Antitumor mechanism of Se-containing polysaccharide, a novel organic selenium compound

Recent studies on the inhibition of tumor growth by Se-containing polysaccharide were reviewed. Meanwhile, the possible molecular mechanisms of the inhibition of tumor cell growth through antioxidation, induction of tumor cell apoptosis, blockade of cell cycle, and enhancement of immunity by Se-containing poly-saccharide were proposed. In the end, the potential application of Se-containing polysaccharide in the preven-tion and treatment of tumor was elucidated.     

野生仙人掌多糖对肺鳞癌细胞SK-MES-1 生长的抑制作用

目的:探讨仙人掌多糖对体外肺鳞癌细胞(SK-MES-1)生长抑制作用。方法:体外培养SK-MES-1细胞,四甲基偶氮唑盐(MTT)法观察野生仙人掌多糖对其生长的抑制,计算最低抑制浓度及抑制率;观察不同浓度多糖对细胞形态的影响;SDS-PAGE凝胶电泳简析不同组别蛋白质表达的差异。结果:野生仙人掌多糖24 h和48 h对肿瘤细胞的最低抑制浓度和抑制率分别为0.0625 mg/ml.34.06%和0.0625 mg/ml 35.37%;不同组间蛋白质表达有差异。结论:野生仙人掌多糖对SK-MES-1肺鳞癌细胞有抑制作用。     

簇生沿丝伞粗多糖的抗肿瘤活性研究

应用传统多糖提取方法从簇生沿丝伞中获得粗多糖,初步纯化后进行了抗癌活性的体外及体内实验。结果表明,簇生沿丝伞中多糖成分具有很好的抗肿瘤活性,对MCF-7细胞体外细胞增殖抑制率达22.4%,体内抗肝癌抑瘤率达33.79%。     

海参多糖抑制人肾癌细胞A498的生长转移作用机制

肾细胞癌(RCC)是最常见的恶性癌之一,癌症转移是目前导致肾癌患者死亡的主要原因之一。MMP-9被发现在许多具有侵袭性和转移能力的人类癌症中过表达,其表达和分泌受到NF-κB调控;VEGF在维持原发性癌和转移瘤生长所需的血管生成中发挥重要作用,其表达也受到活化的NF-κB调节。海参的多种活性物质在抗氧化、抗菌和抗癌方面都有出色的作用,而抗癌的主要机制则包括诱导癌细胞凋亡、抑制癌细胞生长、减少癌细胞转移等。本研究通过利用不同浓度的海参多糖处理人肾癌细胞A498,采用MTT细胞增殖实验、粘附实验、迁移实验和小室侵袭实验,研究了海参多糖对A498细胞的生长转移的影响;采用蛋白印记法检测了海参多糖对A498细胞内MMP-9、NF-κBp65和VEGF表达水平的影响。结果表明,海参多糖能够显著抑制A498细胞的增殖活力、粘附能力、迁移能力和侵袭能力,并且全都表现出明显的剂量依赖性;中浓度(100μg/mL)和高浓度(200μg/mL)的海参多糖能够显著下调A498细胞内MMP-9、NF-κBp65和VEGF的表达。这些结果说明海参多糖能有效抑制人肾癌细胞A498的生长、转移和侵袭,可能的机制是通过抑制NF-κB信号通路下调MMP-9和VEGF的表达,从而发挥抗癌细胞转移的作用。     

Intracellular distribution of selenium and the growth of mammary cells in culture

Retention of Se in CMT-13 cells increased with an increase in the concentration of selenite in the incubation medium, the duration of exposure, and the density of the culture. The enhanced toxicity of selenite coincided with a proportional increase in Se in both the cytoplasm and nucleus. About 90% of the accumulated Se was isolated with cytoplasmic macromolecules. Increased nuclear Se retention correlated with increased cytoplasmic Se retention. Greater quantities of cytosolic Se-containing proteins (74, 55, 41, 34, and 28 kDa) and a nuclear Se-containing protein (56 kDa) were detected as the quantity of Se within CMT-13 cells increased. These findings suggest that cellular retention and distribution of Se are determinanants of the degree of cellular growth inhibition caused by this trace element.     

软骨多糖对L1210白血病小鼠生长抑制作用的研究

目的:研究软骨多糖对L1210白血病小鼠的生长抑制作用,并探讨其抑瘤作用机理。方法:建立DBA/2小鼠L1210腹水瘤模型,将小鼠分为对照组、低剂量组、中剂量组和高剂量组进行实验,通过腹腔注射软骨多糖治疗,每天称重并记录小鼠的生存时间,计算生命延长率。于0h、24h、48h、72h抽取治疗组小鼠的腹水瘤细胞进行细胞周期的分析;采用常规HE染色观察细胞形态学变化;应用免疫荧光方法检测BCL-2和BAD蛋白表达变化,以进一步探讨软骨多糖的抑瘤机制。结果:软骨多糖可以明显提高DBA/2小鼠的生存率;细胞形态学观察可见细胞出现细胞浆浓缩、核固缩及凋亡小体等现象;软骨多糖作用后的L1210细胞,其细胞周期被阻遏于Go/G1期,24h-48h凋亡率迅速上升;Bad蛋白的表达水平于给药24h-72h后升高,抗凋亡基因Bcl-2表达下降。结论:软骨多糖可能通过影响肿瘤细胞周期和Bad、Bcl-2蛋白的表达来诱导L1210细胞凋亡,并显著抑制肿瘤细胞的生长,延长DBA/2小鼠的生存时间,是一种新型的抑癌活性物质。     

人参多糖对环磷酰胺的增效减毒作用

目的探讨人参多糖（ginseng polysaccharide,GPS）对化疗药物环磷酰胺（cyclophosphamide,CTX）抗肿瘤的增效减毒作用。方法建立小鼠肝癌H22实体瘤模型,随机分组,设模型对照组（生理盐水）、环磷酰胺组（30 mg/kg）、人参多糖给药组（7.5、15、30 mg/kg剂量组）和联合给药组（GPS 7.5、15、30 mg/kg,CTX 30 mg/kg）;人参多糖尾静脉注射,CTX腹腔给药,连续给药10 d;测定抑瘤率、血液学指标、脾脏系数和胸腺系数,评价人参多糖对环磷酰胺的增效减毒作用。结果 GPS、GPS＋CTX各组肿瘤生长明显低于模型对照组（P〈0.01）,GPS中、高剂量＋CTX联合给药组肿瘤生长明显低于CTX组（P〈0.05,P〈0.01）。GPS高剂量＋CTX组与CTX组相比,体重、脾脏指数和胸腺指数明显升高（P〈0.05）。结论人参多糖对化疗药物环磷酰胺抗小鼠肝癌H22肿瘤具有增效减毒作用。     

条斑紫菜多糖PY-D2对4种人肿瘤细胞株生长的影响

目的:研究条斑紫菜多糖体外抗肿瘤的生物学活性。方法:应用生化技术分离和纯化条斑紫菜多糖,获得条斑紫菜多糖的2个组分,分别为PY-D1和PY-D2;在体外培养条件下分别用不同浓度的条斑紫菜多糖PY-D2处理4种人肿瘤细胞,通过MTT法观察条斑紫菜多糖PY-D2对4种人肿瘤细胞生长的影响;采用流式细胞仪检测肿瘤细胞的细胞周期变化。结果:条斑紫菜多糖PY-D2诱导HO-8910、MCF-7、K562和7721肿瘤细胞72h后,对其生长有明显的抑制作用,呈剂量依赖效应,500mg/LPY-D2的抑制率分别为21.2%、23.6%、19.8%和21%(P<0.001)。流式细胞仪检测表明PY-D2可以阻滞肿瘤细胞的细胞周期于G0/G1期或G2/M期。结论:条斑紫菜多糖PY-D2具有抑制肿瘤细胞HO-8910、MCF-7、K562和7721生长的作用,其有关的分子生物学作用机理值得进一步研究。     

Significance of protein elicitor isolated from Tuber melanosporum on the production of ganoderic acid and Ganoderma polysaccharides during the fermentation of Ganoderma lucidum

Under the elicitation of protein elicitor isolated from the culture mycelia of Tuber melanosporum, the biosynthesis of ganoderic acids (GA) was significantly stimulated during Ganoderma lucidum fermentation. Compared with our previous results that, GA content was inhibited by polysaccharide elicitor isolated from T. melanosporum, while improved by the elicitor of polysaccharide and protein, protein was identified to be the exact component inducing GA biosynthesis in this work. G. lucidum cell growth was significantly inhibited by elicitor of polysaccharide and protein, and polysaccharide elicitor did not inhibit the cell growth. In this work, the remarkable inhibition on the cell growth was considerably eliminated under the elicitation of protein elicitor isolated from T. melanosporum. These suggested maybe the interaction of polysaccharide and protein components existed in the inhibition on the cell growth of G. lucidum. Not only GA content but also total GA accumulation obtained the highest values after the elicitation of protein elicitor. The maximal GA production of 260.5 ± 5.6 mg/L was 31.2% higher than the control. Under the elicitation of protein elicitor, the production of extracellular polysaccharide (EPS) and the content of intracellular polysaccharide (IPS) were also enhanced; however, total IPS accumulation was lower. GA biosynthesis was also significantly affected by the addition time of protein elicitor, whose optimal value was the culture of day 4.     

软骨多糖诱导小鼠S180细胞凋亡的作用机制

目的研究软骨多糖对S180荷瘤小鼠的作用,并探讨其抑瘤作用机制。方法采用小鼠肉瘤S180细胞建立动物腹水瘤模型,通过腹腔注射软骨多糖进行治疗,治疗期间抽取腹水瘤细胞进行细胞生物学分析。通过HE染色,流式细胞术、TUNEL法检测细胞形态学方面、细胞周期及凋亡率的变化情况;通过免疫荧光方法检测Fas、增殖细胞核抗原(PCNA)的表达情况。结果软骨多糖可以明显提高S180荷瘤小鼠的生存率,细胞形态学观察可见细胞出现细胞质浓缩、核固缩及凋亡小体等现象。软骨多糖作用后的S180细胞,其细胞周期被阻遏于G2/M期,Fas蛋白的表达水平于给药24 h后升高,增殖细胞核抗原PCNA表达下降。结论软骨多糖可能通过影响肿瘤细胞周期和Fas、PCNA蛋白的表达来诱导S180细胞凋亡,并显著抑制肿瘤细胞的生长,延长S180荷瘤小鼠的生存时间,研究证实动物软骨多糖具有潜在的药用价值。     

软骨多糖诱导MCF-7乳腺癌细胞凋亡的实验研究

研究软骨多糖诱导MCF-7乳腺癌细胞凋亡及其作用机理。方法:选用MCF-7人类乳腺癌细胞系体外培养,应用MTT法检测细胞生长抑制率,TUNEL法检测细胞凋亡率,HE染色法观察细胞形态学改变,流式细胞仪检测细胞周期的变化,免疫荧光方法检测BCL-2BAD及波形蛋白Vimentin的表达率。结果:软骨多糖对MCF-7细胞体外生长具有明显的抑制作用,且呈时间和浓度依赖性;软骨多糖可诱导MCF-7细胞发生凋亡并伴随有凋亡小体出现等形态学变化;软骨多糖促进BCL-2蛋白的表达水平下降,BAD表达水平上升,及Vimentin的降解。结论:软骨多糖能够在体外诱导MCF-7细胞凋亡,是一种新型的抗乳腺癌活性物质。     

Antitumor, genotoxicity and anticlastogenic activities of polysaccharide from Curcuma zedoaria

The antitumor effect of the partially purified polysaccharide from Curcuma zedoaria was studied in mice transplanted with sarcoma 180 cells. The polysaccharide fraction, CZ-1-III, at dose of 6.25 mg/kg/d showed 50% inhibition in solid tumor growth. When mice were injected with fractions, CZ-1 and CZ-1-III, at the dose of 100.0 mg/kg, 91.6% and 97.1% of tumor growth were inhibited, respectively, indicating that the cytotoxic effect of polysaccharide on sarcoma 180 cells increases upon increasing the amount of polysaccharide administered. To assess the genotoxicity of CZ-1-III fraction, several classical toxicological tests were performed. In Ames test, CZ-1-III did not show any transformation of revertant with or without S-9 metabolic activating system, indicating the lack of mutagenic effect of the compound. To assess clastogenic effect, micronucleus and chromosomal aberration assays were performed using Chinese hamster lung (CHL) fibroblast cells. However, up to 259.0 microg/ml concentration of CZ-1-III, neither micronucleus formation nor chromosomal aberration was induced regardless of the presence of S-9 metabolic activating system. Inhibition of CZ-1-III on micronucleus formation induced by mitomycin C was exhibited in a dose-dependent manner, maximally up to 52.0%. These results strongly suggest that CZ-1-III, the polysaccharide fraction from C. Zedoaria, decreases tumor size of mouse and prevents chromosomal mutation.     

Effect of fatty acids on the mycelial growth and polysaccharide formation by Ganoderma lucidum in shake flask cultures

Fatty acids were added into the media to investigate their effects on the mycelial growth and polysaccharide formation by Ganoderma lucidum. The experiments were carried out in freely suspended cultures or immobilized cultures using shake flasks. The results indicate that the extent of stimulation or inhibition were associated with the types and levels of fatty acids. Oleic acid at the level of 0.15 g/100 ml led to a significant increase in cell concentration from 0.20 to 0.46 g/100 ml in a suspended culture and palmitic acid was of great advantage to polysaccharide production. In contrast, linoleic acid (0.1 g/100 ml) drastically suppressed both mycelial growth and polysaccharide formation. In immobilized cultures with fatty acids, the stimulation of mycelial growth remained the same level, but the enhancement of polysaccharide production became less. In addition, the growth of G. lucidum in the pattern of immobilization might be beneficial to the production of mycelia and polysaccharide.     

Repair of wounded monolayers of cultured bovine aortic endothelial cells is inhibited by calcium spirulan,a novel sulfated polysaccharide isolated from Spirulina platensis

Calcium spirulan (Ca-SP) is a novel sulfated polysaccharide isolated from a blue-green alga Spirulina platensis. Ca-SP inhibits thrombin by activation of heparin cofactor II. Therefore, it could serve as an origin of anti-atherogenic medicines. Since maintenance of vascular endothelial cell monolayers is important for prevention of vascular lesions such as atherosclerosis, the effect of Ca-SP at 20 microg/ml or less on the repair of wounded bovine aortic endothelial cell monolayers in culture was investigated in the present study. When the monolayers were wounded and cultured in the presence of Ca-SP, the polysaccharide inhibited the appearance of the cells in the wounded area. The inhibition was also observed even when the repair was promoted by excess basic fibroblast growth factor, which is one of the autocrine growth factors that are involved in the endothelial cell monolayer maintenance. On the other hand, Ca-SP inhibited the cell growth and the incorporation of [3H]thymidine into the acid-insoluble fraction of proliferating endothelial cells, suggesting that Ca-SP inhibits endothelial cell proliferation. From these results, it is concluded that Ca-SP may retard the repair process of damaged vascular endothelium through inhibition of vascular endothelial cell proliferation by induction of a lower ability to respond to stimulation by endogenous basic fibroblast growth factor.     

Activation of T cells in tumor-bearing mice

Subcutaneous transplantation of the syngeneic P815 mastocytoma in DBA/2J mice induced an activation of splenic T cells which resulted in a hyperresponsiveness of the tumor-bearing animal to the unrelated antigens pneumococcal polysaccharide (Pn) and sheep red blood cells (SRBC). These tumor-activated T cells appeared to increase the plaque-forming cell (PFC) potential of suboptimal numbers of spleen cells, caused normal spleen cells to express increased numbers of PFC, and produced lymphokine(s) which also increased PFC responses of normal splenocytes. The tumor-activated T cells responsible for stimulating normal splenocytes in an in vitro antibody response were shown to be Ly+2- cells. The activity of the tumor-activated T-cell supernatants was not genetically restricted and required additional Ly1 T cells in order to induce rigorously clean B cells to produce antibody. The T cells capable of stimulating non-specific antibody responses were also capable of slowing tumor growth when injected with tumor cells in normal recipient mice. These results suggest that T cells activated by tumor antigens release immunostimulatory lymphokines and, at the same time, are capable of leading to inhibition of tumor growth.     

9R穿膜肽可增强P53抗肿瘤效果

为解决P53蛋白难以进入细胞内部发挥治疗作用的瓶颈难题.将p53基因融合插入带有9个精氨酸作为穿膜肽的表达载体中表达融合蛋白CPPs-P53,并与没有穿膜肽的P53蛋白进行比较,利用Western blotting方法检测蛋白的表达情况,MTT及Annexin V/PI双染法检测细胞生长抑制率及细胞凋亡率.Western blotting检测表明已成功在原核表达系统中表达融合蛋白CPPs-P53和P53蛋白,且蛋白纯度均已达到90％以上;MTT检测表明,P53蛋白对肿瘤细胞的生长虽有一定的抑制作用,但融合蛋白CPPs-P53与之相比,对肿瘤细胞生长的抑制效果显著增强,细胞生长抑制率有明显的提升,并且细胞生长抑制率呈现剂量依赖性;Annexin V/PI双染检测细胞凋亡情况也表明P53虽可以在一定程度上诱导肿瘤细胞的凋亡,但与P53蛋白相比较,融合蛋白CPPs-P53诱导的凋亡细胞明显增加,凋亡率是P53蛋白的2～3倍.由此说明在抑制肿瘤细胞的生长和诱导细胞凋亡方面,CPPs-P53比没有穿膜肽的P53蛋白的效果更显著.     

Yeast beta-glucan amplifies phagocyte killing of iC3b-opsonized tumor cells via complement receptor 3-Syk-phosphatidylinositol 3-kinase pathway

Anti-tumor mAbs hold promise for cancer therapy, but are relatively inefficient. Therefore, there is a need for agents that might amplify the effectiveness of these mAbs. One such agent is beta-glucan, a polysaccharide produced by fungi, yeast, and grains, but not mammalian cells. Beta-glucans are bound by C receptor 3 (CR3) and, in concert with target-associated complement fragment iC3b, elicit phagocytosis and killing of yeast. Beta-glucans may also promote killing of iC3b-opsonized tumor cells engendered by administration of anti-tumor mAbs. In this study, we report that tumor-bearing mice treated with a combination of beta-glucan and an anti-tumor mAb show almost complete cessation of tumor growth. This activity evidently derives from a 25-kDa fragment of beta-glucan released by macrophage processing of the parent polysaccharide. This fragment, but not parent beta-glucan, binds to neutrophil CR3, induces CBRM 1/5 neoepitope expression, and elicits CR3-dependent cytotoxicity. These events require phosphorylation of the tyrosine kinase, Syk, and consequent PI3K activation because beta-glucan-mediated CR3-dependent cytotoxicity is greatly decreased by inhibition of these signaling molecules. Thus, beta-glucan enhances tumor killing through a cascade of events, including in vivo macrophage cleavage of the polysaccharide, dual CR3 ligation, and CR3-Syk-PI3K signaling. These results are important inasmuch as beta-glucan, an agent without evident toxicity, may be used to amplify tumor cell killing and may open new opportunities in the immunotherapy of cancer.     

Human peripheral blood lymphocytes targeted with bispecific antibodies release cytokines that are essential for inhibiting tumor growth

We have compared the mechanisms by which human PBL targeted with bispecific antibodies either lyse tumor cells or block their growth in culture or in mice. We found that resting PBL were unable to mediate lysis, but were able to block tumor growth. Moreover, targeted PBL were unable to lyse bystander cells, whereas targeted PBL did block the growth of bystander tumor cells in culture and in nude mice. Supernatants from cultures of targeted PBL, or from PBL grown on anti-CD3-coated flasks, blocked the growth of tumor cells in the absence of added effector cells, and antibodies against TNF-alpha and IFN-gamma reversed the inhibition of tumor growth, but had no effect upon cytolysis mediated by targeted by PBL. Our results show that targeted human PBL mediate two different antitumor activities: lysis, which occurs rapidly and requires the direct attachment of the target cell to the cytotoxic cell, and tumor growth inhibition, which is mediated by cytokines released into the medium as a result of receptor cross-linking. The inhibition of bystander tumor growth in mice by targeted PBL suggests that factor release is sufficient to block tumor growth in vivo. Targeted factor release therefore provides a mechanism by which targeted PBL could block the growth of tumor cells in vivo that were not bound by the effector cells, but which were located in the vicinity of tumor cells that were bound.     

Consequences of selenite supplementation on the growth and metabolism of cultures of canine mammary cells

Previous studies with cultures of canine mammary cells revealed differences in the degree of growth inhibition caused by selenite supplementation, with canine mammary tumor cell line 13 > 11 > non-neoplastic canine mammary cells. The present studies show this variation in growth retardation cannot be explained by selenium retention. Intracellular glutathione related inversely to the degree of growth inhibition resulting from the addition of selenite. Dimethyl selenide formation by S-9 preparations corresponded to the sensitivity of the culture to supplemental selenite. DL-buthionine-SR-sulfoximine, a specific inhibitor of glutathione biosynthesis, accentuated the growth inhibition and prevented the increase in intracellular glutathione caused by supplemental selenite. Treatment of canine mammary tumor cell line 13 cultures with DL-buthionine-SR-sulfoximine resulted in a persistent depletion of intracellular glutathione without affecting growth. Glutathione reductase activity, before and following selenite, was inversely related to the degree of growth inhibition, with canine mammary tumor cell line 13 > 11 > non-neoplastic canine mammary tumor cell line. Selenite addition increased the activity of gamma-glutamylcysteine synthetase in canine mammary tumor cell line 11 and non-neoplastic canine mammary cells, but not in canine mammary tumor cell line 13 cells. The present data suggest the differences in the growth inhibition caused by selenite among these mammary cells is related to glutathione regulation and ultimately to selenium detoxification.     

An Apparent Carbohydrate-Amino Acid Interaction in Tetrahymena pyriformis

SYNOPSIS. Experiments were designed to examine the nature of the response of Tetrahymena pyriformis to inhibitory levels of L-serine when growing in defined media with carbohydrate as mono-, or polysaccharide. Growth curves indicated that, when a polysaccharide is being utilized, inhibition by serine affects at least 2 different loci. At one locus, inhibition causes a marked increase in the growth lag, at the other a significant decrease in the maximum rate of growth. Since the inhibition was completely reversible by glucose supplementation, it is evident that the initial inhibition, expressed as increased lag time, is specifically related to uptake or metabolism of the polysaccharide, i.e., it precedes glucose in the metabolic sequence. The inhibition expressed as decreased rate of maximum growth appears to be due to interference at some stage in the glycolytic pathway. The results suggest that in metabolizing a polysaccharide, T. pyriformis utilizes 2 mechanisms simultaneously. One involves phagocytic ingestion of molecular dextrin followed by phosphorylytic cleavage whereby the energy of the glycosidic bond is utilized to form glucose-1-phosphate. The 2nd mechanism depends upon elaboration of extracellular hydrolytic enzymes to cleave the polysaccharide to glucose, which enters the glycolytic pathway via glucose-6-phosphate in the usual manner.