Base editing of the mutated TERT promoter inhibits liver tumor growth

Abstract

Background and Aims: Base editing has shown great potential for treating human diseases with mutated genes. However, its potential for treating hepatocarcinoma (HCC) has not yet explored. Approach and Results: We employed adenine base editors (ABEs) to correct a TERT promoter mutation, which frequently occurs in various human cancers, including HCC. The mutated TERT promoter −124 C>T is corrected to −124 C by a single guide (sg) RNA-guided and deactivated Campylobacter jejuni Cas9 (CjCas9)-fused adenine base editor (CjABE). This edit impairs the binding of the ETS (ETS/TCF) transcription factor family, including ETS1 and GABPA, to the TERT promoter, leading to suppressed TERT promoter and telomerase activity, decreased TERT expression and cell proliferation, and increased cell senescence. Importantly, injection of adeno-associated viruses expressing sgRNA-guided CjABE or employment of lipid nanoparticle-mediated delivery of CjABE mRNA and sgRNA inhibits the growth of liver tumors harboring TERT promoter mutations. Conclusions: These findings demonstrate that a sgRNA-guided CjABE efficiently converts the mutated TERT promoter −124 C>T to −124 C in HCC cells and underscore the potential to treat HCC by the base editing-mediated correction of TERT promoter mutations.