title: Hesperetin-etoposide combinations induce cytotoxicity in U2OS cells: Implications on therapeutic developments for osteosarcoma.
abstract: Osteosarcoma chemotherapy has improved survival rates, however, chemoresistance and drug toxicity still limit therapy. Drug combinations may overcome these limitations by allowing fewer chemoresistant cells to survive. The aim of this study was to evaluate the cytotoxic potential of hesperetin to osteosarcoma and to analyze the cell cycle effects of combinations of hesperetin with chemotherapeutic agents. For this, the U2OS human osteosarcoma cell line was exposed to hesperetin or hesperetin combined with etoposide or doxorubicin in defined proportions. Hesperetin was less cytotoxic compared to chemotherapeutic agents, as shown by cell growth, viability and clonogenic assays. Notwithstanding, hesperetin combined with etoposide showed additive effects on the inhibition of cell growth. Furthermore, hesperetin induced G2-phase arrest, associated with decreased gene expression of cyclins B1 and E1 and cyclin-dependent kinases 1 and 2. The combination with higher additive effect resulted in higher percentage of cells in G2-phase, showing that G2-phase arrest is associated with cytotoxicity. Moreover, hesperetin induced cytostatic effects. In conclusion, our results suggest that G2-phase arrest is an important step for hesperetin-induced cytotoxicity in U2OS cells. Hesperetin shows potential cytotoxicity when combined with etoposide, which may have implications on therapeutic developments for osteosarcoma.
authors.affiliation: CESAM & Department of Biology, University of Aveiro, Campus Universitário de Santiago, Aveiro, Portugal.
authors.forename: Laura
authors.initials: L
authors.lastname: Coutinho
authors.affiliation: CESAM & Department of Biology, University of Aveiro, Campus Universitário de Santiago, Aveiro, Portugal.
authors.forename: Helena
authors.initials: H
authors.lastname: Oliveira
authors.affiliation: CESAM & Department of Biology, University of Aveiro, Campus Universitário de Santiago, Aveiro, Portugal.
authors.forename: Ana Rita
authors.initials: AR
authors.lastname: Pacheco
authors.affiliation: Department of Pharmacology and Therapeutics, Faculty of Medicine, Porto, Portugal.
authors.forename: Luis
authors.initials: L
authors.lastname: Almeida
authors.affiliation: Department of Medical Sciences, University of Aveiro, Aveiro, Portugal; Lenitudes Medical Center & Research, Santa Maria da Feira, Portugal.
authors.forename: Francisco
authors.initials: F
authors.lastname: Pimentel
authors.affiliation: Department of Biology, Faculty of Sciences, University of Porto, Porto, Portugal.
authors.forename: Conceição
authors.initials: C
authors.lastname: Santos
authors.affiliation: CESAM & Department of Biology, University of Aveiro, Campus Universitário de Santiago, Aveiro, Portugal; Department of Biology, Faculty of Sciences, University of Porto, Porto, Portugal. Electronic address: oliveira.miguel@ua.pt.
authors.forename: José Miguel P
authors.initials: JM
authors.lastname: Ferreira de Oliveira
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology* / Q000627:therapeutic use; D001859:Bone Neoplasms / Q000188:drug therapy*; D059447:Cell Cycle Checkpoints / Q000187:drug effects*; D045744:Cell Line, Tumor; D003603:Cytotoxins / Q000494:pharmacology / Q000627:therapeutic use; D004317:Doxorubicin / Q000494:pharmacology / Q000627:therapeutic use; D005047:Etoposide / Q000494:pharmacology* / Q000627:therapeutic use; D006569:Hesperidin / Q000494:pharmacology* / Q000627:therapeutic use; D006801:Humans; D012516:Osteosarcoma / Q000188:drug therapy*
chemical_list: D003603:Cytotoxins; D005047:Etoposide; D004317:Doxorubicin; D006569:Hesperidin; C013015:hesperetin
keywords: Cell cycle; Doxorubicin; Doxorubicin (PubChem: 32874); Etoposide; Etoposide (PubChem CID: 36462); Hesperetin; Hesperetin (PubChem CID: 72281); Osteosarcoma; U2OS