Overexpression of lncRNA TPT1-AS1 Suppresses Hepatocellular Carcinoma Cell Proliferation by Downregulating CDK2

TPT1 Antisense RNA 1 (TPT1-AS1) is a recently identified tumor oncogenic long non-coding RNA (lncRNA) in ovarian cancer and cervical cancer. This study was carried out to study the role of lncRNA TPT1-AS1 in hepatocellular carcinoma (HCC). Samples of HCC and non-tumor tissues derived from 62 HCC patients were subjected to RNA isolation and reverse transcription quantitative polymerase chain reaction to detect the differential expression of TPT1-AS1 and cyclin dependent kinase 2 (CDK2) in HCC. Correlations between the expression of TPT1-AS1 and CDK2 were analyzed by linear regression. TPT1-AS1 and CDK2 were overexpressed in SNU-398 and SU.86.86 cells to explore their relationship. The role of TPT1-AS1 and CDK2 in regulating the cell cycle progression and proliferation of SNU-398 and SU.86.86 cells was explored by cell cycle assay and cell proliferation assay, respectively. In addition, xenograft tumor formation was also carried out to further verify the TPT1-AS1 role in HCC in vivo. It was found that TPT1-AS1 was downregulated in HCC and inversely correlated with CDK2. The expression of TPT1-AS1 in HCC tissues was not affected by age, sex, AFP, HBV, HCV, and cirrhosis infection but was downregulated by clinical stages. In HCC cells, overexpression of TPT1-AS1 mediated the downregulation of CDK2, while silencing of TPT1-AS1 mediated the upregulation of CDK2. In cell proliferation assay, overexpression of TPT1-AS1 mediated the decreased proliferation rates, while silencing of TPT1-AS1 mediated the increased proliferation rates of HCC cells, while overexpression of CDK2 played an opposite role. In addition, overexpression of TPT1-AS1 reduced tumor growth in vivo. Therefore, overexpression of TPT1-AS1 may suppress HCC cell proliferation by downregulating CDK2.