iGEM is an international competition rich in heritage in the field of synthetic biology. Since its establishment in 2003, many experienced teams have demonstrated various wonderful projects. We always want to make some contributions to the future iGEM team, which is one of the driving forces for us to participate in this competition. We’d be more than happy to gain and spread experience in the competition.
With the rapid development of science and technology, the satisfactory treatment of cancers has become the dire desire for both the patients and their families. The successful development and marketing of an anti-cancer drug has cheered the medical community and the patient circle.
We developed RTAC (Rspo-Targeting Anti-cancer Chimeric protein), a novel therapeutic strategy to combat multiple Rspo-induced malignancies. In addition, we created the engineered yeast with self-tunable RTAC delivery to target colon tumors. Due to the severity of precision anti-cancer drugs and the difficulties in their development, we believe that our greatest contribution to the future iGEM teams and the society is to provide the innovative design and proof-of-concept of a novel anti-cancer drug which can potentially be used in clinical treatment.
Dual-targeting is a major feature of our project, which can provide reference for future projects. While RTAC targets RSPO, the engineered yeast can target the colorectal cancer tissue by sensing TME-specific molecules.
Targeting of RTAC: Unlike most targeted drugs that can only target a specific molecule, the RTAC protein we developed can target all members of the RSPO family (RSPO1-4), which is a major advantage. Besides the binding affinity, we also considered the secretion efficiency, flexibility and stability while finalizing RTAC to ensure RTAC is feasibly functional. All these modifications can contribute to the future iGEM teams in their designs of recombinant proteins.
Targeting of R-yeast: As the natural receptor of extracellular ATP (eATP), purinergic receptors can specifically sense eATP and promote tumor growth and progression via the GPCR activity. We employed eATP-purinergic receptors-G protein axis to sense the TME. Through gene editing, we introduced mutant human P2Y2 purinergic receptor and chimeric Gα protein to the engineered S. Cerevisiae. This is an important step of our treatment plan to achieve colon tumor targeting.
This part of our project has made good use of probiotic to release target proteins to designated locations. We believe that the future iGEM team will apply the “dual-targeting” concept to a wider range of aspects.
Mating pathway is one of the best-known signal pathways in eukaryotes, and is often used to express eukaryotic proteins. We have found the application of mating pathway in many iGEM teams in the past, and also learned from their experience.
We genetically removed ste2, and embedded the human P2Y2 receptor and the chimeric yeast Gpa1-human Gαi3 protein to the engineered yeast. And at the transcription level, we engineered RTAC downstream of the mating-responsive transcription factor, pFUS1, as the final outcome of this signaling cascade.
It is believed that the iGEM teams in the future will also improve on the basis of our system to create fancier genetic circuits by modifying yeast mating pathway.
We originally designed and applied the copper ion-dependent kill switches to the engineered yeast to ensure the safety of our experiments and prevent potential biological hazard.
In previous years, many teams also designed kill switches, most of which were in E. coli. We provided a novel paradigm of the kill switch in yeast and provided inspiration and demonstration to the future teams. By changing a few components, the kill switch in our yeasts can be expanded in a variety of situations and developed into more complicated machineries.
We have designed a new part “BBa_K4220100” as an improvement of part “BBa_K2086002”.We improved a kill switch in E. coli (composite part) into one which can function in the yeast by replacing each basic parts into ones which have similar functions in the yeast.
See more in “Improvement”
Our model mainly includes three parts: matching pathway, protein secretion and growth model, which well describes the signal transmission of yeast activation pathway, the secretion of target protein and the change of growth concentration. The establishment of these models proves the feasibility of using yeast as a carrier and promotes our understanding of the microscopic transmission mechanism of pathways. In addition, the establishment of the model is the result of the mutual promotion of wet lab and dry lab. We use the data from the wet lab to establish the model, which guided us to improve the wet lab through the activation effect in the dry lab.
We believe that the future iGEM team can deepen their understanding of yeasts by viewing our model and improve on the basis of our modeling data.
Our IHP has a complete thinking chain and has made detailed planning, which has certain reference significance. Based on the advice and feedbacks from the interviewees and the society, the integrated human practice has constantly inspired us to push the project forward. On the other hand, we have also reciprocally shared our experience and knowledge with different communities and social groups.
Our project can provide a basic template for future iGEM teams (especially for the first time to take part in the competition) to implement the project and promote team cooperation.
See more in “Human Practices”