A stop-gain mutation in GXYLT1 promotes metastasis of colorectal cancer via the MAPK pathway.

Genomic instability plays a key role in the initiation and progression of colorectal cancer (CRC). Although cancer driver genes in CRC have been well characterized, identifying novel genes associated with carcinogenesis and treatment remains challenging because of tumor heterogeneity. Here, we analyzed the genomic alterations of 45 samples from CRC patients in northern China by whole-exome sequencing. In addition to the identification of six well-known CRC driver genes (APC, TP53, KRAS, FBXW7, PIK3CA, and PABPC), two tumor-related genes (MTCH2 and HSPA6) were detected, along with RRP7A and GXYLT1, which have not been previously linked to cancer. GXYLT1 was mutated in 40% (18/45) of the samples in our cohort. Functionally, GXYLT1 promoted migration and invasion in vitro and metastasis in vivo, while the GXYLT1 S212* mutant induced significantly greater effect. Furthermore, both GXYLT1 and GXYLT1 S212* interacted with ERK2. GXYLT1 induced metastasis via a mechanism involving the Notch and MAPK pathways, whereas the GXYLT1 S212* mutant mainly promoted metastasis by activating the MAPK pathway. We propose that GXYLT1 acts as a novel metastasis-associated driver gene and GXYLT1 S212* might serve as a potential indicator for therapies targeting the MAPK pathway in CRC.