Synergistic effect of radachlorin mediated photodynamic therapy on propolis induced apoptosis in AMC-HN-4 cell lines via caspase dependent pathway

SummaryBackgroundPhotodynamic therapy (PDT) is alternative method for treating malignant tumors based on the principle of photodynamic damage to tumor cells through a photochemical reaction. Because of its localized effect, photodynamic therapy has become a very popular alternative treatment for cancer. PDT in combination with other drugs has been reported to have synergistic effects on various chemotherapeutic drugs. Thus for this synergistic effect of photodynamic therapy in combination with various chemotherapeutic drugs has gained the major interests to the scientists in recent days. Studies have been carried out to treat various ailments like cancer with this combination therapy. However, PDT in combination with biologically active natural product has not yet been studied in detail. One of the natural products which have been used as a folk medicine for many centuries is propolis. It is a resinous hive product collected from various plant materials by honeybees. It is reported to exhibit several biological activities.MethodsIn this study, we focused on the effect of propolis and radachlorin-mediated PDT on human head and neck cancer cells AMC-HN-4. After the administration of propolis and radachlorin followed by laser irradiation, the viability of AMC-HN-4 cells was analyzed using MTT assay. The cells were also stained with Hoechst 33342 and propidium iodide (PI) for morphological observations. For more detailed evaluation and observation, flowcytometric analysis and western blotting were also carried out after congruent treatment process.ResultsFrom the result it was found that the proliferation of AMC-HN-4 cells was inhibited by propolis. The inhibition of cell proliferation was increased when the cells were treated in combination. The rate of cell death was also increased in combination. The expressions of different proteins related to apoptosis were also regulated significantly.ConclusionsThus the results of this study indicate that the apoptosis and anti-proliferation efficacy of propolis were significantly enhanced in combination therapy, compared to the individual treatment of PDT or propolis.