Novel action of epidermal growth factor on caspase 3 and its potential as a chemotherapeutic adjunct for neuroblastoma.
OBJECTIVE
We previously reported that epidermal growth factor (EGF) induced cleaved caspase 3 expression and apoptosis in human neuroblastoma cells. We hypothesized that EGF upregulates total caspase 3 expression, thereby enhancing the cytotoxic potency of chemotherapeutic agents.


METHODS
Wild-type (WT) and doxorubicin-resistant (Dox-R) SK-N-SH neuroblastoma cells were incubated with EGF 0 to 250 ng/mL for 24 hours or with 5 ng/mL for 0 to 5 days, and total caspase 3 expression and transcription were determined by immunoblots and reverse transcription and polymerase chain reaction, respectively. Cell proliferation was determined after EGF (5 ng/mL) incubation for 1 to 5 days. Cells incubated with EGF (5 ng/mL) for 24 hours before doxorubicin treatment were used to determine the effect of EGF on cell replication and cleaved caspase 3 expression.


RESULTS
Wild-type and Dox-R cells had maximal total caspase 3 expression after incubation with EGF (5 ng/mL) for 3 and 5 days, respectively, and a corresponding increase in DNA transcription. Treating the cells with or without EGF (5 ng/mL) resulted in similar replication rate. However, cell death was increased by EGF pretreatment and doxorubicin when compared with that by doxorubicin alone (WT, 53% +/- 8%; Dox-R, 44% +/- 9%; P < .05). Cleaved caspase 3 expression was upregulated when cell death was increased.


CONCLUSIONS
Epidermal growth factor upregulates the expression and transcription of total caspase 3 in WT and Dox-R cells in a concentration- and time-dependent manner. Epidermal growth factor pretreatment augments the cytotoxic effect of doxorubicin.
Chiu
Bill
B
Department of Surgery, Children's Memorial Hospital, Northwestern University Feinberg School of Medicine, Chicago, IL 60614, USA.
Mirkin
Bernard
B
Madonna
Mary Beth
MB
D000970:Antineoplastic Agents; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000096:biosynthesis*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D004317:Doxorubicin; D004357:Drug Synergism; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D006801:Humans; D009447:Neuroblastoma / Q000188:drug therapy*; D015854:Up-Regulation
D000970:Antineoplastic Agents; D004815:Epidermal Growth Factor; D004317:Doxorubicin; D053148:Caspase 3