Molecular mechanism underlying the increased risk of colorectal cancer metastasis caused by single nucleotide polymorphisms in LI-cadherin gene
LI-cadherin is a member of the cadherin superfamily. LI-cadherin mediates Ca2+-dependent cell-cell adhesion by forming a homodimer. A previous study reported two single nucleotide polymorphisms (SNPs) in the LI-cadherin-coding gene (CDH17). These SNPs correspond to the amino acid changes of Lys115 to Glu and Glu739 to Ala. Patients with colorectal cancer carrying these SNPs are reported to have a higher risk of lymph node metastasis than patients without the SNPs. Although proteins associated with metastasis have been identified, the molecular mechanisms underlying the functions of these proteins remain unclear, making it difficult to develop effective strategies to prevent metastasis. In this study, we employed biochemical assays and molecular dynamics (MD) simulations to elucidate the molecular mechanisms by which the amino acid changes caused by SNPs in the LI-cadherin-coding gene increase the risk of cancer metastasis. Cell aggregation assays showed that the amino acid changes weakened the LI-cadherin-dependent cell-cell adhesion. In vitro assays demonstrated a decrease in homodimerization tendency due to the mutation of Lys115, and MD simulations suggested an alteration in the intramolecular hydrogen bond network due to the amino acid change. Taken together, our results indicate that the increased risk of lymph node metastasis is due to weakened cell-cell adhesion caused by the decrease in homodimerization tendency.