Elevated cutaneous Smad activation associates with enhanced skin tumor susceptibility in organ transplant recipients

Apelin Prevents and Alleviates Crystalline Silica-induced Pulmonary Fibrosis via Inhibiting Transforming Growth Factor Beta 1-triggered Fibroblast Activation

Silicosis is a common and ultimately fatal occupational disease, yet the limited therapeutic option remains the major clinical challenge. Apelin, an endogenous ligand of the G-protein-coupled receptor (APJ), is abundantly expressed in diverse organs. The apelin-APJ axis helps to control pathological and physiological processes in lung. The role of apelin in the pathological process and its possible therapeutic effects on silicosis have not been elucidated. In this study, we found that lung expression and circulating levels of apelin were markedly decreased in silicosis patients and silica-induced fibrotic mice and associated with the severity. Furthermore, in vivo data demonstrated that pre-treatment from day 3 and post-treatment from day 15 with apelin could both alleviate silica-induced pulmonary fibrosis in mice. Besides, apelin inhibited pulmonary fibroblast activation via transforming growth factor beta 1 (TGF-β1) signaling. Our study suggested that apelin could prevent and reverse silica-induced pulmonary fibrosis by inhibiting the fibroblast activation through TGF-β1 signaling pathway, thus providing a new potential therapeutic strategy for silicosis and other pulmonary fibrosis.

Cutaneous squamous cell carcinoma arising in immunosuppressed patients: a systematic review of tumor profiling studies

As solid organ transplantation becomes more prevalent, more individuals are living as members of the immunosuppressed population with an elevated risk for cutaneous squamous cell carcinoma (cSCC). Although great progress has been made in understanding the pathogenesis of cSCC in general, little is known about the drivers of tumorigenesis in immunosuppressed patients and organ-transplant recipients, specifically. This systematic review sought to synthesize information regarding the genetic and epigenetic alterations as well as changes in protein and mRNA expression that place this growing population at risk for cSCC, influence treatment response, and promote tumor aggressiveness. This review will provide investigators with a framework to identify future areas of investigation and clinicians with additional insight into how to best manage these patients.

Reduced SMAD2/3 activation independently predicts increased depth of human cutaneous squamous cell carcinoma

The incidence of cutaneous squamous cell carcinoma (cSCC) is rising. Whilst the majority are cured surgically, aggressive metastatic cSCC carry a poor prognosis. Inactivating mutations in transforming growth factor beta (TGF-β) receptors have been identified amongst genetic drivers of sporadic tumours and murine models of cSCC, suggesting a tumour suppressor function for TGF-β in normal skin. However, paradoxically, TGF-β acts as a tumour promoter in some murine model systems. Few studies have analysed the role of TGF-β/activin signalling in human normal skin, hyper-proliferative skin disorders and cSCC. Antibodies recognising phospho-SMAD proteins which are activated during canonical TGF-β/activin signalling were validated for use in immunohistochemistry. A tissue microarray comprising FFPE lesional and perilesional tissue from human primary invasive cSCC (n=238), cSCC in-situ (n=2) and keratocanthoma (n=9) were analysed in comparison with tissues from normal human scalp (n=10). Phosphorylated SMAD2 and SMAD3 were detected in normal interfollicular epidermal keratinocytes and were also highly localised to inner root sheath, matrix cells and Keratin 15 positive cells. Lesional cSCC tissue had significantly reduced activated SMAD2/3 compared to perilesional tissue, consistent with a tumour suppressor role for SMAD2/3 activators in cSCC. Increased cSCC tumour thickness inversely correlated with the presence of phospho-SMADs in tumour tissue suggesting that a reduction in canonical TGF-β/activin signalling may be associated with disease progression.

The pathogenesis of cutaneous squamous cell carcinoma in organ transplant recipients

The pathogenesis of keratinocyte carcinoma following organ transplantation is multifactorial, and recent evidence suggests a complex and often synergistic interplay between the carcinogenic effects of ultraviolet radiation, compromised immune surveillance, direct pro- and anticarcinogenic effects of drugs, oncogenic viruses (in particular, beta-genus human papillomaviruses) and host genetic susceptibility factors. We present an overview of those factors for which there is currently the most convincing evidence and highlight important gaps in our knowledge. In particular, a clear understanding of the interdependence and relative contributions of these co-factors is currently lacking, yet has important implications for rational development of clinically relevant biomarkers and targeted strategies for treatment and prevention of post-transplant keratinocyte cancers.

Targeting TGF-β Signaling for Therapeutic Gain

Transforming growth factor βs (TGF-βs) are closely related ligands that have pleiotropic activity on most cell types of the body. They act through common heterotetrameric TGF-β type II and type I transmembrane dual specificity kinase receptor complexes, and the outcome of signaling is context-dependent. In normal tissue, they serve a role in maintaining homeostasis. In many diseased states, particularly fibrosis and cancer, TGF-β ligands are overexpressed and the outcome of signaling is diverted toward disease progression. There has therefore been a concerted effort to develop drugs that block TGF-β signaling for therapeutic benefit. This review will cover the basics of TGF-β signaling and its biological activities relevant to oncology, present a summary of pharmacological TGF-β blockade strategies, and give an update on preclinical and clinical trials for TGF-β blockade in a variety of solid tumor types.

Targeting TGF-β Signaling for Therapeutic Gain

Transforming growth factor βs (TGF-βs) are closely related ligands that have pleiotropic activity on most cell types of the body. They act through common heterotetrameric TGF-β type II and type I transmembrane dual specificity kinase receptor complexes, and the outcome of signaling is context-dependent. In normal tissue, they serve a role in maintaining homeostasis. In many diseased states, particularly fibrosis and cancer, TGF-β ligands are overexpressed and the outcome of signaling is diverted toward disease progression. There has therefore been a concerted effort to develop drugs that block TGF-β signaling for therapeutic benefit. This review will cover the basics of TGF-β signaling and its biological activities relevant to oncology, present a summary of pharmacological TGF-β blockade strategies, and give an update on preclinical and clinical trials for TGF-β blockade in a variety of solid tumor types.

Pattern of TGFbeta receptor 1 expression differs between kras-mutated keratoacanthomas and squamous cell carcinomas of the skin

PURPOSE

Increasing evidence indicates that TGFbeta- and EGFR-signaling is involved in the pathogenesis of keratoacanthoma (KA) and squamous cell carcinoma (SCC) of the skin. We analyzed the expression pattern of TGFbeta-signaling components and screened for mutations in tgfbetaR1, egfr, kras and braf in KAs and SCCs.

METHODS

Immunohistochemical analysis of TGFbeta1, TGFbetaR1, TGFbetaR2 and phospho-SMAD2/3 was performed on skin tumors (29 KAs, 30 well and 31 moderately differentiated SCCs). Mutation screening in hotspot regions of tgfbetaR1, egfr, kras and braf was performed through pyrosequencing of tumor DNA.

FINDINGS

Expression of TGFbeta1, TGFbetaR1 and p-SMAD2/3 was increased in tumors as compared to surrounding skin. In KAs characteristic strong discontinuous membranous TGFbetaR1 expression pattern frequently associated with kras mutation was noted. SCCs showed continuous TGFbetaR1 expression, stronger p-SMAD2/3 expression and less frequent kras mutations. In tumors at sun-exposed sites stronger TGFbetaR1 expression was noted. One SCC showed tgfbetaR1 mutation, but no other mutations were found.

CONCLUSION

Although tgfbetaR1 germline mutations cause inherited KAs and our finding of strong discontinuous membranous expression in KAs suggests accumulation of functionally altered protein, we found no tgfbetaR1 mutations or influence on TGFbeta-signaling, but frequent kras mutations in this subgroup of KAs. Characteristic TGFbetaR1 expression pattern in KA can facilitate histopathologic distinction from SCC.

The complexities of TGF-β action during mammary and squamous cell carcinogenesis

Many advanced tumors produce excess amounts of Transforming Growth Factor-β (TGF-β), which is a potent growth inhibitor of normal epithelial cells. However, in tumors its homeostatic action on cells can be diverted along several alternative pathways. Thus, TGF-β signaling has been reported to elicit a preventative or tumor suppressive effect during the earlier stages of tumorigenesis, but later in tumor development, when carcinoma cells become refractory to TGF-β-mediated growth inhibition, response to TGF-β signaling elicits predominantly tumor progressing effects. This is not a simple switch from suppression to progression, but more like a rheostat, involving multiple complementary and antagonizing activities that slowly tip the balance from one to the other. This review will focus on the multiple activities of TGF-β in regulation of two epithelial tumor types, namely squamous cell carcinoma and breast cancer. Basic findings in current mouse models of cancer are presented, as well as a discussion of the complicating issue of outcome of altered TGFβ signaling depending on genetic variability between mouse strains. This review also discusses the role TGF-β within the tumor microenvironment particularly its ability to polarize the microenvironment towards a pro-tumorigenic milieu.

Procarcinogenic effects of cyclosporine A are mediated through the activation of TAK1/TAB1 signaling pathway

Cyclosporine A (CsA) is an immunosuppressive drug commonly used for maintaining chronic immune suppression in organ transplant recipients. It is known that patients receiving CsA manifest increased growth of aggressive non-melanoma skin cancers. However, the underlying mechanism by which CsA augments tumor growth is not fully understood. Here, we show that CsA augments the growth of A431 epidermoid carcinoma xenograft tumors by activating tumor growth factor β-activated kinase1 (TAK1). The activation of TAK1 by CsA occurs at multiple levels by kinases ZMP, AMPK and IRAK. TAK1 forms heterodimeric complexes with TAK binding protein 1 and 2 (TAB1/TAB2) which in term activate nuclear factor κB (NFκB) and p38 MAP kinase. Transcriptional activation of NFκB is evidenced by IKKβ-mediated phosphorylation-dependent degradation of IκB and consequent nuclear translocation of p65. This also leads to enhancement in the expression of its transcriptional target genes cyclin D1, Bcl2 and COX-2. Similarly, activation of p38 leads to enhanced inflammation-related signaling shown by increased phosphorylation of MAPKAPK2 and which in turn phosphorylates its substrate HSP27. Activation of both NFκB and p38 MAP kinase provide mitogenic stimuli to augment the growth of SCCs.

Pathogenesis of nonmelanoma skin cancers in organ transplant recipients

Nonmelanoma skin cancer (NMSC) is the most common human cancer, with an incidence of more than 1.2 million per year in the USA. The risk for the development of NMSCs increases by approximately 10-250 fold in chronically immune suppressed organ transplant recipients (OTRs). Solar UVB is the most common etiologic factor in the development of this neoplasm, both in immune competent and immune suppressed populations. This review provides a description of NMSC in OTRs. It also provides an account of the various immunologic and non-immune-dependent mechanisms involved in the pathogenesis and progression of NMSCs in OTRs. Finally, this review addresses possible strategies for the prevention of this cancer, particularly focusing on the aspects that may be incorporated to prevent negative effects of chemopreventive chemicals on graft survival.

Loss of the p53/p63 regulated desmosomal protein Perp promotes tumorigenesis

Dysregulated cell–cell adhesion plays a critical role in epithelial cancer development. Studies of human and mouse cancers have indicated that loss of adhesion complexes known as adherens junctions contributes to tumor progression and metastasis. In contrast, little is known regarding the role of the related cell–cell adhesion junction, the desmosome, during cancer development. Studies analyzing expression of desmosome components during human cancer progression have yielded conflicting results, and therefore genetic studies using knockout mice to examine the functional consequence of desmosome inactivation for tumorigenesis are essential for elucidating the role of desmosomes in cancer development. Here, we investigate the consequences of desmosome loss for carcinogenesis by analyzing conditional knockout mice lacking Perp, a p53/p63 regulated gene that encodes an important component of desmosomes. Analysis of Perp-deficient mice in a UVB-induced squamous cell skin carcinoma model reveals that Perp ablation promotes both tumor initiation and progression. Tumor development is associated with inactivation of both of Perp's known functions, in apoptosis and cell–cell adhesion. Interestingly, Perp-deficient tumors exhibit widespread downregulation of desmosomal constituents while adherens junctions remain intact, suggesting that desmosome loss is a specific event important for tumorigenesis rather than a reflection of a general change in differentiation status. Similarly, human squamous cell carcinomas display loss of PERP expression with retention of adherens junctions components, indicating that this is a relevant stage of human cancer development. Using gene expression profiling, we show further that Perp loss induces a set of inflammation-related genes that could stimulate tumorigenesis. Together, these studies suggest that Perp-deficiency promotes cancer by enhancing cell survival, desmosome loss, and inflammation, and they highlight a fundamental role for Perp and desmosomes in tumor suppression. An understanding of the factors affecting cancer progression is important for ultimately improving the diagnosis, prognostication, and treatment of cancer.

Changes in tissue architecture, such as loss of adhesion between cells, have been shown to facilitate cancer development, especially metastasis where cells can detach from a tumor and spread throughout the body. While various studies have demonstrated that inactivation of an adhesion complex known as the adherens junction promotes cancer development and metastasis, little is known about the role of the desmosome—a related cell–cell adhesion complex—in tumorigenesis. Here we examine the consequence of desmosome-deficiency for tumor development by studying mice lacking a key component of desmosomes in the skin, a protein known as Perp. Using a mouse model for human skin cancer, in which ultraviolet light promotes skin cancer development, we demonstrate that Perp-deficiency indeed leads to accelerated skin tumorigenesis. We similarly observe that PERP is lost during human skin cancer development, suggesting that PERP is also important as a tumor suppressor in humans. These findings demonstrate that desmosome-deficiency achieved by Perp inactivation can promote cancer and suggest the potential utility of monitoring PERP status for staging, prognostication, or treatment of human cancers.