title: Cucurbitacin B induces rapid depletion of the G-actin pool through reactive oxygen species-dependent actin aggregation in melanoma cells.
abstract: Cucurbitacin B (CuB), a triterpenoid compound isolated from Cucurbitaceae plants, has been reported as a promising anti-cancer agent, yet its action mechanism is still controversial. In this study, we explored the potential mechanism of CuB in murine B16F10 melanoma cells. Anti-proliferation and anti-invasion effects were assessed in cultured cells, and in vivo anti-tumor activity was evaluated in a murine subcutaneous melanoma model. Flow cytometry was adopted to analyze cell cycle distribution and reactive oxygen species (ROS) levels. Actin levels were determined by western blot analysis, and the profiles of differential expressed proteins were identified by a quantitative proteomic approach. The results showed that CuB exerted inhibitory effects on cell proliferation, colony formation, as well as migration and invasion potential of the melanoma cells. The growth of subcutaneous melanoma was significantly inhibited in mice treated with CuB when compared with control group. Furthermore, CuB treatment caused rapid cell membrane blebbing and deformation, and induced G(2)/M-phase arrest and formation of multiploid cells. Notably, the G-actin pool was rapidly depleted and actin aggregates were formed quickly after CuB treatment. A number of cytoskeleton-regulatory proteins were differentially regulated. Blockage of ROS production significantly reduced the G-actin depletion ability and the anti-tumor activity of CuB. These findings indicate that CuB induces rapid depletion of the G-actin pool through ROS-dependent actin aggregation in melanoma cells, which may at least partly account for its anti-tumor activity.
authors.affiliation: Institute of Tissue Transplantation and Immunology, Jinan University, Guangzhou, China.
authors.forename: Yanting
authors.initials: Y
authors.lastname: Zhang
authors.forename: Dongyun
authors.initials: D
authors.lastname: Ouyang
authors.forename: Lihui
authors.initials: L
authors.lastname: Xu
authors.forename: Yuhua
authors.initials: Y
authors.lastname: Ji
authors.forename: Qingbing
authors.initials: Q
authors.lastname: Zha
authors.forename: Jiye
authors.initials: J
authors.lastname: Cai
authors.forename: Xianhui
authors.initials: X
authors.lastname: He
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000627:therapeutic use*; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D005260:Female; D008546:Melanoma, Experimental / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D009361:Neoplasm Invasiveness; D017382:Reactive Oxygen Species / Q000378:metabolism; D014315:Triterpenes / Q000627:therapeutic use*
chemical_list: D000199:Actins; D000972:Antineoplastic Agents, Phytogenic; D017382:Reactive Oxygen Species; D014315:Triterpenes; C041246:cucurbitacin B