Expression of gelatinases (MMP-2, MMP-9) and gelatinase activator (MMP-14) in actinic keratosis and in in situ and invasive squamous cell carcinoma.

Given the established role of matrix metalloproteinases (MMPs) in physiological processes in the skin, we investigated the expression of MMP-2, MMP-9, and MMP-14 to evaluate their role in the grading and development of atypical epithelial lesions. Immunohistochemistry was performed using antibodies against these MMPs in actinic keratosis (AK; n = 24), squamous cell carcinoma (SCC) in situ (SCCIS; n = 27), SCC well differentiated (SCCWD; n = 28), and SCC moderately to poorly differentiated (SCCMPD; n = 20). Tumoral and stromal expression was assessed by intensity (SI) and percentage positivity (PC). The mean of the total score, calculated by adding intensity and percentage positivity, was used for statistical analyses. In AK, SCCIS, SCCWD, and SCCMPD, mean tumoral MMP-2 expression was 3.33, 4.07, 4.46, and 3.40, respectively (P = NS for all) and stromal expression was 1.42, 3.26, 3.07, and 1.55 respectively (P < 0.05 for AK vs. SCCIS/SCCWD and SCCMPD vs. SCCIS/SCCWD); mean tumoral MMP-9 expression was 4.33, 4.11, 4.46, and 3.35, respectively, and stromal expression was 4.29, 4.41, 4.75, and 4.60, respectively (P = NS for all) and, mean tumoral MMP-14 expression was 1.58, 2.41, 0.32, and 0.35, respectively (P < 0.05 AK vs. SCCWD and SCCIS vs. SCCWD/SCCMPD) and stromal expression was 3.04, 3.52, 0.46, and 0.60, respectively (P < 0.05 for AK vs. SCCWD/SCCMPD). Only MMP-14 showed a statistically significant linear trend with decreasing values for tumoral and stromal expression with invasion suggesting that it might be of use as a prognosticator. Enhanced stromal MMP-2 expression in SCCIS and SCCWD relative to AK suggests that it may be of relevance to disease progression.

Polypodium leucotomos extract decreases UV-induced Cox-2 expression and inflammation, enhances DNA repair, and decreases mutagenesis in hairless mice.

UV-irradiated skin and UV-induced tumors overexpress the inducible isoform of cyclooxygenase-2 (Cox-2), and Cox-2 inhibition reduces photocarcinogenesis. To evaluate photoprotective effects of Polypodium leucotomos extract (PL), hairless Xpc(+/-) mice were fed for 10 days with PL (300 mg/kg) or vehicle then UV-irradiated, once. By 24 hours, UV-induced Cox-2 levels were increased in vehicle-fed and PL-fed mice, whereas by 48 and 72 hours, Cox-2 levels were four- to fivefold lower in PL-fed mice (P < 0.05). p53 expression/activity was increased in PL-fed versus vehicle-fed then UV-irradiated mice. UV-induced inflammation was decreased in PL-fed mice, as shown by approximately 60% decrease (P < 0.001) in neutrophil infiltration at 24 hours, and macrophages by approximately 50% (<0.02) at 24 and 48 hours. By 72 hours, 54 +/- 5% cyclobutane pyrimidine dimers remained in vehicle-fed versus 31 +/- 5% in PL-fed skin (P < 0.003). The number of 8-hydroxy-2'-deoxyguanosine-positive cells were decreased before UV irradiation by approximately 36% (P < 0.01), suggesting that PL reduces constitutive oxidative DNA damage. By 6 and 24 hours, the number of 8-hydroxy-2'-deoxyguanosine-positive cells were approximately 59% (P < 0.01) and approximately 79% (P < 0.03) lower in PL-fed versus vehicle-fed mice. Finally, UV-induced mutations in PL-fed-mice were decreased by approximately 25% when assessed 2 weeks after the single UV exposure. These data demonstrate that PL extract supplementation affords the following photoprotective effects: p53 activation and reduction of acute inflammation via Cox-2 enzyme inhibition, increased cyclobutane pyrimidine dimer removal, and reduction of oxidative DNA damage.