miR-615-5p is epigenetically inactivated and functions as a tumor suppressor in pancreatic ductal adenocarcinoma.
Pancreatic ductal adenocarcinoma (PDAC) is a highly invasive cancer with a poor prognosis. Although microRNA (miRNA) transcripts have a crucial role in carcinogenesis and development, little information is known regarding the aberrant DNA methylation of miRNAs in PDAC. Using methylated DNA immunoprecipitation-chip analysis, we found that miR-615-5p was hypermethylated in its putative promoter region, which silenced its expression in PDAC cell lines. In addition, the overexpression of miR-615-5p in pancreatic cancer cells suppressed cell proliferation, migration and invasion. Insulin-like growth factor 2 (IGF2) is an imprinted gene, and its abnormal expression contributes to tumor growth. Here, we identified IGF2 as a target of miR-615-5p using a luciferase reporter assay. IGF2 upregulation in PDAC tissues was not correlated with a loss of imprinting but was inversely correlated with miR-615-5p downregulation. In addition, miR-615-5p suppressed pancreatic cancer cell proliferation, migration and invasion by directly targeting IGF2, and this effect could be reversed by co-transfection with IGF2. Furthermore, the stable overexpression of miR-615-5p inhibited tumor growth in vivo and was correlated with IGF2 expression. Using RNA sequencing, we further identified miR-615-5p as potentially targeting other genes, such as the proto-oncogene JUNB, and interfering with the insulin signaling pathway. Taken together, our results demonstrate that miR-615-5p was abnormally downregulated in PDAC cells due to promoter hypermethylation, which limited its inhibition of IGF2 and other target genes, thereby contributing to tumor growth, invasion and migration. These data demonstrate a novel and important role of miR-615-5p as a tumor suppressor in PDAC.
Department of General Surgery, The First Affiliated Hospital with Nanjing Medical University, Nanjing, China.
W
W
Gao
Department of General Surgery, The First Affiliated Hospital with Nanjing Medical University, Nanjing, China.
Y
Y
Gu
Department of General Surgery, The First Affiliated Hospital with Nanjing Medical University, Nanjing, China.
Z
Z
Li
Department of Hepato-Biliary Surgery, The First People's Hospital of Changzhou, Changzhou, China.
H
H
Cai
Department of General Surgery, The PLA 105 Hospital, Hefei, China.
Q
Q
Peng
Department of General Surgery, The First Affiliated Hospital with Nanjing Medical University, Nanjing, China.
M
M
Tu
Division of Epigenomics, Aichi Cancer Center Research Institute, 1-1 Kanokoden, Nagoya, Japan.
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Y
Kondo
Division of Epigenomics, Aichi Cancer Center Research Institute, 1-1 Kanokoden, Nagoya, Japan.
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K
Shinjo
Department of General Surgery, The First Affiliated Hospital with Nanjing Medical University, Nanjing, China.
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Y
Zhu
Department of General Surgery, The First Affiliated Hospital with Nanjing Medical University, Nanjing, China.
J
J
Zhang
Division of Molecular Oncology, Aichi Cancer Center Research Institute, 1-1 Kanokoden, Nagoya, Japan.
Y
Y
Sekido
Department of Endocrinology, Nanjing Children's Hospital Affiliated with Nanjing Medical University, Nanjing, China.
B
B
Han
Department of General Surgery, The First Affiliated Hospital with Nanjing Medical University, Nanjing, China.
Z
Z
Qian
Department of General Surgery, The First Affiliated Hospital with Nanjing Medical University, Nanjing, China.
Y
Y
Miao
D021441:Carcinoma, Pancreatic Ductal / Q000235:genetics* / Q000473:pathology; D045744:Cell Line, Tumor; D002465:Cell Movement; D049109:Cell Proliferation; D019175:DNA Methylation; D044127:Epigenesis, Genetic; D016147:Genes, Tumor Suppressor; D006801:Humans; D007335:Insulin-Like Growth Factor II / Q000235:genetics; D035683:MicroRNAs / Q000502:physiology*; D009361:Neoplasm Invasiveness; D010190:Pancreatic Neoplasms / Q000235:genetics* / Q000473:pathology; D000090063:Proto-Oncogene Mas; D017423:Sequence Analysis, RNA
C000715470:MAS1 protein, human; C534344:MIRN615 microRNA, human; D035683:MicroRNAs; D000090063:Proto-Oncogene Mas; D007335:Insulin-Like Growth Factor II