Hideya Ando

Linoleic acid and α-linolenic acid lightens ultraviolet-induced hyperpigmentation of the skin

Abstract This study was conducted to evaluate the effects of unsaturated fatty acids on ultraviolet-induced hyperpigmentation of the skin. An efficient lightening effect was observed following topical application of linoleic acid or α-linolenic acid to UV-stimulated hyperpigmented dorsal skin of brownish guinea pigs. The number of melanocytes in the treated skin was similar to the number in the skin of the pigmented control, indicating that the pigment-lightening effect was not due to depletion of melanocytes. In vitro experiments using cultured murine melanoma cells showed that melanin production was inhibited most effectively by α-linolenic acid, followed by linoleic acid and then by oleic acid. Furthermore, the turnover of the stratum corneum, which plays an important role in the removal of melanin pigment from the epidermis, was accelerated by linoleic acid and by α-linolenic acid. Taken together, the results suggest that the pigment-lightening effects of linoleic acid and α-linolenic acid are, at least in part, due to suppression of melanin production by active melanocytes, and to enhanced desquamation of melanin pigment from the epidermis.

Deletion of specific protein kinase C subspecies in human melanoma cells.

It has been shown that tumor‐promoting phorbol ester, 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA), stimulates the proliferation of normal human melanocytes, whereas it inhibits the growth of human melanoma cell lines. The expression of protein kinase C (PKC) subspecies, the major intracellular receptors for TPA, was examined in normal melanocytes and the four melanoma cell lines HM3KO, MeWo, HMV‐1, and G361. PKC was partially purified and then separated into subspecies by column chromatography on Mono Q and hydroxyapatite successively, and finally subjected to immunoblot analysis using antibodies specific for the PKC subspecies. Of the PKC subspecies examined, δ‐, ϵ‐, and ζ‐PKC were detected in both normal melanocytes and the four melanoma cell lines. In contrast, both α‐PKC and β‐PKC were expressed in normal melanocytes, whereas either α‐PKC or β‐PKC was detected in melanoma cells. Specifically, HM3KO, MeWo, and HMV‐1 cells were shown to contain α‐PKC but not β‐PKC, while G361 cells expressed β‐PKC but not α‐PKC. The growth of these melanoma cells was suppressed by TPA treatment, and the growth of the G361 cells lacking α‐PKC was inhibited more efficiently than the other melanoma cell lines which lacked β‐PKC. It was further shown that β‐PKC was not detected in freshly isolated human primary or metastatic melanoma tissues. These results suggest that the expression of α‐PKC or β‐PKC may be altered during the malignant transformation of normal melanocytes and that loss of α‐PKC or β‐PKC may be related to the inhibitory effect of TPA on the growth of melanoma cells.

Electron microscopic study of cultured cells from the murine hair tissues: cell growth and differentiation

SummaryThe cultured hair cells from 4-day-old C3H mice were studied by electron microscopy. The hair roots isolated from the skin by collagenase digestion were dispersed into a cell suspension by treatment with a mixture of trypsin and ethylenediaminetetraacetate. The cells were cultured in MCDB-153 (a medium containing seven growth factors) for 1, 3, 6 or 13 days. The number of cultured cells on day 3 was twice that on day 1, and stayed at the same level until day 13. By electron microscopy, some of the cells cultured for 1 day were seen to be undifferentiated and others already showed differentiation into various hair structures. Such differentiated cells disappeared on day 3 and most of the cells cultured for 3 days were undifferentiated. Cells cultured for 6 days were differentiated showing inner root sheath cell, hair cortical cell and medulla cell structures. The characteristics of these cultured cells corresponded well to those of in vivo cells of the hair tissues from the back skin of 7-day-old C3H mice. On day 13 degeneration occurred in the cultured cells. In none of these cultures were mesenchymal cells, such as fibroblasts, found. The present electron microscopic study reveals that immature cells obtained from mouse hair tissues proliferate in vitro and differentiate into several subpopulations corresponding to those of in vivo cell layers of hair tissues. The present culture technique may be useful for studies of hair cell growth and differentiation.