Expression Levels of the microRNA Processing Enzymes Drosha and Dicer in Epithelial Skin Cancer

Background: Dysregulation of microRNA (miRNA) metabolism has been observed in a variety of human cancers. In this pilot study, we investigated expression profiles of the two most important enzymes of the miRNA machinery, Drosha and Dicer, in relation to epithelial skin cancer and its premalignant stage. Methods: Patients with premalignant actinic keratoses (AK, n = 6), basal cell carcinomas (BCC, n = 15), and squamous cell carcinomas (SCC, n = 7) were included in the study. Punch biopsies were harvested from the center of the tumors (lesional) as well as from sites of healthy skin (intraindividual controls). Skin samples (n = 14) were also obtained from healthy subjects for additional controls. Dicer and Drosha mRNA levels were detected by quantitative real-time reverse transcriptase polymerase chain reaction. Results: Drosha expression levels were significantly upregulated in both the BCC and SCC groups compared to those in the healthy controls (p < .01), while Dicer expression levels in the BCC group were significantly lower (p < .05). Dicer expression in the SCC group was significantly higher compared to intraindividual controls (p < .05), while Dicer expression levels in both the SCC and AK groups were not significantly different from healthy control samples (p > .05). In the premalignant AK group, we could not observe any significant difference in Drosha or Dicer expression levels compared to either healthy or intraindividual controls (p >.05). Conclusions: We observed dysregulation of Drosha and Dicer expression in epithelial tumors when compared to healthy control samples. Therefore, we favor the hypothesis that miRNAs are involved in the carcinogenesis of epithelial skin cancer.