Lithium Chloride-Induced Nuclear Envelope Remodeling in 3D Endometrial Cancer Spheroids

Selective remodeling of nuclear architecture under pharmacological stress remains incompletely characterized in three-dimensional cancer models, particularly at the ultrastructural level. Lithium chloride (LiCl) is widely used as a cellular stressor capable of altering membrane organization, proliferation, and organelle dynamics; however, its effects on nucleus-associated structural remodeling in three-dimensional tumor systems remain unclear. In the present study, Ishikawa endometrial carcinoma spheroids were exposed to LiCl (10 or 50 mM) for up to 96 h, and cellular responses were evaluated using cell cycle analysis, 5-bromo-2'-deoxyuridine (BrdU) incorporation, viability assays, and transmission electron microscopy. LiCl exposure was associated with sustained accumulation of cells in the G₀/G₁ phase and suppression of DNA synthesis without evidence of a dominant apoptotic or necrotic response under the examined conditions. Ultrastructural analyses showed prominent nuclear envelope elongation, membrane reorganization, and perinuclear double-membraned structures, particularly under prolonged LiCl exposure. These alterations were observed alongside mitochondrial and endomembrane remodeling, supporting the presence of a broader stress-associated ultrastructural adaptation response within LiCl-treated spheroids. Importantly, the present study is morphology-focused and descriptive in scope. Although some ultrastructural features were morphology-compatible with nucleophagy-associated remodeling, no molecular validation using LC3, p62/SQSTM1, LAMP1/lysosomal colocalization, lamin degradation, or autophagic-flux assays was performed. Therefore, the findings should be interpreted as evidence of stress-associated nuclear envelope remodeling rather than mechanistic proof of nucleophagy. Collectively, this study identifies nucleus-associated ultrastructural remodeling as a prominent cellular response to LiCl-induced stress in 3D endometrial cancer spheroids and highlights the utility of three-dimensional tumor models for investigating stress-related architectural adaptations in cancer cells.