LKB1/STK11 Inactivation Leads to Expansion of Pro-Metastatic Tumor Sub-Population in Melanoma

Germline mutations in LKB1 (STK11) are associated with the Peutz–Jeghers syndrome (PJS), which includes aberrant mucocutaneous pigmentation, and somatic LKB1 mutations occur in 10% of cutaneous melanoma. By somatically inactivating Lkb1 with K-Ras activation (+/- p53 loss) in murine melanocytes, we observed variably pigmented and highly metastatic melanoma with 100% penetrance. LKB1 deficiency resulted in increased phosphorylation of the SRC-family kinase (SFK) YES and the subsequent expansion of a CD24+ cell population which showed increased metastatic behavior in vitro and in vivo relative to isogenic CD24- cells. These results suggest that LKB1 inactivation in the context of RAS activation facilitates metastasis by inducing a SFK-dependent expansion of a pro-metastatic, CD24+ tumor sub-population reference x sample