{"doi":"10.1101/2024.09.30.615953","title":"N-Acetyl-2-Aminofluorene (AAF): <i>In vivo</i> temporal expression patterns of growth cycle-dependent macromolecular binding constants K <sub>D[APPARENT]</sub> and B <sub>MAX[APPARENT]</sub> are revealed by primary cultures of premalignant hepatocytes derived from a multi-cyclic hepatocarcinogenic feeding regimen","abstract":"ABSTRACT Biochemical investigations of the hepatoprocarcinogen N-acetyl-2-aminofluorene (AAF) have shown that normal adult rat hepatocytes in primary culture express two sets of pharmacokinetic constants – designated Systems I and II, and Sites I and II – associated respectively with the metabolism (System I [high-affinity K m[APPARENT] and low-velocity V MAX[APPARENT] ] and System II [low-affinity K m APPARENT] and high-velocity V MAX[APPARENT] ]), and the m acromolecular binding (Site I [high-affinity K D[APPARENT] and low capacity B MAX[APPARENT] ] and Site II ([low-affinity K D[APPARENT] and high-capacity B MAX[APPARENT] ]) of AAF. Additional findings – that genomically saturating levels of AAF-DNA adducts form far below reported extracellular AAF concentrations required to block replicative and repair DNA synthesis; and, that biphasic Site I and Site II B MAX[APPARENT] and K D[APPARENT] expression curves varied inversely with respect to time and magnitude during hepatocyte growth – led us to wonder how macromolecular binding constants are expressed during chemical hepatocarcinogenesis. These questions were addressed by Scatchard analysis measurements through five consecutive AAF feeding cycles. Notably, cultured premalignant hepatocytes displayed reduced and elevated B MAX[APPARENT] and K D[APPARENT] levels, respectively, akin to the Site I and Site II expression curves observed during hepatocyte growth transitions in vitro . In contrast, prominent hepatocellular functions such as N-OH-AAF production, DNA replication, cell aggregation and resistance to AAF toxicity displayed different temporal trajectories. Impact Statement Striking similarities are observed between both Site I and Site II B MAX and K D expression curves during in vitro and in vivo premalignant growth transitions. These new findings fit earlier ones that hepatocytes growing during carcinogen exposure manifest fewer intranuclear AAF-DNA adducts. How this phenomenon leads to malignancy remains unclear.","journal":"bioRxiv (Cold Spring Harbor Laboratory)","year":2024,"id":504149,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":0,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9606,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2024-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":1354685,"name":"Tom Moran","orcid":null,"position":1,"is_corresponding":false},{"id":1354275,"name":"Stewart Sell","orcid":"0000-0002-3703-789X","position":2,"is_corresponding":false},{"id":1354276,"name":"Hyam L. Leffert","orcid":"0000-0002-3226-433X","position":3,"is_corresponding":false},{"id":1354684,"name":"Katherine S. Koch","orcid":null,"position":0,"is_corresponding":true}],"reference_count":21,"raw_metadata":null,"created_at":"2026-07-19T02:10:35.597333Z","pmid":null,"pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}