Basic Study
Copyright ©The Author(s) 2018.
World J Gastroenterol. Mar 7, 2018; 24(9): 1004-1012
Published online Mar 7, 2018. doi: 10.3748/wjg.v24.i9.1004
Figure 1
Figure 1 lncRNA RP4 regulates proliferation, tumor growth, and early apoptosis in colorectal cancer cells. Lentivirus-mediated lncRNA RP4 overexpression and knockdown were performed in the colorectal cancer line SW480, and cell proliferation, tumor growth, and early apoptosis were examined. A: Cell proliferation was examined by the CCK-8 assay. lncRNA RP4 overexpression and knockdown were shown to decrease and increase cell proliferation, respectively. B: Tumor growth was evaluated by tumor volume change. lncRNA RP4 overexpression and knockdown were shown to significantly decrease and increase tumor volume, respectively, at weeks 14, 21, and 28. C: Flow cytometry assessment of early apoptosis. lncRNA RP4 overexpression and knockdown increased and decreased early apoptosis, respectively, in colorectal cancer. D: Early apoptosis quantification. eP < 0.001 for between-group comparisons.
Figure 2
Figure 2 lncRNA RP4 affects the expression of SH3GLB1 in colorectal cancer cells. Lentivirus-mediated lncRNA RP4 overexpression and knockdown were performed in SW480 cells, and SH3GLB1 expression was evaluated by real-time quantitative PCR, followed by association analyses between SH3GLB1 and lncRNA RP4 levels. A: LncRNA RP4 overexpression and knockdown, respectively, increased and decreased SH3GLB1 expression in SW480 cells. B: Correlation analyses revealed a linear association between the expression of SH3GLB1 and lncRNA RP4, with an r2 value of 0.827. aP < 0.05 and eP < 0.001 for between-group comparisons.
Figure 3
Figure 3 lncRNA RP4 functions as an miR-7-5p decoy in colorectal cancer cells. A: The predicted miR-7-5p binding sites on the SH3GLB1 and lncRNA RP4 transcript. B: LncRNA RP4 overexpression and knockdown, respectively, decreased and increased the expression of miR-7-5p in SW480 cells. C: Correlation analyses revealed a linear association between the expression of lncRNA RP4 and miR-7-5p, with an r2 value of 0.482. D: SW480 cells were transfected with an miR-7-5p mimic and inhibitor, and cell proliferation was evaluated by the CCK-8 assay. miR-7-5p overexpression and knockdown increased and decreased cell proliferation, respectively. E. Real-time quantitative PCR showed that miR-7-5p overexpression and knockdown, respectively, decreased and increased SH3GLB1 expression level in SW480 colorectal cancer cells. aP < 0.05, bP < 0.01, and eP < 0.001 for between-group comparisons.
Figure 4
Figure 4 Involvement of the autophagy-mediated cell death pathway and PI3K/Akt signaling pathway in lncRNA RP4-mediated effects in colorectal cancer cells. A: LncRNA RP4 overexpression and knockdown, respectively, decreased and increased expression of the autophagy marker LC3, and apoptosis-related proteins Bax and caspase 3 in SW480 cells, suggesting that it positively regulates autophagy-mediated cell death in colorectal cancer cells. B: LncRNA RP4 overexpression and knockdown, respectively, decreased and increased PI3K and Akt phosphorylation in SW480 cells, indicating that it negatively regulates PI3K/Akt in colorectal cancer cells. C: Schematic of lncRNA RP4 functioning as a decoy by competitively binding miR-7-5p, upregulating the specific repressor SH3GLB1, activating autophagy-mediated cell death, and inhibiting the PI3K/Akt signaling pathway, thereby suppressing colorectal carcinogenesis. aP < 0.05, bP < 0.01, and eP < 0.001 for between-group comparisons.