Table 1.
Author, Year | Animal Model | Baseline Diet(s) | Dietary Tomato and/or Lycopene Content * | Length of Intervention | Primary Findings |
---|---|---|---|---|---|
Canene-Adams, 2009 [27] | Dunning R3327-H transplantable tumors (Copenhagen rats) | AIN-93G-based diets fed; ad libitum | 10% TP (providing 13 nmol lycopene/g diet and resulting in 511 nmol/g serum lycopene), 23 nmol/g diet supplemental lycopene beadlet (252 nmol/g serum lycopene), or 224 nmol/g diet supplemental lycopene beadlet (884 nmol/g serum lycopene) | 18 weeks after tumor transplantation | No differences in serum testosterone or DHT between rats fed tomato, lycopene, or control diets |
Limpens, 2006 [28] | Xenograft using PC-346C cells (athymic mice) | 821077 CRM(P) low (but adequate) vitamin E rodent diet; ad libitum | 5 or 50 mg/kg BW lycopene (from LycoVit) oral gavage = 0.5–1.5 mg lyco/day | 42 days after tumor inoculation | No differences in plasma PSA between mice given control or lycopene gavages (PSA levels were proportional to tumor size regardless of intervention) |
Lindshield, 2010 [29] | Dunning R3327-H transplantable tumors (Copenhagen rats) | AIN-93G-based diets; ad libitum | 250 mg/kg diet supplemental lycopene beadlet = 5 mg lyco/day | 18 weeks after tumor transplantation | No differences in serum testosterone or DHT between rats fed lycopene or control diets |
Siler, 2004 [30] | MayLyLu Dunning transplantable tumors (Copenhagen rats) | Kliba #2019 with added coconut fat (6%), <5 ppm vitamin E, reduced (but adequate) vitamin A, and devoid of phytosterols; did not indicate if ad libitum | 200 ppm lycopene (1.02 µM plasma lycopene) | 4 weeks on diet prior to tumor transplantation, then 18 additional days | Lycopene supplementation reduced tumor expression levels of SRD5A1 and androgen-target genes (cystatin related proteins 1 and 2; prostatic spermine binding protein; prostatic steroid-binding protein C1, C2, and C3; probasin) (only fold reductions reported—no other statistical values reported) |
Wan, 2014 [31] | Transgenic (TRAMP mice) | AIN-93G -based diets; did not indicate if ad libitum | 10% TP (providing 384 mg lycopene/kg diet) or 462 mg/kg diet supplemental lycopene beadlet (0.36 µM plasma lycopene) = 3–4 mg lyco/day | 4 weeks diet prior to surgery, then 12 additional days | Reduced prostatic expression of genes related to androgen metabolism by tomato feeding (SRD5A2 (p = 0.04), Pxn (p = 0.04), and Srebf1 (p = 0.05)) and lycopene supplementation (SRD5A1, p = 0.03) |
* All treatments can lead to blood levels of lycopene within a physiological range (~1 µM). Abbreviations: TRAMP (transgenic adenocarcinoma of the mouse prostate); TP (tomato powder); BW (body weight); DHT (dihydrotestosterone); PSA (prostate-specific antigen); SRD5A1 and 2 (5 α-reductase type 1 and 2); Pxn (paxillin); Srebf1 (sterol regulatory element binding transcription factor 1).