Mitochondrial inclusions in selenium-treated mouse mammary epithelial cell lines

Area of Science:

• Cell Biology
• Cancer Research
• Toxicology

Background:

• Mammary epithelial cells are crucial for understanding breast cancer development.
• Selenium's role in cell growth and cancer prevention is under investigation.
• Understanding cellular responses to selenium is key to its therapeutic potential.

Purpose of the Study:

• To investigate the ultrastructural effects of selenium on mammary epithelial cell lines.
• To assess the impact of selenium on cell growth inhibition and tumorigenicity.
• To correlate in vitro findings with in vivo tumor development.

Main Methods:

• Immunocytochemistry and transmission electron microscopy were used to examine cellular ultrastructure.
• In vitro growth assays and in vivo transplantation assays assessed tumorigenicity.
• Specific assays (cytochalasin B-induced multinucleation, multicellular spheroid formation) were employed.

Main Results:

• Selenium induced electron-dense mitochondrial inclusions in all three cell lines, most prominently in YN-4 cells.
• Selenium did not affect cytoplasmic microtubules or intermediate filament networks.
• YN-4 and WAZ-2t cells were tumorigenic in vivo, forming mammary adenocarcinomas.
• Multinucleation and multicellular spheroid formation correlated with tumorigenicity.

Conclusions:

• Selenium exposure leads to mitochondrial alterations in mammary epithelial cells.
• These changes may contribute to selenium-mediated growth inhibition.
• Specific in vitro assays can predict in vivo tumorigenicity of mammary cell lines.