Inhibition of benzo[a]pyrene-induced DNA adduct in buccal cells of smokers by black raspberry lozenges

Using LC–MS/MS analysis we previously showed for the first time (Carcinogenesis 43:746–753, 2022) that levels of DNA damage induced by benzo[a]pyrene (B[a]P), an oral carcinogen and tobacco smoke (TS) constituent, were significantly higher in buccal cells of smokers than those in nonsmokers; these results suggest the potential contribution of B[a]P in the development of oral squamous cell carcinoma (OSCC) in humans. Treating cancers, including OSCC, at late stages, even with improved targeted therapies, continues to be a major challenge. Thus interception/ prevention remains a preferable approach for OSCC management and control. In previous preclinical studies, we and others demonstrated the protective effects of black raspberry (BRB) against carcinogen-induced DNA damage and OSCC. Thus, to translate preclinical findings, we tested the hypothesis in a Phase 0 clinical study that BRB administration reduces DNA damage induced by B[a]P in the buccal cells of smokers. After enrolling 27 smokers, baseline buccal cells were collected before the administration of BRB lozenges (5/day for 8 weeks, 1 gm BRB powder/ lozenge) at baseline, at the middle and the end of BRB administration. The last samples were collected 4 weeks after BRB cessation (washout period). B[a]P-induced DNA damage (BPDE-N²-dG) was evaluated by LC–MS/MS. BRB administration resulted in a significant reduction in DNA damage: 26.3% at the midpoint (P = .01506) compared to baseline, 36.1% at the end of BRB administration (P = .00355), and 16.6% after BRB cessation (P = .007586). Our results suggest the potential benefits of BRB as a chemopreventive agent against the development of TS-initiated OSCC.