Mini and enhanced CRISPR activators for cancer therapies.

INTRODUCTION: The RNA-guided nuclease Cas9 can be used as a programmable transcription activator, but there is still room for improvement in its effectiveness in eukaryotes, and its potential in cancer genetic therapy has been poorly investigated. OBJECTIVES: We aim to construct optimized CRISPRa tools and detect their potential role in cancer therapy by screening 9aa-TAD. METHODS: We selected a range of transcriptional coactivators for programmable activation and analyzed their effects on the expression of multiple endogenous genes using Flow cytometry and qRT-PCR. In order to improve the activation capacity of the CRISPRa tool, we fused the coactivators with the efficient dCas9-VPR system to construct a new activation system. Utilize RNA-seq to assess the activation specificity of genome-wide. To evaluate the value of the newly constructed activation system in cancer gene therapy, we activated the expression of the tumor suppressor genes PER2 and ZNF382, and performed changes in cancer cell proliferation qRT-PCR and clonal formation analysis. RESULTS: In this study, we screened the NHR module from C. elegans, which demonstrated a high transcription activation capacity with a compact size compared to VP64. We successfully demonstrated its efficiency in activating endogenous genes in mammalian cells. Furthermore, we developed an enhanced fused variant called NHR-VP64-p65-Rta (NVPR), which showed even higher efficiency compared to the previously established VPR module, making it an effective CRISPRa tool. The dCas9-NVPR complex also exhibited high specificity on a genome-wide scale. Finally, we utilized the dCas9-NVPR tool to restore the expression of tumor suppressor genes PER2 and ZNF382, effectively inhibiting the malignant phenotype of cancer cells. CONCLUSION: We have successfully developed and demonstrated a breakthrough CRISPRa tool with promising implications for cancer genetic therapy. This innovation expands the range of available gene editing tools and further validates the immense potential of CRISPR-based approaches in precision medicine.