Synergism On The Mechanism Of UVA Assisted 4-Thio-5-(2-thienyl) Uridine To Inhibit Melanoma A375 Cells

Photochemotherapy in which a photosensitizer and ultraviolet or visible light combine to exertsynergistic cytotoxicity is used in the treatment of skin conditions including cancer. This combination has high mutagenicity or non-selectivity, but it is possible to achieve thehigh efficiency, high targeting and low toxicityoptimal treatment for cancer. Asa photosensitizer for UVA, there is no anti-tumor activity report about UVA assisted4-thio-5-(2-thienyl)uridine.Objective To research the synergism on the mechanism of UVA assisted4-thio-5-(2-thienyl) uridine to inhibit human melanoma A375 cells as a new anti-cancer drug in vitro. Methods Combined dose selectionof 4-thio-5-(2-thiophen) uridine and UVA by MTT assay. Annexin V-FITC/PI staining and flow cytometrytest morphology analysis, cell cycle and apoptosis detection toidentify the type of cell death for 4-thio-5-(2-thiophen)uridine and UVA. Through the Western Blotanalysised of signal transmission way by quantitative detecteing some key proteins such as p38, Akt, the Bcl-2 family proteins, caspase family proteins and PARP. Finally,Photoproducts are separated and monitored by High Performance Liquid Chromatography(HPLC), analyzing 4-thio-5-(2-thiophen) uridine possible light reaction under UVA radiation. Results The combined non-toxic dose4-thio-5-(2-thiophen)uridine(100 μmol/L)and low dose of UVA(15 KJ/m2) had an effects of collaborative widely death caused by human melanoma cell line A375. The morphology and flow cytometry results suggested that: By the synergistic effect,4-thio-5-(2-thiophen)uridine( 100 μmol/L)and UVA(15 KJ/m2)induced cell death by the way of apoptotic in A375 cells. Western Blot results showed that: the synergistic effect inhibited cell proliferation though inhibiting p38 protein expression and phosphorylation. At the same time, the synergistic reduced the expression and phosphorylation of Akt and Bcl-2 expression, weakening of the pro-apoptotic protein Bad inhibition to further enlarge the apoptosis signals. Though prompte pro-caspase-9 and pro-caspase-3 activation and shear to activate claved-PARP for apoptosis. HPLC resulted that: Low UVA doses(15 kJ/m2) caused de-thienyl of4-thio-5-(2-thiophen)uridine, and further de-sulfurization or cyclization with the increase of UVA dose. Conclusion The combined non-toxic dose4-thio-5-(2-thiophen)uridine( 100 μmol/L) and low dose of UVA(15 KJ/m2), possibly by photochemical reaction,inhibiting the expression of p38 lightning and A375 cell Akt signaling pathways, inhibiting and inducing cell apoptosis.