A Citrus Polymethoxy Flavonoid, Nobiletin Inhibits Sebum Production and Sebocyte Proliferation, and Augments Sebum Excretion in Hamsters

Abstract

Acne vulgaris is characterized by excess sebum production, and apart from all-trans retinoic acid (atRA) or 13-cis retinoic acid (13-cisRA), there are few effective agents for acne therapy that directly suppresses sebaceous lipogenesis. In this study, we demonstrated that topical application of a citrus polymethoxy flavonoid, nobiletin, to hamster auricles decreased skin surface triacylglycerols (TG) level and the size of sebaceous glands along with inhibition of diacylglycerol acyltransferase (DGAT)-dependent TG synthesis and sebocyte proliferation. The inhibitory actions were similar to that observed with atRA and 13-cisRA in hamster sebocytes. The antilipogenic and antiproliferative actions of nobiletin were also reproduced in UVB (5.4 kJ/m2)-irradiated hamsters, which showed aberrant enhancement of sebum accumulation and sebaceous enlargement. Furthermore, nobiletin, but not 13-cisRA, augmented sebum excretion along with increases in intracellular cAMP level, protein kinase A (PKA) activation, and apoptosis-independent phosphatidylserine (PS) externalization in cell membrane. These phenomena were reproduced by forskolin and inhibited by a PKA inhibitor, H-89. These results provide early evidence that nobiletin is an effective candidate for acne therapy through mechanisms that include the inhibition of DGAT-dependent TG synthesis and sebocyte proliferation, and the progression of apoptosis-independent and PS-externalization-dependent sebum excretion by PKA activation.

Suppression of Sebum Production and Accumulation by <i>β</i>-Cryptoxanthin Due to the Inhibition of the Expression of Diacylglycerol Acyltransferase-1 and Perilipin in Hamster Sebocytes

“…In addition, the sebocyte differentiation inducer, insulin (10 nM), was found to enhance the production of TGs in hamster sebocytes, and the enhanced level of TGs was dose-dependently decreased by β-CRX (72% inhibition at 10 μM). Furthermore, a similar decrease in TG level was time-dependently observed in hamster sebocytes treated with β-CRX as well as 13-cis RA (Figure 3), as we previously reported [18,34]. On the other hand, the gene expression of DGAT-1 was constitutively detectable, and was found to be increased in response to insulin treatment in hamster sebocytes (7.7 ± 3.9 fold, p < 0.05) (Figure 2(B)).…”

“…as the DGAT-1 transcript in differentiated hamster sebocytes [18]. In addition, Harris et al (2011) [36] reported that DGAT is required for not only TG synthesis but also lipid droplet formation in adipocytes from DGAT knockout mice.…”

“…Hamster sebocytes (2.4 × 10 4 cells/cm 2 ) [32] were plated onto 96-well multiplates, 35-mm or 100-mm diameter culture dishes (Becton Dickinson, Tokyo, Japan) and then cultured for 24 h in DMEM/F12 (Invitrogen, Carlsbad, CA) supplemented with 6% heat-denatured fetal bovine serum (Nichirei Biosciences Inc., Tokyo, Japan), 2% human serum (C-C Biotech Co., Valley Center, CA), 0.68 mM L-glutamine (Invitrogen), and recombinant human epidermal growth factor (10 nM) (Progen Biotechnik GmbH, Heidelberg, Germany) to achieve complete cell adhesion as previously described [6,18]. The hamster sebocytes were treated every two days for up to 8 days with or without β-CRX (purity ≥ 95%; Shikoku Yashima Pure Chemicals, Tokushima, Japan) (Figure 1) or 13-cisRA (Sigma Chemical, St. Louis, MO) in the presence or absence of a sebocyte-differentiation inducer, insulin (10 nM) (Sigma Chemical) [12] in DMEM/F12 supplemented with heat-denatured fetal bovine serum, human serum, and L-glutamine.…”

“…On the other hand, retinoic acids such as tretinoin (all-trans retinoic acid; atRA) and isotretinoin (13-cis retinoic acid; 13-cisRA) have been topically and/or systemically used for acne therapy [13,14]. They have been reported to exhibit comedolytic, antiinflammatory, and anti-lipogenetic actions in sebaceous glands and pilosebaceous units in humans, rats, and hamsters in vivo and in vitro [14][15][16][17][18][19]. However, the use of retinoids in acne therapy has been limited in acceptance because of adverse effects such as skin irritation, scaling, and teratogenicity [13].…”

Antimetastatic effect of nobiletin through the down-regulation of CXC chemokine receptor type 4 and matrix metallopeptidase-9

“…Numerous in vivo and in vitro studies have demonstrated the anti-inflammatory activities of nobiletin and its metabolites (Chen et al, 2007;Choi et al, 2007;Li et al, 2007;Murakami et al, 2000). Nobiletin helps to lower cholesterol levels (Whitman et al, 2005) and some studies indicate that it may improve impaired memory loss (Onozuka et al, 2008) and treat acne (Sato et al, 2007). Nobiletin has been shown to exhibit antitumor activities as indicated by the attenuation of pro-MMP-7 protein and its mRNA expression in HT-29 cells (Kawabata et al, 2005), down-regulation of leptin levels in mice with azoxymethane-and dextran sulfate sodium-induced colon carcinogenesis (Miyamoto et al, 2008), and the suppression of invasion and migration in human gastric adenocarcinoma AGS cells (Lee et al, 2011).…”