TAXANE RECOVERY FROM CELLS OF TAXUS IN MICROGRAVITY AND HYPERGRAVITY

Cell suspension cultures of Taxus cuspidata produce taxanes that are r eleased from the outer surface of cells into the culture medium as fre e and bound alkaloids. Paclitaxel (Taxol(TM)), is an anti-cancer drug in short supply. It has a taxane ring derived from baccatin III and a C-13 phenylisoserine side-chain. This drug is produced over a wide ran ge of gravitational forces. Monoclonal and polyclonal antibodies to pa clitaxel, baccatin III, and the C-13 phenylisoserine side chain were c ombined in multiple-labeling studies to localize taxanes and paclitaxe l on cell surfaces or on particles released into the culture medium. B ioreactor vessel design altered the composition of taxanes recovered f rom cells in simulated microgravity. At 10(-2) and 2.10(-4).g, taxane recovery was reduced but biomass growth and percent paclitaxel was sig nificantly increased. At 1 to 24.g, growth was reduced with a signific ant recovery of total taxanes with low percent paclitaxel. Bound pacli taxel was also localized in endonuclease-rich fragmenting nuclei of in dividual apoptotic cells. A model is presented comprising TCH (touch) genes encoding enzymes that modify taxane-bearing xylan residues in ce ll walls, the calcium-sensing of gravitational forces by the cytoplasm , and the predisposition of nuclei to apoptosis. This integrates the a daptive physiological and biochemical responses of drug-producing geno mes with gravitational forces. (C) 1998 Elsevier Science Ltd. All righ ts reserved.