Effects of smoking on human telomerase reverse transcriptase expression in the skin

Background Telomeres are DNA–protein complexes that cap chromosomal ends, promoting chromosome stability. Telomerase is a ribonucleoprotein complex with a direct telomere protective function. Telomere shortening represents lifetime exposure to oxidative stress and is negatively correlated with age, smoking, and mortality. Smoking increases oxidative DNA modification and thus may influence telomere dynamics and human telomerase reverse transcriptase (hTERT) activity. Objectives This study investigated the effect of smoking on hTERT expression in the skin of smokers and non‐smokers. Methods A cross‐sectional study in 20 current smokers and 20 non‐smokers was conducted. Three‐mm punch skin biopsies were obtained. Biopsies were examined in routine hematoxylin and eosin staining and immunohistochemistry to investigate expression of hTERT. Results All skin biopsies from smokers and non‐smokers showed cytoplasmic staining in epidermal cells. Sections positive for hTERT expression showed nuclear and some nucleolar staining in cells of the basal and suprabasal layers. In the dermis, hTERT expression was present in some skin appendages. The epidermis of smokers showed positive hTERT in 55% and negative hTERT in 45% of biopsies. The epidermis of non‐smokers showed positive hTERT in 70% and negative hTERT in 30% of biopsies (P > 0.05). Among smokers, 20% showed positive and 80% showed negative hTERT expression in the dermis. Among non‐smokers, 30% showed positive and 70% showed negative hTERT expression in the dermis. A higher mean pack year value was found in subjects with negative rather than positive hTERT expression (P