RESUMO
BACKGROUND: Doxorubicin (DOX) is a chemotherapy drug that is widely used in cancer therapy, especially in Triple-Negative Breast Cancer (TNBC) patients. Nevertheless, cytoprotective autophagy induction by DOX limits its cytotoxic effect and drug resistance induction in patients. Therefore, finding a new way is essential for increasing the effectiveness of this drug for cancer treatment. OBJECTIVE: This study aimed to investigate the effect of L-lysine on DOX cytotoxicity, probably through autophagy modulation in TNBC cell lines. METHODS: We used two TNBC cell lines, MDA-MB-231 and MDA-MB-468, with various levels of autophagy activity. Cell viability after treatment with L-lysine alone and in combination therapy was evaluated by MTT assay. Reactive Oxygen Species (ROS), nitric oxide (NO) concentration, and arginase activity were assessed using flow cytometric analysis, Griess reaction, and arginase activity assay kit, respectively. Real-time PCR and western blot analysis were used to evaluate the L-lysine effect on the autophagy-related genes and protein expression. Cell cycle profile and apoptotic assay were performed using flow cytometric analysis. RESULTS: The obtained data indicated that L-lysine in both concentrations of 24 and 32 mM increased the autophagy flux and enhanced the DOX cytotoxicity, especially in MDA-MB-231, which demonstrated higher autophagy activity than MDA-MB-468, by inducing ROS and NO production. Furthermore, L-lysine induced G2/M arrest autophagy cell death, while significant apoptotic changes were not observed. CONCLUSION: These findings suggest that L-lysine can increase DOX cytotoxicity through autophagy modulation. Thus, L-lysine, in combination with DOX, may facilitate the development of novel adjunct therapy for cancer.
RESUMO
BACKGROUND: 5-Aminolevulinic acid-mediated photodynamic therapy (ALA-PDT) is an effective and noninvasive modality for treatment of several types of non-melanoma skin cancers. This in-vitro study attempted to know whether the killing effect of ALA-PDT on the human melanoma cells (Mel-Rm cell line) could be increased by the presence of 5-fluorouracil (5-FU). METHODS: To evaluate the effect of ALA-PDT in combination with 5-FU on viability of human melanoma Mel-Rm cells, the cells incubated with 5-ALA and 5-FU for 3h in nontoxic concentrations, and subsequently illuminated with a 630 nm light-emitting diode array. The cells viability and cytotoxicity determined by mitochondrial activity and lactate dehydrogenase assays. RESULTS: Combination of ALA-PDT and 5-FU (FU-ALA-PDT) showed a considerable growth inhibition according to the results of MTT assay compared to ALA-PDT. The results of LDH assay also showed a cytotoxicity effect in ALA-PDT; however, the FU-ALA-PDT showed no significantly enhancement in cytotoxicity compared to ALA-PDT using LDH assay. CONCLUSION: The Mel-Rm cells incubation with 5-FU before PDT enhances the efficiency of 5-Aminolevulinic acid-mediated photodynamic therapy.