title: Salicylic acid induces apoptosis in colon carcinoma cells grown in-vitro: influence of oxygen and salicylic acid concentration.
abstract: In solid tumors the hypoxic environment can promote tumor progression and resistance to therapy. Recently, acetylsalicylic acid a major component of analgesic drugs and its metabolite salicylic acid (SA) have been shown to reduce the risk of colon cancer, but the mechanisms of action remain still unclear. Here we elucidate the effects of physiologically relevant concentrations of SA on colon carcinoma cells (CaCo-2) grown under normoxic and hypoxic conditions. Western blotting, caspase-3/7 apoptosis assays, MTS cell-proliferation assays, LDH cytotoxicity assays and hydrogen peroxide measurements were performed to investigate the effects of 1 and 10μM SA on CaCo-2 cells grown under normoxic conditions and cells exposed to hypoxia. Under normoxic conditions, SA did not influence cell proliferation or LDH release of CaCo-2 cells. However, caspase-3/7 activity was significantly increased. Under hypoxia, cell proliferation was reduced and LDH release and caspase-3/7 activities were increased. None of these parameters was altered by the addition of SA under hypoxic conditions. Hypoxia increased hydrogen peroxide concentrations 300-fold and SA significantly augmented the release of hydrogen peroxide under normoxic, but not under hypoxic conditions. Phosphorylation of the pro-survival kinases akt and erk1/2 was not changed by SA under hypoxic conditions, whereas under normoxia SA reduced phosphorylation of erk1/2 after 2 hours. We conclude that in colon carcinoma cells effects of SA on apoptosis and cellular signaling are dependent on the availability of oxygen.
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, University Hospital Schleswig-Holstein, Kiel, Germany.
authors.forename: Karina
authors.initials: K
authors.lastname: Zitta
authors.forename: Patrick
authors.initials: P
authors.lastname: Meybohm
authors.forename: Berthold
authors.initials: B
authors.lastname: Bein
authors.forename: Ying
authors.initials: Y
authors.lastname: Huang
authors.forename: Christin
authors.initials: C
authors.lastname: Heinrich
authors.forename: Jens
authors.initials: J
authors.lastname: Scholz
authors.forename: Markus
authors.initials: M
authors.lastname: Steinfath
authors.forename: Martin
authors.initials: M
authors.lastname: Albrecht
mesh_terms: D000230:Adenocarcinoma / Q000188:drug therapy*; D017209:Apoptosis / Q000187:drug effects*; D018938:Caco-2 Cells; D053148:Caspase 3 / Q000378:metabolism; D053179:Caspase 7 / Q000378:metabolism; D015687:Cell Hypoxia / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D003110:Colonic Neoplasms / Q000188:drug therapy*; D006801:Humans; D006861:Hydrogen Peroxide / Q000032:analysis; D020935:MAP Kinase Signaling System / Q000187:drug effects; D051058:Oncogene Protein v-akt / Q000032:analysis; D010100:Oxygen / Q000494:pharmacology*; D010766:Phosphorylation / Q000187:drug effects; D020156:Salicylic Acid / Q000494:pharmacology*
chemical_list: D006861:Hydrogen Peroxide; D051058:Oncogene Protein v-akt; C505407:CASP3 protein, human; C505520:CASP7 protein, human; D053148:Caspase 3; D053179:Caspase 7; D020156:Salicylic Acid; D010100:Oxygen