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Lack of Immunomodulatory Interleukin-27 Enhances Oncogenic Properties of Mutant p53 In Vivo.

ABSTRACT: PURPOSE:p53 is mutated in about 50% of human cancers, mostly through missense mutations. Expression of mutant p53 is associated with poor clinical outcomes or metastasis. Although mutant p53 is inherently instable, various stressors such as DNA damage or expression of the oncogenic Kras or c-myc affect the oncogenic properties of mutant p53. However, the effects of inflammation on mutant p53 are largely unknown. IL27 is an important immunomodulatory cytokine, but its impact on mutant p53-driven tumorigenesis has not been reported. EXPERIMENTAL DESIGN:IL27RA(-/-) mice were bred with mutant p53 heterozygous (p53(R172H/+)) mice to obtain IL27RA(-/-)p53(H/+) and IL27RA(-/-)p53(H/H) mice. Mouse survival and tumor spectra for the cohort were analyzed. Stability of p53 protein was analyzed via IHC and Western blot analysis. RESULTS:This study unraveled that lack of IL27 signaling significantly shortened the survival duration of mice with tumors expressing both copies of the mutant p53 gene (Li-Fraumeni mouse model). Interestingly, in mice that were heterozygous for mutant p53, lack of IL27 signaling not only significantly shortened survival time but also doubled the incidence of osteosarcomas. Furthermore, lack of IL27 signaling is closely associated with increased mutant p53 stability in vivo from early age. CONCLUSIONS:These results suggest that IL27 signaling modulates the oncogenic properties of mutant p53 in vivo Clin Cancer Res; 22(15); 3876-83. ©2016 AACR.

SUBMITTER: Dibra D

PROVIDER: S-EPMC4970873 | biostudies-literature | 2016 Aug

REPOSITORIES: biostudies-literature

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Lack of Immunomodulatory Interleukin-27 Enhances Oncogenic Properties of Mutant p53 In Vivo.

Dibra Denada D Mitra Abhisek A Newman Melisa M Xia Xueqing X Cutrera Jeffry J JJ Gagea Mihai M Kleinerman Eugenie S ES Lozano Guillermina G Li Shulin S

Clinical cancer research : an official journal of the American Association for Cancer Research 20160315 15

<h4>Purpose</h4>p53 is mutated in about 50% of human cancers, mostly through missense mutations. Expression of mutant p53 is associated with poor clinical outcomes or metastasis. Although mutant p53 is inherently instable, various stressors such as DNA damage or expression of the oncogenic Kras or c-myc affect the oncogenic properties of mutant p53. However, the effects of inflammation on mutant p53 are largely unknown. IL27 is an important immunomodulatory cytokine, but its impact on mutant p53 ...[more]

PMID: 26979394

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Project description:To gain insights into the mechanisms by which certain second-site suppressor mutations rescue the function of a significant number of cancer mutations of the tumor suppressor protein p53, X-ray crystallographic structures of four p53 core-domain variants were determined. These include an oncogenic mutant, V157F, two single-site suppressor mutants, N235K and N239Y, and the rescued cancer mutant V157F/N235K/N239Y. The V157F mutation substitutes a smaller hydrophobic valine with a larger hydrophobic phenylalanine within strand S4 of the hydrophobic core. The structure of this cancer mutant shows no gross structural changes in the overall fold of the p53 core domain, only minor rearrangements of side chains within the hydrophobic core of the protein. Based on biochemical analysis, these small local perturbations induce instability in the protein, increasing the free energy by 3.6?kcal?mol(-1) (15.1?kJ?mol(-1)). Further biochemical evidence shows that each suppressor mutation, N235K or N239Y, acts individually to restore thermodynamic stability to V157F and that both together are more effective than either alone. All rescued mutants were found to have wild-type DNA-binding activity when assessed at a permissive temperature, thus pointing to thermodynamic stability as the critical underlying variable. Interestingly, thermodynamic analysis shows that while N239Y demonstrates stabilization of the wild-type p53 core domain, N235K does not. These observations suggest distinct structural mechanisms of rescue. A new salt bridge between Lys235 and Glu198, found in both the N235K and rescued cancer mutant structures, suggests a rescue mechanism that relies on stabilizing the ?-sandwich scaffold. On the other hand, the substitution N239Y creates an advantageous hydrophobic contact between the aromatic ring of this tyrosine and the adjacent Leu137. Surprisingly, the rescued cancer mutant shows much larger structural deviations than the cancer mutant alone when compared with wild-type p53. These suppressor mutations appear to rescue p53 function by creating novel intradomain interactions that stabilize the core domain, allowing compensation for the destabilizing V157F mutation.

Project description:Intact and broad immune cell effector functions and specific individual cytokines have been linked to HIV disease outcome, but their relative contribution to HIV control remains unclear. We asked whether the proteome of secreted cytokines and signaling factors in peripheral blood can be used to discover specific pathways critical for host viral control. A custom glass-based microarray, able to measure >600 plasma proteins involved in cell-to-cell communication, was used to measure plasma protein profiles in 96 HIV-infected, treatment-naive individuals with high (>50,000) or low (<10,000 HIV RNA copies/ml) viral loads. Univariate and regression model analysis demonstrate that plasma levels of soluble interleukin-27 (IL-27) are significantly elevated in individuals with high plasma viremia (P < 0.0001) and are positively correlated with proviral HIV-DNA copy numbers in peripheral blood mononuclear cells (PBMC) (Rho = 0.4011; P = 0.0027). Moreover, soluble IL-27 plasma levels are negatively associated with the breadth and magnitude of the total virus-specific T-cell responses and directly with plasma levels of molecules involved in Wnt/?-catenin signaling. In addition to IL-27, gene expression levels of the specific IL-27 receptor (IL27RA) in PBMC correlated directly with both plasma viral load (Rho = 0.3531; P = 0.0218) and the proviral copy number in the peripheral blood as an indirect measure of partial viral reservoir (Rho = 0.4580; P = 0.0030). These results were validated in unrelated cohorts of early infected subjects as well as subjects before and after initiation of antiretroviral treatment, and they identify IL-27 and its specific receptor as a critical immune axis for the antiviral immune response and as robust correlates of viral load and proviral reservoir size in PBMC.IMPORTANCE The detailed knowledge of immune mechanisms that contribute to HIV control is a prerequisite for the design of effective treatment strategies to achieve HIV cure. Cells communicate with each other by secreting signaling proteins, and the blood is a key conduit for transporting such factors. Investigating the communication factors promoting effective immune responses and having potentially antiviral functions against HIV using a novel focused omics approach ("communicome") has the potential to significantly improve our knowledge of effective host immunity and accelerate the HIV cure agenda. Including 140 subjects with variable viral loads and measuring the plasma levels of >600 soluble proteins, our data highlight the importance of Th17 cells and Wnt/?-catenin signaling in HIV control and especially identify the IL-27/IL-27 receptor subunit alpha (IL-27RA) axis as a predictor of plasma viral load and proviral copy number in the peripheral blood. These data may provide important guidance to therapeutic approaches in the HIV cure agenda.

Dataset Information

Lack of Immunomodulatory Interleukin-27 Enhances Oncogenic Properties of Mutant p53 In Vivo.

Publications

Lack of Immunomodulatory Interleukin-27 Enhances Oncogenic Properties of Mutant p53 In Vivo.

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