淫羊藿素抑制外泌体介导的黑色素瘤肺转移及机制初探

本研究从体内外考察淫羊藿素(icaritin,ICT)对外泌体(exosomes,Exo)诱导的小鼠黑色素瘤B16BL6细胞肺转移的影响,并探讨其潜在分子机制.收集B16BL6细胞培养上清液,超速离心法提取Exo,使用透射电镜和Western blotting对Exo进行表征,BCA法对Exo总蛋白进行定量分析.细胞划...     

三七总皂苷对B16黑色素瘤生长及转移的作用

目的观察三七总皂苷（PNS）对B16黑色素瘤生长及转移的作用,及其对B16黑色素瘤表达缝隙连接蛋白Connexin32的影响。方法实验采用B16黑色素瘤自发性肺转移模型,来观察PNS对B16黑色素瘤生长及转移的影响。免疫组织化学检测Connexin32在黑色素瘤原发灶的表达情况。结果（1）PNS对黑色素瘤生长有较好的抑制作用,其中PNS高剂量组抑瘤率可达50．85％。（2）与模型组相比PNS中、高剂量组能有效抑制黑色素瘤的肺转移,转移灶数量与对照组相比有明显减少。（3）免疫组织化学检测,发现PNS各用药组均能增强黑色素瘤原发灶细胞膜上Connexin32的表达。结论PNS能够抑制B16黑色素瘤的生长和转移,并能有效增强肿瘤细胞膜上Connexin32的表达。     

Prevention of growth and metastasis of murine melanoma through enhanced natural-killer cytotoxicity by fatty acid-conjugate of protopanaxatriol

Ginsenosides, the glycosides of Panax ginseng, are metabolized (deglycosylated) by intestinal bacteria after oral administration. 20(S)-Protopanaxatriol (M4) is the main bacterial metabolite of protopanaxatriol-type ginsenosides and mediates their antitumor effects. To clarify the mechanism of the M4-mediated antitumor effect, the antitumor activity and metabolism of M4 was examined, using the C57BL/6 mice implanted with B16-BL6 melanoma. The chronic oral administration of M4 inhibited the growth of B16-BL6 melanoma at the implanted site. Analyses using TLC, HPLC, MS and NMR suggest that orally administered M4 was absorbed from the small intestine into the mesenteric lymphatics followed by the rapid esterification of M4 with fatty acids and its accumulation in the tissues including the liver and lung. The administration of M4 prior to the intravenous injection of B16-BL6 cells abrogated the enhanced lung metastasis in the mice pretreated with 2-chloroadenosine more effectively than in those pretreated with anti-asialo GM1. The esterified M4 (EM4) did not directly affect tumor growth in vitro, whereas it stimulated splenic NK cells to become cytotoxic to tumor cells. These results indicate that the antitumor activity of M4 is based on the NK cell-mediated tumor lysis enhanced by EM4.     

miR-126抑制结肠癌增殖及侵袭转移的功能研究

目的：研究 miR-126在体内是否具有抑制结肠癌细胞增殖及侵袭转移的功能。方法利用慢病毒载体构建稳定过表达miR-126的结肠癌细胞系 HCT116,将实验组及对照组细胞分别进行裸鼠皮下及尾静脉成瘤体内实验。结果成功构建稳定过表达 miR-126细胞系 HCT116;裸鼠皮下成瘤实验结果显示过表达 miR-126实验组皮下移植瘤瘤体平均体积明显小于其对照组瘤体体积（P ＜0．05）;尾静脉成瘤组中稳定过表达 miR-126实验组肺部转移灶的平均数目、面积均明显小于其对照组（P＜0．05）。结论裸鼠移植瘤实验证实 miR-126在体内具有抑制结肠癌细胞增殖及侵袭转移的作用。     

重组人纤连蛋白CH50对黑色素瘤生长及转移的影响

目的：研究重组人纤连蛋白ＣＨ５０对小鼠黑色素瘤生长的影响及其抗肿瘤机制。方法 进行小鼠动物实验及黑色素瘤Ｂ１６细胞实验。结果：ＣＨ５０在体内明显抑制黑色素瘤生长及实验性肺转移,ＣＨ５０在体外能附粘黑色素瘤Ｂ１６细胞,抑制Ｂ１６细胞粘附层粘蛋白并明显提高腹腔巨噬细胞对Ｂ１６细胞杀伤活性,结论：ＣＨ５０抑制小鼠黑色素瘤的生长和转移,ＣＨ５０的抗肿瘤机制与其粘附肿瘤细胞,提高巨噬细胞杀瘤性活性有关。     

Effect of recombinant human fibronectin polypeptide CH50 on growth and metastasis of melanoma 1

目的：研究重组人纤连蛋白ＣＨ５０对小鼠黑色素瘤生长的影响及其抗肿瘤机制．方法：进行小鼠动物实验及黑色素瘤Ｂ１６细胞实验．结果：ＣＨ５０在体内明显抑制黑色素瘤生长及实验性肺转移．ＣＨ５０在体外能粘附黑色素瘤Ｂ１６细胞,抑制Ｂ１６细胞粘附层粘蛋白并明显提高腹腔巨噬细胞对Ｂ１６细胞的杀伤活性．结论：ＣＨ５０抑制小鼠黑色素瘤的生长和转移,ＣＨ５０的抗肿瘤机制与其粘附肿瘤细胞,提高巨噬细胞杀瘤活性有关．     

新型表位基因疫苗的构建及对小鼠黑色素瘤的影响

目的：构建以MAGE-1（161—169）为表位的癌症基因疫苗并检测其抗小鼠黑色素瘤效果。方法：构建基因疫苗pcDNA—HSP70-MAGE—l（161-169）,并免疫C57BL／6小鼠。最后一次免疫后第2周,接种小鼠黑色素瘤细胞。于肿瘤细胞接种后14d,处死全部动物,称量肿瘤的重量。采用ELISA法对小鼠血清中抗MAGE-1-IgG类抗体及小鼠原代脾淋巴细胞IFN-7释放水平进行检测。结果：pcDNA-HSP70-MAGE-1（161—169）表位基因疫苗能够成功地诱发机体产生抗MAGE-1的特异性抗体,并能在体内起到抗小鼠黑色素瘤作用,抑瘤率为40．7％。同时还能提高约3．05倍的小鼠原代脾淋巴细胞IFN-7释放量。结论：pcDNA-HSP70-MAGE-1（161-169）有望成为有效的抗小鼠黑色素瘤基因疫苗。     

Suppression of in vivo tumor growth by using a biodegradable thermosensitive hydrogel polymer containing chemotherapeutic agent

Current systemic chemotherapy in the treatment of solid tumors inevitably induces various systemic adverse effects. Locally injected chemotherapy is expected to overcome this limitation of systemic therapy. We evaluated by luminescence imaging the effects of chemotherapy administered locally by means of a biodegradable thermosensitive hydrogel polymer. The human gastric cancer cell line HSC44Luc was used for tumor induction, and it was confirmed to be sensitive to doxorubicin by MTT assay. Cells were injected subcutaneously into Balb/c-nude mice. When the mean volume of tumor reached 400 mm³, we divided the mice into 6 groups (5 per group) according to treatment: 1) control (intratumor injection of PBS), 2) systemic injection of doxorubicin, 3) intratumor injection of polymer gel, 4) intratumor injection of polymer gel physically mixed with a low dose of doxorubicin, 5) intratumor injection of polymer gel physically mixed with a high dose of doxorubicin, 6) intratumor injection of conjugated polymer gel with doxorubicin. Body weight and tumor volume were measured every 2 or 3 days for 30 days after treatment. One mouse in each group was sacrificed for histopathologic examination every week. Reductions in body weight were not significantly different among groups. The relative rate of tumor growth was 774% in Group 1, 267% in Group 2, 813% in Group 3, -186% in Group 4, and 155% in Group 6, respectively. Thus the relative rate of tumor growth in the groups treated with polymer gel mixed with doxorubicin and the groups treated with conjugated polymer gel with doxorubicin were lower than that in the control group. Locally injectable chemotherapy using a thermosensitive hydrogel polymer with doxorubicin can suppress tumor growth effectively without severe systemic toxicity.     

Suppression of hyperemia and DNA oxidation by indomethacin in cerebral ischemia

We investigated antioxidative activity and the effect of indomethacin, an agent that inhibits cyclooxygenase, on extracellular glutamate and cerebral blood flow in cerebral ischemia in gerbils. Pre-ischemic administration of indomethacin (5 mg/kg, i.p.) significantly rescued hippocampal CA1 neurons (9+/-6 cells/mm in the ischemia, 87+/-43 cells/mm in the indomethacin group, P<0.001). DNA fragmentation induced by ischemia was also examined using the terminal deoxynucleotidyl transferase-mediated UTP nick end labeling (TUNEL) method and indomethacin reduced TUNEL positive cells (140+/-21 in the ischemia, 99+/-31 in the indomethacin group, P<0.01). In addition, indomethacin attenuated the increase in hippocampal blood flow during reperfusion, but not increased extracellular glutamate by ischemia. Eight-hydroxydeoxyguanosine (8-OH-dG), a highly sensitive marker of DNA oxidation, was measured 90 min following ischemia using high-pressure liquid chromatography. Indomethacin significantly decreased the level of ischemia-induced 8-OH-dG in the hippocampus (P<0.05). These results suggest that indomethacin may protect neurons by attenuating oxidative stress and reperfusion injury in ischemic insult.     

Development of transferrin-polycation/DNA based vectors for gene delivery to melanoma cells

We describe the comparison of non-viral polycation transfection reagents, adenovirus-enhanced transferrinfection (AVET), polyethylenimine (PEI800) and transferrin-conjugated PEI800 (Tf-PEI800) in their ability to transfect murine and primary human melanoma cell lines. Expression of a reporter gene, cell surface marker and secreted protein (interleukin-2) was assessed for each vector system. Testing for luciferase reporter gene expression in murine and primary human cell lines, AVET and Tf-PEI800, both showed high levels of expression and comparable activity. Furthermore, when the melanoma cell line B16F10 was transfected with a cell surface marker up to approximately 97% of the cells expressed the protein on the cell surface. Assessing the levels of secreted IL-2 in murine cell lines, AVET/IL-2, Tf-PEI800/IL-2 and PEI800/IL-2 all expressed high levels of the cytokine (up to 20 microg IL-2/10(6) cells/24 h). In primary human melanoma cell lines, AVET/IL-2 transfected cells secreted more IL-2 than cells transfected with either Tf-PEI800/IL-2 or PEI800/IL-2. In murine melanoma cell culture experiments, positively charged PEI800/DNA and Tf-PEI800/DNA complexes gave similar transfection efficiencies. However, when subcutaneous tumors in mice were injected with the luciferase reporter gene complexed with either Tf-PEI800 or AVET, higher transfection activity was measured in the tumors as compared to ligand free PEI800/DNA complexes.     

Suppressive effects of young radish cultivated with sulfur on growth and metastasis of B16-F10 melanoma cells

The oral administration of extracts of young radishes cultivated with sulfur after intravenous tumor cell injection achieved a marked reduction of pulmonary colonization in mice. Treatment of the mice with extracts of young radish cultivated with sulfur did not show any increase in the number of CD8+ or NK T cells in the spleen, indicating no influence on host immunity. Sulforaphane, which could be a candidate for an active compound from young radishes cultivated with sulfur, inhibited cell growth of B16-F10 melanoma cells. In addition, extracts of the young radish cultivated with sulfur-fed group showed enhanced quinine reductase (QR) activities in the liver and lung and a slight increase of glutathione S-transferase (GST) activity in the liver. These results suggested that the administration of extracts of young radishes cultivated with sulfur suppressed pulmonary tumorigenesis, possibly due to increased activity of detoxification enzymes in the liver and lung, and partly due to cell cytotoxicity.     

Angiogenesis and metastasis inhibitors for the treatment of malignant melanoma

Malignant melanoma is one of the most highly invasive and metastatic tumors. Melanoma is an increasingly common malignancy as well, and its mortality rates have been rapidly increasing above those of any other cancer in recent years. Surgical resection and systemic chemotherapy are the main therapeutic strategies for the treatment of malignant melanoma. However, these approaches are insufficiently effective and may be associated with significant adverse effects. Angiogenesis, a process by which new vascular networks are formed from pre-existing capillaries, is required for tumors to grow, invade and metastasize. Tumor vessels are genetically stable, and less likely to accumulate mutations that allow them to develop drug resistance in a rapid manner. Therefore, targeting vasculatures that support tumor growth, rather than cancer cells, is considered the most promising approach to malignant melanoma therapy. Now, novel anti-angiogenic agents with tolerable side effects is actually desired for the treatment of patients with malignant melanoma. In this paper, we review the current understanding of anti-angiogenic therapy for malignant melanoma, especially focusing on pigment epithelium-derived factor (PEDF), which was recently identified as the most potent endogenous inhibitor of angiogenesis in the mammalian eye. We also discuss here the involvement of a receptor for advanced glycation end products (RAGE) in angiogenesis, melanoma growth and metastasis, and the therapeutic implications of the blockers of RAGE in this devastating disorder.     

Suppression of lipid hydroperoxide-induced oxidative damage to cellular DNA by esculetin

Linoleic acid hydroperoxide (LOOH) has been reported to cause an increase in the content of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), a typical oxidation product of DNA bases, in cultured cells due to coexisting iron(III) ion. We examined whether coumarins are able to suppress the formation of 8-oxodG in the DNA of human diploid fibroblasts, TIG-7 cells, treated with LOOH and iron(III) ion. Cotreatment of TIG-7 cells with esculetin (6,7-dihydroxycoumarin) significantly suppressed the increase in 8-oxodG content induced by LOOH and iron(III) ion. Pretreatment of cells with esculetin for 24 h was also effective in protecting cellular DNA against oxidative damage induced by subsequent treatment with LOOH and iron(III) ion. Pretreatment with esculin, the 6-glucoside of esculetin, was effective, but to a lesser extent. Furthermore, the free radical-scavenging activities of coumarins and hydroxycinnamic acids were examined by measuring the inhibition of spin-adduct formation of hydroxyl radicals with 5,5-dimethyl-1-pyrroline N-oxide (DMPO). Compounds bearing an ortho-catechol moiety, such as esculetin, fraxetin, and caffeic acid, significantly reduced the ESR signal intensities of the DMPO-OH spin adduct. These results indicate that esculetin is effective in protecting cells against DNA damage induced by oxidative stress and that the presence of an ortho-catechol moiety is important for antioxidant activities against reactive oxygen species.     

Acidic polysaccharide from Phellinus linteus inhibits melanoma cell metastasis by blocking cell adhesion and invasion

The acidic polysaccharide (PL) from Phellinus linteus is an immunostimulator that has therapeutic activity against cancers. Here, we show that PL markedly inhibits melanoma cell metastasis in mice, and report that PL directly inhibits cancer cell adhesion to and invasion through the extracellular matrix, but that it has no direct effect on cancer cell growth. In addition, we found that PL increased macrophage NO production. These results suggest that PL has two antimetastatic functions, i.e., it acts as an immunopotentiator and as a direct inhibitor of cancer cell adhesion.     

The inhibition of cell proliferation using silencing of N-cadherin gene by siRNA process in human melanoma cell lines

Malignant melanoma is a disease with high mortality rate caused by rapid metastasis. Cell motility is physically and biochemically restricted by cadherin-mediated cell interactions and signalling pathways, and alterations in cadherin expression strongly correlate with E to N-cadherin switch as well as the metastasis and progression of tumours. Contrary to E-cadherin, N-cadherin plays an important role in stimulating processes of cell division, migration, differentiation and death. In this study we investigated the role of N-cadherin in proliferation and AKT, ERK, beta-catenin signalling pathway in human melanoma cells: WM793(VGP), WM115(VGP) from the primary tumor site, as well as Lu1205(lung) and WM266-4(skin) from metastatic sites. N-cadherin, pAKT(S473), β-catenin, pERK1/2(T202/Y204), cyclin D1, cyclin D3, cyclin-dependent kinases CDK4, CDK6, and p15, p16, p21, p27 inhibitors expression was determined by western blot analysis. The study on proliferation of cells was performed with the use of BrdU incorporation and crystal violet staining assays. Knock-out of N-cadherin gene expression by siRNA process reduced the expression of: pAKT(S473), pERK1/2(T202/Y204), betacatenin, cyclin D1, cyclin D3, cyclin-dependent kinases CDK4, CDK6 while increasing expression of cell cycle inhibitors p21 and p27, and significantly decreased cell proliferation (50-70%). The collected data indicate that N-cadherin mediates the effect of cell cycle in G1 phase by AKT, β-catenin, and ERK signalling pathway. These results suggest that increased expression of N-cadherin significantly contributes to the increased invasive potential of melanoma cells. Silencing of N-cadherin arrests cell growth at G1 phase and inhibits the entry into S-phase which is of great importance as to its possible future use in cancer treatment.     

Characterization of calcium phosphate as a gene carrier (II): Zeta potential and DNA transfection

The pH of the transfection medium has been shown to be crucial for the calcium phosphate (CaP_i)-mediated DNA transfection. This study was undertaken in an attempt to examine several physicochemical properties associated with the pH change as related to DNA transfection efficiency. The zeta potential, flocculation coefficient, and adsorption kinetics of [³H]DNA-CaP_i complexes onto FR3T3 cells were experimentally examined as a function of pH of the Hepes-buffered saline (HBS) in which the coprecipitates were formed, which were then correlated with the DNA transfection efficiency. ³H-labeled plasmid DNA was found to be adsorbed on the flocculated CaP_i particles for the HBS pH greater than 6.16. Adsorption of CaP_i—DNA complexes onto the cell surfaces renders the cell surface charge less negative. Both zeta potentials and the flocculation coefficients of the CaP_i—DNA coprecipitates were shown to vary with pH of the system, but no significant difference in the kinetics of adsorption was observed for the CaP_i—DNA coprecipitates prepared at various pH. Zeta potentials of the CaP_i—DNA coprecipitates lying between 11 and 21 mV were determined to be efficient for the CaP_i—DNA complexes to be effectively internalized by the cells. The pH appears to be a determinant factor in the properties studied. The physicochemical properties of the CaP_i—DNA complexes play important roles in the interaction between CaP_i—DNA complexes and cells, which consequently affect the cell transformation efficiency.     

A recombinant peptide, hirudin, potentiates the inhibitory effects of stealthy liposomal vinblastine on the growth and metastasis of melanoma

The metastasis of tumor cells is one of the major obstacles to successful clinical therapy. A treatment strategy by incorporating a specific inhibitor of thrombin, recombinant hirudin with stealthy liposomal vinblastine, was used in this study for inhibiting the metastasis of tumor cells and enhancing the efficacy of anti-tumor agents. In vitro cytotoxicity, cell adhesion to extracellular matrix (ECM) proteins, and cell invasion and migration assays were performed on human A375 melanoma cell line. In vivo measurement of coagulation parameters, inhibition of tumor growth, and inhibition of metastasis were assessed in female BALB/c mice. In vitro, vinblastine or stealthy liposomal vinblastine alone was effective to inhibit the growth of A375 cells. On the contrary, hirudin had no influence on either cytotoxicity when treating with hirudin alone or hirudin plus vinblastine. In addition, in vitro results showed that hirudin had no impact on the adhesion of tumor cells to extracellular matrix proteins, and metastasis and invasion of tumor cells. In mice, hirudin significantly inhibited the activity of thrombin. Furthermore, administered at the initial implantation of murine B16 melanoma cells, hirudin evidently delayed the growth of tumor, and depressed the occurrence of experimental lung metastasis. A subsequent administration of stealthy liposomal vinblastine resulted in further inhibiting growth and metastasis of tumor, indicating that hirudin plus stealthy liposomal vinblastine exhibited a significant anti-metastasis effect and slightly potent effect against tumor growth as compared with stealthy liposomal vinblastine alone. In conclusion, administration of recombinant hirudin followed by giving stealthy liposomal vinblastine may be beneficial for inhibiting the growth and metastasis of melanoma in vivo. The likely mechanism could be associated with inhibition of thrombin after administration of hirudin.     

Suppression of BK virus replication and cytopathic effect by inhibitors of prokaryotic DNA gyrase

Nalidixic acid and oxolinic acid, two antibacterial agents known to inhibit bacterial DNA gyrase, are shown to suppress the replication, as well as the cytopathic effect, of BK virus in Vero cell cultures. The inhibition of virus replication was detectable at day 4 post infection in cultures which had been continuously exposed to drugs at concentrations as low as 0.02 to 0.04 mM of nalidixic acid and 0.2 mM of oxolinic acid. These active concentrations are inferior to plasma levels attained in the course of clinical use of the drugs for antibacterial chemotherapy. Also, under these circumstances, no cytotoxicity occurred. The inhibition of development of cytopathology and of virus-induced cell death was demonstrable in cultures treated for 12 days with the drugs. Under these circumstances of prolonged action, oxolinic acid proved to be slightly cytotoxic in that virus inhibitory doses reduced the viability of normal cells. No alterations in the topological conformation of the viral genome or accumulation of end products of viral DNA replication were detected. However, accumulation of viral DNA form I at 48 h post infection suggests that the drugs act through a mechanism involving DNA topoisomerase.