N-WASP Attenuates Cell Proliferation and Migration through ERK2-Dependent Enhanced Expression of TXNIP.

Neural Wiskott-Aldrich Syndrome Protein (N-WASP) regulates actin cytoskeleton remodeling. It has been known that reduced N-WASP expression in breast and colorectal cancers is associated with poor prognosis. Here, we found reduced N-WASP expression in squamous cell carcinoma (SCC) patient samples. The SCC cell line HSC-5 with reduced N-WASP expression was used to generate HSC-5CN (control) and HSC-5NW (N-WASP overexpression) cells. HSC-5NW cells had reduced cell proliferation and migration compared to HSC-5CN cells. HSC-5NW cells had increased phospho-ERK2 (extracellular signal-regulated kinase 2), phosphorylated Forkhead box protein class O1 (FOXO1) and reduced nuclear FOXO1 staining compared to HSC-5CN cells. Proteasome inhibition stabilized total FOXO1, however, not nuclear staining, suggesting that FOXO1 could be degraded in the cytoplasm. Inhibition of ERK2 enhanced nuclear FOXO1 levels and restored cell proliferation and migration of HSC-5NW to those of HSC-5CN cells, suggesting that ERK2 regulates FOXO1 activity. The expression of thioredoxin-interacting protein (TXNIP), a FOXO1 target that inhibits thioredoxin and glucose uptake, was higher in HSC-5NW cells than in HSC-5CN cells. Knockdown of TXNIP in HSC-5NW cells restored cell proliferation and migration to those of HSC-5CN cells. Thus, we propose that N-WASP regulates cell proliferation and migration via an N-WASP-ERK2-FOXO1-TXNIP pathway.

Melanoma in Singapore: A 20-year review of disease and treatment outcomes.

INTRODUCTION: Melanomas in Asians have different clinicopathological characteristics and prognosis from melanomas in Caucasians. This study reviewed the epidemiology and treatment outcomes of cutaneous melanoma diagnosed at a tertiary referral dermatology centre in Singapore, which has a multiracial population. The study also determined whether Asians had comparable relapse-free and overall survival periods to Caucasians in Singapore. METHOD: This is a retrospective review of cutaneous melanoma cases in our centre between 1996 and 2015. RESULTS: Sixty-two cases of melanoma were diagnosed in 61 patients: 72.6% occurred in Chinese, 19.4% in Caucasians and 3.2% in Indians, with an over-representation of Caucasians. Superficial spreading melanoma, acral lentiginous melanoma and nodular melanoma comprised 37.1%, 35.5% and 22.6% of the cases, respectively. The median time interval to diagnosis was longer in Asians than Caucasians; median Breslow's thickness in Asians were significantly thicker than in Caucasians (2.6mm versus 0.9mm, P=0.018) and Asians tend to present at a later stage. The mortality rates for Asians and Caucasians were 52% and 0%, respectively. CONCLUSION: More physician and patient education on skin cancer awareness is needed in our Asian-predominant population for better outcomes.

Overexpression of CDC42SE1 in A431 Cells Reduced Cell Proliferation by Inhibiting the Akt Pathway.

Cell division cycle 42 (CDC42), a small Rho GTPase, plays a critical role in many cellular processes, including cell proliferation and survival. CDC42 interacts with the CRIB (Cdc42- and Rac-interactive binding) domain of CDC42SE1, a small effector protein of 9 kDa. We found that the expression of CDC42SE1 was reduced in human skin cancer samples relative to matched perilesional control. Exogenous expression of CDC42SE1 but not CDC42SE1H38A (mutation within CRIB domain) in A431 cells (A431SE1, A431SE1-H38A) reduced cell proliferation. Antibody microarray analysis of A431Ctrl and A431SE1 lysate suggested that reduced A431SE1 cells proliferation was due to inhibition of Akt pathway, which was confirmed by the reduced P-Akt and P-mTOR levels in A431SE1 cells compared to A431Ctrl cells. This suggests that CDC42SE1 modulates the CDC42-mediated Akt pathway by competing with other effector proteins to bind CDC42. A431SE1 cells formed smaller colonies in soft agar compared to A431Ctrl and A431SE1-H38A cells. These findings correlate with nude mice xenograft assays, where A431SE1 cells formed tumors with significantly-reduced volume compared to the tumors formed by A431Ctrl cells. Our results suggest that CDC42SE1 is downregulated in skin cancer to promote tumorigenesis, and thus CDC42SE1 might be an important marker of skin cancer progression.

Hydroa vacciniforme-like lymphoproliferative disorder in an elderly Chinese patient and a literature review of adult cases.

Hydroa vaccinforme-like lymphoproliferative disorder (HVLPD) is a rare T-cell lymphoproliferative disorder driven by the Epstein-Barr Virus (EBV). It was initially designated under the 2008 WHO classification of tumors of hematopoietic and lymphoid tissues as a distinct entity but has been recently reclassified as a lymphoproliferative disorder under the 2016 revision of the 2008 WHO classification of lymphoid malignancies. HVLPD mainly affects Asian, Central, and South American children. It is rarely seen in adults. Although HVLPD may initially be limited to cutaneous involvement and run an indolent course, some patients may develop a rapidly aggressive course. We report a case of an elderly Chinese man with cutaneous-limited disease and a favorable course. A review of adult cases of HVLPD published in the English literature, with comparison to our case, is also presented in this paper.

Indeterminate cell histiocytosis in a Chinese patient with progressive and extensive nodular lesions and mixed indeterminate cell and macrophage-monocyte lineage.

Indeterminate cell histiocytosis (ICH) is an extremely rare cutaneous neoplastic disorder. It has the immunophenotypic features of both Langerhans and non-Langerhans cell histiocytosis. We report here a case of a healthy young Chinese woman who presented with disfiguring, thick, infiltrated cutaneous nodules on the face, trunk and extremities which appeared progressively over a period of 4 years. No systemic involvement has been detected so far. Results of a skin biopsy showed diffuse dermal infiltration of histiocytoid cells with indented nuclei and positive staining for S100 and CD1a and negativity for CD207 (langerin). Admixed within were some CD68-positive foamy histiocytes and multinucleated giant cells with focal expression of CD163. Although the clinical presentation is more typical of progressive nodular histiocytosis, the histology and immunoprofile is consistent with ICH. Our report adds to the limited case reports in the current literature of ICH in the Chinese population.

Cutaneous Plasmacytosis: A Clinicopathologic Study of a Series of Cases and Their Treatment Outcomes.

INTRODUCTION: Cutaneous plasmacytosis (CP) is a rare skin disorder characterized by multiple reddish brown nodules with polyclonal plasma cell proliferation. It has most often been reported to affect the trunk but is also known to affect the face and extremities in adults and is predominantly seen in Asians. The etiology is poorly understood, and there is no consensus on treatment methods. METHODS: Five cases diagnosed to have CP were collated from our institution. Their clinicopathologic features and treatment outcomes were reviewed. RESULTS: Four of the 5 patients presented with lesions that affected multiple sites of the body including the trunk, axillae, face, and limbs. The remaining patient had lesions localized to his axillae. The lesions were generally asymptomatic. All patients had hypergammaglobulinaemia but only one had a faint monoclonal band detected on immunofixation. Common findings in the biopsy results for all patients were perivascular plasma cell infiltrates without light chain restriction on kappa/lambda staining, as well as mast cell infiltrates. Partial remission of cutaneous lesions was observed in 3 of the patients, with 2 of them responding well to psoralen and ultraviolet A radiation therapy. CONCLUSION: CP presents with distinctive clinical features and characteristic histological features including polyclonal perivascular plasma cell infiltrates. The axilla seems to be a frequent and characteristic site of involvement and may be a useful clinical clue to the condition. In the management of patients with CP, it is important to exclude secondary causes of plasmacytic infiltrates. While there are no clearly established treatment modalities for CP, psoralen and ultraviolet A radiation therapy may be a viable option in view of the clinical improvement observed in our patients who received it.

Simultaneous Occurrence of Papulonecrotic Tuberculid and Erythema Induratum in an Asian Woman.

A 31-year-old Indonesian woman presented with a 2-month history of recurrent painful nodules on the legs. Review of systems did not reveal any respiratory, gastrointestinal, or abdominal findings. She had been to Singapore working as a domestic helper for close to a year. There was no contact history of tuberculosis.

Anti-BP180 NC16A IgG Titres as an Indicator of Disease Activity and Outcome in Asian Patients with Bullous Pemphigoid.

INTRODUCTION: Anti-BP180 IgG titres were observed to parallel disease activity in case series of bullous pemphigoid (BP). This study aimed to examine whether anti-BP180 titres are an indicator of disease severity, clinical course and outcome in Asian patients with BP. MATERIALS AND METHODS: This was a prospective observational study conducted between March 2005 and March 2008 in the Immunodermatology Clinic at the National Skin Centre, Singapore. Disease activity and anti-BP180 IgG titres were measured 4-weekly for 12 weeks and during disease flares and clinical remission. Associations between anti-BP180 titres and disease activity, disease flare, clinical remission and cumulative prednisolone dose were examined. RESULTS: Thirty-four patients with newly diagnosed BP were recruited. Median follow-up duration was 3 years. Notable correlations between disease activity and anti-BP180 titres were at baseline (r = 0.51, P = 0.002), and disease flare (r = 0.85, P <0.001). Lower titres at Week 12 were associated with greater likelihood of clinical remission (P = 0.036). Post hoc, patients with anti-BP180 titres above 87.5 U/mL at time of diagnosis who reached remission within 2 years of diagnosis received significantly higher cumulative doses (mg/kg) of prednisolone (median, 72.8; range, 56.5 to 127.1) than those with titres <87.5 U/mL (median, 44.6; range, 32.5 to 80.8); P = 0.025). CONCLUSION: Anti-BP180 titres may be a useful indicator of disease activity at time of diagnosis and at disease flare. Lower titres at Week 12 may predict greater likelihood of clinical remission. Titres above 87.5 U/mL at time of diagnosis may suggest the need for higher cumulative doses of prednisolone to achieve remission within 2 years.

Basal cell carcinoma in Singapore: a prospective study on epidemiology and clinicopathological characteristics with a secondary comparative analysis between Singaporean Chinese and Caucasian patients.

BACKGROUND/OBJECTIVES: Susceptibility to and clinical presentation of basal cell carcinoma (BCC) differ in Asian and Caucasian populations. This study aims to evaluate the epidemiological and clinicopathological characteristics of BCC in a multiracial Singaporean population, with a secondary comparative analysis between Chinese and Caucasian patients. METHODS: We prospectively studied patients with newly diagnosed, histologically confirmed BCC at the National Skin Centre, Singapore from 2004 to 2008. RESULTS: In total, 274 BCC from 260 patients were studied, with 19 patients having two or more tumours. Their mean age was 67.5 years and 54% were male. Chinese comprised 80% and Caucasians 14%. The Chinese were 1.8-fold as likely as Caucasians to be older than 60 years, and experienced itch thrice more frequently. Caucasians developed multiple BCC threefold and truncal or upper limb BCC 2.9-fold more frequently than the Chinese. In terms of tumour subtype, morphoeic BCC was 2.7-fold more common in Caucasians. Pigmented BCC occurred 2.7-fold more often in the Chinese, most frequently on the head and neck of elderly Chinese. CONCLUSIONS: Compared to the Chinese, BCC occurred more often in younger Caucasians, with a predilection for the trunk and upper limb, suggesting a greater role for recreational sun exposure as a risk factor. Pigmented BCC more commonly occurred on the head and neck of elderly Chinese and may be reflective of cumulative sun exposure as a risk factor. Aggressive morphoeic BCC was more common in Caucasians than in Singaporean Chinese patients.

Eccrine syringofibroadenomatosis of the reactive subtype occurring in chronic poorly-controlled psoriasis.

Eccrine syringofibroadenomatosis (ESFA) is a rare adnexal tumor with acrosyringeal differentiation. Clinically, it can be mistaken for granulomatous infections or malignancies such as squamous cell carcinoma. Despite the rarity of the condition, we recently encountered two cases of the reactive subtype, which occurred in patients with poorly controlled chronic psoriasis. Both patients presented with long-standing, thick verrucous lesions on the lower legs. The diagnosis was made after histological examination and exclusion of infectious and neoplastic disorders. As this is a reactive disorder, management is focused on treating the underlying condition. Unfortunately, psoriasis was difficult to manage in both our patients and they defaulted further treatment. It is important to recognize ESFA as it can be confused with infectious or malignant disorders.

Pediatric mycosis fungoides in Singapore: a series of 46 children.

Few studies have evaluated Asian children with mycosis fungoides (MF). We report a series of patients from a tertiary dermatologic institution in Singapore. A retrospective review was performed of patients younger than 16 years old diagnosed with MF between 2000 and 2008 at the National Skin Centre, Singapore. Forty-six patients were identified. At initial presentation, a provisional diagnosis of MF was made in 19 patients (41.3%), pityriasis lichenoides chronica (PLC) in 11 (23.9%) and postinflammatory hypopigmentation due to eczema or other causes in 11 (23.9%). After skin biopsy, the hypopigmented variant of MF was diagnosed in 42 patients (91.3%). There was one case each of PLC-like MF, pigmented purpuric dermatosis-like MF, classic MF, and solitary MF. Pityriasis lichenoides coexisted in three cases (6.5%). All except one patient presented with the early patch-plaque stage of disease (stage IA/B). The disease did not progress in any of our patients after a mean follow-up of 71.0 ± 52.5 months. Twenty-seven patients (58.7%) had complete disease clearance after a mean duration of 27.1 ± 28.1 months; 15 (49.7%) of 32 patients who received narrowband ultraviolet B treatment had complete clearance within an average of 8.9 ± 5.3 months, but 7 patients relapsed within 14.9 ± 14.8 months. One patient with solitary MF failed multiple treatment modalities before eventually achieving disease clearance with photodynamic therapy. Hypopigmented MF is the most common MF variant in Asian children. The diagnostic difficulty is in differentiating this from PLC, which may coexist with MF. Long-term prognosis is generally favorable.

A retrospective review of the therapeutic response with remission in patients with newly diagnosed bullous pemphigoid.

We reviewed the clinical characteristics and therapeutic response in cases of newly diagnosed bullous pemphigoid at the National Skin Centre between June 2009 and December 2010. Most (76%, n = 68/90) achieved clinical remission within 6 months of commencement of therapy. Oral mucosal involvement was identified as a risk factor associated with a prolonged duration of treatment beyond 6 months.

Microscopy techniques in flavivirus research.

The Flavivirus genus is composed of many medically important viruses that cause high morbidity and mortality, which include Dengue and West Nile viruses. Various molecular and biochemical techniques have been developed in the endeavour to study flaviviruses. However, microscopy techniques still have irreplaceable roles in the identification of novel virus pathogens and characterization of morphological changes in virus-infected cells. Fluorescence microscopy contributes greatly in understanding the fundamental viral protein localizations and virus-host protein interactions during infection. Electron microscopy remains the gold standard for visualizing ultra-structural features of virus particles and infected cells. New imaging techniques and combinatory applications are continuously being developed to push the limit of resolution and extract more quantitative data. Currently, correlative live cell imaging and high resolution three-dimensional imaging have already been achieved through the tandem use of optical and electron microscopy in analyzing biological specimens. Microscopy techniques are also used to measure protein binding affinities and determine the mobility pattern of proteins in cells. This chapter will consolidate on the applications of various well-established microscopy techniques in flavivirus research, and discuss how recently developed microscopy techniques can potentially help advance our understanding in these membrane viruses.

Genome-wide association study of B cell non-Hodgkin lymphoma identifies 3q27 as a susceptibility locus in the Chinese population.

To identify genetic risk factors underlying non-Hodgkin lymphomas (NHLs) from the B cell lineage, we conducted a genome-wide association study (GWAS) of 253 Chinese individuals with B cell NHL (cases) and 1,438 controls and further validation in 1,175 cases and 5,492 controls. We identified a new susceptibility locus, rs6773854, located between BCL6 (encoding B cell lymphoma protein 6) and LPP (encoding lipoma preferred partner) on oncogene-rich chromosome 3q27 that was significantly associated with increased risk of B cell NHL (meta-analysis P = 3.36 × 10⁻¹³, per-allele odds ratio (OR) = 1.44) and with diffuse large B cell lymphoma (DLBCL) in particular (meta-analysis P = 1.14 × 10⁻¹¹, OR = 1.47). We found no evidence of association of rs6773854 with non-B cell NHLs (T cell and natural killer (NK) lineages) (P = 0.17, OR = 1.12) and observed significant heterogeneity between B cell and non-B cell subtypes (Phet = 0.01, I² = 84%). Our results provide insight that germline variation in the intergenic region between BCL6 and LPP has a role in risk of B cell lymphomagenesis.

Generation of patient-specific induced pluripotent stem cell-derived cardiomyocytes as a cellular model of arrhythmogenic right ventricular cardiomyopathy.

AIMS: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a primary heart muscle disorder associated with sudden cardiac death. Its pathophysiology is still poorly understood. We aimed to produce an in vitro cellular model of ARVC using patient-specific induced pluripotent stem cell (iPSC)-derived cardiomyocytes and determine whether the model could recapitulate key features of the disease phenotype. METHODS AND RESULTS: Dermal fibroblasts were obtained from a 30-year-old man with a clinical diagnosis of ARVC, harbouring a plakophilin 2 (PKP2) gene mutation. Four stable iPSC lines were generated using retroviral reprogramming, and functional cardiomyocytes were derived. Gene expression levels of desmosomal proteins (PKP2 and plakoglobin) in cardiomyocytes from ARVC-iPSCs were significantly lower compared with cardiomyocytes from control iPSCs (P< 0.01); there were no significant differences in the expression of desmoplakin, N-cadherin, and connexin 43 between the two groups. Cardiomyocytes derived from ARVC-iPSCs exhibited markedly reduced immunofluorescence signals when stained for PKP2 and plakoglobin, but similar levels of staining for desmoplakin, N-cadherin, and connexin 43 compared with control cardiomyocytes. Transmission electron microscopy showed that ARVC-iPSC cardiomyocytes were larger and contained darker lipid droplets compared with control cardiomyocytes. After 2 weeks of cell exposure to adiopgenic differentiation medium, ARVC-iPSC cardiomyocytes were found to contain a significantly greater amount of lipid, calculated using Oil Red O staining, compared with controls (734 ± 35.6 vs. 8.1 ± 0.49 a.u., respectively; n = 7, P = 0.001). CONCLUSION: Patient-specific iPSC-derived cardiomyocytes display key features of ARVC, including reduced cell surface localization of desmosomal proteins and a more adipogenic phenotype.

Extramammary Paget disease: Immunohistochemistry is critical to distinguish potential mimickers.

Extra-mammary Paget disease (EMPD) is a rare intra-epithelial carcinoma that is usually found on the apocrine-rich skin of the perineum. We report 2 cases in which EMPD was initially misdiagnosed on the initial punch biopsy as melanoma-in-situ and Bowen disease respectively. Reasons for the misdiagnoses included a rare pigmented axillary variant of EMPD in the first case and atypical bowenoid features on H&E in the second. The cases are described with a critical review of the histopathological findings, along with a review of the current literature. This highlights the necessity of a comprehensive immunohistochemical panel for the assessment of intra-epithelial pagetoid atypical cells.