American Association for Cancer Research
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Data Supplement from Intestinal Epithelial HuR Modulates Distinct Pathways of Proliferation and Apoptosis and Attenuates Small Intestinal and Colonic Tumor Development

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posted on 2023-03-30, 22:40 authored by Antonina Giammanco, Valerie Blanc, Grace Montenegro, Coen Klos, Yan Xie, Susan Kennedy, Jianyang Luo, Sung-Hee Chang, Timothy Hla, ILKe Nalbantoglu, Sekhar Dharmarajan, Nicholas O. Davidson

Supplemental Figure S3. mRNA expression of apoptosis-related factors in AOM-DSS-treated Hur IKO and Hur f/f mice.



HuR is a ubiquitous nucleocytoplasmic RNA-binding protein that exerts pleiotropic effects on cell growth and tumorigenesis. In this study, we explored the impact of conditional, tissue-specific genetic deletion of HuR on intestinal growth and tumorigenesis in mice. Mice lacking intestinal expression of HuR (Hur IKO mice) displayed reduced levels of cell proliferation in the small intestine and increased sensitivity to doxorubicin-induced acute intestinal injury, as evidenced by decreased villus height and a compensatory shift in proliferating cells. In the context of Apcmin/+ mice, a transgenic model of intestinal tumorigenesis, intestinal deletion of the HuR gene caused a three-fold decrease in tumor burden characterized by reduced proliferation, increased apoptosis, and decreased expression of transcripts encoding antiapoptotic HuR target RNAs. Similarly, HurIKO mice subjected to an inflammatory colon carcinogenesis protocol [azoxymethane and dextran sodium sulfate (AOM-DSS) administration] exhibited a two-fold decrease in tumor burden. HurIKO mice showed no change in ileal Asbt expression, fecal bile acid excretion, or enterohepatic pool size that might explain the phenotype. Moreover, none of the HuR targets identified in Apcmin/+HurIKO were altered in AOM-DSS–treated HurIKO mice, the latter of which exhibited increased apoptosis of colonic epithelial cells, where elevation of a unique set of HuR-targeted proapoptotic factors was documented. Taken together, our results promote the concept of epithelial HuR as a contextual modifier of proapoptotic gene expression in intestinal cancers, acting independently of bile acid metabolism to promote cancer. In the small intestine, epithelial HuR promotes expression of prosurvival transcripts that support Wnt-dependent tumorigenesis, whereas in the large intestine epithelial HuR indirectly downregulates certain proapoptotic RNAs to attenuate colitis-associated cancer. Cancer Res; 74(18); 5322–35. ©2014 AACR.

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