Nobiletin Suppresses MMP-9 Expression through Modulation of p38 MAPK Activity in Human Dermal Fibrobalsts

Abstract

We aimed to identify a novel flavonoid from the in-house natural products to suppress matrix metalloproteases (MMPs), which is responsible for degradation of collagen and other extracellular matrix proteins. Total eight natural products were screened for identification of a novel MMP-9 suppressor using MMP-9 reporter system, where the prompt initial screening with multiple samples is readily examined. Among the extracts used in the present study, one extract (Citrus unshiu) was found active in this assay system. Furthermore, three representative flavonoids in this active extract of Citrus unshiu peel were tested in MMP-9 reporter system. Nobiletin (NB) of the tested flavonoids suppressed MMP-9 expression without cytotoxicity, which was validated by both real-time polymerase chain reaction (PCR) and zymography analyses. Sustained p38 mitogen activated protein kinase (MAPK) activity, closely associated with induction of MMP-9 under stress condition, was markedly reduced by NB treatment, which implies that modulation of p38MAPK by nobiletin is responsible for reduction of MMP9 expression. Hence, nobiletin, identified from MMP-9 reporter system based screening, may be further applied for the purpose of delaying collagen degradation in skin fibroblasts.Key words Citrus unshiu; nobiletin; flavonoid; matrix metalloprotease 9; p38 mitogen activated protein kinase (MAPK)The integrity of skin connective tissue, which is important for the elasticity of the skin, relies on the levels of dermal extracellular matrix (ECM) proteins, such as collagen type I and III, elastin, and fibronectin. Aging or chronic exposure to ultra violet (UV) causes loss of ECM and the consequent decreased resilience of skin, which are strongly associated with various phenotypes of aged skin (e.g. wrinkle formation). 1)Matrix metalloproteinases (MMPs), members of the zincdependent endoprotease family, serve as important enzyme in degrading dermal ECM.2) Of note, excess expression of MMPs in keratinocytes and dermal fibroblasts, under a variety of stress conditions such as UV radiation (UVR), and heat-shock, 3) which both are closely associated to the aged skin phenotypes, 4,5) contributes to the degradation of ECM proteins, leading to wrinkle formation in photo-aged skin. 6)Therefore, MMPs, induced by a variety of external stresses and capable of degrading collagen and other ECM proteins, have been widely studied as a target for relieving the appearance of aged skin. 7)Among them, gelatinase A (MMP-2) and gelatinase B (MMP-9) were increased by UV radiation in human dermal fibroblasts (hDFs) 8,9) and are responsible for degrading collagens, which are components of the epidermal basement membranes.10) Thereby, the increased activity or expression of gelatinases induced by UV radiation to cause disruption of the basement membrane is considered to be a main cause of skin photoaging, 11,12) which can provide a rationale to target the gelatinases to prevent UV induced wrinkle formation. 7,12) In special, MMP-9 expression is dependent upon activator protei...

Anti-Tumor Effect of Pinus massoniana Bark Proanthocyanidins on Ovarian Cancer through Induction of Cell Apoptosis and Inhibition of Cell Migration

“…Our data indicated that PMBPs treatment inhibited the activation of ERK1/2 and p38 MAPK in a dose-dependent manner, but had little effect on JNK pathway ( Fig 8B and 8D ). Our data here, together with others, show that MMP-9 can be activated through multiple signaling pathways including the MAPKs family [ 40 , 41 , 42 ], however, whether PMBPs directly regulated MMP-9 activity through ERK1/2 and p38 MAPK pathways needs further investigation.…”

Nobiletin inhibits human osteosarcoma cells metastasis by blocking ERK and JNK-mediated MMPs expression

“…Previous studies shown that nobiletin inhibits invasion and migration capacities of nasopharyngeal carcinoma cell lines and glioma cell lines through down-regulating ERK and/ or JNK pathway [62, 63]. Nobiletin also suppresses MMP-9 expression by reducing p38 MAPK activity [64]. Furthermore, we were interested in nobiletin's inhibitory mechanism on ERK and JNK signaling pathway that mediates MMP-2 and MMP-9 expression, implicating in U2OS and HOS cells metastasis.…”

The Multifunctional Effects of Nobiletin and Its Metabolites In Vivo and In Vitro

“…MMPs are responsible for degradation of extracellular matrix proteins and collagen. NOB has been identified to a novel MMP-9 suppressor using MMP-9 reporter system through downregulation of p38 MAPK phosphorylation in human dermal fibroblasts stimulated by PMA [ 92 ].…”