폐암 세포에서 복제 단백질 A1 유비퀴틴화를 통한 포스포메발론산 키나아제 녹다운의 방사선 민감도 증진 효과 분석

Abstract

Purpose: To evaluate phosphomevalonate kinase (PMVK) as a radiosensitizing target and identify its mechanism of action Materials and Methods: Human kinase siRNA library screening was done to identify PMVK as a novel radiosensitizing target. To confirm the effect of PMVK knockdown on radiosensitivity, lung cancer cells were transfected with siRNAs against PMVK or the control siRNA. Changes in the γH2AX protein levels were evaluated to confirm the impact of PMVK knockdown on DNA double-strand breakage. To check the mechanisms of radiosensitivity, an investigation for the modulations of nonhomologous end joining (NHEJ) and homologous recombination (HR) factors after PMVK knockdown was done. A tumor growth delay experiment was conducted using a mouse model. Results: The reduction in cell viability and survival rates in lung cancer cell lines following PMVK knockdown had a notable impact when combined with radiation therapy (RT). Specifically, RT led to an increase in apoptosis, DNA damage, and the arrest of cells in the G2/M phase after PMVK knockdown. Furthermore, PMVK knockdown heightened the cells' sensitivity to radiation by impeding the HR DNA repair pathway, primarily by decreasing the levels of Replication Protein A1 (RPA1) through the ubiquitin-proteasome system. This radiosensitizing effect of PMVK was validated in an in vivo setting using a stable shRNA PMVK mouse xenograft model. Additionally, the study revealed that PMVK expression was elevated in lung cancer tissues, and this increase was significantly associated with both patient survival and the likelihood of cancer recurrence. Conclusion: PMVK knockdown enhances radiosensitivity via an impaired HR repair pathway by RPA1 ubiquitination in lung cancer. This suggests that PMVK knockdown might be an effective therapeutic strategy to improve the efficacy of RT. Keywords: Lung cancer, Phosphomevalonate kinase, Radiosensitivity, Replication protein A1, Ubiquitination