Nucleophagy-Like Ultrastructural Remodeling in 3D Endometrial Carcinoma Spheroids Exposed to Lithium Chloride

Nucleophagy, the selective autophagic degradation of nuclear components, remains poorly characterized in mammalian systems, especially in the context of cancer. Lithium chloride (LiCl) has been reported to modulate cellular stress responses and induce mitophagy-like processes; however, its effects on nuclear architecture have not been clearly defined at the ultrastructural level. Here, we used three-dimensional spheroids of Ishikawa endometrial cancer cells exposed to 10 mM or 50 mM LiCl for up to 96 hours. Cell cycle distribution, BrdU incorporation, and viability were evaluated using flow cytometry and immunohistochemistry, while ultrastructural changes were examined by transmission electron microscopy (TEM). High-dose LiCl (50 mM) induced marked G1/G0 arrest and a sustained decrease in BrdU-positive cells, while Annexin V-FITC/PI staining revealed reduced viability without a proportional increase in apoptotic or necrotic fractions. TEM analysis revealed nuclear envelope elongation, double-membraned vesicles, and cytoplasmic lysis, morphological features that are suggestive of nucleophagy-like remodeling. Notably, preliminary data with 10 mM LiCl revealed early nuclear envelope changes and autophagic vacuole formation, supporting a time- and dose-dependent nuclear response to lithium. It should be emphasized that all findings are descriptive and based solely on ultrastructural (TEM) analysis, without direct molecular validation; therefore, these results should be interpreted as suggestive rather than definitive evidence of nucleophagy. The use of a 3D spheroid model offers a physiologically relevant platform to investigate nuclear remodeling under pharmacological stress. Future studies incorporating molecular markers and loss-of-function approaches will be essential to confirm these observations and assess their clinical relevance in endometrial cancer.