Following early insult, DNA damage leads to disruptions in the cell cycle such as arrest at the G2 checkpoint to allow time for response. Cellular response can include DNA repair, mutation induction through faulty repair or lack of repair, and programmed cell death of heavily damaged cells. Exposure to tobacco smoke can also trigger an inflammatory response and induce

oxidative stress through increased levels of reactive oxygen species. Persistent induction of these processes following repeated exposure contributes to loss of normal growth control mechanisms, which is a key step in cancer development. Our study supports many of these findings, with exposure to TSC inducing the expression of genes involved in xenobiotic metabolism (e.g., HKI-272 mouse Xenobiotic Metabolism Signaling Pathway, Metabolism of Xenobiotics

by CYP450 Pathway), oxidative stress (e.g., NRF2 Mediated Oxidative Stress Pathway), and DNA damage response as evidenced by changes in the expression of genes involved in cell cycle arrest, protein unfolding, transcription regulation, and inflammation (e.g., IL-10 and IL-17 signaling). These same pathways were also significantly affected following MSC exposure, indicating that, as expected, MSC impacts many of the same molecular processes and functions Fulvestrant concentration as TSC. Although the effects of the condensates were largely similar, dose–response analysis indicates that the MSC is substantially more potent than TSC, with BMDs that in many instances are an order of magnitude lower than those for TSC. In addition, the results

also highlighted some differences in steroid biosynthesis (e.g., Biosynthesis of Steroids Pathway), apoptosis (e.g., TNRF1/2 Signaling Pathway) and inflammation, which were more significantly affected following MSC exposure, and cell cycle (e.g., Mitotic Roles of Polo-like Kinase Pathway, G2/M DNA Damage Checkpoint Regulation Pathway), which was more affected following TSC exposure. IPA canonical pathways related to the metabolism of xenobiotics were significantly affected in both TSC and MSC exposed cells at both time points. These pathways included Xenobiotic Metabolism Signaling, Metabolism of Xenobiotics by CYP450, and AHR Signaling. For both TSC and MSC, the number of genes that were Glutamate dehydrogenase significantly affected increased with increasing concentration and the greatest number of genes changing occurred at the 6 + 4 h time point. The profile of the changing genes was comparable between tobacco and marijuana exposed cells (Table 6). Many of the genes that were differentially expressed in TSC exposed cells are among those that have been typically observed to be induced by cigarette smoke [e.g., Nqo1 ( Pickett et al., 2010 and Sacks et al., 2011), Esd ( Rangasamy et al., 2004), Hmox1 ( Lu et al., 2007 and Yauk et al., 2011), Cyp1a1 and Cyp1b1 ( Nagaraj et al., 2006, Pickett et al., 2010, Sacks et al.