Photodynamic therapy induces microRNA-210 and -296 expression in HeLa cells.

Apoptosis-related microRNAs (miRNAs), the expression levels of which were observed to increase after photodynamic therapy (PDT), were identified as markers of PDT efficacy. miRNAs form a class of small endogenous RNAs that play important regulatory roles by targeting mRNA for cleavage or translational repression. miRNAs contribute to diverse biological processes, including development, cell growth, apoptosis, and hematopoiesis, which suggests a role in cancer development. However, no previous reports have described a relationship between apoptosis and miRNA expression after PDT. In this study, apoptosis-related miRNA levels were characterized by real-time PCR after PDT in HeLa cells. miR-210 and miR-296 expression levels increased 1 hour after PDT, although the other apoptosis-related miRNA (miR-7, miR-148a, miR-204, and miR-216) expression levels were unchanged. Since miR-210 is the most prominent miRNA consistently stimulated under hypoxic conditions and VEGF is capable of increasing miR-296 expression levels, these data suggest that hypoxia induced by PDT induces miR-210 expression, followed by an increase of VEGF expression and miR-296 expression. These results constitute the first report of an analysis of miRNA expression after PDT using talaporfin sodium as a photosensitizer, demonstrating that miR-210 and miR-296 expression levels are markers of PDT efficacy in HeLa cells.