Background Melanoma is the most aggressive type of skin cancer with high mortality rate and poor prognosis. lncRNA MEG3, a tumor suppressor, is closely related to the development of various cancers. However, the role of lncRNA MEG3 in melanoma has seldom been studied. Methods RT-PCR was used to examine the expressions of lncRNA MEG3 and E-cadherin in melanoma patients and cell lines. Then, the biological functions of lncRNA MEG3 and E-cadherin were demonstrated by transfecting lncRNA MEG3-siRNA, lncRNA MEG3-overexpression, E-cadherin-siRNA and E-cadherin-overexpression plasmids in melanoma cell lines. Moreover, CCK8 assay and colony formation assay were utilized to assess the cell proliferation; Transwell assay was performed to evaluate the cell invasive ability; and tumor xenografts in nude mice were applied to test the tumor generation. Additionally, the target interactions among lncRNA MEG3, miR-21 and E-cadherin were determined by dual luciferase reporter assay. Finally, RT-PCR and WB were further conducted to verify the regulatory roles among lncRNA MEG3, miR-21 and E-cadherin. Results The clinical data showed that lncRNA MEG3 and E-cadherin expressions were both declined in carcinoma tissues as compared with their para-carcinoma tissues. Moreover, lncRNA MEG3 and E-cadherin expressions in B16 cells were also higher than those in A375 and A2058 cells. Subsequently, based on the differently expressed lncRNA MEG3 and E-cadherin in these human melanoma cell lines, we chose B16, A375 and A2058 cells for the following experiments. The results demonstrated that lncRNA MEG3 could suppress the tumor growth, tumor metastasis and formation; and meanwhile E-cadherin had the same effects on tumor growth, tumor metastasis and formation. Furthermore, the analysis of Kaplan-Meier curves also confirmed that there was a positive correlation between lncRNA MEG3 and E-cadherin. Ultimately, dual luciferase assays were further used to verify that lncRNA MEG3 could directly target miR-21 which could directly target E-cadherin in turn. Additionally, the data of RT-PCR and WB revealed that knockdown of lncRNA MEG3 in B16 cells inhibited miR-21 expression and promoted E-cadherin expression, but overexpression of lncRNA MEG3 in A375 and A2058 cells presented completely opposite results. Conclusion Our findings indicated that lncRNA MEG3 might inhibit the tumor growth, tumor metastasis and formation of melanoma by modulating miR-21/E-cadherin axis.

中文翻译：

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LncRNA MEG3 通过调节 miR-21/E-cadherin 轴促进黑色素瘤的生长、转移和形成。

背景黑色素瘤是最具侵袭性的皮肤癌类型，死亡率高，预后差。lncRNA MEG3是一种抑癌基因，与多种癌症的发生发展密切相关。然而，很少有人研究 lncRNA MEG3 在黑色素瘤中的作用。方法采用RT-PCR检测lncRNA MEG3和E-cadherin在黑色素瘤患者和细胞系中的表达。然后，通过在黑色素瘤细胞系中转染lncRNA MEG3-siRNA、lncRNA MEG3-overexpression、E-cadherin-siRNA和E-cadherin-overexpression质粒来证明lncRNA MEG3和E-cadherin的生物学功能。此外，CCK8测定和集落形成测定用于评估细胞增殖；进行Transwell测定以评估细胞侵袭能力；并在裸鼠中应用肿瘤异种移植物来测试肿瘤的产生。此外，lncRNA MEG3、miR-21 和 E-cadherin 之间的靶标相互作用通过双荧光素酶报告基因测定确定。最后，进一步进行 RT-PCR 和 WB 以验证 lncRNA MEG3、miR-21 和 E-cadherin 之间的调节作用。结果临床资料显示，lncRNA MEG3和E-cadherin在癌组织中的表达均低于癌旁组织。此外，B16 细胞中 lncRNA MEG3 和 E-cadherin 的表达也高于 A375 和 A2058 细胞。随后，基于这些人黑色素瘤细胞系中lncRNA MEG3和E-cadherin的不同表达，我们选择了B16、A375和A2058细胞进行以下实验。结果表明lncRNA MEG3可以抑制肿瘤的生长、转移和形成；同时E-cadherin对肿瘤的生长、转移和形成也有同样的作用。此外，对 Kaplan-Meier 曲线的分析也证实了 lncRNA MEG3 与 E-cadherin 之间存在正相关关系。最终，双荧光素酶检测进一步用于验证 lncRNA MEG3 可以直接靶向 miR-21，而 miR-21 反过来又可以直接靶向 E-cadherin。此外，RT-PCR 和 WB 的数据显示，在 B16 细胞中敲低 lncRNA MEG3 会抑制 miR-21 表达并促进 E-cadherin 表达，但在 A375 和 A2058 细胞中过表达 lncRNA MEG3 呈现完全相反的结果。结论 我们的研究结果表明，lncRNA MEG3 可能通过调节 miR-21/E-cadherin 轴来抑制肿瘤生长、肿瘤转移和黑色素瘤的形成。此外，对 Kaplan-Meier 曲线的分析也证实了 lncRNA MEG3 与 E-cadherin 之间存在正相关关系。最终，双荧光素酶检测进一步用于验证 lncRNA MEG3 可以直接靶向 miR-21，而 miR-21 反过来又可以直接靶向 E-cadherin。此外，RT-PCR 和 WB 的数据显示，在 B16 细胞中敲低 lncRNA MEG3 会抑制 miR-21 表达并促进 E-cadherin 表达，但在 A375 和 A2058 细胞中过表达 lncRNA MEG3 呈现完全相反的结果。结论 我们的研究结果表明，lncRNA MEG3 可能通过调节 miR-21/E-cadherin 轴来抑制肿瘤生长、肿瘤转移和黑色素瘤的形成。此外，对 Kaplan-Meier 曲线的分析也证实了 lncRNA MEG3 与 E-cadherin 之间存在正相关关系。最终，双荧光素酶检测进一步用于验证 lncRNA MEG3 可以直接靶向 miR-21，而 miR-21 反过来又可以直接靶向 E-cadherin。此外，RT-PCR 和 WB 的数据显示，在 B16 细胞中敲低 lncRNA MEG3 会抑制 miR-21 表达并促进 E-cadherin 表达，但在 A375 和 A2058 细胞中过表达 lncRNA MEG3 呈现完全相反的结果。结论 我们的研究结果表明，lncRNA MEG3 可能通过调节 miR-21/E-cadherin 轴来抑制肿瘤生长、肿瘤转移和黑色素瘤的形成。双荧光素酶测定进一步用于验证 lncRNA MEG3 可以直接靶向 miR-21，而 miR-21 反过来又可以直接靶向 E-cadherin。此外，RT-PCR 和 WB 的数据显示，在 B16 细胞中敲低 lncRNA MEG3 会抑制 miR-21 表达并促进 E-cadherin 表达，但在 A375 和 A2058 细胞中过表达 lncRNA MEG3 呈现完全相反的结果。结论 我们的研究结果表明，lncRNA MEG3 可能通过调节 miR-21/E-cadherin 轴来抑制肿瘤生长、肿瘤转移和黑色素瘤的形成。双荧光素酶测定进一步用于验证 lncRNA MEG3 可以直接靶向 miR-21，而 miR-21 反过来又可以直接靶向 E-cadherin。此外，RT-PCR 和 WB 的数据显示，在 B16 细胞中敲低 lncRNA MEG3 会抑制 miR-21 表达并促进 E-cadherin 表达，但在 A375 和 A2058 细胞中过表达 lncRNA MEG3 呈现完全相反的结果。结论 我们的研究结果表明，lncRNA MEG3 可能通过调节 miR-21/E-cadherin 轴来抑制肿瘤生长、肿瘤转移和黑色素瘤的形成。RT-PCR和WB数据显示，敲低lncRNA MEG3在B16细胞中抑制miR-21表达并促进E-cadherin表达，但在A375和A2058细胞中过表达lncRNA MEG3呈现完全相反的结果。结论 我们的研究结果表明，lncRNA MEG3 可能通过调节 miR-21/E-cadherin 轴来抑制肿瘤生长、肿瘤转移和黑色素瘤的形成。RT-PCR和WB数据显示，敲低lncRNA MEG3在B16细胞中抑制miR-21表达并促进E-cadherin表达，但在A375和A2058细胞中过表达lncRNA MEG3呈现完全相反的结果。结论 我们的研究结果表明，lncRNA MEG3 可能通过调节 miR-21/E-cadherin 轴来抑制肿瘤生长、肿瘤转移和黑色素瘤的形成。