title: Combined effect of proteasome and calpain inhibition on cisplatin-resistant human melanoma cells.
abstract: Resistance of tumor cells to cisplatin is a common feature frequently encountered during chemotherapy against melanoma caused by various known and unknown mechanisms. To overcome drug resistance toward cisplatin, a targeted treatment using alternative agents, such as proteasome inhibitors, has been investigated. This combination could offer a new therapeutic approach. Here, we report the biological effects of proteasome inhibitors on the parental cisplatin-sensitive MeWo human melanoma cell line and its cisplatin-resistant MeWo(cis1) variant. Our experiments show that proteasome inhibitor treatment of both cell lines impairs cell viability at concentrations that are not toxic to primary human fibroblasts in vitro. However, compared with the parental MeWo cell line, significantly higher concentrations of proteasome inhibitor are required to reduce cell viability of MeWo(cis1) cells. Moreover, whereas proteasome activity was inhibited to the same extent in both cell lines, IkappaBalpha degradation and nuclear factor-kappaB (NF-kappaB) activation in MeWo(cis1) cells was proteasome inhibitor independent but essentially calpain inhibitor sensitive. In support, a calpain-specific inhibitor impaired NF-kappaB activation in MeWo(cis1) cells. Here, we show that cisplatin resistance in MeWo(cis1) is accompanied by a change in the NF-kappaB activation pathway in favor of calpain-mediated IkappaBalpha degradation. Furthermore, combined exposure to proteasome and calpain inhibitor resulted in additive effects and a strongly reduced cell viability of MeWo(cis1) cells. Thus, combined strategies targeting distinct proteolytic pathways may help to overcome mechanisms of drug resistance in tumor cells.
authors.affiliation: Institut fuer Biochemie, Charité-Universitaetsmedizin Berlin, Monbijoustrasse 2, 10117 Berlin, Germany.
authors.forename: Izabela
authors.initials: I
authors.lastname: Młynarczuk-Biały
authors.forename: Heike
authors.initials: H
authors.lastname: Roeckmann
authors.forename: Ulrike
authors.initials: U
authors.lastname: Kuckelkorn
authors.forename: Boris
authors.initials: B
authors.lastname: Schmidt
authors.forename: Sumaira
authors.initials: S
authors.lastname: Umbreen
authors.forename: Jakub
authors.initials: J
authors.lastname: Gołab
authors.forename: Antje
authors.initials: A
authors.lastname: Ludwig
authors.forename: Christina
authors.initials: C
authors.lastname: Montag
authors.forename: Lüder
authors.initials: L
authors.lastname: Wiebusch
authors.forename: Christian
authors.initials: C
authors.lastname: Hagemeier
authors.forename: Dirk
authors.initials: D
authors.lastname: Schadendorf
authors.forename: Peter-M
authors.initials: PM
authors.lastname: Kloetzel
authors.forename: Ulrike
authors.initials: U
authors.lastname: Seifert
mesh_terms: D000179:Acrylates / Q000494:pharmacology; D002073:Butanes / Q000494:pharmacology*; D002154:Calpain / Q000037:antagonists & inhibitors*; D002453:Cell Cycle / Q000187:drug effects; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D019008:Drug Resistance, Neoplasm; D004357:Drug Synergism; D006801:Humans; D020672:I-kappa B Proteins / Q000378:metabolism; D008545:Melanoma / Q000188:drug therapy* / Q000201:enzymology* / Q000473:pathology; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism; D009842:Oligopeptides / Q000494:pharmacology*; D011480:Protease Inhibitors / Q000494:pharmacology*; D061988:Proteasome Inhibitors
chemical_list: D000179:Acrylates; C513723:BSc2118; D002073:Butanes; D015853:Cysteine Proteinase Inhibitors; D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D009842:Oligopeptides; C100442:PD 150606; D011480:Protease Inhibitors; D061988:Proteasome Inhibitors; D000072000:NF-KappaB Inhibitor alpha; D002154:Calpain; D002945:Cisplatin