Diosgenin induces cell cycle arrest and apoptosis in human leukemia K562 cells with the disruption of Ca2+ homeostasis

ABSTRACT Inhibition of differentiation has been proposed as an important mechanism for Myc-induced tumorigenesis, but the mechanisms involved are unclear. We have established a genetically defined differentiation model in human leukemia K562 cells by conditional expression of the cyclin-dependent kinase (Cdk) inhibitor p27 (inducible by Zn2+) and Myc (activatable by 4-hydroxy-tamoxifen). Induction of p27 resulted in erythroid differentiation, accompanied by Cdk inhibition and G1 arrest. Interestingly, activation of Myc inhibited p27-mediated erythroid differentiation without affecting p27-mediated proliferation arrest. Microarray-based gene expression indicated that, in the presence of p27, Myc blocked the upregulation of several erythroid-cell-specific genes, including NFE2, JUNB, and GATA1 (transcription factors with a pivotal role in erythropoiesis). Moreover, Myc also blocked the upregulation of Mad1, a transcriptional antagonist of Myc that is able to induce erythroid differentiation. Cotransfection experiments demonstrated that Myc-mediated inhibition of differentiation is partly dependent on the repression of Mad1 and GATA1. In conclusion, this model demonstrates that Myc-mediated inhibition of differentiation depends on the regulation of a specific gene program, whereas it is independent of p27-mediated cell cycle arrest. Our results support the hypothesis that differentiation inhibition is an important Myc tumorigenic mechanism that is independent of cell proliferation.

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Harmine Hydrochloride Induced G2/M Phase Cell Cycle Arrest, Autophagy and Apoptosis in Human Leukemia K562 Cells through Modulation of the MAPK Pathway

10.21203/rs.3.rs-227218/v1 ◽

2021 ◽

Author(s):

Zhilong Liu ◽

Peng Zhang ◽

Na Zhao ◽

Lin-lin Lv ◽

Ziyu Li ◽

...

Keyword(s):

Cell Cycle ◽

Caspase 3 ◽

K562 Cells ◽

Leukemia Cells ◽

Phase Cell ◽

Human Leukemia ◽

Cycle Arrest ◽

Human Leukemia Cells ◽

M Phase ◽

Human Leukemia K562 Cells

Abstract Background Previous studies have indicated that harmine hydrochloride (HAR-HC) has anti-tumor characteristics. However, its potential impact on human leukemia cells is unknown. In this study, we explored the potential mechanism of HAR-HC effects on human leukemia cells in vitro. Methods MTT assay was used to detect cell viability; A flow cytometer was used to analyze the cell cycle; Anexinn V-FITC/PI was used to detect cell apoptosis; Western blotting assay was used to analyze the expression of related proteins. Results The result of flow cytometry suggested G2/M phage arrest in K562 cells induced by HAR-HC. The expression levels of Cyclin E2, Cyclin D1, Bcl-2, Bcl-xL, Mcl-1, pro-caspase-3, and PARP decreased and the expression levels of Cyclin A2, Cyclin B1, p21, Myt-1, p-cdc2 (Tyr15), cleaved -caspase-3 and cleaved-PARP increased. Moreover, the expression of p-JNK and p-ERK1/2 increased and autophagy was induced in the HAR-HC treatment group. Additionally, HAR-HC facilitated autophagy by activating the ERK1/2 pathway. Conclusion HAR-HC induced G2/M phase cell cycle arrest, autophagy and apoptosis by activating the JNK, and ERK1/2 pathways in the human leukemia K562 cells.

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