Characterization of Signalling Pathways That Link Apoptosis and Autophagy to Cell Death Induced by Estrone Analogues
Anne E Mercier1, Renaud Prudent2, Michael S Pepper3
1Department of Physiology, School of Medicine, Faculty of Health Sciences, University of Pretoria, Pretoria 0001, South Africa.
Abstract:
The search for novel anti-cancer compounds which can circumvent chemotherapeutic drug resistance and limit systemic toxicity remains a priority. 2-Ethyl-3-O-sulphamoyl-estra-1,3,5(10)15-tetraene-3-ol-17one (ESE-15-one) and 2-ethyl-3-O-sulphamoyl-estra-1,3,5(10)16-tetraene (ESE-16) are sulphamoylated 2-methoxyestradiol (2-ME) analogues designed by our research team. Although their cytotoxicity has been demonstrated in vitro, the temporal and mechanistic responses of the initiated intracellular events are yet to be determined. In order to do so, assays investigating the compounds' effects on microtubules, cell cycle progression, signalling cascades, autophagy and apoptosis were conducted using HeLa cervical- and MDA-MB-231 metastatic breast cancer cells. Both compounds reversibly disrupted microtubule dynamics as an early event by binding to the microtubule colchicine site, which blocked progression through the cell cycle at the G1/S- and G2/M transitions. This was supported by increased pRB and p27Kip1 phosphorylation. Induction of apoptosis with time-dependent signalling involving the p-JNK, Erk1/2 and Akt/mTOR pathways and loss of mitochondrial membrane potential was demonstrated. Inhibition of autophagy attenuated the apoptotic response. In conclusion, the 2-ME analogues induced a time-dependent cross-talk between cell cycle checkpoints, apoptotic signalling and autophagic processes, with an increased reactive oxygen species formation and perturbated microtubule functioning appearing to connect the processes. Subtle differences in the responses were observed between the two compounds and the different cell lines.
Insights
Novel anti-cancer drugs, 2-Ethyl-3-O-sulphamoyl-estra-1,3,5(10)15-tetraene-3-ol-17one (ESE-15-one) and 2-ethyl-3-O-sulphamoyl-estra-1,3,5(10)16-tetraene (ESE-16), disrupt microtubules and induce apoptosis in cancer cells. These 2-methoxyestradiol analogues show potential for overcoming drug resistance.
Area of Science:
- Pharmacology
- Cancer Biology
- Cell Biology
Background:
- Developing novel anti-cancer compounds is crucial to overcome drug resistance and reduce systemic toxicity.
- 2-Ethyl-3-O-sulphamoyl-estra-1,3,5(10)15-tetraene-3-ol-17one (ESE-15-one) and 2-ethyl-3-O-sulphamoyl-estra-1,3,5(10)16-tetraene (ESE-16) are novel sulphamoylated analogues of 2-methoxyestradiol (2-ME).
Purpose of the Study:
- To determine the temporal and mechanistic intracellular responses of ESE-15-one and ESE-16.
- To investigate the effects of these 2-ME analogues on microtubules, cell cycle, signaling pathways, autophagy, and apoptosis in cancer cells.
Main Methods:
- Utilized HeLa cervical and MDA-MB-231 metastatic breast cancer cell lines.
- Assayed effects on microtubule dynamics, cell cycle progression (G1/S and G2/M transitions), signaling cascades (p-JNK, Erk1/2, Akt/mTOR), autophagy, and apoptosis.
- Measured pRB and p27Kip1 phosphorylation and mitochondrial membrane potential.
Main Results:
- Both compounds reversibly disrupted microtubule dynamics by binding to the colchicine site, leading to cell cycle arrest.
- Induced apoptosis via time-dependent signaling pathways and mitochondrial membrane potential loss.
- Inhibition of autophagy attenuated the apoptotic response, suggesting cross-talk between processes.
Conclusions:
- 2-ME analogues ESE-15-one and ESE-16 induce a time-dependent interplay between cell cycle checkpoints, apoptosis, and autophagy.
- Perturbed microtubule function and increased reactive oxygen species formation appear to link these cellular processes.
- Observed subtle differences in cellular responses between the two compounds and cell lines warrant further investigation.
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