Quadruple-editing of MAPK and PI3K pathways effectively blocks the progression of KRAS-mutated colorectal cancer cells

Abstract Background Mutated KRAS promotes the activation of mitogen-activated protein kinase (MAPK) pathway and the progression of colorectal cancer (CRC) cells. Aberrant activation of phosphatidylinositol 3‑kinase (PI3K) pathway strongly attenuates the efficacy of MAPK suppression in KRAS-mutated CRC cells. The development of a novel strategy targeting dual-pathway is therefore highly essential for the therapy of KRAS-mutated CRC cells. Methods In this study, a quadruple-depleting system for KRAS, MEK1, PIK3CA, and mammalian target of rapamycin (MTOR) genes based on Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/SaCas9 was developed. Serotype 5 of adenovirus (ADV5) was used as packaging virus for systemic delivery of the CRISPR system. To enhance infection efficiency and specificity of ADV5 to CRC cells and reduce its non-specific tissue tropism, two engineered proteins, an adaptor and a protector were synthesized and formed an ADV-protein complex (APC) when delivered the quadruple-editing system intravenously in vivo. Results The quadruple-editing significantly inhibited MAPK and PI3K pathways in CRC cells with oncogenic mutations of KRAS and PIK3CA or with KRAS mutation and compensated PI3K activation. Compared with MEK and PI3K/MTOR inhibitors, the quadruple-editing induced more significant survival inhibition on primary CRC cells with oncogenic mutations of KRAS and PIK3CA. The adaptor protein which specifically targeting epithelial cell adhesion molecule (EpCAM) could dramatically enhance infection efficiency of ADV5 to CRC cells. and the protector protein could significantly reduce the off-targeting tropisms in a variety of organs. Moreover, the quadruple-editing intravenously delivered by APC significantly blocked dual-pathway and tumor growth, without influencing normal tissues in cell- and patient-derived xenograft models of KRAS-mutated CRC cells. Conclusions APC-delivered quadruple-editing of MAPK and PI3K pathways effectively and specifically blocked the progression of KRAS-mutated CRC cells.