Conditional Knockout of N-WASP Enhanced the Formation of Keratinizing Squamous Cell Carcinoma Induced by KRasG12D

Squamous cell carcinoma (SCC) is one of the most common forms of skin cancer in humans, and Neural Wiskott-Aldrich Syndrome Protein (N-WASP) plays a crucial role in epidermal homeostasis. To elucidate the role of N-WASP in skin cancer, we generated mice which expressed constitutively active KRas (KRasG12D) in keratinocytes with either homozygous (N-WASPKOG12D) or heterozygous (N-WASPHetG12D) N-WASP knockout upon Tamoxifen (TAM) injection. Both the N-WASPKOG12D and N-WASPHetG12D mice had similar body weights and no congenital malformations prior to the injection of TAM. Within 2 weeks of the injections, the N-WASPKOG12D mice exhibited significant reductions in weight coupled with visible tumors at numerous sites, unlike the N-WASPHetG12D mice, which had no visible tumors. We found that both sets of mice had oily, sticky skin and wet eyes 3 weeks after their exposure to TAM, indicating the overproduction of sebum/meibum. At 37 days post TAM injection, several notable observations were made. Tumors collected from the N-WASPKOG12D mice had small- to large-sized keratin pearls that were not observed in the N-WASPHetG12D mice. A Western blot and immunostaining analysis both highlighted significantly higher levels of expression of SCC markers, such as the cytokeratins 8, 17, 18, and 19 and TP63, in the tumors of the N-WASPKOG12D mice compared to those of the latter group. Furthermore, we noted increases in the expression levels of EGFR, P-ERK, GLUT1, P-mTOR, and P-4EBP in the N-WASPKOG12D mice, suggesting that the deletion of N-WASP in the keratinocytes enhanced KRas signaling and glucose uptake, resulting in aggressive tumor formation. Interestingly, a thickening of the epidermal layer within the esophagus and tongue was only observed in the N-WASPKOG12D mice. Immunostaining for PCNA emphasized a significantly higher number of PCNA-positive cells in the skin of the N-WASPKOG12D mice compared to their counterparts, implying that epidermal thickening and enhanced tumorigenesis are due to an increased proliferation of keratinocytes. Through our results, we have established that N-WASP plays a tumor-suppressive role in skin cancer.

Lifting the lid over the pearl: A histological insight

Epithelial pearls and Keratin pearls are pathognomonic of squamous cell carcinoma. However, their histogenesis is not well understood. Only a handful of studies have been conducted in the past in this regard. This brief communication aims to understand the formation of these pearls with a few of our own experiences.

Successful treatment of cutaneous squamous cell carcinoma in a captive green iguana (Iguana iguana)

Reptiles are popular exotic pets and green iguanas (Iguana iguana) are amongst the top ten most popular reptiles. Here we describe a captive 8-year-old female green iguana that was referred for treatment of a non-healing, discharging lesion on the side of the body. The lesion was surgically excised and histopathological analysis revealed an epidermal proliferation of neoplastic keratinocytes, with focal infiltration through the basement membrane, into the underlying superficial dermis. Marked dysplastic changes, characterized by multifocal dyskeratosis and keratin pearl formation were also noted. A diagnosis of cutaneous squamous cell carcinoma (SCC) was made. Two years later, the iguana has shown no signs of recurrence. This is the first report of successful treatment of cutaneous SCC in a green iguana and contributes to the limited knowledge of cutaneous neoplasms in green iguanas.

Expression of Hsp90α and cyclin B1 were related to prognosis of esophageal squamous cell carcinoma and keratin pearl formation

Hsp90α (heat shock protein 90α), one of the important molecular chaperones in cancer cell signal transduction, has been a new candidate target for cancer therapy. Cyclin B1, the client protein of Hsp90α, plays a key role as a mitotic cyclin in the G2-M phase transition during the cell cycle progression. However, the relationship between the level of HSP90α and cyclin B1, the location of Hsp90α and cyclin B1 in prognosis of esophageal squamous cell carcinoma (ESCC) has not been examined. Here, we demonstrate that the diagnostic significance of Hsp90α and cyclin B1 by immunohistochemistry and the association of Hsp90α and cyclin B1 expression in ESCC. In the specimens from 105 ESCC patients (81 stained with Hsp90α antibody by Immunohistochemistry, 65 with cyclin B1 antibody, and among them, 41 paired specimens were stained with Hsp90α and cyclin B1 respectively, and then checked for the correlation of the level and location of Hsp90α and cylcin B1. The positivity rate of Hsp90α and cyclin B1 expression were 96.3% (78 of 81) and 84.6% (55 of 65) respectively. Both of them, the expression levels are associated with the clinical pathological stage (Hsp90α, p=0.027; cyclin B1, p=0.007). No association was found between Hsp90α or cyclin B1 and gender, age, tumor location. As to TMN stage, there is no association with the level of Hsp90α, However, cyclin B1 expression is significantly related to tumor status (p=0.002). Interestingly, Hsp90α expression was negatively correlated to cyclin B1 expression (Gamma=-0.692, p=0.007) in the keratin pearls though there is a positive correlation in the other areas of tumor (Gamma=0.503, p=0.015), which suggest Hsp90α might play diverse roles in the cyclin B1 expression and cyclin B1 related cell cycle regulation in the different area of tumor. These findings demonstrated that the expression of Hsp90α, cyclin B1 protein is associated with tumor malignancy and prognosis for patients with human esophageal squamous cell carcinoma, and Hsp90α might be involved in cyclin B1 expression regulation and cell cycle regulation in keratin peal formation of ESCC.