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International audience; New immunocompetent cancer models are still needed for the identification and preclinical validation of novel therapeutic targets in colorectal cancer.The aim of this study was to evaluate the implantation rate of CT-26, a type of murine colorectal cancerous cells, on the peritoneum site according to theinjection site. The tumor graft efficiency was compared in 4 grafting methods according to the PCI score and using bioluminescence imaging in a syngeneicimmunocompetent murine strain. Tumoral growth was then followed by bioluminescence, over 15 days post-grafting and nodules that have been exposedto 10 ns pulses were analyzed by histology. In vitro CT-26 cells were also studied by flow cytometry for their sensitivity to nsPEFs and chemotherapeutic drugs(Mitomycin, Oxyplastin): survival, mitochondrial potential and permeabilization. In parallel, peritoneal tumoral tissue was observed by multiphotonmicroscopy in order to evaluate the tumor microenvironment. We observed in vitro a strong dose-dependent effect of nsPEF on cell viability, cell death (DAPI,Annexin V), calcium signaling (Fluo-4) and permeabilization (Yo-Pro). In vivo nsPEF exposure of PM nodules shows also dramatic cells death and proliferativeinhibition, more efficiently and faster than the ones observed after addition of chemotherapeutic drugs (Mitomycin, Oxyplastin). more...

International audience; The use of chemotherapy drugs before or after surgery is common in human pancreatic cancer. This type of cancer has a very poor prognosis and leads to a rapid deterioration of the general state of the patient, limiting the use of chemotherapies, and justifying the development of alternative and innovating treatments, as bioelectric therapies. Methods Gemcitabine, used as palliative chemotherapy in pancreatic cancer, has been tested in vitro in combination with nanosecond pulsed electric field (~10 ns) on murine pancreatic cancer cells KPC 4580. After obtaining the IC 50, the KPC 4580 were treated with 10, 100, 500 and 1000 pulses of 10 ns duration and electric field of 10 kV/cm in a cuvet exposure system, alone, or before treatment to gemcitabine at 0.15 µM or 15 µM during 24h. Apoptosis rate was evaluated by fluorescence using a flow cytometer (AnnexinV, Muse® Cell Analyzer, Millipore). The cells were then plated in wells and cell nuclei were labeled by DAPI to estimate the survival rate by fluorescence microscopy. A MTT assay was also performed to test the in vitro cytotoxicity of the treatments. Results The gemcitabine chemotherapy doses (0.15 and 15 µM) alone have been associated with 24h cell survival of 65% and 50% respectively. A strong decrease in cell survival at 24 hours is also observed with the use of nsPEF alone, with a dosedependent relation according to the number of pulses. Interestingly, the association of nsPEF with low-dose cytotoxic gemcitabine regains a synergy of action and increases cell death. The cell death profile with AnnexinV/7-AAD study finds apoptosis as a major mechanism of cell death for both cell groups, regardless of their exposure to chemotherapy. Conclusion The combination of nsPEF with low doses of cytotoxic drugs has a synergistic effect on cell death in vivo for pancreatic cancer cells, a cancer that is classically resistant to therapeutic drugs or leading to poor prognosis for patients. The combination of both reduced drug doses and nsPEF treatments could limit side effect and toxicity of chemotherapy, which may provide improved treatment for patients than either treatment alone. more...

International audience; Animal cancer models play an important role to study the development and progression of peritoneal carcinomatosis and to assess new treatments The aim of this study was to compare 4 mouse models of colorectal peritoneal carcinomatosis (PC) in order to obtain whether a limited or extensive peritoneal carcinomatosis. more...

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Array-comparative genomic hybridization (aCGH) was done in 64 small supernumerary marker chromosomes (sSMC). The studied sSMC-specific DNA was derived from glass-needle based microdissection, avoiding by that the problem of mosaicism as present in ~40% of corresponding patients. Furthermore, a detailed analysis of overall 128 characterized breakpoints in non-heterochromatic chromosomal regions of sSMC was done. It turned out that 82.8% and 53.1% of the breakpoints are located within copy number variant regions and regions with segmental duplications, respectively. 6.3% of the breakpoints locate within sequence gaps, making an overall of 90.6% of association of non heterochromatic sSMC-related breakpoints with ‘critical genome structure’. Moreover, approximately three quarters of the breakpoints were concordant with fragile sites. Still, there was a 7.0% overlap of the observed breakpoints and interspersed telomeric sequences (ITS), but only two out of 128 breaks were within an olfactory receptor gene family region. Overall, we present the largest ever done aCGH study in sSMC and provide evidence for hotspots involved in sSMC formation. Deduced from that data it was also possible to characterize regions causing clinical problems if present additionally, for all human chromosomes except for chromosomes 6, 13, X and Y. more...

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Primary neuronal cultures from mammalian fetal brains are widely used for morphological, biochemical and pharmacotoxicological studies. The usefulness of relatively pure neuronal cultures are now demonstrated for such studies. We have compared the neuronal survival and differentiation, the synaptophysin expression and the glial cell percentage in primary neuronal cultures using two different media: a M1 medium containing 10 % fetal calf serum and a M2 medium supplemented with hormones, ions and chemicals. Our study demonstrates that the M2 medium (a serum-free defined medium) is associated with an increased survival at 14 days of culture, an earlier neuronal differentiation and synaptophysin expression in cell bodies and neurites as it was confirmed by immunocytochemical and confocal laser microscopic studies. more...