LGR6 marks nephron progenitor cells.

BACKGROUND: Nephron progenitor cells (NPCs) undergo a stepwise process to generate all mature nephron structures. Mesenchymal to epithelial transition (MET) is considered a multistep process of NPC differentiation to ensure progressive establishment of new nephrons. However, despite this important role, to date, no marker for NPCs undergoing MET in the nephron exists. RESULTS: Here, we identify LGR6 as a NPC marker, expressed in very early cap mesenchyme, pre-tubular aggregates, renal vesicles, and in segments of S-shaped bodies, following the trajectory of MET. By using a lineage tracing approach in embryonic explants in combination with confocal imaging and single-cell RNA sequencing, we provide evidence for the multiple fates of LGR6+ cells during embryonic nephrogenesis. Moreover, by using long-term in vivo lineage tracing, we show that postnatal LGR6+ cells are capable of generating the multiple lineages of the nephrons. CONCLUSIONS: Given the profound early mesenchymal expression and MET signature of LGR6+ cells, together with the lineage tracing of mesenchymal LGR6+ cells, we conclude that LGR6+ cells contribute to all nephrogenic segments by undergoing MET. LGR6+ cells can therefore be considered an early committed NPC population during embryonic and postnatal nephrogenesis with potential regenerative capability.

INPP5A phosphatase is a synthetic lethal target in GNAQ and GNA11-mutant melanomas.

Activating mutations in GNAQ/GNA11 occur in over 90% of uveal melanomas (UMs), the most lethal melanoma subtype; however, targeting these oncogenes has proven challenging and inhibiting their downstream effectors show limited clinical efficacy. Here, we performed genome-scale CRISPR screens along with computational analyses of cancer dependency and gene expression datasets to identify the inositol-metabolizing phosphatase INPP5A as a selective dependency in GNAQ/11-mutant UM cells in vitro and in vivo. Mutant cells intrinsically produce high levels of the second messenger inositol 1,4,5 trisphosphate (IP3) that accumulate upon suppression of INPP5A, resulting in hyperactivation of IP3-receptor signaling, increased cytosolic calcium and p53-dependent apoptosis. Finally, we show that GNAQ/11-mutant UM cells and patients' tumors exhibit elevated levels of IP4, a biomarker of enhanced IP3 production; these high levels are abolished by GNAQ/11 inhibition and correlate with sensitivity to INPP5A depletion. Our findings uncover INPP5A as a synthetic lethal vulnerability and a potential therapeutic target for GNAQ/11-mutant-driven cancers.

In-depth Characterization of Vaccine Breakthrough Infections With SARS-CoV-2 Among Health Care Workers in a Dutch Academic Medical Center.

Severe acute respiratory syndrome coronavirus 2 infection after coronavirus disease 2019 vaccination raises concerns about the emergence of vaccine escape variants. Here we characterize 14 breakthrough infections among 5860 fully vaccinated Dutch health care workers ≥14 days after the final dose of vaccination with either BNT162b2, mRNA-1273, or Ad26.COV2.S. These breakthrough infections presented with regular B.1.1.7 (Alpha) and B.1.617.2 (Delta) variants and high viral loads, despite normal vaccine-induced B- and T-cell immune responses detected by live virus neutralization assays and ELISpot. High-risk exposure settings, such as in households, indicate a potential risk of viral transmission despite full vaccination.

Chemotherapy as primary treatment for brain metastases from breast cancer: analysis of 115 one-year survivors.

PURPOSE: Given the potential toxicity of whole brain radiotherapy, we introduced systemic therapy as possible primary treatment for brain metastases (BM) from breast cancer. This study aims to evaluate the feasibility of this therapeutic approach. METHODS: Review of 115 breast cancer patients treated for BM with at least 1 year of follow-up. RESULTS: Patients with single BM without extracranial disease were usually treated with surgery, patients with multiple BM and controlled extracranial disease usually with RT, and those with progressive extracranial disease usually with systemic therapy as primary treatment for BM. Primary treatment for BM was surgery in 30 patients, RT in 26 patients, RT combined with systemic therapy in 33 patients, and systemic therapy as single treatment in 27 patients (chemotherapy n = 20; hormonal therapy n = 7). Response rate to surgery was 100 %, to RT 85 %, to RT+systemic therapy 87 %, to chemotherapy 70 %, and to hormonal therapy 14 %. Duration of neurological response and of extracranial response to chemotherapy as single treatment was similar (8 and 7 months, respectively). Patients with single BM and patients without extracranial disease had a better survival but the difference was not significant. CONCLUSION: Chemotherapy as single treatment for BM from breast cancer is feasible and should not be restricted to salvage treatment.