A B S T R A C T PurposeLess than 20% of patients with melanoma who undergo sentinel lymph node (SLN) biopsy based on American Society of Clinical Oncology/Society of Surgical Oncology recommendations are SLN positive. We present a multi-institutional study to discover new molecular risk factors associated with SLN positivity in thin and intermediate-thickness melanoma. Patients and MethodsGene clusters with functional roles in melanoma metastasis were discovered by next-generation sequencing and validated by quantitative polymerase chain reaction using a discovery set of 73 benign nevi, 76 primary cutaneous melanoma, and 11 in-transit melanoma metastases. We then used polymerase chain reaction to quantify gene expression in a model development cohort of 360 consecutive thin and intermediate-thickness melanomas and a validation cohort of 146 melanomas. Outcome of interest was SLN biopsy metastasis within 90 days of melanoma diagnosis. Logic and logistic regression analyses were used to develop a model for the likelihood of SLN metastasis from molecular, clinical, and histologic variables. Results ITGB3, LAMB1, PLAT, and TP53 expression were associated with SLN metastasis. The predictive ability of a model that included these molecular variables in combination with clinicopathologic variables (patient age, Breslow depth, and tumor ulceration) was significantly greater than a model that only considered clinicopathologic variables and also performed well in the validation cohort (area under the curve, 0.93; 95% CI, 0.87 to 0.97; false-positive and false-negative rates of 22% and 0%, respectively, using a 10% cutoff for predicted SLN metastasis risk). ConclusionThe addition of cell adhesion-linked gene expression variables to clinicopathologic variables improves the identification of patients with SLN metastases within 90 days of melanoma diagnosis. J Clin Oncol 33:2509-2515. © 2015 by American Society of Clinical Oncology INTRODUCTIONThe identification of metastatic disease to regional lymph nodes in patients who present with cutaneous melanoma remains a challenge despite advances in imaging, molecular genetics, and cancer cell biology. Sentinel lymph node (SLN) biopsy is an established technique for nodal staging with therapeutic implications 1,2 Recommendations on when to use an SLN biopsy are based on clinicopathologic variables, including Breslow depth, mitotic rate, and tumor ulceration. [3][4][5] Morton et al 1,2 reported that 122 (16.0%) of 770 patients with intermediatethickness (Breslow depth of 1.2 to 3.5 mm) melanoma who underwent SLN biopsy had nodal metastasis. Moreover, the Sentinel Lymph Node Working Group reported that among 1,250 patients with thin melanoma (Յ 1 mm Breslow depth) who had an SLN biopsy, 65 (5.2%) had nodal metastasis. 6 Attempts to improve identification of patients at risk for SLN positivity using additional histopathologyderived variables have been largely unsuccessful. [3][4][5][6][7][8][9] Changes in cell adhesion, specifically the remodeling of integrin-linked cell adhesion ...

Focal adhesion kinase (FAK) is a nonreceptor tyrosine kinase involved in development and human disease, including cancer. It is currently thought that the four-point one, ezrin, radixin, moesin (FERM)-kinase domain linker, which contains autophosphorylation site tyrosine (Y) 397, is not required for in vivo FAK function until late midgestation. Here, we directly tested this hypothesis by generating mice with FAK Y397-to-phenylalanine (F) mutations in the germline. We found that Y397F embryos exhibited reduced mesodermal fibronectin (FN) and osteopontin expression and died during mesoderm development akin to FAK kinase-dead mice. We identified myosin-1E (MYO1E), an actin-dependent molecular motor, to interact directly with the FAK FERM-kinase linker and induce FAK kinase activity and Y397 phosphorylation. Active FAK in turn accumulated in the nucleus where it led to the expression of osteopontin and other FN-type matrix in both mouse embryonic fibroblasts and human melanoma. Our data support a model in which FAK Y397 autophosphorylation is required for FAK function in vivo and is positively regulated by MYO1E.focal adhesion | myosin | fibronectin | melanoma | cancer F ocal adhesion kinase (FAK) is a nonreceptor tyrosine kinase involved in many biological processes, ranging from mesoderm development to cancer cell metastasis (1). FAK localizes to focal adhesions (2), where it becomes part of a multiprotein complex that links the extracellular matrix (ECM) to the intracellular actin cytoskeleton. FAK is also found in the nucleus, where it is believed to relay information from the cell cortex (3) and induce transcriptional changes (4). The domain architecture of FAK comprises a four-point one, ezrin, radixin, moesin (FERM) domain that is separated from a C-terminal catalytic kinase domain by the FERM-kinase linker. FAK kinase-dead (5) embryos die with mesodermal defects during late gastrulation. In contrast, mice with conditional FAK deletions in the epidermis (6) or breast epithelium (7) show resistance to carcinogenesis.Although FAK has important biological functions, the mechanisms regulating its activity are incompletely understood. For example, it is unclear whether the FERM-kinase linker that contains autophosphorylation site tyrosine (Y) 397 is required for FAK activity in vivo (8). In its closed, inactive conformation, the FAK kinase domain is autoinhibited through interaction with the N-terminal FERM domain. Y397 is nonphosphorylated (9). Upon activation by tethering (10) or other stimuli that induce conformational change (11), the linker region is exposed and Y397 becomes autophosphorylated, leading to the recruitment of the protooncogene SRC. FAK and SRC then form a transient complex, which stabilizes FAK in its active conformation and induces changes in cell shape and focal adhesion turnover in vitro (12). However, mice with a 19-aa deletion in the FAK linker that includes Y397 develop normally until midgestation (8).Here, we have mechanistically discerned the contributions of Y397 to FAK function in viv...