Lys05 – A Promising Autophagy Inhibitor in the Radiosensitization Battle: Phosphoproteomic Perspective

Background: Autophagy is a crucial factor contributing to radioresistance during radiotherapy. Although Lys05 has proven its ability to improve the results of radiotherapy through the inhibition of autophagy, molecular mechanisms of this inhibition remain elusive. We aimed to describe the molecular mechanisms involved in Lys05-induced autophagy inhibition. Materials and Methods: Radioresistant human non-small cell lung carcinoma cells (H1299, p53-negative) and methods of quantitative phosphoproteomics were employed to define the molecular mechanisms involved in Lys05-induced inhibition of autophagy. Results: We confirmed that at an early stage after irradiation, autophagy was induced, whereas at a later stage after irradiation, it was inhibited. The early-stage induction of autophagy was characterized mainly by the activation of biosynthetic and metabolic processes through up- or down-regulation of the critical autophagic regulatory proteins Sequestosome-1 (SQSTM1) and Proline-rich AKT1 substrate 1 (AKT1S1). The late-stage inhibition of autophagy was attributed mainly to down-regulation of Unc-51 like autophagy activating kinase 1 (ULK1) through phosphorylation at Ser638. Conclusion: This work contributes to emerging phosphoproteomic insights into autophagy-mediated global signaling in lung cancer cells, which might consequently facilitate the development of precision medicine therapeutics.

研究背景：自噬（autophagy）是放疗过程中介导辐射抵抗的关键因素。尽管Lys05已被证实可通过抑制自噬提升放疗疗效，但其具体分子机制仍不明晰。本研究旨在阐明Lys05诱导的自噬抑制相关分子机制。材料与方法：本研究采用辐射抵抗型人非小细胞肺癌细胞（H1299，p53阴性）与定量磷酸化蛋白质组学方法，以明确Lys05诱导自噬抑制的分子机制。研究结果：本研究证实，照射后早期阶段自噬被诱导，而照射后晚期阶段自噬则受到抑制。早期阶段的自噬诱导主要通过对关键自噬调控蛋白Sequestosome-1（SQSTM1）与富含脯氨酸的AKT1底物1（Proline-rich AKT1 substrate 1，AKT1S1）的上调或下调，激活生物合成与代谢过程。晚期阶段的自噬抑制则主要归因于Unc-51样自噬激活激酶1（Unc-51 like autophagy activating kinase 1，ULK1）在Ser638位点发生磷酸化，进而导致其表达下调。研究结论：本研究为肺癌细胞中自噬介导的全局信号通路的磷酸化蛋白质组学研究提供了新的见解，或可助力精准医学治疗方案的开发。