C57BL/6小鼠B16黑色素瘤细胞脾转移机制

 目的　研究C57BL／6小鼠B16黑色素瘤细胞脾转移与血行转移的相关性。方法　细胞悬液接种法制备C57BL／6小鼠B16黑色素瘤细胞的荷瘤模型，HE染色法观察各组织器官中转移瘤细胞的有无及其生长状态，伊文思蓝尾静脉注射法观察蓝染部位与肿瘤转移阳性部位间的相关性。结果　接种成瘤率100 ％。12只小鼠中有9只出现脾转移，均同时伴有不同程度的局部淋巴结转移， 其中3只尚伴有肺转移。脾转移较肺转移出现早、概率高。大体观脾转移阳性部位位于脾背侧段约全长1／4区域。镜下观脾内转移瘤细胞呈散在分布，生长受抑并向成熟分化。伊文思蓝蓝染部位位于脾背侧段约全长1／4区域，与肿瘤转移阳性部位一致。结论　C57BL／6小鼠的B16黑色素瘤细胞脾转移先于其他脏器转移，其转移途径为血行转移。     

Pivotal role of CXCR3 in melanoma cell metastasis to lymph nodes

Chemokines and their receptors play key roles in leukocyte trafficking and are also implicated in cancer metastasis to specific organs. Here we show that mouse B16F10 melanoma cells constitutively express chemokine receptor CXCR3, and that its ligands CXCL9/Mig, CXCL10/IP-10, and CXCL11/I-TAC induce cellular responses in vitro, such as actin polymerization, migration, invasion, and cell survival. To determine whether CXCR3 could play a role in metastasis to lymph nodes (LNs), we constructed B16F10 cells with reduced CXCR3 expression by antisense RNA and investigated their metastatic activities after s.c. inoculations to syngeneic hosts, C57BL/6 mice. The metastatic frequency of these cells to LNs was markedly reduced to approximately 15% (P < 0.05) compared with the parental or empty vector-transduced cells. On the other hand, pretreatment of mice with complete Freund's adjuvant increased the levels of CXCL9 and CXCL10 in the draining LNs, which caused 2.5-3.0-fold increase (P < 0.05) in the metastatic frequency of B16F10 cells to the nodes with much larger foci. Importantly, such a stimulation of metastasis was largely suppressed when CXCR3 expression in B16F10 cells was reduced by antisense RNA or when mice were treated with specific antibodies against CXCL9 and CXCL10. We also demonstrate that CXCR3 is expressed on several human melanoma cell lines as well as primary human melanoma tissues (5 of 9 samples tested). These results suggest that CXCR3 inhibitors may be promising therapeutic agents for treatment of LN metastasis, including that of melanoma.     

抑制整合素α9基因的表达对黑色素瘤细胞B16F1的生长和肺转移的影响

目的 观察shRNA干扰整合素α9（ITGA9）的表达对黑色素瘤细胞B16F1的生长和肺转移的影响。方法 用RNA干扰技术下调B16F1中ITGA9的表达,建立小鼠皮下成瘤和肺转移模型,观察肿瘤生长情况,计数肺转移灶数量。结果 ITGA9-shRNA转染组的肿瘤生长速度减慢（P＜0.05）,实验终点,该组肿瘤平均体积与scramble-shRNA组相比下降36%;肺转移灶数量显著减少（P＜0.05）。结论 下调ITGA9的表达可抑制黑色素瘤细胞B16F1在小鼠体内的生长和肺转移。ITGA9可能成为黑色素瘤的治疗靶点。     

Genetic disruption of host nitric oxide synthase II gene impairs melanoma-induced angiogenesis and suppresses pleural effusion

Our previous study showed that genetic disruption of nitric oxide (NO) synthase II (NOS II) expression inhibits the metastatic ability of non-immunogenic B16 melanoma cells in syngeneic mice. In the present study, the mechanisms for this metastasis suppression were determined. B16-BL6 and B16-F10 murine melanoma cells were injected i.v. into syngeneic wild-type (NOS II(+/+)) and NOS II-null (NOS II(-/-)) C57BL/6 mice. Both melanoma cells produced less and smaller experimental pulmonary metastases in NOS II(-/-) mice than in NOS II(+/+) mice. Moreover, less metastatic pleural effusion was observed in NOS II(-/-) mice than in NOS II(+/+) mice. Immunohistochemical analyses indicated that absence of NOS II expression was correlated with decreased vascular endothelial growth factor expression and tumor-associated vascular formation. After activation with lipopolysaccharide and IFN-gamma, neither melanoma cell line produced detectable levels of NO. Our data demonstrate that tumor-induced expression of host NOS II enhances melanoma metastasis and pleural effusion, at least in part, through regulation of vascular formation and vascular permeability.     

BALB／C小鼠黑色素瘤肿瘤模型的建立及对荷瘤鼠的影响

目的建立小鼠不同部位黑色素瘤模型，为不同研究目的提供合适的动物肿瘤模型。方法接种B16小鼠黑色素瘤细胞于BALB／C小鼠足部、腹腔和尾静脉，建立移植瘤模型和肺部转移瘤模型。观察B16实体瘤的形态学特点，接种细胞数与肿瘤生成的关系，肿瘤生长对小鼠生存时间、血清肿瘤坏死因子（sTNF）和唾液酸（SA）的影响。结果足部接种5X10瘤细胞后10天，肿瘤进入对数生长，成瘤率近100％；腹腔接种瘤细胞数大于5000个／只，成瘤率与接种细胞数成正比；接种3X10细胞／只，10天后在小鼠腹壁和肠系膜可见散在黑色素瘤结节，荷瘤鼠sTNF和SA水平明显高于正常小鼠，且与肿瘤的大小和数量成正比，小鼠平均存活59天；尾静脉接种后3周，肺部可见大小不等转移瘤灶，两肺平均瘤灶数可达192.11士92。结论B16黑色素瘤细胞株在BALB／C小白鼠具有很高的成瘤率和转移特性，且较C57／B16小黑鼠模型具有方便、稳定和观察容易等优点，是一较理想的模型。     

Suppressing effects of dietary supplementation of the organoselenium 1,4-phenylenebis(methylene)selenocyanate and the Citrus antioxidant auraptene on lung metastasis of melanoma cells in mice

The modifying effects of the organoselenium 1,4-phenylenebis(methylene)selenocyanate (p-XSC) and the Citrus antioxidant auraptene as dietary supplements on experimental pulmonary metastasis of B16BL6 murine melanoma cells were investigated in an i.v. injection model in mice. Seven groups of male C57BL/6 mice were fed a basal diet (control group) or the basal diet supplemented with p-XSC (4, 8, or 15 mg/kg) or auraptene (250, 500, or 1000 mg/kg). All mice were fed their respective diet for 2 weeks before and after i.v. injection of 1 x 10(5) viable melanoma cells. At termination of the study, the incidence of lung metastatic tumors was determined. Cross-sectional areas and tumor volumes were analyzed morphometrically. In addition, apoptotic indices of lung metastatic tumors of all groups were counted. The incidences of lung metastasis in mice fed the diet mixed with 8 or 15 mg p-XSC/kg were significantly smaller than that in mice fed the basal diet. The mean numbers of metastatic lung tumors were significantly lower in mice fed p-XSC (4, 8, and 15 mg/kg) and auraptene (500 and 1000 mg/kg) than in controls. Cross-sectional areas and volumes of the tumors were also significantly decreased in mice given p-XSC (8 or 15 mg/kg) and auraptene (500 mg/kg). Apoptotic indices in mice fed the diets mixed with p-XSC (4, 8, or 15 mg/kg) and auraptene (500 and 1000 mg/kg) were significantly greater than those in the control group. These results indicate that in mice, diet supplementation with p-XSC and auraptene reduces pulmonary metastasis of B16BL6 melanoma cells and inhibits the growth of these metastatic tumors in lung, in part, by inducing apoptosis. We suggest that these agents, especially p-XSC, may be valuable in preventing metastatic diseases in future studies in the clinic.     

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.     

99mTcOAADT]-(CH2)2-NEt2: a potential small-molecule single-photon emission computed tomography probe for imaging metastatic melanoma

Evaluation of [99mTc]oxotechnetium(V) complexes of the amine-amide-dithiol (AADT) chelates containing tertiary amine substituents as small-molecule probes for the diagnostic imaging of metastatic melanoma has shown that technetium-99m-labeled AADT-(CH2)2-NEt2 (99mTc-1) has the highest tumor uptake and other favorable biological properties. We have, therefore, assessed this agent in a more realistic metastatic melanoma model in which, after i.v. tail injection, a highly invasive melanoma cell line, B16F10, forms pulmonary tumor nodules in normal C57BL6 mice. Small melanotic lesions develop in the lungs and, on histologic examination, appear as small black melanoma colonies, increasing in size and number with time after tumor cell injection. Groups of mice received tumor cell inocula of 2 x 10(5), 4 x 10(5), or 8 x 10(5) B16F10 cells; 14 days later, 2 hours after 99mTc-1 administration, lung uptake of 2.83 +/- 0.21%, 3.63 +/- 1.07%, and 4.92 +/- 1.61% injected dose per gram of tissue (% ID/g), respectively, was observed, compared with normal lung uptake of 2.13 +/- 0.2% ID/g (P < 0.05). Additionally, a higher level of 99mTc-1 accumulation was seen 17 days after tumor cell inoculation as the lung lesions grew. These in vivo studies coupled with additional in vitro and ex vivo assessment show that 99mTc-1 has high and specific uptake in melanoma metastases in lungs and can potentially follow the temporal growth of these tumors.     

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.     

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。     

Interference with the complement system by tumor cell membrane type-1 matrix metalloproteinase plays a significant role in promoting metastasis in mice

Neoplasms have developed strategies to protect themselves against the complement-mediated host immunity. Invasion- and metastasis-promoting membrane type-1 (MT1) matrix metalloproteinase (MMP) is strongly associated with many metastatic cancer types. The relative importance of the individual functions of MT1-MMP in metastasis was, however, unknown. We have now determined that the expression of murine MT1-MMP in murine melanoma B16F1 cells strongly increased the number of metastatic loci in the lungs of syngeneic C57BL/6 mice. In contrast, MT1-MMP did not affect the number of metastatic loci in complement-deficient C57BL/6-C3-/- mice. Our results indicated, for the first time, that the anticomplement activity of MT1-MMP played a significant role in promoting metastasis in vivo and determined the relative importance of the anticomplement activity in the total metastatic effect of this multifunctional proteolytic enzyme. We believe that our results shed additional light on the functions of MT1-MMP in cancer and clearly make this protease a promising drug target in metastatic malignancies.     

Modulation of metastatic potential of B16F10 melanoma cells by acivicin: synergistic action of glutaminase and potentiation of cisplatin cytotoxicity.

Treatment for metastatic melanoma has mostly been unsatisfactory despite advances in ongoing medical research. Here we investigated the role of acivicin, a glutamine analogue, singly and in combination with either E. coli glutaminase or cisplatin, on the growth, angiogenic activity and invasiveness of B16F10 cells in vitro and after allografting in C57BL/6 mice. B16F10 melanoma colonization in the lungs of mice was measured by monitoring colony counts. Host toxicity was assessed with reference to tumor bearing host's weight and survivability. Acivicin promoted melanoma dormancy and reduced melanoma associated angiogenic factors like VEGF level and vessel diameter. Acivicin in combination with glutaminase significantly suppressed tumor growth by 66.7% and increased life-span by 43.5% without host toxicity. Tumor VEGF content was significantly lowered by combination therapy as assessed by ELISA. Accelerated cytotoxicity, reduced invasion and enhanced apoptosis of melanoma cells were exhibited in vitro by combined than by single agent treatment. Moreover, invasion of melanoma cells through matrigel chambers was reduced in presence of acivicin and glutaminase combination. These findings support future studies of acivicin in combination with other anticancer agents for prevention of melanoma metastasis.     

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。     

A clinically relevant, syngeneic model of spontaneous, highly metastatic B16 mouse melanoma

We report a syngeneic model of spontaneous metastatic B16-F10 mouse melanoma in C57/BL6 mice with a very high metastatic frequency that mimics clinical metastatic melanoma. The B16 melanoma cells were injected between the skin and cartilage on the dorsal side of the ear. The model generated lymphatic and visceral metastases in all of the tested animals. In mice with large primary tumors, tumor weight correlated with the tumor growth time and also with the number of metastases in lymph nodes and organs. The dorsal ear space between the skin and cartilage enables both lymphatic and hematogenous metastatic spread. The model should be useful to study the mechanism of melanoma metastasis and to develop therapy for this currently untreatable disease.     

Dietary restriction of tyrosine and phenylalanine: inhibition of metastasis of three rodent tumors

The effects of a combined dietary restriction of tyrosine and phenylalanine on metastasis were investigated with the use of 3 rodent tumor cell lines: B16-bladder 6 (BL6) melanoma inoculated into (C57BL/6 X DBA/2)F1 mice, Lewis lung (3LL) carcinoma inoculated into C57BL/6 mice, and RT7-4bs hepatocarcinoma inoculated into BD-IV rats. When examined for effects on spontaneous metastasis, dietary restriction of tyrosine and phenylalanine had no effect on metastasis to draining lymph nodes in either BL6 or 3LL tumors. However, the restriction did reduce metastasis of RT7-4bs cells to draining lymph nodes by 60%. In all tumor systems, the dietary restriction effectively inhibited the subsequent growth of lymph node tumors. The most marked effect of the dietary restriction was on spontaneous hematogenous metastasis, which was almost totally blocked for BL6 cells and was reduced by 85% for RT7-4bs cells. Tumor-associated splenomegaly also was completely inhibited in 3LL tumor-bearing mice. The selective dietary amino acid restriction failed to reduce initial lung colonization in the experimental metastasis assay but clearly inhibited subsequent tumor outgrowth in the lungs. These findings demonstrate that modification of host nutritional status by restriction of the dietary intake of tyrosine and phenylalanine exerts a dramatic antimetastatic effect directed particularly on spontaneous hematogenous metastasis. Although the preliminary data suggest a primary modulating effect on tumor cell populations growing in diet-restricted animals to reduce inherent metastatic ability, the actual mechanisms remain to be defined.     

Thrombin inhibitor, argatroban, prevents tumor cell migration and bone metastasis

It is well known that malignant cells show procoagulant activity, which is associated with their metastatic potential. Thrombin, the key enzyme of the blood coagulation system, is generated around tumor cells, promoting the migration and metastasis of tumor cells. In this study, we evaluated the effect of argatroban, a specific thrombin inhibitor, on the migration and metastasis of B16BL6 melanoma cells. In vitro argatroban dose-dependently inhibited cell migration, the maximum inhibition being observed in the presence of 10 microM argatroban (p < 0.0001). In order to investigate the antimetastatic effect of the thrombin inhibitor, we used an animal model that we have reported previously. C57BL6 mice which had received a bone (femur or tibia) transplanted into the dorsal subcutis were injected with B16 melanoma cells into the left heart ventricle. Intraperitoneal injection of argatroban (9 mg/kg/day for 4 weeks) significantly reduced the number of limbs with metastatic lesions as compared to a placebo (p < 0.05). These results suggest that argatroban was associated with reduced melanoma metastases by inhibiting cell migration. Our results showed that argatroban is effective for treatment of bone metastasis.     

Inhibition of Metastatic Lung Cancer in C57BL/6 Mice byMarine Mangrove Rhizophora apiculata

Metastasis is one of the hallmarks of malignant neoplasms and is the leading cause of death in many cancerpatients. A major challenge in cancer treatment is to find better ways to specifically target tumor metastasis.In this study, the anti-metastatic potential of the methanolic extract of Rhizophora apiculata (R.apiculata) wasevaluated using the B16F-10 melanoma induced lung metastasis model in C57BL/6 mice. Metastasis was inducedin C57BL/6 mice by injecting highly metastatic B16F-10 melanoma cells through the lateral tail vein. Simultaneoustreatment with R.apiculata extract (10 mg/kg b.wt (intraperitoneal) significantly (p<0.01) inhibited pulmonarytumor nodule formation (41.1 %) and also increased the life span (survival rate) 107.3 % of metastatic tumorbearing animals. The administration of R.apiculata extract significantly (p<0.01) reduced biochemical parameterssuch as lung collagen hydroxyproline, hexosamine, uronic acid content, serum nitric oxide (NO), γ-glutamyltranspeptidase (GGT) and sialic acid levels when compared to metastasis controls. These results correlated withlung histopathology analysis of R.apiculata extract treated mice showing reduction in lung metastasis and tumormasses. Taken together, our findings support that R.apiculata extract could be used as a potential anti-metastasisagent against lung cancer.     

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.     

Correlation of gangliosides GM2 and GM3 with metastatic potential to lungs of mouse B16 melanoma

Ten B16 mouse melanoma cell lines with increasing metastatic potential to lungs (B16LuF1 to B16LuF10) were generated by in-vitro & in-vivo selection technique starting with B16F1 melanoma cell line. The number of metastatic tumor nodules in lungs rose with increasing metastatic potential. Tumor cell gangliosides of B16LuF1 to B16LuF10 cell lines, analysed and compared with TLC, showed eight major ganglioside bands. Band1 to band6 corresponded with standard gangliosides GT1b, GD1b, GD1a, GM1, GM2 and GM3 respectively. Band7 and Band8 could not be identified. The concentration of total as well as individual ganglioside bands of B16LuF1 to B16LuF10 cells appeared to rise with increasing metastatic potential. Gangliosides from the plasma of these cell lines (B16LuF1 to B16LuF10) maintained in-vivo in C57BL/6 mice on TLC analysis gave eight major ganglioside bands, similar to those of cells. Plasma gangliosides appeared to rise with increasing metastatic potential. However, it was interesting to see that only band5 and band6 gangliosides in plasma increased almost linearly with increasing metastatic potential. The remaining six ganglioside bands in the plasma did not show such correlation. Band5 and Band6 gangliosides corresponded with standard gangliosides GM2 and GM3 respectively. Gangliosides of the spent culture media, secreted by these cell lines in-vitro in tissue culture also gave eight major ganglioside bands, similar to that of cells. Spent culture media gangliosides appeared to increase with increasing metastatic potential. However, concentration of only band5 and band6 gangliosides of spent culture media increased almost linearly with increasing metastatic potential, thus further confirming the role of band5(GM2) and Band6(GM3) gangliosides in regulating metastatic potential of B16-melanoma cells to lung.