Expression of Early Growth Response 3 in Skin Cancers

OBJECTIVE

To assess the expression of early growth response 3 (EGR3) in normal skin and different types of skin tumors: cutaneous squamous cell carcinoma (cSCC), basal cell carcinoma (BCC), melanoma (MM), and cutaneous adnexal tumors containing sebaceous carcinoma (SC), trichoepithelioma (TE) and clear cell hidradenoma (CCH).

BACKGROUND

EGR3, expressed in multiple organs, including skin, plays an important role in cell differentiation and tumor growth. Previous studies have shown that EGR3 suppresses tumor growth and is downregulated in various malignancies. However, its distribution in normal skin and its expression especially in skin tumors have not been studied.

MATERIALS AND METHODS

Samples of normal cases (n = 4), cSCC (n = 12), BCC (n = 12), MM (n = 12), SC (n = 4), TE (n = 4), and CCH (n = 4) were collected from patients treated in our department between 2018 and 2023. Immunohistochemistry was used to investigate the expression of EGR3. The results were analyzed with the description of the staining pattern and the histochemical score.

RESULTS

Immunohistochemical staining showed that EGR3 was uniquely expressed in normal skin in the granular layer and upper part of the stratum spinosum, as well as in sebaceous glands and hair follicles, but not in sweat glands. In skin cancers, BCC, SC, and TE showed positive EGR3 staining, whereas cSCC, MM, and CCH were negative.

CONCLUSIONS

EGR3 has a specific expression pattern in normal skin and in skin tumors, which is important for the differential diagnosis of skin tumors, in particular for cSCC and sebaceous gland carcinoma.

A Case of Biphenotypic Adnexal Carcinoma With Bowenoid and Basaloid Features: Focus on the Expression of SOX9 and Wnt Signaling Pathway Molecules, Including CDX2

ABSTRACT

An 87-year-old woman presented with a pedunculated nodule of 1.2 × 1.2 × 0.6 cm on her left cheek. Microscopic examination of the lesion revealed bowenoid and rosette-like basaloid components, resembling Bowen disease and neuroendocrine carcinoma, respectively. Immunohistochemically, both components were positive for Wnt signaling pathway molecules-nuclear/cytoplasmic beta-catenin, lymphoid enhancer binding factor 1 (LEF1), and caudal type homeobox 2 (CDX2)-and the adnexal marker SRY-box transcription factor 9 (SOX9). Unlike neuroendocrine tumors and basal cell carcinomas, the basaloid component in the present case was negative for chromogranin A, INSM1, synaptophysin, and p40. Previously reported cases of similar CDX2-positive lesions were diagnosed as squamous cell carcinoma with enteric adenocarcinomatous differentiation and basaloid cutaneous carcinoma with a primitive cytomorphology. However, the lesion in the present case was simultaneously positive for SOX9, indicating adnexal differentiation. In particular, the expression of multiple Wnt signaling pathway molecules indicates follicular differentiation despite the absence of morphological follicular features, such as shadow cells. Moreover, shared immunopositivity for SOX9, CDX2, nuclear/cytoplasmic beta-catenin, and LEF1 by both bowenoid and basaloid components indicated that the bowenoid component did not represent Bowen disease but a part of the adnexal tumor, and that the basaloid component was not a tumor-to-tumor metastasis. After complete excision, no recurrence has been observed for 5 months. The findings of the present case expand the histological spectrum of cutaneous adnexal tumors with follicular immunophenotypic differentiation.

FoxP3-Positive Cells and Their Contacts with Mast Cells Are Highly Increased in Basal Cell Carcinoma

INTRODUCTION

The cells of the immune system are thought to contribute to the development of skin cancers, such as basal cell carcinoma (BCC). One possible mechanism may be the interaction between mast cells and regulatory T cells (Tregs), resulting in immunosuppression.

METHODS

Fresh-frozen biopsies from the lesional and nonlesional skin of 16 patients with BCC were processed for the enzymehistochemical staining of mast cell tryptase, immunohistochemical staining of FoxP3 (a marker of Tregs) as well as for the double-staining method to label tryptase+ cells and FoxP3+ cells on the same cryosection. The cell numbers and apparent morphological contacts (AMCs) between these cell types were counted.

RESULTS

There was a high increase in the number of tryptase+ cells, FoxP3+ cells, and AMCs between them in the lesional compared to corresponding nonlesional skin (p < 0.0001) in all cases.

CONCLUSION

A morphological basis is theoretically present in BCC, suggesting an immune evasive microenvironment.

Correlation of ultrasound features with Bcl-2 protein expression in basal cell carcinomas (BCCs)

BACKGROUND

The expression of the Bcl-2 protein is frequently observed in basal cell carcinomas (BCCs), making it a significant biological marker and potential therapeutic target. Skin ultrasonography offers a noninvasive means of obtaining anatomical information about cutaneous tumors.

OBJECTIVES

The purpose of this study was to investigate the correlation between ultrasound features and Bcl-2 expression in BCCs, to provide a reference for developing pharmacological treatment plans.

METHODS

According to the Bcl-2 protein expression, 74 BCCs confirmed by surgical pathology were divided into high Bcl-2 expression BCCs (HB-BCCs) and low Bcl-2 expression BCCs (LB-BCCs). Preoperative lesion ultrasound features were analyzed retrospectively based on Liang's criteria, which included the following features: shape, surface, keratinization, base, infiltration level, internal echogenicity, distribution of hyperechoic spots, posterior echogenic changes, internal Doppler signal, and lesion size (maximum diameter and infiltration depth). The differences of two groups were compared using a chi-square test or a paired t-test.

RESULTS

Based on ultrasound features, cystic areas were more frequent in LB-BCCs (χ2  = 7.015, P = .008). Furthermore, LB-BCCs exhibited greater infiltration depth than HB-BCCs (4.86 ± 2.12 mm vs. 2.72 ± 1.40 mm, P = .000), had a higher propensity to infiltrate the subcutaneous tissue (χ2  = 12.422, P = .002), and displayed a more abundant internal Doppler signal within the lesions (χ2  = 24.696, P = .000). Conversely, maximum diameter of the lesions, shape, surface, keratinization, base, hyperechoic spots distribution, and posterior echogenic changes of the lesions did not differ significantly between the two groups.

CONCLUSIONS

Ultrasound features are correlated with Bcl-2 protein expression level in BCCs. LB-BCCs show greater infiltration depth, subcutaneous infiltration, more cystic changes and more abundant internal Doppler signal than HB-BCCs, which may suggest a potential basis for drug selection in BCC chemotherapy.

Pharmacokinetics and pharmacodynamics of Hedgehog pathway inhibitors used in the treatment of advanced or treatment-refractory basal cell carcinoma

INTRODUCTION

Sonidegib and vismodegib are currently the only US Food and Drug Administration and European Medicines Agency-approved small-molecule Hedgehog pathway inhibitors (HHIs)for treating adults with advanced or refractory basal cell carcinoma (BCC) that is not amenable to conventional surgery or radiotherapy. At this time, there are no head-to-head clinical trials comparing these two HHIs for efficacy and safety to assist clinicians with determining which HHI may be best suited for their patients.

AREAS COVERED

This review briefly describes the pathogenesis of BCC, provides a detailed overview of the key pharmacokinetic profile differences between sonidegib and vismodegib, explains their pharmacodynamics, and highlights the therapeutic considerations when either HHI is used to treat special patient populations.

EXPERT OPINION

Although both HHIs act at the same molecular target in the Hedgehog pathway, there are significant differences in their pharmacokinetic profiles that may play a potential role in their efficacy and safety. Evidence-based recommendations serve to inform clinicians until direct comparative clinical trials of sonidegib versus vismodegib are conducted to determine the clinical relevance of the reported differences in their pharmacokinetic properties.

Skin basal cell carcinomas assemble a pro-tumorigenic spatially organized and self-propagating Trem2+ myeloid niche

Cancer immunotherapies have revolutionized treatment but have shown limited success as single-agent therapies highlighting the need to understand the origin, assembly, and dynamics of heterogeneous tumor immune niches. Here, we use single-cell and imaging-based spatial analysis to elucidate three microenvironmental neighborhoods surrounding the heterogeneous basal cell carcinoma tumor epithelia. Within the highly proliferative neighborhood, we find that TREM2+ skin cancer-associated macrophages (SCAMs) support the proliferation of a distinct tumor epithelial population through an immunosuppression-independent manner via oncostatin-M/JAK-STAT3 signaling. SCAMs represent a unique tumor-specific TREM2+ population defined by VCAM1 surface expression that is not found in normal homeostatic skin or during wound healing. Furthermore, SCAMs actively proliferate and self-propagate through multiple serial tumor passages, indicating long-term potential. The tumor rapidly drives SCAM differentiation, with intratumoral injections sufficient to instruct naive bone marrow-derived monocytes to polarize within days. This work provides mechanistic insights into direct tumor-immune niche dynamics independent of immunosuppression, providing the basis for potential combination tumor therapies.

Expression of β-Catenin, E-Cadherin, and α-Smooth Muscle Actin in Basal Cell Carcinoma Before Photodynamic Therapy in Non-recurrent and Recurrent Tumors: Exploring the Ability of Predicting Photodynamic Therapy Outcome

Photodynamic therapy (PDT) is an effective and cosmetically beneficial treatment of low-risk basal cell carcinomas (BCCs). To optimize PDT response, it is important to correctly select tumors. We sought to find markers that could identify such tumors beyond contributions from clinical and histological examination. Studies have shown that β-catenin, E-cadherin, and α-smooth muscle actin (SMA) expression can indicate BCC aggressiveness/BCC invasiveness. We wanted to use these markers in an explorative study to investigate whether they were differently expressed among non-recurring compared with recurring BCCs, to evaluate their ability of predicting PDT outcome. Fifty-two BCCs were stained with antibodies against β-catenin, E-cadherin, and α-SMA, and evaluated using immunoreactive score (IRS), subcellular localization, and stromal protein expression. Results showed that IRS of E-cadherin was significantly different among recurring compared with non-recurring BCCs and with area under a receiver operating characteristic curve of 0.71 (95% confidence interval: 0.56-0.86, p=0.025). Stromal β-catenin expression significantly increased among recurring BCCs. Some recurring BCCs had intense expression in the deep invading tumor edge. In conclusion, E-cadherin, and stromal and deep edge β-catenin expression were most prominent in BCCs that recurred post-PDT, suggesting they could potentially predict PDT outcome. Further studies are needed to investigate whether these results are of clinical value.

Segmental basaloid follicular hamartomas derive from a post-zygotic SMO p.L412F pathogenic variant and express hair follicle development-related proteins in a pattern that distinguish them from basal cell carcinomas

Basaloid follicular hamartomas (BFH) are benign small basaloid skin tumors that can present as solitary or multiple lesions. Congenital BFH lesions arranged in a segmental distribution have been described, suggesting they derive from a somatic post-zygotic mutational event. Previously, BFH were described in Happle-Tinschert syndrome, which results from a post-zygotic SMO variant and is characterized by segmental BFH with variable involvement of the teeth, skeleton, and central nervous system. Here, we describe two patients with isolated segmental BFH and no systemic involvement. Paired whole exome sequencing of BFH and normal tissue revealed a pathogenic SMO c.1234 C>T, p.L412F variant restricted to BFH tissue. We characterized the proliferation index and expression of Hedgehog and Wnt/beta-catenin pathway related proteins in segmental BFH compared to sporadic basal cell carcinomas (BCCs) and found that segmental BFH had a lower proliferation index. Although segmental BFH expressed a similar level of Gli-1 compared to BCCs, levels of LEF-1 and SOX-9 expression in BFH were weaker for both and patchier for LEF-1. Our results show that a somatic SMO activating variant causes segmental BFH. Since these patients are prone to developing BCCs, differences in SOX9, LEF1, and Ki-67 expression can help distinguish between these two basaloid lesions.

Novel Approaches in Non-Melanoma Skin Cancers—A Focus on Hedgehog Pathway in Basal Cell Carcinoma (BCC)

Basal cell carcinoma (BCC) is one of the most common neoplasms in the population. A good prognosis and mainly non-aggressive development have made it underdiagnosed and excluded from the statistics. Due to the availability of efficient surgical therapy, BCC is sometimes overlooked in the search for novel therapies. Most clinicians are unaware of its complicated pathogenesis or the availability of effective targeted therapy based on Hedgehog inhibitors (HHI) used in advanced or metastatic cases. Nevertheless, the concomitance and esthetic burden of this neoplasm are severe. As with other cancers, its pathogenesis is multifactorial and complicated with a network of dependencies. Although the tumour microenvironment (TME), genetic aberrations, and risk factors seem crucial in all skin cancers, in BCC they all have become accessible as therapeutic or prevention targets. The results of this review indicate that a central role in the development of BCC is played by the Hedgehog (Hh) signalling pathway. Two signalling molecules have been identified as the main culprits, namely Patched homologue 1 (PTCH1) and, less often, Smoothened homologue (SMO). Considering effective immunotherapy for other neoplastic growths being introduced, implementing immunotherapy in advanced BCC is pivotal and beneficial. Up to now, the US Food and Drug Administration (FDA) has approved two inhibitors of SMO for the treatment of advanced BCC. Sonidegib and vismodegib are registered based on their efficacy in clinical trials. However, despite this success, limitations might occur during the therapy, as some patients show resistance to these molecules. This review aims to summarize novel options of targeted therapies in BCC and debate the mechanisms and clinical implications of tumor resistance.

Serum Vitamin D Levels Explored in the Latvian Cohort of Patients with Basal Cell Carcinoma Linked to the Sonic Hedgehog and Vitamin D Binding Protein Cutaneous Tissue Indices

Ultraviolet radiation is known as one of the major contributors to skin malignancies, including basal cell carcinoma (BCC), which is the most common type of skin cancer. It is a heterogeneous tumor, which presents with various types that are stratified into low- and high-risk tumors. Sunlight is important for overall health and vitamin D synthesis in the skin, whereas deviations from the optimal level of vitamin D are shown to be associated with the risk of the development of BCC. The accumulating evidence suggests the ability of vitamin D to antagonize the Sonic Hedgehog (SHH) signaling, the key tumor pathway, and play a protective role in the development of BCC. Additionally, a vitamin D binding protein (DBP) is shown to be implicated in the complex regulation of vitamin D. Here, we aimed to explore serum vitamin D in patients with different primary and recurrent BCC of the head and neck and investigate cutaneous DBP and SHH indices, confirmed immunohistochemically in these subjects. According to the results, 94.9% of the Latvian cohort of BCC patients were found to be deficient in vitamin D. No significant differences in serum vitamin D levels were found between genders, primary and recurrent tumors, and different types of BCC. Serum vitamin D was inversely associated with tumor size. Susceptible male individuals with low blood vitamin D levels were recognized at risk of developing aggressive and recurrent BCC confirmed by the use of hierarchical clustering analysis. In smaller tumors with a favorable course, such as superficial and nodular BCC, the association between high DBP and low SHH tissue expression was found, providing supportive evidence of the existence of a link between vitamin D, proteins involved in its metabolism, as exemplified by the DBP and SHH signaling pathway. The assumption of a deficiency in the protective effect of vitamin D in patients with high-risk BCCs was proposed in low DBP and high SHH tissue indices. New extensions to existing knowledge and characterization of the BCC signaling pathways and their cross-talk with vitamin D are warranted when searching for a preferential effect of vitamin D on skin cancer.

High cyclin E1 protein, but not gene amplification, is prognostic for basal-like breast cancer

Basal-like breast cancer (BLBC) has a greater overlap in molecular features with high-grade serous ovarian cancer (HGSOC) than with other breast cancer subtypes. Similarities include BRCA1 mutation, high frequency of TP53 mutation, and amplification of CCNE1 (encoding the cyclin E1 protein) in 6-34% of cases, and these features can be used to group patients for targeted therapies in clinical trials. In HGSOC, we previously reported two subsets with high levels of cyclin E1: those in which CCNE1 is amplified, have intact homologous recombination (HR), and very poor prognosis; and a CCNE1 non-amplified subset, with more prevalent HR defects. Here, we investigate whether similar subsets are identifiable in BLBC that may allow alignment of patient grouping in clinical trials of agents targeting cyclin E1 overexpression. We examined cyclin E1 protein and CCNE1 amplification in a cohort of 76 BLBCs and validated the findings in additional breast cancer datasets. Compared to HGSOC, CCNE1 amplified BLBC had a lower level of amplification (3.5 versus 5.2 copies) and lower relative cyclin E1 protein, a lack of correlation of amplification with expression, and no association with polyploidy. BLBC with elevated cyclin E1 protein also had prevalent HR defects, and high-level expression of the cyclin E1 deubiquitinase ubiquitin-specific protease 28 (USP28). Using a meta-analysis across multiple studies, we determined that cyclin E1 protein overexpression but not amplification is prognostic in BLBC, while both cyclin E1 overexpression and amplification are prognostic in HGSOC. Overall CCNE1 gene amplification is not equivalent between BLBC and HGSOC. However, high cyclin E1 protein expression can co-occur with HR defects in both BLBC and HGSOC, and is associated with poor prognosis in BLBC.

Single-cell analysis of human basal cell carcinoma reveals novel regulators of tumor growth and the tumor microenvironment

How basal cell carcinoma (BCC) interacts with its tumor microenvironment to promote growth is unclear. We use singe-cell RNA sequencing to define the human BCC ecosystem and discriminate between normal and malignant epithelial cells. We identify spatial biomarkers of tumors and their surrounding stroma that reinforce the heterogeneity of each tissue type. Combining pseudotime, RNA velocity-PAGA, cellular entropy, and regulon analysis in stromal cells reveals a cancer-specific rewiring of fibroblasts, where STAT1, TGF-β, and inflammatory signals induce a noncanonical WNT5A program that maintains the stromal inflammatory state. Cell-cell communication modeling suggests that tumors respond to the sudden burst of fibroblast-specific inflammatory signaling pathways by producing heat shock proteins, whose expression we validated in situ. Last, dose-dependent treatment with an HSP70 inhibitor suppresses in vitro vismodegib-resistant BCC cell growth, Hedgehog signaling, and in vivo tumor growth in a BCC mouse model, validating HSP70's essential role in tumor growth and reinforcing the critical nature of tumor microenvironment cross-talk in BCC progression.

Delivery of Targeted Co(III)-DNA Inhibitors of Gli Proteins to Disrupt Hedgehog Signaling

The Hedgehog (Hh) signaling pathway is integral for embryonic development and normal cell maintenance. However, aberrant expression of the Hh pathway is recognized as the oncogenic driving force for basal cell carcinoma (BCC). Current chemotherapeutic treatments that inhibit Hh signaling allow treatment of only locally advanced and metastatic BCCs via inhibition of the transmembrane protein, smoothened. It is further recognized that downstream mutations often lead to chemoresistant tumor recurrence. The Gli proteins are the ultimate regulators of Hh signaling and belong to a family of Cys2His2 zinc finger transcription factors (ZnFTFs) that we have shown can be irreversibly inhibited by a series of cobalt(III) Schiff base-DNA (CoSB-DNA) conjugates. However, a significant challenge is the delivery of CoSB-DNA complexes in mammalian tissues. Herein, we report a polyethyleneimine-functionalized graphene oxide nanoconjugate (GOPEI) that delivers CoGli, a CoSB-DNA complex that targets Gli specifically. We describe the characterization of the surface functionalization of GOPEI and accumulation in ASZ murine BCC cells via confocal microscopy and inductively coupled plasma-mass spectrometry (ICP-MS). Lysosomal escape of CoGli is further confirmed by confocal microscopy. We report the successful targeting of Gli by CoGli and a 17-fold improvement in potency over small-molecule Gli inhibitor GANT-61 in inhibiting Hh-driven migration of ASZ murine BCC cells. This study provides a promising starting point for further investigating CoGli inhibitors of Hh signaling in developed mammalian tissues.

Affinity-based protein profiling identifies vitamin D3 as a heat shock protein 70 antagonist that regulates hedgehog transduction in murine basal cell carcinoma

Vitamin D3 (VD3) is a seco-steroid that inhibits the Hedgehog (Hh) signaling pathway. Initial studies suggested its anti-Hh activity results from direct inhibition of Smoothened, a seven-transmembrane cell surface receptor that is a key regulator of the Hh signaling cascade. More recently, a role for the Vitamin D Receptor in mediating inhibition of Hh-signaling by seco-steroid has been suggested. Herein, an affinity-based protein profiling study was carried out to better understand the cellular proteins that govern VD3-mediated anti-Hh activity. We synthesized a novel biotinylated VD3 analogue (8) for use as a chemical probe to explore cellular binding targets of the seco-steroidal scaffold. Through a series of pull-down experiments and follow up mass spectrum analyses, heat shock protein 70 (Hsp70) was identified as a primary binding protein of VD3. Hsp70 was validated as a binding target of VD3 through a series of biochemical and cellular assays. VD3 bound with micromolar affinity to Hsp70. In addition, both selective knockdown of Hsp70 expression and pharmacological inhibition of its activity with known Hsp70 inhibitors suppressed Hh-signaling transduction in murine basal cell carcinoma cells, suggesting that Hsp70 regulates proper Hh-signaling. Additional cellular assays suggest that VD3 and its seco-steroidal metabolites inhibit Hh-signaling through different mechanisms.

Expression of Proton-Sensitive GPR31, GPR151, TASK1 and TASK3 in Common Skin Tumors

TWIK-related acid-sensitive potassium channels TASK1 and TASK3, as well as the G-protein-coupled receptors GPR31 and GPR151, are proton-sensitive membrane proteins. They can be activated or inhibited by low extracellular pH (pHe), which is a hallmark of the tumor microenvironment in solid tumors. However, the role of these channels in the development of skin tumors is still unclear. In this study, we investigated the expression profiles of TASK1, TASK3, GPR31 and GPR151 in squamous cell carcinomas (SCCs), basal cell carcinomas (BCCs), nevus cell nevi (NCN), and malignant melanomas (MMs). We performed immunohistochemistry using paraffin-embedded tissue samples from patients and found that most skin tumors express TASK1/3 and GPR31/151. The results show that BCCs are often negative for GPR31/151 as well as for TASK1/3, while nearly all SCCs express these markers. MMs and NCN show similar expression patterns. However, some tumors show a decreasing TASK1/3 expression in deeper dermal tumor tissue, while GPCRs were expressed more evenly. The lower frequency of GPR31/151 and TSAK1/3 expression in BCCs when compared to SCCs is a novel histological feature distinguishing these two entities. Moreover, BCCs also show lower expression of GPR31/151 and TASK1/3 as compared to NCN and MMs.

Noncovalent Interactions with PAMAM and PPI Dendrimers Promote the Cellular Uptake and Photodynamic Activity of Rose Bengal: The Role of the Dendrimer Structure

Rose bengal is an anionic dye considered as a potential photosensitizer for anticancer photodynamic therapy. The clinical utility of rose bengal is hampered by its short half-life, limited transmembrane transport, aggregation, and self-quenching; consequently, efficient drug carriers that overcome these obstacles are urgently required. In this study, we performed multilevel in vitro and in silico characterization of interactions between rose bengal and cationic poly(amidoamine) (PAMAM) and poly(propyleneimine) (PPI) dendrimers of the third and fourth generation and assessed the ability of the resultant complexes to modulate the photosensitizing properties of the drug. We focused on explaining the molecular basis of this phenomenon and proved that the generation- and structure-dependent binding of the dye by the dendrimers increases the cellular uptake and production of singlet oxygen and intracellular reactive oxygen species, leading to an increase in phototoxicity. We conclude that the application of dendrimer carriers could enable the design of efficient photodynamic therapies based on rose bengal.

c-FOS drives reversible basal to squamous cell carcinoma transition

While squamous transdifferentiation within subpopulations of adenocarcinomas represents an important drug resistance problem, its underlying mechanism remains poorly understood. Here, using surface markers of resistant basal cell carcinomas (BCCs) and patient single-cell and bulk transcriptomic data, we uncover the dynamic roadmap of basal to squamous cell carcinoma transition (BST). Experimentally induced BST identifies activator protein 1 (AP-1) family members in regulating tumor plasticity, and we show that c-FOS plays a central role in BST by regulating the accessibility of distinct AP-1 regulatory elements. Remarkably, despite prominent changes in cell morphology and BST marker expression, we show using inducible model systems that c-FOS-mediated BST demonstrates reversibility. Blocking EGFR pathway activation after c-FOS induction partially reverts BST in vitro and prevents BST features in both mouse models and human tumors. Thus, by identifying the molecular basis of BST, our work reveals a therapeutic opportunity targeting plasticity as a mechanism of tumor resistance.

Investigating DNA methylation as a potential mediator between pigmentation genes, pigmentary traits and skin cancer

Pigmentation characteristics are well-known risk factors for skin cancer. Polymorphisms in pigmentation genes have been associated with these traits and with the risk of malignancy. However, the functional relationship between genetic variation and disease is still unclear. This study aims to assess whether pigmentation SNPs are associated with pigmentary traits and skin cancer via DNA methylation (DNAm). Using a meta-GWAS of whole-blood DNAm from 36 European cohorts (N = 27,750; the Genetics of DNA Methylation Consortium, GoDMC), we found that 19 out of 27 SNPs in 10 pigmentation genes were associated with 391 DNAm sites across 30 genomic regions. We examined the effect of 25 selected DNAm sites on pigmentation traits, sun exposure phenotypes and skin cancer and on gene expression in whole blood. We uncovered an association of DNAm site cg07402062 with red hair in the Avon Longitudinal Study of Parents and Children (ALSPAC). We also found that the expression of ASIP and CDK10 was associated with hair colour, melanoma and basal cell carcinoma. Our results indicate that DNAm and expression of pigmentation genes may play a role as potential mediators of the relationship between genetic variants, pigmentation phenotypes and skin cancer and thus deserve further scrutiny.

Cutaneous Human Papillomaviruses and the Risk of Keratinocyte Carcinomas

Cutaneous human papillomavirus (cuHPV) infections may be novel targets for skin cancer prevention and treatment, but critical information regarding the development of virus-positive skin cancers following cuHPV infection has been lacking. In this study, baseline cuHPV infection was measured by serology and viral DNA detection in eyebrow hairs (EBH) and forearm skin swabs (SSW) among 1,008 individuals undergoing routine skin cancer screening exams and followed for incidence of basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (cuSCC). Baseline β-HPV detection, particularly in SSW, significantly predicted cuSCC (HR = 4.32; 95% confidence interval, 1.00-18.66), whereas serologic evidence of past β-HPV infection was not associated with cuSCC. Less than 5% of baseline β-HPV types detected in SSW were present in subsequent cuSCC tumors, and cuHPV detected in SSW with higher mean fluorescence intensity values were more likely to be present in cuSCC compared with those with lower levels (P < 0.001). β-HPV-positive cuSCC occurred more often in areas of highly sun-damaged skin than did β-HPV-negative cuSCC. Overall, no clear patterns were observed between baseline β-HPV detection and subsequent development of BCC, or between baseline γ-HPV detection and either cuSCC or BCC. Collectively, these results demonstrate that β-HPV detection in SSW is a significant predictor of cuSCC risk, although evidence suggests only a small subset of cuSCC is etiologically linked to β-HPV infection. SIGNIFICANCE: β-HPV positivity may be a useful biomarker for identifying individuals who could benefit from increased screening or novel cutaneous squamous cell carcinoma prevention strategies.

Manually scanned single fiber optical coherence tomography for skin cancer characterization

Optical coherence tomography (OCT) is a cross-sectional imaging modality based on low coherence light interferometry. Within dermatology, it has found applications for in vivo diagnostic imaging purposes, as well as to guide Mohs micrographic surgery (MMS), due to its ability to visualize skin morphology up to several millimeters in depth. However, standard OCT probes have a large footprint and capture an extended area of the skin, making it difficult to precisely pinpoint clinically relevant location being imaged. Mohs surgeons stand to benefit from a handheld in vivo imaging device that can accurately trace surgical margins. In this study, we demonstrate the use of a single fiber OCT (sfOCT) instrument. Our imaging system features a miniature common path single fiber probe, and a novel speckle decorrelation technique that generates distortion free 2D images from manual scanning.By manually moving the single-fiber probe across the region of interest, the user can perform a lateral OCT scan while visualizing the location of the probe during data acquisition. Using the sfOCT, we have identified normal skin morphology, qualitatively correlated features of basal cell carcinoma and squamous cell carcinoma with histopathology, and quantified the disruption of the dermo-epidermal junction OCT pattern in skin tumors-each demonstrating the potential of utilizing sfOCT to differentiate tumor from normal skin. Using this imaging tool, a Mohs surgeon can enhance determination of surgical margins for the first stage of MMS, potentially decreasing the time and number of stages required for complete tumor removal.

Rapid and exceptional response to Sonidegib in a patient with multiple locally advanced basal cell carcinomas

Locally advanced basal cell carcinoma (laBCC) represents a rare but possible occurrence in the vast scenario of dermatological diseases. It is well known that most BCC has a pathological activation of the hedgehog pathway, making them susceptible to targeted therapy with selective inhibitors. Sonidegib, approved for the treatment of laBCC on the basis of the results of the basal cell carcinoma outcomes with LDE225 treatment study, demonstrated rapid efficacy and a manageable safety profile. Here, we describe the case of a patient affected by multiple laBCC treated with Sonidegib. The patient experienced an important regression of tumors after only 2 months of therapy, with few side effects. This result confirms the role of Sonidegib as a valid and well-tolerated therapeutic option for laBCC.

Single-cell transcriptomics reveals involution mimicry during the specification of the basal breast cancer subtype

Basal breast cancer is associated with younger age, early relapse, and a high mortality rate. Here, we use unbiased droplet-based single-cell RNA sequencing (RNA-seq) to elucidate the cellular basis of tumor progression during the specification of the basal breast cancer subtype from the luminal progenitor population in the MMTV-PyMT (mouse mammary tumor virus-polyoma middle tumor-antigen) mammary tumor model. We find that basal-like cancer cells resemble the alveolar lineage that is specified upon pregnancy and encompass the acquisition of an aberrant post-lactation developmental program of involution that triggers remodeling of the tumor microenvironment and metastatic dissemination. This involution mimicry is characterized by a highly interactive multicellular network, with involution cancer-associated fibroblasts playing a pivotal role in extracellular matrix remodeling and immunosuppression. Our results may partially explain the increased risk and poor prognosis of breast cancer associated with childbirth.

The miR-5694/AF9/Snail Axis Provides Metastatic Advantages and a Therapeutic Target in Basal-like Breast Cancer

Epigenetic deregulation, especially mutagenesis or the abnormal expression of epigenetic regulatory factors (ERFs), plays an important role in malignant tumorigenesis. To screen natural inhibitors of breast cancer metastasis, we adopted small interfering RNAs (siRNAs) to transiently knock down 591 ERF-coding genes in luminal breast cancer MCF-7 cells and found that depletion of AF9 significantly promoted MCF-7 cell invasion and migration. A mouse model of metastasis further confirmed the suppressive role of AF9 in breast cancer metastasis. RNA profiling revealed enrichment of AF9 targets genes in the epithelial-mesenchymal transition (EMT). Mechanistically, tandem mass spectrometry showed that AF9 interacts with Snail, which hampers Snail transcriptional activity in basal-like breast cancer (BLBC) cells. AF9 reconstitutes an activated state on the promoter of Snail, which is a master regulator of EMT, and derepresses genes by recruiting CBP or GCN5. Additionally, microRNA-5694 (miR-5694) targeted and degraded AF9 messenger RNA (mRNA) in BLBC cells, further enhancing cell invasion and migration. Notably, AF9 and miR-5694 expression in BLBC clinical samples correlated inversely. Hence, miR-5694 mediates downregulation of AF9 and provides metastatic advantages in BLBC. Restoring expression of the metastasis suppressor AF9 is a possible therapeutic strategy against metastatic breast cancer.

Differentiation of Basal Cell Carcinoma and Trichoepithelioma: An Immunohistochemical Study

ABSTRACT

Basal cell carcinoma (BCC) is the most common malignancy of the skin. It is an epithelial neoplasm with origin in the precursor cells of the interfollicular epidermis. Even though it has low metastatic potential, delay in management may lead to local destruction and morbidity. In contrast, trichoepithelioma (TE) is a benign tumor originating from the outer root sheath of the hair follicle. Similar to BCC, TE tends to affect the head and neck region. Both neoplasms may exhibit clinical and histopathological similarities, making them prone to misdiagnosis. Multiple immunomarkers have been used to distinguish among these entities, but so far, no single agent or combination of agents appear to be neither sensitive nor specific enough to differentiate between them. This study was divided into 2 parts. First, 17 cases of BCC and 14 cases of TE were stained with androgen receptor and bcl-2. Then, 27 cases of borderline/equivocal of BCC and 13 cases of borderline/equivocal TE were stained with the same protocol. Sensitivity and specificity were calculated for each individual immunomarker and for the combination of them. Androgen receptor positivity was 100% specific for BCC and borderline/equivocal BCC, whereas bcl-2 diffuse staining pattern demonstrated a sensitivity of 82.4% for BCC and 88.9% borderline/equivocal BCC. When both immunomarkers were combined, the sensitivity for BCC decreased (70.6%) but the specificity remained high (100%). Similarly, the sensitivity for borderline/equivocal BCC was 55.6%, whereas the specificity was 100%. Although moderately sensitive, combining both immunomarkers showed an excellent specificity to discriminate between BCC and TE.

Spreading of Isolated Ptch Mutant Basal Cell Carcinoma Precursors Is Physiologically Suppressed and Counteracts Tumor Formation in Mice

Basal cell carcinoma (BCC) originate from Hedgehog/Patched signaling-activated epidermal stem cells. However, the chemically induced tumorigenesis of mice with a CD4Cre-mediated biallelic loss of the Hedgehog signaling repressor Patched also induces BCC formation. Here, we identified the cellular origin of CD4Cre-targeted BCC progenitors as rare Keratin 5⁺ epidermal cells and show that wildtype Patched offspring of these cells spread over the hair follicle/skin complex with increasing mouse age. Intriguingly, Patched mutant counterparts are undetectable in age-matched untreated skin but are getting traceable upon applying the chemical tumorigenesis protocol. Together, our data show that biallelic Patched depletion in rare Keratin 5⁺ epidermal cells is not sufficient to drive BCC development, because the spread of these cells is physiologically suppressed. However, bypassing the repression of Patched mutant cells, e.g., by exogenous stimuli, leads to an accumulation of BCC precursor cells and, finally, to tumor development.

A rare case of invasive melanoma likely arising from passenger melanocytes of a basal cell carcinoma

Neoplasms consisting of different cell lineages within a single skin specimen are rare, yet well documented in the literature. However, to date, there appears to be no report of invasive melanoma arising directly from the passenger melanocytes of a basal cell carcinoma (BCC). We present a case of a 91-year-old male with a suspicious lesion on the ear. Histopathology and immunohistochemical staining revealed BCC closely intertwined with invasive melanoma that exhibited foci of chondroid differentiation. The melanoma appeared to arise from the benign-appearing passenger melanocytes of the BCC and lacked connection to the overlying epidermis or an in situ component. Multiple dermatopathologists reviewed the case and agreed that the most likely explanation for the histopathologic findings was that the invasive melanoma arose from the passenger melanocytes within the BCC.

Hyperactive CDK2 Activity in Basal-like Breast Cancer Imposes a Genome Integrity Liability that Can Be Exploited by Targeting DNA Polymerase ε

Knowledge of fundamental differences between breast cancer subtypes has driven therapeutic advances; however, basal-like breast cancer (BLBC) remains clinically intractable. Because BLBC exhibits alterations in DNA repair enzymes and cell-cycle checkpoints, elucidation of factors enabling the genomic instability present in this subtype has the potential to reveal novel anti-cancer strategies. Here, we demonstrate that BLBC is especially sensitive to suppression of iron-sulfur cluster (ISC) biosynthesis and identify DNA polymerase epsilon (POLE) as an ISC-containing protein that underlies this phenotype. In BLBC cells, POLE suppression leads to replication fork stalling, DNA damage, and a senescence-like state or cell death. In contrast, luminal breast cancer and non-transformed mammary cells maintain viability upon POLE suppression but become dependent upon an ATR/CHK1/CDC25A/CDK2 DNA damage response axis. We find that CDK1/2 targets exhibit hyperphosphorylation selectively in BLBC tumors, indicating that CDK2 hyperactivity is a genome integrity vulnerability exploitable by targeting POLE.

A Vismodegib Experience in Elderly Patients with Basal Cell Carcinoma: Case Reports and Review of the Literature

Cutaneous basal cell carcinoma (BCC) is the most common type of human tumor, and its incidence rate is increasing worldwide. Up until a few years ago, therapeutic options have been limited for patients with advanced BCC (including metastatic and locally-advanced BCC). Over the last few years, promising systemic therapies have been investigated for the treatment of advanced BCC. In particular, the Hedgehog signaling inhibition has shown remarkable results for this population. Hedgehog inhibitors, represented by vismodegib and sonidegib, have been approved by the Food and Drug Administration and the European Medicines Agency for the treatment of both locally advanced and metastatic BCC, with, generally, a good safety profile. Notwithstanding the late onset of BCC in the global population, associated with life expectancy increase, only a few clinical trials have evaluated the efficacy and safety profile of Hedgehog inhibitors in this complex and neglected population. Herein, we review the major mechanisms implicated in the pathogenesis of BCC focusing on the Hedgehog signaling pathway and its therapeutic role in the elderly population. Finally, we report two case reports of BCC elderly patients in order to demonstrate both efficacy and safety of the Hedgehog inhibitors.

Expression profiles of proton-sensing G-protein coupled receptors in common skin tumors

The proton-sensing GPCRs (pH-GPCRs) GPR4 (GPR19), TDAG8 (GPR65, T-cell death associated gene 8), OGR1 (GPR68, ovarian cancer GPCR1), and G2A (GPR132, G2 accumulation protein) are involved in sensing and transducing changes in extracellular pH (pHe). Extracellular acidification is a central hallmark of solid cancer. pH-GPCR function has been associated with cancer cell proliferation, adhesion, migration and metastasis, as well as with modulation of the immune system. Little is known about the expression levels and role of pH-GPCRs in skin cancer. To better understand the functions of pH-GPCRs in skin cancer in vivo, we examined the expression-profiles of GPR4, TDAG8, OGR1 and G2A in four common skin tumors, i.e. squamous cell carcinoma (SCC), malignant melanoma (MM), compound nevus cell nevi (NCN), basal cell carcinoma (BCC). We performed immunohistochemistry and immunofluorescence staining on paraffin-embedded tissue samples acquired from patients suffering from SCC, MM, NCN or BCC. We show the expression of pH-GPCRs in four common skin cancers. Different expression patterns in the investigated skin cancer types indicate that the different pH-GPCRs may have distinct functions in tumor progression and serve as novel therapeutic targets.

Expression of p16 Protein in Cutaneous Basal Cell Carcinoma: Still far from Being Clearly Understood

Dear Editor, p16INK4a protein (p16) is an important tumor suppressor protein involved in the carcinogenesis of many human malignancies. I have read with interest an article by Donati et al. (1) in this journal, who investigated an expression of p16 and proliferation marker Ki-67 in cutaneous tumors. Among them, there were 27 cases of non-melanoma skin cancer (NMSC), 23 of which comprised basal cell carcinoma (BCC), and 4 squamous cell carcinoma (SCC) lesions. The authors stated "in NMSC, they found a high prevalence (69.6%) of lesions with p16 expression between 34-66%, while the remaining specimens showed p16 expression 34%". Although they did not specify the exact proportions of BCC and SCC, one may speculate that the majority of BCCs (and maybe all) were at least partly immunoreactive for p16. As the literature gives very contradictory data on this topic, herein I will present my personal observations in this field. I performed immunohistochemical analysis of p16 in a set of 24 cutaneous BCCs obtained from 23 patients. They were categorized into non-aggressive (4 superficial and 10 nodular subtypes) and aggressive (7 nodular-infiltrative and 3 infiltrative subtypes) subgroups. In all cases, monoclonal mouse antibody against p16 (clone G175-405, Zeta Corp., dilution 1:75) was used for staining. Overall, I found 7 cases (29.1%) of BCCs manifesting a certain degree of p16-immunoreactivity in the tumor tissue. These lesions arose on the head in four cases (4/17 23.5%) and on the back and limbs in three cases (3/7 42.8%). Histologically, they comprised four cases (4/14 28.6%) of non-aggressive and three cases (3/10 30%) of aggressive histologic subtypes, respectively. As regards to the extent of p16-positivity, it was only focal and involved merely 5-20% of total cancer tissue. Notably, p16-positive areas occurred only at the edges and at the invasive margins of tumor aggregates (Figure 1), except for the case of pure infiltrative BCC subtype in which they were haphazardly distributed within the tumor mass (Figure 2). p16-reactivity was not observed at the center of solid tumor nests. Immunohistochemical expression of p16 in cutaneous BCC is very variable and reported values vary greatly between publications. Some authors (2-6) demonstrated it in the vast majority (79.2-100%) of BCCs. Conscience et al. (7) and Zheng et al. (8) observed it only in 50% and 14.9% of the cases, respectively. Finally, Villada et al. (9) did not report any p16-positive BCC in their recent study. Based on the literature review (1-9), I speculate that such striking discrepancies could be attributed to the following reasons: a) different processing technique and methods used; b) heterogeneity of the biopsy sample size; c) case selection bias in terms of the prevalence of certain histological BCC subtypes; and d) different cut-off values defining the p16-positivity of tumors. Biologic and prognostic impact of p16 production in cutaneous BCC remains unclear. In principle, it would be valuable to know whether BCCs with at least focal p16 immunostaining behave differently from their p16-negative counterparts. Several studies have reported conflicting data regarding a potential effect of p16 to invasive properties. Svensson et al. (5) showed that p16 expression was associated with invasive BCCs with an infiltrative growth pattern. In superficial, nodular, and infiltrative histologic subtypes, they found p16-positivity in 75.0%, 88.8%, and 100.0% of the cases, respectively. Other authors (2,3) did not find a clear relationship between the aggressive growth phenotype of BCC and immunoreactivity for p16. The data presented herein support the results of the latter group, but the present sample of p16-positive BCCs was too small to provide a reliable conclusion. Nevertheless, evidence of p16-immunoreactivity at the edges of tumor nodules and in the infiltrative growth pattern was similar with the findings published by Svensson et al. (5). Another useful question is whether p16 protein production in neoplastic cells depends on the topographic distribution of lesions and if it may thus be influenced by solar exposure. Some authors (1,3,7) found that p16 overexpression was associated with NMSC arising on sun-exposed areas, suggesting a possible induction of p16 protein production by permanent ultraviolet radiation. On the other hand, Italian researchers (4) did not find such an association, as among the five BCCs arising on the head and neck region only one displayed a high p16 immunoreactivity. Furthermore, in the study conducted by Villada et al. (9), all ten p16-negative BCCs were situated on the head and neck. Taken together, the biologic and clinical aspects of p16 production in cutaneous BCC are still far from being clearly understood. I assume that a simple quantification of p16 expression in BCC by immunohistochemistry is not sufficient for a reliable assessment of the clinicopathologic significances. Further studies must be more focused on spatial distribution and intensity of p16-positive areas in tumor tissue.

Proteogenomic analysis of Inhibitor of Differentiation 4 (ID4) in basal-like breast cancer

BACKGROUND

Basal-like breast cancer (BLBC) is a poorly characterised, heterogeneous disease. Patients are diagnosed with aggressive, high-grade tumours and often relapse with chemotherapy resistance. Detailed understanding of the molecular underpinnings of this disease is essential to the development of personalised therapeutic strategies. Inhibitor of differentiation 4 (ID4) is a helix-loop-helix transcriptional regulator required for mammary gland development. ID4 is overexpressed in a subset of BLBC patients, associating with a stem-like poor prognosis phenotype, and is necessary for the growth of cell line models of BLBC through unknown mechanisms.

METHODS

Here, we have defined unique molecular insights into the function of ID4 in BLBC and the related disease high-grade serous ovarian cancer (HGSOC), by combining RIME proteomic analysis, ChIP-seq mapping of genomic binding sites and RNA-seq.

RESULTS

These studies reveal novel interactions with DNA damage response proteins, in particular, mediator of DNA damage checkpoint protein 1 (MDC1). Through MDC1, ID4 interacts with other DNA repair proteins (γH2AX and BRCA1) at fragile chromatin sites. ID4 does not affect transcription at these sites, instead binding to chromatin following DNA damage. Analysis of clinical samples demonstrates that ID4 is amplified and overexpressed at a higher frequency in BRCA1-mutant BLBC compared with sporadic BLBC, providing genetic evidence for an interaction between ID4 and DNA damage repair deficiency.

CONCLUSIONS

These data link the interactions of ID4 with MDC1 to DNA damage repair in the aetiology of BLBC and HGSOC.

FAK activates AKT-mTOR signaling to promote the growth and progression of MMTV-Wnt1-driven basal-like mammary tumors

BACKGROUND

Breast cancer is a heterogeneous disease. Hence, stratification of patients based on the subtype of breast cancer is key to its successful treatment. Among all the breast cancer subtypes, basal-like breast cancer is the most aggressive subtype with limited treatment options. Interestingly, we found focal adhesion kinase (FAK), a cytoplasmic tyrosine kinase, is highly overexpressed and activated in basal-like breast cancer.

METHODS

To understand the role of FAK in this subtype, we generated mice with conditional deletion of FAK and a knock-in mutation in its kinase domain in MMTV-Wnt1-driven basal-like mammary tumors. Tumor initiation, growth, and metastasis were characterized for these mice cohorts. Immunohistochemical and transcriptomic analysis of Wnt1-driven tumors were also performed to elucidate the mechanisms underlying FAK-dependent phenotypes. Pharmacological inhibition of FAK and mTOR in human basal-like breast cancer cell lines was also tested.

RESULTS

We found that in the absence of FAK or its kinase function, growth and metastasis of the tumors were significantly suppressed. Furthermore, immunohistochemical analyses of cleaved caspase 3 revealed that loss of FAK results in increased tumor cell apoptosis. To further investigate the mechanism by which FAK regulates survival of the Wnt1-driven tumor cells, we prepared an isogenic pair of mammary tumor cells with and without FAK and found that FAK ablation increased their sensitivity to ER stress-induced cell death, as well as reduced tumor cell migration and tumor sphere formation. Comparative transcriptomic profiling of the pair of tumor cells and gene set enrichment analysis suggested mTOR pathway to be downregulated upon loss of FAK. Immunoblot analyses further confirmed that absence of FAK results in reduction of AKT and downstream mTOR pathways. We also found that inhibition of FAK and mTOR pathways both induces apoptosis, indicating the importance of these pathways in regulating cell survival.

CONCLUSIONS

In summary, our studies show that in a basal-like tumor model, FAK is required for survival of the tumor cells and can serve as a potential therapeutic target.

SHARPIN regulates cell proliferation of cutaneous basal cell carcinoma via inactivation of the transcriptional factors GLI2 and c‑JUN

SHANK‑associated RH domain‑interacting protein (SHARPIN) is a component of the linear ubiquitin chain assembly complex that can enhance the NF‑κB and JNK signaling pathways, acting as a tumor‑associated protein in a variety of cancer types. The present study investigated the role of SHARPIN in cutaneous basal cell carcinoma (BCC). Human BCC (n=26) and normal skin (n=5) tissues, and BCC (TE354.T) and normal skin (HaCaT) cell lines were used to evaluate SHARPIN expression level using immunohistochemistry and western blotting, respectively. A lentivirus carrying SHARPIN‑targeting or negative control short hairpin RNA was infected into TE354.T cells, and the infected stable cells were assayed to analyze tumor cell proliferation, cell cycle, apoptosis, migration and invasion by Cell Counting Kit‑8 and 5‑ethynyl‑2'‑deoxyuridine incorporation assays, flow cytometry and Transwell assays. Western blotting was performed to assess the protein expression levels of gene signaling in SHARPIN‑silenced BCC cells. SHARPIN protein expression levels were downregulated or absent in BCC cancer nests and precancerous lesions compared with normal skin samples. In addition, SHARPIN expression levels were lower in TE354.T cells compared with HaCaT cells. SHARPIN shRNA enhanced tumor cell proliferation and the S phase of the cell cycle, whereas BCC cell apoptotic rates, and migratory and invasive abilities were not significantly altered. The expression levels of cyclin D1, cyclin‑dependent kinase 4, phosphorylated‑c‑JUN and GLI family zinc finger 2 proteins were increased, whereas Patched 1 (PTCH1) and PTCH2 were decreased in the SHARPIN‑shRNA‑infected BCC cells. Therefore, the present results suggested that SHARPIN may act as a tumor suppressor during BCC development.

Emerging noninvasive treatments of nonmelanoma skin cancers

Nonmelanoma skin cancer (NMSC) is the most common malignancy worldwide, and the incidence continues to increase. Originally, treatment options for NMSCs largely relied on destructive and surgical methods. Basal cell carcinomas (BCCs) and squamous cell carcinomas (SCCs) commonly are treated with cryosurgery, electrodesiccation and curettage, or more definitive surgical options. Over time, topical agents such as 5-fluorouracil, imiquimod, ingenol mebutate, and various forms of aminolevulinic acid (ALA) for photodynamic therapy (PDT) were included for superficial lesions as well as field treatment. The development of oral hedgehog (Hh) inhibitors such as vismodegib offered a promising alternative to patients with advanced disease. Each treatment has its own specific indications and side effects, thus there is always room for novel therapeutic approaches. We review new and potential treatments for NMSCs since 2018 including topical sonidegib, cemiplimab, taladegib, posaconazole, radiation therapy (RT), combination RT with vismodegib, PDT, and laser therapies.

The Role of Dermal Fibroblasts in Nevoid Basal Cell Carcinoma Syndrome Patients: An Overview

Nevoid basal cell carcinoma syndrome (NBCCS), also named Gorlin syndrome, is a rare multisystem genetic disorder characterized by marked predisposition to basal cell carcinomas (BCCs), childhood medulloblastomas, maxillary keratocysts, celebral calcifications, in addition to various skeletal and soft tissue developmental abnormalities. Mutations in the tumor suppressor gene PATCHED1 (PTCH1) have been found to be associated in the majority of NBCCS cases. PATCH1 somatic mutations and loss of heterozygosity are also very frequent in sporadic BCCs. Unlike non-syndromic patients, NBCCS patients develop multiple BCCs in sun-protected skin area starting from early adulthood. Recent studies suggest that dermo/epidermal interaction could be implicated in BCC predisposition. According to this idea, NBCCS fibroblasts, sharing with keratinocytes the same PTCH1 germline mutation and consequent constitutive activation of the Hh pathway, display features of carcinoma-associated fibroblasts (CAF). This phenotypic traits include the overexpression of growth factors, specific microRNAs profile, modification of extracellular matrix and basement membrane composition, increased cytokines and pro-angiogenic factors secretion, and a complex alteration of the Wnt/β-catenin pathway. Here, we review studies about the involvement of dermal fibroblasts in BCC predisposition of Gorlin syndrome patients. Further, we matched the emerged NBCCS fibroblast profile to those of CAF to compare the impact of cell autonomous “pre-activated state” due to PTCH1 mutations to those of skin tumor stroma.

Cutaneous neoplasms composed of melanoma and carcinoma: A rare but important diagnostic pitfall and review of the literature

We report two cases of combined cutaneous tumors composed of melanoma and carcinoma. The first tumor presented as a 5-mm pink-blue macule over the right zygomatic arch in an 85-year-old man. Shave biopsy and immunohistochemical studies revealed that the tumor was composed of melanoma (highlighted by SOX10 and MART-1, with high Ki-67 proliferative index) intermixed with nodular basal cell carcinoma (highlighted by pan-cytokeratin and Ber-EP4). The neoplastic melanocytes were confined to the basal cell carcinoma nodules, and a diagnosis of combined melanoma in situ and basal cell carcinoma was rendered. After therapeutic excision, the patient was disease-free at 9 months after the initial diagnosis. The second tumor presented as a 6-mm pink-brown crusted papule on the right forehead in an 89-year-old man. Shave biopsy and immunohistochemical studies revealed that the tumor was composed of malignant melanoma (MM) (highlighted by S100 and MART-1) intermixed with squamous cell carcinoma (SCC) (highlighted by cytokeratin and p63), and a diagnosis of combined MM-SCC was rendered. These two cases highlight the importance of recognizing these rare types of melanocytic-epithelial cutaneous neoplasms to arrive at an accurate diagnosis that may inform appropriate disease stage and therapy.

The Role of Stem Cell Factor in Hyperpigmented Skin Lesions

BACKGROUND

Skin hyperpigmentation usually results from an increased number, or activity, of melanocytes. The degree of pigmentation of skin depends on the amount and type of melanin, degree of skin vascularity, presence of carotene, and thickness of the stratum corneum. Common causes of hyperpigmentation include post-inflammatory hyperpigmentation, melasma, solar lentigines, ephelides (freckles), and café-au-lait macules. Some skin tumors can be hyperpigmented as basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and malignant melanoma (MM). Stem cell factor (SCF) is a growth factor and its interaction with its receptor, c-kit, is well known to be critical to the survival of melanocytes.

METHODS

This study was carried out on 60 patients complaining of hyperpigmented skin lesions (20 melasma, 20 solar lentigines, and 20 freckles) and 36 patients with skin tumors (14 BCC, 12 SCC, and 10 MM). Punch skin biopsies were taken from the previous lesions. Immunohistochemical staining of these samples was done using the stem cell factor (SCF).

RESULTS

There was positive expression of SCF in all cases of melasma, solar lentigines and freckles with significant increase in the intensity of expression in the lesional areas than the non-lesional ones (P=0.004). There was also a statistically significant increase in the expression of SCF in BCC and melanoma tumor cells.

CONCLUSION

SCF has a great role in skin hyperpigmented disorders and this can be used as a target for the developing of new antipigmentary lines of treatment by inhibiting SCF. SCF can also be involved in the emergence of some skin tumors.

p63 Is a Promising Marker in the Diagnosis of Unusual Skin Cancer

Skin cancer is the most common type of cancer worldwide. Ozone depletion and climate changes might cause a further increase in the incidence rate in the future. Although the early detection of skin cancer enables it to be treated successfully, some tumours can evolve and become more aggressive, especially in the case of melanoma. Therefore, good diagnostic and prognostic markers are needed to ensure correct detection and treatment. Transcription factor p63, a member of the p53 family of proteins, plays an essential role in the development of stratified epithelia such as skin. In this paper, we conduct a comprehensive review of p63 expression in different types of skin cancer and discuss its possible use in the diagnosis and prognosis of cutaneous tumours.

CENPV Is a CYLD-Interacting Molecule Regulating Ciliary Acetylated α-Tubulin

CYLD is a deubiquitylase with tumor suppressor functions, first identified in patients with familial cylindromatosis. Despite many molecular mechanisms in which a function of CYLD was reported, affected patients only develop skin appendage tumors, and their precise pathogenesis remains enigmatic. To elucidate how CYLD contributes to tumor formation, we aimed to identify molecular partners in keratinocytes. By using yeast two-hybrid, coprecipitation, and proximity ligation experiments, we identified CENPV as a CYLD-interacting partner. CENPV, a constituent of mitotic chromosomes associating with cytoplasmic microtubules, interacts with CYLD through the region between the third cytoskeleton-associated protein-glycine domain and the active site. CENPV is deubiquitylated by CYLD and localizes in interphase to primary cilia where it increases the ciliary levels of acetylated α-tubulin. CENPV is overexpressed in basal cell carcinoma. Our results support the notion that centromeric proteins have functions in ciliogenesis.

Matrical carcinoma with melanocytic hyperplasia mimicking nodular melanoma in an elderly Mexican male

Matrical carcinoma with melanocytic hyperplasia (MCMH), previously referred to as malignant melanocytic matricoma, is a rare variant of the uncommon pilomatrical carcinoma, occurring most often on the head/neck and upper backs of middle-aged men. Nodular lesions may resemble pigmented basal cell carcinoma or melanoma clinically. We present a case of MCMH in a Hispanic patient with history of melanoma. Histopathological clues to appropriate diagnosis include basaloid cells, numerous atypical mitotic figures, matrical differentiation, shadow cells, strong diffuse nuclear and cytoplasmic expression of ß-catenin, and interspersed pigmented dendritic melanocytes.

A Practical Guide for the Follow-Up of Patients with Advanced Basal Cell Carcinoma During Treatment with Hedgehog Pathway Inhibitors

The Hedgehog pathway inhibitors (HPIs), vismodegib and sonidegib, are increasingly employed in the treatment of patients with advanced basal cell carcinoma (BCC). The aim of this review is to create a synthesis of available information in the literature regarding the follow-up of patients with advanced BCC treated with HPIs and to provide the treating physician with a structured practical guide to standardize clinical practice. Several challenges during treatment are addressed: to optimally evaluate tumor responses, to differentiate between resistance (HPI rechallenge not possible) and recurrence (HPI rechallenge may be possible) in case of BCC regrowth, to readily assess for toxicity and tolerability issues, to provide patients with practical ways and behaviors to effectively cope with adverse events, and to improve patient adherence and quality of life. IMPLICATIONS FOR PRACTICE: This is a practical guide for clinical practice regarding the monitoring and follow-up of patients with advanced basal cell carcinoma (BCC) during treatment with the Hedgehog pathway inhibitors (HPIs) vismodegib and sonidegib. This review aims to bridge the gap in knowledge of assessing tumor response for BCC with both an externally visible component and an infiltrating component measurable with imaging. Furthermore, it addresses the follow-up for adverse events as a challenging multistep process involving practices aiming to readily assess new-onset symptoms of HPI toxicity, perform total-body skin examination, and improve patient adherence and quality of life.

Slide-free imaging of hematoxylin-eosin stained whole-mount tissues using combined third-harmonic generation and three-photon fluorescence microscopy

Intraoperative margin assessment of surgical tissues during cancer surgery is clinically important, especially in the case of tissue conserving surgery like Mohs micrographic surgery in which minimization of the surgical area is considered crucial. Frozen pathology is the gold standard of assessing excised tissues for signs of remaining cancerous lesions. The current protocol, however, is time-consuming and labor-intensive. Instead of the complex frozen sectioning, staining, and traditional white light microscopy imaging protocol, optically sectioned histopathological imaging of hematoxylin-eosin stained whole-mount skin tissues with a subfemtoliter resolution is demonstrated by using nonlinear microscopy in this study. With our proposed method, the reagents of staining and the contrast of imaging are fully consistent with the current clinical standard of frozen pathology, thus facilitating rapid intraoperative assessment of surgical tissues for future applications. Image: Slide-free nonlinear microscopy imaging of H&E stained whole-mount skin tissue showing the morphology of sweat glands.

N-Glycosylation in progression of skin cancer

Skin cancer can be classified as cutaneous malignant melanoma, basal cell carcinoma, and squamous cell carcinoma. Due to the high level of morbidity and mortality, skin cancer has become a global public health issue worldwide while the pathogenesis of skin cancer is still unclear. It is necessary to further identify the pathogenesis of skin cancer and find candidate targets to diagnose and treat skin cancer. A variety of factors are known to be associated with skin cancer including N-glycosylation, which partly explained the malignant behaviors of skin cancer. In this review, we retrieved databases such as PubMed and Web of Science to elucidate its relationship between glycosylation and skin cancer. We summarized some key glycosyltransferases and proteins during the process of N-glycosylation related to skin cancer, which was helpful to unmask the additional mechanism of skin cancer and find some novel targets of skin cancer.

Keratinocyte Carcinomas: Current Concepts and Future Research Priorities

Cutaneous squamous cell carcinoma (cSCC) and basal cell carcinoma (BCC) are keratinocyte carcinomas, the most frequently diagnosed cancers in fair-skinned populations. Ultraviolet radiation (UVR) is the main driving carcinogen for these tumors, but immunosuppression, pigmentary factors, and aging are also risk factors. Scientific discoveries have improved the understanding of the role of human papillomaviruses (HPV) in cSCC as well as the skin microbiome and a compromised immune system in the development of both cSCC and BCC. Genomic analyses have uncovered genetic risk variants, high-risk susceptibility genes, and somatic events that underlie common pathways important in keratinocyte carcinoma tumorigenesis and tumor characteristics that have enabled development of prediction models for early identification of high-risk individuals. Advances in chemoprevention in high-risk individuals and progress in targeted and immune-based treatment approaches have the potential to decrease the morbidity and mortality associated with these tumors. As the incidence and prevalence of keratinocyte carcinoma continue to increase, strategies for prevention, including effective sun-protective behavior, educational interventions, and reduction of tanning bed access and usage, are essential. Gaps in our knowledge requiring additional research to reduce the high morbidity and costs associated with keratinocyte carcinoma include better understanding of factors leading to more aggressive tumors, the roles of microbiome and HPV infection, prediction of response to therapies including immune checkpoint blockade, and how to tailor both prevention and treatment to individual risk factors and needs.

Common skin bacteria protect their host from oxidative stress through secreted antioxidant RoxP

Cutibacterium acnes is an abundant skin commensal with several proposed mutualistic functions. A protein with strong antioxidant activity was recently identified from the C. acnes secretome. This protein, termed RoxP, facilitated aerobic bacterial growth in vitro and ex vivo. As reducing events naturally occurred outside of the bacterial cell, it was further hypothesized that RoxP could also serve to modulate redox status of human skin. The biological function of RoxP was here assessed in vitro and in vivo, through oxidatively stressed cell cultures and through protein quantification from skin affected by oxidative disease (actinic keratosis and basal cell carcinoma), respectively. 16S rDNA amplicon deep sequencing and single locus sequence typing was used to correlate bacterial prevalence to cutaneous RoxP abundances. We show that RoxP positively influence the viability of monocytes and keratinocytes exposed to oxidative stress, and that a congruent concentration decline of RoxP can be observed in skin affected by oxidative disease. Basal cell carcinoma was moreover associated with microbial dysbiosis, characterized by reduced C. acnes prevalence. C. acnes's secretion of RoxP, an exogenous but naturally occurring antioxidant on human skin, is likely to positively influence the human host. Results furthermore attest to its prospective usability as a biopharmaceutical.

Loss of Primary Cilia Drives Switching from Hedgehog to Ras/MAPK Pathway in Resistant Basal Cell Carcinoma

Basal cell carcinomas (BCCs) rely on Hedgehog (HH) pathway growth signal amplification by the microtubule-based organelle, the primary cilium. Despite naive tumor responsiveness to Smoothened inhibitors (Smoⁱ), resistance in advanced tumors remains common. Although the resistant BCCs usually maintain HH pathway activation, squamous cell carcinomas with Ras/MAPK pathway activation also arise, and the molecular basis of tumor type and pathway selection are still obscure. Here, we identify the primary cilium as a critical determinant controlling tumor pathway switching. Strikingly, Smoothened inhibitor-resistant BCCs have an increased mutational load in ciliome genes, resulting in reduced primary cilia and HH pathway activation compared with naive or Gorlin syndrome patient BCCs. Gene set enrichment analysis of resistant BCCs with a low HH pathway signature showed increased Ras/MAPK pathway activation. Tissue analysis confirmed an inverse relationship between primary cilia presence and Ras/MAPK activation, and primary cilia removal in BCCs potentiated Ras/MAPK pathway activation. Moreover, activating Ras in HH-responsive cell lines conferred resistance to both canonical (vismodegib) and noncanonical (atypical protein kinase C and MRTF inhibitors) HH pathway inhibitors and conferred sensitivity to MAPK inhibitors. Our results provide insights into BCC treatment and identify the primary cilium as an important lineage gatekeeper, preventing HH-to-Ras/MAPK pathway switching.

LAP2 Proteins Chaperone GLI1 Movement between the Lamina and Chromatin to Regulate Transcription

Understanding transcription factor navigation through the nucleus remains critical for developing targeted therapeutics. The GLI1 transcription factor must maintain maximal Hedgehog pathway output in basal cell carcinomas (BCCs), and we have previously shown that resistant BCCs increase GLI1 deacetylation through atypical protein kinase Cι/λ (aPKC) and HDAC1. Here we identify a lamina-associated polypeptide 2 (LAP2) isoform-dependent nuclear chaperoning system that regulates GLI1 movement between the nuclear lamina and nucleoplasm to achieve maximal activation. LAP2β forms a two-site interaction with the GLI1 zinc-finger domain and acetylation site, stabilizing an acetylation-dependent reserve on the inner nuclear membrane (INM). By contrast, the nucleoplasmic LAP2α competes with LAP2β for GLI1 while scaffolding HDAC1 to deacetylate the secondary binding site. aPKC functions to promote GLI1 association with LAP2α, promoting egress off the INM. GLI1 intranuclear trafficking by LAP2 isoforms represents a powerful signal amplifier in BCCs with implications for zinc finger-based signal transduction and therapeutics.