Phenol sulfotransferases can detoxify or toxify foreign compounds. Therefore, the long-term hypothesis is that sulfation pathways likely play an important role in pulmonary carcinogenesis, as previously demonstrated with hepatocarcinogenesis. Preliminary data indicate that exposure of airway epithelial cells or explants to xenobiotics causes an increase of phenol sulfotransferase activity. Increased activity is also observed upon deprivation of vitamin A in cell culture. It is not known, however, which member(s) of this family is actually responsive, because this class of enzymes is composed of several similar but distinct proteins. It is also not known if the increase in activity is due to increased enzyme expression, is due to an alteration of unknown regulatory factors, or is dependent on cell type. This initial investigation will address these questions using in vitro models as follows. First, two phenol sulfotransferases detected in both alveolar and bronchial mucosa will be purified for subsequent amino acid composition and sequence analyses. Second, the purified proteins will be used to raise polyclonal and monoclonal antibodies which recognize phenol sulfotransferases. Third, assay techniques which will differentially measure two phenol sulfotransferases in crude extracts will be developed. Fourth, the cellular locations of the two enzymes within normal airways and within bronchial explants exposed to xenobiotics will be determined by immunohistology. Fifth, the effects of xenobiotic exposures and retinoic acid deprivation on specific enzyme activities and biosyntheses in airway epithelial cells will be determined by both enzymatic and immunological approaches. Sixth, several approaches are proposed to begin the isolation of cDNAs which encode phenol sulfotransferases. These include oligonucleotide hybridization, polymerase chain reaction, and antigenic screening using antibodies. These reagents will thereby provide the tools to investigate phenol sulfotransferase regulation on the genetic level. These studies may provide insights into possible biochemical causes of, and preventative therapeutic approaches for, airway cancers induced by xenobiotics.
