Methanol Extract of Usnea barbata Induces Cell Killing, Apoptosis, and DNA Damage against Oral Cancer Cells through Oxidative Stress

Abstract

Some lichens provide the resources of common traditional medicines and show anticancer effects. However, the anticancer effect of Usnproliea barbata (U. barbata) is rarely investigated, especially for oral cancer cells. The aim of this study was to investigate the cell killing function of methanol extracts of U. barbata (MEUB) against oral cancer cells. MEUB shows preferential killing against a number of oral cancer cell lines (Ca9-22, OECM-1, CAL 27, HSC3, and SCC9) but rarely affects normal oral cell lines (HGF-1). Ca9-22 and OECM-1 cells display the highest sensitivity to MEUB and were chosen for concentration effect and time course experiments to address its cytotoxic mechanisms. MEUB induces apoptosis of oral cancer cells in terms of the findings from flow cytometric assays and Western blotting, such as subG1 accumulation, annexin V detection, and pancaspase activation as well as poly (ADP-ribose) polymerase (PARP) cleavage. MEUB induces oxidative stress and DNA damage of oral cancer cells following flow cytometric assays, such as reactive oxygen species (ROS)/mitochondrial superoxide (MitoSOX) production, mitochondrial membrane potential (MMP) depletion as well as overexpression of γH2AX and 8-oxo-2′deoxyguanosine (8-oxodG). All MEUB-induced changes in oral cancer cells were triggered by oxidative stress which was validated by pretreatment with antioxidant N-acetylcysteine (NAC). In conclusion, MEUB causes preferential killing of oral cancer cells and is associated with oxidative stress, apoptosis, and DNA damage.

Pro-Apoptotic Potential of Pseudevernia furfuracea (L.) Zopf Extract and Isolated Physodic Acid in Acute Lymphoblastic Leukemia Model In Vitro

“…In our previous work, we clearly confirmed the direct association of oxygen radicals in gyrophoric acid-mediated DNA damage with apoptosis in HeLa cells [31]. Moreover, several studies have described DNA damage and genotoxicity caused by lichen secondary metabolites in vitro [24,41,45]. To analyze the impact of PSE-and Phy-mediated oxidative stress on DNA in Jurkat cells, DNA double-strand breaks and 8-oxoguanine formation were analyzed as biomarkers of DNA damage.…”

“…In addition, in order to determine the cytotoxic effects of PSE and Phy treatment, reactive oxygen species (ROS) were analyzed. It is known that lichen extracts and isolated/purified secondary metabolites can change the redox status of cancer cells and ROS production or accumulation, which significantly contribute to the initiation and execution of apoptosis, resulting in cytotoxicity [31,40,41]. It is also known that ROS are needed to oxidize cytochrome c, which is then capable of efficient apoptosome formation.…”

Usnic Acid and Usnea barbata (L.) F.H. Wigg. Dry Extracts Promote Apoptosis and DNA Damage in Human Blood Cells through Enhancing ROS Levels

“…Wigg ( U. barbata ) is a fruticose thalli lichen with interesting therapeutic properties [ 11 ]; this species has been used for thousands of years in traditional medicine worldwide to treat various diseases [ 12 ]. The wide range of bio-activities (antioxidant [ 13 ], antimicrobial [ 14 ], anti-inflammatory [ 15 ], anticancer [ 16 ], cytotoxic [ 17 ], pro-oxidant [ 18 ]) is due to the content of active secondary metabolites [ 19 ] synthesized by the mycobiont (lichen-forming fungus) [ 20 ]. The phytochemical profile of U. barbata is already known.…”

Cyclovirobuxine D Induces Apoptosis and Mitochondrial Damage in Glioblastoma Cells Through ROS-Mediated Mitochondrial Translocation of Cofilin

“…Previous reports have suggested that excessive production of ROS by exogenous means is more harmful to cancer cells (22). For instance, increasing ROS by exogenous drugs can cause apoptosis, DNA damage, or mitochondrial dysfunction of several cancers, including colorectal cancer, oral cancers, and breast cancer cells (44)(45)(46). We found that the effect of CVBD in inducing GBM cell apoptosis is related to the increase of intracellular ROS.…”