Alpay Kemal, Farshchian Mehdi, Tuomela Johanna, Sandholm Jouko, Aittokallio Kaappo, Siljamäki Elina, Kallio Marko, Kähäri Veli-Matti, Hietanen Sakari
Department of Obstetrics and Gynecology and Joint Clinical Biochemistry Laboratory of Turku University Hospital, Medicity Research Laboratory, University of Turku, Turku, Finland.
Department of Dermatology and MediCity Research Laboratory, University of Turku and Turku University Hospital, Turku, Finland.
PLoS One. 2014 Aug 22;9(8):e105526. doi: 10.1371/journal.pone.0105526. eCollection 2014.
Although c-Abl has increasingly emerged as a key player in the DNA damage response, its role in this context is far from clear. We studied the effect of inhibition of c-Abl kinase activity by imatinib with chemotherapy drugs and found a striking difference in cell survival after combined mitoxantrone (MX) and imatinib treatment compared to a panel of other chemotherapy drugs. The combinatory treatment induced apoptosis in HeLa cells and other cancer cell lines but not in primary fibroblasts. The difference in MX and doxorubicin was related to significant augmentation of DNA damage. Transcriptionally active p53 accumulated in cells in which human papillomavirus E6 normally degrades p53. The combination treatment resulted in caspase activation and apoptosis, but this effect did not depend on either p53 or p73 activity. Despite increased p53 activity, the cells arrested in G2 phase became defective in this checkpoint, allowing cell cycle progression. The effect after MX treatment depended partially on c-Abl: Short interfering RNA knockdown of c-Abl rendered HeLa cells less sensitive to MX. The effect of imatinib was decreased by c-Abl siRNA suggesting a role for catalytically inactive c-Abl in the death cascade. These findings indicate that MX has a unique cytotoxic effect when the kinase activity of c-Abl is inhibited. The treatment results in increased DNA damage and c-Abl-dependent apoptosis, which may offer new possibilities for potentiation of cancer chemotherapy.
尽管c-Abl在DNA损伤反应中越来越成为关键因素，但其在这种情况下的作用仍远未明确。我们研究了伊马替尼抑制c-Abl激酶活性与化疗药物联合使用的效果，发现与其他一系列化疗药物相比，米托蒽醌（MX）与伊马替尼联合治疗后细胞存活率存在显著差异。联合治疗在HeLa细胞和其他癌细胞系中诱导凋亡，但在原代成纤维细胞中未诱导凋亡。MX和阿霉素的差异与DNA损伤的显著增加有关。转录活性p53在人乳头瘤病毒E6通常降解p53的细胞中积累。联合治疗导致半胱天冬酶激活和凋亡，但这种效应不依赖于p53或p73活性。尽管p53活性增加，但在G2期停滞的细胞在这个检查点出现缺陷，从而允许细胞周期进展。MX治疗后的效应部分依赖于c-Abl：c-Abl的短发夹RNA敲低使HeLa细胞对MX的敏感性降低。c-Abl siRNA降低了伊马替尼的效应，表明无催化活性的c-Abl在死亡级联反应中发挥作用。这些发现表明，当c-Abl的激酶活性被抑制时，MX具有独特的细胞毒性作用。该治疗导致DNA损伤增加和c-Abl依赖性凋亡，这可能为增强癌症化疗提供新的可能性。
