MicroRNA-29b-2-5p inhibits cell proliferation by directly targeting Cbl-b in pancreatic ductal adenocarcinoma

• Published in: BMC cancer Vol. 18; no. 1; p. 681
• Main Authors: Li, Ce, Dong, Qian, Che, Xiaofang, Xu, Ling, Li, Zhi, Fan, Yibo, Hou, Kezuo, Wang, Shuo, Qu, Jinglei, Xu, Lu, Wen, Ti, Yang, Xianghong, Qu, Xiujuan, Liu, Yunpeng
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 25.06.2018; BioMed Central; BMC
• Subjects: Adaptor Proteins, Signal Transducing - genetics; Adenocarcinoma; Adenocarcinoma - pathology; Analysis; Animals; Biomarkers; Breast cancer; Cancer therapies; Carcinoma, Pancreatic Ductal - pathology; Care and treatment; Cbl-b; Cbl-b protein; Cell cycle; Cell growth; Cell Line, Tumor; Cell Proliferation; Chemotherapy; Female; G1 Phase Cell Cycle Checkpoints; Gastric cancer; Growth factors; Humans; Leukemia; Lymphoma; Medical prognosis; Mice; Mice, Inbred BALB C; MicroRNA; MicroRNAs; MicroRNAs - physiology; miR-29b-2-5p; miRNA; p53; Pancreas; Pancreatic cancer; Pancreatic Neoplasms - pathology; Patients; PDAC; Prognosis; Proliferation; Proteins; Proto-Oncogene Proteins c-cbl - genetics; Studies; Tumor Suppressor Protein p53 - physiology; Tumors; China; PDAC; Prognosis; Proliferation; Cbl-b; miR-29b-2-5p; p53
• ISSN: 1471-2407; 1471-2407
• DOI: 10.1186/s12885-018-4526-z

MicroRNAs can be used in the prognosis of malignancies; however, their regulatory mechanisms are unknown, especially in pancreatic ductal adenocarcinoma (PDAC). In 120 PDAC specimens, miRNA levels were assessed by quantitative real time polymerase chain reaction (qRT-PCR). Then, the role of miR-29b-2-5p in cell proliferation was evaluated both in vitro (Trypan blue staining and cell cycle analysis in the two PDAC cell lines SW1990 and Capan-2) and in vivo using a xenograft mouse model. Next, bioinformatics methods, a luciferase reporter assay, Western blot, and immunohistochemistry (IHC) were applied to assess the biological effects of Cbl-b inhibition by miR-29b-2-5p. Moreover, the relationship between Cbl-b and p53 was evaluated by immunoprecipitation (IP), Western blot, and immunofluorescence. From the 120 PDAC patients who underwent surgical resection, ten patients with longest survival and ten with shortest survival were selected. We found that high miR-29b-2-5p expression was associated with good prognosis (p = 0.02). The validation cohort confirmed miR-29b-2-5p as an independent prognostic factor in PDAC (n = 100, 95% CI = 0.305-0.756, p = 0.002). Furthermore, miR-29b-2-5p inhibited cell proliferation, induced cell cycle arrest, and promoted apoptosis both in vivo and in vitro. Interestingly, miR-29b-2-5p directly bound the Cbl-b gene, down-regulating its expression and reducing Cbl-b-mediated degradation of p53. Meanwhile, miR-29b-2-5p expression was negatively correlated with Cbl-b in PDAC tissues (r = - 0.33, p = 0.001). Taken together, these findings indicated that miR-29b-2-5p improves prognosis in PDAC by targeting Cbl-b to promote p53 expression, and would constitute an important prognostic factor in PDAC.