Short-term in vitro exposure to crocetin promotes apoptosis in human leukemic HL-60 cells via intrinsic pathway

Abstract

Acute promyelocytic leukemia (APL) is one of the most threatening hematological malignant cancers. Defects in the cell growth and apoptotic pathways are responsible for both the disease pathogenesis and its resistance to therapy. Crocetin, a naturally occurring dietary carotenoid compound, is abundantly found in various plants including Crocus sativus. It has shown chemopreventive and anticancer effects. This study is designed to investigate the apoptogenic potential of crocetin and its underlying mechanism in acute human leukemia HL-60 cells versus normal human polymorph nuclear (PMN) cells. Resazurin assay was used to determine the viability of HL-60 and PMN cells following treatment with crocetin (5-100 µM) and ATRA (10 µM, as positive control) for 24-72 h. Sub-G1 cell population and apoptotic cells were detected by flow cytometry using annexin V and propidium iodide labeling. The levels of genes involved in apoptosis (CASP3, CASP8, CASP9, Bax and Bcl-2) were also determined using real time PCR. The results showed that crocetin concentration-dependently decreased cell viability and increased sub-G1 cell population in HL-60 cells, without significant toxicity toward normal PMN cells. Also, crocetin (100 µM)-treated cells significantly showed apoptosis (15.1 ± 1.3) against 18.8 ± 1.4 in ATRA-treated HL-60 cells during 48 h incubation. In addition, the expressions of CASP3 and CASP9 and Bax/Bcl-2 ratio were significantly increased in HL-60 cells, while CASP8 remained unchanged. It was suggested that crocetin promoted apoptosis in HL-60 cells in concentration-dependent manner through induction of intrinsic pathway. In conclusion, this study suggests that crocetin may be utilized as appropriate alternative for ATRA in APL. © 2018 Polish Pharmaceutical Society. All Rights Reserved