IKKβ Overexpression Leads to Pathologic Lesions in Stratified Epithelia and Exocrine Glands and to Tumoral Transformation of Oral Epithelia

IKKα-deficient lung adenocarcinomas generate an immunosuppressive microenvironment by overproducing Treg-inducing cytokines

The tumor microenvironment (TME) provides potential targets for cancer therapy. However, how signals originating in cancer cells affect tumor-directed immunity is largely unknown. Deletions in the CHUK locus, coding for IκB kinase α (IKKα), correlate with reduced lung adenocarcinoma (ADC) patient survival and promote Kras^G12D-initiated ADC development in mice, but it is unknown how reduced IKKα expression affects the TME. Here, we report that low IKKα expression in human and mouse lung ADC cells correlates with increased monocyte-derived macrophage and regulatory T cell (Treg) scores and elevated transcription of genes coding for macrophage-recruiting and Treg-inducing cytokines (CSF1, CCL22, TNF, and IL-23A). By stimulating recruitment of monocyte-derived macrophages from the bone marrow and enforcing a TNF/TNFR2/c-Rel signaling cascade that stimulates Treg generation, these cytokines promote lung ADC progression. Depletion of TNFR2, c-Rel, or TNF in CD4⁺ T cells or monocyte-derived macrophages dampens Treg generation and lung tumorigenesis. Treg depletion also attenuates carcinogenesis. In conclusion, reduced cancer cell IKKα activity enhances formation of a protumorigenic TME through a pathway whose constituents may serve as therapeutic targets for KRAS-initiated lung ADC.

ERAS, a Member of the Ras Superfamily, Acts as an Oncoprotein in the Mammary Gland

Simple Summary

The genes of the RAS family are among the group of genes most frequently mutated in human cancer. ERAS is a relatively unknown gene of this family. Although ERAS is overexpressed in some tumoral samples and in several cancer cell lines of human origin, it is not known if its expression drives tumor formation or if, alternatively, its expression is a secondary event in tumoral transformation. In this report, in order to clarify the role of ERAS in mammary tumorigenesis, we studied transgenic mice expressing ERAS in myoepithelial cells of mammary and other exocrine glands and in basal cells of stratified epithelia. These mice displayed an altered development and function of the mammary glands, and suffered high-frequency tumoral lesions in the mammary glands resembling a rare human breast tumor named malignant adenomyoepithelioma. Our results clearly demonstrate that ERAS is a true oncogene able to produce mammary tumors when inappropriately expressed.

Abstract

ERAS is a relatively uncharacterized gene of the Ras superfamily. It is expressed in ES cells and in the first stages of embryonic development; later on, it is silenced in the majority of cell types and tissues. Although there are several reports showing ERAS expression in tumoral cell lines and human tumor samples, it is unknown if ERAS deregulated expression is enough to drive tumor development. In this report, we have generated transgenic mice expressing ERAS in myoepithelial basal cells of the mammary gland and in basal cells of stratified epithelia. In spite of the low level of ERAS expression, these transgenic mice showed phenotypic alterations resembling overgrowth syndromes caused by the activation of the AKT-PI3K pathway. In addition, their mammary glands present developmental and functional disabilities accompanied by morphological and biochemical alterations in the myoepithelial cells. These mice suffer from tumoral transformation in the mammary glands with high incidence. These mammary tumors resemble, both histologically and by the expression of differentiation markers, malignant adenomyoepitheliomas. In sum, our results highlight the importance of ERAS silencing in adult tissues and define a truly oncogenic role for ERAS in mammary gland cells when inappropriately expressed.

Role of NF-κB in Ageing and Age-Related Diseases: Lessons from Genetically Modified Mouse Models

Ageing is a complex process, induced by multifaceted interaction of genetic, epigenetic, and environmental factors. It is manifested by a decline in the physiological functions of organisms and associated to the development of age-related chronic diseases and cancer development. It is considered that ageing follows a strictly-regulated program, in which some signaling pathways critically contribute to the establishment and maintenance of the aged state. Chronic inflammation is a major mechanism that promotes the biological ageing process and comorbidity, with the transcription factor NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) as a crucial mediator of inflammatory responses. This, together with the finding that the activation or inhibition of NF-κB can induce or reverse respectively the main features of aged organisms, has brought it under consideration as a key transcription factor that acts as a driver of ageing. In this review, we focused on the data obtained entirely through the generation of knockout and transgenic mouse models of either protein involved in the NF-κB signaling pathway that have provided relevant information about the intricate processes or molecular mechanisms that control ageing. We have reviewed the relationship of NF-κB and premature ageing; the development of cancer associated with ageing and the implication of NF-κB activation in the development of age-related diseases, some of which greatly increase the risk of developing cancer.

Attribution of NF-κB Activity to CHUK/IKKα-Involved Carcinogenesis

Simple Summary

CHUK/IKKα has emerged as a novel tumor suppressor in several organs of humans and mice. In general, activation of NF-κB promotes inflammation and tumorigenesis. IKKα reduction stimulates inflammatory responses including NF-κB’s targets and NF-κB-independent pathways for tumor promotion. Specific phenomena from genetically-modified mice and human TCGA database show the crosstalk between IKKα and NF-κB although their nature paths for normal organ development and the disease and cancer pathogenesis remains largely under investigation. In this review, we focus on the interplay between IKKα and NF-κB signaling during carcinogenesis. A better understanding of their relationship will provide insight into therapeutic targets of cancer.

Abstract

Studies analyzing human cancer genome sequences and genetically modified mouse models have extensively expanded our understanding of human tumorigenesis, even challenging or reversing the dogma of certain genes as originally characterized by in vitro studies. Inhibitor-κB kinase α (IKKα), which is encoded by the conserved helix-loop-helix ubiquitous kinase (CHUK) gene, is first identified as a serine/threonine protein kinase in the inhibitor-κB kinase complex (IKK), which is composed of IKKα, IKKβ, and IKKγ (NEMO). IKK phosphorylates serine residues 32 and 36 of IκBα, a nuclear factor-κB (NF-κB) inhibitor, to induce IκBα protein degradation, resulting in the nuclear translocation of NF-κB dimers that function as transcriptional factors to regulate immunity, infection, lymphoid organ/cell development, cell death/growth, and tumorigenesis. NF-κB and IKK are broadly and differentially expressed in the cells of our body. For a long time, the idea that the IKK complex acts as a direct upstream activator of NF-κB in carcinogenesis has been predominately accepted in the field. Surprisingly, IKKα has emerged as a novel suppressor for skin, lung, esophageal, and nasopharyngeal squamous cell carcinoma, as well as lung and pancreatic adenocarcinoma (ADC). Thus, Ikkα loss is a tumor driver in mice. On the other hand, lacking the RANKL/RANK/IKKα pathway impairs mammary gland development and attenuates oncogene- and chemical carcinogen-induced breast and prostate tumorigenesis and metastasis. In general, NF-κB activation leads one of the major inflammatory pathways and stimulates tumorigenesis. Since IKKα and NF-κB play significant roles in human health, revealing the interplay between them greatly benefits the diagnosis, treatment, and prevention of human cancer. In this review, we discuss the intriguing attribution of NF-κB to CHUK/IKKα-involved carcinogenesis.

Inflammation-Related Carcinogenesis: Lessons from Animal Models to Clinical Aspects

Simple Summary

In multicellular organisms, inflammation is the body’s most primitive and essential protective response against any external agent. Inflammation, however, not only causes various modern diseases such as cardiovascular disorders, neurological disorders, autoimmune diseases, metabolic syndrome, infectious diseases, and cancer but also shortens the healthy life expectancy. This review focuses on the onset of carcinogenesis due to chronic inflammation caused by pathogen infections and inhalation/ingestion of foreign substances. This study summarizes animal models associated with inflammation-related carcinogenesis by organ. By determining factors common to inflammatory carcinogenesis models, we examined strategies for the prevention and treatment of inflammatory carcinogenesis in humans.

Abstract

Inflammation-related carcinogenesis has long been known as one of the carcinogenesis patterns in humans. Common carcinogenic factors are inflammation caused by infection with pathogens or the uptake of foreign substances from the environment into the body. Inflammation-related carcinogenesis as a cause for cancer-related death worldwide accounts for approximately 20%, and the incidence varies widely by continent, country, and even region of the country and can be affected by economic status or development. Many novel approaches are currently available concerning the development of animal models to elucidate inflammation-related carcinogenesis. By learning from the oldest to the latest animal models for each organ, we sought to uncover the essential common causes of inflammation-related carcinogenesis. This review confirmed that a common etiology of organ-specific animal models that mimic human inflammation-related carcinogenesis is prolonged exudation of inflammatory cells. Genotoxicity or epigenetic modifications by inflammatory cells resulted in gene mutations or altered gene expression, respectively. Inflammatory cytokines/growth factors released from inflammatory cells promote cell proliferation and repair tissue injury, and inflammation serves as a “carcinogenic niche”, because these fundamental biological events are common to all types of carcinogenesis, not just inflammation-related carcinogenesis. Since clinical strategies are needed to prevent carcinogenesis, we propose the therapeutic apheresis of inflammatory cells as a means of eliminating fundamental cause of inflammation-related carcinogenesis.

S100A9 promotes prostate cancer cell invasion by activating TLR4/NF-κB/integrin β1/FAK signaling

Background

S100A9, which is expressed in prostate cancer, has been reported in association with prostate cancer progression. However, the role of S100A9 in prostate cancer metastasis is largely unknown. The aim of this study was to investigate the effect of S100A9 on prostate cancer cell invasion and the involved mechanisms.

Materials and methods

Integrin β1 expression in PC-3 and DU-145 cells was determined by quantitative real-time polymerase chain reaction (PCR) (qRT-PCR) and Western blot. Cellular invasion was measured by transwell invasion assay. Western blot was used to determine protein expression. Concentrations of S100A9 and fibronectin were analyzed by enzyme-linked immunosorbent assay. The protein interaction was detected by immunoprecipitation. The NF-κB activity was measured by luciferase reporter assay. The DU-145 cells metastasis in vivo was determined in mice xenograft models after S100A9 overexpression.

Results

S100A9 promoted prostate cancer cells invasion, integrin β1 expression and fibronectin secretion. Further investigation evidenced that S100A9 interacted with Toll-like receptor 4 (TLR4) and activated NF-κB, which was responsible for tumor cell invasion, integrin β1 up-regulation and focal adhesion kinase (FAK) phosphorylation. Furthermore, integrin β1 inhibition led to decreased FAK phosphorylation and reduced tumor cell invasion. Overexpression of S100A9 increased xenograft tumor micro-metastases, integrin β1 expression and induced NF-κB and FAK activation in vivo.

Conclusion

Our study demonstrated that S100A9 promotes prostate cancer cell invasion, and one of the underlying molecular mechanisms is that S100A9 activates integrin β1/FAK through TLR4/NF-κB signaling leading to metastasis of prostate cancer cell.

IKKβ overexpression together with a lack of tumour suppressor genes causes ameloblastic odontomas in mice

Odontogenic tumours are a heterogeneous group of lesions that develop in the oral cavity region and are characterized by the formation of tumoural structures that differentiate as teeth. Due to the diversity of their histopathological characteristics and clinical behaviour, the classification of these tumours is still under debate. Alterations in morphogenesis pathways such as the Hedgehog, MAPK and WNT/β-catenin pathways are implicated in the formation of odontogenic lesions, but the molecular bases of many of these lesions are still unknown. In this study, we used genetically modified mice to study the role of IKKβ (a fundamental regulator of NF-κB activity and many other proteins) in oral epithelial cells and odontogenic tissues. Transgenic mice overexpressing IKKβ in oral epithelial cells show a significant increase in immune cells in both the oral epithelia and oral submucosa. They also show changes in the expression of several proteins and miRNAs that are important for cancer development. Interestingly, we found that overactivity of IKKβ in oral epithelia and odontogenic tissues, in conjunction with the loss of tumour suppressor proteins (p53, or p16 and p19), leads to the appearance of odontogenic tumours that can be classified as ameloblastic odontomas, sometimes accompanied by foci of secondary ameloblastic carcinomas. These tumours show NF-κB activation and increased β-catenin activity. These findings may help to elucidate the molecular determinants of odontogenic tumourigenesis and the role of IKKβ in the homoeostasis and tumoural transformation of oral and odontogenic epithelia.

(+)-Aeroplysinin-1 Modulates the Redox Balance of Endothelial Cells

The bioactive natural compound from marine origin, (+)-aeroplysinin-1, has been shown to exhibit potent anti-inflammatory and anti-angiogenic effects. The aim of the present study was to identify new targets for (+)-aeroplysinin-1 in endothelial cells. The sequential use of 2D-electrophoresis and MALDI-TOF-TOF/MS allowed us to identify several differentially expressed proteins. Four of these proteins were involved in redox processes and were validated by Western blot. The effects of (+)-aeroplysinin-1 were further studied by testing the effects of the treatment with this compound on the activity of several anti- and pro-oxidant enzymes, as well as on transcription factors involved in redox homeostasis. Finally, changes in the levels of total reactive oxygen species and mitochondrial membrane potential induced by endothelial cell treatments with (+)-aeroplysinin-1 were also determined. Taken altogether, these findings show that (+)-aeroplysinin-1 has multiple targets involved in endothelial cell redox regulation.

Context-Dependent Role of IKKβ in Cancer

Inhibitor of nuclear factor kappa-B kinase subunit beta (IKKβ) is a kinase principally known as a positive regulator of the ubiquitous transcription factor family Nuclear Factor-kappa B (NF-κB). In addition, IKKβ also phosphorylates a number of other proteins that regulate many cellular processes, from cell cycle to metabolism and differentiation. As a consequence, IKKβ affects cell physiology in a variety of ways and may promote or hamper tumoral transformation depending on hitherto unknown circumstances. In this article, we give an overview of the NF-κB-dependent and -independent functions of IKKβ. We also summarize the current knowledge about the relationship of IKKβ with cellular transformation and cancer, obtained mainly through the study of animal models with cell type-specific modifications in IKKβ expression or activity. Finally, we describe the most relevant data about IKKβ implication in cancer obtained from the analysis of the human tumoral samples gathered in The Cancer Genome Atlas (TCGA) and the Catalogue of Somatic Mutations in Cancer (COSMIC).

IKKβ-Mediated Resistance to Skin Cancer Development Is Ink4a/Arf-Dependent

IKKβ (encoded by IKBKB) is a protein kinase that regulates the activity of numerous proteins important in several signaling pathways, such as the NF-κB pathway. IKKβ exerts a protumorigenic role in several animal models of lung, hepatic, intestinal, and oral cancer. In addition, genomic and proteomic studies of human tumors also indicate that IKBKB gene is amplified or overexpressed in multiple tumor types. Here, the relevance of IKKβ in skin cancer was determined by performing carcinogenesis studies in animal models overexpressing IKKβ in the basal skin layer. IKKβ overexpression resulted in a striking resistance to skin cancer development and an increased expression of several tumor suppressor proteins, such as p53, p16, and p19. Mechanistically, this skin tumor-protective role of IKKβ is independent of p53, but dependent on the activity of the Ink4a/Arf locus. Interestingly, in the absence of p16 and p19, IKKβ-increased expression favors the appearance of cutaneous spindle cell-like squamous cell carcinomas, which are highly aggressive tumors. These results reveal that IKKβ activity prevents skin tumor development, and shed light on the complex nature of IKKβ effects on cancer progression, as IKKβ can both promote and prevent carcinogenesis depending on the cell type or molecular context.Implications: The ability of IKKβ to promote or prevent carcinogenesis suggests the need for further evaluation when targeting this protein. Mol Cancer Res; 15(9); 1255-64. ©2017 AACR.

Inactivation of Fam20B in the dental epithelium of mice leads to supernumerary incisors

Tooth formation is tightly regulated by epithelial-mesenchymal interactions via hierarchic cascades of signaling molecules. The glycosaminoglycan (GAG) chains covalently attached to the core protein of proteoglycans (PGs) provide docking sites for signaling molecules and their receptors during the morphogenesis of tissues and organs. Although PGs are believed to play important roles in tooth formation, little is known about their exact functions in this developmental process and the relevant molecular basis. Family with sequence similarity member 20-B (FAM20B) is a newly identified kinase that phosphorylates the xylose in the common linkage region connecting the GAG with the protein core of PGs. The phosphorylation of xylose is essential for elongation of the common linkage region and the subsequent GAG assembly. In this study, we generated a Fam20B-floxed allele in mice and found that inactivating Fam20B in the dental epithelium leads to supernumerary maxillary and mandibular incisors. This finding highlights the pivotal role of PGs in tooth morphogenesis and opens a new window for understanding the regulatory mechanism of PG-mediated signaling cascades during tooth formation.

Bridging the Gap: A Regulator of NF-κB Linking Inflammation and Cancer

BACKGROUND

A close connection between inflammation and cancer has now been firmly established. While tumor initiation is typically independent of inflammatory events, immune cells infiltrating the tumor microenvironment secrete inflammatory cytokines that enhance the aberrant growth of tumor cells and thus facilitate tumor progression. Therefore, inflammation and tumor growth are usually interpreted as closely related on a systemic level but as distinct, independently regulated processes at a molecular level.

HIGHLIGHT

Recently, we reported that a sub-class of small GTPases, namely κB-Ras1 and κB-Ras2, regulate both inflammation and tumor growth, thereby providing a unique molecular bridge between the two biological processes.

CONCLUSION

Here, we briefly summarize the known contact points between inflammation and cancer, including oral cancers, and put into context the identification of κB-Ras proteins as molecular link between two independent pathways important for tumor growth.

ADAM17 mediates OSCC development in an orthotopic murine model

BACKGROUND

ADAM17 is one of the main sheddases of the cells and it is responsible for the cleavage and the release of ectodomains of important signaling molecules, such as EGFR ligands. Despite the known crosstalk between ADAM17 and EGFR, which has been considered a promising targeted therapy in oral squamous cell carcinoma (OSCC), the role of ADAM17 in OSCC development is not clear.

METHOD

In this study the effect of overexpressing ADAM17 in cell migration, viability, adhesion and proliferation was comprehensively appraised in vitro. In addition, the tumor size, tumor proliferative activity, tumor collagenase activity and MS-based proteomics of tumor tissues have been evaluated by injecting tumorigenic squamous carcinoma cells (SCC-9) overexpressing ADAM17 in immunodeficient mice.

RESULTS

The proteomic analysis has effectively identified a total of 2,194 proteins in control and tumor tissues. Among these, 110 proteins have been down-regulated and 90 have been up-regulated in tumor tissues. Biological network analysis has uncovered that overexpression of ADAM17 regulates Erk pathway in OSCC and further indicates proteins regulated by the overexpression of ADAM17 in the respective pathway. These results are also supported by the evidences of higher viability, migration, adhesion and proliferation in SCC-9 or A431 cells in vitro along with the increase of tumor size and proliferative activity and higher tissue collagenase activity as an outcome of ADAM17 overexpression.

CONCLUSION

These findings contribute to understand the role of ADAM17 in oral cancer development and as a potential therapeutic target in oral cancer. In addition, our study also provides the basis for the development of novel and refined OSCC-targeting approaches.

A role for NF-κB activity in skin hyperplasia and the development of keratoacanthomata in mice

BACKGROUND

Previous studies have implicated NF-κB signaling in both cutaneous development and oncogenesis. However, these studies have been limited in part by the lethality that results from extreme over- or under-expression of NF-κB in available mouse models. Even cre-driven tissue specific expression of transgenes, or targeted deletion of NF-κB can cause cell death. Therefore, the present study was undertaken to evaluate a novel mouse model of enhanced NF-κB activity in the skin.

METHODS

A knock-in homologous recombination technique was utilized to develop a mouse model (referred to as PD mice) with increased NF-κB activity.

RESULTS

The data show that increased NF-κB activity leads to hyperproliferation and dysplasia of the mouse epidermis. Chemical carcinogenesis in the context of enhanced NF-κB activity promotes the development of keratoacanthomata.

CONCLUSION

Our findings support an important role for NF-κB in keratinocyte dysplasia. We have found that enhanced NF-κB activity renders keratinocytes susceptible to hyperproliferation and keratoacanthoma (KA) development but is not sufficient for transformation and SCC development. We therefore propose that NF-κB activation in the absence of additional oncogenic events can promote TNF-dependent, actinic keratosis-like dysplasia and TNF-independent, KAs upon chemical carcinogensis. These studies suggest that resolution of KA cannot occur when NF-κB activation is constitutively enforced.

A transposon-based analysis of gene mutations related to skin cancer development

Nonmelanoma skin cancer (NMSC) is by far the most frequent type of cancer in humans. NMSC includes several types of malignancies with different clinical outcomes, the most frequent being basal and squamous cell carcinomas. We have used the Sleeping Beauty transposon/transposase system to identify somatic mutations associated with NMSC. Transgenic mice bearing multiple copies of a mutagenic Sleeping Beauty transposon T2Onc2 and expressing the SB11 transposase under the transcriptional control of regulatory elements from the keratin K5 promoter were treated with TPA, either in wild-type or Ha-ras mutated backgrounds. After several weeks of treatment, mice with transposition developed more malignant tumors with decreased latency compared with control mice. Transposon/transposase animals also developed basal cell carcinomas. Genetic analysis of the transposon integration sites in the tumors identified several genes recurrently mutated in different tumor samples, which may represent novel candidate cancer genes. We observed alterations in the expression levels of some of these genes in human tumors. Our results show that inactivating mutations in Notch1 and Nsd1, among others, may have an important role in skin carcinogenesis.