TY - JOUR
T1 - DNA copy number aberrations in small-cell lung cancer reveal activation of the focal adhesion pathway
AU - Ocak, S.
AU - Yamashita, H.
AU - Udyavar, A. R.
AU - Miller, A. N.
AU - Gonzalez, A. L.
AU - Zou, Y.
AU - Jiang, A.
AU - Yi, Y.
AU - Shyr, Y.
AU - Estrada, L.
AU - Quaranta, V.
AU - Massion, P. P.
N1 - Funding Information:
We thank Kathy Taylor, Director of the Research Institute at St Thomas Health Services, Nashville, TN, for sharing archived SCLC tissue blocks; Dr Coe for providing array CGH data (Coe et al., 2006); and Vanderbilt’s Immunohistochemistry Core (supported by a Cancer Center Support Grant 5P30 CA068485) for their contribution. We also thank Steven K Hanks, Alissa M Weaver and Donna J Webb for their useful input in the interpretation of the paper. This work was supported by a Merit Review grant from the Department of Veterans Affairs. Dr Ocak was supported by an IASLC Young Investigator Fellowship Award and by a grant from Université Catholique de Louvain (Bourse Clinicien-Chercheur), Belgium.
PY - 2010/12/2
Y1 - 2010/12/2
N2 - Small-cell lung cancer (SCLC) is the most aggressive subtype of lung cancer in its clinical behavior, with a 5-year overall survival as low as 5%. Despite years of research in the field, molecular determinants of SCLC behavior are still poorly understood, and this deficiency has translated into an absence of specific diagnostics and targeted therapeutics. We hypothesized that tumor DNA copy number alterations would allow the identification of molecular pathways involved in SCLC progression. Array comparative genomic hybridization was performed on DNA extracted from 46 formalin-fixed paraffin-embedded SCLC tissue specimens. Genomic profiling of tumor and sex-matched control DNA allowed the identification of 70 regions of copy number gain and 55 regions of copy number loss. Using molecular pathway analysis, we found a strong enrichment in these regions of copy number alterations for 11 genes associated with the focal adhesion pathway. We verified these findings at the genomic, gene expression and protein level. Focal Adhesion Kinase (FAK), one of the central genes represented in this pathway, was commonly expressed in SCLC tumors and constitutively phosphorylated in SCLC cell lines. Those were poorly adherent to most substrates but not to laminin-322. Inhibition of FAK phosphorylation at Tyr 397 by a small-molecule inhibitor, PF-573,228, induced a dose-dependent decrease of adhesion and an increase of spreading in SCLC cell lines on laminin-322. Cells that tended to spread also showed a decrease in focal adhesions, as demonstrated by a decreased vinculin expression. These results support the concept that pathway analysis of genes in regions of copy number alterations may uncover molecular mechanisms of disease progression and demonstrate a new role of FAK and associated adhesion pathways in SCLC. Further investigations of FAK at the functional level may lead to a better understanding of SCLC progression and may have therapeutic implications.
AB - Small-cell lung cancer (SCLC) is the most aggressive subtype of lung cancer in its clinical behavior, with a 5-year overall survival as low as 5%. Despite years of research in the field, molecular determinants of SCLC behavior are still poorly understood, and this deficiency has translated into an absence of specific diagnostics and targeted therapeutics. We hypothesized that tumor DNA copy number alterations would allow the identification of molecular pathways involved in SCLC progression. Array comparative genomic hybridization was performed on DNA extracted from 46 formalin-fixed paraffin-embedded SCLC tissue specimens. Genomic profiling of tumor and sex-matched control DNA allowed the identification of 70 regions of copy number gain and 55 regions of copy number loss. Using molecular pathway analysis, we found a strong enrichment in these regions of copy number alterations for 11 genes associated with the focal adhesion pathway. We verified these findings at the genomic, gene expression and protein level. Focal Adhesion Kinase (FAK), one of the central genes represented in this pathway, was commonly expressed in SCLC tumors and constitutively phosphorylated in SCLC cell lines. Those were poorly adherent to most substrates but not to laminin-322. Inhibition of FAK phosphorylation at Tyr 397 by a small-molecule inhibitor, PF-573,228, induced a dose-dependent decrease of adhesion and an increase of spreading in SCLC cell lines on laminin-322. Cells that tended to spread also showed a decrease in focal adhesions, as demonstrated by a decreased vinculin expression. These results support the concept that pathway analysis of genes in regions of copy number alterations may uncover molecular mechanisms of disease progression and demonstrate a new role of FAK and associated adhesion pathways in SCLC. Further investigations of FAK at the functional level may lead to a better understanding of SCLC progression and may have therapeutic implications.
UR - http://www.scopus.com/inward/record.url?scp=78649878924&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=78649878924&partnerID=8YFLogxK
U2 - 10.1038/onc.2010.362
DO - 10.1038/onc.2010.362
M3 - Article
C2 - 20802517
AN - SCOPUS:78649878924
SN - 0950-9232
VL - 29
SP - 6331
EP - 6342
JO - Oncogene
JF - Oncogene
IS - 48
ER -