High focal adhesion kinase expression in invasive breast carcinomas is associated with an aggressive phenotype

Focal adhesion kinase ( FAK) is a protein tyrosine kinase expressed in invasive breast cancer that regulates antiapoptotic signaling. We have examined FAK expression by immunohistochemistry using anti- FAK 4.47 in breast tumor samples from a large population- based, case - control study of women participating in the University of North Carolina Breast Specialized Programs of Research Excellence ( SPORE), Carolina Breast Cancer Study. In this population, 629 formalin- fixed, paraffin- embedded tissue sections were stained for FAK and scored as high ( 3+ or 4+ intensity and >= 90% positive cells) or otherwise. High FAK expression was associated with poor prognostic indicators including high mitotic index ( 410 mitoses per 10 consecutive high-power fields), nuclear grade 3, architectural grade 3, estrogen and progesterone receptor negative, and HER- 2/ neu overexpressed using CB11 antibody. The association of high FAK expression with HER- 2/ neu overexpression lends further support that HER- 2/ neu and FAK collaborate to promote tumorigenesis. The presence of strong FAK expression in many high grade, estrogen- and progesterone- negative breast carcinomas indicates that FAK may be an attractive target for therapeutic intervention.