Nadine Martinet

SOX2 is an oncogene activated by recurrent 3q26.3 amplifications in human lung squamous cell carcinomas.

Squamous cell carcinoma (SCC) of the lung is a frequent and aggressive cancer type. Gene amplifications, a known activating mechanism of oncogenes, target the 3q26-qter region as one of the most frequently gained/amplified genomic sites in SCC of various types. Here, we used array comparative genomic hybridization to delineate the consensus region of 3q26.3 amplifications in lung SCC. Recurrent amplifications occur in 20% of lung SCC (136 tumors in total) and map to a core region of 2 Mb (Megabases) that encompasses SOX2, a transcription factor gene. Intense SOX2 immunostaining is frequent in nuclei of lung SCC, indicating potential active transcriptional regulation by SOX2. Analyses of the transcriptome of lung SCC, SOX2-overexpressing lung epithelial cells and embryonic stem cells (ESCs) reveal that SOX2 contributes to activate ESC-like phenotypes and provide clues pertaining to the deregulated genes involved in the malignant phenotype. In cell culture experiments, overexpression of SOX2 stimulates cellular migration and anchorage-independent growth while SOX2 knockdown impairs cell growth. Finally, SOX2 over-expression in non-tumorigenic human lung bronchial epithelial cells is tumorigenic in immunocompromised mice. These results indicate that the SOX2 transcription factor, a major regulator of stem cell function, is also an oncogene and a driver gene for the recurrent 3q26.33 amplifications in lung SCC.

The retinoblastoma gene and its product are targeted by ICBP90: a key mechanism in the G1/S transition during the cell cycle.

The retinoblastoma protein (pRB) is encoded by the RB1 gene whose promoter contains several putative binding sites for ICBP90 (Inverted CCAAT box Binding Protein of 90 kDa), a transcriptional regulator of the topoisomerase IIα gene. ICBP90 has two consensus binding sites for pRB in its primary sequence. Here, we show that pRB and ICBP90 co-immunoprecipitate in cell extracts of proliferating human lung fibroblasts and of proliferating or confluent Jurkat cells. GST pull-down assays and immunocytochemistry, after cell synchronization in late G1 phase, confirmed this interaction. Overexpression of ICBP90 induces downregulation of pRB expression in lung fibroblasts as a result of mRNA decrease. DNA chromatin immunoprecipitation experiment shows that ICBP90 binds to the RB1 gene promoter under its methylated status. Overexpression of ICBP90 increases the S and G2/M phase cell fractions of serum-starved lung fibroblasts as assessed by flow cytometry analysis and increases topoisomerase IIα expression. Together, these results show that ICBP90 regulates pRB at the protein and gene transcription levels, thus favoring the entry into the S phase of the cells. We propose that ICBP90 overexpression, found in cancer cells, is involved in the altered checkpoint controls occurring in cancerogenesis.

Cytokines in human lung fibrosis

Fibrosis is a pathological process characterized by the replacement of normal tissue by mesenchymal cells and the extracellular matrix produced by these cells. The sequence of events leading to fibrosis of an organ involves the subsequent processes of injury with inflammation and disruption of the normal tissue architecture, followed by tissue repair with accumulation of mesenchymal cells in the area of derangement. The same sequence of events occurs in wound healing with normal granulation tissue and scar formation, but, while normal scar formation is very localized and transient, in contrast, in fibrosis, the repair process is exaggerated and usually widespread and can be chronic. Inflammatory cells (mainly mononuclear phagocytes), platelets, endothelial cells, and type II pneumocytes play a direct and indirect role in tissue injury and repair. The evaluation of three human fibrotic lung diseases, two diffuse [idiopathic pulmonary fibrosis (IPF), and the adult respiratory distress syndrome (ARDS)], and one focal (tumor stroma in lung cancer), has shown that several cytokines participate to the local injury and inflammatory reaction [interleukin-1 (IL-1), interleukin-8 (IL-8), monocyte chemotactic protein-1 (MCP-1), tumor necrosis factor-alpha (TNF-alpha)], while other cytokines are involved in tissue repair and fibrosis [platelet-derived growth factor (PDGF), insulin-like growth factor-1 (IGF-1), transforming growth factor-beta (TGF-beta), and basic-fibroblast growth factor (b-FGF)]. A better understanding of the cytokines and cytokine networks involved in lung fibrosis leads to the possibility of new therapeutic approaches.

Potentiation by tumour necrosis factor‐α of calcium signals induced by bradykinin and carbachol in human tracheal smooth muscle cells

The effect of tumour necrosis factor‐α (TNFα) on the increase in cytosolic free calcium ([Ca2+])i induced by carbachol and bradykinin (BK) was investigated in human tracheal smooth muscle cells in culture (TSMC). BK (10−12–10−9m) and carbachol (10−7–10−3m) produced a concentration‐dependent increase in [Ca2+]i (pD2 = 10.73 ± 0.05 and 5.57 ± 0.03 respectively). The increase in [Ca2+]i was significantly enhanced for both agonists in TNFα‐treated cells (10 ng ml−1 for 24 h). However, pD2 values were not modified (10.78 ± 0.03 and 5.62 ± 0.04 for BK and carbachol, respectively) suggesting that no change in the apparent receptor affinity occured. Thus, TNFα induced‐alterations in Ca2+ homeostasis in human TSMC may be a key mechanism underlying airway hyperreactivity.

Blood monocyte chemotaxis

Migration is a prerequisite for blood monocytes to exert their biological activities, since they have to migrate from blood into the tissues where they transform into macrophages. In vivo chemotaxis of blood monocytes is seldom evaluated, while their in vitro ability to migrate is frequently tested. The most frequently used test relies on BM migration through filters using modified Boyden chemotactic chambers. Using checkerboard analysis it is possible to define chemotactic and chemokinetic factors.

Clinical and Biological Basis of Lung Cancer Prevention

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Epigenetic effects of lung cancer predisposing factors impact on clinical diagnosis and prognosis

•  Introduction •  Tobacco smoke •  Radiation •  Viruses and hormones •  Implication of gene methylation in clinical diagnosis and prognosis •  Conclusions – Outlook

Serum level of soluble tumour necrosis factor receptor II (75 kDa) indicates inflammatory activity of sarcoidosis

Abstract. Ziegenhagen MW, Fitschen J, Martinet N, Schlaak M, Müller‐Quernheim J (Medical Hospital, Borstel, Germany and INSERM U.14, Vandoevre‐Les‐Nancy, France). Serum level of soluble tumour necrosis factor receptor II (75 kDa) indicates inflammatory activity of sarcoidosis. J Intern Med 2000; 248: 33–41.

An adult tissue-specific stem cell molecular phenotype is activated in epithelial cancer stem cells and correlated to patient outcome

Recent studies have shown that embryonic stem cell-like molecular phenotypes are commonly activated in human epithelial primary tumors and are linked to adverse patient prognosis. However it remains unclear whether these correlations to outcome are linked to the differentiation status of the human primary tumours1 or represent molecular reminiscences of epithelial cancer stem cells. In addition, while it has been demonstrated that leukemic cancer stem cells re-acquire an embryonic stem cell-like phenotype, the molecular basis of stem cell function in epithelial cancer stem cells has not been investigated. Here we show that a normal adult tissue-specific stem cell molecular phenotype is commonly activated in epithelial cancer stem cells and for the first time provide evidence that enrichment in cancer stem cells-specific molecular signatures are correlated to highly aggressive tumor phenotypes in human epithelial cancers.

Differential migratory response of U-2 OS osteosarcoma cell to the various forms of platelet-derived growth factor

U-2 OS osteosarcoma cells are mesenchymal-derived transformed cells spontaneously expressing both platelet-derived growth factor (PDGF) A- and B-chain genes, and releasing PDGF AA dimers in culture. Using modified Boyden chemotactic chambers, platelet-purified PDGF was shown to be a chemoattractant for U-2 OS cells. More specifically, U-2 OS cells migrated in the presence of PDGF AB and BB dimers but not in the presence of PDGF AA dimers. This pattern of response was similar to that observed with human fibroblasts and this similarity is consistent with the fact that U-2 OS cells express PDGF receptor alpha- and beta-subunits in a similar fashion to human fibroblasts.