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Functional inactivation of tumor suppressor genes drives cancer initiation, progression, and treatment responses. Most tumor suppressor genes are inactivated through 1 of 2 well-characterized mechanisms: DNA-level mutations, such as point mutations or deletions, and promoter DNA hypermethylation. Here, we report a distinct third mechanism of tumor suppressor inactivation based on alterations to the histone rather than DNA code. We demonstrated that PAX2 is an endometrial tumor suppressor recurrently inactivated by a distinct epigenetic reprogramming event in more than 80% of human endometrial cancers. Integrative transcriptomic, epigenomic, 3D genomic, and machine learning analyses showed that PAX2 transcriptional downregulation is associated with replacement of open/active chromatin features (H3K27ac/H3K4me3) with inaccessible/repressive chromatin features (H3K27me3) in a framework dictated by 3D genome organization. The spread of the repressive H3K27me3 signal resembled a pearl necklace, with its length modulated by cohesin loops, thereby preventing transcriptional dysregulation of neighboring genes. This mechanism, involving the loss of a promoter-proximal superenhancer, was shown to underlie transcriptional silencing of PAX2 in human endometrial cancers. Mouse and human preclinical models established PAX2 as a potent endometrial tumor suppressor. Functionally, PAX2 loss promoted endometrial carcinogenesis by rewiring the transcriptional landscape via global enhancer reprogramming. The discovery that most endometrial cancers originate from a recurring epigenetic alteration carries profound implications for their diagnosis and treatment.

MiT/TFE gene fusions like SFPQ-TFE3 drive both epithelial (translocation RCC) and mesenchymal (PEComas) neoplasms. However, no mouse models for SFPQ-TFE3 -related tumors exist and the underlying mechanisms of lineage plasticity remain unclear. Here, we demonstrate that constitutive murine renal expression of SFPQ-TFE3 disrupts kidney development with early neonatal renal failure and death, while post-natal induction induces infiltrative epithelioid tumors, that morphologically and transcriptionally resemble human PEComas, with strong activation of mTORC1 signaling via increased V-ATPase expression. Remarkably, SFPQ-TFE3 expression is sufficient to induce lineage plasticity, with down-regulation of the PAX2/PAX8 nephric lineage factors and tubular epithelial markers, and up-regulation of PEComa differentiation markers in transgenic mice, cell lines and human tRCC. mTOR inhibition downregulates SFPQ-TFE3 expression and rescues PAX8 expression and transcriptional activity in vitro. These data provide evidence of an epithelial cell-of-origin for TFE3 -driven PEComas, highlighting a reciprocal role for SFPQ-TFE3 and mTOR in driving lineage plasticity in the kidney. TFE3-fusions are known to drive both epithelial and mesenchymal renal tumors. Here, the authors generate a transgenic mouse model of renal tumorigenesis expressing the human SFPQ-TFE3 fusion, showing that the fusion regulates mTORC1 activity and induces lineage plasticity.

Naturally occurring cell death is a fundamental developmental mechanism for regulating cell numbers and sculpting developing organs. This is particularly true in the nervous system, where large numbers of neurons and oligodendrocytes are eliminated via apoptosis during normal development. Given the profound impact of death upon these two major cell populations, it is surprising that developmental death of another major cell type-the astrocyte-has rarely been studied. It is presently unclear whether astrocytes are subject to significant developmental death, and if so, how it occurs. Here, we address these questions using mouse retinal astrocytes as our model system. We show that the total number of retinal astrocytes declines by over 3-fold during a death period spanning postnatal days 5-14. Surprisingly, these astrocytes do not die by apoptosis, the canonical mechanism underlying the vast majority of developmental cell death. Instead, we find that microglia engulf astrocytes during the death period to promote their developmental removal. Genetic ablation of microglia inhibits astrocyte death, leading to a larger astrocyte population size at the end of the death period. However, astrocyte death is not completely blocked in the absence of microglia, apparently due to the ability of astrocytes to engulf each other. Nevertheless, mice lacking microglia showed significant anatomical changes to the retinal astrocyte network, with functional consequences for the astrocyte-associated vasculature leading to retinal hemorrhage. These results establish a novel modality for naturally occurring cell death and demonstrate its importance for the formation and integrity of the retinal gliovascular network.

Endometrial cancer (EC) is a malignancy of the endometrial epithelium. The prevalence and mortality rates associated with the disease are on the rise globally. A total of 20 cases of type I EC tissues were collected for transcriptomic sequencing, our findings indicate that PAX2 is highly expressed in EC tissues and is closely related to the pathogenesis of EC. PAX2 is a member of the paired homeobox domain family and has been linked to the development of a number of different tumours. In normal endometrial tissue, PAX2 is methylated; however, in EC, it is demethylated. Nevertheless, few studies have focused on its role in EC. A protein–protein interaction (PPI) analysis revealed a regulatory relationship between PAX2 and CD133, which in turn affects the activity of AKT1. CD133 is a well-known marker of tumor stem cells and is involved in tumor initiation, metastasis, recurrence, and drug resistance; AKT1 promotes cell survival by inhibiting apoptosis and is considered a major promoter of many types of cancer. Nevertheless, further investigation is required to ascertain whether PAX2 affects the progression of EC by regulating the CD133-AKT1 pathway. The present study demonstrated that PAX2 promoted cell proliferation, migration, invasion and adhesion, and inhibited apoptosis. Its mechanism of action was found to be the inhibition of mitochondrial oxidative phosphorylation, promotion of glycolysis, increase in mitochondrial copy number, and increase in the levels of reactive oxygen species (ROS) and hexokinase, as well as the concentration of mitochondrial calcium ions. This was achieved through the promotion of CD133 expression and the phosphorylation of AKT1. In conjunction with the aforementioned regulatory pathways, the progression of EC is facilitated.

Extra spindle-polar body like 1 (ESPL1) is associated with the development of a variety of cancers, including bladder cancer, and is closely related to chemoresistance. In this study, we aimed to reveal the role of ESPL1 in bladder cancer progression and cisplatin (DDP) resistance. First, ESPL1 was found to be highly expressed in tumor tissues and cells of bladder cancer, and more highly expressed in cisplatin resistant tumor tissues or cells. The binding of PAX2 in ESPL1 promoter region was predicted by Jaspar database and verified by Ch-IP analysis and the luciferase reporter gene assay. Next, cisplatin-resistant T24 cells (T24/DDP) were established and transfected with ESPL1 siRNA (si-ESPL1) or overexpression vector (pcDNA-ESPL1) or co-transfected with PAX2 siRNA (si-PAX2) or overexpression vector (pcDNA-PAX2), and then treated with DDP or AG490, an inhibitor of JAK2. The results showed that silencing ESPL1 significantly reduced T24/DDP cell viability, colony formation and invasion, enhanced sensitivity to DDP, and induced cell apoptosis. Silencing PAX2 decreased ESPL1 expression, enhanced sensitivity to DDP, and induced apoptosis of T24/DDP cells, and inhibited activation of JAK2/STAT3 pathway. Overexpressing ESPL1 reversed the effect of PAX2 silencing on T24/DDP cells, while AG490 counteracted the reversal effect of overexpressing ESPL1. Finally, a xenograft tumor model was established and found that silencing ESPL1 or DDP treatment inhibited tumor growth, while silencing ESPL1 combined with DDP treatment had the best effect. In summary, this study suggested that PAX2-mediated ESPL1 transcriptional activation enhanced cisplatin resistance in bladder cancer by activating JAK2/STAT3 pathway.

Deafness or hearing loss is a major issue in human health. Inner ear hair cells are the main sensory receptors responsible for hearing. Defects in hair cells are one of the major causes of deafness. A combination of induced pluripotent stem cell (iPSC) technology with genome-editing technology may provide an attractive cell-based strategy to regenerate hair cells and treat hereditary deafness in humans. Here, we report the generation of iPSCs from members of a Chinese family carrying MYO15A c.4642G>A and c.8374G>A mutations and the induction of hair cell-like cells from those iPSCs. The compound heterozygous MYO15A mutations resulted in abnormal morphology and dysfunction of the derived hair cell-like cells. We used a CRISPR/Cas9 approach to genetically correct the MYO15A mutation in the iPSCs and rescued the morphology and function of the derived hair cell-like cells. Our data demonstrate the feasibility of generating inner ear hair cells from human iPSCs and the functional rescue of gene mutation-based deafness by using genetic correction.

To investigate the utility of whole-exome sequencing (WES) to define a molecular diagnosis for patients clinically diagnosed with congenital anomalies of kidney and urinary tract (CAKUT). WES was performed in 62 families with CAKUT. WES data were analyzed for single-nucleotide variants (SNVs) in 35 known CAKUT genes, putatively deleterious sequence changes in new candidate genes, and potentially disease-associated copy-number variants (CNVs). In approximately 5% of families, pathogenic SNVs were identified in PAX2, HNF1B, and EYA1. Observed phenotypes in these families expand the current understanding about the role of these genes in CAKUT. Four pathogenic CNVs were also identified using two CNV detection tools. In addition, we found one deleterious de novo SNV in FOXP1 among the 62 families with CAKUT. The clinical database of the Baylor Miraca Genetics laboratory was queried and seven additional unrelated individuals with novel de novo SNVs in FOXP1 were identified. Six of these eight individuals with FOXP1 SNVs have syndromic urinary tract defects, implicating this gene in urinary tract development. We conclude that WES can be used to identify molecular etiology (SNVs, CNVs) in a subset of individuals with CAKUT. WES can also help identify novel CAKUT genes. Genet Med19 4, 412–420.

Tamoxifen resistance mechanism Tamoxifen is commonly used for breast cancer therapy, but a proportion of patients become resistant to the treatment, and their cancer is more likely to return. A study of the relationship between the oestrogen receptor and ERBB2/HER-2 pathways in breast cancer throws light on the mechanism of tamoxifen action and on the basis of tamoxifen-resistance. The new work shows that Pax2 is required for active repression of ErbB2 in breast cancer and that reduction of Pax2 causes ErbB2-driven tamoxifen-resistant cell growth. Tamoxifen is commonly used for breast cancer therapy. This paper shows that the transcriptional repression of the ERBB2 oncogene by tamoxifen in breast cancer cells is affected by an antagonistic interaction between the transcriptional regulators PAX2 and AIB-1. This affects the ability of tamoxifen to inhibit cancer cell proliferation. The relative levels of PAX2 and AIP1 in breast cancer patients treated with tamoxifen correlates with relapse-free survival. Crosstalk between the oestrogen receptor (ER) and ERBB2/HER-2 pathways has long been implicated in breast cancer aetiology and drug response 1 , yet no direct connection at a transcriptional level has been shown. Here we show that oestrogen–ER and tamoxifen–ER complexes directly repress ERBB2 transcription by means of a cis -regulatory element within the ERBB2 gene in human cell lines. We implicate the paired box 2 gene product (PAX2), in a previously unrecognized role, as a crucial mediator of ER repression of ERBB2 by the anti-cancer drug tamoxifen. We show that PAX2 and the ER co-activator AIB-1/SRC-3 compete for binding and regulation of ERBB2 transcription, the outcome of which determines tamoxifen response in breast cancer cells. The repression of ERBB2 by ER-PAX2 links these two breast cancer subtypes and suggests that aggressive ERBB2-positive tumours can originate from ER-positive luminal tumours by circumventing this repressive mechanism. These data provide mechanistic insight into the molecular basis of endocrine resistance in breast cancer.

Renal cell carcinoma (RCC) is a significant oncological challenge due to its heterogeneous nature and limited treatment options. The PAX developmental gene family encodes nine highly conserved transcription factors that play crucial roles in embryonic development and organogenesis, which have been implicated in the occurrence and development of RCC. This review explores the molecular landscape of RCC, with a specific focus on the role of the PAX gene family in RCC tumorigenesis and disease progression. Of the various RCC subtypes, clear cell renal cell carcinoma (ccRCC) is the most prevalent, characterized by the loss of the von Hippel–Lindau (VHL) tumor suppressor gene. Here, we review the published literature on the expression patterns and functional implications of PAX genes, particularly PAX2 and PAX8, in the three most common RCC subtypes, including ccRCC, papillary RCC (PRCC), and chromophobe RCC (ChRCC). Further, we review the interactions and potential biological mechanisms involving PAX genes and VHL loss in driving the pathogenesis of RCC, including the key signaling pathways mediated by VHL in ccRCC and associated mechanisms implicating PAX. Lastly, concurrent with our update regarding PAX gene research in RCC, we review and comment on the targeting of PAX towards the development of novel RCC therapies.

Background Pathogenic variants of PAX2 cause autosomal-dominant PAX2 -related disorder, which includes variable phenotypes ranging from renal coloboma syndrome (RCS), congenital anomalies of the kidney and urinary tract (CAKUT) to nephrosis. Phenotypic variability makes it difficult to define the phenotypic spectrum associated with genotype. Methods We collected the phenotypes in patients enrolled in the China national multicenter registry who were diagnosed with pathogenic variant in PAX2 and reviewed all published cases with PAX2 -related disorders. We conducted a phenotype-based cluster analysis by variant types and molecular modeling of the structural impact of missense variants. Results Twenty different PAX2 pathogenic variants were identified in 32 individuals (27 families) with a diagnosis of RCS (9), CAKUT (11) and nephrosis (12) from the Chinese cohort. Individuals with abnormal kidney structure (RCS or CAKUT group) tended to have likely/presumed gene disruptive (LGD) variants ( Fisher test , p  < 0.05). A system review of 234 reported cases to date indicated a clear association of RCS to heterozygous loss-of-function PAX2 variants (LGD variants). Furthermore, we identified a subset of PAX2 missense variants in DNA-binding domain predicted to affect the protein structure or protein-DNA interaction associated with the phenotype of RCS. Conclusion Defining the phenotypic spectrum combined with genotype in PAX2 -related disorder allows us to predict the pathogenic variants associated with renal and ophthalmological development. It highlighted the approach of structure-based analysis can be applied to diagnostic strategy aiding precise and timely diagnosis.