Otoshi et al. report a genetic background-dependent hyperactive TGF-β/PDGFRA/TNC program unleashed by a brief in utero exposure to a vitamin A/retinoic acid–deficient environment, resulting in structural remodeling of the airway smooth muscle and hyperresponsiveness in adult mice. The cover image shows the aberrant ectopic expansion of PDGFRA (red) where airway smooth muscle emerges in the embryonic lung near distal epithelial buds (SOX9, green) and airway epithelial progenitors (SOX2, cyan).
Jianfei Ji, Wenjing You, Xiaoli Sun, Peng Zhao
Cell metabolic rewiring is associated with resistance to venetoclax-azacitidine (Ven-Aza) combination therapy and relapse in acute myeloid leukemia (AML) patients. Drug-resistant cells exhibit an enhanced reliance on oxidative phosphorylation (OXPHOS) for energy production. Therefore, impairing mitochondrial metabolism represents an exciting strategy to face this unmet clinical need. We recently demonstrated that the specific activation of the phosphatase PP2A-B56α enhances the pro-apoptotic efficacy of venetoclax in AML. Here, through leveraging unbiased multi-omics-based approaches and using both genetic and pharmacological tools, we define key roles for the tumor suppressor PP2A-B56α complex in OXPHOS regulation and treatment response in disease-relevant AML models. From a translational perspective, the specific stabilization of PP2A-B56α heterocomplex with the novel PP2A molecular glue activator, RPT04402, reduces OXPHOS levels in treatment-resistant AML cells and improves treatment response in both Ven-Aza-sensitive and -resistant AML cell lines, primary cells, and in vivo models. Together, our work supports further research on targeted combination therapy approaches based on PP2A-B56α stabilization to counteract OXPHOS-related treatment resistance and improve AML responses in a patient population with historically poor outcomes.
Silvia Romero-Murillo, Irene Peris, Anna Maria Lucianò, Nerea Marcotegui, Carmen Vicente, Brian Tran, Kelsey Barrie, Caitlin M. O'Connor, Andrea Torres-López, Maria C. Mateos, Maria L. Cayuela, Victoriano Mulero, Joaquín Fernández-Irigoyen, Enrique Santamaría, Maria D. Odero, Goutham Narla
Despite advances in treatment approaches for lung cancer, the morbidity and survival of lung cancer patients with malignant pleural effusions (MPE) remain poor. This is in part due to gaps in understanding the role of immune cells in the pleural fluid microenvironment. We performed single cell analysis with flow cytometry validation of CD45+ cells in eight malignant and five benign pleural fluid (BPE) specimens to identify changes in the transcriptomic landscape of immune cells across disease states. We found upregulation of pro-inflammatory signaling pathways, including interferon and TNF signaling, in T cells, B cells, and macrophages in benign compared to malignant pleural effusions. Pro-inflammatory HLA-DR+ macrophages were associated with good survival outcomes while pro-tumorigenic HLA-DR- macrophages with upregulation of angiogenesis, TGFβ, and fibronectin signaling were associated with poor survival outcomes in patients with MPE. We also validated these findings with macrophage cell surface expression markers using flow cytometry in 14 MPE and 7 BPE specimens. Finally, we performed multiplex cytokine analysis which showed enrichment of the type 3 inflammatory cytokine, IL17A, in MPE as a putative mechanism for macrophage reprogramming. These data provide a rich resource for interrogating the immune cell types and states present across the spectrum of pleural disease. They offer not only prognostic value for patient outcomes at the time of pleural fluid collection, but also insights into novel immunotherapy targets.
Aaditya Khatri, Huimin Wang, Zhicheng Ji, Prekshaben Patel, Smita K. Nair, Javid P. Mohammed, Beth H. Shaz, Andrew B. Nixon, Scott M. Palmer, Kamran Mahmood
Activation of the mechanistic target of rapamycin (mTOR) complex1 (mTORC1) promotes muscle protein synthesis, mass, and function. Muscle mTORC1 can be activated by feeding and contraction. Here, muscle mTORC1 signaling, protein synthesis, mass, and function are characterized in a genetic mouse model that separates these two major modes of muscle mTORC1 regulation. AKT signaling is required for feeding-induced muscle mTORC1 signaling and protein synthesis, and mice expressing a mutant of tuberous sclerosis complex 2 (TSC2) that cannot be phosphorylated by AKT specifically in skeletal muscle (SkM-TSC2-5A) attenuate these effects of feeding. Despite this loss of postprandial protein synthesis, SkM-TSC2-5A mice have similar muscle and myofiber size compared to SkM-TSC2-WT mice. SkM-TSC2-5A mice maintain normal muscle mTORC1 activation in response to contraction and exhibit no differences in atrophy-related gene expression or ribosomal content. SkM-TSC2-5A mice exhibit improved maximal endurance capacity without changes in muscle contractile function. This phenotype occurs without alterations in muscle glycogen content or myofiber type but does coincide with a modest increase in muscle mitochondrial content. Therefore, AKT-mediated phosphorylation of TSC2 is required for postprandial mTORC1 activation and the induction of protein synthesis; however, these are dispensable for the development and maintenance of muscle mass in sedentary mice.
Samuel C. Lapp, Krystle C. Kalafut, Madi Y. Cissé, Khaled Tighanimine, Dean M. Rosenthal, Will Doxsey, Sheng Hui, Karen E. Inouye, Claire E. Morrow, Yann Cormerais, Brendan D. Manning
Dysfunctional tumor vessels promote disease progression, whereas improved function enhances therapeutic delivery. However, current approaches to normalize tumor vasculature have limited efficacy. In vascular malformations, vessels are similarly dysfunctional, with endothelial cell (EC) hyperproliferation impairing arterial-venous specification. These defects are corrected with palbociclib, a cyclin-dependent kinase 4/6 inhibitor (CDK4/6i) that has beneficial effects on tumor and immune cells, but the effects on tumor vasculature are not well characterized. In our studies, murine mammary tumor ECs (TECs) exhibited disrupted cell cycle and specification, and CDK4/6i promoted TEC cycle control, enabling improved tumor vascular function. To investigate transcriptomic changes, we performed single-cell RNA sequencing (scRNAseq) of treated and untreated tumors, and healthy tissues. CDK4/6i-mediated TEC cycle arrest promoted arterial-venous specification, cellular junctions, and pericyte association, and suppressed glycolytic and immunosuppressive gene expression. These effects were associated with increased vessel perfusion, decreased tumor hypoxia, and a more favorable immune landscape with immunotherapy. In scRNAseq datasets from patients treated long-term with CDK4/6i, TECs exhibited similar transcriptomic changes associated with arterial-venous specification, pericyte recruitment, and immune signaling. Thus, in contrast to current strategies, CDK4/6i-mediated vascular changes may be maintained with continued treatment, highlighting the relevance of modulating TEC cycle to improve vessel maturation/function.
Shelby R. Cain, Gael Genet, Nafiisha Genet, Jordon W. Aragon, Madeline G. Jackson, Victoria M. Milosek, Mark R. Schwartz, Umadevi Paila, Aleksandra Cwiek, Zaneta Markowska, Nicholas W. Chavkin, Richard J. Price, Andrew C. Dudley, Karen K. Hirschi