Potassium bicarbonate and D-ribose effects on A72 canine and HTB-126 human cancer cell line proliferation in vitro

<p>Abstract</p> <p>Background</p> <p>The synergic action of KHCO₃and D-ribose is tested on A72 and HTB-126 cell lines proliferation using K:D-Rib solution. Altered Na⁺/K⁺ATPase expression and activity were shown in patients with cancer. Studies in human epithelial-derived malignancies indicate that K⁺depletion also occurs, contributing to the increased intracellular Na⁺/K⁺ratio <abbrgrp><abbr bid="B1">1</abbr></abbrgrp>. D-ribose transformed to piruvate, enters into the Krebs's cycle and has a key role on energetic metabolism. The up-regulation of glycolysis in tumor cells is already well known and it is the rationale of F¹⁸-FDG PET diagnostic technique. D-ribose is synthesized by the non-oxidative transketolase PPP reaction.</p> <p>Results</p> <p>Results with different K:D-Rib concentrations show that MTT salt interferes with K:D-Rib solution and therefore this method is not reliable. The UV/VIS measurements show that K:D-Rib solutions reduce MTT salt to formazan in absence of cells. Cell proliferation has then been evaluated analysing the digital photos of the Giemsa stained cells with MCID™ software. At 5 mM K:D-Rib concentration, the cell growth arrests between 48 h and 72 h; in fact the cell number after 48 h is around the same with respect to the control after 72 h. In case of HTB-126 human cancer cells, the growth rate was valuated counting the splitting times during 48 days: control cells were split sixteen times while 5 mM treated cells eleven times. Most relevant, the clonogenic assay shows that nine colonies are formed in the control cells while only one is formed in the 5 mM and none in 10 mM treated cells.</p> <p>Conclusions</p> <p>The K:D-Rib solution has an antioxidant behaviour also at low concentrations. Incubation with 5 mM K:D-Rib solution on A72 cells shows a cytostatic effect at 5 mM, but it needs more than 24 h of incubation time to evidence this effect on cell proliferation. At the same concentration on human HTB-126 cells, K:D-Rib solution shows a clear replication slowing but the cytostatic effect at 10 mM K:D-Rib solution only. Results on A72 cells indicate the K⁺uptake could be determinant either to arrest or to slow down cell growth.</p

K:D-Rib: cancer cell proliferation inibitor and DNAzyme folding promoter

We report the effects of K:D-Rib, a D-ribose and KHCO3 water solution on HTB-126 human cancer cell line proliferation and the preliminary ultraviolet-visible (UV-VIS) measures of DNAzyme as biosensor of extracellular K+ concentration. On the one hand, we demonstrate that the synergic action of KHCO3 and D-ribose from one side has a cytostatic effect on human breast cancer cell line increasing by 30% the doubling population time of treated cells with respect to the control; and on the other hand we demonstrate how it seems to permit the K+ uptake

MDI: integrity index of cytoskeletal fibers observed by AFM

The Modified Directional Index (MDI) is a form factor of the angular spectrum computed from the 2D Fourier transform of an image marking the prevalence of rectilinear features throughout the picture. We study some properties of the index and we apply it to AFM images of cell cytoskeleton regions featuring patterns of rectilinear nearly parallel actin filaments as in the case of microfilaments grouped in bundles. The analysis of AFM images through MDI calculation quantifies the fiber directionality changes which could be related to fiber damages. This parameter is applied to the images of Hs 578Bst cell line, non-tumoral and not immortalized human epithelial cell line, irradiated with X-rays at doses equivalent to typical radiotherapy treatment fractions. In the reported samples, we could conclude that the damages are mainly born to the membrane and not to the cytoskeleton. It could be interesting to test the parameter also using other kinds of chemical or physical agents

PS2.M: Looking for a potassium biosensor

DNA sequences with guanine repeats are able to fold as G-quadruplex (G4) structures. This is an alternative DNA conformation in which four guanines are arranged as a tetrad, the structural unit of G4; two or more stacked tetrads form a G4 structure. The hydrogen bonds characterizing G4 are called Hoogsten bonds but more interactions are involved in the G4 structure stabilization. For example, cations work as G4 stabilizers and their role is not restricted to the structural folding. They coordinate the guanines’ carbonilic oxygens located towards the hydrophobic channel of the G4 inner structure. This feature suggests that the G4 could work as a cation biosensor. Biological media are characterized by the simultaneous presence of K+and Na+exhibiting different affinities and thus promoting different topological arrangements in the folding solution. In this article we explore the possibility of using PS2.M, an 18 base long synthetic oligonucleotide, as a detector of K+at concentrations in the range 0mM to 10mM. Our intent is therefore to study a biosensor that is made of the G4 sequence only, without intervention of other coupled molecules. As with most guanine-rich oligonucleotides, also PS2.M shows different structures depending on the folding conditions. In agreement with the literature data, our results outline the expected behavior and the key role of K+and Na+in promoting the folding, with Na+promoting the antiparallel structure formation of PS2.M, even at high concentrations. On the other hand, if PS2.M is folded in 10mM to 100mM KCl solutions, the parallel conformation sets in becoming more and more relevant as concentration grows. In a complex solution of G4 in the presence of both K+and Na+ions, spectra display the coexistence of parallel, antiparallel and mixed type conformations. Results show that the CD spectra values at this wavelength can be diagrammed as a function of the K+concentration to construct a biosensor calibration curve. In conclusion, given a Na+concentration in the range 50mM to 80mM and K+concentration in the range 0mM to 10mM, the measured CD signal at 263.6nm permits a K+concentration measurement with a resolution of ∼ 1 mM