Target identification and mode of action studies on phyllobilins, natural compounds with effects on cancer cells

• Applicant: Dr. Simone Moser
• Subject Area: Pharmacy
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 448289381

Phyllobilins are tetrapyrrolic natural products that arise from the degradation of chlorophyll, a phenomenom which is primarily associated with the colored leaves of deciduous trees that we observe every autumn. Nevertheless, the mainly occurring breakdown products - the phylloleucobilins- turned out to be colorless. They can, however, be easily converted to phylloxanthobilins and phylloroseobilins – yellow and pink pigments that also occur naturally and contribute to the fall colors of leaves in autumn. Those colored phyllobilins possess interesting properties and are, in contrast to many other natural products, easily accessible. With our preliminary data, we are able to demonstrate anti-cancer activities of phyllobilins, affecting proliferation, apoptosis, and the cell cycle. Based on these observations, we now aim at understanding the functional effects on cancer cells caused by the phyllobilins. In a nutshell, we have compounds for which we observe strong effects on cancer cells, and we now want to clarify how these effects happen. To address this question, we plan to perform un-biased target ID screens, as well as whole proteome and transcriptome analyses to decipher the mode of action. For target identification, a yest-3-hybrid system will be employed to screen phyllobilin probes against human cDNA libraries. In a second approach, complementary to the Y3H system, we will attach the phyllobilin to a solid support and perform affinity chromatography. Affinity chromatography will also be used to validate target proteins identified in the Y3H screen and vice versa. Furthermore, we aim at identifying affected biochemical pathways and networks on the proteome and transcriptome level to find the causalities of the observed cellular effects, thereby elucidating the role of a putative target in the anti-cancer activities of the phyllobilins. For this, we will perform proteome and transcriptome profiling of un-treated cells in comparison to phyllobilin treated cells. Taken together, the research proposed here serves the purpose of identifying a target of the phyllobilins and understanding the link between the interaction of the compound with its target and the cellular effects that are observed. In addition, the identification of affected networks can lead to an explanation of the observed effects even in the case that no direct binding partner of the phyllobilins can be identified, thereby providing a backup plan for understanding the bioactivities of these natural products.

• DFG Programme: Research Grants
• International Connection: Austria