HIF-1 inactivation empowers HIF-2 to drive hypoxia adaptation in aggressive forms of medulloblastoma.

Medulloblastoma (MB) is the most prevalent brain cancer in children. Four subgroups of MB have been identified; of these, Group 3 is the most metastatic. Its genetics and biology remain less clear than the other groups, and it has a poor prognosis and few effective treatments available. Tumor hypoxia and the resulting metabolism are known to be important in the growth and survival of tumors but, to date, have been only minimally explored in MB. Here we show that Group 3 MB tumors do not depend on the canonical transcription factor hypoxia-inducible factor-1α (HIF-1α) to mount an adaptive response to hypoxia. We discovered that HIF-1α is rendered inactive either through post-translational methylation, preventing its nuclear localization specifically in Group 3 MB, or by a low expression that prevents modulation of HIF-target genes. Strikingly, we found that HIF-2 takes over the role of HIF-1 in the nucleus and promotes the activation of hypoxia-dependent anabolic pathways. The exclusion of HIF-1 from the nucleus in Group 3 MB cells enhances the reliance on HIF-2's transcriptional role, making it a viable target for potential anticancer strategies. By combining pharmacological inhibition of HIF-2α with the use of metformin, a mitochondrial complex I inhibitor to block respiration, we effectively induced Group 3 MB cell death, surpassing the effectiveness observed in Non-Group 3 MB cells. Overall, the unique dependence of MB cells, but not normal cells, on HIF-2-mediated anabolic metabolism presents an appealing therapeutic opportunity for treating Group 3 MB patients with minimal toxicity.

The mitochondrial NADH shuttle system is a targetable vulnerability for Group 3 medulloblastoma in a hypoxic microenvironment.

Medulloblastoma is a cancerous brain tumor that affects mostly children. Among the four groups defined by molecular characteristics, Group 3, the least well characterized, is also the least favorable, with a survival rate of 50%. Current treatments, based on surgery, radiotherapy, and chemotherapy, are not adequate and the lack of understanding of the different molecular features of Group 3 tumor cells makes the development of effective therapies challenging. In this study, the problem of medulloblastoma is approached from a metabolic standpoint in a low oxygen microenvironment. We establish that Group 3 cells use both the mitochondrial glycerol-3 phosphate (G3PS) and malate-aspartate shuttles (MAS) to produce NADH. Small molecules that target G3PS and MAS show a greater ability to decrease cell proliferation and induce apoptosis specifically of Group 3 cells. In addition, as Group 3 cells show improved respiration in hypoxia, the use of Phenformin, a mitochondrial complex 1 inhibitor, alone or in combination, induced significant cell death. Furthermore, inhibition of the cytosolic NAD+ recycling enzyme lactate dehydrogenase A (LDHA), enhanced the effects of the NADH shuttle inhibitors. In a 3D model using Group 3 human cerebellar organoids, tumor cells also underwent apoptosis upon treatment with NADH shuttle inhibitors. Our study demonstrates metabolic heterogeneity depending on oxygen concentrations and provides potential therapeutic solutions for patients in Group 3 whose tumors are the most aggressive.

HIF-1 inactivation empowers HIF-2 to drive hypoxia adaptation in aggressive forms of medulloblastoma.

Medulloblastoma (MB) is the most prevalent brain cancer in children. Four subgroups of MB have been identified; of these, Group 3 is the most metastatic. Its genetics and biology remain less clear than the other groups, and it has a poor prognosis and few effective treatments available. Tumor hypoxia and the resulting metabolism are known to be important in the growth and survival of tumors but, to date, have been only minimally explored in MB. Here we show that Group 3 MB tumors do not depend on the canonical transcription factor hypoxia-inducible factor-1α (HIF-1α) to mount an adaptive response to hypoxia. We discovered that HIF-1α is rendered inactive either through post-translational methylation, preventing its nuclear localization specifically in Group 3 MB, or by a low expression that prevents modulation of HIF-target genes. Strikingly, we found that HIF-2 takes over the role of HIF-1 in the nucleus and promotes the activation of hypoxia-dependent anabolic pathways. The exclusion of HIF-1 from the nucleus in Group 3 MB cells enhances the reliance on HIF-2's transcriptional role, making it a viable target for potential anticancer strategies. By combining pharmacological inhibition of HIF-2α with the use of metformin, a mitochondrial complex I inhibitor to block respiration, we effectively induced Group 3 MB cell death, surpassing the effectiveness observed in Non-Group 3 MB cells. Overall, the unique dependence of MB cells, but not normal cells, on HIF-2-mediated anabolic metabolism presents an appealing therapeutic opportunity for treating Group 3 MB patients with minimal toxicity.

Head and neck cancer associated with myiasis.

Head and neck cancer patients represent a risk group for the development of fly larvae infestation in neoplastic wounds. This condition can accelerate the disease progression and increase its lethality due to local or systemic complications. The aim of this study was to conduct a scoping review on head and neck cancer associated with myiasis in order to answer the focal question: what are the occurrence, diagnosis, aetiology, treatment and outcomes of head and neck cancer associated with myiasis? This paper was structured based on the five-steps methodology proposed by Arksey and O'Malley (Int J Soc Res Methodol 2005;1:19-32), and followed the PRISMA Extension for Scoping Reviews (PRISMA-ScR), OSF Registries protocol. The electronic search was performed in the MEDLINE/PubMed, Embase and SciELO.org databases for articles published up to 28 February 2021. In total, 38 articles and 56 patients were included. Most patients were male (66%), and the mean age was 66.63 years. Cases were predominantly associated with squamous or basal cell cancer. The most affected anatomical sites were the eyes, scalp, ears and oral cavity, and the most frequent type of larva was Crisomyia (13%). Manual removal of the larvae was considered the standard treatment, associated or not with antibiotics, analgesics and antiparasitic drugs.

[Folic acid: Primary prevention of neural tube defects. Literature Review]. / Ácido fólico: prevención primaria de los defectos del tubo neural. Revisión bibliográfica.

Neural tube defects (NTD) are the most common congenital malformations of the nervous system, they have a multifactorial etiology, are caused by exposure to chemical, physical or biological toxic agents, factors deficiency, diabetes, obesity, hyperthermia, genetic alterations and unknown causes. Some of these factors are associated with malnutrition by interfering with the folic acid metabolic pathway, the vitamin responsible for neural tube closure. Its deficit produce anomalies that can cause abortions, stillbirths or newborn serious injuries that cause disability, impaired quality of life and require expensive treatments to try to alleviate in some way the alterations produced in the embryo. Folic acid deficiency is considered the ultimate cause of the production of neural tube defects, it is clear the reduction in the incidence of Espina Bifida after administration of folic acid before conception, this leads us to want to further study the action of folic acid and its application in the primary prevention of neural tube defects. More than 40 countries have made the fortification of flour with folate, achieving encouraging data of decrease in the prevalence of neural tube defects. This paper attempts to make a literature review, which clarify the current situation and future of the prevention of neural tube defects.

Development and psychometric validation of a brief comprehensive health status assessment scale in older patients with hematological malignancies: The GAH Scale.

OBJECTIVES: The purpose of this study was to develop a new brief, comprehensive geriatric assessment scale for older patients diagnosed with different hematological malignancies, the Geriatric Assessment in Hematology (GAH scale), and to determine its psychometric properties. MATERIALS AND METHODS: The 30-item GAH scale was designed through a multi-step process to cover 8 relevant dimensions. This is an observational study conducted in 363 patients aged≥65years, newly diagnosed with different hematological malignancies (myelodysplasic syndrome/acute myeloblastic leukemia, multiple myeloma, or chronic lymphocytic leukemia), and treatment-naïve. The scale psychometric validation process included the analyses of feasibility, floor and ceiling effect, validity and reliability criteria. RESULTS: Mean time taken to complete the GAH scale was 11.9±4.7min that improved through a learning-curve effect. Almost 90% of patients completed all items, and no floor or ceiling effects were identified. Criterion validity was supported by reasonable correlations between the GAH scale dimensions and three contrast variables (global health visual analogue scale, ECOG and Karnofsky), except for comorbidities. Factor analysis (supported by the scree plot) revealed nine factors that explained almost 60% of the total variance. Moderate internal consistency reliability was found (Cronbach's α: 0.610), and test-retest was excellent (ICC coefficients, 0.695-0.928). CONCLUSION: Our study suggests that the GAH scale is a valid, internally reliable and a consistent tool to assess health status in older patients with different hematological malignancies. Future large studies should confirm whether the GAH scale may be a tool to improve clinical decision-making in older patients with hematological malignancies.

Mitochondrial respiratory uncoupling promotes keratinocyte differentiation and blocks skin carcinogenesis.

Decreased mitochondrial oxidative metabolism is a hallmark bioenergetic characteristic of malignancy that may have an adaptive role in carcinogenesis. By stimulating proton leak, mitochondrial uncoupling proteins (UCP1-3) increase mitochondrial respiration and may thereby oppose cancer development. To test this idea, we generated a mouse model that expresses an epidermal-targeted keratin-5-UCP3 (K5-UCP3) transgene and exhibits significantly increased cutaneous mitochondrial respiration compared with wild type (FVB/N). Remarkably, we observed that mitochondrial uncoupling drove keratinocyte/epidermal differentiation both in vitro and in vivo. This increase in epidermal differentiation corresponded to the loss of markers of the quiescent bulge stem cell population, and an increase in epidermal turnover measured using a bromodeoxyuridine (BrdU)-based transit assay. Interestingly, these changes in K5-UCP3 skin were associated with a nearly complete resistance to chemically-mediated multistage skin carcinogenesis. These data suggest that targeting mitochondrial respiration is a promising novel avenue for cancer prevention and treatment.

Darbepoetin alfa for anemia in patients with low or intermediate-1 risk myelodysplastic syndromes and positive predictive factors of response.

BACKGROUND: Current guidelines support the use of erythropoiesis-stimulating agents for the treatment of anemia associated with low-risk myelodysplastic syndromes (MDS). DESIGN AND METHODS: Single-arm, open-label, multi-center, phase 2 trial that evaluated the efficacy and safety of darbepoetin alfa (DA) in patients with low or intermediate-risk MDS, hemoglobin <100 g/L, erythropoietin (EPO) levels <500 IU/L and transfusion requirements <2 units/month over the preceding 2 months. Erythroid response (major [MaR] or minor [MiR]) and fatigue (Functional Assessment of Cancer Therapy-Fatigue [FACT-F]) were evaluated at 8, 16 and 24 weeks. DA was initiated at 300 µg weekly. For patients who did not achieve MaR by 8 weeks, filgrastim 300 µg weekly was added. CLINICAL TRIAL REGISTRATION: clinicaltrials.gov identifier: NCT01039350. RESULTS: Forty-four patients (72.7% transfusion independent) were included. Median age was 76.0 years (range 41.3-92.4), 54.5% were male, and 90.9% presented ECOG Status (0-1). Eighteen patients received filgrastim. An erythroid response was achieved by 31 of 44 patients (70.5%) at week 8 (47.7% MaR, 22.7% MiR), 31 of 44 patients (70.5%) at week 16 (61.4% MaR, 9.1% MiR), and 32 of 44 patients (72.7%) at week 24 (61.3% MaR, 11.4% MiR). Mean (95% CI) change in FACT-F at week 24 was 3.61 (0.72 to 6.51). Baseline EPO levels <100 IU/L were a predictive factor of response. DA was well tolerated. Four mild (two iron deficiencies, flu syndrome and headache) and one fatal (thromboembolic event) adverse events were considered related to darbepoetin alfa. CONCLUSIONS: A fixed dose of 300 µg of darbepoetin alfa weekly (with or without filgrastim) seems to be an effective and safe treatment for anemic patients with low or intermediate-risk MDS, low transfusion burden and EPO levels <500 IU/L. Results may not be extrapolable to unselected MDS patients.

Inhibition of IAPP and IAPP(20-29) fibrillation by polymeric nanoparticles.

The fibrillation process of the islet amyloid polypeptide (IAPP) and its fragment (IAPP(20-29)) was studied by means of Thioflavin T (ThT) fluorescence and transmission electron microscopy in the absence and presence of N-isopropylacrylamide:N-tert-butylacrylamide (NiPAM:BAM) copolymeric nanoparticles. The process was found to be strongly affected by the presence of the nanoparticles, which retard protein fibrillation as a function of the chemical surface properties of the nanoparticles. The NiPAM:BAM ratio was varied from 50:50 to 100:0. The nanoparticles with higher fraction of NiPAM imposed the strongest retardation of IAPP and IAPP(20-29) fibrillation. These particles have the strongest hydrogen bonding capacity due to the less bulky N-isopropyl group and thus less steric hindrance of the hydrogen-bonding groups of the nanoparticle polymer backbone. Kinetic fibrillation data, as monitored by ThT fluorescence and supported by surface plasmon resonance experiments, suggest that the peptide is strongly absorbed onto the surface of the nanoparticles. This interaction reduces the concentration of peptide free in solution available to proceed to fibrillation which results in an increased lag time of fibrillation, observed as a delayed onset of ThT fluorescence increase, plus a reduction of the amount of fibrils formed as indicated by the equilibrium values at the end of the fibrillation reaction. For the fragment (IAPP(20-29)), the presence of nanoparticles changes the mechanism of association from monomers to fibrils, by interfering with early oligomeric species along the fibrillation pathway.

[Antegrade colonic enemas for intractable constipation in non-mentally retarded children]. / Lavados colónicos anterógrados para el estreñimiento refractario en niños sin encefalopatía.

A descriptive review of 12 patients who underwent appendicocecostomy or caecostomy for antegrade colonic lavage from January 2002 to February 2008. There were 9 appendicocecostomies performed patients from 3 to 13 years suffering from myelomeningocele, of which 8 of them had a very good outcome, with one case withdrawn due to poor use by the family. Three caecostomies were performed in non-mentally retarded constipated children. One was an otherwise healthy 7 year-old boy with hard stools since he was 10 months old, in spite of multiple laxative treatments, with normal morphology and function. He had a percutaneous caecostomy five years ago, with some improvement and a good quality of life, but still some occasional partial impactions. Another healthy 12 year-old boy with daily constipation associated faecal incontinence since he was 3 years old (normal manometry and rectal biopsy with signs of mild neuronal dysplasia) had a percutaneous caecostomy performed three years ago, with improvement in the faecal incontinence and better psychological outcome. The last caecostomy patient was an 8-year-old boy, with a similar clinical history and good progress in last three years after placing a Chait's button using an endoscopic procedure. Stubborn constipation continuing into adult life has a negative impact on the social and emotional adaptation of the paediatric patient, affecting family interactions. Antegrade colonic lavage allows independence and improves the quality of life in patients affected by recurrent faecal impactions. This technique needs to be performed on more patients to find out its true effectiveness.

Italian neuropsychological instruments to assess memory, attention and frontal functions for developmental age.

In this study, a series of tests exploring long-term verbal memory (the Short Story Test), attention (a modified version of Attentional Matrices and the Trail Making Test) and frontal functions (a modified version of the Frontal Assessment Battery) have been standardised on an Italian population of 283 children aged 5-14. Raw scores for each test have been adjusted for a series of variables (child's age, years of parents' education, handedness, gender) and transformed in equivalent scores enabling direct comparison across measures. This study was promoted by LICE (the Italian League Against Epilepsy) in order to provide Italian instruments standardised on the developmental age population and to study some of the most frequently impaired cognitive functions in epilepsy.

[Spontaneous urinary bladder perforation after pediatric cystoplasty]. / Perforación vesical espontánea tras cistoplastia en la infancia.

OBJECTIVE: The spontaneous cystoplasty perforation is a serious and potentially fatal problem if a delay in diagnosis and treatment occurs. We pretend: 1) to look for prevention analyzing the risk factors, 2) to identify the main data of diagnostic suspicion and 3) to evaluate the result of the treatments done. MATERIAL AND METHODS: Out of 30 children with cystoplasty 5 of them have presented 8 perforations (16,6%). Several influential factors, the symptoms, the treatments and the evolution are reviewed. RESULTS: The average time between cystoplasty and the perforation was 8,2 years. A urethral resistance that allows continence, and an insufficient intermittent catheterization, have been the main risk factors. In the 8 episodes there were abdominal pain and distension. The ultrasonography showed intraperitoneal extravasation in 5 episodes, multiple peritoneal cysts in one, and suggestive image of appendicular plastron in another one. The cystography showed intraperitoneal extravasation only in 3 cases. The initial management was conservative in the 7 episodes diagnosed before surgery, and 3 had a good evolution (42,8%); the other 4 needed surgery with good evolution in all cases. Two of 5 patients (40%) presented 3 relapses in an average time of 5 years. The survival is 100%. CONCLUSIONS: 16,6% of patients with cystoplasty of this series had one or more episodes of spontaneous bladder perforation. The more significant risk factors are a high urethral resistance and an inadequate intermittent catheterization. The patients with cystoplasty, and their families, must know this complication, their risk factors and symptoms to prevent it, or to facilitate an early diagnosis.

[New indications for erythropoietin in clinical practice]. / Nuevas indicaciones de la eritropoyetina en la práctica clínica.

The utilization of rHuEp changed definitively the treatment and the natural history of anemia in patients with chronic renal insufficiency (CRI), and now is modifying the treatment of anemia of other non-renal patients as anemia of premature, anemia in onco-hematological illnesses, anemia in human immunodeficiency virus (HIV) infection, and for reduction of allogenic blood transfusions in surgery. We analyze briefly the clinical indications of rHuEpo and the possible complications secondary to its use.

Structure-function analysis of the EGF-CFC family member Cripto identifies residues essential for nodal signalling.

Cripto is the founding member of the family of EGF-CFC genes, a class of extracellular factors essential for early vertebrate development. In this study we show that injection of Cripto recombinant protein in mid to late zebrafish Maternal-Zygotic one-eyed pinhead (MZoep) blastulae was able to fully rescue the mutant phenotype, thus providing the first direct evidence that Cripto activity can be added extracellularly to recover oep-encoded function in zebrafish early embryos. Moreover, 15 point mutations and two deletion mutants were generated to assess in vivo their functional relevance by comparing the ability of cripto wild-type and mutant RNAs to rescue the zebrafish MZoep mutant. From this study we concluded that the EGF-CFC domain is sufficient for Cripto biological activity and identified ten point mutations with a functional defective phenotype, two of which, located in the EGF-like domain, correspond to loss-of-function mutations. Finally, we have developed a three-dimensional structural model of Cripto protein and used it as a guide to predict amino acid residues potentially implicated in protein-protein interaction.

A truncated form of teratocarcinoma-derived growth factor-1 (cripto-1) mRNA expressed in human colon carcinoma cell lines and tumors.

The human teratocarcinoma-derived growth factor (TDGF)-1 gene encodes a 188-amino acid protein, cripto-1. The TDGF-1 gene is overexpressed in the majority of human primary colorectal carcinomas and hepatic metastases, in breast carcinomas and in testicular nonseminoma germ cell embryonal carcinomas. In the human embryonal carcinoma cell line NTERA-2 clone D1, a 2-kb TDGF-1 mRNA transcript is expressed. The present study shows that a 1.7-kb mRNA transcript lacking the first two exons of the TDGF-1 gene is expressed in the human colon carcinoma cell line GEO. This shorter mRNA is the only TDGF-1 transcript that is present in the majority of primary human colorectal carcinomas and hepatic metastases and in adult human tissues such as the pancreas, heart, stomach, mammary gland, skeletal muscle, liver and placenta. In contrast, in the kidney, brain, testis, ovary and spleen, the longer 2-kb TDGF-1 mRNA transcript is expressed. The putative shorter protein starts at a CUG codon 129 nucleotides downstream of the starting AUG codon of the longer protein. These data indicate the potential for differential transcriptional regulation of the TDGF-1 gene in different normal and tumor tissues.

Membrane-anchorage of Cripto protein by glycosylphosphatidylinositol and its distribution during early mouse development.

cripto is the original member of the family of EGF-CFC genes, recently recognized as novel extracellular factors essential for vertebrate development. During the early stages of mouse gastrulation, cripto mRNA is detected in mesodermal cells; later, cripto mRNA is detected only in the truncus arteriosus of the developing heart. Here we describe the in vivo distribution of Cripto protein throughout mouse embryo development and show that cripto mRNA and protein colocalize. By means of immunofluorescence analysis and biochemical characterization, we show that Cripto is a membrane-bound protein anchored to the lipid bilayer by a glycosylphosphatidylinositol (GPI) moiety. We suggest that presentation of Cripto on the cell surface via a GPI-linkage is important in determining the spatial specificity of cell-cell interactions that play a critical role in the early patterning of the embryo.

[Long-term follow-up of children with neurogenic bladder and artificial urinary sphincter]. / Resultado a largo plazo del esfínter urinario artificial en niños con vejiga neurógena. A propósito de 16 casos en 12 años.

MATERIALS AND METHODS: Since 1986 an artificial urinary sphincter was implanted in 16 children (13 males and 3 females) 4 to 12 years old (median age 9) in order to solve their urinary incontinence. Mean age at implantation was 9 years. In 10 children (63%) only the implant procedure of artificial sphincter was performed without any other procedure associated (Group A), while in 6 children an augmentation cystoplasty simultaneously was performed (Group B). The results were analysed in both groups separately: 1. Group A: 10 patients. Two are functioning excellently after 10 and 11 years of follow up. Eight developed some type of troublesome: Five developed a deterioration of urinary tract and all of five were treated by augmentation cystoplasty; one of them is in a good condition after 11 years, another presented a fail of the device after 10 years, it has been changed, and in the others three the apparatus was removed by diverse causes. Two developed a mechanical fail of device: one was removed due familiar decision and the other has received another device. One urinary fistula developed 6 months later. The device was removed. 2. Group B: 6 patients (artificial sphincter and augmentation cystoplasty simultaneously). Five are functioning without trouble some. One persistent urinary fistula. The device was removed. Actually, of 16 cases (both groups) 8 cases (50%) are good functioning, 6 devices have been removed and 2 are waiting a new implant. CONCLUSIONS: The artificial urinary sphincter is a good solution for children with urinary incontinence in selected cases, but is mandatory a correct follow up because longterm complications can be developed. Results seem better when an augmentation cystoplasty is associated.

Assignment of human teratocarcinoma derived growth factor (TDGF) sequences to chromosomes 2q37, 3q22, 6p25 and 19q13.1.

The human teratocarcinoma derived growth factor 1 (TDGF1) gene maps on chromosome (Chr) 3p21.3. One pseudogene (TDGF3) maps on Chr Xq21-->q22. We now report the nucleotide sequence and chromosome location of three additional TDGF pseudogenes. The three new sequences (TDGF2, TDGF4 and TDGF5) are truncated at the 5' end and have accumulated several point mutations, deletions and insertions. TDGF2, TDGF4 and TDGF6 map on Chrs 2q37, 6p25 and 3q22, respectively. Finally, Southern blot analysis of DNA from normal individuals shows a highly variable restriction pattern of the TDGF sequences.

[Intermittent catheterization as the basis for treatment of neurogenic bladder during childhood]. / El sondaje intermitente como base del tratamiento de la vejiga neurógena durante la infancia.

OBJECTIVE: Neurogenic bladder (NB) frequently causes incomplete bladder emptying, which can lead to deterioration of the upper urinary tract (UUT), vesico-renal reflux (VRR) and incontinence. The aim of this study is to determine the degree of acceptance, performance and results of treatment of NB in children by intermittent catheterization (IC). METHODS: Of 121 children (50 girls and 38 boys) with NB, 88 were managed by intermittent catheterization. The mean age at treatment was 5.2 years (range 20 days-13 years). PVC catheters were employed and reutilized for 3 or 4 weeks. Catheters were aseptic but not sterile. Antimicrobial prophylactic therapy was not administered except in patients with VRR. The statistical study was descriptive and results were compared using the Pearson chi square test. RESULTS: 90% had 4 or more catheterizations daily. Family and patient cooperation was good in 90% of the cases. Patients were managed by IC for a mean period of 4 years (range 1 month-14 years). Only two cases (2%) showed mild, transient complications (urethral pain and cystitis). Normal UUT remained normal in 85%; 45% with compromised UUT improved and 7% became worse. Of the children with no VRR, 94% did not develop this complication; VRR resolved in 72% of the cases (24% by IC alone and 48% with drugs or surgery). Only 12% were continent for more than 3 hours, which increased to 77% (64% by IC alone and 86% with drug therapy or surgery). Urethral sphincter urodynamics was the most important prognostic factor: patients with a lower urethral resistance showed better results for the UUT (p = 0.00373) and VRR (p = 0.00943). The results were also better in patients with normal UUT (p = 0.0003) and no VRR (p = 0.009). CONCLUSIONS: IC is not limited by patient age, sex or sociocultural level. It preserves normal TUS and prevents VRR when instituted early, on demonstrating residual urine and high urethral resistance. IC alone or in combination with other treatments is the basic therapy in NB.

Upregulation of the angiogenic factors PlGF, VEGF and their receptors (Flt-1, Flk-1/KDR) by TSH in cultured thyrocytes and in the thyroid gland of thiouracil-fed rats suggest a TSH-dependent paracrine mechanism for goiter hypervascularization.

Placenta growth factor (PlGF) and vascular endothelial growth factor (VEGF) represent two closely related angiogenic growth factors active as homodimers or heterodimers. Since goiters of the thyroid gland are extremely hypervascular, we investigated the expression of PlGF, VEGF and their receptors, Flt-1 and Flk-1/KDR, in a small panel of human goiters from patients with Graves's disease, in an animal model of thyroid goitrogenesis and in in vitro cultured thyroid cells. Here we report that the mRNA expression of PlGF, VEGF and their receptors is markedly enhanced in biopsies of goiters resected from Graves's patients. In vivo studies demonstrated that in the thyroid gland of thiouracil-fed rats, increased mRNA and protein expression of PIGF, VEGF, Flt-1 and Flk-1/KDR occurred subsequent to the rise in the serum thyroid stimulating hormone (TSH) levels and in parallel with thyroid capillary proliferation. In vitro studies confirmed the existence of such TSH-dependent paracrine communication between thyroid epithelial cells and endothelium since the conditioned medium collected from TSH-stimulated thyrocytes acquired mitogenic activity for human umbilical vein endothelial (HUVE) cells. Altogether, these data suggest that PlGF and VEGF, released by thyrocytes in response to the chronic activation of the TSH receptor pathway, may act through a paracrine mechanism on thyroid endothelium.