The Biological Effects of Retinoids on Cell Differentiation and Proliferation

Abstract

The retinoids are the natural and synthetic analogues of retinol or vitamin A. These molecules are able to modulate differentiation and proliferation processes in several cell types. The presence of retinoids is essential for inducing or maintaining the differentiation of epithelial cells. On the other hand, when excess retinol is added to the culture medium, the differentiation of some mesenchymal cells is impaired. Retinoids also promote the differentiation of carcinoma cells of various origins: embryonal carcinoma, leukaemic and melanoma cells. While their effect on the proliferation of normal cells appears variable, these molecules inhibit the growth of cells treated with a tumoural promoter, or spontaneously transformed cells, and they prevent tumour promotion. Various mechanisms of action might be involved: retinoids could act at the level of the genome with or without the participation of their binding proteins. They might also influence glycoconjugate biosynthesis and interact, through certain glycosylation reactions, with growth factor receptors. The role of vitamin A and its structural analogues in cell differentiation and growth is of great therapeutic interest.After a brief reminder of the structure and metabolism The neoplastic process is characterized by an alter-of the retinoids we shall go on to discuss first the ation of the differentiated histological state of cells effect of these compounds on the differentiation of towards metaplastic and anaplastic forms and is as-various cell types (of epithelial, mesenchymal and sociated with cellular proliferation which escapes the cancerous origin). We shall then study the influence usual homeostatic control systems.of the retinoids on the proliferation

Tissue distribution of retinoids in common dolphins Delphinus delphis

“…Retinoids are a family of lipid-soluble substances that possess Vitamin A-like biological activity, including compounds such as retinol and retinol derivatives, retinal, retinyl palmitate and retinoic acid (Blomhoff et al 1992). In mammals, they can be provided only through diet (Blomhoff et al 1991) and are crucial for vision, growth, bone development, reproductive success, immune function, normal differentiation and proliferation of cells, and maintenance of the general health of the organism (Wolf 1984, Favennec & Cals 1988, Blomhoff 1994. Retinoid deficiency is associated with a diversity of anomalies, such as reproductive impairment, embryonic mortality, growth retardation, and decreased resistance to infections (Thompson 1976, Peakall 1992.…”

Periadventitial atRA citrate-based polyester membranes reduce neointimal hyperplasia and restenosis after carotid injury in rats

“…All-trans retinoic acid (atRA), a vitamin A derivative, acts on retinoic acid nuclear receptors regulating cellular proliferation and differentiation (9). It has been used clinically in patients to treat proliferative disorders, such as acute promyelocytic leukemia and other cancers (10,29).…”

“…atRA is a relatively unstable drug that can rapidly decompose into nonactive isomers when exposed to heat or light (9). When systemically delivered, atRA is bound by albumin and retinol-binding proteins in the serum and rapidly transferred to tissue stores found in the liver (3).…”

Topical Retinoids in Skin Ageing: A Focused Update with Reference to Sun-Induced Epidermal Vitamin A Deficiency

“…The presence of retinoids is essential for inducing or maintaining the differentiation of keratinocytes from the stratum basale to the stratum corneum, leading to the various layers of the epidermis [36,37,38]. Retinoids also play a crucial role in epidermal renewal, both during natural epidermal turnover and in case of epidermal injury.…”