Long non‐coding RNA POU6F2‐AS2 promotes cell proliferation and drug resistance in colon cancer by regulating miR‐377/BRD4

Abstract

The aim of this study was to explore the molecular mechanism of lncRNA POU6F2-AS2 in proliferation and drug resistance of colon cancer. Total paired 70 colon cancer and adjacent normal tissues were collected from colon cancer patients.Colon cancer and normal colonic epithelial cells were purchased. POU6F2-AS2 was up-or down-expressed by vectors. LC50 of all cell lines before and after transfection with these plasmids was detected. qRT-PCR was used to detect the expression of POU6F2-AS2, miR-377 and BRD4 before or after transfection. In situ hybridization was also undertaken to detect the level of POU6F2-AS2. Different concentrations of 5-Fu (0, 1, 2.5, 5, 10, 20, 40 and 80 μg/mL) were used for 5-FU insensitivity assay.CCK-8 and crystal violet staining assay were used for detecting cell proliferation, and flow cytometry was used for identifying cell cycle distribution and apoptosis. In order to detect the fragmented DNA in apoptotic cells, TUNEL assay was used. RNA pull-down assay and luciferase reporter assay were used to verify the binding site.Rescue assay confirmed the subtractive effect of miR-377 inhibitors. POU6F2-AS2 was highly expressed in colon cancer, which was associated with clinical pathology. Up-regulated POU6F2-AS2 promoted cell proliferation and cell cycle of colon cancer cells. Overexpression of POU6F2-AS2 inhibited the expression of miR-377 and then up-regulated the expression of BRD4. Up-regulated BRD4 ultimately promoted cell proliferation and cell survival Down-regulated POU6F2-AS2 showed enhanced sensitivity of 5-FU. POU6F2-AS2 promoted cell proliferation and drug resistance in colon cancer by regulating miR-377/BRD4 gene. K E Y W O R D S cell proliferation, colon cancer, drug resistance, LncRNA POU6F2-AS2, miR-377/BRD4 | 4137 XU et al. | INTRODUC TI ONColon cancer is the third gastrointestinal tumour that occurs at the junction of the rectum and the sigmoid colon. 1 The incidence of colon cancer is increased in people aged 40-50, and the ratio is 2 to 3:1 for male: female. 2 In the middle and late stage, patients are always with characters of abdominal distension, indigestion, abdominal pain, mucus or sticky stool. 3 Companying with tumour ulceration, blood loss and toxin absorption, patients show more serious symptoms, including anaemia, hypothermia, fatigue, weight loss and lower extremity oedema. 4 Colon cancer in early stage can be cured by endoscopic minimally invasive treatment, while for middle or late stage, the main treatment method is surgery. 5 Chemotherapy, immunotherapy, traditional Chinese medicine and other supportive treatments are supplement to improve the sur-Highlights 1. LncRNA POU6F2-AS2 is highly expressed in colon cancer, which is associated with clinical pathology. 2. Overexpression of lncRNA POU6F2-AS2 promotes cell proliferation and cell cycle of colon cancer cells. 3. POU6F2-AS2 inhibits the expression of miR-377 and then up-regulates the BRD4 expression. 4. Up-regulated BRD4 ultimately promotes cell prolifera-How to cite this article: Xu G, Zhu H, Xu J, et al. Lo...

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