title: Increased carcinogenic potential of myeloid tumor cells induced by aberrant TGF-beta1-signaling and upregulation of cathepsin B.
abstract: The TGF-beta signaling pathways are implicated in cancer. Cysteine cathepsins can contribute to the carcinogenic potential of tumor cells. The aim of this study was to investigate the regulation of cysteine cathepsin expression by TGF-beta1 and the functional implications in tumor cells. We found an upregulation of cathepsin B (CathB, 2- to 5-fold) in different myeloid tumor cells (THP-1, MonoMac-1, MonoMac-6) after incubation with TGF-beta1. No upregulation was found in monocytes, and there was suppression of CathB expression in epithelial tumor cells (A549). Increased cathepsin B activity led to enhanced carcinogenic potential, which was reflected by increased migration and invasion of the cells and resistance to inhibitor-induced apoptosis. Analysis of the TGF-beta signaling pathways showed no alterations in TGF-beta/BMP receptor expression or SMAD2/3 phosphorylation, and no influence of MAP kinase pathways. However, a reduction in SMAD1 expression was detected. The lack of BMP action on cysteine cathepsin expression in myeloid tumor cells, but not in epithelial tumor cells, suggests a defect in the Smad1/Smad5 pathway. We located a related TGF-beta1-responsive element within the first intron of the CathB gene. In conclusion, alterations in the TGF-beta1 signaling pathway lead to upregulation of CathB, which contributes to the carcinogenic potential of tumor cells.
authors.affiliation: Probiodrug AG, Weinbergweg 22, D-06120 Halle, Germany.
authors.forename: Anita
authors.initials: A
authors.lastname: Reisenauer
authors.forename: Oliver
authors.initials: O
authors.lastname: Eickelberg
authors.forename: Aline
authors.initials: A
authors.lastname: Wille
authors.forename: Anke
authors.initials: A
authors.lastname: Heimburg
authors.forename: Annegret
authors.initials: A
authors.lastname: Reinhold
authors.forename: Bonnie F
authors.initials: BF
authors.lastname: Sloane
authors.forename: Tobias
authors.initials: T
authors.lastname: Welte
authors.forename: Frank
authors.initials: F
authors.lastname: Bühling
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D002401:Cathepsin B / Q000096:biosynthesis* / Q000235:genetics; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D011401:Promoter Regions, Genetic; D012313:RNA / Q000096:biosynthesis; D015398:Signal Transduction / Q000187:drug effects*; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology*; D015854:Up-Regulation
chemical_list: D053773:Transforming Growth Factor beta1; D012313:RNA; D002401:Cathepsin B