The cellular origin of chemically induced tumours

Area of Science:

• Developmental biology
• Cancer research
• Biochemistry

Background:

• Chimaeric mice were created from embryos producing different glucose phosphate isomerase (GPI) variants.
• Normal tissues in chimaeras typically contained both GPI isoenzymes.

Purpose of the Study:

• To investigate the cellular origin of chemically induced epidermal tumours in chimaeric mice.
• To determine if these tumours arise from a single cell (clonal growth).

Main Methods:

• Induction of tumours using chemical carcinogens in chimaeric mice.
• Analysis of glucose phosphate isomerase (GPI) isoenzyme profiles in normal tissues and tumours.
• Estimation of clonal size in chimaeric epidermis.

Main Results:

• Almost all induced tumours exhibited a single GPI isoenzyme, unlike normal tissues.
• Epidermal tumours were estimated to have originated from a maximum of 8 cells.
• This indicates a restricted cellular origin for the tumours.

Conclusions:

• Chemically induced epidermal tumours in these chimaeric mice are likely clonal growths.
• The findings support the hypothesis that cancer can arise from a single cell mutation.
• This study provides evidence for the clonal nature of chemically induced carcinogenesis.