Binding features of BCL2-targeted oligodeoxynucleotides with K562 cells

Delivery of various oligodeoxynucleotides into cells is mediated by binding to certain surface proteins followed by receptor-mediated endocytosis. Moreover, oligonucleotides are able to provoke perturbation of cell surface proteins and growth factor receptors among them. Here we described binding sense BCL2 oligodeoxynucleotide targeted to translation start of BCL2 mRNA (ODN) with K562 cells. At low concentration ODN bound efficiently with K562 and penetrated into the cells via binding cell surface with rather high affinity and priming new binding sites. The loose binding constant at 4 degrees C was 1.8 x 10(9) M(-1) both for binding ODN in solution and ODN-associated liposome. The number of loose binding sites under both treatments was rather high: 4.6 to 6.6 pmoles per 10(6) cells. The extent of ODN penetration into the cells showed higher potential site numbers than initially seen and reached 8.6 pmoles per 10(6) cells for four hours incubation at 37 degrees C.     

Binding and transfer of an oligodeoxynucleotide containing the translation initiation site of the <Emphasis Type="Italic">BCL2</Emphasis> mRNA into K562 cells

A study was conducted of the interaction of an octadecameric oligodeoxynucleotide (dON) containing the BCL2 mRNA translation start with K562 cells. Both in solution and upon lipofection, the binding of dON used at a low concentration (30 nM) at 37°C involved two steps: saturating surface binding with the cell membrane and internalization. Three phases were revealed in the dynamics of internalization: the extent and rate of internalization increased during the first hour of incubation; decreased during the second hour; and then increased again, which was assumed to reflect the priming of new dON-binding sites. The binding constant and the number of binding sites were estimated at 10°C (the conditions preventing internalization) by consecutive dissociation of dON-cell complexes formed in 1 h at 37°C. Incubation of dON with cells led to the priming of new high-affinity binding sites and an increase of the binding constant to a level characteristic of high-affinity ligand-receptor interactions (10⁹ M^–1). High-affinity receptor-mediated binding preceded internalization of dON. Lipofection increased the binding constant and the number of binding sites severalfold but had virtually no effect on the temporal pattern and the extent of dON internalization.__________Translated from Molekulyarnaya Biologiya, Vol. 39, No. 2, 2005, pp. 235–244.Original Russian Text Copyright © 2005 by Timofeev, Borovkova, Nydenova, Akhlynina, Shmarov, Grineva.     

Apoptosis and neutrophils in the regulation of Ph-positive myeloid cell proliferation and differentiation ex vivo

Ex vivo proliferation and differentiation of Philadelphia chromosome-positive (Ph⁺) human myeloid cells (Ph+ cells) from chronic myeloid leukemia (CML) proceed via alternation stages of cell proliferation and neutrophil maturation. To regulate them, apoptosis is alternately blocked or induced with the help of neutrophils and expression of bcr/abl, bax, and bcl2. The regulation of apoptosis in main types of Ph⁺ cells depends on the alternation of (1) Ph⁺ cell proliferation and (2) neutrophil maturation and may follow two pathways. One consists in alternating blockages and inductions of apoptosis with initial maturation and subsequent proliferation under alternation stages as (2)-(1)-(2) and has not been described as yet. Neutrophil accumulation blocks apoptosis. As neutrophils are depleted, apoptosis is induced again. Its block accelerates proliferation with a new accumulation of neutrophils, which is followed by regular neutrophil death and a new induction of apoptosis. The way optimizes the proliferation efficiency (P/D index) with a regular alternation of maturation and proliferation, allowing the cycle of proliferation and differentiation to be completed. In another way, the alternation starts with proliferation as (1)-(2)-(1) at a lower neutrophil content) and leads to resistant decrease of the maximal apoptosis level by a factor of 3–8 as compared with (2)-(1)-(2) alternation. A stable block of apoptosis is observed in cells with prolonged stages of proliferation and maturation, leading to an accumulation of blasts and myelocytes with elevated bcr/abl expression and expression of bcl2 > bax. A stable block of apoptosis is associated with CML progression and in Ph⁺ cell lines. Cells follow the first pathway of the apoptotic regulation in chronic-phase CML. Ex vivo cultivation of Ph⁺ cells from individual CML patients was assumed to provide for a more exact diagnosis of the CML phase and optimizing the treatment.     

Long non‐coding RNAs in melanoma

Melanoma is the most lethal cutaneous cancer with a highly aggressive and metastatic phenotype. While recent genetic and epigenetic studies have shed new insights into the mechanism of melanoma development, the involvement of regulatory non‐coding RNAs remain unclear. Long non‐coding RNAs (lncRNAs) are a group of endogenous non‐protein‐coding RNAs with the capacity to regulate gene expression at multiple levels. Recent evidences have shown that lncRNAs can regulate many cellular processes, such as cell proliferation, differentiation, migration and invasion. In the melanoma, deregulation of a number of lncRNAs, such as HOTAIR, MALAT1, BANCR, ANRIL, SPRY‐IT1 and SAMMSON, have been reported. Our review summarizes the functional role of lncRNAs in melanoma and their potential clinical application for diagnosis, prognostication and treatment.     

Protective effect of bixin on carbon tetrachloride-induced hepatotoxicity in rats

Background

The liver is an important organ for its ability to transform xenobiotics, making the liver tissue a prime target for toxic substances. The carotenoid bixin present in annatto is an antioxidant that can protect cells and tissues against the deleterious effects of free radicals. In this study, we evaluated the protective effect of bixin on liver damage induced by carbon tetrachloride (CCl₄) in rats.

Results

The animals were divided into four groups with six rats in each group. CCl₄ (0.125 mL kg^-1 body wt.) was injected intraperitoneally, and bixin (5.0 mg kg^-1 body wt.) was given by gavage 7 days before the CCl₄ injection. Bixin prevented the liver damage caused by CCl₄, as noted by the significant decrease in serum aminotransferases release. Bixin protected the liver against the oxidizing effects of CCl₄ by preventing a decrease in glutathione reductase activity and the levels of reduced glutathione and NADPH. The peroxidation of membrane lipids and histopathological damage of the liver was significantly prevented by bixin treatment.

Conclusion

Therefore, we can conclude that the protective effect of bixin against hepatotoxicity induced by CCl₄ is related to the antioxidant activity of the compound.     

Cancer-testis gene expression profile in human melanoma cell lines

A growing number of evidence indicates that cancer-testis antigens (CTA) can be used as specific targets for immune therapy of malignant melanoma. The aim of this study was to provide a basis for selecting the most suitable CTA by analyzing the mRNA expression profile of genes encoding CTA in melanoma cell lines. We used a real-time quantitative PCR to measure the expression level for the following genes: GAGE1, NY-ESO-1, MAGEA1, PASD, SCP1, SEMG1, SPANXA, SSX1, and PRAME. The objects of study were cell lines mel P, mel Si, mel Mtp, mel Il, mel Hn, mel Ibr, and mel Kor obtained from patients diagnosed with disseminated melanoma. We established that the highest frequency of occurrence and the highest expression level had the following genes: GAGE1, NY-ESO-1, MAGEA1, SCP1, SPANXA, SSX1, and PRAME. Their mRNA translation products can be promising candidates for immunotherapy.     

Effect of hydrophobic compounds on rRNA synthesis in intact cells and isolated nuclei

Papaverine, cycloheximide, 2,4-dinitrophenol (DNP) and actinomycin D at low concentration have been shown to suppress selectively rRNA synthesis in Ehrlich ascite carcinoma cells. rRNA synthesis in isolated nuclei is not sensible to wide range of concentration of papaverine (0,005-0,1 mM), cycloheximide (0,5-100 micrograms/ml) and DNP (5-500 microM). Actinomycin D at low concentration does not act on the rRNA synthesis in vitro either. To suppress rRNA synthesis in this system much higher concentration of this agent (10 micrograms/ml) producing inhibition of all classes of rRNA synthesis in intact cells is required. Selective sensitivity of rRNA synthesis in the cells to papaverine, cycloheximide, DNP and low concentration of actinomycin D does not connect with their direct action on the apparatus of rRNA synthesis.     

Parameters of binding and transport of oligodeoxynucleotide, which includes BCL2 mRNA translation start, to the K562 cells

Interaction of oligodeoxynucleotides (ODN), 18-mer, which included sequence of BCL2 mRNA translation start, with K562 cells has been studied. The kinetic curves of interaction showed that oligonucleotide total binding with the cells at 37 degrees C and low oligonucleotide concentration (< or = 30 nM), as well as under lipofection, were composed of two processes: 18-mer surface binding with cell membranes and its non-proportional internalization into the cells. The last, in turn, consisted of three consequent steps. The enhanced extent and rate of oligonucleotide internalization was diminished after first hour incubation and later they were increased again. This reflected rising additional binding sites that provided internalization. At chosen time-points the internalization of ODN into cells, been proceeded at 37 degrees C, were at most abruptly abrogated by cooling down. ODN to K562 cell membrane binding constants and specific number of binding sites have been determined. Time-intervals, providing equilibrium for each successive stage of multistep ODN bound/free determination, were maintained. It was established that receptor binding with increased binding constant (more than 2 x 10(9) M(-1)) promoted ODN internalization. Oligonucleotide binding and internalization with prolonged incubation were also up-regulated due to priming new binding sites of higher affinity. Lipofection enhanced ODN binding to cell membrane but conserved the main features of ligand-receptor interaction. During lipofection constants and ODN binding site numbers increased without changing the overall time-pattern of the process, observed for ODN without liposomes. Extent and rate of internalization of ODN in liposomal formulation did not differ substantially from ODN in solution.     

Inhibitor interaction in the suppression of ribosomal RNA synthesis in Ehrlich ascites carcinoma cells

Kinetic analysis of inhibitory action of papaverine, 2,4-dinitrophenol (DNP) and actinomycin D on RNA synthesis in the intact Ehrlich ascites carcinoma cells has shown that the action of these agents is mediated by their effect on the same step of rRNA synthesis.