High Frequency of RPL22 Mutations in Microsatellite-Unstable Colorectal and Endometrial Tumors

Ribosomal Protein L22 (RPL22) encodes a protein that is a component of the 60S subunit of the ribosome. Variants in this gene have recently been linked to cancer development. Mutations in an A8 repeat in exon 2 were found in a recent study in 52% of microsatellite-unstable endometrial tumors. These tumors are particularly prone to mutations in repeats due to mismatch repair deficiency. We screened this coding repeat in our collection of microsatellite-unstable endometrial tumors (EC) and colorectal tumors (CRC). We found 50% mutation frequency for EC and 77% mutation frequency for CRC. These results confirm the previous study on the involvement of RPL22 in EC and, more importantly, reports for the first time such high mutation frequency in this gene in colorectal cancer. Furthermore, considering the high mutation frequency found, our data point toward an important role for RPL22 in microsatellite instability carcinogenesis.