The Role of Magmatism at Rifted Margins

Rifted margins form by the thinning and stretching of continental lithosphere until it ruptures, forming new oceanic crust and lithosphere, which can be accompanied by decompression melting and the addition of magmatic material. Despite numerous studies on magma-rich margins, we still do not fully understand how and when magmatic features form at rifted margins. To address this I investigate the formation of various magmatic features on three rifted margins, the East Indian margin, the Pelotas margin and the Southeast (SE) Greenland margin, using a range of quantitative techniques. The East Indian margin is an often-cited example of a magma-poor margin; however, some interpretations suggest the transition from exhumed mantle to oceanic crust consists of 9 km thick magmatic crust. Gravity inversion, RDA analysis, subsidence analysis and joint inversion of seismic and gravity data alongside seismic observations, reveal the presence of magma-poor and magma-rich characteristics in the form of exhumed mantle and 9 km thick magmatic crust juxtaposed against each other, resulting from a two-stage breakup. Juxtaposition of end-member characteristics suggests that the use of end-member terminology based on volumes of magma alone is misleading. The Pelotas margin in the South Atlantic shows an extraordinarily thick sequence of seaward dipping reflectors (SDRs), of which the composition and formation is poorly understood. I investigate these SDRs using gravity inversion with a sensitivity to basalt/sediment composition, flexural backstripping and reverse thermal subsidence modelling, joint inversion of seismic and gravity data and seismic observations. I show there are two types of SDRs present on the Pelotas margin, an inner subaerial set of SDRs formed of basalt during pre-breakup intra-continental rifting and an outer set of SDRs formed of a mix of volcaniclastics and basalts during breakup in a subaqueous environment at an embryonic mid-ocean ridge. The SE Greenland margin in the North Atlantic has a broad region of ~15 km thick crust and exhibits strong crustal asymmetry with its conjugate Hatton Bank similar to magma-poor margins. I investigate whether the SE Greenland margin consists of magmatic crust or hyper-extended continental crust sandwiched by magmatic material. Gravity inversion, joint inversion of seismic and gravity data as well as seismic velocity analysis suggest the 15 km thick crust on the SE Greenland margin is magmatic rather than a sandwich of thinned continental crust and magmatic additions. This interpretation requires a sharp continent-ocean boundary, similar to Hatton Bank. Together, these case studies investigate the relationship between magmatism and breakup at rifted margins. The East Indian margin suggests that the use of end-member terminology in the classification of rifted margins is misleading when based only on the magmatic budget. The Pelotas margin shows how extrusive magmatism can record different stages in margin formation. Finally, the SE Greenland margin shows the importance of using quantitative techniques to interpret margin structure and subsequent formation processes

Origin, composition and relative timing of seaward dipping reflectors on the Pelotas rifted margin

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Reappraisal of the magma-rich versus magma-poor rifted margin archetypes

Abstract Rifted margins are commonly defined as magma-poor or magma-rich archetypes based on their morphology. We re-examine the prevailing model inferred from this classification that magma-rich margins have excess decompression melting at lithospheric breakup compared with steady-state seafloor spreading, while magma-poor margins have inhibited melting. We investigate the magmatic budget related to lithospheric breakup along two high-resolution long-offset deep reflection seismic profiles across the SE Indian (magma-poor) and Uruguayan (magma-rich) rifted margins. Resolving the magmatic budget is difficult and several interpretations can explain our seismic observations, implying different mechanisms to achieve lithospheric breakup and melt production for each archetype. We show that the Uruguayan and other magma-rich margins may indeed involve excess decompression melting compared with steady-state seafloor spreading but could also be explained by a gradual increase with an early onset relative to crustal breakup. A late onset of decompression melting relative to crustal breakup enables mantle exhumation characteristic of magma-poor margin archetypes (e.g. SE India). Despite different volumes of magmatism, the mechanisms suggested at lithospheric breakup are comparable between both archetypes. Considerations on the timing of decompression melting onset relative to crustal thinning may be more important than the magmatic budget to understand the evolution and variability of rifted margins.</jats:p

JAK/STAT3 represents a therapeutic target for colorectal cancer patients with stromal-rich tumors

Colorectal cancer (CRC) is a heterogenous malignancy underpinned by dysregulation of cellular signaling pathways. Previous literature has implicated aberrant JAK/STAT3 signal transduction in the development and progression of solid tumors. In this study we investigate the effectiveness of inhibiting JAK/STAT3 in diverse CRC models, establish in which contexts high pathway expression is prognostic and perform in depth analysis underlying phenotypes. In this study we investigated the use of JAK inhibitors for anti-cancer activity in CRC cell lines, mouse model organoids and patient-derived organoids. Immunohistochemical staining of the TransSCOT clinical trial cohort, and 2 independent large retrospective CRC patient cohorts was performed to assess the prognostic value of JAK/STAT3 expression. We performed mutational profiling, bulk RNASeq and NanoString GeoMx® spatial transcriptomics to unravel the underlying biology of aberrant signaling. Inhibition of signal transduction with JAK1/2 but not JAK2/3 inhibitors reduced cell viability in CRC cell lines, mouse, and patient derived organoids (PDOs). In PDOs, reduced Ki67 expression was observed post-treatment. A highly significant association between high JAK/STAT3 expression within tumor cells and reduced cancer-specific survival in patients with high stromal invasion (TSPhigh) was identified across 3 independent CRC patient cohorts, including the TrasnSCOT clinical trial cohort. Patients with high phosphorylated STAT3 (pSTAT3) within the TSPhigh group had higher influx of CD66b + cells and higher tumoral expression of PDL1. Bulk RNAseq of full section tumors showed enrichment of NFκB signaling and hypoxia in these cases. Spatial deconvolution through GeoMx® demonstrated higher expression of checkpoint and hypoxia-associated genes in the tumor (pan-cytokeratin positive) regions, and reduced lymphocyte receptor signaling in the TME (pan-cytokeratin- and αSMA-) and αSMA (pan-cytokeratin- and αSMA +) areas. Non-classical fibroblast signatures were detected across αSMA + regions in cases with high pSTAT3. Therefore, in this study we have shown that inhibition of JAK/STAT3 represents a promising therapeutic strategy for patients with stromal-rich CRC tumors. High expression of JAK/STAT3 proteins within both tumor and stromal cells predicts poor outcomes in CRC, and aberrant signaling is associated with distinct spatially-dependant differential gene expression

Prior knowledge transfer across transcriptional data sets and technologies using compositional statistics yields new mislabelled ovarian cell line

Here, we describe gene expression compositional assignment (GECA), a powerful, yet simple method based on compositional statistics that can validate the transfer of prior knowledge, such as gene lists, into independent data sets, platforms and technologies. Transcriptional profiling has been used to derive gene lists that stratify patients into prognostic molecular subgroups and assess biomarker performance in the pre-clinical setting. Archived public data sets are an invaluable resource for subsequent in silico validation, though their use can lead to data integration issues. We show that GECA can be used without the need for normalising expression levels between data sets and can outperform rank-based correlation methods. To validate GECA, we demonstrate its success in the cross-platform transfer of gene lists in different domains including: bladder cancer staging, tumour site of origin and mislabelled cell lines. We also show its effectiveness in transferring an epithelial ovarian cancer prognostic gene signature across technologies, from a microarray to a next-generation sequencing setting. In a final case study, we predict the tumour site of origin and histopathology of epithelial ovarian cancer cell lines. In particular, we identify and validate the commonly-used cell line OVCAR-5 as non-ovarian, being gastrointestinal in origin. GECA is available as an open-source R package

Three versus six months of adjuvant doublet chemotherapy for patients with colorectal cancer: a multi-country cost-effectiveness and budget impact analysis

Introduction: The Short Course Oncology Treatment (SCOT) trial demonstrated non-inferiority, less toxicity and cost-effectiveness from a UK perspective of 3 versus 6 months of oxaliplatin-based chemotherapy for patients with colorectal cancer. This study assessed the cost-effectiveness of shorter treatment, and the budget impact of implementing trial findings from the perspective of all countries that recruited to SCOT: Australia, Denmark, New Zealand, Spain, Sweden and the UK. Methods: Individual cost-utility analyses (CUAs) were performed from the perspective of each country. Resource, quality of life and survival estimates from the SCOT trial (n=6,065) were used. Probabilistic sensitivity analysis and sub-group analyses were undertaken. Using undiscounted costs from these CUAs, the impact on the country specific healthcare budgets of implementing the SCOT trial findings was calculated over a 5-year period. United States dollars were the currency used, with 2019 as base year. One-way and scenario sensitivity analysis addressed uncertainty within the budget impact analysis. Results: Three months of treatment was cost-saving and cost-effective compared to 6 months from the perspective of all countries. The incremental net monetary benefit per patient ranged from $8,972 (Spain) to$13,884 (Denmark). The healthcare budget impact over 5 years for the base case scenario ranged from $3.6 million (New Zealand) to$61.4 million (UK) and totalled over $150 million across all countries. Discussion: This study has widened the transferability of results from the SCOT trial, showing shorter treatment is cost-effective from a multi-country perspective. The vast savings from implementation could fully justify the investment in conducting the SCOT trial

The Glasgow Microenvironment Score associates with prognosis and adjuvant chemotherapy response in colorectal cancer

Background The Glasgow Microenvironment Score (GMS) combines peritumoural inflammation and tumour stroma percentage to assess interactions between tumour and microenvironment. This was previously demonstrated to associate with colorectal cancer (CRC) prognosis, and now requires validation and assessment of interactions with adjuvant therapy. Methods Two cohorts were utilised; 862 TNM I–III CRC validation cohort, and 2912 TNM II–III CRC adjuvant chemotherapy cohort (TransSCOT). Primary endpoints were disease-free survival (DFS) and relapse-free survival (RFS). Exploratory endpoint was adjuvant chemotherapy interaction. Results GMS independently associated with DFS (p = 0.001) and RFS (p < 0.001). GMS significantly stratified RFS for both low risk (GMS 0 v GMS 2: HR 3.24 95% CI 1.85–5.68, p < 0.001) and high-risk disease (GMS 0 v GMS 2: HR 2.18 95% CI 1.39–3.41, p = 0.001). In TransSCOT, chemotherapy type (pinteraction = 0.013), but not duration (p = 0.64) was dependent on GMS. Furthermore, GMS 0 significantly associated with improved DFS in patients receiving FOLFOX compared with CAPOX (HR 2.23 95% CI 1.19–4.16, p = 0.012). Conclusions This study validates the GMS as a prognostic tool for patients with stage I–III colorectal cancer, independent of TNM, with the ability to stratify both low- and high-risk disease. Furthermore, GMS 0 could be employed to identify a subset of patients that benefit from FOLFOX over CAPOX

Sexually Dimorphic Serotonergic Dysfunction in a Mouse Model of Huntington's Disease and Depression

Depression is the most common psychiatric disorder in Huntington's disease (HD) patients. In the general population, women are more prone to develop depression and such susceptibility might be related to serotonergic dysregulation. There is yet to be a study of sexual dimorphism in the development and presentation of depression in HD patients. We investigated whether 8-week-old male and female R6/1 transgenic HD mice display depressive-like endophenotypes associated with serotonergic impairments. We also studied the behavioral effects of acute treatment with sertraline. We found that only female HD mice exhibited a decreased preference for saccharin as well as impaired emotionality-related behaviors when assessed on the novelty-suppressed feeding test (NSFT) and the forced-swimming test (FST). The exaggerated immobility time displayed by female HD in the FST was reduced by acute administration of sertraline. We also report an increased response to the 5-HT1A receptor agonist 8-OH-DPAT in inducing hypothermia and a decreased 5-HT2A receptor function in HD animals. While tissue levels of serotonin were reduced in both male and female HD mice, we found that serotonin concentration and hydroxylase-2 (TPH2) mRNA levels were higher in the hippocampus of males compared to female animals. Finally, the antidepressant-like effects of sertraline in the FST were blunted in male HD animals. This study reveals sex-specific depressive-related behaviors during an early stage of HD prior to any cognitive and motor deficits. Our data suggest a crucial role for disrupted serotonin signaling in mediating the sexually dimorphic depression-like phenotype in HD mice

Prognostic and predictive value of Immunoscore in stage III colorectal cancer: pooled analysis of 2,608 cases from the SCOT and IDEA-HORG studies

Purpose Immunoscore (IS) is prognostic in stage III colorectal cancer (CRC) and may predict benefit of duration (6 v 3 months) of adjuvant infusional fluorouracil, leucovorin, and oxaliplatin (FOLFOX) chemotherapy. We sought to determine IS prognostic and predictive value in stage-III CRC treated with adjuvant FOLFOX or oral capecitabine and infusional oxaliplatin (CAPOX) in the SCOT and IDEA-HORG trials. Methods Three thousand sixty-one cases had tumor samples, of which 2,643 (1,792 CAPOX) were eligible for IS testing. Predefined cutoffs (IS-Low and IS-High) were used to classify cases into two groups for analysis of disease-free survival (3-year DFS) and multivariable-adjusted hazard ratios (mvHRs) by Cox regression. Results IS was determined in 2,608 (99.5%) eligible cases, with 877 (33.7%) samples classified as IS-Low. IS-Low tumors were more commonly high-risk (T4 and/or N2; 52.9% IS-Low v 42.2% IS-High; P &lt; .001) and in younger patients (P = .024). Patients with IS-Low tumors had significantly shorter DFS in the CAPOX, FOLFOX, and combined cohorts (mvHR, 1.52 [95% CI, 1.28 to 1.82]; mvHR, 1.58 [95% CI, 1.22 to 2.04]; and mvHR, 1.55 [95% CI, 1.34 to 1.79], respectively; P &lt; .001 all comparisons), regardless of sex, BMI, clinical risk group, tumor location, treatment duration, or chemotherapy regimen. IS prognostic value was greater in younger (≤65 years) than older (&gt;65 years) patients in the CAPOX cohort (mvHR, 1.92 [95% CI, 1.50 to 2.46] v 1.28 [95% CI, 1.01 to 1.63], PINTERACTION = .026), and in DNA mismatch repair proficient than deficient mismatch repair disease (mvHR, 1.68 [95% CI, 1.41 to 2.00] v 0.67 [95% CI, 0.30 to 1.49], PINTERACTION = .03), although these exploratory analyses were uncorrected for multiple testing. Adding IS to a model containing all clinical variables significantly improved prediction of DFS (likelihood ratio test, P &lt; .001) regardless of MMR status. Conclusion IS is prognostic in stage III CRC treated with FOLFOX or CAPOX, including within clinically relevant tumor subgroups. Possible variation in IS prognostic value by age and MMR status, and prediction of benefit from extended adjuvant therapy merit validation