DNA repair and damage pathways in mesothelioma development and therapy.

Malignant mesothelioma (MMe) is an aggressive neoplasm that occurs through the transformation of mesothelial cells. Asbestos exposure is the main risk factor for MMe carcinogenesis. Other important etiologies for MMe development include DNA damage, over-activation of survival signaling pathways, and failure of DNA damage response (DDR). In this review article, first, we will describe the most important signaling pathways that contribute to MMe development and their interaction with DDR. Then, the contribution of DDR failure in MMe progression will be discussed. Finally, we will review the latest MMe therapeutic strategies that target the DDR pathway.

Cyclooxygenase inhibitors combined with deuterium-enriched water augment cytotoxicity in A549 lung cancer cell line via activation of apoptosis and MAPK pathways.

OBJECTIVES: Combination chemotherapy is a rational strategy to increase patient response and tolerability and to decrease adverse effects and drug resistance. Recently, the use of non-steroidal anti-inflammatory drugs (NSAIDs) has been reported to be associated with reduction in occurrence of a variety of cancers including lung cancer. On the other hand, growing evidences suggest that deuterium-enriched water (DEW, D2O) and deuterium-depleted water (DDW) play a role both in treatment and prevention of cancers. In the present study, we examined the effects of DEW and DDW in combination with two NSAIDs, celecoxib and indomethacin, on A549 human non-small lung cancer cell to identify novel treatment options. MATERIALS AND METHODS: The cytotoxicity of celecoxib or indomethacin, alone and in combination with DDW and DEW was determined. The COX-2, MAPK pathway proteins, the anti-apoptotic Bcl2 and pro-apoptotic Bax proteins and caspase-3 activity were studied for cytotoxic combinations. RESULTS: Co-administration of selective and non-selective COX-2 inhibitors with DEW led to a remarkable increase in cytotoxicity and apoptosis of A549 cells. These events were associated with activation of p38 and JNK MAPKs and decreasing pro-survival proteins Bcl-2, COX-2 and ERK1/2. Furthermore, the combination therapy activated caspase-3, and the apoptosis mediator, and disabled poly ADP-ribose polymerase (PARP), the key DNA repair enzyme, by cleaving it. CONCLUSION: The combination of DEW with NSAIDs might be effective against lung cancer cells by influence on principal cell signalling pathways, and this has a potential to become a candidate for chemotherapy.