Expression profiling of cutaneous squamous cell carcinoma with perineural invasion implicates the p53 pathway in the process

Gene expression landscape of cutaneous squamous cell carcinoma progression

BACKGROUND

Cutaneous squamous cell carcinomas (cSCCs) are the second most common human cancer and have been characterized by RNA sequencing (RNA-Seq); however, the transferability of findings from individual studies may be limited by small sample sizes and diverse analysis protocols.

OBJECTIVES

To define the transcriptome landscape at different stages in the progression of normal skin to cSCC via a meta-analysis of publicly available RNA-Seq samples.

METHODS

Whole-transcriptome data from 73 clinically normal skin samples, 46 actinic keratoses (AK) samples, 16 in situ SCC samples, 13 keratoacanthoma (KA) samples and 147 cSCC samples [including 30 samples from immunocompromised patients and 8 from individuals with recessive dystrophic epidermolysis bullosa (RDEB)] were uniformly processed to harmonize gene expression. Differential expression, fusion detection and cell-type deconvolution analyses were performed.

RESULTS

Individual RNA-Seq studies of cSCC demonstrated study-specific clustering and varied widely in their differential gene expression detection. Following batch correction, we defined a consensus set of differentially expressed genes (DEGs), including those altered in the preinvasive stages of cSCC development, and used single-cell RNA-Seq data to demonstrate that DEGs are often - but not always - expressed by tumour-specific keratinocytes (TSKs). Analysis of the cellular composition of cSCC, KA and RDEB-cSCC identified an increase in differentiated keratinocytes in KA, while RDEB-cSCC contained the most TSKs. Compared with cSCC arising in immunocompetent individuals, cSCC samples from immunosuppressed patients demonstrated fewer memory B cells and CD8+ T cells. A comprehensive and unbiased search for fusion transcripts in cSCC and intermediate disease stages identified few candidates that recurred in >1% of all specimens, suggesting that most cSCC are not driven by oncogenic gene fusions. Finally, using Genotype-Tissue Expression (GTEx) data, we distilled a novel 300-gene signature of chronic sun exposure that affirms greater cumulative ultraviolet (UV) exposure in later stages of cSCC development.

CONCLUSIONS

Our results define the gene expression landscape of cSCC progression, characterize cell subpopulation heterogeneity in cSCC subtypes that contribute to their distinct clinical phenotypes, demonstrate that gene fusions are not a common cause of cSCC and identify UV-responsive genes associated with cSCC development.

Management Approaches for High-Risk Cutaneous Squamous Cell Carcinoma with Perineural Invasion: An Updated Review

OPINION STATEMENT

Cutaneous squamous cell carcinoma (cSCC) stands as the second most prevalent non-melanoma skin cancer worldwide, comprising approximately 20% of all cutaneous malignancies. Determining its precise incidence poses challenges; however, reports indicate a global increase in its prevalence. At the time of diagnosis, the majority of cSCCs are localized, resulting in favorable 5-year cure rates surpassing 90%. Nevertheless, a subset of patients (3-7%) encounters locally advanced or metastatic cSCC, leading to substantial morbidity and mortality. The risk of metastasis ranges from 0.1% to 9.9%, carrying an associated mortality risk of 2.8%. Factors influencing recurrence, metastasis, and disease-specific mortality underscore the significance of perineural invasion (PNI) as a key indicator. Patients with PNI may manifest clinical symptoms and/or radiologic signs of PNI, while the majority remain asymptomatic, and PNI is frequently identified upon histologic examination. Despite its lower frequency compared to other cancer types, PNI serves as a recognized adverse prognostic factor for cSCC. Surgery is the elective treatment for these patients, while the role of adjuvant radiotherapy (ART) is yet contentious and have not been conclusively assessed, particularly in clear surgical margin. Prospective comparative studies are required to comprehensively evaluate the benefit and the risks of ART for cSCC and PNI patients.

Development of an in vivo murine model of perineural invasion and spread of cutaneous squamous cell carcinoma of the head and neck

Introduction

Cutaneous squamous cell carcinoma of the head and neck (cSCCHN) can metastasize by invading nerves and spread toward the central nervous system. This metastatic process is called perineural invasion (PNI) and spread (PNS). An in vivo sciatic nerve mouse model is used for cSCCHN PNI/PNS. Here we describe a complementary whisker pad model which allows for molecular studies investigating drivers of PNI/PNS in the head and neck environment.

Methods

A431 cells were injected into the whisker pads of BALB/c Foxn1nu and NSG-A2 mice. Tumor progression was monitored by bioluminescence imaging and primary tumor resection was performed. PNI was detected by H&E and IHC. Tumor growth and PNI were assessed with inducible ablation of LOXL2.

Results

The rate of PNI development in mice was 10%-28.6%. Tumors exhibited PNI/PNS reminiscent of the morphology seen in the human disease. Our model's utility was demonstrated with inducible ablation of LOXL2 reducing primary tumor growth and PNI.

Discussion

This model consists in a feasible way to test molecular characteristics and potential therapies, offers to close a gap in the described in vivo methods for PNI/PNS of cSCCHN and has uses in concert with the established sciatic nerve model.

Dysregulation of core neurodevelopmental pathways-a common feature of cancers with perineural invasion

Background: High nerve density in tumors and metastasis via nerves (perineural invasion-PNI) have been reported extensively in solid tumors throughout the body including pancreatic, head and neck, gastric, prostate, breast, and colorectal cancers. Ablation of tumor nerves results in improved disease outcomes, suggesting that blocking nerve-tumor communication could be a novel treatment strategy. However, the molecular mechanisms underlying this remain poorly understood. Thus, the aim here was to identify molecular pathways underlying nerve-tumor crosstalk and to determine common molecular features between PNI-associated cancers. Results: Analysis of head and neck (HNSCC), pancreatic, and gastric (STAD) cancer Gene Expression Omnibus datasets was used to identify differentially expressed genes (DEGs). This revealed extracellular matrix components as highly dysregulated. To enrich for pathways associated with PNI, genes previously correlated with PNI in STAD and in 2 HNSCC studies where tumor samples were segregated by PNI status were analyzed. Neurodevelopmental genes were found to be enriched with PNI. In datasets where tumor samples were not segregated by PNI, neurodevelopmental pathways accounted for 12%-16% of the DEGs. Further dysregulation of axon guidance genes was common to all cancers analyzed. By examining paralog genes, a clear pattern emerged where at least one family member from several axon guidance pathways was affected in all cancers examined. Overall 17 different axon guidance gene families were disrupted, including the ephrin-Eph, semaphorin-neuropilin/plexin, and slit-robo pathways. These findings were validated using The Cancer Genome Atlas and cross-referenced to other cancers with a high incidence of PNI including colon, cholangiocarcinoma, prostate, and breast cancers. Survival analysis revealed that the expression levels of neurodevelopmental gene families impacted disease survival. Conclusion: These data highlight the importance of the tumor as a source of signals for neural tropism and neural plasticity as a common feature of cancer. The analysis supports the hypothesis that dysregulation of neurodevelopmental programs is a common feature associated with PNI. Furthermore, the data suggested that different cancers may have evolved to employ alternative genetic strategies to disrupt the same pathways. Overall, these findings provide potential druggable targets for novel therapies of cancer management and provide multi-cancer molecular biomarkers.

Real-world Evidence Shows Clinicians Appropriately Use the Prognostic 40-gene Expression Profile (40-GEP) Test for High-risk Cutaneous Squamous Cell Carcinoma (cSCC) Patients

Treatment decisions for patients with cutaneous squamous cell carcinoma (cSCC) are traditionally based upon clinicopathologic risk factors and staging systems. Due to the accuracy limitations of these resources in predicting poor outcomes, there is a clinically significant need for more accurate methods of risk assessment. The 40-gene expression profile (40-GEP) test was developed to augment metastatic risk prediction of high-risk cSCC patients and has been validated in two independent, multi-center studies involving over 1,000 patients. This study substantiates that the 40-GEP is appropriately utilized by clinicians and that the personalized risk-stratification results are impactful in guiding risk-aligned patient management.

Immunotherapy for the treatment of perineural spread in cutaneous head and neck squamous cell carcinoma: Time to rethink treatment paradigms

BACKGROUND

Immune checkpoint inhibitors have shown promising antitumour activity. Application in head and neck cutaneous squamous cell carcinoma (cSCC) large nerve perineural spread (PNS) is limited.

METHODS

Retrospective review of 13 patients with PNS receiving anti-PD-1 therapy from September 2017 to May 2021 is presented. Primary endpoints were objective response (complete or partial response) and median time to progression, determined by Head and Neck Multi-Disciplinary Team (MDT) and independent radiology review of magnetic resonance imaging (MRI) and/or computed tomography/positron emission tomography (CT/PET).

RESULTS

Objective response was observed in 9/13 patients (69%), with complete response in 6 (46%) and partial response in 3 patients (23%). Median time to response was 2.1 months (IQR 1.8-2.7 months). There were 3 (23%) patients with progressive disease, with median time to progression of 3.5 months. There were no grade 3-4 treatment related adverse events.

CONCLUSIONS

This case series supports developing evidence for anti-PD-1 checkpoint inhibitor therapy for perineural spread, supporting future prospective clinical trials in this patient population.

Current Methods and Caveats to Risk Factor Assessment in Cutaneous Squamous Cell Carcinoma (cSCC): A Narrative Review

Cutaneous squamous cell carcinoma (cSCC) is the second most common form of skin cancer, and the number of deaths due to cSCC is estimated to be greater than the number attributed to melanoma. While the majority of cSCC tumors are resectable with clear margins by standard excision practices, some lesions exhibit high-risk factors for which there is evidence of their association with recurrence, metastasis, and disease-specific death. The most commonly used staging systems and guidelines in the USA for cSCC are based on these clinical and pathologic high-risk factors; however, these are limited in their ability to predict adverse events, thus posing a challenge for implementing risk-directed patient management. Since the development of local recurrence and/or metastasis has a profound impact on the survival of patients with cSCC, accurate identification of patients at high risk for poor outcomes is critical, potentially allowing for early and appropriate adjuvant therapy. This review summarizes the current cSCC literature with a focus on how differing clinical assessments within each of the five selected risk factors (perineural invasion, differentiation, depth of invasion, size, and location) can influence the evaluation of patient outcomes, along with summarizing the utility of staging and guidelines, and highlighting the potential for molecular tools to improve upon cSCC risk assessment.

Gene expression profiling of perineural invasion in head and neck cutaneous squamous cell carcinoma

Perineural invasion (PNI) is frequently associated with aggressive clinical behaviour in head and neck cutaneous squamous cell carcinoma (HNcSCC) leading to local recurrence and treatment failure. This study evaluates the gene expression profiles of HNcSCC with PNI using a differential expression analysis approach and constructs a tailored gene panel for sensitivity and specificity analysis. 45 cases of HNcSCC were stratified into three groups (Extensive, Focal and Non PNI) based on predefined clinicopathological criteria. Here we show HNcSCC with extensive PNI demonstrates significant up- and down-regulation of 144 genes associated with extracellular matrix interactions, epithelial to mesenchymal transition, cell adhesion, cellular motility, angiogenesis, and cellular differentiation. Gene expression of focal and non PNI cohorts were indistinguishable and were combined for further analyses. There is clinicopathological correlation between gene expression analysis findings and disease behaviour and a tailored panel of 10 genes was able to identify extensive PNI with 96% sensitivity and 95% specificity.

Functional genomic analysis identifies drug targetable pathways in invasive and metastatic cutaneous squamous cell carcinoma

Although cutaneous squamous cell carcinoma (cSCC) is treatable in the majority of cases, deadly invasive and metastatic cases do occur. To date there are neither reliable predictive biomarkers of disease progression nor FDA-approved targeted therapies as standard of care. To address these issues, we screened patient-derived primary cultured cells from invasive/metastatic cSCC with 107 small-molecule inhibitors. In-house bioinformatics tools were used to cross-analyze drug responses and DNA mutations in tumors detected by whole-exome sequencing (WES). Aberrations in molecular pathways with evidence of potential drug targets were identified, including the Eph-ephrin and neutrophil degranulation signaling pathways. Using a screening panel of siRNAs, we identified EPHA6 and EPHA7 as targets within the Eph-ephrin pathway responsible for mitigating decreased cell viability. These studies form a plausible foundation for detecting biomarkers of high-risk progressive disease applicable in dermatopathology and for patient-specific therapeutic options for invasive/metastatic cSCC.

Validation of a 40-gene expression profile test to predict metastatic risk in localized high-risk cutaneous squamous cell carcinoma

BACKGROUND

Current staging systems for cutaneous squamous cell carcinoma (cSCC) have limited positive predictive value for identifying patients who will experience metastasis.

OBJECTIVE

To develop and validate a gene expression profile (GEP) test for predicting risk for metastasis in localized, high-risk cSCC with the goal of improving risk-directed patient management.

METHODS

Archival formalin-fixed paraffin-embedded primary cSCC tissue and clinicopathologic data (n = 586) were collected from 23 independent centers in a prospectively designed study. A GEP signature was developed using a discovery cohort (n = 202) and validated in a separate, nonoverlapping, independent cohort (n = 324).

RESULTS

A prognostic 40-GEP test was developed and validated, stratifying patients with high-risk cSCC into classes based on metastasis risk: class 1 (low risk), class 2A (high risk), and class 2B (highest risk). For the validation cohort, 3-year metastasis-free survival rates were 91.4%, 80.6%, and 44.0%, respectively. A positive predictive value of 60% was achieved for the highest-risk group (class 2B), an improvement over staging systems, and negative predictive value, sensitivity, and specificity were comparable to staging systems.

LIMITATIONS

Potential understaging of cases could affect metastasis rate accuracy.

CONCLUSION

The 40-GEP test is an independent predictor of metastatic risk that can complement current staging systems for patients with high-risk cSCC.

Loss of Rab25 promotes the development of skin squamous cell carcinoma through the dysregulation of integrin trafficking

Rab25 can function as both a tumor suppressor and a tumor promoter across different tissues. This study sought to clarify the role of Rab25 as a tumor suppressor in skin squamous cell carcinoma (SCC). Rab25 loss was closely associated with neoplastic transition in both humans and mice. Rab25 loss was well correlated with increased cell proliferation and poor differentiation in human SCC. While Rab25 knockout (KO) in mice did not induce spontaneous tumor formation, it did significantly accelerate tumor generation and promote malignant transformation in a mouse two-stage skin carcinogenesis model. Xenografting of a Rab25-deficient human keratinocyte cell line, HaCaT, also elicited neoplastic transformation. Notably, Rab25 deficiency led to dysregulation of integrins β1, β4, and α6, which matched well with increased epidermal proliferation and impaired desmosome-tight junction formation. Rab25 deficiency induced impairment of integrin recycling, leading to the improper expression of integrins. In line with this, significant attenuation of integrin β1, β4, and α6 expression was identified in human SCCs where Rab25 was deficient. Collectively, these results suggest that loss of Rab25 promotes the development and neoplastic transition of SCC through dysregulation of integrin trafficking. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Antitumor Effect of Albendazole on Cutaneous Squamous Cell Carcinoma (SCC) Cells

Drug repurposing and/or repositioning is an alternative method to develop new treatment for certain diseases. Albendazole was originally developed as an anthelmintic medication, and it has been used to treat a variety of parasitic infestations. In this study, we investigated the antitumor effect of albendazole and putative action mechanism. Results showed that albendazole dramatically decreased the cell viability of SCC cell lines (SCC12 and SCC13 cells). Albendazole increased apoptosis-related signals, including cleaved caspase-3 and PARP-1 in a dose-dependent fashion. The mechanistic study showed that albendazole induced endoplasmic reticulum (ER) stress, evidenced by increase of CHOP, ATF-4, caspase-4, and caspase-12. Pretreatment with ER stress inhibitor 4-PBA attenuated albendazole-induced apoptosis of SCC cells. In addition, albendazole decreased the colony-forming ability of SCC cells, together with inhibition of Wnt/β-catenin signaling. These results indicate that albendazole shows an antitumor effect via regulation of ER stress and cancer stemness, suggesting that albendazole could be repositioned for cutaneous SCC treatment.

The prognostic value of inositol polyphosphate 5-phosphatase in cutaneous squamous cell carcinoma

BACKGROUND

Inositol polyphosphate 5-phosphatase (INPP5A) has been shown to play a role in development and progression of cutaneous squamous cell carcinoma (cSCC). The goal of the current study was to explore the prognostic value of INPP5A expression in cSCC.

METHODS

A total of 189 cases of actinic keratosis and SCC in 174 patients were identified; clinical and outcome data were abstracted, histopathology was rereviewed, and immunohistochemical staining and interpretation was performed for INPP5A.

RESULTS

The majority of tumors (89.4%) had an INPP5A score of 2 or 3. No patients had complete loss of INPP5A. Tumors with an INPP5A score of 1 were more likely to be intermediate- to high-risk tumors (Brigham and Women's Hospital stage ≥T2a 85.0% vs 23.7% [P < .0001]) characterized by a larger diameter (2.4 cm vs 1.3 cm [P = .0004]), moderate-to-poor differentiation (86.7% vs 17.6% [P < .0001]), and perineural invasion (37.5% vs 5.3%, [P < .0001]). An INPP5A score of 1 was associated with a worse 3-year survival (a rate of 42.3% [hazard ratio, 2.81, P = .0006]) and a local metastasis rate of 48.0% (hazard ratio, 4.71; P < .0001).

CONCLUSIONS

Low INPP5A scores are predictive of aggressive tumors and may be a useful adjunct to guide clinical management of cSCC.

Inhibitory effect of microRNA-154 targeting WHSC1 on cell proliferation of human skin squamous cell carcinoma through mediating the P53 signaling pathway

OBJECTIVE

Skin squamous cell carcinoma (SCC) is a common, morbid, and frequently lethal malignancy and ranks as the sixth most deadly cancer worldwide. Hence, this study aims to explore the effect of microRNA-154 (miR-154) targeting WHSC1 on proliferation and apoptosis of SCC cells via the P53 signaling pathway.

METHODS

The targeting relationship between WHSC1 and miR-154 was validated using dual-luciferase reporter assay. Normal human epidermal keratinocytes (NHEK) were included, and SCC A431 and SCC-15 cell lines were cultured and transfected with miR-154 mimic, miR-154 inhibitor or siRNA-WHSC1. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) and western blot analysis were used for the miR-154 expression and levels of WHSC1, P53 signaling pathway- and apoptosis-related genes. MTT assay and flow cytometry were applied to determine the cell viability and apoptosis.

RESULTS

WHSC1 is a target gene of miR-154. MiR-154 negatively regulated WHSC1 expression and inhibited the activation of P53 signaling pathway. In response to miR-154 mimic or siRNA-WHSC1, SCC A431 and SCC-15 cell lines exhibited increased expression of P73, P16 and Bax, decreased expression of WHSC1, P53, c-myc and Bcl-2, as well as attenuated cell viability and enhanced cell apoptosis. The treatment of miR-154 inhibitor reversed the tendency.

CONCLUSION

These results demonstrate that up-regulation of miR-154 inhibits proliferation and induces apoptosis of human skin SCC cells by down-regulating WHSC1 and blocking the P53 signaling pathway.

Expression profiling analysis of autophagy-related genes in perineural invasion of cutaneous squamous cell carcinoma

The aim of the present study was to identify the potential autophagy-related genes and to explore the underlying molecular mechanisms involved in cutaneous squamous cell carcinoma of head and neck (cSCCHN) by bioinformatics analysis. The Gene Expression Omnibus (GEO) series GSE86544 was downloaded from the GEO database. The primary data was generated from cSCCHN with clinical perineural invasion (PNI) and cSCCHN without PNI, and was further analyzed in order to identify differentially expressed genes (DEGs). The results revealed 239 autophagy-related DEGs. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed and intersected to investigate the predicted functions of the key DEGs, including hypoxia-inducible factor 1α (HIF1A), mitogen-activated protein kinase 8 (MAPK8), mammalian target of rapamycin (mTOR) and B-cell lymphoma 2 like 1 (BCL2L1). Up and downregulated genes shared one pathway, namely ‘pathways in cancer’. Next, the protein-protein interaction (PPI) network of the autophagy-related DEGs was constructed using Cytoscape 3.30 software. HIF1A, MAPK8, mTOR and BCL2L1 were key nodes in the PPI network. Additionally, RAB23 gene expression was positively correlated with HIF1A, MAPK8 and ADP ribosylation factor GTPase activating protein 1 (ARFGAP1), but negatively correlated with mTOR and BCL2L1. The present results suggested that the genes HIF1A, MAPK8, mTOR, BCL2L1 and RAB23 may be associated with and serve as potential therapeutic targets in cSCCHN with clinical PNI.

Effects of microRNA-374 on proliferation, migration, invasion, and apoptosis of human SCC cells by targeting Gadd45a through P53 signaling pathway

The present study investigated the effects of microRNA-374 (miR-374) on human squamous cell carcinoma (SCC) cell proliferation, migration, invasion, and apoptosis through P53 signaling pathway by targeting growth arrest and DNA-damage-inducible protein 45 α (Gadd45a). Skin samples were collected from patients with skin SCC and normal skin samples. Expression of miR-374, Gadd45a, P53, P73, P16, c-myc, bcl-2, Bax, caspase-3, and caspase-9 were detected using quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting. A431 and SCL-1 cells were divided into blank, negative control (NC), miR-374 mimics, miR374 inhibitors, siRNA–Gadd45a, and miR-374 inhibitors + siRNA–Gadd45a groups. Their proliferation, migration, invasion, cell cycle, and apoptosis were evaluated by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay, scratch test, Transwell assay, and flow cytometry. SCC skin tissues exhibited decreased expression of miR-374, P73, P16, Bax caspase-3 and caspase-9, and increased levels of Gadd45a, P53, c-myc, and Bcl-2 compared with the normal skin tissues. The miR-374 inhibitors group exhibited decreased expression of miR-374, P73, P16, Bax caspase-3 and caspase-9, and increased expression of Gadd45a, P53, c-myc, and Bcl-2, enhanced cell proliferation, migration, and invasion, and reduced apoptosis compared with the blank and NC groups; the miR-374 mimics group followed opposite trends. Compared with the blank and NC groups, the miR-374 inhibitors + siRNA–Gadd45a group showed decreased miR-374 level; the siRNA–Gadd45a group showed elevated levels of P73, P16, Bax, caspase-3 and caspase-9, decreased levels of Gadd45a, P53, c-myc, and Bcl-2, reduced cell proliferation, migration, and invasion, and accelerated apoptosis. miR-374 induces apoptosis and inhibits proliferation, migration, and invasion of SCC cells through P53 signaling pathway by down-regulating Gadd45a.