A Toolbox of Genetically Engineered E. coli for Precise Targeting and Programmable Elimination of Cancer Cells According to Their Mirna Profile

Early diagnosis and successful treatment of colorectal cancer (CRC), the second most frequent type of cancer, constitute a modern medical challenge. iGEM Greece 2017, an interdisciplinary group of undergraduate students and the very first collegiate team from Greece to take part in the worldwide iGEM competition, aims to design a toolbox that integrates miRNA profile data and the natural propensity of bacteria to colonize cancer tissue, in order to engineer a novel probiotic anti-cancer programmable agent. By modifying the adhesion systems of E. coli (fim genes coding for the type I pili) to achieve selective binding to neoplastic cells with the simultaneous utilization of quorum sensing-based regulatory systems for their propagation in the tumor microenvironment, bacterial invasion into the cancer cells can be achieved via the expression of invasin and listeriolysin O. The end goal is the subsequent transfer of the bacterial genetic load, an RNAi-based synthetic logic circuit that is constructed according to the miRNA differential expression pattern of the cancer tissue and drives cancer cells into apoptosis through RNA interference. The aim of this study is to set the computational basis of the project by utilizing a bioinformatic analysis to identify miRNA differential expression profiles in colorectal cancer and modeling the quorum sensing behavior of the engineered strain while finalizing ongoing work in the wet lab. Experimental results regarding the transformation and efficiency of our bacterial system are expected to be available by the time of the conference due to the competition’s deadlines that we work under. The team’s vision is to advance cancer therapeutics by tuning the bacterial system for individualized therapy and targeting of multiple tumor sites while implementing precise control of cytotoxicity based on the tumor miRNA profile without adverse systemic effects.