Overexpression of microRNA­21 inhibits the growth and metastasis of melanoma cells by targeting MKK3.

Melanoma is an aggressive skin carcinoma with poor prognosis, and is prevalent worldwide. It was demonstrated that microRNA (miR)­21 and mitogen­activated protein kinase kinase 3 (MKK3) both participated in the occurrence and development of various tumors; however, their detailed roles in the progression of melanoma remain unclear. Reverse transcription­quantitative PCR (RT­qPCR) and western blot analyses were conducted to examine the expression levels of miR­21 and MKK3 in clinical specimens of patients with melanoma and melanoma cell lines. A dual­luciferase reporter assay was performed to verify the target interaction between miR­21 and MKK3. The mRNA and protein expressions of MKK3 were measured using RT­qPCR and western blot analysis, respectively, following transfection with miR­21 mimics and inhibitor. Subsequently, Cell Counting Kit­8 and colony formation assays, and flow cytometry were conducted to assess the effects of miR­21 and MKK3 on the cell growth of melanoma. Cell migration and invasion experiments were performed to evaluate the effects of miR­21 and MKK3 on the cell metastasis of melanoma. It was revealed that MKK3 was upregulated, and miR­21 was downregulated in patients with melanoma and melanoma cell lines. MKK3 was demonstrated to be a direct target of miR­21. Furthermore, it was demonstrated that upregulated miR­21 expression and downregulated MKK3 expression suppressed cell proliferation and colony formation, promoted apoptosis, delayed the cell cycle, and inhibited cell migration and invasion. The present findings suggested that miR­21 could inhibit the cell growth and metastasis of melanoma by negatively regulating MKK3.

Long non-coding RNA GAS5 regulates human B lymphocytic leukaemia tumourigenesis and metastasis by sponging miR-222.

Accumulating evidence has shown that lncRNA GAS5 is a novel tumour-promoting RNA that contributes to tumour progression by sponging miRNAs. However, the detailed role of lncRNA GAS5 in B lymphocytic leukaemia is still unclear. A qRT-PCR assay was used to examine the levels of lncRNA GAS5 and miR-222 in leukomonocytes of patients with B lymphocytic leukaemia and in healthy donors. Raji cells were transfected with GAS5 overexpression or shRNA-GAS5 plasmids for 48⁢h, and cell proliferation was assessed by the CCK-8 assay, while apoptosis and cell cycle progression were assessed using flow cytometry. The Transwell assay was applied to detect the invasion of Raji cells with GAS5 overexpression or knockdown. The dual luciferase reporter assay and regression curve were conducted to evaluate the binding interaction between lncRNA GAS5 and miR-222. The results showed that the expression of lncRNA GAS5 was decreased in B lymphocytic leukaemia patients compared with the healthy group, and the levels of lncRNA GAS5 in B lymphocytic leukaemia cell lines were significantly higher than those in the normal B cell line, whereas the levels of miR-222 were increased in B lymphocytic leukaemia patients compared with the healthy group. Moreover, cell culture experiments indicated that lncRNA GAS5 overexpression decreased B lymphocytic leukaemia cell proliferation, promoted B lymphocytic leukaemia cell apoptosis, arrested B lymphocytic leukaemia cells in the G1 phase of the cell cycle, and inhibited B lymphocytic leukaemia cell invasion. Finally, the luciferase reporter assay showed a direct target interaction between lncRNA GAS5 and miR-222. The regression analysis showed a negative correlation between the levels of lncRNA GAS5 and miR-222. Thus, our data suggested that lncRNA GAS5 could effectively sponge miR-222 to modulate human B lymphocytic leukaemia cell tumourigenesis and metastasis. This work advances our understanding of the clinical significance of lncRNA GAS5 from the perspective of lncRNA-miRNA regulation.