CSTMP induces apoptosis and mitochondrial dysfunction in human myeloma RPMI8226 cells via CHOP-dependent endoplasmic reticulum stress

Background: The natural product tetramethylpyrazine (TMP) and resveratrol have a variety of biologic activities, including anti-cancer effects. However the pharmacological function of CSTMP (a newly designed and synthesized TMP and resveratrol derivative) in cancer have not been elucidated. Methods: In RPMI8226 cells, the cytotoxic effects and apoptosis were detected by MTT and Double staining for Annexin V-FITC and propidium iodide (PI). The protein and mRNA expression levels were detected by Real Time PCR and Western blot, respectively. The localization of cleaved caspase-12 was evaluated by immunofluorescent staining. The activation of caspase were measured by colorimetric assays and Western blot. Results: CSTMP showed significantly cytotoxic effects and induced apoptosis in RPMI8226 cells. Caspase activation, Cytochrome c release and Bax, Bcl-2 and Bcl-XL levels analyses demonstrated that the anticancer effect of CSTMP in RPMI8226 cells was mediated by promoting caspase-and mitochondria-dependent apoptosis. In addition, CSTMP induced the increased expression of endoplasmic reticulum (ER) stress related proteins (CHOP, GRP78, GRP94 and cleaved caspase-12) and the activation of multiple branches of ER stress transducers (PERK-eIF2 alpha, IRE1 alpha and ATF6). Moreover, knockdown of CHOP by siRNA markedly inhibited CSTMP-induced cytotoxic effects, caspases activity and mitochondrial dysfunction in RPMI8226 cells. Conclusions: Our results indicated that CSTMP could induce apoptosis and mitochondrial dysfunction in RPMI8226 cells via CHOP-dependent ER stress. (C) 2016 Elsevier Masson SAS. All rights reserved.