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Epidemiological studies, mostly ecological but also case-control and prospective studies show a negative association between residential sun exposure and incidence (or fatality) of major cancers: colon, breast, and prostate cancer, and non-Hodgkin lymphoma. And it has been suggested that this reduction in risk could be influenced by vitamin D synthesized in the skin as a result of sun exposure. Low serum vitamin D levels are linked to an increase in risk of colon cancer, and to a lesser extent to risk of breast cancer, but not to risk of prostate cancer or non-Hodgkin lymphoma. Intervention trials consisting in daily supplementation in vitamin D for several years have all failed to demonstrate an effect on cancer incidence. Hence, it is not clear whether the reduction in cancer risk associated with sun exposure is mediated by vitamin D or by another factor influenced by sun exposure such as inflammation or immunosuppression, or whether a low vitamin D status is simply a consequence of ill health.

Mutated RAS oncoproteins and epidermal growth factor (EGF) are thought to contribute to the proliferative, invasive and metastatic properties of transformed cells. In the present study, we investigated the role of EGF in two H-ras transfected clones and compared it to that in the parental cell line, HaCaT and primary cultured keratinocytes. Our findings show that the motility on type I collagen, measured by the migration index, was similar for both the HaCaT cell line and normal human keratinocytes, whereas it was higher for the HaCaT-ras clones. These results suggest an involvement of the ras oncogene in the stimulation of cell migration. EGF in cell pretreatment or during the migration assay also caused an increase in migration of all the cells, but preserved the difference between HaCaT and HaCaT-ras. However, no significant difference in EGF-R expression was detected between normal cultured keratinocytes, HaCaT and HaCaT-ras cell lines with or without EGF pretreatment. Moreover, when the cells were stimulated with EGF, the MMP-9 activity was greatly increased in a dose-dependent manner in all the cells, and EGF stimulation particularly highlights the increased amount of MMP-9 in HaCaT-ras cells compared to HaCaT cells. In conclusion, EGF is able to enhance motility and to up-regulate MMP-9 activity in all cells, but with a higher impact in HaCaT-ras cells without an overexpression of EGF-R. As EGF acts in synergy with the H-ras mutation, they could be implicated in the local invasion by the HaCaT-ras clones. [ABSTRACT FROM AUTHOR]

We report an ultrastructural study of the reactivity of an IgG monoclonal antibody, which reacts with human dermal elastic fibres. On electron microscopy, immunogold labelling demonstrated the reactivity of HB8 with the mirofibrillar component of the fibres. in contrast, the electron- dense granular component which contains elastin was unlabelled with FIBS. A fine network of microfibrils from the level of the oxytalan fibres to the large elastic fibres of the deep dermis was labelled with gold particles. No reactivity was detected on collagen fibres. These results demonstrate that HB8 reacts with the microfibrillar glycoproteins of the elastic fibres in normal skin. The precise biochemical nature of the antigens identified by HB8 is still unknown. [ABSTRACT FROM AUTHOR]

Presents a letter to the editor about postembedding immunogold labeling of epidermis.