ABSTRACT
Photodynamic therapy (PDT) employing exogenous photosensitizers is currently being approved for treatment of basal cell carcinoma (BCC). 2-(4-Aminophenyl)benzothiazoles (6) consist of chromophoric structure and absorb light in the UVA (315-400 nm). These results encouraged us to design and synthesize a diversity of 2-phenylbenzothiazoles (6). Studies on the apoptotic mechanism involved in photosensitive effects induced by UVA-activated 6 in BCC cells are carried out in the present article. 6-UVA-treated cells displayed several features of apoptosis, including an increase in the sub-G1 population, a significantly increased annexin V binding, and activation of caspase-3. 6-UVA induced a decrease in mitochondrial membrane potential (Deltapsi(mt)) and ATP via enhanced ROS generation and promoted phosphorylation of extracellular signal-regulated kinase (ERK) and p38 MAPK expression. These results suggest that 6-UVA elicits photosensitive effects in mitochondria processes which involve ERK and p38 activation, and ultimately lead to BCC cell apoptosis.
Subject(s)
Benzothiazoles/chemistry , Benzothiazoles/pharmacology , Carcinoma, Basal Cell/drug therapy , Photosensitizing Agents/chemistry , Photosensitizing Agents/pharmacology , Apoptosis/drug effects , Apoptosis/radiation effects , Benzothiazoles/chemical synthesis , Cell Line, Tumor , Cell Survival/drug effects , Cell Survival/radiation effects , Humans , MAP Kinase Signaling System/drug effects , Mitochondria/drug effects , Mitochondria/pathology , Mitochondria/radiation effects , Photochemotherapy , Photosensitizing Agents/chemical synthesis , Ultraviolet RaysABSTRACT
A series of novel thiobenzanilides is described. These compounds have been previously found to show strong biological activity such as antimycotic and antifungal actions. This is the first demonstration on the mechanism of the anticancer effect of thiobenzanilide agents (4a-c) on human melanoma A375 cells. The cytotoxic studies of compounds 4a-c on human melanoma A375 cells indicate thiobenzanilides induced higher cytotoxicity than nitrobenzanilides (3a-c). In addition, DNA flow cytometric analysis shows that 4a-c displays a significant G2/M phase arrest, which progresses to early apoptosis as detected by flow cytometry after double-staining with annexin V and propidium iodide (PI). Because cellular apoptosis is often preceded by the disruption of mitochondrial function, the assessment of mitochondrial function in 4a-c-treated cells is worthy of investigation. Our data revealed that treatment of A375 cells with 4a-c resulted in the loss of mitochondrial membrane potential (DeltaPsi(mt)), a reduction of ATP synthesis, increased reactive oxygen species (ROS) generation, and activation of caspase-3. Thus, we suggest that 4a-c agents are potent inducers of cell apoptosis in A375 cells.
