Clinical Research and Lab Center, Affiliated Kunshan Hospital of Jiangsu University, Kunshan, China.
General Surgery, Cancer Center, Department of Colorectal Surgery, Zhejiang Provincial People's Hospital, Hangzhou, China.
Cell Death Dis. 2024 Sep 30;15(9):699. doi: 10.1038/s41419-024-07079-6.
The increasing mortality rate of pancreatic cancer globally necessitates the urgent identification for novel therapeutic targets. This study investigated the expression, functions, and mechanistic insight of G protein inhibitory subunit 3 (Gαi3) in pancreatic cancer. Bioinformatics analyses reveal that Gαi3 is overexpressed in human pancreatic cancer, correlating with poor prognosis, higher tumor grade, and advanced classification. Elevated Gαi3 levels are also confirmed in human pancreatic cancer tissues and primary/immortalized cancer cells. Gαi3 shRNA or knockout (KO) significantly reduced cell viability, proliferation, cell cycle progression, and mobility in primary/immortalized pancreatic cancer cells. Conversely, Gαi3 overexpression enhanced pancreatic cancer cell growth. RNA-sequencing and bioinformatics analyses of Gαi3-depleted cells indicated Gαi3's role in modulating the Akt-mTOR and PKA-Hippo-YAP pathways. Akt-S6 phosphorylation was decreased in Gαi3-depleted cells, but was increased with Gαi3 overexpression. Additionally, Gαi3 depletion elevated PKA activity and activated the Hippo pathway kinase LATS1/2, leading to YAP/TAZ inactivation, while Gαi3 overexpression exerted the opposite effects. There is an increased binding between Gαi3 promoter and the transcription factor TCF7L2 in pancreatic cancer tissues and cells. Gαi3 expression was significantly decreased following TCF7L2 silencing, but increased with TCF7L2 overexpression. In vivo, intratumoral injection of Gαi3 shRNA-expressing adeno-associated virus significantly inhibited subcutaneous pancreatic cancer xenografts growth in nude mice. A significant growth reduction was also observed in xenografts from Gαi3 knockout pancreatic cancer cells. Akt-mTOR inactivation and increased PKA activity coupled with YAP/TAZ inactivation were also detected in xenograft tumors upon Gαi3 depletion. Furthermore, bioinformatic analysis and multiplex immunohistochemistry (mIHC) staining on pancreatic cancer tissue microarrays showed a reduced proportion of M1-type macrophages and an increase in PD-L1 positive cells in Gαi3-high pancreatic cancer tissues. Collectively, these findings highlight Gαi3's critical role in promoting pancreatic cancer cell growth, potentially through the modulation of the Akt-mTOR and PKA-Hippo-YAP pathways and its influence on the immune landscape.
全球范围内胰腺癌的死亡率不断上升，迫切需要寻找新的治疗靶点。本研究探讨了 G 蛋白抑制亚单位 3（Gαi3）在胰腺癌中的表达、功能和作用机制。生物信息学分析显示，Gαi3 在人胰腺癌中过表达，与预后不良、肿瘤分级高和分类进展相关。在人胰腺癌组织和原代/永生化癌细胞中也证实了 Gαi3 水平升高。Gαi3 shRNA 或敲除（KO）显著降低了原代/永生化胰腺癌细胞的活力、增殖、细胞周期进程和迁移。相反，Gαi3 过表达增强了胰腺癌细胞的生长。Gαi3 耗竭细胞的 RNA 测序和生物信息学分析表明，Gαi3 在调节 Akt-mTOR 和 PKA-Hippo-YAP 通路中发挥作用。Gαi3 耗竭细胞中 Akt-S6 磷酸化减少，但 Gαi3 过表达时增加。此外，Gαi3 耗竭增加了 PKA 活性并激活了 Hippo 通路激酶 LATS1/2，导致 YAP/TAZ 失活，而 Gαi3 过表达则产生相反的效果。在胰腺癌组织和细胞中，Gαi3 启动子与转录因子 TCF7L2 之间的结合增加。沉默 TCF7L2 后，Gαi3 表达显著降低，但过表达 TCF7L2 后增加。在体内，Gαi3 shRNA 表达的腺相关病毒的肿瘤内注射显著抑制了裸鼠皮下胰腺癌异种移植物的生长。Gαi3 敲除胰腺癌细胞的异种移植物也观察到明显的生长减少。在 Gαi3 耗竭的异种移植瘤中还检测到 Akt-mTOR 失活和 PKA 活性增加以及 YAP/TAZ 失活。此外，对胰腺癌组织微阵列的生物信息学分析和多重免疫组化（mIHC）染色显示，Gαi3 高表达的胰腺癌组织中 M1 型巨噬细胞比例降低，PD-L1 阳性细胞增加。总之，这些发现强调了 Gαi3 在促进胰腺癌细胞生长中的关键作用，可能是通过调节 Akt-mTOR 和 PKA-Hippo-YAP 通路及其对免疫景观的影响。
