had significantly higher radiosensitivity than other cell lines. Quantitative RT-PCR analysis showed that radiation induced increased expression of p53, Bax, and p21 mRNA in KK47 and RT4. After irradiation, G1 cell-cycle arrest was observed in KK47 and RT4 under flow cytometry analysis, while T24, 5637, and UM-UC-3 showed an increase in the proportion of G2 cells. Increased cell apoptosis was also observed under TUNEL assay in KK47 and RT4, but not in other cell lines. Conclusions: It was demonstrated that ionizing radiation induces p53-dependent cell apoptosis in bladder cancer cells with wt-p53 but not in those with mutated p53.     

Expression of Med19 in bladder cancer tissues and its role on bladder cancer cell growth

ObjectivesThe human Med19 gene encodes a critical subunit that stabilizes the whole mediator complex. To understand the role of Med19 in bladder cancer, we studied the effects of lentivirus-mediated suppression of Med19 expression on bladder cancer cells in vitro and in vivo.Methods and materialsIn this study, immunohistochemical analysis was used to demonstrate the expression of Med19 in human bladder cancer. The lentivirus vectors containing a small hairpin RNA (shRNA) to target Med19 were constructed. After bladder cancer cells (5637 and T24) were infected, RT-PCR and Western blotting were used to measure Med19 expression. The influence of Med19 on the proliferation of bladder cancer cells were assessed using MTT, BrdU, colony formation and tumorigenicity experiments. Cell cycle was analyzed with flow cytometric assay.ResultsMed19 was up-regulated in human bladder cancers compared with adjacent benign tissues by immunohistochemical analysis, but was strongly inhibited in 5637 and T24 bladder cancer cells infected with lentiviruses delivering shRNA against Med19. The down-regulation of Med19 increased the proportion of cells in G0/G1 phases and attenuated the growth of 5637 and T24 cells in vitro. The tumorigenicity of Med19-suppressed T24 cells was decreased after inoculation into nude mice.ConclusionsOur results suggested that lentiviruses delivering shRNA against Med19 may be a promising tool for bladder cancer therapy.     

Interferon-α inhibits cyclooxygenase-1 and stimulates cyclooxygenase-2 expression in bladder cancer cells in vitro

The enzymes cyclooxygenase-1 (Cox-1) and cyclooxygenase-2 (Cox-2) catalyze the initial step in the formation of prostaglandins (PGs). PGs are known to be involved in numerous processes, for example inflammation, immune responses, carcinogenesis, and tumor angiogenesis. The formation of PGs is stimulated in various cancers since the expression of Cox-2 is upregulated. Interferon (IFN)-α is used in the treatment of bladder cancer, although not all of the effects of such treatment are thoroughly known. Therefore, we investigated the expression of cyclooxygenases in two bladder cancer cell lines, 5637 and T24, under basal conditions and in the presence of human recombinant IFN-α (100, 1,000, and 10,000 U/ml). The mRNA of Cox-1 and Cox-2 was expressed in both cultured bladder carcinoma cell lines. The level of Cox-1 expression was low in 5637 cells and higher in T24 cells. In contrast, Cox-2 expression was prominent in 5637 cells and low in T24 cancer cells. The highest IFN-α concentration (10,000 U/ml) decreased the expression of Cox-1 to 47 and 28% of the control levels in 5637 and T24 cells, respectively. In contrast, Cox-2 expression increased in both cell lines. In 5,637 cells, Cox-2 expression increased 1.3-fold with 10,000 U/ml of IFN-α. In T24 cells, the maximum effect was achieved by 1,000 U/ml of IFN-α, which increased the expression of Cox-2 up to 2.4-fold. These findings may have relevance in the outcome of patients treated with IFN-α because upregulated Cox-2 expression may suppress the cell-mediated defense system. On the other hand, the inhibition of Cox-1 could be beneficial because Cox-1 is known to stimulate angiogenesis. Received: 5 August 1999 / Accepted: 8 September 2000     

CHEMOSENSITIZATION OF BLADDER CARCINOMA CELLS BY BCL-xL ANTISENSE OLIGONUCLEOTIDES

PURPOSE: We investigated antisense inhibition of anti-apoptotic bcl-xL and bcl-2 proteins to increase chemosensitization in the T24 and 5637 bladder carcinoma cell lines. MATERIALS AND METHODS: A T24 bladder carcinoma cell line stably over expressing bcl-xL protein was constructed. Apoptosis by cytotoxic agents was estimated by cell cycle analysis and Annexin V binding. To eliminate bcl-xL expression T24 and 5637 cells were treated with C5-propynylated and 2'-O-methylribo-oligonucleotides. Levels of protein and messenger RNA were measured by Western and Northern blot analysis. Cell viability after combined treatment with oligonucleotides and various cytotoxic agents was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and evaluated statistically by Student's 2-sample t test. RESULTS: Forced over expression of bcl-xL protein desensitized the T24 bladder carcinoma cell line to cytotoxic agents. C5-propynylated and 2'-O-methylribo-oligonucleotides down-regulated bcl-xL protein expression in the T24 and 5637 cell lines, and increased their sensitivity to cytotoxic agents. The efficiency of antisense down-regulation of bcl-xL protein expression depended on the type of delivery agent. CONCLUSIONS: Antisense down-regulation of bcl-xL protein sensitizes bladder carcinoma cells to cytotoxic agents. However, it is possible that cellular chemosensitization results from a combination of effects, including nonsequence specificity, irrelevant cleavage and effects of the carriers combined with the specific antisense effects.     

RNA干扰下调p53抑制因子iASPP表达对膀胱癌细胞的影响

目的 探讨RNA干扰使p53抑制因子iASPP表达下调对膀胱癌细胞的影响.方法 iASPP siRNA慢病毒感染入膀胱癌细胞株5637和T24,实时定量PCR和蛋白质印迹法检测iASPP的表达;噻唑盐法测定细胞生长;集落形成测定法检测集落形成比率;荧光激活细胞分选术检测细胞周期.结果 iASPP siRNA慢病毒感染后细胞iASPP mRNA为0.60±0.02,低于阴性对照慢病毒组(1.00±0.03,P＜0.05).膀胱癌细胞iASPP蛋白表达降低.iASPP下调能抑制入膀胱癌细胞5637和T24的生长和增殖(P＜0.05),每个集落中细胞数显著减少(P＜0.05),集落数目也低于阴性对照组(P＜0.05).iASPP siRNA慢病毒5637细胞培养中的G1期细胞比率明显高于阴性对照慢病毒组,分别为(51.94±0.98)%和(46.00±0.77)%;T24细胞结果与之类似,分别为(60.04±0.45)%和(53.62±0.69)%;组间比较差异均有统计学意义(P＜0.05).结论 RNA干扰能够使膀胱癌细胞iASPP表达下调,从而抑制膀胱癌细胞的生长和增殖.

Abstract：

Objective To discuss the effects of silencing of iASPP gene on human bladder cancer cells. Methods RNAi silencing of iASPP gene in bladder cancer cell 5637 and T24 cells were used by lentiviral mediated interfering short hairpin RNAs. Cell proliferation was tested by MTT assay, and rate of colony was tested by colony formation assay. Cell cycles were tested by using fluorescence-activated cell sorting. Results Down-regulation of iASPP could inhibit the growth and proliferation of human bladder cancer cells (P＜0.05). iASPP know-down could decrease the colony formation of 5637 and T24 cells (P＜0, 05). Knocking down of iASPP in 5637 and T24 cells showed cell arrested at G1. Conclusions Silencing of iASPP gene could inhibit proliferation and colony formation of bladder cancer, iASPP might be an important target for gene therapy of bladder cancer.