scienze della vita roma, 22-23 ottobre 2012 - SIF

KHCO3 AND D-RIBOSE: IN VITRO SLOWDOWN
OF CANCER CELL GROWTH
S.Croci 1,2 , L. Bruni 1,2,3
1 Neuroscience Department, Biophysics and Medical Physic Unit, Parma University
2 INBB- Nation Institute of Biosystem and Biostructure - Rome
3 Valsè Pantellini Foundation, Oviedo, Asturia Spain
Cancer cells have a glycolysis enhancement even in the presence of available oxygen. The “aerobic
glycolysis”, known as the Warburg effect, is considered a fundamental metabolic alteration during
malignant transformation. The up-regulation of glycolysis in tumour cells is well known and it is
the rationale of F 18 -FDG PET diagnostic technique. This propriety is strictly link to the increase of
sugar transporters (GLUTs) in most tumours. Also SGLT family transporters, which include the
sodium-glucose symporter, are deregulated in many tumours. The influx of Na + into tumour cells
leads to a change into ions equilibrium, with particular reference to K + intracellular concentration.
We investigated the effect of K:D-Rib on cell proliferation. Experiments performed on HTB-126
cells (human breast adenocarcinoma) demonstrate that the synergic action of KHCO3 and D-ribose
(K:D-Rib) has a cytostatic effect, reducing by 30% the doubling population time of treated cancer
cells respect to the control.
HTB-126 cells were sown to perform the clonogenic assay. The water solution tested were K:D-Rib
and K:D-Frutt (KHCO3 and D-fructose) at the concentration of 5mM. The clonogenic assay shows
that the colonies formed during the incubation with 5 mM K:D-Rib (10 colonies) are significantly
less respect to the control (23 colonies) but not if D-fructose (12 colonies) is used instead D-ribose.
The colony shape of cells treated with K:D-Rib and K:D-Frutt appears confined and with the inner
part more compact respect to the control.
These experimental evidences drive us to consider a fine-tuning of K + concentration regulation. The
concentration of K + is measured by the folding of DNAzyme. This molecule has the functional
characteristics of a protein, because it is able to catalyze the peroxidation reaction but it is
structurally different from a protein. To permit such catalytic activity, guanine-rich oligonucleotides
are folded in G-quadruplex structure, which can bind hemin molecule. The DNAzyme formation is
not possible without suitable concentrations of K + ion. From the amount of DNAzyme we can
estimate how much K + ion is present in the solution. The DNAzyme formation and quantification
is determined by UV-VIS spectroscopy.
DNAzyme formation has been measured also in presence of K:D-Rib 5mM allowing the use of
DNAzyme as potassium concentration sensor. Measures on cell medium, before and after treatment,
have been done. Preliminary results indicate that the extracellular medium of HTB-126 treated with
K:D-Rib 5mM has a lower DNAzyme concentration, compared to reference solution of K:D-Rib
5mM. This could demonstrate that an amount of K + ion enters inside the cell.
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