MicroRNA-224 is downregulated in mucinous cystic neoplasms of the pancreas and may regulate tumorigenesis by targeting Jagged1

miR‑224‑5p regulates the proliferation, migration and invasion of pancreatic mucinous cystadenocarcinoma by targeting PTEN

Pancreatic mucinous cystadenocarcinoma (MCC) is a rare malignant tumor, with a limited number of studies. The present study aimed to investigate the function and mechanism of microRNA (miR)-224-5p on proliferation, migration and invasion of MCC of the pancreas. Reverse transcription-quantitative PCR was used to explorethe expression of miR-224-5p and the PTEN gene. MTT, wound healing, Transwell and tumorigenesis assays were conducted to investigate the proliferation, migration and invasion of MCC1 cells in vitro and in vivo. Western blot analysis was employed to test the protein expression of PTEN. The target gene of miR-224-5p was assessed and verified by luciferase assay. miR-224-5p expression was notably higher, while PTEN expression was lower, in MCC1 cells compared with normal tissues and cells. Overexpression of miR-224-5p promoted the proliferation, migration and invasion of MCC and knockdown of miR-224-5p inhibited these functions. Bioinformatics analysis and luciferase assay indicated that PTEN was the direct target gene of miR-224-5p. The negative correlation between miR-224-5p and PTEN was confirmed both in vitro and in vivo. PTEN reversed the effects of miR-224-5p on proliferation, migration and invasion of MCC1 cells. The present study revealed for the first time, to the best of the authors' knowledge, that miR-224-5p was highly expressed and served an oncogenic role in MCC. miR-224-5p not only regulated the proliferation, migration and invasion of pancreatic MCC but may also be a potential therapeutic target for MCC.

Autophagy promotes malignant migration and invasion via miR-224-5p/BCL2 in pancreatic mucinous cystadenocarcinoma MCC1 cells

The prognosis of invasive pancreatic mucinous cystadenocarcinoma (MCC) is poor, and the molecular mechanism underlying its development remains unclear. The present study aimed to explore the potential role of autophagy in pancreatic MCC. The results demonstrated an increase in autophagy signaling in pancreatic MCC tissues and the MCC1 cell line compared with adjacent tissues and normal human pancreatic ductal epithelium (HPDE) cells. In addition, abnormal autophagy activation facilitated the migration and invasion of MCC1 cells. MicroRNA (miR)-224-5p expression levels were significantly higher in MCC1 cells compared with those in HPDE cells. Treatment with rapamycin further demonstrated that high levels of autophagy elevated miR-224-5p expression in MCC1 cells in a time-dependent manner. BCL2 was identified as a downstream target gene of miR-224-5p, which binds to the 3′-untranslated region of BCL2. In addition, the results of the present study demonstrated that BCL2 knockdown reversed the inhibition of autophagy mediated by the miR-224-5p inhibitor. To the best of our knowledge, this is the first study to evaluate the role of autophagy in pancreatic MCC. Thus, these results suggested that autophagy may be hyperactivated in pancreatic MCC. In addition, the present study identified a positive feedback loop between autophagy signaling and miR-224-5p, which may promote the aggressive migration and invasion of MCC1. These results may provide a new insight into the relationship between autophagy and tumor metastasis in pancreatic MCC.

The oncogenic role of Jagged1/Notch signaling in cancer

Aberrant activation of Notch signaling plays an oncogenic role in cancer development. Jagged1 (JAG1) is an important Notch ligand that triggers Notch signaling through cell-cell interactions. JAG1 overexpression has been reported in many different types of cancer and correlates with a poor clinical prognosis. JAG1/Notch signaling controls oncogenic processes in different cell types and cellular contexts. Furthermore, JAG1/Notch signaling cascades activate a number of oncogenic factors that regulate cellular functions such as proliferation, metastasis, drug-resistance, and angiogenesis. To suppress the severe toxicity of pan-Notch inhibitors, JAG1 is attracting increasing attention as a source of therapeutic targets for cancers. In this review, the oncogenic role of JAG1/Notch signaling in cancer is discussed, as well as implications of strategies to inhibit JAG1/Notch signaling activity.

Crosstalk between the Notch signaling pathway and non-coding RNAs in gastrointestinal cancers

The Notch signaling pathway is one of the main signaling pathways that mediates direct contact between cells, and is essential for normal development. It regulates various cellular processes, including cell proliferation, apoptosis, migration, invasion, angiogenesis and metastasis. It additionally serves an important function in tumor progression. Non-coding RNAs mainly include small microRNAs, long non-coding RNAs and circular RNAs. At present, a large body of literature supports the biological significance of non-coding RNAs in tumor progression. It is also becoming increasingly evident that cross-talk exists between Notch signaling and non-coding RNAs. The present review summarizes the current knowledge of Notch-mediated gastrointestinal cancer cell processes, and the effect of the crosstalk between the three major types of non-coding RNAs and the Notch signaling pathway on the fate of gastrointestinal cancer cells.