Hypoxia Promotes Early Tumorigenesis through Dynamical-Mechanical Balance and Genetic Instability

Abstract

Understanding early tumor formation provides insights for cancer prevention. However, in vivo studies focus on later stages, leaving initial tumorigenesis poorly understood. Hypoxia is a key microenvironmental factor in cancer, yet its impact on single-cell tumor initiation and dynamics remains unclear. To address this, we developed an integrated live-imaging platform for hypoxic conditions, enabling first direct observation of 3D tumor spheroid development from a single cell. We show hypoxia accelerates tumorigenesis. Beyond growth, directional movement promotes spheroid fusion. This is driven by optimized actin polymerization and cell-cell adhesion. Hypoxia induces specialized, fusion-competent cells with outstretched F-actin and tiny nuclei that bridge spheroids. Concurrently, hypoxia triggers genetic instability, evidenced by tiny nuclei and aneuploidy. The interplay between dynamic and genetic instability optimizes spheroid mechanical properties, creating a positive feedback loop fuels proliferation. Our findings offer insight into hypoxias role in early tumorigenesis and highlight potential of targeting dynamic-genetic balance for prevention. Statement of SignificanceHypoxia accelerates early tumorigenesis by promoting directional 3D tumor spheroid fusion via optimized actin dynamics and mechanical balance, while inducing micronuclei formation and aneuploidy-linked genetic instability, forming a positive feedback loop that boosts proliferation and malignant progression.