Suicide gene transfer has been study extensively for therapies in various human diseases. We can evaluate cellular activity of thymidine kinase and cytotoxic effect in colon cancer cells after suicide gene transfer. We observed cellular expression of green fluorescence protein after transfer with adenovirus into colon adenocarcinoma HCT-15 cells. After transfer HSVtk, we also estimated thymidine kinase activity using [3H]-penciclovir and cellular cytotoxicity by MTT assay. After transfer green fluorescence protein into HCT-15 cells, we could observed fluorescence expression in 10 moi concentration. Expression level of green fluorescence protein markedly increased in 30 moi and most of HCT-15 cells expressed green fluorescence protein in 100 moi. By infection with HSVtk in HCT-15 cells and HT-29 cells, thymidine kinase activity in HCT-15 cells was about two fold higher than that HT-29 cells. Thymidine kinase activity at 1 moi concentration makes no difference with 0 moi in both cells. At 10 moi concentration, thymidine kinase activity increased about three fold compared with 1moi in HCT-15 cells, but not observed high increase in HT-29 cells. Thymidine kinase activity at 100 moi showed about three fold increase in HCT-15 cells and one and a half fold in HT-29 cells compared with 10 moi. By treatment of HSVtk at various mois and ganciclovir to HCT-15 cells, we could find that increased cytotoxic effect according to HSVtk concentration. Cellular cytotoxic effect was slightly appeared at 5 moi concentration and intensively increased at 30 moi concentration, dead colon cancer cells were reached about 30% of total colon cancer cells. Cellular cytotoxic effect was consistently increased until 50 moi, and about 50% of cells at 100 moi and less then 50% of HCT-15 cells at 200 moi were survived. Finally, we can identify that suicide gene transfer into HCT-15 cells is performed according to concentration of suicide gene and thymidine kinase activity also increase with HSVtk concentration in both HCT-15 cells and HT-29 cells. Additionally, we also find that suicide gene therapy by HSVtk with ganciclovir intensively increase cellular cytotoxicity in colon cancer cells. Therefore, our findings suggest that suicide gene therapy by HSVtk can affect cytotoxicy for colon cancer cells and eventually seems to influence therapeutic efficacy.

Dendropanax morbifera Léveille (Araliaceae) is an endemic species growing in the south-western part of South Korea and has been used in folk medicine and health functional food. Several studies have indicated that extract of D. morbifera (DP) has cytotoxic activities on a number of human cancers, such as, breast cancer, lung cancer, hepatoma, and chorioepithelioma. Recently, polyacetylene and triterpene compounds have been isolated from the DP and showed to have anti-complement activity. β-Amyrin, α-amyrin, dendropanoxide, and β-sitosterol are isolated from DP. However, its biological activities in cancer have not yet been clearly elucidated. In this study, we evaluated the anti-cancer activity of isolated triterpenoids from the DP leaves by measuring the levels of cytotoxicity against MCF-7 human breast cancer and A549 human lung cancer cells. Six triterpenoids were isolated from the n-hexane fraction of DP leaves along with the known compounds. β-amyrin (1), α-amyrin (2), olean-12-en-3,24 β-diol (3), dendropanoxide (4), β-sitosterol (5), and stigmasterol (6). Compound 3 and 6 were isolated from DP for the first time. Cytotoxic activities of six compounds were evaluated against two human cancer cell lines by using the MTT in vitro assay. Among them, five compounds (1, 2, 4, 5, and 6) showed moderate cytotoxic activities toward the tested cell lines, and were safe to normal cells. Western blot analysis showed a decreased expression of anti-apoptotic protein Bcl-2 and increased levels of pro-apoptotic protein Bax in MCF-7 and A549 cells treated by β-amyrin and α-amyrin. Flow cytometry analysis confirmed that five compounds (1, 2, 4, 5, and 6) treatment increased populations of sub-G1 (apoptosis) phase. The results of the present study revealed that triterpenoids from DP have the potential for further development as anticancer agents.