Critical Contribution of Nuclear Factor Erythroid 2-related Factor 2 (NRF2) to Electrophile-induced Interleukin-11 Production.

Nuclear factor erythroid 2-related factor 2 (NRF2) is a transcription factor that plays a crucial role in protection of cells from electrophile-induced toxicity through up-regulating phase II detoxifying enzymes and phase III transporters. We previously reported that oxidative stress induces up-regulation of interleukin-11 (IL-11), a member of the IL-6 family that ameliorates acetaminophen-induced liver toxicity. However, a role for IL-11 in protection of cells from electrophile-induced toxicity remains unclear. Here we show that an environmental electrophile, 1,2-naphthoquinone (1,2-NQ), but not 15d-prostaglandin J2 (PGJ2) or tert-butylhydroxyquinone (tBHQ), induced IL-11 production. Consistent with a crucial role for prolonged ERK activation in H2O2-induced IL-11 production, 1,2-NQ, but not 15d-PGJ2 or tBHQ, elicited prolonged ERK activation. Conversely, inhibition of the ERK pathway by a MEK inhibitor completely blocked 1,2-NQ-induced IL-11 production at both protein and mRNA levels, further substantiating an intimate cross-talk between ERK activation and 1,2-NQ-induced IL-11 production. Promoter analysis of the Il11 gene revealed that two AP-1 sites were essential for 1,2-NQ-induced promoter activities. Among various members of the AP-1 family, Fra-1 was up-regulated by 1,2-NQ, and its up-regulation was blocked by a MEK inhibitor. Although NRF2 was not required for H2O2-induced IL11 up-regulation, NRF2 was essential for 1,2-NQ-induced IL11 up-regulation by increasing Fra-1 proteins possibly through promoting mRNA translation of FOSL1 Finally, intraperitoneal administration of 1,2-NQ induced body weight loss in wild-type mice, which was further exacerbated in Il11ra1-/- mice compared with Il11ra1+/- mice. Together, both Fra-1 and NRF2 play crucial roles in IL-11 production that protects cells from 1,2-NQ intestinal toxicity.

Autocrine production of IL-11 mediates tumorigenicity in hypoxic cancer cells.

IL-11 and its receptor, IL-11Ra, are expressed in human cancers; however, the functional role of IL-11 in tumor progression is not known. We found that IL11 is a hypoxia-inducible, VHL-regulated gene in human cancer cells and that expression of IL11 mRNA was dependent, at least in part, on HIF-1. A cooperative interaction between HIF-1 and AP-1 mediated transcriptional activation of the IL11 promoter. Additionally, we found that human cancer cells expressed a functional IL-11Ra subunit, which triggered signal transduction either by exogenous recombinant human IL-11 or by autocrine production of IL-11 in cells cultured under hypoxic conditions. Silencing of IL11 dramatically abrogated the ability of hypoxia to increase anchorage-independent growth and significantly reduced tumor growth in xenograft models. Notably, these results were phenocopied by partial knockdown of STAT1 in a human prostate cancer cell line (PC3), suggesting that this pathway may play an important role in mediating the effects of IL-11 under hypoxic conditions. In conclusion, these results identify IL11 as an oxygen- and VHL-regulated gene and provide evidence of a pathway "hijacked" by hypoxic cancer cells that may contribute to tumor progression.

Evaluating the role of IL-11, a novel cytokine in the IL-6 family, in a mouse model of spinal cord injury.

BACKGROUND: Spinal cord injury (SCI) is a devastating condition with substantial functional and social morbidity. Previous research has established that the neuroinflammatory response plays a significant role in cord damage post-SCI. However, global immunosuppressive therapies have demonstrated mixed results. As a result, more specific therapies modulating inflammation after injury are needed. In this regard, research into cytokine signaling has demonstrated that cytokines of the gp130 family including IL-6 and leukemia inhibitory factor (LIF) play key roles in mediating damage to the spinal cord. Since members of the gp130 family all share a common signal transduction pathway via the JAK/STAT system, we performed the first study of a relatively new member of the gp130 family, IL-11, in SCI. METHODS: A validated clip-compression mouse model of SCI was used to assess for temporal changes in expression of IL-11 and its receptor, IL-11Rα, post-SCI. To elucidate the role of IL-II in the pathophysiology of SCI, we compared differences in locomotor recovery (Basso Mouse Score; CatWalk), electrophysiological spinal cord signaling, histopathology, and the acute inflammatory neutrophil response in IL-11Rα knockouts with littermate wild-type C57BL/6 mice. RESULTS: We found an increase in gene expression of IL-11 in the spinal cord to a peak at twenty-four hours post-SCI with increases in IL-11Rα gene expression, peaking at seven days post-SCI. In spite of clear changes in the temporal expression of both IL-11 and its receptor, we found that there were no significant differences in motor function, electrophysiological signaling, histopathology, or neutrophil infiltration into the spinal cord between wild-type and knockout mice. CONCLUSIONS: This is the first study to address IL-11 in SCI. This study provides evidence that IL-11 signaling may not play as significant a role in SCI as other gp130 cytokines, which will ideally guide future therapy design and the signaling pathways those therapies target.

Interleukin 11 is upregulated in uterine lavage and endometrial cancer cells in women with endometrial carcinoma.

BACKGROUND: Interleukin (IL) 11 is produced by human endometrium and endometrial cancer tissue. It has roles in endometrial epithelial cell adhesion and trophoblast cell invasion, two important processes in cancer progression. This study aimed to determine the levels of IL11 in uterine lavage fluid in women with endometrial cancer and postmenopausal women. It further aimed to determine the levels of IL11 protein and its signaling molecules in human endometrial cancer of varying grades, and endometrium from postmenopausal women and IL11 signalling mechanisms in endometrial cancer cell lines. METHODS: IL11 levels in uterine lavage were measured by ELISA. IL11, IL11 receptor(R) alpha, phosphorylated (p) STAT3 and SOCS3 were examined by immunohistochemistry in endometrial carcinomas and in control endometrium from postmenopausal women and normal cycling women. The effect of IL11 on pSTAT3/STAT3 and SOCS3 protein abundance in endometrial cancer cell lines and non-cancer endometrial epithelial cells was determined by Western blot. RESULTS: IL11 was present in uterine flushings and was significantly higher in women with Grade 1 carcinomas compared to postmenopausal women (p < 0.05). IL11 immunostaining was significantly elevated in the endometrial tumour epithelial cells from Grade 1 and 3 compared to endometrial epithelium from postmenopausal and cycling women. IL11R alpha immunostaining intensity was increased in cancer epithelium in the Grades 1 and 2 tumours compared to epithelium from postmenopausal women. Both IL11 and IL11R alpha localized to vascular endothelial and smooth muscle cells while IL11 also localized to subsets of leucocytes in the cancer tissues. pSTAT3 was found in both the tumour epithelial and stromal compartments but was maximal in the tumour epithelial cells, while SOCS3 was predominantly found in the tumour epithelial cells. pSTAT3 staining intensity was significantly higher in Grade 1 and 2 tumour epithelial cells compared to epithelial cells from cycling and postmenopausal women. SOCS3 staining intensity did not differ between between each tumour and postmenopausal endometrial epithelium but SOCS3 in cycling endometrium was significantly higher compared to postmenopausal and Tumour Grades 2 and 3. IL11 increased pSTAT3/STAT3 in all tumour cell lines, while SOCS3 abundance was increased only in one tumour cell line. CONCLUSIONS: The present study suggests that IL11 in uterine washings may be useful as a diagnostic marker for early stage endometrial cancer. It indicates that IL11, along with its specific receptor, IL11R alpha, and downstream signalling molecules, STAT3 and SOCS3, are likely to play a role in the progression of endometrial carcinoma. The precise role of IL11 in endometrial cancer remains to be elucidated.