Establishment of an miR-137-knockout cell model using CRISPR/Cas9 genome editing

MicroRNA-137 (miR-137) has been reported to be abnormally expressed in a variety of types of cancer, including ovarian cancer. However, the roles served by miR-137 in cancer are not fully understood. In the present study, 3 single guide RNAs (sgRNAs) were designed, synthesized and inserted into pXPR001 plasmids. The pXPR001-sgRNA plasmids were verified using sequencing and integrated into the genome of the ovarian cancer cell line, A2780, through lentiviral transduction, puromycin selection and single-cell culture. PCR products amplified from single-cell cultures using primers covering miR-137 targeting sites were sequenced to identify clones with miR-137 gene disruption. Genome editing was detected in 72% of the clones derived from sgRNA2, 4% from sgRNA3 and 0% from sgRNA1. Of the clones from sgRNA2, 32% contained 1 edited miR-137 allele and 40% contained 2 edited miR-137 alleles. The expression of miR-137 in clones #2 and #3 could not be detected by reverse transcription-quantitative polymerase chain reaction. In addition, an MTT assay demonstrated that clones #2 and #3 exhibited enhanced proliferation. In conclusion, an miR-137-knockout cell model was successfully established in A2780 cells using CRISPR/Cas9 technology.