An experimental trial of cyclic nucleotides on multicellular spheroids derived from human brain tumours.

The effects of cyclic nucleotides, dibutyryl cyclic adenosine monophosphate and dibutyryl cyclic guanosine monophosphate (db-cAMP and db-cGMP), on the growth rate of multicellular tumour spheroids were evaluated by comparing the growth delay and colony forming efficiency in vitro. Multicellular tumour spheroids were derived directly from human brain tumours. To compare the chemotherapeutic effect of cyclic nucleotides, CCNU was used as a known effective cytotoxic drug on malignant gliomas. Significant growth delay was obtained by db-cAMP (p less than 0.001) while CCNU was tumouricidal rather then producing a delay in growth of the tumour spheroids. Db-cGMP found not to be effective in decreasing the growth rate of the tumour spheroids in vitro (p greater than 0.2). The role of cyclic nucleotides in brain tumours is discussed on a review basis.