Appropriate Modulation of Autophagy Sensitizes Malignant Peripheral Nerve Sheath Tumor Cells to Treatment With Imatinib Mesylate

作者：Okano Munehiro; Sakata Naoki^*; Ueda Satoshi; Takemura Tsukasa

来源：Journal of Pediatric Hematology/Oncology, 2014, 36(3): 200-211.

DOI：10.1097/MPH.0000000000000038

• malignant peripheral nerve sheath tumor
• imatinib mesylate
• platelet-derived growth factor receptor
• autophagy

Malignant peripheral nerve sheath tumor (MPNST), very rare in childhood, is a highly aggressive soft-tissue tumor. We experienced a case of a 7-year-old boy with MPNST who was treated with imatinib mesylate (imatinib) after the identification of platelet-derived growth factor receptor expression in his tumor. We were unable to observe clinical benefits of imatinib in this patient. Therefore, cellular reactions of imatinib were investigated in vitro using 3 MPNST cell lines. Imatinib induced cytotoxicity in vitro with variable IC50 values (11.7 to >30 M). Induction of apoptosis was not a pivotal mechanism in the inhibitory effects. We found that the treatment of MPNST cell lines with imatinib induced autophagy. Suppression of the initiation of autophagy by 3-methyladenine or small interfering RNA (siRNA) against beclin-1 attenuated the imatinib-mediated cytotoxicity. In contrast, blocking the formation of autophagosomes or the development of autolysosomes using siRNA against microtubule-associated protein light chain 3B, bafilomycin A1, chloroquine, or an MEK1/2 inhibitor (U0126) enhanced the imatinib-induced cytotoxicity in MPNST cells. Our data showed that the imatinib-mediated autophagy can function as a cytotoxic mechanism and that appropriate modulation of autophagy may sensitize MPNST cells to imatinib, which in turn may be a novel therapeutic strategy for MPNST.

• 出版日期2014-4