ATB-346, a Novel Hydrogen Sulfide-releasing Anti-inflammatory Drug, Induces Apoptosis of Human Melanoma Cells and Inhibits Melanoma Development in Vivo

Inflammation plays a key role in tumor promotion and development. Indeed, cyclooxygenase-2 (COX-2) expression is strongly associated with different types of cancer. An emerging class of compounds with significant anti-inflammatory properties is the hydrogen sulfide-releasing non-steroidal anti-inflammatory drugs (HS-NSAIDs). They consist of a traditional NSAID to which an HS-releasing moiety is covalently attached. We have recently demonstrated that HS donors inhibit melanoma cell proliferation. In the current study, we evaluated the potential beneficial effects of a new HS-releasing derivative of naproxen, ATB-346 [2-(6-methoxynapthalen-2-yl)-propionic acid 4-thiocarbamoyl phenyl ester] which inhibits COX activity but also releases HS. We used cell culture and a mouse melanoma model to evaluate the effect of ATB-346 on: i) in vitro growth of human melanoma cells; ii) in vivo melanoma development in mice. Cell culture studies demonstrated that ATB-346 reduced the in vitro proliferation of human melanoma cells and this effect was associated to induction of apoptosis and inhibition of NF-κB activation. Moreover, ATB-346 had novel Akt signaling inhibitory properties. Daily oral dosing of ATB-346 (43μmol/kg) significantly reduced melanoma development in vivo. This study shows that ATB-346, a novel HS-NSAID, inhibits human melanoma cell proliferation by inhibiting pro-survival pathways associated with NF-κB and Akt activation. Furthermore, oral treatment with ATB-346 inhibits melanoma growth in mice. In conclusion, the combination of inhibition of cyclooxygenase and delivery of HS by ATB-346 may offer a promising alternative to existing therapies for melanoma.