title: Rapamycin suppresses TLR4-triggered IL-6 and PGE(2) production of colon cancer cells by inhibiting TLR4 expression and NF-kappaB activation.
abstract: Toll-like receptor 4 (TLR4) signaling in tumor cells can mediate tumor cell immune escape and tumor progression, being regarded as one of the mechanisms for chronic inflammation in tumorigenesis and progression. So, intervention of TLR4-mediated immune escape and metastasis has been proposed as one of the approaches to cancer prevention and treatment. Rapamycin, an immunosuppressant agent widely used for treatment of autoimmune diseases and transplantation rejection, is recently used for cancer therapy. However, the underlying mechanisms remain to be fully understood. In the present study, we demonstrate that rapamycin can significantly inhibit TLR4-triggered IL-6 and PGE(2) production and invasion of colon cancer cells. Suppression of TLR4-induced IL-6 and PGE(2) production is responsible for the rapamycin-mediated decrease of TLR4-evoked invasion of colon cancer cells. Furthermore, disruption of NF-kappaB pathway contributes to the inhibition of TLR4-induced IL-6, PGE(2) production and invasion by rapamycin in colon cancer cells. Rapamycin can also downregulate TLR4 expression. Therefore, we demonstrate that rapamycin may abrogate TLR4-triggered tumor cell immune escape and invasion by downregulating TLR4 expression and inhibiting TLR4-activated NF-kappaB pathway, thus providing new mechanistic explanation for the antitumor effect of rapamycin.
authors.affiliation: Institute of Immunology, Zhejiang University School of Medicine, 388 Yuhangtang Road, Hangzhou 310058, PR China.
authors.forename: Qiaoling
authors.initials: Q
authors.lastname: Sun
authors.forename: Qiuyang
authors.initials: Q
authors.lastname: Liu
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Zheng
authors.forename: Xuetao
authors.initials: X
authors.lastname: Cao
mesh_terms: D000818:Animals; D019898:Autocrine Communication / Q000187:drug effects; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D003110:Colonic Neoplasms / Q000201:enzymology / Q000276:immunology* / Q000473:pathology; D015232:Dinoprostone / Q000096:biosynthesis*; D015536:Down-Regulation / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D015850:Interleukin-6 / Q000096:biosynthesis* / Q000235:genetics; D008070:Lipopolysaccharides / Q000494:pharmacology; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016328:NF-kappa B / Q000276:immunology*; D009361:Neoplasm Invasiveness; D020123:Sirolimus / Q000494:pharmacology*; D051197:Toll-Like Receptor 4 / Q000276:immunology*
chemical_list: D015850:Interleukin-6; D008070:Lipopolysaccharides; D016328:NF-kappa B; D051197:Toll-Like Receptor 4; D020928:Mitogen-Activated Protein Kinases; D015232:Dinoprostone; D020123:Sirolimus