Polyploid formation via chromosome duplication induced by CTP:phosphocholine cytidylyltransferase deficiency and Bcl-2 overexpression: identification of two novel endogenous factors

Cytokinesis regulators as potential diagnostic and therapeutic biomarkers for human hepatocellular carcinoma

Cytokinesis, the final step of mitosis, is critical for maintaining the ploidy level of cells. Cytokinesis is a complex, highly regulated process and its failure can lead to genetic instability and apoptosis, contributing to the development of cancer. Human hepatocellular carcinoma is often accompanied by a high frequency of aneuploidy and the DNA ploidy pattern observed in human hepatocellular carcinoma results mostly from impairments in cytokinesis. Many key regulators of cytokinesis are abnormally expressed in human hepatocellular carcinoma, and their expression levels are often correlated with patient prognosis. Moreover, preclinical studies have demonstrated that the inhibition of key cytokinesis regulators can suppress the growth of human hepatocellular carcinoma. Here, we provide an overview of the current understanding of the signaling networks regulating cytokinesis, the key cytokinesis regulators involved in the initiation and development of human hepatocellular carcinoma, and their applications as potential diagnostic and therapeutic biomarkers.

De novo lipogenesis at the mitotic exit is used for nuclear envelope reassembly/expansion. Implications for combined chemotherapy

Mitosis has been traditionally considered a metabolically inactive phase. We have previously shown, however, that extensive alterations in lipids occur as the cells traverse mitosis, including increased de novo fatty acid (FA) and phosphatidylcholine (PtdCho) synthesis and decreased lysophospholipid content. Given the diverse structural and functional properties of these lipids, we sought to study their metabolic fate and their importance for cell cycle completion. Here we show that FA and PtdCho synthesized at the mitotic exit are destined to the nuclear envelope. Importantly, FA and PtdCho synthesis, but not the decrease in lysophospholipid content, are necessary for cell cycle completion beyond G₂/M. Moreover, the presence of alternative pathways for PtdCho synthesis renders the cells less sensitive to its inhibition than to the impairment of FA synthesis. FA synthesis, thus, represents a cell cycle-related metabolic vulnerability that could be exploited for combined chemotherapy. We explored the combination of fatty acid synthase (FASN) inhibition with agents that act at different phases of the cell cycle. Our results show that the effect of FASN inhibition may be enhanced under some drug combinations.

Effect of fungicide Euparen Multi (Tolylfluanid) on the induction of chromosomal aberations in cultivated bovine lymphocytes

The effect of the fungicide Euparen Multi (containing 50% tolylfluanid) was investigated on the induction of chromosomal aberrations (CA) in cultured bovine peripheral lymphocytes. Cultures from two healthy donors were treated with tolylfluanid-based fungicide at concentrations ranging from 1.7 to 17.5 μg/ml for the last 24 and 48 hours of cultivation. Conventional cytogenetic method (CA assay) with Giemsa staining as well as fluorescence in situ hybridization (FISH) with whole bovine chromosomes 1 and 5 painting probes were used in the experiment. In the CA assay, no clastogenic effect of the fungicide was found after Euparen Multi treatment for 24 hours. On the contrary, significant elevation in polyploidy induction was observed with dose-dependence in one of the donors. Using prolonged time of exposure to the fungicide (the last 48 h of the cultivation), a slight clastogenic effect was detected at the doses of 8.75 and 17.5 μg/ml (P < 0.05, P < 0.01, respectively) in donor 1 and at the dose of 8.75 μg/ml (P < 0.05) in donor 2. The highest doses tested caused reduction of the mitotic indices (MI) (P < 0.05, P < 0.01) in both donors as well as both treatment times. The evaluation of stable structural aberrations in lymphocytes by two-colour FISH (48 h exposure) using bovine chromosome painting probes revealed the presence of nonreciprocal translocations at two examined concentrations (3.5 μg/ml and 8.75 μg/ml).

Expression of cell kinetics and death during monocyte-macrophage differentiation: effects of Actinomycin D and Vinblastine treatments

The different effects of two cytostatic drugs, Actinomycin D and Vinblastine, during macrophage-like differentiation induced in THP-1 monocytic cell line by phorbol ester phorbol 12-myristate 13-acetate (PMA) (6, 30, and 60 nM), were studied by morpho-cytochemical approaches. In PMA-unstimulated monocytic cells, the cytostatic effects of Actinomycin D (an antimetabolic drug) were characterized by a drastic reduction of the G2/M cells accompanied by dramatic death of the G1 cells; on the contrary, Vinblastine (a microtubule-depolymerizating drug) induced an accumulation of the G2/M cells with the appearance of aneugenic micronuclei and scarce cell death mainly from the G1 cells. After 60 nM PMA stimulation, the culture was mostly composed by macrophagic cells characterized by low proliferation and the appearance of mono-/binucleated polyploid cells; in this condition, the cytotoxicity of the two drugs, more effective for Vinblastine, induced cell death in the different ploidy classes (2c, 4c, 8c). Cell death appeared to be of apoptotic nature, but with some morpho-phenotypic differences due to the action mechanism of the drugs and dependent on cell culture growth and differentiation. As a consequence of the different block-action of the two drugs on the cell cycle phases and in relation to the different subcellular targets, the effects changed during the transition from not-adhering/proliferating monocytes to adhering/low-proliferating differentiated macrophages.