Are aggressive pituitary tumors and carcinomas two sides of the same coin? Pathologists reply to clinician's questions.

Pituitary adenohypophyseal tumors are considered as benign and termed "adenomas". However, many tumors are invasive and a proportion of these exhibit an "aggressive behavior" with premature death due to progressive growth. Only very rare (0.2%) tumors with metastases are considered malignant and termed "carcinomas". Taking into account this variability in behavior and the oncological definition, pathologists have proposed changing the term adenoma to tumor. Here we explain why use the term tumor instead of adenoma and identify tumor characteristics, associated with a high risk for poor prognosis. In a cohort of 125 tumors with aggressive behavior (APT) and 40 carcinomas with metastases (PC), clinical and pathological features were very similar. The comparison of this cohort (APT+PC) with a reference surgical cohort of 374 unselected patients clearly shows that the two cohorts differ greatly, especially the percentage of tumors with Ki67 ≥ 10% (35%vs3%; p < 0.001). A five-tiered prognostic classification, associating invasion and proliferation, identified grade 2b tumors (invasive and proliferative), with a high risk of recurrence/progression. Because half of the APT+ PC tumors have a Ki67 index ≥10%, and 80% of them show 2 or 3 positive markers of proliferation, we suggest that tumors that are clinically aggressive, invasive and highly proliferative with a Ki67 ≥ 10%, represent tumors with malignant potential. The percentage of grade 2b tumors, suspected of malignancy, which will become aggressive tumors or carcinomas is unknown. It is probably very low, but higher than 0.2% in surgical series. Early identification and active treatment of these aggressive tumors is needed to decrease morbidity and prolong survival.

Clinical, Pathological, and Molecular Factors of Aggressiveness in Lactotroph Tumours.

The behaviour of lactotroph tumours varies between benign tumours, those cured by treatment, and that of aggressive tumours, and carcinomas with metastasis. Identification of clinical, pathological and molecular factors is essential for the early identification of patients that may have such aggressive tumours. Plasma prolactin levels and tumour size and invasion, per se, are not prognostic factors. However, tumours appearing at a young age (<20 years), especially in boys, and the presence of genetic predisposition have a poorer prognosis. In addition, lactotroph tumours in men differ from those in women, being larger, more often invasive, and resistant to dopamine agonists. They are also more often high-grade with a high risk of recurrence and malignancy. The expression of estrogen receptor α is lower than in women and is closely correlated to aggressiveness. Proliferation markers (Ki-67 expression: ≥3%, mitotic count n > 2) are correlated to invasion and proliferation, but, taken alone, their prognostic value is debatable. Based on a 5-tiered clinicopathological classification, and taking into account invasion and proliferation, a grade 2b (aggressive) lactotroph tumour has a 20× risk of progression compared to a grade 1a (benign) tumour. Moreover, lactotroph tumours are the second-most frequent aggressive and malignant tumour. Other factors, such as the expression of growth factors (vascular endothelial growth factor [VEGF] and epidermal growth factor [EGF]), the genes regulating invasion, differentiation and proliferation, adhesion molecules (E-cadherin), matrix metalloproteinase 9, and chromosome abnormalities (chromosomes 11, 19, and 1), have also been correlated with aggressiveness. Currently, clinical signs, a prognostic classification, and molecular and genetic markers may all help the clinician in the early identification of aggressive lactotroph tumours and enable stratification of their management.

EMT inducers catalyze malignant transformation of mammary epithelial cells and drive tumorigenesis towards claudin-low tumors in transgenic mice.

The epithelial-mesenchymal transition (EMT) is an embryonic transdifferentiation process consisting of conversion of polarized epithelial cells to motile mesenchymal ones. EMT-inducing transcription factors are aberrantly expressed in multiple tumor types and are known to favor the metastatic dissemination process. Supporting oncogenic activity within primary lesions, the TWIST and ZEB proteins can prevent cells from undergoing oncogene-induced senescence and apoptosis by abolishing both p53- and RB-dependent pathways. Here we show that they also downregulate PP2A phosphatase activity and efficiently cooperate with an oncogenic version of H-RAS in malignant transformation of human mammary epithelial cells. Thus, by down-regulating crucial tumor suppressor functions, EMT inducers make cells particularly prone to malignant conversion. Importantly, by analyzing transformed cells generated in vitro and by characterizing novel transgenic mouse models, we further demonstrate that cooperation between an EMT inducer and an active form of RAS is sufficient to trigger transformation of mammary epithelial cells into malignant cells exhibiting all the characteristic features of claudin-low tumors, including low expression of tight and adherens junction genes, EMT traits, and stem cell-like characteristics. Claudin-low tumors are believed to be the most primitive breast malignancies, having arisen through transformation of an early epithelial precursor with inherent stemness properties and metaplastic features. Challenging this prevailing view, we propose that these aggressive tumors arise from cells committed to luminal differentiation, through a process driven by EMT inducers and combining malignant transformation and transdifferentiation.

Two polygenic mouse models of major depressive disorders identify TMEM161B as a potential biomarker of disease in humans.

Treatments are only partially effective in major depressive disorders (MDD) but no biomarker exists to predict symptom improvement in patients. Animal models are essential tools in the development of antidepressant medications, but while recent genetic studies have demonstrated the polygenic contribution to MDD, current models are limited to either mimic the effect of a single gene or environmental factor. We developed in the past a model of depressive-like behaviors in mice (H/Rouen), using selective breeding based on behavioral reaction after an acute mild stress in the tail suspension test. Here, we propose a new mouse model of depression (H-TST) generated from a more complex genetic background and based on the same selection process. We first demonstrated that H/Rouen and H-TST mice had similar phenotypes and were more sensitive to glutamate-related antidepressant medications than selective serotonin reuptake inhibitors. We then conducted an exome sequencing on the two mouse models and showed that they had damaging variants in 174 identical genes, which have also been associated with MDD in humans. Among these genes, we showed a higher expression level of Tmem161b in brain and blood of our two mouse models. Changes in TMEM161B expression level was also observed in blood of MDD patients when compared with controls, and after 8-week treatment with duloxetine, mainly in good responders to treatment. Altogether, our results introduce H/Rouen and H-TST as the two first polygenic animal models of MDD and demonstrate their ability to identify biomarkers of the disease and to develop rapid and effective antidepressant medications.

Aggressive and malignant prolactin pituitary tumors: pathological diagnosis and patient management.

According to the World Health Organization classification of pituitary tumors, only tumors with systemic metastasis must be considered as carcinomas. Invasive tumors with multiple recurrences are only classified as aggressive tumors or "atypical adenomas". To illustrate the problems encountered in the pathological diagnosis of pituitary carcinoma and in patient management, we present two male patients operated on for an aggressive prolactin pituitary adenoma with and without metastasis. In case 1, 5 surgeries, 3 irradiations, increased doses of dopamine agonists, and trials of temozolomide and carboplatine-VP16 failed to control tumor progression and the appearance of metastases which lead to death 16 years after onset. In case 2, based on the initial diagnosis of an aggressive-invasive adenoma that was resistant to dopamine agonists, gamma-Knife irradiation was initially performed on the intra-cavernous remnant. Eight years after onset, the remnant remained stabilized and the plasma PRL normalized under dopamine agonist. From these 2 cases alongside other cases found in the literature, we propose that the association of certain clinical signs (male sex, dopamine-resistant hyperprolactinemia), radiological signs (invasive macro or giant tumor on MRI) and histological signs (angiogenesis, Ki-67 > 3%, p53 positive, mitoses >2 per high power field, vascular invasion, up-regulation of genes related to invasion and proliferation, and allelic loss of chromosome 11) might suggest aggressiveness and be suspicious of malignancy before the appearance of metastasis. The early detection of an aggressive phenotype of a prolactin pituitary tumor should permit the earlier establishment of the optimum therapeutic strategy associating surgery and radiotherapy to delay or inhibit metastasis.

Molecular characterization of central neurocytomas: potential markers for tumor typing and progression.

Central neurocytomas (CNs) are rare intraventricular tumors presenting a favorable prognosis after surgery. Their transcriptomic profile is poorly characterized. We performed a microarray transcriptomic study to search for molecular markers that might improve diagnostic accuracy. Microarray analysis was performed on five CNs (3 primary and 2 recurrent CNs) using CodeLink human whole genome bioarrays, and the gene expression in CNs was compared with that in four pineal parenchymal tumors, consisting of two pineocytomas (PCs) and two pineoblastomas (PBs), other periventricular tumors which may present neuronal differentiation. We identified genes that were highly expressed in CNs compared to normal brain and might be candidates for the molecular typing of CNs. Several genes are part of the Wnt/ß-catenin and sonic hedgehog signaling pathways or mainly linked to calcium function or maintenance of neural progenitors. Moreover, several genes are overexpressed in both CNs and PCs and/or PBs such as INSM1 and NEUROD4, involved in neural or neuroendocrine differentiation. The overexpression of eight candidate genes in CNs (CHRDL2, IGF2, KiSS-1, CAL2, NTS, NHLH1, RGS16 and SCGN) was confirmed by real-time RT-PCR. Of the genes overexpressed in the recurrent CNs compared to the primary CNs, AQP5, KiSS-1, FZD7, AURKB, UBE2C and PTTG1 are genes which may be involved in tumor progression. Our study shows the potential involvement of various genes in the pathogenesis of CNs. These genes could be potential candidate markers for improving the characterization of CNs and some could be involved in CN tumorigenesis.

Molecular characterization of circumventricular organs and third ventricle ependyma in the rat: potential markers for periventricular tumors.

Circumventricular organs (CVOs) are specialized ventricular structures around the third and fourth ventricles of the brain. In humans, these structures are present during the fetal period and some become vestigial after birth. Some of these organs, such as the pineal gland (PG), subcommissural organ (SCO), and organum vasculosum of the lamina terminalis, might be the sites of origin of periventricular tumors, notably pineal parenchymal tumors, papillary tumor of the pineal region and chordoid glioma. In contrast to the situation in humans, CVOs are present in the adult rat and can be dissected by laser capture microdissection (LCM). In this study, we used LCM and microarrays to analyze the transcriptomes of three CVOs, the SCO, the subfornical organ (SFO), and the PG and the third ventricle ependyma in the adult rat, in order to better characterize these organs at the molecular level. Several genes were expressed only, or mainly, in one of these structures, for example, Erbb2 and Col11a1 in the ependyma, Epcam and Claudin-3 (CLDN3) in the SCO, Ren1 and Slc22a3 in the SFO and Tph, Aanat and Asmt in the PG. The expression of these genes in periventricular tumors should be examined as evidence for a possible origin from the CVOs. Furthermore, we performed an immunohistochemical study of CLDN3, a membrane protein involved in forming cellular tight junctions and found that CLDN3 expression was restricted to the apical pole of ependymocytes in the SCO. This microarray study provides new evidence regarding the possible origin of some rare periventricular tumors.

Intestinal Epithelial Cells Adapt to Chronic Inflammation through Partial Genetic Reprogramming.

Reactive oxygen species (ROS) are considered to be the main drivers of inflammatory bowel disease. We investigated whether this permanent insult compels intestinal stem cells to develop strategies to dampen the deleterious effects of ROS. As an adverse effect, this adaptation process may increase their tolerance to oncogenic insults and facilitate their neoplastic transformation. We submitted immortalized human colonic epithelial cells to either a mimic of chronic inflammation or to a chemical peroxide, analyzed how they adapted to stress, and addressed the biological relevance of these observations in databases. We demonstrated that cells adapt to chronic-inflammation-associated oxidative stress in vitro through a partial genetic reprogramming. Through a gene set enrichment analysis, we showed that this program is recurrently active in the intestinal mucosae of Crohn's and ulcerative colitis disease patients and evolves alongside disease progression. Based on a previously reported characterization of intestinal stem and precursor cells using tracing experiments, we lastly confirmed the activation of the program in intestinal precursor cells during murine colorectal cancer development. This adaptive process is thus likely to play a role in the progression of Crohn's and ulcerative disease, and potentially in the initiation of colorectal cancer.

New targeted therapies in pituitary carcinoma resistant to temozolomide.

To evaluate the antitumoral efficacy of everolimus in pituitary carcinoma resistant to temozolomide, the correlation with mammalian target of rapamycin (mTOR) signaling in the tumor and to present recent advances and future treatments of pituitary carcinomas. Pituitary carcinomas are rare and largely unresponsive to current treatment options. Recent reports on the antitumoral efficacy of temozolomide in some such patients are encouraging, yet most patients appear to show resistance to its actions. As a potential alternative, the mTOR inhibitor, everolimus, has been shown to potently inhibit pituitary cell proliferation highlighting mTOR inhibition as a promising therapeutic approach for pituitary carcinomas. We described the tumoral effects of a combination therapy with everolimus (5 mg/day) and octreotide (30 mg/month) and the mTOR signalling expression in a patient with pituitary ACTH carcinoma, compared to 17 other ACTH adenomas. Clinical and biochemical evaluation were performed every month, and imaging after 3 month of treatment. mTOR signaling was assessed by microarray expression analysis of each of the 18 adenoma tissues. Combined therapy failed to control pituitary tumor growth and ACTH secretion. Slight activation of mTOR signaling was found in all ACTH tumors alongside important variations between tumors. Low antitumor efficacy shown by everolimus might be explained by the weak activation of mTOR pathway in ACTH tumors. Everolimus treatment was inefficient at controlling secretion and tumor growth of one ACTH pituitary carcinoma. More clinical cases, with mTOR signalling expression analysis of the tumor, must be published before any conclusions can be drawn.

In Vivo Syngeneic Tumor Models with Acquired Resistance to Anti-PD-1/PD-L1 Therapies.

Antibodies targeting PD-1 and PD-L1 have produced durable responses in a subset of patients with cancer. However, a majority of these patients will ultimately relapse due to acquired resistance. To explore the underlying mechanisms of this secondary resistance, we developed five syngeneic murine tumor variants with acquired resistance to anti-PD-1 and/or PD-L1 antibodies in vivo. Resistant in vivo models were obtained by serial treatment/reimplantation cycles of the MC38 colorectal, MB49 and MBT2 bladder, and RENCA kidney and TyrNras melanoma models. Tumor immune infiltrates were characterized for wild type and resistant tumors using spectral cytometry and their molecular alterations analyzed using RNA sequencing analyses. Alterations in the tumor immune microenvironment were strongly heterogeneous among resistant models, involving select lymphoid and/or myeloid subpopulations. Molecular alterations in resistant models included previously identified pathways as well as novel candidate genes found to be deregulated in several resistant models. Among these, Serpinf1, coding for pigment epithelial-derived factor (PEDF) was further explored in the MC38 and the MBT2 models. Overexpression of Serpinf1 induced resistance to anti-PD-1 antibodies in the MC38 model, whereas knockdown of Serpinf1 sensitized this model as well as the primarily resistant MBT2 model. Serpinf1 overexpression was associated with increased production of free fatty acids and reduced activation of CD8+ cells, while orlistat, a compound that reduces the production of free fatty acids, reversed resistance to anti-PD-1 therapy. Our results suggest that a panel of syngeneic resistant models constitutes a useful tool to model the heterogeneity of resistance mechanisms encountered in the clinic.

Differential effect of oxidative or excitotoxic stress on the transcriptional profile of amyotrophic lateral sclerosis-linked mutant SOD1 cultured neurons.

Amyotrophic lateral sclerosis (ALS) is a progressive, lethal, degenerative disorder of motor neurons. The causes of most cases of ALS are as yet undefined. In a previous study, it was shown that N-methyl-D-aspartate (NMDA) and H(2)O(2) stimuli reduce neuronal survival in cortical neurons in culture (Boutahar et al., 2008). To identify variations in gene expression in response to these neurotoxins in transgenic vs. control cortical neurons cultures, both microarray and RT-PCR analysis were performed. High-density oligonucleotide microarrays showed changes in the expression of about 600 genes involved in protein degradation, neurotrophic factors pathway, cell cycle, inflammation, cytoskeleton, cell adhesion, transcription, or signalling. The most up-regulated genes following H(2)O(2) treatment were involved in cytoskeletal organization and axonal transport, such as ARAP2, KIF17, and DKK2, or in trophic factors pathways, such as insulin-like growth factor-binding protein 4 (IGFBP4), FGF17, and serpin2. The most down-regulated genes were involved in ion transport, such as TRPV1. After NMDA treatment, the most up-regulated genes were involved in protein degradation, such as ubiquitin-conjugating enzyme E2I and cathepsin H, and the most down-regulated genes were involved in ion transport, such as SCN7A. We conclude that these neurotoxins act through different transcriptional inductions, and these changes may reflect an adaptative cellular response to the cellular stress induced by the neurotoxins involved in ALS in the presence of mutant human SOD1.

Exploring the Significance of the Exon 4-Skipping Isoform of the ZNF217 Oncogene in Breast Cancer.

Oncogene alternative splicing events can create distinct functional transcripts that offer new candidate prognostic biomarkers for breast cancer. ZNF217 is a well-established oncogene but its exon 4-skipping isoform (ZNF217-ΔE4) has never been investigated in terms of clinical or biological relevance. Using in silico RNA-seq and RT-qPCR analyses, we demonstrated for the first time the existence of ZNF217-ΔE4 transcripts in primary breast tumors, and a positive correlation between ZNF217-ΔE4 mRNA levels and those of the wild-type oncogene (ZNF217-WT). A pilot retrospective analysis revealed that, in the Luminal subclass, the combination of the two ZNF217 variants (the ZNF217-ΔE4-WT gene-expression signature) provided more information than the mRNA expression levels of each isoform alone. Ectopic overexpression of ZNF217-ΔE4 in breast cancer cells promoted an aggressive phenotype and an increase in ZNF217-WT expression levels that was inversely correlated with DNA methylation of the ZNF217 gene. This study provides new insights into the possible role of the ZNF217-ΔE4 splice variant in breast cancer and suggests a close interplay between the ZNF217-WT and ZNF217-ΔE4 isoforms. Our data suggest that a dual signature combining the expression levels of these two isoforms may serve as a novel prognostic biomarker allowing better stratification of breast cancers with good prognosis and aiding clinicians in therapeutic decisions.

PARP inhibitors and radiation potentiate liver cell death in vitro. Do hepatocellular carcinomas have an achilles' heel?

BACKGROUND: A promising avenue for cancer treatment is exacerbating the deregulation of the DNA repair machinery that would normally protect the genome. To address the applicability of poly(ADP-ribose) polymerase (PARP) inhibitors (PARPi) combined with radiotherapy for the treatment of hepatocellular carcinoma (HCC) two approaches were used: firstly, the in vitro sensitivity to the PARPi Veliparib and Talazoparib +/- radiation exposure was determined in liver cell lines and the impact of the HBV X protein (HBx) that deregulates cellular DNA damage repair via SMC5/6 degradation was investigated. Secondly, PARP expression profiles and DNA damage levels using the surrogate marker gammaH2AX were assessed in a panel of control liver vs HCC tissues. METHODS: Cell cytotoxicity was measured by clonogenic survival or relative cell growth and the DNA damage response using immunological-based techniques in Hep3B, PLC/PRF/5, HepG2- and HepaRG-derived models. Transcriptome changes due to HBx expression vs SMC6 loss were assessed by RNA sequencing in HepaRG-derived models. PARP and PARG transcripts (qPCR) and PARP1, H2AX and gammaH2AX protein levels (RPPA) were compared in control liver vs HBV-, HCV-, alcohol- and non-alcoholic steatohepatitis-associated HCC (tumor/peritumor) tissues. RESULTS: PARPi cytotoxicity was significantly enhanced when combined with X-rays (2Gy) with Talazoparib having a greater impact than Veliparib in most in vitro models. HBx expression significantly lowered survival, probably driven by SMC5/6 loss based on the transcriptome analysis and higher DNA damage levels. PARP1 and PARP2 transcript levels were significantly higher in tumor than peritumor and control tissues. The HBV/HCV/alcohol-associated tumor tissues studied had reduced H2AX but higher gammaH2AX protein levels compared to peritumor and control tissues providing evidence of increased DNA damage during liver disease progression. CONCLUSIONS: These proof-of-concept experiments support PARPi alone or combined with radiotherapy for HCC treatment, particularly for HBV-associated tumors, that warrant further investigation.

Long-Term Exposure of Early-Transformed Human Mammary Cells to Low Doses of Benzo[a]pyrene and/or Bisphenol A Enhances Their Cancerous Phenotype via an AhR/GPR30 Interplay.

It is of utmost importance to decipher the role of chronic exposure to low doses of environmental carcinogens on breast cancer progression. The early-transformed triple-negative human mammary MCF10AT1 cells were chronically (60 days) exposed to low doses (10-10 M) of Benzo[a]pyrene (B[a]P), a genotoxic agent, and/or Bisphenol A (BPA), an endocrine disruptor. Our study revealed that exposed MCF10AT1 cells developed, in a time-dependent manner, an acquired phenotype characterized by an increase in cancerous properties (anchorage independent growth and stem-like phenotype). Co-exposure of MCF10AT1 cells to B[a]P and BPA led to a significantly greater aggressive phenotype compared to B[a]P or BPA alone. This study provided new insights into the existence of a functional interplay between the aryl hydrocarbon receptor (AhR) and the G protein-coupled receptor 30 (GPR30) by which chronic and low-dose exposure of B[a]P and/or BPA fosters the progression of MCF10AT1 cells into a more aggressive substage. Experiments using AhR or GPR30 antagonists, siRNA strategies, and RNAseq analysis led us to propose a model in which AhR signaling plays a "driver role" in the AhR/GPR30 cross-talk in mediating long-term and low-dose exposure of B[a]P and/or BPA. Retrospective analysis of two independent breast cancer cohorts revealed that the AhR/GPR30 mRNA expression signature resulted in poor breast cancer prognosis, in particular in the ER-negative and the triple-negative subtypes. Finally, the study identified targeting AhR and/or GPR30 with specific antagonists as a strategy capable of inhibiting carcinogenesis associated with chronic exposure to low doses of B[a]P and BPA in MCF10AT1 cells. Altogether, our results indicate that the engagement of both AhR and GPR30 functions, in particular in an ER-negative/triple-negative context of breast cells, favors tumor progression and leads to poor prognosis.

Chromosomal instability in the prediction of pituitary neuroendocrine tumors prognosis.

The purpose of this study was to analyze the impact of copy number variations (CNV) on sporadic pituitary neuroendocrine tumors (PitNETs) prognosis, to identify specific prognosis markers according to the known clinico-pathological classification. CGH array analysis was performed on 195 fresh-frozen PitNETs (56 gonadotroph, 11 immunonegative, 56 somatotroph, 39 lactotroph and 33 corticotroph), with 5 years post-surgery follow-up (124 recurrences), classified according to the five-tiered grading classification (invasion, Ki-67, mitotic index and p53 positivity). Effect of alterations on recurrence was studied using logistic regression models. Transcriptomic analysis of 32 lactotroph tumors was performed. The quantity of CNV was dependent on tumor type: higher in lactotroph (median(min-max) = 38% (0-97) of probes) compared to corticotroph (11% (0-77)), somatotroph (5% (0-99)), gonadotroph (0% (0-10)) and immunonegative tumors (0% (0-17). It was not predictive of recurrence in the whole cohort. In lactotroph tumors, genome instability, especially quantity of gains, significantly predicted recurrence independently of invasion and proliferation (p-value = 0.02, OR = 1.2). However, no specific CNV was found as a prognostic marker. Transcriptomic analysis of the genes included in the CNV and associated with prognosis didn't show significantly overrepresented pathway. In somatotroph and corticotroph tumors, USP8 and GNAS mutations were not associated with genome disruption or recurrence respectively. To conclude, CGH array analysis showed genome instability was dependent on PitNET type. Lactotroph tumors were highly altered and the quantity of altered genome was associated with poorer prognosis though the mechanism is unclear, whereas gonadotroph and immunonegative tumors showed the same 'quiet' profile, leaving the mechanism underlying tumorigenesis open to question.

Gene expression profiling in brain following acute systemic hypertonicity: novel genes possibly involved in osmoadaptation.

In brain osmoprotective genes known to be involved in cellular osmoadaptation to hypertonicity, as well as the related transcription factor tonicity-responsive enhancer binding protein (TonEBP) are only expressed in some cell subsets. In the search for other genes possibly involved in osmoadaptation of brain cells we have analyzed, through microarray, the transcriptional profile of forebrain from rats subjected to 45 min, 90 min, and 6 h systemic hypertonicity. Microarray data were validated by quantitative real-time PCR. Around 23 000 genes gave a reliable hybridization signal. The number of genes showing a higher expression increased from around 15 (45 min) up to nearly 200 (6 h). Among about 30 immediate early genes (IEGs) encoding transcription factors, only Atf3, Verge, and Klf4 showed a rapid increased expression. TonEBP-mRNA tissue level and TonEBP-mRNA labeling in neurons remained unchanged whereas TonEBP labeling was rapidly increased in neurons. Sodium-dependent neutral amino acid transporter-2 (SNAT2) encoded by gene Slc38a2 showed a delayed increased expression. The rapid tonicity-induced activation of Atf3, Verge, and Klf4 may regulate genes involved in osmoadaptation. Nfat5 encoding TonEBP is not an IEG and the early tonicity-induced expression of TonEBP in neurons may result from translational activation. Increased expression of sodium-dependent neutral amino-acid transporter 2 may lead to the cellular accumulation of amino acids for adaptation to hypertonicity.

Sex-Related Differences in Lactotroph Tumor Aggressiveness Are Associated With a Specific Gene-Expression Signature and Genome Instability.

Sex-related differences have been reported in various cancers, in particular men with lactotroph tumors have a worse prognosis than women. While the underlying mechanism of this sexual dimorphism remains unclear, it has been suggested that a lower estrogen receptor alpha expression may drive the sex differences observed in aggressive and malignant lactotroph tumors that are resistant to dopamine agonists. Based on this observation, we aimed to explore the molecular importance of the estrogen pathway through a detailed analysis of the transcriptomic profile of lactotroph tumors from 20 men and 10 women. We undertook gene expression analysis of the selected lactotroph tumors following their pathological grading using the five-tiered classification. Chromosomic alterations were further determined in 13 tumors. Functional analysis showed that there were differences between tumors from men and women in gene signatures associated with cell morphology, cell growth, cell proliferation, development, and cell movement. Hundred-forty genes showed an increased or decreased expression with a minimum 2-fold change. A large subset of those genes belonged to the estrogen receptor signaling pathway, therefore confirming the potent role of this pathway in lactotroph tumor sex-associated aggressiveness. Genes belonging to the X chromosome, such as CTAG2, FGF13, and VEGF-D, were identified as appealing candidates with a sex-linked dysregulation in lactotroph tumors. Through our comparative genomic hybridization analyses (CGH), chromosomic gain, in particular chromosome 19p, was found only in tumors from men, while deletion of chromosome 11 was sex-independent, as it was found in most (5/6) of the aggressive and malignant tumors. Comparison of transcriptomic and CGH analysis revealed four genes (CRB3, FAM138F, MATK, and STAP2) located on gained regions of chromosome 19 and upregulated in lactotroph tumors from men. MATK and STAP2 are both implicated in cell growth and are reported to be associated with the estrogen signaling pathway. Our work confirms the proposed involvement of the estrogen signaling pathway in favoring the increased aggressiveness of lactotroph tumors in men. More importantly, we highlight a number of ER-related candidate genes and further identify a series of target molecules with sex-specific expression that could contribute to the aggressive behavior of lactotroph tumors in men.

A diagnostic marker set for invasion, proliferation, and aggressiveness of prolactin pituitary tumors.

Although most pituitary tumors are benign, some are invasive or aggressive. In the absence of specific markers of malignancy, only tumors with metastases are considered malignant. To identify markers of invasion and aggressiveness, we focused on prolactin (PRL) tumors in the human and rat. Using radiology and histological methods, we classified 25 human PRL tumors into three groups (non-invasive, invasive, and aggressive-invasive) and compared them with a model of transplantable rat PRL tumors with benign and malignant lineages. Combining histological(mitoses and labeling for Ki-67, P53, pituitary transforming tumor gene (PTTG), and polysialic acid neural cell adhesion molecule) and transcriptomic (microarrays and q-RTPCR) methods with clinical data (post-surgical outcome with case-control statistical analysis), we found nine genes implicated in invasion (ADAMTS6, CRMP1, and DCAMKL3) proliferation (PTTG, ASK, CCNB1, AURKB, and CENPE), or pituitary differentiation (PITX1) showing differential expression in the three groups of tumors (P = 0.015 to 0.0001). A case-control analysis, comparing patients in remission (9 controls) and patients with persistent or recurrent tumors (14 cases) revealed that eight out of the nine genes were differentially up- or downregulated (P = 0.05 to 0.002), with only PTTG showing no correlation with clinical course (P = 0.258). These combined histological and transcriptomic analyses improve the pathological diagnosis of PRL tumors, indicating a reliable procedure for predicting tumor aggressiveness and recurrence potential. The similar gene profiles found between non-invasive human and benign rat tumors, as well as between aggressive-invasive human and malignant rat tumors provide new insights into malignancy in human pituitary tumors.

MicroRNAs in pituitary tumors.

Since the presence of microRNAs was first observed in normal pituitary, the majority of scientific publications addressing their role and the function of microRNAs in the pituitary have been based on pituitary tumor studies. In this review, we briefly describe the involvement of microRNAs in the synthesis of pituitary hormones and we present a comprehensive inventory of microRNA suppressors and inducers of pituitary tumors. Finally, we summarize the functional role of microRNAs in tumorigenesis, progression and aggressiveness of pituitary tumors, mechanisms contributing to the regulation (transcription factors, genomic modifications or epigenetic) or modulation (pharmacological treatment) of microRNAs in these tumors, and the interest of thoroughly studying the expression of miRNAs in body fluids.

A stemness-related ZEB1-MSRB3 axis governs cellular pliancy and breast cancer genome stability.

Chromosomal instability (CIN), a feature of most adult neoplasms from their early stages onward, is a driver of tumorigenesis. However, several malignancy subtypes, including some triple-negative breast cancers, display a paucity of genomic aberrations, thus suggesting that tumor development may occur in the absence of CIN. Here we show that the differentiation status of normal human mammary epithelial cells dictates cell behavior after an oncogenic event and predetermines the genetic routes toward malignancy. Whereas oncogene induction in differentiated cells induces massive DNA damage, mammary stem cells are resistant, owing to a preemptive program driven by the transcription factor ZEB1 and the methionine sulfoxide reductase MSRB3. The prevention of oncogene-induced DNA damage precludes induction of the oncosuppressive p53-dependent DNA-damage response, thereby increasing stem cells' intrinsic susceptibility to malignant transformation. In accord with this model, a subclass of breast neoplasms exhibit unique pathological features, including high ZEB1 expression, a low frequency of TP53 mutations and low CIN.