Differential expression profiling of microRNAs in para-carcinoma, carcinoma and relapse human pancreatic cancer

Hypoxia: a barricade to conquer the pancreatic cancer

Pancreatic cancer (PC) remains one of the most extremely lethal malignancies worldwide due to late diagnosis and early metastasis, with a 1-year overall survival rate of approximately 20%. The hypoxic microenvironment, induced by intratumoral hypoxia, promotes tumor invasion and progression, leading to chemotherapy or radiotherapy resistance and eventual mortality after treatment of PC. However, the role of the hypoxic microenvironment in PC is complicated and requires further investigation. In this article, we review recent advances regarding the regulation of malignant behaviors in PC, which provide insight into the potential of hypoxic microenvironment activation therapy for the therapeutic agents.

MiR-101 inhibits cell proliferation and invasion of pancreatic cancer through targeting STMN1

MiRNAs regulated most genes expression, which were proved important in various tumors. In this study, we want to investigate miR-101 effect and molecular mechanism on pancreatic cancer (PC), the research about this was blank now. RT-PCR analysis showed that miR-101 expression was declined in PC. MTT assay found that miR-101 mimic suppressed cell viability, while suppressing miR-101 facilitated cell proliferation. Transwell assay showed that miR-101 mimic inhibited cell invasion, but promoted cell invasion by miR-101 inhibitor. With TargetScanHuman's help, we verified STMN1 as a specific target of miR-101 and luciferase reporter assay was carried out to further confirm this discovery. STMN1 expression was reduced by miR-101 mimic and increased by miR-101 inhibitor. We next found that STMN1 was elevated in PC and its expression was negatively correlated with miR-101 expression. Furthermore, STMN1 siRNA curbed cell proliferation and invasion, which was opposite to miR-101 inhibitor effect on PC progression and STMN1 siRNA attenuated miR-101 inhibitor effect on cell proliferation and invasion. In conclusion, miR-101 inhibited PC cell proliferation and invasion via regulating STMN1, which provided a potential therapeutic for PC patients.

MiR-142 modulates human pancreatic cancer proliferation and invasion by targeting hypoxia-inducible factor 1 (HIF-1α) in the tumor microenvironments

MicroRNAs regulate most protein-coding genes, including genes important in cancer and other diseases. In this study, we demonstrated that the expression of miR-142 could be significantly suppressed in pancreatic cancer specimens and cell lines compared to their adjacent tissues and normal pancreatic cells. Growth and invasion of PANC-1 and SW1990 cells were attenuated by overexpression of miR-142 in vitro. With the help of bioinformatics analysis, hypoxia-inducible factor 1 (HIF-1α) was identified to be a direct target of miR-142, and a luciferase reporter experiment confirmed this discovery. Overexpression of miR-142 decreases protein expression of HIF-1α. In the hypoxic microenvironment, HIF-1α was up-regulated while miR-142 was down-regulated. The invaded cells significantly increased in the hypoxic microenvironment compared to the normoxic microenvironment. The hypoxia treatment induced cells’ proliferation, and invasion could be inhibited by miR-142 overexpression or HIF-1α inhibition. Moreover, expression of epithelial-mesenchymal transition (EMT) markers, Vimentin, VEGF-C and E-cad, was altered under hypoxia conditions and regulated by miR-142/HIF-1α. Above all, these findings provided insights on the functional mechanism of miR-142, suggesting that the miR-142/HIF-1α axis may interfere with the proliferative and invasive properties of pancreatic cancer cells, and indicated that miR-142 could be a potential therapeutic target for pancreatic cancer.

Summary: Our findings provide insights to the functional mechanism of miR-142, suggesting that the miR-142/HIF-1α axis may interfere with the proliferative and invasive property of pancreatic cancer cells.

MicroRNA-127 is aberrantly downregulated and acted as a functional tumor suppressor in human pancreatic cancer

Pancreatic carcinoma is one of the most malignant human cancers. In this study, we intended to explore the molecular functional of microRNA-127 (miR-127) in regulating pancreatic cancer development both in vitro and in vivo. Quantitative real-time PCR (qRT-PCR) was performed to evaluate endogenous miR-127 expression in in vitro pancreatic cancer cell lines and in vivo clinical samples of pancreatic carcinoma. Lentiviral technology was applied to overexpress miR-127 in capan-1 and PANC-1 cells. Pancreatic cancer proliferation, cell-cycle progression, and invasion were assessed in vitro, and capan-1-derived tumorigenicity was evaluated in vivo. Dual-luciferase reporter assay and qRT-PCR were performed to assess the downstream target gene of miR-127 in pancreatic cancer, human Bcl-2-associated athanogene 5 (BAG5). BAG5 was subsequently upregulated in miR-127-overexpressed capan-1 and PANC-1 cells to evaluate its effect on pancreatic cancer progression. MiR-127 was preferentially downregulated in both pancreatic carcinoma cell lines and human pancreatic tumors. In lentivirus-infected capan-1 and PANC-1 cells, miR-127 overexpression significantly inhibited cancer progression, cell-cycle transition and invasion in vitro, as well as tumorigenicity in vivo. Human BAG5 was confirmed to be the downstream target of miR-127 in pancreatic cancer. Forced overexpression of BAG5 in capan-1 and PANC-1 cells reversed the tumor-suppressing effect of miR-127 on cancer development. MiR-127 is downregulated and acting as a tumor suppressor in pancreatic carcinoma. The functional regulation of miR-127 in pancreatic carcinoma is very likely through the inverse correlation of its downstream target gene of BAG5.

MicroRNA-140 regulates cell growth and invasion in pancreatic duct adenocarcinoma by targeting iASPP

MicroRNAs are ∼22 nucleotide RNAs processed from RNA hairpin structures that play important roles in regulating protein expression level via binding to mRNA, either suppressing its translation or speeding up its degradation. In humans, they regulate most protein-coding genes, including genes important in cancer and other diseases. In this study, the expression of microRNA-140 (miR-140) was demonstrated to be significantly suppressed in pancreatic duct adenocarcinoma specimens and cell lines, compared with their adjacent normal tissues. With the help of bioinformatics analysis, inhibitor of apoptosis-stimulating protein of p53 (iASPP) was identified to be a direct target of miR-140, and luciferase reporter experiment confirmed this discovery. Overexpression of miR-140 decreases the protein expressions of iASPP, ΔNp63, MMP2, and MMP9. Growth and invasion of PANC-1 cells were attenuated by overexpression of miR-140 in vitro. The suppressive effect of miR-140 on PANC-1 cell line could be partly balanced out by manual overexpression of iASPP. Above all, these findings provided insights into the functional mechanism of miR-140, suggested that the miR-140/iASPP axis may interfere with the proliferative and invasive property of pancreatic duct adenocarcinoma cells, and indicated that miR-140 could be a potential therapeutic target for pancreatic duct adenocarcinoma.