Kazutoshi Murao

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.

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.

Epithelial stem cell mutations that promote squamous cell carcinoma metastasis.

Squamous cell carcinomas (SCCs) originate in stratified epithelia, with a small subset becoming metastatic. Epithelial stem cells are targets for driver mutations that give rise to SCCs, but it is unknown whether they contribute to oncogenic multipotency and metastasis. We developed a mouse model of SCC by targeting two frequent genetic mutations in human SCCs, oncogene Kras(G12D) activation and Smad4 deletion, to mouse keratin 15-expressing (K15+) stem cells. We show that transgenic mice developed multilineage tumors, including metastatic SCCs. Among cancer stem cell-enriched (CSC-enriched) populations, those with increased side population (SP) cells correlated with epithelial-mesenchymal transition (EMT) and lung metastasis. We show that microRNA-9 (miR-9) contributed to SP expansion and metastasis, and miR-9 inhibition reduced the number of SP cells and metastasis. Increased miR-9 was detected in metastatic human primary SCCs and SCC metastases, and miR-9-transduced human SCC cells exhibited increased invasion. We identified α-catenin as a predominant miR-9 target. Increased miR-9 in human SCC metastases correlated with α-catenin loss but not E-cadherin loss. Our results demonstrate that stem cells with Kras(G12D) activation and Smad4 depletion can produce tumors that are multipotent and susceptible to EMT and metastasis. Additionally, tumor initiation and metastatic properties of CSCs can be uncoupled, with miR-9 regulating the expansion of metastatic CSCs.

p53 prevents progression of nevi to melanoma predominantly through cell cycle regulation

p53 is the central member of a critical tumor suppressor pathway in virtually all tumor types, where it is silenced mainly by missense mutations. In melanoma, p53 predominantly remains wild type, thus its role has been neglected. To study the effect of p53 on melanocyte function and melanomagenesis, we crossed the ‘high‐p53’Mdm4+/− mouse to the well‐established TP‐ras0/+ murine melanoma progression model. After treatment with the carcinogen dimethylbenzanthracene (DMBA), TP‐ras0/+ mice on the Mdm4+/− background developed fewer tumors with a delay in the age of onset of melanomas compared to TP‐ras0/+ mice. Furthermore, we observed a dramatic decrease in tumor growth, lack of metastasis with increased survival of TP‐ras0/+: Mdm4+/− mice. Thus, p53 effectively prevented the conversion of small benign tumors to malignant and metastatic melanoma. p53 activation in cultured primary melanocyte and melanoma cell lines using Nutlin‐3, a specific Mdm2 antagonist, supported these findings. Moreover, global gene expression and network analysis of Nutlin‐3‐treated primary human melanocytes indicated that cell cycle regulation through the p21WAF1/CIP1 signaling network may be the key anti‐melanomagenic activity of p53.

Bowen's disease on the sole: p16INK4a overexpression associated with human papillomavirus type 16

We report a case of Bowens disease on the sole presenting clinically as an exophytic, blackish‐grey, verrucous tumour, and showing human papillomavirus (HPV) type 16 on analysis with polymerase chain reaction. Positive stains for HPV particles by immunohistochemical analysis were limited to several cell nuclei at the upper stratum Malpighii. However, all the tumour cells in the epidermis exhibited strong and diffuse nuclear and cytoplasmic stains for the tumour suppressor protein p16INK4a. We speculate that dysregulation of the retinoblastoma/p16INK4a pathway may be involved in the pathogenesis of the lesion, and p16INK4a overexpression might serve as a useful surrogate marker for identifying Bowens disease harbouring high‐risk types of HPV infection.

Human papillomavirus infection in Bowen disease: Negative p53 expression, not p16(INK4a) overexpression, is correlated with human papillomavirus-associated Bowen disease

Genital Bowen disease (BD) has been linked to the high‐risk types of human papillomavirus (HPV) infection. Recently, it has been recognized that HPV also can be associated with extragenital BD. HPV oncoproteins E6 and E7 interfere with the function of p53 and pRb, respectively, leading carcinogenesis. p16INK4a overexpression induced by inactivation of pRb is recognized as a surrogate marker for HPV‐associated cervical cancer. In this study, we examined the presence of HPV DNA in 142 BD lesions by polymerase chain reaction (PCR), and determined the type of HPV by PCR restriction fragment length polymorphism or direct DNA sequencing. HPV DNA was detected in 66.7% of genital BD and 8.3% of extragenital BD. The types of HPV detected were HPV types 6, 16, 33, 52, 56, 58 and 59. We also investigated the expression of p16INK4a, pRb and p53 by immunohistochemistry. Positive expression was detected in 88.6% for p16INK4a, 25.2% for pRb, and 63.8% for p53. There was no significant difference in p16INK4a and pRb expression between HPV‐positive and ‐negative BD. However, a strong correlation of HPV positivity with p53 negativity was found. A total of 66.7% of HPV‐positive BD showed no p53 expression, whereas the corresponding rate was 32.8% of HPV‐negative BD. This study demonstrated that HPV can participate in the development of BD, not only in the genital lesion, but also in extragenital lesion. p16INK4a overexpression is not a marker for HPV infection in BD. Instead, negative p53 expression is correlated with HPV‐associated BD.

Increased lysophospholipase D activity of autotaxin in sera of patients with atopic dermatitis

Atopic dermatitis (AD) is a chronically relapsing skin disorder ith pruritic and eczematous skin lesions. Various studies indicate (Fig. 1B and E) and 33-fold (Fig. 1E) in the assay mixture containing 18:2-LPC, followed by incubation for 24 h. As shown in Fig. 1E and F, the ratio of the increment of lysoPLD activity in the 33-fold diluted serum to that in 6.7-fold diluted serum in high-lysoPLD AD patients was significantly higher than that of low-lysoPLD AD patients, psoriasis patients, or healthy controls, indicating the existence of an inhibitory factor at a low concentration in the serum of high-lysoPLD AD patients.

Primary cutaneous mucormycosis caused by Mucor irregularis in an immunocompetent patient

Dear Editor, Mucormycosis, which mainly affects immunocompromised patients, is a rare, life-threatening infection caused by the order Mucorales. Among the six clinical types of mucormycosis, cutaneous mucormycosis is the rarest and is further categorized into two types: (i) the gangrenous type, which only occurs in immunocompromised patients and progresses rapidly, and (ii) the superficial type, which develops in immunocompetent individuals, manifests as erythematous plaques, and progresses slowly. We present a case of superficial cutaneous mucormycosis caused by Mucor irregularis (M. irregularis) involving an immunocompetent patient. A 16-year-oldJapanese boy who was otherwise healthy presented with a 1-year history of a gradually enlarging plaque on his leg. A physical examination demonstrated an erythematous plaque exhibiting slight desquamation on his lower right leg, which he had scraped in a bicycle accident 2 years before (Fig. 1a). A histopathological examination detected a suppurative granuloma containing neutrophils, lymphocytes, and multinucleated giant cells in the dermis (Fig. 1b). Broad, ribbon-like, hyaline, aseptate hyphae were also observed (Fig. 1c). However, fungal hyphae and microvascular thrombosis were not detected in his blood vessels. Skin tissue specimens and skin scales cultured on Sabouraud dextrose agar at 25°C yielded wool-like, light yellow colonies, but no colony growth occurred at 38°C (Fig. 1d). Microscopic examinations of slide cultures detected sporangiophores, which had formed a terminal, globose sporangium. No apophyses were observed (Fig. 1e). These findings were consistent with Mucor fungi, and the isolate was identified as Mucor irregularis based on sequencing of the D1/D2 domain of the large subunit rRNA gene (GenBank accession no. IFM 57177). Before obtaining a diagnosis, we tried itraconazole (100 mg/ day), fluconazole (200 mg/day), and voriconazole (300 mg/day), independently, as empirical therapies, but none of them was effective. However, when we administered high-dose itraconazole (400 mg/day), the patient’s plaque gradually regressed. Itraconazole was administered for a total of 9 weeks (Fig. 1f). No recurrence has been observed for 5 years. M. irregularis was originally known as Rhizomucor variabilis, but it was renamed M. irregularis based on its DNA sequence. Cases of mucormycosis due to M. irregularis are rare, and only 14 cases have been reported in the English-language literature. However, it is worth noting that mucormycosis due to M. irregularis presents with unique clinical features. In contrast to classical mucormycosis, most M. irregularis infections affect immunocompetent patients and do not exhibit angioinvasion, especially in the early stages. Moreover, the majority of M. irregularis infections manifest as the superficial cutaneous type, progress chronically, and persist for several years on exposed sites. It is unknown why M. irregularis infections display these unique features. However, the lower thermotolerance of M. irregularis could be responsible for its lack of angioinvasion. Amphotericin B is the first-line treatment for M. irregularis infections (as well as for other types of mucormycosis), and

Bowen disease of the palm associated with human papillomavirus 52.

Human papillomavirus (HPV) is a well‐known risk factor for many human cancers, especially cervical cancers. Among the nonmelanoma skin cancers, Bowen disease (BD) of the genitalia and fingers has also been shown to be closely associated with the high‐risk types of HPV, especially HPV16. We report a case of BD of the palm, which is a very rare location for BD. In addition to its rare location, HPV52, which is classified as a mucous high‐risk HPV type, was detected in the lesion by PCR restriction fragment length polymorphism analysis. To our knowledge, this is the first reported case of BD associated with HPV52.

Verrucous skin lesions on the feet in diabetic neuropathy successfully treated with topical maxacalcitol

ejd.2012.1640 Auteur(s) : Kazutoshi Murao kmurao@clin.med.tokushima-u.ac.jp, Mika Oshima, Osamu Miyajima, Yoshiaki Kubo Department of Dermatology, Institute of Health Biosciences, University of Tokushima Graduate School, 3-15-18 Kuramoto-cho, Tokushima 770-8503, Japan Verrucous skin lesions on the feet in diabetic neuropathy (VSLDN) was first described by Gerbig and Hunziker in 1995 [1]. Chronic pressure or friction in an area of sensory loss is considered an important factor for development of [...]