Extraintestinal roles of intestinal vitamin D receptor in protecting against dysbiosis and tumorigenesis in breast cancer

Abstract

The microbiota play critical roles in regulating the function and health of intestine and extraintestinal organs. A fundamental question is whether there is an intestinal-microbiome-breast axis during the development of breast cancer. If yes, what are the roles of host factors? Vitamin D receptor (VDR) involves host factors and the human microbiome. Vdr gene variation shapes the human microbiome and VDR deficiency leads to dysbiosis. We hypothesized that intestinal VDR protects hosts against tumorigenesis in breast. Reduced VDR mRNA expression was observed in patients with breast cancer. We used a 7,12-dimethylbenzanthracene (DMBA)-induced breast cancer model in intestinal epithelial VDR knockout (VDR{Delta}IEC) mice. We reported that VDR{Delta}IEC mice with dysbiosis are more susceptible to breast cancer induced by DMBA. Intestinal and breast microbiota analysis showed that lacking VDR leads to bacterial profile shift from normal to susceptible carcinogenesis. We found enhanced bacterial staining within breast tumors. At the molecular and cellular levels, we identified the mechanisms by which intestinal epithelial VDR deficiency led to increased gut permeability, disrupted tight junctions, microbial translocation, and enhanced inflammation, thus increasing the tumor size and number in breast. Furthermore, treatment with beneficial bacterial metabolite butyrate or probiotic Lactobacillus plantarum reduced the breast tumors, enhanced the tight junctions, and inhibited inflammation in the VDR{Delta}IEC mice. Gut microbiome contribute to the pathogenesis of diseases, not only in the intestine, but also in the breast. Our study provides new insights into the mechanism by which intestinal VDR dysfunction and gut dysbiosis led to high risk of extraintestinal tumorigenesis. Gut-tumor-microbiome interactions indicate a new target in the prevention and treatment of breast cancer. O_FIG O_LINKSMALLFIG WIDTH=165 HEIGHT=200 SRC="FIGDIR/small/492300v1_ufig1.gif" ALT="Figure 1"> View larger version (38K): org.highwire.dtl.DTLVardef@7e354eorg.highwire.dtl.DTLVardef@1dd9b50org.highwire.dtl.DTLVardef@1ffe2c5org.highwire.dtl.DTLVardef@810b1a_HPS_FORMAT_FIGEXP M_FIG C_FIG