Oxidative stress-triggered Wnt signaling perturbation characterizes the tipping point of lung adeno-to-squamous transdifferentiation

Lkb1 deficiency confers the Kras-mutant lung cancer with strong plasticity and the potential for adeno-to-squamous transdifferentiation(AST).However,it remains largely unknown how Lkb1 deficiency dynamically regulates AST.Using the classical AST mouse model(Kras LSL-G12D/+;Lkb1flox/flox,KL),we here comprehensively analyze the temporal transcriptomic dynamics of lung tumors at different stages by dynamic network biomarker(DNB)and identify the tipping point at which the Wnt signaling is abruptly suppressed by the excessive accumulation of reactive oxygen species(ROS)through its downstream effector FOXO3A.Bidirectional genetic perturbation of the Wnt pathway using two different Ctnnb1 conditional knockout mouse strains confirms its essential role in the negative regulation of AST.Importantly,pharmacological activation of the Wnt pathway before but not after the tipping point inhibits squamous transdifferentiation,highlighting the irreversibility of AST after crossing the tipping point.Through comparative transcriptomic analyses of mouse and human tumors,we find that the lineage-specific transcription factors(TFs)of adenocarcinoma and squamous cell carcinoma form a“Yin-Yang”counteracting network.Interestingly,inactivation of the Wnt pathway preferentially suppresses the adenomatous lineage TF network and thus disrupts the“Yin-Yang”homeostasis to lean towards the squamous lineage,whereas ectopic expression of NKX2-1,an adenomatous lineage TF,significantly dampens such phenotypic transition accelerated by the Wnt pathway inactivation.The negative correlation between the Wnt pathway and AST is further observed in a large cohort of human lung adenosquamous carcinoma.Collectively,our study identifies the tipping point of AST and highlights an essential role of the ROS-Wnt axis in dynamically orchestrating the homeostasis between adeno-and squamous-specific TF networks at the AST tipping point.

MAPK signaling in inflammation-associated cancer development

Mitogen-activated protein(MAP)kinases comprise a family of protein-serine/threonine kinases,which are highly conserved in protein structures from unicellular eukaryotic organisms to multicellular organisms,including mammals.These kinases,including ERKs,JNKs and p38s,are regulated by a phosphorelay cascade,with a prototype of three protein kinases that sequentially phosphorylate one another.MAPKs transduce extracellular signals into a variety of cellular processes,such as cell proliferation,survival,death,and differentiation.Consistent with their essential cellular functions,MAPKs have been shown to play critical roles in embryonic development,adult tissue homeostasis and various pathologies.In this review,we discuss recent findings that reveal the profound impact of these pathways on chronic inflammation and,particularly,inflammation-associated cancer development.

mTOR regulates TLR-induced c-fos and Th1 responses to HBV and HCV vaccines

Although IL-12 plays a critical role in priming Th1 and cytotoxic T lymphocyte(CTL) responses, Toll-like receptor(TLR) signaling only induces low amounts of IL-12 in dendritic cells and macrophages, implying the existence of stringent regulatory mechanisms. In this study, we sought to uncover the mechanisms underlying TLR-induced IL-12 expression and the Th1 response. By systemic screening, we identified a number of protein kinases involved in the regulation of TLRinduced IL-12 expression. In particular, PI3 K, ERK, and m TOR play critical roles in the TLR-induced Th1 response by regulating IL-12 and IL-10 production in innate immune cells. Moreover, we identified c-fos as a key molecule that mediates m TOR-regulated IL-12 and IL-10 expression in TLR signaling. Mechanistically, m TOR plays a crucial role in c-fos expression, thereby modulating NFκB binding to promoters of IL-12 and IL-10. By controlling the expression of a special innate gene program, m TOR can specifically regulate the TLR-induced T cell response in vivo. Furthermore, blockade of m TOR by rapamycin efficiently boosted TLR-induced antigen-specific T and B cell responses to HBV and HCV vaccines. Taken together, these results reveal a novel mechanism through which m TOR regulates TLR-induced IL-12 and IL-10 production, contributing new insights for strategies to improve vaccine efficacy.

Progress in human liver organoids

Understanding the development,regeneration,and disorders of the liver is the major goal in liver biology.Current mechanistic knowledge of human livers has been largely derived from mouse models and cell lines,which fall short in recapitulating the features of human liver cells or the structures and functions of human livers.Organoids as an in vitro system hold the promise to generate organ-like tissues in a dish.Recent advances in human liver organoids also facilitate the understanding of the biology and diseases in this complex organ.Here we review the progress in human liver organoids,mainly focusing on the methods to generate liver organoids,their applications,and possible future directions.

Recent advances in tissue stem cells

Stem cells are undifferentiated cells capable of self-renewal and differentiation,giving rise to specialized functional cells.Stem cells are of pivotal importance for organ and tissue development,homeostasis,and injury and disease repair.Tissue-specific stem cells are a rare population residing in specific tissues and present powerful potential for regeneration when required.They are usually named based on the resident tissue,such as hematopoietic stem cells and germline stem cells.This review discusses the recent advances in stem cells of various tissues,including neural stem cells,muscle stem cells,liver progenitors,pancreatic islet stem/progenitor cells,intestinal stem cells,and prostate stem cells,and the future perspectives for tissue stem cell research.

RePhine: An Integrative Method for Identification of Drug Response-related Transcriptional Regulators

Transcriptional regulators(TRs)participate in essential processes in cancer pathogenesis and are critical therapeutic targets.Identification of drug response-related TRs from cell line-based compound screening data is often challenging due to low m RNA abundance of TRs,protein modifications,and other confounders(CFs).In this study,we developed a regression-based pharmacogenomic and Ch IP-seq data integration method(Re Phine)to infer the impact of TRs on drug response through integrative analyses of pharmacogenomic and Ch IP-seq data.Re Phine was evaluated in simulation and pharmacogenomic data and was applied to pan-cancer datasets with the goal of biological discovery.In simulation data with added noises or CFs and in pharmacogenomic data,Re Phine demonstrated an improved performance in comparison with three commonly used methods(including Pearson correlation analysis,logistic regression model,and gene set enrichment analysis).Utilizing Re Phine and Cancer Cell Line Encyclopedia data,we observed that Re Phinederived TR signatures could effectively cluster drugs with different mechanisms of action.Re Phine predicted that loss-offunction of EZH2/PRC2 reduces cancer cell sensitivity toward the BRAF inhibitor PLX4720.Experimental validation confirmed that pharmacological EZH2 inhibition increases the resistance of cancer cells to PLX4720 treatment.Our results support that Re Phine is a useful tool for inferring drug response-related TRs and for potential therapeutic applications.The source code for Re Phine is freely available at https://github.com/coexps/Re Phine.