Nitric Oxide Production Correlates with Cell Death of Fibroblasts Treated by Bacillus pumilus Ribonuclease

NO is a crucial messenger in tumor cell signaling. High levels of nitric oxide synthase expression may be cytostatic or cytotoxic for tumor cells, whereas low levels can have the opposite effect and promote tumor growth. Bioimaging is a major technique to visualize the nitric oxide level in living cells and to compare it with physiological outcomes. In this report, we used two fluorescent probes, DAA and DAF-FM diacetate, in order to visualize NO levels in normal and ras-transformed fibroblasts treated by the bacterial ribonuclease binase (Bacillus pumilus RNase). To assess selective toxicity of binase towards cells expressing the ras oncogene, a fluorescent live/dead dye was applied. Here we compared the NO levels in normal and ras-transformed fibroblasts to elucidate the role of NO in the apoptotic signaling cascade induced by binase.