The U1 cell line, derived from a chronically infected U937 culture harbors a latent HIV genome which can be induced to synthesize virus in the presence of TPA, TNFa, IL-6, okadaic acid and some other cytokines. Various chemical carcinogens and environmental mutagens were examined for their ability to induce virus from U1 cells with the objective to identify risk factors of physiologic relevance that may modulate disease progression in AIDS. In the first phase of the experiment, the cells were treated with carcinogens and harvested at different time points for measurement of p24 and RT activity from supernatants. Cell pellets were harvested for DNA and RNA preparation. Among these, benzo(a)pyrene (BOP) and alpha hexachlorocyclohexane(HCH) were found to be upregulating the virus production more than 18 and 12.5 fold after six days of treatment. TPA served as the positive control in the experiment. Enhanced levels of HIV RNA were observed in BOP and HCH treated cultures. A ten fold increase in virus production was observed using electron microscopy. In order to understand the mechanism of virus induction, experiments were carried out to analyze the induction of NF- kB protein, or the production of cytokines like TNFa or phosphorylation of kB complex. It is interesting to note that BOP and HCH both induce NF-kB protein as early as 2 hours of treatment and the effect persists for 2 days. Treated cell free supernatants showed less elevated TNFa activity after 24 hours than TPA treated supernatants. In case of BOP treated cells, phosphorylation of the Ik B complex by Protein Kinase C is observed reflected by generation of enhanced NF-kB activity for overall up- regulation of the virus. Other environmental mutagens that were analyzed and showed more than 5 fold viral induction included cigarette smoke constituents such as NNK, NNN, dimethyl nitrosamine(DMNA) and aflatoxin. Nicotine, NNN, NNK and DMNA were found to induce NF-kB protein at different time points. The involvement of PKC activity was observed in cells treated with nicotine, NNK and DMNA.
