LINC00665 Affects the Malignant Biological Behavior of Ovarian Cancer via the miR-148b-3p/KLF5

Abstract Objectives: This study was to investigate the expression and clinical significance of long intergenic noncoding RNA 00665 (LINC00665) in ovarian cancer , as well as its effect on malignant biological behavior of ovarian cancer cells. Methods: The expressions of LINC00665, miR-148b-3p and KLF5 in ovarian cancer (OC) tissues and cells were detected by RT-qPCR. Western blotting was used to detect KLF5 expression. The expression patterns of LINC00665, U6 and GAPDH in nuclear and cytoplasm fractions were detected using qRT-PCR. Besides, CCK-8 assay, clone formation assay, transwell, scratch test, and flow cytometry were respectively used to detect the cell activity, proliferation, invasiveness, healing of cells, and apoptosis rate of OC cells. Furthermore, the interactions between LINC00665 and miR-148b-3p and between miR-148b-3p and KLF5 were verified by luciferase reporter assay, and the correlations among these three genes were analyzed.Results: LINC00665 expression was up-regulated in ovarian cancer cell lines and tissues. Si-LINC00665 inhibited cell proliferation, invasion and migration, and induced the apoptosis to a certain extent. Subcellular fraction assay revealed the location of LINC00665 was mainly situated in the cytoplasm. Besides, miR-148b-3p was a target of LINC00665, and KLF5 was directly targeted by miR-148b-3p. Si-LINC00665 inhibited KLF5 expression, miR-148b-3p inhibitor promoted KLF5 expression, and si-KLF5 inhibited LINC00665 expression. Interestingly, expressions of LINC00665 and miR-148b-3p, and expressions of miR-148b-3p and KLF5 were negatively correlated, while expressions of LINC00665 and KLF5 were positively correlated. In addition, si-KLF5 inhibited the malignant biological behavior of ovarian cancer cells, while miR-148b-3p inhibitor had the opposite effect. Most importantly, the si-LINC00665 could reverse the promotion effect of miR-148b-3p inhibitor on the malignant biological behavior of ovarian cancer cells.Conclusions: LINC00665 can be used as an effective prognostic indicator of ovarian cancer, which has the potential to be a new drug target.