Somatic mutation of the Peutz-Jeghers syndrome gene, LKB1/STK11, in malignant melanoma

Mutations in LKB1/STK11, a gene mapping to chromosome 19p13.3 and encoding a widely expressed serine/threonine kinase, were recently identified as the cause of Peutz-Jeghers syndrome. Despite the hamartomatous polyps and incr eased cancer risk associated with this syndrome, somatic alterations in LKB 1/STK11 have not been identified in human tumours. Prompted by another feat ure of the syndrome, lentigines of the lips and oral mucosa, we evaluated t he status of LKB1/STK11 expression, deletion, and mutation in cell lines an d tumour samples from 35 patients with sporadic malignant melanoma, Two som atic mutations were identified, a nonsense mutation (Glu170Stop) causing ex on skipping and intron retention, and a missense mutation (Asp194Tyr) affec ting an invariant residue in the catalytic subunit of LKB1/STK11. Our data suggest that LKB1/STK11 may contribute to tumorigenesis in a small fraction of malignant melanomas.