Genetic attenuation of ALDH1A1 increases metastatic potential and aggressiveness in colorectal cancer

Colorectal cancer ranks third in global incidence and second in cancer mortality. Patient-derived models are irreplaceable for studying tumor biology. We established a human epithelial cell line from a rectal adenocarcinoma overexpressing cancer stem cell marker ALDH1A1, and we investigated the effect of ALDH1A1 knockout on tumor cell traits. The cell line and its CRISPR-Cas9 ALDH1A1 knockouts were characterized by genomic and cytogenetic methods (CNV, WES, RNAseq, karyotype), in vitro (proliferation, response to chemotherapy, migration, invasion, apoptosis), and in vivo methods. We identified the landscape of somatic mutations and copy number alterations in the original tumor and the derived cell line. Genetic attenuation of ALDH1A1 was characterized by an increase in migratory potential and extensive metastatic ability, accompanied by reduced growth of subcutaneous xenografts and alterations in gene expression associated with inhibited proliferation and promoted invasion and metastasis, ultimately resulting in dysregulation of the Wnt signaling pathway. Increased metastatic potential was also confirmed in HT-29 cells after ALDH1A1 genetic attenuation. CRISPR-Cas9-mediated editing led to functional, cellular, and molecular changes confirming the role of ALDH1A1 in colorectal cancer carcinogenesis.