Related Experiment Videos
Unexpected cytokinetic effects induced by puromycin include a G2-arrest, a metaphase-mitotic-arrest, and apoptosis
1Department of Haematology, School of Pathology, South African Institute for Medical Research, Johannesburg.
Abstract:
The potent effects of low doses of PM on the cell cycle have to date been obscured by the conventional usage of this drug at high concentrations (5-50 micrograms/ml) to inhibit protein synthesis. In this in vitro study undertaken in a variety of malignant and non-malignant human and murine cell types, we found that low doses of PM (0.1-0.5 microgram/ml) disrupted significant phase-to-phase cell cycle transitions, causing a G2-arrest, a metaphase-mitotic-arrest, and apoptosis. In HL-60 cells these observations were elicited by PM concentrations starting at 0.1 microgram/ml, and were more pronounced at slightly higher PM concentrations, including that (0.5 microgram/ml) which inhibited [14C]leucine incorporation by approximately 20% after one hour, and by approximately 50% after 24 h. A concentration of CHX (0.25 microgram/ml) which was equivalent to 0.5 microgram/ml of PM, both in terms of molarity (0.9 microM) and degree of inhibition of [14C]leucine incorporation, failed to induce similar changes to those induced by PM. This suggests that at these particular concentrations the PM-induced changes were likely to have been related to the different mechanisms of protein synthesis inhibition exerted by these two 'classical' translation inhibitors. PM but not CHX generates nascent peptidyl-PM complexes (PMPs), and we therefore propose that the subsequent intracellular effects exerted by the PMPs may account, in part, for the differential cytokinetic effects elicited by these drugs. The role of PM is currently being evaluated in vivo as a low-dose component of a multidrug chemotherapeutic regimen in which its cell cycle-specific effects could potentially be synergistic with other agents.
Insights
Low doses of protein மருந்துகள் (PM) disrupt cell cycle transitions, causing G2-arrest, mitotic arrest, and apoptosis. These effects, distinct from cycloheximide (CHX), may involve nascent peptidyl-PM complexes, suggesting potential in combination chemotherapy.
Area of Science:
- Molecular Biology
- Cell Biology
- Pharmacology
Background:
- Protein மருந்துகள் (PM) are conventionally used at high concentrations (5-50 µg/ml) to inhibit protein synthesis.
- The effects of low-dose PM on cell cycle regulation have not been extensively studied.
- Understanding PM's distinct mechanisms is crucial for novel therapeutic applications.
Purpose of the Study:
- To investigate the effects of low-dose PM on cell cycle progression in various human and murine cell types.
- To compare the cellular effects of PM with cycloheximide (CHX) at equivalent concentrations and protein synthesis inhibition levels.
- To elucidate the potential mechanisms underlying PM's cell cycle-specific effects.
Main Methods:
- In vitro cell culture studies using malignant and non-malignant human and murine cell lines.
- Treatment with varying concentrations of PM (0.1-0.5 µg/ml) and CHX (0.25 µg/ml).
- Assessment of cell cycle phase distribution (G2-arrest, mitotic arrest) and apoptosis induction.
- Measurement of [14C]leucine incorporation to quantify protein synthesis inhibition.
Main Results:
- Low doses of PM (0.1-0.5 µg/ml) induced significant G2-arrest, metaphase-mitotic arrest, and apoptosis across tested cell types.
- PM-induced effects were observed at concentrations as low as 0.1 µg/ml in HL-60 cells.
- Equivalent concentrations of CHX did not induce similar cell cycle disruptions, despite comparable protein synthesis inhibition.
- PM, unlike CHX, generated nascent peptidyl-PM complexes (PMPs).
Conclusions:
- Low-dose PM exhibits potent cell cycle-disrupting activities, including G2-arrest, mitotic arrest, and apoptosis.
- The observed effects are likely mediated by mechanisms distinct from CHX, potentially involving PMPs.
- These findings suggest PM's potential as a cell cycle-specific agent in combination chemotherapy regimens.