Functional loss of ATRX and telomerase activates Alternative Lengthening of Telomeres (ALT). Functional loss of ATRX and telomerase activates Alternative Lengthening of Telomeres (ALT)

The presence of ALT is strongly associated with recurrent cancer-specific somatic inactivating mutations in the ATRX-DAXX chromatin remodeling complex. Here, we generate an ALT-positive adenocarcinoma cell line following functional inactivation of ATRX and telomerase in a telomerase-positive carcinoma cell line. Overall design: We used the CRISPR Cas9 nickase system to generate multiple ATRXKO clones in LAPC4 and CWR22Rv1. We used previously designed gRNAs that targeted the ATRX-DNMT3-DNMT3L (ADD) domain of ATRX. We generated three independent isogenic KO clones derived from LAPC-4 (LAPC-4 ATRXKO 1-3) and CWR22Rv1 (CWR22Rv1 ATRXKO 1-3) with sequence-confirmed frameshift mutations in ATRX and disrupted ATRX protein expression.