血管抑素和内皮抑素的研究进展

近年来,越来越多的学者对血管抑素和内皮抑素的结构、作用机制以及抗肿瘤作用做了深入的研究,认为它们极有可能成为未来抗肿瘤的主要药物,为肿瘤治疗提供新的有效手段.     

Addition of an aminopeptidase N-binding sequence to human endostatin improves inhibition of ovarian carcinoma growth

BACKGROUND: Blood vessels in tumors express higher level of aminopeptidase N (APN) compared with normal tissues. It has been reported that peptides that contain asparagine-glycine-arginine (NGR) sequence home to APN in tumor vasculature. Increased expression of APN in tumor vascular endothelium, therefore, offers an opportunity to target NGR peptide-linked therapeutic reagents to tumors. METHODS: To determine whether an additional NGR sequence could improve endothelial homing and biologic activity, human endostatin was modified genetically to introduce an NGR motif (NGR-endostatin) and was expressed in yeast. In vitro biologic activity of NGR-endostatin was compared with the native protein in endothelial cell proliferation and migration. NGR-modified endostatin was used in tumor localization studies. Finally, the effects of endostatin and NGR-endostatin on tumor growth were determined in two model systems. RESULTS: Human endostatin has an internal NGR sequence, which is not accessible to bind APN. However, the addition of an NGR-sequence at the amino terminus resulted in strong binding and inhibition of endothelial cell APN. NGR-endostatin showed increased binding to endothelial cells compared with the native protein. Increased binding of endostatin also coincided with improved antiangiogenic properties of endostatin. NGR modification improved tumor localization and, as a consequence, effectively inhibited ovarian carcinoma growth in athymic nude mice. CONCLUSIONS: These studies demonstrated that human endostatin can be modified genetically to improve its ability to inhibit tumor growth.     

血管抑素基因和内皮抑素基因抑制肝癌作用的比较

日的:比较血管抑素(angiostatin)和内皮抑素(endostain)基因抑制肝癌作用的差异.方法:建立大鼠肝癌模型,随机分组,在肝癌局部分别注入血管抑素基因、内皮抑素基因、血管抑素 内皮抑素基因及0.9%氯化钠溶液,观察各组肿瘤微血管密度(microvessel density,MVD)、肿瘤凋亡率、肺转移瘤的数量、大鼠生存期及肿瘤生长率等指标.结果:所有治疗组的肿瘤体积生长率均受到抑制,以双基因联合的作用最为明显.各治疗组肺内转移灶数、MVD和凋亡指数与对照组相比,差异均有统计学意义(P<0.01,P<0.05和P<0.05);双基因联合应用组与其他治疗组相比,差异具有统计学意义(P<0.05);而单一基因治疗组之间比较差异无统计学意义(P>0.05).双基因联合应用后大鼠存活时间最长,而对照组生存时间最短.结论:血管抑素、内皮抑素均通过抑制肿瘤新生血管的生长、迁移而达到抑制肿瘤生长和转移的目的,2种抑素基因的协同作用更加明显.     

In vitro growth inhibition of ovarian cancer cells by decorin: synergism of action between decorin and carboplatin

In vitro studies showed that decorin, a small proteoglycan that is a normal component of the cell matrix involved in tissue scaffolding, effectively inhibited the growth of two ovarian cancer lines, SKOV3 and 2774. Using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay to measure cell growth, IC50s for decorin ranged from 150 to 400 microg/ml for the two cell lines. In contrast, the growth of tumor cells grown on an artificial cell matrix (Matrigel) was unaffected by decorin treatment, perhaps because of the decorin being irreversibly bound by matrix-associated collagen. Decorin-induced inhibition of ovarian tumor cells appeared to be associated with the increased expression of the cyclin-dependent kinase inhibitor p21Waf1/Cip1. Up-regulation of p21 expression was shown by Western blot analysis in decorin-treated ovarian cancer cells. No decorin-induced up-regulation of c-myc was seen, although decorin was reported to activate the epidermal growth factor receptor. Decorin was also shown to synergize with carboplatin to inhibit the growth of ovarian tumor cells. Additional studies are warranted to determine the role of decorin in the treatment of ovarian cancer.     

内皮抑素抑制裸鼠肺癌生长转移的实验研究

背景与目的:内皮抑素(endostatin,ES)可以有效抑制血管发生.系统给予ES可引起多种肿瘤异种移植模型生长减缓.本实验通过建立裸鼠肺癌胸腔移植模型,观察ES对裸鼠肺癌生长和转移的抑制作用.方法:将大细胞肺癌H460细胞接种于裸鼠左侧胸腔,并随机分成内皮抑素组(ES组)和对照组.ES组和对照组裸鼠自接种肿瘤的当天开始,每天分别给予ES 20mg/kg和等体积PBS皮下注射,共20 d.每日称量动物体重,记录动物生存时间,处死后称瘤重,测定动物血液中基质金属蛋白酶2(matrix metalloproteinase-2, MMP2)的表达.结果:裸鼠肺癌胸腔内接种成瘤率为100%,并出现远处转移.对照组移植瘤重量(1.54±0.14)g明显高于ES组(0.9±0.3)g,差异有显著性(t=-3.163,P=0.005),且第1天和第21天体重差值(1.9±2.8)g与ES组(-0.8±2.8)g比较,差异有显著性(t=-2.156,P=0.045).而ES组的MMP2表达明显低于对照组.结论:ES可抑制肺肿瘤生长和转移,其作用机制之一与抑制MMP2的表达活性有关.裸鼠肺癌胸腔移植模型更容易形成肺癌转移模型,是研究肺癌生长和转移的理想模型.     

Liposomes complexed to plasmids encoding angiostatin and endostatin inhibit breast cancer in nude mice.

Gene therapy transfer of angiostatin and endostatin represents an alternative method of delivering angiogenic polypeptide inhibitors. We examined whether liposomes complexed to plasmids encoding angiostatin or endostatin inhibited angiogenesis and the growth of MDA-MB-435 tumors implanted in the mammary fat pads of nude mice. We determined that plasmids expressing angiostatin (PCI-Angio) or endostatin (PCI-Endo) effectively reduced angiogenesis using an in vivo Matrigel assay. We then investigated the efficacy of these plasmids in reducing the size of tumors implanted in the mammary fat pad of nude mice. Both PCI-Angio and PCI-Endo significantly reduced tumor size when injected intratumorally (P < 0.05). Compared to the untreated control group, the mice treated with PCI-Angio and PCI-Endo exhibited a reduction in tumor size of 36% and 49%, respectively. In addition, we found that i.v. injections of liposomes complexed to PCI-Endo reduced tumor growth in the nude mice by nearly 40% when compared to either empty vector (PCI) or untreated controls (P < 0.05). These findings provide a basis for the further development of nonviral delivery of antiangiogenic genes.     

Sphingosine kinase-1 inhibition sensitizes curcumin-induced growth inhibition and apoptosis in ovarian cancer cells

Recent published studies suggest that increasing levels of ceramides enhance the chemo-sensitivity of curcumin. Using in vitro approaches, we analyzed the impact of sphingosine kinase-1 (SphK-1) inhibition on ceramide production, and evaluated SphK1 inhibitor II (SKI-II) as a potential curcumin chemo-sensitizer in ovarian cancer cells. We found that SphK1 is overexpressed in ovarian cancer patients' tumor tissues and in cultured ovarian cancer cell lines. Inhibition of SphK1 by SKI-II or by RNA interference (RNAi) knockdown dramatically enhanced curcumin-induced apoptosis and growth inhibition in ovarian cancer cells. SKI-II facilitated curcumin-induced ceramide production, p38 activation and Akt inhibition. Inhibition of p38 by the pharmacological inhibitor (SB 203580), a dominant-negative expression vector, or by RNAi diminished curcumin and SKI-II co-administration-induced ovarian cancer cell apoptosis. In addition, restoring Akt activation introducing a constitutively active Akt, or inhibiting ceramide production by fumonisin B1 also inhibited the curcumin plus SKI-II co-administration-induced in vitro anti-ovarian cancer effect, suggesting that ceramide accumulation, p38 activation and Akt inhibition are downstream effectors. Our findings suggest that low, well-tolerated doses of SKI-II may offer significant improvement to the clinical curcumin treatment of ovarian cancer.     

SA脂质体介导血管抑素和／或内皮抑素基因治疗Lewis肺癌小鼠的实验研究

 目的 观察SA脂质体介导血管抑素和／或内皮抑素基因对Lewis肺癌小鼠移植瘤生长、转移的抑制作用。方法 建立C57BL／6j小鼠肺癌模型，30只荷瘤鼠随机分空白对照组，SA脂质体对照组，血管抑素基因（pAng）治疗组，内皮抑素基因（pEnd）治疗组，血管抑素和内皮抑素基因联合治疗组，每组6只。以SA脂质体介导，将血管抑素和／或内皮抑素基因直接注入移植瘤内，每周2次，共6周，每周测瘤体大小2次，6周末处死所有小鼠，观察瘤体大小变化、肺表面转移灶数、生存期等。结果 各治疗组均能抑制肿瘤增长及肺内转移，与对照组比较有统计学意义（P＜0.01），小鼠活动能力、饮食、对外界刺激的反应能力均无明显改变，生存期明显长于对照组。结论 SA脂质体介导血管抑素和／或内皮抑素基因治疗可有效地抑制Lewis肺癌移植瘤的生长、转移，生存期明显长于对照组。     

Effects and mechanisms of endostatin on the growth of ovarian cancer SKOV3 cells in vitro and in vivo

Objective To evaluate the inhibitory effect of Endostatin on ovarian cancer cell line SKOV₃ and to investigate the possible mechanism of the inhibition. Methods Using MTT, transmission electron microscope (TEM) and immunocytochemistry, the effects of Endostatin on the proliferation of SKOV₃ cells were studied. Nude mice were subcutaneously implanted with SKOV₃ cells. The cell apoptosis of implanted tumor was detected by TUNEL and TEM. The expressions of bcl-2 and bax in implanted tumor tissues were measured by RT-PCR and immunohistochemistry. Results Endostatin significantly inhibited the proliferation of SKOV₃ cells in vitro (P<0.01) and induced cell apoptosis, whereas the expressions of bcl-2 and bax were not changed obviously in SKOV₃ cell treated with Endostatin. The mean tumor weight of Endostatin treated group was markedly lower than that of PBS control group (P<0.05). The expression of bcl-2 was down-regulated in Endostatin treated group, but bax was not influenced. Conclusions The results demonstrated that Endostatin might have anti-tumor effect on ovarian carcinoma. One of the important mechanisms of Endostatin effect of anti-angiogenic and anti-tumor activities might involve regulating the bcl-2/bax expression and inducing apoptosis. Biography: LIU Mei-mei(1977–), female, candidate doctor of medicine, The Second Affiliated Hospital, Harbin Medical University, majors in gynecology.     

Growth Inhibition of Breast Cancer in Rat by AAV Mediated Angiostatin Gene

Objective： To observe growth inhibition effect of adeno-associated viral vectors （AAV） mediated angiostatin （ANG） gene on implanted breast cancer in rat and its mechanism. Methods： Gene transfer technique was used to transfer AAV-ANG to the tumor. Growth curves were drawn to observe the growth of breast cancer implanted in rat, and immunohistochemical method was used to detect the effects of angiostatin on microvesel density （MVD） of breast cancer implanted in rat. Results： Angiostatin inhibited the growth of breast cancer implanted in rat and decreased the microvessel density of tumor. Conclusion： Expression of an angiostatin transgene can suppress the growth of breast cancer implanted in rat through the inhibition of the growth of microvessels, surggesting that angiostatin gene transfer technique may be effective against breast cancer.     

Multi-kinase inhibition in ovarian cancer

Sorafenib (Nexavar) is a multi-kinase inhibitor that was developed as an inhibitor of RAF-1, in the ERK1/2 pathway, but which was subsequently shown to inhibit class III tyrosine kinase receptors.¹ More recently regorafenib (Stivarga) has been developed, which is a further fluorinated version of sorafenib with greater bioavailability and similar inhibitory properties against RAF-1/class III RTKs.² Some of the anti-tumor effects of sorafenib have been ascribed to anti-angiogenic actions of this agent on endothelial associated kinases such as VEGFR2. Other effects of sorafenib clearly have to be due to its effects on the inherent biology of the tumor cells themselves. For example, through various mechanisms sorafenib has been shown in the laboratory and the clinic to suppress expression of the protective protein MCL-1.³ Sorafenib has also been linked to inhibition of STAT3, NFκB, and activation of the death receptor CD95.⁴ Sorafenib is routinely dosed daily (400 mg BID) and 7 d after the start of dosing has a C_max of ~21 μM with a nadir at 12 h of ~10 μM, and is a highly protein bound based on in vitro assays.⁵ Despite this in vitro binding data sorafenib has profound in vivo effects on tumor cells in renal carcinoma and hepatocellular carcinoma patients; cells which are not per se addicted to high activity oncogene signals that are targets of sorafenib/regorafenib. Thus the precise stable bioavailable level of sorafenib/regorafenib in patient plasma is not known.     

Binding of endostatin to human ovarian cancer cells inhibits cell attachment

Endostatin, a C-terminal fragment of collagen type XVIII, is one of the well-characterized endogenous inhibitors of angiogenesis. Endostatin is known to bind integrin alpha(5)beta(1), which is upregulated on tumor endothelium. Most of the ovarian cancer cells express significant amounts of alpha(5)beta(1) integrin, which is important for ovarian cancer cells to attach to the peritoneal wall. Therefore we investigated whether endostatin could directly bind ovarian cancer cells and inhibit tumor cell attachment to extracellular matrix. Binding of endostatin to ovarian cancer cells was characterized by preincubation with function blocking antibodies to integrin subunits. These studies showed that ovarian cancer cell attachment to fibronectin-coated wells can be inhibited by alpha(5)beta(1) integrin specific antibodies as well as endostatin. Downregulation of integrin alpha(5) and beta(1) by siRNA abrogated the binding of OVCAR5 and human umbilical vein endothelial cell to endostatin. Although endostatin treatment did not affect ovarian cancer cell migration, treated cells failed to attach mouse peritoneal wall preparations. These studies suggest an extra-antiangiogenic role for endostatin, which can be used prevent peritoneal attachment and dissemination of ovarian cancer cells.     

Correlation between serum vascular endothelial growth factor and endostatin levels in patients with breast cancer

Serum vascular endothelial growth factor (VEGF) and endostatin levels were detected in 59 patients with breast cancer before surgery and at 3 weeks after surgery. Pre-operatively, their levels were significantly elevated and correlated with each other. Post-operatively, VEGF level decreased significantly and endostatin remained at a high level. Patients with both normalized VEGF and elevated endostatin following surgery had a lower risk of relapse than patients whose VEGF failed to normalize. Univariate and multivariate analyses showed a correlation between elevated VEGF level and short free-relapse survival. These findings suggest a new angiogenesis balance is formed in the patients after surgery and such a resultant balance may be beneficial for the prognosis of breast cancer, which deserves more extensive study.     

Tyrphostins and retinoids cooperate during inhibition of in vitro growth of ovarian cancer cells

Chemoresistance of ovarian cancer can be overcome by co-administration of retinoids, albeit clinical proof of this hypothesis is pending. Moreover, growth factor/c-erbB signaling is crucial for ovarian tumor growth/chemosensitivity. Retinoids and c-erbB modulators therefore represent promising drugs for ovarian cancer. We demonstrate that c-erbB-1 (RG-14620, AG1517) and c-erbB-2 selective tyrphostins (AG825, AG879), and all-trans and 9-cis retinoic acid inhibit ovarian cancer cell proliferation (HOC-7, OVCAR-3). Unlike retinoids, AG1517 and AG879 induce apoptosis. The antiproliferative activity of AG1517 is enhanced by all-trans retinoic acid suggesting that c-erbB and retinoid pathways interact. Thus, these agents cooperate during ovarian cancer cell growth inhibition.     

内皮抑素和血管内皮生长因子在卵巢癌组织中的表达及其临床意义

背景与目的:血管内皮生长因子(vascularendothelialgrowthfactor,VEGF)能够诱导血管生成,导致肿瘤的生长、侵袭及远处转移;内皮抑素(endostatin)强效抑制肿瘤血管生成,进而抑制肿瘤生长、侵袭和转移。为探讨内皮抑素和VEGF在卵巢癌组织中的表达及其与卵巢癌发生发展的关系,本研究拟从基因和蛋白水平研究二者在卵巢癌组织中的表达情况。方法:运用逆转录聚合酶链反应(RT-PCR)和免疫组织化学染色法检测内皮抑素和VEGF在正常卵巢组织、卵巢癌组织中的表达情况。结果:卵巢癌组织中内皮抑素和VEGFmRNA表达水平及蛋白阳性率均高于正常卵巢组织(P<0.05);临床Ⅲ、Ⅳ期卵巢癌组织中内皮抑素和VEGFmRNA表达水平及蛋白阳性率均高于Ⅰ、Ⅱ期(P<0.05);内皮抑素mRNA≤0.5组和mRNA>0.5组,其蛋白阳性率分别为29.4%和77.8%(P<0.05);VEGFmRNA≤0.5组和mRNA>0.5组,其蛋白阳性率分别为20.0%和72.0%(P<0.05)。结论:正常卵巢组织和卵巢癌组织中内皮抑素、VEGFmRNA和蛋白含量的变化是一致的,内皮抑素与VEGF比例失调可能是卵巢癌发生发展的重要机制之一。     

Androgen receptor and vitamin D receptor in human ovarian cancer: growth stimulation and inhibition by ligands

The data suggest that 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] and androgens are essential for regulation of growth and differentiation in, e.g., human reproductive tissues. We investigated the possible cross-talk between 1,25(OH)2D3 and androgens in the human ovarian cancer cell line OVCAR-3. Our data demonstrate that 1,25(OH)2D3 and androgen (dihydrotestosterone, DHT) regulate the growth of OVCAR-3 cells. Nine days' treatment of OVCAR-3 cells with 100 nM DHT resulted in 48% stimulation of growth, whereas growth inhibition (73%) was observed after treatment with 100 nM 1,25(OH)2D3. The combination of 1,25(OH)2D3 and DHT showed that 1,25(OH)2D3 clearly reduces the growth-stimulatory effect of DHT on OVCAR-3 cells. Moreover, Western blot analysis revealed that these cells contain receptors for 1,25(OH)2D3 (VDR) and androgen (AR). Expression of VDR and AR was up-regulated by their cognate ligands. Up-regulation of AR by 1,25(OH)2D3 and of VDR by DHT provides evidence of cross-talk between 2 signaling pathways in OVCAR-3 cells. We also studied the immuno-histochemical distribution of VDRs and ARs in rat ovaries and human ovarian cancer cases. In rat ovaries, VDRs were observed mainly in granulosa and theca cells and ARs in granulosa cells and surface epithelium. In the human ovarian cancer cases studied, 43% were VDR-positive and 64% AR-positive. Combining the results suggests that the growth of ovarian tissue might be regulated by 1,25(OH)2D3 and androgen.     

Interleukin-10-mediated inhibition of angiogenesis and tumor growth in mice bearing VEGF-producing ovarian cancer

Interleukin-10 (IL-10) is an immunosuppressive cytokine produced by T lymphocytes and drawing attention as an inhibitor of tumor angiogenesis. In this study, we investigated antiangiogenic and tumor suppressive effects of IL-10 in ovarian cancer cells. mIL-10-expressing plasmid was transferred into two ovarian cancer cell lines, SHIN-3 [vascular endothelial growth factor (VEGF) producing] and KOC-2S (non-VEGF producing). After selection, mIL-10-expressing cells were obtained as SHIN-3/mIL-10 and KOC-2S/mIL-10. No significant differences were observed in in vitro growth properties between mIL-10-expressing cells and control (luciferase expressing) cells in either KOC-2S or SHIN-3. The angiogenic activities of mIL-10-expressing cells were measured by dorsal air sac assay, which detected the number of newly formed blood vessels within a chamber in vivo. In addition, tumor formation was evaluated by s.c. tumor transplantation, and survival was monitored after i.p. injection of ovarian cancer cells into BALB/c nude mice. Both in vivo angiogenic activity and tumor growth were significantly inhibited in SHIN-3/mIL-10 cells compared with the control. Moreover, peritoneal dissemination was inhibited, and the survival period was significantly prolonged (mean survival days > 90 versus 36). In contrast, in the case of KOC-2S cells, no significant differences were observed in any of the parameters tested. These results indicate that IL-10 has suppressive effects on angiogenesis, tumor growth, and peritoneal dissemination of VEGF-producing ovarian cancer cells. Although the mechanisms of the antiangiogenic effect of IL-10 are still unclear, the potential usefulness of IL-10-mediated gene therapy of ovarian cancer was suggested.     

Adeno-associated virus 2-mediated antiangiogenic cancer gene therapy: long-term efficacy of a vector encoding angiostatin and endostatin over vectors encoding a single factor

Angiogenesis is characteristic of solid tumor growth and a surrogate marker for metastasis in many human cancers. Inhibition of tumor angiogenesis using antiangiogenic drugs and gene transfer approaches has suggested the potential of this form of therapy in controlling tumor growth. However, for long-term tumor-free survival by antiangiogenic therapy, the factors controlling tumor neovasculature need to be systemically maintained at stable therapeutic levels. Here we show sustained expression of the antiangiogenic factors angiostatin and endostatin as secretory proteins by recombinant adeno-associated virus 2 (rAAV)-mediated gene transfer. Both vectors provided significant protective efficacy in a mouse tumor xenograft model. Stable transgene persistence and systemic levels of both angiostatin and endostatin were confirmed by in situ hybridization of the vector-injected tissues and by serum ELISA measurements, respectively. Whereas treatment with rAAV containing either endostatin or angiostatin alone resulted in moderate to significant protection, the combination of endostatin and angiostatin gene transfer from a single vector resulted in a complete protection. These data suggest that AAV-mediated long-term expression of both endostatin and angiostatin may have clinical utility against recurrence of cancers after primary therapies and may represent rational adjuvant therapies in combination with radiation or chemotherapy.     

Synergy between PPARgamma ligands and platinum-based drugs in cancer

PPARgamma is a member of the nuclear receptor family for which agonist ligands have antigrowth effects. However, clinical studies using PPARgamma ligands as a monotherapy failed to show a beneficial effect. Here we have studied the effects of PPARgamma activation with chemotherapeutic agents in current use for specific cancers. We observed a striking synergy between rosiglitazone and platinum-based drugs in several different cancers both in vitro and using transplantable and chemically induced "spontaneous" tumor models. The effect appears to be due in part to PPARgamma-mediated downregulation of metallothioneins, proteins that have been shown to be involved in resistance to platinum-based therapy. These data strongly suggest combining PPARgamma agonists and platinum-based drugs for the treatment of certain human cancers.     

Effect of inhibition of the adrenomedullin gene on the growth and chemosensitivity of ovarian cancer cells

Adrenomedullin (AM), a potent vasodilator peptide, is present in various types of tumors. Here, we constructed short hairpin RNA (shRNA) in order to target the AM gene in?vitro using RNA interference (RNAi) technology. HO8910 ovarian cancer cells were transfected, and the effects of AM on proliferation and chemosensitivity of the cells were examined. RT-PCR, real-time PCR and western blot analysis were performed to detect the AM gene and protein expression. The MTT assay was used to observe the effect of AM on proliferation and chemosensitivity of the cells. Also, the protein levels of bcl-2 and the extracellular regulated protein kinase (ERK) were evaluated by western blot analysis. We found that silencing of the AM gene inhibited the proliferation and increased the chemosensitivity of HO8910 cells, reduced the expression of AM mRNA and protein as well as downregulated bcl-2 and p-ERK expression. We, therefore, conclude that silencing of the AM gene in HO8910 ovarian cancer cells inhibited the proliferation and increased the chemosensitivity of the cells through downregulation of ERK and bcl-2 expression. Thus, anti-AM treatment together with suppression of ERK and bcl-2 expression provides a novel research approach for ovarian cancer.