Ki = 18.9 nM for human adenosine A3 receptor

Ki = 113 nM for rat adenosine A3 receptor

MRS1523 is a selective adenosine A3 receptor (A3R) antagonist. A3R is strongly overexpressed in cancer cell lines and cancer tissues. The activation of the A3R is related to several second messenger systems which are for signaling pathways including asthmatic, inflammatory, and ischemic responses.

In vitro: MRS1523 reversed the increase in mRNA expression in B16-F10 Melanoma Cells. Also, MRS1523 antagonized the modulation in the expression level of the proteins, which indicated that adenosine A3R mediated the responses [1].

In vivo: C57BL/6J, male mice, inoculated B16-F10 melanoma cells, were administered MRS1523 at a dose of 100 μg/kg orally twice daily for 15 days. MRS1523 counteracted the activity of IB-MECA which is an adenosine A3R agonist. In addition, it was demonstrated that the response was adenosine A3R mediated. The modulation of up-regulation of GSK-3β expression level was neutralized by MRS1523, further suggesting the specificity of the response [1].

Reference:
[1].  Madi, L., Rosenberg-Haggen, B., Nyska, A., & Korenstein, R. Enhancing pigmentation via activation of A3 adenosine receptors in B16 melanoma cells and in human skin explants. Experimental Dermatology. 2012; 22(1): 74-77.