p63 in Squamous Cell Carcinoma of the Skin: More Than a Stem Cell/Progenitor Marker

The cutaneous beta human papillomavirus type 8 E6 protein induces CCL2 through the CEBPα/miR-203/p63 pathway to support an inflammatory microenvironment in epidermodysplasia verruciformis skin lesions

Human papillomavirus type 8 (HPV8), a cutaneous genus beta HPV type, has co-carcinogenic potential at sun-exposed sites in patients suffering from the inherited skin disease epidermodysplasia verruciformis (EV). We had previously shown that Langerhans cells responsible for epithelial immunosurveillance were strongly reduced at infected sites and that the HPV8 E7 protein interferes with the CCAAT/enhancer-binding protein (C/EBP)β to suppress the Langerhans cell chemokine CCL20. At the same time, however, we observed that EV lesions are heavily infiltrated with inflammatory immune cells, which is similar to the situation in HPV8 E6 transgenic mice. To identify critical inflammatory factors, we used a broad multiplex approach and found that the monocyte attracting chemokine CCL2 was significantly and strongly induced by HPV8 E6 but not E7-expressing HaCaT cells, which were used as a model for UV-damaged skin keratinocytes. Conditioned media from HPV8 E6-expressing keratinocytes enhanced CCL2-receptor (CCR2)-dependent monocyte recruitment in vitro, and macrophages predominated in the stroma but were also detected in the epidermal compartment of EV lesions in vivo. CCL2 induction by HPV8 E6 was even stronger than stimulation with the proinflammatory cytokine TNF-α, and both HPV8 E6 and TNF-α resulted in substantial suppression of the transcription factor C/EBPα. Using RNAi-mediated knockdown and overexpression approaches, we demonstrated a mechanistic role of the recently identified C/EBPα/miR-203/p63 pathway for HPV8 E6-mediated CCL2 induction at protein and transcriptional levels. Epithelial co-expression of p63 and CCL2 was confirmed in HPV8 E6-expressing organotypic air-liquid interface cultures and in lesional EV epidermis in vivo. In summary, our data demonstrate that HPV8 oncoproteins actively deregulate epidermal immune homeostasis through modulation of C/EBP factor-dependent pathways. While HPV8 E7 suppresses immunosurveillance required for viral persistence, the present study provides evidence that E6 involves the stemness-promoting factor p63 to support an inflammatory microenvironment that may fuel carcinogenesis in EV lesions.

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.

Association of human papillomavirus (HPV), p16, p53 and p63 expression with non-bilharzia-associated squamous cell carcinoma of the bladder and algorithm construction for histopathological grading prediction

OBJECTIVE

To investigate the expression of human papillomavirus (HPV), p16, p53, and p63 in non-schistosomiasis-related squamous cell carcinoma of the bladder and to develop an accurate and automated tool to predict histological classification based on clinicopathological features.

METHODS

Twenty-eight patients with primary bladder pure squamous cell carcinoma who underwent cystectomy or transurethral resection of bladder tumor (TURBT) for bladder cancer between January 2011 and July 2017 were evaluated. Clinical data and follow-up information were obtained from medical records. Formalin-fixed, paraffin-embedded surgical specimens were used for immunohistochemical staining for p16, p53, and p63. Human papillomavirus detection was evaluated by PCR. Statistical analysis was performed, and statistical significance was set at p<0.05. Finally, decision trees were built to classify patients' prognostic features. Leave-one-out cross-validation was used to test the generalizability of the model.

RESULTS

Neither direct HPV detection nor its indirect marker (p16 protein) was identified in most cases. The absence of p16 was correlated with less aggressive histological grading (p=0.040). The positive p16 staining detection found only in pT1 and pT2 cases in our sample suggests a possible role for this tumor suppressor protein in the initial stages of bladder squamous cell carcinoma. The decision trees constructed described the relationship between clinical features, such as hematuria/dysuria, the level of tumor invasion, HPV status, lymphovascular invasion, gender, age, compromised lymph nodes, and tumor degree differentiation, with high classification accuracy.

CONCLUSION

The algorithm classifier approach established decision pathways for semi-automatic tumor histological classification, laying the foundation for tailored semi-automated decision support systems for pathologists.

MicroRNA31 and MMP-1 contribute to the differentiated pathway of invasion -with enhanced epithelial-to-mesenchymal transition- in squamous cell carcinoma of the skin

Epithelial to mesenchymal transition (EMT) is an important mechanism of invasion in cutaneous squamous cell carcinomas (cSCCs) and has been found to be enhanced in tumors originated from actinic keratosis with transformation limited to the basal epithelial layer -differentiated pathway-, compared to cases with invasion subsequent to complete epidermal transformation -classical pathway-. Several microRNAs and proteins can contribute to EMT modulation in cSCCs. MicroRNA21 and microRNA31 are involved in posttranscriptional regulation of protein expression and could play a relevant role in EMT and cSCC progression. Throughout the EMT process upregulation of matrix metalloproteinases (MMPs) enhances invasiveness and MMP-1 and MMP-3 contribute to local invasion, angiogenesis and metastasis in cSCCs. Additionally, cSCC development is associated with PTEN loss and NF-κB, NOTCH-1 and p63 activation. The aim of this work is to identify differences in the expression of those molecules between both pathways of cSCCs development. Eight tissue microarrays from 80 consecutive cSCCs were analyzed using LNA-based miRNA in situ hybridization for miRNA21 and miRNA31 evaluation, and immunohistochemistry for MMP-1, MMP-3, PTEN, NOTCH-1, NF-κB, p63 and CD31. Significantly higher expression of miRNA31 (p < 0.0001) and MMP-1 (p = 0.0072) and angiogenesis (p = 0.0199) were found in the differentiated pathway, whereas PTEN loss (p = 0.0430) was more marked in the classical pathway. No significant differences were found for the other markers. Our findings support a contribution of miRNA31 and MMP-1 in the differentiated pathway, associated to EMT and increased microvascularization. The greater PTEN loss in the classical pathway indicate that its relevance in cSCC is not EMT-related.

Clinical and pathological risk factors for worse stage and mortality of eyelid and periocular squamous cell carcinoma

BACKGROUND

The clinical and pathological risk factors for worse T stage and prognosis in eyelid and periocular squamous cell carcinomas (SCCs) remain unclear. P63 was reported to predict a worse prognosis in other SCCs; however, this correlation was not validated in eyelid and periocular SCCs.

METHODS

We reported on a retrospective case series of 85 consecutive patients with eyelid and periocular SCCs from 1995 to 2019. Cox proportional hazards regression models and logistic regression models were applied for risk factor analysis.

RESULTS

Thirty-nine (45.8%) patients were diagnosed with T4 SCCs. Four (5.1%) patients developed nodal metastasis, and five (6.4%) patients developed distant metastasis during the follow-up. 2-year and 5-year disease-specific survival rates were 95.3% and 86.4%, respectively. Poorly or moderately differentiated eyelid and periocular SCCs were associated with worse T stage (p=0.001; p=0.008). Poor differentiation was associated with a higher risk of recurrence (p=0.024). Disease-specific death was more common in patients with T4 stage SCCs (p=0.038, HR=9.05). P63 expression was more common in patients with T3c or worse stage (p=0.008, OR=3.77). P63 expression alone was associated with worse differentiation (p=0.029), higher risk of perineural invasion (p=0.042, OR=4.61) and metastasis (p=0.009, HR=3.99). P63 expression (p=0.012, HR=7.80), coexpression of P63 and Ki67 (p=0.007, HR=9.21) and distant metastasis (p=0.001, HR=11.23) were associated with disease-specific death.

CONCLUSION

Patients presented with more aggressive orbital invasion features and a higher rate of distant metastasis in this cohort. P63 and coexpression of Ki67 predicted a worse stage, differentiation and prognosis, including metastasis and death due to disease.

Epithelial-to-mesenchymal transition in oral squamous cell carcinoma: Challenges and opportunities

Oral squamous cell carcinoma (OSCC) is the most common malignancy representing 90% of all forms of oral cancer worldwide. Although great efforts have been made in the past decades, the 5-year survival rate of OSCC patients is no more than 60% due to tumor metastasis and subsequent recurrence. The metastasis from the primary site is due to a complex process known as epithelial-to-mesenchymal transition (EMT). During the EMT, epithelial cells gradually acquire the structural and functional characteristics of mesenchymal cells, leading to the upregulation of cell migration and the promotion of tumor cell dissemination. Therefore, EMT attracted broad attention due to its close relationship with cancer invasion and metastasis. Therefore, in the present review, an extensive description of the current research on OSCC and the role of EMT in this cancer type is provided, including diverse EMT markers, regulatory networks and crucial EMT-inducing transcription factors in OSCC. Moreover, a brief summary was made regarding the current application of EMT-correlated indexes in the prognostic analysis of OSCC patients, and the potential therapeutic approaches against OSCC and difficulties in the development of an effective anti-EMT treatment are discussed. Our aim is to provide novel insights to develop new strategies to combat OSCC by targeting EMT.

Protective Effects of Dietary Grape on UVB-Mediated Cutaneous Damages and Skin Tumorigenesis in SKH-1 Mice

Non-melanoma skin cancers (NMSCs) are the most diagnosed cancers in the US and occur more frequently in males. We previously demonstrated chemoprotective effects of dietary grape powder (GP) against UVB-mediated skin tumorigenesis in female SKH-1 mice. To expand on this, here, we determined the effects of GP in a short-term UVB exposure protocol (0 or 5% GP, followed by UVB every other day for 2 weeks) in male and female SKH-1 mice, as well as explored any sex-related differences in UVB carcinogenesis via male SKH-1 mice (0, 3, or 5% GP; UVB twice weekly for 28 weeks). In the short-term study, we found that GP protects against early-stage epithelial hyperplasia and mast cell infiltration in both sexes. In the long term, GP markedly reduced tumor counts and malignant conversion, along with significant decreases in mast cell infiltration, serum IgE and Eotaxin. We also found inhibition of P38 phosphorylation and reduced PCNA, Ki67 and BCL2 levels, suggesting that the anti-inflammatory effects of GP inhibits P38, acting as an upstream regulator to inhibit proliferation and reduce tumor cell survival. Together, GP appears to protect against UVB-mediated skin damage and carcinogenesis in SKH-1 mice and should be explored further as a supplement for NMSC prevention.

A genomic survey of sarcomas on sun-exposed skin reveals distinctive candidate drivers and potentially targetable mutations

Sarcomas on photodamaged skin vary in prognosis and management, but can display overlapping microscopic and immunophenotypic features. Improved understanding of molecular alterations in these tumors may provide diagnostic and therapeutic insights. We characterized 111 cutaneous sarcomatoid malignancies and their counterparts, including primary cutaneous angiosarcoma (n = 7), atypical fibroxanthoma (AFX) (n = 21), pleomorphic dermal sarcoma (PDS) (n = 17), extracutaneous undifferentiated pleomorphic sarcoma (n = 8), cutaneous leiomyosarcoma (LMS) (n = 5), extracutaneous LMS (n = 9), sarcomatoid squamous cell carcinoma (spindle cell squamous cell carcinoma) (S-SCC) (n = 24), and conventional cutaneous squamous cell carcinoma (SCC) (n = 20), by next-generation sequencing (NGS) using the StrataNGS panel for copy number variations, mutations, and/or fusions in more than 60 cancer-related genes. TP53 mutations were highly recurrent in most groups. Angiosarcoma displayed previously reported MYC amplifications, as well as CCND1 gains. RB1 mutations were relatively restricted to cutaneous LMS. As previously reported, PIK3CA mutations occurred in AFX, whereas RAS activation was more frequent in PDS. CDKN2A mutations were recurrent in AFX and S-SCC, whereas PDS displayed frequent CDKN2A deletion. S-SCC displayed mutational similarity to conventional SCC. BRCA1/2 mutations were specific to tumors with disease progression. In a subset, we detected potential driver events novel to these tumor types: activating mutations in IDH2 (PDS), MAP2K1 (angiosarcoma, PDS), and JAK1 (S-SCC) and copy gains in FGFR1 (angiosarcoma, S-SCC), KIT (AFX), MET (PDS), and PDGFRA (PDS). Our findings confirm and expand the spectrum of known genomic aberrations, including potential targetable drivers, in cutaneous sarcomatoid malignancies. In addition, certain events are relatively specific to particular tumors within this differential diagnosis and hence might be diagnostically informative.

Targeting p63 Upregulation Abrogates Resistance to MAPK Inhibitors in Melanoma

Targeting the MAPK pathway by combined inhibition of BRAF and MEK has increased overall survival in advanced BRAF-mutant melanoma in both therapeutic and adjuvant clinical settings. However, a significant proportion of tumors develop acquired resistance, leading to treatment failure. We have previously shown p63 to be an important inhibitor of p53-induced apoptosis in melanoma following genotoxic drug exposure. Here, we investigated the role of p63 in acquired resistance to MAPK inhibition and show that p63 isoforms are upregulated in melanoma cell lines chronically exposed to BRAF and MEK inhibition, with consequent increased resistance to apoptosis. This p63 upregulation was the result of its reduced degradation by the E3 ubiquitin ligase FBXW7. FBXW7 was itself regulated by MDM2, and in therapy-resistant melanoma cell lines, nuclear accumulation of MDM2 caused downregulation of FBXW7 and consequent upregulation of p63. Consistent with this, both FBXW7-inactivating mutations and MDM2 upregulation were found in melanoma clinical samples. Treatment of MAPK inhibitor-resistant melanoma cells with MDM2 inhibitor Nutlin-3A restored FBXW7 expression and p63 degradation in a dose-dependent manner and sensitized these cells to apoptosis. Collectively, these data provide a compelling rationale for future investigation of Nutlin-3A as an approach to abrogate acquired resistance of melanoma to MAPK inhibitor targeted therapy. SIGNIFICANCE: Upregulation of p63, an unreported mechanism of MAPK inhibitor resistance in melanoma, can be abrogated by treatment with the MDM2 inhibitor Nutlin-3A, which may serve as a strategy to overcome resistance.

Human Papillomaviruses and Skin Cancer

Human papillomaviruses (HPVs) infect squamous epithelia and can induce hyperproliferative lesions. More than 220 different HPV types have been characterized and classified into five different genera. While mucosal high-risk HPVs have a well-established causal role in anogenital carcinogenesis, the biology of cutaneous HPVs is less well understood.From patients with the rare genetic disorder epidermodysplasia verruciformis (EV) and animal models, evidence is accumulating that cutaneous PV of genus β synergize with ultraviolet (UV) radiation in the development of cutaneous squamous cell carcinoma (cSCC). In 2009, the International Agency for Research on Cancer (IARC) classified the genus β-HPV types 5 and 8 as "possible carcinogenic" biological agents (group 2B) in EV disease. Epidemiological and biological studies indicate that genus β-PV infection may also play a role in UV-mediated skin carcinogenesis in non-EV patients. However, they rather act at early stages of carcinogenesis and become dispensable for the maintenance of the malignant phenotype, compatible with a "hit-and-run" mechanism.This chapter will give an overview on genus β-PV infections and discuss similarities and differences of cutaneous and genus α mucosal high-risk HPV in epithelial carcinogenesis.

Molecular Mechanisms of p63-Mediated Squamous Cancer Pathogenesis

The p63 gene is a member of the p53/p63/p73 family of transcription factors and plays a critical role in development and homeostasis of squamous epithelium. p63 is transcribed as multiple isoforms; ΔNp63α, the predominant p63 isoform in stratified squamous epithelium, is localized to the basal cells and is overexpressed in squamous cell cancers of multiple organ sites, including skin, head and neck, and lung. Further, p63 is considered a stem cell marker, and within the epidermis, ΔNp63α directs lineage commitment. ΔNp63α has been implicated in numerous processes of skin biology that impact normal epidermal homeostasis and can contribute to squamous cancer pathogenesis by supporting proliferation and survival with roles in blocking terminal differentiation, apoptosis, and senescence, and influencing adhesion and migration. ΔNp63α overexpression may also influence the tissue microenvironment through remodeling of the extracellular matrix and vasculature, as well as by enhancing cytokine and chemokine secretion to recruit pro-inflammatory infiltrate. This review focuses on the role of ΔNp63α in normal epidermal biology and how dysregulation can contribute to cutaneous squamous cancer development, drawing from knowledge also gained by squamous cancers from other organ sites that share p63 overexpression as a defining feature.

Cross-talk of cutaneous beta human papillomaviruses and the immune system: determinants of disease penetrance

Human papillomaviruses (HPVs) infect the epithelia of skin or mucosa, where they can induce hyperproliferative lesions. More than 220 different HPV types have been characterized and classified into five different genera. Mucosal high-risk HPVs are causative for cancers of the anogenital region and oropharynx. Clinical data from patients with the rare genetic disorder epidermodysplasia verruciformis (EV) indicate that genus beta-HPVs cooperate with ultraviolet (UV) radiation in the development of cutaneous squamous cell carcinoma. In addition, epidemiological and biological findings indicate that beta-HPV types play a role in UV-mediated skin carcinogenesis also in non-EV individuals. However, the mechanisms used by these cutaneous viruses to promote epithelial carcinogenesis differ significantly from those of mucosal HPVs. Recent studies point to a delicate cross-talk of beta-HPVs with the cell-autonomous immunity of the host keratinocytes and the local immune microenvironment that eventually determines the fate of cutaneous HPV infection and the penetrance of disease. This review gives an overview of the critical interactions of genus beta-HPVs with the local immune system that allow the virus to complete its life cycle, to escape from extrinsic immunity, and eventually to cause chronic inflammation contributing to skin carcinogenesis. This article is part of the theme issue 'Silent cancer agents: multi-disciplinary modelling of human DNA oncoviruses'.

ΔNp63 to TAp63 expression ratio as a potential molecular marker for cervical cancer prognosis

p63 is a transcription factor p53 family. Two major isoforms of p63, TAp63 with transactivation (TA) domain and ΔNp63 with truncated TA domain, have been reported to play opposing roles either in tumor suppression or oncogenic function. Little is known about the association of these two isoforms of p63 in the carcinogenesis of cervical cancer. In this study, the mRNA expression levels of TAp63 and ΔNp63 in 40 normal, 30 low-grade squamous intraepithelial lesions (LSIL), 38 high-grade squamous intraepithelial lesions (HSIL), and 52 cervical cancer formalin-fixed paraffin-embedded tissues were examined using quantitative reverse transcription polymerase chain reaction (RT-qPCR). We analyzed the association between the ΔNp63 and ΔN/TAp63 mRNA expression ratio and clinicopathological parameters and compared disease-specific survival of each ΔNp63 mRNA expression and ΔN/TAp63 mRNA expression ratio. The ΔN/TAp63 mRNA expression ratio in cervical cancer showed higher sensitivity than the mRNA expression levels of ΔNp63 (52.0% vs 44.2%). The level of ΔN/TAp63 mRNA expression ratio in precancerous LSIL and HSIL was higher than in normal tissues (P = 0.01 and P = 0.003) and lower than in cervical cancer tissues (P = 0.03 and P = 0.02). Besides, the positive ΔN/TAp63 mRNA expression ratio was associated with bulky tumor size and high expression of Ki-67, the proliferation marker, in cervical cancer (P = 0.04 and P = 0.02). The cervical cancer patients with the positive ΔN/TAp63 mRNA expression ratio showed worse survival compared to those who with the negative expression ratio of ΔN/TAp63 (HR = 5.7, 95% CI: 1.6–19.9). In conclusion, the balance of TAp63 and ΔNp63 is closely related to the carcinogenesis of cervical cancer. The ΔN/TAp63 mRNA expression ratio could be useful as a diagnostic and prognostic marker of cervical cancer.

p63 is a key regulator of iRHOM2 signalling in the keratinocyte stress response

Hyperproliferative keratinocytes induced by trauma, hyperkeratosis and/or inflammation display molecular signatures similar to those of palmoplantar epidermis. Inherited gain-of-function mutations in RHBDF2 (encoding iRHOM2) are associated with a hyperproliferative palmoplantar keratoderma and squamous oesophageal cancer syndrome (termed TOC). In contrast, genetic ablation of rhbdf2 in mice leads to a thinning of the mammalian footpad, and reduces keratinocyte hyperproliferation and migration. Here, we report that iRHOM2 is a novel target gene of p63 and that both p63 and iRHOM2 differentially regulate cellular stress-associated signalling pathways in normal and hyperproliferative keratinocytes. We demonstrate that p63-iRHOM2 regulates cell survival and response to oxidative stress via modulation of SURVIVIN and Cytoglobin, respectively. Furthermore, the antioxidant compound Sulforaphane downregulates p63-iRHOM2 expression, leading to reduced proliferation, inflammation, survival and ROS production. These findings elucidate a novel p63-associated pathway that identifies iRHOM2 modulation as a potential therapeutic target to treat hyperproliferative skin disease and neoplasia.

Phosphorylation of Pkp1 by RIPK4 regulates epidermal differentiation and skin tumorigenesis

Tissue homeostasis of skin is sustained by epidermal progenitor cells localized within the basal layer of the skin epithelium. Post-translational modification of the proteome, such as protein phosphorylation, plays a fundamental role in the regulation of stemness and differentiation of somatic stem cells. However, it remains unclear how phosphoproteomic changes occur and contribute to epidermal differentiation. In this study, we survey the epidermal cell differentiation in a systematic manner by combining quantitative phosphoproteomics with mammalian kinome cDNA library screen. This approach identified a key signaling event, phosphorylation of a desmosome component, PKP1 (plakophilin-1) by RIPK4 (receptor-interacting serine-threonine kinase 4) during epidermal differentiation. With genome-editing and mouse genetics approach, we show that loss of function of either Pkp1 or Ripk4 impairs skin differentiation and enhances epidermal carcinogenesis in vivo Phosphorylation of PKP1's N-terminal domain by RIPK4 is essential for their role in epidermal differentiation. Taken together, our study presents a global view of phosphoproteomic changes that occur during epidermal differentiation, and identifies RIPK-PKP1 signaling as novel axis involved in skin stratification and tumorigenesis.