Tumor inhibition by metallocenes: ultrastructural localization of titanium and vanadium in treated tumor cells by electron energy loss spectroscopy.

The intracellular distribution patterns of the metal atoms titanium and vanadium after in vivo as well as in vitro treatment of Ehrlich ascites tumor with the antitumor agents titanocene dichloride (TDC) or vanadocene dichloride (VDC) have been investigated by use of electron energy loss spectroscopy (EELS). The metals were found mainly accumulated in the nuclear heterochromatin and, to a minor extent, in the nucleolus and in the cytoplasmic ribosomes. In connection with other experimental results it is argued that this accumulation is indicative of the molecular interaction of the metal-containing species with the nucleic acids, especially with the DNA.