Molecular Mechanisms of Cutaneous Squamous Cell Carcinoma

Molecular mechanisms of human papilloma virus related skin cancers: A review

The human papillomavirus (HPV) belongs to the Papillomaviridae family of viruses which includes small, double-stranded DNA viral agents. Approximately 90% of HPV infections occur asymptomatically and resolve spontaneously. However, infection with high-risk viral strains can lead to the development of preneoplastic lesions, with an increased propensity to become cancerous. The location of these malignancies includes the oral cavity, cervix, vagina, anus, and vulva, among others. The role of HPV in carcinogenesis has already been demonstrated for the aforementioned neoplasia. However, regarding skin malignancies, the mechanisms that pinpoint the role played by HPV in their initiation and progression still elude our sight. Until now, the only fully understood mechanism of viral cutaneous oncogenesis is that of human herpes virus 8 infection in Kaposi sarcoma. In the case of HPV infection, however, most data focus on the role that beta strains exhibit in the oncogenesis of cutaneous squamous cell carcinoma (cSCC), along with ultraviolet radiation (UVR) and other environmental or genetic factors. However, recent epidemiological investigations have highlighted that HPV could also trigger the onset of other non-melanocytic, for example, basal cell carcinoma (BCC), and/or melanocytic skin cancers, for example, melanoma. Herein, we provide an overview of the role played by HPV in benign and malignant skin lesions with a particular focus on the main epidemiological, pathophysiological, and molecular aspects delineating the involvement of HPV in skin cancers.

Common skin cancers and their association with other non-cutaneous primary malignancies: a review of the literature

It has long been recognized that a history of skin cancer puts one at risk for additional primary skin cancers. However, more variable data exists for the risk of developing a non-cutaneous primary cancer following a diagnosis of skin cancer. The data are most variable for Basal Cell Carcinoma (BCC), the most common and least aggressive type of skin cancer. While early studies imply that BCC does not impart a larger risk of other primary non-cutaneous cancers, more recent studies with larger populations suggest otherwise. The cancers most significantly associated with BCC are lip, oropharyngeal, and salivary gland cancer. There is also burgeoning evidence to suggest a link between BCC and prostate, breast, and colorectal cancer, but more data are needed to draw a concrete conclusion. Squamous Cell Carcinoma (SCC), the second most common type of skin cancer, has a slightly more defined risk to other non-cutaneous primary malignancies. There is a notable link between SCC and non-Hodgkin's lymphoma (NHL), possibly due to immunosuppression. There is also an increased risk of other cancers derived from squamous epithelium following SCC, including oropharyngeal, lip, and salivary gland cancer. Some studies also suggest an increased risk of respiratory tract cancer following SCC, possibly due to shared risk factors. Melanoma, a more severe type of skin cancer, shows a well-defined risk of additional primary non-cutaneous malignancies. The most significant of these risks include NHL, thyroid cancer, prostate cancer, and breast cancer along with a host of other cancers. Each of these three main skin cancer types has a profile of genetic mutations that have also been linked to non-cutaneous malignancies. In this review, we discuss a selection of these genes to highlight the complex interplay between different tumorigenesis processes.

Incidence of Nonmelanoma Skin Cancers in Alberta, Canada, From 2007 to 2018

BACKGROUND

Nonmelanoma skin cancer (NMSC) is the most common malignancy affecting Caucasian populations and has been seeing steady increases in incidence globally for decades. Our previous study (from Alberta, Canada) had shown a plateau in the incidence rates for NMSC. This contrasts with data from other regions within Canada and throughout the world that indicated a continued increase in incidence rates of NMSCs.

OBJECTIVES

The objective of this study was to provide an update on the trends in incidence of NMSC in Alberta, Canada, from 2007 to 2018.

METHODS

A retrospective analysis of patients from Alberta diagnosed with NMSC from 2007 to 2018 inclusive was conducted with data retrieved from Alberta Cancer Registry. Sex-, age-, anatomical location-, NMSC subtype-, stage-specific incidence rates and trends were examined.

RESULTS

From 2007 to 2018, overall incidence rates of NMSC increased by 36%. Invasive squamous cell carcinoma (SCC) and in situ SCC demonstrated the most significant increase, invasive SCC [annual percentage change (APC) 3.48, P = .014] and in situ SCC (APC 5.61, P = .0001). In addition, we were able to determine that females had the most significant increases in NMSC incidence rates from 2007 to 2018 particularly invasive SCC (APC 3.03, P = <.0001) and in situ SCC (APC 5.08, P = <.0001).

CONCLUSIONS

After initial levelling of NMSC incidence in Alberta in the early part of 21st century, the incidence of NMSC continues to increase over the past decade. The reasons for this change are not clear and likely multifactorial.

E3 Ubiquitin Ligase NEDD4L Negatively Regulates Skin Tumorigenesis by Inhibiting IL-6/GP130 Signaling Pathway

IL-6 signaling plays a crucial role in the survival and metastasis of skin cancer. NEDD4L acts as a suppressor of IL-6 signaling by targeting GP130 degradation. However, the effects of the NEDD4L-regulated IL-6/GP130 signaling pathway on skin cancer remain unclear. In this study, protein expression levels of NEDD4L and GP130 were measured in tumor tissues from patients with cutaneous squamous cell carcinoma. Skin tumors were induced in wild-type and Nedd4l-knockout mice, and activation of the IL-6/GP130/signal transducer and activator of transcription 3 signaling pathway was detected. The results indicated a negative correlation between the protein expression levels of NEDD4L and GP130 in cutaneous squamous cell carcinoma tissues from patients. Nedd4l deficiency significantly promoted 7,12-dimethylbenz[a]anthracene/12-O-tetradecanoylphorbol-13-acetate-induced skin tumorigenesis and benign-to-malignant conversion by activating the IL-6/GP130/signal transducer and activator of transcription 3 signaling pathway, which was abrogated by supplementation with the GP130 inhibitor SC144. Furthermore, our findings suggested that NEDD4L can interact with GP130 and promote its ubiquitination in skin tumors. In conclusion, our results indicate that NEDD4L could act as a tumor suppressor in skin cancer, and inhibition of GP130 could be a potential therapeutic method for treating this disease.

METTL3-mediated HPV vaccine enhances the effect of anti PD-1 immunotherapy to alleviate the development of cutaneous squamous cell carcinoma

BACKGROUND

Cutaneous squamous cell carcinoma (cSCC) develops from epithelial keratinocytes by dysregulation of self-renewal and differentiation. Recent studies have found that the size and number of cSCC tumors gradually decrease or even disappear after HPV vaccination. However, the role of the HPV vaccine in the cSCC mechanism is poorly understood.

OBJECTIVE

The aim of this study is to investigate the effect and mechanism of the HPV vaccine in cSCC.

METHODS

Immunofluorescence was used to study the immune infiltrating cells in the tumor tissues of patients with cSCC. The effects of the HPV vaccine on cSCC cells and tissues were studied by Cell Culture, Real-time PCR, Western Blot, Cytotoxicity Assay, Enzyme-linked Immunosorbent Assay, m6A Blotting, CCK-8 Assay, m6A Ribonucleic acid Methylation Quantification and tumor transplantation.

RESULTS

The HPV vaccine enhanced the toxic effect of CD8+T cells on cSCC cells and promoted the secretion of multiple cytokines by CD8+T cells. In addition, HPV vaccines can increase tumor sensitivity to anti-PD-1 therapy by downregulating METTL3 in tumor tissue, with the combination of HPV vaccine and PD-1 monoclonal antibodies producing enhanced immune cell infiltration compared to PD-1 blockade alone.

STUDY LIMITATIONS

It is important to note the limitations of this study, including the small sample size, the construction of the mouse model, and the choice of HPV vaccine and PD-1 monoclonal antibody, which may limit the generalization of our findings to a wider population.

CONCLUSIONS

It is hoped that this research will contribute to a deeper understanding of the role of the HPV vaccine in the treatment of cSCC. HPV vaccine is expected to become an important approach to alleviate the development of cSCC.

Pathophysiology, Histopathology, and Differential Diagnostics of Basal Cell Carcinoma and Cutaneous Squamous Cell Carcinoma-An Update from the Pathologist's Point of View

Basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (cSCC) are the most frequently occurring non-melanocytic skin cancers. The objective of our study is to present the pathophysiology of BCC and cSCC and its direct relationship with the histopathological diagnostics and the differential diagnostics of these types of cancer, based on the morphological characteristics, immunohistochemical profile, and genetic alterations. The qualitative study was based on emphasizing the morphological characteristics and immunohistochemistry profiles of BCC and cSCC and the differential diagnostics based on the tissue samples from the Clinical Pathology Department of Mures Clinical County Hospital between 2020 and 2022. We analyzed the histopathological appearances and immunohistochemical profiles of BCC and cSCC in comparison with those of Bowen disease, keratoacanthoma, hyperkeratotic squamous papilloma, metatypical carcinoma, pilomatricoma, trichoblastoma, Merkel cell carcinoma, pleomorphic dermal sarcoma (PDS), and melanoma. Our study showed the importance of the correct histopathological diagnosis, which has a direct impact on the appropriate treatment and outcome for each patient. The study highlighted the histopathological and morphological characteristics of NMSCs and the precursor lesions in HE and the immunohistochemical profile for lesions that may make the differential diagnosis difficult to establish.

Inducible Keratinocyte Specific FGFR2 Deficiency Inhibits UVB-Induced Signaling, Proliferation, Inflammation, and Skin Carcinogenesis

A potential role for fibroblast growth factor receptor 2 (FGFR2) in cutaneous squamous cell carcinoma (cSCC) has been reported. To demonstrate the specific role of FGFR2 in UVB-induced skin carcinogenesis and development of cSCC, we generated a keratinocyte specific, tamoxifen inducible mouse model of FGFR2 deficiency. In this mouse model, topical application of 4-hydroxy tamoxifen led to the induction of Cre recombinase to delete FGFR2 in epidermal keratinocytes of both male and female transgenic mice. Analysis of epidermal protein lysates isolated from FGFR2 deficient mice exposed to UVB showed significant reductions of phospho-FGFR (pFGFR; Y653/654) and phospho-fibroblast growth factor receptor substrate 2α as well as downstream effectors of mTORC1 signaling. Phosphorylation of signal transducer and activators of transcription 1/3 was significantly reduced as well as levels of IRF-1, DUSP6, early growth response 1, and PD-L1 compared to the control groups. Keratinocyte-specific ablation of FGFR2 also significantly inhibited epidermal hyperproliferation, hyperplasia, and inflammation after exposure to UVB. Finally, keratinocyte-specific deletion of FGFR2 significantly inhibited UVB-induced cSCC formation. Collectively, the current data demonstrate an important role of FGFR2 in UVB-induced oncogenic signaling as well as development of cSCC. In addition, the current preclinical findings suggest that inhibition of FGFR2 signaling may provide a previously unreported strategy to prevent and/or treat UVB-induced cSCC.

PIK Your Poison: The Effects of Combining PI3K and CDK Inhibitors against Metastatic Cutaneous Squamous Cell Carcinoma In Vitro

Cutaneous squamous cell carcinoma (cSCC) is a very common skin malignancy with poor prognosis for patients with locally advanced or metastatic cSCC (mcSCC). PI3K/AKT/mTOR and cell cycle signalling pathways are often dysregulated in mcSCC. A combination drug approach has been theorised to overcome the underwhelming clinical performance of targeted inhibitors as single agents. This study investigates the potential of targeted inhibition of the p110α-subunit of PI3K with PIK-75 or BGT226 (P13Ki), and of CDK1/2/5/9 with dinaciclib (CDKi) as single agents and in combination. The patient-derived mcSCC cell lines, UW-CSCC1 and UW-CSCC2, were used to assess cell viability, migration, cell signalling, cell cycle distribution, and apoptosis. PIK-75, BGT226, and dinaciclib exhibited strong cytotoxic potency as single agents. Notably, the non-malignant HaCaT cell line was unaffected. In 2D cultures, PIK-75 synergistically enhanced the cytotoxic effects of dinaciclib in UW-CSCC2, but not UW-CSCC1. Interestingly, this pattern was reversed in 3D spheroid models. Despite the combination of PIK-75 and dinaciclib resulting in an increase in cell cycle arrest and apoptosis, and reduced cell motility, these differences were largely negligible compared to their single-agent counterpart. The differential responses between the cell lines correlated with driver gene mutation profiles. These findings suggest that personalised medicine approaches targeting PI3K and CDK pathways in combination may yield some benefit for mcSCC, and that more complex 3D models should be considered for drug responsiveness studies in this disease.

Squamous carcinogenesis: potential truncal mutations

Squamous carcinogenesis is incompletely understood, but more recent genetic studies support that the order of acquired mutations is important. This paper will review more recent genetic studies with an emphasis on the potential truncal mutations, mutations critical to the trunk of the cancer evolutionary tree, in actinic keratosis, squamous cell carcinoma in situ, cutaneous squamous cell carcinoma, keratoacanthoma, and keratoacanthoma-like squamous proliferation.

Somatic mutations reveal hyperactive Notch signaling and racial disparities in prurigo nodularis

Prurigo nodularis (PN) is a chronic inflammatory skin disease that disproportionately affects African Americans and is characterized by pruritic skin nodules of unknown etiology. Little is known about genetic alterations in PN pathogenesis, especially relating to somatic events which are often implicated in inflammatory conditions. We thus performed whole-exome sequencing on 54 lesional and nonlesional skin biopsies from 17 PN patients and 10 atopic dermatitis (AD) patients for comparison. Somatic mutational analysis revealed that PN lesional skin harbors pervasive somatic mutations in fibrotic, neurotropic, and cancer-associated genes. Nonsynonymous mutations were most frequent in NOTCH1 and the Notch signaling pathway, a regulator of cellular proliferation and tissue fibrosis, and NOTCH1 mutations were absent in AD. Somatic copy-number analysis, combined with expression data, showed that recurrently deleted and downregulated genes in PN lesional skin are associated with axonal guidance and extension. Follow-up immunofluorescence validation demonstrated increased NOTCH1 expression in PN lesional skin fibroblasts and increased Notch signaling in PN lesional dermis. Finally, multi-center data revealed a significantly increased risk of NOTCH1-associated diseases in PN patients. In characterizing the somatic landscape of PN, we uncover novel insights into its pathophysiology and identify a role for dysregulated Notch signaling in PN.

Perianal Cutaneous Spindle Cell Squamous Cell Carcinoma With Myxoid Stroma: Case Report and Literature Review

ABSTRACT

Spindle cell squamous cell carcinoma with myxoid stroma is a rare variant of squamous cell carcinoma with sarcomatoid morphology. We report a case of a 75-year-old woman with an ulcerated polypoid cutaneous mass in the perianal area. The patient had a history of clear cell renal cell carcinoma. Microscopy revealed an invasive myxoid spindle cell carcinoma without the classic squamous cell carcinoma component. The immunohistochemical study demonstrated diffuse positive reactions for p63, AE1/3, and CK5/6. The tumor cells were negative for desmin, smooth muscle actin, S100, and CD34. Fluorescent in situ hybridization was negative for EWSR1 gene rearrangement. Follow-up was remarkable for recurrence of tumor in 2 months after complete resection with negative surgical margin. This is the first case report of perianal spindle cell squamous cell carcinoma with myxoid stroma with a literature review of previous case reports from different locations.

Whole-Exome Sequencing of a Case of Squamoid Eccrine Ductal Carcinoma Reveal Similarities With Cutaneous Squamous Cell Carcinoma

ABSTRACT

Squamoid eccrine ductal carcinoma (SEDC) is a poorly documented but likely underrecognized sweat gland malignancy with significant risk for local recurrence and potential for metastasis and rare disease-related mortality. Histopathologically, the tumor demonstrates a biphasic differentiation pattern: superficially, the tumor has squamous differentiation [indistinguishable from well-differentiated cutaneous squamous cell carcinoma (cSCC)], while the deeper aspect has a more infiltrative pattern with prominent ductal differentiation. Diagnosis of SEDC relies upon histopathologic examination alone. Its pathogenesis is poorly understood, and its genomic features have yet to be described. In this article, we characterize the genomic features in a case of SEDC through whole-exome sequencing, then compare its features with cSCC and other eccrine ductal carcinomas. Whole-exome sequencing revealed 30 mutations/Mb with 21 pathogenic or likely pathogenic mutations in total, identified across 14 different genes. The genomic abnormalities identified in this case of SEDC overlap considerably with those found in cSCC but not those of other sweat gland malignancies. The clinical and histopathologic features of SEDC previously reported and the genetic features determined from this case suggest that this tumor may arise initially as a well-differentiated cSCC that subsequently undergoes divergent differentiation focally to resemble a sweat gland malignancy. Genetic analyses of additional cases are warranted to clarify this consideration.

Immunohistochemical Analysis of Single-Stranded DNA Binding Protein 2 in Non-Melanoma Skin Cancers

Single-stranded DNA binding protein 2 (SSBP2) is a tumor suppressor candidate. In this study, the expression level and clinicopathological significance of SSBP2 in squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) were evaluated. We also identified biological pathways associated with a set of genes potentially related to SSBP2. Immunohistochemistry (IHC) was performed on 70 SCC and 146 BCC cases to assess SSBP2 expression semi-quantitatively. In addition, the associations between SSBP2 expression and clinicopathological characteristics were analyzed. Gene ontology (GO) enrichment analysis was performed using publicly available data and web-based bioinformatics tools. Compared with BCC, SCC had a significantly low SSBP2 expression (p < 0.001). In total, 12 (17.1%) of the 70 SCC cases and 30 (20.5%) of the 146 BCC cases showed low SSBP2 expression. Among SCC cases, ulceration (p = 0.005) and a deep level of invasion (p = 0.012) showed an association with low SSBP2 expression. Local recurrence was slightly more common in the SCC subgroup with low SSBP2 expression, although the difference was not significant (p = 0.058). Using GO enrichment analysis, we identified several biological functions performed by a set of 36 genes in SCC. SSBP2 evaluation using IHC can be helpful in the differential diagnosis of SCC and BCC. SSBP2 expression was associated with tumor invasiveness in SCC.

The Distinctive Features behind the Aggressiveness of Oral and Cutaneous Squamous Cell Carcinomas

Squamous cell carcinomas arise from stratified squamous epithelia. Here, a comparative analysis based on recent studies defining the genetic alterations and composition of the stroma of oral and cutaneous squamous cell carcinomas (OSCC and CSCC, respectively) was performed. Both carcinomas share some but not all histological and genetic features. This review was focused on how mutations in tumor suppressor genes and protooncogenes cooperate to determine the differentiation, aggressiveness, and metastatic potential of OSCC and CSCC. In fact, driver mutations in tumor suppressor genes are more frequently observed in OSCC than CSCC. These include mutations in TP53 (encoding pP53 protein), CDKN2A (encoding cyclin dependent kinase inhibitor 2A), FAT1 (encoding FAT atypical cadherin 1), and KMT2D (encoding lysine methyltransferase 2D), with the exception of NOTCH (encoding Notch receptor 1), whose mutation frequency is lower in OSCC compared to CSCC. Finally, we describe the differential composition of the tumor microenvironment and how this influences the aggressiveness of each tumor type. Although both OSCC and CSCC tumors are highly infiltrated by immune cells, high levels of tumor-infiltrating lymphocytes (TILs) have been more frequently reported as predictors of better outcomes in OSCC than CSCC. In conclusion, OSCC and CSCC partially share genetic alterations and possess different causal factors triggering their development. The tumor microenvironment plays a key role determining the outcome of the disease.

PRR14 acts a novel oncogene activating the PI3K signal pathway in human cutaneous squamous cell carcinoma

Proline rich protein 14 (PRR14) is considered as a new component of the nuclear fiber layer, it may be a key molecule in mediating nuclear morphological changes and functional changes in tumorigenesis. But, it's still unclear in human cutaneous squamous cell carcinoma (cSCC). In the study, the expression profiles of PRR14 in patients with cSCC were investigated by immunohistochemistry (IHC), also the PRR14 expression in cSCC tissues were detected using the methods of real-time quantitative PCR (RT-qPCR) and Western blot; cell counting kit-8 (CCK-8) assay, wound healing assay, matrigel-based transwell assay and Annexin V-FITC and PI double-staining with flow cytometry assay were used to investigate the biological functions of PRR14 in A431 and HSC-1 cSCC cells. Overexpression of PRR14 in cSCC patients was reported firstly in this study and its high expression was related to differentiation, thickness and tumor node metastasis (TNM) stage of cSCC. PRR14 inhibition with RNA interfering (RNAi) method resulted in the suppression of cell proliferation, migration and invasion but promotion the apoptosis of cSCC cells, and upregulation of the protein phosphorylation levels of mammalian target of rapamycin (mTOR), phosphoinositide 3-kinase (PI3K) and Akt. The study shows PRR14 maybe an activator of cSCC carcinogenesis through PI3K/Akt/mTOR signal pathway, and it also maybe a prognostic factor and new therapeutical target for cSCC treatment.

The Prognostic Value and Clinical Utility of the 40-Gene Expression Profile (40-GEP) Test in Cutaneous Squamous Cell Carcinoma: Systematic Review and Meta-Analysis

BACKGROUND

The current tumor staging systems for cutaneous squamous cell carcinoma (cSCC) are considered inadequate and insufficient for evaluating the risk of metastasis and for identifying patients at high risk of cSCC. This meta-analysis aimed to assess the prognostic significance of a 40-gene expression profile (40-GEP) both independently and integrated with clinicopathologic risk factors and established staging systems (American Joint Committee on Cancer, eighth edition (AJCC8) and Brigham and Women's Hospital (BWH)).

METHODS

Electronic databases, including PubMed (MEDLINE), Embase, the Cochrane Library, and Google Scholar, were systematically searched to identify cohort studies and randomized controlled trials on evaluations of the prediction value of 40-GEP in cSCC patients up to January 2023. The metastatic risk analysis of a given 40-GEP class combined with tumor stage and/or other clinicopathologic risk factors was based upon log hazard ratios (HRs) and their standard error (SE). Heterogeneity and subgroup analyses were performed, and data quality was assessed.

RESULTS

A total of 1019 patients from three cohort studies were included in this meta-analysis. The overall three-year metastatic-free survival rates were 92.4%, 78.9%, and 45.4% for class 1 (low risk), class 2A (Intermediate risk), and class 2B (high risk) 40-GEP, respectively, indicating a significant variation in survival rates between the risk classification groups. The pooled positive predictive value was significantly higher in class 2B when compared to AJCC8 or BWH. The subgroup analyses demonstrated significant superiority of integrating 40-GEP with clinicopathologic risk factors or AJCC8/BWH, especially for class 2B patients.

CONCLUSIONS

The integration of 40-GEP with staging systems can improve the identification of cSCC patients at high risk of metastasis, potentially leading to improved care and outcomes, especially in the high-risk class 2B group.

Modified 5-aminolevulinic acid photodynamic therapy suppresses cutaneous squamous cell carcinoma through blocking Akt/mTOR-mediated autophagic flux

Background: We previously found that modified 5-aminolevulinic acid photodynamic therapy (M-PDT) is painless and effective in cutaneous squamous cell carcinoma (cSCC) treatment, however, the regulatory mechanism of M-PDT in cSCC is still unclear.

Objective: To clarify the effect and relevant regulatory mechanism of M-PDT in cSCC.

Methods: The cSCC apoptosis was examined by flow cytometry, TUNEL staining and Cleaved-caspase-3 immunofluorescence, respectively. The autophagy-related characterization was detected by monodansylcadaverine (MDC) staining, transmission electron microscopy (TEM), GFP-LC3B autophagic vacuoles localization and mRFP-EGFP tandem fluorescence-tagged LC3B construct, respectively. The expression of autophagy-related proteins and Akt/mTOR signaling molecules were examined by Western blot. ROS generation was measured by DCFH-DA probe.

Results: We found that M-PDT induced cSCC apoptosis in a dose-dependent manner, and this result was related to autophagic flux blockage. The phenomenon is confirmed by the results that M-PDT could induce autophagosomes accumulation and upregulate LC3-II and p62 expression. M-PDT elevated co-localization of RFP and GFP tandem-tagged LC3B puncta in cSCC cell, reflecting autophagic flux blockage, and this was confirmed by transmission electron microscopy. Furthermore, we noticed that M-PDT induced accumulated autophagosomes-dependent apoptosis via targeting ROS-mediated Akt/mTOR signaling. Suppression of Akt potentiated M-PDT-induced upregulation of LC3-II and p62 levels, whereas Akt activation and ROS inhibition rendered resistance to these events. In addition, we observed that lysosomal dysfunction was involved in M-PDT-triggered accumulated autophagosomes-dependent cSCC apoptosis.

Conclusion: Our data demonstrates that M-PDT inhibits cSCC through blocking Akt/mTOR-mediated autophagic flux.

Wnt Signaling Pathways: From Inflammation to Non-Melanoma Skin Cancers

Canonical and non-canonical Wnt signaling pathways are involved in cell differentiation and homeostasis, but also in tumorigenesis. In fact, an exaggerated activation of Wnt signaling may promote tumor growth and invasion. We summarize the most intriguing evidence about the role of Wnt signaling in cutaneous carcinogenesis, in particular in the pathogenesis of non-melanoma skin cancer (NMSC). Wnt signaling is involved in several ways in the development of skin tumors: it may modulate the inflammatory tumor microenvironment, synergize with Sonic Hedgehog pathway in the onset of basal cell carcinoma, and contribute to the progression from precancerous to malignant lesions and promote the epithelial-mesenchymal transition in squamous cell carcinoma. Targeting Wnt pathways may represent an additional efficient approach in the management of patients with NMSC.

Global status of research on cutaneous squamous cell carcinoma and its programmed cell death: Bibliometric and visual analysis from 2012 to middle 2022

Objective

This study was aimed to analyze the research status and development trend of cutaneous squamous cell carcinoma (CSCC), focusing on the field of programmed cell death of CSCC, and providing suggestions for the research of CSCC.

Methods

The publications related to CSCC and CSCC programmed cell death were searched in the Web of Science Core Collection (WOSCC) database, and timespan was set from 2012 to middle 2022. Research trends, authors, major country collaborations, research institutions, representative journals, publishers, and keywords were analyzed with CiteSpace and VOSviewer.

Results

After screening, a total of 3656 publications on CSCC and 156 publications on CSCC cell programmed death were obtained. The number of published articles increased gradually with the years. The United States ranked first in terms of the number of published papers. Research in this field had focused on dermatology. Most of the institutions in both regions were from European and American countries. Harvard University was the most prolific institution. Wiley was the most prolific publisher. The popular keywords for programmed cell death in CSCC were cutaneous squamous cell carcinoma, diagnosis, pd 1, head, nivolumab and risk. Keywords in CSCC field were divided into 7 clusters: cutaneous squamous cell carcinoma, sentinel lymph node biopsy, skin cancer, B-Raf Proto-Oncogene, Serine/Threonine Kinase (BRAF) inhibitor and human Papillomaviruses, and P63 expression. Squamous cell carcinoma, cancer, head and expression were the most popular keywords. The popular keywords for programmed cell death in CSCC were cutaneous squamous cell carcinoma, diagnosis, pd 1, head, nivolumab and risk.

Conclusion

This study analyzed the research status of cutaneous squamous cell carcinoma and programmed cell death from 2012 to middle 2022. Understanding research status and hotspots can help scholars, countries and policymakers to better understand the background and research frontier of CSCC, and guide further research directions.

Suppression of Krüppel-like factor 5 basal expression by CREB1 binding to far distal element

BACKGROUND

Krüppel-like factor 5 (KLF5) is a transcription factor regulating the proliferation and differentiation of epithelial cells, and its uncontrolled expression is closely associated with carcinoma progression. Sp3 binding to the minimal essential region (MER) of KLF5 gene is critical for KLF5 basal expression, but the expression control mechanism is unknown.

OBJECTIVE

This study aimed to identify a regulatory region for KLF5 basal expression and the binding protein in carcinoma cells by analyzing the promoter upstream region.

METHODS

Reporter assays determined the silencer region. The protein binding to the region was identified by database analysis and ChIP assay. The protein mediating the interaction between the region and the MER was confirmed through chromosome conformation capture (3 C) on ChIP assay. The effects of the protein on KLF5 expression were analyzed using qRT-PCR and western blot.

RESULTS

Reporter assay localized the 425-region from upstream KLF5 gene as the silencer. Database analysis and ChIP assay found CREB1 binding to the 425-region. CREB1 siRNA or mutation of CREB1-binding site in the 425-region increased luciferase activities and decreased the binding to 425-region. 3 C on ChIP assay showed that CREB1 mediated interaction of the 425-region and the MER. CREB1 overexpression decreased endogenous KLF5 expression and luciferase activity.

CONCLUSIONS

The 425-region is the silencer of KLF5 basal expression, and CREB1 binding suppresses the expression.

Alkannin exerts antitumor properties in cutaneous squamous cell carcinoma by inducing apoptosis and shifting the M1/M2 polarization of tumor-associated macrophages by upregulating PTEN

Cutaneous squamous cell carcinoma (CSCC) is a common cancer in humans and is the second major type of skin cancer that causes death in humans. In this article, we investigated the effects of alkannin on CSCC progression. We revealed that alkannin curbed CSCC cell viability in a dose-dependent manner and accelerated CSCC cell apoptosis. In addition, alkannin expedited macrophage M1 polarization while curbing M2 polarization. Moreover, alkannin elevated phosphatase and tensin homolog (PTEN) abundance in CSCC cells. The results of bioinformatics analysis revealed that alkannin might modulate CSCC via PTEN. Downregulation of PTEN reversed the effects of alkannin on apoptosis of CSCC cells and M1/M2 polarization of macrophages. Alkannin reduced CSCC tumor growth in a mouse xenograft model. In conclusion, alkannin curbed the advancement of CSCC by expediting apoptosis and facilitating M1 polarization of macrophages by upregulating PTEN. These data may offer a therapeutic approach against CSCC.

Design-of-Experiments (DoE)-Assisted Fabrication of Quercetin-Loaded Nanoemulgel and Its Evaluation against Human Skin Cancer Cell Lines

Background: Quercetin (QCT) is a natural polyphenolic flavonoid showing great potential in the treatment of skin cancer. However, its use is limited owing to its poor water solubility, poor absorption, quick metabolism and excretion, as well as low stability. Preparation of nanoemulgel has been proven to be an effective approach to deliver the drugs topically due to various advantages associated with it. Objectives: This study aimed to prepare stable nanoemulgel of QCT using a Design-of-Experiments (DoE) tool for optimization, to characterize and to assess its in vivo toxicity and efficacy against human cancer cell lines in vitro. Methods: An ultrasonication emulsification method was used for the preparation of QCT-loaded nanoemulsion (QCT@NE). Box-Behnken design was used for the optimization of developed nanoemulgel. Then, in vitro characterization of prepared nanoemulsion was performed using Fourier Transform-Infra Red (FT-IR) spectroscopy, Scanning Electron Microscopy (SEM), particle size analysis, determination of zeta potential and entrapment efficiency (%EE). Further, the developed QCT-loaded nanoemulgel (QCT@NG) was characterized in vitro using texture profile analysis, viscosity and pH determination. Eventually, the cell cytotoxicity studies of the prepared nanoemulgel were performed on the skin cancer cell lines A431 followed by an acute toxicity and skin irritation study on male wistar rats in vivo. Results: The developed QCT@NE was found to be nanometric in size (173.1 ± 1.2 nm) with low polydispersity index (0.353 ± 0.13), zeta potential (-36.1 ± 5.9 mV), and showed good %EE (90.26%). The QCT@NG was found to be substantially more effective against the human skin carcinoma (A431) cell lines as compared to plain QCT with IC₅₀ values of 108.5 and 579.0 µM, respectively. Skin irritation study showed no sign of toxicity and ensured safety for topical application. Hematological analysis revealed no significant differences between the treatment and control group in any biochemical parameter. In the nanoemulgel treatment group, there were no discernible differences in the liver enzymes, bilirubin, hemoglobin, total leukocyte and platelet counts as compared to the control group. Conclusions: The optimized QCT@NG was found to be an ideal and promising formulation for the treatment of skin cancer without showing skin irritation and organ toxicity.

Chondroitin Sulfate Proteoglycan 4 as a Marker for Aggressive Squamous Cell Carcinoma

Chondroitin sulfate (CS) proteoglycan 4 (CSPG4) is a cell surface proteoglycan that is currently under investigation as a marker of cancer malignancy, and as a potential target of anticancer drug treatment. CSPG4 acts as a driver of tumourigenesis by regulating turnover of the extracellular matrix (ECM) to promote tumour cell invasion, migration as well as inflammation and angiogenesis. While CSPG4 has been widely studied in certain malignancies, such as melanoma, evidence is emerging from global gene expression studies, which suggests a role for CSPG4 in squamous cell carcinoma (SCC). While relatively treatable, lack of widely agreed upon diagnostic markers for SCCs is problematic, especially for clinicians managing certain patients, including those who are aged or infirm, as well as those with underlying conditions such as epidermolysis bullosa (EB), for which a delayed diagnosis is likely lethal. In this review, we have discussed the structure of CSPG4, and quantitatively analysed CSPG4 expression in the tissues and pathologies where it has been identified to determine the usefulness of CSPG4 expression as a diagnostic marker and therapeutic target in management of malignant SCC.

Molecular Mechanisms and Targeted Therapies of Advanced Basal Cell Carcinoma

Among human cutaneous malignancies, basal cell carcinoma is the most common. Solid advances in unveiling the molecular mechanisms of basal cell carcinoma have emerged in recent years. In Gorlin syndrome, which shows basal cell carcinoma predisposition, identification of the patched 1 gene (PTCH1) mutation was a dramatic breakthrough in understanding the carcinogenesis of basal cell carcinoma. PTCH1 plays a role in the hedgehog pathway, and dysregulations of this pathway are known to be crucial for the carcinogenesis of many types of cancers including sporadic as well as hereditary basal cell carcinoma. In this review, we summarize the clinical features, pathological features and hedgehog pathway as applied in basal cell carcinoma. Other crucial molecules, such as p53 and melanocortin-1 receptor are also discussed. Due to recent advances, therapeutic strategies based on the precise molecular mechanisms of basal cell carcinoma are emerging. Target therapies and biomarkers are also discussed.

Electrochemotherapy for the treatment of cutaneous squamous cell carcinoma: The INSPECT experience (2008-2020)

Introduction

Cutaneous squamous cell carcinoma (cSCC) is a frequent skin cancer with a high risk of recurrence characterized by tumor infiltration and, in advanced cases, a poor prognosis. ECT (electrochemotherapy) is an alternative treatment option for locally advanced or recurrent cSCC that is unsuitable for surgical resection. In this study, we aimed to evaluate the data in the InspECT (International Network for Sharing Practice on ECT) registry of the referral centers and to clarify the indications for the use of ECT as a treatment modality for cSCC.

Materials and methods

Patients with primary, recurrent or locally advanced cSCC from 18 European centers were included. They underwent at least one ECT session with bleomycin between February 2008 and November 2020, which was performed following the European Standard Operating Procedures.

Results

The analysis included 162 patients (mean age of 80 years; median, 1 lesion/patient). Side effects were mainly local and mild (hyperpigmentation, 11%; ulceration, 11%; suppuration, 4%). The response to treatment per patient was 62% complete and 21% partial. In the multivariate model, intravenous drug administration and small tumor size showed a significant association with a positive outcome (objective response). One-year local progression-free survival was significantly better (p<0.001) in patients with primary tumors (80% (95% C.I. 70%-90%) than in patients with locally advanced disease (49% (95% C.I. 30%-68%).

Conclusion

In the present study, ECT showed antitumor activity and a favorable safety profile in patients with complex cSCC for whom there was no widely accepted standard of care. Better results were obtained in primary and small tumors (<3 cm) using intravenous bleomycin administration.