Expression, regulation, and function of paired-box gene 8 in the human placenta and placental cancer cell lines

Maternal Vitamin and Mineral Supplementation and Rate of Maternal Weight Gain Affects Placental Expression of Energy Metabolism and Transport-Related Genes

Maternal nutrients are essential for proper fetal and placental development and function. However, the effects of vitamin and mineral supplementation under two rates of maternal weight gain on placental genome-wide gene expression have not been investigated so far. Furthermore, biological processes and pathways in the placenta that act in response to early maternal nutrition are yet to be elucidated. Herein, we examined the impact of maternal vitamin and mineral supplementation (from pre-breeding to day 83 post-breeding) and two rates of gain during the first 83 days of pregnancy on the gene expression of placental caruncles (CAR; maternal placenta) and cotyledons (COT; fetal placenta) of crossbred Angus beef heifers. We identified 267 unique differentially expressed genes (DEG). Among the DEGs from CAR, we identified ACAT2, SREBF2, and HMGCCS1 that underlie the cholesterol biosynthesis pathway. Furthermore, the transcription factors PAX2 and PAX8 were over-represented in biological processes related to kidney organogenesis. The DEGs from COT included SLC2A1, SLC2A3, SLC27A4, and INSIG1. Our over-representation analysis retrieved biological processes related to nutrient transport and ion homeostasis, whereas the pathways included insulin secretion, PPAR signaling, and biosynthesis of amino acids. Vitamin and mineral supplementation and rate of gain were associated with changes in gene expression, biological processes, and KEGG pathways in beef cattle placental tissues.

Precision genotyping diagnosis of lung tumors with trophoblastic morphology in young women

Trophoblastic differentiation has been previously described in somatic carcinomas at different primary sites, including the lung. Lung carcinomas with trophoblastic morphology presenting in women during the reproductive years pose a unique diagnostic challenge due to their overlapping microscopical and immunophenotypical features with metastatic choriocarcinoma of gestational origin. Distinction between the two entities is paramount as they require different chemotherapeutic regimens and have a markedly different prognostic outlook. Here we report a series of three female patients (ages 37-48 years) presenting with lung masses. Two of the three patients were noted to have elevated serum beta-hCG levels at the time of their presentation, while serum beta-hCG was not evaluated preoperatively in the third patient. None of them had a clinical history of molar pregnancy or gestational trophoblastic neoplasia. Core biopsies of the lung masses were performed in two patients and one patient underwent a wedge resection, showing poorly differentiated carcinoma in all cases with scattered multinucleated giant cells, hemorrhage, and necrosis. Beta-hCG immunostain was performed in two cases and showed diffuse immunoreactivity. Clinical history and imaging studies were not conclusive in any of the cases to rule out a gestational origin. Short tandem repeat genotyping analysis was performed to compare the allelic patterns between tumor and normal tissues and revealed identical profiles in one case, consistent with somatic origin, and unique paternal alleles in two cases, confirming metastatic gestational choriocarcinoma. The patient with primary somatic lung carcinoma died of disease within 15 months despite chemotherapy, while both patients with gestational choriocarcinoma responded well to chemotherapy and are alive without evidence of disease. Our cases illustrate the diagnostic pitfalls of lung tumors with trophoblastic differentiation in young women. Genotyping analysis offers precise diagnostic distinction between primary lung carcinoma and gestational choriocarcinoma with major therapeutic and prognostic implications for the patients.

Essential role of the ERK/MAPK pathway in blood-placental barrier formation

The mammalian genome contains two ERK/MAP kinase kinase genes, Map2k1 and Map2k2, which encode dual-specificity kinases responsible for ERK activation. Loss of Map2k1 function in mouse causes embryonic lethality due to placental defects, whereas Map2k2 mutants have a normal lifespan. The majority of Map2k1(+/-) Map2k2(+/-) embryos die during gestation from the underdevelopment of the placenta labyrinth, demonstrating that both kinases are involved in placenta formation. Map2k1(+/-) Map2k2(+/-) mutants show reduced vascularization of the labyrinth and defective formation of syncytiotrophoblast layer II (SynT-II) leading to the accumulation of multinucleated trophoblast giant cells (MTGs). To define the cell type-specific contribution of the ERK/MAPK pathway to placenta development, we performed deletions of Map2k1 function in different Map2k1 Map2k2 allelic backgrounds. Loss of MAP kinase kinase activity in pericytes or in allantois-derived tissues worsens the MTG phenotype. These results define the contribution of the ERK/MAPK pathway in specific embryonic and extraembryonic cell populations for normal placentation. Our data also indicate that MTGs could result from the aberrant fusion of SynT-I and -II. Using mouse genetics, we demonstrate that the normal development of SynT-I into a thin layer of multinucleated cells depends on the presence of SynT-II. Lastly, the combined mutations of Map2k1 and Map2k2 alter the expression of several genes involved in cell fate specification, cell fusion and cell polarity. Thus, appropriate ERK/MAPK signaling in defined cell types is required for the proper growth, differentiation and morphogenesis of the placenta.

Molecular basis of thyrotropin and thyroid hormone action during implantation and early development

BACKGROUND

Implantation and early embryo development are finely regulated processes in which several molecules are involved. Evidence that thyroid hormones (TH: T4 and T3) might be part of this machinery is emerging. An increased demand for TH occurs during gestation, and any alteration in maternal thyroid physiology has significant implications for both maternal and fetal health. Not only overt but also subclinical hypothyroidism is associated with infertility as well as with obstetric complications, including disruptions and disorders of pregnancy, labor, delivery, and troubles in early neonatal life.

METHODS

We searched the PubMed and Google Scholar databases for articles related to TH action on ovary, endometrium, trophoblast maturation and embryo implantation. In addition, articles on the regulation of TH activity at cellular level have been reviewed. The findings are hereby summarized and critically discussed.

RESULTS

TH have been shown to influence endometrial, ovarian and placental physiology. TH receptors (TR) and thyrotropin (thyroid-stimulating hormone: TSH) receptors (TSHR) are widely expressed in the feto-maternal unit during implantation, and both the endometrium and the trophoblast might be influenced by TH either directly or through TH effects on the synthesis and activity of implantation-mediating molecules. Interestingly, due to the multiplicity of mechanisms involved in TH action (e.g. differential expression of TR isoforms, heterodimeric receptor partners, interacting cellular proteins, and regulating enzymes), the TH concentration in blood is not always predictive of their cellular availability and activity at both genomic and nongenomic level.

CONCLUSIONS

In addition to the known role of TH on the hormonal milieu of the ovarian follicle cycle, which is essential for a woman's fertility, evidence is emerging on the importance of TH signaling during implantation and early pregnancy. Based on recent observations, a local action of TH on female reproductive organs and the embryo during implantation appears to be crucial for a successful pregnancy. Furthermore, an imbalance in the spatio-temporal expression of factors involved in TH activity might induce early arrest of pregnancy in women considered as euthyroid, based on their hormonal blood concentration. In conclusion, alterations of the highly regulated local activity of TH may play a crucial, previously underestimated, role in early pregnancy and pregnancy loss. Further studies elucidating this topic should be encouraged.

Role of PAX8 in the regulation of MET and RON receptor tyrosine kinases in non-small cell lung cancer

BACKGROUND

Non-small cell lung cancers (NSCLC) are highly heterogeneous at the molecular level and comprise 75% of all lung tumors. We have previously shown that the receptor tyrosine kinase (RTK) MET frequently suffers gain-of-function mutations that significantly promote lung tumorigenesis. Subsequent studies from our lab also revealed that PAX5 transcription factor is preferentially expressed in small cell lung cancer (SCLC) and promotes MET transcription. PAX8, however, is also expressed in NSCLC cell lines. We therefore investigated the role of PAX8 in NSCLC.

METHODS

Using IHC analysis, PAX8 protein expression was determined in archival NSCLC tumor tissues (n = 254). In order to study the effects of PAX8 knockdown on NSCLC cellular functions such as apoptosis and motility, siRNA against PAX8 was used. Confocal fluorescence microscopy was used to monitor the localization of MET, RON and PAX8. The combinatorial effect of PAX8 knockdown and MET inhibition using SU11274 was investigated in NSCLC cell viability assay.

RESULTS

Relative levels of PAX8 protein were elevated (≥ + 2 on a scale of 0-3) in adenocarcinoma (58/94), large cell carcinoma (50/85), squamous cell carcinoma (28/47), and metastatic NSCLC (17/28; lymph node). Utilizing early progenitors isolated from NSCLC cell lines and fresh tumor tissues, we observed robust overexpression of PAX8, MET, and RON. PAX8 knockdown A549 cells revealed abrogated PAX8 expression with a concomitant loss in MET and the related RON kinase expression. A dramatic colocalization between the active form of MET (also RON) and PAX8 upon challenging A549 cells with HGF was visualized. A similar colocalization of MET and EGL5 (PAX8 ortholog) proteins was found in embryos of C. elegans. Most importantly, knockdown of PAX8 in A549 cells resulted in enhanced apoptosis (~6 fold) and decreased cell motility (~45%), thereby making PAX8 a potential therapeutic target. However, the combinatorial approach of PAX8 knockdown and treatment with MET inhibitor, SU11274, had marginal additive effect on loss of NSCLC cell viability.

CONCLUSION

PAX8 provides signals for growth and motility of NSCLC cells and is necessary for MET and RON expression. Further investigations are necessary to investigate the therapeutic potential of PA8 in NSCLC.

Thyroglobulin in smoking mothers and their newborns at delivery suggests autoregulation of placental iodide transport overcoming thiocyanate inhibition

BACKGROUND

Placental transport of iodide is required for fetal thyroid hormone production. The sodium iodide symporter (NIS) mediates active iodide transport into the thyroid and the lactating mammary gland and is also present in placenta. NIS is competitively inhibited by thiocyanate from maternal smoking, but compensatory autoregulation of iodide transport differs between organs. The extent of autoregulation of placental iodide transport remains to be clarified.

OBJECTIVE

To compare the impact of maternal smoking on thyroglobulin (Tg) levels in maternal serum at delivery and in cord serum as markers of maternal and fetal iodine deficiency.

METHODS

One hundred and forty healthy, pregnant women admitted for delivery and their newborns were studied before the iodine fortification of salt in Denmark. Cotinine in urine and serum classified mothers as smokers (n=50) or nonsmokers (n=90). The pregnant women reported on intake of iodine-containing supplements during pregnancy and Tg in maternal serum at delivery and in cord serum were analyzed.

RESULTS

In a context of mild-to-moderate iodine deficiency, smoking mothers had significantly higher serum Tg than nonsmoking mothers (mean Tg smokers 40.2 vs nonsmokers 24.4 μg/l, P=0.004) and so had their respective newborns (cord Tg 80.2 vs 52.4 μg/l, P=0.006), but the ratio between Tg in cord serum and maternal serum was not significantly different in smokers compared with nonsmokers (smoking 2.06 vs nonsmoking 2.22, P=0.69).

CONCLUSION

Maternal smoking increased the degree of iodine deficiency in parallel in the mother and the fetus, as reflected by increased Tg levels. However, placental iodide transport seemed unaffected despite high thiocyanate levels, suggesting that thiocyanate-insensitive iodide transporters alternative to NIS are active or that NIS in the placenta is autoregulated to keep iodide transport unaltered.

PAX Genes in Cancer; Friends or Foes?

PAX genes have been shown to be critically required for the development of specific tissues and organs during embryogenesis. In addition, PAX genes are expressed in a handful of adult tissues where they are thought to play important roles, usually different from those in embryogenesis. A common theme in adult tissues is a requirement for PAX gene expression in adult stem cell maintenance or tissue regeneration. The connections between adult stem cell PAX gene expression and cancer are intriguing, and the literature is replete with examples of PAX gene expression in either situation. Here we systematically review the literature and present an overview of postnatal PAX gene expression in normal and cancerous tissue. We discuss the potential link between PAX gene expression in adult tissue and cancer. In addition, we discuss whether persistent PAX gene expression in cancer is favorable or unfavorable.

Effect of oxygen concentrations on sodium iodide symporter expression and iodide uptake and hCG expression in human choriocarcinoma BeWo cells

Normal human fetal development requires an adequate supply of thyroid hormone from conception. Until about 16 wk gestation this is supplied entirely by placental transfer of maternal hormone. Subsequently, the fetal thyroid synthesizes thyroid hormones, requiring a supply of maternal iodide. Trophoblast iodide transfer is mediated by the apical sodium iodide symporter (NIS). Placental oxygen levels are low in early pregnancy (~1%), rising with placental vascularisation to a plateau of ~8% at about 16 wk. Although the impact of these changing oxygen levels on placental implantation is well recognized, effects on trophoblast materno-fetal exchange are less understood. We investigated expression of the NIS regulator hCG, NIS mRNA expression, and I(125) uptake in choriocarcinoma BeWo cells (a model of the trophoblast) cultured in 1 and 8% oxygen and in room air (21% oxygen). Expression of NIS and hCG mRNA and protein was low at 1% oxygen but rose significantly at 8 and at 21%. This was reflected in significant increases in I(125) uptake. Desferrioxamine, an iron chelator and hypoxia mimic, decreased NIS and hCG expression and I(125) uptake in BeWo cells. NIS expression and I(125) uptake in cells grown at 1% oxygen were not increased by addition of hCG (2,500 IU/l). We infer that placental NIS mRNA and protein expression are regulated by oxygen, rising with vascularization of the placenta in the late first trimester, a time when fetal iodide requirements are increasing.

Inhibition of peroxisome proliferator-activated receptor gamma increases estrogen receptor-dependent tumor specification

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a nuclear receptor that regulates gene transcription associated with intermediary metabolism, adipocyte differentiation, and tumor suppression and proliferation. To understand the role of PPARgamma in tumorigenesis, transgenic mice were generated with mammary gland-directed expression of the dominant-negative transgene Pax8PPARgamma. Transgenic mice were phenotypically indistinguishable from wild-type (WT) mice, but mammary epithelial cells expressed a greater percentage of CD29(hi)/CD24(neg), CK5(+), and double-positive CK14/CK18 cells. These changes correlated with reduced PTEN and increased Ras and extracellular signal-regulated kinase (ERK) and AKT activation. Although spontaneous tumorigenesis did not occur, transgenic animals were highly susceptible to progestin/7,12-dimethylbenz(a)anthracene-induced mammary carcinogenesis, which in contrast to WT mice resulted in a high tumor multiplicity and, most importantly, in the appearance of predominantly estrogen receptor alpha-positive (ER(+)) ductal adenocarcinomas. Tumors expressed a similar PTEN(lo)/pERK(hi)/pAKT(hi) phenotype as mammary epithelium and exhibited high activation of estrogen response element-dependent reporter gene activity. Tumorigenesis in MMTV-Pax8PPARgamma mice was insensitive to the chemopreventive effect of a PPARgamma agonist but was profoundly inhibited by the ER antagonist fulvestrant. These results reveal important new insights into the previously unrecognized role of PPARgamma in the specification of mammary lineage and the development of ER(+) tumors.

Expression of hepatocyte nuclear factor-1alpha mRNA in human anaplastic thyroid cancer cell lines and tumors

BACKGROUND

Hepatocyte nuclear factor (HNF)-1alpha and HNF-1beta are related transcription factors that are mainly expressed in liver cells. Our previous study showed that HNF-1beta was highly expressed in papillary thyroid cancer cell lines and tumors. HNF-1alpha mRNA, however, was not detected in differentiated thyroid cancer cell lines. The objective of this study was to determine whether HNF-1alpha is expressed in dedifferentiated anaplastic thyroid cancer cells.

METHODS

Total RNA isolated from six anaplastic thyroid cancer cell lines and 38 surgical samples was analyzed for HNF-1alpha mRNA by conventional reverse-transcription polymerase chain reaction (RT-PCR) or real-time RT-PCR. HNF-1alpha DNA binding activity was measured by gel retardation assay and HNF-1alpha protein was identified by Western blotting.

RESULTS

HNF-1alpha mRNA was expressed in four of the six anaplastic cell lines. The presence of HNF-1alpha protein and DNA binding activity was detected in three lines with higher HNF-1alpha mRNA level. Three cell lines also expressed HNF-1beta. HNF-1alpha transcripts were also detected in five out of six anaplastic tumors, but not in the papillary tumors except one with weak PCR signal.

CONCLUSION

HNF-1alpha mRNA was detected in high frequency in anaplastic thyroid cancer cell lines and tumors. HNF-1alpha might play a role in the pathogenesis of anaplastic thyroid cancer.

Effect of Iodide on Human Choriogonadotropin, Sodium-Iodide Symporter Expression, and Iodide Uptake in BeWo Choriocarcinoma Cells

CONTEXT

Active placental transport of maternal iodide by the thyroidal sodium iodide symporter (NIS) provides an essential substrate for fetal thyroid hormone synthesis. NIS is expressed in trophoblast and is regulated by human choriogonadotropin (hCG). In thyroid, iodide down-regulates expression of several genes including NIS. Placentas of iodine-deficient rats demonstrate up-regulation of NIS mRNA, suggesting a role for iodide in regulating placental NIS.

OBJECTIVES AND METHODS

The objectives were to examine effects of iodide on expression of NIS and hCG in BeWo choriocarcinoma cells. Gene expression was studied by quantitative real-time PCR. Effects on NIS protein expression were assessed by Western blotting. Functional activity of NIS was measured by (125)I uptake. Expression of hCG protein was assessed by immunoassay of secreted hormone.

RESULTS

Iodide inhibited NIS mRNA and membrane protein expression as well as (125)I uptake, which were paralleled by decreased betahCG mRNA expression and protein secretion. Iodide had no effects on pendrin expression. Addition of hCG increased NIS mRNA expression. This effect was partially inhibited by addition of iodide. The inhibitory effects of iodide on NIS mRNA expression were abolished by propylthiouracil and dithiothreitol.

CONCLUSIONS

We conclude that expression of placental NIS is modulated by maternal iodide. This may occur through modulation of hCG effects on NIS and hCG gene expression.

A PANorama of PAX genes in cancer and development

Populations of self-renewing cells that arise during normal embryonic development harbour the potential for rapid proliferation, migration or transdifferentiation and, therefore, tumour generation. So, control mechanisms are essential to prevent rapidly expanding populations from malignant growth. Transcription factors have crucial roles in ensuring establishment of such regulation, with the Pax gene family prominent amongst these. This review examines the role of Pax family members during embryogenesis, and their contribution to tumorigenesis when subverted.