[Antitumor effects of aromatic retinoids (Ro 10-1670, Ro 10-9359) on the chemically-induced epithelial tumors].

Pathological and histochemical studies were made to clarify the response to an aromatic retinoids (Ro 10-1670, Ro 10-9359) of the papilloma and carcinoma in hamster cheek pouch and mouse dorsal skin. The sizes of papilloma and carcinoma were remarkably reduced or completely regressed following systemic and topical administration of the aromatic retinoids. The antitumor effects increased in proportion to the frequency of administration than doses and were showed no side effects. Tumor tissues responded remarkably to the aromatic retinoids indicated an irregular keratinization including loss of hornified cells, nuclear vacuolization and inflammatory infiltrates which located in the border layer between stromas and neoplastic epithelia. Histochemically, tumor tissues which intensely affected by drugs were characterized by the presence of abundant acid phosphatase active cells. Those acid phosphatase active cells may be consisted of tumor cells, histiocytes and fibroblasts. In the electrocytochemical study acid phosphatase (a lysosomal marker enzyme) activity was found in epithelial tumor cells and fibroblasts. These results were indicated that epithelial tumor regression by aromatic retinoids the might be due to the accelerated lysosomal activity in the tumor cells and fibroblasts.