Paclitaxel treatment of breast cancer cell lines modulates Fas/Fas ligand expression and induces apoptosis which can be inhibited through the CD40 receptor.
OBJECTIVE
Cytotoxic chemotherapy of advanced breast cancer is frequently complicated by drug resistance. Our goal was to define the role of the apoptosis-regulating receptors Fas (CD95) and CD40 in the chemosensitivity of breast cancer.


METHODS
The sensitivity of four breast cancer cell lines to paclitaxel and mitoxantrone was evaluated using an ATP-based cell viability assay. After verification of apoptosis by annexin V staining and TUNEL assay, cell lines were characterized regarding their constitutive expression of both surface and soluble (s)Fas (CD95) and Fas ligand (Fas-L). The role of the Fas/Fas-L system and different caspases was assessed by blocking drug-mediated apoptosis with specific antibodies. Finally, the paclitaxel sensitivity of the CD40-negative cell line KS was compared to that of its CD40-positive transfectant KS-CD40.


CONCLUSIONS
While the cytotoxic effect of mitoxantrone did not correlate with Fas expression, the results presented here suggest some involvement of the Fas/Fas-L system in paclitaxel-induced apoptosis. Cell lines with constitutive expression of Fas/sFas demonstrated a higher sensitivity to paclitaxel than Fas-negative cells. Incubation with paclitaxel led to a measurable downregulation of the expression of both soluble and surface Fas receptor in these cells. Interestingly, stimulation of the CD40 receptor inhibited paclitaxel-induced apoptosis in the transfected cell line KS-CD40, suggesting a role of this receptor in the modulation of chemosensitivity.
Stumm
Susanne
S
Department of Gynecology, University of Heidelberg, Heidelberg, Germany.
Meyer
Anke
A
Lindner
Matthias
M
Bastert
Gunter
G
Wallwiener
Diethelm
D
Gückel
Brigitte
B
D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism*; D023201:CD40 Ligand / Q000187:drug effects* / Q000378:metabolism; D045744:Cell Line, Tumor; D004797:Enzyme-Linked Immunosorbent Assay; D053222:Fas Ligand Protein; D005260:Female; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D008562:Membrane Glycoproteins / Q000187:drug effects* / Q000378:metabolism; D017239:Paclitaxel / Q000494:pharmacology*; D014162:Transfection; D019014:fas Receptor / Q000187:drug effects* / Q000378:metabolism
D000972:Antineoplastic Agents, Phytogenic; C505661:FASLG protein, human; D053222:Fas Ligand Protein; D008562:Membrane Glycoproteins; D019014:fas Receptor; D023201:CD40 Ligand; D017239:Paclitaxel