Parmelia sulcata Taylor and Usnea filipendula Stirt induce apoptosis-like cell death and DNA damage in cancer cells.

OBJECTIVE

Successful cancer treatments still require more compounds to be isolated from natural sources. Thus, we have investigated anti-proliferative/apoptotic effects of methanolic extracts of lichen species Parmelia sulcata Taylor and Usnea filipendula Stirt on human lung cancer (A549, PC3), liver cancer (Hep3B) and rat glioma (C6) cells.

METHODS

Anti-proliferative effects were monitored by MTT and adenosine triphosphate viability assays, while genotoxic activity was studied using the comet assay. Additionally, cell death mode and apoptosis assays (fluorescence staining, caspase-cleaved cytokeratin 18, caspase-3 activity and PARP cleavage) were performed.

RESULTS

Extracts produced anti-population growth effects in a dose-dependent manner (1.56-100 μg/ml) by inducing apoptosis-like cell death. This resulted in the lines having the presence of pyknotic cell nuclei. In addition, significant increase in genetic damage in the cell lines was seen, indicating that DNA damage may have been responsible for apoptotic cell death.

CONCLUSIONS

In this study, methanolic extracts of Parmelia sulcata and Usnea filipendula induced apoptosis-like cell death by causing DNA damage, to cancer cells.