Journal Article

Caffeic acid, a phenolic phytochemical in coffee, directly inhibits Fyn kinase activity and UVB-induced COX-2 expression

Nam Joo Kang, Ki Won Lee, Bong Jik Shin, Sung Keun Jung, Mun Kyung Hwang, Ann M. Bode, Yong-Seok Heo, Hyong Joo Lee and Zigang Dong

in Carcinogenesis

Volume 30, issue 2, pages 321-330
Published in print February 2009 | ISSN: 0143-3334
Published online December 2008 | e-ISSN: 1460-2180 | DOI: http://dx.doi.org/10.1093/carcin/bgn282
Caffeic acid, a phenolic phytochemical in coffee, directly inhibits Fyn kinase activity and UVB-induced COX-2 expression

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Caffeic acid (3,4-dihydroxycinnamic acid) is a well-known phenolic phytochemical present in many foods, including coffee. Recent studies suggested that caffeic acid exerts anticarcinogenic effects, but little is known about the underlying molecular mechanisms and specific target proteins. In this study, we found that Fyn, one of the members of the non-receptor protein tyrosine kinase family, was required for ultraviolet (UV) B-induced cyclooxygenase-2 (COX-2) expression, and caffeic acid suppressed UVB-induced skin carcinogenesis by directly inhibiting Fyn kinase activity. Caffeic acid more effectively suppressed UVB-induced COX-2 expression and subsequent prostaglandin E2 production in JB6 P+ mouse skin epidermal (JB6 P+) cells compared with chlorogenic acid (5-O-caffeoylquinic acid), an ester of caffeic acid with quinic acid. Data also revealed that caffeic acid more effectively induced the downregulation of COX-2 expression at the transcriptional level mediated through the inhibition of activator protein-1 (AP-1) and nuclear factor-κB transcription activity compared with chlorogenic acid. Fyn kinase activity was suppressed more effectively by caffeic acid than by chlorogenic acid, and downstream mitogen-activated protein kinases (MAPKs) were subsequently blocked. Pharmacological Fyn kinase inhibitor (3-(4-chlorophenyl)1-(1,1-dimethylethyl)-1H-pyrazolo[3,4-d]pyrimidin-4-amine and leflunomide) data also revealed that Fyn is involved in UVB-induced COX-2 expression mediated through the phosphorylation of MAPKs in JB6 P+ cells. Pull-down assays revealed that caffeic acid directly bound with Fyn and non-competitively with adenosine triphosphate. In vivo data from mouse skin also supported the idea that caffeic acid suppressed UVB-induced COX-2 expression by blocking Fyn kinase activity. These results suggested that this compound could act as a potent chemopreventive agent against skin cancer.

Journal Article.  7611 words.  Illustrated.

Subjects: Clinical Cytogenetics and Molecular Genetics

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