Integrated single-cell genetic and transcriptional analysis suggests novel drivers of chronic lymphocytic leukemia.

Intra-tumoral genetic heterogeneity has been characterized across cancers by genome sequencing of bulk tumors, including chronic lymphocytic leukemia (CLL). In order to more accurately identify subclones, define phylogenetic relationships, and probe genotype-phenotype relationships, we developed methods for targeted mutation detection in DNA and RNA isolated from thousands of single cells from five CLL samples. By clearly resolving phylogenic relationships, we uncovered mutated LCP1 and WNK1 as novel CLL drivers, supported by functional evidence demonstrating their impact on CLL pathways. Integrative analysis of somatic mutations with transcriptional states prompts the idea that convergent evolution generates phenotypically similar cells in distinct genetic branches, thus creating a cohesive expression profile in each CLL sample despite the presence of genetic heterogeneity. Our study highlights the potential for single-cell RNA-based targeted analysis to sensitively determine transcriptional and mutational profiles of individual cancer cells, leading to increased understanding of driving events in malignancy.

The roles and experiences of informal carers providing care to people with advanced cancer in Africa-A systematic review and critical interpretive analysis.

There is an increasing prevalence of cancer in Africa with approximately 80% of cancers diagnosed at an advanced stage. High out-of-pocket healthcare costs and overstretched health systems lead to heavy reliance on informal carers for cancer care. This study aims to explore the roles and experiences of informal carers including the impact of cancer care on individuals and communities and support available for carers. We carried out a systematic review following PRISMA reporting guidelines and used critical interpretative synthesis to identify themes and develop an informal carers' experience framework. We searched nine databases and screened 8,123 articles from which 31 studies were included in the review. Most studies were from Sub-Saharan Africa (29/31, 94%), particularly Uganda (9, 29%). Carers were mostly women, aged 30-40 years, and siblings, spouses, or children. Caring roles included care coordination, fundraising, and emotional support. Caring was time-consuming with some carers reporting 121 hours/week of caring, associated with the inability to pursue paid work and depression. Four themes demonstrated carers' experiences: 1) intrapersonal factors: strong sense of familial obligation, and grappling with gender roles, 2) interpersonal factors: impact of a cancer diagnosis on households, changing social and sexual relationships, 3) community factors: navigating cultural norms on nature and location of care, and 4) health system influences: barriers to accessing healthcare services, and tensions between traditional and biomedical medicine. These themes aligned with Bronfenbrenner's social ecological model which aided our development of a framework for understanding informal carers' experiences'. Our review highlights multifaceted roles and experiences of informal carers in Africa, amidst cultural and community impacts. Carers experience a strong obligation and willingly undertake the role of carer, but at the expense of their social, economic, and psychological wellbeing. Support for carers, including flexible working hours/ carers' allowance, should be incorporated as part of universal health coverage.

A Murine Model of Chronic Lymphocytic Leukemia Based on B Cell-Restricted Expression of Sf3b1 Mutation and Atm Deletion.

SF3B1 is recurrently mutated in chronic lymphocytic leukemia (CLL), but its role in the pathogenesis of CLL remains elusive. Here, we show that conditional expression of Sf3b1-K700E mutation in mouse B cells disrupts pre-mRNA splicing, alters cell development, and induces a state of cellular senescence. Combination with Atm deletion leads to the overcoming of cellular senescence and the development of CLL-like disease in elderly mice. These CLL-like cells show genome instability and dysregulation of multiple CLL-associated cellular processes, including deregulated B cell receptor signaling, which we also identified in human CLL cases. Notably, human CLLs harboring SF3B1 mutations exhibit altered response to BTK inhibition. Our murine model of CLL thus provides insights into human CLL disease mechanisms and treatment.

Physiologic Expression of Sf3b1(K700E) Causes Impaired Erythropoiesis, Aberrant Splicing, and Sensitivity to Therapeutic Spliceosome Modulation.

More than 80% of patients with the refractory anemia with ring sideroblasts subtype of myelodysplastic syndrome (MDS) have mutations in Splicing Factor 3B, Subunit 1 (SF3B1). We generated a conditional knockin mouse model of the most common SF3B1 mutation, Sf3b1(K700E). Sf3b1(K700E) mice develop macrocytic anemia due to a terminal erythroid maturation defect, erythroid dysplasia, and long-term hematopoietic stem cell (LT-HSC) expansion. Sf3b1(K700E) myeloid progenitors and SF3B1-mutant MDS patient samples demonstrate aberrant 3' splice-site selection associated with increased nonsense-mediated decay. Tet2 loss cooperates with Sf3b1(K700E) to cause a more severe erythroid and LT-HSC phenotype. Furthermore, the spliceosome modulator, E7017, selectively kills SF3B1(K700E)-expressing cells. Thus, SF3B1(K700E) expression reflects the phenotype of the mutation in MDS and may be a therapeutic target in MDS.

Transcriptomic Characterization of SF3B1 Mutation Reveals Its Pleiotropic Effects in Chronic Lymphocytic Leukemia.

Mutations in SF3B1, which encodes a spliceosome component, are associated with poor outcome in chronic lymphocytic leukemia (CLL), but how these contribute to CLL progression remains poorly understood. We undertook a transcriptomic characterization of primary human CLL cells to identify transcripts and pathways affected by SF3B1 mutation. Splicing alterations, identified in the analysis of bulk cells, were confirmed in single SF3B1-mutated CLL cells and also found in cell lines ectopically expressing mutant SF3B1. SF3B1 mutation was found to dysregulate multiple cellular functions including DNA damage response, telomere maintenance, and Notch signaling (mediated through KLF8 upregulation, increased TERC and TERT expression, or altered splicing of DVL2 transcript, respectively). SF3B1 mutation leads to diverse changes in CLL-related pathways.