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Inhibition of DNA synthesis and neoplastic cell growth by vitamin A (retinol)
Abstract:
The inhibitory effect of vitamin A alcohol (retinol) on the DNA synthesis and neoplastic cell growth of chemically induced carcinomas (squamous cell carcinomas in Swiss male albino mice and basal cell carcinomas in inbred SD rats) by 3-methylcholanthrene [(MCA) CAS: 56-49-5] was studied. A marked inhibition of squamous cell carcinomas and basal cell carcinomas was observed following a combined administration of MCA and vitamin A (retinol) compared to the finding for animals treated with MCA alone (P less than .001). DNA radioactivity and autoradiographic studies with the use of [3H]thymidine showed a marked inhibition of DNA synthesis (twofold to threefold) in the neoplastic cell nuclei following a concomitant administration of vitamin A (retinol) and MCA (12%) as compared to the DNA synthesis following administration of MCA alone (31%) (P less than .001). Electron microscopic and cytologic observations revealed an advanced cytolysis and disorganization of neoplastic cells with reduction of polysomes, tonofilaments, and lysosome populations and mitochondrial alterations following vitamin A and MCA administration as compared to characteristic squamous neoplastic cells and basal neoplastic cells following MCA treatment alone. In addition, scanning electron microscopy revealed advanced changes of cell surfaces with reduction of microvilli and disorganization of cytoarchitecture. The present findings demonstrate that vitamin A exerts its anticarcinogenic effect by inhibiting DNA synthesis, disrupting cell surfaces, and possibly interfering with MCA metabolism in epidermal cells.
Insights
Vitamin A (retinol) significantly inhibits chemical-induced cancer growth by reducing cancer cell DNA synthesis. This study shows vitamin A
Area of Science:
- Oncology
- Biochemistry
- Cell Biology
Background:
- Chemically induced carcinomas pose a significant health risk.
- Understanding the mechanisms of carcinogenesis is crucial for developing effective treatments.
Purpose of the Study:
- To investigate the inhibitory effect of vitamin A (retinol) on chemically induced carcinomas.
- To elucidate the impact of vitamin A on DNA synthesis and neoplastic cell growth.
Main Methods:
- Chemical induction of squamous cell carcinomas and basal cell carcinomas using 3-methylcholanthrene (MCA) in mice and rats.
- Administration of vitamin A (retinol) in combination with MCA.
- Assessment of DNA synthesis using [3H]thymidine incorporation and autoradiography.
- Evaluation of cellular changes using electron microscopy and scanning electron microscopy.
Main Results:
- Combined administration of MCA and vitamin A markedly inhibited tumor growth compared to MCA alone.
- Vitamin A significantly reduced DNA synthesis in neoplastic cells (twofold to threefold inhibition).
- Microscopic analysis revealed cytolysis, disorganization, and altered cell structures in vitamin A-treated groups.
Conclusions:
- Vitamin A (retinol) demonstrates potent anticarcinogenic effects against chemically induced carcinomas.
- The mechanism involves inhibition of DNA synthesis and disruption of neoplastic cell integrity.
- Vitamin A may interfere with carcinogen metabolism in epidermal cells.