Role of interleukin-6 and endothelin-1 receptors in enhanced melanocyte dendricity of facial spots and suppression of their ligands by niacinamide and tranexamic acid

BACKGROUND

Hyperpigmented spots are common issues in all ethnicities with a hallmark characteristic of increased melanocyte dendricity.

OBJECTIVES

To determine (1) potential receptors and/or cytokines that are involved in increased melanocyte dendricity in multiple facial spot types; (2) treatment effects of skin-lightening compounds on identified cytokine release from keratinocytes and on dendricity in melanocytes.

METHODS

Facial spots (melasma, solar lentigo, acne-induced post-inflammatory hyperpigmentation) and adjacent non-spot skin biopsies were collected from Chinese women (age 20-70). The epidermal supra and basal layers were laser dissected to enrich keratinocyte or melanocyte biology respectively for transcriptome analysis. Melanocyte dendricity was assessed histologically by immunofluorescent staining. Effect of interleukin-6 (IL-6) and endothelin-1 (ET-1) on melanocyte dendricity and melanosome transfer were assessed in human melanocytes or melanocyte-keratinocyte co-culture models. Treatment effects of skin-lightening compounds (niacinamide, tranexamic acid [TxA], sucrose laurate/dilaurate mixture [SDL]) were assessed on IL-6 or ET-1 release from keratinocytes and on dendricity in melanocytes.

RESULTS

Transcriptome analysis revealed IL-6 receptor and ET-1 receptor were significantly upregulated compared to the adjacent normal skin, visually confirmed at the protein level through immunostaining. Melanocytes in spot areas are more dendritic than melanocytes in adjacent non-spot skin. The addition of IL-6 and ET-1 to cell culture models increased melanocyte dendricity and melanosome transfer. IL-6 release was significantly suppressed by niacinamide and its combination, while ET-1 release was significantly reduced by both niacinamide and TxA. In contrast, SDL acted directly upon melanocytes to reduce dendricity.

CONCLUSION

Interleukin-6 and ET-1 receptors are significantly upregulated in multiple facial spot types. The in vitro testing demonstrated their respective ligands increased melanocyte dendricity. Tested skin-lightening compounds showed reduction in release of IL-6/ET-1 from epidermal keratinocytes and/or inhibition of melanocyte dendricity. This work sheds light on pathophysiological mechanism of facial spots and potential new mechanisms of these skin-lightening compounds which warrant further human clinical validation.

A case of nivolumab-induced acute-onset type 1 diabetes mellitus in melanoma

Nivolumab, an anti-PD-1 antibody, is now considered an important therapeutic agent in several advanced malignancies. However, immune-related adverse events such as endocrinopathies have been reported with its use. Thyroid disorder and isolated adrenocorticotropic hormone deficiency have frequently been reported as nivolumab-induced immune-related adverse events. Another endocrinopathy is nivolumab-induced type 1 diabetes mellitus (t1dm), described as diabetes mellitus with rapid onset and complete insulin insufficiency, at times leading to fulminant t1dm. We report the case of a 68-year-old woman who developed pancreatic islet-related autoantibody-negative t1dm, possibly induced by nivolumab, under continuous glucocorticoid administration. She was treated with nivolumab for advanced malignant melanoma, concomitant with 10 mg prednisolone daily for thrombophlebitis tapered to 5 mg after 13 courses of nivolumab therapy. At approximately the 27th course of nivolumab therapy, she showed elevated plasma glucose levels despite preserved insulin secretion. A month later, she developed diabetic ketoacidosis. Her insulin secretion decreased and finally was exhausted. She was diagnosed with acute-onset rather than fulminant t1dm because of a rapidly progressive course to diabetic ketoacidosis during just more than 1 week. She is currently receiving insulin replacement. There has been no recurrence of the melanoma. Thus, nivolumab might induce autoimmune diabetes mellitus, with patients having t1dm-sensitive human leucocyte antigen being more susceptible even when receiving glucocorticoids. Physicians should be aware that nivolumab could potentially induce t1dm as a critical immune-related adverse event.

The IL-13/periostin/IL-24 pathway causes epidermal barrier dysfunction in allergic skin inflammation

BACKGROUND

Barrier dysfunction is an important feature of atopic dermatitis (AD) in which IL-4 and IL-13, signature type 2 cytokines, are involved. Periostin, a matricellular protein induced by IL-4 or IL-13, plays a crucial role in the onset of allergic skin inflammation, including barrier dysfunction. However, it remains elusive how periostin causes barrier dysfunction downstream of the IL-13 signal.

METHODS

We systematically identified periostin-dependent expression profile using DNA microarrays. We then investigated whether IL-24 downregulates filaggrin expression downstream of the IL-13 signals and whether IL-13-induced IL-24 expression and IL-24-induced downregulation of filaggrin expression are dependent on the JAK/STAT pathway. To build on the significance of in vitro findings, we investigated expression of IL-24 and activation of STAT3 in mite-treated mice and in AD patients.

RESULTS

We identified IL-24 as an IL-13-induced molecule in a periostin-dependent manner. Keratinocytes are the main IL-24-producing tissue-resident cells stimulated by IL-13 in a periostin-dependent manner via STAT6. IL-24 significantly downregulated filaggrin expression via STAT3, contributing to barrier dysfunction downstream of the IL-13/periostin pathway. Wild-type mite-treated mice showed significantly enhanced expression of IL-24 and activation of STAT3 in the epidermis, which disappeared in both STAT6-deficient and periostin-deficient mice, suggesting that these events are downstream of both STAT6 and periostin. Moreover, IL-24 expression was enhanced in the epidermis of skin tissues taken from AD patients.

CONCLUSIONS

The IL-13/periostin pathway induces IL-24 production in keratinocytes, playing an important role in barrier dysfunction in AD.

The pruritogenic mediator endothelin-1 shifts the dendritic cell-T-cell response toward Th17/Th1 polarization

Endothelin-1 (ET-1) is associated with skin diseases such as atopic dermatitis (AD) and psoriasis. ET-1 is enhanced in the skin of patients AD and psoriasis. In addition, plasma levels of ET-1 are elevated in AD and psoriasis. Although both AD and psoriasis are T-cell-mediated skin diseases, the association between ET-1 and the T-cell immune response has not been clarified. To evaluate the role of ET-1 in inflammatory skin disease, we sought to investigate the effects of ET-1 on the functions of dendritic cells (DCs) and subsequent immune responses. For this purpose, we immunohistochemically confirmed the upregulation of ET-1 in the epidermis of patients with AD or psoriasis. ET-1 directly induced phenotypic maturation of bone marrow-derived DCs (BMDCs). In addition, ET-1 augmented the production of several cytokines and allogeneic stimulatory capacity of BMDCs. Interestingly, ET-1-activated BMDCs primed T cells to produce Th1 and Th17 cytokines, but not Th2 cytokines. These findings indicate that ET-1 polarizes the DC-T-cell response toward Th17/1 differentiation and may augment the persistent course of inflammatory skin diseases.

Emerging role of interleukin-31 and interleukin-31 receptor in pruritus in atopic dermatitis

Atopic dermatitis (AD) is a chronic or chronically relapsing, eczematous, severely pruritic skin disorder associated with skin barrier dysfunction. The lesional skin of AD exhibits T helper 2 (T_H 2)-deviated immune reactions. Interleukin-31 (IL-31), preferentially produced from T_H 2 cells, is a potent pruritogenic cytokine, and its systemic and local administration induces scratching behavior in rodents, dogs and monkeys. Recent clinical trials have revealed that administration of an anti-IL-31 receptor antibody significantly alleviates pruritus in patients with AD. In this review, we summarize recent topics related to IL-31 and its receptor with special references to atopic itch.

The first trial of CIM331, a humanized antihuman interleukin-31 receptor A antibody, in healthy volunteers and patients with atopic dermatitis to evaluate safety, tolerability and pharmacokinetics of a single dose in a randomized, double-blind, placebo-controlled study

BACKGROUND

The cytokine interleukin-31 (IL-31) is considered to be responsible for the development of pruritus in humans. At present, no available evidence has been provided on the safety and efficacy of blocking the IL-31 signal in humans for the amelioration of pruritus in atopic dermatitis (AD). CIM331 is a humanized antihuman IL-31 receptor A (IL-31RA) monoclonal antibody, which binds to IL-31RA to inhibit subsequent IL-31 signalling.

OBJECTIVES

To assess the tolerability, safety, pharmacokinetics and preliminary efficacy of CIM331 in healthy Japanese and white volunteers, and Japanese patients with AD.

METHODS

In this randomized, double-blind, placebo-controlled phase I/Ib study, CIM331 was administered in a single subcutaneous dose. The primary outcomes were safety and tolerability; the exploratory analysis was efficacy.

RESULTS

No deaths, serious adverse events (AEs) or discontinuations due to AEs were reported in any part of the study. No dose-dependent increase in the incidence of AEs occurred in any part of the study. In healthy volunteers, all AEs occurred once in the placebo groups, and increased creatine phosphokinase was more common in the CIM331 groups. In patients with AD, CIM331 reduced pruritus visual analogue scale score to about -50% at week 4 with CIM331 compared with -20% with placebo. CIM331 increased sleep efficiency and decreased the use of hydrocortisone butyrate.

CONCLUSIONS

A single subcutaneous administration of CIM331 was well tolerated in healthy volunteers and patients with AD. It decreased pruritus, sleep disturbance and topical use of hydrocortisone. CIM331 may become a novel therapeutic option for AD by inhibiting IL-31.

Mutual upregulation of endothelin-1 and IL-25 in atopic dermatitis

BACKGROUND

Endothelin-1 (ET-1) has been reported to evoke histamine-independent pruritus in mammals. However, its association with pruritus or inflammation of atopic dermatitis (AD) has not been clarified. We sought to investigate the role of ET-1 in the skin inflammation of AD.

METHODS

To examine the role of ET-1 in AD, we investigated the expression of ET-1 and IL-25 in the skin of an AD mouse model and patients with AD and examined the mutual regulatory relationship between ET-1 and IL-25, one of the important cytokines in AD, using the human HaCaT keratinocyte cell line.

RESULTS

We immunohistochemically confirmed the upregulation of ET-1 and IL-25 expression in the epidermis of both the AD mouse model and patients with AD. In vitro, IL-25 upregulated ET-1 mRNA and protein expression in a concentration- and time-dependent fashion in HaCaT cells. This IL-25-induced ET-1 expression was inhibited by ERK1/2 or JNK inhibitor. In a reciprocal manner, ET-1 also induced IL-25 upregulation. The enhancing effect of ET-1 on IL-25 was inhibited by an endothelin A receptor antagonist, ERK1/2 inhibitor, or p38 inhibitor, but not by an endothelin B receptor antagonist or JNK inhibitor.

CONCLUSION

These findings suggest that mutual upregulation of ET-1 and IL-25 takes place in the epidermis of AD, which may be a future target for antipruritic agents.

Hashimoto's disease is a frequent comorbidity and an exacerbating factor of chronic spontaneous urticaria

BACKGROUND

The precise pathogenesis of chronic spontaneous urticaria (CSU) remains unknown. However, an important association between CSU and autoimmune disorders such as Hashimoto's disease (HD) has been reported. We investigated the frequency of HD as a comorbidity of CSU and the prevalence rate of autoreactivity among CSU patients with HD.

PATIENTS AND METHODS

The presence of thyroid autoantibodies and the levels of thyroid hormones were examined in 40 CSU patients who showed urticaria symptoms for >4 weeks. Patients who were diagnosed with HD, including subclinical ones, and were in need of treatment received thyroid therapy, and the changes in their urticarial symptoms were observed. An autologous serum skin test (ASST) was also performed to examine the relation of CSU with autoreactivity.

RESULTS

Eleven of the 40 CSU patients were diagnosed with HD, and 4 of the 5 patients who received and completed thyroid therapy showed considerable remission of urticarial symptoms during and after treatment. In addition, the rate of positive ASST results tended to be higher in CSU patients with HD (5 of 7) than in those without HD (2 of 6).

CONCLUSIONS

The comorbidity rate of HD in CSU patients was high, and such patients tended to have a positive ASST. Thyroid therapy in CSU patients with HD can lead to a considerable remission of urticarial symptoms, which may suggest that HD is possibly involved in the aetiology of CSU, or is at least a potential exacerbating factor for CSU.

Analysis of sebum lipid composition and the development of acneiform rash before and after administration of egfr inhibitor

Treatment with an epidermal growth factor receptor inhibitor (egfri) in patients having non-small-cell lung cancer can cause frequent and diverse skin toxicities, an acneiform rash being one of the commonest. Although the exact pathophysiology of this rash and its development mechanisms remain unknown, investigators have noted that egfri-induced skin toxicity might be partly associated with sebaceous gland function. Sebum is composed mainly of the lipids squalene (sq), wax ester (we), triglyceride, free fatty acid, and cholesterol, which are secreted mostly from the sebaceous glands and by keratinocytes. We therefore investigated the lipid composition of sebum before and after administration of egfri and whether sebum composition was associated with the development of acneiform rash. To investigate any associated changes in sebum gland activity, we focused especially on alterations in the amounts of sq and we, which are secreted solely from the sebaceous glands. In contrast to our expectations, we observed no substantial changes in the lipid composition of sebum before and after administration of egfri. Composition varies with the individual; however, the proportion of sq and we derived from the sebaceous glands was significantly lower in regions that did not develop acneiform rash than in regions that did. Our results suggest that development of an acneiform rash after administration of egfri could be related to sebaceous gland activity. Measurement of the lipid composition of sebum before therapy with egfri might predict which patients will be prone to acneiform rash.

Narrow-margin excision is a safe, reliable treatment for well-defined, primary pigmented basal cell carcinoma: an analysis of 288 lesions in Japan

BACKGROUND

Complete excision is the most promising treatment for basal cell carcinoma (BCC) and a surgical margin of at least 4 mm is recommended. However, little is known about the appropriate surgical margin of pigmented BCC.

OBJECTIVE

To investigate the reliability of narrower margin excision of well-defined, pigmented BCC.

METHODS

We identified a total of 263 patients with 288 well-defined, primary pigmented BCC at the Department of Dermatology, Kyushu University (Fukuoka, Japan), between January 2006 and December 2013. All lesions were surgically excised with 1-6-mm margins and analysed. For 30 recent lesions out of the 288 lesions, border gaps between dermoscopy and histopathology were assessed.

RESULTS

Of the 288 lesions, 218 (75.7%) were excised with a narrow margin (≤ 3 mm) and 60 lesions (24.3%) with a wide margin (≥ 4 mm). Only two lesions (0.7%), which were excised with 2-mm margins, were associated with tumour-positive margins. Narrow-margin excision showed a complete removal rate of 99% (2-mm margins, 95.3%; 3-mm margins, 100%). Dermoscopically determined borders almost exactly corresponded to the histopathological ones; 71.2% of border gaps between dermoscopy and histopathology were within 1 mm and there were no cases in which tumours spread beyond 1 mm of their dermoscopic borders.

CONCLUSION

Surgical excision with a 2-3-mm margin is reliable treatment for well-defined, primary pigmented BCC, with a complete removal rate of 99%.

Inhibition of AHR transcription by NF1C is affected by a single-nucleotide polymorphism, and is involved in suppression of human uterine endometrial cancer

Involvement of the aryl hydrocarbon receptor (AHR) in carcinogenesis has been suggested in many studies. Upregulation of AHR has been reported in some cancer species, and an association between single-nucleotide polymorphisms (SNPs) of AHR and cancer risk or cancer development has also been reported. This evidence suggests the involvement of some specific SNPs in AHR transcriptional regulation in the process of carcinogenesis or cancer development, but there have been no studies to elucidate the mechanism involved. In this study, we identified the transcription factor Nuclear Factor 1-C (NF1C) as a candidate to regulate AHR transcription in a polymorphism-dependent manner. SNP rs10249788 was included in a consensus binding site for NF1C. Our results suggested that NF1C preferred the C allele to the T allele at rs10249788 for binding. Forced expression of NF1C suppressed the activity of the AHR promoter with C at rs10249788 stronger than that with T. Moreover, expression analysis of human uterine endometrial cancer (HEC) specimens showed greater upregulation of AHR and downregulation of NF1C than those of normal endometrium specimens. Sequence analysis showed HEC patients at advanced stages tended to possess T/T alleles more frequently than healthy women. We also demonstrated that NF1C suppressed proliferation, motility and invasion of HEC cells. This function was at least partially mediated by AHR. This study is the first to report that a polymorphism on the AHR regulatory region affected transcriptional regulation of the AHR gene in vitro. Because NF1C is a tumor suppressor, our new insights into AHR deregulation and its polymorphisms could reveal novel mechanisms of genetic susceptibility to cancer.

Topical application of PPARα (but not β/δ or γ) suppresses atopic dermatitis in NC/Nga mice

BACKGROUND

Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors, which regulate not only adipogenesis and proliferation/differentiation but also the immune response of cells. Because topical application of the activators of some PPAR isoforms improved clinical symptoms in patients with atopic dermatitis (AD), we investigated the role of PPAR activators using a murine AD model in NC/Nga mice; to the best of our knowledge, this has not been previously reported.

METHODS

Activators of three PPAR isoforms (α, β/δ, γ) were topically applied on inflamed skin in a murine AD model that was developed by repeated topical application of mite antigen in NC/Nga mice. The efficacy of each topical PPAR activator was evaluated immunologically and serologically.

RESULTS

Topical application of the PPARα activator, but not of the activators of PPARβ/δ or PPARγ, improved clinical dermatitis, reduced inflammatory cell infiltration in the dermis, and alleviated the elevation of serum IgE levels. In addition, PPARα expression was downregulated in the epidermis in our murine AD model, as is seen in patients with AD.

CONCLUSIONS

Topical application of PPARα activator could be a potent therapeutic agent for patients with AD and could take the place of topical steroid treatments.

A Case of Sparganosis mansoni in the Thigh: Serological Validation of Cure Following Surgery

Cases of Sparganum mansoni, caused by the plerocercoid larva of the tapeworm S. mansoni, occur throughout the world, particularly in Asian, Middle Eastern, and European countries. However, cases of infection with this parasite are rarely seen in Japan. Here, we present a case of a 61-year-old woman with a solitary subcutaneous nodule in left inner aspect of the thigh, from which a long, slender, whitish worm was surgically removed. The parasite was histopathologically identified as S. mansoni. Serological testing confirmed cure of the infection after surgical removal of the parasite. The authors advocate immunoserological examination in case of S. mansoni.

Expression of milk fat globule epidermal growth factor-VIII may be an indicator of poor prognosis in malignant melanoma

BACKGROUND

Milk fat globule epidermal growth factor-VIII (MFG-E8) is a secreted protein that binds phosphatidylserine and promotes apoptotic cell ingestion by phagocytes, mediating the immune tolerance and maintenance of homeostasis. A recent study has shown that MFG-E8 expression in human melanoma is increased with tumour progression; however, the effect of its expression on patient survival has not yet been clarified.

OBJECTIVE

To analyse MFG-E8 expression in melanoma, and to determine whether it can serve as a marker for diagnosis, tumour progression and/or prognosis.

METHODS

MFG-E8 expression was examined by immunohistochemistry in 60 primary melanomas, 22 metastatic lesions and 30 benign naevi. The following clinicopathological variables were evaluated: age, gender, histological type, tumour site, Breslow thickness, Clark's level, the presence or absence of ulceration and tumour-infiltrating lymphocytes, and survival periods. Statistical analyses were performed to assess associations and melanoma-specific survival.

RESULTS

MFG-E8 expression was significantly higher in primary and metastatic melanoma than in naevus. Furthermore, it increased according to tumour progression and metastasis. Patients with MFG-E8 expression in primary tumours had significantly shorter survival periods than those without MFG-E8 expression. Univariate and multivariate analyses revealed that MFG-E8 expression was a statistically significant and independent prognostic factor.

CONCLUSION

MFG-E8 expression may serve as a tumour progression marker and can predict an unfavourable prognosis in patients with melanoma.

Stromal expression of cathepsin K in squamous cell carcinoma

BACKGROUND

Cathepsin K (CTSK), a cysteine protease with strong collagenolytic and elastolytic properties involved in extracellular matrix turnover, may be produced by neoplastic cells as well as stromal macrophages and fibroblasts. Its expression is suggested as associated with increased invasive and metastatic potential.

OBJECTIVES

The aim of this study is to examine stromal expression of cathepsin K in skin tumors.

METHODS

A series of 13 normal skin and 109 skin tumours, including 51 benign and 58 malignant epidermal tumours were tested for CTSK and Ki-67 expression by immunohistochemical analysis.

RESULTS

Stromal CTSK expression and the tumoral Ki-67 labelling index were significantly higher in invasive squamous cell carcinoma (SCC) than in other epidermal tumours.

CONCLUSION

Cathepsin K-positive stromal fibroblasts may play a crucial role in SCC progression by promoting extracellular matrix degradation, thereby facilitating SCC growth and invasion into surrounding tissue and vasculature. CTSK inhibitors may be a potential novel therapeutic option to decrease SCC progression.

T cell-specific overexpression of interleukin-27 receptor α subunit (WSX-1) prevents spontaneous skin inflammation in MRL/lpr mice

BACKGROUND

Interleukin (IL)-27 and WSX-1, the receptor α-specific subunit, have been shown to play important roles in initiating Th1 responses and in inducing immune modulation, and the immunosuppressive effect of IL-27 appears to be exerted via suppression of IL-10 and IL-17, which may participate in the pathogenesis of human systemic lupus erythematosus (SLE).

OBJECTIVES

To examine the significance of IL-27/WSX-1 signalling in spontaneous skin inflammation of MRL/lpr mice, a model for SLE.

METHODS

The severity and development of skin lesions, dermal inflammatory cells and epidermal-dermal depositions in the skin lesions of MRL/lpr mice with CD2-promoted WSX-1 overexpression (WSX-1 Tg mice) and those with globally disrupted WSX-1 (WSX-1 KO mice) were examined and compared with those of MRL/lpr mice.

RESULTS

By 4 months of age, both WSX-1 KO mice and control MRL/lpr mice developed predominantly similar skin inflammation, while WSX-1 Tg mice hardly did so, demonstrating that intensifying IL-27/WSX-1 signalling on T cells prevents the spontaneous skin inflammation. WSX-1 KO mice showed Th2-type skin inflammation as evidenced by the Th2-prone dermal infiltrating cells and an absence of cutaneous Th1-type IgG deposition. Interestingly, there were significant IL-17+ dermal infiltrating cells in both WSX-1 KO and control MRL/lpr mice, which might potentially contribute to the formation of skin inflammation in these mice.

CONCLUSIONS

These data indicate that IL-27/WSX-1 signalling may play a protective role in the development of SLE-like skin inflammation, and modulating IL-27/WSX-1 signalling might be an interesting therapeutic strategy in the treatment of SLE.

Use of a simple arm-raising test with a portable laser Doppler blood flow meter to detect dehydration

Using micro electromechanical systems (MEMS) technologies, the authors have developed the world’s smallest, lightest, and least power-consuming laser Doppler blood flow meter. Unlike commercial fibre-type blood flow instruments, the new blood flow meter is invulnerable to any movements of the person wearing it and has a wireless transmitter. Utilizing the characteristics of the blood flow meter, the authors attempted to detect dehydration by having a subject simply raise an arm (arm-raising test) with the flow meter attached to a fingertip. Healthy young volunteers (20 men and two women, mean age 22.9, age range 21–27 years) were instructed to perspire in a sauna until they became dehydrated. The target dewatering ratio was 2 per cent, which was calculated from the body weight measured using a weight scale. Four markers were compared: mean blood flow (MBF) before arm-raising, MBF during arm-raising, maximum amplitude (MA) of the pulse wave during arm-raising, and inclination of reflex (IR) wave calculated from the recorded blood flow data for the non-dehydrated (before sauna) and dehydrated (3 h after sauna) states in the arm-raising test. Each of the mean total markers (MBF during arm-raising, MA, and IR) was significantly lower ( P < 0.05) during the dehydrated state than the non-dehydrated. These results suggest that three markers could detect dehydration and the blood flow meter devised has the potential to be used as a portable device for detecting dehydration.

Activation of the mammalian target of rapamycin signalling pathway in epidermal tumours and its correlation with cyclin-dependent kinase 2

BACKGROUND

The enzyme mammalian target of rapamycin (mTOR) integrates many different cellular signals to control cell growth and proliferation, protein synthesis and breakdown, and other processes. Dysregulation of mTOR is implicated in a range of human diseases, including cancers and cardiovascular disorders. To date, there has been no report on the expression of protein kinase B (AKT)/mTOR cell signalling in epidermal tumours.

OBJECTIVES

This study was designed to investigate the activation of the mTOR signalling pathway in epidermal tumours and to correlate this with cyclin-dependent kinase 2 (CDK2) expression.

METHODS

Immunohistological staining was performed with phosphorylated (p-) AKT, p-mTOR, p-4E-binding protein 1 (p-4EBP1), p-ribosomal protein S6 (p-S6), p-p70 ribosomal protein S6 kinase 1 (p-p70S6K1) and CDK2 in 15 cases each of seborrhoeic keratosis, actinic keratosis, keratoacanthoma and Bowen's disease (BD), and 25 cases of squamous cell carcinoma (SCC). Fifteen normal skin (NS) samples served as control.

RESULTS

Among 85 tumours, 40 (47%) were positive for p-AKT, 31 (36%) for p-mTOR, 44 (52%) for p-4EBP1, 38 (45%) for p-S6, and 39 (46%) for p-p70S6K1. CDK2 immunostaining was positive in all cases of SCC and BD, and in 67% of benign tumours. All of these markers were stained much more frequently in malignant tumours than in benign tumours or NS. p-AKT, p-mTOR, p-4EBP1, p-p70S6K1 and p-S6 each showed high correlation with CDK2.

CONCLUSIONS

Constitutive activation of the AKT/mTOR pathway was frequent in epidermal tumours, especially in malignant tumours. Activation was highly correlated with CDK2 expression, suggesting that the AKT/mTOR pathway may induce the malignant transition through CDK2 in epidermal tumours.

Increased expression of an epidermal stem cell marker, cytokeratin 19, in cutaneous squamous cell carcinoma

BACKGROUND

Cytokeratin 19 (CK19) has been considered to be a putative marker for epidermal stem cells in the hair follicle bulge. Cumulative reports have shown that epidermal stem cells play an important role in skin carcinogenesis. However, to date there has been no report on the clinical alteration of the stem cells in squamous cell carcinoma (SCC).

OBJECTIVES

To investigate alteration of the stem cells and proliferating cells and to assess their relationship and potential contribution to SCC.

METHODS

Thirty paraffin-embedded neoplastic skin lesions, consisting of 10 cases each of actinic keratosis (AK), Bowen disease (BD) and SCC, were examined immunohistologically for CK19 and Ki-67.

RESULTS

Positive reactivity for CK19 was seen in 30% of AK, 50% of BD and 80% of SCC lesions. There was significantly higher expression levels of CK19 in SCC than in AK and BD (P < 0.05). In addition, BD lesions harboured a significantly higher number of CK19-positive cells than did AK lesions (P < 0.05). There were significant differences in Ki-67 labelling indices between AK and BD and between AK and SCC (P < 0.001), but not between BD and SCC (P > 0.05). Furthermore, a serial section comparison study showed that there was a minor population of cells co-expressing CK19 and Ki-67 in a subset of the tumour cells of SCC samples. The percentage of CK19+ cells significantly correlated with that of Ki67+ cells in all examined neoplastic skin lesions.

CONCLUSIONS

These results suggest that CK19 expression may be associated with the retention of stem cell characteristics or a state that is uncommitted to terminal squamous differentiation.

Differential expression of two new members of the p53 family, p63 and p73, in extramammary Paget's disease

BACKGROUND

The proteins p53, p63 and p73 are known to be overexpressed and to play important roles in the pathogenesis of many tumours, but the expression of p63 and p73 has not previously been investigated in extramammary Paget's disease (EMPD).

AIM

To investigate the potential contribution of p53, p63 and p73 in the pathogenesis of EMPD.

METHODS

In total, 35 paraffin wax-embedded tissue samples from patients with EMPD were examined using immunohistochemical staining for p53, p63 and p73.

RESULTS

All of the 35 EMPD specimens, including all 6 invasive EMPD and 2 metastatic lymph-node specimens, showed nuclear overexpression of both p53 and p73. The expression levels (percentage of positive cells) of p53 and p73 (90.66 +/- 12.53% and 80.20 +/- 13.07%) in EMPD were significantly higher than those of normal skin. There was a significant correlation between the expression levels of p53 and p73 in EMPD. In 29 of 35 EMPD specimens, there was no nuclear expression of p63, and weak or moderate staining was found in only 6 specimens. The expression level of p63 in EMPD was significantly less than that in normal skin.

CONCLUSIONS

Our study shows that the concordant overexpression of p53 and p73 and the decreased expression of p63 may play a pivotal role in the pathogenesis of EMPD. The decreased expression of p63 may play a more important role in the pathogenesis of EMPD than the overexpression of p53 and p73.