JOURNAL OF COSMETIC SCIENCE 86 papillae cells to UV radiation causes an increase in the expression of SA-β-Gal indicating the cells are expressing biochemical signatures of premature senescence (Figure 6). Treatment with Hexapeptide-11 shows a dose-dependent, statistically signifi cant decline in SA-β-Gal indicating reduced senescence at the 0.5% and 1.0% treatment levels. CONCLUSION Senescence, whether replicative or stress-induced, can be detected in both fi broblasts and dermal papillae cells through analysis of ATM protein expression and SA-β-Gal activity. A hexapeptide originally isolated from S. cerevisiae fermentation lysates and later synthe- sized at high purity when applied to both intrinsically and extrinsically aged fi broblasts in vitro was found to reduce gene expression of ATM and SA-β-Gal proteins in a dose- dependent fashion. Application of Hexapeptide-11 reduced ATM protein expression in fi broblasts that have undergone SIPS using H2O2 and those grown through intrinsic ag- ing cycles. SA-β-Gal activity was reduced in intrinsically aged fi broblasts exposed to Hexapeptide-11 as well. A method of using UV light to induce SIPS in dermal papillae was also developed. It was shown that Hexapeptide-11 also decreased SA-β-Gal activity in UV-irradiated dermal papillae cells. This suggests that the hexapeptide can delay senescence in a second dermal cell line. The infl uence of Hexapeptide-11 on senescence-associated aging appears to be broadly applicable and reversible. To date, this may represent the fi rst known peptide to possess these attributes. The impact of these fi ndings is being further substantiated on ex vivo models. The results of these fi ndings will be reported at a later date. REFERENCES (1) J. A. Knight, The Biochemistry of aging, Adv. Clin. Chem., 35, 1–62 (2000). (2) L. Hayfl ick and P.S. Moorhead, The serial cultivation of human diploid cell strains, Exp. Cell Res., 25, 585–621 (1961). (3) L. Hayfl ick, The limited in vitro lifetime of human diploid cell strains, Exp. Cell Res., 37, 614–636 (1965). Figure 6. Analysis of SA-β-Gal expression in UV-induced prematurely senescent human dermal papillae cells compared against nonirradiated cells.

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