Recent advances in the role of AMP-activated protein kinase in metabolic reprogramming of metastatic cancer cells: targeting cellular bioenergetics and biosynthetic pathways for anti-tumor treatment.

Growing data indicate that tumor progression and metastasis is dependent on the reprograming of cellular metabolism. Rapidly growing cancer cells undergo metabolic stress in a harsh microenvironment. AMP-activated protein kinase (AMPK) is an energy sensing factor that regulates bioenergetics and biosynthetic pathways within the cell, but its role under metastasis is in dispute. The best studied phenotype of cancer cells is aerobic glycolysis (the Warburg effect), an increased catabolism of glucose to lactate. However, glycolysis and mitochondrial oxidative phosphorylation may operate simultaneously in cancer cells. Many tumors may switch between these pathways accordingly to the current requirements. The alterations in metabolism of cancer cells combined with the overexpression of oncogenes (c-Myc) and transcription factors (Hypoxia-inducible factor 1a) confer a great advantage to malignant cells to avoid reactive oxygen species induced apoptosis. The determination of the role of AMPK network in metabolic reprogramming of metastatic cancer cells may help to identify the selective molecular targets for efficient anti-cancer therapies. In this review, we discuss the implications of AMPK activation in metabolic reprogramming of cancer cells and we present several potential therapeutic strategies targeting cancer cell metabolism. AMPK activator, biguanide metformin, either alone or in combination with other drugs, may selectively modulate signaling pathways, expresses the chemopreventive potential and can be used in current anti-cancer approaches. However, the ambiguous data suggest that the activation of AMPK may induce multiple effects and thus potential therapeutic anti-cancer approach should be carefully considered in relation to metabolic network of cancer cell signaling and other determinants such tumor stage and origin as well.

Transmission of the Aegilops ovata chromosomes carrying gametocidal factors in hexaploid triticale (×Triticosecale Wittm.) hybrids.

The main aim of this work was to induce the chromosome rearrangements between Aegilops ovata (UUMM) and hexaploid triticale (AABBRR) by expression of the gametocidal factor located on the chromosome 4M. The Aegilops ovata × Secale cereale (UUMMRR) amphiploids and triticale 'Moreno' were used to produce hybrids by reciprocal crosses. Chromosome dynamics was observed in subsequent generations of hybrids during mitotic metaphase of root meristems and first metaphase of meiosis of pollen mother cells. Chromosomes were identified by genomic in situ hybridisation (GISH) and fluorescence in situ hybridisation (FISH) using pTa71, pTa791, pSc119.2 and pAs1 DNA probes. It has been shown that the origin of the genetic background had an influence on Aegilops chromosome transmission. Moreover, it has been reported that the preferential transmission of chromosome 4M appeared during both androgenesis and gynogenesis. It is also hypothesised that the expression of the triticale Gc gene suppressor had an influence on the semi-fertility of hybrids but did not inhibit the chromosome rearrangements. This paper also describes the double haploid production, which enabled to obtain plants with two identical copies of triticale chromosomes with translocations of Aegilops chromatin segments.

In vitro expansion of human megakaryocytes as a tool for studying megakaryocytic development and function.

Research on normal human megakaryopoiesis has been limited by technical problems in obtaining megakaryocytic cells in sufficient quantities for experimental purposes. We describe here an ex vivo serum-free liquid culture system to expand normal human megakaryoblasts from purified bone marrow-, cord blood- or peripheral blood-derived CD34(+) cells. The early megakaryocytic cells are expanded in the presence of recombinant thrombopoietin (TpO) and interleukin-3 (IL-3), and if necessary further purified by employing anti-CD61 immunomagnetic beads. Our expansion system generates normal human megakaryoblasts in quantities sufficient to perform various functional studies on these cells as well as to isolate from them proteins and mRNA for molecular analysis. Megakaryocytic cells isolated from these cultures (i) express several markers characteristic of this lineage (CD41, CD61, CD62 P, CXCR-4, PAR-1, etc.), (ii) respond by calcium flux and phosphorylation of various intracellular proteins to stimulation by thrombin and (iii) adhere to fibrinogen and vitronectin. However, human megakaryoblasts derived from the cultures supplemented with TpO + IL-3, in contrast to murine megakaryocytic cells cultured under similar conditions, display poor polyploidization and do not release platelets. Since IL-3 has been reported to inhibit final maturation of megakaryocytic cells, we recently modified our expansion strategy. In this new approach CD34(+) cells are first expanded for 11 days in the presence of TpO + IL-3. Then megakaryoblasts derived are expanded for an additional 7 days supplemented with TpO only. We found that megakaryocytic cells expanded in this 'two step culture' model are more differentiated, are polyploid and release platelets. The model described here provides normal human megakaryoblasts in adequate numbers, to study megakaryopoiesis and megakaryocyte function.