Combination chemotherapy of paclitaxel and cisplatin induces apoptosis with Bcl-2 phosphorylation in a cisplatin-resistant human epidermoid carcinoma cell line

• Published in: Cancer chemotherapy and pharmacology Vol. 51; no. 6; pp. 505 - 511
• Main Authors: SAWADA, Seiji, MESE, Hiroshi, SASAKI, Akira, YOSHIOKA, Norie, MATSUMURA, Tomohiro
• Format: Journal Article
• Language: English
• Published: Berlin Springer 01-06-2003; Springer Nature B.V
• Subjects: Antineoplastic agents; Antineoplastic Agents - pharmacology; Antineoplastic Agents, Phytogenic - pharmacology; Apoptosis - drug effects; Biological and medical sciences; Blotting, Western; Carcinoma, Squamous Cell - drug therapy; Carcinoma, Squamous Cell - pathology; Caspase 3; Caspases - metabolism; Cell Cycle - drug effects; Chemotherapy; Cisplatin - pharmacology; DNA Fragmentation; Drug Resistance, Neoplasm; Enzyme-Linked Immunosorbent Assay; Flow Cytometry; Humans; Medical sciences; Paclitaxel - pharmacology; Pharmacology. Drug treatments; Phosphorylation; Proto-Oncogene Proteins c-bcl-2 - metabolism; Tumor Cells, Cultured; Antineoplastic agent; Phosphorylation; Taxane derivatives; Established cell line; Paclitaxel; Mechanism of action; Antimitotic; Tumor cell; Protooncogene; Platinum II Complexes; Cisplatin (CDDP); Human; Drug combination; Squamous cell carcinoma; Malignant tumor; In vitro; Biological activity; Cisplatin; Resistance; Bcl-2 phosphorylation; Alkylating agent; Cisplatin-resistant; Cell death; C-Onc gene; Paclitaxel (TXL); Apoptosis
• ISSN: 0344-5704; 1432-0843
• DOI: 10.1007/s00280-003-0614-z

Paclitaxel (Taxol, TXL) is an antimicrotubule agent that stabilizes microtubules, arrests the cell cycle at the G(2)/M phase and induces apoptosis. In vitro drug sensitivity assays have shown that the combination of TXL and CDDP is more effective in CDDP-resistant ovarian carcinoma cell lines, with different cytotoxicities depending on the sequence of drug exposure. CDDP also shows poor results in human epidermoid carcinoma particularly of the head and neck region.
We investigated the effects and the molecular mechanisms of combination chemotherapy with TXL and CDDP in the CDDP-resistant cell line A431/CDDP2, and in its parental human epidermoid cell line A431/P. Drug sensitivity was determined using the MTS assay and cell cycle perturbation was analyzed using flow cytometry. DNA fragmentation was then analyzed and the protein levels of caspase-3 and Bcl-2, and phosphorylated of Bcl-2 were determined by Western blotting.
In the drug sensitivity assay, exposure to CDDP prior to TXL was more effective than exposure TXL prior to CDDP in A431/P cells. In A431/CDDP2 cells, exposure to TXL prior to CDDP was more effective than exposure to CDDP prior to TXL. Exposure to TXL arrested the cells in the G(2)/M phase in both cell lines. In A431/CDDP2 cells, exposure to TXL prior to CDDP arrested the cells in the G(2)/M phase, an effect caused by either CDDP or TXL. Analysis of DNA fragmentation showed similar results to the drug sensitivity assay. Expression of caspase-3 protein active form was detected following exposure to TXL only and to the TXL/CDDP combination in both A431/P and A431/CDDP2 cells, but phosphorylation of Bcl-2 protein was detected only following exposure to TXL and only in A431/CDDP2 cells.
These results indicate that exposure to TXL prior to CDDP plays a key role in circumventing CDDP resistance by phosphorylating Bcl-2 protein in the human epidermoid carcinoma cell line A431/CDDP2.