CircFOXK2 Promotes Growth and Metastasis of Pancreatic Ductal Adenocarcinoma by Complexing with RNA Binding Proteins and Sponging MiR-942.
CircFOXK2 通过与 RNA 结合蛋白和海绵 MiR-942 络合促进胰腺导管腺癌的生长和转移。
- 作者列表："Wong CH","Lou UK","Li Y","Chan SL","Tong JHM","To KF","Chen Y
:The detailed biological functions of circular RNA (circRNA) are largely unexplored. Using circRNA sequencing, we identified 169 differentially expressed circRNA in pancreatic ductal adenocarcinoma (PDAC) cells compared to non-tumor human pancreatic ductal epithelial (HPDE) cells. Among them, circFOXK2 was validated with significant upregulation in PDAC cells and 63 % of primary tumors (53 out of 84). circFOXK2 promoted cell growth, migration, and invasion and was involved in cell cycle progression and apoptosis. circFOXK2 contained multiple miRNA binding sites, functioning as a sponge for miR-942, which in turn promoted expression of ANK1, GDNF, and PAX6. A novel and highly specific circRNA-pulldown followed by mass spectrometry analysis identified 94 circFOXK2-interacting proteins, which were involved in cell adhesion, mRNA splicing, and structural molecule activity. Of these, circFOKX2 interactions with YBX1 and hnRNPK enhanced expression of oncogenes NUF2 and PDXK. Knockdown of circFOXK2 reduced binding of YBX1 and hnRNPK to NUF2 and PDXK, in turn decreasing their expression. Collectively, our findings demonstrate that circFOXK2 in complex with YBX1 and hnRNPK promotes expression of oncogenic proteins that contribute to PDAC progression.
: 环状 RNA (circRNA) 的详细生物学功能在很大程度上是未知的。使用 circRNA 测序，我们与非肿瘤人胰腺导管上皮 (HPDE) 细胞相比，在胰腺导管腺癌 (PDAC) 细胞中鉴定了 169 个差异表达的 circRNA。其中，circFOXK2 在 PDAC 细胞和 63% 的原发性肿瘤 (84 例中有 53 例) 中被验证为显著上调。circFOXK2 促进细胞生长、迁移和侵袭，参与细胞周期进程和凋亡。circoxk2 包含多个 miRNA 结合位点，作为 miR-942 的海绵,从而促进 ANK1 、 GDNF 和 pax6 的表达。一个新的和高度特异性的 circRNA-pulldown 随后的质谱分析确定了 94 circFOXK2-interacting 蛋白，它们参与细胞粘附，mRNA 剪接和结构分子活性。其中，circFOKX2 与 YBX1 和 hnRNPK 的相互作用增强了癌基因 NUF2 和 PDXK 的表达。敲除 circoxk2 可减少 YBX1 和 hnRNPK 与 NUF2 和 PDXK 的结合，进而降低它们的表达。总的来说，我们的研究结果证明 circoxk2 与 YBX1 和 hnRNPK 复合物促进了有助于 PDAC 进展的致癌蛋白的表达。
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.