Bolong Liu1, Pingbo Yao2, Feng Xiao3, Jianjin Guo4, Lianghui Wu5, Yong Yang6. 1. Department of Andrology, The First Affiliated Hospital of University of South China, Hengyang, 421001, Hunan, China. 2. Changsha Social Work College, Changsha, 421004, Hunan, China. 3. Department of Oncology, The Second Hospital of Shanxi Medical University, Taiyuan, 030001, Shanxi, China. 4. Department of Endocrinology and Metabolism, The Second Hospital of Shanxi Medical University, Taiyuan, 030001, Shanxi, China. 5. Department of Intensive Care Unit, Affiliated Nanhua Hospital, University of South China, No. 336, Dongfeng South Road, Zhuhui District, Hengyang, 421001, Hunan, China. wulianghui20051217@163.com. 6. Department of General Surgery, The Second Hospital, University of South China, 30 Jiefang Road, Shigu District, Hengyang, 421001, Hunan, China. maji1177@sina.com.
Abstract
BACKGROUND: In recent years, long non-coding RNAs (lncRNAs) have attracted much attention because of its regulatory role in occurrence and progression of tumors, including triple-negative breast cancer (TNBC). LncRNA PITPNA antisense RNA 1 (PITPNA-AS1) has been explored in some cancers, whereas its function and molecular mechanism in TNBC remain unclear. METHODS: PITPNA-AS1 expression in TNBC tissues and cells was determined by RT-qPCR. TNBC cell viability, proliferation, migration, invasion were assessed with CCK-8, colony formation, wound healing, transwell assays. Cell apoptosis was evaluated by flow cytometry. Expression of EMT-related markers was detected by western blot analyses. The molecular mechanism of PITPNA-AS1 was explored by RNA pull down, luciferase reporter, RIP and ChIP assays. RESULTS: PITPNA-AS1 showed high expression levels in TNBC tissues and cells. PITPNA-AS1 knockdown suppressed TNBC cell viability, proliferation, migration, invasion in vitro and inhibited xenograft tumor growth in mice. Mechanistically, PITPNA-AS1 upregulated SIK2 expression by sponging miR-520d-5p and recruiting DDX54 protein. Results of rescue assays suggested that the inhibitive effects of silenced PITPNA-AS1 on TNBC cellular processes were partially rescued by overexpressing SIK2 or combination of miR-520d-5p inhibition and DDX54 overexpression. More importantly, we found that the upregulation of PITPNA-AS1 in TNBC cells was attributed to transcription factor MYBL2. CONCLUSION: PITPNA-AS1 activated by MYBL2 plays an oncogenic role in TNBC through upregulating SIK2.
BACKGROUND: In recent years, long non-coding RNAs (lncRNAs) have attracted much attention because of its regulatory role in occurrence and progression of tumors, including triple-negative breast cancer (TNBC). LncRNA PITPNA antisense RNA 1 (PITPNA-AS1) has been explored in some cancers, whereas its function and molecular mechanism in TNBC remain unclear. METHODS:PITPNA-AS1 expression in TNBC tissues and cells was determined by RT-qPCR. TNBC cell viability, proliferation, migration, invasion were assessed with CCK-8, colony formation, wound healing, transwell assays. Cell apoptosis was evaluated by flow cytometry. Expression of EMT-related markers was detected by western blot analyses. The molecular mechanism of PITPNA-AS1 was explored by RNA pull down, luciferase reporter, RIP and ChIP assays. RESULTS:PITPNA-AS1 showed high expression levels in TNBC tissues and cells. PITPNA-AS1 knockdown suppressed TNBC cell viability, proliferation, migration, invasion in vitro and inhibited xenograft tumor growth in mice. Mechanistically, PITPNA-AS1 upregulated SIK2 expression by sponging miR-520d-5p and recruiting DDX54 protein. Results of rescue assays suggested that the inhibitive effects of silenced PITPNA-AS1 on TNBC cellular processes were partially rescued by overexpressing SIK2 or combination of miR-520d-5p inhibition and DDX54 overexpression. More importantly, we found that the upregulation of PITPNA-AS1 in TNBC cells was attributed to transcription factor MYBL2. CONCLUSION:PITPNA-AS1 activated by MYBL2 plays an oncogenic role in TNBC through upregulating SIK2.