lncRNA-PLACT1 sustains activation of NF-κB pathway through a positive feedback loop with IκBα/E2F1 axis in pancreatic cancer.
LncRNA-PLACT1 在胰腺癌中通过 i κ b α/E2F1 轴的正反馈回路维持 NF-κ b 通路的激活。
- 作者列表："Ren X","Chen C","Luo Y","Liu M","Li Y","Zheng S","Ye H","Fu Z","Li M","Li Z","Chen R
BACKGROUND:The activation of NF-κB signaling pathway is regarded as the dominant process that correlates with tumorigenesis. Recently, increasing evidence shows that long noncoding RNAs (lncRNAs) play crucial roles in sustaining the NF-κB signaling pathway. However, the underlying mechanisms have not yet been elucidated. METHODS:The expression and clinical features of PLACT1 were analyzed in a 166-case cohort of PDAC by qRT-PCR and in situ hybridization. The functional role of PLACT1 was evaluated by both in vitro and in vivo experiments. Chromatin isolation by RNA purification assays were utilized to examine the interaction of PLACT1 with IκBα promoter. RESULTS:We identified a novel lncRNA-PLACT1, which was significantly upregulated in tumor tissues and correlated with progression and poor survival in PDAC patients. Moreover, PLACT1 promoted the proliferation and invasion of PDAC cells in vitro. Consistently, PLACT1 overexpression fostered the progression of PDAC both in orthotopic and lung metastasis mice models. Mechanistically, PLACT1 suppressed IκBα expression by recruiting hnRNPA1 to IκBα promoter, which led to increased H3K27me3 that decreased the transcriptional level of IκBα. Furthermore, E2F1-mediated overexpression of PLACT1 modulated the progression of PDAC by sustained activation of NF-κB signaling pathway through forming a positive feedback loop with IκBα. Importantly, administration of the NF-κB signaling pathway inhibitor significantly suppressed PLACT1-induced sustained activation of NF-κB signaling pathway, leading to reduced tumorigenesis in vivo. CONCLUSIONS:Our findings suggest that PLACT1 provides a novel epigenetic mechanism involved in constitutive activation of NF-κB signaling pathway and may represent a new therapeutic target of PDAC.
背景: NF-κ b 信号通路的激活被认为是与肿瘤发生相关的主导过程。最近，越来越多的证据表明，长链非编码 rna (lncRNAs) 在维持 NF-κ b 信号通路中起着至关重要的作用。然而，潜在的机制尚未阐明。 方法: 采用 qRT-PCR 和原位杂交技术，分析 166 例 PDAC 病例队列中 PLACT1 的表达和临床特征。通过体外和体内实验评价 PLACT1 的功能作用。利用 RNA 纯化试验进行染色质隔离，检测 PLACT1 与 i κ b α 启动子的相互作用。 结果: 我们发现了一种新的 lncRNA-PLACT1，它在肿瘤组织中显著上调，并与 PDAC 患者的进展和不良生存期相关。此外，PLACT1 在体外促进 PDAC 细胞的增殖和侵袭。一致地，PLACT1 过表达在原位和肺转移小鼠模型中均促进了 PDAC 的进展。机制上，PLACT1 通过招募 hnRNPA1 到 i κ b α 启动子抑制 i κ b α 表达，导致 H3K27me3 增加，降低 i κ b α 的转录水平。此外，E2F1-mediated PLACT1 过表达通过与 i κ b α 形成正反馈环路，通过持续激活 NF-κ b 信号通路调节 PDAC 的进展。重要的是，给予 NF-κ b 信号通路抑制剂显著抑制 PLACT1-induced NF-κ b 信号通路的持续激活，导致体内肿瘤发生减少。 结论: 我们的研究结果表明，PLACT1 提供了一种参与 NF-κ b 信号通路组成性激活的新的表观遗传机制，可能代表了 PDAC 的一个新的治疗靶点。
METHODS::Pancreatic ductal adenocarcinoma (PDAC) is a disease of aging. The TP53 gene product regulates cell growth, aging, and cancer. To determine the important targets of TP53 in PDAC, we examined the expression of 440 proteins on a reverse phase protein array (RPPA) in PDAC-derived MIA-PaCa-2 cells which either had WT-TP53 or lacked WT-TP53. MIA-PaCa-2 cells have a TP53 mutation as well as mutant KRAS and represent a good in vitro model to study PDAC. RPPA analysis demonstrated expression of tumor promoting proteins in cells that lacked WT-TP53; and this feature could be reversed significantly when the cells were transfected with vector encoding WT-TP53 or treated with berberine or a modified berberine (BBR). Expression of miR-34a-associated signaling was elevated in cells expressing WT-TP53 compared to cells expressing mTP53. Results from in vivo studies using human PDAC specimens confirmed the in vitro results as the expression of miR-34a and associated signaling was significantly decreased in PDAC specimens compared to non-cancerous tissues. This study determined SERPINE1 as a miR-34a target with relevance to the biology of PDAC. Thus, we have identified a key target (SERPINE1) of the TP53/miR-34a axis that may serve as a potential biomarker for early detection of pancreatic cancer.
METHODS::Background: SLC6A14 (ATB0,+), a Na+/Cl-coupled transporter for neutral/cationic amino acids, is overexpressed in many cancers; It has been investigated as a target for improved liposomal drug delivery to treat liver cancer.Research design and methods: Here we explored the mechanism of ATB0,+-mediated entry of such liposomes. As ATB0,+ is highly-expressed in pancreatic cancer, we also examined the therapeutic utility of ATB0,+-targeted liposomal drug delivery to treat this cancer.Results: The uptake of lysine-conjugated liposomes (LYS-LPs) was greater in ATB0,+-positive MCF7 cells. The uptake process consisted of two steps: binding and internalization. The binding of LYS-LPs to MCF7 cells was higher than that of bare liposomes, and the process was dependent on Na+ and Cl-, and inhibitable by ATB0,+ substrates or blocker. In contrast, the internalization step was independent of lysine. The cellular entry of LYS-LPs facilitated by ATB0,+ occurred via endocytosis with transient endosomal degradation of ATB0,+ protein with subsequent recovery. Moreover, LYS-LPs also enhanced the uptake and cytotoxicity of gemcitabine in these cells in an ATB0,+-dependent manner.Conclusions: We conclude that ATB0,+ could be exploited for targeted drug delivery in the form of lysine-conjugated liposomes and that the approach represents a novel strategy for enhanced pancreatic cancer therapy.
METHODS:PURPOSE:Pre-operative prediction of histological response to neoadjuvant therapy aids decisions regarding surgical management of borderline resectable pancreatic cancer (BRPC). We elucidate correlation between pre-/post-treatment whole-tumor apparent diffusion coefficient (ADC) value and rate of tumor cell destruction. We newly verify whether post-treatment ADC value at the site of vascular contact predicts R0 resectability of BRPC. METHODS:We prospectively reviewed 28 patients with BRPC who underwent diffusion-weighted magnetic resonance imaging before neoadjuvant chemotherapy and surgery. Correlation between the percentage of tumor cell destruction and various parameters was analyzed. Strong parameters were assessed for their ability to predict therapeutic histological response and R0 resectability. RESULTS:Pre-/post-treatment whole-tumor ADC value correlated with tumor cell destruction rate by all parameters (R = 0.630/0.714, P 50% was determined at 1.40 × 10-3 mm2/s. It predicts histological response with 100% sensitivity, 81% specificity, and 89% accuracy. It predicts R0 with 88% sensitivity, 70% specificity, and 75% accuracy. CONCLUSIONS:Post-treatment whole-tumor ADC value may be a predictor of R0 resectability in patients with BRPC. Tumor cell destruction rate is indicated by the difference between pre-/post-treatment ADC values. This difference is strongly affected by the pre-treatment ADC value. The cutoff value of ADC at the site of vascular contact could not discriminate R0 resectability.