A novel antitumor piperazine alkyl compound causes apoptosis by inducing RhoB expression via ROS-mediated c-Abl/p38 MAPK signaling

Purpose: We investigated the action mechanism of a novel anticancer compound, KR28 (1-allyl-4-dodecanoyl-1-ethyl-piperazin-1-ium; bromide), to induce apoptosis of human prostate carcinoma PC-3 cells. Methods: To explore an apoptotic signaling of KR28, we used ROS assay, SRB assay, flow cytometry analysis, reporter assay, xenograft assay, Western blotting, and RT-PCR analysis. Results: The growth inhibitory action of KR28 is cell line specific, impeding the growth of prostate carcinoma PC-3 and stomach carcinoma NUGC-3 cells. KR28 showed strong antitumor activity in PC-3 mouse xenograft model. KR28 increased ROS production, leading to nuclear c-Abl expression, which in turn activated p38 mitogen-activated protein kinase (MAPK) to enhance the expression of RhoB, an apoptosis inducer. The KR28-induced apoptosis was abrogated by the ROS scavenger N-acetylcysteine and by knockdown of c-Abl, p38 MAPK, or ATF2. Moreover, the p300 binding site and two CCAAT boxes in the RhoB promoter appear to be involved in ROS-mediated RhoB expression in the presence of KR28. Conclusion: The antitumor agent KR28 induces apoptosis of PC-3 cells by ROS-mediated RhoB expression via c-Abl upregulation and activation of p38 MAPK/ATF-2.