The Wnt/β‐catenin signalling and autophagy pathways each play important roles during development, adult tissue homeostasis and tumorigenesis. Here we identify the Wnt/β‐catenin signalling pathway as a negative regulator of both basal and stress‐induced autophagy. Manipulation of β‐catenin expression levels in vitro and in vivo revealed that β‐catenin suppresses autophagosome formation and directly represses p62/SQSTM1 (encoding the autophagy adaptor p62) via TCF4. Furthermore, we show that during nutrient deprivation β‐catenin is selectively degraded via the formation of a β‐catenin–LC3 complex, attenuating β‐catenin/TCF‐driven transcription and proliferation to favour adaptation during metabolic stress. Formation of the β‐catenin–LC3 complex is mediated by a W/YXXI/L motif and LC3‐interacting region (LIR) in β‐catenin, which is required for interaction with LC3 and non‐proteasomal degradation of β‐catenin. Thus, Wnt/β‐catenin represses autophagy and p62 expression, while β‐catenin is itself targeted for autophagic clearance in autolysosomes upon autophagy induction. These findings reveal a regulatory feedback mechanism that place β‐catenin at a key cellular integration point coordinating proliferation with autophagy, with implications for targeting these pathways for cancer therapy.

Wilms' tumour (WT) is a pediatric tumor of the kidney that arises via failure of the fetal developmental program. The absence of identifiable mutations in the majority of WTs suggests the frequent involvement of epigenetic aberrations in WT. We therefore conducted a genome-wide analysis of promoter hypermethylation in WTs and identified hypermethylation at chromosome 5q31 spanning 800 kilobases (kb) and more than 50 genes. The methylated genes all belong to α-, β-, and γ-protocadherin (PCDH) gene clusters (Human Genome Organization nomenclature PCDHA@, PCDHB@, and PCDHG@, respectively). This demonstrates that long-range epigenetic silencing (LRES) occurs in developmental tumors as well as in adult tumors. Bisulfite polymerase chain reaction analysis showed that PCDH hypermethylation is a frequent event found in all Wilms' tumor subtypes. Hypermethylation is concordant with reduced PCDH expression in tumors. WT precursor lesions showed no PCDH hypermethylation, suggesting that de novo PCDH hypermethylation occurs during malignant progression. Discrete boundaries of the PCDH domain are delimited by abrupt changes in histone modifications; unmethylated genes flanking the LRES are associated with permissive marks which are absent from methylated genes within the domain. Silenced genes are marked with non-permissive histone 3 lysine 9 dimethylation. Expression analysis of embryonic murine kidney and differentiating rat metanephric mesenchymal cells demonstrates that Pcdh expression is developmentally regulated and that Pcdhg@ genes are expressed in blastemal cells. Importantly, we show that PCDHs negatively regulate canonical Wnt signalling, as short-interfering RNA–induced reduction of PCDHG@ encoded proteins leads to elevated β-catenin protein, increased β-catenin/T-cell factor (TCF) reporter activity, and induction of Wnt target genes. Conversely, over-expression of PCDHs suppresses β-catenin/TCF-reporter activity and also inhibits colony formation and growth of cancer cells in soft agar. Thus PCDHs are candidate tumor suppressors that modulate regulatory pathways critical in development and disease, such as canonical Wnt signaling. The development of tissues and organs in the human body requires carefully regulated production of proteins by cells. Proteins permit the growth and development of the many varied structures required for a healthy body. In many diseases, including some cancers, tissues and organs fail to develop as they should due to the normal production of proteins being changed. The work presented here shows that in Wilms' tumor, a childhood cancer of the kidney, a large group of related proteins that are likely necessary for growth and development of a normal kidney are not produced properly. This is due to their production being switched off within the cancer cells. We show how these proteins, known as protocadherins, can themselves alter the function of other proteins already known to be important in normal growth and cancer. Thus our study increases our understanding of how protocadherins are important in normal growth and of how altering protocadherins may lead to disease, such as cancer.

Summary We report the first complete nucleotide sequence of an adult T cell leukaemia virus/human T cell leukaemia virus type I (ATLV/HTLV-I) isolate from a British patient of Caribbean origin. Sequence comparisons of our proviral clone (HS-35) with other molecular clones are shown. We note the strong sequence conservation between isolates of Caribbean and Japanese origin (2.3% divergence), but demonstrate the higher homologies existing between isolates originating from similar geographical areas (approximately 1% divergence). Implications for the origin, evolution and dissemination of the ATLV/HTLV-I subgroup are discussed. Analysis of defective proviral clones isolated from the same genomic library is also reported, and suggests a pattern of proviral sequence deletions during the biogenesis of defective proviruses.

Mammalian kidney development requires the functions of the Wilms tumor gene WT1 and the WNT/β-catenin signaling pathway. Recent studies have shown that WT1 negatively regulates WNT/β-catenin signaling, but the molecular mechanisms by which WT1 inhibits WNT/β-catenin signaling are not completely understood. In this study, we identified a gene, CXXC5, which we have renamed WID (WT1-induced Inhibitor of Dishevelled), as a novel WT1 transcriptional target that negatively regulates WNT/β-catenin signaling. WT1 activates WID transcription through the upstream enhancer region. In the developing kidney, Wid and Wt1 are coexpressed in podocytes of maturing nephrons. Structure-function analysis demonstrated that WID interacts with Dishevelled via its C-terminal CXXC zinc finger and Dishevelled binding domains and potently inhibits WNT/β-catenin signaling in vitro and in vivo. WID is evolutionarily conserved, and ablation of wid in zebrafish embryos with antisense morpholino oligonucleotides perturbs embryonic kidney development. Taken together, our results demonstrate that the WT1 negatively regulates WNT/β-catenin pathway via its target gene WID and further suggest a role for WID in nephrogenesis.

Hypoxia is a hallmark of solid tumours and a key physiological feature distinguishing cancer from normal tissue. However, a major challenge remains in identifying tractable molecular targets that hypoxic cancer cells depend on for survival. Here, we used SILAC‐based proteomics to identify the orphan G protein‐coupled receptor GPRC5A as a novel hypoxia‐induced protein that functions to protect cancer cells from apoptosis during oxygen deprivation. Using genetic approaches in vitro and in vivo, we reveal HIFs as direct activators of GPRC5A transcription. Furthermore, we find that GPRC5A is upregulated in the colonic epithelium of patients with mesenteric ischaemia, and in colorectal cancers high GPRC5A correlates with hypoxia gene signatures and poor clinical outcomes. Mechanistically, we show that GPRC5A enables hypoxic cell survival by activating the Hippo pathway effector YAP and its anti‐apoptotic target gene BCL2L1. Importantly, we show that the apoptosis induced by GPRC5A depletion in hypoxia can be rescued by constitutively active YAP. Our study identifies a novel HIF‐GPRC5A‐YAP axis as a critical mediator of the hypoxia‐induced adaptive response and a potential target for cancer therapy. Synopsis This study identifies a novel hypoxia‐activated signalling axis that facilitates the adaptation of tumour cells to low oxygen conditions. HIFs directly induce the expression of orphan receptor GPRC5A, which signals via Hippo pathway effector YAP to protect hypoxic tumour cells from apoptosis. Orphan G protein‐coupled receptor GPRC5A is induced by hypoxia in vitro and in vivo. HIFs are major and direct physiological regulators of GPRC5A expression. Depletion of GPRC5A promotes apoptosis in hypoxic cancer cells. GPRC5A activates YAP via RhoA to suppress apoptosis via BCL‐XL induction. GPRC5A is a potentially druggable target to exploit tumour‐associated hypoxia for cancer therapy.

Loss of tumour suppressor gene function can occur as a result of epigenetic silencing of large chromosomal regions, referred to as long-range epigenetic silencing (LRES), and genome-wide analyses have revealed that LRES is present in many cancer types. Here we utilize Illumina Beadchip methylation array analysis to identify LRES across 800 kb of chromosome 5q31 in colorectal adenomas and carcinomas (n=34) relative to normal colonic epithelial DNA (n=6). This region encompasses 53 individual protocadherin (PCDH) genes divided among three gene clusters. Hypermethylation within these gene clusters is asynchronous; while most PCDH hypermethylation occurs early, and is apparent in adenomas, PCDHGC3 promoter methylation occurs later in the adenoma–carcinoma transition. PCDHGC3 was hypermethylated in 17/28 carcinomas (60.7%) according to methylation array analysis. Quantitative real-time reverse transcription–polymerase chain reaction showed that PCDHGC3 is the highest expressed PCDH in normal colonic epithelium, and that there was a strong reciprocal relationship between PCDHGC3 methylation and expression in carcinomas (R=−0.84). PCDH LRES patterns are reflected in colorectal tumour cell lines; adenoma cell lines are not methylated at PCDHGC3 and show abundant expression at the mRNA and protein level, while the expression is suppressed in hypermethylated carcinoma cell lines (R=−0.73). Short-interfering RNA-mediated reduction of PCDHGC3 led to a decrease of apoptosis in RG/C2 adenoma cells, and overexpression of PCDHGC3 in HCT116 cells resulted in the reduction of colony formation, consistent with tumour suppressor capabilities for PCDHGC3. Further functional analysis showed that PCDHGC3 can suppress Wnt and mammalian target of rapamycin signalling in colorectal cancer cell lines. Taken together, our data suggest that the PCDH LRES is an important tumour suppressor locus in colorectal cancer, and that PCDHGC3 may be a strong marker and driver for the adenoma–carcinoma transition.