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Differing responses of G2-related genes during differentiation of HL60 cells induced by TPA or DMSO
1Department of Internal Medicine, Aoto Hospital, Jikei University School of Medicine, Tokyo, Japan.
Abstract:
Differentiation leads to the cessation of cellular proliferation, but little is known about the molecular mechanisms of growth arrest. We compared the effect of two differentiation inducers, 12-o-tetradecanoyl 13-acetate (TPA) and dimethyl sulfoxide (DMSO) on both the cell-cycle and the modulation of G2-related genes in synchronized HL60 cells. TPA treatment of HL60 cells resulted in G1 arrest within 24 h. In contrast, the cell cycling of DMSO-treated cells was initially accelerated and they progressed to the second cycle before accumulating in the G1 phase. Expression of cyclin B, cdc25, wee1 and cdc2 was studied during cell cycle arrest by Northern blot hybridization. Expression of cyclin B, cdc25 and cdc2 fluctuated in association with cell cycle progression towards the G2/M phase, while wee1 expression remained constant in untreated cells. These four genes were highly expressed in TPA-treated cells for the first 12 h, but drastic down-regulation was seen at 18 h and expression became undetectable after 24 h. In contrast, no remarked changes of gene expression were seen in DMSO-treated cells. These findings suggest that cell cycle progression along with the initial process of differentiation in response to TPA differs from the response to DMSO and that the down-regulation of cdc2 expression by TPA-treated HL60 cells contributes to endorsement of G1 arrest.
Insights
12-o-tetradecanoyl 13-acetate (TPA) and dimethyl sulfoxide (DMSO) induce distinct cell cycle arrest mechanisms in HL60 cells. TPA down-regulates G2-related gene expression, promoting G1 arrest, unlike DMSO.
Area of Science:
- Cell Biology
- Molecular Biology
- Cancer Research
Background:
- Cellular differentiation typically halts proliferation, but the molecular control of growth arrest remains unclear.
- Understanding cell cycle regulation is crucial for cancer research and therapeutic development.
Purpose of the Study:
- To compare the effects of TPA and DMSO on cell cycle progression and G2-related gene expression in HL60 cells.
- To elucidate the molecular mechanisms underlying TPA- and DMSO-induced growth arrest.
Main Methods:
- Synchronized HL60 cells were treated with TPA or DMSO.
- Cell cycle progression was monitored.
- Expression of G2-related genes (cyclin B, cdc25, wee1, cdc2) was analyzed using Northern blot hybridization.
Main Results:
- TPA induced G1 arrest within 24 hours.
- DMSO treatment initially accelerated cell cycling before causing G1 accumulation.
- TPA treatment led to significant down-regulation of cyclin B, cdc25, wee1, and cdc2 expression, particularly after 18 hours.
- DMSO treatment showed no significant changes in the expression of these G2-related genes.
Conclusions:
- TPA and DMSO elicit different cellular responses and cell cycle progression patterns during differentiation.
- Down-regulation of cdc2 expression by TPA is a key mechanism contributing to G1 arrest in HL60 cells.
- These findings provide insights into the distinct molecular pathways governing differentiation-induced growth arrest.