Mechanism of paclitaxel resistance in a human prostate cancer cell line, PC3-PR, and its sensitization by cabazitaxel

Paclitaxel (PTX) is a microtubule-targeting drug widely used for the treatment of a variety of cancers. However, drug resistance can emerge after a series of treatments, and this can seriously affect the patient's prognosis. Here, we analyzed the mechanism of PTX resistance using a human prostate cancer cell line, PC3, and its PTX-resistant subline, PC3-PR. Compared with PC3, PC3-PR exhibited some unique phenotypes that might be associated with PTX resistance, including decreased expression of acetylated α-tubulin and the cell cycle regulator p21, and increased expression of βIII tubulin, histone deacetylase 6 (HDAC6), and the anti-apoptotic protein Bcl2. The drug exporters MDR1 and MRP1 were not involved in PTX resistance. Although cabazitaxel (CTX), a novel taxoid, has been reported to overcome PTX resistance, its mechanism of action is unknown. We found that treatment of PC3-PR cells with CTX induced expression of acetylated α-tubulin and p21, but not the related regulators p27, p15, and p16 or the Bcl2 family proteins. The pan-HDAC inhibitors trichostatin A and suberanilohydroxamic acid and the HDAC6-specific inhibitor tubacin inhibited PC3-PR proliferation and increased expression of p21 and acetylated α-tubulin in a manner similar to CTX. Our data shed light on the cellular response to PTX and CTX.

Biochemical and biophysical research communications. 2016 Sep 26 [Epub ahead of print]

Sayaka Sobue, Naoki Mizutani, Yuka Aoyama, Yoshiyuki Kawamoto, Motoshi Suzuki, Yoshinori Nozawa, Masatoshi Ichihara, Takashi Murate

College of Life and Health Sciences, Chubu University, Kasugai, Japan., Division of Molecular Carcinogenesis, Nagoya University Graduate School of Medicine, Nagoya, Japan., Tokai Gakuin University, Kakamigahara, Japan., College of Life and Health Sciences, Chubu University, Kasugai, Japan. Electronic address: .