Reduced Expression of Insulin-Like Growth Factor-Binding Protein-3 (IGFBP-3) in Squamous Cell Carcinoma Complicating Recessive Dystrophic Epidermolysis Bullosa

The tumor suppressor kinase DAPK3 drives tumor-intrinsic immunity through the STING-IFN-β pathway

Evasion of host immunity is a hallmark of cancer; however, mechanisms linking oncogenic mutations and immune escape are incompletely understood. Through loss-of-function screening of 1,001 tumor suppressor genes, we identified death-associated protein kinase 3 (DAPK3) as a previously unrecognized driver of anti-tumor immunity through the stimulator of interferon genes (STING) pathway of cytosolic DNA sensing. Loss of DAPK3 expression or kinase activity impaired STING activation and interferon (IFN)-β-stimulated gene induction. DAPK3 deficiency in IFN-β-producing tumors drove rapid growth and reduced infiltration of CD103+CD8α+ dendritic cells and cytotoxic lymphocytes, attenuating the response to cancer chemo-immunotherapy. Mechanistically, DAPK3 coordinated post-translational modification of STING. In unstimulated cells, DAPK3 inhibited STING K48-linked poly-ubiquitination and proteasome-mediated degradation. After cGAMP stimulation, DAPK3 was required for STING K63-linked poly-ubiquitination and STING-TANK-binding kinase 1 interaction. Comprehensive phospho-proteomics uncovered a DAPK3-specific phospho-site on the E3 ligase LMO7, critical for LMO7-STING interaction and STING K63-linked poly-ubiquitination. Thus, DAPK3 is an essential kinase for STING activation that drives tumor-intrinsic innate immunity and tumor immune surveillance.

Impairment of cytokinesis by cancer-associated DAPK3 mutations

Death-associated protein kinase 3 (DAPK3), a member of the DAPK family, contributes to cytokinesis by phosphorylating myosin II regulatory light chain (MRLC). Missense mutations in DAPK3, T112M, D161N, and P216S, were observed in the lung, colon, and cervical cancers, respectively, but the effects of these mutations on cytokinesis remain unclear. Here, we show that cells expressing EGFP-DAPK3-T112M, -D161N, or -P216S exhibited reduced rates of cytokinesis, with an increased ratio of multinucleated cells. In addition, these cells exhibited reduced levels of phosphorylated MRLC at the contractile ring. Collectively, our data demonstrates that cancer-associated DAPK3 mutations impair cytokinesis by reducing phosphorylated MRLC.

Restoration of DAP Kinase Tumor Suppressor Function: A Therapeutic Strategy to Selectively Induce Apoptosis in Cancer Cells Using Immunokinase Fusion Proteins

Targeted cancer immunotherapy is designed to selectively eliminate tumor cells without harming the surrounding healthy tissues. The death-associated protein kinases (DAPk) are a family of proapoptotic proteins that play a vital role in the regulation of cellular process and have been identified as positive mediators of apoptosis via extrinsic and intrinsic death-regulating signaling pathways. Tumor suppressor activities have been shown for DAPk1 and DAPk2 and they are downregulated in e.g., Hodgkin's (HL) and B cell lymphoma (CLL), respectively. Here, we review a targeted therapeutic approach which involves reconstitution of DAPks by the generation of immunokinase fusion proteins. These recombinant proteins consist of a disease-specific ligand fused to a modified version of DAPk1 or DAPk2. HL was targeted via CD30 and B-CLL via CD22 cell surface antigens.

Death-associated protein kinase 3 controls the tumor progression of A549 cells through ERK MAPK/c-Myc signaling

Death-associated protein kinases (DAPKs) are members of the serine/threonine protein kinase family, which regulate cell death. Although DAPK3 has been implicated as a tumor suppressor, a recent study revealed an oncogenic role of DAPK3. However, the role of DAPK3 in non-small cell lung cancer (NSCLC) remains unclear. Therefore, we examined whether DAPK3 controls the progression of NSCLC using the NSCLC cell line, A549. We generated A549 cells stably expressing small hairpin RNA (shRNA) targeting DAPK3. In the A549 cells, the protein level of DAPK3 was decreased and the cell proliferation was inhibited. DAPK3 knockdown caused G1/G0 cell cycle arrest as assessed by flow cytometric assay and reduced cyclin D1 expression in A549 cells. Phosphorylation of ERK and c-Myc, but not Akt and JNK, was inhibited by DAPK3 knockdown. Cell migration and invasion were also inhibited by DAPK3 knockdown as determined by a Boyden chamber assay and an invasion assay, respectively. Moreover, DAPK3 knockdown inhibited anchorage-independent cell growth as determined by soft-agar colony formation assay. In a mouse xenograft model, tumors derived from DAPK3-knockdown cells exhibited reduced tumor growth. The present results demonstrated for the first time that DAPK3 controls proliferation, migration, invasion, soft‑agar colony formation and tumor growth through activation of ERK/c-Myc signaling in A549 cells. These findings indicate that DAPK3 may be a novel target for the treatment of NSCLC.

Zipper-interacting protein kinase promotes epithelial-mesenchymal transition, invasion and metastasis through AKT and NF-kB signaling and is associated with metastasis and poor prognosis in gastric cancer patients

Zipper-interacting Protein Kinase (ZIPK) belongs to the death-associated protein kinase family. ZIPK has been characterized as a tumor suppressor in various tumors, including gastric cancer. On the other hand, ZIPK also promotes cell survival. In this study, both in vitro and in vivo assays indicated that ZIPK promoted cell growth, proliferation, migration, invasion, tumor formation and metastasis in nude mice. ZIPK induced epithelial-mesenchymal transition (EMT) with increasing expression of β-catenin, mesenchymal markers, Snail and Slug, and with decreasing expression of E-cadherin. Furthermore, ZIPK activated the AKT/IκB/NF-κB pathway, which can promote EMT and metastasis. Additionally, ZIPK expression was detected in human primary gastric cancer and their matched metastatic lymph node samples by immunohistochemistry. Increased expression of ZIPK in lymph node metastases was significantly associated with stage VI and abdominal organ invasion. Survival analysis revealed that patients with increased ZIPK expression in metastatic lymph nodes had poor disease-specific survival. Taken together, our study reveals that ZIPK is a pro-oncogenic factor, which promotes cancer metastasis.

[Parallels between wound healing, chronic inflammatory skin diseases and neoplasia: clinical aspects]

Chronic wounds, scars, burns and recalcitrant chronic inflammatory skin lesions can give rise to malignancy. These neoplasias are usually squamous cell carcinomas but basal cell carcinomas can also develop. Tumorigenesis is a severe complication of chronic ulcers as well as certain inflammatory skin diseases; early diagnosis is critical for prognosis. This article describes parallels between wound healing, chronic inflammatory skin diseases and carcinogenesis and provides advice on practical aspects of diagnosis and therapy.

Type VII collagen regulates expression of OATP1B3, promotes front-to-rear polarity and increases structural organisation in 3D spheroid cultures of RDEB tumour keratinocytes

Type VII collagen is the main component of anchoring fibrils, structures that are integral to basement membrane homeostasis in skin. Mutations in the gene encoding type VII collagen COL7A1 cause recessive dystrophic epidermolysis bullosa (RDEB) an inherited skin blistering condition complicated by frequent aggressive cutaneous squamous cell carcinoma (cSCC). OATP1B3, which is encoded by the gene SLCO1B3, is a member of the OATP (organic anion transporting polypeptide) superfamily responsible for transporting a wide range of endogenous and xenobiotic compounds. OATP1B3 expression is limited to the liver in healthy tissues, but is frequently detected in multiple cancer types and is reported to be associated with differing clinical outcome. The mechanism and functional significance of tumour-specific expression of OATP1B3 has yet to be determined. Here, we identify SLCO1B3 expression in tumour keratinocytes isolated from RDEB and UV-induced cSCC and demonstrate that SLCO1B3 expression and promoter activity are modulated by type VII collagen. We show that reduction of SLCO1B3 expression upon expression of full-length type VII collagen in RDEB cSCC coincides with acquisition of front-to-rear polarity and increased organisation of 3D spheroid cultures. In addition, we show that type VII collagen positively regulates the abundance of markers implicated in cellular polarity, namely ELMO2, PAR3, E-cadherin, B-catenin, ITGA6 and Ln332.

Fibroblast-derived dermal matrix drives development of aggressive cutaneous squamous cell carcinoma in patients with recessive dystrophic epidermolysis bullosa

Patients with the genetic skin blistering disease recessive dystrophic epidermolysis bullosa (RDEB) develop aggressive cutaneous squamous cell carcinoma (cSCC). Metastasis leading to mortality is greater in RDEB than in other patient groups with cSCC. Here we investigate the dermal component in RDEB using mRNA expression profiling to compare cultured fibroblasts isolated from individuals without cSCC and directly from tumor matrix in RDEB and non-RDEB samples. Although gene expression of RDEB normal skin fibroblasts resembled that of cancer-associated fibroblasts, RDEB cancer-associated fibroblasts exhibited a distinct and divergent gene expression profile, with a large proportion of the differentially expressed genes involved in matrix and cell adhesion. RDEB cancer-associated fibroblasts conferred increased adhesion and invasion to tumor and nontumor keratinocytes. Reduction of COL7A1, the defective gene in RDEB, in normal dermal fibroblasts led to increased type XII collagen, thrombospondin-1, and Wnt-5A, while reexpression of wild type COL7A1 in RDEB fibroblasts decreased type XII collagen, thrombospondin-1, and Wnt-5A expression, reduced tumor cell invasion in organotypic culture, and restricted tumor growth in vivo. Overall, our findings show that matrix composition in patients with RDEB is a permissive environment for tumor development, and type VII collagen directly regulates the composition of matrix proteins secreted by dermal and cancer-associated fibroblasts.

Matrix metalloproteinase-7 activates heparin-binding epidermal growth factor-like growth factor in cutaneous squamous cell carcinoma

BACKGROUND

Tumour-specific expression of matrix metalloproteinase (MMP)-7 has been noted in cutaneous squamous cell carcinomas (SCCs) in patients with recessive dystrophic epidermolysis bullosa (RDEB).

OBJECTIVES

To examine the potential role of MMP-7 in shedding of heparin-binding epidermal growth factor-like growth factor (HB-EGF) in RDEB-associated and sporadic SCCs.

METHODS

Tissue microarrays of RDEB-associated SCC (n = 20), non-EB SCC (n = 60) and Bowen disease (n = 28) were immunostained for MMP-7, CD44 variant 3 (CD44v3) and HB-EGF. Shedding of HB-EGF was studied in vitro using two cutaneous SCC cell lines.

RESULTS

Immunohistochemical analysis showed that HB-EGF was absent in tumour cells when MMP-7 and CD44v3 colocalized, and that the absence of HB-EGF was more pronounced in RDEB-associated SCCs than in non-EB SCCs. The loss of HB-EGF in MMP-7-CD44v3 double-positive areas was interpreted to indicate shedding and activation of HB-EGF; this was also detected in Bowen disease indicating its importance in the early phase of SCC development. Specific knockdown of MMP-7 expression in human cutaneous SCC cells by small interfering RNA inhibited shedding of HB-EGF and resulted in diminished activation of the EGF receptor (EGFR) and ERK1/2, and in reduced proliferation of SCC cells.

CONCLUSIONS

These findings provide evidence for the role of MMP-7 in promoting the growth of cutaneous SCCs by shedding HB-EGF, and identify EGFR signalling as a potential therapeutic target in RDEB-associated SCC and unresectable sporadic cutaneous SCC.

Treatment of skin cancers in epidermolysis bullosa

Squamous cell carcinomas (SCCs) are highly aggressive in patients with epidermolysis bullosa (EB). Non-ultraviolet-related SCCs are the leading cause of death in patients with recessive dystrophic EB, particularly recessive dystrophic EB-generalized severe subtype (RDEB-GS). The mechanism of SCC development in patients with RDEB continues to be investigated and several theories have been reported in the literature.

Inherited epidermolysis bullosa: recent basic and clinical advances

PURPOSE OF REVIEW

This review highlights key findings, both clinical and basic, that have been published in the field of inherited epidermolysis bullosa within the past few years.

RECENT FINDINGS

New epidermolysis bullosa phenotypes, genotypes and modes of transmission have been identified, resulting in a revised classification system. Detailed evidence-based data are now available on the risk of extracutaneous complications in each of the major epidermolysis bullosa subtypes. Studies are now underway to try to better explain the biological aggressiveness of squamous cell carcinomas arising in epidermolysis bullosa skin. Cell and animal models have been refined and used to ascertain the feasibility of gene replacement therapy, stem cell transplantation, and treatment with injected allogeneic fibroblasts or recombinant type VII collagen. As a result, clinical trials are now being pursued to test each of these in humans.

SUMMARY

Epidermolysis bullosa is caused by mutations in at least 14 genes, leading to a broad spectrum of entities, each of which has its own relative risk for the development of specific extracutaneous complications and/or premature death. Intensive research, both basic and clinical, is bringing us closer to more effective treatments and possibly even a cure.

Progress in epidermolysis bullosa research: toward treatment and cure

Epidermolysis bullosa (EB) is a clinically and genetically heterogeneous group of blistering disorders with considerable morbidity and mortality. Two decades ago, EB entered the molecular era with the identification of mutations in specific genes expressed within the cutaneous basement membrane zone; mutations in 14 genes have now been identified. This progress has now formed the basis for development of novel molecular therapies for this disease.

Understanding the pathogenesis of recessive dystrophic epidermolysis bullosa squamous cell carcinoma

Patients with recessive dystrophic epidermolysis bullosa develop numerous life-threatening skin cancers. The reasons for this remain unclear. Parallels exist with other scarring skin conditions, such as Marjolin ulcer. We summarize observational and experimental data and discuss proposed theories for the development of such aggressive skin cancers. A context-driven situation seems to be emerging, but more focused research is required to elucidate the pathogenesis of epidermolysis bullosa-associated squamous cell carcinoma.

Increased invasive behaviour in cutaneous squamous cell carcinoma with loss of basement-membrane type VII collagen

Type VII collagen (ColVII) is the main component of anchoring fibrils, attachment structures within the lamina densa of the basement membrane that are responsible for attachment of the epidermis to the dermis in skin. Mutations in the human ColVII gene, COL7A1, cause the severe inherited blistering disorder recessive dystrophic epidermolysis bullosa (RDEB) affecting skin and mucosae, associated with a greatly increased risk of skin cancer. In this study, we examined the effect of loss of ColVII on squamous cell carcinoma (SCC) tumourigenesis using RNAi in a 3D organotypic skin model. Our findings suggest that loss of ColVII promotes SCC migration and invasion as well as regulating cell differentiation with evidence for concomitant promotion of epithelial-mesenchymal transition (EMT). Immunostaining of RDEB skin and a tissue array of sporadic cutaneous SCCs confirmed that loss of ColVII correlates with decreased involucrin expression in vivo. Gene-expression-array data and immunostaining demonstrated that loss of ColVII increases expression of the chemokine ligand-receptor CXCL10-CXCR3 and downstream-associated PLC signalling, which might contribute to the increased metastatic potential of SCCs with reduced or absent ColVII expression. Together, these findings may explain the aggressive behaviour of SCCs in RDEB patients and may also be relevant to non-RDEB skin cancer, as well as other tumours from organs where ColVII is expressed.

Anchorless keratinocyte survival: an emerging pathogenic mechanism for squamous cell carcinoma in recessive dystrophic epidermolysis bullosa

Squamous cell carcinomas in patients suffering from recessive dystrophic epidermolysis bullosa are highly invasive and frequently metastatic. Expression of a collagen VII fragment (NC1) has been described as a prerequisite for the development of this tumor form. This commentary focuses on potential molecular mechanisms by which expression of the NC1 fragment may augment anchorage-independent growth and survival of malignant keratinocytes.

Mitochondrial membrane permeabilization in cell death

Irrespective of the morphological features of end-stage cell death (that may be apoptotic, necrotic, autophagic, or mitotic), mitochondrial membrane permeabilization (MMP) is frequently the decisive event that delimits the frontier between survival and death. Thus mitochondrial membranes constitute the battleground on which opposing signals combat to seal the cell's fate. Local players that determine the propensity to MMP include the pro- and antiapoptotic members of the Bcl-2 family, proteins from the mitochondrialpermeability transition pore complex, as well as a plethora of interacting partners including mitochondrial lipids. Intermediate metabolites, redox processes, sphingolipids, ion gradients, transcription factors, as well as kinases and phosphatases link lethal and vital signals emanating from distinct subcellular compartments to mitochondria. Thus mitochondria integrate a variety of proapoptotic signals. Once MMP has been induced, it causes the release of catabolic hydrolases and activators of such enzymes (including those of caspases) from mitochondria. These catabolic enzymes as well as the cessation of the bioenergetic and redox functions of mitochondria finally lead to cell death, meaning that mitochondria coordinate the late stage of cellular demise. Pathological cell death induced by ischemia/reperfusion, intoxication with xenobiotics, neurodegenerative diseases, or viral infection also relies on MMP as a critical event. The inhibition of MMP constitutes an important strategy for the pharmaceutical prevention of unwarranted cell death. Conversely, induction of MMP in tumor cells constitutes the goal of anticancer chemotherapy.

Altered expression of l-arginine metabolism pathway genes in chronic wounds in recessive dystrophic epidermolysis bullosa

Individuals with the severe, mutilating Hallopeau-Siemens form of recessive dystrophic epidermolysis bullosa (HS-RDEB) have trauma-induced blisters and skin erosions which often progress to wounds that are slow to heal. These chronic wounds cause considerable morbidity and there is an increased risk of squamous cell carcinoma arising in the wound margins. Currently, little is known about the keratinocyte cell biology in these wounds. Therefore, we compared the gene expression profiles of wound edge with nonwounded skin from two individuals with HS-RDEB. Trauma-induced wound sites had been present in both patients for more than 3 months. Hybridizations using DermArray gene expression filters showed relative differences in gene expression between wounded and unwounded skin. Notably, there was a fivefold increase in expression of arginase-1 (ARG1) in the chronic wound samples. Expression of seven other genes relevant to L-arginine metabolism also showed differences greater than twofold. L-arginine is known to have a critical role in the synthesis of nitric oxide as part of normal tissue repair. Although alterations in arginase isoenzymes have been detected previously in other chronic wounds (human and animal models), this is the first study to demonstrate differences in several components of the L-arginine metabolism pathway in chronic wounds, and the first to examine chronic wounds in HS-RDEB. The data show that the cascade of L-arginine metabolites is altered in HS-RDEB and the findings may provide new insight into the pathology of chronic wounds in this genodermatosis.