MiR-497 inhibits cell proliferation and invasion ability by targeting HMGA2 in pancreatic ductal adenocarcinoma

Long non-coding RNA ZFAS1 promotes pancreatic cancer proliferation and metastasis by sponging miR-497-5p to regulate HMGA2 expression

The lncRNA ZFAS1 plays a carcinogenic regulatory role in many human tumours, but it is rarely reported in pancreatic cancer. We identify the role and molecular mechanisms of ZFAS1 in pancreatic cancer. The expression of ZFAS1, miR-497-5p and HMGA2 in pancreatic cancer tissues was detected by qRT-PCR. Pancreatic cancer data in The Cancer Genome Atlas were also included in this study. CCK8, EdU, transwell and scratch wound assays were used to investigate the biological effects of ZFAS1 in pancreatic cancer cells. MS2-RIP, RNA pull-down, RNA-ChIP and luciferase reporter assays were used to clarify the molecular biological mechanisms of ZFAS1 in pancreatic cancer. The role of ZFAS1 in vivo was also confirmed via xenograft experiments. ZFAS1 was overexpressed in pancreatic cancer tissues. ZFAS1 promoted the growth and metastasis of pancreatic cancer cells, and miR-497-5p acted as a tumour suppressor gene in pancreatic cancer by targeting HMGA2. We also demonstrated that ZFAS1 exerts its effects by promoting HMGA2 expression through decoying miR-497-5p. We also found that ZFAS1 promoted the progression of pancreatic cancer in vivo by modulating the miR-497-5p/HMGA2 axis. In conclusion, this study revealed a new role for and the molecular mechanisms of ZFAS1 in pancreatic cancer, identifying ZFAS1 as a novel target for the diagnosis and treatment of pancreatic cancer.

HMGA2 as a Critical Regulator in Cancer Development

The high mobility group protein 2 (HMGA2) regulates gene expression by binding to AT-rich regions of DNA. Akin to other DNA architectural proteins, HMGA2 is highly expressed in embryonic stem cells during embryogenesis, while its expression is more limited at later stages of development and in adulthood. Importantly, HMGA2 is re-expressed in nearly all human malignancies, where it promotes tumorigenesis by multiple mechanisms. HMGA2 increases cancer cell proliferation by promoting cell cycle entry and inhibition of apoptosis. In addition, HMGA2 influences different DNA repair mechanisms and promotes epithelial-to-mesenchymal transition by activating signaling via the MAPK/ERK, TGFβ/Smad, PI3K/AKT/mTOR, NFkB, and STAT3 pathways. Moreover, HMGA2 supports a cancer stem cell phenotype and renders cancer cells resistant to chemotherapeutic agents. In this review, we discuss these oncogenic roles of HMGA2 in different types of cancers and propose that HMGA2 may be used for cancer diagnostic, prognostic, and therapeutic purposes.

circUBAP2 regulates osteosarcoma progression via the miR‑204‑3p/HMGA2 axis

Circular RNA (circRNA/circ)-ubiquitin associated protein 2 (UBAP2), a newly recognized circRNA, serves a functional role in several types of tumor, including ovarian cancer, colorectal cancer and osteosarcoma. However, the precise roles and molecular mechanism under-lying circUBAP2 in osteosarcoma (OS) are not completely understood. In the present study, the expression levels of circUBAP2, microRNA (miR)-204-3p and (HMGA2) were evaluated via reverse transcription-quantitative PCR in OS tissues and cells. OS cell proliferation, migration, invasion and apoptosis were assessed by performing Cell Counting Kit-8, Transwell and flow cytometry assays, respectively. HMGA2 protein expression levels were determined via western blot-ting. Dual-luciferase reporter assays were performed to verify the interaction between circUBAP2 and miR-204-3p, and between miR-204-3p and HMGA2. An RNA immunoprecipitation (RIP) assay was conducted to confirm the interaction between circUBAP2 and miR-204-3p. The results demonstrated that circUBAP2 expression was significantly upregulated in OS tissues and cell lines compared with para-cancerous tissues and hFOB1.19 cells, respectively. In addition, high circUBAP2 expression levels in patients with OS were associated with a lower survival rate compared with lower expression levels in patients with OS. The functional assays revealed that circUBAP2 knockdown significantly inhibited OS cell proliferation, migration and invasion, but increased OS cell apoptosis compared with the small interfering RNA-negative control (si-NC) group. The dual-luciferase reporter and RIP assay results confirmed that circUBAP2 bound to miR-204-3p. Moreover, miR-204-3p expression was significantly downregulated in OS tissues compared with paracancerous tissues, and miR-204-3p expression was negatively correlated with circUBAP2 expression in OS tissues. Collectively, the results demonstrated that miR-204-3p was associated with circUBAP2 knockdown-mediated inhibition of OS cell malignant behavior. Moreover, miR-204-3p was also identified as one of the direct targets of HMGA2. Collectively, the results indicated that compared with the si-NC group, circUBAP2 knockdown significantly inhibited OS cell malignant behavior by binding to miR-204-3p, which subsequently regulated HMGA2 expression. Therefore, the present study demonstrated that circUBAP2 expression was upregulated in OS, and circUBAP2 regulated OS cell malignant behavior via the miR-204-3p/HMGA2 axis.