YY1 targets tubulin polymerisation-promoting protein to inhibit migration, invasion and angiogenesis in pancreatic cancer via p38/MAPK and PI3K/AKT pathways.

BACKGROUND: Pancreatic cancer (PDAC) is a highly invasive cancer with poor prognosis. Recent research has found that the transcription factor Yin Yang 1 (YY1) plays an inhibitory role in the development of pancreatic cancer. It has been reported that tubulin polymerisation-promoting protein (TPPP) plays an indispensable role in a variety of tumours, but its expression and role in pancreatic cancer have not yet been elucidated. METHODS: In this study, we performed ChIP-sequencing and found that YY1 directly binds to the promoter region of TPPP. The expression of TPPP in pancreatic cancer was detected by western blotting and immunohistochemistry. Four-week-old male BALB/c-nude mice were used to assess the effect of TPPP on pancreatic cancer. RESULTS: Immunohistochemistry revealed that TPPP was expressed at low levels in pancreatic cancer tissues, and was associated with blood vessel invasion. The results from vivo experiments have showed that TPPP could enhance the migration and invasion of pancreatic cancer. Further experiments showed that YY1 could inhibit the migration, invasion and angiogenesis of pancreatic cancer cells by downregulating TPPP via p38/MAPK and PI3K/AKT pathways. CONCLUSION: Our study demonstrates that TPPP may act as a promoter and may serve as a novel target for the treatment of pancreatic cancer.

MiR-548t-5p regulates pancreatic ductal adenocarcinoma metastasis through an IL-33-dependent crosstalk between cancer cells and M2 macrophages.

IL-33 has been associated with pro- and anticancer functions in cancer. However, its role in pancreatic cancer metastasis remains unknown. This study aimed to explore the role of miR-548t-5p/IL-33 axis in the metastasis of pancreatic cancer. Luciferase activity assay, qRT-PCR, Western blot and ELISA were performed to prove whether IL-33 is the target of miR-548t-5p. In vivo metastasis assay and cellular transwell assay were performed to explore the role of miR-548t-5p/IL-33 axis in the invasion and metastasis of pancreatic cancer. Co-culture experiments and immunohistochemistry were performed to observe whether IL-33 affects cell invasion and metastasis dependent on the involvement of M2 macrophages. THP-1 cell induction experiment and flow cytometry were performed to explore the effect of IL-33 on macrophage polarization. CCK-8, colony formation, cell apoptosis, cell cycle, cell wound healing and transwell assay were performed to investigate the effect of IL-33 induced M2 macrophages on cell malignant biological behavior by coculturing pancreatic cancer cells with the conditioned medium (CM) from macrophages. We found that miR-548t-5p regulated the expression and secretion of IL-33 in pancreatic cancer cells by directly targeting IL-33 mRNA. IL-33 secreted by cancer cells promoted the recruitment and activation of macrophages to a M2-like phenotype. In turn, IL-33 induced M2 macrophages promoted the migration and invasion of cancer cells. Moreover, IL-33 affected pancreatic cancer cell invasion dependent on the involvement of M2 macrophages in the co-culture system. Thus, our study suggested that manipulation of this IL-33-dependent crosstalk has a therapeutic potential for the treatment of pancreatic cancer metastasis.

Suppressive effect of YY1-mediated RGS22 regulation on the proliferation, migration and invasion of pancreatic ductal adenocarcinoma.

Regulator of G-protein signaling 22 (RGS22) is specifically expressed in the testis and in tumors of epithelial origin, but the expression and role of RGS22 in pancreatic cancer are unclear. In this study, 52 pairs of pancreatic ductal adenocarcinoma (PDAC) and adjacent non-neoplastic tissue samples with the corresponding clinical data were used to examine the expression of RGS22 and its relationship with PDAC prognosis. The findings showed that the expression of RGS22 was higher in the PDAC tissues than in the adjacent non-tumorous tissues and its expression was associated with the degree of blood vessel invasion. The in vitro experiments with PDAC cell lines and a normal control cell line showed that the proliferation, invasion, and metastasis of PDAC cells were suppressed by RGS22 overexpression and enhanced by RGS22 knockdown. The in vivo effect of RGS22 on PDAC xenografts was studied using subcutaneous implantation of tumor cells in BALB/cA-nu mice, and the results corroborated the in vitro findings. Analysis of the regulators of RGS22 showed that it was positively regulated by the transcription factor Yin Yang-1 (YY1). Thus, YY1-mediated RGS22 regulation suppressed the proliferation, migration, and invasion of PDAC.

DUOX2 As a Potential Prognostic Marker which Promotes Cell Motility and Proliferation in Pancreatic Cancer.

DUOX2 has been reported to highly express in several types of cancers. However, the prognostic significance and the biological function of DUOX2 expression with pancreatic cancer (PC) still remain unclear. The present study is aimed at investigating whether DUOX2 could act as a novel biomarker of prognosis and evaluating its effect on PC cell progression. The mRNA and protein expression of DUOX2 in PC cells and tissues were assessed by quantitative real-time PCR (RT-qPCR) and immunohistochemistry. The effect of DUOX2 expression on PC cell motility and proliferation was evaluated in vitro. The correlation between DUOX2 mRNA expression and clinicopathological features and its prognostic significance were analyzed according to the Gene Expression Profiling Interactive Analysis (GEPIA) website based on The Cancer Genome Atlas (TCGA) and the GTEx databases combined with our clinical information. According to bioinformatics analysis, we forecasted the upstream transcription factors (TFs) and microRNA (miRNA) regulatory mechanism of DUOX2 in PC. The expression of DUOX2 at transcriptional and protein level was dramatically increased in PC specimens when compared to adjacent nontumor specimens. Functionally, DUOX2 knockdown inhibited cell motility and proliferation activities. Our clinical data revealed that the patients had better postoperative overall survival (OS) with lower expression of DUOX2, which is consistent with GEPIA data. Multivariate analysis revealed that high DUOX2 expression was considered as an independent prognostic indicator for OS (P = 0.031). Based on Cistrome database, the top 5 TFs of each positively and negatively association with DUOX2 were predicted. hsa-miR-5193 and hsa-miR-1343-3p targeting DUOX2 were forecasted from TargetScan, miRDB, and DIANA-TarBase databases, which were negatively correlated with OS (P = 0.043 and P = 0.0088, respectively) and DUOX2 expression (P = 0.0093 and P = 0.0032, respectively) in PC from TCGA data. These findings suggest that DUOX2 acts as a promising predictive biomarker and an oncogene in PC, which could be a therapeutic target for PC.

Roundabout homolog 1 inhibits proliferation via the YY1-ROBO1-CCNA2-CDK2 axis in human pancreatic cancer.

Pancreatic cancer (PC) is highly malignant and has a high mortality with a 5-year survival rate of less than 8%. As a member of the roundabout immunoglobulin superfamily of proteins, ROBO1 plays an important role in embryogenesis and organogenesis and also inhibits metastasis in PC. Our study was designed to explore whether ROBO1 has effects on the proliferation of PC and its specific mechanism. The expression of ROBO1 was higher in cancer tissues than in matched adjacent tissues by immunohistochemistry (IHC) and qRT-PCR. Low ROBO1 expression is associated with PC progression and poor prognosis. Overexpression of ROBO1 can inhibit the proliferation of PC cells in vitro, and the S phase fraction can also be induced. Further subcutaneous tumor formation in nude mice showed that ROBO1 overexpression can significantly inhibit tumor growth. YY1 was found to directly bind to the promoter region of ROBO1 to promote transcription by a luciferase reporter gene assay, a chromatin immunoprecipitation (ChIP) and an electrophoretic mobility shift assay (EMSA). Mechanistic studies showed that YY1 can inhibit the development of PC by directly regulating ROBO1 via the CCNA2/CDK2 axis. Taken together, our results suggest that ROBO1 may be involved in the development and progression of PC by regulating cell proliferation and shows that ROBO1 may be a novel and promising therapeutic target for PC.

Effect of the transcription factor YY1 on the development of pancreatic endocrine and exocrine tumors: a narrative review.

Pancreatic tumors are classified into endocrine and exocrine types, and the clinical manifestations in patients are nonspecific. Most patients, especially those with pancreatic ductal adenocarcinoma (PDAC), have lost the opportunity to receive for the best treatment at the time of diagnosis. Although chemotherapy and radiotherapy have shown good therapeutic results in other tumors, their therapeutic effects on pancreatic tumors are minimal. A multifunctional transcription factor, Yin-Yang 1 (YY1) regulates the transcription of a variety of important genes and plays a significant role in diverse tumors. Studies have shown that targeting YY1 can improve the survival time of patients with tumors. In this review, we focused on the mechanism by which YY1 affects the occurrence and development of pancreatic tumors. We found that a YY1 mutation is specific for insulinomas and has a role in driving the degree of malignancy. In addition, changes in the circadian network are a key causative factor of PDAC. YY1 promotes pancreatic clock progression and induces malignant changes, but YY1 seems to act as a tumor suppressor in PDAC and affects many biological behaviors, such as proliferation, migration, apoptosis and metastasis. Our review summarizes the progress in understanding the role of YY1 in pancreatic endocrine and exocrine tumors and provides a reasonable assessment of the potential for therapeutic targeting of YY1 in pancreatic tumors.

Optimization of internal reference genes for qPCR in human pancreatic cancer research.

BACKGROUND: Pancreatic cancer (PC) has been becoming a common cancer with high mortality and quantitative real-time polymerase chain reaction (qPCR) is one of the best choices for researching gene expression. Internal reference genes, such as actin beta (ACTB) and glyceraldehyde-3-phosphatide hydrogenase (GAPDH) have long been used in relative quantification analysis. But evidence shows that some internal reference genes expression may vary in different tissues, cell lines and different conditions. The present study aimed to find more stable internal reference gene for qPCR experiment in PC. METHODS: Total RNA of human PC tissues were prepared using TRIZOL reagent. qPCR was performed using FastStart Universal SYBR Green Master to reflects the expression of target genes. Normfinder and geNorm were used to analyze the stability of chosen internal reference genes. RESULTS: According to the results of NormFinder and geNorm, eukaryotic translation initiation factor 2B subunit alpha (EIF2B1) and importin 8 (IPO8) were the same most stable internal reference genes in PCs and non-neoplastic tissues. In addition, EIF2B1 and IPO8 remained the most stable internal reference genes only in PCs. Using a normalization factor NF2 by geNorm as reference, the normalized GAPDH and ACTB expression levels were obviously up-regulated by 3.29- and 2.23-fold change, meanwhile ribosomal protein S17 (RPS17) were down-regulated by 0.77-fold change in PCs comparing with corresponding adjacent tissues. CONCLUSIONS: The use of the combination of EIF2B1 and IPO8 would provide more stable results in differential expression analysis and prognostic analysis of PC.

The YY1/miR-548t-5p/CXCL11 signaling axis regulates cell proliferation and metastasis in human pancreatic cancer.

Pancreatic cancer (PC) is a malignant tumor with a poor prognosis and high mortality. However, the biological role of miR-548t-5p in PC has not been reported. In this study, we found that miR-548t-5p expression was significantly decreased in PC tissues compared with adjacent tissues, and that low miR-548t-5p expression was associated with malignant PC behavior. In addition, high miR-548t-5p expression inhibited the proliferation, migration, and invasion of PC cell lines. Regarding the molecular mechanism, the luciferase reporter gene, chromatin immunoprecipitation (ChIP), and functional recovery assays revealed that YY1 binds to the miR-548t-5p promoter and positively regulates the expression and function of miR-548t-5p. miR-548t-5p also directly regulates CXCL11 to inhibit its expression. A high level of CXCL11 was associated with worse Tumor Node Metastasis (TNM) staging in patients with PC, enhancing proliferation and metastasis in PC cells. Our study shows that the YY1/miR-548t-5p/CXCL11 axis plays an important role in PC and provides a new potential candidate for the treatment of PC.

Linc01232 promotes the metastasis of pancreatic cancer by suppressing the ubiquitin-mediated degradation of HNRNPA2B1 and activating the A-Raf-induced MAPK/ERK signaling pathway.

Pancreatic cancer (PC) is a malignant cancer with high mortality and poor prognosis. In this study, we found that Linc01232 was significantly upregulated in PC tissues and cells and higher Linc01232 expression was associated with poorer prognosis. Linc01232 overexpression promoted and Linc01232 knockdown inhibited the migration and invasion of PC cells. The results of RNA pull-down, RNA Binding Protein Immunoprecipitation (RIP) assays revealed that Linc01232 physically interacted with Heterogeneous Nuclear Ribonucleoprotein A2/B1 (HNRNPA2B1) (680-890 nt fragment with the RNA recognition motif 2 domain) to inhibit its ubiquitin-mediated degradation in PC cells. RNA sequencing was performed to obtain the transcriptional profiles regulated by Linc01232 and we further demonstrated that Linc01232 participated in the alternative splicing of A-Raf by stabilizing HNRNPA2B1 and subsequently regulated the MAPK/ERK signaling pathway. Collected, our study showed that Linc01232/HNRNPA2B1/A-Raf/MAPK axis participated in the progression of PC and provided a potential therapeutic target for PC.

YY1 inhibits the migration and invasion of pancreatic ductal adenocarcinoma by downregulating the FER/STAT3/MMP2 signaling pathway.

Pancreatic ductal adenocarcinoma (PDAC) has a poor prognosis and a high mortality rate. The transcription factor YY1 acts as an inhibitor of many types of tumors. We found that YY1 knockdown promoted the invasion and migration of PANC-1 and BxPC-3 cells; FER knockdown partially restored the promotion of pancreatic cancer caused by YY1 knockdown. In vivo experiments yielded the same results. According to luciferase reporter gene, electrophoretic mobility shift (EMSA) and chromatin immunoprecipitation (ChIP) assays, YY1 directly binds to the FER promoter region. Moreover, higher level FER expression results in a worse TNM stage and prognosis for patients with PDAC. Furthermore, by downregulating FER, YY1 inhibits the formation of the STAT3-MMP2 complex, thereby suppressing expression of MMP2 and ultimately inhibiting the migration and invasion of pancreatic cancer. Our study demonstrates that the YY1/FER/STAT3/MMP2 axis is associated with the progression of pancreatic cancer and may provide a new therapeutic target for the treatment of pancreatic cancer.

Association between NR5A2 and the risk of pancreatic cancer, especially among Caucasians: a meta-analysis of case-control studies.

BACKGROUND: Previous studies have reported that nuclear receptor subfamily 5, group A, member 2 (NR5A2) polymorphisms (rs3790843 G>A, rs3790844 T>C, rs12029406 C>T) are associated with the risk of pancreatic cancer. However, the results of epidemiological investigations are still controversial. In order to explore its potential attributing factors, we pooled the updated literatures to evaluate the association between NR5A2 polymorphism and the risk of pancreatic cancer in this meta-analysis. MATERIALS AND METHODS: Databases such as PubMed, Google Scholar and China National Knowledge Infrastructure were searched for eligible articles following strict inclusion and exclusion criteria (updated to November 18, 2017). Odds ratios (ORs) and 95% CIs were computed to assess the intensity of association. In addition, heterogeneity, sensitivity analysis and publication bias were explored. All statistical analyses were conducted by STATA 14.0. RESULTS: Our results showed that the rs3790843 (GA vs GG: OR=0.86, CI=0.76-0.98, P=0.992; GA+AA vs GG: OR=0.83, CI=0.73-0.94, P=0.950; A vs G: OR=0.85, CI=0.78-0.93, P=0.802), rs3790844 (CC vs TT: OR=0.65, CI=0.54-0.78, P=0.617; CC vs TT+CT: OR=0.73, CI=0.62-0.85, P=0.742; C vs T: OR=0.78, CI=0.73-0.84, P=0.555) and rs12029406 (TT vs CC: OR=0.73, CI=0.61-0.89, P=0.483; TT vs CC+CT: OR=0.78, CI=0.66-0.92, P=0.648; T vs C: OR=0.87, CI=0.79-0.95, P=0.837) polymorphisms were associated statistically with the risk of pancreatic cancer. Furthermore, the results of subgroup analysis showed that rs3790843 and rs3790844 polymorphisms were especially related to the risk of pancreatic cancer in Caucasian population. CONCLUSION: Our results revealed that NR5A2 may have a protective effect on pancreatic cancer. However, more well-designed researches are needed to verify the relationship between NR5A2 polymorphisms and the risk of pancreatic cancer.