In vitro growth changes of oral human keratinocytes after treatment with carotenoids, retinoid, and/or DMBA

Carotenoids from Cyanobacteria: A Biotechnological Approach for the Topical Treatment of Psoriasis

In this study, five cyanobacteria strains (Alkalinema aff. pantanalense LEGE15481, Cyanobium gracile LEGE12431, Nodosilinea (Leptolyngbya) antarctica LEGE13457, Cuspidothrix issatschenkoi LEGE03282 and Leptolyngbya-like sp. LEGE13412) from the Blue Biotechnology and Ecotoxicology Culture Collection (LEGE CC) of CIIMAR were explored for their biotechnological potential in the treatment of psoriasis. Different extracts were characterized for their pigment profile by HPLC-PDA. The antioxidant potential of the extracts was assessed against the superoxide anion radical (O₂^•-). Their anti-inflammatory and antiproliferative potential was assessed in vitro using the macrophages RAW 264.7 and the human keratinocytes HaCaT as cell-line models, respectively. Terrestrial and freshwater strains presented the highest carotenoid content (33193-63926 μg/g dry extract), with all-trans-β-carotene, zeaxanthin, echinenone and lutein derivatives being the most abundant carotenoids. Acetone was the most effective solvent for pigment extraction. The acetone extracts presented the lowest IC₅₀ values (0.29-0.38 mg dry extract/mL) regarding O₂^•- scavenging, and revealed anti-inflammatory potential, with N. antarctica LEGE13457, A. pantanalense LEGE15481 and Leptolyngbya-like sp. LEGE13412 reducing the nitric oxide (NO) in RAW 264.7 cell culture medium in about 25% (p < 0.05). With the exception of A. pantanalense LEGE15481, all the extracts significantly reduced keratinocyte proliferation (p < 0.05), demonstrating a selective toxicity among the different cell lines. Overall, Leptolyngbya-like sp. LEGE13412 and N. antarctica LEGE13457 seem promising for further exploitation in the framework of psoriasis, due to their antioxidant, anti-inflammatory and antiproliferative potential.

Keratinization of outer root sheath cells is prevented by contact with inner root sheath of rat hair follicles

The purpose of the present study was to elucidate why keratinocytes of the outer root sheath (ORS) do not keratinize in situ. Two possibilities were considered--inhibition of keratinization is caused by contact of ORS with inner root sheath (IRS) or insufficient supply of keratinization promoting factors from the surrounding tissues to the ORS. In order to distinguish between these possibilities mid-segments of hair follicles were liberated from the dermis by dissection followed by collagenase digestion. ORS cells were then either allowed to migrate from the mid-segments or were kept on the agarose layer which prevented cell spreading and preserved three dimensional structure of hair root. Cultures were stimulated with calcium or EGF, and studied morphologically at the light and transmission electron microscope level. The level of mRNA for differentiation cell markers was also studied by RealTime PCR. ORS cells growing in a medium with low Ca2+ content formed monolayers, which after elevation of Ca2+ produced multilayers with cells containing keratohyalin-like granules. Ca2+ or EGF treatment upregulated expression of involucrin, filaggrin and keratinocyte differentiation associated protein (Kdap). Culture of mid-segments of hair follicles in low calcium culture medium kept on agarose increased expression of filaggrin and Kdap, but downregulated expression of involucrin. Stimulation by Ca2+ further increased expression of filaggrin and Kdap, but had no effect on the level of involucrin expression. EGF stimulated expression of filaggrin only. It is concluded that IRS exerted an inhibitory effect on the expression of involucrin, an essential component of the cornified envelope, thus preventing keratinization of ORS cells in situ. On the other hand, improved access of nutrients or promoting factors of keratinization to the mid-segment of hair follicles augmented expression of filaggrin and Kdap, proteins engaged in the differentiation of keratinocytes but not involved in its terminal phase.

Apigenin induced apoptosis through p53-dependent pathway in human cervical carcinoma cells

Apigenin is a widely distributed plant flavonoid and was proposed as an antitumor agent. In this study, we reported for the first time that apigenin inhibited the growth of human cervical carcinoma cells (HeLa) and through apoptotic pathway. The results showed that apigenin significantly decreased the viability of HeLa cells at 37-74 microM and the IC50 value was 35.89 microM. Apigenin-induced apoptosis in HeLa cells was confirmed by DNA fragmentation assay and induction of sub-G1 phase by flow cytometry. Apigenin-treated HeLa cells were arrested at G1 phase, which was associated with a marked increment of the expression of p21/WAF1 protein. The induction of p21/WAF1 appeared to be transcriptionally upregulated and was p53-dependent. In addition, apigenin induced Fas/APO-1 and caspase-3 expression which were also correlated with apoptosis. Apigenin decreased in the protein expression of Bcl-2 protein, which is an anti-apoptotic factor. The conclusion of this study is the apigenin induced p53 expression which caused cell cycle arrest and apoptosis. These findings suggest that apigenin has strong potential for development as an agent for preventing cervical cancer.

Modulation of p53 in 7,12-dimethylbenz[a]anthracene–induced skin tumors by diallyl sulfide in Swiss albino mice

Allium vegetables have been shown to have beneficial health effects against several chronic diseases including cancer. Diallyl sulfide (DAS), an organosulfur compound present in garlic, is well known for its chemopreventive properties in several tumor models. The pharmacologic role of DAS in prevention and treatment of cancer is well documented in the literature, but its molecular mechanism of action is not yet well defined. In the present study, modulation in p53 expression by topical application of DAS was recorded in 7,12-dimethylbenz[a]anthracene (DMBA)–induced skin tumors in Swiss albino mice. Western blot analysis and immunohistochemical protein detection, combined with multivariable flow cytometry, show that DAS application induces the expression of the wild-type (wt) p53 and down-regulates the expression of mutant (mut) p53. Immunoblotting analysis of tumors showed significant increase in levels of wtp53 by DAS application, whereas for mutp53 the DMBA-induced levels of protein were found to reduce to near normal levels with DAS application. The quantitative analysis of immunostained skin/tumor sections using image analysis and quantitative stereology showed 66.6% and 54.2% increases in wtp53 levels and 53.4% and 44.3% decreases in mutp53 levels in animals where DAS was applied 1 hour prior to or 1 hour after DMBA application, respectively. Flow cytometric analysis further confirmed modulation of wtp53 and mutp53 protein in DAS-supplemented tumors. The increase in the expression of wt tumor suppressor gene protein p53 was accompanied by elevation of the levels of cyclin-dependent kinase inhibitor p21/waf1. The percentage increase in the levels of p21/waf1 was found to be 72.9% and 61.3%, respectively, in DAS-supplemented groups before and after administration. These results thus show that DAS is a potential chemopreventive agent capable of modulating and regulating the tumor suppressor p53 along with its downstream effective molecule, p21/waf1. Thus, DAS can be a potential chemopreventive agent against skin tumor development.

Increase in wild-type p53 stability and transactivational activity by the chemopreventive agent apigenin in keratinocytes

Apigenin, a naturally occurring, non-mutagenic flavonoid, has been shown to inhibit UV-induced skin tumorigenesis in mice when topically applied. In this report we have used the mouse keratinocyte 308 cell line, which contains a wild-type p53 gene, to study the effect of apigenin treatment on p53 protein levels and the expression of its downstream partner, p21/waf1. Cells were treated with 70 microM apigenin for various times and levels of p53 and p21/waf1 protein were assessed by western blot analysis. The level of p53 protein was induced 27-fold after 4 h of apigenin treatment and levels remained elevated through 10 h of exposure. After 24 h of exposure to 70 microM apigenin, p53 protein levels returned to control levels. p21/waf1 protein levels increased approximately 1. 5-2-fold after 4 h and remained elevated at 24 h. To investigate the mechanism of p53 protein accumulation, we compared the half-life of p53 protein in vehicle- and apigenin-treated cells. Cells were incubated for 4 h in the presence of apigenin, then cycloheximide was added to inhibit further protein synthesis and p53 protein levels were measured by western blot. The half-life of p53 protein was found to be increased an average of 8-fold in apigenin-treated cells compared with vehicle-treated cells (t(1/2) = 131 min versus 16 min in apigenin- versus vehicle-treated cells, respectively). The mechanism of p53 protein stabilization is currently being investigated. To determine whether p53 was transcriptionally active, we also performed gel mobility shift assays and transient transfection studies using a luciferase plasmid under the control of the p21/waf1 promoter. Both p53 DNA-binding activity and transcriptional activation peaked after 24 h of exposure to apigenin. These studies suggest that apigenin may exert anti-tumorigenic activity by stimulating the p53-p21/waf1 response pathway.