Inhibitory effects of Momordica grosvenori Swingle extracts on 12-O-tetradecanoylphorbol 13-acetate-induced skin inflammation and tumor promotion in mouse skin
Our previous data showed that the Momordica grosvenori Swingle extract (MSE) exhibited the anti-inflammatory effect through markedly suppressed LPS-induced up-regulation of inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2) and ODC (ornithine decarboxylase) gene expression in RAW 264.7 cells. Regarding the link between inflammation and carcinogenesis, we further investigated the bio-molecular mechanisms of both anti-inflammatory and anti-tumor activities in vivo using a TPA (12-O-tetradecanoyl phorbol 13-acetate)-stimulated mouse skin model. Pretreatment with MSE in mouse skin has led to the reduction of TPA-induced nuclear translocation of the nuclear factor-κB (NFκB) subunits as well as phosphorylation of IκBα and p65 subsequent reduction of IκBα degradation. In addition, the MSE inhibitory effect on upstream of NFκB was found to involve the transcriptional effects of MAPK signaling as indicated by strong suppression on TPA-induced activation of extracellular signal regulate kinase (ERK)1/2, p38 mitogen-activated protein kinase (MAPK), c-Jun N-terminal kinase (JNK)1/2, phosphatidylinositol 3-kinase (PI3K) and Akt. Moreover, MSE significantly inhibited 7,12-dimethylbenz[a]anthracene (DMBA)–TPA-induced skin tumor formation in mice measured by the tumor multiplicity of papillomas at 20 weeks. The results suggested that MSE contained promising functional ingredients capable of preventing inflammation-associated tumorigenesis.