Fam72a enforces error-prone DNA repair during antibody diversification.

Efficient humoral responses rely on DNA damage, mutagenesis and error-prone DNA repair. Diversification of B cell receptors through somatic hypermutation and class-switch recombination are initiated by cytidine deamination in DNA mediated by activation-induced cytidine deaminase (AID)1 and by the subsequent excision of the resulting uracils by uracil DNA glycosylase (UNG) and by mismatch repair proteins1-3. Although uracils arising in DNA are accurately repaired1-4, how these pathways are co-opted to generate mutations and double-strand DNA breaks in the context of somatic hypermutation and class-switch recombination is unknown1-3. Here we performed a genome-wide CRISPR-Cas9 knockout screen for genes involved in class-switch recombination and identified FAM72A, a protein that interacts with the nuclear isoform of UNG (UNG2)5 and is overexpressed in several cancers5. We show that the FAM72A-UNG2 interaction controls the levels of UNG2 and that class-switch recombination is defective in Fam72a-/- B cells due to the upregulation of UNG2. Moreover, we show that somatic hypermutation is reduced in Fam72a-/- B cells and that its pattern is skewed upon upregulation of UNG2. Our results are consistent with a model in which FAM72A interacts with UNG2 to control its physiological level by triggering its degradation, regulating the level of uracil excision and thus the balance between error-prone and error-free DNA repair. Our findings have potential implications for tumorigenesis, as reduced levels of UNG2 mediated by overexpression of Fam72a would shift the balance towards mutagenic DNA repair, rendering cells more prone to acquire mutations.

CD95-Mediated Calcium Signaling Promotes T Helper 17 Trafficking to Inflamed Organs in Lupus-Prone Mice.

CD95 ligand (CD95L) is expressed by immune cells and triggers apoptotic death. Metalloprotease-cleaved CD95L (cl-CD95L) is released into the bloodstream but does not trigger apoptotic signaling. Hence, the pathophysiological role of cl-CD95L remains unclear. We observed that skin-derived endothelial cells from systemic lupus erythematosus (SLE) patients expressed CD95L and that after cleavage, cl-CD95L promoted T helper 17 (Th17) lymphocyte transmigration across the endothelial barrier at the expense of T regulatory cells. T cell migration relied on a direct interaction between the CD95 domain called calcium-inducing domain (CID) and the Src homology 3 domain of phospholipase Cγ1. Th17 cells stimulated with cl-CD95L produced sphingosine-1-phosphate (S1P), which promoted endothelial transmigration by activating the S1P receptor 3. We generated a cell-penetrating CID peptide that prevented Th17 cell transmigration and alleviated clinical symptoms in lupus mice. Therefore, neutralizing the CD95 non-apoptotic signaling pathway could be an attractive therapeutic approach for SLE treatment.

Disrupting the CD95-PLCγ1 interaction prevents Th17-driven inflammation.

CD95L is a transmembrane ligand (m-CD95L) that is cleaved by metalloproteases to release a soluble ligand (s-CD95L). Unlike m-CD95L, interaction between s-CD95L and CD95 fails to recruit caspase-8 and FADD to trigger apoptosis and instead induces a Ca2+ response via docking of PLCγ1 to the calcium-inducing domain (CID) within CD95. This signaling pathway induces accumulation of inflammatory Th17 cells in damaged organs of lupus patients, thereby aggravating disease pathology. A large-scale screen revealed that the HIV protease inhibitor ritonavir is a potent disruptor of the CD95-PLCγ1 interaction. A structure-activity relationship approach highlighted that ritonavir is a peptidomimetic that shares structural characteristics with CID with respect to docking to PLCγ1. Thus, we synthesized CID peptidomimetics abrogating both the CD95-driven Ca2+ response and transmigration of Th17 cells. Injection of ritonavir and the CID peptidomimetic into lupus mice alleviated clinical symptoms, opening a new avenue for the generation of drugs for lupus patients.

Synthesis of peptidomimetics and chemo-biological tools for CD95/PLCγ1 interaction analysis.

The death receptor CD95 (also known as Fas) induces apoptosis through protein/protein association and the formation of the death-inducing signaling complex. On the other hand, in certain biological conditions, this receptor recruits different proteins and triggers the formation of another complex designated motility-inducing signaling complex, which promotes cell migration and inflammation. This pathway relies on a short sequence of CD95, called calcium-inducing domain (CID), which interacts with the phospholipase PLCγ1. To better understand how CID/PLCγ1 interaction occurs, we synthesized different α-AA peptides mimicking CID. Some of these peptidomimetics are as potent as the natural peptide to disrupt the CID/PLCγ1 interaction and cell migration, and showed improved pharmacokinetic properties. We also generated biotinyl- and palmitoyl-labelled peptidomimetics, useful chemico-biological tools to further explore the pro-inflammatory signal of CD95, which plays an important role in the pathogenesis of lupus and other autoimmune diseases.

All anti-vascular endothelial growth factor drugs can induce 'pre-eclampsia-like syndrome': a RARe study.

BACKGROUND: Specific therapies that target vascular endothelial growth factor (VEGF) and its receptors have improved the survival of patients with metastatic cancers, but can induce side effects. Renal side effects (proteinuria, hypertension and renal failure) are underestimated. METHODS: The French RARe (Reins sous traitement Anti-VEGF Registre) study collects data on patients with cancer who had a renal biopsy because of major renal side effects during treatment with anti-VEGF drugs. RESULTS: We collected 22 renal biopsies performed 16.2±10.6 months after the beginning of treatment; of which 21 had hypertension, mean proteinuria was 2.97±2.00 g/day and mean serum creatinine, 134±117 µmol/L. Thrombotic microangiopathy (TMA) was observed in 21 biopsy specimens, sometimes associated with acute tubular necrosis (ATN; n=4). TMA histological lesions were more important than the biological signs of TMA could suggest. Patients with ATN of >20% had higher serum creatinine levels than those with only TMA (231 versus 95 µmol/L). Nephrin, podocin and synaptopodin were variably down-regulated in all renal biopsies. VEGF was down-regulated in all glomeruli. CONCLUSION: This study underlines the importance of regular clinical and biological cardiovascular and renal checking during all anti-VEGF therapies for cancer for early detection of renal dysfunction. Collaboration between oncologists and nephrologists is essential. In such cases, renal biopsy might help in appreciating the severity of the renal lesions and after multidisciplinary discussion whether or not it is safe to continue the treatment.

Afatinib or Bevacizumab in combination with Osimertinib efficiently control tumor development in orthotopic murine models of non-small lung cancer.

Lung cancer is one of the most common and deadliest cancers. Preclinical models are essential to study new therapies and combinations taking tumor genetics into account. We have established cell lines expressing the luciferase gene from lines with varied genetic backgrounds, commonly encountered in patients with pulmonary adenocarcinoma. We have characterized these lines by testing their response to multiple drugs. Thus, we have developed orthotopic preclinical mouse models of NSCLC with very high engraftment efficiency. These models allow the easy monitoring of tumor growth, particularly in response to treatment, and of tumor cells dissemination in the body. We show that concomitant treatment with osimertinib (3rd generation tyrosine kinase inhibitor targeting mutated EGFR) and bevacizumab (anti-angiogenic targeting VEGF) can have a beneficial therapeutic effect on EGFR-mutated tumors. We also show that the addition of afatinib to osimertinib-treated tumors in escape leads to tumor growth inhibition. No such effect is observed with selumetinib or simvastatin. These preclinical mouse models therefore make it possible to test innovative therapeutic combinations and are also a tool of choice for studying resistance mechanisms.

KDM6B drives epigenetic reprogramming associated with lymphoid stromal cell early commitment and immune properties.

Mature lymphoid stromal cells (LSCs) are key organizers of immune responses within secondary lymphoid organs. Similarly, inflammation-driven tertiary lymphoid structures depend on immunofibroblasts producing lymphoid cytokines and chemokines. Recent studies have explored the origin and heterogeneity of LSC/immunofibroblasts, yet the molecular and epigenetic mechanisms involved in their commitment are still unknown. This study explored the transcriptomic and epigenetic reprogramming underlying LSC/immunofibroblast commitment. We identified the induction of lysine demethylase 6B (KDM6B) as the primary epigenetic driver of early immunofibroblast differentiation. In addition, we observed an enrichment for KDM6B gene signature in murine inflammatory fibroblasts and pathogenic stroma of patients with autoimmune diseases. Last, KDM6B was required for the acquisition of LSC/immunofibroblast functional properties, including the up-regulation of CCL2 and the resulting recruitment of monocytes. Overall, our results reveal epigenetic mechanisms that participate in the early commitment and immune properties of immunofibroblasts and support the use of epigenetic modifiers as fibroblast-targeting strategies in chronic inflammation.

UnAIDed Class Switching in Activated B-Cells Reveals Intrinsic Features of a Self-Cleaving IgH Locus.

Activation-induced deaminase (AID) is the major actor of immunoglobulin (Ig) gene diversification in germinal center B-cells. From its first description, it was considered as mandatory for class switch recombination (CSR), and this discovery initiated a long quest for all of the AID-interacting factors controlling its activity. The mechanisms focusing AID-mediated DNA lesions to given target sequences remain incompletely understood with regards the detailed characterization of optimal substrates in which cytidine deamination will lead to double strand breaks (DSBs) and chromosomal cleavage. In an effort to reconsider whether such CSR breaks absolutely require AID, we herein provide evidence, based on deep-sequencing approaches, showing that this dogma is not absolute in both human and mouse B lymphocytes. In activated B-cells from either AID-deficient mice or human AID-deficient patients, we report an intrinsic ability of the IgH locus to undergo "on-target" cleavage and subsequent synapsis of broken regions in conditions able to yield low-level CSR. DNA breaks occur in such conditions within the same repetitive S regions usually targeted by AID, but their repair follows a specific pathway with increased usage of microhomology-mediated repair. These data further demonstrate the role of AID machinery as not initiating de novo chromosomal cleavage but rather catalyzing a process which spontaneously initiates at low levels in an appropriately conformed IgH locus.

ING2 tumor suppressive protein translocates into mitochondria and is involved in cellular metabolism homeostasis.

ING2 (Inhibitor of Growth 2) is a tumor suppressor gene that has been implicated in critical biological functions (cell-cycle regulation, replicative senescence, DNA repair and DNA replication), most of which are recognized hallmarks of tumorigenesis occurring in the cell nucleus. As its close homolog ING1 has been recently observed in the mitochondrial compartment, we hypothesized that ING2 could also translocate into the mitochondria and be involved in new biological functions. In the present study, we demonstrate that ING2 is imported in the inner mitochondrial fraction in a redox-sensitive manner in human cells and that this mechanism is modulated by 14-3-3η protein expression. Remarkably, ING2 is necessary to maintain mitochondrial ultrastructure integrity without interfering with mitochondrial networks or polarization. We observed an interaction between ING2 and mtDNA under basal conditions. This interaction appears to be mediated by TFAM, a critical regulator of mtDNA integrity. The loss of mitochondrial ING2 does not impair mtDNA repair, replication or transcription but leads to a decrease in mitochondrial ROS production, suggesting a detrimental impact on OXPHOS activity. We finally show using multiple models that ING2 is involved in mitochondrial respiration and that its loss confers a protection against mitochondrial respiratory chain inhibition in vitro. Consequently, we propose a new tumor suppressor role for ING2 protein in the mitochondria as a metabolic shift gatekeeper during tumorigenesis.

Alterations of EDEM1 functions enhance ATF6 pro-survival signaling.

Activating transcription factor 6 alpha (referred to as ATF6 hereafter) is an endoplasmic reticulum (ER)-resident glycoprotein and one of the three sensors of the unfolded protein response (UPR). Upon ER stress, ATF6 is exported to the Golgi complex where it is cleaved by the S1P and S2P proteases thus releasing ATF6 cytosolic fragment and leading to the transcription of ATF6 target genes. In this study, we performed a phenotypic small-interfering RNA (siRNA) screening to better characterize the ER mechanisms involved in ATF6 activation upon ER stress. This revealed that silencing of ER-degradation-enhancing alpha-mannosidase-like protein-1 (EDEM1) increased the bioavailability of ER stress-induced ATF6 export to the Golgi complex through the stabilization of the natively unstable ATF6 protein. Moreover, we characterized a somatic variant of EDEM1 (N198I) found in hepatocellular carcinoma that alters ATF6 signaling and might provide a selective advantage to the transforming cells. Hence, our work confirms the natively unstable nature of ATF6 and links this property to potentially associated pro-oncogenic functions.

Dual IRE1 RNase functions dictate glioblastoma development.

Proteostasis imbalance is emerging as a major hallmark of cancer, driving tumor aggressiveness. Evidence suggests that the endoplasmic reticulum (ER), a major site for protein folding and quality control, plays a critical role in cancer development. This concept is valid in glioblastoma multiform (GBM), the most lethal primary brain cancer with no effective treatment. We previously demonstrated that the ER stress sensor IRE1α (referred to as IRE1) contributes to GBM progression, through XBP1 mRNA splicing and regulated IRE1-dependent decay (RIDD) of RNA Here, we first demonstrated IRE1 signaling significance to human GBM and defined specific IRE1-dependent gene expression signatures that were confronted to human GBM transcriptomes. This approach allowed us to demonstrate the antagonistic roles of XBP1 mRNA splicing and RIDD on tumor outcomes, mainly through selective remodeling of the tumor stroma. This study provides the first demonstration of a dual role of IRE1 downstream signaling in cancer and opens a new therapeutic window to abrogate tumor progression.

Plasma level and tissue expression of vascular endothelial growth factor in renal cell carcinoma: a prospective study of 50 cases.

Vascular endothelial growth factor (VEGF) is the major factor involved in angiogenesis. Although it is known that one of the functions of VEGF is to regulate neovascularization in renal cell carcinomas, the relationship between the production of VEGF in tumor tissue and its concentration in blood has not yet been studied. The aims of this study were to determine, in a series of conventional renal cell carcinoma (CRCC) cases, (1) VEGF expression and VEGF pattern in tumor cells, (2) the relationship between VEGF expression/pattern and VEGF levels in plasma (pVEGF), and (3) the association with usual clinical and pathologic prognostic factors. Fifty patients operated on for CRCC by radical nephrectomy were included. Clinical and histologic parameters were studied. VEGF expression and VEGF pattern in tumor cells was immunohistochemically recorded. pVEGF levels and platelet count were analyzed in relation to clinical and histologic parameters. Intratumoral VEGF expression associated with a cytoplasmic VEGF pattern was significantly higher in patients with high pVEGF levels (P = .01). Both VEGF expression and pVEGF levels were significantly correlated with Fuhrman grade (P = .002 and P = .01, respectively) and tumor stage (P = .006 and P = .008, respectively). In addition, VEGF expression was also correlated with tumor necrosis (P = .001) and progression (P = .001). We demonstrated that in CRCC with tumor necrosis, VEGF expression, pVEGF levels, and platelet count were significantly higher than in CRCC with no tumor necrosis (P = .001, P = .03, and P = .001, respectively). Our results revealed that cytoplasmic VEGF expression and pVEGF levels are associated with usual prognostic factors and progression in CRCC, which may allow VEGF to be used as a prognostic marker for CRCC, especially in patients with VEGF-targeted therapy.

The pVHL172 isoform is not a tumor suppressor and up-regulates a subset of pro-tumorigenic genes including TGFB1 and MMP13.

The von Hippel-Lindau (VHL) tumor suppressor gene is often deleted or mutated in ccRCC (clear cell renal cell carcinoma) producing a non-functional protein. The gene encodes two mRNA, and three protein isoforms (pVHL213, pVHL160 and pVHL172). The pVHL protein is part of an E3 ligase complex involved in the ubiquitination and proteasomal degradation of different proteins, particularly hypoxia inducible factors (HIF) that drive the transcription of genes involved in the regulation of cell proliferation, angiogenesis or extracellular matrix remodelling. Other non-canonical (HIF-independent) pVHL functions have been described. A recent work reported the expression of the uncharacterized protein isoform pVHL172 which is translated from the variant 2 by alternative splicing of the exon 2. This splice variant is sometimes enriched in the ccRCCs and the protein has been identified in the respective samples of ccRCCs and different renal cell lines. Functional studies on pVHL have only concerned the pVHL213 and pVHL160 isoforms, but no function was assigned to pVHL172. Here we show that pVHL172 stable expression in renal cancer cells does not regulate the level of HIF, exacerbates tumorigenicity when 786-O-pVHL172 cells were xenografted in mice. The pVHL172-induced tumors developed a sarcomatoid phenotype. Moreover, pVHL172 expression was shown to up regulate a subset of pro-tumorigenic genes including TGFB1, MMP1 and MMP13. In summary we identified that pVHL172 is not a tumor suppressor. Furthermore our findings suggest an antagonistic function of this pVHL isoform in the HIF-independent aggressiveness of renal tumors compared to pVHL213.

CD90 Expression Controls Migration and Predicts Dasatinib Response in Glioblastoma.

Purpose: CD90 (Thy-1) is a glycophosphatidylinositol-anchored glycoprotein considered as a surrogate marker for a variety of stem cells, including glioblastoma (GBM) stem cells (GSC). However, the molecular and cellular functions of CD90 remain unclear.Experimental Design: The function of CD90 in GBM was addressed using cellular models from immortalized and primary GBM lines, in vivo orthotopic mouse models, and GBM specimens' transcriptome associated with MRI features from GBM patients. CD90 expression was silenced in U251 and GBM primary cells and complemented in CD90-negative U87 cells.Results: We showed that CD90 is not only expressed on GSCs but also on more differentiated GBM cancer cells. In GBM patients, CD90 expression was associated with an adhesion/migration gene signature and with invasive tumor features. Modulation of CD90 expression in GBM cells dramatically affected their adhesion and migration properties. Moreover, orthotopic xenografts revealed that CD90 expression induced invasive phenotypes in vivo Indeed, CD90 expression led to enhanced SRC and FAK signaling in our GBM cellular models and GBM patients' specimens. Pharmacologic inhibition of these signaling nodes blunted adhesion and migration in CD90-positive cells. Remarkably, dasatinib blunted CD90-dependent GBM cell invasion in vivo and killed CD90high primary GSC lines.Conclusions: Our data demonstrate that CD90 is an actor of GBM invasiveness through SRC-dependent mechanisms and could be used as a predictive factor for dasatinib response in CD90high GBM patients. Clin Cancer Res; 23(23); 7360-74. ©2017 AACR.

The utility of Ki-67 expression in the differential diagnosis of prostatic intraepithelial neoplasia and ductal adenocarcinoma.

Cribriform and/or papillary prostatic lesions observed on limited tissue, such as needle biopsy, can pose diagnostic dilemmas. One such area of difficulty is the distinction between papillary and/or cribriform prostatic high-grade prostatic intraepithelial neoplasia (HG-PIN) and ductal adenocarcinoma. Over 48 months, we identified 17 cases of ductal adenocarcinoma and 17 cases of HG-PIN from radical retropubic prostatectomy specimens. The HG-PIN lesions were in all cases associated with an acinar prostatic adenocarcinoma component. For each case, we evaluated the proliferative activity, assessed by Ki-67 immunohistochemistry. The majority (82%) of ductal adenocarcinomas were composed of mixed papillary and cribriform patterns, with the remaining demonstrating pure papillary or cribriform patterns. The HG-PIN lesions showed a papillary, cribriform, or mixed papillary/cribriform architecture. The proliferative activity, defined as Ki-67 labeling index, was statistically higher in ductal adenocarcinoma (mean 33%, range 21%-66%) as compared with HG-PIN (mean 6%, range 2%-15%), with no overlap in the Ki-67 indices (P = 0001). A combination of histological features and measurements of cellular proliferation may be helpful to distinguish HG-PIN from ductal adenocarcinoma in limited prostatic tissue samples.

Development of the uterine shell glands during the preovulatory and early gestation periods in oviparous and viviparous Lacerta vivipara.

The evolutionary process leading to the emergence of viviparity in Squamata consists of lengthening the period of egg retention in utero coupled with marked reduction in the thickness of the eggshell. We used light microscopy and scanning electron microscopy to study uterine structure during the reproductive cycle of oviparous and viviparous females of the reproductively bimodal Lacerta vivipara. We compared the structure of the uterine shell glands, which secrete components of the eggshell, during preovulatory and early gestation phases of the reproductive cycle and also compared histochemistry of the eggshells. The uterine glands of both reproductive forms undergo considerable growth within a period of a few weeks during folliculogenesis and vitellogenesis preceding ovulation. The majority of the proteinaceous fibers of the shell membrane are secreted early in embryonic development and the uterine glands regress shortly thereafter. This supports previous observations indicating that, in Squamata, secretion of the shell membrane occurs very rapidly after ovulation. The most striking differences between reproductive modes were larger uterine glands at late vitellogenesis in oviparous females, 101 microm compared to 60 microm in viviparous females, and greater thickness of the shell membrane during early gestation in oviparous females (52-73 microm) compared to viviparous females (4-8 microm). Our intraspecific comparison supports the conclusions of previous studies that, prior to ovulation, the uterine glandular layer is less developed in viviparous than in oviparous species, and that this is the main factor accounting for differences in the thickness of the shell membrane of the two reproductive forms of squamates.

Immunohistochemical analysis of tumor polyamines discriminates high-risk patients undergoing nephrectomy for renal cell carcinoma.

Renal cell carcinoma (RCC) is known to display a wide variation in biological behavior and clinical outcome. Although usual bioclinical prognostic parameters (eg, nuclear grade, tumor stage) are to a certain extent useful in predicting the outcome of RCC after radical nephrectomy, they now appear to be insufficient. The polyamines (spermidine, spermine, and putrescine) are ubiquitous polycations that are essential for cell proliferation. To support their excessive proliferation, cancer cells have high rates of polyamine metabolism. Indeed, malignant cells typically have higher polyamine levels than their normal counterparts. Before this report, antipolyamine antibodies that are potentially valuable tools for the in situ observation of polyamines had not been exploited in clinical conditions. In the present study, tumor tissues obtained from radical nephrectomy performed for RCC (n = 73) were immunostained with the anti-spermine monoclonal antibody Spm8-2, and the immunoreactivity was evaluated as a prognostic tool. RCC cells displayed various reactivity to the antibody Spm8-2 that translated into a heterogeneous cytoplasmic staining. The prognostic value of the labeling index (LI) on clinical outcome was correlated with the usual clinicopathologic parameters, and the cell proliferation rate was evaluated using Ki-67 labeling. Multiple correspondence analysis and ascending hierarchical classification were performed to determine significant prognostic factors. Univariate statistical survival analysis demonstrated that tumor size (P < .001), nuclear grade (P < .01), necrosis (P < .007), tumor stage (P < .004), metastasis (P < .001), Ki-67 LI (P < .0003), and Spm8-2 immunoreactivity (P < .0001) were predictors of tumor-related death. A positive correlation was found between Ki-67 LI and Spm8-2 immunoreactivity (r' = .53). Multivariate analysis revealed that only Ki-67 LI and Spm8-2 immunoreactivity were significant independent factors in patients with metastases (P < .04 and <.001, respectively) and in patients without metastases (P < .006 and <.001, respectively). Moreover, 100% of the patients with Spm8-2 immunoreactivity <10% were alive at the end of the follow-up. In terms of predictive values, Spm8-2 immunoreactivity had the highest predictive values (sensitivity, 89; specificity, 75; risk ratio, 11) of all clinicopathologic parameters. This study demonstrates that the anti-spermine monoclonal antibody Spm8-2 may be used at the time of radical nephrectomy as a reliable prognostic marker for defining RCC patients at high risk for progression.

Sunitinib combined with angiotensin-2 type-1 receptor antagonists induces more necrosis: a murine xenograft model of renal cell carcinoma.

BACKGROUND: Angiotensin-2 type-1 receptor antagonists not are only antihypertensive drugs but also can inhibit VEGF production. We hypothesised that adding telmisartan to sunitinib could potentiate the antiangiogenic effects. MATERIAL AND METHODS: 786-O cell lines were injected in nude mice. After tumor development, mice were divided into 4 groups: the first was the control group (DMSO), the second group was treated with sunitinib alone, the third group was treated with telmisartan alone, and the fourth group was treated with the combination. Drugs were orally administered every day for four weeks. Animals were sacrificed after treatment. Blood and tumor tissues were collected for analysis by immunohistochemistry, Western Blot, and ELISA methods. RESULTS: All animals developed a ccRCC and ten in each group were treated. Using a kinetic model, tumors tended to grow slower in the combination group compared to others (P = 0.06). Compared to sunitinib alone, the addition of telmisartan significantly increased tissue necrosis (P = 0.038). Central microvascular density decreased (P = 0.0038) as well as circulating VEGF (P = 0.003). There was no significant variation in proliferation or apoptosis markers. CONCLUSION: The combination of sunitinib and telmisartan revealed an enhancement of the blockage of the VEGF pathway on renal tumor resulting in a decrease in neoangiogenesis and an increase in necrosis.