Mutual repression between JNK/AP-1 and JAK/STAT stratifies senescent and proliferative cell behaviors during tissue regeneration.

Epithelial repair relies on the activation of stress signaling pathways to coordinate tissue repair. Their deregulation is implicated in chronic wound and cancer pathologies. Using TNF-α/Eiger-mediated inflammatory damage to Drosophila imaginal discs, we investigate how spatial patterns of signaling pathways and repair behaviors arise. We find that Eiger expression, which drives JNK/AP-1 signaling, transiently arrests proliferation of cells in the wound center and is associated with activation of a senescence program. This includes production of the mitogenic ligands of the Upd family, which allows JNK/AP-1-signaling cells to act as paracrine organizers of regeneration. Surprisingly, JNK/AP-1 cell-autonomously suppress activation of Upd signaling via Ptp61F and Socs36E, both negative regulators of JAK/STAT signaling. As mitogenic JAK/STAT signaling is suppressed in JNK/AP-1-signaling cells at the center of tissue damage, compensatory proliferation occurs by paracrine activation of JAK/STAT in the wound periphery. Mathematical modelling suggests that cell-autonomous mutual repression between JNK/AP-1 and JAK/STAT is at the core of a regulatory network essential to spatially separate JNK/AP-1 and JAK/STAT signaling into bistable spatial domains associated with distinct cellular tasks. Such spatial stratification is essential for proper tissue repair, as coactivation of JNK/AP-1 and JAK/STAT in the same cells creates conflicting signals for cell cycle progression, leading to excess apoptosis of senescently stalled JNK/AP-1-signaling cells that organize the spatial field. Finally, we demonstrate that bistable separation of JNK/AP-1 and JAK/STAT drives bistable separation of senescent signaling and proliferative behaviors not only upon tissue damage, but also in RasV12, scrib tumors. Revealing this previously uncharacterized regulatory network between JNK/AP-1, JAK/STAT, and associated cell behaviors has important implications for our conceptual understanding of tissue repair, chronic wound pathologies, and tumor microenvironments.

Distinct signaling signatures drive compensatory proliferation via S-phase acceleration.

Regeneration relies on cell proliferation to restore damaged tissues. Multiple signaling pathways activated by local or paracrine cues have been identified to promote regenerative proliferation. How different types of tissue damage may activate distinct signaling pathways and how these differences converge on regenerative proliferation is less well defined. To better understand how tissue damage and proliferative signals are integrated during regeneration, we investigate models of compensatory proliferation in Drosophila imaginal discs. We find that compensatory proliferation is associated with a unique cell cycle profile, which is characterized by short G1 and G2 phases and, surprisingly, by acceleration of the S-phase. S-phase acceleration can be induced by two distinct signaling signatures, aligning with inflammatory and non-inflammatory tissue damage. Specifically, non-autonomous activation of JAK/STAT and Myc in response to inflammatory damage, or local activation of Ras/ERK and Hippo/Yki in response to elevated cell death, promote accelerated nucleotide incorporation during S-phase. This previously unappreciated convergence of different damaging insults on the same regenerative cell cycle program reconciles previous conflicting observations on proliferative signaling in different tissue regeneration and tumor models.

Medulloblastoma: Distinctive Histo-Molecular Correlation with Clinical Profile, Radiologic Characteristics, and Surgical Outcome.

OBJECTIVE: Medulloblastoma (MB) is a heterogenous tumor, and the prognosis is influenced by various clinical, histological, and molecular factors. The aim of the study is to determine the clinical profile and radiologic characteristics among the histo-molecular subgroups, the predictors of surgical outcome, and the pattern of relapse in pediatric and adult MB. METHOD: An analysis of 118 patients of MB who underwent surgical treatment at National Institute of Mental Health and Neurosciences, India, over a 7-year period (2005-2011) is presented. The clinical profile, radiologic characteristics, surgical nuances, and survival patterns are discussed. The relevant statistical analysis was done using SPSS software, version 22.0. RESULTS: The mean age of the cohort was 12 years (12.3 ± 8.7). The primary manifestation was raised intracranial tension headache in 53 patients (44.9%), which was the predominant symptom in large cell/anaplastic (LCA)- and WNT-activated subgroups. The median preoperative Karnofsky performance score was 60 (60.6 ± 12.9). Vermian and hemispheric location of tumor was most commonly observed in non-WNT/non-SHH (groups 3 and 4; 91.7%) and SHH-activated (42.9%) subgroups, respectively. Ninety-two patients (78%) underwent preoperative ventriculoperitoneal shunts (VPS) for obstructive hydrocephalus (HCP) and 14 patients (11.8%) underwent VPS in the postoperative period. The median overall survival (OS) for the whole group was 82.1 ± 5.7 months and the median recurrence-free survival was 51.0 ± 4.8 months. While radiotherapy had a significant influence on OS, progression-free survival was influenced by radiotherapy as well as chemotherapy in both pediatric and adult cohort. Desmoplastic/nodular subtype and WNT-activated subgroup had the best prognosis; LCA and non-WNT/non-SHH had the worst prognosis. CONCLUSIONS: Majority of the patients were pediatric in the study. Age, hemispheric location of tumor, extent of resection, and adjuvant treatment status were the important clinical prognostic factors for survival. Surgery for MB is formidable, and VPS can be considered in persistent symptomatic and progressive HCP. Our study on pediatric and adult MB validates the prognostic significance of various clinical, radiologic, and histo-molecular parameters of MB.

Spectrum of primary intracranial tumors at a tertiary care neurological institute: A hospital-based brain tumor registry.

BACKGROUND: Hospital-based cancer registries (HBCRs) provide information on the magnitude and distribution of cancers in a given hospital. Hospital-based brain tumor registry (HBBTR) data on primary intracranial tumors from a tertiary care neurological center is presented. This is compared with related national and international data. MATERIALS AND METHODS: Data of patients operated for brain tumors at the National Institute of Mental Health and Neurosciences, Bangalore, India, between January 2010 and December 2014 was collected. Patients' clinical details and histopathological diagnosis were recorded. Data was analyzed and compared with that of Tata Memorial Hospital (TMH), Mumbai, and the Central Brain Tumor Registry of the United States (CBTRUS). RESULTS: A total of 4295 primary intracranial tumors in 1847 (43%) females and 2448 (57%) male patients were recorded. Pediatric and adult patients accounted for 16.2% and 83.8% of the cases, respectively. The maximum proportion of tumors was noted in the fourth decade. Among children, astrocytomas (25.1%), embryonal (20.6%), and ependymal tumors (14.8%) were the most frequently reported histology. In adults, meningiomas (23.2%), glioblastomas (15.5%), and nerve sheath tumors (12.7%) were common. Glioblastomas and all other tumors showed a male predilection whereas meningiomas presented more commonly in females. While our HBBTR followed similar trends as TMH data, marked difference was seen in the median age of some tumor subtypes when compared to CBTRUS. CONCLUSION: This HBBTR data gives a glimpse of the prevalence of varied primary intracranial tumors. Such data can be linked to other HBCRs and population-based cancer registries in India for improved research and policy-making decisions.

Proteomic profiling of medulloblastoma reveals novel proteins differentially expressed within each molecular subgroup.

OBJECTIVES: The objective of the study was to identify novel medulloblastoma (MB) biomarkers through proteomic profiling, correlate it with the molecular subgroups of MB and assess the clinical significance. METHODS: Archived paraffin embedded tumor tissue blocks from 118 MB patients, operated at our institute were retrieved. Clinical information was documented from the hospital database. Tumours were stratified into molecular subgroups using the IHC markers- ß Catenin, GAB-1, YAP-1 and p53. Six fresh MB tumour tissues and two control cerebellar tissues were subjected to proteomic profiling to study differential protein expression in molecular subgroups using high resolution mass spectrometry. Prominent signalling pathways activated in each subgroup were identified using the Panther pathway software. RESULTS: Non WNT/SHH group was the most common (61.1 %), followed by SHH and WNT. p53 immunopositivity did not correlate with prognosis in any subgroup. Proteomic profiling revealed several novel proteins differentially expressed between MB molecular subgroups. Signalling pathways exclusively enriched in each molecular subgroup were also identified. The top upregulated proteins were PMEL and FBN2 in the WNT subgroup, SYNGR2 in the SHH subgroup and GFAP, IMPG2 and MAGEA10 in the Non WNT/Non SHH group. We validated GFAP by immunohistochemistry on the archived samples (n = 118) and noted two types of staining pattern in MBs - reactive (stellate) astrocytes and tumour cell staining. GFAP immunopositivity in tumor cells of SHH subgroup correlated with a better prognosis. CONCLUSIONS: Proteomic profile identified several novel proteins differentially regulated within the molecular subgroups that could serve as potential diagnostic /prognostic biomarkers. Notably, GFAP, which was derived from proteomics data, when validated by IHC, revealed a variable staining pattern in MB tumours. The prognostic significance of GFAP in SHH tumor patients further points at the heterogeneity of this subgroup. The study also throws light on the signaling pathways activated in MB and in turn its plausible role in the tumorigenesis.

JNK-dependent cell cycle stalling in G2 promotes survival and senescence-like phenotypes in tissue stress.

The restoration of homeostasis after tissue damage relies on proper spatial-temporal control of damage-induced apoptosis and compensatory proliferation. In Drosophila imaginal discs these processes are coordinated by the stress response pathway JNK. We demonstrate that JNK signaling induces a dose-dependent extension of G2 in tissue damage and tumors, resulting in either transient stalling or a prolonged but reversible cell cycle arrest. G2-stalling is mediated by downregulation of the G2/M-specific phosphatase String(Stg)/Cdc25. Ectopic expression of stg is sufficient to suppress G2-stalling and reveals roles for stalling in survival, proliferation and paracrine signaling. G2-stalling protects cells from JNK-induced apoptosis, but under chronic conditions, reduces proliferative potential of JNK-signaling cells while promoting non-autonomous proliferation. Thus, transient cell cycle stalling in G2 has key roles in wound healing but becomes detrimental upon chronic JNK overstimulation, with important implications for chronic wound healing pathologies or tumorigenic transformation.

Analysis of the Fgfr2C342Y mouse model shows condensation defects due to misregulation of Sox9 expression in prechondrocytic mesenchyme.

Syndromic craniosynostosis caused by mutations in FGFR2 is characterised by developmental pathology in both endochondral and membranous skeletogenesis. Detailed phenotypic characterisation of features in the membranous calvarium, the endochondral cranial base and other structures in the axial and appendicular skeleton has not been performed at embryonic stages. We investigated bone development in the Crouzon mouse model (Fgfr2C342Y) at pre- and post-ossification stages to improve understanding of the underlying pathogenesis. Phenotypic analysis was performed by whole-mount skeletal staining (Alcian Blue/Alizarin Red) and histological staining of sections of CD1 wild-type (WT), Fgfr2C342Y/+ heterozygous (HET) and Fgfr2C342Y/C342Y homozygous (HOM) mouse embryos from embryonic day (E)12.5-E17.5 stages. Gene expression (Sox9, Shh, Fgf10 and Runx2) was studied by in situ hybridisation and protein expression (COL2A1) by immunohistochemistry. Our analysis has identified severely decreased osteogenesis in parts of the craniofacial skeleton together with increased chondrogenesis in parts of the endochondral and cartilaginous skeleton in HOM embryos. The Sox9 expression domain in tracheal and basi-cranial chondrocytic precursors at E13.5 in HOM embryos is increased and expanded, correlating with the phenotypic observations which suggest FGFR2 signalling regulates Sox9 expression. Combined with abnormal staining of type II collagen in pre-chondrocytic mesenchyme, this is indicative of a mesenchymal condensation defect. An expanded spectrum of phenotypic features observed in the Fgfr2C342Y/C342Y mouse embryo paves the way towards better understanding the clinical attributes of human Crouzon-Pfeiffer syndrome. FGFR2 mutation results in impaired skeletogenesis; however, our findings suggest that many phenotypic aberrations stem from a primary failure of pre-chondrogenic/osteogenic mesenchymal condensation and link FGFR2 to SOX9, a principal regulator of skeletogenesis.

Insulin-like growth factor binding protein-2 regulates ß-catenin signaling pathway in glioma cells and contributes to poor patient prognosis.

BACKGROUND: Upregulation of insulin-like growth factor binding protein 2 (IGFBP-2) is often associated with aggressiveness of glioblastoma (GBM) and contributes to poor prognosis for GBM patients. In view of the regulation of ß-catenin by IGFBP-2 in breast cancer and the crucial role of ß-catenin pathway in glioma invasion, proliferation and maintenance of glioma stem cells, the mechanism of regulation of ß-catenin by IGFBP-2, and its role in GBM prognosis was studied. METHODS: Regulation of the ß-catenin pathway was studied by immunocytochemistry, Western blot analysis, luciferase assays, and real-time RT-PCR. The role of IGFBP-2 was studied by subcutaneous tumor xenografts in immunocompromised mice using glioma cells engineered to express IGFBP-2 and its domains. GBM patient tumor tissues (n = 112) were analyzed for expression of IGFBP-2 and ß-catenin by immunohistochemistry. Survival analysis was performed employing Cox regression and Kaplan-Meier survival analyses. RESULTS: IGFBP-2 knockdown in U251, T98G, and U373 or overexpression in LN229 and U87 cells revealed a role for IGFBP-2 in stabilization of ß-catenin and regulation of its nuclear functions involving integrin-mediated inactivation of GSK3ß. Similar results were obtained upon overexpression of the C-terminal domain of IGFBP-2 but not the N-terminal domain. Subcutaneous xenograft tumors overexpressing either full-length or the C-terminal domain of IGFBP-2 showed larger volume as compared with controls. Coexpression of high levels of IGFBP-2 and ß-catenin was associated with worse prognosis (P = .001) in GBM patients. CONCLUSION: IGFBP-2 potentiates GBM tumor growth by the activation of the ß-catenin pathway through its C-terminal domain, and their coexpression possibly contributes to worse patient prognosis.