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Programmed cell death in response to chemotherapeutic agents in human germ cell tumour lines
R A Huddart1, J Titley, D Robertson
1Section of Molecular Carcinogenesis, Institute of Cancer Research, Sutton, Surrey, U.K.
Abstract:
Testicular germ cell tumours are amongst the most chemosensitive neoplasms both in vivo and in vitro. In the present study we demonstrate that following exposure to drugs used in chemotherapeutic treatment of testicular germ cell cancer tumour cells undergo death by apoptosis. Thus, after exposure of the GCT27 embryonal carcinoma cell line to cisplatin, we observed the degradation of DNA into oligonucleosomal fragments, which is a hallmark of apoptosis. Furthermore, light, fluorescence and electron microscopy reveal the presence of condensed abnormal shaped nuclear chromatin which is characteristic of apoptosis. Changes diagnostic of apoptosis were also observed following (a) cisplatin treatment of the GCT48 and Susa embryonal carcinoma cell lines and the GCT44 yolk sac tumour cell line and (b) etoposide treatment of the GCT27 and Susa cell lines. When the GCT27 cell line was treated with 15 microns cisplatin, apoptosis was first observed at 6-9 h and greater than 90% of cells were dead within 24 h. Apoptosis was not blocked when cisplatin-treated cells were incubated in the presence of cycloheximide, although this agent did cause a 4-6 h delay in the onset of cell death. In addition, we demonstrated that the GCT27 cell line can be induced to undergo apoptosis by exposure to low concentrations of the calcium ionophore, ionomycin. These observations show that germ cell tumours are remarkably sensitive to a range of agents that act by different mechanisms. They are triggered to undergo apoptosis rapidly by a mechanism that is not blocked by inhibitors of protein synthesis.
Insights
Testicular germ cell tumors are highly sensitive to chemotherapy, undergoing programmed cell death (apoptosis) rapidly. This rapid apoptosis is triggered by various agents and is not inhibited by protein synthesis blockers.
Area of Science:
- Oncology
- Molecular Biology
- Cell Biology
Background:
- Testicular germ cell tumors (GCTs) are highly responsive to chemotherapy.
- Understanding the precise mechanisms of GCT cell death is crucial for optimizing treatment.
Purpose of the Study:
- To investigate the induction of apoptosis in testicular germ cell tumor cells upon exposure to chemotherapeutic agents.
- To characterize the cellular and molecular events associated with chemotherapy-induced GCT cell death.
Main Methods:
- Exposure of various GCT cell lines (GCT27, GCT48, Susa, GCT44) to cisplatin and etoposide.
- Assessment of apoptosis using DNA fragmentation assays, light, fluorescence, and electron microscopy.
- Evaluation of the role of protein synthesis inhibitors (cycloheximide) and calcium ionophores (ionomycin) in apoptosis.
Main Results:
- Chemotherapeutic agents like cisplatin and etoposide induce apoptosis in GCT cell lines.
- Apoptosis is characterized by DNA degradation and condensed nuclear chromatin.
- Apoptosis onset was observed within 6-9 hours and led to >90% cell death within 24 hours.
- The apoptotic process was not blocked by cycloheximide, though a delay was observed.
- Ionomycin also induced apoptosis in GCT cells.
Conclusions:
- Testicular germ cell tumors are highly sensitive to apoptosis induction by diverse chemotherapeutic agents.
- The rapid apoptotic response is triggered by mechanisms independent of protein synthesis.
- These findings highlight the vulnerability of GCTs to apoptosis-inducing therapies.