Lichens exerts an anti-proliferative effect on human breast and lung cancer cells through induction of apoptosis

Abstract

Successful cancer treatment still requires new complexes or compounds from natural sources. Therefore, we investigated anti-growth/apoptotic effects of methanol extracts of the lichen species (Xanthoparmelia somloensis (Gleyn.) Hale, Usnea intermedia (A. Massal.) Jatta, Bryoria capillaris (Ach.) Brodo & D. Hawksw and Lobaria pulmonaria (L.) Hoffm.) on human lung (A549, H1299) and breast (MCF-7, MDA-MB-231) cancer cell lines. Anti-growth effects were monitored by the MTT and ATP viability assays. Cell death mode was evaluated by employing the fluorescence staining of nucleus, caspase-cleaved cytokeratin 18 detection, caspase 3/7 activity assay, Anneksin V cytofluorimetric assay and mitochondria membrane potential assay. Among the lichen extracts, Usnea intermedia exhibited strong anti-growth activity in a dose-dependent manner (1.56–100 µg/ml) compared to the others. Usnea intermedia was especially cytotoxic against MDA-MB-231 and H1299 cells (IC₅₀ value for was found 3.0 and 10.2 μg/ml respectively). The cytotoxicity was resulted from apoptosis as proved by the presence of pyknotic nuclei, caspase 3/7 activity, phosphatidylserine translocation and loss of mitochondria membrane potential. In conclusion, Usnea intermedia warrants for further in vivo evaluation as a new alternative in cancer treatment.

Keywords:

• Apoptosis
• cancer cell death
• cytotoxicity
• lichens
• Usnea intermedia

Acknowledgement

The authors would like to thank O Akgün (Uludag University, Bursa, Turkey) for his assistance in editing of figures.

Disclosure statement

The authors report no conflicts of interest.

Additional information

Funding

This study was financially supported by the Research Fund of Uludag University for the project that is numbered UAP(F)-2011/42.