Effect of the Hewitt keratinizing epidermal carcinoma on cell proliferation in different organs of the host mouse and in human psoriatic skin cultured in diffusion chambers.

Abstract

Incorporation of 3H-thymidine into different squamous epithelia and other tissues was studied in mice bearing the Hewitt keratinizing epidermal carcinoma with a raised epidermal chalone content in the body. The results showed that DNA synthesis in the tumour-bearing mice was inhibited strongly in the epithelium of the ear (c.80%), moderately in the epithelium of the back skin and the foot (c.55%), and weakly in the epithelium of the tongue and the cornea (c.25%). These inhibitions appear to be specific in nature, because cell proliferation was not detectably affected in the sebaceous gland, intestinal epithelium, bone marrow, and thymus lymphocytes. Thymus size, however, was reduced in the tumour-bearing mice compared with controls, and 3H-thymidine uptake was depressed in the spleen and to some extent also in the lymph nodes, possibly owing to non-specific stress. Labelling index of human psoriatic epidermis was suppressed in diffusion-chamber cultures carried by the tumour-bearing host mice compared with controls. However, this reaction was probably not specific in nature, because the labelling index of mouse bone-marrow cells was also decreased when grown in tumour-bearing animals.