Epigenetic regulation of LINC01270 in breast cancer progression by mediating LAMA2 promoter methylation and MAPK signaling pathway.

Application of long non-coding RNAs (lncRNAs) for modulation of breast cancer (BC) has attracted much attention. Here, we probed into the role and underlying mechanism of long intergenic non-coding RNA 01270 (LINC01270) in BC. With the help of bioinformatics tools, we identified laminin subunit alpha 2 (LAMA2) as a BC-related differentially expressed gene to discern the effect of LAMA2 in BC cells. LAMA2 was initially poorly expressed while LINC01270 was highly expressed in BC. BC cells were subsequently treated with sh-LINC01270 or/and sh-LAMA2 for exploration of their regulatory mechanism in BC, which unfolded that LINC01270 inhibition up-regulated LAMA2 and inactivated the MAPK signaling pathway to suppress malignant characteristics of BC cells. Functional assays demonstrated that LINC01270 bound to DNMT1, DNMT3a, and DNMT3b promoted the methylation of CpG islands in LAMA2 promoter and inhibited the LAMA2 expression. Moreover, our data suggested that LAMA2 suppressed MAPK signaling pathway to inhibit BC cell malignant characteristics. The in vitro results were re-produced with the help of the in vivo experimentations. In conclusion, LINC01270 silencing inhibited the methylation of LAMA2 promoter to suppress the activation of MAPK signaling pathway, which subsequently restrained the BC progression. 1, Overexpression of LAMA2 inhibits malignant features of BC cells. 2, LINC01270 promotes LAMA2 promoter methylation by recruiting DNMTs to the LAMA2 promoter region. 3, 5-aza-dc reverses the promotion of LAMA2 promoter methylation by LINC01270. 4, LAMA2 inhibits malignant features of BC cells by suppressing the activation of MAPK signaling pathway.

MicroRNA-4500 Inhibits Migration, Invasion, and Angiogenesis of Breast Cancer Cells via RRM2-Dependent MAPK Signaling Pathway.

With the consideration of the dynamic role of microRNAs (miRNAs) in breast cancer, miRNAs may serve as therapeutic targets, helping to prevent development of therapy resistance, maintain stable disease, and prohibit metastatic spread. We identified the differentially expressed breast cancer-related gene ribonucleotide reductase subunit M2 (RRM2) as the study focus through microarray expression profiles. Next, the upstream regulatory microRNA (miR)-4500 of RRM2 was predicted using bioinformatics website analysis, and their binding was verified by a dual luciferase reporter gene assay. The regulatory effects of miR-4500 on breast cancer cell proliferation, apoptosis, migration, invasion, and capillary-like tube formation of endothelial cells were assessed by gain- and loss-of-function experiments. The experimental data revealed that miR-4500 was downregulated, whereas RRM2 was upregulated in breast cancer cells. Mechanistic analysis revealed that miR-4500 downregulated the RRM2 expression to inactivate the mitogen-activated protein kinase (MAPK) signaling pathway. Furthermore, miR-4500 exerted anti-tumor effects by targeting RRM2 through suppression of the MAPK signaling pathway in vitro, evidenced by attenuated cancer cell migration and invasion and capillary-like tube formation of endothelial cells. The in vivo experiments further corroborated in vitro results. Collectively, overexpressed miR-4500 could downregulate RRM2 and inhibit activation of the MAPK signaling pathway, thus attenuating breast cancer cell proliferation, invasion, migration, and angiogenesis and promoting breast cancer cell apoptosis.

Down-regulated long non-coding RNA RNAZFHX4-AS1 suppresses invasion and migration of breast cancer cells via FAT4-dependent Hippo signaling pathway.

Breast cancer is ranked as the second leading cause of cancer-related deaths among women. Accumulating evidences have revealed that long non-coding RNAs (lncRNAs) are involved in human tumorigenesis owing to the regulation of essential pathways for tumor initiation and progression. Herein, the current study aimed to explore the regulatory mechanism of lncRNA ZFHX4-AS1 in breast cancer in relation to the Hippo signaling pathway. Initially, microarray analysis was conducted to screen out differentially expressed lncRNAs related to breast cancer. Next, the functional role of lncRNA ZFHX4-AS1 in breast cancer was determined using ectopic expression, knockdown, and reporter assay experiments. Subsequently, lncRNA ZFHX4-AS1, TAF4, TAZ, and YAP expressions were determined, followed by verification of the targeting relationship between lncRNA ZFHX4-AS1 and TAF4. Then cell proliferation, invasion, migration, cell cycle, and apoptosis were measured. Lastly, tumor growth and metastasis were detected by tumor xenograft in nude mice. LncRNA ZFHX4-AS1 was found to be highly expressed while FAT4 was poorly expressed in breast cancer tissues. FAT4 was the target gene of lncRNA ZFHX4-AS1, and lncRNA ZFHX4-AS1 silencing increased FAT4 expressions, while decreased YAP and TAZ expressions. In addition, knockdown of lncRNA ZFHX4-AS1 suppressed breast cancer cell proliferation, migration, and invasion as well as tumor growth, blocked cell cycle entry, while promoted cell apoptosis by inhibiting the Hippo signaling pathway. In conclusion, our findings reveal that lncRNA ZFHX4-AS1 silencing exerts an inhibitory effect on breast cancer development by suppressing the activation of the Hippo signaling pathway via FAT4.