Targeting Protein Tyrosine Kinase 6 Enhances Apoptosis of Colon Cancer Cells Following DNA Damage
Menée sur des lignées cellulaires de cancer du côlon, cette étude suggère l'intérêt d'une inhibition de la protéine tyrosine kinase PTK6, en combinaison avec une chimiothérapie ou une radiothérapie, pour induire une apoptose des cellules cancéreuses sans mutations de p53
Protein Tyrosine Kinase 6 (PTK6) is an intracellular tyrosine kinase that has distinct functions in normal epithelia and cancer. It is expressed primarily in nondividing epithelial cells in the normal intestine where it promotes differentiation. However after DNA damage, PTK6 is induced in proliferating progenitor cells where it contributes to apoptosis. We examined links between PTK6 and the tumor suppressor p53 in the isogenic p53+/+ and p53-/- HCT116 colon tumor cell lines. We found that p53 promotes expression of PTK6 in HCT116 cells, and shRNA-mediated knockdown of PTK6 leads to reduced induction of the CDK inhibitor p21. Knockdown of PTK6 enhances apoptosis in HCT116 cells with wild type p53, following treatment of cells with γ-radiation, doxorubicin, or 5-fluorouracil. No differences in activation of AKT, ERK1/2, or ERK5, known PTK6 regulated prosurvival signaling proteins, were detected. However, activity of STAT3, a PTK6 substrate, was impaired in cells with knockdown of PTK6 following DNA damage. In contrast to its role in the normal epithelium following DNA damage, PTK6 promotes survival of cancer cells with wild type p53 by promoting p21 expression and STAT3 activation. Targeting PTK6 in combination with use of chemotherapeutic drugs or radiation may enhance death of colon tumor cells with wild type p53.
http://mct.aacrjournals.org/content/early/2012/09/18/1535-7163.MCT-12-0009.abstract