Collagens XV and XVIII show different expression and localisation in cutaneous squamous cell carcinoma: type XV appears in tumor stroma, while XVIII becomes upregulated in tumor cells and lost from microvessels

Clinical Risk Factors for Cutaneous Squamous Cell Carcinoma in Patients with Actinic Keratosis or Cutaneous Squamous Cell Carcinoma in Situ: A Retrospective Double-cohort Study

Actinic keratosis and cutaneous squamous cell carcinoma in situ are precancerous forms of cutaneous squamous cell carcinoma. In this single-centre retrospective study, patients with histopathologically confirmed actinic keratosis (n = 121) or cutaneous squamous cell carcinoma in situ (n = 99) as their initial keratinocyte-derived lesion were compared and evaluated with regard to development of cutaneous squamous cell carcinoma during a 5-year observation period. Patients with severely dysplastic actinic keratosis or cutaneous squamous cell carcinoma in situ as their initial lesion developed cutaneous squamous cell carcinoma more rapidly than patients with actinic keratosis with mild or moderate dysplasia. With either actinic keratosis or cutaneous squamous cell carcinoma in situ as an initial lesion, advanced age, male sex, comorbidity with basal cell carcinoma, and immunosuppressive medication were associated with elevated risk of cutaneous squamous cell carcinoma development. Regarding solely patient with actinic keratosis as their initial lesion male sex, advanced age, immunosuppressive medication, location of the initial lesion, and degree of dysplasia were associated with the risk of cutaneous squamous cell carcinoma. Among patients with cutaneous squamous cell carcinoma in situ as their initial lesion, only aspirin usage was associated with increased risk of cutaneous squamous cell carcinoma. This study indicates that, among the vast and increasing population of patients with cutaneous squamous cell carcinoma precursors, male patients with immunosuppressive medication who develop basal cell carcinoma should be regarded as at heightened risk of cutaneous squamous cell carcinoma development and warrant closer surveillance.

Cancer-associated fibroblast activation predicts progression, metastasis, and prognosis of cutaneous squamous cell carcinoma

Cutaneous squamous cell carcinoma (cSCC) is the most common metastatic skin cancer and the metastatic disease is associated with poor prognosis. Cancer-associated fibroblasts (CAFs) promote progression of cancer, but their role in cSCC is largely unknown. We examined the potential of CAF markers in the assessment of metastasis risk and prognosis of primary cSCC. We utilized multiplexed fluorescence immunohistochemistry for profiling CAF landscape in metastatic and non-metastatic primary human cSCCs, in metastases, and in premalignant epidermal lesions. Quantitative high-resolution image analysis was performed with two separate panels of antibodies for CAF markers and results were correlated with clinical and histopathological parameters including disease-specific mortality. Increased stromal expression of fibroblast activation protein (FAP), α-smooth muscle actin, and secreted protein acidic and rich in cysteine (SPARC) were associated with progression to invasive cSCC. Elevation of FAP and platelet-derived growth factor receptor-β (PDGFRβ) expression was associated with metastasis risk of primary cSCCs. High expression of PDGFRβ and periostin correlated with poor prognosis. Multimarker combination defined CAF subset, PDGFRα-/PDGFRβ+/FAP+, was associated with invasion and metastasis, and independently predicted poor disease-specific survival. These results identify high PDGFRβ expression alone and multimarker combination PDGFRα-/PDGFRβ+/FAP+ by CAFs as potential biomarkers for risk of metastasis and poor prognosis.

The Mutational and Microenvironmental Landscape of Cutaneous Squamous Cell Carcinoma: A Review

Cutaneous squamous cell carcinoma (cSCC) manifests through the complex interactions of UV-induced DNA damage, genetic mutations, and alterations in the tumor microenvironment. A high mutational burden is present in cSCC, as well as both cSCC precursors and normal skin, making driver genes difficult to differentiate. Despite this, several key driver genes have been identified, including TP53, the NOTCH family, CDKN2A, PIK3CA, and EGFR. In addition to mutations, the tumor microenvironment and the manipulation and evasion of the immune system play a critical role in cSCC progression. Novel therapeutic approaches, such as immunotherapy and EGFR inhibitors, have been used to target these dysregulations, and have shown promise in treating advanced cSCC cases, emphasizing the need for targeted interventions considering both genetic and microenvironmental factors for improved patient outcomes.

Targeting collagen XVIII improves the efficiency of ErbB inhibitors in breast cancer models

The tumor extracellular matrix (ECM) critically regulates cancer progression and treatment response. Expression of the basement membrane component collagen XVIII (ColXVIII) is induced in solid tumors, but its involvement in tumorigenesis has remained elusive. We show here that ColXVIII was markedly upregulated in human breast cancer (BC) and was closely associated with a poor prognosis in high-grade BCs. We discovered a role for ColXVIII as a modulator of epidermal growth factor receptor tyrosine kinase (ErbB) signaling and show that it forms a complex with ErbB1 and -2 (also known as EGFR and human epidermal growth factor receptor 2 [HER2]) and α6-integrin to promote cancer cell proliferation in a pathway involving its N-terminal portion and the MAPK/ERK1/2 and PI3K/AKT cascades. Studies using Col18a1 mouse models crossed with the mouse mammary tumor virus-polyoma virus middle T antigen (MMTV-PyMT) mammary carcinogenesis model showed that ColXVIII promoted BC growth and metastasis in a tumor cell-autonomous manner. Moreover, the number of mammary cancer stem cells was significantly reduced in the MMTV-PyMT and human cell models upon ColXVIII inhibition. Finally, ablation of ColXVIII substantially improved the efficacy of ErbB-targeting therapies in both preclinical models. In summary, ColXVIII was found to sustain the stemness properties of BC cells and tumor progression and metastasis through ErbB signaling, suggesting that targeting ColXVIII in the tumor milieu may have important therapeutic potential.

Matrix Effectors in the Pathogenesis of Keratinocyte-Derived Carcinomas

Basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (cSCC), referred to as keratinocyte carcinomas, are skin cancer with the highest incidence. BCCs, rarely metastasize; whereas, though generally not characterized by high lethality, approximately 2–4% of primary cSCCs metastasize with patients exhibiting poor prognosis. The extracellular matrix (ECM) serves as a scaffold that provides structural and biological support to cells in all human tissues. The main components of the ECM, including fibrillar proteins, proteoglycans (PGs), glycosaminoglycans (GAGs), and adhesion proteins such as fibronectin, are secreted by the cells in a tissue-specific manner, critical for the proper function of each organ. The skin compartmentalization to the epidermis and dermis compartments is based on a basement membrane (BM), a highly specialized network of ECM proteins that separate and unify the two compartments. The stiffness and assembly of BM and tensile forces affect tumor progenitors' invasion at the stratified epithelium's stromal border. Likewise, the mechanical properties of the stroma, e.g., stiffness, are directly correlated to the pathogenesis of the keratinocyte carcinomas. Since the ECM is a pool for various growth factors, cytokines, and chemokines, its' intense remodeling in the aberrant cancer tissue milieu affects biological functions, such as angiogenesis, adhesion, proliferation, or cell motility by regulating specific signaling pathways. This review discusses the structural and functional modulations of the keratinocyte carcinoma microenvironment. Furthermore, we debate how ECM remodeling affects the pathogenesis of these skin cancers.

The Role of Extracellular Matrix Remodeling in Skin Tumor Progression and Therapeutic Resistance

The extracellular matrix remodeling in the skin results from a delicate balance of synthesis and degradation of matrix components, ensuring tissue homeostasis. These processes are altered during tumor invasion and growth, generating a microenvironment that supports growth, invasion, and metastasis. Apart from the cellular component, the tumor microenvironment is rich in extracellular matrix components and bound factors that provide structure and signals to the tumor and stromal cells. The continuous remodeling in the tissue compartment sustains the developing tumor during the various phases providing matrices and proteolytic enzymes. These are produced by cancer cells and stromal fibroblasts. In addition to fostering tumor growth, the expression of specific extracellular matrix proteins and proteinases supports tumor invasion after the initial therapeutic response. Lately, the expression and structural modification of matrices were also associated with therapeutic resistance. This review will focus on the significant alterations in the extracellular matrix components and the function of metalloproteinases that influence skin cancer progression and support the acquisition of therapeutic resistance.

C1r Upregulates Production of Matrix Metalloproteinase-13 and Promotes Invasion of Cutaneous Squamous Cell Carcinoma

Cutaneous squamous cell carcinoma (cSCC) is the most common metastatic skin cancer with increasing incidence worldwide. Previous studies have demonstrated the role of complement system in cSCC progression. In this study we have investigated the mechanistic role of serine protease C1r, a component of the classical pathway of complement system, in cSCC. Knockout of C1r in cSCC cells using CRISPR/Cas9 resulted in significant decrease in their proliferation, migration, and invasion through collagen type I compared to wild type cSCC cells. Knockout of C1r suppressed growth and vascularization of cSCC xenograft tumors, and promoted apoptosis of tumor cells in vivo. mRNA-seq analysis after C1r knockdown revealed significantly regulated GO terms Cell-matrix adhesion, Extracellular matrix component, Basement membrane, Metalloendopeptidase activity and KEGG pathway Extracellular matrix-receptor interaction. Among the significantly regulated genes were invasion-associated matrix metalloproteinases MMP1, MMP13, MMP10, and MMP12. Knockout of C1r resulted in decreased production of MMP-1, MMP-13, MMP-10, and MMP-12 by cSCC cells in culture. Knockout of C1r inhibited expression of MMP-13 by tumor cells, suppressed invasion, and reduced the amount of degraded collagen in vivo in xenografts. These results provide evidence for the role of C1r in promoting the invasion of cSCC cells by increasing MMP production.

Therapeutic combination silencing VEGF and SOX10 increases the antiangiogenic effect in the mouse melanoma model B16-F10 - in vitro and in vivo studies

INTRODUCTION

Gene therapy is an innovative form of treatment of genetic diseases, in which psiRNA molecules silencing specific genes are applied.

AIM

The study evaluated the anti-tumour effect of psiRNA silencing preparations of the vascular endothelial growth factor (VEGF) and Sry-related HMG-Box gene 10 (SOX10) on melanoma (B16-F10) by inhibiting angiogenesis.

MATERIAL AND METHODS

The preparations based on plasmid vectors psiRNA silencing the gene SOX10 and VEGF that form complexes with cationic lipid (psiRNA/carrier) have been developed. psiRNA preparations were tested on the mouse melanoma cell line B16-F10, both in vitro and in vivo. The silencing activity of transfected melanoma cells with the obtained psiRNA preparations was examined using the qPCR and Western blot methods. The anti-tumour activity of psiRNA preparations on melanoma tumour cells was then evaluated in a mouse in vivo model.

RESULTS

In vitro studies have shown that the B16-F10 cells efficiently transfect non-viral preparations - psiRNA: Lyovec (74-89%). Worth mentioning is the fact that silencing SOX10 in B16-F10 melanoma cells increases the expression of the COL18A1 gene (compared to the preparation inhibiting only VEGF), which codes the endostatin to stop angiogenesis. In vivo results show that the level of haemoglobin in tumours of mice treated with psiRNA formulations was over 6 times lower than controls and tumour mass was 60-80% lower.

CONCLUSIONS

The novel study proves that simultaneous inhibition of SOX10 and VEGF enhances the antiangiogenic action and thus contributes to a significant halt of disease development. In addition, these data expand knowledge about SOX10 regulation and functions.

Stroma AReactive Invasion Front Areas (SARIFA) - a new prognostic biomarker in gastric cancer related to tumor-promoting adipocytes

Compared to other malignancies, there is a lack of easy-to-evaluate biomarkers for gastric cancer, which is associated with an adverse clinical outcome in many cases. Here, we present Stroma AReactive Invasion Front Areas (SARIFA) as a new histological prognostic marker. We defined SARIFA as the direct contact between a cluster of tumor glands/cells comprising at least five tumor cells and inconspicuous surrounding adipose tissue at the invasion front. A total of 480 adenocarcinomas of the stomach and the gastroesophageal junction from two different collections were classified according to SARIFA. To understand the potential underlying mechanisms, a transcriptome analysis was conducted using digital spatial profiling (DSP). It was found that 20% of the tumors were SARIFA-positive. Kappa values between the three pathologists were good in both collections: 0.74 and 0.78. Patients who presented SARIFA-positive tumors had a significantly lower overall survival in Collections A (median: 20.0 versus 44.0 months; p = 0.014, n = 160) and B (median: 15.0 versus 41.0 months; p < 0.0001, n = 320). SARIFA positivity emerged as a negative independent prognostic factor for overall survival (HR 1.638, 95% CI 1.153-2.326, p = 0.006). Using DSP, the most upregulated genes in SARIFA-positive cases were those associated with triglyceride catabolism and endogenous sterols. COL15A1, FABP2, and FABP4 were differentially expressed in positive cases. At the protein level, the expression of proteins related to lipid metabolism was confirmed. SARIFA combines low inter-observer variability, minimal effort, and high prognostic relevance, and is therefore an extremely promising biomarker related to tumor-promoting adipocytes in gastric cancer. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.

Deletion of Col15a1 Modulates the Tumour Extracellular Matrix and Leads to Increased Tumour Growth in the MMTV-PyMT Mouse Mammary Carcinoma Model

Basement membrane (BM) zone-associated collagen XV (ColXV) has been shown to suppress the malignancy of tumour cells, and its restin domain can inhibit angiogenesis. In human breast cancer, as well as in many other human carcinomas, ColXV is lost from the epithelial BM zone prior to tumour invasion. Here, we addressed the roles of ColXV in breast carcinogenesis using the transgenic MMTV-PyMT mouse mammary carcinoma model. We show here for the first time that the inactivation of Col15a1 in mice leads to changes in the fibrillar tumour matrix and to increased mammary tumour growth. ColXV is expressed by myoepithelial and endothelial cells in mammary tumours and is lost from the ductal BM along with the loss of the myoepithelial layer during cancer progression while persisting in blood vessels and capillaries, even in invasive tumours. However, despite the absence of anti-angiogenic restin domain, neovascularisation was reduced rather than increased in the ColXV-deficient mammary tumours compared to controls. We also show that, in robust tumour cell transplantation models or in a chemical-induced fibrosarcoma model, the inactivation of Col15a1 does not affect tumour growth or angiogenesis. In conclusion, our results support the proposed tumour suppressor function of ColXV in mammary carcinogenesis and reveal diverse roles of this collagen in different cancer types.

The Role of p53 in Progression of Cutaneous Squamous Cell Carcinoma

Skin cancers are the most common types of cancer worldwide, and their incidence is increasing. Melanoma, basal cell carcinoma (BCC), and cutaneous squamous cell carcinoma (cSCC) are the three major types of skin cancer. Melanoma originates from melanocytes, whereas BCC and cSCC originate from epidermal keratinocytes and are therefore called keratinocyte carcinomas. Chronic exposure to ultraviolet radiation (UVR) is a common risk factor for skin cancers, but they differ with respect to oncogenic mutational profiles and alterations in cellular signaling pathways. cSCC is the most common metastatic skin cancer, and it is associated with poor prognosis in the advanced stage. An important early event in cSCC development is mutation of the TP53 gene and inactivation of the tumor suppressor function of the tumor protein 53 gene (TP53) in epidermal keratinocytes, which then leads to accumulation of additional oncogenic mutations. Additional genomic and proteomic alterations are required for the progression of premalignant lesion, actinic keratosis, to invasive and metastatic cSCC. Recently, the role of p53 in the invasion of cSCC has also been elucidated. In this review, the role of p53 in the progression of cSCC and as potential new therapeutic target for cSCC will be discussed.

NBAT1/CASC15-003/USP36 control MYCN expression and its downstream pathway genes in neuroblastoma

Background

MYCN has been an attractive therapeutic target in neuroblastoma considering the widespread amplification of the MYCN locus in neuroblastoma, and its established role in neuroblastoma development and progression. Thus, understanding neuroblastoma-specific control of MYCN expression at the transcriptional and post-transcriptional level would lead to identification of novel MYCN-dependent oncogenic pathways and potential therapeutic strategies.

Methods

By performing loss- and gain-of-function experiments of the neuroblastoma hotspot locus 6p22.3 derived lncRNAs CASC15-003 and NBAT1, together with coimmunoprecipitation and immunoblotting of MYCN, we have shown that both lncRNAs post-translationally control the expression of MYCN through regulating a deubiquitinase enzyme USP36. USP36 oncogenic properties were investigated using cancer cell lines and in vivo models. RNA-seq analysis of loss-of-function experiments of CASC15-003/NBAT1/MYCN/USP36 and JQ1-treated neuroblastoma cells uncovered MYCN-dependent oncogenic pathways.

Results

We show that NBAT1/CASC15-003 control the stability of MYCN protein through their common interacting protein partner USP36. USP36 harbors oncogenic properties and its higher expression in neuroblastoma patients correlates with poor prognosis, and its downregulation significantly reduces tumor growth in neuroblastoma cell lines and xenograft models. Unbiased integration of RNA-seq data from CASC15-003, NBAT1, USP36, and MYCN knockdowns and neuroblastoma cells treated with MYCN inhibitor JQ1, identified genes that are jointly regulated by the NBAT1/CASC15-003/USP36/MYCN pathway. Functional experiments on one of the target genes, COL18A1, revealed its role in the NBAT1/CASC15-003-dependent cell adhesion feature in neuroblastoma cells.

Conclusion

Our data show post-translational regulation of MYCN by NBAT1/CASC15-003/USP36, which represents a new regulatory layer in the complex multilayered gene regulatory network that controls MYCN expression.

Matrix metalloproteinases in keratinocyte carcinomas

The incidence of cutaneous keratinocyte-derived cancers is increasing globally. Basal cell carcinoma (BCC) is the most common malignancy worldwide, and cutaneous squamous cell carcinoma (cSCC) is the most common metastatic skin cancer. BCC can be classified into subtypes based on the histology, and these subtypes are classified further into low- and high-risk tumors. There is an increasing need to identify new therapeutic strategies for the treatment of unresectable and metastatic cSCC, and for aggressive BCC variants such as infiltrating, basosquamous or morpheaform BCCs. The most important risk factor for BCC and cSCC is solar UV radiation, which causes genetic and epigenetic alterations in keratinocytes. Similar gene mutations are noted already in sun-exposed normal skin emphasizing the role of the alterations in the tumor microenvironment in the progression of cSCC. Early events in cSCC progression are alterations in the composition of basement membrane and dermal extracellular matrix induced by influx of microbes, inflammatory cells and activated stromal fibroblasts. Activated fibroblasts promote inflammation and produce growth factors and proteolytic enzymes, including matrix metalloproteinases (MMPs). Transforming growth factor-β produced by tumor cells and fibroblasts induces the expression of MMPs by cSCC cells and promotes their invasion. Fibroblast-derived keratinocyte growth factor suppresses the malignant phenotype of cSCC cells by inhibiting the expression of several MMPs. These findings emphasize the importance of interplay of tumor and stromal cells in the progression of cSCC and BCC and suggest tumor microenvironment as a therapeutic target in cSCC and aggressive subtypes of BCC.

Skin proteomics - analysis of the extracellular matrix in health and disease

INTRODUCTION

The skin protects the human body from external insults and regulates water and temperature homeostasis. A highly developed extracellular matrix (ECM) supports the skin and instructs its cell functions. Reduced functionality of the ECM is often associated with skin diseases that cause physical impairment and also have implications on social interactions and quality of life of affected individuals.

AREAS COVERED

With a focus on the skin ECM we discuss how mass spectrometry (MS)-based proteomic approaches first contributed to establishing skin protein inventories and then facilitated elucidation of molecular functions and disease mechanisms.

EXPERT OPINION

MS-based proteomic approaches have significantly contributed to our understanding of skin pathophysiology, but also revealed the challenges in assessing the skin ECM. The numerous posttranslational modifications of ECM proteins, like glycosylation, crosslinking, oxidation, and proteolytic maturation in disease settings can be difficult to tackle and remain understudied. Increased ease of handling of LC-MS/MS systems and automated/streamlined data analysis pipelines together with the accompanying increased usage of LC-MS/MS approaches will ensure that in the coming years MS-based proteomic approaches will continue to play a vital part in skin disease research. They will facilitate the elucidation of molecular disease mechanisms and, ultimately, identification of new druggable targets.

Collagen XV, a multifaceted multiplexin present across tissues and species

Type XV collagen is a non-fibrillar collagen that is associated with basement membranes and belongs to the multiplexin subset of the collagen superfamily. Collagen XV was initially studied because of its sequence homology with collagen XVIII/endostatin whose anti-angiogenic and anti-tumorigenic properties were subjects of wide interest in the past years. But during the last fifteen years, collagen XV has gained growing attention with increasing number of studies that have attributed new functions to this widely distributed collagen/proteoglycan hybrid molecule. Despite the cumulative evidence of its functional pleiotropy and its evolutionary conserved function, no review compiling the current state of the art about collagen XV is currently available. Here, we thus provide the first comprehensive view of the knowledge gathered so far on the molecular structure, tissue distribution and functions of collagen XV in development, tissue homeostasis and disease with an evolutionary perspective. We hope that our review will open new roads for promising research on collagen XV in the coming years.

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Type XV collagen belongs to the multiplexin subset of the collagen superfamily.

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It is evolutionarily conserved collagen and associated with basement membranes.

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This collagen/proteoglycan hybrid molecule contains an anti-angiogenic restin domain.

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It has important functions in the cardiovascular and the neuromuscular systems.

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Its expression is dysregulated in various diseases including cancers.

p53-Regulated Long Noncoding RNA PRECSIT Promotes Progression of Cutaneous Squamous Cell Carcinoma via STAT3 Signaling

Long noncoding RNAs (lncRNAs) have emerged as putative biomarkers and therapeutic targets in cancer. The role of lncRNA LINC00346 in cutaneous squamous carcinoma (cSCC) was examined. The expression of LINC00346 was up-regulated in cSCC cells compared with normal human epidermal keratinocytes. Elevated expression of LINC00346 was noted in tumor cells in cSCC tissue sections in vivo, as compared with cSCC in situ, and actinic keratosis by RNA in situ hybridization; and the expression in seborrheic keratosis and normal skin was very low. Immunohistochemical analysis of cSCC tissue sections and functional assays of cSCC cells in culture showed that LINC00346 expression is down-regulated by p53. Knockdown of LINC00346 inhibited invasion of cSCC cells in culture and suppressed growth of human cSCC xenografts in vivo. Knockdown of LINC00346 inhibited expression of activated STAT3 and resulted in down-regulation of the expression of matrix metalloproteinase (MMP)-1, MMP-3, MMP-10, and MMP-13. Based on these observations LINC00346 was named p53 regulated carcinoma-associated STAT3-activating long intergenic non-protein coding transcript (PRECSIT). These results identify PRECSIT as a new p53-regulated lncRNA, which promotes progression of cSCC via STAT3 signaling.

Unripe peach (Prunus persica) extract ameliorates damage from UV irradiation and improved collagen XVIII expression in 3D skin model

INTRODUCTION

Collagen type XVIII regulates cellular activities of adjacent cells at the dermal-epidermal junction (DEJ). To investigate its possible changes during aging, we compared its mRNA levels and protein localization in skin samples from female participants aged 20-70 years old. In addition, we evaluated the beneficial effects of unripe peach extracts in a 3D skin model.

METHODS

Sun-exposed or sun-protected female skin samples were compared by DNA array or by immunohistochemistry for basement membrane components. To evaluate protective effects of fresh unripe peach extract, UV-B irradiated human 3D skin models were incubated in the presence or absence of the extract, followed by measurements of mRNA levels by real-time PCR, or by immunohistochemistry.

RESULTS

In aged skin samples, COL18A1 mRNA levels were lower and the protein localization exhibited less intensive signal by anti-collagen type XVIII immunostaining. As observed in the skin tissues, collagen type XVIII exists at the DEJ in the 3D skin model. Fresh unripe peach extract significantly improved mRNA levels and partially localizations of collagen type XVIII, suggesting that fresh unripe peach extract ameliorates DEJ damages caused by UV-B irradiation.

CONCLUSION

Collagen type XVIII and fresh unripe peach extract can be promising protective cosmetic strategies against skin aging.

Exploring the roles of MACIT and multiplexin collagens in stem cells and cancer

The extracellular matrix (ECM) is ubiquitously involved in neoplastic transformation, tumour growth and metastatic dissemination, and the interplay between tumour and stromal cells and the ECM is now considered crucial for the formation of a tumour-supporting microenvironment. The 28 different collagens (Col) form a major ECM protein family and display extraordinary functional diversity in tissue homeostasis as well as in pathological conditions, with functions ranging from structural support for tissues to regulatory binding activities and storage of biologically active cryptic domains releasable through ECM proteolysis. Two subfamilies of collagens, namely the plasma membrane-associated collagens with interrupted triple-helices (MACITs, including ColXIII, ColXXIII and ColXXV) and the basement membrane-associated collagens with multiple triple-helix domains with interruptions (multiplexins, including ColXV and ColXVIII), have highly interesting regulatory functions in tissue and organ development, as well as in various diseases, including cancer. An increasing, albeit yet sparse, data suggest that these collagens play crucial roles in conveying regulatory signals from the extracellular space to cells. We summarize here the current knowledge about MACITs and multiplexins as regulators of stemness and oncogenic processes, as well as their roles in influencing cell fate decisions in healthy and cancerous tissues. In addition, we present a bioinformatic analysis of the impacts of MACITs and multiplexins transcript levels on the prognosis of patients representing a wide array of malignant diseases, to aid future diagnostic and therapeutic efforts.

Complement System in Cutaneous Squamous Cell Carcinoma

Epidermal keratinocyte-derived cutaneous squamous cell carcinoma (cSCC) is the most common metastatic skin cancer with high mortality rates in the advanced stage. Chronic inflammation is a recognized risk factor for cSCC progression and the complement system, as a part of innate immunity, belongs to the microenvironment of tumors. The complement system is a double-edged sword in cancer, since complement activation is involved in anti-tumor cytotoxicity and immune responses, but it also promotes cancer progression directly and indirectly. Recently, the role of several complement components and inhibitors in the regulation of progression of cSCC has been shown. In this review, we will discuss the role of complement system components and inhibitors as biomarkers and potential new targets for therapeutic intervention in cSCC.

Uncommon Presentation of Metastatic Squamous Cell Carcinoma of the Skin and Treatment Challenges

Patient: Female, 80

Final Diagnosis: Metastatic squamous cell carcinoma of skin

Symptoms: Back pain • leg swelling • uti

Medication: —

Clinical Procedure: Immunotherapy

Specialty: Oncology

Long non-coding RNA PICSAR decreases adhesion and promotes migration of squamous carcinoma cells by downregulating α2β1 and α5β1 integrin expression

Long non-coding RNAs (lncRNAs) regulate various cellular processes, and they have emerged as potential biomarkers and therapeutic targets in cancer. We have previously characterized the oncogenic role of lncRNA PICSAR (p38 inhibited cutaneous squamous cell carcinoma associated lincRNA) in cutaneous squamous cell carcinoma (cSCC), the most common metastatic skin cancer. In this study, we show that knockdown of PICSAR in cSCC cells upregulates expression of α2, α5 and β1 integrins, resulting in increased cell adhesion and decreased cell migration on collagen I and fibronectin. In contrast, overexpression of PICSAR in cSCC cells downregulates expression of α2, α5 and β1 integrins on cell surface, resulting in decreased cell adhesion on collagen I and fibronectin and increased cell migration. These results demonstrate a novel mechanism for regulation of the expression of collagen and fibronectin binding integrins by lncRNA PICSAR, leading to altered adhesion and migration of cSCC cells.

This article has an associated First Person interview with the first author of the paper.

Summary: Long non-coding RNA PICSAR decreases adhesion and promotes migration of cutaneous squamous cell carcinoma cells by regulating the expression of collagen and fibronectin binding α2β1 and α5β1 integrins.

Matrix molecules and skin biology

An extracellular matrix (ECM) is a prerequisite for multicellular life. It is adapted to tissues and constantly undergoes changes to preserve microenvironmental homeostasis. The ECM acts as a structural scaffold that establishes tissue architecture and provides tensile strength. It has cell-instructive functions by serving as a reservoir and presenter of soluble agents, being directly signaling, integrating transmission of mechanical and biological cues, or serving as a co-factor potentiating signaling. The skin contains a highly developed, mechanically tough, but yet flexible ECM. The tissue-specific features of this ECM are largely attributed by minor ECM components. A large number of genetic and acquired ECM diseases with skin manifestations, provide an illustrative testament to the importance of correct assembly of the ECM for dermal homeostasis. Here, we will present the composition and features of the skin ECM during homeostasis and regeneration. We will discuss genetic and acquired ECM diseases affecting skin, and provide a short outlook to therapeutic strategies for them.

Photodynamic therapy corrects abnormal cancer-associated gene expression observed in actinic keratosis lesions and induces a remodeling effect in photodamaged skin

BACKGROUND

Actinic keratoses (AK) are proliferations of neoplastic keratinocytes in the epidermis resulting from cumulative exposure to ultraviolet radiation (UVR), which are liable to transform into squamous cell carcinoma (SCC). Organ Transplant Recipients (OTR) have an increased risk of developing SCC as a consequence of long-term immunosuppressive therapy. The aim of this study was to determine the molecular signature of AKs from OTR prior to treatment with methyl aminolevulinate-photodynamic therapy (MAL-PDT), and to assess what impact the treatment has on promoting remodeling of the photo-damaged skin.

METHODS

Seven patients were enrolled on a clinical trial to assess the effect of MAL-PDT with biopsies taken at screening prior to the first treatment session (week 1), and six weeks after completion of final treatment (week 18). Whole-genome gene expression analysis was carried out on skin biopsies isolated from an AK lesion, an area surrounding the lesion, and a non-sun exposed region of the body. Quantitative PCR was utilized to confirm the differential expression of key genes.

RESULTS

MAL-PDT treatment corrected abnormal proliferation-related gene profiles, corrected aberrantly expressed cancer-associated genes and induced expression of dermal extracellular matrix genes in photo-exposed skin.

CONCLUSION

The efficacy of the MAL-PDT on AK lesions was confirmed at whole-genome gene expression level. A transcriptional signature of remodeling, identified through assessing the effect of MAL-PDT on photodamaged skin, supports the use of MAL-PDT for treating photodamaged skin and field cancerized areas.

Proteoglycans remodeling in cancer: Underlying molecular mechanisms

Extracellular matrix is a highly dynamic macromolecular network. Proteoglycans are major components of extracellular matrix playing key roles in its structural organization and cell signaling contributing to the control of numerous normal and pathological processes. As multifunctional molecules, proteoglycans participate in various cell functions during morphogenesis, wound healing, inflammation and tumorigenesis. Their interactions with matrix effectors, cell surface receptors and enzymes enable them with unique properties. In malignancy, extensive remodeling of tumor stroma is associated with marked alterations in proteoglycans' expression and structural variability. Proteoglycans exert diverse functions in tumor stroma in a cell-specific and context-specific manner and they mainly contribute to the formation of a permissive provisional matrix for tumor growth affecting tissue organization, cell-cell and cell-matrix interactions and tumor cell signaling. Proteoglycans also modulate cancer cell phenotype and properties, the development of drug resistance and tumor stroma angiogenesis. This review summarizes the proteoglycans remodeling and their novel biological roles in malignancies with particular emphasis to the underlying molecular mechanisms.

Expression of claudin-11 by tumor cells in cutaneous squamous cell carcinoma is dependent on the activity of p38δ

The incidence of cutaneous squamous cell carcinoma (cSCC) is rapidly increasing, and the prognosis of patients with metastatic disease is poor. There is an emerging need to identify molecular markers for predicting aggressive behaviour of cSCC. Here, we have examined the role of tight junction (TJ) components in the progression of cSCC. The expression pattern of mRNAs for TJ components was determined with RNA sequencing and oligonucleotide array-based expression analysis from cSCC cell lines (n=8) and normal human epidermal keratinocytes (NHEK, n=5). The expression of CLDN11 was specifically elevated in primary cSCC cell lines (n=5), but low or absent in metastatic cSCC cell lines (n=3) and NHEKs. Claudin-11 was detected in cell-cell contacts of primary cSCC cells in culture by indirect immunofluorescence analysis. Analysis of a large panel of tissue samples from sporadic UV-induced cSCC (n=65), cSCC in situ (n=56), actinic keratoses (n=31), seborrhoeic keratoses (n=7) and normal skin (n=16) by immunohistochemistry showed specific staining for claudin-11 in intercellular junctions of keratinizing tumor cells in well and moderately differentiated cSCCs, whereas no staining for claudin-11 was detected in poorly differentiated tumors. The expression of claudin-11 in cSCC cells was dependent on the activity of p38δ MAPK and knock-down of claudin-11 enhanced cSCC cell invasion. These findings provide evidence for the role of claudin-11 in regulation of cSCC invasion and suggest loss of claudin-11 expression in tumor cells as a biomarker for advanced stage of cSCC.

Collagen XVIII in tissue homeostasis and dysregulation - Lessons learned from model organisms and human patients

Collagen XVIII is a ubiquitous basement membrane (BM) proteoglycan produced in three tissue-specific isoforms that differ in their N-terminal non-collagenous sequences, but share collagenous and C-terminal non-collagenous domains. The collagenous domain provides flexibility to the large collagen XVIII molecules on account of multiple interruptions in collagenous sequences. Each isoform has a complex multi-domain structure that endows it with an ability to perform various biological functions. The long isoform contains a frizzled-like (Fz) domain with Wnt-inhibiting activity and a unique domain of unknown function (DUF959), which is also present in the medium isoform. All three isoforms share an N-terminal laminin-G-like/thrombospondin-1 sequence whose specific functions still remain unconfirmed. The proteoglycan nature of the isoforms further increases the functional diversity of collagen XVIII. An anti-angiogenic domain termed endostatin resides in the C-terminus of collagen XVIII and is proteolytically cleaved from the parental molecule during the BM breakdown for example in the process of tumour progression. Recombinant endostatin can efficiently reduce tumour angiogenesis and growth in experimental models by inhibiting endothelial cell migration and proliferation or by inducing their death, but its efficacy against human cancers is still a subject of debate. Mutations in the COL18A1 gene result in Knobloch syndrome, a genetic disorder characterised mainly by severe eye defects and encephalocele and, occasionally, other symptoms. Studies with gene-modified mice have elucidated some aspects of this rare disease, highlighting in particular the importance of collagen XVIII in the development of the eye. Research with model organisms have also helped in determining other structural and biological functions of collagen XVIII, such as its requirement in the maintenance of BM integrity and its emerging roles in regulating cell survival, stem or progenitor cell maintenance and differentiation and inflammation. In this review, we summarise current knowledge on the properties and endogenous functions of collagen XVIII in normal situations and tissue dysregulation. When data is available, we discuss the functions of the distinct isoforms and their specific domains.

New perspectives on role of tumor microenvironment in progression of cutaneous squamous cell carcinoma

Epidermal keratinocyte-derived cutaneous squamous cell carcinoma (cSCC) is the most common metastatic skin cancer, and its incidence is increasing worldwide. Solar UV radiation is an important risk factor for cSCC and leads to genetic and epigenetic changes both in epidermal keratinocytes and dermal cells. Tumor cells in cutaneous cSCCs typically harbor several driver gene mutations, but epidermal keratinocytes in sun-exposed normal skin also contain mutations in these same genes. Therefore, alterations in the microenvironment of premalignant lesions are evidently required for their progression to invasive and metastatic cSCC. For example, alterations in the composition of basement membrane and dermal extracellular matrix are early events in cSCC progression. The presence of microbial structures and the influx of inflammatory cells promote the secretion of proteases, which in turn regulate the availability of growth factors, cytokines, and chemokines and thus influence the growth and invasion of cSCC. Together, these observations emphasize the role of the tumor microenvironment in the progression of cSCC and identify it as a novel therapeutic target in cSCC and other malignant tumors. Graphical abstract Tumor-stroma interactions in the progression of cutaneous squamous cell carcinoma (cSCC). Epidermal layer is separated by a well-organized basement membrane (BM) from the dermal layer. UV radiation, other environmental insults, and aging target both epidermal keratinocytes and dermal fibroblasts and lead to genetic and epigenetic changes in these cells. In addition, epidermal keratinocytes in normal sun-exposed skin harbor several mutations in the cSCC driver genes. During transition to premalignant actinic keratosis (AK), the differentiation of keratinocytes is disturbed resulting in a neoplastic epithelium with hyperplastic cells. Expression of proteinases, such as matrix metalloproteinases (MMP) by neoplastic cells and activated stromal fibroblasts and macrophages is induced in AK, and collagen XV and XVIII are lost from the dermal BM. Furthermore, inflammatory cells accumulate at the site of the hyperplastic epithelium. During a later stage of cSCC progression, the number of inflammatory cells increases, and the expression of complement components and inhibitors by tumor cells is induced (CFI complement factor I, CFH complement factor H, FHL-1 Factor H-like protein 1). In addition to MMPs, activated fibroblasts also produce growth factors and promote inflammation, growth, and invasion of tumor cells.