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Supplementary Tables 1-5, Figures 1-7 from Reduction in IκB Kinase α Expression Promotes the Development of Skin Papillomas and Carcinomas

Objective Hypohidrotic ectodermal dysplasia (HED) is a hereditary disorder characterized by abnormal structures and functions of the ectoderm-derived organs, including teeth. HED patients exhibit a variety of dental symptoms, such as hypodontia. Although disruption of the EDA/EDAR/EDARADD/NF-κB pathway is known to be responsible for HED, it remains unclear whether this pathway is involved in the process of enamel formation. Experimental subjects and methods To address this question, we examined the mice overexpressing Ikkβ (an essential component required for the activation of NF-κB pathway) under the keratin 5 promoter (K5-Ikkβ). Results Upregulation of the NF-κB pathway was confirmed in the ameloblasts of K5-Ikkβ mice. Premature abrasion was observed in the molars of K5-Ikkβ mice, which was accompanied by less mineralized enamel. However, no significant changes were observed in the enamel thickness and the pattern of enamel rods in K5-Ikkβ mice. Klk4 expression was significantly upregulated in the ameloblasts of K5-Ikkβ mice at the maturation stage, and the expression of its substrate, amelogenin, was remarkably reduced. This suggests that abnormal enamel observed in K5-Ikkβ mice was likely due to the compromised degradation of enamel protein at the maturation stage. Conclusion Therefore, we could conclude that the overactivation of the NF-κB pathway impairs the process of amelogenesis.

Significance This study reveals that impaired IKKα expression or activity in lung cancer enhances differentiation of protumorigenic Treg cells through a TNF/TNFR2/NF-κB signaling pathway in both human and mouse lung ADC. Depletion of one of the molecules that are required for Treg cell induction represses lung ADC development. Thus, the components that interfere with this particular Treg differentiation provide targets for the generation of TME-modifying therapies.

Global inactivation of IκB kinase (IKK)-α results in defective lymph node (LN) formation and B cell maturation, and loss of IKK-α–dependent noncanonical NF-κB signaling in stromal organizer and hematopoietic cells is thought to underlie these distinct defects. We previously demonstrated that this pathway is also activated in vascular endothelial cells (ECs). To determine the physiologic function of EC-intrinsic IKK-α, we crossed Ikkα(F/F) mice with Tie2-cre or Cdh5-cre mice to ablate IKK-α in ECs. Notably, the compound defects of global IKK-α inactivation were recapitulated in Ikkα(Tie2) and Ikkα(Cdh5) mice, as both lacked all LNs and mature follicular and marginal zone B cell numbers were markedly reduced. However, as Tie2-cre and Cdh5-cre are expressed in all ECs, including blood forming hemogenic ECs, IKK-α was also absent in hematopoietic cells (HC). To determine if loss of HC-intrinsic IKK-α affected LN development, we generated Ikkα(Vav) mice lacking IKK-α in only the hematopoietic compartment. While mature B cell numbers were significantly reduced in Ikkα(Vav) mice, LN formation was intact. As lymphatic vessels also arise during development from blood ECs, we generated Ikkα(Lyve1) mice lacking IKK-α in lymphatic ECs (LECs) to determine if IKK-α in lymphatic vessels impacts LN development. Strikingly, while mature B cell numbers were normal, LNs were completely absent in Ikkα(Lyve1) mice. Thus, our findings reveal that IKK-α in distinct EC-derived compartments is uniquely required to promote B cell homeostasis and LN development, and we establish that LEC-intrinsic IKK-α is absolutely essential for LN formation.

Lung cancer remains one of the leading causes of mortality of cancer patients. Kinase-dead Ikkα knock-in (KA/KA) mice develop CD4 T cell-derived autoimmune disease. Previously, we reported spontaneous lung squamous cell carcinoma (SCC) associated with increase macrophage and CD4 T cell numbers in KA/KA mice. Depleting macrophages dampens lung SCC development in KA/KA mice, but a lot of CD4 T cells remain in the lungs. The activity of CD4 T cells in lung SCC development is unknown. In this study, we attempted to investigate the role of CD4 T cells in lung SCC development. We performed adoptive CD4 T cell transfer experiment and found that KA/KA CD4 T cell transfer, not WT CD4 T cells, recruited marked macrophages to the lungs and induced lung SCC in KA/KA;Rag1-/- mice. The CD4 T cells isolated from the lungs of KA/KA mice and KA/KA;Rag1-/- mice with KA/KA CD4 T cell transfer expressed elevated PD-1, IL-4, IL-5, Il-13, and Il-21 levels compared to WT mice. We found that Il4 ablation, not Il5 deletion, reduced macrophage recruitment and blocked SCC development in KA/KA;Il4-/- mice as well as unlike KA/KA CD4 T cells, KA/KA;Il4-/- CD4 T cells did not induce spontaneous lung SCC in KA/KA;Rag1-/- mice with KA/KA;Il4-/- CD4 T cell injections. Taken together, the finding highlights a pathogenic role of IL-4-producing CD4 T cells in lung carcinogenesis. Citation Format: Gajendra Jogdand, Sayantan Banerjee, Gongping Shi, Jami Willet Brown, Amit Singh, Yongmei Zhao, Jyoti Shetty, Bao Tran, Yinling Hu. Interleukin 4 Producing CD4 T cells initiate a crucial event for lung cancer development [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1339.

Urothelial cell carcinoma is the most common cancer of the renal pelvis or ureter in humans. Due to a lack of animal models, its pathogenic causes remain elusive. Here, we generated IkkαΔKsp mice lacking Ikkα specifically in epithelial cells of the developing kidney and genitourinary tract as well as renal tubules. The mutant mice developed invasive papillary urothelial cell carcinomas initiated from the pelvis, leading to hydronephrosis, and the animals eventually died. Depleting neutrophils or antibiotic treatment slowed down the development of phenotypes but did not rescue them, suggesting that epithelial-cell-autonomous aberrant alterations induced by Ikkα loss are critical for the initiation of urothelial cancer. Moreover, We found that the urothelial cell carcinomas in the mutant mice highly expressed cancer stem-cell markers such as Sox2, K15, p63, Nanog, and CD44, as well as FGFR3 and osteopontin (OPN). Thus, we hypothesize that Ikkα ablation-mediated OPN and FGFR3 overexpression regulates and amplifies CD44+ renal cancer-stem cells for tumor initiation. These alterations are shared with human papillary urothelial cell carcinomas. Citation Format: Xin Li, Feng Zhu, Chengfei Jiang, Yongmei Zhao, Bao Tran, Donna Butcher, Xiaolin Wu, Tross Debra, Yinling Hu. IIKKa deletion amplifies renal transitional epithelial stem cells and initiates lethal invasive papillary urothelial cell carcinoma development [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 926.

Previously we reported that bone marrow-derived macrophages are required for lung squamous cell carcinoma development in kinase-dead Ikkα knockin (KA/KA) mice. The KA/KA lungs display strikingly enlarged sizes, sustained inflammation with increased expression of multiple cytokines and chemokines and marked infiltrating macrophages and T cells, and tissue damage, which look like a “burning hill”. To determine a critical event for the pathogenesis of the lung disease and SCC development, in this study, we found that these F4/80+CD11b+CSF1R+ monocyte-derived macrophages isolated from KA/KA lungs showed enlarged sizes carrying many lipid droplets and highly expressed the genes that encode proteins involved in lipid metabolism compared to WT. To determine whether the lung lipid concentrations regulate foamy macrophage development, we incubated Raw macrophages with WT or KA/KA lung extract, respectively, and found that KA/KA lung extracts induced lipid droplets and elevated lipid levels and pathways for lipid metabolism compared to WT lung extracts. Furthermore, we found that cytokines including IL-4, IL-6, IL-33, and IFNb, promoted lipid metabolism in Raw macrophages incubated with WT lung extracts, and also stimulated lipid metabolism in human lung SCC SW900 cells. These results suggest that these cytokines, which were highly expressed in KA/KA lungs, contribute to aberrant lipid metabolism. Because IL-4, which is produced by Th2 T cells, promoted lipid metabolism in macrophages and lung SCC cells, we further showed that KA/KA lung CD4 T cells stimulated lipid gene expression in Raw macrophages compared to WT lung CD4 T cells. Depleting CD4 T cells indeed significantly decreased foamy macrophage formation in the lungs of KA/KA mice. Importantly, treatment with a lipid inhibitor reduced IL-4-mediated lipid metabolism in Raw macrophages and human lung SCC SW900 cells, as well as this treatment attenuated lung foamy macrophage numbers and dampened lung SCC development in irradiated KA/KA mice with KA/KA bone marrow transplants. These findings highlight that the interplay between CD4 T cells, macrophages, cytokines, and epithelial cells contribute to a series of biological events in a landscape scale, which promote lung disease and lung SCC development through aberrant lipid metabolism. Citation Format: Gongping Shi, Sayantan Banerjee, Xin Li, Gajendra Jogdand, Yongmei Zhao, Kunio Nagashima, Thorkell Andresson, Jyoti Shetty, Bao Tran, Yinling Hu. Lipid-rich foamy macrophages along with CD4 T cell-derived signaling drive aberrant lipid metabolism and are a cause of lung cancer development [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1355.

Patients with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) develop chronic mucocutaneous candidiasis during childhood and about 10% of senior patients develop upper GI tract squamous cell carcinoma (SCC), suggesting that C. albicans infection may be relevant to the cause of SCC development in APECED patients. In this study, we investigated the role of C. albicans infection in upper GI tract SCC development using an APECED-like IKKα kinase-dead (KA/KA) mouse model. We found that KA/KA mice developed upper GI tract SCC after oral infection of WT C. albicans weekly for three months. Interestingly, while upper GI tract SCC development in C. albicans - infected KA/KA mice is IL-17a-independent, EGFR pathway plays an important role in C. albicans infection-mediated tumorigenesis in KA/KA mice, as evidenced by significantly lower SCC incidence in the upper GI tract of KA/KA mice infected with Als3Δ/Δ C. albicans. Moreover, upper GI tract SCCs from WT C. albicans-infected KA/KA mice exhibited robust p-EGFR and Ki67 signals. However, both p-EGFR and Ki67 signals were only mildly increased in upper GI tract of Als3Δ/Δ C. albicans-infected KA/KA mice compared to WT control mice. Meanwhile, EGFR inhibition dramatically reduced C. albicans colonization in upper GI tract and the weight of stomach in KA/KA mice. Furthermore, we found that aberrant infiltrations of neutrophils and macrophages with significant inflammatory signatures were present in the upper GI tract SCCs in KA/KA mice. Interestingly, KA/KA neutrophils exhibited a defect in C. albicans killing capacity due to functional defects in ROS generation, degranulation, NETs formation, and apoptosis. We reasoned that KA/KA neutrophils’ inability in C. albicans killing capacity may further enhance the tumor-promoting microenvironment. Finally, whole genome sequencing data suggested that C. albicans infection may lead to genome instability. Currently we are investigating the role of neutrophil infiltration in C. albicans infection-mediated upper GI tract tumorigenesis. Citation Format: Feng Zhu, Quynh T. Phan, Elise M. Ferre, Jami Willette-Brown, Rosalba Salcedo, Tsai-Wei Shen, Yu Fan, Yongmei Zhao, Monika Mehta, Daoud Meerzaman, Bao Tran, Giorgio Trinchieri, Michail S. Lionakis, Scott G. Filler, Yinling Hu. C. albicans infection mediates upper gastrointestinal tract malignancy independently of Il17a in an APECED-like mouse model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3044.

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.

Patients with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy show diverse endocrine and nonendocrine manifestations initiated by self-reactive T cells because of AIRE mutation–induced defective central tolerance. A large number of American patients with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy suffer from early-onset cutaneous inflammatory lesions accompanied by an infiltration of T cells and myeloid cells. The role of myeloid cells in this setting remains to be fully investigated. In this study, we characterize the autoinflammatory phenotypes in the skin of both autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy–like kinase-dead Ikkα knockin mice and patients with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy. We found a marked infiltration of autoreactive CD4 T cells, macrophages, and neutrophils; elevated uric acid; and increased NLRP3, a major inflammasome component. Depleting autoreactive CD4 T cells or ablating Ccl2/Cxcr2 genes significantly attenuated the inflammasome activity, inflammation, and skin phenotypes in kinase-dead Ikkα knockin mice. Importantly, treatment with an NLRP3 inhibitor reduced skin phenotypes and decreased infiltration of CD4 T cells, macrophages, and neutrophils. These results suggest that increased myeloid cell infiltration contributes to autoreactive CD4 T cell–mediated skin autoinflammation. Thus, our findings reveal that the combined infiltration of macrophages and neutrophils is required for autoreactive CD4 T cell–mediated skin disease pathogenesis and that the NLRP3-dependent inflammasome is a potential therapeutic target for the cutaneous manifestations of autoimmune diseases.

Simple Summary Microbiota dysbiosis is correlated with numerous diseases in the human body. To date, the research on the microbiome-associated diseases been focused on an organ-specific microbiome. However, the interorgan microbial network is emerging as an important regulator in physiological functions and pathological processes. The oral cavity and gut are the two largest microbial ecosystems. Recent studies have demonstrated that the oral-to-gut and gut-to-oral microbial transmission can regulate pathogenesis, indicating the presence of the oral–gut microbiome axis. Here, we will review the role of the oral–gut microbiome axis in gastrointestinal disease and cancer, which may provide insight for precise diagnosis/prognosis and effective treatment. Abstract It is well-known that microbiota dysbiosis is closely associated with numerous diseases in the human body. The oral cavity and gut are the two largest microbial habitats, playing a major role in microbiome-associated diseases. Even though the oral cavity and gut are continuous regions connected through the gastrointestinal tract, the oral and gut microbiome profiles are well-segregated due to the oral–gut barrier. However, the oral microbiota can translocate to the intestinal mucosa in conditions of the oral–gut barrier dysfunction. Inversely, the gut-to-oral microbial transmission occurs as well in inter- and intrapersonal manners. Recently, it has been reported that oral and gut microbiomes interdependently regulate physiological functions and pathological processes. Oral-to-gut and gut-to-oral microbial transmissions can shape and/or reshape the microbial ecosystem in both habitats, eventually modulating pathogenesis of disease. However, the oral–gut microbial interaction in pathogenesis has been underappreciated to date. Here, we will highlight the oral–gut microbiome crosstalk and its implications in the pathogenesis of the gastrointestinal disease and cancer. Better understanding the role of the oral–gut microbiome axis in pathogenesis will be advantageous for precise diagnosis/prognosis and effective treatment.

Decreased ATG16L1 stabilization is associated with increased susceptibility to develop inflammatory bowel diseases. Diamanti et al. identify IKKα as a central upstream kinase of ATG16L1, providing evidence that ATG16L1 stabilization is controlled by phosphorylation downstream of TNF and NOD activation., Inhibition of the IκB kinase complex (IKK) has been implicated in the therapy of several chronic inflammatory diseases including inflammatory bowel diseases. In this study, using mice with an inactivatable IKKα kinase (IkkαAA/AA), we show that loss of IKKα function markedly impairs epithelial regeneration in a model of acute colitis. Mechanistically, this is caused by compromised secretion of cytoprotective IL-18 from IKKα-mutant intestinal epithelial cells because of elevated caspase 12 activation during an enhanced unfolded protein response (UPR). Induction of the UPR is linked to decreased ATG16L1 stabilization in IkkαAA/AA mice. We demonstrate that both TNF-R and nucleotide-binding oligomerization domain stimulation promote ATG16L1 stabilization via IKKα-dependent phosphorylation of ATG16L1 at Ser278. Thus, we propose IKKα as a central mediator sensing both cytokine and microbial stimulation to suppress endoplasmic reticulum stress, thereby assuring antiinflammatory function during acute intestinal inflammation.

Purpose The incidence of retinopathy of prematurity (ROP) has increased continuously in recent years. However, the therapeutic effects of current treatments still remain undesired. This study aims to investigate the role of C-CBL in retinal angiogenesis in ROP and its potential as a therapeutic target. Methods Mouse retina microvascular endothelial cells (mRMECs) and induced experimental ROP/ oxygen-induced retinopathy (OIR) mice were employed to investigate the role of C-CBL in angiogenesis with combined molecular and cellular approaches, and histopathology methods. OIR mouse pups at postnatal day 12 (P12) were either injected intravitreally with adenovirus overexpressing c-Cbl or c-Cbl siRNA. Retinal neovascularization and avascular status were evaluated by retinal immunofluorescence (IF) staining, whole-mounts and hematoxylin and eosin (H&E) staining. Results C-CBL inhibits neovascularization by negatively regulating JAK2/STAT3/VEGF signaling axis in a ubiquitination-dependent manner. Knockdown of c-Cbl by siRNA reduced ubiquitin-mediated JAK2 degradation and increased levels of p-JAK2, p-STAT3, VEGF, and neovascularization in mRMECs, which can be reversed by JAK2 inhibitor treatment. While knockdown of c-Cbl significantly increased neovascular (NV) zone in the retinas, c-Cbl overexpression inhibited neovascularization in the retinal tissues in OIR mice. Conclusion We found that C-CBL is required for anti-neovascularization process in ROP development by inhibiting JAK2/STAT3-dependent angiogenesis. Thus, our finding strongly suggest that C-CBL may be a potential novel therapeutic target for treating ROP.

The cytokine Il17a plays an important role in protection against fungal infection, yet it also serves as a pathogenic factor in several inflammation-related cancers. Previously we reported that fungal infection promotes the development of esophageal squamous cell carcinoma (ESCC) in the IKKalpha kinase-dead KA knock-in (KA) mice that mimic a human autoimmune disorder, autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED). Our data showed that KA T cells failed to induce Il17a in response to fungal infection. However, the role of Il17a in fungal infection-mediated esophageal carcinogenesis remains to be further determined. In this study, we crossed KA mice with Il17a-/- mice to generate KA;Il17a-/- double mutant mice. We orally inoculated WT, Il17a-/-, KA, and KA;Il17a-/- mice with Candida albicans weekly for 3 months to investigate gastrointestinal (GI) track tumorigenesis, including the SCC development in the oral cavity, esophagus, and forestomach. We found that loss of Il17a leads to much earlier onset of GI track tumors in KA;Il17a-/- mice than that in KA mice. KA;Il17a-/- mice also died much earlier compared to KA mice, which is likely due to increased C. albicans burden in the absence of Il17a. The incidence of GI track tumors is comparable between KA and KA;Il17a-/- mice, suggesting that C. albicans infection-associated GI track tumorigenesis is independent of Il17a in KA mouse model. To further understand the underlying mechanism, we performed single-cell RNA sequencing analysis for CD45+ immune cells isolated from long-term C. alibicans-infected mouse esophagi of WT, Il17a-/-, KA, and KA;Il17a-/- mouse cohorts. Interestingly, the neutrophil population was significantly increased in the esophagi of KA and KA;Il17a-/- mice compared to WT and Il17a-/- mice. However, KA neutrophils exhibited reduced capacity in killing C. albicans with reduced NETs formation compared to WT neutrophils, suggesting that the defect in NETs formation may play a pivotal role in GI track tumorigenesis in the context of fungal infection. We are currently investigating how the interplay between C. albicans infection and host neutrophils regulates Candida infection-associated GI track tumorigenesis. This abstract is also being presented as Poster B01. Citation Format: Feng Zhu, Jami Willette-Brown, Trang Phan, Yongmei Zhao, Bao Tran, Scott G. Filler, Mihalis S. Lionakis, Yinling Hu. Candida albicans infection mediates gastrointestinal track malignancy independently of Il17a in an APECED mouse model [abstract]. In: Proceedings of the AACR Special Conference on the Microbiome, Viruses, and Cancer; 2020 Feb 21-24; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2020;80(8 Suppl):Abstract nr PR10.

Clinically, oral fungating lesions frequently occur in cancer patients following radiation and chemotherapy. However, their role in carcinogenesis has not been fully understood. Our previous finding showed that defective IKKα-mediated autoreactive T cells promote fungal infection and esophageal malignancy, but whether IKKα-mediated altered epithelial properties regulate fungal colonization and carcinogenesis remains to be tested. To investigate whether IKKα-mediated altered epithelial properties regulate fungal colonization and carcinogenesis, we orally infected mice lacking Ikkα (IkkαΔSOE) or both Ikkα and Stat3 (IkkαΔSOEStat3ΔSOE) in the stem cells of the skin and mouth with fungi. We found that oral fungal infection enhanced Ikkα ablation-mediated skin and oral carcinogenesis in association with increased oral and skin bacteria counts and altered oral bacteria phylum from gram-positive to gram-negative. Enhanced oral fungal/bacterial infection increased inflammasome activities and systemic IL-17A/IL-1β signals. Surprisingly, Stat3 ablation rescued these phenotypes in IkkαΔSOEStat3ΔSOE mice. In addition, amoxicillin treatment inhibited skin carcinogenesis and oral/skin bacteria counts and reversed oral bacteria phyla in fungal-inoculated IkkαΔSOE mice. These findings highlight that cancer cell IKKα/STAT3 antagonizing pathways determine susceptibility to fungal and bacterial colonization, which impacts carcinogenesis. Human head and neck squamous cell carcinomas also share oncogenic pathways and bacteria sequences/counts with mice, suggesting that oral fungating/ulcerating lesions enhance local and distal tumorigenesis in humans. Citation Format: Na-Young Song, Xin Li, Jonathan H. Badger, Jami Willette Brown, Xhonghe Sun, Gongping Shi, Feng Zhu, Chengfei Jiang, Colum O'hUigin, Xiaolin Wu, Giorgio Trinchieri, Yinling Hu. IKKα/STAT3 antagonistic signaling regulates fungi-bacteria endosymbiosis-associated carcinogenesis [abstract]. In: Proceedings of the AACR Special Conference on the Microbiome, Viruses, and Cancer; 2020 Feb 21-24; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2020;80(8 Suppl):Abstract nr B17.

Viruses are present in the intestinal microflora and are currently discussed as a potential causative mechanism for the development of inflammatory bowel disease. A number of viruses, such as Human Herpesvirus-8, express homologs to cellular FLIPs, which are major contributors for the regulation of epithelial cell death. In this study we analyzed the consequences of constitutive expression of HHV8-viral FLIP in intestinal epithelial cells (IECs) in mice. Surprisingly, expression of vFlip disrupts tissue homeostasis and induces severe intestinal inflammation. Moreover vFlip(IEC-tg) mice showed reduced Paneth cell numbers, associated with excessive necrotic cell death. On a molecular level vFlip expression altered classical and alternative NFκB activation. Blocking of alternative NFκB signaling by deletion of Ikka in vivo largely protected mice from inflammation and Paneth cell loss induced by vFLIP. Collectively, our data provide functional evidence that expression of a single viral protein in IECs can be sufficient to disrupt epithelial homeostasis and to initiate chronic intestinal inflammation.

Only few genes have been confidently identified to be involved in the Follicular (FO) and Marginal Zone (MZ) B cell differentiation, migration, and retention in the periphery. Our group previously observed that IKKα kinase inactive mutant mice IKKα(K44A/K44A) have significantly lower number of MZ B cells whereas FO B cell numbers appeared relatively normal. Because kinase dead IKKα can retain some of its biological functions that may interfere in revealing its actual role in the MZ and FO B cell differentiation. Therefore, in the current study, we genetically deleted IKKα from the pro-B cell lineage that revealed novel functions of IKKα in the MZ and FO B lymphocyte development. The loss of IKKα produces a significant decline in the percentage of immature B lymphocytes, mature marginal zone B cells, and follicular B cells along with a severe disruption of splenic architecture of marginal and follicular zones. IKKα deficiency affect the recirculation of mature B cells through bone marrow. A transplant of IKKα knockout fetal liver cells into Rag(−/−) mice shows a significant reduction compared to control in the B cells recirculating through bone marrow. To reveal the genes important in the B cell migration, a high throughput gene expression analysis was performed on the IKKα deficient recirculating mature B cells (B220(+)IgM(hi)). That revealed significant changes in the expression of genes involved in the B lymphocyte survival, homing and migration. And several among those genes identified belong to G protein family. Taken together, this study demonstrates that IKKα forms a vial axis controlling the genes involved in MZ and FO B cell differentiation and migration.

Human lung squamous cell carcinoma (SCC) is highly associated with increased pulmonary macrophage infiltration. Previously, we showed that marked pulmonary infiltrating macrophages were required for spontaneous lung SCC development in a mouse model (L-Ikkα KA/KA , KA/KA) that resembles human lung SCC. Interestingly the lung SCC-associated macrophages specifically express elevated inducible nitric oxide synthase (NOS2). However, the role of macrophage NOS2 in lung carcinogenesis has not been explored. Here, we show that NOS2 ablation inhibits macrophage infiltration, fibrosis, and SCC development in the lungs of KA/KA mice. Macrophage NOS2 was found to circulate inflammation and enhance macrophage migration and survival. NOS2 promotes foamy macrophage formation characterized with impaired lipid metabolism. NOS2 null bone marrow transplantation reduces foamy macrophage numbers and carcinogenesis in KA/KA chimaeras. This finding sheds light on a new mechanism by which macrophage NOS2 increases pulmonary inflammatory responses and macrophage survival and impairs macrophage lipid metabolism, thereby promoting lung SCC formation.

Significance Reactive oxygen species (ROS) can promote tumorigenesis or kill cancer cells. How different cancer-associated genetic alterations regulate ROS balance and outcome is of great importance for the design of rational cancer treatments, many of which affect ROS metabolism and sensing. Kras activation induces a ROS defense system and cell senescence, which counteract its oncogenic activity. KRAS-activating mutations are accompanied by IKKα loss mutations that result in elevated NOX2 but decreased expression of the NRF2 ROS defense system. Thus, IKKα ablation turns the antitumorigenic effect of Kras-induced ROS to a protumorigenic effect that enhances Kras-induced progression of lung adenocarcinoma (ADC). Restoration of IKKα activity or inhibition of the pathways activated on its loss may offer new opportunities for ADC treatment., Lung adenocarcinoma (ADC) and squamous cell carcinoma (SCC) are two distinct and predominant types of human lung cancer. IκB kinase α (IKKα) has been shown to suppress lung SCC development, but its role in ADC is unknown. We found inactivating mutations and homologous or hemizygous deletions in the CHUK locus, which encodes IKKα, in human lung ADCs. The CHUK deletions significantly reduced the survival time of patients with lung ADCs harboring KRAS mutations. In mice, lung-specific Ikkα ablation (IkkαΔLu) induces spontaneous ADCs and promotes KrasG12D-initiated ADC development, accompanied by increased cell proliferation, decreased cell senescence, and reactive oxygen species (ROS) accumulation. IKKα deletion up-regulates NOX2 and down-regulates NRF2, leading to ROS accumulation and blockade of cell senescence induction, which together accelerate ADC development. Pharmacologic inhibition of NADPH oxidase or ROS impairs KrasG12D-mediated ADC development in IkkαΔLu mice. Therefore, IKKα modulates lung ADC development by controlling redox regulatory pathways. This study demonstrates that IKKα functions as a suppressor of lung ADC in human and mice through a unique mechanism that regulates tumor cell-associated ROS metabolism.

BackgroundAutoimmune disease is generally a systemic inflammatory response with production of autoantibodies. In this study, we investigated the anti-microbial antibodies in circulation in cases of Crohn’s disease (CD), Sjogren’s syndrome (SS) and other autoimmune disease and their roles in the pathogenesis of these autoimmune diseases.Material and methodsWestern blot was used to determine the reactivity of human plasmas from patients with CD and SS as the primary antibodies against the whole microbial extracts. The microbial proteins reactive to patients’ plasma were further identified and the modified sandwich ELISA assays were used to determine the blood levels of antibodies against these microbial proteins in patients with CD and SS. Antibodies against the microbial proteins are used for immunohistochemical staining of normal human tissue.ResultsA group of 7 microbial proteins was identified reactive to the plasmas of patients with CD and SS including DNA-directed RNA polymerase B (RPOB), and elongation factor G (EF-G) fromStaphylococcus aureusandStaphylococcus pseudintermedius(S. aureusandS. pseudintermedius), ATP synthase alpha (ATP5a) and heat shock protein 65 (Hsp65) fromMycobacterium avium subspecies paratuberculosis(MAP), elongation factor Tu (EF-Tu) and outer membrane porin C (ompC) fromEscherichia Coli(E. coli). Anti-microbial antibodies can cross-react to normal human tissues. The levels of antibodies against the microbial proteins are significantly elevated in the patients with CD and SS.ConclusionThe levels of antibodies against the microbial proteins are significantly elevated in CD and SS. The cross-reactivity of the anti-microbial antibodies to human tissue provides a new mechanism of pathogenesis of autoimmune diseases such as CD and SS.

Our previous studies have shown that the absence of tumor suppressor IKKα leads to development of spontaneous mouse squamous cell carcinomas (SCCs) in the skin, lungs, and esophagus, which is partially mediated by aberrant epigenetic alterations and inflammation. However, it remains unknown whether there is a crosstalk between the above-mentioned mechanisms. As a part of the epigenetic machinery, miRNAs regulate many genes post-transcriptionally. Here we show that IKKα deletion in the mouse epidermis results in impaired miRNA processing with markedly reduced expression of ribonuclease Dicer, an enzyme required for miRNA maturation. We found that the lack of IKKα causes Dicer gene silencing through DNA methylation. As a result, the maturation of miR-203-3p, which is the most abundant miRNA in keratinocytes, is blocked in Ikkα-null keratinocytes. Next, we identified Myd88, an important component of innate immunity and inflammation, as one of miR-203-3p targets. The level of Myd88 expression is robustly increased in Ikkα-null keratinocytes due to the lack of miR-203-3p. We also observed increased activity of caspase 1 cleavage, an indicator of inflammasome activation, in Ikkα-null keratinocytes. Interestingly, Myd88 deletion or 5-aza-2’-deoxycytidine (DNA methyltransferase inhibitor) treatment rescued the survival of Ikkαf/f;K5Cre mice, which usually die within three weeks after birth. Ikkαf/f;Myd88f/f;K5Cre mice also develop much fewer spontaneous skin tumors. By analyzing a cohort of human head and neck SCCs from TCGA database, we found that Dicer expression is concurrently downregulated among 32% of patients with low IKKα expression. Taken together, our finding illustrated how IKKα loss mediates Dicer gene silencing, which turns off miRNA processing, including miR-203-3p maturation, and eventually triggers Myd88-dependent inflammation. Thus, our study revealed a novel IKKα/Dicer/miR-203-3p/Myd88 signaling loop, in which IKKα serves as a molecular switch linking microRNA biogenesis and inflammation in skin tumorigenesis. Citation Format: Feng Zhu, Jian Zhang, Jami Willette-Brown, Ling Su, Xiaolin Wu, Yinling Hu. IKKa serves as a molecular switch linking miRNA biogenesis and inflammation in skin tumorigenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2355.

NLRC5 is an important regulator in innate immune responses. However, the ability of NLRC5 to inhibit NF-κB activation is controversial in different cell types. How dynamic modification of NLRC5 shapes NF-κB signaling remains unknown. We demonstrated that NLRC5 undergoes robust ubiquitination by TRAF2/6 after lipopolysaccharide treatment, which leads to dissociation of the NLRC5-IκB kinase complex. Experimental and mathematical analyses revealed that the K63-linked ubiquitination of NLRC5 at lysine 1,178 generates a coherent feedforward loop to further sensitize NF-κB activation. Meanwhile, we found USP14 specifically removes the polyubiquitin chains from NLRC5 to enhance NLRC5-mediated inhibition of NF-κB signaling. Furthermore, we found that different cell types may exhibit different sensitivities to NF-κB activation in response to NLRC5 ablation, possibly as a result of the various intrinsic levels of deubiquitinases and NLRC5. This might partially reconcile controversial studies and explain why NLRC5 exhibits diverse inhibitory efficiencies. Collectively, our results provide the regulatory mechanisms of reversible NLRC5 ubiquitination and its role in the dynamic control of innate immunity.

The inflammatory microenvironment promotes skin tumorigenesis. However, the mechanisms of how cells protect themselves from inflammatory signals have yet to be revealed. Downregulation of IKKα promotes skin tumor progression from papillomas to squamous cell carcinomas, which is frequently accompanied by genomic instability, including aneuploid chromosomes and extra centrosomes. In this study, we found that IKKα promoted oligomerization of nucleophosmin (NPM), a negative centrosome duplication regulator, which further enhanced NPM and centrosome association, inhibited centrosome amplification, and maintained genome integrity. Levels of NPM hexamers and IKKα were conversely associated with skin tumor progression. Importantly, pro-inflammatory cytokine-induced IKKα activation promoted the formation of NPM oligomers and reduced centrosome numbers in mouse and human cells, whereas kinase-dead IKKα blocked this connection. Therefore, our findings suggest a previously unknown mechanism in which an IKKα-NPM axis may use the inflammatory signal to suppress centrosome amplification, promote genomic integrity, and prevent tumor progression.

SummaryBAFF is a soluble factor required for B cell maturation and survival. BAFF-R signals via the noncanonical NF-κB pathway regulated by the TRAF3/NIK/IKK1 axis. We show that deletion of Ikk1 during early B cell development causes a partial impairment in B cell maturation and BAFF-dependent survival, but inactivation of Ikk1 in mature B cells does not affect survival. We further show that BAFF-R employs CD19 to promote survival via phosphatidylinositol 3-kinase (PI3K), and that coinactivation of Cd19 and Ikk1 causes a profound block in B cell maturation at the transitional stage. Consistent with a role for PI3K in BAFF-R function, inactivation of PTEN mediates a partial rescue of B cell maturation and function in Baff−/− animals. Elevated PI3K signaling also circumvents BAFF-dependent survival in a spontaneous B cell lymphoma model. These findings indicate that the combined activities of PI3K and IKK1 drive peripheral B cell differentiation and survival in a context-dependent manner.

Here, we report that kinase-dead IKKα knockin mice develop spontaneous lung squamous cell carcinomas (SCCs) associated with IKKα downregulation and marked pulmonary inflammation. IKKα reduction upregulated the expression of p63, Trim29, and keratin 5 (K5), which serve as diagnostic markers for human lung SCCs. IKKα(low)K5(+)p63(hi) cell expansion and SCC formation were accompanied by inflammation-associated deregulation of oncogenes, tumor suppressors, and stem cell regulators. Reintroducing transgenic K5.IKKα, depleting macrophages, and reconstituting irradiated mutant animals with wild-type bone marrow (BM) prevented SCC development, suggesting that BM-derived IKKα mutant macrophages promote the transition of IKKα(low)K5(+)p63(hi) cells to tumor cells. This mouse model resembles human lung SCCs, sheds light on the mechanisms underlying lung malignancy development, and identifies targets for therapy of lung SCCs.

Gene knockout studies unexpectedly reveal a pivotal role for IkB kinase alpha (IKKa) in mouse embryonic skin development. Skin carcinogenesis experiments show that Ikka heterozygous mice are highly susceptible to chemical carcinogen or ultraviolet B light (UVB) induced benign and malignant skin tumors in comparison to wild-type mice. IKKa deletion mediated by keratin 5 (K5).Cre or K15.Cre in keratinocytes induces epidermal hyperplasia and spontaneous skin squamous cell carcinomas (SCCs) in Ikka floxed mice. On the other hand, transgenic mice overexpressing IKKa in the epidermis, under the control of a truncated loricrin promoter or K5 promoter, develop normal skin and show no defects in the formation of the epidermis and other epithelial organs, and the transgenic IKKa represses chemical carcinogen or UVB induced skin carcinogenesis. Moreover, IKKa deletion mediated by a mutation, which generates a stop codon in the Ikka gene, has been reported in a human autosomal recessive lethal syndrome. Downregulated IKKa and Ikka mutations and deletions are found in human skin SCCs. The collective evidence not only highlights the importance of IKKa in skin development, maintaining skin homeostasis, and preventing skin carcinogenesis, but also demonstrates that mouse models are extremely valuable tools for revealing the mechanisms underlying these biological events, leading our studies from bench side to bedside.

Humans with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED), a T cell–driven autoimmune disease caused by impaired central tolerance, are susceptible to developing chronic fungal infection and esophageal squamous cell carcinoma (ESCC). However, the relationship between autoreactive T cells and chronic fungal infection in ESCC development remains unclear. We find that kinase-dead Ikkα knockin mice develop phenotypes reminiscent of APECED, including impaired central tolerance, autoreactive T cells, chronic fungal infection, and ESCCs expressing specific human ESCC markers. Using this model, we investigated the potential link between ESCC and fungal infection. Autoreactive CD4 T cells permit fungal infection and incite tissue injury and inflammation. Antifungal treatment or depletion of autoreactive CD4 T cells rescues, whereas oral fungal administration promotes, ESCC development. Inhibition of inflammation or EGFR activity decreases fungal burden. Importantly, fungal infection is highly associated with ESCCs in non-autoimmune human patients. Therefore, autoreactive T cells and chronic fungal infection, fostered by inflammation and epithelial injury, promote ESCC development.

IκB kinase alpha (Ikk-α) gene mutations and IKK-α downregulation have been detected in various human squamous cell carcinomas (SCCs), which are malignancies derived from squamous epithelial cells. These squamous epithelial cells distribute to many organs in the body; however, the epidermis is the only organ mainly composed of stratified squamous epithelial cells, called keratinocytes. SCC is the second most common type of skin cancer. Reducing IKK-α expression promotes tumor initiation, and its loss greatly enhances tumor progression from benign papillomas to malignant carcinomas during chemical skin carcinogenesis in mice. Thus, IKK-α has emerged as a tumor suppressor for SCCs. Furthermore, inducible deletion of IKK-α in the keratinocytes of adult mice causes spontaneous skin papillomas and carcinomas, indicating that IKK-α deletion functions as a tumor initiator as well as a tumor promoter. This article discusses IKK-α biological activities and associated molecular events in skin tumor development, which may provide insight into the diagnosis, treatment, and prevention of human squamous cell carcinomas (SCCs) in the future.

Bacteria and fungi, two major components of the microbiota, generally share niches and develop both antagonistic and symbiotic relationships, regulating the pathological impacts on the host. The epithelium is where the bacterial-fungal interaction occurs most abundantly, but the relationship between the epithelium, bacteria, and fungi on the pathogenesis of numerous diseases, particularly tumorigenesis, is poorly understood. IKKα is one of the crucial factors regulating the homeostasis of squamous epithelial tissues. Recently, our lab has established a mouse model that develops esophageal squamous cell carcinomas (SCCs) associated with IKKα reduction, inflammation and chronic fungal infection. Cladosporium cladosporioides was a major type of fungi identified in this mouse model. Because IKKα deletion in the keratinocytes causes impaired skin barrier, we hypothesized that loss of epithelial IKKα may control fungal colonization through regulating the barrier integrity and inflammation, resulting in tumor promotion. We thus generated IKKαf/f mice with inducible K15.Cre (IKKαf/f/K15.Cre) which is expressed in skin stem cells, which are important for the epidermal formation and hair follicle development. After ablating IKKα in K15 cells in the oral mucosa and skin, IKKαf/f/K15.Cre mice were orally inoculated with Cladosporium cladosporioides. Loss of epithelial IKKα showed disruption of skin barrier functions and bacterial colonization in the oral mucosa and skin, oral dysplasia and skin SCC development. Interestingly, oral infection with Cladosporium further promoted bacterial colonization as well as skin tumorigenesis in IKKαf/f/K15.Cre mice. This suggests that epithelial IKKα loss can provoke oral bacterial-fungal symbiosis which contributes to tumor promotion. To confirm this hypothesis, we treated Cladosporium-infected IKKαf/f/K15.Cre mice with amoxicillin, an antibiotic, through drinking water. Amoxicillin treatment remarkably reduced skin tumor incidence in fungal-infected IKKαf/f/K15.Cre mice, indicating that oral bacterial-fungal symbiosis indeed promotes skin SCC development driven by epithelial IKKα reduction. We also detected bacterial colonization in human skin SCC tissue array as well as IKKα mutation in 17% of human skin SCC patients from the Cancer Genome Atlas database, supporting that the crosstalk between epithelial IKKα and bacterial-fungal symbiosis in skin SCC promotion is relavent to human diseases. Taken together, our data demonstrate that loss of epithelial IKKα induces the bacterial-fungal symbiosis in oral mucosa, promoting skin tumors. This study will shed light on the importance of the epithelial-bacterial-fungal interaction in the pathogenesis, proposing epithelial IKKα as a novel regulator of the bacterial-fungal interaction. Citation Format: Na-Young Song, Jami Willette-Brown, Feng Zhu, Yinling Hu. Crosstalk between epithelial-IKKα-deletion and symbiotic bacterial-fungal infection in skin carcinogenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5008.

Ultraviolet B light (UVB) is a common cause of human skin cancer. UVB irradiation induces mutations in the tumor suppressor p53 gene as well as chronic inflammation, which are both essential for UVB carcinogenesis. Inhibitor of nuclear factor kappaB kinase-alpha (IKKalpha) plays an important role in maintaining skin homeostasis, and expression of IKKalpha was found to be down-regulated in human and murine skin squamous cell carcinomas. However, the role of IKKalpha in UVB skin carcinogenesis has not been investigated. Thus, here we performed UVB carcinogenesis experiments on Ikkalpha(+/+) and Ikkalpha(+/-) mice. Ikkalpha(+/-) mice were found to develop a twofold greater number of skin tumors than Ikkalpha(+/+) mice after chronic UVB irradiation. In addition, tumor latency was significantly shorter and tumors were bigger in Ikkalpha(+/-) than in Ikkalpha(+/+) mice. At an early stage of carcinogenesis, an increase in UVB-induced p53 mutations as well as macrophage recruitment and mitogenic activity, and a decrease in UVB-induced apoptosis, were detected in Ikkalpha(+/-) compared with those in Ikkalpha(+/+) skin. Also, reduction of IKKalpha levels in keratinocytes up-regulated the expression of monocyte chemoattractant protein-1 (MCP-1/CCL2), TNFalpha, IL-1, and IL-6, and elevated macrophage migration, which might promote macrophage recruitment and inflammation. Therefore, these findings suggest that reduction of IKKalpha expression orchestrates UVB carcinogen, accelerating tumorigenesis.

Keratinocyte differentiation is the process of cellular maturation from a mitotic state to a terminally differentiated state during which skin builds up a tough yet soft skin barrier to protect the body. Its irreversibility also allows the shedding of excessive keratinocytes, thereby maintaining skin homeostasis and preventing skin diseases. Although the entire journey of keratinocyte differentiation is intricate and not well understood, it is known that Ras is able to block keratinocyte terminal differentiation and instead induce keratinocyte proliferation and transformation. It appears that uncontrolled proliferation actually interrupts differentiation. However, it has been unclear whether there are any innate surveillants that would be able to induce terminal differentiation by antagonizing excessive mitotic activities. Inhibitor of nuclear factor kappaB kinase-alpha (IKKalpha, previously known as Chuk) emerges as a master regulator in the coordinative control of keratinocyte differentiation and proliferation and as a major tumor suppressor in human and mouse skin squamous cell carcinomas. IKKalpha does so largely by integrating into the epidermal growth factor receptor (EGFR)/Ras/extracellular signal-regulated kinase (Erk)/EGFR ligand pathways during mitosis and differentiation. We discuss these findings herein to extend our understanding of how IKKalpha-mediated terminal differentiation serves as an innate surveillant in skin.

We reported recently a marked reduction in IκB kinase α (IKKα) expression in a large proportion of human poorly differentiated squamous cell carcinomas (SCC) and the occurrence of Ikkα mutations in human SCCs. In addition, overexpression of IKKα in the epidermis inhibited the development of skin carcinomas and metastases in mice. However, whether a reduction in IKKα expression promotes skin tumor development is currently unknown. Here, we assessed the susceptibility of Ikkα hemizygotes to chemical carcinogen-induced skin carcinogenesis. Ikkα+/− mice developed 2 times more papillomas and 11 times more carcinomas than did Ikkα+/+ mice. The tumors were larger in Ikkα+/− than in Ikkα+/+ mice, but tumor latency was shorter in Ikkα+/− than in Ikkα+/+ mice. Some of the Ikkα+/− papillomas and most Ikkα+/− carcinomas lost the remaining Ikkα wild-type allele. Somatic Ikkα mutations were detected in carcinomas and papillomas. The chemical carcinogen-induced H-Ras mutations were detected in all the tumors. The phorbol ester tumor promoter induced higher mitogenic and angiogenic activities in Ikkα+/− than in Ikkα+/+ skin. These elevated activities were intrinsic to keratinocytes, suggesting that a reduction in IKKα expression provided a selective growth advantage, which cooperated with H-Ras mutations to promote papilloma formation. Furthermore, excessive extracellular signal-regulated kinase and IKK kinase activities were observed in carcinomas compared with those in papillomas. Thus, the combined mitogenic, angiogenic, and IKK activities might contribute to malignant conversion. Our findings provide evidence that a reduction in IKKα expression promotes the development of papillomas and carcinomas and that the integrity of the Ikkα gene is required for suppressing skin carcinogenesis. [Cancer Res 2007;67(19):9158–68]

We recently reported that a large proportion of aggressive squamous cell carcinomas of humans and mice express markedly reduced IKKalpha. However, the role of IKKalpha in maintaining genomic stability is unknown. Here we reported that IKKalpha-deficient keratinocytes had a defect in the G(2)/M cell-cycle arrest in response to DNA damage due to downregulated 14-3-3sigma, a cell cycle checkpoint protein. Trimethylated histone H3 lysine 9 (H3-K9) was found to associate with the histone trimethyltransferase Suv39h1 and DNA methyltransferase Dnmt3a in the methylated 14-3-3sigma locus. Reintroduction of IKKalpha restored the expression of 14-3-3sigma. IKKalpha was found to associate with H3 in 14-3-3sigma, which prevented access of Suv39h1 to H3, thereby preventing hypermethylation of 14-3-3sigma. IKKalpha mutants that failed to bind to H3 did not restore the expression of 14-3-3sigma. Thus, IKKalpha protects the 14-3-3sigma locus from hypermethylation, which serves as a mechanism of maintaining genomic stability in keratinocytes.

// Eyra Marien 1 , Michael Meister 2,3 , Thomas Muley 2,3 , Teresa Gomez del Pulgar 4 , Rita Derua 5 , Jeffrey M. Spraggins 6 , Raf Van de Plas 6,7 , Frank Vanderhoydonc 1 , Jelle Machiels 1 , Maria Mercedes Binda 8 , Jonas Dehairs 1 , Jami Willette-Brown 9 , Yinling Hu 9 , Hendrik Dienemann 3,10 , Michael Thomas 3,11 , Philipp A. Schnabel 3,12 , Richard M. Caprioli 6 , Juan Carlos Lacal 4 , Etienne Waelkens 5 and Johannes V. Swinnen 1 1 KU Leuven – University of Leuven, LKI - Leuven Cancer Institute, Department of Oncology, Laboratory of Lipid Metabolism and Cancer, Leuven, Belgium 2 Thoraxklinik at University Hospital Heidelberg, Translational Research Unit, Heidelberg, Germany 3 TLRC-H – Translational Lung Research Center Heidelberg, Member of The German Center for Lung Research, Heidelberg, Germany 4 Fundacion Jimenez Diaz, Division of Translational Oncology, Madrid, Spain 5 KU Leuven – University of Leuven, Department of Cellular and Molecular Medicine, Laboratory of Protein Phosphorylation and Proteomics, Leuven, Belgium 6 Vanderbilt University Medical Center, Department of Biochemistry and Mass Spectrometry Research Center, Nashville, TN, USA 7 Delft University of Technology, Delft Center for Systems and Control, Delft, The Netherlands 8 KU Leuven – University of Leuven, LKI - Leuven Cancer Institute, Department of Oncology, Abdominal Surgical Oncology, Leuven, Belgium 9 National Cancer Institute, Centre for Cancer Research, Cancer and Inflammation Program, Frederick, MD, USA 10 Thoraxklinik at University Hospital Heidelberg, Department of Surgery, Heidelberg, Germany 11 Thoraxklinik at University Hospital Heidelberg, Department of Thoracic Oncology, Heidelberg, Germany 12 University of The Saarland, Institut fur Allgemeine und Spezielle Pathologie, Homburg/Saar, Germany Correspondence to: Johannes V. Swinnen, email: // Keywords : lipidomics, phospholipids, cancer, ELOVL, lung SCC Received : December 17, 2015 Accepted : January 04, 2016 Published : February 03, 2016 Abstract Lung cancer is the leading cause of cancer death. Beyond first line treatment, few therapeutic options are available, particularly for squamous cell carcinoma (SCC). Here, we have explored the phospholipidomes of 30 human SCCs and found that they almost invariably (in 96.7% of cases) contain phospholipids with longer acyl chains compared to matched normal tissues. This trait was confirmed using in situ 2D-imaging MS on tissue sections and by phospholipidomics of tumor and normal lung tissue of the L-Ikkα KA/KA mouse model of lung SCC. In both human and mouse, the increase in acyl chain length in cancer tissue was accompanied by significant changes in the expression of acyl chain elongases (ELOVLs). Functional screening of differentially expressed ELOVLs by selective gene knockdown in SCC cell lines followed by phospholipidomics revealed ELOVL6 as the main elongation enzyme responsible for acyl chain elongation in cancer cells. Interestingly, inhibition of ELOVL6 drastically reduced colony formation of multiple SCC cell lines in vitro and significantly attenuated their growth as xenografts in vivo in mouse models. These findings identify acyl chain elongation as one of the most common traits of lung SCC discovered so far and pinpoint ELOVL6 as a novel potential target for cancer intervention.

IKK (IκB kinase) α is essential for embryonic skin development in mice. Mice deficient in IKKα display markedly hyperplasic epidermis that lacks terminal differentiation, and they die because of this severely impaired skin. However, the function of IKKα in human skin diseases remains largely unknown. To shed light on the role of IKKα in human skin diseases, we examined IKKα expression and Ikk α mutations in human squamous cell carcinomas (SCCs). We found a marked reduction in IKKα expression in poorly differentiated human SCCs and identified Ikk α mutations in exon 15 of Ikk α in eight of nine human SCCs, implying that IKKα is involved in development of this human skin cancer. Furthermore, in a chemical carcinogen-induced skin carcinogenesis setting, mice overexpressing human IKKα in the epidermis under the control of a truncated loricrin promoter developed significantly fewer SCCs and metastases than did wild-type mice. The IKKα transgene altered the skin microenvironment conditions, leading to elevated terminal differentiation in the epidermis, reduced mitogenic activity in the epidermis, and decreased angiogenic activity in the skin stroma. Thus, overexpression of IKKα in the epidermis antagonized chemical carcinogen-induced mitogenic and angiogenic activities, repressing tumor progression and metastases.

IKK alpha is a component of the I kappa B kinase (IKK) complex that plays a key role in the activation of NF-kappa B. In Ikk alpha mutant mice and mice expressing a transdominant negative mutant of I kappa B alpha (cI kappa B alpha Delta N), molars have abnormal cusps, indicating that Ikk alpha is involved in cusp formation through the NF-kappa B pathway. However, Ikk alpha mutant incisors also have an earlier phenotype where epithelium evaginates outward into the developing oral cavity rather than invaginating into the underlying mesenchyme. A similar evagination of epithelium was also observed in whisker development, suggesting that Ikk alpha contributes to the direction of epithelial growth during the early stages of development in many ectodermal appendages. Since cI kappa B alpha Delta N mice have normal incisor epithelial invagination, Ikk alpha's role appears to be NF-kappa B independent. Changes in Notch1, Notch2, Wnt7b, and Shh expression found in incisor epithelium of Ikk alpha mutants suggest that this NF-kappa B-independent function is mediated by Notch/Wnt/Shh signaling pathways.

Human esophageal cancer is the sixth leading cause of cancer death worldwide. More than 90% of esophageal cancer is esophageal squamous cell carcinoma (ESCC). While the etiological causes remain unclear, esophageal mucosal fungal infection is very common in esophageal cancer patients, including patients with autoimmune polyendocrinopathy candidiasis ectodermal dystrophy (APECED) who have more than 20-fold risk of ESCC when compared to the healthy population. Here, we report that kinase-dead Ikka knock-in mice (hereafter referred to as mutant mice) develop APECED-like autoimmune disease due to developmental defects in thymus and lack of central tolerance. Similar to human APECED patients who develop esophageal mucosal fungal infection on average at the age of five, mutant mice develop fungal infection in oral cavity and esophagus as early as seven weeks old. About 20% of mutant mice develop ESCC during aging, which exhibits specific molecular signatures observed in human ESCC, such as p16 gene silencing, elevated EGFR phosphorylation and PD-L1 expression, etc. Autoreactive T cell depletion, or central tolerance reconstitution and/or normal T cell transfer prevents fungal infection and ESCC development in mutant mice. Importantly, antifungal drug treatment inhibits inflammation and ESCC development in mutant mice. However, oral inoculation of Clasdosporium, one of the major fungal species isolated from mutant mice, increases the tumor incidence from 20% to 63% in mutant mice. These results reveal that immune dysfunction and fungal infection is associated with ESCC development, which sheds new light on ESCC etiological factors, prevention and treatment. Citation Format: Feng Zhu, Jami Willette-Brown, Na-young Song, Peilin Zhang, Yinling Hu. Immune dysfunction and fungal infection contribute to esophageal carcinogenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4802. doi:10.1158/1538-7445.AM2017-4802

Bacteria and fungi, two major components of the microbiota, generally share niches and develop both antagonistic and symbiotic relationships, regulating the pathological impacts on the host. The epithelium is where the bacterial-fungal interaction occurs most abundantly, but the relationship between the epithelium, bacteria, and fungi on the pathogenesis, particularly tumorigenesis, is poorly understood. IKKα is one of the crucial factors regulating the homeostasis of squamous epithelial tissues. Recently, our lab has established a mouse model that develops esophageal squamous cell carcinomas associated with IKKα reduction, inflammation and chronic fungal infection. Cladosporium cladosporioides was a major type of fungi identified in this mouse model. Because IKKα deletion in the keratinocytes causes impaired skin barrier, we hypothesized that loss of epithelial IKKα may control fungal colonization through regulating the barrier integrity and inflammation. We generated IKKαf/f mice with inducible K15.Cre (IKKαf/f/K15.Cre) specifically expressed in keratinocytes in hair follicles which is considered as skin stem cells. After deleting IKKα in K15 cells in oral mucosa and skin, IKKαf/f/K15.Cre mice were orally inoculated with Cladosporium cladosporioides. We found that epithelial IKKα deletion increased bacterial colonization in oral mucosa and skin. Moreover, Cladosporium infection further promoted bacterial and fungal colonization in oral cavity and development of skin tumors. Taken together, our data suggest that loss of epithelial IKKα induces the bacterial-fungal symbiosis in oral mucosa, promoting skin tumors. This study will shed light on the importance of the epithelial-bacterial-fungal interaction in the pathogenesis, proposing epithelial IKKα as a novel regulator of the bacterial-fungal interaction. Citation Format: Na-Young Song, Jami Willette-Brown, Feng Zhu, Yinling Hu. Determining the signaling pathway of epithelial-IKKα deletion-mediated symbiotic bacterial and fungal infection in carcinogenesis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1986. doi:10.1158/1538-7445.AM2017-1986

It was reported that TNF receptor type II signaling, which has the capacity to stimulate CD4+ forkhead box P3+ (Foxp3+) regulatory T cells (Tregs), activated the noncanonical NF-κB pathway in an IKKα-dependent manner. Therefore, we studied the role of IKKα in the homeostasis of Treg population. To this end, we generated a mouse strain with conditional knockout of IKKα in CD4 cells (Ikkαf/f:CD4.Cre) that showed a >60% reduction in the number of Tregs in the thymus and peripheral lymphoid tissues, whereas the number of Foxp3− effector T cells (Teffs) remained at a normal level. The function of Tregs deficient in IKKα was examined using Rag1−/− mice cotransferred with naive CD4 cells (nCD4s). Although wild-type (WT) Tregs inhibited colitis induced by transfer of WT nCD4s, IKKα-deficient Tregs failed to do so, which was associated with their inability to reconstitute Rag1−/− mice. Furthermore, nCD4s deficient in IKKα also failed to reconstitute Rag1−/− mice and were defective in proliferative responses in vitro and in vivo. Thus, our study reveals a novel role of IKKα in the maintenance of a normal Treg population and in the control of expansion of CD4 T cells. These properties of IKKα may be exploited as therapeutic strategies in the treatment of major human diseases.—Chen, X., Willette-Brown, J., Wu, X., Hu, Y., Howard, O. M. Z., Hu, Y., Oppenheim, J. J. IKKα is required for the homeostasis of regulatory T cells and for the expansion of both regulatory and effector CD4 T cells.