THE ANTICANCER AGENT PB-100 CONCENTRATES IN THE NUCLEUS AND NUCLEOLI OF HUMAN GLIOBLASTOMA CELLS BUT DOES NOT ENTER NORMAL ASTROCYTES

Abstract

Selectivity of the anticancer agent PB-100 for malignant cells, already demonstrated using cell growth and viability evaluation, is now confirmed by microscopic observations. PB-100 is easily detected inside cells by its yellow color under visible light and by its blue fluorescence; it may be measured in isolated nuclei using its characteristic UV absorbance. After short treatment of human BCNU-resistant glioblastoma cells (U 251) and normal astrocyte controls (CRL 1656), PB-100 accumulates in the malignant cell nucleus, particularly concentrating in the multiple nucleoli and rapidly inducing glioblastoma cell death, whilst, in contrast, the anticancer agent does not even enter normal cells. We had already shown that PB-100 binds to DNA of cancer cells, but not to that of normal cells. In vitro tests described in this report indicate that PB-100 binds to purine bases, but not to pyrimidines, of various ribopolymers and its binding to purine rich nucleic acid stretches is inferred.