METTL3 regulates thyroid cancer differentiation and chemosensitivity by modulating PAX8.

Background: Thyroid cancer (TC) is a common endocrine cancer with a favourable prognosis. However, poor patient prognosis due to TC dedifferentiation is becoming an urgent challenge. Recently, methyltransferase-like 3 (METTL3)-mediated N6 -methyladenosine (m6A) modification has been demonstrated to play an important role in the occurrence and progression of various cancers and a tumour suppressor role in TC. However, the mechanism of METTL3 in TC remains unclear. Methods: The correlation between METTL3 and prognosis in TC patients was evaluated by immunohistochemistry. Mettl3fl/flBrafV600ETPO-cre TC mouse models and RNA-seq were used to investigate the underlying molecular mechanism, which was further validated by in vitro experiments. The target gene of METTL3 was identified, and the complete m6A modification process was described. The phenomenon of low expression of METTL3 in TC was explained by identifying miRNAs that regulate METTL3. Results: We observed that METTL3 expression was negatively associated with tumour progression and poor prognosis in TC. Mechanistically, silencing METTL3 promoted the progression and dedifferentiation of papillary thyroid carcinoma (PTC) both in vivo and in vitro. Moreover, overexpressing METTL3 promoted the sensitivity of PTC and anaplastic thyroid cancer (ATC) cells to chemotherapeutic drugs and iodine-131 (131I) administration. Overall, the METTL3/PAX8/YTHDC1 axis has been revealed to play a pivotal role in repressing tumour occurrence, and is antagonized by miR-493-5p.

The Role of the PAX Genes in Renal Cell Carcinoma.

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.

In Silico Search for Drug Candidates Targeting the PAX8-PPARγ Fusion Protein in Thyroid Cancer.

The PAX8/PPARγ rearrangement, producing the PAX8-PPARγ fusion protein (PPFP), is thought to play an essential role in the oncogenesis of thyroid follicular tumors. To identify PPFP-targeted drug candidates and establish an early standard of care for thyroid tumors, we performed ensemble-docking-based compound screening. Specifically, we investigated the pocket structure that should be adopted to search for a promising ligand compound for the PPFP; the position of the ligand-binding pocket on the PPARγ side of the PPFP is similar to that of PPARγ; however, the shape is slightly different between them due to environmental factors. We developed a method for selecting a PPFP structure with a relevant pocket and high prediction accuracy for ligand binding. This method was validated using PPARγ, whose structure and activity values are known for many compounds. Then, we performed docking calculations to the PPFP for 97 drug or drug-like compounds registered in the DrugBank database with a thiazolidine backbone, which is one of the characteristics of ligands that bind well to PPARγ. Furthermore, the binding affinities of promising ligand candidates were estimated more reliably using the molecular mechanics Poisson-Boltzmann surface area method. Thus, we propose promising drug candidates for the PPFP with a thiazolidine backbone.

Pax protein depletion in proximal tubules triggers conserved mechanisms of resistance to acute ischemic kidney injury preventing transition to chronic kidney disease.

Acute kidney injury (AKI) is a common condition that lacks effective treatments. In part, this shortcoming is due to an incomplete understanding of the genetic mechanisms that control pathogenesis and recovery. Identifying the molecular and genetic regulators unique to nephron segments that dictate vulnerability to injury and regenerative potential could lead to new therapeutic targets to treat ischemic kidney injury. Pax2 and Pax8 are homologous transcription factors with overlapping functions that are critical for kidney development and are re-activated in AKI. Here, we examined the role of Pax2 and Pax8 in recovery from ischemic AKI and found them upregulated after severe AKI and correlated with chronic injury. Surprisingly, proximal-tubule-selective deletion of Pax2 and Pax8 resulted in a less severe chronic injury phenotype. This effect was mediated by protection against the acute insult, similar to pre-conditioning. Prior to injury, Pax2 and Pax8 mutant mice develop a unique subpopulation of proximal tubule cells in the S3 segment that displayed features usually seen only in acute or chronic injury. The expression signature of these cells was strongly enriched with genes associated with other mechanisms of protection against ischemic AKI including caloric restriction, hypoxic pre-conditioning, and female sex. Thus, our results identified a novel role for Pax2 and Pax8 in mature proximal tubules that regulates critical genes and pathways involved in both the injury response and protection from ischemic AKI.

Methylation of Septin9, SRSF1, and PAX8 in Early Screening of Colorectal Cancer in the Population Undergoing Physical Examinations.

BACKGROUND: The aim was to investigate the value of blood Septin9, SRSF1, and PAX8 gene methylation detection techniques in early screening of colorectal cancer (CRC). METHODS: A prospective cohort study enrolled 3,000 participants undergoing routine physical examination at Shizong County People's Hospital Health Management Center from December 2021 through November 2022, including 1,512 males and 1,488 females, ranging in age from 20 to 90 years, with a median age of 49 years. Fresh blood samples were collected and tested for Septin9, SRSF1, and PAX8 gene methylation. Positive or negative results were reported. Colonoscopy was recommended for positive results and telephone follow-up for negative results. A chi-squared test analyzed the positive rate of initial screening, colonoscopy compliance, and the detection rate of colorectal lesions. Finally, combined with the follow-up data, the screening effect of Septin9, SRSF1, and PAX8 methylation detection on CRC was evaluated. RESULTS: Among 3,000 cases, 215 cases were preliminarily positive, with a positive rate of 7.1% (215/3,000). The positive rate of Septin9 gene methylation was the highest (6%, 180/3000), followed by SRSF1 (4.1%, 124/3000) and PAX8 (3.6%, 108/3000). The sensitivity of combined detection of Septin9, SRSF1, and PAX8 methylation in the diagnosis of CRC was higher than that of the three alone, and the specificity, positive predictive value, and negative predictive value of combined detection were higher than that of the single detection of blood Septin9, SRSF1, and PAX8 DNA methylation. In addition, the positive rate of initial screening increased with age (χ2 = 32.135, p < 0.001). A total of 150 cases underwent further colonoscopy, and the colonoscopy compliance rate was 69.8% (150/215). Among 150 cases who completed colonoscopy, 5 cases of CRC (3.4%), 25 cases of advanced adenoma (16.0%), 78 cases of non-advanced adenoma (52.0%), and 24 cases of non-adenomatous polyps (22.7%) were detected. The positive predictive value of Septin9, SRSF1, and PAX8 methylation was 94% (141/150) for all colorectal lesions, and 70.0% (105/150) for colorectal cancer and precancerous lesions. CONCLUSIONS: Blood Septin9, SRSF1, and PAX8 gene methylation detection, combined with colonoscopy, can effectively detect colorectal cancer and precancerous lesions. This strategy may be an effective way to carry out large-scale colorectal cancer screening in the general risk population. Combined detection of the three genes can improve the detection rate of colorectal cancer, but Septin9 methylation is the most sensitive, which can be used for screening and efficacy evaluation of CRC.

Two Cases of Biphasic Synovial Sarcoma With Expression of PAX8 and ER: A Diagnostic Pitfall.

Synovial sarcoma (SS) is a high-grade malignant neoplasm frequently arising in the deep soft tissue of the lower and upper extremities of young adults. Primary SS in the pelvis is extremely rare with scattered case reports. It often causes a diagnostic challenge in small biopsy and/or with aberrant expression of immunohistochemical markers. Here, we report 2 unusual cases of SS in the pelvis. Microscopically both cases present with biphasic morphology including spindle and epithelioid cells. In addition, the tumor cells in both cases expressed PAX8 and estrogen receptor. PAX8 is a transcription factor usually expressed in tumors of thyroid gland, kidney, and Müllerian system origin. The expression of PAX8 especially with co-expression of estrogen receptor can be misleading and result in a diagnosis of Müllerian tumors in female patients with pelvic masses. The diagnosis of SS for both cases was confirmed either with the fluorescence in situ hybridization or reverse transcription polymerase chain reaction showing a SS18 (SYT) (18q11) gene rearrangement. It is imperative to include SS in the differential diagnosis for malignant neoplasms exhibiting monotonous spindle cells (monophasic SS) and biphasic mixed monotonous spindle and epithelioid tumor cells in female patients with a pelvic mass. Molecular study for SS18 translocation is essential for the diagnosis in such cases.

Novel Missense Variants in PAX8 and NKX2-1 Cause Congenital Hypothyroidism.

Primary congenital hypothyroidism (CH) is a common neonatal endocrine disorder characterized by elevated concentrations of thyroid stimulating hormone (TSH) and low concentrations of free thyroxine (FT4). PAX8 and NKX2-1 are important transcription factors involved in thyroid development. In this study, we detected three novel variants in PAX8 (c.149A > C and c.329G > A) and NKX2-1 (c.706A > G) by whole exome sequencing (WES) in three unrelated CH patients with variable phenotypes. The results of Western blot and immunofluorescence analysis showed that the three variants had no effect on protein expression and subcellular localization. However, the results of the electrophoretic mobility shift assay (EMSA) and dual-luciferase reporter assay suggested that the three variants in PAX8 and NKX2-1 both affected their DNA-binding ability and reduced their transactivation capacity. Moreover, a dominant-negative effect in K236E−NKX2-1 was identified by dual-luciferase reporter assay. To sum up, our findings extend our knowledge of the current mutation spectrum of PAX8 and NKX2-1 and provide important information for diagnosing, treating, and preventing CH in these families.

Association of LncRNA-PAX8-AS1 and LAIR-2 polymorphisms along with their expression with clinical and subclinical hypothyroidism.

The genetic and epigenetic architecture of clinical and subclinical hypothyroidism remains unclear. We investigated the impact of long noncoding RNA (LncRNA)-PAX8-AS1 and LAIR-2 genetic variants on the susceptibility to clinical and subclinical hypothyroidism, their influence on LncRNA-PAX8-AS1 and LAIR-2 expression and their potential as hypothyroid biomarkers. Hundred clinical hypothyroid patients, 110 subclinical hypothyroid patients, and 95 healthy controls were enrolled. Gene expression analysis and genotyping were performed by qPCR. LAIR-2 protein, a proinflammatory mediator, was tested by ELISA. Serum LncRNA-PAX8-AS1 was downregulated, whereas LAIR-2 mRNA and protein levels were upregulated in clinical and subclinical hypothyroid patients compared to healthy controls. LncRNA-PAX8-AS1 rs4848320 and rs1110839 were associated with increased risk of clinical hypothyroidism. Interestingly, both SNPs were associated with differential expression of serum LncRNA-PAX8-AS1 among clinical hypothyroid patients. LAIR-2 rs2287828 was associated with elevated risk of both clinical and subclinical hypothyroidism. Harboring the rs2287828 T allele augmented the LAIR-2 mRNA expression among clinical hypothyroid patients, while elevated both LAIR-2 mRNA and protein levels in subclinical hypothyroid patients. The rs4848320-rs1110839-rs2287828 TTT, CTT, and CGT haplotypes were associated with increased hypothyroid risk. Surprisingly, serum LncRNA-PAX8-AS1 and LAIR-2 mRNA expression demonstrated superior diagnostic accuracy for clinical hypothyroidism and turned out as independent predictors in the multivariate analysis. Conclusively, LncRNA-PAX8-AS1 and LAIR-2 genetic variants are novel genetic biomarkers of hypothyroidism that could alter the LncRNA-PAX8-AS1 and LAIR-2 expression. LncRNA-PAX8-AS1 and LAIR-2 expression profiles have the potential as effective diagnostic and prognostic indicators of hypothyroidism.

PAX8 modulates the tumor microenvironment of high grade serous ovarian cancer through changes in the secretome.

High grade serous ovarian cancer (HGSC) arises from the fimbriated end of the fallopian tube epithelium (FTE), and in some cases, the ovarian surface epithelium (OSE). PAX8 is a commonly used biomarker for HGSC and is expressed in ∼90% of HGSC. Although the OSE does not express PAX8, murine models of HGSC derived from the OSE acquire PAX8, suggesting that it is not only a marker of Müllerian origin, but also an essential part of cancer progression, potentially from both the OSE and FTE. Previously, we have shown that PAX8 loss in HGSC cells causes tumor cell death and reduces cell migration and invasion. Herein, secretome analysis was performed in PAX8 deleted cells and we identified a reduction of the extracellular matrix (ECM) components, collagen and fibronectin. Immunoblotting and immunofluorescence in PAX8 deleted HGSC cells further validated the results from the secretome analysis. PAX8 loss reduced the amount of secreted TGFbeta, a cytokine that plays a crucial role in remodelling the tumor microenvironment. Furthermore, PAX8 loss reduced the integrity of 3D spheroids and caused a reduction of ECM proteins fibronectin and collagen in 3D cultures. Due to the ubiquitous nature of PAX8 in HGSC, regardless of cell origin, and the association of its reduced expression with decreasing tumor burden, a PAX8 inhibitor could be a promising drug target against various types of HGSC. To accomplish this, we generated a murine oviductal epithelial (MOE) cell line stably expressing PAX8 promoter-luciferase. Using this cell line, we performed a screening assay with a library of FDA-approved drugs (Prestwick Library) and quantitatively assessed these compounds for their inhibition of PAX8. We identified two hits: losartan and captropril, both inhibitors of the renin-angiotensin pathway that inhibit PAX8 expression and function. Overall, this study validates PAX8 as a regulator of ECM deposition in the tumor microenvironment.

Multi-genomic analysis of 260 adrenocortical cancer patient tumors identifies novel network BIRC5-hsa-miR-335-5p-PAX8-AS1 strongly associated with poor survival.

BACKGROUND: Adrenocortical carcinoma is a rare endocrine cancer with poor overall survival. Linking survival outcomes to a common target across multiple genomic datasets incorporating microRNA-long non-coding RNA dysregulation have not been well described. We hypothesized that a multi-database analysis of microRNA-long noncoding RNA-messenger RNA regulatory networks associated with survival will identify novel biomarkers. METHODS: Significantly dysregulated genes or microRNA in adrenocortical carcinoma compared to normal adrenal was identified from sequencing data for 260 human adrenocortical carcinomas using GEO2R. The miRnet identified hub microRNA and genes and long noncoding RNA and microRNA associated with survival genes. The R2 generated Kaplan-Meier curves. The database miRTarBase linked genes associated with poor survival and dysregulated microRNA. RESULTS: Analysis of genes and microRNAs differentially regulated in >50% of datasets revealed 75 genes and 12 microRNAs were upregulated, and 167 genes and 12 microRNAs were downregulated (bonf. P < .05). Kyoto Encyclopedia of Genes and Genomes pathway analysis revealed cell cycle, P53 signaling, arachidonic acid and innate immune response, and PI3/Akt are altered in adrenocortical carcinoma. A microRNA-target interaction network of differentially regulated microRNAs identified upregulated miRNA107, 103a-3p and 27a-3p, 16-5p, and downregulated 335-5p to have the highest degree of interaction with upregulated (ie, TPX2, CDK1, BIRC5, PRC1, CCNB1, GINS1) and downregulated (ie, RSPO3, NR2F1, TLR4, HOXA5, USP53, SLC16A9) hub genes as well as hub long noncoding RNAs XIST, NEAT1, KCNQ1OT1, and PAX8-AS1. Survival analysis revealed that the hub genes are associated with poor overall survival (P < .05) of adrenocortical carcinoma in the Cancer Genome Atlas data. CONCLUSION: A messenger RNA-microRNA-long noncoding RNA network analysis identified the BIRC5-miR335-5p-PAX8-AS1 network as one that was associated with poor overall survival in adrenocortical carcinoma, warranting further validation as a potential therapeutic target.

Initial screening of the rs104893657 variant of the PAX8 gene in women with hypothyroidism from Northeastern Slovakia.

OBJECTIVE: Thyroid diseases are among the most common endocrinopathies and metabolic disorders. Hypothyroidism is caused by insufficient production of thyroid hormones with a higher prevalence in women. Causes for the development of endocrine diseases may be mutations in genes that encode peptide hormones. The aim of this scientific study was to determine the genotype and allele frequencies of the rs104893657 variant of the PAX8 gene and to determine the genotype versus phenotype association. METHODS: The study population consisted of 135 women from northeastern Slovakia who were divided on the basis of screening into two groups: a control group without diagnosed hypothyroidism (CG = 67) and a group of women with hypothyroidism (HY = 68). Biochemical markers - thyroid-stimulating hormone (TSH), prealbumin (PREA), calcium (Ca), phosphorus (P), and alkaline phosphatase (ALP) were determined using Cobas Integra 400 plus, Cobas e411 analysers (Roche). Genotyping was performed using TaqMan® SNP Genotyping Assay instrument 7500 Fast Real-Time PCR Systems (Applied Biosystem). RESULTS: Student's t-test revealed a statistically significant difference between CG and HY in biochemical parameters: TSH (p < 0.001), P (p = 0.008). By Chi-square test we found no statistically significant difference in the representation of genotypes (p = 0.788) in the rs104893657 polymorphism of PAX8 gene. The T allele was not associated with hypothyroidism in Slovak women (p = 0.548). In CC genotype we found statistically significant difference between CG and HY in parameters TSH (p < 0.001) and P (p = 0.006). CONCLUSION: The mutant T allele was detected at low frequency in both groups of women studied. The association of the T allele with the development of hypothyroidism in Slovak women was not confirmed. The results of this work provide initial information on the distribution of genotypes and alleles in the studied variant of PAX8 gene in the Slovak female population.

Hnf1b renal expression directed by a distal enhancer responsive to Pax8.

Xenopus provides a simple and efficient model system to study nephrogenesis and explore the mechanisms causing renal developmental defects in human. Hnf1b (hepatocyte nuclear factor 1 homeobox b), a gene whose mutations are the most commonly identified genetic cause of developmental kidney disease, is required for the acquisition of a proximo-intermediate nephron segment in Xenopus as well as in mouse. Genetic networks involved in Hnf1b expression during kidney development remain poorly understood. We decided to explore the transcriptional regulation of Hnf1b in the developing Xenopus pronephros and mammalian renal cells. Using phylogenetic footprinting, we identified an evolutionary conserved sequence (CNS1) located several kilobases (kb) upstream the Hnf1b transcription start and harboring epigenomic marks characteristics of a distal enhancer in embryonic and adult renal cells in mammals. By means of functional expression assays in Xenopus and mammalian renal cell lines we showed that CNS1 displays enhancer activity in renal tissue. Using CRISPR/cas9 editing in Xenopus tropicalis, we demonstrated the in vivo functional relevance of CNS1 in driving hnf1b expression in the pronephros. We further showed the importance of Pax8-CNS1 interaction for CNS1 enhancer activity allowing us to conclude that Hnf1b is a direct target of Pax8. Our work identified for the first time a Hnf1b renal specific enhancer and may open important perspectives into the diagnosis for congenital kidney anomalies in human, as well as modeling HNF1B-related diseases.

Significance analysis of PAX8 expression in endometrial carcinoma.

To analyze the expression and prognostic value of paired-box 8 (PAX8) expression in uterine corpus endometrial carcinoma (UCEC) by bioinformatics. The expression of PAX8 gene in UCEC was analyzed by R language and immunohistochemistry. The correlation between PAX8 expression and clinicopathological features was analyzed by R language. The prognostic factors was analyzed by univariate/multivariate regression. The survival curve of patients was analyzed by Kaplan-Meier Plotter (K-M Plotter). The diagnostic value of PAX8 in UCEC was analyzed by receiver operating characteristic curve, and the relationship between PAX8 expression and methylation was analyzed by Ualcan. The relationship between methylation and prognosis was analyzed by MethSurv database. The expression of PAX8 in cancer tissues was significantly higher than that in normal tissues. The expression of PAX8 was related to clinical stage, age, histological type, histologic grade, tumor invasion and disease-specific survival event. Univariate/multivariate regression analysis showed that clinical stage, tumor invasion, and PAX8 expression were the influence factors of overall survival (OS), while histologic grade and PAX8 expression were the influence factors of disease-specific survival, and patients with low expression had a longer OS. The area under the curve of receiver operating characteristic curve was 0.81 for PAX8 diagnosis of UCEC. PAX8 was hypomethylated in cancer tissue, and patients with hypermethylated PAX8 had a longer OS. The high expression of PAX8 induced by hypomethylation may play an important role in the occurrence and prognosis of UCEC.

PAX8 in the Junction between Development and Tumorigenesis.

Normal processes of embryonic development and abnormal transformation to cancer have many parallels, and in fact many aberrant cancer cell capabilities are embryonic traits restored in a distorted, unorganized way. Some of these capabilities are cell autonomous, such as proliferation and resisting apoptosis, while others involve a complex interplay with other cells that drives significant changes in neighboring cells. The correlation between embryonic development and cancer is driven by shared proteins. Some embryonic proteins disappear after embryogenesis in adult differentiated cells and are restored in cancer, while others are retained in adult cells, acquiring new functions upon transformation to cancer. Many embryonic factors embraced by cancer cells are transcription factors; some are master regulators that play a major role in determining cell fate. The paired box (PAX) domain family of developmental transcription factors includes nine members involved in differentiation of various organs. All paired box domain proteins are involved in different cancer types carrying pro-tumorigenic or anti-tumorigenic roles. This review focuses on PAX8, a master regulator of transcription in embryonic development of the thyroid, kidney, and male and female genital tracts. We detail the role of PAX8 in each of these organ systems, describe its role during development and in the adult if known, and highlight its pro-tumorigenic role in cancers that emerge from PAX8 expressing organs.

The Significance of PAX8-PPARγ Expression in Thyroid Cancer and the Application of a PAX8-PPARγ-Targeted Ultrasound Contrast Agent in the Early Diagnosis of Thyroid Cancer.

Objective: To investigate the significance of PAX8-PPARγ expression in thyroid cancer and the application of a PAX8-PPARγ-targeted ultrasound contrast agent in the early diagnosis of thyroid cancer. Methods: In this study, the expression of PAX8-PPARγ in thyroid cancer tissues, paracancer groups, and normal thyroid tissues was detected by western and immunohistochemical techniques; the effects of PAX8-PPARγ expression inhibition on thyroid cancer cell growth, clonogenic ability, and antiapoptosis were examined. The terminal carboxylactic acid/hydroxyacetic acid copolymer (PLGA-COOH) nanoparticles were prepared by the double emulsification solvent volatilization method. The in vitro cytotoxicity of the targeted contrast agent was detected by MTS and other methods; LD50 was used to evaluate its short-term in vivo toxicity after intraperitoneal injection in mice. Results: PAX8-PPARγ expression was significantly increased in thyroid cancer tissues, and the expression level of PAX8-PPARγ was closely correlated with TNM staging and lymph node metastasis (P < 0.05). In addition, PAX8-PPARγ was also expressed at high levels in thyroid cancer cell lines relative to normal thyroid cells. MTS experiments showed that the PAX8-PPARγ-targeted ultrasound nanocontrast agent had no significant toxic side effects on thyroid cells; countess observed that the contrast agent had no effect on cell survival and mortality; the LD50 assay showed that the targeted contrast agent had a wide safety range. Western blot showed the expression of caspase-3, BAX, and Bcl-2 in thyroid cancer cells, indicating that the nanocontrast agent has a good biosafety. In vitro targeting experiments showed that there were more nanospheres aggregated around the cells in the targeted contrast group. In vivo targeting imaging of nude mice revealed that the ultrasound signal was significantly enhanced in the targeted group compared with the nontargeted group after 20 min of LIFU irradiation. Conclusion: PAX8-PPARγ overexpression in thyroid cancer cell lines and thyroid cancer tissues promoted the proliferation and antiapoptotic ability of thyroid cancer cells and promoted the tumorigenic ability in nude mice in vivo. We successfully prepared a PAX8-PPARγ-targeted ultrasound nanocontrast agent, which has regular morphology, uniform size, and high stability, and its liquid-gas phase change can be promoted at lower temperature. Therefore, this contrast agent can achieve US-targeted imaging and temperature phase transition function, and may have enhanced ultrasound imaging potential.

The renal lineage factor PAX8 controls oncogenic signalling in kidney cancer.

Large-scale human genetic data1-3 have shown that cancer mutations display strong tissue-selectivity, but how this selectivity arises remains unclear. Here, using experimental models, functional genomics and analyses of patient samples, we demonstrate that the lineage transcription factor paired box 8 (PAX8) is required for oncogenic signalling by two common genetic alterations that cause clear cell renal cell carcinoma (ccRCC) in humans: the germline variant rs7948643 at 11q13.3 and somatic inactivation of the von Hippel-Lindau tumour suppressor (VHL)4-6. VHL loss, which is observed in about 90% of ccRCCs, can lead to hypoxia-inducible factor 2α (HIF2A) stabilization6,7. We show that HIF2A is preferentially recruited to PAX8-bound transcriptional enhancers, including a pro-tumorigenic cyclin D1 (CCND1) enhancer that is controlled by PAX8 and HIF2A. The ccRCC-protective allele C at rs7948643 inhibits PAX8 binding at this enhancer and downstream activation of CCND1 expression. Co-option of a PAX8-dependent physiological programme that supports the proliferation of normal renal epithelial cells is also required for MYC expression from the ccRCC metastasis-associated amplicons at 8q21.3-q24.3 (ref. 8). These results demonstrate that transcriptional lineage factors are essential for oncogenic signalling and that they mediate tissue-specific cancer risk associated with somatic and inherited genetic variants.

Oncogenic Signaling in Kidney Cancer Requires Renal Lineage Factor PAX8.

Lineage factor PAX8 is essential for downstream oncogenic signaling of ccRCC-specific driver mutations.

A Novel Pathogenic Variant in PAX8 Leads to Familial Congenital Hypothyroidism.

We report a 10-month-old girl with familial congenital hypothyroidism harboring a novel heterozygous pathogenic variant in the paired DNA-binding domain of PAX8 (NM_003466:c.110T>C:p.Leu37Pro). Genotype-phenotype correlation revealed complete penetrance of this PAX8 defect in this family, in which the affected father and half-brother carry the same mutation. This deleterious variant has not been reported in any of the available databases [MAFgnomAD = 0, dbSNP (-)], and the amino acid leucine at position 37 is highly conserved across species. Establishing the molecular diagnosis expands our knowledge on the cause of thyroid dysgenesis and provides a guide for counseling and early treatment.

Spindle Cell/Sclerosing Rhabdomyosarcoma With PAX8::PPARG Fusion.

The spindle cell/sclerosing subtype of rhabdomyosarcoma is classified based on genetic features into the three categories of MYOD1-mutated, gene fusion-driven, and a subset without a currently identified genetic driver event. The gene fusion-driven spindle cell/sclerosing rhabdomyosarcomas are heterogenous and characterized by increasing numbers of gene fusions, the most common gene partners being VGLL2, NCOA2, and TFCP2. Here we report a spindle cell/sclerosing rhabdomyosarcoma that arose in the orbit of a 4-year-old male. This tumor harbored a unique PAX8::PPARG fusion. PAX8::PPARG fusions have previously only been described in follicular thyroid carcinoma and follicular variant of papillary thyroid carcinoma. Our report adds to the growing number of gene fusions in spindle cell/sclerosing rhabdomyosarcomas.