PhD defence by Carmen Quiñonero López – University of Copenhagen

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PhD defence by Carmen Quiñonero López

Thapsigargin and nortrilobolide are sesquiterpene lactones found in the Mediterranean plant Thapsia garganica L. Thapsigargin is a potent inhibitor of the sarco/endoplasmic reticulum calcium ATPase (SERCA) pump, inducing apoptosis in mammalian cells. Due to its ability to induce apoptosis, thapsigargin has become the active part of a pro-drug (Mipsagargin) for the treatment of different cancer types producing promising results in patients with hepatocellular carcinoma, glioblastoma, prostate cancer and renal cell carcinoma. The thapsigargin-based prodrug has been patented by the American company Inspyr Therapeutics under the name of Mipsagargin. The annual demand for thapsigargin is expected to be 1 ton per year; therefore, there is an increasing need to discover the thapsigargin biosynthesis; and to develop novel production platforms that allow for large scale production.

In this PhD project, I present a review article about the evolution of the bioactive compound thapsigargin produced by Thapsia garganica until the development of the prodrug Mipsagargin (chapter I). Next, in chapter II I have established an alternative production platform for thapsigargin production based on in vitro tissue cultures. In this chapter has been described, from the regeneration of in vitro plants of T. garganica, to the establishment and enhancement of thapsigargins production in temporary immersion bioreactors. A part from an alternative production platform for thapsigargins, in vitro plant tissue cultures techniques have been described for this medicinal species, which can be used for plant genetic conservation and biodiversity. In the chapters II, III and IV, I present studies on the expression levels of the two biosynthetic genes described in the thapsigargin biosynthesis, TgTPS2 and TgCYP76AE2. These studies were performed with T. garganica in vitro plants under stress treatments, with plants growing in the greenhouse and with wild plants. We wanted to understand the complex mechanisms determining the production of thapsigargins in order to transpose this knowledge for futures approaches.

Finally, I was encouraged to genetically transform T. garganica (chapter V). I tried to design an Agrobacterium tumefaciens-mediated transformation protocol. Nevertheless, the performed experiments did not work. It was evident that a bigger investment in time is necessary to achieve Thapsia transformation, but I am confident that it is possible.

Supervisors

Professor Søren Bak
Associate Professor Henrik Toft Simonsen, DTU

Assessment Comittee
Associate Professor Henrik Lütken (Chair)
Professor Pinarosa Avato, University of Bari Aldo Moro, Italy
Vice-President Frederic Bourgaud, Plant Advanced Technologies, Nancy, France

Reception

The defence is followed by a reception in meeting room M117, Thorvaldsensvej 40, first floor.