These findings support a model in which normal-like cells tolerate oncogenic mutations not because most cells fail to respond, but because a p53-independent, cell-intrinsic barrier limits the stabilization of malignant transformation following a transient period of heightened plasticity.
Abstract
Normal tissues frequently harbor oncogenic mutations without progressing to cancer, but the cellular basis of this resistance remains poorly defined. We asked whether transformation requires selection of a rare, permissive state within normal-like cell populations. Dermal fibroblasts and mammary epithelial cells responded uniformly to combined HRAS-G12V expression and p53 disruption. Cellular barcoding revealed no loss or enrichment of clones during morphological transformation, arguing against clonal selection as the primary driver of neoplastic reprogramming. Instead, all transduced cells underwent an early, shared transcriptional transition characterized by loss of differentiation markers, induction of RAS-associated and inflammatory programs, activation of alternative-lineage signatures, increased single-cell entropy, and chromatin decondensation. These changes were transient: entropy and chromatin accessibility subsequently declined, and some cells moved toward the control transcriptional state, whereas others stabilized in altered states. The two lineages followed distinct trajectories. Fibroblasts showed greater initial transcriptional plasticity but subsequently reverted more strongly toward the normal state, whereas epithelial cells changed more gradually and continued to diverge from it, suggesting a stronger barrier to transformation in the mesenchymal lineage. Thus, oncogenic perturbation initiated reprogramming throughout the population but did not uniformly produce a stable transformed state. Together, these findings support a model in which normal-like cells tolerate oncogenic mutations not because most cells fail to respond, but because a p53-independent, cell-intrinsic barrier limits the stabilization of malignant transformation following a transient period of heightened plasticity. This framework may facilitate the identification of mechanisms that constrain tumor initiation.. Significance Statement Loss of TP53 and activation of oncogenic RAS are common drivers of human cancer and frequently coexist in the same tumor. Nevertheless, these alterations often fail to induce malignant transformation. To investigate why, we introduced both alterations into fibroblasts and epithelial cells and tracked their responses using clonal barcoding, single-cell transcriptomics, and phenotypic assays. Initially, cells uniformly reprogrammed their transcriptional and chromatin states without detectable clonal selection. They then diverged: some reacquired transcriptional profiles resembling those of the original normal cells, whereas others became transformed. Thus, normal cells resist transformation through an intrinsic barrier that operates despite p53 disruption. Because this transition is transient and reversible, it provides a tractable window for studying the earliest stages of cancer development.
This review evaluating how the antagonistic interplay between Polycomb and Trithorax complexes, chromatin modifier activity, and enhancer reprogramming affects lineage identity and enables multi-lineage plasticity in cancer underscores epigenetic deregulation as a primary driver of lineage plasticity and intratumoral heterogeneity.
Ezgi Boyvatlı, Burcu Akman, E. Bağırsakçı et al.· FEBS Letters· 0 citations
The immortalized non-tumorigenic breast epithelial cell line (MCF10A) develops neoplastic clones under fluctuating conditions in-vitro that mimic the harsh tumor microenvironment and is identified as a potential therapeutic target against epithelial-mesenchymal plasticity and metastatic spread in breast cancer.
Erez Persi, Rafael R. Canevarolo, P. Sudalagunta et al.· Research Square· 1 citation
Lineage plasticity has emerged as a central mechanism through which cancer cells adapt to therapeutic pressure, evade immune surveillance, and acquire aggressive phenotypes. Although recognized across tumor types, the regulatory principles governing how cancer cells reprogram cellular identity remain incompletely understood. In this review, we propose that lineage plasticity in cancer reflects the redeployment of regulatory frameworks established during normal development. Rather than representing a stochastic byproduct of genomic instability, cancer plasticity frequently unfolds within gene regulatory architectures that also govern cell fate specification, lineage commitment, and controlled state transitions during embryogenesis and tissue homeostasis. Developmental transcription factors, including members of the SOX family, FOXA1, ASCL1, NKX2-1, and epithelial-mesenchymal transition regulators, function as lineage gatekeepers during development but are repurposed in cancer to destabilize lineage commitment and enable phenotypic switching. Similarly, epigenetic regulators that guide developmental trajectories, including chromatin remodeling complexes, Polycomb group proteins, and DNA methylation machinery, are frequently dysregulated or redistributed in tumors, altering the repression of lineage-stabilizing and alternative lineage programs and thereby weakening epigenetic barriers to lineage transitions. Together, these observations support a model in which development and cancer operate as mirror regulatory systems: one establishing and stabilizing cellular identity, the other exploiting the same regulatory architecture to permit adaptive reprogramming under selective pressure. We further discuss how emerging single-cell and spatial multi-omics technologies, integrated with artificial intelligence-based modeling, enable mapping of cell state landscapes and transitional trajectories, transforming lineage plasticity from a descriptive phenomenon into a measurable and predictable property of tumor evolution.
Melanie Fraidenburg, Longjun Li, Rosa Kwon et al.· Cancer Letters· 0 citations
Breast cancer is a heterogeneous disease in which a single oncogenic driver can give rise to divergent tumor phenotypes. How oncogenic mutations generate epithelial state plasticity and coordinately remodel the surrounding tissue remains incompletely understood. Here, we applied longitudinal single cell RNA-sequencing to trace the mammary landscape during Pik3caH1047R-driven tumor progression in the mouse. We identify an expansion of the epithelial transcriptional state space, in which luminal cells lose lineage fidelity and activate ciliated, basal, and squamous-like gene expression programs. While oncogene-expressing cells lose features of luminal identity, they retain expression of hormone-sensing genes such as Esr1, Pgr, and Foxa1. These transcriptional states are established early, and the transition to overt tumors is marked by the emergence of cancer-associated fibroblasts rather than new epithelial states. We identify a Postn+ fibroblast population enriched at the epithelial interface as a candidate progenitor of cancer-associated fibroblasts. Postn+ fibroblasts express an ECM-remodeling program and display altered epithelial crosstalk in oncogenic glands. Altogether, Pik3caH1047R activation initiates a tissue-level process beginning with epithelial lineage infidelity, followed by an altered stromal microenvironment, which together mark tumor initiation.
Jennifer T. Le, Eun K. Kim, Vasudha Srivastava et al.· bioRxiv· 0 citations
It is proposed that integrating precise editing, in vivo screening, single-cell multi-omics, and emerging artificial intelligence (AI)-assisted design may provide information and a design basis for future combined strategies that simultaneously target vulnerabilities in senescent cells and malignant populations.
Bo Fan, Aiwei Wu, Xue Pan et al.· Ageing and Cancer Research &...· 0 citations
There is broad consensus that the malignant epithelial cells of human pancreatic ductal adenocarcinoma (PDA) comprise multiple, molecularly distinct states. Yet precise characterization of how these are regulated-including their mechanistic determinants, dependencies, plasticity and functional properties-remains elusive. Single-cell master regulator (MR) analysis of multiple PDA cohorts identified malignant cells in three co-existing, molecularly distinct developmental lineage states, with distinct histopathological morphologies and spatial architecture. These include a poorly differentiated lineage driven by epithelial-mesenchymal-transition-related MRs and two well-differentiated states driven by gastrointestinal epithelial development and pancreatic development MRs, respectively. Furthermore, each state comprises two epigenetically distinct substates with low versus high MAPK signaling activity. Barcode-based lineage tracing confirmed both spontaneous and treatment-dependent cross-state plasticity. Furthermore, loss-of-function studies confirmed state-specific MR essentiality, while their ectopic expression effectively reprogrammed cell state, in vitro and in vivo, thus providing a mechanism-based foundation for PDA heterogeneity and a roadmap for pharmacological targeting.
P. Laise, Mikko M. Turunen, Álvaro Curiel-García et al.· Nature Genetics· 0 citations
