Human prostate cancer incidence is lower in populations with higher lycopene or tomato intakes, and consumption of lycopene or tomatoes by TRAMP mice inhibits prostate cancer in this model of the disease.  The effect of lycopene or tomatoes on prostate cancer in TRAMP mice is modulated by their b-carotene oxygenase 2 (Bco2) genotype.  However, the literature does not describe the impact of either lycopene or tomato intake on gene expression in the prostate during the early stages of carcinogenesis.  The work by Moran and colleagues addressed this void in our understanding, and their results are reported in the April 2022 issue of The Journal of Nutrition.

Mice (3-week old) that were TRAMP/+ or TRAMP/- and were Bco2+/+ or Bco2-/- were provided a control diet, or one containing lycopene, or 10% tomato powder, which provided 0, 384 or 462 mg lycopene/kg diet, respectively.  After 5 weeks of receiving the experimental diets, gene expression patterns were determined using arrays focused on prostate cancer or cholesterol and lipid metabolism.

Pathways associated with cell survival were induced by the TRAMP genotype, whereas PTEN signaling, cholesterol synthesis, and LXR/RXR pathway activation were inhibited even at this early stage of the disease process.  Consumption of lycopene or tomato powder had only modest impacts on procarcinogenic signaling changes caused by the TRAMP genotype, but did increase expression of genes involved in lipid metabolism.  The Bco2 genotype effects were limited to those affected by lycopene.  The conclusions derived by the authors were that there is a strong impact of the TRAMP genotype on procarcinogenic gene expression patterns occurring very early in the disease process, that lycopene and tomato consumption has only modest effects at this time, and that the Bco2 genotype has limited effects at this disease stage.

References

Nancy E Moran, Jennifer M Thomas-Ahner, Joshua W Smith, Ceasar Silva, Noor A Hason, John W Erdman, Jr, Steven K Clinton, β-Carotene Oxygenase 2 Genotype Modulates the Impact of Dietary Lycopene on Gene Expression during Early TRAMP Prostate Carcinogenesis, The Journal of Nutrition, Volume 152, Issue 4, April 2022, Pages 950–960, https://doi.org/10.1093/jn/nxab445.

Images via canva.com.

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Nancy Turner, PhD

Nancy Turner is a Professor of Nutrition at Michigan State University.  Her research focus is on the role of diet on colon cancer and inflammatory bowel disease.  She is the author of many papers on this topic, as well as the co-editor of a book, and co-author of a textbook.