When non-transformed epithelial cells are removed from the extracellular matrix, they undergo apoptosis in an integrin and focal adhesion kinase (FAK) dependent manner. This process has been termed """"""""anoikis"""""""". The growth and migratory factor, hepatocyte growth factor/ scatter factor (HGF/SF) can inhibit anoikis. Anoikis prevents normal epithelial cells, which may detach from the ECM, from remaining viable under anchorage-independent conditions. However, invasive and metastatic tumor cells do not undergo anoikis. An understanding of the mechanism of a transformed cell's resistance to anoikis will lead to valuable insight into the molecular basis of metastasis. The purpose of this proposal is to examine potential molecular mechanisms leading to the metastasis of oral squamous cell carcinomas. I propose to study the influence of the ECM and HGF/SF on the survival of normal and transformed oral keratinocytes. I hypothesize that degradation of FAK is a key event in anoikis and FAK levels in non transformed cells are tightly regulated by the extracellular matrix and growth factors such as HGF/SF. Transformed cells are resistant to anoikis because they accumulate abnormal amounts of FAK even under anchorage-independent conditions. As first steps in testing this idea, I propose to: 1) Examine the influence of ECM and HGF/SF on the half-life of FAK mRNA and protein in normal and transformed oral keratinocytes using standard biochemical assays 2) Determine if non-transformed oral keratinocytes are capable of accumulating FAK and, if so, whether FAK accumulation is sufficient to inhibit anoikis. B. Determine if FAK inhibition using a dominant negative version of FAK is sufficient to restore anoikis to transformed keratinocytes. Normal human keratinocytes will be transfected with """"""""tagged""""""""-FAK allowing us to differentiate endogenous from exogenous FAK. This will allow us to determine whether normal cells place controls on the amount of expressed FAK. If normal cells can accumulate FAK, we will determine if FAK accumulation will protect these cells from anoikis. We will also determine whether expression of FRNK, a dominant negative inhibitor of FAK function, can restore anoikis to transformed cells. This work will allow us to examine a potential mechanism leading to anchorage dependent cell growth. An understanding of the molecular events controlling anchorage independence will have a great impact on the control and treatment of metastatic cancers.
| Kornberg, Lori; Fleigel, Jeffery (2003) The effects of inducible overexpression of FAK-related non-kinase (FRNK) on a transformed epithelial cell line. Anticancer Res 23:91-7 |
| Fleigel, Jeffery; Sedwick, Jack; Kornberg, Lori J (2002) Hepatocyte growth factor/scatter factor stimulates mitogenesis and migration of a head and neck squamous cell carcinoma cell line. Otolaryngol Head Neck Surg 127:271-8 |
