Atom-based QSAR and 3D QSAR using pharmacophore based alignment for discovery of nimesulide-derived SKBR-3 cell line inhibitors

Growth suppression of many non-COX-2 expressing tumor cells can be exhibited by COX-2 inhibitors, where supplementation of cells with exogenous prostaglandins fails to rescue the cells from growth inhibition. It can, therefore, be speculated that anti-cancer properties of some COX-2 inhibitors may be contributed by the COX-2-independent effects also. Some of the derivatives obtained from certain COX-2 inhibitors which show non-COX-2 inhibitory mechanism have revealed some significant anti-cancer activities. From a COX-2 selective inhibitor nimesulide, an analog JCC76 is derived which is a non-COX-2 active compound and shows inhibition of SKBR-3 breast cancer cell growth. Other JCC76 derived inhibitors also played significant role in SKBR-3 cell inhibition. An analog-based study was done using pharmacophore modeling and 3D-QSAR to provide clues for potential lead compound designing. A five point pharmacophore ADHRR was generated using 39 JCC76-derived SKBR-3 inhibitors. The validated pharmacophore alignment was used for further 3D-QSAR analysis, which presented a good R2 value of 0.562, 0.982, and 0.848 for atom-based QSAR, CoMFA, and CoMSIA model, respectively. All the QSAR models presented good statistical significance and predictivity. The corresponding Q2 values for each model are 0.513, 0.649, and 0.518, respectively. Both the pharmacophore and CoMSIA results displayed that the H-bond donor and acceptor sites are the key structural feature for JCC76-derived non-COX-2-dependent inhibitors with high activity.