The Genomic Landscape of Lobular Breast Cancer.

Invasive lobular carcinoma (ILC) is the second most common breast cancer histologic subtype, accounting for approximately 15% of all breast cancers. It is only recently that its unique biology has been assessed in high resolution. Here, we present a meta-analysis of ILC sequencing datasets, to provide a long-awaited ILC-specific resource, and to confirm the prognostic value and strength of association between a number of clinico-pathology features and genomics in this special tumour type. We consider panel (n = 684), whole exome (n = 215) and whole genome sequencing data (n = 48), and review histology of The Cancer Genome Atlas cases to assign grades and determine whether the ILC is of classic type or a variant, such as pleomorphic, prior to performing statistical analyses. We demonstrate evidence of considerable genomic heterogeneity underlying a broadly homogeneous tumour type (typically grade 2, estrogen receptor (ER)-positive); with genomes exhibiting few somatic mutations or structural alterations, genomes with a hypermutator phenotype, and tumours with highly rearranged genomes. We show that while CDH1 (E-cadherin) and PIK3CA mutations do not significantly impact survival, overall survival is significantly poorer for patients with a higher tumour mutation burden; this is also true for grade 3 tumours, and those carrying a somatic TP53 mutation (and these cases were more likely to be ER-negative). Taken together, we have compiled a meta-dataset of ILC with molecular profiling, and our analyses show that the genomic landscape significantly impacts the tumour's variable natural history and overall survival of ILC patients.

Correction: McCart Reed et al. The Genomic Landscape of Lobular Breast Cancer. Cancers 2021, 13, 1950.

The authors wish to make the following corrections to this paper [...].

MRI changes and complement activation correlate with epileptogenicity in a mouse model of temporal lobe epilepsy.

The complex pathogenesis of temporal lobe epilepsy includes neuronal and glial pathology, synaptic reorganization, and an immune response. However, the spatio-temporal pattern of structural changes in the brain that provide a substrate for seizure generation and modulate the seizure phenotype is yet to be completely elucidated. We used quantitative magnetic resonance imaging (MRI) to study structural changes triggered by status epilepticus (SE) and their association with epileptogenesis and with activation of complement component 3 (C3). SE was induced by injection of pilocarpine in CD1 mice. Quantitative diffusion-weighted imaging and T2 relaxometry was performed using a 16.4-Tesla MRI scanner at 3 h and 1, 2, 7, 14, 28, 35, and 49 days post-SE. Following longitudinal MRI examinations, spontaneous recurrent seizures and interictal spikes were quantified using continuous video-EEG monitoring. Immunohistochemical analysis of C3 expression was performed at 48 h, 7 days, and 4 months post-SE. MRI changes were dynamic, reflecting different outcomes in relation to the development of epilepsy. Apparent diffusion coefficient changes in the hippocampus at 7 days post-SE correlated with the severity of the evolving epilepsy. C3 activation was found in all stages of epileptogenesis within the areas with significant MRI changes and correlated with the severity of epileptic condition.

Hippocampal volume and cell density changes in a mouse model of human genetic epilepsy.

OBJECTIVE: The human γ-aminobutyric acid type A (GABAA)γ2R43Q (R43Q) mutation is associated with genetic epilepsy with febrile seizures. R43Q mice in the C57Bl/6J background do not display spontaneous seizures, but are significantly more susceptible to hyperthermic seizures, providing a model with enhanced seizure susceptibility without the confounding influence of ongoing epileptic activity. Because of GABA's role in brain development, we sought to determine whether the R43Q mutation alters brain structure before the appearance of seizures. METHODS: We used 16.4-tesla, high-field MRI to determine the volumes of hippocampal subregions. Histologic analysis of the same brains allowed stereology-based estimates of neuron counts to be obtained in CA1-3 and the dentate gyrus. RESULTS: Morphologic changes were evident in seizure-naive hippocampi of susceptible mice. Dentate granule cell MRI determined that volume was 5% greater in R43Q mice compared with controls (0.628 mm(3), 95% confidence interval [CI] 0.611-0.645 vs 0.595 mm(3), 95% CI 0.571-0.619). The dentate granule cell density was 30% higher in R43Q compared with control mice (553 × 10(3) cells/mm(3), 95% CI 489-616 vs 427 × 10(3) cells/mm(3), 95% CI 362-491). CONCLUSIONS: In a genetic epilepsy model that is both seizure-naive and carries an allele for febrile seizure susceptibility, we have determined hippocampal structural changes that may be applied as a biomarker for seizure susceptibility.