Background Glycerol kinase 3 pseudogene (GK3P) is a long non-coding RNA (lncRNA) located in the 4q32.3 region of human chromosome. Its parent gene glycerol kinase is related to tumor development. However, the expression and mechanism of lncRNA-GK3P in esophageal cancer are still unclear.
Objective This experiment aims to investigate the expression of lncRNA-GK3P in esophageal cancer tissues and cancer cells, and its effects on the proliferation, cycle, and apoptosis of esophageal cancer EC109 cells.
Methods Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) technology was used to detect expression of lncRNA-GK3P in esophageal cancer cells (EC109), immortalized esophageal epithelial cells (Het-1A), and 41 esophageal cancer tissues and paired adjacent tissues. siRNA technology and plasmid transfection were used to construct lncRNA-GK3P knockdown and lncRNA-GK3P overexpressed EC109 cell lines, respectively. They were divided into four groups: si-GK3P group (siRNA GK3P transfection), si-NC group (siRNA GK3P empty vector control), plasmid-GK3P group (GK3P overexpression plasmid transfection), and plasmid-NC group (GK3P empty plasmid control). CCK8 method was used to detect cell viability, EdU method for the proliferation of EC109 cells, flow cytometry for apoptosis and cycle of EC109 cells, and Western blotting for expression of proteins related to cell cycle and apoptosis (Cyclin E1, Cyclin B1, Bcl2, and Bax).
Results Compared with adjacent tissues, the expression of lncRNA-GK3P in esophageal cancer tissues was 2.91±0.61 times higher (t=19.38, P < 0.05); and compared with esophageal epithelial Het-1A cells, the expression of lncRNA-GK3P in EC109 cells was 3.15±0.27 times higher (t=13.06, P < 0.05). After the knockdown of lncRNA-GK3P, the cell proliferation was inhibitedsi-GK3P group vs si-NC group, (27.21±1.11)% vs (37.95±0.93)%, P < 0.05; the proportion of cells in G0/G1 phase increased (P < 0.05), the proportion of cells in S phase increased (P < 0.05), and the proportion of cells in G2/M phase decreased (P < 0.05); the overall apoptosis rate increasedsi-GK3P group vs si-NC group, (10.19±0.91)% vs (7.46±0.18)%, P < 0.05; moreover, the expressions of Cyclin E1, Cyclin B1, and Bcl2 were down-regulated, while the expression of Bax was up-regulated. After the overexpression of lncRNA-GK3P, the cell proliferation was promotedplasmidGK3P group vs plasmid-NC group, (37.00±1.71)% vs (29.63±1.45)%, P < 0.05; the proportion of G0/G1 phase cells decreased (P < 0.05), the proportion of S phase cells increased (P < 0.05), and the proportion of G2/M phse cells decreased (P < 0.05); the overall apoptosis rate reducedplasmid-GK3P group vs plasmid-NC group, (5.27±0.07)% vs (9.71±0.19)%, P < 0.05; furthermore, the expressions of Cyclin E1, Cyclin B1, and Bcl2 were up-regulated, and the expression of Bax was down-regulated.
Conclusion LncRNA-GK3P is highly expressed in esophageal cancer, and it promotes proliferation and inhibits apoptosis in EC109 cells by regulating the expressions of Cyclin E1, Cyclin B1, Bcl2, and Bax.
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