title: SIAH ubiquitin ligases regulate breast cancer cell migration and invasion independent of the oxygen status.
abstract: Seven-in-absentia homolog (SIAH) proteins are evolutionary conserved RING type E3 ubiquitin ligases responsible for the degradation of key molecules regulating DNA damage response, hypoxic adaptation, apoptosis, angiogenesis, and cell proliferation. Many studies suggest a tumorigenic role for SIAH2. In breast cancer patients SIAH2 expression levels correlate with cancer aggressiveness and overall patient survival. In addition, SIAH inhibition reduced metastasis in melanoma. The role of SIAH1 in breast cancer is still ambiguous; both tumorigenic and tumor suppressive functions have been reported. Other studies categorized SIAH ligases as either pro- or antimigratory, while the significance for metastasis is largely unknown. Here, we re-evaluated the effects of SIAH1 and SIAH2 depletion in breast cancer cell lines, focusing on migration and invasion. We successfully knocked down SIAH1 and SIAH2 in several breast cancer cell lines. In luminal type MCF7 cells, this led to stabilization of the SIAH substrate Prolyl Hydroxylase Domain protein 3 (PHD3) and reduced Hypoxia-Inducible Factor 1α (HIF1α) protein levels. Both the knockdown of SIAH1 or SIAH2 led to increased apoptosis and reduced proliferation, with comparable effects. These results point to a tumor promoting role for SIAH1 in breast cancer similar to SIAH2. In addition, depletion of SIAH1 or SIAH2 also led to decreased cell migration and invasion in breast cancer cells. SIAH knockdown also controlled microtubule dynamics by markedly decreasing the protein levels of stathmin, most likely via p27(Kip1). Collectively, these results suggest that both SIAH ligases promote a migratory cancer cell phenotype and could contribute to metastasis in breast cancer.
authors.affiliation: a Cellular Senescence Group ; German Cancer Research Center DKFZ ; Heidelberg , Germany.|b GTRG Oncology II; GDD; Bayer Pharma AG ; Berlin , Germany.
authors.forename: M Gordian
authors.initials: MG
authors.lastname: Adam
authors.affiliation: a Cellular Senescence Group ; German Cancer Research Center DKFZ ; Heidelberg , Germany.
authors.forename: Sonja
authors.initials: S
authors.lastname: Matt
authors.affiliation: b GTRG Oncology II; GDD; Bayer Pharma AG ; Berlin , Germany.
authors.forename: Sven
authors.initials: S
authors.lastname: Christian
authors.affiliation: b GTRG Oncology II; GDD; Bayer Pharma AG ; Berlin , Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Hess-Stumpp
authors.affiliation: b GTRG Oncology II; GDD; Bayer Pharma AG ; Berlin , Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Haegebarth
authors.affiliation: a Cellular Senescence Group ; German Cancer Research Center DKFZ ; Heidelberg , Germany.
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Hofmann
authors.affiliation: b GTRG Oncology II; GDD; Bayer Pharma AG ; Berlin , Germany.
authors.forename: Carolyn
authors.initials: C
authors.lastname: Algire
mesh_terms: D017209:Apoptosis / Q000235:genetics; D001943:Breast Neoplasms / Q000235:genetics* / Q000473:pathology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics*; D049109:Cell Proliferation / Q000235:genetics; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000378:metabolism / Q000502:physiology; D055785:Gene Knockdown Techniques; D006801:Humans; D061986:MCF-7 Cells; D008870:Microtubules / Q000378:metabolism; D009361:Neoplasm Invasiveness / Q000235:genetics*; D009362:Neoplasm Metastasis / Q000235:genetics; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D034622:RNA Interference; D050777:Stathmin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D000098563:Seven in Absentia Proteins
chemical_list: C436291:CDKN1B protein, human; D009687:Nuclear Proteins; D050777:Stathmin; D050760:Cyclin-Dependent Kinase Inhibitor p27; D044767:Ubiquitin-Protein Ligases; D000098563:Seven in Absentia Proteins
keywords: SIAH ubiquitin ligases; SIAH1; SIAH2; breast cancer; invasion; metastasis; migration; p27Kip1; seven-in-absentia; stathmin