Effect of chemical modification on the ability of pyrrolidinium fullerene to induce apoptosis of cells transformed by JAK2 V617F mutant

•Pyrrolidinium fullerene induces apoptosis of cells transformed by the JAK2 mutant.•Pyrrolidinium fullerene inhibits the ASK1-MKK4/7-JNK pathway.•Introduction of butyl group improves the ability of fullerene to induce apoptosis.•Introduction of butyl group to fullerene potently inhibits the ASK1-MKK4/7-JNK pathway.

JAK2 V617F mutant, a gene responsible for human myeloproliferative neoplasms (MPNs), causes not only cellular transformation but also resistance to various anti-cancer drugs. We previously reported that pyrrolidinium fullerene markedly induced the apoptosis of JAK2 V617F mutant-induced transformed cells through the reduction of apoptosis signal-regulating kinase 1 (ASK1), following inhibition of the c-Jun N-terminal kinase (JNK) pathway. In the current study, we found that the replacement of the 2-hydrogen atom (H) or N-methyl group (CH3) by the butyl group (C4C9) caused the more than 3-fold potent cytotoxic effects on cells transformed by the JAK2 V617F mutant. Strikingly, these chemical modification of pyrrolidinium fullerene resulted in more marked reduction of ASK1 protein and a more potent inhibitory effect on the JNK signaling cascade. On the other hand, when modified with a longer alkyl group, the derivatives lacked their cytotoxicity. These observations clearly indicate that the modification of pyrrolidinium fullerene with a suitable length of alkyl group such as butyl group enhances its apoptotic effect through inhibition of the ASK1-MKK4/7-JNK pathway.