Attachment, invasion, chemotaxis, and proteinase expression of B16-BL6 melanoma cells exhibiting a low metastatic phenotype after exposure to dietary restriction of tyrosine and phenylalanine.

We previously reported that low levels of tyrosine (Tyr) and phenylalanine (Phe) alter the metastatic phenotype of B16-BL6 (BL6) murine melanoma and select for tumor cell populations with decreased lung colonizing ability. To more specifically characterize the effects of Tyr and Phe restriction on the malignant phenotype of BL6, we investigated in vitro attachment, invasion, proteinase expression, and chemotaxis of high and low metastatic BL6 variants. High metastatic variant cells were isolated from subcutaneous tumors of mice fed a nutritionally complete diet (ND cells) and low metastatic variant cells were isolated from mice fed a diet restricted in Tyr and Phe (LTP cells).

Effect of L-dopa methylester and glutathione depletion on murine B16BL6 melanoma growth in vitro.

The cytotoxic and growth-inhibitory effect of levodopa methylester (LDME) in murine B16BL6 (BL6) melanoma cells after glutathione (GSH) depletion was studied in vitro. Pretreatment of BL6 cells with 50 microM buthionine sulfoximine (BSO) depleted GSH content by nearly 90% and enhanced the growth-inhibitory effect of even a minimally cytotoxic concentration of LDME. Radiothymidine incorporation into BL6 cells significantly increased compared to untreated controls during the first 4 h of exposure to 0.