CryptoGreen

Cryptophycin-1 is a cyclic depsipetide produced by Nostoc cyanobacteria. This cyanobacterial specialized metabolites is an extremely potent antiproliferative agent. However, its use, or the use of close structural analogues, as a therapeutic agent to treat cancers, has been hampered by its substantial toxicity. Fortunately, very recent works have shown that cryptophycin conjugated to internalizing peptides, were more selective and thus presented a reduced toxicity, and were thus particularly interesting drug leads. We propose, in this collaborative project involving three academic laboratories with complementary expertise, to microbiologically produce cryptophycin-1 from a cyanobacterial Nostoc strain cultivated in photo-bioreactors, and to prepare by semisynthesis new conjugates that might serve as drug leads for future anti-cancer drugs. The originality of this project lies in the fact that we shall use a photosynthetic microorganism to produce a high-value-added molecule rather than using a classical organic synthesis. Our primary goal is to replace the chemical synthesis by an environmental-friendly bioprocess. To this end, we propose to optimize the microbiological production of cryptophycin-1 thanks to a thorough study of the production under fine-tuned culture conditions (pH, light, nutrients, nitrogen source, etc.) using photo-bioreactors. Furthermore, we propose to complete the description of the biosynthesis of cryptophycin-1, for which several steps are still obscure (the actual precursor of the cryptohycin synthase is unknown). We will use diverse approaches such as isotopic incorporation studies, enzymology of the polyketide synthases involved in the biosynthesis, to decipher this interesting pathway. We also propose to get a more complete picture of the secondary metabolome of the Nostoc strain by using a combination of high-resolution LC-MS data and a bioinformatic approach to build a fingerprinting model based on molecular networking. Using these modern techniques we hope to better describe the production of cryptophycin-1 ad its close analogs by the Nostoc strain. In addition it might be possible using these powerful technologies, to identify new analogs of cryptophycin-1 that might be potent new anti-cancer drug leads. Lastly, we propose to prepare by semisynthesis new cryptophycin conjugates. These new conjugates will be vectorized using for instance neuropilin ligands to lower the toxicity of the parent molecules by specifically targeting the cancer cells. All these new compounds will be tested on a dedicated screening platform to determine their anti-proliferative properties. The three teams, members of this consortium, have complementary expertise and cover many important fields for the present project: bioprocess applied to the culture of photosynthetic microorganisms, the study of the biosynthesis of cyanobacterial specialized metabolites, expertise in analytical chemistry and in particular in LC-MS derived technologies, metabolomics, medicinal chemistry and natural product chemistry, screening of potential anti-cancer molecules. We believe that we will be able at the end of this three-year program to produce using an environmental-friendly bioprocess new cryptophycin conjugates with promising anti-cancer properties.