Calcium regulation of growth and differentiation of mouse epidermal cells in culture

http://sun-lab.med.nyu.edu/files_private/sun-lab/attachments/1989.Cell.Cotsarelis-s.pdf

Existence of slow-cycling limbal epithelial basal cells that can be preferentially stimulated to proliferate: implications on epithelial stem cells.

Polyamines in rapid growth and cancer

Publisher Summary This chapter discusses the cellular biology and biochemistry of the retinoids In isolated 9-day-old rat embryos, retinoic acid prevents the formation of the pharyngeal arches, which are derived from cephalic mesenchyme; these structures later form the maxilla and the mandible Another mesenchymal derivative, whose formation is markedly suppressed by retinoic acid in rat embryos, is the yolk sac circulation Retinoids can exert a powerful influence on cell differentiation in many different types of epithelia The effects of retinoids on differentiation of epithelia in organ culture result from a combination of complex cellular responses and interactions of different cell types in the explant One of the most illuminating examples of the ability of retinoids to promote differentiation is the effect of retinoids on mouse embryonal carcinoma cells These undifferentiated stem cells of teratocarcinomas are multipotential, that is, they can differentiate into a multiplicity of somatic cell types Another example of the ability of retinoic acid to promote terminal differentiation of neoplastic cells to nonneoplastic cell types is the effect of retinoic acid on human promyelocytic leukemia cells

Cellular Biology and Biochemistry of the Retinoids

Multistage carcinogenesis in mouse skin

TUMOUR-PROMOTING agents have been defined by their ability to promote tumour formation on carcinogen-initiated mouse skin. The most potent of these agents are the diesters of phorbol which are the active components of croton oil, the classic promoting substance. Phorbol esters can be chemically modified in a number of positions to form molecules with a wide range of promoter potency1. Such modifications have been useful in determining structure-function relationships2. A good correlation exists between the ability of phorbol esters to promote epidermal tumours and their ability to stimulate epidermal macro-molecular synthesis in vivo3,4. In particular, all tumour promoters stimulate synthesis of epidermal DNA, although not all chemicals which induce hyperplasia are promoters1. Recently O'Brien et al.5 suggested that the degree of induction of ornithine decarboxylase (ODC) activity in mouse skin after application of promoting and non-promoting compounds correlates well with their promoting potency. Evidence from our laboratory indicates that brief exposure to the potent phorbol ester 12-O-tetradecanoyl-phorbol-13-acetate (TPA), stimulates DNA synthesis and ODC activity in mouse epidermal cell cultures (S.H.Y., T.B., E.P., D. Michael, K. Elgjo and H.H., to be published, and U.L. and S.H.Y., to be published). Using such a culture system, we have examined a series of phorbol esters to test the correlation of promoter potency in vivo with the stimulation of DNA synthesis and ODC activity in vitro.

Phorbol esters stimulate DNA synthesis and ornithine decarboxylase activity in mouse epidermal cell cultures

Mouse epidermal basal cells can be selectively cultivated in medium with 0.02 to 0.09 mm Ca 2+ and can be induced to differentiate by medium containing 1.2 mm Ca 2+ . Basal cell cultures were studied to determine if all cells in this population responded identically to the skin tumor promoter 12- O -tetradecanoylphorbol-13-acetate (TPA). Studies on the induction of the enzyme epidermal transglutaminase by TPA demonstrated a 2- to 4-fold increase in activity within 12 hr of exposure. This activity increase paralleled morphological differentiation in approximately 50% of the basal cell population, and differentiating cells sloughed from the culture dish within 24 to 48 hr as transglutaminase activity returned to basal levels. The cells which remained were resistant to induced differentiation by 1.2 mm Ca 2+ medium, in that they failed to demonstrate increased transglutaminase activity or decreased thymidine incorporation, both characteristics of control basal cells induced to differentiate by 1.2 mm Ca 2+ . Cells remaining after a single exposure to TPA did not respond to a second exposure with an induction of transglutaminase if the interval between exposures was 4 days. TPA-pretreated cells did not undergo a transient decrease in thymidine incorporation (characteristic of control cells) when exposed to TPA a second time but instead were directly stimulated to proliferate by the phorbol ester, indicating that such cells were not refractory to the promoter. When the treatment-free interval after TPA was extended from 4 to 10 days, transglutaminase inducibility was restored in basal cells to either TPA or 1.2 mm Ca 2+ as inducers. These results indicate that heterogeneity exists within the epidermal cell population and that exposure to phorbol esters induces differentiation in some cells, while stimulating proliferation in others. Such heterogeneous responses would cause a selective redistribution of the epidermal cell population and could lead to clonal expansion of initiated cells.

https://cancerres.aacrjournals.org/content/canres/42/6/2344.full.pdf

Divergent responses in epidermal basal cells exposed to the tumor promoter 12-O-tetradecanoylphorbol-13-acetate.

Phorbol ester tumor promoters induce epidermal transglutaminase activity

Exposure of mouse epidermal cells in culture to 12- O -tetradecanoyl-phorbol-13-acetate (TPA) results in an initial inhibition of DNA synthesis for 24 hr followed by a 5- to 10-fold stimulation at 72 to 96 hr. A corresponding increase in mitotic rate also occurs at 72 to 96 hr. These responses occur when TPA is continuously present in the medium or if the exposure is as short as 1 hr, but the degree of stimulation was dependent on dose and duration of exposure. Sensitivity to TPA varied with the length of time the cells were in culture prior to treatment. TPA treatment also produced an alteration in morphology from clearly epithelial to a more fibroblastic type. These biochemical and morphological effects did not occur after treatment of epidermal cells with either phorbol-13,20-diacetate or phorbol. Primary dermal fibroblasts in culture did not respond to TPA in this manner, but a line of cultured liver epithelial cells was slightly stimulated by the promoter. This sytem appears to be a sensitive in vitro model for detecting the hyperplasia-inducing effects of phorbol esters and should be useful for mechanistic studies and bioassay.

Stimulated DNA synthesis in mouse epidermal cell cultures treated with 12-O-tetradecanoyl-phorbol-13-acetate.

Dimethyl sulfoxide added to cultures first treated with 5-iododeoxyuridine increased C-type virus production approximately tenfold in a human rhabdomyosarcoma cell line 5-Iododeoxyuridine followed by dimethyl sulfoxide also activated a similar C-type virus in a metastatic tumor from a bronchial node taken from a 52-year-old male

http://science.sciencemag.org/content/sci/175/4018/198.full.pdf

Theresa Ben

Papers

Phorbol esters stimulate DNA synthesis and ornithine decarboxylase activity in mouse epidermal cell cultures

Divergent responses in epidermal basal cells exposed to the tumor promoter 12-O-tetradecanoylphorbol-13-acetate.

Phorbol ester tumor promoters induce epidermal transglutaminase activity

Stimulated DNA synthesis in mouse epidermal cell cultures treated with 12-O-tetradecanoyl-phorbol-13-acetate.

Activation of viruses in human tumors by 5-iododeoxyuridine and dimethyl sulfoxide.