Quercetin decreases tumorigenesis in a mouse model of breast cancer

Quercetin is a flavonol with anti‐inflammatory actions in macrophages; however no studies have investigated the benefits of quercetin (Quer) on tumorigenesis and inflammation in a mouse model of breast cancer (BrCa). Female C3(1)/SV40Tag mice were assigned to a Quer (0.2%) or control (AIN‐76A) diet (n=14–15) at 4wks of age and tumor number and volume were recorded bi‐weekly. At 20wks mice were sacrificed; tumors and mammary glands were analyzed for mRNA and protein expression. Quer significantly decreased tumor number (20wks) and volume (18.5–20wks); at sacrifice (20wks) average tumor volume was 2061.8 ± 977.0 mm3 in control mice and only 462.9 ± 75.9 mm3 with quercetin treatment. This was consistent with a reduction in invasiveness and numbers of ductal lesions in the mammary gland. Plasma MCP‐1 and tumor MCP‐1 protein was decreased with quercetin (P<0.05). Similarly, markers of pro‐tumor macrophages (CD206 and IL‐10) were reduced in the mammary gland of quercetin treated mice (P<0.05). However, tumor mRNA expression of inflammatory cytokines, MCP‐1, IL‐6, and TNF‐alpha, and the macrophage marker, F4/80, did not differ between treatments. These data provide strong support for a beneficial effect of quercetin on inflammatory processes however, it is likely that inflammation‐independent pathways are also involved. Grant Funding Source : COBRE grant from NIH/NIGMS (1P20GM103641–01)