Effects of Zonula occludens-1 (ZO-1) tight junction protein on tumor characteristics in human ovarian cancer cells
Ovarian cancer is among the most lethal malignancies affecting women, largely due to its asymptomatic progression in early stages, rapid advancement, and high mortality rate. Tight junction protein 1 (TJP1), also known as Zonula occludens-1 (ZO-1), plays a critical role in epithelial and endothelial cell integrity by regulating paracellular permeability. Additionally, ZO-1 is involved in cell-cell communication networks, influencing cellular proliferation, differentiation, and metastasis. While previous studies have demonstrated the significance of ZO-1 in tumorigenesis and cancer progression, its precise mechanistic role remains to be fully elucidated. This study aims to investigate the functional role of ZO-1 in human ovarian cancer cells to provide a molecular perspective on its impact on tumor progression. Human ovarian cancer cell lines SNU119 and SKOV3 were utilized. ZO-1 knockout (KO) was achieved using the Clustered Regularly Interspaced Short Palindromic Repeats-CRISPR-associated protein 9 (CRISPR-Cas9) system in combination with single-guide RNA (sgRNA) targeting ZO-1. Hygromycin B selection was employed to establish stable ZO-1 KO SNU119 and ZO-1 KO SKOV3 cell lines. The successful knockout of ZO-1 was confirmed at both the transcript and protein levels via real-time quantitative PCR (RT-qPCR) and Western blotting. Functional assays, including cell proliferation, migration, and invasion assays, were conducted to assess the effects of ZO-1 KO on key tumor-associated characteristics. CRISPR-Cas9-mediated ZO-1 KO in SNU119 and SKOV3 ovarian cancer cell lines resulted in a significant reduction of ZO-1 expression at both the transcript and protein levels. The loss of ZO-1 led to a disruption of cell-cell junctions. Functionally, ZO-1 KO cells exhibited reduced proliferation, whereas cell migration and invasion were significantly enhanced, suggesting a shift toward a more aggressive phenotype. The findings indicate that ZO-1 KO in ovarian cancer cells suppresses cell proliferation while promoting migratory and invasive properties, hallmarks of tumor progression. These results underscore the complex role of ZO-1 in ovarian cancer and highlight the need for further investigation into its broader regulatory impact on oncogenic pathways.