The Polycomb proteins RING1B and EZH2 repress the tumoral pro-inflammatory function in metastasizing primary cutaneous squamous cell carcinoma

Inflammation and epigenetics of sporotrichosis disease

Sporotrichosis, a fungal disease, is caused by exposure to soil that harbors Sporothrix schenckii or through inhalation of fungal spores. Skin is the most frequently exposed organ making sporotrichosis a primarily dermal disease. Many described reports in the literature suggest a connection of sporotrichosis with cutaneous squamous cell carcinoma with some connection between initial sporotrichosis diagnosis and treatment followed by development of cutaneous squamous cell carcinoma at the very site. Conversely, there is also evidence for sporotrichosis subsequent to skin cancer diagnosis, even after cancer chemotherapy, which points towards weakening of immune response by cancer chemotherapy leading to attack and infection by Sporothrix schenckii. We also propose and focus on inflammation as the connection between sporotrichosis, cancer and even the metastatic spread of cancer. Inflammation-associated IL-6, IFN-γ, natural killer cells and M2-macrophages possibly mechanistically link sporotrichosis with cancer, particularly cutaneous squamous cell carcinoma. These inflammation related factors/cells are regulated epigenetically raising the possibility of epigenetic regulation of sporotrichosis, which has not been described yet in the available literature. Clinical management of inflammation may thus be effective strategy not just against sporotrichosis but also the related onset of cutaneous squamous cell carcinoma and possibly its metastasis to lymph nodes.

Advances in cutaneous squamous cell carcinoma

Human malignancies arise predominantly in tissues of epithelial origin, where the stepwise transformation from healthy epithelium to premalignant dysplasia to invasive neoplasia involves sequential dysregulation of biological networks that govern essential functions of epithelial homeostasis. Cutaneous squamous cell carcinoma (cSCC) is a prototype epithelial malignancy, often with a high tumour mutational burden. A plethora of risk genes, dominated by UV-induced sun damage, drive disease progression in conjunction with stromal interactions and local immunomodulation, enabling continuous tumour growth. Recent studies have identified subpopulations of SCC cells that specifically interact with the tumour microenvironment. These advances, along with increased knowledge of the impact of germline genetics and somatic mutations on cSCC development, have led to a greater appreciation of the complexity of skin cancer pathogenesis and have enabled progress in neoadjuvant immunotherapy, which has improved pathological complete response rates. Although measures for the prevention and therapeutic management of cSCC are associated with clinical benefit, the prognosis remains poor for advanced disease. Elucidating how the genetic mechanisms that drive cSCC interact with the tumour microenvironment is a current focus in efforts to understand, prevent and treat cSCC.

Update on the Molecular Pathology of Cutaneous Squamous Cell Carcinoma

Cutaneous squamous cell carcinoma (cSCC) is the second most common skin cancer, originating from keratinocytes of the spinous layer. Numerous risk factors have been discovered for the initiation and growth of this type of cancer, such as exposure to UV and ionizing radiation, chemical carcinogens, the presence of immunosuppression states, chronic inflammation, infections with high-risk viral strains, and, last but not least, the presence of diseases associated with genetic alterations. The important socio-economic impact, as well as the difficulty associated with therapy for advanced forms, has made the molecular mechanisms underlying this neoplasia more and more intensively studied, with the intention of achieving a better understanding and advancing the treatment of this pathology. This review aims to provide a brief foray into the molecular, genetic, and epigenetic aspects of this cancer, as well as the treatment methods, ranging from the first used to the latest targeted therapies.

Loss of dyskerin facilitates the acquisition of metastatic traits by altering the mevalonate pathway

The initial dissemination of cancer cells from many primary tumors implies intravasation to lymphatic nodes or blood vessels. To investigate the mechanisms involved, we analyzed the expression of small non-coding RNAs in cutaneous squamous cell carcinoma (cSCC), a prevalent tumor that mainly spreads to lymph nodes. We report the reduced expression of small nucleolar RNAs in primary cSCCs that metastasized when compared to non-metastasizing cSCCs, and the progressive loss of DKC1 (dyskerin, which stabilizes the small nucleolar RNAs) along the metastasis. DKC1 depletion in cSCC cells triggered lipid metabolism by altering the mevalonate pathway and the acquisition of metastatic traits. Treatment of DKC1-depleted cells with simvastatin, an inhibitor of the mevalonate pathway, blocked the expression of proteins involved in the epithelial-to-mesenchymal transition. Consistently, the expression of the enzyme 3-hydroxy-3-methylglutaryl-CoA synthase 1 was associated with pathological features of high metastatic risk in cSCC patients. Our data underpin the relevance of the mevalonate metabolism in metastatic dissemination and pave the possible incorporation of therapeutic approaches among the antineoplastic drugs used in routine patient care.

Scientific Research Directions on the Histopathology and Immunohistochemistry of the Cutaneous Squamous Cell Carcinoma: A Scientometric Study

Introduction: Cutaneous squamous cell carcinoma (cSCC) is one of the most frequently occurring types of cancer in humans. Scientometric research is an innovative method for analyzing the research trends in various domains, with great implications in the field of medicine. Materials and Methods: We searched the Web of Science database with the following established query terms: “Squamous cell carcinoma”, “skin”, and “immunohistochemistry”. After applying the inclusion and exclusion criteria, a total of 76 articles were selected. The present study aims to analyze, based on the frequency of use of keywords with scientometric algorithms and map-based distributions, the trends of the research concerning cSCCs in 2017–2022. Results: A graphical representation based on 11 scientometric maps presented the division of the keywords into seven clusters, from which seven categories of research interest were defined. The clusters represent a multidisciplinary approach to the diagnosis and treatment of cSCCs, cancer diagnostics, patient outcomes, histopathological importance, management of cSCCs, role of progression, and adequate treatment of and importance of immunohistochemistry for cSCCs. The distribution of the citations shows the importance of the available research on cSCCs by analyzing the first five most-cited articles included in our study in direct concordance with the seven defined clusters. Conclusion: The scientometric research method reveals the interest of research in the multidisciplinary approach used to obtain the best outcomes for the patient, including a targeted investigation, as well as diagnostic and treatment options. The trends in the research reveal that histopathological diagnostics and immunohistochemistry, combined with molecular techniques, are the most important tools used to establish a personalized diagnosis, thus increasing the quality of life and life expectancy for patients with cSCCs.

Oh, the Mutations You'll Acquire! A Systematic Overview of Cutaneous Squamous Cell Carcinoma

Nearly two million cases of cutaneous squamous cell carcinoma (cSCC) are diagnosed every year in the United States alone. cSCC is notable for both its prevalence and its propensity for invasion and metastasis. For many patients, surgery is curative. However, patients experiencing immunosuppression or recurrent, advanced, and metastatic disease still face limited therapeutic options and significant mortality. cSCC forms after decades of sun exposure and possesses the highest known mutation rate of all cancers. This mutational burden complicates efforts to identify the primary factors driving cSCC initiation and progression, which in turn hinders the development of targeted therapeutics. In this review, we summarize the mutations and alterations that have been observed in patients’ cSCC tumors, affecting signaling pathways, transcriptional regulators, and the microenvironment. We also highlight novel therapeutic opportunities in development and clinical trials.

Epigenetic and metabolic interplay in cutaneous squamous cell carcinoma

With the ageing of the population and increased levels of recreational sun exposure and immunosuppression, cutaneous squamous cell carcinoma (cSCC), is both an enormous and expanding clinical and economic issue. Despite advances in therapy, up to 5000-8000 people are estimated to die every year from cSCC in the U.S., highlighting the need for both better prevention and treatments. Two emerging areas of scientific discovery that may offer new therapeutic approaches for cSCC are epigenetics and metabolism. Importantly, these disciplines display extensive crosstalk, with metabolic inputs contributing to the chromatin landscape, while the dynamic epigenome shapes transcriptional and cellular responses that feedback into cellular metabolism. Recent evidence suggests that indeed, epigenetic and metabolic dysregulation may be critical contributors to cSCC pathogenesis. Here, we synthesize the latest findings from these fast-moving fields, including how they may drive cSCC, yet also be harnessed for therapy.

Methyltransferases in the Pathogenesis of Keratinocyte Cancers

Recent evidence suggests that the disruption of gene expression by alterations in DNA, RNA, and histone methylation may be critical contributors to the pathogenesis of keratinocyte cancers (KCs), made up of basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (cSCC), which collectively outnumber all other human cancers combined. While it is clear that methylation modifiers are frequently dysregulated in KCs, the underlying molecular and mechanistic changes are only beginning to be understood. Intriguingly, it has recently emerged that there is extensive cross-talk amongst these distinct methylation processes. Here, we summarize and synthesize the latest findings in this space and highlight how these discoveries may uncover novel therapeutic approaches for these ubiquitous cancers.

lncRNA HCP5 acts as a ceRNA to regulate EZH2 by sponging miR‑138‑5p in cutaneous squamous cell carcinoma

Long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) are essential for the progression of tumors, including cutaneous squamous cell carcinoma (CSCC). The present study aimed to examine the competing endogenous RNA (ceRNA) network in CSCC. Differentially expressed genes in CSCC were analyzed using the GSE66359 microarray data set, and the upstream miRNAs and lncRNAs were predicted using online database analysis (TargetScan 7.1, mirDIP 4.1, miRSearch V3.0, miRDB and RNA22 2.0) and were verified in clinical tissues. RNA pull-down and dual luciferase reporter gene assays were used to verify the targeting relationships among lncRNA human histocompatibility leukocyte antigen complex P5 (HCP5), miR-138-5p and enhancer of zeste homolog 2 (EZH2). Cell lines with a high and low HCP5 expression were screened, and a pcDNA-3.1-HCP5 overexpression vector, small interfering RNA against HCP5, miR-138-5p mimics and miR-138-5p inhibitors were transfected into the CSCC cells. Cell viability, invasion, migration, apoptotic rate and autophagy were evaluated. The effects of HCP5 on autophagy and apoptosis of CSCC cells were verified in vivo using Ki67 and TUNEL staining. EZH2 was demonstrated to be upregulated in CSCC cells. miR-138-5p target sequences were identified in HCP5 and EZH2. HCP5 was revealed to function as a putative ceRNA of miR-138-5p to positively regulate EZH2, and EZH2 was shown to regulate autophagy and apoptosis of CSCC cells through the STAT3/VEGFR2 pathway. HCP5 overexpression decreased miR-138-5p levels, increased EZH2 levels and promoted cell malignant behaviors and autophagy but decreased the apoptosis rate. These trends were opposite when HCP5 was silenced. In conclusion, HCP5 may competitively bind to miR-138-5p to regulate EZH2 in CSCC cells, promoting autophagy and reducing apoptosis through the STAT3/VEGFR2 pathway. This study may provide a new perspective for understanding the molecular mechanism and treatment of CSCC.

Cutaneous Squamous Cell Carcinoma: From Pathophysiology to Novel Therapeutic Approaches

Cutaneous squamous cell carcinoma (cSCC), a non-melanoma skin cancer, is a keratinocyte carcinoma representing one of the most common cancers with an increasing incidence. cSCC could be in situ (e.g., Bowen’s disease) or an invasive form. A significant cSCC risk factor is advanced age, together with cumulative sun exposure, fair skin, prolonged immunosuppression, and previous skin cancer diagnoses. Although most cSCCs can be treated by surgery, a fraction of them recur and metastasize, leading to death. cSCC could arise de novo or be the result of a progression of the actinic keratosis, an in situ carcinoma. The multistage process of cSCC development and progression is characterized by mutations in the genes involved in epidermal homeostasis and by several alterations, such as epigenetic modifications, viral infections, or microenvironmental changes. Thus, cSCC development is a gradual process with several histological- and pathological-defined stages. Dermoscopy and reflectance confocal microscopy enhanced the diagnostic accuracy of cSCC. Surgical excision is the first-line treatment for invasive cSCC. Moreover, radiotherapy may be considered as a primary treatment in patients not candidates for surgery. Extensive studies of cSCC pathogenic mechanisms identified several pharmaceutical targets and allowed the development of new systemic therapies, including immunotherapy with immune checkpoint inhibitors, such as Cemiplimab, and epidermal growth factor receptor inhibitors for metastatic and locally advanced cSCC. Furthermore, the implementation of prevention measures has been useful in patient management.

PARP1 and PRC2 double deficiency promotes BRCA-proficient breast cancer growth by modification of the tumor microenvironment

Poly (ADP-ribose) polymerase 1 (PARP1) and polycomb-repressive complex 2 (PRC2) are each known for their individual roles in cancer, but their cooperative roles have only been studied in the DNA damage repair process in the context of BRCA-mutant cancers. Here, we show that simultaneous inhibition of PARP1 and PRC2 in the MDA-MB-231 BRCA-proficient triple-negative breast cancer (TNBC) cell line leads to a synthetic viability independent of the mechanisms of DNA damage repair. Specifically, we find that either genetic depletion or pharmacological inhibition of both PARP1 and PRC2 can accelerate tumor growth rate. We attribute this to modifications in the tumor microenvironment (TME) that are induced by double-depleted breast cancer cells, such as promoting intratumoral angiogenesis and increasing the proportion of tumor-promoting type 2 (M2) macrophages. These changes subsequently inhibit cell death and promote proliferation. Mechanistically, we find that PARP1 and PRC2 double depletion induces not only a basal activation of the NF-κB pathway but also a maximal activation of NF-κB within the TME in response to external stimuli such as hypoxia and the presence of macrophages. In summary, our study reveals an unprecedented synthetic viable interaction between PARP1 and PRC2 in BRCA-proficient TNBC and identifies NF-κB as the downstream mediator. DATABASE: RNA-seq data are available in the GEO databases under the accession GSE142769.

Molecular prediction of metastasis in cutaneous squamous cell carcinoma

PURPOSE OF REVIEW

Cutaneous squamous cell carcinoma (cSCC) is a highly prevalent malignancy frequently occurring on body surfaces chronically exposed to ultraviolet radiation. While a large majority of tumors remain localized to the skin and immediate subcutaneous tissue and are cured with surgical excision, a small subset of patients with cSCC will develop metastatic disease. Risk stratification for cSCC is performed using clinical staging systems, but given a high mutational burden and advances in targeted and immunotherapy, there is growing interest in molecular predictors of high-risk disease.

RECENT FINDINGS

Recent literature on the risk for metastasis in cSCC includes notable findings in genes involved in cell-cycle regulation, tumor suppression, tissue invasion and microenvironment, interactions with the host-immune system, and epigenetic regulation.

SUMMARY

cSCC is a highly mutated tumor with complex carcinogenesis. Regulators of tumor growth and local invasion are numerous and increasingly well-understood but drivers of metastasis are less established. Areas of importance include central system regulators (NOTCH, miRNAs), proteins involved in tissue invasion (podoplanin, E-cadherin), and targets of existing and emerging therapeutics (PD-1, epidermal growth factor receptor). Given the complexity of cSCC carcinogenesis, the use of machine learning algorithms and computational genomics may provide ultimate insight and prospective studies are needed to verify clinical relevance.

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.

Polycomb complexes associate with enhancers and promote oncogenic transcriptional programs in cancer through multiple mechanisms

Polycomb repressive complex 1 (PRC1) plays essential roles in cell fate decisions and development. However, its role in cancer is less well understood. Here, we show that RNF2, encoding RING1B, and canonical PRC1 (cPRC1) genes are overexpressed in breast cancer. We find that cPRC1 complexes functionally associate with ERα and its pioneer factor FOXA1 in ER+ breast cancer cells, and with BRD4 in triple-negative breast cancer cells (TNBC). While cPRC1 still exerts its repressive function, it is also recruited to oncogenic active enhancers. RING1B regulates enhancer activity and gene transcription not only by promoting the expression of oncogenes but also by regulating chromatin accessibility. Functionally, RING1B plays a divergent role in ER+ and TNBC metastasis. Finally, we show that concomitant recruitment of RING1B to active enhancers occurs across multiple cancers, highlighting an under-explored function of cPRC1 in regulating oncogenic transcriptional programs in cancer.

The role of Polycomb Repressive Complex 1 (PRC1) is well described in development. Here, the authors investigate canonical PRC1’s regulation of transcriptional programs in breast cancer where, in addition to its repressive function, it is also recruited to oncogenic active enhancers to regulate enhancer activity and chromatin accessibility.