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Origin of microcells in the human sarcoma cell line HT-1080
I Buiķis1, L Harju, T Freivalds
1Latvian Institute of Experimental and Clinical Medicine, Riga.
Abstract:
The aim of this study was to investigate the development of microcells in the human sarcoma cell line HT-1080 after interference with thiophosphamidum. We found that damaged interphase macrocells located at the projection of the nucleolus may form one or several microcells. The micronuclei of the microcells intensively incorporate the thymidine analogue 5-bromo-2'-deoxyuridine and strongly express argyrophilic nucleolar organiser region proteins. At an early phase of the development, the micronuclei contain fragmented DNA, but in subsequent phases, the micronuclei accumulate polymeric DNA, simultaneously with an increase in their size. After desintegration of the damaged macrocell, the microcells appear in the intercellular space. The microcells can enter mitosis and they strongly express the lung resistance protein. Electron microscopic observations suggest that coiled bodies are involved in the development of the microcells. Since the observed path of microcell formation differs from apoptotic cell fragmentation into apoptotic bodies, we propose a new term for this microcell development: sporosis. We suggest that self-renewal of the tumour stem cells is likely based on sporosis.
Insights
Damaged human sarcoma cells can form microcells through a novel process termed sporosis. These microcells, containing fragmented and then polymeric DNA, may contribute to tumor stem cell self-renewal.
Area of Science:
- Oncology
- Cell Biology
- Genetics
Background:
- Sarcoma cell lines like HT-1080 are crucial models for cancer research.
- Understanding novel cell death and regeneration pathways is key to cancer therapy development.
Purpose of the Study:
- To investigate microcell formation in HT-1080 cells after thiophosphamidum treatment.
- To characterize the biological processes and molecular markers involved in microcell development.
- To propose a new term for this observed phenomenon.
Main Methods:
- Human sarcoma cell line (HT-1080) treatment with thiophosphamidum.
- Microscopy (light and electron) to observe cell morphology and dynamics.
- Incorporation assays using 5-bromo-2'-deoxyuridine (BrdU) to assess DNA synthesis.
- Immunofluorescence for argyrophilic nucleolar organiser region (AgNOR) proteins and lung resistance protein (LRP).
Main Results:
- Damaged macrocells formed microcells containing fragmented DNA, which later accumulated polymeric DNA and increased in size.
- Microcells incorporated BrdU and expressed AgNOR proteins and LRP, indicating active biological processes.
- Microcells were observed to enter mitosis after the disintegration of the parent macrocell.
- Electron microscopy suggested the involvement of coiled bodies in microcell formation.
Conclusions:
- A novel pathway of microcell formation, distinct from apoptosis, was identified and termed 'sporosis'.
- Sporosis involves the development of microcells from damaged macrocells, characterized by DNA changes and protein expression.
- This process may represent a mechanism for tumor stem cell self-renewal.