Unraveling the influence of TTF-1 expression on immunotherapy outcomes in PD-L1-high non-squamous NSCLC: a retrospective multicenter study.

Introduction: Several studies explored the association between thyroid transcription factor-1 (TTF-1) and the therapeutic efficacy of immunotherapy. However, the effect of TTF-1 on the therapeutic efficacy of programmed death-1 (PD-1) inhibitor/chemoimmunotherapy in patients with non-squamous non-small cell lung cancer (non-Sq NSCLC) with a programmed death-ligand 1 (PD-L1) tumor proportion score of 50% or more who are highly susceptible to immunotherapy remains unresolved. Therefore, we evaluated whether TTF-1 has a clinical impact on this population. Methods: Patients with non-Sq NSCLC and high PD-L1 expression who received PD-1 inhibitor monotherapy or chemoimmunotherapy between May 2017 and December 2020 were retrospectively enrolled. Treatment efficacy was compared after adjusting for baseline differences using propensity score matching. Results: Among the 446 patients with NSCLC with high PD-L1 expression, 266 patients with non-Sq NSCLC were analyzed. No significant differences in therapeutic efficacy were observed between the TTF-1-positive and -negative groups in the overall and propensity score-matched populations. Of chemoimmunotherapy, pemetrexed containing regimen significantly prolonged progression-free survival compared to chemoimmunotherapy without pemetrexed, regardless of TTF-1 expression (TTF1 positive; HR: 0.46 (95% Confidence interval: 0.26-0.81), p<0.01, TTF-1 negative; HR: 0.29 (95% Confidence interval: 0.09-0.93), p=0.02). Discussion: TTF-1 expression did not affect the efficacy of PD-1 inhibitor monotherapy or chemoimmunotherapy in patients with non-Sq NSCLC with high PD-L1 expression. In this population, pemetrexed-containing chemoimmunotherapy demonstrated superior anti-tumor efficacy, irrespective of TTF-1 expression.

Systematic review of thyroid function in NKX2-1-related disorders: Screening and diagnosis.

BACKGROUND: NKX2-1-related disorders (NKX2-1-RD) are rare conditions affecting lung, thyroid, and brain development, primarily caused by pathogenic variants or deletions in the NKX2-1 gene. Congenital hypothyroidism (CH) is a common endocrine manifestation, leading to irreversible intellectual disability if left untreated. OBJECTIVES: The aim was to evaluate the current evidence for the use of screening and diagnostic techniques for endocrine alterations in patients with NKX2-1-RD. METHODS: This systematic review was reported following the PRISMA guidelines. Two separate research questions in PICO format were addressed to cover initial screening and diagnosis procedures for endocrine diseases in patients with NKX2-1-RD. Eligibility criteria focused on patients with genetic confirmation of the disease and hypothyroidism. Various databases were searched, and data were extracted and assessed independently by two reviewers. RESULTS: Out of 1012 potentially relevant studies, 46 were included, for a total of 113 patients. CH was the most frequent endocrine alteration (45% of patients). Neonatal screening was reported in only 21% of patients based on blood TSH measurements. TSH thresholds varied widely across studies, making hypothyroidism detection ranges difficult to establish. Diagnostic tests using serum TSH were used to diagnose hypothyroidism or confirm its presence. 35% of patients were diagnosed at neonatal age, and 42% at adult age. Other hormonal dysfunctions identified due to clinical signs, such as anterior pituitary deficiencies, were detected later in life. Thyroid scintigraphy and ultrasonography allowed for the description of the thyroid gland in 30% of cases of hypothyroidism. Phenotypic variability was observed in individuals with the same variants, making genotype-phenotype correlations challenging. CONCLUSION: This review highlights the need for standardized protocols in endocrine screening for NKX2-1-RD, emphasizing the importance of consistent methodology and hormone threshold levels. Variability in NKX2-1 gene variants further complicates diagnostic efforts. Future research should concentrate on optimizing early screening protocols and diagnostic strategies.

Gastric-Type Expression Signature in Hepatocellular Carcinoma.

It is known that V-set and immunoglobulin domain containing 1 (VSIG1) is a cell-cell adhesion molecule that can serve as an indicator of better survival in patients with gastric cancer. Its interaction with cytoplasmic thyroid transcription factor 1 (TTF-1) has been hypothesized to characterize gastric-type HCC, but its clinical importance is far from understood. As VSIG1 has also been supposed to be involved in the epithelial-mesenchymal transition (EMT) phenomenon, we checked for the first time in the literature the supposed interaction between VSIG1, TTF-1, and Vimentin (VIM) in HCCs. Immunohistochemical (IHC) stains were performed on 217 paraffin-embedded tissue samples that included tumor cells and normal hepatocytes, which served as positive internal controls. VSIG1 positivity was seen in 113 cases (52.07%). In 71 out of 217 HCCs (32.71%), simultaneous positivity for VSIG1 and TTF-1 was seen, being more specific for G1/G2 carcinomas with a trabecular architecture and a longer OS (p = 0.004). A negative association with VIM was revealed (p < 0.0001). Scirrhous-type HCC proved negative for all three examined markers. The present paper validates the hypothesis of the existence of a gastric-type HCC, which shows a glandular-like architecture and is characterized by double positivity for VSIG1 and TTF-1, vimentin negativity, and a significant OS.

A Novel Missense Variant in the NKX2-1 Homeodomain Prevents Transcriptional Rescue by TAZ.

Background: Brain-lung-thyroid syndrome (BLTS) is caused by NKX2-1 haploinsufficiency, resulting in chorea/choreoathetosis, respiratory problems, and hypothyroidism. Genes interacting with NKX2-1 mutants influence its phenotypic variability. We report a novel NKX2-1 missense variant and the modifier function of TAZ/WWTR1 in BLTS. Methods: A child with BLTS underwent next-generation sequencing panel testing for thyroid disorders. His family was genotyped for NKX2-1 variants and screened for germline mosaicism. Mutant NKX2-1 was generated, and transactivation assays were performed on three NKX2-1 target gene promoters. DNA binding capacity and protein-protein interaction were analyzed. Results: The patient had severe BLTS and carried a novel missense variant c.632A>G (p.N211S) in NKX2-1, which failed to bind to specific DNA promoters, reducing their transactivation. TAZ cotransfection did not significantly increase transcription of these genes, although the variant retained its ability to bind to TAZ. Conclusions: We identify a novel pathogenic NKX2-1 variant that causes severe BLTS and is inherited through germline mosaicism. The mutant lacks DNA-binding capacity, impairing transactivation and suggesting that NKX2-1 binding to DNA is essential for TAZ-mediated transcriptional rescue.

CEBPA restricts alveolar type 2 cell plasticity during development and injury-repair.

Cell plasticity theoretically extends to all possible cell types, but naturally decreases as cells differentiate, whereas injury-repair re-engages the developmental plasticity. Here we show that the lung alveolar type 2 (AT2)-specific transcription factor (TF), CEBPA, restricts AT2 cell plasticity in the mouse lung. AT2 cells undergo transcriptional and epigenetic maturation postnatally. Without CEBPA, both neonatal and mature AT2 cells reduce the AT2 program, but only the former reactivate the SOX9 progenitor program. Sendai virus infection bestows mature AT2 cells with neonatal plasticity where Cebpa mutant, but not wild type, AT2 cells express SOX9, as well as more readily proliferate and form KRT8/CLDN4+ transitional cells. CEBPA promotes the AT2 program by recruiting the lung lineage TF NKX2-1. The temporal change in CEBPA-dependent plasticity reflects AT2 cell developmental history. The ontogeny of AT2 cell plasticity and its transcriptional and epigenetic mechanisms have implications in lung regeneration and cancer.

Significance of NKX2-1 as a biomarker for clinical prognosis, immune infiltration, and drug therapy in lung squamous cell carcinoma.

Background: This study was performed to determine the biological processes in which NKX2-1 is involved and thus its role in the development of lung squamous cell carcinoma (LUSC) toward improving the prognosis and treatment of LUSC. Methods: Raw RNA sequencing (RNA-seq) data of LUSC from The Cancer Genome Atlas (TCGA) were used in bioinformatics analysis to characterize NKX2-1 expression levels in tumor and normal tissues. Survival analysis of Kaplan-Meier curve, the time-dependent receiver operating characteristic (ROC) curve, and a nomogram were used to analyze the prognosis value of NKX2-1 for LUSC in terms of overall survival (OS) and progression-free survival (PFS). Then, differentially expressed genes (DEGs) were identified, and Kyoto Encyclopedia of Genes and Genomes (KEGG), Gene Ontology (GO), and Gene Set Enrichment Analysis (GSEA) were used to clarify the biological mechanisms potentially involved in the development of LUSC. Moreover, the correlation between the NKX2-1 expression level and tumor mutation burden (TMB), tumor microenvironment (TME), and immune cell infiltration revealed that NKX2-1 participates in the development of LUSC. Finally, we studied the effects of NKX2-1 on drug therapy. To validate the protein and gene expression levels of NKX2-1 in LUSC, we employed immunohistochemistry(IHC) datasets, The Gene Expression Omnibus (GEO) database, and qRT-PCR analysis. Results: NKX2-1 expression levels were significantly lower in LUSC than in normal lung tissue. It significantly differed in gender, stage and N classification. The survival analysis revealed that high expression of NKX2-1 had shorter OS and PFS in LUSC. The multivariate Cox regression hazard model showed the NKX2-1 expression as an independent prognostic factor. Then, the nomogram predicted LUSC prognosis. There are 51 upregulated DEGs and 49 downregulated DEGs in the NKX2-1 high-level groups. GO, KEGG and GSEA analysis revealed that DEGs were enriched in cell cycle and DNA replication.The TME results show that NKX2-1 expression was positively associated with mast cells resting, neutrophils, monocytes, T cells CD4 memory resting, and M2 macrophages but negatively associated with M1 macrophages. The TMB correlated negatively with NKX2-1 expression. The pharmacotherapy had great sensitivity in the NKX2-1 low-level group, the immunotherapy is no significant difference in the NKX2-1 low-level and high-level groups. The analysis of GEO data demonstrated concurrence with TCGA results. IHC revealed NKX2-1 protein expression in tumor tissues of both LUAD and LUSC. Meanwhile qRT-PCR analysis indicated a significantly lower NKX2-1 expression level in LUSC compared to LUAD. These qRT-PCR findings were consistent with co-expression analysis of NKX2-1. Conclusion: We conclude that NKX2-1 is a potential biomarker for prognosis and treatment LUSC. A new insights of NKX2-1 in LUSC is still needed further research.

A case report of loss of thyroid transcription factor 1 expression in lung adenocarcinoma EBUS FNA.

We present a case report of a 76-year-old male with a histologically confirmed KRAS mutated, thyroid transcription factor 1 (TTF1) positive, grade 1, mucinous adenocarcinoma with cytologically difficult to interpret lymph node metastasis showing loss of TTF1 expression and overlapping features with goblet cell hyperplasia. The case highlights the importance of molecular testing in aiding diagnosis and guiding treatment of non-small cell lung carcinomas (NSCLC).

Diagnostic Value of Immunostaining for Thyroid Transcription Factor 1 (TTF1) and Paired Box 8 (PAX8) in Distinguishing Pulmonary Metastases of Mesonephric and Mesonephric-like Adenocarcinomas from Primary Lung Adenocarcinomas.

BACKGROUND/AIM: Both mesonephric adenocarcinoma (MA) and mesonephric-like adenocarcinoma (MLA) express thyroid transcription factor 1 (TTF1). TTF1 is also considered a highly sensitive and specific diagnostic marker for primary lung adenocarcinoma (PLA). However, distinguishing PLA from pulmonary metastatic MA/MLA (PMM) based on the expression of TTF1 alone can be difficult. This study aimed to investigate the expression of TTF1 and paired box 8 (PAX8) and assess their value in distinguishing PMM from PLA. PATIENTS AND METHODS: We reviewed the electronic medical records and pathology slides of eight PMM cases. We conducted immunostaining for TTF1 and PAX8 in 6, 8, and 21 cases of primary MA/MLA, PMM, and PLA, respectively. RESULTS: Two patients with stage IB uterine MLA developed lung metastases at 5 and 57 months after hysterectomy. Solitary pulmonary nodules were suspected to be primary lung cancer in two patients. Compared to primary tumors, all matched PMMs exhibited reduced TTF1 immunoreactivity. In contrast, the majority of PLAs showed uniform and intense TTF1 expression. All except one PMM exhibited diffuse and strong PAX8 expression, while only one PLA showed focal and weak PAX8 expression. CONCLUSION: Immunostaining for TTF1 and PAX8 can help in distinguishing PMM from PLA in the diagnosis of pulmonary lesions detected in patients with a history of MA/MLA.

NKX2-1 gene is targeted by H19 lncRNA and is found to be overexpressed in benign nodular goiter tissues.

OBJECTIVE: Nodular goiter may increase the risk of thyroid cancer, but the genetic factors contributing to nodular goiter are not well understood. There is an overexpression of H19 lncRNA in goiter tissue and its target remains unknown. In this study, we attempted to identify a new target for H19 in the context of goiter development. METHODS: Using interaction energy calculations, the interaction between NKX2-1 mRNA and H19 lncRNA was examined. Putative microRNAs were found at the H19 lncRNA target site with the highest affinity for NKX2-1. RNAseq data was analyzed to determine the tissue specificity of gene expression. Samples were taken from 18 goiter and 18 normal tissues during thyroidectomy. The expression of NKX2-1 was determined by RT-qPCR using specific primers. RESULTS: The interaction between NKX2-1 and H19 was characterized by six local base-pairing connections, with a maximum energy of -20.56 kcal/moL. Specifically, the sequence that displayed the highest affinity for binding with H19 overlapped with the binding site of has-miR-1827 to NKX2-1. It was found that NKX2-1 is exclusively co-expressed with H19 in normal thyroid tissue. As compared to adjacent normal tissues, nodular goiter tissues have a significant overexpression of NKX2-1 (relative expression = 1.195, p =  0.038). CONCLUSION: NKX2-1 has been identified as the putative target of H19 lncRNA, which is overexpressed in nodular goiter tissues significantly.

Non-small cell lung carcinoma with focal coexpression of thyroid transcription factor-1 and Δ Np63/p40: A case report.

Most lung carcinomas are subtyped by their morphologies; however, immunohistochemistry is usually performed when it is difficult to determine. The most reliable antibodies for distinguishing lung adenocarcinoma from squamous cell carcinoma are thyroid transcription factor-1 (TTF-1) and p40 (ΔNp63). In general, these markers are mutually exclusive in their expression of lung primary carcinoma; however, a few cases of non-small cell lung carcinoma (NSCLC) with coexpression of both markers have been reported. Examining a tissue microarray of 229 squamous cell carcinomas and 346 adenocarcinomas, we found one case of NSCLC with coexpression of TTF-1 and p40. Herein, we present a 71-year-old man, who had a mass lesion in the left lung apex. A transbronchial lung biopsy was performed, revealing NSCLC. He underwent left upper segmentectomy and lymph node dissection. Macroscopically, the mass showed a white-to-tan solid tumor on the cut surface. Microscopically, the tumor was composed of polygonal tumor cells which had round and vesicular nuclei with prominent nucleoli. They had an abundant amount of cytoplasm, which was slightly eosinophilic or amphophilic. Multinucleated cells with atypical nuclear features were observed to be scattered in some areas. Multifocal necrosis and hemorrhage were also noted. Distinct squamous features and obvious glandular features were absent. Immunohistochemically, the most tumor cells were coexpressed positive for both TTF-1 and p40. In our study, NSCLC with TTF-1 and p40 coexpression is rare; therefore, it is necessary to obtain further data and examine similar cases to establish more precise definitions and clinicopathological features.

Thyroid transcription factor-1 expression in lung neuroendocrine tumours: a gender-related biomarker?

PURPOSE: Thyroid transcription factor-1 (TTF-1) assessed by immunohistochemistry (IHC) is a specific biomarker for lung adenocarcinoma, and is commonly used to confirm the pulmonary origin of neuroendocrine tumours (NET). The majority of the available data suggest that TTF-1 is favourable prognostic biomarker for lung adenocarcinomas, whereas its role is more conflicting for lung NET. The main aim of this multicenter retrospective study was to investigate the potentially relevant associations between TTF-1 biomarker and clinical and pathological features of the study population, as well as determine TTF-1 prognostic effect on the clinical outcome of the patients. METHODS: A multicentre retrospective study was conducted on 155 surgically-removed lung NET, with available IHC TTF-1 assessment. RESULTS: Median age was 59.5 years (range 13-86), 97 patients (62.6%) were females, 31 cases (20%) were atypical carcinoids, 4 (2.6%) had TNM stage IV. Mitotic count ≥2 per 10 high-power field was found in 35 (22.6%) subjects, whereas necrosis was detected in 20 patients (12.9%). TTF-1 was positive in 78 cases (50.3%). The median overall survival was 46.9 months (range 0.6-323) and the median progression-free survival was 39.1 months (range 0.6-323). Statistically significant associations were found between (1) TTF-1 positivity and female sex (p = 0.007); and among (2) TTF-1 positivity and the absence of necrosis (p = 0.018). CONCLUSIONS: This study highlights that TTF-1 positivity differs according to sex in lung NET, with a more common TTF-1 positive staining in female. Moreover, TTF-1 positivity correlated with the absence of necrosis. These data suggest that TTF-1 could potentially represent a gender-related biomarker for lung NET.

Canine follicular cell and medullary thyroid carcinomas: Immunohistochemical characterization.

Research on modulation of iodine uptake by thyroid cells could help improve radioiodine treatment of dogs with thyroid tumors. The aim of this study was to characterize the immunohistochemical expression of thyroid transcription factor-1 (TTF-1), thyroglobulin, thyrotropin receptor (TSHR), sodium iodide symporter (NIS), pendrin, thyroid peroxidase (TPO), vimentin, and Ki-67 in follicular cell thyroid carcinomas (FTCs) and medullary thyroid carcinomas (MTCs), and to compare protein expression between FTC causing hyperthyroidism and FTC of euthyroid dogs. Immunohistochemistry was performed in 25 FTCs (9 follicular, 8 follicular-compact, and 8 compact) and 8 MTCs. FTCs and MTCs were positive for TTF-1, and expression was higher in FTCs of euthyroid dogs compared with FTCs of hyperthyroid dogs (P= .041). Immunolabeling for thyroglobulin was higher in follicular and follicular-compact FTCs compared with compact FTCs (P = .001), while vimentin expression was higher in follicular-compact FTCs compared with follicular FTCs (P = .011). The expression of TSHR, NIS, pendrin, and TPO was not significantly different among the different subtypes of FTCs or between FTCs causing hyperthyroidism and FTCs in euthyroid dogs. TSHR, NIS, pendrin, and TPO were also expressed in MTCs. Ki-67 labeling index was comparable between FTCs and MTCs, and between FTCs causing hyperthyroidism and FTCs in euthyroid dogs. Proteins of iodine transport were also expressed in canine MTCs, which could have implications for diagnosis and treatment. The different expression of thyroglobulin and vimentin between FTC histological subtypes could reflect variations in tumor differentiation.

Regulatory effect of NK homeobox 1 (NKX2.1) on melanocortin 4 receptor (Mc4r) promoter in Mandarin fish.

The melanocortin 4 receptor (MC4R) is a G protein-coupled transporter that mediates the regulation of thyroid hormones and leptin on energy balance and food intake. However, the mechanisms of transcriptional regulation of Mc4r by thyroid hormone and leptin in fish have been rarely reported. The messenger RNA expression of Mc4r gene was significantly higher in brain than those in other tissues of mandarin fish. We analyzed the structure and function of a 2029 bp sequence of Mc4r promoter. Meanwhile, overexpression of NKX2.1 and incubation with leptin significantly increased Mc4r promoter activity, but triiodothyronine showed the opposite effect. In addition, mutations in the NKX2.1 binding site abolished not only the activation of Mc4r promoter activity by leptin but also the inhibitory effect of thyroid hormones on Mc4r promoter activity. In summary, these results suggested that thyroid hormones and leptin might regulate the transcriptional expression of Mc4r through NKX2.1.

Transcription factor NKX2-1 drives serine and glycine synthesis addiction in cancer.

BACKGROUND: One-third of cancers activate endogenous synthesis of serine/glycine, and can become addicted to this pathway to sustain proliferation and survival. Mechanisms driving this metabolic rewiring remain largely unknown. METHODS: NKX2-1 overexpressing and NKX2-1 knockdown/knockout T-cell leukaemia and lung cancer cell line models were established to study metabolic rewiring using ChIP-qPCR, immunoblotting, mass spectrometry, and proliferation and invasion assays. Findings and therapeutic relevance were validated in mouse models and confirmed in patient datasets. RESULTS: Exploring T-cell leukaemia, lung cancer and neuroendocrine prostate cancer patient datasets highlighted the transcription factor NKX2-1 as putative driver of serine/glycine metabolism. We demonstrate that transcription factor NKX2-1 binds and transcriptionally upregulates serine/glycine synthesis enzyme genes, enabling NKX2-1 expressing cells to proliferate and invade in serine/glycine-depleted conditions. NKX2-1 driven serine/glycine synthesis generates nucleotides and redox molecules, and is associated with an altered cellular lipidome and methylome. Accordingly, NKX2-1 tumour-bearing mice display enhanced tumour aggressiveness associated with systemic metabolic rewiring. Therapeutically, NKX2-1-expressing cancer cells are more sensitive to serine/glycine conversion inhibition by repurposed anti-depressant sertraline, and to etoposide chemotherapy. CONCLUSION: Collectively, we identify NKX2-1 as a novel transcriptional regulator of serine/glycine synthesis addiction across cancers, revealing a therapeutic vulnerability of NKX2-1-driven cancers. Transcription factor NKX2-1 fuels cancer cell proliferation and survival by hyperactivating serine/glycine synthesis, highlighting this pathway as a novel therapeutic target in NKX2-1-positive cancers.

Hypothalamic TTF-1 orchestrates the sensitivity of leptin.

OBJECTIVE: Thyroid transcription factor-1 (TTF-1), a homeodomain-containing transcription factor, is predominantly expressed in discrete areas of the hypothalamus, which acts as the central unit for the regulation of whole-body energy homeostasis. Current study designed to identify the roles of TTF-1 on the responsiveness of the hypothalamic circuit activity to circulating leptin and the development of obesity linked to the insensitivity of leptin. METHODS: We generated conditional knock-out mice by crossing TTF-1flox/flox mice with leptin receptor (ObRb)Cre or proopiomelanocortin (POMC)Cre transgenic mice to interrogate the contributions of TTF-1 in leptin signaling and activity. Changes of food intake, body weight and energy expenditure were evaluated in standard or high fat diet-treated transgenic mice by using an indirect calorimetry instrument. Molecular mechanism was elucidated with immunohistochemistry, immunoblotting, quantitative PCR, and promoter assays. RESULTS: The selective deletion of TTF-1 gene expression in cells expressing the ObRb or POMC enhanced the anorexigenic effects of leptin as well as the leptin-induced phosphorylation of STAT3. We further determined that TTF-1 inhibited the transcriptional activity of the ObRb gene. In line with these findings, the selective deletion of the TTF-1 gene in ObRb-positive cells led to protective effects against diet-induced obesity via the amelioration of leptin resistance. CONCLUSIONS: Collectively, these results suggest that hypothalamic TTF-1 participates in the development of obesity as a molecular component involved in the regulation of cellular leptin signaling and activity. Thus, TTF-1 may represent a therapeutic target for the treatment, prevention, and control of obesity.

Stable iPSC-derived NKX2-1+ lung bud tip progenitor organoids give rise to airway and alveolar cell types.

Bud tip progenitors (BTPs) in the developing lung give rise to all epithelial cell types found in the airways and alveoli. This work aimed to develop an iPSC organoid model enriched with NKX2-1+ BTP-like cells. Building on previous studies, we optimized a directed differentiation paradigm to generate spheroids with more robust NKX2-1 expression. Spheroids were expanded into organoids that possessed NKX2-1+/CPM+ BTP-like cells, which increased in number over time. Single cell RNA-sequencing analysis revealed a high degree of transcriptional similarity between induced BTPs (iBTPs) and in vivo BTPs. Using FACS, iBTPs were purified and expanded as induced bud tip progenitor organoids (iBTOs), which maintained an enriched population of bud tip progenitors. When iBTOs were directed to differentiate into airway or alveolar cell types using well-established methods, they gave rise to organoids composed of organized airway or alveolar epithelium, respectively. Collectively, iBTOs are transcriptionally and functionally similar to in vivo BTPs, providing an important model for studying human lung development and differentiation.

Sox9 is involved in the thyroid differentiation program and is regulated by crosstalk between TSH, TGFß and thyroid transcription factors.

While the signaling pathways and transcription factors involved in the differentiation of thyroid follicular cells, both in embryonic and adult life, are increasingly well understood, the underlying mechanisms and potential crosstalk between the thyroid transcription factors Nkx2.1, Foxe1 and Pax8 and inductive signals remain unclear. Here, we focused on the transcription factor Sox9, which is expressed in Nkx2.1-positive embryonic thyroid precursor cells and is maintained from embryonic development to adulthood, but its function and control are unknown. We show that two of the main signals regulating thyroid differentiation, TSH and TGFß, modulate Sox9 expression. Specifically, TSH stimulates the cAMP/PKA pathway to transcriptionally upregulate Sox9 mRNA and protein expression, a mechanism that is mediated by the binding of CREB to a CRE site within the Sox9 promoter. Contrastingly, TGFß signals through Smad proteins to inhibit TSH-induced Sox9 transcription. Our data also reveal that Sox9 transcription is regulated by the thyroid transcription factors, particularly Pax8. Interestingly, Sox9 significantly increased the transcriptional activation of Pax8 and Foxe1 promoters and, consequently, their expression, but had no effect on Nkx2.1. Our study establishes the involvement of Sox9 in thyroid follicular cell differentiation and broadens our understanding of transcription factor regulation of thyroid function.

Dabrafenib monotherapy for a recurrent BRAFV600E-mutated TTF-1-positive posterior pituitary tumor.

Posterior pituitary tumors (PPT) expressing thyroid transcription factor-1 (TTF-1) are extremely rare low-grade neoplasms. The recent discovery of BRAF mutations in these tumors offers a potential alternative treatment using targeted therapies. We present the case of a 57-year-old female with recurrent BRAFV600E-mutated TTF-1-positive PPT treated with a BRAF inhibitor monotherapy (dabrafenib) leading to tumor regression. After 18 months of uninterrupted treatment, ongoing radiological tumor regression was observed and the patient remained asymptomatic without any significant adverse event. BRAF inhibitor is potentially a valuable treatment option for recurrent TTF-1-positive PPT with BRAF mutation.

NKX2-1 controls lung cancer progression by inducing DUSP6 to dampen ERK activity.

The RAS→RAF→MEK→ERK pathway is hyperactivated in the majority of human lung adenocarcinoma (LUAD). However, the initial activating mutations induce homeostatic feedback mechanisms that limit ERK activity. How ERK activation reaches the tumor-promoting levels that overcome the feedback and drive malignant progression is unclear. We show here that the lung lineage transcription factor NKX2-1 suppresses ERK activity. In human tissue samples and cell lines, xenografts, and genetic mouse models, NKX2-1 induces the ERK phosphatase DUSP6, which inactivates ERK. In tumor cells from late-stage LUAD with silenced NKX2-1, re-introduction of NKX2-1 induces DUSP6 and inhibits tumor growth and metastasis. We show that DUSP6 is necessary for NKX2-1-mediated inhibition of tumor progression in vivo and that DUSP6 expression is sufficient to inhibit RAS-driven LUAD. Our results indicate that NKX2-1 silencing, and thereby DUSP6 downregulation, is a mechanism by which early LUAD can unleash ERK hyperactivation for tumor progression.

Analysis of Islet-1, Nkx2.1, Pax6, and Orthopedia in the forebrain of the sturgeon Acipenser ruthenus identifies conserved prosomeric characteristics.

The distribution patterns of a set of conserved brain developmental regulatory transcription factors were analyzed in the forebrain of the basal actinopterygian fish Acipenser ruthenus, consistent with the prosomeric model. In the telencephalon, the pallium was characterized by ventricular expression of Pax6. In the subpallium, the combined expression of Nkx2.1/Islet-1 (Isl1) allowed to propose ventral and dorsal areas, as the septo-pallidal (Nkx2.1/Isl1+) and striatal derivatives (Isl1+), respectively, and a dorsal portion of the striatal derivatives, ventricularly rich in Pax6 and devoid of Isl1 expression. Dispersed Orthopedia (Otp) cells were found in the supracommissural and posterior nuclei of the ventral telencephalon, related to the medial portion of the amygdaloid complex. The preoptic area was identified by the Nkx2.1/Isl1 expression. In the alar hypothalamus, an Otp-expressing territory, lacking Nkx2.1/Isl1, was identified as the paraventricular domain. The adjacent subparaventricular domain (Spa) was subdivided in a rostral territory expressing Nkx2.1 and an Isl1+ caudal one. In the basal hypothalamus, the tuberal region was defined by the Nkx2.1/Isl1 expression and a rostral Otp-expressing domain was identified. Moreover, the Otp/Nkx2.1 combination showed an additional zone lacking Isl1, tentatively identified as the mamillary area. In the diencephalon, both Pax6 and Isl1 defined the prethalamic domain, and within the basal prosomere 3, scattered Pax6- and Isl1-expressing cells were observed in the posterior tubercle. Finally, a small group of Pax6 cells was observed in the pretectal area. These results improve the understanding of the forebrain evolution and demonstrate that its basic bauplan is present very early in the vertebrate lineage.