Combination of panobinostat with ponatinib synergistically overcomes imatinib-resistant CML cells

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• 作者：Yasufumi Matsuda ; Takahiro Yamauchi ; Naoko Hosono ; Kanako Uzui ; Eiju Negoro ; Koji Morinaga ; Rie Nishi ; Akira Yoshida ; Shinya Kimura ; Taira Maekawa and Takanori Ueda
• 刊名：Cancer Science
• 出版年：2016
• 出版时间：July 2016
• 年：2016
• 卷：107
• 期：7
• 页码：1029-1038
• 全文大小：1202K
• ISSN：1349-7006

文摘

The major mechanism of imatinib (IM) resistance of CML is the reactivation of ABL kinase either through BCR-ABL gene amplification or mutation. We investigated the cytotoxicity of a pan-ABL tyrosine kinase inhibitor, ponatinib, and a pan-histone deacetylase inhibitor, panobinostat, against IM-resistant CML cells in vitro. Two different IM-resistant cell lines, K562/IM-R1 and Ba/F3/T315I were evaluated in comparison with their respective, parental cell lines, K562 and Ba/F3. K562/IM-R1 overexpressed BCR-ABL due to gene amplification. Ba/F3/T315I was transfected with a BCR-ABL gene encoding T315I-mutated BCR-ABL. Ponatinib inhibited the growth of both K562/IM-R1 and Ba/F3/T315I as potently as it inhibited their parental cells with an IC₅₀ of 2–30 nM. Panobinostat also similarly inhibited the growth of all of the cell lines with an IC₅₀ of 40–51 nM. This was accompanied by reduced histone deacetylase activity, induced histone H3 acetylation, and an increased protein level of heat shock protein 70, which suggested disruption of heat shock protein 90 chaperone function for BCR-ABL and its degradation. Importantly, the combination of ponatinib with panobinostat showed synergistic growth inhibition and induced a higher level of apoptosis than the sum of the apoptosis induced by each agent alone in all of the cell lines. Ponatinib inhibited phosphorylation not only of BCR-ABL but also of downstream signal transducer and activator of transcription 5, protein kinase B, and ERK1/2 in both K562/IM-R1 and Ba/F3/T315I, and the addition of panobinostat to ponatinib further inhibited these phosphorylations. In conclusion, panobinostat enhanced the cytotoxicity of ponatinib towards IM-resistant CML cells including those with T315I-mutated BCR-ABL.