Inhibition of cytokine-induced microvascular arrest of tumor cells by recombinant endostatin prevents experimental hepatic melanoma metastasis

We investigated effects of endostatin (ES) in the prometastatic microenvironment of inflammation occurring during the microvascular phase of cancer cell infiltration in the liver. We used a model of intrasplenic injection of B16 melanoma (B16M) cells leading to hepatic metastasis through vascular cell adhesion molecule-(VCAM-1)-mediated capillary arrest of cancer cells via interleukin-18 (IL-18)-dependent mechanism. We show that administration of 50 mg/kg recombinant human (rh) ES 30 min before B16M, plus repetition of same dose for 3 additional days decreased metastasis number by 60%. A single dose of rhES before B16M injection reduced hepatic microvascular retention of luciferase-transfected B16M by 40% and inhibited hepatic production of tumor necrosis factor alpha (TNF-alpha) and IL-18 and VCAM-1 expression by hepatic sinusoidal endothelia (HSE). Consistent with these data, rhES inhibited VCAM-1-dependent B16M cell adhesion to primary cultured HSE receiving B16M conditioned medium, and it abolished the HSE cell production of TNF-alpha and IL-18 induced by tumor-derived vascular endothelial cell growth factor (VEGF). rhES abrogated recombinant murine VEGF-induced tyrosine phosphorylation of KDR/flk-1 receptor in HSE cells, preventing the proinflammatory action of tumor-derived VEGF on HSE. rhES also abolished hepatic production of TNF-alpha, microvascular retention of luciferase-transfected B16M, and adhesion of B16M cells to isolated HSE cells, all of them induced in mice given 5 micro g/kg recombinant murine VEGF for 18 h. This capillary inflammation-deactivating capability constitutes a nonantiangiogenic antitumoral action of endostatin that decreases cancer cell arrest within liver microvasculature and prevents metastases promoted by proinflammatory cytokines induced by VEGF.     

Inhibition of b16 melanoma metastasis by administration of g(m3)- or gg3- liposomes - blocking adhesion of melanoma-cells to endothelial-cells (antiadhesion therapy) via inhibition of g(m3)-gg3cer or g(m3)-laccer interaction

Tumor cell (TC) metastasis is initiated by selective adhesion of TCs to target structures such as basement membrane and endotheliaI cells (ECs), followed by transvascular migration of TCs. Variants of murine B16 melanoma having different metastatic potentials (in the order BL6 greater than or equal to F10>F1>WA4) have been characterized by the same decreasing order of cell surface G(M3) expression level, relative adhesiveness to nonactivated ECs, and relative degree of G(M3)-dependent adhesion to Gg3Cer- or LacCer-coated plates. Degree of integrin-dependent cell adhesion and adhesion to IL-1-activated ECs was similar for BL6, F10, and F1. These results suggest that metastatic potential of these B16 variants is closely dependent on relative adhesion to nonactivated ECs, which is based on G(M3)-Gg3Cer or G(M3)-LacCer interaction. This possibility has been supported by further studies showing that blocking of G(M3)-dependent melanoma adhesion by mu M-order concentrations of G(M3) or Gg3Cer in liposomes, or by sialidase treatment of melanoma cells, strongly inhibited BL6 metastasis to lung. Paragloboside or sialylparagloboside did not affect G(M3)-dependent BL6 cell adhesion and did not inhibit metastasis. Spontaneous metastasis from subcutaneously-grown tumors was significantly reduced if G(M3)- or Gg3Cer-liposomes were intravenously injected during tumor growth. Thus, blocking of TC adhesion to nonactivated ECs based on carbohydrate-carbohydrate interaction may provide effective anti-adhesion therapy against tumor progression, in analogy to the antimetastatic effect produced by blocking of integrin-dependent cell adhesion.     

Association between pterostilbene and quercetin inhibits metastatic activity of B16 melanoma

Inhibition of cancer growth by resveratrol (trans-3,5,4'-trihydroxystilbene; RESV), a phytoalexin present in many plant species, is limited by its low bioavailability. Pterostilbene (3,5-dimethoxy-4'-hydroxystilbene; PTER) and quercetin (3,3',4',5,6-pentahydroxyflavone; QUER), two structurally related and naturally occurring small polyphenols, show longer half-life in vivo. In vitro growth of highly malignant B16 melanoma F10 cells (B16M-F10) is inhibited (56%) by short-time exposure (60 min/day) to PTER (40 microm) and QUER (20 microm) (approximate mean values of plasma concentrations measured within the first hour after intravenous administration of 20 mg/kg each polyphenol). Intravenous administration of PTER and QUER (20 mg/kg per day) to mice inhibits (73%) metastatic growth of B16M-F10 cell in the liver, a common site for metastasis development. The anti-metastatic mechanism involves: 1) a PTER-induced inhibition of vascular adhesion molecule 1 expression in the hepatic sinusoidal endothelium, which consequently decreases B16M-F10 cell adhesion to the endothelium through very late activation antigen 4; and 2) a QUER- and PTER-induced inhibition of Bcl-2 expression in metastatic cells, which sensitizes them to vascular endothelium-induced cytotoxicity. Our findings demonstrate that the association of PTER and QUER inhibits metastatic melanoma growth and extends host survival.     

Enhancement role of host 12/15-lipoxygenase in melanoma progression

12/15-Lipoxygenase (12/15-LOX) is a non-haeme iron-containing dioxygenase that forms 12(S)-hydroxyeicosatetraenoic acid (12(S)-HETE) or 15(S)-HETE. Several biological mediators including cytokines, growth factors and lipid metabolites released during tumour cell-endothelial cell adhesion are associated with malignant tumour progression. Here we found that HETEs released from the host organ played a critical role in tumour metastasis. Intravenous injection of B16F10 melanoma cells caused lung nodule formation, which was markedly attenuated in 12/15-LOX null mice. Co-injection of melanoma cells with 12(S)-HETE increased the lung homing activity of B16F10 melanoma cells. In vitro studies showed that 12(S)-HETE and 15(S)-HETE treatment resulted in a concentration-dependent increase of adhesion of B16F10 cells on collagen or fibronectin. The melanoma cell adhesion was then evaluated in pulmonary primary cell culture isolated from wild-type (WT) and 12/15-LOX knockout (KO) mice. It was found that the adhesion of melanoma cells on the epithelial cells isolated from 12/15-LOX null mice was reduced in comparison with those isolated from WT mice. Treatment of 12(S)-HETE increased the pFAK in melanoma cells adhering on collagen-coated slide. The enhancement of adherence elicited by 12(S)-HETE in B16F10 cells could be antagonised by focal adhesion kinase (FAK) inhibitor 14 (FAK inhibitor) or PD98059 (extracellular signal-regulated kinase (ERK) inhibitor). 12(S)-HETE increased the phosphorylation of FAK and ERK in adhering melanoma cells. The FAK phosphorylation induced by 12(S)-HETE was further inhibited by PD98059, indicating that FAK is the downstream target of ERK. The adhesion and lung metastasis of human melanoma cells of C32 in NOD/SCID mice were also potentiated by co-treatment with 12(S)-HETE. These results demonstrate that 12(S)-HETE/15(S)-HETE activates ERK and FAK signalling pathways, thereby upregulates the adhesion and metastatic potential of melanoma cells. The endogenous release of 12(S)-HETE/15(S)-HETE in the host organ may affect the metastatic potential of melanoma.     

苦参碱衍生物M19对于肿瘤细胞转移的抑制作用

目的:探讨苦参碱衍生物M19对于肝细胞癌和黑色素瘤细胞转移的抑制作用。方法:肝癌细胞Hep3B、MHCC-LM3和黑色素瘤细胞B16F10经M19处理后,检测肿瘤细胞体外迁移能力。建立C57BL/6小鼠黑色素瘤B16F10和裸鼠肝细胞癌MHCC-LM3转移模型,经M19体内给药后,观察肿瘤细胞肝、肺转移情况。结果:M19能浓度依赖性地抑制肝癌细胞和黑色素瘤细胞迁移。M19体内给药使B16F10细胞在小鼠肺的转移减少,且还能抑制MHCC-LM3细胞在裸鼠肺和肝的转移。结论:M19能在体内外抑制肝细胞癌和黑色素瘤细胞的转移。     

Influence of tumor-derived interleukin 1 on melanoma-endothelial cell interactions in vitro.

Human melanoma cell lines that express high constitutive levels of the metastasis-associated marker intercellular adhesion molecule 1 (ICAM-1) were found to secrete interleukin 1 (IL-1) in vitro. Experiments with neutralizing antibodies showed that this cytokine was responsible for their expression of ICAM-1 but not that of two other progression/metastasis markers, Muc-18 and Gp IIb/IIIa. The IL-1 present in melanoma-conditioned medium induced the expression of vascular cell adhesion molecule 1, endothelial-leukocyte adhesion molecule 1, and ICAM-1 on human umbilical vein endothelial cells (ECs) in culture and increased the rate at which melanoma cells and ECs adhered to each other. IL-1-producing melanoma lines adhered significantly more rapidly to ECs than did non-IL-1-producing lines, and this enhancement was reduced by prior incubation of the melanoma cells with neutralizing anti-IL-1 antibodies. Similarly, endothelial cells treated with conditioned medium from IL-1-producing melanoma lines adhered significantly more rapidly to melanoma cells than did ECs treated with medium from non-IL-1-producing melanoma lines, and this enhancement was abolished by addition of anti-IL-1 antibodies to EC cultures in conditioned medium. Blocking antibodies to endothelial vascular cell adhesion molecule 1, endothelial-leukocyte adhesion molecule 1, and ICAM-1 failed to inhibit melanoma-EC adhesion, but an antibody to tumor cell GpIIb/IIIa did block adhesion by up to 44%. The ability to secrete IL-1 could increase the metastatic potential of melanoma cells by stimulating tumor cell-EC adhesion.     

Cellular adhesion pathways and metastatic potential of human melanoma

Cellular adhesion molecules of the cadherin, integrin, and immunoglobulin superfamilies are important to both growth and metastasis of many cancers, including malignant melanoma. Malignant melanoma is an excellent model for studying these molecules, due in part to a sequential series of five defineable stages. As the malignant phenotype of melanoma cells changes from the noninvasive radial growth phase to the vertical growth phase, which has high metastatic potential, so does the repertoire of the cellular adhesion molecules expressed on the cells surface. The cellular adhesion molecule MCAM/MUC18 confers metastatic potential and increased tumorigenicity to melanoma cells. MCAM/MUC18 mediates homotypic and heterotypic adhesion between melanoma cells and endothelial cells, respectively. Both types of interaction may promote metastasis at different stages in the metastasis cascade. We developed a fully humanized antibody to MCAM/MUC18 (ABX-MA1) that blocked melanoma metastasis in vivo. Furthermore, ABX-MA1 blocked the homotypic interaction between melanoma cells and endothelial cells as well as the promoter and collagenase activity of MMP-2. During melanoma progression the loss of E-cadherin expression disrupts normal homeostasis in the skin by freeing melanoma cells from structural and functional regulation by keratinocytes. The loss of functional E-cadherin is parallelled by a gain in N-cadherin function that mediates homotypic interaction between melanoma cells, facilitates gap-junctional formation with fibroblasts and endothelial cells and promotes melanoma cell migration and survival. In addition, loss of E-cadherin may affect the beta-catenin/wnt signaling pathways, resulting in deregulation of genes involved in growth and metastasis. The integrin family member alpha(v)beta(3) is widely expressed on melanoma cells in the vertical growth phase. When alpha(v)beta(3) is expressed in melanoma cells in the radial growth phase, this integrin is associated with increased tumor growth in vivo. alpha(v)beta(3) may also promote melanoma invasion, through an interaction with MMP-2, and transendothelial migration, via a heterotypic melanomaendothelial cell interaction. This review summarizes recent knowledge on how changes in these adhesion molecules contribute to the acquisition of the metastatic phenotype in human melanoma.     

Suppression of growth and hepatic metastasis of murine B16FO melanoma cells by a novel nutrient mixture

Highly metastatic melanoma is resistant to existing therapies. Our main objective was to investigate the effect of a nutrient mixture (NM) on B16FO tumor growth and hepatic metastasis. Tumor growth was studied in athymic nude male mice, 5-6 weeks old, inoculated with 10(6) B16FO melanoma cells subcutaneously and fed either a regular diet or one supplemented with 0.5% NM. Four weeks later, the mice were sacrificed and their tumors excised, weighed and processed for histology. Metastasis was studied in C57BL/6 mice, which received 10(6) B16FO melanoma cells by intrasplenic injection, as well as a regular or 0.5% NM-supplemented diet for 2 weeks. Survival was studied in C57BL/6 mice receiving 10(6) B16FO melanoma cells intraperitoneally (i.p.) followed by the regular, NM-supplemented, or regular diet in addition to being administered with 2 mg NM injection 3 times per week. NM inhibited the growth of B16FO melanoma cells by 50%. Lesions in the two groups were consistent with malignant melanoma. Mice were injected with B16FO cells in the spleen. Those fed the regular diet developed large black spleens and livers indicating growth in the spleen and metastasis to the liver. In contrast, mice supplemented with NM showed less growth in spleen, but also reduced metastasis to the liver. The survival time of mice receiving NM supplementation and B16FO cells i.p. was greater than in mice which were fed the regular diet. To confirm effects in vivo, we investigated the effect of NM on murine B16FO melanoma cells in vitro, including cell proliferation by MTT assay, morphology by hematoxylin and eosin (H&E) staining and apoptosis using live green caspase detection kit. In vitro, NM was not toxic at 100 microg/ml concentration, but exhibited 44% toxicity over the control at 500 and 1000 microg/ml. H&E did not indicate any changes up to 100 microg/ml. NM induced slight apoptosis at 100 microg/ml, moderate at 500 and extensive at 1000 microg/ml concentration.     

Natural killer T cell ligand alpha-galactosylceramide inhibited lymph node metastasis of highly metastatic melanoma cells.

The role of natural killer T (NKT) cells in the prevention of multiple tumor metastasis was examined. The i.v. inoculation of a highly metastatic subline of B16-BL6 (B16-BL6-HM) melanoma cells resulted in the formation of metastatic nodules in lymph nodes in addition to lung, intrapleural cavity, and ovary. However, treatment of the mice with the NKT cell ligand alpha-galactosylceramide (alpha-GalCer) three times from 1 day after B16-BL6-HM melanoma inoculation caused a significant inhibition of multiple metastasis. Lymph node metastasis of B16-BL6-HM was almost completely blocked by alpha-GalCer treatment. This antimetastatic effect of alpha-GalCer was abolished in NKT cell-deficient mice. These results suggest that alpha-GalCer-activated NKT cells played a critical role in the prevention of lymph node metastasis of melanoma cells.     

Gene silencing of beta-catenin in melanoma cells retards their growth but promotes the formation of pulmonary metastasis in mice

Altered expression of beta-catenin, a key component of the Wnt signaling pathway, is involved in a variety of cancers because increased levels of beta-catenin protein are frequently associated with enhanced cellular proliferation. Although our previous study demonstrated that gene silencing of beta-catenin in melanoma B16-BL6 cells by plasmid DNA (pDNA) expressing short-hairpin RNA targeting the gene (pshbeta-catenin) markedly suppressed their growth in vivo, gene silencing of beta-catenin could promote tumor metastasis by the rearranging cell adhesion complex. In this study, we investigated how silencing of beta-catenin affects metastatic aspects of melanoma cells. Transfection of B16-BL6 cells with pshbeta-catenin significantly reduced the amount of cadherin protein, a cell adhesion molecule binding to beta-catenin, with little change in its mRNA level. Cadherin-derived fragments were detected in culture media of B16-BL6 cells transfected with pshbeta-catenin, suggesting that cadherin is shed from the cell surface when the expression of beta-catenin is reduced. The mobility of B16-BL6 cells transfected with pshbeta-catenin was greater than that of cells transfected with any of the control pDNAs. B16-BL6 cells stably transfected with pshbeta-catenin (B16/pshbeta-catenin) formed less or an equal number of tumor nodules in the lung than cells stably transfected with other plasmids when injected into mice via the tail vein. However, when subcutaneously inoculated, B16/pshbeta-catenin cells formed more nodules in the lung than the other stably transfected cells. These results raise concerns about the gene silencing of beta-catenin for inhibiting tumor growth, because it promotes tumor metastasis by reducing the amount of cadherin in tumor cells.     

Natural Killer T Cell Ligand α-Galactosylceramide Inhibited Lymph Node Metastasis of Highly Metastatic Melanoma Cells

The role of natural killer T (NKT) cells in the prevention of multiple tumor metastasis was examined. The i.v. inoculation of a highly metastatic subline of B16-BL6 (B16-BL6-HM) melanoma cells resulted in the formation of metastatic nodules in lymph nodes in addition to lung, intrapleural cavity, and ovary. However, treatment of the mice with the NKT cell ligand α-galactosylceramide (α-GalCer) three times from 1 day after B16-BL6-HM melanoma inoculation caused a significant inhibition of multiple metastasis. Lymph node metastasis of B16-BL6-HM was almost completely blocked by α-GalCer treatment. This antimetastatic effect of α-GalCer was abolished in NKT celldeficient mice. These results suggest that α-GalCer-activated NKT cells played a critical role in the prevention of lymph node metastasis of melanoma cells.     

Inhibition of tumor metastasis by adoptive transfer of IL-12-activated Valpha14 NKT cells

A unique lymphocyte lineage, the Valpha14 NKT cells, expresses both NK1.1 and an invariant antigen receptor encoded by Valpha14 and Jalpha281 gene segments. Valpha14 NKT cells play crucial roles in various immune responses, including autoimmune diseases, allergic reactions and anti-tumor immunity. Valpha14 NKT cells were demonstrated to be essential for anti-tumor effect of IL-12 in vivo. Here, we report that adoptive transfer of IL-12-activated Valpha14 NKT cells prevents hepatic metastasis of B16 melanoma. The injection of large amounts of IL-2, IL-4, and IFN-gamma, which are cytokines produced by activated Valpha14 NKT cells, exhibited no significant inhibition of the metastasis of this melanoma. The cells prepared from the liver of IL-12-injected mice expressed a potent cytotoxic activity on B16 melanoma cells in vitro. Although the adoptive transfer of IL-12-activated Valpha14 NKT cells prevents hepatic metastasis of B16 melanoma, activated NK cells from IL-12-injected RAG-1-/- mice failed to inhibit the metastasis of this melanoma. Thus, the anti-tumor effect of IL-12 can be replaced by adoptive transfer of IL-12-activated Valpha14 NKT cells but not by IL-12-activated NK cells, suggesting a minor role of NK cells for the IL-12-mediated anti-tumor effect in this experimental system. Moreover, our studies have suggested the involvement of direct cytotoxic mechanisms rather than cytokine-mediated immune responses at the effector phase of the Valpha14 NKT cell-mediated anti-tumor activity.     

Transgenic expression of IL-33 activates CD8 T cells and NK cells and inhibits tumor growth and metastasis in mice

IL-33 is a multifunctional cytokine in immune regulation that activates Th1 cells, Th2 cells, CD8⁺ T cells and NK cells. Our study showed that transgenic expression of IL-33 attenuated tumor metastasis in the B16 melanoma and Lewis lung carcinoma (LLC) metastatic models. The percentages and cytotoxicity of CD8⁺ T cells and NK cells and their infiltration into the tumor tissues were significantly increased by the transgenic expression of IL-33 in tumor-bearing mice. Treatment with recombinant IL-33 could also increase the cytotoxicity of CD8⁺ T cells and NK cells in vitro. In addition, depletion of CD8⁺ T cells and NK cells using anti-CD8 or anti-asialo GM1 antibody abolished the pulmonary metastasis inhibition mediated by IL-33. Furthermore, IL-33 stimulated the activation of NF-κB and increased CD69 expression, which is a marker of the activated form of the two cell subsets, in CD8⁺ T cells and NK cells. Our results suggest that IL-33 stimulated NF-κB signaling and promoted the proliferation, activation and infiltration of CD8⁺ T cells and NK cells, which resulted in the inhibition of pulmonary metastasis in B16 melanoma and LLC mice models.     

A novel function of junctional adhesion molecule-C in mediating melanoma cell metastasis

Hematogenous dissemination of melanoma is a life-threatening complication of this malignant tumor. Here, we identified junctional adhesion molecule-C (JAM-C) as a novel player in melanoma metastasis to the lung. JAM-C expression was identified in human and murine melanoma cell lines, in human malignant melanoma, as well as in metastatic melanoma including melanoma lung metastasis. JAM-C expressed on both murine B16 melanoma cells as well as on endothelial cells promoted the transendothelial migration of the melanoma cells. We generated mice with inactivation of JAM-C. JAM-C(-/-) mice as well as endothelial-specific JAM-C-deficient mice displayed significantly decreased B16 melanoma cell metastasis to the lung, whereas treatment of mice with soluble JAM-C prevented melanoma lung metastasis. Together, JAM-C represents a novel therapeutic target for melanoma metastasis.     

Enhanced suppression of pulmonary metastasis of malignant melanoma cells by combined administration of alpha-galactosylceramide and interleukin-18

α-Galactosylceramide (α-GalCer) shows antitumor effects by activating natural killer (NK) cells indirectly through stimulation of the secretion of cytokines by NKT cells, whereas interleukin (IL)-18 shows antitumor effects by activating NK cells directly. In the present study, we examined the antitumor effect of the combined administration of α-GalCer and IL-18. An injection of NK cell-sensitive mouse B16 melanoma cells into a mouse tail vein produced pulmonary metastasis. The daily administration of α-GalCer or IL-18 alone for 4 days starting 1 day after the injection of B16 melanoma cells markedly suppressed the number of pulmonary metastatic foci, and their combined administration enhanced the antitumor effect compared with single administration. The antitumor effect of their combined administration was completely abolished by treatment of mice with anti-asialo GM1 serum, which depletes NK cells but not NKT cells. Combined administration of α-GalCer and IL-18 enhanced the cytotoxicity of NK cells and increased the number of NK cells in the lung. Analysis of NKT cell-dependent and NK cell-independent secretion of cytokines, to which NK cells can respond, showed that the administration of α-GalCer increased the secretion of IL-2, IL-4, interferon-γ, IL-12, granulocyte-macrophage colony-stimulating factor, tumor necrosis factor-α, and IL-10, and the combined administration of α-GalCer and IL-18 enhanced the secretion of IL-2, IL-4, interferon-γ, and granulocyte-macrophage colony-stimulating factor further but only slightly. These results show that IL-18 in combination with α-GalCer exerts an antitumor effect on NK cell-sensitive tumors primarily by the direct stimulation of NK cells by IL-18 and the indirect stimulation of NK cells by α-GalCer through its activation of NKT cells. ( Cancer Sci 2008; 99: 113–120)     

Suramin augments the antitumor and antimetastatic activity of pentoxifylline in B16F10 melanoma

Rapid tumor growth and metastasis are 2 major problems associated with treatment of malignant melanoma. Therefore, drugs that can intervene these processes are of clinical importance. Pentoxifylline (PTX), a methyl xanthine derivative, has been shown to inhibit B16F10 melanoma tumor growth and metastasis. We hypothesized that suramin when combined with PTX enhances its antineoplastic effects, which we have examined using the B16F10 mouse melanoma model. Suramin in simultaneous or sequential combination potentiated the cytotoxic effects of PTX on B16F10 cells. PTX arrested cells in the G0-G1 phase and suramin augmented the effects. Both the drugs inhibited F10 adhesion to laminin, matrigel and collagen type IV and showed enhanced inhibition in combination The combination also demonstrated significantly higher inhibition in cell motility (p = 0.002) and invasion through matrigel (p = 0.005) as compared to the single agents. Suramin synergized with PTX in its effects on secretion of MMP-9 gelatinase. DBA2/J mice implanted with intradermal B16F10 tumor were used as a model to study tumor growth. Animals were intratumorally treated with 50 mg/kg of PTX, 10 mg/kg of suramin and their combinations. Simultaneous administration of the drugs inhibited tumor growth by 5- to 6-folds. Tumor growth was completely blocked in sequential regimen with regression in some cases. The number and size of metastatic nodules on lung was also reduced significantly by the combination treatment. In conclusion, the novel combination of PTX and suramin has synergistic antitumor and antimetastatic activity in B16F10 melanoma and may be a promising approach in treatment of patients suffering from malignant melanoma.     

As an independent unfavorable prognostic factor, IL-8 promotes metastasis of nasopharyngeal carcinoma through induction of epithelial-mesenchymal transition and activation of AKT signaling

Nasopharyngeal carcinoma (NPC) has the highest metastatic potential among head and neck cancers. Distant metastasis is the major cause of treatment failure. The role of interleukin-8 (IL-8) in NPC progression remains unknown. Our multivariate survival analyses of 255 patients with NPC revealed that higher IL-8 expression in primary NPC tissue was an independent prognostic factor for overall survival, disease-free survival, and distant metastasis-free survival of the patients. In vitro study revealed that IL-8 was highly expressed in the established high-metastasis NPC clone S18 relative to the low-metastasis cells. Suppression of IL-8 by short-hairpin RNA reduced the expression of IL-8 in S18 cells and subsequently inhibited migration, invasion, and hepatic metastasis of the cells without influencing cellular growth. Overexpression of IL-8 in S26 cells resulted in increased migration, invasion, and metastasis capabilities of the cells without affecting cellular growth. Exogenous IL-8 enhanced the migration and invasion of low-metastasis CNE-2 cells in a dose-dependent manner. An epithelial-mesenchymal transition (EMT) could be induced by IL-8 in various NPC cell lines. The high level of phosphorylated AKT in S18 cells could be suppressed by knocking down IL-8 expression. Further, IL-8-promoted migration and invasion could be abolished by either the application of the phosphoinositide-3-kinase inhibitor LY294002 or the knock down of AKT expression by using small-interfering RNA. In summary, IL-8 serves as an independent prognostic indicator of overall survival, disease-free survival, and metastasis-free survival for patients with NPC. IL-8 promotes NPC metastasis via autocrine and paracrine means, involving activation of AKT signaling and inducing EMT in NPC cells.     

蛇葡萄素抗黑色素瘤侵袭和转移的作用

背景与目的：我们先前的研究发现蛇葡萄素在体外对几种人肿瘤细胞以及在体内对小鼠移植性B16黑色素瘤具有抑制作用。为了进一步研究其抑制肿瘤转移的作用。我们研究了蛇葡萄素在体内外抗B16小鼠黑色素瘤侵袭和转移的作用。方法：B16细胞由尾静脉注入C57BL／6小鼠体内,建立实验性肺转移模型,蛇葡萄素以3个剂量从接种瘤细胞前一天腹腔给药,连续18天,于停药后第2天观察肺转移瘤灶数,B16细胞经蛇葡萄素处理3天,用具有聚碳酸酯和重建基底膜（基质胶Matrigel)的Transwell小室侵袭模型,研究药物处理后细胞侵袭,趋化运动,粘附能力的改变。结果：150、200,250mg/kg的蛇葡萄素可抑制小鼠肺转移瘤灶形成,与对照组比,抑制率分别为30．97％,40．58％,61．16％（P＜0．05）,经20,40,80μmol/L蛇葡萄素处理后,对B16细胞侵袭人工基底膜的抑制率分别为36．06％,59．58％和79．09％（P＜0．01）;对细胞的趋化运动抑制率分别为51．59％,56．51％和66．75％（P＜0．01）;显著降低B16细胞与基质成分层粘连蛋白,纤维粘连蛋白及Matrigel的粘附作用,结论：蛇葡萄素具有抑制黑色素瘤的侵袭和转移的作用。     

Expression of CXC chemokine receptor-4 enhances the pulmonary metastatic potential of murine B16 melanoma cells

The chemokine receptors CC chemokine receptor (CCR) 7 and CXC chemokine receptor (CXCR) 4 have been implicated in cancer metastasis. To evaluate whether CXCR4 is sufficient to increase tumor metastasis in an organ-specific manner, we transduced murine B16 melanoma cells with CXCR4 (CXCR4-B16) and followed the metastatic fate of the transduced cells in both i.v. and s.c. inoculation models of metastasis. CXCR4-B16 cells demonstrated marked increases (>10-fold) in pulmonary metastasis compared with vector (pLNCX2)-B16 after i.v. and s.c. inoculation of tumor cells. The increase in metastasis could be completely inhibited by T22, a small peptide antagonist of CXCR4. As early as 24 and 48 h after i.v. injection, CXCR4-B16 cells were significantly increased in the lung compared with control B16 cells by 5- and 10-fold (P < 0.05), respectively. CXCR4-B16 cells adhered better to both dermal and pulmonary microvascular endothelial cells relative to control B16 cells. Moreover, CXCL12 promoted the growth of CXCR4-B16 cells in vitro. Whereas expression of CXCR4 in B16 cells dramatically enhanced pulmonary metastasis, metastasis to the lymph nodes, liver, and kidney was rare. Immunohistochemical staining of both primary human cutaneous melanoma and pulmonary metastases revealed CXCR4 expression. Thus, CXCR4 plays a potentially important role in promoting organ-selective metastasis, possibly by stimulating tumor adhesion to microvascular endothelial cells and by enhancing the growth of tumor cells under stress.