ATX was shown to delay carboplatin induced apoptosis in ovarian cancer cells. ATX inhibition was a proposed mechanism of action of BT in a melanoma model via inhibition of cell migration and invasion. Given the significance of ATX in ovarian cancer, we studied the effect selleck bio of BT on ATX in a panel of ovarian cancer cell lines. Our results clearly demonstrate significant inhibition of ATX in a concentration and time dependent fashion. ATX LPA stimulate the PI3 K, Akt, and ERK pathways and cause the activation of Rho and Rac. These path ways facilitate cell division, survival, and migration. BT may inhibit cell survival directly via inhib ition of ATX or indirectly via inhibition of PI3 K, Akt or NF kB pathways. Additionally, ATX is known to act as antioxidant, thus, protecting cells from oxidative stress.
The fact that BT treatment reduced ATX activity would imply that treated cells are exposed to a higher oxidative stress, eventually leading to apoptosis or ne crosis. In view of the significance of ATX in chemoresis tance in a majority of widely used chemotherapeutic agents, ATX inhibition or the LPA pathway can be con sidered as a significant therapeutic target. In our studies, we also observed a significant inhibition of ATX by BT. Based on our findings, BT affects cells by causing mitochondrial dysfunction, ROS generation, cell cycle arrest and ATX inhibition, ultimately leading to cell death. BT appears to be a viable thera peutic agent against ovarian cancer cell lines in vitro. Further exploration of its anti tumor potential in ovarian cancer animal xenograft model is essential before pro ceeding to clinical trials.
Additionally, it is interesting to focus on synergistic, additive or antagonistic effects of BT in combination with other standard chemo drugs. These studies are currently underway. Conclusions We demonstrated the ability of BT to exert cytotoxic ef fects on a panel of ovarian cancer cell lines regardless of their cisplatin sensitivities. BT IC50 values observed in various ovarian cancer cell lines are well below the clin ically tolerable doses of BT for humans. BT was shown to induce cell death via apoptosis. The mechanism of actions appears to be via cell cycle regulation, ROS generation, NF kB inhibition and ATX inhibition. ROS generation appears to be major mechanism of BT cyto toxicity in cisplatin resistant variants.
Agents causing cell cycle mediated apoptosis, NF kB and ATX inhibition are already considered ideal candidates for the treatment of ovarian cancer. Because BT was shown to exhibit these desirable properties in in vitro, it is being further explored as an effective therapeutic agent in mice ovarian cancer xenograft model, either alone or in combination. In sum mary, the present study provides Tipifarnib mechanism preclinical data support ing the possible therapeutic role of BT in the treatment of recurrent platinum resistant ovarian cancers.