5 research outputs found
The role of mTOR-mediated signaling in the regulation of cellular migration
Mechanistic target for rapamycin (mTOR) is a serine/threonine protein kinase that forms two distinct complexes mTORC1 and mTORC2, integrating mitogen and nutrient signals to regulate cell survival and proliferation; processes which are commonly deregulated in human cancers. mTORC1 and mTORC2 have divergent molecular associations and cellular functions: mTORC1 regulates in mRNA translation and protein synthesis, while mTORC2 is involved in the regulation of cellular survival and metabolism. Through AKT phosphorylation/activation, mTORC2 has also been reported to regulate cell migration. Recent attention has focused on the aberrant activation of the PI3K/mTOR pathway in B cell malignancies and there is growing evidence for its involvement in disease pathogenesis, due to its location downstream of other established novel drug targets that intercept B cell receptor (BCR) signals. Shared pharmacological features of BCR signal inhibitors include a striking ālymphocyte redistributionā effect whereby patients experience a sharp increase in lymphocyte count on initiation of therapy followed by a steady decline. Chronic lymphocytic leukemia (CLL) serves as a paradigm for migration studies as lymphocytes are among the most widely travelled cells in the body, a product of their role in immunological surveillance. The subversion of normal lymphocyte movement in CLL is being elucidated; this review aims to describe the migration impairment which occurs as part of the wider context of cancer cell migration defects, with a focus on the role of mTOR in mediating migration effects downstream of BCR ligation and other microenvironmental signals
AKT/mTORC2 inhibition activates FOXO1 function in CLL cells reducing B cell receptor-mediated survival
Purpose: To determine whether inhibition of mechanistic target of rapamycin (mTOR) kinase-mediated signaling represents a valid therapeutic approach for chronic lymphocytic leukemia (CLL). Experimental Design: Stratification of mTOR activity was carried out in primary CLL patient samples and an aggressive CLL-like mouse model. The potency of dual mTOR inhibitor AZD8055 to induce apoptosis in primary CLL cells was assessed in the presence/absence of B cell receptor (BCR) ligation. Furthermore, we addressed the molecular and functional impact of dual mTOR inhibition in combination with BTK inhibitor ibrutinib. Results: Differential regulation of basal mTORC1 activity was observed in poor prognostic CLL samples, with elevated p4EBP1T37/46 and decreased p70S6 kinase activity, suggesting that dual mTORC1/2 inhibitors may exhibit improved response in poor prognostic CLL compared with rapalogs. AZD8055 treatment of primary CLL cells significantly reduced CLL survival in vitro compared with rapamycin, preferentially targeting poor prognostic subsets and overcoming BCR-mediated survival advantages. Furthermore, AZD8055, and clinical analog AZD2014, significantly reduced CLL tumor load in mice. AKT substrate FOXO1, while overexpressed in CLL cells of poor prognostic patients in LN biopsies, peripheral CLL cells, and mouse-derived CLL-like cells, appeared to be inactive. AZD8055 treatment partially reversed FOXO1 inactivation downstream of BCR crosslinking, significantly inhibiting FOXO1T24 phosphorylation in an mTORC2-AKT-dependent manner, to promote FOXO1 nuclear localization, activity and FOXO1-mediated gene regulation. FOXO1 activity was further significantly enhanced on combining AZD8055 with ibrutinib. Conclusions: Our studies demonstrate that dual mTOR inhibitors show promise as future CLL therapies, particularly in combination with ibrutinib
PKCĪ² Facilitates Leukemogenesis in Chronic Lymphocytic Leukaemia by Promoting Constitutive BCR-Mediated Signalling
B cell antigen receptor (BCR) signalling competence is critical for the pathogenesis of chronic lymphocytic leukaemia (CLL). Defining key proteins that facilitate these networks aid in the identification of targets for therapeutic exploitation. We previously demonstrated that reduced PKCĪ± function in mouse hematopoietic stem/progenitor cells (HPSCs) resulted in PKCĪ²II upregulation and generation of a poor-prognostic CLL-like disease. Here, prkcb knockdown in HSPCs leads to reduced survival of PKCĪ±-KR-expressing CLL-like cells, concurrent with reduced expression of the leukemic markers CD5 and CD23. SP1 promotes elevated expression of prkcb in PKCĪ±-KR expressing cells enabling leukemogenesis. Global gene analysis revealed an upregulation of genes associated with B cell activation in PKCĪ±-KR expressing cells, coincident with upregulation of PKCĪ²II: supported by activation of key signalling hubs proximal to the BCR and elevated proliferation. Ibrutinib (BTK inhibitor) or enzastaurin (PKCĪ²II inhibitor) treatment of PKCĪ±-KR expressing cells and primary CLL cells showed similar patterns of Akt/mTOR pathway inhibition, supporting the role for PKCĪ²II in maintaining proliferative signals in our CLL mouse model. Ibrutinib or enzastaurin treatment also reduced PKCĪ±-KR-CLL cell migration towards CXCL12. Overall, we demonstrate that PKCĪ² expression facilitates leukemogenesis and identify that BCR-mediated signalling is a key driver of CLL development in the PKCĪ±-KR model.</jats:p
Multiorgan MRI findings after hospitalisation with COVID-19 in the UK (C-MORE): a prospective, multicentre, observational cohort study
Introduction:
The multiorgan impact of moderate to severe coronavirus infections in the post-acute phase is still poorly understood. We aimed to evaluate the excess burden of multiorgan abnormalities after hospitalisation with COVID-19, evaluate their determinants, and explore associations with patient-related outcome measures.
Methods:
In a prospective, UK-wide, multicentre MRI follow-up study (C-MORE), adults (aged ā„18 years) discharged from hospital following COVID-19 who were included in Tier 2 of the Post-hospitalisation COVID-19 study (PHOSP-COVID) and contemporary controls with no evidence of previous COVID-19 (SARS-CoV-2 nucleocapsid antibody negative) underwent multiorgan MRI (lungs, heart, brain, liver, and kidneys) with quantitative and qualitative assessment of images and clinical adjudication when relevant. Individuals with end-stage renal failure or contraindications to MRI were excluded. Participants also underwent detailed recording of symptoms, and physiological and biochemical tests. The primary outcome was the excess burden of multiorgan abnormalities (two or more organs) relative to controls, with further adjustments for potential confounders. The C-MORE study is ongoing and is registered with ClinicalTrials.gov, NCT04510025.
Findings:
Of 2710 participants in Tier 2 of PHOSP-COVID, 531 were recruited across 13 UK-wide C-MORE sites. After exclusions, 259 C-MORE patients (mean age 57 years [SD 12]; 158 [61%] male and 101 [39%] female) who were discharged from hospital with PCR-confirmed or clinically diagnosed COVID-19 between March 1, 2020, and Nov 1, 2021, and 52 non-COVID-19 controls from the community (mean age 49 years [SD 14]; 30 [58%] male and 22 [42%] female) were included in the analysis. Patients were assessed at a median of 5Ā·0 months (IQR 4Ā·2ā6Ā·3) after hospital discharge. Compared with non-COVID-19 controls, patients were older, living with more obesity, and had more comorbidities. Multiorgan abnormalities on MRI were more frequent in patients than in controls (157 [61%] of 259 vs 14 [27%] of 52; p<0Ā·0001) and independently associated with COVID-19 status (odds ratio [OR] 2Ā·9 [95% CI 1Ā·5ā5Ā·8]; padjusted=0Ā·0023) after adjusting for relevant confounders. Compared with controls, patients were more likely to have MRI evidence of lung abnormalities (p=0Ā·0001; parenchymal abnormalities), brain abnormalities (p<0Ā·0001; more white matter hyperintensities and regional brain volume reduction), and kidney abnormalities (p=0Ā·014; lower medullary T1 and loss of corticomedullary differentiation), whereas cardiac and liver MRI abnormalities were similar between patients and controls. Patients with multiorgan abnormalities were older (difference in mean age 7 years [95% CI 4ā10]; mean age of 59Ā·8 years [SD 11Ā·7] with multiorgan abnormalities vs mean age of 52Ā·8 years [11Ā·9] without multiorgan abnormalities; p<0Ā·0001), more likely to have three or more comorbidities (OR 2Ā·47 [1Ā·32ā4Ā·82]; padjusted=0Ā·0059), and more likely to have a more severe acute infection (acute CRP >5mg/L, OR 3Ā·55 [1Ā·23ā11Ā·88]; padjusted=0Ā·025) than those without multiorgan abnormalities. Presence of lung MRI abnormalities was associated with a two-fold higher risk of chest tightness, and multiorgan MRI abnormalities were associated with severe and very severe persistent physical and mental health impairment (PHOSP-COVID symptom clusters) after hospitalisation.
Interpretation:
After hospitalisation for COVID-19, people are at risk of multiorgan abnormalities in the medium term. Our findings emphasise the need for proactive multidisciplinary care pathways, with the potential for imaging to guide surveillance frequency and therapeutic stratification