Citations

PURPOSE The prevalence of germline pathogenic variants (PVs) in established breast cancer predisposition genes in women in the general population over age 65 years is not well-defined. However, testing guidelines suggest that women diagnosed with breast cancer over age 65 years might have < 2.5% likelihood of a PV in a high-penetrance gene. This study aimed to establish the frequency of PVs and remaining risks of breast cancer for each gene in women over age 65 years. METHODS A total of 26,707 women over age 65 years from population-based studies (51.5% with breast cancer and 48.5% unaffected) were tested for PVs in germline predisposition gene. Frequencies of PVs and associations between PVs in each gene and breast cancer were assessed, and remaining lifetime breast cancer risks were estimated for non-Hispanic White women with PVs. RESULTS The frequency of PVs in predisposition genes was 3.18% for women with breast cancer and 1.48% for unaffected women over age 65 years. PVs in BRCA1, BRCA2, and PALB2 were found in 3.42% of women diagnosed with estrogen receptor (ER)–negative, 1.0% with ER-positive, and 3.01% with triple-negative breast cancer. Frequencies of PVs were lower among women with no first-degree relatives with breast cancer. PVs in CHEK2, PALB2, BRCA2, and BRCA1 were associated with increased risks (odds ratio = 2.9-4.0) of breast cancer. Remaining lifetime risks of breast cancer were ≥ 15% for those with PVs in BRCA1, BRCA2, and PALB2. CONCLUSION This study suggests that all women diagnosed with triple-negative breast cancer or ER-negative breast cancer should receive genetic testing and that women over age 65 years with BRCA1 and BRCA2 PVs and perhaps with PALB2 and CHEK2 PVs should be considered for magnetic resonance imaging screening.

Summary Even in the era of highly active combination antiretroviral therapy (cART), patients with HIV have a disproportionate risk of developing aggressive lymphomas that are frequently Epstein‐Barr virus (EBV)‐related. Here, we investigate HIV‐associated diffuse large B‐cell lymphoma (HIV‐DLBCL) and compare EBV‐positive and EBV‐negative cases. HIV‐DLBCL were identified from two academic medical centres and characterised by immunohistochemistry, EBV status, fluorescence in situ hybridisation, cell of origin determination by gene expression profiling, and targeted deep sequencing using a custom mutation panel of 334 genes. We also applied the Lymphgen tool to determine the genetic subtype of each case. Thirty HIV‐DLBCL were identified, with a median patient age of 46 years and male predominance (5:1). Thirteen cases (48%) were EBV‐positive and 14 (52%) EBV‐negative. Nine of the 16 tested cases (56%) had MYC rearrangement, three (19%) had BCL6 (two of which were double hit MYC / BCL6 ) and none had BCL2 rearrangements. Using the Lymphgen tool, half of the cases (15) were classified as other. All HIV‐DLBCL showed mutational abnormalities, the most frequent being TP53 (37%), MYC (30%), STAT3 (27%), HIST1H1E (23%), EP300 (20%), TET2 (20%), SOCS1 (17%) and SGK1 (17%). EBV‐negative cases were mostly of germinal centre B‐cell (GCB) origin (62%), showed more frequent mutations per case (a median of 13·5/case) and significant enrichment of TP53 (57% vs. 15%; P = 0·046), SGK1 (36% vs. 0%; P = 0·04), EP300 (43% vs. 0%; P = 0·02) and histone‐modifying gene (e.g. HIST1H1E , HIST1H1D , 79% vs. 31%; P = 0·02) mutations. EBV‐positive cases were mostly of non‐GCB origin (70%), with fewer mutations per case (median 8/case; P = 0·007), and these tumours were enriched for STAT3 mutations ( P = 0·10). EBV‐positive cases had a higher frequency of MYC mutations but the difference was not significant (36% vs. 15%; P = 0·38). EBV‐association was more frequent in HIV‐DLBCLs, arising in patients with lower CD4 counts at diagnosis (median 46·5 vs. 101, P = 0·018). In the era of cART, approximately half of HIV‐DLBCL are EBV‐related. HIV‐DLBCL are enriched for MYC rearrangements, MYC mutations and generally lack BCL2 rearrangements, regardless of EBV status. Among HIV‐DLBCL, tumours that are EBV‐negative and EBV‐positive appear to have important differences, the latter arising in context of lower CD4 count, showing frequent non‐GCB origin, lower mutation burden and recurrent STAT3 mutations.

Metabolic drugs frequently target mitochondrial functions and AMP signaling. Metformin, one of the most prescribed anti-diabetic medications, exerts its glucose lowering effect through mild interference with mitochondrial energy metabolism triggering homeostatic adenylate kinase (AK)-catalyzed AMP and downstream AMPK signaling. However, metabolomic signature of drug-induced “therapeutic mitochondrial toxicity" and energetic imbalance-induced AMP signaling are poorly understood. This work was aimed to determine metabolomic representation of metformin-induced mitochondrial and AMP signaling stress by comparing wild type and AK1-deficient mice with compromised AMP-signaling. Metabolomic profiling of plasma and urine samples from wild type mice treated with metformin revealed distinct metabolic signature suggesting altered energy, Krebs cycle, lipid and ketone body metabolism, with higher levels of creatinine, malate, α-ketoglutarate, FFA, glycerol, glycerol-3-phosphate, 3-hydroxybutyrate and hypoxanthine. Contrary to expectations glucose lowering effect of metformin was greater in energetically and AMP-signaling compromised AK1-/- mice. Metformin action on AK1 deficient mice was characterized by increased levels of creatinine, lactate, alanine, FFA, phosphoserine, acetoacetate, 3-hydroxybutyrate, malate and α-ketoglutarate indicating broader alterations in energy, glycolytic, Krebs cycle, ketone body, lipid and amino acid metabolism. At baseline, livers from AK1-/- mice had higher AMP/ADP and pAMPKα/AMPKα ratios compared to wild type. There were no significant sustained changes in global nucleotide ratios after metformin treatment. Overall metabolomic profile of AK1-/- mice indicate larger disturbances in energetic and substrate metabolic networks after metformin treatment compared to wild type. Thus, this study revealed specific metabolomic signatures of metformin therapeutic action and mitochondrial toxicity indicating that genetic and metabolic background modulate individual response to metformin treatment.

Energy metabolism and metabolic signaling circuits orchestrate cell commitment to self-renewal, lineage specification, differentiation and regeneration. When energy resources are plenty, cell can grow, proliferate and regenerate, however when energy is low - augmented adenylate kinase (AK)-mediated AMP signaling turns on AMPK which silences p53/p21/cyclin cell cycle metabolic checkpoint and halts cell division. Using mouse neonatal hearts, with high and low regenerative capacity, we have determined metabolomic profiles and dynamics of phosphotransfer circuits using 18O-phosphoryl labeling mass-spectrometric and 18O-assisted 31P NMR techniques. We demonstrate that loss of heart regenerative capacity after birth is associated with marked changes in heart AK-catalyzed phosphotransfer flux and AMP signaling along with changes in expression levels of p21, cyclin A and E and thymidine kinase. It appears, that in adult heart increased expression of AK isoforms (AK1, AK2 and AK1β) and augmented high energy phosphoryl and AMP signal dynamics is misread by AMPK-sensor as "low energy" state inducing blockade of cell cycle metabolic checkpoint and cardiomyocyte proliferation and renewal. Using AK-GFP constructs and immunocytochemistry we further demonstrate the distribution of AK1, AK1β, AK2 and AMPK between cytosol and nucleus and association with mitotic spindle and cytokinetic apparatus during cell division cycle. AK1 translocation to the nucleus, however, doesn’t occur in adult cardiomyocytes deficient in cytokinesis. Protein knockdown using siRNA indicates that AK2 is critical for cardiomyocyte mitochondrial biogenesis and network formation. Furthermore, we have discovered that deficiency of the AK2 isoform, which is localized in mitochondria intermembrane-intra-cristae space, arrests developmental programming and is embryonically lethal in mice. The uncovered shift in metabolic signaling mechanisms opens new avenues for targeted regulation of heart regenerative potential critical for repair of injured hearts.

Metabolic signaling mechanisms of tissue regeneration is still an enigma. Energy state and metabolite signals regulate cell commitment to self-renewal, lineage specification, differentiation and regeneration. In a favorable metabolic environment, cells can grow and proliferate, however when energy is low - metabolic monitoring system sends signals to cell cycle checkpoint to halt cell division and preserve fuel resources. We demonstrate that loss of heart regenerative capacity after birth in mice is associated with marked changes in metabolome, AK-catalyzed phosphotransfer flux (β-ATP[ 18 O]), ATP turnover (γ-ATP[ 18 O]) and AMP-AMPK signaling along with changes in expression levels of p21, cyclins A and E, pGSK3β and thymidine kinase. Marked reduction of thymidine phosphorylation capacity prevents DNA synthesis and cell proliferation. It emerges, that in adult heart augmented ATP turnover and AMP signal dynamics is misread by AMPK-sensor as "low energy" state inducing blockade of cell cycle metabolic checkpoint and cardiomyocyte proliferation and regeneration after injury. This occurs through augmented adenylate kinase (AK)-mediated AMP signaling which turns on AMPK consequently silencing p53/p21/cyclin cell cycle checkpoint. Changes in expression levels AK1, AK1β, AK2 and AK5 isoforms occur with arrest of heart regeneration. Protein knockdown using siRNA and CRISPR/Cas9 approach indicates that AK2 is critical for cardiomyocyte mitochondrial biogenesis and network formation. Furthermore, we have discovered that deficiency of the AK2 isoform, which is localized in mitochondria intermembrane-intra-cristae space, arrests developmental programming and is embryonically lethal in mice. The uncovered shift in metabolic signaling mechanisms opens new avenues for targeted regulation of heart regenerative potential critical for repair of injured hearts.

The mammalian heart loses its regenerative potential within a week after birth. Although under certain circumstances adult cardiomyocytes can re-enter the cell cycle, initiate DNA synthesis and progress towards mitosis, however, they do not complete a conventional mitosis cycle and proceed towards endomitosis resulting in polyploidy. This suggests that high-energy dependent steps in cell cycle and myofibrillar disassembly are malfunctioning in adult cardiomyocytes. It is known that nucleotide-based energetic signaling and metabolic environment are critical for initiation of tissue regeneration after injury. The regulatory mechanisms and energetic-metabolic signaling circuits that govern cardiomyocyte cell cycle withdrawal and binucleation are poorly understood. Using mouse neonatal (2 and 10 days) hearts, with high and low regenerative capacity, respectively, we have determined metabolomic profiles and dynamics of phosphotransfer circuits and AMP-signaling using 18O-phosphoryl labeling mass-spectrometric and 18O-assisted 31P NMR techniques. The results demonstrate that loss of heart regenerative capacity 10 days after birth is associated with marked changes in heart metabolome and adenylate kinase (AK)-catalyzed phosphotransfer flux. Among most altered metabolites were putrescine and myo-inositol, involved in tissue regeneration, Krebs cycle and amino acid metabolites, creatinine, glucose-6-phosphate and lactate indicating rearrangements in energy and substrate metabolic systems. AK flux was the only phosphotransfer flux significantly upregulated in hearts at 10 days of age along with increased in mitochondrial and glycolytic capacities and mitochondrial AK2 expression. Increased AK2 expression was associated with augmented AMP phosphorylation, measured by generation of β-ATP[18O], and reduction of AMPK activity. Thus, increased channeling of AMP into mitochondria and reduction of AK-AMP-AMPK signaling axis could contribute to the withdrawal from completion of cell cycle in terminally differentiated adult cardiomyocytes. The uncovered metabolic signaling mechanism opens new avenues for targeted regulation of heart regenerative potential critical for repair of injured hearts.

Knowledge of major adverse clinical events (MACE) associated with ICD and pacemaker (PM) pulse generator (PG) and lead performance may be important for managing patients who have these devices. The aim of our study was to assess MACE in our Multicenter Registry. Participating centers prospectively reported ICD and PM PG and lead failures, and PG replaced for normal battery depletion (NBD). Data included dates of implant and removal, failure signs including the elective replacement indicator (ERI), clinical consequences, and reason for removal. MACE were death, inappropriate shocks (IAS), syncope, heart failure, ischemia, sustained tachyarrhythmias, and replacement of a normally functioning PG or lead due to a manufacturers recall. Since 1998, 6,291 ICD and PM PG and leads were removed from service. Of 5,212 ICD and PM PGs, 4,562 (88%) were removed for NBD, 346 (7%) for a recall, and 304 (5%) for component defects. MACE are shown in the Table . The deaths (n=2) were due to component defects causing an ICD PG to short-circuit and a PM PG to deliver high rate pacing. Thus, of the 304 component defects in our database, 2 resulted in death (0.7%). No deaths were associated with ICD or PM lead failure, but 2 deaths occurred following PM lead extraction. The ERI, signifying NBD, resulted in 48 MACE, primarily syncope (67%). Most MACE are due to replacement of normally functioning recalled devices. However, our experience suggests that death due to ICD and PM PG component or lead failure is rare; this finding may be important for managing patients who have recalled devices. Overall, MACE may be substantially reduced by improving high voltage lead reliability, and by providing physiologic ERIs.