title: Proteasome inhibitor PS-341 induces apoptosis through induction of endoplasmic reticulum stress-reactive oxygen species in head and neck squamous cell carcinoma cells.
abstract: PS-341, also known as Velcade or Bortezomib, represents a new class of anticancer drugs which has been shown to potently inhibit the growth and/or progression of human cancers, including head and neck squamous cell carcinoma (HNSCC). Although it has been logically hypothesized that NF-kappaB is a major target of PS-341, the underlying mechanism by which PS-341 inhibits tumor cell growth is unclear. Here we found that PS-341 potently activated the caspase cascade and induced apoptosis in human HNSCC cell lines. Although PS-341 could inhibit NF-kappaB activation, the inhibition of NF-kappaB was not sufficient to initiate apoptosis in HNSCC cells. Using biochemical and microarray approaches, we found that proteasome inhibition by PS-341 induced endoplasmic reticulum (ER) stress and reactive oxygen species (ROS) in HNSCC cells. The inhibition of ROS significantly suppressed caspase activation and apoptosis induced by PS-341. Consistently, PS-341 could not induce the ER stress-ROS in PS-341-resistant HNSCC cells. Taken together, our results suggest that in addition to the abolishment of the prosurvival NF-kappaB, PS-341 might directly induce apoptosis by activating proapoptotic ER stress-ROS signaling cascades in HNSCC cells, providing novel insights into the PS-341-mediated antitumor activity.
authors.affiliation: Laboratory of Molecular Signaling and Apoptosis, Department of Biologic and Materials Sciences, University of Michigan, 1011 N. University Ave., Ann Arbor, MI 48109-1078, USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Fribley
authors.forename: Qinghua
authors.initials: Q
authors.lastname: Zeng
authors.forename: Cun-Yu
authors.initials: CY
authors.lastname: Wang
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001897:Boronic Acids / Q000494:pharmacology*; D000069286:Bortezomib; D002294:Carcinoma, Squamous Cell / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D020869:Gene Expression Profiling; D006258:Head and Neck Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D006801:Humans; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D011480:Protease Inhibitors / Q000494:pharmacology*; D046988:Proteasome Endopeptidase Complex; D061988:Proteasome Inhibitors; D011719:Pyrazines / Q000494:pharmacology*; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D000970:Antineoplastic Agents; D001897:Boronic Acids; D016328:NF-kappa B; D011480:Protease Inhibitors; D061988:Proteasome Inhibitors; D011719:Pyrazines; D017382:Reactive Oxygen Species; D000069286:Bortezomib; D020169:Caspases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease