Our project stems from biologically owned chemotaxis and the now popular ADC drugs. We found that the chemotaxis of bacteria is due to its own sensor protein, especially Nissle1917, which has a complete sensor-conduction-phoresis system. At the same time, we noticed that solid tumors have some very typical targets, which are the focus of drug development. For example, HER2-positive breast cancer has a HER2 target.
Based on these basic theories, we proposed to establish an ADC drug expression system that is chemotactic to lactate and regulated by lactate. We named our system “HER2 Positive Tumor Stalker.”
In order to accurately realize the expression of lactate trend and ADC drugs, we reviewed a lot of relevant literature and learned about various design methods. We also specifically reviewed the antibody design methods. On the basis of ensuring that the bacterial growth was not exceeded, we conducted the following the design of
One design is to fuse the extramembrane sensing portion of the lactate chemoattractant protein of H. pylori with the transmembrane and intramembrane portions of the serine sensor protein of Nissle1917.
Another option is to retain the extramembrane sensing part and the transmembrane part of the lactate chemoattractant protein and fuse only the serine intramembrane part of Nissle1917.
The transmembrane parts of the two fusion proteins are different, but after modeling analysis, they should have similar effects. Therefore, we will compare these two designs in experiments, measure the effect of chemotaxis, and conduct quantitative experiments based on qualitative experiments to optimize mathematical models and fit curves.
In order to achieve the expression and precise release of ADC drugs, we designed the lactate-regulated promoter PlldR-T7. We linked the SYFP2 protein behind this promoter. It is difficult to directly detect the secretion amount of ADC drugs and promoter strength. This fluorescent protein can characterize the strength of the promoter and indirectly reflect the secretion amount of ADC drugs. Finally, we combined the chemotactic module and the ADC drug module to obtain a complete killing system, which can be directed to high lactic acid areas and induced by different lactic acid concentrations to achieve the regulation of ADC drugs and complete the killing of solid tumors.
We hope that some of our components can be used in more aspects of life, the chemotaxis module can realize environmental detection, and the method of modifying chemotaxis can be applied to many other aspects. Drug development can be applied to more cancer treatments.