A revolutionary tool: CRISPR technology plays an important role in construction of intelligentized gene circuits.

With the development of synthetic biology, synthetic gene circuits have shown great applied potential in medicine, biology, and as commodity chemicals. An ultimate challenge in the construction of gene circuits is the lack of effective, programmable, secure and sequence-specific gene editing tools. The clustered regularly interspaced short palindromic repeat (CRISPR) system, a CRISPR-associated RNA-guided endonuclease Cas9 (CRISPR-associated protein 9)-targeted genome editing tool, has recently been applied in engineering gene circuits for its unique properties-operability, high efficiency and programmability. The traditional single-targeted therapy cannot effectively distinguish tumour cells from normal cells, and gene therapy for single targets has poor anti-tumour effects, which severely limits the application of gene therapy. Currently, the design of gene circuits using tumour-specific targets based on CRISPR/Cas systems provides a new way for precision cancer therapy. Hence, the application of intelligentized gene circuits based on CRISPR technology effectively guarantees the safety, efficiency and specificity of cancer therapy. Here, we assessed the use of synthetic gene circuits and if the CRISPR system could be used, especially artificial switch-inducible Cas9, to more effectively target and treat tumour cells. Moreover, we also discussed recent advances, prospectives and underlying challenges in CRISPR-based gene circuit development.