Dietary Tomato Inhibits Tumor Angiogenesis in the TRAMP Model of Prostate Cancer but Is Not Protective With a Western-Style Diet

Abstract

Abstract Objectives The objective of this study was to investigate the interplay between tomato powder (TP), incorporated into control (CON) and obesogenic (OB) diets, and PCa tumor growth and blood perfusion over time in a transgenic model of PCa. We hypothesized that TP would be protective against PCa growth. Methods Diets (either CON [17.2% kcal from fat] or OB [44.6% kcal from fat] both with and without 10% TP) were fed to transgenic adenocarcinoma of the mouse prostate (TRAMP) mice (n = 5/dietary group) from weaning. Tumor growth was monitored by weekly ultrasound scanning, at which time novel ultrasound microvessel images (UMI) were captured to quantitatively measure tumor blood perfusion over time. Animals were euthanized after 5 weeks of tumor growth, and tissues were collected for measurement of protein (HIF-1α, TNFα) and gene (ar, srd5a1, srd5a2) expression. Data were analyzed to determine differences between CON diets (without TP + with 10% TP) and OB diets (without TP + with 10% TP) and to evaluate the impact of 10% TP on outcome measures both independent of TP (No TP vs. TP) as well as within CON and OB diets (interaction effect of diet*TP) by mixed model ANCOVA with body weight as a covariate. Results UMI results showed good agreement with gold-standard immunohistochemistry quantification of endothelial cell density, indicating that this technique can be applied to non-invasively and longitudinally monitor tumor blood perfusion in vivo. Greater body weight (P = 0.029) and OB diets (P = 0.008) were associated with earlier age at tumor detection, and greater body weight was positively associated with tumor growth (P = 0.001). TP significantly inhibited prostate tumor angiogenesis (P = 0.043), but this inhibition differentially affected measured outcomes depending on CON or OB diets. TP led to reduced tumor growth (P = 0.004), intratumoral inflammation (TNFα; P = 0.019), and intratumoral androgen-regulated gene expression (srd5a1, srd5a2; P = 0.030 and P = 0.016, respectively) when incorporated with the CON diet but greater tumor growth and intratumoral gene expression when incorporated with the OB diet. Conclusions Results from this study show that protective benefits from dietary tomato are lost, or may become deleterious, when combined with a Western-style diet. Funding Sources CA was supported by the NIH NIBIB. MRL and PS were partially supported by NIH NCI.