Discovery of a new molecule inducing melanoma cell death: dual AMPK/MELK targeting for novel melanoma therapies

In the search of biguanide-derived molecules against melanoma, we have discovered and developed a series of bioactive products and identified the promising new compound CRO15. This molecule exerted anti-melanoma effects on cells lines and cells isolated from patients including the ones derived from tumors resistant to BRAF inhibitors. Moreover, CRO15 was able to decrease viability of cells lines from a broad range of cancer types. This compound acts by two distinct mechanisms. First by activating the AMPK pathway induced by a mitochondrial disorder. Second by inhibition of MELK kinase activity, which induces cell cycle arrest and activation of DNA damage repair pathways by p53 and REDD1 activation. All of these mechanisms activate autophagic and apoptotic processes resulting in melanoma cell death. The strong efficacy of CRO15 to reduce the growth of melanoma xenograft sensitive or resistant to BRAF inhibitors opens interesting perspective.Subject terms: Melanoma, Cell death     

Two types of cyclic GMP binding site associated with the cyclic AMP-dependent protein kinase from lymphocytes

Low- and high-affinity binding sites for cyclic GMP were found to be associated with the cyclic AMP-dependent protein kinase (ATP: protein phosphotransferase, EC 2.7.1.37) from human tonsillar lymphocytes, but neither of them was identical with the cyclic AMP binding site.The enzyme activated by cyclic GMP phosphorylated the same site of calf thymus H2b histone as the cyclic AMP activated enzyme; however, more complex kinetics of activation were found with cyclic GMP.Two classes of cyclic GMP binding site were demonstrated by kinetic analysis of cyclic [³H]GMP binding in the enzyme preparations eluted by 0.1 M potassium phosphate (pH 7.0) from DEAE cellulose. The high-affinity cyclic GMP binding site (K_d about 44 · 10^?8 M belonged to some complex form of the protein kinase, as evidenced by the mutual inhibition of cyclic AMP binding and high affinity cyclic GMP binding. However, the high-affinity cyclic GMP binding site disappeared on Sephadex G-100 gel chromatography of the enzyme preparation, whereas the cyclic AMP binding activity was recovered quantitively as separate fractions. The low-affinity cyclic GMP binding site (K_d 2–5 · 10^?6 M) was demonstrated by the inhibitory effect of 10^?5 M cyclic GMP on cyclic AMP binding in each cyclic AMP binding fraction obtained by gel chromatography. However, cyclic AMP did not inhibit the binding of cyclic GMP to the low-affinity binding site.     

Effect of transgenic alfalfa plants with introduced gene for Alfalfa Mosaic Virus coat protein on rhizosphere microbial community composition and physiological profile

The aim of this study was to evaluate the effect of transgenic alfalfa (Medicago sativa L.) plants, in comparison to their non-transgenic counterpart, on the density and physiological profiles of aerobic bacteria in the rhizosphere. Plants of transgenic alfalfa expressing the AMVcp-s gene coding for Alfalfa Mosaic Virus coat protein were cultivated in a climatic chamber. Two methods were used to determine the microbial diversity in rhizospheres of transgenic plants. First, the cultivation-dependent plating method, based on the determination of the density of colony-forming bacteria, and second, a biochemical method using the Biolog™ system, based on the utilization of different carbon sources by soil microorganisms. Statistically significant differences in densities of rhizospheric bacteria between transgenic and non-transgenic alfalfa clones were observed in ammonifying bacteria (GTL4/404-1), cellulolytic bacteria (GTL4/404-1, GTL4/402-2, A5-3-3), rhizobial bacteria (GTL4/402-2), denitrifying bacteria (A5-3-3) and Azotobacter spp. (GTL4/402-2). The highest values of substrate utilization by microbial communities and average respiration of C-sources were determined in non-transgenic alfalfa plants of the isogenic line SE/22-GT2. Carbohydrates, carboxylic acids and amino-acids were the most utilized carbon substrates by both Gram-negative and Gram-positive bacteria. Both, the community metabolic diversity and the utilization of C-sources increased in all alfalfa lines with culture time and regardless of transgenic or non-transgenic nature of lines.     

CHLOROPHYLL LEVELS AND LEAF ULTRASTRUCTURE AS ECOTYPIC CHARACTERS IN XANTHIUM STRUMARIUM L.

Comparison of six different populations of Xanthium strumarium grown under controlled laboratory conditions revealed a general pattern of greater chlorophyll levels with increase in latitude of origin. Indications of ultrastructural differences were found, with plants containing greater chlorophyll levels having more chloroplasts with greater membrane development compared to plants of this species from more southern or lower latitude habitats.