The class II myosin MYH4 safeguards genome integrity and suppresses tumor progression

• Text
• PDF

Abstract

Loss-of-function mutations in genome maintenance genes fuel tumorigenesis through increased genomic instability. A subset of these tumor suppressors are challenging to identify due to context dependency, including functional interactions with other genes and pathways. Here, we searched for potential causal genes that impact tumor development and/or progression in breast cancer through functional-genetic screening of candidate genes. MYH4, encoding a class II myosin, emerged as a top hit impacting genomic stability. We show that MYH4 suppresses DNA replication stress by promoting replication licensing and replication fork progression. Moreover, we observed a strong synergistic relationship among class II myosins in suppressing replication-associated DNA damage. Genomic analysis of Pan-Cancer Analysis of Whole Genomes project breast cancer samples revealed frequent concomitant loss of TP53 with MYH4 and class II myosins on chromosome 17p. Notably, Myh4 disruption accelerated mouse mammary tumorigenesis in a Trp53-deficient background. In conclusion, our results suggest an unanticipated function of MYH4 in p53-mediated tumor suppression that can explain their combined loss in breast cancer.

Authors

Jayashree Thatte, Ana Moisés da Silva, Judit Börcsök, Thorkell Gudjónsson, Jan Benada, Xin Li, Muthiah Bose, Hanneke van der Gulden, Ji-Ying Song, Renée Menezes, Elena Martín-Doncel, Luis Toledo, Valdemaras Petrosius, Cord Brakebusch, Jos Jonkers, Finn Cilius Nielsen, Maria Rossing, Claus S. Sørensen

Phospho-RPA2 predicts response to platinum and PARP inhibitors in homologous recombination-proficient ovarian cancer

• Text
• PDF

Abstract

BACKGROUND. Treatment of tubo-ovarian high-grade serous carcinoma (HGSC) includes cytoreductive surgery, platinum-based chemotherapy, and often poly (ADP-ribose) polymerase (PARP) inhibitors. While homologous recombination (HR)-deficiency is a well-established predictor of therapy sensitivity, over 50% of HR-proficient HGSC also exhibit sensitivity. Currently, there are no biomarkers to identify which HR-proficient HGSCs will be sensitive to standard-of-care therapy. Replication stress may serve as a key determinant of response. METHODS. We evaluated phospho-RPA2-T21 (pRPA2) foci via immunofluorescence as a biomarker of replication stress in formalin-fixed, paraffin-embedded HGSC samples collected at diagnosis from patients treated with platinum chemotherapy (discovery cohort: n=31, validation cohort: n=244) or PARP inhibitors (n=63). Recurrent HGSCs (n=38) were also analyzed. pRPA2 score was calculated using automated imaging analysis. RESULTS. Samples were defined as pRPA2-High if >16% of cells had ≥2 pRPA2 foci on automated analysis. In the discovery cohort, HR-proficient, pRPA2-High HGSCs demonstrated significantly higher rates of a chemotherapy response score of 3 to platinum chemotherapy than HR-proficient, pRPA2-Low HGSCs. In the validation cohort, patients with HR-proficient, pRPA2-High HGSCs had significantly longer survival after platinum treatment than those with HR-proficient, pRPA2-Low HGSCs. Additionally, the pRPA2 assay effectively predicted survival outcomes in patients treated with PARP inhibitors and in recurrent HGSC samples. CONCLUSION. Our study underscores the importance of considering replication stress marker, such as pRPA2, alongside HR status in therapeutic planning. This approach has the potential to increase the number of patients receiving effective therapy while reducing unnecessary toxicity.

Authors

Angela Schab, Amanda Compadre, Rebecca Drexler, Megan Loeb, Kevin Rodriguez, Joshua Brill, Shariska Harrington, Carmen Sandoval, Brooke Sanders, Lindsay Kuroki, Carolyn McCourt, Andrea R. Hagemann, Premal Thaker, David Mutch, Matthew Powell, Violeta Serra, Ian S. Hagemann, Ann E. Walts, Beth Y. Karlan, Sandra Orsulic, Katherine Fuh, Lulu Sun, Priyanka Verma, Elena Lomonosova, Peinan Zhao, Dineo Khabele, Mary M. Mullen

Plasma endotrophin levels correlate with insulin resistance in people with obesity

• Text
• PDF

Abstract

BACKGROUND. Adipose tissue-derived endotrophin, a peptide cleaved from the α3 chain of collagen VI during fibrogenesis, causes systemic insulin resistance in rodent models. Here, we evaluated the potential importance of endotrophin in regulating whole-body insulin sensitivity in people. METHODS. We evaluated: i) plasma endotrophin concentration, insulin sensitivity (assessed by using the hyperinsulinemic-euglycemic clamp procedure in conjunction with stable isotopically labeled glucose tracer infusion) and adipose tissue expression of genes involved in endotrophin production in three groups of participants that were rigorously stratified by adiposity and insulin sensitivity [lean insulin-sensitive (Lean-IS; n=10), obese insulin-sensitive (Obese-IS; n=10), and obesity insulin-resistant (Obese-IR; n=10)]; ii) plasma endotrophin concentration and insulin sensitivity in 15 people with obesity and type 2 diabetes before and after marked (~18%) weight loss; and iii) the effect of endotrophin on insulin signaling (AKTser473 phosporylation) and insulin action (insulin-stimulated glucose uptake) in primary human skeletal muscle myotubes. RESULTS. Plasma endotrophin progressively increased from the Lean-IS to the Obese-IS to the Obese-IR group, was negatively associated with insulin sensitivity and positively associated with factors involved in adipose tissue endotrophin production, namely adipose tissue gene expression of matrix metalloproteinases and markers of hypoxia, inflammation, and fibrosis. Marked weight loss increased insulin sensitivity in conjunction with a decrease in plasma endotrophin concentration. Endotrophin inhibited insulin insulin-stimulated AKTser473 phosphorylation and insulin-stimulated glucose uptake in myotubes, which was restored by incubation with a neutralizing endotrophin antibody. CONCLUSIONS. These results suggest plasma endotrophin is both a biomarker and cause of whole-body insulin resistance in people with obesity.

Authors

Gordon I. Smith, Samuel Klein

Safety and implementation of phase 1 randomized GLA-SE-adjuvanted CH505TF gp120 HIV vaccine trial in newborns

• Text
• PDF

Abstract

BACKGROUND. The neonatal immune system is uniquely poised to generate broadly neutralizing antibodies (bnAbs) and thus infants are ideal for evaluating HIV vaccine candidates. We present the design and safety of a new-in-infants glucopyranosyl lipid A (GLA)-stable emulsion (SE) adjuvant admixed with a first-in-infant CH505 transmitter-founder (CH505TF) gp120 immunogen designed to induce precursors for bnAbs against HIV. METHODS. HVTN 135 is a phase I randomized, placebo-controlled trial of CH505TF+GLA-SE or placebo. Healthy infants aged ≤ 5 days, born to mothers living with HIV but HIV nucleic acid negative at birth were randomized to five doses of CH505TF + GLA-SE or placebo at birth and 8, 16, 32, and 54 weeks. RESULTS. 38 infants (median age = 4 days; interquartile range 4, 4.75 days) were enrolled November 2020 to January 2022. Among 28 (10) infants assigned to receive CH505TF + GLA-SE (placebo), most (32/38) completed the 5-dose immunization series and follow-up (35/38). Solicited local and systemic reactions were more frequent in vaccine (8, 28.6% local; 16, 57.1% systemic) vs. placebo recipients (1, 10% local, P = 0.25; 4, 40.0% systemic, P = 0.38). All events were Grade 1 except two Grade 2 events (pain, lethargy). Serious vaccine-related adverse events were not recorded. CONCLUSIONS. This study illustrates the feasibility of conducting trials of new-in-infants adjuvanted HIV vaccines in HIV-exposed infants receiving standard infant vaccinations. The safety profile of the CH505TF + GLA-SE vaccine was reassuring. TRIAL REGISTRATION. ClinicalTrials.gov NCT04607408. FUNDING. The trial was funded through National Institute of Allergy and Infectious Disease of the National Institutes of Health under grants UM1 AI068614 (HVTN Leadership and Operations Center), UM1 AI068635 (HVTN Statistical and Data Management Center), and UM1 AI068618 (HVTN Laboratory Center).

Authors

Avy Violari, Kennedy Otwombe, William Hahn, Shiyu Chen, Deirdre Josipovic, Vuyelwa Baba, Asimenia Angelidou, Kinga K. Smolen, Ofer Levy, Nonhlanhla N. Mkhize, Amanda S. Woodward Davis, Troy M. Martin, Barton F. Haynes, Wilton B. Williams, Zachary K. Sagawa, James G. Kublin, Laura Polakowski, Margaret Brewinski Isaacs, Catherine Yen, Georgia Tomaras, Lawrence Corey, Holly Janes, Glenda E. Gray

Prefrontal correlates of fear generalization during endocannabinoid depletion

• Text
• PDF

Abstract

Maladaptive fear generalization is one of the hallmarks of trauma-related disorders. The endocannabinoid 2-arachidonoylglycerol (2-AG) is crucial for modulating anxiety, fear, and stress adaptation but its role in balancing fear discrimination versus generalization is not known. To address this, we used a combination of plasma endocannabinoid measurement and neuroimaging from a childhood maltreatment-exposed and non-exposed mixed population combined with human and rodent fear conditioning models. Here we show that 2-AG levels are inversely associated with fear generalization at the behavioral level in both mice and humans. In mice, 2-AG depletion increases the proportion of neurons, and the similarity between neuronal representations, of threat-predictive and neutral stimuli within prelimbic prefrontal cortex neuronal ensembles. In humans, increased dorsolateral prefrontal cortical-amygdala resting state connectivity is inversely correlated with fear generalization. These data provide convergent cross-species evidence that 2-AG is a key regulator of fear generalization and further support the notion that 2-AG deficiency could represent a trauma-related disorder susceptibility endophenotype.

Authors

Luis E. Rosas-Vidal, Saptarnab Naskar, Leah M. Mayo, Irene Perini, Rameen Masroor, Megan Altemus, Liorimar Ramos-Medina, S. Danyal Zaidi, Hilda Engelbrektsson, Puja Jagasia, Markus Heilig, Sachin Patel