AB111. Synthesizing an AND gate genetic circuit for identification of bladder cancer cells based on CRISPR-Cas9

Background: Because of the lack of an ideal promoter that selectively identifies cancer cells and robustly drives therapeutic gene expression, the conventional strategy for cancer gene therapy offers limited control of specificity and efficacy. A possible way to overcome these limitations is to construct logic circuits capable of integrating cellular information from multiple promoters as inputs.

Methods: Here, we designed and constructed a modular AND gate circuit based on CRISPR-cas9 system through combining the cancer-specific promoter of human telomerase reverse transcriptase (hTERT) gene with the bladder-specific promoter of human uroplakin II gene. The AND gate circuit integrates cellular information from the two promoters as inputs and activates the CMV promoter of output gene repressed by LacI only when both inputs are active in the tested cell lines. The integration occurs via an interaction between the Cas9 protein and sgRNA targeting LacI.

Results: Using the luciferase reporter as the output gene, we have shown that the circuit specifically detected bladder cancer cells and significantly enhanced luciferase expression in comparison to the hTERT-renilla luciferase (Rluc) construct. We also demonstrated the modularity of this circuit by replacing the output with other cellular functional genes including hBAX, p21, and E-cadherin. The circuit effectively inhibited bladder urothelial carcinoma cell growth, induced apoptosis, and decreased cell motility by regulating the corresponding gene.

Conclusions: This approach provides a synthetic biology platform for targeting and controlling bladder cancer.

Keywords: CRISPR-Cas9; bladder cancer; AND gate; genetic circuit