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-ß (PDGFRß) expression was associated with metastasis risk of primary cSCCs. High expression of PDGFRß and periostin correlated with poor prognosis. Multimarker combination defined CAF subset, PDGFRα-/PDGFRß+/FAP+, was associated with invasion and metastasis, and independently predicted poor disease-specific survival. These results identify high PDGFRß expression alone and multimarker combination PDGFRα-/PDGFRß+/FAP+ by CAFs as potential biomarkers for risk of metastasis and poor prognosis.

Immunomodulatory Synthetic Glycocluster Molecule Prevents Melanoma Growth in vivo.

Triacedimannose (TADM) is a synthetic trivalent acetylated glycocluster and a transmembrane macrophage activator independent of the mannose receptor. TADM induces Th1-type immune responses and suppresses Th2-type cytokines in acute and chronic allergic inflammation models in vivo. We, therefore, wanted to test whether TADM could also facilitate anti-tumour tissue responses similar to what has been observed for the immune checkpoint inhibitors, such as anti-PD-1 and anti-CTLA-4. A syngeneic mouse melanoma model was selected since metastatic melanoma has been successfully targeted by checkpoint inhibitors in the clinic. TADM inhibited the growth of B16 mouse melanoma tumours at levels comparable to an anti-PD-1 antibody. TADM-treated tumours encompassed significantly more apoptotic cells as measured by TUNEL staining, and interferon-gamma (IFN-γ) expression was increased in the spleens of TADM-treated mice compared to untreated controls. TADM-treated mice also demonstrated increased Ly6C low monocytes and neutrophils in the spleens. However, TADM-treated tumours showed no discernible differences in infiltrating immune cells. TADM can alone suppress the growth of melanoma tumours. TADM likely activates M1 type macrophages, type N1 neutrophils, and CD8+ and Th1 T cells, suppressing the type 2 immune response milieu of melanoma tumour with a strong type 1 immune response.

Long noncoding RNA plasmacytoma variant translocation 1 is overexpressed in cutaneous squamous cell carcinoma and exon 2 is critical for its oncogenicity.

BACKGROUND: Cutaneous squamous cell carcinoma (cSCC) is one of the most common and fastest increasing forms of cancer worldwide with metastatic potential. Long noncoding RNAs (lncRNAs) are a group of RNA molecules with essential regulatory functions in both physiological and pathological processes. OBJECTIVES: To investigate the function and mode of action of lncRNA plasmacytoma variant translocation 1 (PVT1) in cSCC. METHODS: Quantitative reverse transcriptase polymerase chain reaction and single-molecule in situ hybridization were used to quantify the expression level of PVT1 in normal skin, premalignant skin lesions, actinic keratosis (AK) and primary and metastatic cSCCs. The function of PVT1 in cSCC was investigated both in vivo (tumour xenografts) and in vitro (competitive cell growth assay, 5-ethynyl-2'-deoxyuridine incorporation assay, colony formation assay and tumour spheroid formation assay) upon CRISPR-Cas9-mediated knockout of the entire PVT1 locus, the knockout of exon 2 of PVT1, and locked nucleic acid (LNA) gapmer-mediated PVT1 knockdown. RNA sequencing analysis was conducted to identify genes and processes regulated by PVT1. RESULTS: We identified PVT1 as a lncRNA upregulated in cSCC in situ and cSCC, associated with the malignant phenotype of cSCC. We showed that the expression of PVT1 in cSCC was regulated by MYC. Both CRISPR-Cas9 deletion of the entire PVT1 locus and LNA gapmer-mediated knockdown of PVT1 transcript impaired the malignant behaviour of cSCC cells, suggesting that PVT1 is an oncogenic transcript in cSCC. Furthermore, knockout of PVT1 exon 2 inhibited cSCC tumour growth both in vivo and in vitro, demonstrating that exon 2 is a critical element for the oncogenic role of PVT1. Mechanistically, we showed that PVT1 was localized in the cell nucleus and its deletion resulted in cellular senescence, increased cyclin-dependent kinase inhibitor 1 (p21/CDKN1A) expression and cell cycle arrest. CONCLUSIONS: Our study revealed a previously unrecognized role for exon 2 of PVT1 in its oncogenic role and that PVT1 suppresses cellular senescence in cSCC. PVT1 may be a potential biomarker and therapeutic target in cSCC.

Consensus statement on the diagnosis and treatment of sclerosing diseases of the skin, Part 2: Scleromyxoedema and scleroedema.

The term 'sclerosing diseases of the skin' comprises specific dermatological entities, which have fibrotic changes of the skin in common. These diseases mostly manifest in different clinical subtypes according to cutaneous and extracutaneous involvement and can sometimes be difficult to distinguish from each other. The present consensus provides an update to the 2017 European Dermatology Forum Guidelines, focusing on characteristic clinical and histopathological features, diagnostic scores and the serum autoantibodies most useful for differential diagnosis. In addition, updated strategies for the first- and advanced-line therapy of sclerosing skin diseases are addressed in detail. Part 2 of this consensus provides clinicians with an overview of the diagnosis and treatment of scleromyxoedema and scleroedema (of Buschke).

Retrospective, Registry-based, Cohort Investigation of Clinical Outcomes in Patients with Cutaneous Squamous Cell Carcinoma and Basal Cell Carcinoma in Finland.

Most cases of keratinocyte cancer can be treated effectively with surgery. However, survival is reduced in patients with advanced disease. This retrospective cohort study evaluated overall survival of patients with invasive keratinocyte cancers, and high-risk features for progression of the disease and mortality in Finnish patients in a real-world setting. A total of 43,143 patients with keratinocyte cancer types of basal cell carcinoma and 10,380 with cutaneous squamous cell carcinoma were identified nationwide. More detailed patient records were available for a subset of patients (basal cell carcinoma n = 5,020 and cutaneous squamous cell carcinoma n = 1,482) from a regional database. Fifty percent of patients with advanced cutaneous squamous cell carcinoma died approximately 4.5 years after diagnosis. Multivariable models suggested that risk factors for keratinocyte cancer progression were male sex, presence of comorbidities, immunosuppression, and pre-cancerous lesions, while risk factors for disease-specific mortality were advanced disease stage with immunosuppression, other malignancies, and consecutive surgical excisions. These results suggest that identifying patient and tumour factors associated with poor disease outcome could be important when determining appropriate treatment and follow-up; however, further studies are necessary.

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.

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-ß 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.

Complement factor I upregulates expression of matrix metalloproteinase-13 and -2 and promotes invasion of cutaneous squamous carcinoma cells.

The incidence of cutaneous squamous cell carcinoma (cSCC) is increasing globally. Here, we have studied the functional role of complement factor I (CFI) in the progression of cSCC. CFI was knocked down in cSCC cells, and RNA-seq analysis was performed. Significant downregulation of genes in IPA biofunction categories Proliferation of cells and Growth of malignant tumor, in Gene Ontology (GO) terms Metallopeptidase activity and Extracellular matrix component, as well as Reactome Degradation of extracellular matrix was detected after CFI knockdown. Further analysis of the latter three networks, revealed downregulation of several genes coding for invasion-associated matrix metalloproteinases (MMPs) after CFI knockdown. The downregulation of MMP-13 and MMP-2 was confirmed at mRNA, protein and tissue levels by qRT-qPCR, Western blot and immunohistochemistry, respectively. Knockdown of CFI decreased the invasion of cSCC cells through type I collagen. Overexpression of CFI in cSCC cells resulted in enhanced production of MMP-13 and MMP-2 and increased invasion through type I collagen and Matrigel, and in increased ERK1/2 activation and cell proliferation. Altogether, these findings identify a novel mechanism of action of CFI in upregulation of MMP-13 and MMP-2 expression and cSCC invasion. These results identify CFI as a prospective molecular marker for invasion and metastasis of cSCC.

Different expression of BRAFV600E, ALK and PD-L1 in melanoma in children and adolescents: a nationwide retrospective study in Finland in 1990-2014.

BACKGROUND: Pediatric melanoma may have a different biological background and more favorable prognosis compared with melanoma in adults. The aim of this study was to investigate melanoma in children and adolescents in the Finnish population in terms of incidence, clinical course, treatment, prognosis and BRAFV600E-, ALK- and PD-L1-positivity of the primary tumors. MATERIALS AND METHODS: Primary tumor samples and clinical records of all patients aged 0-19 years diagnosed with cutaneous melanoma in Finland in 1990-2014 were collected using the Finnish Cancer Registry database, Finnish hospitals and private pathology laboratories. BRAFV600E, ALK and PD-L1 were analyzed from 54 primary tumors and BRAFV600E from six metastasis samples. RESULTS: A total of 122 patients diagnosed with cutaneous melanoma were retrieved from the Cancer Registry database. The primary tumor samples of 73 patients were obtained for the review, and 56 cases were included in the study. The incidence of pediatric melanoma increased from 0.02 to 0.1/100 000 during the period 1990-2014. Spitzoid melanoma was the most common subtype (66%). The 10-year cancer-specific survival (CSS) was 88.7% in all patients. The 10-year-CSS did not differ in SLNB-positive or -negative groups. BRAFV600E was positive in 48%, ALK in 9% and PD-L1 in 2% of the tumors. BRAFV600E mutation was associated with 83% of melanoma deaths. CONCLUSIONS: Young melanoma patients had more favorable prognosis and a different staining profile for BRAFV600E, ALK, and PD-L1 in primary tumor than reported in adults. SLNB status was not an indicator for survival. BRAFV600E-positive patients have worse prognosis and could benefit from surveillance and treatment similarly to adults.

Signaling pathways in human osteoclasts differentiation: ERK1/2 as a key player.

Little is known about the signaling pathways involved in the differentiation of human osteoclasts. The present study evaluated the roles of the Ras/PI3K/Akt/mTOR, Ras/Raf/MEK1/2/ERK1/2, calcium-PKC, and p38 signaling pathways in human osteoclast differentiation. Mononuclear cells were isolated from the peripheral blood of control persons and patients with neurofibromatosis 1 (NF1), and the cells were differentiated into osteoclasts in the presence of signaling pathway inhibitors. Osteoclast differentiation was assessed using tartrate-resistant acid phosphatase 5B. Inhibition of most signaling pathways with chemical inhibitors decreased the number of human osteoclasts and disrupted F-actin ring formation, while the inhibition of p38 resulted in an increased number of osteoclasts, which is a finding contradictory to previous murine studies. However, the p38 inhibition did not increase the bone resorption capacity of the cells. Ras-inhibitor FTS increased osteoclastogenesis in samples from control persons, but an inhibitory effect was observed in NF1 samples. Inhibition of MEK, PI3K, and mTOR reduced markedly the number of NF1-deficient osteoclasts, but no effect was observed in control samples. Western blot analyses showed that the changes in the phosphorylation of ERK1/2 correlated with the number of osteoclasts. Our results highlight the fact that osteoclastogenesis is regulated by multiple interacting signaling pathways and emphasize that murine and human findings related to osteoclastogenesis are not necessarily equivalent.

Long non-coding RNAs in cutaneous biology and keratinocyte carcinomas.

Long non-coding RNAs (lncRNAs) are a largely uncharacterized group of non-coding RNAs with diverse regulatory roles in various biological processes. Recent observations have elucidated the functional roles of lncRNAs in cutaneous biology, e.g. in proliferation and differentiation of epidermal keratinocytes and in cutaneous wound repair. Furthermore, the role of lncRNAs in keratinocyte-derived skin cancers is emerging, especially in cutaneous squamous cell carcinoma (cSCC), which presents a significant burden to health care services worldwide and causes high mortality as metastatic disease. Elucidation of the functions of keratinocyte-specific lncRNAs will improve understanding of the molecular pathogenesis of epidermal disorders and skin cancers and can be exploited in development of new diagnostic and therapeutic applications for keratinocyte carcinomas. In this review, we summarize the current evidence of functionally important lncRNAs in cutaneous biology and in keratinocyte carcinomas.

Risk Factors and Prognosis for Metastatic Cutaneous Squamous Cell Carcinoma: A Cohort Study.

Cutaneous squamous cell carcinoma (cSCC) has metastatic potential. The aims of this study were to identify the risk factors for metastasis of primary cSCC and for poor prognosis in metastatic cSCC. Retrospective primary tumour cohorts of metastatic cSCCs (n = 85) and non-metastatic cSCCs (n = 218) were analysed. The mean annual rate of metastasis for primary cSCCs was 2.28%. In 49.4% of patients with metastatic cSCC, metastasis was detected within 6 months of diagnosis of the primary cSCC. There was no prior history of cSCC in 84.7% of metastatic cSCCs. Risk factors for metastasis included Clark's level 5, tumour diameter 20-29.9 mm, age at diagnosis < 50 or 70-79 years, and location on lower lip or forehead. A reduced risk of metastasis correlated with: isosorbide mono-/di-nitrate and/or aspirin use; comorbidity with actinic keratosis or basal cell carcinoma; and actinic keratosis or cSCC in situ as part of, or confirmedly preceding, primary cSCC. Poor prognosis in metastatic cSCC correlated significantly with ≥3 nodal metastases and extranodal extension of metastasis. These results characterize new risk factors for metastatic cSCC.

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.

Complement Component C3 and Complement Factor B Promote Growth of Cutaneous Squamous Cell Carcinoma.

Cutaneous squamous cell carcinoma (cSCC) is one of the most common metastatic skin cancers with increasing incidence. We examined the roles of complement component C3 and complement factor B (CFB) in the growth of cSCC. Analysis of cSCC cell lines (n = 8) and normal human epidermal keratinocytes (n = 11) with real-time quantitative PCR and Western blotting revealed up-regulation of C3 and CFB expression in cSCC cells. Immunohistochemical staining revealed stronger tumor cell-specific labeling for C3 and CFB in invasive cSCCs (n = 71) and recessive dystrophic epidermolysis bullosa-associated cSCCs (n = 11) than in cSCC in situ (n = 69), actinic keratoses (n = 63), and normal skin (n = 5). Significant up-regulation of C3 and CFB mRNA expression was noted in chemically induced mouse cSCCs, compared to benign papillomas. Knockdown of C3 and CFB expression inhibited migration and proliferation of cSCC cells and resulted in potent inhibition of extracellular signal-regulated kinase 1/2 activation. Knockdown of C3 and CFB markedly inhibited growth of human cSCC xenograft tumors in vivo. These results provide evidence for the roles of C3 and CFB in the development of cSCC and identify them as biomarkers and potential therapeutic targets in this metastatic skin cancer.

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.

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.

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.

As the second most common skin malignancy, cutaneous squamous cell carcinoma (cSCC) is an increasing health concern, while its pathogenesis at molecular level remains largely unknown. We studied the expression and localisation of two homologous basement membrane (BM) collagens, types XV and XVIII, at different stages of cSCC. These collagens are involved in angiogenesis and tumorigenesis, but their role in cancer development is incompletely understood. Quantitative RT-PCR analysis revealed upregulation of collagen XVIII, but not collagen XV, in primary cSCC cells in comparison with normal human epidermal keratinocytes. In addition, the Ha-ras-transformed invasive cell line II-4 expressed high levels of collagen XVIII mRNA, indicating upregulation in the course of malignant transformation. Immunohistochemical analyses of a large human tissue microarray material showed that collagen XVIII is expressed by tumor cells from grade 1 onwards, while keratinocytes in normal skin and in premalignant lesions showed negative staining for it. Collagen XV appeared instead as deposits in the tumor stroma. Our findings in human cSCCs and in mouse cSCCs from the DMBA-TPA skin carcinogenesis model showed that collagen XVIII, but not collagen XV or the BM markers collagen IV or laminin, was selectively reduced in the tumor vasculature, and this decrease associated significantly with cancer progression. Our results demonstrate that collagens XV and XVIII are expressed in different sites of cSCC and may contribute in a distinct manner to processes related to cSCC tumorigenesis, identifying these collagens as potential biomarkers in the disease.

Matrix metalloproteinases in inflammation.

BACKGROUND: Matrix metalloproteinases (MMPs) are a family of ubiquitously expressed zinc-dependent endopeptidases with broad substrate specificity and strictly regulated tissue specific expression. They are expressed in physiological situations and pathological conditions involving inflammation. MMPs regulate several functions related to inflammation including bioavailability and activity of inflammatory cytokines and chemokines. There is also evidence that MMPs regulate inflammation in tumor microenvironment, which plays an important role in cancer progression. SCOPE OF REVIEW: Here, we discuss the current view on the role of MMPs in the regulation of inflammation. MAJOR CONCLUSIONS: MMPs modulate inflammation by regulating bioavailability and activity of cytokines, chemokines, and growth factors, as well as integrity of physical tissue barriers. MMPs are also involved in immune evasion of tumor cells and in regulation of inflammation in tumor microenvironment. GENERAL SIGNIFICANCE: There is increasing evidence for non-matrix substrates of MMPs that are related to regulation of inflammatory processes. New methods have been employed for identification of the substrates of MMPs in inflammatory processes in vivo. Detailed information on the substrates of MMPs may offer more specific and effective ways of inhibiting MMP function by blocking the cleavage site in substrate or by inhibition of the bioactivity of the substrate. It is expected, that more precise information on the MMP-substrate interaction may offer novel strategies for therapeutic intervention in inflammatory diseases and cancer without blocking beneficial actions of MMPs. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties.

C1s targeting antibodies inhibit the growth of cutaneous squamous carcinoma cells.

Cutaneous squamous cell carcinoma (cSCC) is the most common metastatic skin cancer. The incidence of cSCC is increasing globally and the prognosis of metastatic disease is poor. Currently there are no specific targeted therapies for advanced or metastatic cSCC. We have previously shown abundant expression of the complement classical pathway C1 complex components, serine proteases C1r and C1s in tumor cells in invasive cSCCs in vivo, whereas the expression of C1r and C1s was lower in cSCCs in situ, actinic keratoses and in normal skin. We have also shown that knockdown of C1s expression results in decreased viability and growth of cSCC cells by promoting apoptosis both in culture and in vivo. Here, we have studied the effect of specific IgG2a mouse monoclonal antibodies TNT003 and TNT005 targeting human C1s in five primary non-metastatic and three metastatic cSCC cell lines that show intracellular expression of C1s and secretion of C1s into the cell culture media. Treatment of cSCC cells with TNT003 and TNT005 significantly inhibited their growth and viability and promoted apoptosis of cSCC cells. These data indicate that TNT003 and TNT005 inhibit cSCC cell growth in culture and warrant further investigation of C1s targeted inhibition in additional in vitro and in vivo models of cSCC.

ADAMTS5: A New Player in the Vascular Field.

This Commentary highlights the article by Kumar et al, showing that ADAMTS5 suppresses tumor growth by down-regulating other angiogenesis-inducing factors in addition to VEGF and that the central TSR1 domain of ADAMTS5 is required in this function.