Abstract：Objective: To investigate the inhibitory effects of long non-coding RNA tumor suppressor candidate 7 (LncRNA TUSC7) on the proliferation, migration, and invasion of colorectal cancer (CRC) via regulation of microRNA-182 (miR-182)/T-box5 (TBX5) axis.Methods: Quantitative real-time PCR was performed to detect the levels of LncRNA TUSC7, miR-182, and TBX5 in 90 pairs of CRC adenocarcinoma tissues and the corresponding adjacent normal tissues, and their correlations were analyzed in clinical samples, as well as the expressions of LncRNA TUSC7 in human CRC cell lines LoVo, SW1116, CaCO2, HCT116 and SW480 and normal human colon mucosal cell line NCM460. RNA fluorescence in situ hybridization was conducted to detect the subcellular localization of LncRNA TUSC7. SW480 cells were divided into 10 groups:TUSC7 knockdown (shTUSC7) group and knockdown control (shNC) group, TUSC7 overexpression (oeTUSC7) group and overexpression control (oeNC) group, miR-182 overexpression (miR-182 mimic) group and overexpression control (NC mimic) group, interference miR-182 (miR-182 inhibitor) group and interference control (NC inhibitor) group, simultaneous overexpression of TUSC7 and miR-182 (oeTUSC7+miR-182) group and simultaneous overexpression of TUSC7, miR-182, and TBX5 (oeTUSC7+miR-182 mimic+oeTBX5) group, transfected with shTUSC7, shNC, oeTUSC7, oeNC, miR-182 mimic, NC mimic, miR-182 inhibitor, NC inhibitor, oeTUSC7+miR-182 mimic, and oeTUSC7+miR-182 mimic+oeTBX5, respectively. The effects of LncRNA TUSC7, miR-182, and TBX5 on cell viability, proliferation, apoptosis, migration, and invasion of SW480 cells were determined by CCK8, clonal formation, flow cytometry, and Transwell assays. Dual luciferase reporter assay, RNA immunoprecipitation, RNA pull-down assay, and Western blot were performed to verify the relationships in LncRNA TUSC7, miR-182, and TBX5. Kaplan-Meier method was used to determine survival analysis. The nude mice were randomly divided into 4 groups (n=12):shTUSC7 group, shNC group, oeTUSC7 group, and oeNC group, which were inoculated subcutaneously with SW480 cells transfected with shTUSC7, shNC, oeTUSC7, and oeNC, respectively, in the right underarm. The effects of LncRNA TUSC7 on tumor growth of CRC and survival analysis were evaluated by xenograft model in vivo.Results: Compared to adjacent normal tissue, LncRNA TUSC7 (1.53±0.84 vs 6.97±3.97) and TBX5 (0.58±0.29 vs 3.25±1.51) were low-expressed, while miR-182 (0.54±0.33 vs 0.09±0.06) was high-expressed in CRC tissues (P<0.05). LncRNA TUSC7 was negatively correlated with miR-182 (R2=0.09077), but positively related to TBX5 (R2=0.08371). miR-182 were negatively associated with TBX5 (R2=0.06914;P<0.05). Compared with NCM460 (1.00±0.05) cells, LncRNA TUSC7 was significantly lower expressed in LoVo (0.51±0.08), SW1116 (0.41±0.10), CaCO2 (0.42±0.11), HCT-116 (0.53±0.10) and SW480 (0.35±0.07) cells (P<0.05). The expression was lowest in SW480 cells. LncRNA TUSC7 was located in the CRC cytoplasm. Compared with the shNC/oeNC group, silencing/overexpression of LncRNA TUSC7 promoted/inhibited the proliferation, migration, and invasion, while decreased/increased apoptosis of CRC cells. LncRNA TUSC7 directly targeted miR-182, and TBX5 was a direct target of miR-182. Mechanistically, LncRNA TUSC7 promoted the expression of TBX5 by targeting miR-182, thus inhibiting the proliferation, migration, and invasion, but promoting apoptosis of CRC cells (P<0.05). Consistent with the results in vitro, LncRNA TUSC7 could inhibit CRC growth in vivo.Conclusion: LncRNA TUSC7 was low expressed in CRC tissues and cells. LncRNA TUSC7 inhibited the proliferation, migration and invasion of CRC cells by regulating the miR-182/TBX5 axis.
2024, Vol. 30 
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