MiRNA-615-5p Functions as a Tumor Suppressor in Pancreatic Ductal Adenocarcinoma by Targeting AKT2

Background

Aberrant microRNA (miRNA) expression is associated with tumor development. This study aimed to elucidate the role of miR-615-5p in the development of pancreatic ductal adenocarcinoma (PDAC).

Methods

Locked nucleic acid in situ hybridization (LNA-ISH) was performed to compare miR-615-5p expression in patients between PDAC and matched adjacent normal tissues. Effects of miR-615-5p overexpression on cell proliferation, apoptosis, colony formation, migration, and invasion were determined in the pancreatic cancer cell lines PANC-1 and MIA PaCa-2. Effects of miR-615-5p on AKT2 were examined by dual-luciferase reporter assay. Lentivirus expressing miR-615 was used to create stable overexpression cell lines, which were subsequently used in mouse xenograft and metastasis models to assess tumor growth, apoptosis and metastasis.

Results

miR-615-5p expression was significantly lower in PDAC than in adjacent normal tissues. Low levels of miR-615-5p were independently associated with poor prognosis (HR: 2.243, 95% CI: 1.190-4.227, P=0.013). AKT2 protein expression was inversely correlated with miR-615-5p expression (r=-0.3, P=0.003). miR-615-5p directly targeted the 3’-untranslated region of AKT2 mRNA and repressed its expression. miR-615-5p overexpression inhibited pancreatic cancer cell proliferation, migration, and invasion in vitro, and tumor growth and metastasis in vivo. Furthermore, miR-615-5p overexpression also induced pancreatic cancer cell apoptosis both in vitro and in vivo.

Conclusions

These results show that miR-615-5p inhibits pancreatic cancer cell proliferation, migration, and invasion by targeting AKT2. The data implicate miR-615-5p in the prognosis and treatment of PDAC.     

miR-186 and 326 Predict the Prognosis of Pancreatic Ductal Adenocarcinoma and Affect the Proliferation and Migration of Cancer Cells

MicroRNAs can function as key tumor suppressors or oncogenes and act as biomarkers for cancer diagnosis or prognosis. Although high-throughput assays have revealed many miRNA biomarkers for pancreatic ductal adenocarcinoma (PDAC), only a few have been validated in independent populations or investigated for functional significance in PDAC pathogenesis. In this study, we correlated the expression of 36 potentially prognostic miRNAs within PDAC tissue with clinico-pathological features and survival in 151 Chinese patients. We then analyzed the functional roles and target genes of two miRNAs in PDAC development. We found that high expression of miR-186 and miR-326 predict poor and improved survival, respectively. miR-186 was over-expressed in PDAC patients compared with controls, especially in patients with large tumors (>2 cm), lymph node metastasis, or short-term survival (< 24 months). In contrast, miR-326 was down-regulated in patients compared with controls and displayed relatively increased expression in the patients with long-term survival or without venous invasion. Functional experiments revealed that PDAC cell proliferation and migration was decreased following inhibition and enhanced following over-expression of miR-186. In contrast, it was enhanced following inhibition and decreased after over-expression of miR-326. A luciferase assay indicated that miR-186 can bind directly to the 3′-UTR of NR5A2 to repress gene expression. These findings suggest that miR-186 over-expression contributes to the invasive potential of PDAC, likely via suppression of NR5A2, thereby leading to a poor prognosis; high miR-326 expression prolongs survival likely via the decreasing invasive potential of PDAC cells. These two miRNAs can be used as markers for clinical diagnosis and prognosis, and they represent therapeutic targets for PDAC.     

Long noncoding RNA DLEU1 aggravates pancreatic ductal adenocarcinoma carcinogenesis via the miR-381/CXCR4 axis

Recent evidence has highlighted that long noncoding RNAs (lncRNA) are associated with many diseases, particularly cancer. However, current understanding of the lncRNA deleted in lymphocytic leukemia 1 (DLEU1) in pancreatic ductal adenocarcinoma (PDAC) remains limited. Our studies indicated that the DLEU1 expression level was upregulated in PDAC tissue samples compared with adjacent normal tissue. Moreover, the aberrant overexpression of DLEU1 indicated poor prognosis of patients with PDAC. Loss-of-function experiments revealed that DLEU1 knockdown inhibited the proliferation, migration, and invasion of PDAC cells in vitro and decreased tumor growth in vivo. Bioinformatics analysis predicted that miR-381 potentially targeted the DLEU1 3′-untranslated region (UTR), suggesting an interaction between miR-381 and DLEU1. Furthermore, miR-381 also targeted the chemokine receptor-4 (CXCR4) messenger RNA 3′-UTR, which was validated by luciferase reporter assay. Taken together, our study demonstrated the oncogenic role of DLEU1 in clinical PDAC specimens and cellular experiments, showing the potential involvement of DLEU1/miR-381/CXCR4 pathway. These results provide novel insight into PDAC tumorigenesis.     

RELA/NEAT1/miR-302a-3p/RELA feedback loop modulates pancreatic ductal adenocarcinoma cell proliferation and migration

Pancreatic ductal adenocarcinoma (PDAC) remains a challenging malignancy due to distant metastasis. RELA, a major component of the NF-κB pathway, could serve as an oncogene through activating proliferation or migration-related gene expression, including NEAT1, a well-known oncogenic long noncoding RNA. In the current study, the expression and function of RELA and NEAT1 in PDAC were examined. The potential upstream regulatory microRNAs of RELA were screened and verified for their correlation with RELA and NEAT1. The expression and function of the selected miR-302a-3p were evaluated. RELA and NEAT1 expression were upregulated in PDAC tissues, particularly in PDAC tissues with lymph node metastasis, and their expression correlated with clinical parameters. RELA overexpression promoted PDAC cell proliferation and migration, which could be partially attenuated by the NEAT1 knockdown. By binding to RELA, miR-302a-3p inhibited RELA expression, as well as PDAC cell proliferation and migration. RELA downstream NEAT1 expression was negatively regulated by miR-302a-3p; the suppressive effect of NEAT1 knockdown on PDAC cell proliferation and migration was partially attenuated by miR-302a-3p inhibition. Moreover, through direct binding, the expression of miR-302a-3p was also negatively regulated by NEAT1. The expression of miR-302a-3p was downregulated and negatively correlated with RELA or NEAT1 in tissue samples, indicating that rescuing miR-302a-3p expression may inhibit PDAC cell proliferation and migration through RELA/NEAT1. In summary, RELA, NEAT1, and miR-302a-3p form a feedback loop in PDAC to modulate PDAC cell proliferation and migration.     

MicroRNA-200 Family Members Differentially Regulate Morphological Plasticity and Mode of Melanoma Cell Invasion

Background

A functional role of microRNAs (miRNAs or miRs) in neoplasia and metastasis is becoming clear, and the miR-200 family has received much attention for potentially regulating tumor progression. The miRNAs of this family have been shown to suppress epithelial-mesenchymal transition, and their down-regulation in some tumors promotes invasion and metastasis. Interestingly, while miR-200 is down-regulated in some cancers, it is up-regulated in others.

Principal Findings

We show that levels of miR-200 are increased in melanoma cell lines compared to normal melanocytes and that miR-200 family members play a role in determining modes of tumor cell migration. Individual tumor cells can invade in either elongated, “mesenchymal-type” or rounded, “amoeboid-like” modes and these two modes of invasion are inter-convertible [1]. In melanoma cell lines, expression of miR-200 members does not suppress invasion but rather leads to a switch between modes of invasion. MicroRNA-200c results in a higher proportion of cells adopting the rounded, amoeboid-like mode of invasion, while miR-200a results in a protrusion-associated elongated mode of invasion. Functional target identification studies suggest that the morphological effects of miR-200c may be mediated by reduced expression of MARCKS, which has been linked to formation of cell protrusions. In contrast miR-200a reduces actomyosin contractility, a feature of rounded morphology.

Significance

Overall our findings call into question the general role of miR-200 in suppressing invasion and metastasis, and highlight novel distinguishing characteristics of individual miR-200 family members.     

MiR-1178 Promotes the Proliferation,G1/S Transition,Migration and Invasion of Pancreatic Cancer Cells by Targeting CHIP

CHIP, a co-chaperone protein that interacts with Hsc/Hsp70, has been shown to be under-expressed in pancreatic cancer cells and has demonstrated a potential tumor suppressor property. Nevertheless, the underlying mechanisms of CHIP regulation in pancreatic cancer cells remain unknown. In this study, we found that miR-1178 decreased the translation of the CHIP protein by targeting the 3′-UTR region. We observed that over-expression of miR-1178 facilitated the proliferation, G1/S transition, migration and invasion of pancreatic cancer cells. Conversely, the inhibition of miR-1178 expression significantly suppressed these phenotypes. Furthermore, CHIP over-expression abrogated miR-1178-induced cell proliferation and invasion. Our data suggest that miR-1178 acts as an oncomiR in pancreatic cancer cells by inhibiting CHIP expression.     

miR-211 Modulates Gemcitabine Activity Through Downregulation of Ribonucleotide Reductase and Inhibits the Invasive Behavior of Pancreatic Cancer Cells

Only a subset of radically-resected pancreatic ductal adenocarcinoma (PDAC) patients benefit from gemcitabine-based chemotherapy, thus the identification of novel prognostic factors is essential. In a high-throughput, microRNA (miRNA) array, miR-211 emerged as the best discriminating miRNA, with high expression associated with long survival. Here, we further explored the biological role of miRNA-211 in gemcitabine activity in the human PDAC cells (SUIT-2) subclones SUIT2-007 and SUIT2-028. Our results showed that miR-211 was expressed differentially in PDAC cells characterized by differential metastatic capability. In particular, S2-028 with lower metastatic ability had a higher expression of miR-211, compared to the S2-007 with higher metastatic capacity. Enforced expression of miR-211 via pre-miR-211 significantly reduced cell migration and invasion (e.g., 40% reduction of invasion of SUIT2 cells, compared to control; p <.05). Moreover, we demonstrated that induction of the miR-211 expression in the cells increased the sensitivity to gemcitabine and reduced the expression of its target ribonucleotide reductase subunit 2 (RRM2). In conclusion, miR-211 functional analyses suggested the role of RRM2 as a target of miR-211 in the modulation of gemcitabine sensitivity. Moreover, inhibition of cell migration and invasion might explain the less aggressive behavior of pancreatic cancer cells with higher expression levels of miR-211.     

Antibiotic tigecycline inhibits cell proliferation,migration and invasion via down-regulating CCNE2 in pancreatic ductal adenocarcinoma

Recently, many researches have reported that antibiotic tigecycline has significant effect on cancer treatment. However, biomedical functions and molecular mechanisms of tigecycline in human pancreatic ductal adenocarcinoma (PDAC) remain unclear. In the current study, we tried to assess the effect of tigecycline in PDAC cells. AsPC-1 and HPAC cells were treated with indicated concentrations of tigecycline for indicated time, and then, MTT, BrdU and soft agar assay were used to test cell proliferation. The effect of tigecycline on cell cycle and cellular apoptosis was tested by cytometry. Migration and invasion were detected by wound healing assay and transwell migration/invasion assay. Expressions of cell cycle-related and migration/invasion-related protein were determined by using Western blot. The results revealed that tigecycline observably suppressed cell proliferation by inducing cell cycle arrest at G0/G1 phase and blocked cell migration/invasion via holding back the epithelial-mesenchymal transition (EMT) process in PDAC. In addition, tigecycline also remarkably blocked tumorigenecity in vivo. Furthermore, the effects of tigecycline alone or combined with gemcitabine in vitro or on PDAC xenografts were also performed. The results showed that tigecycline enhanced the chemosensitivity of PDAC cells to gemcitabine. Interestingly, we found CCNE2 expression was declined distinctly after tigecycline treatment. Then, CCNE2 was overexpressed to rescue tigecycline-induced effect. The results showed that CCNE2 overexpression significantly rescued tigecycline-inhibited cell proliferation and migration/invasion. Collectively, we showed that tigecycline inhibits cell proliferation, migration and invasion via down-regulating CCNE2, and tigecycline might be used as a potential drug for PDAC treatment alone or combined with gemcitabine.     

Plexin-B1 is a target of miR-214 in cervical cancer and promotes the growth and invasion of HeLa cells

Plexin-B1, the receptor for Sema4D, has been reported to trigger multiple and sometimes opposing cellular responses in various types of tumor cells. It has been implicated in the regulation of tumor-cell survival, proliferation, angiogenesis, invasion and metastasis. However, the plexin-B1 gene expression and its regulatory mechanism in cervical cancer remain unclear. The present study shows that plexin-B1 is over-expressed in cervical tumor tissues compared to normal cervical tissues by immunohistochemistry, Western blotting and quantitative RT-PCR. The expression of plexin-B1 is significantly associated with cervical tumor metastasis and invasion according to the analysis of the clinicopathologic data. Plexin-B1 also promotes proliferation, migration and invasion in human cervical cancer HeLa cells. We also found that the plexin-B1 levels are inversely correlated with miR-214 amounts in both cervical cancer tissues and HeLa cells. And miR-214 expression level is also associated with metastasis and invasion of cervical tumor. Furthermore, we demonstrate that plexin-B1 is inhibited by miR-214 through a miR-214 binding site within the 3'UTR of plexin-B1 in HeLa cells. Ectopic expression of miR-214 could inhibit the proliferation capacity, migration and invasion ability of HeLa cells. Our findings suggest that plexin-B1, a target of miR-214, may function as an oncogene in human cervical cancer HeLa cells.     

lncRNA JPX modulates malignant progress of osteosarcoma through targeting miR-33a-5p and PNMA1 regulatory loop

Osteosarcoma (OS) is a common type of bone tumor, present worldwide, that has distal metastasis ability. Although continuous development in cancer therapy has taken place, there are still no effective metastasis-curbing strategies for OS available. Hence, a better understanding of the biological characteristics and molecular mechanisms of OS carcinogenesis is urgently needed. Long noncoding RNAs (lncRNAs) have captured great interest among cancer scientists with considerable potential implications for cancer treatment. In this study, we found that lncRNA JPX was up-regulated in OS tissues and cells. We subsequently examined the functional role of JPX in OS cells through knocked-down JPX by using siRNA. JPX down-regulation was observed to suppress OS cell proliferation, migration and invasion. Furthermore, it was verified that JPX acts as a sponge for miR-33a-5p, and that JPX regulated OS cell proliferation, migration and invasion through miR-33a-5p. Moreover, down-regulation of miR-33a-5p in OS contributed to PNMA1 upregulation, and PNMA1 depletion inhibited OS cell proliferation, migration and invasion in vitro. Taken together, our data support an important role of JPX in regulating OS cell proliferation, invasion and migration that highlights JPX may be a potential therapeutic target for OS.     

MicroRNA-221 Mediates the Effects of PDGF-BB on Migration,Proliferation, and the Epithelial-Mesenchymal Transition in Pancreatic Cancer Cells

The platelet-derived growth factor (PDGF) signaling pathway has been found to play important roles in the development and progression of human cancers by regulating the processes of cell proliferation, apoptosis, migration, invasion, metastasis, and the acquisition of the epithelial-mesenchymal transition (EMT) phenotype. Moreover, PDGF signaling has also been found to alter the expression profile of miRNAs, leading to the reversal of EMT phenotype. Although the role of miRNAs in cancer has been documented, there are very few studies documenting the cellular consequences of targeted re-expression of specific miRNAs. Therefore, we investigated whether the treatment of human pancreatic cancer cells with PDGF could alter the expression profile of miRNAs, and we also assessed the cellular consequences. Our study demonstrates that miR-221 is essential for the PDGF-mediated EMT phenotype, migration, and growth of pancreatic cancer cells. Down-regulation of TRPS1 by miR-221 is critical for PDGF-mediated acquisition of the EMT phenotype. Additionally, the PDGF-dependent increase in cell proliferation appears to be mediated by inhibition of a specific target of miR-221 and down-regulation of p27Kip1.     

miR-30 family promotes migratory and invasive abilities in CD133<Superscript>+</Superscript> pancreatic cancer stem-like cells

Pancreatic cancer is a deadly disease with a poor prognosis. Recently, miRNAs have been reported to be abnormally expressed in several cancers and play a role in cancer development and progression. However, the role of miRNA in cancer stem cells remains unclear. Therefore, our aim was to investigate the role of miRNA in the CD133⁺ pancreatic cancer cell line Capan-1M9 because CD133 is a putative marker of pancreatic cancer stem cells. Using miRNA microarray, we found that the expression level of the miR-30 family decreased in CD133 genetic knockdown shCD133 Capan-1M9 cells. We focused on miR-30a, -30b, and -30c in the miR-30 family and created pancreatic cancer cell sublines, each transfected with these miRNAs. High expression of miR-30a, -30b, or -30c had no effect on cell proliferation and sphere forming. In contrast, these sublines were resistant to gemcitabine, which is a standard anticancer drug for pancreatic cancer, and in addition, promoted migration and invasion. Moreover, mesenchymal markers were up-regulated by these miRNAs, suggesting that mesenchymal phenotype is associated with an increase in migration and invasion. Thus, our study demonstrated that high expression of the miR-30 family modulated by CD133 promotes migratory and invasive abilities in CD133⁺ pancreatic cancer cells. These findings suggest that targeted therapies to the miR-30 family contribute to the development of novel therapies for CD133⁺ pancreatic cancer stem cells.     

Long noncoding RNA lncBRM promotes proliferation and invasion of colorectal cancer by sponging miR-204-3p and upregulating TPT1

Long noncoding RNAs (lncRNAs) are characterized as a type of noncoding RNAs over 200 nucleotides with little or none protein-coding potential. In the past years, lncRNAs have been proved to participant in many physiological and pathological processes. However, the role of lncRNAs in colorectal cancer (CRC) still needs more attentions. In our study, we found that lncBRM was highly expressed in CRC samples and the expression level of lncBRM was correlated with metastasis and advanced stage in CRC patients. And also, we showed that high expression of lncBRM predicted poor prognosis. Furthermore, we found that knockdown of lncBRM impaired the proliferation, migration and invasion of CRC cells while overexpressing of lncBRM promotes the proliferation, migration and invasion of CRC cells. Mechanically, we found that lncBRM served as a sponge of miR-204-3p that targeted TPT1. Highly expressed TPT1 can promote the proliferation, migration and invasion of CRC cells. In conclusion, we found that lncBRM was highly expressed in CRC and sponged miR-204-3p to modulate the expression of TPT1.