Antitumor activity and macrophage nitric oxide producing action of medicinal herb, Crassocephalum crepidioides.
BACKGROUND
Crassocephalum crepidioides, a plant distributed in Okinawa Islands, is known in folk medicine; however, its anticancer activity has not been investigated. The aim of this study was to determine the in vitro and in vivo antitumor activities of C. crepidioides on murine Sarcoma 180 (S-180) and related molecular mechanisms.


METHODS
The antitumor effect of C. crepidioides was evaluated in S-180-cell-bearing mice. Cell growth was assessed using a colorimetric assay. Nitrite and nitrate levels were measured by colorimetry. The expression levels of inducible NO synthase (iNOS) in murine RAW264.7 macrophages was assessed by reverse transcriptase-polymerase chain reaction. Activation of iNOS promoter was detected by reporter gene. Activation of nuclear factor-κB (NF-κB) was evaluated by electrophoretic mobility shift assay. The role of NF-κB signaling was analyzed using inhibitors of NF-κB and dominant-negative mutants, and Western blot analysis.


RESULTS
C. crepidioides extract delayed tumor growth in S-180-bearing mice. However, it did not inhibit S-180 cell growth in vitro. Supernatant of cultured C. crepidioides-stimulated RAW264.7 macrophages was cytotoxic to S-180 cells. This cytotoxicity was associated with nitric oxide (NO) production. NF-κB signaling pathway was crucial for the transcriptional activation of iNOS gene. Isochlorogenic acid, a component of C. crepidioides, induced NF-κB activation and iNOS expression.


CONCLUSIONS
The results highlight the oncolytic and immunopotentiation properties of C. crepidioides mediated through NF-κB-induced release of NO from macrophages.
Department of Microbiology and Oncology, Graduate School of Medicine, University of the Ryukyus, 207 Uehara, Nishihara, Okinawa, 903-0215, Japan.
Koh
K
Tomimori
Shinji
S
Nakama
Ryuichiro
R
Kimura
Kazumi
K
Tamaki
Chie
C
Ishikawa
Naoki
N
Mori
D000818:Animals; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology / Q000627:therapeutic use; D019659:Asteraceae / Q000737:chemistry*; D002460:Cell Line; D045744:Cell Line, Tumor; D002726:Chlorogenic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology / Q000627:therapeutic use; D005260:Female; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D016328:NF-kappa B / Q000378:metabolism; D009569:Nitric Oxide / Q000096:biosynthesis*; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000378:metabolism*; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology / Q000627:therapeutic use; D010946:Plants, Medicinal; D012509:Sarcoma / Q000188:drug therapy* / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D015533:Transcriptional Activation / Q000187:drug effects
D000972:Antineoplastic Agents, Phytogenic; D016328:NF-kappa B; D010936:Plant Extracts; C469310:isochlorogenic acid; D002726:Chlorogenic Acid; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II