Severe pulmonary metastasis in obese and diabetic mice

Although obesity is known as a risk factor for several human cancers, the association of obesity with cancer recurrence and metastasis remains to be characterized. Here, B16-BL6 melanoma and Lewis lung carcinoma cells were intravenously injected into diabetic (db/db) and obese (ob/ob) mice. The number of experimental lung colonies was markedly promoted in these mice when compared with C57BL/6 mice. In contrast, tumor growth at the implanted site was comparable when cells were inoculated orthotopically. The use of B16-BL6 cells stably transfected with the luciferase gene revealed that the increased metastasis reflected a difference mainly within 6 hr after the intravenous inoculation of tumor cells. Administration of recombinant leptin in ob/ob mice abolished the increase in metastasis early on as well as the decrease in the splenic NK cell number. In addition, depletion of NK cells by an anti-asialo-GM1 antibody abrogated the enhanced metastasis in db/db mice. These results demonstrate that metastasis is markedly promoted in diabetic and obese mice mainly because of decreased NK cell function during the early phase of metastasis.     

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.     

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.     

Inhibition of metastatic tumor growth in mouse lung by repeated administration of polyethylene glycol-conjugated catalase: quantitative analysis with firefly luciferase-expressing melanoma cells.

PURPOSE: To develop a novel and effective approach to inhibit tumor metastasis based on controlled delivery of catalase, we first evaluated the characteristics of the disposition and proliferation of tumor cells. Then, we examined the effects of polyethylene glycol-conjugated catalase (PEG-catalase) on tumor metastasis. On the basis of the results obtained, PEG-catalase was repetitively administered to completely suppress the growth of tumor cells. EXPERIMENTAL DESIGN: Murine melanoma B16-BL6 cells were stably transfected with firefly luciferase gene to obtain B16-BL6/Luc cells. These cells were injected intravenously into syngeneic C57BL/6 mice. PEG-catalase was injected intravenously, and the effect was evaluated by measuring the luciferase activity as the indicator of the number of tumor cells. RESULTS: At 1 hour after injection of B16-BL6/Luc cells, 60 to 90% of the injected cells were recovered in the lung. The numbers decreased to 2 to 4% at 24 hours, then increased. An injection of PEG-catalase just before inoculation significantly reduced the number of tumor cells at 24 hours. Injection of PEG-catalase at 1 or 3 days after inoculation was also effective in reducing the cell numbers. Daily dosing of PEG-catalase greatly inhibited the proliferation and the number assayed at 14 days after inoculation was not significantly different from the minimal number observed at 1 day, suggesting that the growth had been markedly suppressed by the treatment. CONCLUSIONS: These findings indicate that sustained catalase activity in the blood circulation can prevent the multiple processes of tumor metastasis in the lung, which could lead to a state of tumor dormancy.     

Enhancement of antiproliferative activity of interferons by RNA interference-mediated silencing of SOCS gene expression in tumor cells

The suppressor of cytokine signaling (SOCS) proteins, negative regulators of interferon (IFN)-induced signaling pathways, is involved in IFN resistance of tumor cells. To improve the growth inhibitory effect of IFN-β and IFN-γ on a murine melanoma cell line, B16-BL6, and a murine colon carcinoma cell line, Colon26 cells, SOCS-1 and SOCS-3 gene expression in tumor cells was downregulated by transfection of plasmid DNA expressing short hairpin RNA targeting one of these genes (pshSOCS-1 and pshSOCS-3, respectively). Transfection of pshSOCS-1 significantly increased the antiproliferative effect of IFN-γ on B16-BL6 cells. However, any other combinations of plasmids and IFN had little effect on the growth of B16-BL6 cells. In addition, transfection of pshSOCS-1 and pshSOCS-3 produced little improvement in the effect of IFN on Colon26 cells. To understand the mechanism underlining these findings, the level of SOCS gene expression was measured by real time polymerase chain reaction. Addition of IFN-γ greatly increased the SOCS-1 mRNA expression in B16-BL6 cells. Taking into account the synergistic effect of pshSOCS-1 and IFN-γ on the growth of B16-BL6 cells, these findings suggest that IFN-γ-induced high SOCS-1 gene expression in B16-BL6 cells significantly interferes with the antiproliferative effect of IFN-γ. These results indicate that silencing SOCS gene expression can be an effective strategy to enhance the antitumor effect of IFN under conditions in which the SOCS gene expression is upregulated by IFN. ( Cancer Sci 2008; 99: 1650–1655)     

Inhibition of Tumor Cell Invasion by Ubenimex (Bestatin) in vitro

We have investigated the effect of the immunomodulator ubenimex (bestatin) on tumor cell invasion of reconstituted basement membrane (Matrigel). The invasion of B16-BL6 melanoma cells and Lewis lung carcinoma (3LL) cells into Matrigel-coated filters was inhibited by the presence of bestatin in a concentration-dependent manner. The prctrcatment of either tumor cells or Matrigel with bestatin, however, had little effect on the invasion of tumor cells. Since bestatin was found to inhibit aminopeptidase in addition to its immunomodulating activities, the inhibition of tumor invasion by bestatin is likely to be associated with the action as an enzyme inhibitor. Other aminopeptidase inhibitors, arphamcnine B and amastatin A, could also inhibit tumor cell invasion into Matrigel. Bestatin inhibited hydrolyzing activities towards substrates of aminopeptidases in B16-BL6 melanoma cells. However, bestatin did not have any effect on the haptotactic migration and adhesion of tumor cells to the substrates. These results indicated that bestatin may inhibit tumor cell invasion through a mechanism involving its inhibitory action on aminopeptidases in tumor cells.     

Inhibition of tumor cell invasion by ubenimex (bestatin) in vitro

We have investigated the effect of the immunomodulator ubenimex (bestatin) on tumor cell invasion of reconstituted basement membrane (Matrigel). The invasion of B16-BL6 melanoma cells and Lewis lung carcinoma (3LL) cells into Matrigel-coated filters was inhibited by the presence of bestatin in a concentration-dependent manner. The pretreatment of either tumor cells or Matrigel with bestatin, however, had little effect on the invasion of tumor cells. Since bestatin was found to inhibit amino-peptidase in addition to its immunomodulating activities, the inhibition of tumor invasion by bestatin is likely to be associated with the action as an enzyme inhibitor. Other aminopeptidase inhibitors, arphamenine B and amastatin A, could also inhibit tumor cell invasion into Matrigel. Bestatin inhibited hydrolyzing activities towards substrates of aminopeptidases in B16-BL6 melanoma cells. However, bestatin did not have any effect on the haptotactic migration and adhesion of tumor cells to the substrates. These results indicated that bestatin may inhibit tumor cell invasion through a mechanism involving its inhibitory action on aminopeptidases in tumor cells.     

人参皂甙Rg3和核糖核酸酶抑制因子转基因对小鼠黑色素瘤的抑制作用研究

目的观察人参皂甙Rg3和核糖核酸酶抑制因子(RI)转基因对小鼠B16黑色素瘤肺转移的抑制作用和影响,探讨人参皂甙Rg3和RI抗肿瘤生长和转移作用的分子机制。方法制备转RI基因的B16黑色素瘤肺转移小鼠模型,对野生型对照组(W组)、空质粒转染组(B组)和RI转基因组(RI组)以及给予Rg3的野生型对照组(Rg3/W组)、空质粒转染组(Rg3/B组)和RI转基因组(Rg3/RI组)中,荷瘤小鼠肺重量、肿瘤转移灶数目、生存期和肿瘤组织微血管密度进行检测和分析。结果Rg3和RI转基因使荷瘤小鼠肺重量降低,肿瘤转移灶数目减少,其肺重量降低和肿瘤转移灶数目减少的程度以Rg3/RI组最明显,Rg3/B组、Rg3/W组和RI组次之,与W组和B组差异有显著性(P<0.01),Rg3和RI有一定的协同性。Rg3和RI可延长荷瘤小鼠的生存期,Rg3/RI组小鼠在观察期(1.5个月)内均存活,W组和B组小鼠全部死亡(至26d),且出现死亡的时间较早。经HE染色和第Ⅷ因子相关抗原的免疫组化分析显示,Rg3和RI使肺内瘤组织的微血管密度降低,降低的程度为Rg3/RI组>Rg3/B组>Rg3/W组>RI组>B组>W组。结论人参皂甙Rg3可增强RI转基因对小鼠黑色素瘤肺转移的抑制作用,人参皂甙Rg3和RI基因在抗肿瘤生长、转移及血管生成方面有协同作用。     

Influence of nitric oxide synthase II gene disruption on tumor growth and metastasis

The relationship between nitric oxide (NO) synthase II (NOS II) expression and the metastatic ability of tumor cells is inconclusive. We determined the role of host NOS II expression in the growth and metastasis of the B16-BL6 murine melanoma and M5076 murine ovarian sarcoma cell lines. The cells were either s.c. or i.v. injected into syngeneic wild-type (NOS H+/+) and NOS II-null (NOS H-/-) C57BL/6 mice. Both cell lines produced slightly larger s.c. tumors in NOS H-/- mice than in NOS II+/+ mice. However, B16- BL6 cells produced more and larger experimental lung metastases in NOS II+/+ mice than in NOS II-/- mice, whereas M5076 cells produced fewer and smaller experimental lung metastases in NOS II+/+ mice than in NOS II-/- mice. After activation with IFN-gamma and lipopolysaccharide, macrophages isolated from NOS II+/+ C57BL/6 mice produced NO-dependent cytotoxicity in sarcoma cells, whereas macrophages from NOS II-/- C57BL/6 mice did not. In contrast, activated macrophages produced little to no NO-mediated cytotoxicity in melanoma cells. Immunostaining analyses indicated that NOS II expression was apparent in the metastases growing in NOS H+/+ mice and correlated with increased cell proliferation in B16-BL6 lung metastases but with decreased cell proliferation in M5076 liver metastases. Our data suggest that disruption of host NOS II expression enhanced the growth and metastasis of NO-sensitive tumor cells but suppressed the metastasis of NO-resistant tumor cells, proposing that host-derived NO may differentially modulate tumor progression.     

Antimetastatic Effect by Anti-adhesion Therapy with Cell-adhesive Peptide of Fibronectin in Combination with Anticancer Drugs

We have investigated the therapeutic effect of CH-271 fusion polypeptide containing both cell-binding domain (C-274) and heparin-binding domain (H-271) of fibronectin in combination with anticancer drugs such as doxorubicin (DOX) or mitomycin C (MMC) on tumor metastasis of different types of tumors. CH-271 fusion polypeptide alone significantly inhibited both liver and lung metastasis when it was co-injected with L5178Y-ML25 T-lymphoma, RAW117-H10 B-lymphoma or B16-BL6 melanoma cells, and spontaneous lung metastasis of B16-BL6 melanoma cells when administered i.v. seven times before or after surgical excision of the primary tumors. Combined treatments with CH-271 and either DOX or MMC significantly inhibited liver and lung metastasis of lymphoma or melanoma cells respectively, as compared with either treatment alone or the untreated control. Administrations of CH-271 and DOX in combination substantially prolonged the survival time of mice injected i.v. with L5178Y-ML25 cells. CH-271 or DOX was effective for inhibiting the invasion of LS178Y-ML25 cells into Matrigel in a concentration-dependent manner. Our previous study has shown that CH-271-mediated inhibition of tumor invasion may be due in part to the anti-cell adhesive property without affecting the cell growth, whereas the anti-invasive effect of DOX was established to have resulted from the growth inhibition of tumor cells. Moreover, the combination of CH-271 with DOX provided a more effective inhibition of tumor invasion into Matrigel than did either alone. Thus, we have demonstrated that the combination of anti-cell adhesive CH-271 and anticancer drugs such as DOX or MMC, i.e. anti-adhesion therapy and chemotherapy, is a new approach that offers enhanced (additive) inhibitory effects on tumor metastasis and invasion.     

Reduced Invasive and Metastatic Potentials of KAI1-transfected Melanoma Cells

KAI1 is a metastasis suppressor gene for human prostate cancer. To reveal the effect of KAI1 on the in vivo metastasis of tumors other than prostatic cancer, we transfected a human KAI1 cDNA into highly metastatic B16-BL6 murine melanoma cells and established stable transfectant clones with different expression levels of KAI1 message. The following results were obtained with the use of those transfectants. (1) Cell aggregation assay revealed a significantly enhanced Ca²⁺-independent aggregation of B16-BL6 cells by KAI1 cDNA transfection compared with mock transfectants ( P <0.01). (2) The in vivo phagokinetic activity and invasive ability of KAI1 transfectants were clearly decreased as compared with those of mock transfectants ( P <0.01). There was no significant effect of KAI1 expression on the in vitro or in vivo proliferation of B16-BL6 cells. (3) Lung colony formation of intravenously injected KAI1 transfectants in nude mice was significantly reduced as compared with mock transfectants or parental B16-BL6 cells ( P <0.01). These data suggest that KAI1 expression gives rise to the suppression of invasive and metastatic potentials of B16-BL6 cells.     

A variant actin (βm) reduces metastasis of mouse B16 melanoma

We recently reported an acidic actin co-expressed with β and γ actin in mouse B16 melanoma, whose expression was inversely correlated with the metastatic potential. The cDNA for this actin is slightly different from the hitherto recognized mouse β actin cDNA, and we designated it βm actin. In order to directly investigate the effects of βm actin on metastasis, we transfected the βm actin cDNA into a re-cloned B16-BL6 cell line which is more invasive than the highly metastatic cell line, B16-F10; we have already reported the suppressive effect of pm actin on the invasiveness of B16 F10. Here we report on the decline in the metastatic ability of βm-transfected cells. In the pm-transfected B16-BL6 cell line, we observed an increase in the organization of actin stress fibers, accompanied by a decrease in metastasis to the lung, in the invasion of collagen gels, in In vivo invasive-ness, and in cell migration on a glass plate covered with colloidal gold particles. We observed no correlation of pm actin expression either with cell attachment to Matrigel, or with type-IV collagenase expression. These results suggest that βm actin can play a role in reducing the invasiveness of mouse B16 melanoma, most probably through decreasing cell motility, which may thus result in suppression of the metastatic ability of cells.     

DT-5461, a New Synthetic Lipid A Analogue, Inhibits Lung and Liver Metastasis of Tumor in Mice

We have investigated the antimetastatic effect of a new synthetic lipid A analogue, of low endo-toxicity, DT-5461, against two highly metastatic tumor cell lines, L5178Y-ML25 T-lymphoma and B16-BL6 melanoma cells in mice. Four intermittent i.v. administrations of DT-5461 at intervals of 4 days resulted in a significant inhibition of liver metastasis caused by i.v. injection of L5178Y-ML25 cells and lung metastasis of B16-BL6 cells in the experimental metastasis models. Intraperitoneal and intranasal administrations as well as i.v. administration of DT-5461 were also effective in preventing lung metastasis of the melanoma cells. Multiple administrations of DT-5461 before the surgical excision of primary tumors significantly reduced the number of lung colonies of melanoma cells and primary tumor size. Similarly, this treatment modality after the surgical excision of primary tumors showed a greater reduction of lung tumor colonies as compared with lipopolysaccharide, a synthetic lipid A (No. 506) and its analogue as well as untreated control in the spontaneous lung metastasis model. Furthermore, the group that received DT-5461 after the inoculation of lymphoma or melanoma cells showed significantly enhanced survival rate compared with the untreated control. These results suggested that DT-5461 may he therapeutically useful for the inhibition of tumor metastasis.     

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.     

DT-5461, a new synthetic lipid A analogue, inhibits lung and liver metastasis of tumor in mice.

We have investigated the antimetastatic effect of a new synthetic lipid A analogue, of low endotoxicity, DT-5461, against two highly metastatic tumor cell lines, L5178Y-ML25 T-lymphoma and B16-BL6 melanoma cells in mice. Four intermittent i.v. administrations of DT-5461 at intervals of 4 days resulted in a significant inhibition of liver metastasis caused by i.v. injection of L5178Y-ML25 cells and lung metastasis of B16-BL6 cells in the experimental metastasis models. Intraperitoneal and intranasal administrations as well as i.v. administration of DT-5461 were also effective in preventing lung metastasis of the melanoma cells. Multiple administrations of DT-5461 before the surgical excision of primary tumors significantly reduced the number of lung colonies of melanoma cells and primary tumor size. Similarly, this treatment modality after the surgical excision of primary tumors showed a greater reduction of lung tumor colonies as compared with lipopolysaccharide, a synthetic lipid A (No. 506) and its analogue as well as untreated control in the spontaneous lung metastasis model. Furthermore, the group that received DT-5461 after the inoculation of lymphoma or melanoma cells showed significantly enhanced survival rate compared with the untreated control. These results suggested that DT-5461 may be therapeutically useful for the inhibition of tumor metastasis.     

Inhibition of the metastatic spread and growth of B16-BL6 murine melanoma by a synthetic matrix metalloproteinase inhibitor

The synthetic matrix metalloproteinase inhibitor batimastat was tested for its ability to inhibit growth and metastatic spread of the B16-BL6 murine melanoma in syngeneic C57BL/6N mice. Intraperitoneal administration of batimastat resulted in a significant inhibition in the number of lung colonies produced by B16-BL6 cells injected i.v. The effect of batimastat on spontaneous metastases was examined in mice inoculated in the hind footpad with B16-BL6 melanoma. The primary tumor was removed surgically after 26-28 days. Batimastat was administered twice a day from day 14 to day 28 (pre-surgery) or from day 26 to day 44 (post-surgery). With both protocols, the median number of lung metastases was not significantly affected, but there was a significant reduction in the weight of the metastases. Finally, the effect of batimastat was examined on s.c. growth of B16-BL6 melanoma. Batimastat administered daily, starting at day of tumor transplantation, resulted in a significant growth delay, whereas treatment starting at advanced stage tumor only reduced tumor growth marginally. Our results indicate that a matrix metalloproteinase inhibitor can not only prevent the colonization of secondary organs by B16-BL6 cells but also limit the growth of solid tumors.     

基因枪介导的neu基因DNA疫苗抗肿瘤作用的实验研究

目的 探讨DNA疫苗pWRG-neu的皮内免疫,对高表达neu基因的小鼠移植瘤生长和转移的抑制作用。方法 向小鼠黑色素瘤B16F10细胞系转染pcDNA-neu,用有限稀释法筛选一株高表达neu基因的细胞株B16F10-neu。在基因枪介导下,向C57BL／6小鼠导入DNA疫苗pWRG-neu,通过观察免疫动物的生存期,评价DNA疫苗的抗肿瘤作用。分离免疫动物脾细胞,经自体淋巴细胞混合培养实验,分析DNA疫苗体内免疫后机体的CTL应答。结果 筛选到一株高表达neu基因的B16F10-neu细胞株,转基因过程和外源基因的表达没有改变细胞系的增殖特性。用基因枪轰击,进行DNA疫苗pWRG-neu皮内免疫,对小鼠黑色素瘤B16F10-neu进行预防、治疗和抗转移的实验研究,结果表明,DNA疫苗的免疫能够明显推迟移植瘤的生长,延长小鼠生存期,获得明显的抗肿瘤效果。DNA疫苗免疫后可诱导小鼠脾淋巴细胞CTL活性。结论 基因枪介导的DNA疫苗pWRG-neu经皮内免疫,能够有效的诱导机体的细胞免疫应答,预防和治疗小鼠移植瘤的发生,并有一定的预防肿瘤肺转移的作用。     

Inhibition of invasion,gelatinase activity,tumor take and metastasis of malignant cells by N-acetylcysteine

The thiol N-acetylcysteine (NAC) is currently considered one of the most promising cancer chemopreventive agents by virtue of its multiple and coordinated mechanisms affecting the process of chemical carcinogenesis. Recent studies have shown that an unpaired cysteine residue in the propeptide plays a key role in inactivation of latent metastasis-associated metalloproteinases: the present study was designed to assess whether NAC could also affect tumor take, invasion and metastasis of malignant cells. As assessed by zymographic analysis, NAC completely inhibited the gelatinolytic activity of type-IV collagenases in the cells tested (gelatinases A and B). Moreover, NAC was efficient in inhibiting the chemotactic and invasive activities of tumor cells of human (A2058 melanoma) and murine origin (K1735 and B16-F10 melanoma cells as well as C87 Lewis lung carcinoma cells) in Boyden-chamber assays, which are predictive of the invasive and metastatic properties. Reduced glutathione (GSH) had a similar, although less effective activity. The number of lung metastases decreased sharply when B16-F10 murine melanoma cells, injected i.v. into nude mice, were pre-treated with NAC and resuspended in medium supplemented with 10 mM NAC. In other experiments NAC was given in drinking water, starting 48-72 hr before subcutaneous inoculation of either B16-F10 cells or of their highly metastatic variant B16-BL6, or intramuscular injection of LLC cells. In all experiments NAC treatment decreased the weight of the locally formed primary tumor and produced a dose-related delay in tumor formation. Spontaneous metastasis formation by B16-F10 and B16-BL6 tumors was slightly yet significantly reduced by oral administration of NAC. However, this was not observed for Lewis lung tumors. These data indicate that NAC affects the process of tumor-cell invasion and metastasis, probably due to inhibition of gelatinases by its sulfhydryl group, with the possible contribution of other mechanisms, including the potent antioxidant activity of this thiol. © 1995 Wiley-Liss, Inc.     

Tumor metastasis and cell adhesion molecules

The adhesive interaction between tumor cells, host cells or extracellular matrix (ECM) plays a crucial role in metastatic formation. We used synthetic polypeptide containing a repetitive core sequence, Arg-Gly-Asp (RGD), of cell-adhesive molecules; poly (RGD), to antagonize the adhesive interaction between ECM and integrin receptors on tumor cell surface during the metastatic cascade. Poly (RGD) significantly inhibited the experimental lung and liver metastasis as compared with RGD peptide when it was coinjected i.v. with different types of tumors. In a spontaneous lung metastasis model using B16-BL6 melanoma, multiple i.v. administrations of poly (RGD), before or after surgical excision of the primary tumor, resulted in significant reduction of the lung colonization. The mechanism responsible for the inhibition is partly associated with the ability to interfere with cell functions such as adhesiveness, motility, and invasiveness in the metastatic process. Poly (RGD) showed no cytotoxicity against host and tumor cells. Thus, the regulation of adhesive interaction of tumor cells with ECM or host cells by anti-adhesive polypeptides may provide a promising approach for the prevention of tumor metastasis.