FLOW CYTOMETRIC AND ULTRASTRUCTURAL ASPECTS OF THE SYNERGISTIC ANTITUMOR-ACTIVITY OF VITAMIN-C - VITAMIN-K-3 COMBINATIONS AGAINST HUMAN PROSTATIC-CARCINOMA CELLS

Transmission and scanning electron microscopy and flow cytometry were employed to characterize the cytotoxic effects of vitamin C (VC), vita min K-3 (VK3), or VC-VK3 combinations on a human prostate carcinoma ce ll line (DU145) following a 1-h vitamin treatment and a 24-h incubatio n in culture medium. Cells exposed to VC exhibited membranous blebs, a berrant microvillar morphology, mitochondria with swollen cristae and intramitochondrial deposits, as well as nucleoli with segregated compo nents. VK3-treated cells displayed a damaged cytoskeleton and membrane s, a cytoplasm which contained large lumen, condensed polysomes, and s everely damaged mitochondria with residual bodies, and nuclei which ex hibited chromatic condensation, pyknosis, and karyolysis. VC-VK3 -trea ted cells exhibited characteristics consistent with necrosis, i.e. swo llen mitochondria and swollen, achromatic nuclei with marginated chrom atin and intact envelopes, while other cells displayed characteristics consistent with apoptosis, i.e. expulsion of organelle-containing ble bs, margination of nuclear chromatin, and segregation of nucleolar com ponents. Vitamin treatment also decreased DNA synthesis, induced a S/G (2) block in the cell cycle, and resulted in the accumulation of fragm ented DNA. These results suggested that increased oxidative stress, su bsequent membrane damage, and DNA fragmentation were responsible for e nhanced cytotoxicity of the vitamin combination.