cyclin-d1 and Carcinoma--Medullary

Dexamethasone is known to inhibit the cell proliferation of certain transformed cell lines. In this study, the effect and action mechanism of dexamethasone were examined in the human medullary thyroid cancer cell line, TT cells.. TT cells were treated with or without dexamethasone. 5-Bromo-2'-deoxyuridine uptake assay was used to evaluate cell proliferation. Cell cycle and its regulatory proteins were assessed by flow cytometry and western blot analysis, respectively. Apoptosis was analyzed by Hoechst staining and Annexin V assay.. Dexamethasone significantly reduced TT cell proliferation by 60% (p < 0.01). A substantial portion of cells was arrested at the G1 phase. The expression levels of cyclin D1, cyclin-dependent kinase (CDK)4, and CDK2 were decreased. In addition, the phosphorylation of retinoblastoma protein, which is a critical checkpoint protein in the transition of G1 to S phase, was decreased. On the other hand, the expression level of p27(Kip1), which is a cyclin/CDK inhibitor, was enhanced. Hoechst staining showed many fragmented nuclei in the dexamethasone-treated cells. The proportion of early apoptotic cells was also increased in the Annexin V assay.. Dexamethasone inhibited the proliferation of TT cells through cell cycle arrest at the G1 phase and increased apoptosis.

Topics: Apoptosis; Blotting, Western; Carcinoma, Medullary; Cell Cycle Checkpoints; Cell Line, Tumor; Cell Proliferation; Cyclin D1; Cyclin-Dependent Kinase 2; Cyclin-Dependent Kinase 4; Cyclin-Dependent Kinase Inhibitor p27; Dexamethasone; Flow Cytometry; Glucocorticoids; Humans; Thyroid Neoplasms

Glycogen synthase kinase-3beta (GSK-3beta) is an important regulator of cell proliferation and survival. Conflicting observations have been reported regarding the regulation of GSK-3beta and extracellular signal-regulated kinase (ERK1/2) in cancer cells. In this study, we found that raf-1 activation in human medullary thyroid cancer cells, TT cells, resulted in phosphorylation of GSK-3beta. Inactivation of GSK-3beta in TT cells with well-known GSK-3beta inhibitors such as lithium chloride (LiCl) and SB216763 is associated with both growth suppression and a significant decrease in neuroendocrine markers such as human achaete-scute complex-like 1 and chromogranin A. Growth inhibition by GSK-3beta inactivation was found to be associated with cell cycle arrest due to an increase in the levels of cyclin-dependent kinase inhibitors such as p21, p27, and p15. Additionally, LiCl-treated TT xenograft mice had a significant reduction in tumor volume compared with those treated with control. For the first time, we show that GSK-3beta is a key downstream target of the raf-1 pathway in TT cells. Also, our results show that inactivation of GSK-3beta alone is sufficient to inhibit the growth of TT cells both in vitro and in vivo.

Topics: Adjuvants, Immunologic; Animals; Apoptosis; Carcinoma, Medullary; Cell Cycle; Cell Line, Tumor; Cell Proliferation; Chromogranin A; Cyclin D1; Cyclin-Dependent Kinase Inhibitor p15; Cyclin-Dependent Kinase Inhibitor p21; Cyclin-Dependent Kinase Inhibitor p27; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Humans; Indoles; Lithium Chloride; Maleimides; Mice; Mice, Nude; NIH 3T3 Cells; Phosphorylation; Proto-Oncogene Proteins c-raf; Signal Transduction; Thyroid Neoplasms; Xenograft Model Antitumor Assays

BP1, a novel transcriptional factor, belongs to DLX family of homeobox genes. Recent researches showed that BP1 gene is correlated to genesis of breast cancer, but its correlation to cell cycle control factor has not been reported yet. This study was to observe the expression of BP1 in breast cancer, and to make clear its correlation to Cyclin D1.. The expression of BP1 and Cyclin D1 in 86 specimens of human breast cancer and 20 specimens of normal breast tissue (3 cm away from primary tumor) was detected by reverse transcription-polymerase chain reaction (RT-PCR). BP1 poly antibody was made and was certificated by Western blot. The expression of BP1 and Cyclin D1 in 86 specimens of human breast cancer were detected by immunohistochemistry; their correlation was analyzed.. The positive rate of BP1 mRNA was significanlty higher in breast cancer than in normal breast tissues (69.8% vs. 0, P < 0.001). The positive rate of Cyclin D1 mRNA was 64.0% in breast cancer. BP1 mRNA and Cyclin D1 mRNA were co-expressed in 52 specimens of breast cancer, and simultaneously negative in 23 specimens (P = 0.227); BP1 protein and Cyclin D1 protein were co-expressed in 43 specimens, and simultaneously negative in 31 specimens (P = 0.146).. BP1 gene is highly expressed in breast cancer. There is co-expression of Cyclin D1 and BP1 in breast cancer. BP1 gene may promote the genesis of breast cancer through regulating the expression of Cyclin D1.

Topics: Adult; Aged; Blotting, Western; Breast; Breast Neoplasms; Carcinoma, Ductal, Breast; Carcinoma, Medullary; Cyclin D1; Female; Gene Expression Regulation, Neoplastic; Genes, bcl-1; Homeodomain Proteins; Humans; Immunohistochemistry; Middle Aged; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Transcription Factors

Activation of Ras or Raf in the human medullary thyroid carcinoma (MTC) cell line, TT, induces growth arrest and differentiation via two parallel, yet independent, pathways. One of these pathways is intracellular and the other is a cell-extrinsic, autocrine/paracrine pathway mediated by the leukemia inhibitory factor (LIF)/JAK/STAT pathway. Here, we show that IFI16 is a necessary and sufficient downstream effector for LIF effects in MTC cells, specifically required for the LIF/JAK/STAT pathway-induced growth inhibition in these cells. IFI16 was induced by Raf or LIF. Dominant-negative STAT3 could block the induction, indicating that Raf can induce IFI16 only via the cell-extrinsic pathway. Knock-down of IFI16 using siRNA abrogated LIF-induced changes in cellular levels of E2F1, cyclin D1, and p21WAF/CIP1, and cell cycle arrest. In addition, adenovirus-mediated overexpression of IFI16 was sufficient to induce growth arrest. In contrast to its essential role for LIF-mediated growth arrest, IFI16 was not required for differentiation induced by LIF. Knock-down of IFI16 could not block changes in differentiation markers of the MTC cells, including calcitonin, RET, and cell morphology. Our study identifies IFI16 as an essential growth-specific effector of the cell-extrinsic growth inhibitory pathway of Ras/Raf signaling in MTC cells.

Topics: Adenoviridae; Calcitonin; Carcinoma, Medullary; Cell Cycle; Cell Cycle Proteins; Cell Differentiation; Cell Line; Cell Line, Tumor; Cell Proliferation; Culture Media; Culture Media, Conditioned; Cyclin D1; Cyclin-Dependent Kinase Inhibitor p21; DNA-Binding Proteins; E2F Transcription Factors; E2F1 Transcription Factor; Genes, Dominant; Humans; Immunoblotting; Interleukin-6; Janus Kinase 1; Leukemia Inhibitory Factor; Models, Biological; Nuclear Proteins; Oligonucleotide Array Sequence Analysis; Phosphoproteins; Plasmids; Protein-Tyrosine Kinases; Reverse Transcriptase Polymerase Chain Reaction; RNA, Small Interfering; STAT3 Transcription Factor; Thyroid Neoplasms; Time Factors; Trans-Activators; Transcription Factors; Transfection

The aim of the study was to demonstrate and evaluate the expression of cyclin D1, a protein connected with a cell cycle, by means of the immunohistochemical method in malignant thyroid neoplasms. The purpose of the analysis of the results was to explain the relation between cyclin D1 in thyroid cells and neoplasm transformation.. The study was conducted on thyroid neoplasms from 35 patients who were diagnosed with the thyroid carcinoma (30 women and 5 men). Detection DAKO LSAB + system was applied with use of monoclonal antibodies against cyclin D1. The results of immunohistochemical reaction was described as an index (percentage of cells showing a characteristic brown color in 1000 counted cells). As a positive result of reaction an intensive brown color of carcinomas cellular nuclei was acknowledged.. The mean value of cyclin D1 expression index in papillary carcinoma was 14.44% +/- 9.37, in medullary carcinoma 27.35% +/- 5.40, in nonpapillary carcinomas originating from A cells 18.0% +/- 10.20. The results were statistically analyzed. In medullary carcinoma the highest values of positive cells cyclin D1 index were revealed.. The results obtained encourage continued studies on cyclin D1 expression in thyroid neoplasms and a more accurate analysis with a larger number of cases. Perhaps the index of this protein will become a recognized prognostic marker in thyroid neoplasms or an objective risk factor of the thyroid epithelial cells neoplastic transformation.

Topics: Adolescent; Adult; Aged; Aged, 80 and over; Biomarkers, Tumor; Carcinoma; Carcinoma, Medullary; Carcinoma, Papillary; Cell Transformation, Neoplastic; Cyclin D1; Female; Gene Expression Regulation, Neoplastic; Humans; Immunohistochemistry; In Vitro Techniques; Male; Middle Aged; Thyroid Neoplasms

Cyclin D1 is a G1 cyclin participating in the control of cell cycle progression through interaction with the retinoblastoma gene product (pRB). The overexpression of positive regulators (such as cyclin D1) has been reported in a variety of neoplasms, but their role in thyroid tumorigenesis is yet to be established. In our series of 54 thyroid carcinomas, cyclin D1 overexpression (detected by both immunohistochemistry and by Northern blotting) was correlated with prognostic variables, proliferative activity and pRB. Cyclin D1 overexpression was observed in 35% of thyroid carcinomas with a significantly higher expression of this cyclin in neoplastic tissues than in matched normal parenchyma. In well-differentiated carcinomas, the cyclin D1 mRNA overexpression was inversely correlated with nodal status (p = 0.03), while the protein product was higher in tumors from patients less than 40 than patients over 40 years of age. Inversely, there was no significant correlation with gender and tumor status, pRB and with proliferative activity.

Topics: Adenocarcinoma, Follicular; Blotting, Northern; Carcinoma, Medullary; Carcinoma, Papillary; Cell Division; Cyclin D1; Gene Expression; Genes, Retinoblastoma; Humans; Immunohistochemistry; Ki-67 Antigen; Prognosis; RNA, Messenger; Thyroid Neoplasms