Beáta Scholtz

DIFFERENTIALLY EXPRESSED MicroRNAs IN SMALL CELL LUNG CANCER

Expression of microRNAs (miRNAs) is characteristically altered in cancer, and they may play a role in cancer development and progression. The authors performed microarray and real-time quantitative reverse transcriptase–polymerase chain reaction (RT-PCR) analyses to determine the miRNA expression profile of primary small cell lung cancer. Here we show that at least 24 miRNAs are differentially expressed between normal lung and primary small cell lung cancer (SCLC) tumors. These include miR-301, miR-183/96/182, miR-126, and miR-223, which are microRNAs deregulated in other tumor types as well; and other miRNAs, such as miR-374 and miR-210, not previously reported in association with lung cancer. The aberrant miRNA profile of SCLC may offer new insights in the biology of this aggressive tumor, and could potentially provide novel diagnostic markers.

miR-126 inhibits proliferation of small cell lung cancer cells by targeting SLC7A5

Despite intensive efforts to improve therapies, small cell lung cancer (SCLC) still has a dismal median survival of 18 months. Since miR‐126 is under‐expressed in the majority of SCLC tumors, we investigated the effect of miR‐126 overexpression on the proliferation and cell cycle distribution of H69 cells. Our results demonstrate that miR‐126 inhibits proliferation of H69 cells, by delaying the cells in the G1 phase. Short interfering RNA (siRNA) mediated suppression of SLC7A5, a predicted target of mir‐126, has the same effect on H69 cells. We also show for the first time that SLC7A5 is a direct target of miR‐126.

Identification and characterization of two related murine genes, Eat2a and Eat2b, encoding single SH2-domain adapters

Human EAT-2 (SH2D1B) and SLAM-associated protein (SAP) (SH2D1A) are single SH2-domain adapters, which bind to specific tyrosine residues in the cytoplasmic tail of six signaling lymphocytic activation molecule (SLAM) (SLAMF1)-related receptors. Here we report that, unlike in humans, the mouse and rat Eat2 genes are duplicated with an identical genomic organization. The coding regions of the mouse Eat2a and Eat2b genes share 91% identity at the nucleotide level and 84% at the protein level; similarly, segments of introns are highly conserved. Whereas expression of mouse Eat2a mRNA was detected in multiple tissues, Eat2b was only detectable in mouse natural killer cells, CD8+ T cells, and ovaries, suggesting a very restricted tissue expression of the latter. Both the EAT-2A and EAT-2B coimmunoprecipitated with mouse SLAM in transfected cells and augmented tyrosine phosphorylation of the cytoplasmic tail of SLAM. Both EAT-2A and EAT-2B bind to the Src-like kinases Fyn, Hck, Lyn, Lck, and Fgr, as determined by a yeast two-hybrid assay. However, unlike SAP, the EAT-2 proteins bind to their kinase domains and not to the SH3 domain of these kinases. Taken together, the data suggest that both EAT-2A and EAT-2B are adapters that recruit Src kinases to SLAM family receptors using a mechanism that is distinct from that of SAP.

Reference genes for quantitative real time PCR in UVB irradiated keratinocytes.

Real time quantitative reverse transcription-polymerase chain reaction (qRT-PCR) is a sensitive and highly reproducible method often used for determining mRNA levels. To enable proper comparison of gene expression genes expressed at stabile levels within the cells in the studied experimental system need to be identified and used as reference. Ultraviolet B (UVB) radiation is an exogenous carcinogenic stimulus in keratinocytes, and UVB elicited changes have extensively been studied by qRT-PCR, yet a comparison of commonly used reference genes in UVB treatment is lacking. To find the best genes for compensating slight inter-sample variations in keratinocytes in UVB experiments and to understand the potential effects of improper reference gene (RG) selection we have analyzed the mRNA expression of 10 housekeeping genes in neonatal human epidermal keratinocytes (NHEK) after UVB treatment. The biological effect of the used UVB light source was validated by trypane blue exclusion, MTT and comet assays. 20-40mJ/cm(2) dose was chosen for the experiments. The stability of the 10 RGs was assessed by the GeNorm and Normfinder software tools. Regardless of their slightly different algorithm the programs found succinate dehydrogenase complex subunit A (SDHA) to be the best individual RG and SDHA and phosphoglycerate kinase-1 (PGK1) as the most suitable combination. Analysis of the expression of tumor necrosis factor alpha (TNFalpha) and vascular endothelial growth factor (VEGF) found that while the perception of changes in TNF-alpha, a gene undergoing marked upregulation after UVB irradiation is independent of the used RG, changes seen in the more modestly upregulated VEGF are greatly effected by reference gene selection. These findings highlight the importance of reference gene selection in UVB irradiation experiments, and provide evidence that using SDHA or the combination of SDHA and PGK1 as standards could be a reliable method for normalizing qRT-PCR results in keratinocytes after UVB treatment.

Chronic Obstructive Pulmonary Disease-Specific Gene Expression Signatures of Alveolar Macrophages as well as Peripheral Blood Monocytes Overlap and Correlate with Lung Function

Background: Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory disease characterized by progressive airflow limitation and significant extrapulmonary (systemic) effects that lead to co-morbid conditions, though the pathomechanism of COPD is largely undetermined. Alveolar macrophages (AM) derived from peripheral monocytes (MO) appear to play a key role in initiating and/or sustaining disease progression. Objectives: To identify disease- and cell type-specific gene expression profiles and potential overlaps in those in order to diagnose COPD, characterize its progression and determine the effect of drug treatment. Method: Global gene expression analysis was used for primary screening in order to obtain expression signatures of AMs and circulating MOs of COPD patients and healthy controls. The results of microarray analyses of AMs (20 controls and 26 COPD patients) and MOs (16 controls and 22 COPD patients) were confirmed and validated by real-time quantitative polymerase chain reaction. Results: We have identified gene sets specifically associated with COPD in AMs and MOs. There were overlapping genes between the two cell types. Our data also show that COPD-specific gene expression signatures in AMs and MOs correlate with percent of predicted FEV1. Conclusion: Disease-specific and overlapping gene expression signatures can be defined in lung-derived macrophages and also in circulating monocytes. Some of the validated expression changes in both cell types correlate with lung function and therefore could serve as biomarkers of disease progression.

Transformed dermatofibrosarcoma protuberans: real time polymerase chain reaction detection of COL1A1–PDGFB fusion transcripts in sarcomatous areas

Background: Recent cytogenetic studies have shown that reciprocal translocation t (17;22)(q22;q13) and a supernumerary ring chromosome derived from the translocation r(17;22) are highly characteristic of dermatofibrosarcoma protuberans (DFSP). The chromosomal rearrangements fuse the collagen type Iα1 (COL1A1) and the platelet-derived growth factor B-chain (PDGFB) genes. The COL1A1–PDGFB fusion transcript has been shown not only in conventional DFSP but also in a small series of DFSP with fibrosarcomatons areas (DFSP-FS) using reverse transcriptase-based conventional polymerase chain reaction. Nothing is known about the status of the COL1A1–PDGFB chimaeric gene in the pleomorphic areas of DFSP-PleoSarc (formerly known as DFSP-malignant fibrous sarcoma). Aims: To show the COL1A1–PDGFB fusion transcript in transformed malignant fibrous histiocytoma. Method: A real-time polymerase chain reaction assay for the COL1A1–PDGFB fusion transcript in a series of DFSP containing sarcoma was conducted to determine whether the chimaeric gene could be identified in both components of DFSP-FS and DFSP-PleoSarc. Eight cases were analysed. Results: In seven cases, transcriptable RNA was detected, and in these cases, translocations were found between COL1A1 and PDGFB genes involving exons 27, 32, 34, 40 and 47 of the COL1A1 gene and exon 2 of the PDGFB gene. Conclusions: From a diagnostic aspect, this assay can be particularly useful in confirming the diagnosis of sarcomatous DFSP. On the other hand, the COL1A1–PDGFB fusion gene was shown in three cases of DFSP containing pleomorphic sarcoma, which supports the theory of the common histogenesis.

Retinoids enhance glucocorticoid-induced apoptosis of T cells by facilitating glucocorticoid receptor-mediated transcription

Glucocorticoid-induced apoptosis of thymocytes is one of the first recognized forms of programmed cell death. It was shown to require gene activation induced by the glucocorticoid receptor (GR) translocated into the nucleus following ligand binding. In addition, the necessity of the glucocorticoid-induced, but transcription-independent phosphorylation of phosphatidylinositol-specific phospholipase C (PI-PLC) has also been shown. Here we report that retinoic acids, physiological ligands for the nuclear retinoid receptors, enhance glucocorticoid-induced death of mouse thymocytes both in vitro and in vivo. The effect is mediated by retinoic acid receptor (RAR) alpha/retinoid X receptor (RXR) heterodimers, and occurs when both RARα and RXR are ligated by retinoic acids. We show that the ligated RARα/RXR interacts with the ligated GR, resulting in an enhanced transcriptional activity of the GR. The mechanism through which this interaction promotes GR-mediated transcription does not require DNA binding of the retinoid receptors and does not alter the phosphorylation status of Ser232, known to regulate the transcriptional activity of GR. Phosphorylation of PI-PLC was not affected. Besides thymocytes, retinoids also promoted glucocorticoid-induced apoptosis of various T-cell lines, suggesting that they could be used in the therapy of glucocorticoid-sensitive T-cell malignancies.

Adenosine A2A receptor-mediated cell death of mouse thymocytes involves adenylate cyclase and Bim and is negatively regulated by Nur77.

Adenosine is generated in the microenvironment of emerging thymocytes through normal mechanisms of lymphocyte selection. In a normal thymus, most of the adenosine is catabolized by adenosine deaminase; however, in an environment where up to 95% of the cells undergo programmed cell death, a sufficient amount of adenosine is accumulated to trigger cell surface adenosine receptors. Here we show that accumulated adenosine can induce apoptosis in immature mouse thymocytes, mostly via adenosine A2A receptors. The signaling pathway is coupled to adenylate cyclase activation, induction of the Nur77 transcription factor, Nur77‐dependent genes, such as Fas ligand and TRAIL, and the pro‐apoptotic BH3‐only protein Bim. We analyzed several knockout and transgenic mouse lines and found that adenosine‐induced killing of mouse thymocytes requires Bim, occurs independently of “death receptor” signaling and is inhibited by Bcl‐2 and Nur77. Collectively our data demonstrate that adenosine‐induced cell death involves signaling pathways originally found in negative selection of thymocytes and suggest a determining role of Bim and a regulatory role for Nur77.

Expression of invasion-related extracellular matrix molecules in human glioblastoma versus intracerebral lung adenocarcinoma metastasis.

Tumor cell invasion into the surrounding brain tissue is mainly responsible for the failure of radical surgical resection, with tumor recurrence in the form of microdisseminated disease. Extracellular matrix (ECM)-related molecules and their receptors predominantly participate in the invasion process, including cell adhesion to the surrounding microenvironment and cell migration. The extent of infiltration of the healthy brain by malignant tumors strongly depends on the tumor cell type. Malignant gliomas show much more intensive peritumoral invasion than do metastatic tumors. In this study, the mRNA expression of 30 invasion-related molecules (twenty-one ECM components, two related receptors, and seven ECM-related enzymes) was investigated by quantitative reverse transcriptase-polymerase chain reaction. Fresh frozen human tissue samples from glioblastoma (GBM), intracerebral lung adenocarcinoma metastasis, and normal brain were evaluated. Significant differences were established for 24 of the 30 molecules. To confirm our results at the protein level, immunohistochemical analysis of seven molecules was performed (agrin, neurocan, syndecan, versican, matrix metalloproteinase 2 [MMP-2], MMP-9, and hyaluronan). Determining the differences in the levels of invasion-related molecules for tumors of different origins can help to identify the exact molecular mechanisms that facilitate peritumoral infiltration by glioblastoma cells. These results should allow the selection of target molecules for potential chemotherapeutic agents directed against highly invasive malignant gliomas.

Lipid metabolite levels of prostaglandin D2 and eicosapentaenoic acid recovered from bronchoalveolar lavage fluid correlate with lung function of chronic obstructive pulmonary disease patients and controls

One‐step global profiling of analyte (mRNA, protein, metabolite) biomarkers may soon replace conventional blood and histological/biopsy diagnostics technologies. It is important to establish whether the numerous blood and other body fluid‐derived potential novel diagnostics will be sufficiently efficacious and precise to replace, for example, imaging and functional diagnostic tests. Currently, imaging technologies and spirometry are indispensable for the diagnosis and management of chronic obstructive pulmonary disease (COPD). To validate the concept of using body fluid biomarkers in COPD and to address the question of whether biomarker levels correlate with lung function, we measured the level of a number of biologically relevant lipids and metabolites in the bronchoalveolar lavage (BAL) fluid of COPD and control subjects and examined whether these correlate with numeric parameters of lung function. Both the diagnosis and management of COPD rely on costly and labor intensive lung function tests. Thus, there is an imminent need to replace the current diagnostic approaches with simpler clinical assays. As a first step, we demonstrate proof of principle; the correlation of lipid biomarkers as measured by LC‐MS with lung function. In the apparently BAL‐accessible fluid compartment, the total recovered lipid metabolite amount, particularly prostaglandin D2 and eicosapentaenoic acid show a remarkable linear correlation with lung function (R2>0.7). The study outcome is encouraging for the continuation of the work toward the measurement of lipid metabolite levels in more easily obtainable biological fluids such as sputum, exhaled air condensate, urine and plasma.