胰腺导管腺癌（PDAC）仍然是最难治疗的癌症之一。吉西他滨仍然是PDAC的标准治疗，但生存好处有限且已经报道了抗药性。本研究探索了在PDAC细胞中抑制p21活化激酶4（PAK4）的潜力，PAK4是KRAS致癌通路的下游蛋白质，在与吉西他滨联合应用时的潜力。KPT-9274抑制PAK4导致PDAC细胞中吉西他滨活性显著增强，伴有细胞凋亡、DNA损伤和细胞周期阻滞的增加。在分子水平上，PAK4的抑制剂量依赖性地抑制吉西他滨诱导的β-连环素、c-JUN和核糖核酸还原酶亚单位2（RRM2）水平。PAK4的抑制进一步抑制了磷酸化ERK（p-ERK）水平；吉西他滨诱导的磷酸化AKT（p-AKT），磷酸化和总c-Myc水平。这些结果暗示了β-连环素、p-ERK和p-AKT在通过抑制PAK4增强吉西他滨活性中的作用可能与Wnt/β-连环素、MAPK和PI3K通路的关键效应蛋白有关。我们的数据揭示了PAK4抑制剂与吉西他滨联合治疗PDAC的可能分子机制，这可以通过PAK4的沉默进一步得到确证。我们的发现为在临床前和临床层面上利用吉西他滨和PAK4抑制剂的联合治疗PDAC提供了有力的理论基础。©2023作者。

Pancreatic Ductal Adenocarcinoma (PDAC) remains one of the most difficult to treat cancers. Gemcitabine is still the standard of care treatment for PDAC but with modest survival benefit and well reported resistance. Here we explored potential of inhibiting p21 activated kinase 4 (PAK4), a downstream protein of KRAS oncogenic pathway, in combination with Gemcitabine in PDAC cells. PAK4 inhibition by KPT-9274 led to significant potentiation of Gemcitabine activity in PDAC cells, with an increase in apoptosis, DNA damage and cell cycle arrest. At molecular level, PAK4 inhibition dose dependently inhibited Gemcitabine-induced β-catenin, c-JUN and Ribonucleotide Reductase subunit 2 (RRM2) levels. PAK4 inhibition further inhibited levels of phosphorylated ERK (p-ERK); Gemcitabine-induced phosphorylated AKT (p-AKT), phosphorylated and total c-Myc. These results suggest possible role of β-catenin, p-ERK and p-AKT, key effector proteins of Wnt/β-catenin, MAPK and PI3K pathways respectively, in sensitisation of Gemcitabine activity with PAK4 inhibition. Our data unravel probable molecular mechanisms behind combination of PAK4 inhibition with Gemcitabine to counter PDAC, which may be unequivocally proved further with knock down of PAK4. Our findings provide a strong rationale to exploit the combination therapy of Gemcitabine and PAK4 inhibitor for PDAC at pre-clinical and clinical levels.© 2023 The Authors.