Antitumoral effects of squamocin on parental and multidrug resistant MCF7 (human breast adenocarcinoma) cell lines.

The antiproliferative effects of squamocin, one of the easiest annonaceous acetogenins to obtain, were studied in the parental (MCF7-S) and the multidrug resistant (MCF7-R) human breast adenocarcinoma cell lines. Squamocin inhibited proliferation of both cell lines identically, by blocking the cell cycle in the G1-phase. This inhibition was reversible in the long term. Squamocin decreased the ATP pool in both MCF7 cell lines, but did not seem to induce apoptosis. Cytotoxic activity of adriamycin was not restored in MCF7-R Pgp expressing cells by squamocin addition.     

Vectorisation of doxorubicin in nanospheres and reversion of pleiotropic resistance of tumor cells

A multidrug resistance human cell line (Dox-R-MCF7), originating from mammary adenocarcinoma was compared to the drug sensitive parent line (MCF7) to determine whether or not the use of doxorubicin-loaded biodegradable nanospheres (NS-Dox) could circumvent drug resistance. The Dox-R-MCF7 line was shown to resist free doxorubicin (Dox) as the 50% lethal dose for them was 150 times higher than for the sensitive cell-line. Isohexylcyanoacrylate nanospheres, porous matrices of biodegradable innocuous polymer, diameter 300 nm, were loaded with doxorubicin. Free Dox, NS-Dox and Dox-free polymer (NS) were added to the culture medium for 6 hrs. In terms of 50% lethal dose, NS-Dox were cytotoxic for the resistant cell line to an identical extent as for the sensitive parent line. Dox-free nanospheres alone or mixed with free-Dox were noncytotoxic for the resistant line. Drug targetting could be of main importance to overcome multidrug resistance.     

On-line reversed-phase liquid chromatography hydride generation emission spectrometry: speciation of arsenic in urine of patients intravenously treated with As2O3

Hydride generation inductively coupled plasma–atomic emission spectrometry (HG ICP–AES) was used as a continuous detection system for the determination of arsenic in the eluate from a high-performance liquid chromatographic (HPLC) system. Four arsenic species [arsenite As(III), arsenate As(V), monomethylarsonate (MMA), and dimethylarsinate (DMA)] present in the urine samples of patients treated intravenously with arsenite, were analyzed separately by HPLC–HG-ICP–AES using a non-polar C₁₈ column. This analytical method allowed the sensitive determination of the arsenic species in the submicrogram per liter range. Urine samples collected on different days after arsenite administration were found to contain arsenite predominantly – monomethylarsonate and dimethylarsinate were also detected.     

Transglutaminase activity and putrescine-binding capacity in cloned cell lines with different metastatic potential

An inverse correlation was found between cellular transglutaminase activity and metastatic potential of four cloned cell lines derived from a primary nickel-induced rat rhabdomyosarcoma. Cellular transglutaminase activity as assessed with endogenous cellular protein or exogenous methylated casein was greatest in the clone F9-4/8 which is the least metastasizing. When the putrescine-binding capacity of one cellular derived protein - fibronectin - was examined with exogenous transglutaminase, it was found that the fibronectin derived from the clone F9-4/8 showed the lowest binding capacity compared with those from the other clones. However, when the overall binding capacity of cellular proteins from each cell line was examined no differences could be detected. The results are discussed in the light of the well-known role of fibronectin in cellular adhesion.     

Synergistic effects of temperature and light affect the relationship between Taonia atomaria and its epibacterial community: a controlled conditions study

In the context of global warming, this study aimed to assess the effect of temperature and irradiance on the macroalgal Taonia atomaria holobiont dynamics. We developed an experimental set-up using aquaria supplied by natural seawater with three temperatures combined with three irradiances. The holobiont response was monitored over 14 days using a multi-omics approach coupling algal surface metabolomics and metabarcoding. Both temperature and irradiance appeared to shape the microbiota and the surface metabolome, but with a distinct temporality. Epibacterial community first changed according to temperature, and later in relation to irradiance, while the opposite occurred for the surface metabolome. An increased temperature revealed a decreasing richness of the epiphytic community together with an increase of several bacterial taxa. Irradiance changes appeared to quickly impact surface metabolites production linked with the algal host photosynthesis (e.g. mannitol, fucoxanthin, dimethylsulfoniopropionate), which was hypothesized to explain modifications of the structure of the epiphytic community. Algal host may also directly adapt its surface metabolome to changing temperature with time (e.g. lipids content) and also in response to changing microbiota (e.g. chemical defences). Finally, this study brought new insights highlighting complex direct and indirect responses of seaweeds and their associated microbiota under changing environments.