Inflammation mobilizes copper metabolism to promote colon tumorigenesis via an IL-17-STEAP4-XIAP axis.

Copper levels are known to be elevated in inflamed and malignant tissues. But the mechanism underlying this selective enrichment has been elusive. In this study, we report a axis by which inflammatory cytokines, such as IL-17, drive cellular copper uptake via the induction of a metalloreductase, STEAP4. IL-17-induced elevated intracellular copper level leads to the activation of an E3-ligase, XIAP, which potentiates IL-17-induced NFκB activation and suppresses the caspase 3 activity. Importantly, this IL-17-induced STEAP4-dependent cellular copper uptake is critical for colon tumor formation in a murine model of colitis-associated tumorigenesis and STEAP4 expression correlates with IL-17 level and XIAP activation in human colon cancer. In summary, this study reveals a IL-17-STEAP4-XIAP axis through which the inflammatory response induces copper uptake, promoting colon tumorigenesis

Deriving Debris‐Flow Dynamics From Real‐Time Impact‐Force Measurements

Understanding the impact forces exerted by debris flows is limited by a lack of direct field measurements and validated numerical models. In this study, we use real‐time impact‐force measurements and field observations of debris flows recorded by a sensor network in Jiangjia Ravine, China, to quantify the impact‐force distribution of natural debris flows. We observed one debris flow event during and after a storm on 25 August 2004, including 42 short‐duration surges and seven long‐duration surges, and impact‐force signals were successfully recorded for 38 surges. Our observed debris flows comprise high‐viscosity laminar flows with high sediment concentration and frequent solid‐to‐solid interactions. We identified a large magnitude (up to 1 kN), high‐frequency (greater than 1 Hz) fluctuating component of the impact force that we interpret as solid particle impact on the sensors. The variability of particle impact forces increases with the mean impact force. Our results show that a log‐logistic distribution can describe the probability density distribution of impact forces. Solid‐dominated surges and fluid‐dominated intersurge flows have similar impact‐force distributions, but surges usually have heavy tails. We created a dimensionless number to describe the impact force and correlated it against existing dimensionless parameters. Finally, we develop a simple particle impact model to understand the relationship between flow dynamics and the impact force inside debris flows that could be applied to improve debris‐flow flume experiments and design debris‐flow hazard mitigation measures.Plain Language Summary: Debris flows are fast‐moving mixtures of dirt and water that can cause huge damage to buildings and infrastructures and harm people. For effective hazard protection, we need to understand the impact forces exerted by debris flows. In this study, we measured impact forces at the high temporal resolution of 49 debris‐flow surges during and after a storm on 25 August 2004, recorded by a sensor array in Jiangjia Ravine, southwestern China. We develop statistical descriptions of the mean and the variability of the force and derive a relationship between flow dynamics and the impact force using a simple particle impact model. Our results could be applied to improve the future design of debris‐flow hazard mitigation measures.Key Points: Log‐logistic distribution is a good fit for debris‐flow impact force probability density functions. Debris‐flow surges and intersurge flows have similar impact force distribution, but surges usually have heavy tails. A simple particle impact model can explain the debris‐flow impact force signal.National Natural Science Foundation of China http://dx.doi.org/10.13039/501100001809National Key R&D Program of Chinahttps://doi.org/10.6084/m9.figshare.21078136.v5https://doi.org/10.6084/m9.figshare.21078154.v

Repression of <i>GFI1</i> by p53 is independent of HDACs and p21^Cip1.

<p>(A) <i>p53</i>^−/− HCT116 cells were transfected with <i>GFI1</i> promoter (−1933/+468 bp) luciferase reporter construct without or with p53 and treated with TSA (0.15 µM) 8 hrs later. Luciferase activities were measured 24 hrs after TSA treatment. (B) <i>p21^Cip1</i>^+/+ and <i>p21^Cip1</i>^−/− HCT116 cells were transfected with <i>GFI1</i> promoter (−1933/+468 bp) reporter construct and treated with Doxo (400 ng/ml) 8 hrs later. Luciferase activities were measured 16 hrs after Doxo treatment.</p

p53 binds to and represses <i>GFI1</i>.

<p>(A) <i>p53</i>^−/− HCT116 cells were transfected with the <i>GFI1</i> promoter (−1933/+468 bp) luciferase reporter construct along with the wild type (WT) or W248 mutant p53. Luciferase activities were measured 36 hrs later and normalized for β-Gal activities. Data are shown as mean ± SD. (B) <i>p53</i>^+/+ and <i>p53</i>^−/− HCT116 cells were transfected with <i>GFI1</i> promoter luciferase reporter construct and treated with Doxo (400 ng/ml) 8 hrs later. Luciferase activities were measured 16 hrs after Doxo treatment. (C) <i>p53</i>^−/− HCT116 cells were transfected with pGL3-basic plasmid containing <i>GFI1</i> promoter fragment (−4840/+184 bp) either alone or together with p53. ChIP assays were carried out using the anti human p53 or an irrelevant species-matched antibody. The indicated regions of <i>GFI1</i> promoter were amplified by PCR. (D) ChIP experiment was carried out on Molt3 cells using the anti human p53 and control antibodies.</p

Gfi1 has no significant effect on the expression of Bax, Bak and Bcl-2.

<p>(A) Ba/F3 and Ramos cells transduced with the inducible Gfi1-expressing lentiviral construct were preincubated with Doxy (1 µg/ml) for 24 hrs and then treated with Doxo (100 ng/ml) for times as indicated. The expression of Gfi1 and the Bcl-2 family members as indicated was examined by Western blot analysis. (B) The levels of the Bcl-2 family members in control and GFI1 knocked down U937 and HL-60 cells were examined by Western blot analysis.</p

Mapping of the <i>GFI1</i> promoter region required for p53-mediated repression.

<p>(A and B) Schematic diagrams of <i>GFI1</i> promoter fragments cloned into pGL3-basic vector (A) or inserted upstream of the <i>SV40</i> promoter of the pGL3-promoter vector. (C and D) p53^−/− HCT116 cells were transfected with the indicated <i>GFI1</i> promoter luciferase reporter constructs without or with p53. Luciferase activities were measured 36 hrs after transfection.</p

GFI1 protein and mRNA levels are upregulated upon p53 knockdown.

<p>(A) MO7e and Molt3 cells were infected with the lentivirus containing a p53 shRNA. The expression of GFI1 and p53 proteins was examined by Western blot analysis. GFI1 mRNA levels were examined by RT-PCR. Subsequently, control (Ctr) and p53 knocked down (KD) MO7e (B) and Molt3 (D) cells were treated with Doxo (25 ng/ml) for times as indicated and examined for expression of p53 and GFI1. The results shown in B and D were quantitated using ImageJ and normalized based on the levels of β-actin protein and GAPDH mRNA for MO7e (C) and Molt3 (E) cells. (F) Human umbilical cord blood CD34+ cells were treated with Doxo prior to evaluation of the expression of p53 and GFI1.</p

Overexpression of Gfi1 inhibits DNA damage-induced cell death.

<p>Ba/F3 (A–C) and Ramos (D–F) cells were transduced with the inducible lentiviral expression construct for Gfi1 and examined for Gfi1 expression by Western blot analysis after incubation with Doxy (1 µg/ml) for 24 hrs (A and D). Cells were then exposed to Doxo (100 ng/ml for Ba/F3 cells and 2 mg/ml for Ramos cells) for 18 hrs with or without preincubation with Doxy (1 µg/ml) for 24 hrs. Cell viabilities were determined by exclusion of trypan blue staining (B and E), percentages of apoptotic (annexin V-positive) cells were assessed by flow cytometry after staining with annexin V and 7-AAD (C), and the numbers of living cells were quantitated by MTS assay (F).</p

Knockdown of GFI1 increases cell death in response to DNA damage.

<p>U937 (A–C) and HL-60 (D–F) cells were transduced with empty lentivirus (Ctr) or lentiviruses containing two different shRNAs against <i>GFI1</i> and examined for GFI1 expression by Western blot analysis (A and D). Cells were left untreated or treated with Doxo at 200 ng/ml for 10 hrs prior to evaluation of living cell numbers by trypan blue exclusion (B and E) and MTS assays (C and F).</p

Identification of the repressive p53 RE in <i>GFI1</i> core promoter.

<p>(A) Nucleotide sequences of wild type (WT) and mutated <i>GFI1</i> core promoter fragments as compared with conserved repressive p53 RE. Potential p53 RE in <i>GFI1</i> core promoter are underlined. Mutated nucleotides are in bold. (B) <i>p53</i>^−/− HCT116 cells were transfected with WT or M1 <i>GFI1</i> promoter (−1933/+468 bp; left panel), or WT or M2 <i>GFI1</i> promoter (−460/+6 bp; right panel) luciferase reporter construct without or with p53. Luciferase activity was measured 36 hrs after transfection. (C) <i>p53</i>^−/− HCT116 cells were transfected with pGL3-basic plasmid containing WT or M1 <i>GFI1</i> promoter fragment (−4840/+184 bp) along with p53. Binding of p53 to the <i>GFI1</i> promoter fragments was examined by ChIP assays (left panel). Expression of p53 was confirmed by Western blot analysis (right panels).</p