MicroRNAs (miRNAs) are a class of highly conserved, small endogenous single-strand non-coding RNAs. They are aberrantly expressed in the circulation and tissue of patients with cancer. Therefore, it has been suggested that they may act as key regulators of carcinogenesis. The aim of the present study was to examine the expression level of miR-195-5p in human breast cancer and its potential role in carcinogenesis. The expression level of miR-195-5p was measured in 40 breast cancer specimens and adjacent normal breast tissues by quantitative polymerase chain reaction (qPCR). Next, to explore the potential function of miR-195-5p, we used MDA-MB-231 human breast cancer cells and carried out MTT, colony formation, Transwell chamber migration and cell cycle assays. The dual-luciferase reporter assay was also performed to determine putative targets of miR-195-5p, which were validated using qPCR and western blot assays. We found that miR-195-5p expression was significantly decreased in the 40 breast cancer specimens when compared with that in the adjacent normal breast tissues (P<0.05). Overexpression of miR-195-5p inhibited cell proliferation, reduced cell colony formation, suppressed cell migration and caused an accumulation of cells in the G1 phase of the cell cycle. In the 3′-untranslated region (3′-UTR) of cyclin E1 (CCNE1), we found two putative target sites which may bind miR-195-5p, suggesting that CCNE1 is a direct target of miR-195-5p. Furthermore, through qPCR and western blot assays we showed that overexpression of miR-195-5p reduced CCNE1 mRNA and protein levels, respectively. Our study suggests that miR-195-5p may act as a tumor suppressor in breast cancer. Therefore, targeting of this miRNA may provide a novel strategy for the diagnosis and treatment of patients with this lethal disease.
Dysregulation of microRNAs (miRNAs) plays a critical role in cancer progression. They can act as either oncogenes or tumor suppressor genes in human cancer. The purpose of this study was to investigate the crucial role of miR-135b in breast cancer and to validate whether miR-135b could regulate proliferation of breast cancer cells by effecting specific targets in the Hippo pathway. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) was carried out to quantify the expression levels of miR-135b in both breast cancer tissues and cell lines. To characterize the function of miR-135b, MTT assays, colony formation assays, cell migration assays, cell invasion assays, and cell cycle assays were used. Luciferase reporter assays were performed to validate the regulation of a putative target of miR-135b, in corroboration with western blot assays. Finally, we verified the changes of cellular function after transfection of LATS2-siRNA. Our experiments indicate that expression of miR-135b was commonly upregulated in breast cancer specimens and breast cancer cells when compared with that in adjacent normal tissues and non-malignant breast epithelial cells. Enforced expression of miR-135b can regulate cellular proliferation, migration and invasion as well as disrupt the cell cycle of breast cancer cells. Luciferase assays revealed that miR-135b directly bound to the 3'-untranslated region (3'-UTR) of LATS2 (large tumor suppressor kinase 2), a critical gene in the Hippo pathway. Western blot analysis verified that miR-135b regulated the expression of LATS2 at protein levels. Further study demonstrated that the downstream gene of LATS2 in the Hippo pathway, such as cyclin-dependent kinase 2 (CDK2) and Phospho-Yes-associated protein (p-YAP), can also be regulated by miR-135b and LATS2 axis. Knockdown of endogenous LATS2 can mimic the result of miR-135b up-regulation in breast cancer. Taken together, our findings reveal that the miR-135b and LATS2 axis may be a potential therapeutic target for breast cancer in the future.
Triple-negative breast cancer (TNBC) has the worst prognosis of all subtypes of breast cancer (BC), with limited options for conventional therapy and no targeted therapies. MicroRNAs (miRNAs) are small noncoding RNAs that negatively regulate gene expression. In this study, we aimed to determine whether two members of the miR-200 family, miR-200b-3p and miR-429-5p, are involved in BC cell proliferation and motility and to elucidate their target genes and pathways. We performed a meta-analysis that reveals down-regulated expression of miR-200b-3p and miR-429-5p in BC tissues and cell lines, consistent with a lower expression of miR-200b-3p and miR-429-5p in MDA-MB-231 and HCC1937 cells than in MCF-7 and MCF-10 cells. Overexpression of miR-200b-3p and miR-429-5p significantly inhibited the proliferation, migration, and invasion of TNBC cells; suppressed the expression of markers for proliferation and metastasis in TNBC cells. We next demonstrated that LIM domain kinase 1 (LIMK1) is a direct target gene of miR-200b-3p and miR-429-5p. Inhibition of LIMK1 reduced the expression and phosphorylation of cofilin 1 (CFL1), which polymerizes and depolymerizes F-actin and G-actin to reorganize cellular actin cytoskeleton. In addition, transfection with mimics for miR-200b-3p and miR-429-5p arrested G2/M and G0/G1 cell cycles respectively, suppressed the expression of the cell cycle–related complexes, cyclin D1/CDK4/CDK6 and cyclin E1/CDK2, in TNBC cells. In conclusion, miR-200b-3p and miR-429-5p suppress proliferation, migration, and invasion in TNBC cells, via the LIMK1/CFL1 pathway. These results provide insight into how specific miRNAs regulate TNBC progression and suggest that the LIMK1/CFL1 pathway is a therapeutic target for treating TNBC.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.