Identification of m6A modification patterns and RBM15 mediated macrophage phagocytosis in pancreatic cancer: An integrative analysis.

Pancreatic cancer (PC) responds weakly to conventional immunotherapy. RNA N6-methyladenosine (m6A) modification has an essential role in the immune response, while its potential role in PC tumor microenvironment (TME) immune cell infiltration remains unknown. In this study, we thoroughly assessed the m6A modification patterns of 472 PC samples using 19 m6A regulators, and we systematically correlated these modification patterns with TME immune cell infiltration characteristics. We also created the m6Ascore and evaluated the m6A modification patterns of individual tumors, identified three different m6A modification patterns, and explored the role of the important m6A "writer" RBM15 in the regulation of macrophage function in PC. Two independent PC cohorts confirmed that patients with higher m6Ascore showed significant survival benefit. We verified that knockdown of RBM15 has the ability to inhibit PC growth and to promote macrophage infiltration and enhance phagocytosis of PC cells by macrophages. In conclusion, m6A modifications play a non-negligible role in the formation of TME diversity and complexity in PC. We reveal that inhibition of RBM15 suppresses PC development and modulates macrophage phagocytosis, and provide a more effective immunotherapeutic strategy for PC.

N6 -methyladenosine RNA demethylase FTO regulates extracellular matrix-related genes and promotes pancreatic cancer cell migration and invasion.

Pancreatic cancer (PC) is a deadly disease, and its post-transcriptional gene regulation mechanism remains unclear. The abundant extracellular matrix (ECM) in PC plays an important role in tumor progression. This study is the first to focus on the role of N6 -methyladenosine (m6 A) RNA methylation, an emerging post-transcriptional regulatory mechanism, in the regulation of the ECM in PC. Here, we found that ADAMTS2, COL12A1, and THBS2 were associated with the prognosis of PC by comprehensive analysis of differentially expressed genes from two independent GEO expression profile datasets and m6 A-related genes in RMVar database (PAAD). GO and KEGG enrichment analysis found that these m6 A-related targets are chiefly functionally concentrated in the ECM region and participate in ECM signal transduction. Correlation analysis revealed that these genes can be regulated by the demethylase FTO. Cell biology function assays showed that knockdown of FTO-inhibited PC cell abilities to migrate and invade in vitro. qRT-PCR and MeRIP experiments showed that after knockdown of FTO, the mRNA levels of ADAMTS2, COL12A1, and THBS2 and their m6 A modification levels were significantly reduced. These results indicate that m6 A RNA demethylation is associated with the regulation of ECM in PC. In conclusion, m6 A RNA demethylase FTO regulates ECM-related genes and promotes PC cell abilities to migrate and invade, our work provides a new perspective on the molecular mechanism of PC progression.

m6A RNA demethylase FTO promotes the growth, migration and invasion of pancreatic cancer cells through inhibiting TFPI-2.

Pancreatic cancer (PC) is one of the most fatal cancers with a very poor prognosis. Here, we found that N6-methyladenosine (m6A) RNA demethylase fat mass and obesity-related protein (FTO) promote the growth, migration and invasion of PC. FTO expression level is increased in human PC and is associated with poor prognosis of PC patients. Knockdown of FTO increases m6A methylation of TFPI-2 mRNA in PC cells, thereby increasing mRNA stability via the m6A reader YTHDF1, resulting in up-regulation of TFPI-2 expression, and inhibits PC proliferation, colony formation, sphere formation, migration and invasion in vitro, as well as tumour growth in vivo. Rescue assay further confirms that FTO facilitates cancer progression by reducing the expression of TFPI-2. Mechanistically, FTO promotes the progression of PC at least partially through reducing m6A/YTHDF1 mediated TFPI-2 mRNA stability. Our findings reveal that FTO, as an m6A demethylase, plays a critical role in promoting PC growth, migration and invasion, suggesting that FTO may be a potential therapeutic target for treating PC.

Four potential microRNAs affect the progression of pancreatic ductal adenocarcinoma by targeting MET via the PI3K/AKT signaling pathway.

Pancreatic ductal adenocarcinoma (PDAC) is the most common tumor subtype of pancreatic cancer, which exhibits poor patient prognosis due to the lack of effective biomarkers in the diagnosis and treatment. The present study aimed to identify the potential biomarkers of PDAC carcinogenesis and progression using three microarray datasets, GSE15471, GSE16515 and GSE28735, which were downloaded from the Gene Expression Omnibus database. The datasets were analyzed to screen out differentially expressed genes (DEGs) in PDAC tissues and adjacent normal tissues. A total of 143 DEGs were identified, including 132 upregulated genes and 11 downregulated genes. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes functional and signaling pathway enrichment analyses were performed on the DEGs, and the Search Tool for the Retrieval of Interacting Genes/Proteins database was used to construct a protein-protein interaction network. The main functions of DEGs include extracellular matrix degradation, and regulation of matrix metalloproteinase activity and the PI3K-Akt signaling pathway. The five hub genes were subsequently screened using Cytoscape software, and survival analysis demonstrated that abnormal expression levels of the hub genes was associated with poor disease-free survival and overall survival. Biological experiments were performed to confirm whether mesenchymal-to-epithelial transition (MET) factors promote the proliferation, migration and invasion of PDAC cells via the PI3K/AKT signaling pathway. In addition, six MET-targeted microRNAs (miRNAs) were identified, four of which had conserved binding sites with MET. Based on the signaling pathway enrichment analysis of these miRNAs, it is suggested that they can affect the progression of PDAC by targeting MET via the PI3K/AKT signaling pathway. In conclusion, the hub genes and miRNAs that were identified in the present study contribute to the molecular mechanisms of PDAC carcinogenesis and progression. They also provide candidate biomarkers for early diagnosis and treatment of patients with PDAC.

Panax notoginseng Saponins Promote Cell Death and Chemosensitivity in Pancreatic Cancer through the Apoptosis and Autophagy Pathways.

BACKGROUND: Panax notoginseng Saponins (PNS) is used as a traditional Chinese medicine for ischemic stroke and cardiovascular disease; it has been proven to possess anticancer activity recently. OBJECTIVE: In this study, we aimed to explore the curative anticancer effect and potential mechanisms of PNS in pancreatic cancer cells. METHODS: Pancreatic cancer Miapaca2 and PANC-1 cells were treated with PNS and Gemcitabine (Gem), respectively. Then the cell viability was assessed by CCK-8 assay, cell proliferation was tested by colony formation assay and EdU cell proliferation assay, cell migration and invasiveness were tested by wound healing assay and transwell assay, respectively, and cell apoptosis was detected by flow cytometry. Finally, we detected the expression levels of proteins related to migration, apoptosis and autophagy through Western blotting. RESULTS: PNS not only inhibited the proliferation, migration, invasion and autophagy of Miapaca2 and PANC-1 cells, but also induced apoptosis and promoted chemosensitivity of pancreatic cancer cells to Gem. CONCLUSION: PNS may exhibit cytotoxicity and increase chemosensitivity of pancreatic cancer cells to Gem by inhibiting autophagy and inducing apoptosis, providing a new strategy and potential treatment option for pancreatic cancer.

MicroRNA-23a acts as an oncogene in pancreatic carcinoma by targeting TFPI-2.

Pancreatic carcinoma (PC) is a rapidly progressive, fatal malignant tumor with the poorest prognosis among all major carcinoma types. MicroRNAs (miRNAs/miRs) have been indicated to be key post-transcriptional regulatory factors, which are involved in cancer development. The present study was designed to investigate the effect of miR-23a on PC cell proliferation, metastasis and apoptosis. The expression of miR-23a was detected in a normal pancreatic ductal epithelial cell line and three PC cell lines, and miR-23a inhibitor or mimics were transfected into the Panc-1 and MiaPaCa2 PC cells. The association between miR-23a and tissue factor pathway inhibitor (TFPI)-2 was examined using a luciferase reporter assay. MTT and flow cytometry assays were used to assess cell viability and apoptosis, respectively. Furthermore, wound-healing, Transwell and Matrigel assays were used to evaluate cell migration and invasion abilities, and the protein expression level of TFPI-2 was determined using western blot analysis. The results of the present study revealed that miR-23a was upregulated in PC cells. Furthermore, TFPI-2 was identified as a downstream target of miR-23a, and TFPI-2 expression was found to be increased following miR-23a knockdown. In addition, functional assays revealed that downregulation of miR-23a decreased PC cell proliferation, migration and invasiveness and promoted cell apoptosis, while miR-23a overexpression exerted the opposite effects. Furthermore, TFPI-2 knockdown rescued the biological effects on PC cells, which were induced by miR-23a knockdown. The results of the present study indicated that miR-23a negatively modulated TFPI-2 expression in vitro and enhanced the malignant phenotypes of PC cells. Therefore, miR-23a may be a potential marker and/or target for the diagnosis and treatment of PC.

Circulating exosomal microRNAs as novel potential detection biomarkers in pancreatic cancer.

Circulating exosomal microRNAs (ex-miRNAs) are reflective of the characteristics of the tumor and are valuable biomarkers in different types of tumor. In addition, miRNAs serve important roles in tumor progression and metastasis. The present study aimed to investigate the circulating ex-miRNA-21 and miRNA-210 as novel biomarkers for patients with pancreatic cancer (PC). For this purpose, serum ex-miRNAs were extracted from the serum of patients with PC (n=30) and chronic pancreatitis (CP) (n=10) using an RNA isolation kit. For exosome identification in serum, transmission electron micrographs were used to determine crystalline structure, western blotting was used to identify exosomal markers, and NanoSight was used for nanoparticle characterization. The relative expression levels of ex-miRNAs were quantified using quantitative PCR and compared between patients with PC and CP. The expression levels of both ex-miRNA-21 and miRNA-210 were significantly higher in patients with PC compared with patients with CP (both P<0.001). However, no significant difference in the relative serum levels of free miR-21 and miR-210 was observed between the 2 groups of patients (both P>0.05). ex-miRNA-21 and miRNA-210 were associated with tumor stage, as well as other factors. The diagnostic potential of ex-miRNA-21 and miRNA-210 levels was 83 and 85%, respectively. In addition, when ex-miRNA and serum carbohydrate antigen 19-9 expression levels were combined, the accuracy increased to 90%. The present study identified that serum ex-miRNAs, miRNA-21 and miRNA-210 may be of value as potential biomarkers and therapeutic targets for the diagnosis and treatment of PC.