Black raspberry restores the expression of the tumor suppressor p120ctn in the oral cavity of mice treated with the carcinogen dibenzo[a,l]pyrene diol epoxide

Abstract

One of the major risk factors for head and neck squamous cell carcinoma (HNSCC) is tobacco smoke exposure, but the mechanisms that can account for disease development remain to be fully defined. Utilizing our HNSCC mouse model, we analyzed oral squamous cell carcinomas (OSCC) induced by the active metabolite of a common smoke constituent, dibenzo[a,l]pyrene diol-epoxide (DBPDE). Analyzing protein expression by either immunofluorescence or immunohistochemistry, we identified biologic processes that are dysregulated in premalignant and invasive cancer lesions induced by DBPDE. Interestingly, p120ctn expression is downregulated in both stages of the disease. In addition to decreased p120ctn expression, there was also increased proliferation (as measured by Ki67), inflammation (as measured by NFkB (p65) expression), neovascularization (as measured by CD31) and recruitment of Ly6G-positive immune cells as well as strong EGFR expression. We also examined the effect of the chemopreventive agent black raspberry (BRB) on p120ctn and EGFR protein expression in DBPDE treated mice. p120ctn, but not EGFR, protein expression increased in mice treated with BRB. Our results suggest that modulation of p120ctn may, in part, account for the mechanism by which BRB inhibits DBPDE induced OSCC in mice.

Black Raspberry Extract Enhances Glutathione Conjugation of the Fjord-Region Diol Epoxide Derived from the Tobacco Carcinogen Dibenzo[def,p]chrysene in Human Oral Cells

“…10,11 Therefore, in a series of previous studies, we reported that BRB inhibits DBP-induced DNA damage, mutagenesis and OSCC development. 12,13 We also showed that BRB enhanced the DNA repair capacity of DNA damage induced by DBP 14 and altered genetic 15 and epigenetic markers 16 in a manner consistent with its cancer prevention activity.…”

“…DBPDE-N 6 -dA and its isotope-labeled [ 15 N 5 ]DBPDE-N 6 -dA adduct standards were prepared as previously reported. 25 [ 13 C 4 , 15 N 2 ]GSSG ammonium salt was obtained from Toronto Research Chemical, Inc. (North York, Ontario, Canada). [ 13 C 2 , 15 N]GSH trifluoroacetate salt was obtained from Sigma-Aldrich (St. Louis, MO).…”

“…25 [ 13 C 4 , 15 N 2 ]GSSG ammonium salt was obtained from Toronto Research Chemical, Inc. (North York, Ontario, Canada). [ 13 C 2 , 15 N]GSH trifluoroacetate salt was obtained from Sigma-Aldrich (St. Louis, MO). Other chemicals and enzymes used in the study were also obtained from Sigma-Aldrich (St. Louis, MO).…”

“…The water layer was collected and further purified by HPLC, and 1.7 mg of DBPDE-GSH conjugate was obtained at a yield of 17.2%. The isotope-labeled [ 13 C 2 , 15 N]DBPDE-GSH conjugate was prepared under conditions identical to those described above, but we used the isotope-labeled glutathione-(Glycine-13 C 2 , 15 N) as the starting material.…”

Black raspberry extract inhibits regulatory T-cell activity in a murine model of head and neck squamous cell carcinoma chemoprevention

“…Although tumors that arise from this model make extensive functional characterization of immune cell populations in the tumor microenvironment technically challenging, it remains one of the best models that mimic the stepwise progression observed in HNSCC patients. Using these and other related animal models, we and others have demonstrated the chemopreventive potential of BRB in HNSCC chemoprevention ( 10 , 27 , 29 , 30 ). While multiple mechanisms have been proposed to mediate HNSCC chemoprevention, including modulation of tumor suppressor and apoptotic genes, as well as proinflammatory, glycolytic, and glucocorticoid signaling pathways ( 27 , 29 – 31 ), modulation of adaptive immune cells in a manner that promotes tumor cell cytotoxicity in the tumor microenvironment is a novel and potentially major mechanism of HNSCC chemoprevention by BRB.…”