ABSTRACT
OBJECTIVE: Autophagy and apoptosis play key roles in cancer survival and pathogenesis and are governed by specific genes which have a dual role in both cell death and survival. Arsenic trioxide (ATO) and thalidomide (THAL) are used for treatment of many types of hematologic malignancies. ATO prevents the proliferation of cells and induces apoptosis in some cancer cells. Moreover, THAL has immunomodulatory and antiangiogenic effects in malignant cells. The aim of present study was to examine the effects of ATO and THAL on U937 and KG-1 cells, and evaluation of mRNA expression level of VEGFs genes, PI3K genes and some of autophagy genes. MATERIALS AND METHODS: In this in vitro experimental study, U937 and KG-1 cells were treated by ATO (0.4-5 µM) and THAL (5-100 µM) for 24, 48 and 72 hours. Cell viability was measured by MTT assay. The apoptosis rate and cell cycle arrest were evaluated by flow cytometry (Annexin/PI) and cell cycle flow cytometry analysis, respectively. The effect of ATO/THAL on mRNAs expression was evaluated by real-time polymerase chain reaction (PCR). RESULTS: ATO/THAL combination enhanced cell apoptosis in a dose-dependent manner. Also, ATO/THAL induced SubG1/ G1 phase arrest. mRNA expression levels of VEGFC (contrary to other VEGFs isoform), PI3K, AKT, mTOR, MEK1, PTEN, IL6, LC3 and P62 genes were upregulated in acute myeloid leukemia (AML) cells following treatment with ATO/THAL. CONCLUSION: Combined treatment with ATO and THAL can inhibit proliferation and invasion of AML cells by down-regulating ULK1 and BECLIN1 and up-regulating PTEN and IL6, and this effect was more marked than the effects of ATO and THAL alone.
ABSTRACT
OBJECTIVE: Acute myeloid leukemia (AML) is a clonal disorder of hemopoietic progenitor cells. The Raf serine/threonine (Ser/Thr) protein kinase isoforms including B-Raf and RAF1, are the upstream in the MAPK cascade that play essential functions in regulating cellular proliferation and survival. Activated autophagy-related genes have a dual role in both cell death and cell survival in cancer cells. The cytotoxic activities of arsenic trioxide (ATO) were widely assessed in many cancers. Sorafenib is known as a multikinase inhibitor which acts through suppression of Ser/Thr kinase Raf that was reported to have a key role in tumor cell signaling, proliferation, and angiogenesis. In this study, we examined the combination effect of ATO and sorafenib in AML cell lines. MATERIALS AND METHODS: In this experimental study, we studied in vitro effects of ATO and sorafenib on human leukemia cell lines. The effective concentrations of compounds were determined by MTT assay in both single and combination treatments. Apoptosis was evaluated by annexin-V FITC staining. Finally, mRNA levels of apoptotic and autophagy genes were evaluated using real-time polymerase chain reaction (PCR). RESULTS: Data demonstrated that sorafenib, ATO, and their combination significantly increase the number of apoptotic cells. We found that the combination of ATO and sorafenib significantly reduces the viability of U937 and KG-1 cells. The expression level of selective autophagy genes, ULK1 and Beclin1 decreased but LC3-II increased in U937. CONCLUSION: The expression levels of apoptotic and autophagy activator genes were increased in response to treatment. The crosstalk between apoptosis and autophagy is a complicated mechanism and further investigations seem to be necessary.
