Naoya Asai

Objectives: Genetic risk models have substantially advanced our understanding of germline pathogenic variants (GPVs) in some malignancies, whereas their clinical significance in lung cancer remains unclear. The present study aimed to better understand potential contribution of GPVs to lung cancer etiology. Methods: A targeted sequencing panel of 143 cancer-related genes was applied to analyze 26 distinct lung adenocarcinoma (LUAD) tumors from 11 patients histopathologically diagnosed with multiple primary lung cancers (MPLC). Tumor classification was performed through integrated evaluation of mutation profiles, and variants shared among tumor lesions were further validated as likely germline or somatic mutations using Sanger sequencing. Results: Mutation profiles were compared to reveal clonal relationships among lesions in each patient. Nine of the 11 cases (81.8%) were classified as MPLC, 1/11 (9.1%) as intrapulmonary metastasis (IM), and 1/11 (9.1%) exhibited features of both MPLC and IM. Among the nine MPLC cases, eight (88.9%) harbored matching variants across independent tumor lesions that were also detected in tumor-adjacent regions, suggesting classification as likely germline variants. Importantly, among the eight cases with shared variants, one possessed a novel truncating BRCA2 DNA repair associated (BRCA2) variant (p.N900IfsTer4), while the others harbored variants of uncertain significance (VUS) in the tumor protein p53 (TP53), caspase recruitment domain family member 11 (CARD11), platelet derived growth factor receptor beta (PDGFRB), lysine methyltransferase 2D (KMT2D), phosphoinositide-3-kinase regulatory subunit 1 (PIK3R1), neuregulin 1 (NRG1), androgen receptor (AR), and KIT proto-oncogene, receptor tyrosine kinase (KIT) genes. To determine whether a similar BRCA2 variant was present in other lung cancer patients, 123 LUAD cases were analyzed, and one (0.81%) possessing a truncating BRCA2 variant (p.Q1429FfsTer20) without any typical driver mutations was identified. Conclusions: BRCA2 GPVs may represent putative pathogenic mutations, and thus be potential molecular targets for future treatment of LUAD.

Complement factor D (CFD, also known as adipsin) is a secreted serine protease classically known for activating the alternative complement pathway and regulating systemic metabolism. Although CFD is highly expressed in adipocytes, its roles in adipogenesis remain to be elucidated. Here, we show that intracellularly localized CFD promoted lipid droplet (LD) formation in its catalytic activity-independent manner. Using mammary adipose tissue-derived stem cells (mADSCs) isolated from wild-type (WT) and Cfd-knockout (Cfd-KO) mice, we demonstrated that the lack of CFD significantly reduced LD number in mature adipocytes. Lentiviral expression of the secretion signal sequence-deficient (SD) or catalytically inactive CFD mutant, as well as the cytosolic CFD3 splice variant, rescued LD formation to WT levels in Cfd-KO adipocytes. In contrast, exogenously supplemented CFD proteins were unable to restore LD formation in our culture system. These findings uncover a previously unrecognized intracellular function for CFD, revealing its regulatory role in LD biogenesis during adipocyte differentiation.

Abstract Objective Loss‐of‐function mutations in the GIRDIN/CCDC88A gene cause developmental epileptic encephalopathy (DEE) in humans. However, its pathogenesis is largely unknown. Global knockout mice of the corresponding orthologous gene (gKOs) have a preweaning lethal phenotype with growth failure, preventing longitudinal analysis. We aimed to overcome this lethality and elucidate DEE pathogenesis. Methods We developed a novel lifelong feeding regimen (NLFR), which consists of providing mash food from postnatal day 14 (P14) until weaning (P28), followed by agar‐bound food exclusively after weaning. Videography, electroencephalography (EEG), and histological analyses were performed. Conditional Girdin/Ccdc88a knockout mice (cKOs) of variable lineages (Nestin, Emx1, or Nkx2‐1) were generated to identify the region responsible for epilepsy. Results Under the NLFR, gKOs survived beyond 1 year and displayed fully penetrant, robust epileptic phenotypes, including early‐onset (P22.3 in average) generalized tonic–clonic seizures (GTCSs) (averaging eight per day), which were completely synchronized with fast rhythms on EEG, frequent interictal electroencephalographic spikes (averaging 430 per hour), and progressive deformation of visceral organs. In addition, gKOs had absence seizures, which were not always time‐locked to frequent spike waves on EEG. The frequent GTCSs and interictal spikes in gKOs were suppressed by known antiepileptic drugs. Histologically, bilateral hippocampi in gKOs exhibited congenital cornu‐ammonis splitting, granule cell dispersion, and astrogliosis. Furthermore, analysis of conditional knockouts using multiple Cre‐deleters identified a defect in the delivery of interneuron precursors from the medial ganglionic eminence into the hippocampal primordium during embryogenesis as a major cause of epileptogenesis. Significance These findings give rise to a new approach of lifelong caregiving to overcome the problem of preweaning lethality in animal models. We propose a useful model for studying DEE with hippocampal sclerosis and interneuronopathy. gKOs with NLFR combine the contradictory properties of robust epileptic phenotypes and long‐term survivability, which can be used to investigate spontaneous epileptic wave propagation and therapeutic intervention in hippocampal sclerosis.

Adipocyte-cancer cell interactions promote tumor development and progression. Previously, we identified adipsin (CFD) and its downstream effector, hepatocyte growth factor (HGF), as adipokines that enhance adipocyte-breast cancer stem cell interactions. Here, we show that adipsin-dependent adipocyte maturation and the subsequent upregulation of HGF promote tumor invasion in breast cancers. Mature adipocytes, but not their precursors, significantly induced breast tumor cell migration and invasion in an adipsin expression-dependent manner. Promoters of tumor invasion, galectin 7 and matrix metalloproteinases, were significantly upregulated in cancer cells cocultured with mature adipocytes; meanwhile, their expression levels in cancer cells cocultured with adipocytes were reduced by adipsin knockout (Cfd KO) or a competitive inhibitor of CFD. Tumor growth and distant metastasis of mammary cancer cells were significantly suppressed when syngeneic mammary cancer cells were transplanted into Cfd KO mice. Histological analyses revealed reductions in capsular formation and tumor invasion at the cancer-adipocyte interface in the mammary tumors formed in Cfd KO mice. These findings indicate that adipsin-dependent adipocyte maturation may play an important role in adipocyte-cancer cell interaction and breast cancer progression.