Background: Recent studies have emphasized determining the ability of microRNAs (miRNAs) as crucial regulators in the occurrence and development of pancreatic cancer (PC), which continues to be one of the deadliest malignancies with few effective therapies. The study aimed to investigate the functional role of miR-135b and its associated mechanism to unravel the biological characteristics of tumor growth in pancreatic cancer stem cells (PCSCs). Methods: Microarray analyses were initially performed to identify the PC-related miRNAs and genes. The expression of miR-135b and PCSC markers in PC tissues and cells was determined by RT-qPCR and western blot analysis, respectively. The potential gene (JADE-1) that could bind to miR-135b was confirmed by the dual-luciferase reporter assay. To investigate the tumorigenicity, migration, invasion, and stemness of PC cells, several gain-of-function and loss-offunction genetic experiments were conducted. Finally, tumor formation in nude mice was conducted to confirm the results in vivo. Results: miR-135b was highly-expressed in PC tissues and PCSCs, which was identified to specifically target JADE-1. The overexpression of miR-135b promoted proliferation, migration, and invasion of PCSC, inhibited cell apoptosis and increased the expression of stemness-related factors (Sox-2, Oct-4, Nanog, Aldh1, and Slug). Moreover, miR-135b could promote the expression of phosphorylated AKT and phosphorylated mTOR in the AKT/mTOR pathway. Additionally, miR-135b overexpression accelerated tumor growth in nude mice. Conclusions: Taken together, the silencing of miR-135b promotes the JADE-1 expression, which inactivates the AKT/mTOR pathway and ultimately results in inhibition of self-renewal and tumor growth of PCSCs. Hence, this study contributes to understanding the role of miR-135 in PCSCs and its underlying molecular mechanisms to aid in the development of effective PC therapeutics.

Backround: Pancreatic ductal adenocarcinoma (PDAC) is the most common and deadly cancer. Surgical resection is the only possible cure for pancreatic cancer but often has a poor prognosis, and the role of adjuvant therapy is urgently explored. Methods: MicroRNAs (miRNAs) play very important role in tumorigenesis by regulating the target genes. In this study, we identified miR-320b lower-expressed in human pancreatic cancer tissues but relatively higher-expressed in the adjacent nontumor tissues. Results: Consistently，the expression of miR-320b in different pancreatic cancer cell lines was significantly lower than the normal pancreatic cells. In order to identify the effects of miR-320b on cell growth, we overexpressed miR-320b in PANC-1 and FG pancreatic cancer cell lines, CCK8 and BrdU incorporation assay results showed that miR-320b inhibited cell proliferation. Discussion: We next predicted miR-20b targeted FOXM1（Forkhead box protein M1）and identified the negative relationship between miR-320b and FOXM1.We also demonstrated that elevated miR-320b expression inhibited tumor growth in vivo. Conclusion: All of these results showed that miR-320b suppressed pancreatic cancer cells proliferation by targeting FOXM1, which might provide a new diagnostic marker for pancreatic cancer.

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