Hepatocellular carcinoma (HCC) is the most common form of liver cancer worldwide. Accumulating clinical and experimental evidence suggests the role of cyclo-oxygenase (COX) enzymes in the pathogenesis of cancers including HCC. Deuterium-enriched water (DEW) and deuterium-depleted water (DDW) play a role both in the treatment and prevention of cancers. Combination therapy using COX-inhibitors and DDW/DEW could be a rational strategy to enhance the cytotoxicity of either agent in HCC. The cytotoxicity of celecoxib or indomethacin, alone and in combination with DDW or DEW was determined in the Hep-G2 HCC cell line by MTT assay. The COX-2, MAPK pathway proteins, the anti-apoptotic Bcl2 and pro-apoptotic Bax proteins, and caspase-3 activity were determined by SDS-PAGE and western blot. Co-treatment of selective and non-selective COX-2 inhibitors with DEW led to a remarkable increase in cytotoxicity and apoptosis of Hep-G2 cells. These events were associated with the activation of p38 and JNK MAPKs and a decrease in 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. The combination of DEW with NSAIDs might be effective against HCC cells by influencing principal cell signaling pathways, and this has a potential to become a candidate for chemotherapy.

Nanoparticles (NPs) are widely used in diverse disciplines, including biology, medicine science. The central question that need to be answered is whether NPs have toxic effects on biological cells and molecules or are they safe. The safety of NPs including targeted drug delivery is critical and so is their toxicity in the environment. In recent years, in vitro and in vivo research on animals has generated abundant information about the toxicity of NPs. However, due to varying laboratory conditions, the comparison of the results from ensuing studies is somewhat unreliable. It should be noted that, depending on the type of production, NPs can enter the body through inhalation, skin and via digestive routes. Due to the diversity of NPs and their properties, there is paucity of accurate information on their toxicological effects; particle size, shape, surface area and the chemical levels are considered as key factors in creating health and toxicological effects. Consequently, there is a need for reliable information about their effects on various organs so as to deal with NPs effectively and their impact on health and the environment. This review covers the existing knowledge base on the subject that hopefully prepares us better to address these challenges.