Project description:Pituitary adenomas cause significant endocrine and mass-related morbidity. Not much is known about mechanisms underlying pituitary tumor pathogenesis. We searched for a side population (SP) in pituitary tumor, representing cells with high efflux capacity and potentially enriching for cancer/tumor stem cells (CSC/TSC). Human pituitary adenomas contain a SP irrespective of hormonal phenotype. This adenoma SP, as well as the further purified SP (pSP) depleted from endothelial and immune cells, enriches for cells that express ‘tumor stemness’ markers and signaling pathways, including epithelial-mesenchymal transition (EMT)-linked factors. The adenomas were found to contain self-renewing sphere-forming cells, considered a property of TSC. The sphere-initiating cells were retrieved in the pSP. Because benign pituitary adenomas do not grow in vitro and failed to expand in immunodeficient mice, the pituitary tumor cell line AtT20 was further used. We identified a SP in this cell line and found it more tumorigenic than the main population (MP). Of the two EMT-regulatory pathways tested, inhibition of Cxcr4 signaling reduced EMT-linked cell motility in vitro as well as xenograft tumor growth, whereas activation of TGFβ had no effect. The tumor pSP showed upregulated expression of the pituitary stem cell marker SOX2. Pituitaries from dopamine receptor D2 knockout (Drd2-/-) mice bearing prolactinomas, contain more pSP, Sox2+ and colony-forming cells than wildtype glands. In conclusion, we detected a SP in pituitary tumors and identified TSC-associated characteristics. Our study may contribute to a better understanding of pituitary tumor pathogenesis and lead to new therapeutic targets. We determined gene expression profiles for 5 human pituitary adenoma samples (all NF-A type). The samples were obtained immediately after transsphenoidal resection (by the neurosurgeon Dr. van Loon, Division Neurosurgery, University Hospitals Leuven). Informed consent was received from the patients. Hormonal phenotype was determined by the Department of Imaging and Pathology (University Hospitals Leuven). For each sample, CD31¯/CD45¯ SP (purified SP or pSP) and pMP cells were sorted by FACS. Separate assays were run subsequently for the two fractions. As such we present data from 10 microarrays.

Project description:Pituitary adenomas cause significant endocrine and mass-related morbidity. Not much is known about mechanisms underlying pituitary tumor pathogenesis.We searched for a side population (SP) in pituitary tumor, representing cells with high efflux capacity and potentially enriching for cancer/tumor stem cells (CSC/TSC). Human pituitary adenomas contain a SP irrespective of hormonal phenotype. This adenoma SP, as well as the further purified SP (pSP) depleted from endothelial and immune cells, enriches for cells that express ‘tumor stemness’ markers and signaling pathways, including epithelial-mesenchymal transition (EMT)-linked factors. The adenomas were found to contain self-renewing sphere-forming cells, considered a property of TSC. The sphere-initiating cells were retrieved in the pSP.Because benign pituitary adenomas do not grow in vitro and failed to expand in immunodeficient mice, the pituitary tumor cell line AtT20 was further used. We identified a SP in this cell line and found it more tumorigenic than the main population (MP). Of the two EMT-regulatory pathways tested, inhibition of Cxcr4 signaling reduced EMT-linked cell motility in vitro as well as xenograft tumor growth, whereas activation of TGFβ had no effect.The tumor pSP showed upregulated expression of the pituitary stem cell marker SOX2. Pituitaries from dopamine receptor D2 knockout (Drd2-/-) mice bearing prolactinomas, contain more pSP, Sox2+ and colony-forming cells than wildtype glands.In conclusion, we detected a SP in pituitary tumors and identified TSC-associated characteristics. Our study may contribute to a better understanding of pituitary tumor pathogenesis and lead to new therapeutic targets. We determined gene expression profiles for 9 human pituitary adenoma samples (5 x NF-A; 4 x GH-A). The samples were obtained immediately after transsphenoidal resection (by the neurosurgeon Dr. van Loon, Division Neurosurgery, University Hospitals Leuven). Informed consent was received from the patients. Hormonal phenotype was determined by the Department of Imaging and Pathology (University Hospitals Leuven). For each sample, total SP and MP cells were sorted by FACS. Separate assays were run subsequently for the two fractions. As such we present data from 18 microarrays.

Project description:Pituitary adenomas are common benign neoplasms giving rise to disorders of growth, reproductive function and cortisol production. Although recently determined to be monoclonal, very little is known about the mechanisms regulating the development of pituitary hyperplasia and neoplasia in humans. Surgical resection is the treatment of choice for most symptomatic pituitary adenomas. The goal of surgery is the complete removal of the tumor and the success of surgery is strongly affected by the presence of local invasion. However, complete tumor removal is unlikely when there is extensive local invasion. Identifying genes that control the invasiveness and recurrence of this class of tumors will provide therapeutic targets for this class of tumors. We will determine the expression pattern of genes in recurrent and invasive and pituitary adenomas and compare those to non-invasive and non-recurrent tumors. We hypothesize that the differential expression and activation of a number of genes affect pituitary adenoma recurrence and invasiveness. Rationale: Preliminary result showed a differential expression of novel PKC isozymes in non-invasive and invasive pituitary adenomas. PMA, an activator of both novel and classical PKC isozymes increased the expression of gelatinase A (MMP-2) mRNA in human pituitary adenoma cell line. This result raises a fundamental question as to the functional role of novel PKC isozymes and proteases in the invasive phenotype of pituitary adenomas. The primary component of this Specific Aim is to determine whether specific genes are differentially expressed in recurrent or invasive adenomas when compared with control non-invasive tumors. Tissue specimens from non-invasive and invasive (dural invasion based microscopic examination) and recurrent vs non-recurrent tumors will be used for microarray analysis. Frozen pituitaryspecimens will be collected and total RNA extracted with TriZol reagent. We will provide total RNA (10 ug) from non-invasive, invasive, reoccurred and non-occurrent pituitary adenomas.

Project description:Pituitary adenomas are common benign neoplasms giving rise to disorders of growth, reproductive function and cortisol production. Although recently determined to be monoclonal, very little is known about the mechanisms regulating the development of pituitary hyperplasia and neoplasia in humans. Surgical resection is the treatment of choice for most symptomatic pituitary adenomas. The goal of surgery is the complete removal of the tumor and the success of surgery is strongly affected by the presence of local invasion. However, complete tumor removal is unlikely when there is extensive local invasion. Identifying genes that control the invasiveness and recurrence of this class of tumors will provide therapeutic targets for this class of tumors. We will determine the expression pattern of genes in recurrent and invasive and pituitary adenomas and compare those to non-invasive and non-recurrent tumors. We hypothesize that the differential expression and activation of a number of genes affect pituitary adenoma recurrence and invasiveness. Rationale: Preliminary result showed a differential expression of novel PKC isozymes in non-invasive and invasive pituitary adenomas. PMA, an activator of both novel and classical PKC isozymes increased the expression of gelatinase A (MMP-2) mRNA in human pituitary adenoma cell line. This result raises a fundamental question as to the functional role of novel PKC isozymes and proteases in the invasive phenotype of pituitary adenomas. The primary component of this Specific Aim is to determine whether specific genes are differentially expressed in recurrent or invasive adenomas when compared with control non-invasive tumors. Tissue specimens from non-invasive and invasive (dural invasion based microscopic examination) and recurrent vs non-recurrent tumors will be used for microarray analysis. Frozen pituitaryspecimens will be collected and total RNA extracted with TriZol reagent. We will provide total RNA (10 ug) from non-invasive, invasive, reoccurred and non-occurrent pituitary adenomas. Keywords: other

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Pituitary tumors contain a side population with 'tumor stem cell'-associated characteristics [set 1]

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