title: Nitric oxide-mediated antitumor activity induced by the extract from Grifola frondosa (Maitake mushroom) in a macrophage cell line, RAW264.7.
abstract: We have investigated D-fraction (MDF) extracted from Grifola frondosa (Maitake mushroom) on the inducible nitric oxide synthase (iNOS)-mediated nitric oxide (NO) production in RAW264.7 (RAW) cells, a murine monocyte/macrophage cell line, with special reference to antitumor activity of MDF against human hepatoma-derived huH-1 cells. MDF could induce iNOS mRNA expression in RAW cells in a dose range of more than 30 microg/ml, but the effect of 10 microg/ml of MDF was negligible. The iNOS mRNA expression induced by 100 microg/ml of MDF was 6 hrs later, but lasted for a longer time than that of lipopolysaccharide (LPS), a representative iNOS inducer. Although iNOS mRNA levels in MDF-stimulated cells were almost equal to LPS-stimulated cells at the peak time, the cumulative amount of nitrite was only about 50% compared with that of LPS-treated cells. When huH-I cells were cultured in MDF containing media in a 24-well plate with inserted porous bottom in the presence or absence of RAW cells, the viability of huH-1 cells decreased significantly only in the presence of RAW cells in MDF dose-dependent manner. This antitumor activity of RAW cells in the presence of MDF was abolished or attenuated by the addition of L-NAME, a NOS inhibitor, confirming that this phenomenon is due to iNOS-mediated NO production by RAW cells, but not direct cytotoxic activity of MDF against huH-1 cells. These data suggest that MDF is a novel inducer for iNOS which contributes at least in part to antitumor activity of MDF.
authors.affiliation: Dept. of Clinical Nursing, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Sugitani, Japan.
authors.forename: I
authors.initials: I
authors.lastname: Sanzen
authors.forename: N
authors.initials: N
authors.lastname: Imanishi
authors.forename: N
authors.initials: N
authors.lastname: Takamatsu
authors.forename: S
authors.initials: S
authors.lastname: Konosu
authors.forename: N
authors.initials: N
authors.lastname: Mantani
authors.forename: K
authors.initials: K
authors.lastname: Terasawa
authors.forename: K
authors.initials: K
authors.lastname: Tazawa
authors.forename: Y
authors.initials: Y
authors.lastname: Odaira
authors.forename: M
authors.initials: M
authors.lastname: Watanabe
authors.forename: M
authors.initials: M
authors.lastname: Takeyama
authors.forename: H
authors.initials: H
authors.lastname: Ochiai
mesh_terms: D000363:Agaricales / Q000737:chemistry*; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D017931:DNA Primers / Q000737:chemistry; D005936:Glucans / Q000302:isolation & purification / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D009566:Nitrates / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D009573:Nitrites / Q000378:metabolism; D010936:Plant Extracts / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors
chemical_list: D000970:Antineoplastic Agents; D017931:DNA Primers; D005936:Glucans; D009566:Nitrates; D009573:Nitrites; D010936:Plant Extracts; D012333:RNA, Messenger; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse