Fish oil alters tamoxifen-modulated expression of genes related to differentiation, proliferation, metastasis, and immune response in rat mammary tumors

Herein, we evidence that tamoxifen treatment modifies gene expression of mammary tumors depending upon the type of dietary fat fed to the animals. Rats initiated with MNU and treated with tam were fed a diet rich in corn oil (CO) or fish oil (FO). After 8 weeks, tumors of the same histological type (cribriform) were collected and comprehensive analysis of messenger RNA expression was performed. The mRNA expression of genes such as SerpinB10, Wisp2 and Apod in tumors from FO-treated rats is indicative of highly differentiated tumors. Decreased expression of H19 and Igf2 mRNA in tam-treated groups, and Thrsp and Wnt5b mRNA in FOtam group may be related to tumor growth impairment and lower metastatic capacity. Increased Irf7, RT1-CE3, RT1-CE16 transcript levels in FO-treated animals suggests an improved immune response against tumors (Th1 pattern) whereas decreased mRNA of Fcer1a, Hdc, Ms4a2, Slp1, Mcpt1 and Mcpt2 may indicate a shift of the immune response towards Th2 pattern. Sprague-Dawley rats received one injection of MNU and were distributed in 4 different groups. G1 received corn oil diet (CO); G2 received CO and tamoxifen; G3 received fish oil diet (FO) and G4 received FO an tamoxifen. After 8 weeks of treatment, diet- and/or tamoxifen-induced transcriptomic changes were evaluated in cribriform tumors of three different rats/group.