Citations

Abstract SARS-CoV-2 infection disrupts iron homeostasis in organs such as the lung. Emerging evidence suggests similar dysregulation in the placenta may impair function and fetal growth. Ferroptosis, an iron-dependent form of cell death, is driven by the accumulation of labile ferrous iron, catalyzing the peroxidation of polyunsaturated fatty acids in the absence of sufficient iron storage or antioxidant defenses. This pathway has been implicated in SARS-CoV-2-related tissue damage in other organs and may contribute to placental dysfunction during pregnancy. However, the influence of infection timing, symptom severity, and fetal sex on placental iron regulation remains unexamined. We analyzed placental samples from a cohort of SARS-CoV-2-exposed pregnancies in the first (n = 6), second (n = 14), or third trimester (n = 30), classified by symptom severity (asymptomatic n = 23, symptomatic n = 27) and fetal sex, alongside unexposed controls (n = 47). We assessed placental iron deposition, lipid peroxidation, and mRNA and protein expression of ferroptosis markers. Publicly available RNA-sequencing datasets from human placenta tissue, exposed or not to SARS-CoV-2, were analyzed to assess ferroptosis-related gene expression. SARS-CoV-2 infection, particularly in symptomatic cases, was associated with reduced placental weight and birth weight. Asymptomatic cases showed increased placental iron deposition, which correlated with lower birthweight and was accompanied by elevated expression of nuclear receptor coactivator 4, a cytosolic adaptor protein that mediates the selective autophagic degradation of ferritin (ferritinophagy) and iron release. Placentas from symptomatic patients exhibited evidence of altered iron transport and sex-specific down-regulation of antioxidant defenses. Transcriptomic analyses further suggested widespread disruption of ferroptosis pathways in placentas from infected patients. Our findings reveal that SARS-CoV-2 infection alters placental iron homeostasis and is associated with ferroptosis-related changes, with distinct molecular responses based on timing of infection, symptom severity, and fetal sex.

With more than 6000 attendees between in-person and virtual offerings, the American Epilepsy Society Meeting 2022 in Nashville, felt as busy as in prepandemic times. An ever-growing number of physicians, scientists, and allied health professionals gathered to learn a variety of topics about epilepsy. The program was carefully tailored to meet the needs of professionals with different interests and career stages. This article summarizes the different symposia presented at the meeting. Basic science lectures addressed the primary elements of seizure generation and pathophysiology of epilepsy in different disease states. Scientists congregated to learn about anti-seizure medications, mechanisms of action, and new tools to treat epilepsy including surgery and neurostimulation. Some symposia were also dedicated to discuss epilepsy comorbidities and practical issues regarding epilepsy care. An increasing number of patient advocates discussing their stories were intertwined within scientific activities. Many smaller group sessions targeted more specific topics to encourage member participation, including Special Interest Groups, Investigator, and Skills Workshops. Special lectures included the renown Hoyer and Lombroso, an ILAE/IBE joint session, a spotlight on the impact of Dobbs v. Jackson on reproductive health in epilepsy, and a joint session with the NAEC on coding and reimbursement policies. The hot topics symposium was focused on traumatic brain injury and post-traumatic epilepsy. A balanced collaboration with the industry allowed presentations of the latest pharmaceutical and engineering advances in satellite symposia.

Abstract The blood–brain barrier ensures CNS homeostasis and protection from injury. Claudin-5 (CLDN5), an important component of tight junctions, is critical for the integrity of the blood–brain barrier. We have identified de novo heterozygous missense variants in CLDN5 in 15 unrelated patients who presented with a shared constellation of features including developmental delay, seizures (primarily infantile onset focal epilepsy), microcephaly and a recognizable pattern of pontine atrophy and brain calcifications. All variants clustered in one subregion/domain of the CLDN5 gene and the recurrent variants demonstrate genotype–phenotype correlations. We modelled both patient variants and loss of function alleles in the zebrafish to show that the variants analogous to those in patients probably result in a novel aberrant function in CLDN5. In total, human patient and zebrafish data provide parallel evidence that pathogenic sequence variants in CLDN5 cause a novel neurodevelopmental disorder involving disruption of the blood–brain barrier and impaired neuronal function.

Abstract Estrogen receptor positive (ER+) breast cancer is treated with endocrine therapy but intrinsic resistance occurs in ˜1/3 of patients and acquired resistance in ˜1/5 of the remainder. While many resistance mechanisms have been explored, clinical trials testing associated therapeutics have had mixed outcomes. Understanding mechanisms of resistance and finding therapeutic strategies to target them, therefore, remain important challenges. In this study we discover an intriguing link between mismatch repair (MMR) deficiency, specifically of the MutL complex (MLH1/3, PMS1/2), and endocrine therapy resistance in ER+ disease. We find a direct role for MutL loss in inducing endocrine therapy resistance in vitro and in vivo by knocking down multiple MutL genes using CRISPR and stable shRNA approaches validated using standard rescue experiments. We identify the underlying mechanism: MutL deficiency in ER+ breast cancer abrogates Chk2-mediated feedback inhibition of CDK4/6 that appears necessary for endocrine therapy responsiveness. Consequently, pharmacological targeting of CDK4/6 in vitro and in vivo significantly inhibits growth of endocrine therapy resistant MutL-deficient ER+ breast cancer cells. These results are corroborated by data from a neoadjuvant clinical trial demonstrating that cell cycle regulation of MutL-mutant tumors is estrogen-independent but CDK4/6 dependent. The results of this study provide important biological and clinically relevant insights. 1) a novel role for MMR in endocrine therapy resistance 2) A mechanism underlying the effectiveness of CDK4/6 inhibitors in some de novo endocrine therapy resistant tumors. While there are currently no biomarkers to guide the use of CDK4/6 inhibitors for ER+ breast cancer, markers of MMR dysregulation could identify patients in whom CDK4/6 inhibition may, most effectively, prevent disease recurrence. Citation Format: Haricharan S, Punturi N, Singh P, Holloway KR, Anurag M, Schmelz J, Schmidt C, Lei JT, Suman V, Hunt K, Olson Jr JA, Hoog J, Li S, Huang S, Edwards DP, Kavuri SM, Bainbridge MN, Ma CX, Ellis MJ. Loss of mismatch repair predicts resistance to endocrine therapy and sensitivity to CDK4/6 inhibitors in ER+ breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P4-04-01.

Abstract Significant endocrine therapy–resistant tumor proliferation is present in ≥20% of estrogen receptor–positive (ER+) primary breast cancers and is associated with disease recurrence and death. Here, we uncover a link between intrinsic endocrine therapy resistance and dysregulation of the MutL mismatch repair (MMR) complex (MLH1/3, PMS1/2), and demonstrate a direct role for MutL complex loss in resistance to all classes of endocrine therapy. We find that MutL deficiency in ER+ breast cancer abrogates CHK2-mediated inhibition of CDK4, a prerequisite for endocrine therapy responsiveness. Consequently, CDK4/6 inhibitors (CDK4/6i) remain effective in MutL-defective ER+ breast cancer cells. These observations are supported by data from a clinical trial where a CDK4/6i was found to strongly inhibit aromatase inhibitor–resistant proliferation of MutL-defective tumors. These data suggest that diagnostic markers of MutL deficiency could be used to direct adjuvant CDK4/6i to a population of patients with breast cancer who exhibit marked resistance to the current standard of care. Significance: MutL deficiency in a subset of ER+ primary tumors explains why CDK4/6 inhibition is effective against some de novo endocrine therapy–resistant tumors. Therefore, markers of MutL dysregulation could guide CDK4/6 inhibitor use in the adjuvant setting, where the risk benefit ratio for untargeted therapeutic intervention is narrow. Cancer Discov; 7(10); 1168–83. ©2017 AACR. This article is highlighted in the In This Issue feature, p. 1047

Abstract Estrogen receptor positive (ER+) breast cancer is treated with endocrine therapy but intrinsic resistance occurs in ~1/3 of patients and acquired resistance in ~1/5 of the remainder. While many resistance mechanisms have been explored, therapeutic strategies to overcome resistance in the clinical setting have seen mixed outcomes, and appear most effective in the acquired resistance setting. Understanding mechanisms of resistance and finding therapeutic strategies to target them, therefore, remain important challenges facing breast cancer researchers. In this study we systematically examine the role of DNA damage repair defects in inducing endocrine therapy resistance, a relatively understudied question of recent interest. We use in silico analysis of clinical datasets, in vitro experiments evaluating endocrine therapy resistance in response to DDR dysregulation in multiple breast cancer celllines, and in vivo validation using cellline xenograft and patient-derived xenograft models. We also use gene expression microarrays and RPPA data from cell lines, patient-derived xenografts and primary ER+ breast tumors to uncover therapeutic options that are validated in vitro and in vivo and corroborated by clinical trial data. The results of this study uncover an intriguing link between mismatch repair (MMR) deficiency, specifically of the MutL complex (MLH1/3, PMS1/2), and poor prognosis in ER+ disease. We find a direct role for MutL loss in endocrine therapy resistance in vitro and in vivo by knocking down multiple MutL genes using CRISPR and stable shRNA approaches validated using standard rescue experiments. We identify the underlying mechanism: MutL deficiency in ER+ breast cancer abrogates Chk2-mediated feedback inhibition of CDK4/6 that appears necessary for endocrine therapy responsiveness. Consequently, pharmacological targeting of CDK4/6 in vitro and in vivo significantly inhibits growth of endocrine therapy resistant MutL-deficient ER+ breast cancer cells. These results are corroborated by data from a neoadjuvant clinical trial demonstrating that cell cycle regulation of MutL-mutant tumors tends to be estrogen-independent but sensitive to CDK4/6 inhibitors. The results of this study provide important biological and clinically relevant insights. 1) MMR deficiency is unexpectedly causal to intrinsic endocrine therapy resistance 2) This causal effect appears to be mediated by abrogation of cell cycle checkpoint activation in response to endocrine therapy 3) MMR deficiency in a subset of ER+ tumors explains why CDK4/6 inhibition is effective against some de novo endocrine therapy resistant tumors. While there are currently no biomarkers to guide the use of CDK4/6 inhibitors for ER+ breast cancer, markers of MMR dysregulation could identify patients in whom CDK4/6 inhibition should be used to prevent disease recurrence. Citation Format: Svasti Haricharan, Jacob Schmelz, Cheryl Schmidt, Purba Singh, Kimberly R. Holloway, Meenakshi Anurag, Shunqiang Li, Shyam M. Kavuri, Shixia Huang, Dean P. Edwards, Vera Suman, Kelly Hunt, John A. Olson, Jeremy Hoog, Cynthia X. Ma, Matthew N. Bainbridge, Matthew J. Ellis. Mismatch repair defects and endocrine therapy resistance in estrogen receptor positive breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 489. doi:10.1158/1538-7445.AM2017-489