Adenosine 5'-triphosphate (ATP) is found in high concentrations in the extracellular microenvironment of tumours and is postulated to play critical roles in cancer progression. In the present study, we found that stimulation of human MCF-7 breast cancer cells with 30 µM ATP increased their migration by 140 ± 31%, whereas it had minor or no effect on their proliferation. This effect was prevented by the ectonucleotidase apyrase and was antagonized by suramin and pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid, consistently with the participation of P2 receptors. MCF-7 cells expressed messenger RNA for all known P2Y receptors and for P2X2, P2X4, P2X5, P2X6 and P2X7 receptors. Brief applications (20 s) of external ATP resulted in a 50 pA P2X-like inward current. ATP, but not adenosine diphosphate or uridine diphosphate, increased the intracellular calcium concentration in absence of extracellular calcium, and this effect was prevented by the inhibition of phospholipase C. Uridine triphosphate (UTP) (10 µM) and 2-thio-UTP (10 µM) increased intracellular calcium concentration and cell migration to the same extent as ATP. The UTP-dependent increase in cell migration was absent in cells knocked-down for P2Y2. It was inhibited by MEK inhibitor PD98059. UTP induced a time-dependent phosphorylation of extracellular signal-regulated kinases 1 and 2 (ERK1/2), which was prevented by the incubation with PD98059. Taken together, these results highlight the importance of the purinergic signalling in cancer cells and indicate that the activation of P2Y2 receptors enhances breast cancer cells migration through the activation of a MEK-ERK1/2-dependent signalling pathway.

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Peroxisome proliferator-activated receptor β (PPARβ) and NaV1.5 voltage-gated sodium channels have independently been shown to regulate human breast cancer cell invasiveness. The n-3 polyunsaturated docosahexaenoic acid (DHA, 22:6n-3), a natural ligand of PPAR, is effective in increasing survival and chemotherapy efficacy in breast cancer patient with metastasis. DHA reduces breast cancer cell invasiveness and it also inhibits PPARβ expression. We have shown previously that NaV1.5 promotes MDA-MB-231 breast cancer cells invasiveness by potentiating the activity of Na(+)/H(+) exchanger type 1 (NHE-1), the major regulator of H(+) efflux in these cells. We report here that DHA inhibited NaV1.5 current and NHE-1 activity in human breast cancer cells, and in turn reduced NaV1.5-dependent cancer cell invasiveness. For the first time, we show that antagonizing PPARβ, or inhibiting its expression, reduced NaV1.5 mRNA and protein expression and NaV1.5 current, as well as NHE-1 activity and cell invasiveness. Consistent with these results, the DHA-induced reduction of both NaV1.5 expression and NHE-1 activity was abolished in cancer cells knocked-down for the expression of PPARβ (shPPARβ). This demonstrates a direct link between the inhibition of PPARβ expression and the inhibition of Nav1.5/NHE-1 activities and breast cancer cell invasiveness. This study provides new mechanistic data advocating for the use of natural fatty acids such as DHA to block the development of breast cancer metastases.

Extensive studies are performed in order to develop more safe and selective anticancer drugs in terms of decreasing treatment-associated toxicity. Special attention has been paid to molecules containing sulfur heterocycles as they consider an important structural unit of many marketed drugs. A series of 2-amino, 5-nitrothiazole derivatives were designed by our University. We aimed for in vitro testing of three compounds upon growth rates of MDA-MB-231 cell line and its ability for migration. Materials and methodsCytotoxicity of the mentioned compounds against the MDA-MB-231 cell line was assessed using MTT assay. Scratch assay was used to determine the possible effects of compounds on the migratory capacity of MDA-MB-231. ResultsTwo compounds, i.e., 5-nitro-1,3-thiazol-2-amine and 4-{(E)-[(5-nitro-1,3-thiazol-2-yl)imino]methyl}benzaldehyde showed an inhibitory effect upon cancer cell migration while showing, no effect on the cytotoxicity of the MDA-MB-231 cancer cell line at increasing concentrations (1,5,10, 25, 50, and 100 μM/L) after 72 hours of incubation (with p.value=0.1076 and 0.8171 respectively).In addition to cell migration inhibition, the derivate compound (5E)-5-(4-{(E)-[(5-nitro-1,3-thiazol-2-yl) imino]methyl}benzylidene)imidazolidine-2,4-dione showed a statistically significant cytotoxic effect upon MDA-MB-231 cell line following 72-h incubation at the drug concentration of 100 μM/L (p=0.0164). ConclusionThe derivatives of 2-amino, 5-nitrothiazole are considered a promising starting point to synthesize further drug candidates to treat metastatic breast cancer.