Introduction: Metastatic malignant melanoma is an extremely aggressive cancer with no current viable therapy. A unique non-toxic nutrient mixture (NM) consisting of lysine, proline, ascorbic acid and green tea extract has shown potent anti-tumor effects in a number of cancer cell lines in vitro and in vivo. Objective: The present study investigated whether NM could also inhibit lung metastasis by B16F0 melanoma cell in C57BL/6 female mice. Method and Materials: C57BL/6 female mice were divided into 6 groups of 6 mice per group; Groups 1-4 were injected via tail vein with B16F0 melanoma cells (5x104/mouse) and Group 5 (control group) received the vehicle saline. Group 1 was fed the control diet, Group 2 was fed the same diet supplemented with 0.5% NM, Group 3 and 4 were given NM by IP and IV (4 mg/mouse, three times a week) respectively, and fed the control diet. Group 6 mice were fed the control diet but injected with B16F0 melanoma cells pretreated with NM (500 μg/ml for 24 hrs). In another study, mice were injected either with 106 or 105 B16F melanoma cells per mouse and divided into four groups (A-D). Groups A ,C were fed the control diet, while Groups B, D fed the same diet supplemented with 0.5% NM. Two weeks later mice in all the groups were euthanized, lungs were excised, weighed, fixed, pulmonary metastatic colonies were counted, and lung tissue processed for histology. Results: Pulmonary colonization was reduced to 63% in Group 2 (NM diet) compared to Group 1 (control). Pulmonary colonization was further inhibited by 86% in mice receiving MN by ip and iv injections (Groups 3, 4). Complete inhibition of pulmonary colonization was seen in mice that received melanoma cells pretreated with NM (Group 6). Findings were corroborated with histological analysis. Furthermore, inhibitory effect of NM was also confirmed by comparing the weight of lungs. Of mice that received 106 cells, the NM fed group (B) had an average lung weight of 0.55 gm, compared to 0.92 gm in the control group (A). Histopathology revealed metastasis in all lobes with back-to-back colonies. Similar inhibition was seen in the mice that received 105 cells. For example, an average lung weight of mice fed NM (Group D) was 0.11, compared to 0.15 gm in mice fed the control diet (Group E). Metastasis involved 40-45% of the lung. The average number of colonies in control Group C was 600, while in NM-fed Group D it was 400 (33% reduction). Results from the control and the test groups for weight of lungs and number of cells inoculated were pooled and the correlation coefficient was calculated. An excellent correlation was obtained (r=0.93, P<0.0001) Conclusions: These results show that NM is effective in suppressing the metastasis of B16 melanoma cells. These findings together with our earlier results clearly indicate that these potent anti-tumor properties of NM should be tested in clinical setting.
[Proc Amer Assoc Cancer Res, Volume 47, 2006]