AbstractBackground and Purpose: Cancer is a leading cause of death worldwide. Artemisinin (ARS) and its derivatives are extremely effective against malarial infections and have also shown good activity against tumouric cells, with the greatest activity reported against leukaemia and colon cancer cell lines. The current study aimed to investigate the antitumour activities and underlying mechanisms of action of novel derivatives of dihydroartemisinin (DHA) designed to target DNA (such as LLP246, SL2935) were evaluated against cultured HT29-AK (colon cancer cells) and HL-60 (leukaemia cells) cell lines. The activity of newly synthesised tetraoxane dimers (RKA152M, RKA153, RKA154, RKA155, RKA157 and RKA160) were also evaluated against the cells.
Methods: The cancer cells were incubated with the test compounds and assessed for cytotoxicity by MTT assay and cellular levels of sTfR by ELISA. The effects of drug treatment on apoptosis were evaluated by measuring levels of cleaved caspase-3, P-AKT and survivin by flow cytometric analyses and ELISA, respectively. Their effects on DNA fragmentation was assessed by gel electrophoresis and a scratch assay backed by trypan blue dye exclusion were used to evaluate the effects of the lead compounds on cell migration/wound healing.
Key Results: The test compounds showed potent cytotoxic effects against HT29-AK and HL-60 cells. LLP246 showed ~13.7 fold greater activity than DHA (IC50 of 4.47±0.39 μM vs 61.39±2.86 μM). Among the tetraoxane dimers, RKA160 (IC50 of 22.85±4.36 μM) displayed ~2.7 fold greater activity than DHA against HT29-AK cells. The tetraoxane dimers showed less cytotoxicity against HL-60 cells as compared to DHA (IC50 of 0.39±0.10 μM). There were measurable levels of sTfR in the cells, but the effects of the drugs were variable. Drug treatment caused increased activity of cleaved caspase-3 in the cell, P-AKT, DNA fragmentation, but decreased cellular survivin levels in the cells. All the test compounds showed a concentration-dependent inhibition of cell migration/wound healing supported by a concentration-dependent increase in dead cells.
Conclusions and Implications: Data from these studies suggest that the cytotoxicity of the test compounds is may be mediated by an iron-dependent mechanism, stemming from the identification of sTfR in the cells. The agents caused apoptosis by an increase in cellular levels of cleaved caspase-3 and decreased survivin concentrations. A potent inhibitory activity against the capacity of the wound to heal was measured. Overall, these agents may have utility (alone or in combination with conventional chemotherapeutic agents) against a variety of cancer cell types.
|Date of Award||2013|