Christophe Tomasoni

Cultivated microalgae and the carotenoid fucoxanthin from Odontella aurita as potent anti-proliferative agents in bronchopulmonary and epithelial cell lines

The antiproliferative activities of several extracts from cultivated microalgae in France have been studied against bronchopulmonary and epithelial cell lines, respectively (A549, NSCLC-N6 and SRA 01/04). The algal extracts, of Diatomae (Odontella aurita, Chaetoseros sp.), as well as of Haptophyceae: Isochrisys aff. galbana, appeared as the most active among all the assayed species, expressing a broad spectrum of in vitro antiproliferative activity of well-differentiated pathologic cells such as NSCLC-N6 by terminal differentiation. Bio-guided fractionation of the above referred extracts, led us to the isolation, of the carotenoid fucoxanthin. Fucoxanthin has been structurally determined, through modern spectral means and has been studied separately for its activities.

Synthesis and antiproliferative activity of benzofuran-based analogs of cercosporamide against non-small cell lung cancer cell lines.

A novel series of 3-methyl-1-benzofuran derivatives were synthesized and screened in vitro for their antiproliferative activity against two human NSCLC cell lines (NSCLC-N6 mutant p53 and A549 wild type p53). Most promising compounds presented a structural analogy with the west part of cercosporamide, a natural product of biological interest. In particular, compounds 10, 12 and 31 showed cytotoxic activities at micromolar concentrations (IC₅₀ < 9.3 μM) and compounds 13, 18 and 32 displayed moderate IC₅₀ values (25-40 μM).

miRNAs, a potential target in the treatment of Non-Small-Cell Lung Carcinomas

Lung cancer is a serious public health problem and Non Small Cell Lung Carcinoma, NSCLC, is particularly resistant to current treatments. So it is important to find new strategies that are active against NSCLC. miRNA is implicated in cancer and may be implicated in NSCLC. Our team has been working on two genes HEF1, a gene implicated in different functions of cell cycle and B2, a large non-coding RNA (nc RNA). These two genes have the same localisation: chromosome 6 and locus p24-25. nc RNA B2 may be involved in the regulation of HEF1. Firstly, we examine a bank of different human miRNAs known to interact with exons of HEF1. HEF1 and B2 were overexpressed in vitro by treating NSCLC-N6 with the cytostatic molecule A190, and carried out qRT-PCR for the expression of miRNA. Secondly, using specific software, we sought for structures originating from the B2 RNA sequence which might interact with HEF1 and assessed their expression. This strategy enabled us to confirm firstly that known miRNAs that can interact with exons of HEF1 are expressed in NSCLC-N6 cells. More precisely this strategy highlighted overexpression of one miRNA, hsa-miR-146b, listed in miRbase. The second step of the studies highlighted the expression of miRNA, potentially sequences originating from B2 in the NSCLC-N6. This miRNA overexpressed might be one of the regulators of the gene HEF1 and consequently implies on the carcinogenesis of lung cancer. So in the future it could be a potential and an innovative way to find a new strategy for the treatment of lung cancer.

Up-regulation of a novel mRNA (NY-CO-1) involved in the methyl 4-methoxy-3-(3-methyl-2-butenoyl) benzoate (VT1)-induced proliferation arrest of a non-small-cell lung carcinoma cell line (NSCLC-N6)

It is now well known that treatment of tumors, especially non‐small‐cell lung cancer (NSCLC), remains limited and it is urgent to develop strategies that target tumor cells and their genetic features. In this regard, our work is about genetic modifications arising in an in vitro NSCLC cell line after treatment with a chemical substance, methyl 4‐methoxy‐3‐(3‐methyl‐2‐butenoyl) benzoate (VT1). First, we showed that VT1 induces arrest of proliferation by blocking cells in the G1 phase of the cell cycle. Second, we use “differential display” strategy to clarify the genetic mechanisms involved in this proliferation arrest. A novel mRNA, NY‐CO‐1 (New‐York Colon 1), of unknown function showed up‐regulated expression after treatment. Application of “antisense” strategy confirmed this novel mRNA induction was effectively linked to growth arrest. Therefore, these data provide new information about mechanisms participating in arrest of proliferation of tumor cells and open new ways of treatment to target tumor growth.

TP53 transcription factor for the NEDD9/HEF1/Cas-L gene: potential targets in Non-Small Cell Lung Cancer treatment

Lung cancer is a serious public health problem. Although there has been significant progress in chemotherapy, non-small cell lung cancer is still resistant to current treatments, primarily because of the slow rate of cell development. It is thus important to find new molecules directed against targets other than proliferation agents. Considering the high proportion of mutant proteins in tumor cells, and the high rate of mutation of the TP53 gene in all cancers, and in NSCLC in particular, this gene is a perfect target. Certain new molecules have been shown to restore the activity of mutated p53 protein, for example PRIMA-1, which reactivates the His273 mutant p53. In a previous study, we presented triazine A190, a molecule with a cytostatic activity that blocks cells in the G1 phase and induces apoptosis. Here, we show that A190 not only restores mutant p53 activity, but also induces an overexpression of the NEDD9 gene, leading to apoptotic death. These findings might offer hope for the development of new targeted therapies, specific to tumor cells, which spare healthy cells.

Activation of EGFR by small compounds through coupling the generation of hydrogen peroxide to stable dimerization of Cu/Zn SOD1

Activation of cell signaling by reactive chemicals and pollutants is an important issue for human health. It has been shown that lipophilic nitro-benzoxadiazole (NBD) compounds rapidly move across the plasma membrane and enhance Epidermal Growth Factor Receptor (EGFR) tyrosine phosphorylation in cancer cells. Unlike ligand-dependent activation, the mechanism of this induction relies on the generation of hydrogen peroxide, which is involved in the activation of the catalytic site of the receptor and the inactivation of protein tyrosine phosphatase PTP-1B. Production of H2O2 during redox transformation of NBD compounds is associated with the transition of a monomeric form of Cu/Zn superoxide dismutase 1 (SOD1) to stable dimers. The highly stable and functionally active SOD1 dimer, in the absence of adequate activities in downstream reactions, promotes the disproportionate production and accumulation of intracellular hydrogen peroxide shortly after exposure to NBD compounds. The intrinsic fluorescence of small compounds was used to demonstrate their binding to SOD1. Our data indicate that H2O2 and concomitantly generated electrophilic intermediates behave as independent entities, but all contribute to the biological reactivity of NBD compounds. This study opens a promising path to identify new biomarkers of oxidative/electrophilic stress in the progression of cancer and other diseases.

Study of antiproliferative effects of synthetic substances against lens epithelial cell line (SRA 01/04).

A cataract is a clouded area of the eye, which impairs vision. Cataracts can be caused by a natural hardening of the lens in the elderly, or may be the result of eye injury. However there is a treatment by extracapsular surgery, almost 50% of operations are followed by another posterior capsule opacification. This secondary cataract is due to abnormal cellular proliferation. Pharmacologic inhibition of this cellular proliferation would be a very promising treatment. The objective of our study is to test some antiproliferative drugs, less toxic than those currently used such as 5-FU or mytomycin C. We have investigated the in vitro effects of several molecules (V0 and its derivatives) on a proliferative human lens epithelial cell line (SRA 01/04). During a first step, we have measured the IC50 of each molecule. After this first screening, we have studied the kinetic of the cell growth with or without the molecules at different concentration. Then, flow cytometry was used to determine the phase of the cell cycle at which the proliferation stopped. This study has shown that 3 molecules V19, V1, and A190 have an interesting profile in vitro and were selected to analyze their mechanism of action.