Genome-wide association studies have identified several loci associated with pancreatic cancer risk; however, the mechanisms by which genetic factors influence the development of sporadic pancreatic cancer remain largely unknown. Here, by using genome-wide association analysis and functional characterization, we identify a long intergenic noncoding RNA (lincRNA), LINC00673, as a potential tumor suppressor whose germline variation is associated with pancreatic cancer risk. LINC00673 is able to reinforce the interaction of PTPN11 with PRPF19, an E3 ubiquitin ligase, and promote PTPN11 degradation through ubiquitination, which causes diminished SRC-ERK oncogenic signaling and enhanced activation of the STAT1-dependent antitumor response. A G>A change at rs11655237 in exon 4 of LINC00673 creates a target site for miR-1231 binding, which diminishes the effect of LINC00673 in an allele-specific manner and thus confers susceptibility to tumorigenesis. These findings shed new light on the important role of LINC00673 in maintaining cell homeostasis and how its germline variation might confer susceptibility to pancreatic cancer.
Pancreatic cancer has the lowest survival rate among human cancers, and there are no effective markers for its screening and early diagnosis. To identify genetic susceptibility markers for this cancer, we carried out a genome-wide association study on 981 individuals with pancreatic cancer (cases) and 1,991 cancer-free controls of Chinese descent using 666,141 autosomal SNPs. Promising associations were replicated in an additional 2,603 pancreatic cancer cases and 2,877 controls recruited from 25 hospitals in 16 provinces or cities in China. We identified five new susceptibility loci at chromosomes 21q21.3, 5p13.1, 21q22.3, 22q13.32 and 10q26.11 (P = 2.24 × 10(-13) to P = 4.18 × 10(-10)) in addition to 13q22.1 previously reported in populations of European ancestry. These results advance our understanding of the development of pancreatic cancer and highlight potential targets for the prevention or treatment of this cancer.
miRNAs are associated with various types of cancer due to their ability to affect expression of genes that modulate tumorigenesis. In this study, we explored the role of miR-141 in pancreatic cancer. The analysis of clinical characteristics showed that miR-141 was significantly downregulated in tissues and cell lines of pancreatic cancer. Moreover, the decreased miR-141 level was significantly associated with tumor size and TNM stage, as well as lymph node and distant metastasis. Meanwhile, both Kaplan-Meier and multivariate survival analysis showed decreased miR-141 were associated with overall survival. Overexpression of miR-141 in pancreatic cancer cells inhibited cell proliferation, clonogenicity, and invasion; induced G 1 arrest and apoptosis; and enhanced chemosensitivity. To understand how miR-141 mediates the phenotype of pancreatic cancer cells, a bioinformatics tool was used to identify MAP4K4 as a potential target of miR-141. The DualLuciferase reporter gene assay showed that miR-141 binds directly to the 3 0 -untranslated region (3 0 UTR) of MAP4K4 to inhibit MAP4K4 expression. Western blot and quantitative real-time PCR (qRT-PCR) analyses revealed that MAP4K4 expression was inversely correlated with miR-141 expression both in pancreatic cancer samples and cell lines. Knockdown of MAP4K4 inhibited cell proliferation, clonogenicity, and invasion, induced G 1 arrest and apoptosis, and enhanced chemosensitivity. In a nude mouse xenograft model, both overexpression of miR-141 and knockdown of MAP4K4 significantly repressed pancreatic cancer cell growth. Therefore, we conclude that miR-141 targets MAP4K4, acts as a tumor suppressor in pancreatic cancer cells, and may serve as a novel therapeutic agent for miRNA-based pancreatic cancer therapy. Mol Cancer Ther; 12(11); 2569-80. Ó2013 AACR.
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