Silencing of β-TrCP2 Suppresses Growth and G1/S Cell Cycle Progression in Non-small Cell Lung Carcinoma Cells

초록

Background/Aim: Aberrant cell cycle progression is a hallmark of non-small cell lung cancer (NSCLC) and remains a major driver of uncontrolled tumor growth. β-Transducin repeat-containing protein 2 (β-TrCP2), a substraterecognition component of an E3 ubiquitin ligase complex, has been implicated in diverse cellular processes; however, its role in NSCLC progression is not fully understood. This study aimed to investigate the functional significance of β-TrCP2 in NSCLC cell proliferation and cell cycle regulation. Materials and Methods: β-TrCP2 was silenced using small interfering RNA (siRNA) in human non-small cell lung cancer (NSCLC) cell lines (A549, H1299, and H460). Cell proliferation was assessed by CCK-8 and colony formation assays. Cell-cycle distribution was analyzed by BrdU/7-AAD flow cytometry. Cell migration was evaluated using woundhealing and Transwell assays. Expression of cell cycle–related genes and proteins was examined by quantitative realtime PCR and western blotting. Subcellular localization of E2F transcription factor 4 (E2F4) was assessed by nuclear fractionation and immunofluorescence. Results: Silencing of β-TrCP2 significantly suppressed proliferation in A549 and H1299 cell lines and reduced migratory capacity in A549 cells. β-TrCP2 depletion induced a pronounced G1/S cell cycle arrest, accompanied by downregulation of S-phase kinase-associated protein 2 (Skp2), accumulation of the cyclin-dependent kinase (CDK) inhibitors p21 (CDKN1A) and p27 (CDKN1B), and reduced phosphorylation of retinoblastoma protein (Rb). These changes were indicative of attenuated CDK activity. In parallel, β-TrCP2 knockdown led to increased accumulation of E2F4 in both cytoplasmic and nuclear fractions. Conclusion: These findings identify β-TrCP2 as a critical regulator of NSCLC cell lines, A549 and H1299 proliferation by coordinating G1/S cell cycle progression. Targeting β-TrCP2 may represent a potential therapeutic strategy for NSCLC by disrupting cancer cell cycle control mechanisms.

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