Mutant p53 regulates Survivin to foster lung metastasis.

Esophageal squamous cell carcinoma (ESCC) is one of the most lethal cancers worldwide and evolves often to lung metastasis. P53R175H (homologous to Trp53R172H in mice) is a common hot spot mutation. How metastasis is regulated by p53R175H in ESCC remains to be investigated. To investigate p53R175H-mediated molecular mechanisms, we used a carcinogen-induced approach in Trp53R172H/- mice to model ESCC. In the primary Trp53R172H/- tumor cell lines, we depleted Trp53R172H (shTrp53) and observed a marked reduction in cell invasion in vitro and lung metastasis burden in a tail-vein injection model in comparing isogenic cells (shCtrl). Furthermore, we performed bulk RNA-seq to compare gene expression profiles of metastatic and primary shCtrl and shTrp53 cells. We identified the YAP-BIRC5 axis as a potential mediator of Trp53R172H -mediated metastasis. We demonstrate that expression of Survivin, an antiapoptotic protein encoded by BIRC5, increases in the presence of Trp53R172H Furthermore, depletion of Survivin specifically decreases Trp53R172H-driven lung metastasis. Mechanistically, Trp53R172H but not wild-type Trp53, binds with YAP in ESCC cells, suggesting their cooperation to induce Survivin expression. Furthermore, Survivin high expression level is associated with increased metastasis in several GI cancers. Taken together, this study unravels new insights into how mutant p53 mediates metastasis.

Biomechanical remodeling of the microenvironment by stromal caveolin-1 favors tumor invasion and metastasis.

Mechanotransduction is a key determinant of tissue homeostasis and tumor progression. It is driven by intercellular adhesions, cell contractility, and forces generated within the microenvironment and is dependent on extracellular matrix composition, organization, and compliance. We show that caveolin-1 (Cav1) favors cell elongation in three-dimensional cultures and promotes Rho- and force-dependent contraction, matrix alignment, and microenvironment stiffening through regulation of p190RhoGAP. In turn, microenvironment remodeling by Cav1 fibroblasts forces cell elongation. Cav1-deficient mice have disorganized stromal tissue architecture. Stroma associated with human carcinomas and melanoma metastases is enriched in Cav1-expressing carcinoma-associated fibroblasts (CAFs). Cav1 expression in breast CAFs correlates with low survival, and Cav1 depletion in CAFs decreases CAF contractility. Consistently, fibroblast expression of Cav1, through p190RhoGAP regulation, favors directional migration and invasiveness of carcinoma cells in vitro. In vivo, stromal Cav1 remodels peri- and intratumoral microenvironments to facilitate tumor invasion, correlating with increased metastatic potency. Thus, Cav1 modulates tissue responses through force-dependent architectural regulation of the microenvironment.

Thymine DNA glycosylase is essential for active DNA demethylation by linked deamination-base excision repair.

DNA methylation is a major epigenetic mechanism for gene silencing. Whereas methyltransferases mediate cytosine methylation, it is less clear how unmethylated regions in mammalian genomes are protected from de novo methylation and whether an active demethylating activity is involved. Here, we show that either knockout or catalytic inactivation of the DNA repair enzyme thymine DNA glycosylase (TDG) leads to embryonic lethality in mice. TDG is necessary for recruiting p300 to retinoic acid (RA)-regulated promoters, protection of CpG islands from hypermethylation, and active demethylation of tissue-specific developmentally and hormonally regulated promoters and enhancers. TDG interacts with the deaminase AID and the damage response protein GADD45a. These findings highlight a dual role for TDG in promoting proper epigenetic states during development and suggest a two-step mechanism for DNA demethylation in mammals, whereby 5-methylcytosine and 5-hydroxymethylcytosine are first deaminated by AID to thymine and 5-hydroxymethyluracil, respectively, followed by TDG-mediated thymine and 5-hydroxymethyluracil excision repair.

The LIN28B-IMP1 post-transcriptional regulon has opposing effects on oncogenic signaling in the intestine.

RNA-binding proteins (RBPs) are expressed broadly during both development and malignant transformation, yet their mechanistic roles in epithelial homeostasis or as drivers of tumor initiation and progression are incompletely understood. Here we describe a novel interplay between RBPs LIN28B and IMP1 in intestinal epithelial cells. Ribosome profiling and RNA sequencing identified IMP1 as a principle node for gene expression regulation downstream from LIN28B In vitro and in vivo data demonstrate that epithelial IMP1 loss increases expression of WNT target genes and enhances LIN28B-mediated intestinal tumorigenesis, which was reversed when we overexpressed IMP1 independently in vivo. Furthermore, IMP1 loss in wild-type or LIN28B-overexpressing mice enhances the regenerative response to irradiation. Together, our data provide new evidence for the opposing effects of the LIN28B-IMP1 axis on post-transcriptional regulation of canonical WNT signaling, with implications in intestinal homeostasis, regeneration and tumorigenesis.

Epithelial overexpression of IL-33 induces eosinophilic esophagitis dependent on IL-13.

BACKGROUND: Eosinophilic esophagitis (EoE) is an increasingly common inflammatory condition of the esophagus; however, the underlying immunologic mechanisms remain poorly understood. The epithelium-derived cytokine IL-33 is associated with type 2 immune responses and elevated in esophageal biopsy specimens from patients with EoE. OBJECTIVE: We hypothesized that overexpression of IL-33 by the esophageal epithelium would promote the immunopathology of EoE. METHODS: We evaluated the functional consequences of esophageal epithelial overexpression of a secreted and active form of IL-33 in a novel transgenic mouse, EoE33. EoE33 mice were analyzed for clinical and immunologic phenotypes. Esophageal contractility was assessed. Epithelial cytokine responses were analyzed in three-dimensional organoids. EoE33 phenotypes were further characterized in ST2-/-, eosinophil-deficient, and IL-13-/- mice. Finally, EoE33 mice were treated with dexamethasone. RESULTS: EoE33 mice displayed ST2-dependent, EoE-like pathology and failed to thrive. Esophageal tissue remodeling and inflammation included basal zone hyperplasia, eosinophilia, mast cells, and TH2 cells. Marked increases in levels of type 2 cytokines, including IL-13, and molecules associated with immune responses and tissue remodeling were observed. Esophageal organoids suggested reactive epithelial changes. Genetic deletion of IL-13 in EoE33 mice abrogated pathologic changes in vivo. EoE33 mice were responsive to steroids. CONCLUSIONS: IL-33 overexpression by the esophageal epithelium generated immunopathology and clinical phenotypes resembling human EoE. IL-33 may play a pivotal role in the etiology of EoE by activating the IL-13 pathway. EoE33 mice are a robust experimental platform for mechanistic investigation and translational discovery.

ALDH2 dysfunction and alcohol cooperate in cancer stem cell enrichment.

The alcohol metabolite acetaldehyde is a potent human carcinogen linked to esophageal squamous cell carcinoma (ESCC) initiation and development. Aldehyde dehydrogenase 2 (ALDH2) is the primary enzyme that detoxifies acetaldehyde in the mitochondria. Acetaldehyde accumulation causes genotoxic stress in cells expressing the dysfunctional ALDH2E487K dominant negative mutant protein linked to ALDH2*2, the single nucleotide polymorphism highly prevalent among East Asians. Heterozygous ALDH2*2 increases the risk for the development of ESCC and other alcohol-related cancers. Despite its prevalence and link to malignant transformation, how ALDH2 dysfunction influences ESCC pathobiology is incompletely understood. Herein, we characterize how ESCC and preneoplastic cells respond to alcohol exposure using cell lines, three-dimensional organoids and xenograft models. We find that alcohol exposure and ALDH2*2 cooperate to increase putative ESCC cancer stem cells with high CD44 expression (CD44H cells) linked to tumor initiation, repopulation and therapy resistance. Concurrently, ALHD2*2 augmented alcohol-induced reactive oxygen species and DNA damage to promote apoptosis in the non-CD44H cell population. Pharmacological activation of ALDH2 by Alda-1 inhibits this phenotype, suggesting that acetaldehyde is the primary driver of these changes. Additionally, we find that Aldh2 dysfunction affects the response to cisplatin, a chemotherapeutic commonly used for the treatment of ESCC. Aldh2 dysfunction facilitated enrichment of CD44H cells following cisplatin-induced oxidative stress and cell death in murine organoids, highlighting a potential mechanism driving cisplatin resistance. Together, these data provide evidence that ALDH2 dysfunction accelerates ESCC pathogenesis through enrichment of CD44H cells in response to genotoxic stressors such as environmental carcinogens and chemotherapeutic agents.

Diclofenac exhibits cytotoxic activity associated with metabolic alterations and p53 induction in ESCC cell lines and decreases ESCC tumor burden in vivo.

Esophageal squamous cell carcinoma (ESCC) is one of the most aggressive forms of human malignancy, often displaying limited therapeutic response. Here, we examine the non-steroidal anti-inflammatory drug diclofenac (DCF) as a novel therapeutic agent in ESCC using complementary in vitro and in vivo models. DCF selectively reduced viability of human ESCC cell lines TE11, KYSE150, and KYSE410 as compared with normal primary or immortalized esophageal keratinocytes. Apoptosis and altered cell cycle profiles were documented in DCF-treated TE11 and KYSE 150. In DCF-treated TE11, RNA-Sequencing identified differentially expressed genes and Ingenuity Pathway Analysis predicted alterations in pathways associated with cellular metabolism and p53 signaling. Downregulation of proteins associated with glycolysis was documented in DCF-treated TE11 and KYSE150. In response to DCF, TE11 cells further displayed reduced levels of ATP, pyruvate, and lactate. Evidence of mitochondrial depolarization and superoxide production was induced by DCF in TE11 and KYSE150. In DCF-treated TE11, the superoxide scavenger MitoTempo improved viability, supporting a role for mitochondrial reactive oxygen species in DCF-mediated toxicity. DCF treatment resulted in increased expression of p53 in TE11 and KYSE150. p53 was further identified as a mediator of DCF-mediated toxicity in TE11 as genetic depletion of p53 partially limited apoptosis in response to DCF. Consistent with the anticancer activity of DCF in vitro, the drug significantly decreased tumor burdene in syngeneic ESCC xenograft tumors and 4-nitroquinoline 1-oxide-mediated ESCC lesions in vivo. These preclinical findings identify DCF as an experimental therapeutic that should be explored further in ESCC.

Rab11-FIP1 mediates epithelial-mesenchymal transition and invasion in esophageal cancer.

Esophageal squamous cell carcinoma (ESCC) is the most common subtype of esophageal cancer worldwide. The most commonly mutated gene in ESCC is TP53. Using a combinatorial genetic and carcinogenic approach, we generate a novel mouse model of ESCC expressing either mutant or null p53 and show that mutant p53 exhibits enhanced tumorigenic properties and displays a distinct genomic profile. Through RNA-seq analysis, we identify several endocytic recycling genes, including Rab Coupling Protein (Rab11-FIP1), which are significantly downregulated in mutant p53 tumor cells. In 3-dimensional (3D) organoid models, genetic knockdown of Rab11-FIP1 results in increased organoid size. Loss of Rab11-FIP1 increases tumor cell invasion in part through mutant p53 but also in an independent manner. Furthermore, loss of Rab11-FIP1 in human ESCC cell lines decreases E-cadherin expression and increases mesenchymal lineage-specific markers, suggesting induction of epithelial-mesenchymal transition (EMT). Rab11-FIP1 regulates EMT through direct inhibition of Zeb1, a key EMT transcriptional factor. Our novel findings reveal that Rab11-FIP1 regulates organoid formation, tumor cell invasion, and EMT.

Persistent Basal Cell Hyperplasia Is Associated With Clinical and Endoscopic Findings in Patients With Histologically Inactive Eosinophilic Esophagitis.

BACKGROUND & AIMS: Although eosinophil count is the standard used to monitor disease activity in patients with eosinophilic esophagitis (EoE), there are often disparities between patient-reported symptoms and eosinophil counts. We examined the prevalence of epithelial alterations, namely basal cell hyperplasia (BCH) and spongiosis, among patients with inactive EoE (eosinophil counts below 15 following therapy) and aimed to determine whether maintenance of these changes in epithelial morphology are associated with persistent clinical findings. METHODS: Esophageal biopsies of 243 patients (mean age, 16.9 years) undergoing routine endoscopy at the University of Pennsylvania were evaluated for epithelial BCH and spongiosis. Univariable analysis was used to calculate the association between epithelial changes and symptoms as well as endoscopic findings and peak eosinophil count. We validated our findings using data from a cohort of patients at the University of North Carolina. RESULTS: The discovery and validation cohorts each included patients with inactive EoE, based on histologic factors, but ongoing BCH and spongiosis. Ongoing BCH, but not spongiosis, in patients with inactive EoE was associated with symptoms (odds ratio, 2.14; 95% CI, 1.03-4.42; P = .041) and endoscopic findings (odds ratio, 7.10; 95% CI, 3.12-16.18; P < .001). CONCLUSIONS: In patients with EoE, the presence of BCH might indicate ongoing disease activity, independent of eosinophil count. This might account for the persistent symptoms in patients who are considered to be in remission based on histologic factors.

Paired Basic Amino Acid-cleaving Enzyme 4 (PCSK6): An Emerging New Target Molecule in Human Melanoma.

Although recent therapeutic developments raise hope, melanoma remains a devastating disease with a need for new treatment targets. In other tumours prohormone convertases have been shown to be pro-tumourigenic as they are involved in processing preforms of matrix-metalloproteinases, growth factors and adhesion molecules. The aim of this study was to look for new treatment options for melanoma, by investigating the role of the prohormone convertase Paired basic Amino acid-Cleaving Enzyme 4 (PACE4/PCSK6) in melanoma cell lines and human melanoma tissue. PACE4-transfected A375 melanoma cells displayed significantly increased proliferation, MMP-2 production, gelatinase activity and migratory capacity in vitro compared with sham-transfected cells. In vivo, elevated PACE4 expression resulted in significantly increased tumour growth on immunodeficient mice. In the majority of 45 human primary melanomas and melanoma metastases ex vivo PACE4 immunoreactivity was detectable, while it was absent in in situ melanomas. These results indicate PACE4 as a regulator of melanoma cell aggressiveness.

Fibrostenotic eosinophilic esophagitis might reflect epithelial lysyl oxidase induction by fibroblast-derived TNF-α.

BACKGROUND: Fibrosis and stricture are major comorbidities in patients with eosinophilic esophagitis (EoE). Lysyl oxidase (LOX), a collagen cross-linking enzyme, has not been investigated in the context of EoE. OBJECTIVE: We investigated regulation of epithelial LOX expression as a novel biomarker and functional effector of fibrostenotic disease conditions associated with EoE. METHODS: LOX expression was analyzed by using RNA-sequencing, PCR assays, and immunostaining in patients with EoE; cytokine-stimulated esophageal 3-dimensional organoids; and fibroblast-epithelial cell coculture, the latter coupled with fluorescence-activated cell sorting. RESULTS: Gene ontology and pathway analyses linked TNF-α and LOX expression in patients with EoE, which was validated in independent sets of patients with fibrostenotic conditions. TNF-α-mediated epithelial LOX upregulation was recapitulated in 3-dimensional organoids and coculture experiments. We find that fibroblast-derived TNF-α stimulates epithelial LOX expression through activation of nuclear factor κB and TGF-ß-mediated signaling. In patients receiver operating characteristic analyses suggested that LOX upregulation indicates disease complications and fibrostenotic conditions in patients with EoE. CONCLUSIONS: There is a novel positive feedback mechanism in epithelial LOX induction through fibroblast-derived TNF-α secretion. Esophageal epithelial LOX might have a role in the development of fibrosis with substantial translational implications.

IMP1 3' UTR shortening enhances metastatic burden in colorectal cancer.

The RNA-binding protein insulin-like growth factor 2 mRNA binding protein 1 (IMP1) is overexpressed in colorectal cancer (CRC); however, evidence for a direct role for IMP1 in CRC metastasis is lacking. IMP1 is regulated by let-7 microRNA, which binds in the 3' untranslated region (UTR) of the transcript. The availability of binding sites is in part controlled by alternative polyadenylation, which determines 3' UTR length. Expression of the short 3' UTR transcript (lacking all microRNA sites) results in higher protein levels and is correlated with increased proliferation. We used in vitro and in vivo model systems to test the hypothesis that the short 3' UTR isoform of IMP1 promotes CRC metastasis. Herein we demonstrate that 3' UTR shortening increases IMP1 protein expression and that this in turn enhances the metastatic burden to the liver, whereas expression of the long isoform (full length 3' UTR) does not. Increased tumor burden results from elevated tumor surface area driven by cell proliferation and cell survival mechanisms. These processes are independent of classical apoptosis pathways. Moreover, we demonstrate the shifts toward the short isoform are associated with metastasis in patient populations where IMP1-long expression predominates. Overall, our work demonstrates that different IMP1 expression levels result in different functional outcomes in CRC metastasis and that targeting IMP1 may reduce tumor progression in some patients.

Inactivation of Tp53 and Pten drives rapid development of pleural and peritoneal malignant mesotheliomas.

Malignant mesothelioma (MM) is a therapy-resistant cancer arising primarily from the lining of the pleural and peritoneal cavities. The most frequently altered genes in human MM are cyclin-dependent kinase inhibitor 2A (CDKN2A), which encodes components of the p53 (p14ARF) and RB (p16INK4A) pathways, BRCA1-associated protein 1 (BAP1), and neurofibromatosis 2 (NF2). Furthermore, the p53 gene (TP53) itself is mutated in ~15% of MMs. In many MMs, the PI3K-PTEN-AKT-mTOR signaling node is hyperactivated, which contributes to tumor cell survival and therapeutic resistance. Here, we demonstrate that the inactivation of both Tp53 and Pten in the mouse mesothelium is sufficient to rapidly drive aggressive MMs. PtenL/L ;Tp53L/L mice injected intraperitoneally or intrapleurally with adenovirus-expressing Cre recombinase developed high rates of peritoneal and pleural MMs (92% of mice with a median latency of 9.4 weeks and 56% of mice with a median latency of 19.3 weeks, respectively). MM cells from these mice showed consistent activation of Akt-mTor signaling, chromosome breakage or aneuploidy, and upregulation of Myc; occasional downregulation of Bap1 was also observed. Collectively, these findings suggest that when Pten and Tp53 are lost in combination in mesothelial cells, DNA damage is not adequately repaired and genomic instability is widespread, whereas the activation of Akt due to Pten loss protects genomically damaged cells from apoptosis, thereby increasing the likelihood of tumor formation. Additionally, the mining of an online dataset (The Cancer Genome Atlas) revealed codeletions of PTEN and TP53 and/or CDKN2A/p14ARF in ~25% of human MMs, indicating that cooperative losses of these genes contribute to the development of a significant proportion of these aggressive neoplasms and suggesting key target pathways for therapeutic intervention.

Correction to: Buthionine sulfoximine sensitizes antihormone-resistant human breast cancer cells to estrogen-induced apoptosis.

After the publication of this work [1] an error was noticed in Fig. 3a and Fig. 5a.

Autophagy mediates epithelial cytoprotection in eosinophilic oesophagitis.

OBJECTIVE: The influence of eosinophilic oesophagitis (EoE)-associated inflammation upon oesophageal epithelial biology remains poorly understood. We investigated the functional role of autophagy in oesophageal epithelial cells (keratinocytes) exposed to the inflammatory EoE milieu. DESIGN: Functional consequences of genetic or pharmacological autophagy inhibition were assessed in endoscopic oesophageal biopsies, human oesophageal keratinocytes, single cell-derived ex vivo murine oesophageal organoids as well as a murine model recapitulating EoE-like inflammation and basal cell hyperplasia. Gene expression, morphological and functional characterisation of autophagy and oxidative stress were performed by transmission electron microscopy, immunostaining, immunoblotting, live cell imaging and flow cytometry. RESULTS: EoE-relevant inflammatory conditions promoted autophagy and basal cell hyperplasia in three independent murine EoE models and oesophageal organoids. Inhibition of autophagic flux via chloroquine treatment augmented basal cell hyperplasia in these model systems. Oesophageal keratinocytes stimulated with EoE-relevant cytokines, including tumour necrosis factor-α and interleukin-13 exhibited activation of autophagic flux in a reactive oxygen species-dependent manner. Autophagy inhibition via chloroquine treatment or depletion of Beclin-1 or ATG-7, augmented oxidative stress induced by EoE-relevant stimuli in murine EoE, oesophageal organoids and human oesophageal keratinocytes. Oesophageal epithelia of paediatric EoE patients with active inflammation displayed increased autophagic vesicle content compared with normal and EoE remission subjects. Functional flow cytometric analysis revealed autophagic flux in human oesophageal biopsies. CONCLUSIONS: Our findings reveal for the first time that autophagy may function as a cytoprotective mechanism to maintain epithelial redox balance and homeostasis under EoE inflammation-associated stress, providing mechanistic insights into the role of autophagy in EoE pathogenesis.

Esophageal Expression of Active IκB Kinase-ß in Mice Up-Regulates Tumor Necrosis Factor and Granulocyte-Macrophage Colony-Stimulating Factor, Promoting Inflammation and Angiogenesis.

BACKGROUND & AIMS: IκB kinase-ß (IKKß) mediates activation of the nuclear factor-κB, which regulates immune and inflammatory responses. Although nuclear factor-κB is activated in cells from patients with inflammatory diseases or cancer, little is known about its roles in the development and progression of esophageal diseases. We investigated whether mice that express an activated form of IKKß in the esophageal epithelia develop esophageal disorders. METHODS: We generated ED-L2-Cre/Rosa26-IKK2caSFL mice, in which the ED-L2 promoter activates expression of Cre in the esophageal epithelia, leading to expression of a constitutively active form of IKKß (IKKßca) in epithelial cells but not in inflammatory cells or the surrounding stroma (IKKßca mice). Mice lacking the Cre transgene served as controls. Some mice were given intraperitoneal injections of neutralizing antibodies against granulocyte-macrophage colony-stimulating factor (GM-CSF) or tumor necrosis factor (TNF), or immunoglobulin G1 (control), starting at 1 month of age. Epithelial tissues were collected and analyzed by immunofluorescence, immunohistochemical, and quantitative real-time polymerase chain reaction assays. Transgenes were overexpressed from retroviral vectors in primary human keratinocytes. RESULTS: IKKßca mice developed esophagitis and had increased numbers of blood vessels in the esophageal stroma, compared with controls. Esophageal tissues from IKKßca mice had increased levels of GM-CSF. Expression of IKKßca in primary human esophageal keratinocytes led to 11-fold overexpression of GM-CSF and 200-fold overexpression of TNF. Incubation of human umbilical vein endothelial cells with conditioned media from these keratinocytes increased endothelial cell migration by 42% and promoted formation of capillary tubes; these effects were blocked by a neutralizing antibody against GM-CSF. Injections of anti-GM-CSF reduced angiogenesis and numbers of CD31+ blood vessels in esophageal tissues of IKKßca mice, but did not alter the esophageal vasculature of control mice and did not alter recruitment of intraepithelial leukocytes to esophageal tissues of IKKßca mice. Injections of anti-TNF prevented the development of esophagitis in IKKßca mice. CONCLUSIONS: Constitutive activation of IKKß in the esophageal epithelia of mice leads to inflammation and angiogenesis, mediated by TNF and GM-CSF, respectively.

Targeting proprotein convertases in furin-rich lung cancer cells results in decreased in vitro and in vivo growth.

Proprotein convertases (PCs) are serine proteases with an active role in the post-translational processing of numerous inactive proteins to active proteins including many substrates of paramount importance in cancer development and progression. Furin (PCSKC3), a well-studied member of this family, is overexpressed in numerous human and experimental malignancies. In the present communication, we treated two furin-overexpressing non-small cell carcinoma (NSCLC) cell lines (Calu-6 and HOP-62) with the PC inhibitor CMK (Decanoyl-Arg-Val-Lys-Arg-chloromethylketone). This resulted in a diminished IGF-1R processing and a simultaneous decrease in cell proliferation of two NSCLC lines. Similarly, growth of subcutaneous xenografts of both cell lines, were partially inhibited by an in vivo treatment with the same drug. These observations point to a potential role of PC inhibitors in cancer therapy. © 2016 Wiley Periodicals, Inc.

WNT10A promotes an invasive and self-renewing phenotype in esophageal squamous cell carcinoma.

Esophageal cells overexpressing epidermal growth factor receptor (EGFR) and TP53 mutation can invade into the extracellular matrix when grown in 3D-organotypic cultures (OTC) and mimic early invasion in esophageal squamous cell carcinoma (ESCC). We have performed laser capture microdissection with RNA microarray analysis on the invasive and non-invasive tumor cells of p53(R175H)-overexpressing OTC samples to determine candidate genes facilitating tumor invasion. WNT10A was found to be >4-fold upregulated in the invasive front. Since WNT10A is also prominently upregulated during placode promotion in hair follicle development, a process that requires epithelial cells to thicken and elongate, in order to allow downward growth, we hypothesized that WNT10A may be important in mediating a similar mechanism of tumor cell invasion in ESCC. We have found that WNT10A expression is significantly upregulated in human ESCC, when compared with normal adjacent tissue. Furthermore, high WNT10A expression levels correlate with poor survival. Interestingly, we observe that WNT10A is expressed early in embryogenesis, but is reduced dramatically postnatally. We demonstrate that overexpression of WNT10a promotes migration and invasion, and proliferation of transformed esophageal cells. Lastly, we show that WNT10A overexpression induces a greater CD44(High)/CD24(Low) population, which are putative markers of cancer stem cells, and increases self-renewal capability. Taken together, we propose that WNT10A acts as an oncofetal factor that is highly expressed and may promote proper development of the esophagus. During tumorigenesis, it is aberrantly overexpressed in order to promote ESCC migration and invasion, and may be linked to self-renewal of a subset of ESCC cells.

Enhanced aggressiveness of benzopyrene-induced squamous carcinomas in transgenic mice overexpressing the proprotein convertase PACE4 (PCSK6).

PACE4 (PCSK6) is a proprotein convertase (PC) capable of processing numerous substrates involved in tumor growth, invasion, and metastasis. Because of the human relevancy of the tobacco-associated carcinogen benzo[a]pyrene (B(a)P) we investigated whether transgenic mice in which this PC is targeted to the epidermis (K5-PACE4) may be more susceptible to B(a)P complete carcinogenesis than wild type (WT) mice. In an in vitro experiment, using cell lines derived from skin tumors obtained after B(a)P treatment, we observed that PACE4 overexpression and activity accounts for an increased proliferation rate, exaggerated sensitivity to the PC inhibitor CMK, and interference with IGF-1R autophosphorylation. Squamous cell carcinomas, obtained from K5-PACE4 mice subjected to complete chemical carcinogenesis, were characterized by a 50% increase in cell proliferation, when compared with similar tumors from WT mice. In addition, tumors from K5-PACE4 mice showed deeper invasion into the underlying dermis. Thus, mice overexpressing PACE4 exhibited tumors of increased growth rate and invasive potential when exposed to the human carcinogen B(a)P, further supporting the significance of PCs in tumor growth and progression.

Regulation of HIF-1 alpha by the proprotein convertases furin and PC7 in human squamous carcinoma cells.

Proprotein convertases (PC), a family of serine proteases, process cancer-related substrates such as growth factors, growth factor receptors, cell adhesion molecules, metalloproteinases, etc. HIF-1α is a major transcription factor involved in tumorigenesis by sensing intratumoral hypoxia. Furin (PCSK3) is one of the numerous target genes regulated by HIF-1α transactivation and its distribution into endosomal compartments and onto the cell surface can be triggered by hypoxia via HIF-1α. siRNAs to knockdown PCs were transfected into cells alone or in combination with different drug treatments. Protein and RNA expression levels were analyzed by Western blotting or RT-PCR, respectively. PC7 (PCSK7) and furin siRNAs upregulated HIF-1α protein under normoxic condition to a level similar to that obtained by cobalt chloride treatment, eventually leading to activation of VEGF-A synthesis in two human head and neck squamous cell carcinoma cell lines. The unchanged levels of HIF-1α mRNA expression under siRNA treatment and the additive HIF-1α induction of PC siRNAs and either cobalt chloride or the 26S ribosome inhibitor, MG-132, suggested a post-transcriptional PC-mediated regulation. Furthermore, cycloheximide chase showed that PC7/furin siRNA regulation occurred at the level of HIF-1α translation. A specific IGF-1R signaling inhibitor was able to attenuate the PC siRNA induction of HIF-1α, suggesting the involvement of the IGF-1R pathway. Thus, the data show that PCs regulate HIF-1α. Furin and PC7 siRNAs induced HIF-1α protein by increasing its translation, resulting in upregulation of VEGF-A. This finding may provide insight into intricate PC functions that seem to be independent from their substrate-processing activity.