TY - JOUR
T1 - Focal adhesion kinase silencing augments docetaxel-mediated apoptosis in ovarian cancer cells
AU - Halder, Jyotsnabaran
AU - Landen, Charles N.
AU - Lutgendorf, Susan K.
AU - Li, Yang
AU - Jennings, Nicholas B.
AU - Fan, Dominic
AU - Nelkin, Gina M.
AU - Schmandt, Rosemarie
AU - Schaller, Michael D.
AU - Sood, Anil K.
PY - 2005/12/15
Y1 - 2005/12/15
N2 - Objective: Docetaxel causes cell death through induction of apoptosis; however, cell death characteristics for docetaxel have not yet been fully elucidated. We examined the role of focal adhesion kinase (FAK) cleavage in docetaxel-mediated apoptosis. Methods: FAK degradation after treatment with docetaxel was determined in both taxane-sensitive (HeyA8 and SKOV3) and taxane-resistant (HeyA8-MDRand SKOV3-TR) ovarian cancer cell lines by Western blot analysis. Cell growth was determined with 3- (4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay. FAK-targeting small interfering RNA (siRNA) was used to decrease FAK expression. Apoptosis and caspase activity were determined using commercially available kits. Results: SKOV3 and HeyA8 cell lines were both sensitive to docetaxel (IC50levels, 1-6.2 nmol/L), whereas the SKOV3-TR and HeyA8-MDR cells were resistant (IC50 ≥ 250 nmol/L for both). Docetaxel induced high rates of apoptosis in SKOV3 and HeyA8 cells (84% and 66% apoptosis, respectively) but minimal apoptosis (5-8%) in SKOV3-TR and HeyA8-MDR cells. Similarly, FAK was cleaved in SKOV3 and HeyA8 cells in response to docetaxel treatment but unchanged in the resistant cells. Caspase-3 and caspase-8 activity also increased significantly in docetaxel-treated SKOV3 and HeyA8 cells but not in the taxane-resistant cells. DEVD-fmk (caspase-3 biocker) was able to block both FAK cleavage and apoptosis mediated by docetaxel in SKOV3 and HeyA8 cells. FAK siRNA transfection resulted in 70% to 90% decrease in FAK levels in all cell lines within 72 hours. FAK silencing augmented docetaxel-mediated growth inhibition (5- to 8-fold increase) and apoptosis in both of the taxane-sensitive and taxane-resistant cell lines. Conclusions: Docetaxel induces FAK cleavage, mediated through activation of caspase-3, in taxane-sensitive ovarian cancer cells but not in taxane-resistant cells. The absence of FAK degradation may contribute to cell survival in taxane-resistant cells. FAK silencing promotes the in vitro efficacy of docetaxel in both taxane-sensitive and taxane-resistant cell lines and may serve as a novel therapeutic approach.
AB - Objective: Docetaxel causes cell death through induction of apoptosis; however, cell death characteristics for docetaxel have not yet been fully elucidated. We examined the role of focal adhesion kinase (FAK) cleavage in docetaxel-mediated apoptosis. Methods: FAK degradation after treatment with docetaxel was determined in both taxane-sensitive (HeyA8 and SKOV3) and taxane-resistant (HeyA8-MDRand SKOV3-TR) ovarian cancer cell lines by Western blot analysis. Cell growth was determined with 3- (4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay. FAK-targeting small interfering RNA (siRNA) was used to decrease FAK expression. Apoptosis and caspase activity were determined using commercially available kits. Results: SKOV3 and HeyA8 cell lines were both sensitive to docetaxel (IC50levels, 1-6.2 nmol/L), whereas the SKOV3-TR and HeyA8-MDR cells were resistant (IC50 ≥ 250 nmol/L for both). Docetaxel induced high rates of apoptosis in SKOV3 and HeyA8 cells (84% and 66% apoptosis, respectively) but minimal apoptosis (5-8%) in SKOV3-TR and HeyA8-MDR cells. Similarly, FAK was cleaved in SKOV3 and HeyA8 cells in response to docetaxel treatment but unchanged in the resistant cells. Caspase-3 and caspase-8 activity also increased significantly in docetaxel-treated SKOV3 and HeyA8 cells but not in the taxane-resistant cells. DEVD-fmk (caspase-3 biocker) was able to block both FAK cleavage and apoptosis mediated by docetaxel in SKOV3 and HeyA8 cells. FAK siRNA transfection resulted in 70% to 90% decrease in FAK levels in all cell lines within 72 hours. FAK silencing augmented docetaxel-mediated growth inhibition (5- to 8-fold increase) and apoptosis in both of the taxane-sensitive and taxane-resistant cell lines. Conclusions: Docetaxel induces FAK cleavage, mediated through activation of caspase-3, in taxane-sensitive ovarian cancer cells but not in taxane-resistant cells. The absence of FAK degradation may contribute to cell survival in taxane-resistant cells. FAK silencing promotes the in vitro efficacy of docetaxel in both taxane-sensitive and taxane-resistant cell lines and may serve as a novel therapeutic approach.
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U2 - 10.1158/1078-0432.CCR-05-1728
DO - 10.1158/1078-0432.CCR-05-1728
M3 - Article
C2 - 16361572
AN - SCOPUS:29344471438
SN - 1078-0432
VL - 11
SP - 8829
EP - 8836
JO - Clinical Cancer Research
JF - Clinical Cancer Research
IS - 24
ER -