Vitamin D is chemopreventive against colorectal carcinogenesis in vivo and in vitro. The protective effects of vitamin D against colonic carcinogenesis are most probably mediated through the vitamin D receptor (VDR). When bound to the hormonally active form of vitamin D, 1,25(OH)2-D3, VDR transactivates genes that inhibit proliferation, or promote differentiation and apoptosis. Previous studies showed that stress-activated protein kinase JNKs (c-Jun NH2-terminal kinases) and p38 cooperated to activate VDR and increase vitamin D3-dependent growth inhibition in breast cancer cells. To determine whether vitamin D-mediated maturation is associated with JNK1 and VDR in colorectal cancer cells, we treated the human colon cancer cell HT29 with 1,25(OH)2-D3, and found that 1,25(OH)2-D3 significantly inhibited cell proliferation and induced apoptosis, which was associated with induction of phosphorylated JNK1 (p-JNK1) and p21,p27, which was also associated with increased the expression of PARP and cleaved Caspase 3. In the JNK1 knockout mouse model in which tumor spontaneously formed in intestinal tract, we found that VDR was significantly reduced or not expressed in mouse intestinal epithelial cells, compared to those in the wild-type mice. Further, we found that VDR transcriptional activity was lower in JNK1-/- mouse embryonic fibroblast cells (MEFs), assayed by transfection with VDR-element-Luc reporter. When the JNK1-/- MEFs were treated with calcitriol, the induced of VDR transcriptional activity was also attenuated, compared to that in JNK1+/+ MEFs. Moreover, increasing expression of activated JNK1 by transfection with pcDNA3-Flag-MKK7 (activated JNK1) in HT29 colon cancer cells, VDR-element-Luc was significantly increased, and VDR expression levels were also increased. Finally, we co-transfected HEK239 cells with pcDNA3-HA-VDR and pcDNA3-Flag-MKK7 plasmids and conducted co-immunoprecipitation assay, we found that VDR was physically binding to JNK1. Taken together, JNK1 interacted with VDR and affected VDR at transcriptional and translational levels. Thus, the status of JNK1 may play a critical role in vitamin D-medicated cancer prevention through modulating vitamin D receptor. Whether JNK1 affects VDR polymorphisms and then influences cancer prevention efficacy of vitamin D is under further investigation.

*Supported by National Natural Science Foundation Of China (81272251)

Citation Format: Qi Shi, Xiuli Bi, Wenfeng Fang, Dong Hu, Zhiguo Chen, Huali Dong, Wancai Yang, Wancai Yang. c-JunNH2-teminal kinase 1 plays a crucial role in vitamin D-mediated cancer cellmaturation through interacting with vitamin D receptor. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3655. doi:10.1158/1538-7445.AM2013-3655