gingerol and Papilloma

We previously reported that 6-shogaol strongly suppressed lipopolysaccharide-induced overexpression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in murine macrophages. In this study, we further compared curcumin, 6-gingerol, and 6-shogaol's molecular mechanism of action and their anti-tumor properties. We demonstrate that topical application of 6-shogaol more effectively inhibited 12-O-tetradecanoylphorbol 13-acetate (TPA)-stimulated transcription of iNOS and COX-2 mRNA expression in mouse skin than curcumin and 6-gingerol. Pretreatment with 6-shogaol has resulted in the reduction of TPA-induced nuclear translocation of the nuclear factor-kappaB subunits. 6-Shogaol also reduced TPA-induced phosphorylation of IkappaBalpha and p65, and caused subsequent degradation of IkappaBalpha. Moreover, 6-shogaol markedly suppressed TPA-induced activation of extracellular signal-regulate kinase1/2, p38 mitogen-activated protein kinase, JNK1/2, and phosphatidylinositol 3-kinase/Akt, which are upstream of nuclear factor-kappaB and AP-1. Furthermore, 6-shogaol significantly inhibited 7,12-dimethylbenz[a]anthracene/TPA-induced skin tumor formation measured by the tumor multiplicity of papillomas at 20 wk. Presented data reveal for the first time that 6-shogaol is an effective anti-tumor agent that functions by down-regulating inflammatory iNOS and COX-2 gene expression in mouse skin. It is suggested that 6-shogaol is a novel functional agent capable of preventing inflammation-associated tumorigenesis.

Topics: Administration, Topical; Animals; Anti-Inflammatory Agents, Non-Steroidal; Anticarcinogenic Agents; Catechols; Curcumin; Cyclooxygenase 2; Dose-Response Relationship, Drug; Fatty Alcohols; Female; Gene Expression Regulation, Enzymologic; Mice; Mice, Inbred ICR; Nitric Oxide Synthase Type II; Papilloma; RNA, Messenger; Signal Transduction; Skin; Skin Neoplasms; Tumor Burden

Ginger (Zingiber officinale Roscoe, Zingiberaceae) has been widely used as a dietary spice, as well as in traditional oriental medicine. The rhizome of ginger contains pungent vanillyl ketones, including [6]-gingerol and [6]-paradol, and has been reported to possess a strong anti-inflammatory activity. These pungent substances have a vanilloid structure found in other chemopreventive phytochemicals, including curcumin. In our study, we found anti-tumor-promoting properties of [6]-gingerol and [6]-paradol. Thus, topical application of [6]-gingerol or [6]-paradol 30 min prior to 12-O-tetradecanoyl-phorbol-13-acetate (TPA) attenuated the skin papillomagenesis initiated by 7,12-dimethylbenz[a]anthracene in female ICR mice. These substances also significantly inhibited the tumor-promoter-stimulated inflammation, TNF-alpha production, and activation of epidermal ornithine decarboxylase in mice. In another study, [6]-gingerol and [6]-paradol suppressed the superoxide production stimulated by TPA in differentiated HL-60 cells. Taken together, these findings suggest that pungent vanilloids found in ginger possess potential chemopreventive activities.

Topics: Animals; Anticarcinogenic Agents; Carcinogens; Catechols; Dermatitis; Fatty Alcohols; Female; Guaiacol; HL-60 Cells; Humans; Ketones; Mice; Mice, Inbred ICR; Ornithine Decarboxylase; Papilloma; Plant Extracts; Skin; Skin Neoplasms; Superoxides; Tetradecanoylphorbol Acetate; Tumor Necrosis Factor-alpha; Zingiber officinale