|Kim, Beum Jun|
Submitted to: Biotechnology Progress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/21/2004
Publication Date: 12/15/2004
Citation: Kim, B., Gibson, D.M., Shuler, M.L. 2004. Effect of subculture and elicitation on instability of taxol production in taxus sp. suspension cultures. Biotechnology Progress. 20:1666-1673. Interpretive Summary: Paclitaxel (Taxol) is a potent chemotherapeutic drug with proven utility against a range of cancers, including lung, breast, and ovarian cancer. The limited supply of this drug from the original tree source prompted the development of alternative sources of production, including the use of plant cell cultures. Taxol derived from plant cell cultures has been commercialized, but work is still needed to understand the underlying mechanisms affecting product formation, particularly with regard to instability of production. This work describes our study to evaluate whether particular subculture treatments and the presence of methyl jasmonate, a known elicitor for taxol production in cell culture, are sources of variability. We report that cell signaling within the culture may be the primary source of variability in production. This study will be useful to understand the overall mechanisms involved in optimizing taxol production in plant cell cultures.
Technical Abstract: The production of secondary metabolites through plant cell suspension cultures is challenging because the level and pattern of production is often unstable and unpredictable. To investigate the factors affecting instability of secondary metabolite production, high Taxol (paclitaxel)-producing Taxus cultures induced by methyl jasmonate elicitation and their low Taxol-producing counterparts were compared with respect to growth and Taxol production kinetics. With Taxus subcultures we observe alternating states of high and low productivity. Parental cultures and their subcultures from five different cell lines were used to test whether a high-producing culture grows more slowly or dies more rapidly than a low-producing one. These cell lines were of three types: (1) Taxol-producing with and without methyl jasmonate, (2) Taxol producing only upon elicitation, and (3) nonproducing. High-producing cultures show growth inhibition upon subculture, whereas nonproducing elicited cultures show little growth inhibition. Thus, growth inhibition is primarily due to Taxol or taxane accumulation and not a direct result of methyl jasmonate treatment. Through media exchange between high- and low-producing cultures, it appears that culture components generated by cells alter culture properties. To assess variability as a function of culture lineage, two groups of replicate cultures were generated either with a mixing of the parental flasks or segregation of parental flasks at each subculture. Although parental culture mixing did not reduce flask-to-flask variation, the production level of Taxol in subcultures resulting from mixing inocula was sustained at a higher level relative to segregated subcultures. The results are consistent with the possibility of cell signaling within the population that can induce Taxol production.