Seiji Arase

Strong expression of a longevity-related protein, SIRT1, in Bowen’s disease

The class III histone deacetylase (HDAC), SIRT1, is a mammalian homologue of the Saccharomyces cerevisiae chromatin-silencing factor Sir2 that regulates longevity. SIRT1 regulates cell survival via deacetylation of p53 and forkhead transcription factors, and overexpression of SIRT1 is reported to be essential for cell growth and survival in some kinds of cancer. To elucidate the role of SIRT1 in human skin carcinogenesis, we have examined SIRT1 protein expression in 20 cases each of squamous cell carcinoma (SCC), basal cell carcinoma (BCC), Bowen’s disease (BD), and actinic keratosis (AK) by immunohistochemical analysis. Overexpression of SIRT1 is frequently observed in all kinds of non-melanoma skin cancers included in this study. In particular, strong expression was observed in all cases of BD. In addition, no obvious difference between AK and SCC was observed in the expression of SIRT1, suggesting that overexpression of SIRT1 may have some relevance to the early stage of skin carcinogenesis. We suppose that SIRT1 could be one of the critical targets for future therapy with the aim of inhibiting cell proliferation and promoting apoptosis in non-melanoma skin cancers.

Derivation and clinical application of special imaging by means of digital cameras and Image J freeware for quantification of erythema and pigmentation.

Background: Quantification of erythema and pigmentation is useful for analysis of skin tests and management of skin diseases. However, reflectance instruments for this purpose suffer from many technical and financial disadvantages. The aim of this study was to establish a method for evaluation of the amounts of haemoglobin and melanin using ordinary digital cameras and Image J freeware.

Sebaceous carcinoma: an immunohistochemical reappraisal.

The rates of distant metastases and tumor death in sebaceous carcinoma (SC) have been reported to be higher than those of other cutaneous carcinomas, such as squamous cell carcinoma (SCC) and basal cell carcinoma (BCC), regardless of whether they occur in ocular or extraocular regions. Therefore, strict differentiation of SC from SCC and BCC is required. In this article, we report immunohistochemical findings of SC and compare these data to those of SCC, BCC, and sebaceoma. An immunohistochemical study was performed using 7 antibodies [anti-carcinoembryonic antigen (CEA), anti-epithelial membrane antigen (EMA), anti-CA15-3, anti-CA19-9, anti-androgen receptor (AR), anti-epithelial antigen (Ber-EP4), and anti-adipophilin (ADP)] on 35 cases of SC (16 cases in ocular and 19 cases in extraocular regions) and 10 cases of each SCC (5 cases in ocular and 5 cases in extraocular regions), BCC (5 cases in ocular and 5 cases in extraocular regions), and sebaceoma (no cases arose on the eyelids). In summary, the typical immunophenotypes of SC were EMA+, CA15-3+, AR+, Ber-EP4−, and ADP+; those of sebaceoma were CEA−, EMA+, Ber-EP4−, and ADP+; those of SCC were CEA−, EMA+, CA19-9−, AR−, Ber-EP4−, and ADP−; and those of BCC were CEA−, EMA−, CA15-3−, Ber-EP4+, and ADP−. Other antibody tests for each neoplasm were positive in about half of the cases. The detection of AR and ADP was useful for differentiating SC from SCC, whereas the determination of EMA, CA15-3, Ber-EP4, and ADP was valuable in differentiating SC from BCC.

Epigenetic abnormalities in cutaneous squamous cell carcinomas: frequent inactivation of the RB1/p16 and p53 pathways

Background  Aberrant methylation of CpG islands in the promoter regions of cancer‐related genes has been demonstrated in many human tumours. However, the methylation profile of these regions in cutaneous squamous cell carcinomas (SCCs) has not been well studied.

Reduction of total E2F/DP activity induces senescence-like cell cycle arrest in cancer cells lacking functional pRB and p53.

E2F/DP complexes were originally identified as potent transcriptional activators required for cell proliferation. However, recent studies revised this notion by showing that inactivation of total E2F/DP activity by dominant-negative forms of E2F or DP does not prevent cellular proliferation, but rather abolishes tumor suppression pathways, such as cellular senescence. These observations suggest that blockage of total E2F/DP activity may increase the risk of cancer. Here, we provide evidence that depletion of DP by RNA interference, but not overexpression of dominant-negative form of E2F, efficiently reduces endogenous E2F/DP activity in human primary cells. Reduction of total E2F/DP activity results in a dramatic decrease in expression of many E2F target genes and causes a senescence-like cell cycle arrest. Importantly, similar results were observed in human cancer cells lacking functional p53 and pRB family proteins. These findings reveal that E2F/DP activity is indeed essential for cell proliferation and its reduction immediately provokes a senescence-like cell cycle arrest.

Effective inhibition of melanosome transfer to keratinocytes by lectins and niacinamide is reversible.

Abstract:  Skin pigmentation results in part from the transfer of melanized melanosomes synthesized by melanocytes to neighboring keratinocytes. Plasma membrane lectins and their glycoconjugates expressed by these epidermal cells are critical molecules involved in this transfer process. In addition, the derivative of vitamin B3, niacinamide, can inhibit melanosome transfer and induce skin lightening. We investigated the effects of these molecules on the viability of melanocytes and keratinocytes and on the reversibility of melanosome‐transfer inhibition induced by these agents using an in vitro melanocyte–keratinocyte coculture model system. While lectins and neoglycoproteins could induce apoptosis in a dose‐dependent manner to melanocytes or keratinocytes in monoculture, similar dosages of the lectins, as opposed to neoglycoproteins, did not induce apoptosis to either cell type when treated in coculture. The dosages of lectins and niacinamide not affecting cell viability produced an inhibitory effect on melanosome transfer, when used either alone or together in cocultures of melanocytes–keratinocytes. Cocultures treated with lectins or niacinamide resumed normal melanosome transfer in 3 days after removal of the inhibitor, while cocultures treated with a combination of lectins and niacinamide demonstrated a lag in this recovery. Subsequently, we assessed the effect of niacinamide on facial hyperpigmented spots using a vehicle‐controlled, split‐faced design human clinical trial. Topical application of niacinamide resulted in a dose‐dependent and reversible reduction in hyperpigmented lesions. These results suggest that lectins and niacinamide at concentrations that do not affect cell viability are reversible inhibitors of melanosome transfer.

Visualizing the dynamics of p21Waf1/Cip1 cyclin-dependent kinase inhibitor expression in living animals

Although the role of p21Waf1/Cip1 gene expression is well documented in various cell culture studies, its in vivo roles are poorly understood. To gain further insight into the role of p21Waf1/Cip1 gene expression in vivo, we attempted to visualize the dynamics of p21Waf1/Cip1 gene expression in living animals. In this study, we established a transgenic mice line (p21-p-luc) expressing the firefly luciferase under the control of the p21Waf1/Cip1 gene promoter. In conjunction with a noninvasive bioluminescent imaging technique, p21-p-luc mice enabled us to monitor the endogenous p21Waf1/Cip1 gene expression in vivo. By monitoring and quantifying the p21Waf1/Cip1 gene expression repeatedly in the same mouse throughout its entire lifespan, we were able to unveil the dynamics of p21Waf1/Cip1 gene expression in the aging process. We also applied this system to chemically induced skin carcinogenesis and found that the levels of p21Waf1/Cip1 gene expression rise dramatically in benign skin papillomas, suggesting that p21Waf1/Cip1 plays a preventative role(s) in skin tumor formation. Surprisingly, moreover, we found that the level of p21Waf1/Cip1 expression strikingly increased in the hair bulb and oscillated with a 3-week period correlating with hair follicle cycle progression. Notably, this was accompanied by the expression of p63 but not p53. This approach, together with the analysis of p21Waf1/Cip1 knockout mice, has uncovered a novel role for the p21Waf1/Cip1 gene in hair development. These data illustrate the unique utility of bioluminescence imaging in advancing our understanding of the timing and, hence, likely roles of specific gene expression in higher eukaryotes.

Graphic analysis of the relationship between skin colour change and variations in the amounts of melanin and haemoglobin

Background/aims The L*a*b* coordinate is the most commonly used colour system to measure skin colour in dermatology and cosmetology. In this system, a* and L* are often used for quantification of the degrees of erythema and pigmentation. The aim of this study was to examine whether a* and L* can be used as specific scales to indicate the amount of haemoglobin and melanin, respectively, in the skin.

The chemotactic effect of a dermal papilla cell-derived factor on outer root sheath cells

The effect of cultured normal human dermal papilla cells (DPCs) and conditioned medium prepared with cultured DPCs on chemotactic migration of human hair outer root sheath cells (ORSCs) was examined quantitatively. ORSCs showed significantly increased migration toward both cultured DPCs and the conditioned medium suggesting that DPCs produce and secrete a paracrine factor(s), which attracts hair follicle epithelial cells. Some soluble factors, which are reportedly produced by DPCs, such as insulin-like growth factor-I (IGF-I), hepatocyte growth factor (HGF), vascular endothelial cell growth factor (VEGF), and transforming growth factor-beta1 (TGF-beta1), were also examined. ORSCs showed dramatically increased migration toward IGF-I and HGF at concentrations of 1-10 ng/ml. On the other hand, neither VEGF nor TGF-beta1 showed any effect on the chemotaxis of ORSCs. It is interesting that all factors involving mitogenic activity did not always have chemotactic activity for ORSCs. This is the first report to establish that IGF-I and HGF have not only a growth stimulatory but also a chemotactic effect on ORSCs. In addition, the method presented here may help to simplify chemotaxis assays of any type of epithelial keratinocytes with poor mobility.

Quantification of erythema and pigmentation using a videomicroscope and a computer

We report a method for quantitative analysis of erythema and pigmentation using a videomicroscope interfaced with a computer. The analysis was carried out by examining the brightness intensity of every picture element, composed of an image picked up from each band of red, green, and blue, and by deriving the quasi‐absorbance value (absorbance index) from the mean brightness for each band. In assessments of UV‐induced erythema and tanning, excellent linear correlations were found between the results obtained with our system and those with a narrow‐band reflectance spectrometer. Moreover, the absorbance indices of haemoglobin and melanin solutions showed linear relationships with their concentrations in in vitro examination. As the monitored picture becomes out of focus if incorrect pressure is exerted on the skin, and as regions of interest can be chosen from a magnified image, this system offers excellent interobserver reproducibility, and is suitable for the evaluation of erythema or pigmented lesions which are too small or irregular to quantify by conventional methods such as colorimetry.