Acta Pharmacologica Sinica 2007 December; 28 (12): 1991-1995; doi: 10.1111/j.1745-7254.2007.00707.x

Aim: The aim of this study was to investigate the effects of aloe-emodin, a natural compound from the root and rhizome of Rheum palmatum, on the growth of human cervical cancer cells, HeLa.

Methods: HeLa cells were treated with various concentrations of aloe-emodin for 1_5 d, and cell growth was measured by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide assay. The long-term growth effect was investigated by crystal violet assay. The distributions of the cell cycle and apoptosis were analyzed by flow cytometry. The alkaline phosphatase (ALP) activity was analyzed by a chemical analyzer. Finally, Western blotting was used to indicate the abundant changes of protein kinase C (PKC), c-myc, cyclins, cyclin-dependent kinases (CDK), and proliferating cell nuclear antigen (PCNA).

Results: Aloe-emodin inhibited the growth of HeLa cells in a dose-dependent manner at concentrations ranging between 2.5 and 40 µmol/L. The flow cytometric analysis showed that HeLa cells were arrested at the G₂/M phase. This effect was associated with the decrease in cyclin A and CDK2, and the increase in cyclin B1 and CDK1. More importantly, the ALP activity was found to be increased by aloe-emodin treatment, and accompanied by the inhibition of PCNA expression. In addition, aloe-emodin suppressed the expression of PKCα and c-myc.

Conclusion: These findings provide a possible mechanistic explanation for the growth inhibitory effect of aloe-emodin on HeLa, which includes cell cycle arrest and inducing differentiation.

Keywords: HeLa cells; cell cycle; aloe-emodin; alkaline phosphatase; c-myc