Antiproliferative effects of artemisinin on human breast cancer cells requires the downregulated expression of the E2F1 transcription factor and loss of E2F1-target cell cycle genes

Abstract

Artemisinin, a sesquiterpene phytolactone derived from Artemisia annua, is a potent antimalarial compound with promising anticancer properties, although the mechanism of its anticancer signaling is not well understood. Artemisinin inhibited proliferation and induced a strong G1 cell cycle arrest of cultured MCF7 cells, an estrogen-responsive human breast cancer cell line that represents an early-stage cancer phenotype, and effectively inhibited the in-vivo growth of MCF7 cell-derived tumors from xenografts in athymic nude mice. Artemisinin also induced a growth arrest of tumorigenic human breast cancer cell lines with preneoplastic and late stage cancer phenotypes, but failed to arrest the growth of a nontumorigenic human mammary cell line. Concurrent with the cell cycle arrest of MCF7 cells, artemisinin selectively downregulated the transcript and protein levels of the CDK2 and CDK4 cyclin-dependent kinases, cyclin E, cyclin D1, and the E2F1 transcription factor. Analysis of CDK2 promoter-luciferase reporter constructs showed that the artemisinin ablation of CDK2 gene expression was accounted for by the loss of CDK2 promoter activity. Chromatin immunoprecipitation revealed that artemisinin inhibited E2F1 interactions with the endogenous MCF7 cell CDK2 and cyclin E promoters. Moreover, constitutive expression of exogenous E2F1 prevented the artemisinin-induced cell cycle arrest and downregulation of CDK2 and cyclin E gene expression. Taken together, our results demonstrate that the artemisinin disruption of E2F1 transcription factor expression mediates the cell cycle arrest of human breast cancer cells and represents a critical transcriptional pathway by which artemisinin controls human reproductive cancer cell growth.

Development of artemisinin compounds for cancer treatment

“…Results indicate they are toxic to cancer cells with IC 50 s in the 10-20 μM range. Only few studies had simultaneously tested the compounds on normal cells [1,2,[4][5][6][7][8][9][10][11]. In general, artemisinin compounds have been shown to be more toxic toward cancer cells than their corresponding normal cells.…”

“…Tin et al [11] MCF-7 breast cancer mouse xenograft; started when tumors about 35 mm 3 ; artemisinin (100 mg/kg/day, SC) for two weeks.…”

“…Artemisinins affect many different cellular pathways that are involved in cellular development, proliferation, and apoptosis. Apoptosis is a commonly reported effect [6,7,[12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31], as well as arrest in cell cycle [9,11,[32][33][34][35][36][37], particularly at the G 0 /G 1 phases. Thus, both cell death and growth inhibition occur.…”

Nitidine chloride inhibits hepatocellular carcinoma cell growth in vivo through the suppression of the JAK1/STAT3 signaling pathway

“…G1/S checkpoints are located at the end of the G1 phase of the cell cycle, just before entry into the S phase. The CDK4/cyclin D complex phosphorylates the retinoblastoma (Rb) protein, promoting cyclin E expression through its E2F-dependent transcriptional activation and the disruption of the Rb-histone deacetylase (HDAC) complex, culminating in CDK2 kinase activation as the S phase progresses (38,39). Uncontrolled cell division and malignancy occur due to an unchecked or hyper-activated cyclin D1/CDK4 complex.…”

Ethyl acetate extraction from a Chinese herbal formula, Jiedu Xiaozheng Yin, inhibits the proliferation of hepatocellular carcinoma cells via induction of G0/G1 phase arrest in vivo and in vitro

“…Regulating of phosphorylation and dephosphorylation of CDK-cyclin complexes ensure the normal transition of cell cycle stages (17,18). Arresting cell cycle in G1 phase or G2/M phase is one of the mechanisms used by anticancer medicines (19,20).…”