College of Pharmacy, Chongqing Medical University, Chongqing, 400016, People's Republic of China.
Department of Pharmacy, Chongqing University Cancer Hospital, Chongqing, 400030, People's Republic of China.
Cell Mol Biol Lett. 2024 Aug 17;29(1):110. doi: 10.1186/s11658-024-00626-1.
Gastric cancer (GC) is a prevalent malignant tumor, and the RNA-binding protein polypyrimidine tract-binding protein 1 (PTBP1) has been identified as a crucial factor in various tumor types. Moreover, abnormal autophagy levels have been shown to significantly impact tumorigenesis and progression. Despite this, the precise regulatory mechanism of PTBP1 in autophagy regulation in GC remains poorly understood.
To assess the expression of PTBP1 in GC, we employed a comprehensive approach utilizing western blot, real-time quantitative polymerase chain reaction (RT-qPCR), and bioinformatics analysis. To further identify the downstream target genes that bind to PTBP1 in GC cells, we utilized RNA immunoprecipitation coupled with sequencing (si-PTBP1 RNA-seq). To evaluate the impact of PTBP1 on gastric carcinogenesis, we conducted CCK-8 assays, colony formation assays, and GC xenograft mouse model assays. Additionally, we utilized a transmission electron microscope, immunofluorescence, flow cytometry, western blot, RT-qPCR, and GC xenograft mouse model experiments to elucidate the specific mechanism underlying PTBP1's regulation of autophagy in GC.
Our findings indicated that PTBP1 was significantly overexpressed in GC tissues compared with adjacent normal tissues. Silencing PTBP1 resulted in abnormal accumulation of autophagosomes, thereby inhibiting GC cell viability both in vitro and in vivo. Mechanistically, interference with PTBP1 promoted the stability of thioredoxin-interacting protein (TXNIP) mRNA, leading to increased TXNIP-mediated oxidative stress. Consequently, this impaired lysosomal function, ultimately resulting in blockage of autophagic flux. Furthermore, our results suggested that interference with PTBP1 enhanced the antitumor effects of chloroquine, both in vitro and in vivo.
PTBP1 knockdown impairs GC progression by directly binding to TXNIP mRNA and promoting its expression. Based on these results, PTBP1 emerges as a promising therapeutic target for GC.
胃癌（GC）是一种常见的恶性肿瘤，RNA 结合蛋白多嘧啶 tract 结合蛋白 1（PTBP1）已被确定为多种肿瘤类型的关键因素。此外，异常的自噬水平已被证明对肿瘤发生和进展有重大影响。尽管如此，PTBP1 在 GC 中调节自噬的确切调控机制仍知之甚少。
为了评估 PTBP1 在 GC 中的表达，我们采用了综合方法，包括 Western blot、实时定量聚合酶链反应（RT-qPCR）和生物信息学分析。为了进一步鉴定与 GC 细胞中 PTBP1 结合的下游靶基因，我们使用了 RNA 免疫沉淀结合测序（si-PTBP1 RNA-seq）。为了评估 PTBP1 对胃癌发生的影响，我们进行了 CCK-8 测定、集落形成测定和 GC 异种移植小鼠模型测定。此外，我们还利用透射电子显微镜、免疫荧光、流式细胞术、Western blot、RT-qPCR 和 GC 异种移植小鼠模型实验，阐明了 PTBP1 调节 GC 中自噬的具体机制。
我们的研究结果表明，与相邻正常组织相比，PTBP1 在 GC 组织中显著过表达。沉默 PTBP1 导致自噬体异常积累，从而抑制体外和体内 GC 细胞的活力。机制上，干扰 PTBP1 促进了硫氧还蛋白相互作用蛋白（TXNIP）mRNA 的稳定性，导致 TXNIP 介导的氧化应激增加。因此，这会损害溶酶体功能，最终导致自噬流受阻。此外，我们的结果表明，干扰 PTBP1 增强了氯喹在体外和体内的抗肿瘤作用。
PTBP1 敲低通过直接结合 TXNIP mRNA 并促进其表达来损害 GC 进展。基于这些结果，PTBP1 成为 GC 的一个有前途的治疗靶点。
