Vitamin C : K3 combinations induce autoschizic cell death in human bladder cancer cell lines

JM Jamison, PhD a, J Gilloteaux, DSc a, DR Neal, BSMT a, PB Calderon, PhD b, HS Taper, MD, PhD b, JL Summers, MD,PhD a

<sup>a Department of Urology, Summa Health System / N.E. Ohio Univ. Coll. of Med, Rootstown, Ohio United States <sup>b Unit of Pharmacokinetics, Metabolism, Nutrition and Toxicology, The Catholic University of Louvain, Brussels, Belgium

AIM: To elucidate the morphological and biochemical changes in bladder cancer cell lines following exposure to vitamin C (VC), vitamin K3 and the vitamin combination. METHODS: The cell viability of five human bladder cancer cell lines was evaluated following administration of the vitamins. Ultrastructural changes as well as cell cycle perturbations and changes in ATP levels, DNA and protein synthesis, thiol levels, oxidative stress, caspase levels, Ca2+ levels and DNases were evaluated in one cell line (T24). RESULTS: The 50% cytotoxic doses of the vitamin combination were 6- to 20-fold lower than for VC or VK3 alone. VC:VK3-treated cells extruded substantial pieces of organelle-free cytoplasm to produce an intact nucleus surrounded by a narrow rim of cytoplasm which contained damaged organelles. Despite mitochondrial damage, tumor cell death was not due to ATP depletion. However, vitamin treatment induced a G1/S block, diminished DNA synthesis, increased hydrogen peroxide (H2O2) production and decreased cellular thiol levels. These effects were prevented by catalase. There was a concurrent 8- to 10-fold decrease in intracellular Ca2+ levels from the mitochondria and at least one other subcellular compartment. Electrophoretic analysis of DNA revealed degradation due to the sequential release of DNase I and II. Caspase levels were not elevated. CONCLUSIONS: Redox cycling of the vitamins increased oxidative stress until it surpassed the reducing ability of cellular thiols and inducedCa2+ release which triggered activation of Ca2+-dependent DNase and led to degradation of DNA. This produced a novel form of cell death called autoschizis in which tumor cells underwent a process of self-morsellation.

KEY WORDS: Ascorbate, Autoschizis, Bladder Cancer, Menadione, Oxidative Stress.

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Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Paris, France; February 9 - 12, 2002; in the section on Prevention.