Piperlongumine (PL) is an alkaloid that inhibits glutathione S-transferase pi 1 (GSTP1) activity, resulting in elevated reactive oxygen species (ROS) levels and cancer-selective cell death. We aimed to identify stress-associated molecular responses to PL treatment in pancreatic ductal adenocarcinoma (PDAC) cells. GSTP1 directly interacts with JNK, which is activated by oxidative stress and can lead to decreased cancer cell proliferation and cell death. Therefore, we hypothesized that JNK pathways are activated in response to PL treatment. Our results show PL causes dissociation of GSTP1 from JNK; robust JNK, c-Jun, and early ERK activation followed by suppression; increased expression of cleaved caspase-3 and cleaved PARP; and nuclear translocation of Nrf2 and c-Myc in PDAC cells. Gene expression analysis revealed PL caused a > 20-fold induction of heme oxygenase-1 (HO-1), which we hypothesized was a survival mechanism for PDAC cells under enhanced oxidative stress. HO-1 knockout resulted in enhanced PL-induced PDAC cell death under hypoxic conditions. Similarly, high concentrations of the HO-1 inhibitor, ZnPP (10 µM), sensitized PDAC cells to PL; however, lower concentrations ZnPP (10 nM) and high or low concentrations of SnPP both protected PDAC cells from PL-induced cell death. Interestingly, the JNK inhibitor significantly blocked PL-induced PDAC cell death, Nrf-2 nuclear translocation, and HMOX-1 mRNA expression. Collectively, the results demonstrate JNK signaling contributes to PL-induced PDAC cell death, and at the same time, activates Nrf-2 transcription of HMOX-1 as a compensatory survival mechanism. These results suggest that elevating oxidative stress (using PL) while at the same time impairing antioxidant capacity (inhibiting HO-1) may be an effective therapeutic approach for PDAC.

中文翻译：

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JNK抑制作用阻断了哌仑米定诱导的胰腺癌细胞死亡和血红素加氧酶-1的转录激活。

Piperlongumine（PL）是一种生物碱，可抑制谷胱甘肽S-转移酶pi 1（GSTP1）活性，从而导致活性氧（ROS）水平升高和癌症选择性细胞死亡。我们旨在鉴定胰腺导管腺癌（PDAC）细胞中PL治疗的应激相关分子反应。GSTP1直接与JNK相互作用，JNK被氧化应激激活，并可能导致癌细胞增殖减少和细胞死亡。因此，我们假设JNK通路响应PL治疗而被激活。我们的结果表明PL导致JNK分离GSTP1；强大的JNK，c-Jun和早期ERK激活，然后被抑制；裂解的caspase-3和裂解的PARP的表达增加；和Nrf2和c-Myc在PDAC细胞中的核易位。基因表达分析显示PL引起> 我们假设血红素加氧酶-1（HO-1）的20倍诱导是PDAC细胞在增强的氧化应激下的存活机制。HO-1敲除导致缺氧条件下增加的PL诱导PDAC细胞死亡。同样，高浓度的HO-1抑制剂ZnPP（10 µM）使PDAC细胞对PL敏感。但是，较低浓度的ZnPP（10 nM）和高浓度或低浓度的SnPP均可保护PDAC细胞免于PL诱导的细胞死亡。有趣的是，JNK抑制剂显着阻断了PL诱导的PDAC细胞死亡，Nrf-2核易位和HMOX-1 mRNA表达。总体而言，结果表明JNK信号传导有助于PL诱导的PDAC细胞死亡，同时激活HMOX-1的Nrf-2转录作为补偿性生存机制。