miR-544 inhibits the migration and invasion of anaplastic thyroid cancer by targeting Yin Yang-1

Linc-ROR has a Potential ceRNA Activity for OCT4A by Sequestering miR-335-5p in the HEK293T Cell Line

Linc-ROR has a regulatory role in reprogramming, and the core stem cell transcription factors, OCT4, SOX2, and NANOG, regulate its expression. MicroRNAs (miRNAs) are also a critical constituent of pivotal posttranscriptional regulatory pathways. One of such interactions is a competing endogenous RNA interaction that connects small and long non-coding RNAs with coding transcripts. Here, we aimed to investigate the existence of such associations between OCT4A, Linc-ROR, hsa-miR-335-5p, and hsa-miR-544. Bioinformatic analysis was performed to evaluate the expression status of OCT4A, Linc-ROR, miR-335, and miR-544 throughout differentiation as well as in various differentiated cells. The complete lengths of OCT4A and Linc-ROR, and OCT4A 3'-UTR were cloned in the luciferase reporter vector, and the precursors of miR-335 and miR-544 were cloned in expression vectors. Following the overexpression of miR-335 and miR-544 in the 5637 cell line, the endogenous expression of OCT4A and Linc-ROR was evaluated. Afterward, the expression vectors of miRNAs and the reporter vectors of OCT4A/Linc-ROR were co-transfected in the HEK293T cell line. Via the Dual-Luciferase assay, the effect of the overexpression of miRNAs on their two possible targets (Linc-ROR and OCT4A) was investigated. The bioinformatic analysis demonstrated a relatively similar expression pattern for OCT4A and Linc-ROR, while miR-335 showed a different expression status. Both miR-335 and miR-544 inhibited the endogenous expression of OCT4A. The Dual-Luciferase assay likewise confirmed the inhibitory effect of miR-335 and miR-544 on OCT4A expression. In contrast, the miR-335 inhibitory effect was reversed in the presence of Linc-ROR, resulting in the upregulation of OCT4A. Such evidence suggests that Linc-ROR may compete with OCT4A to interact with miR-335.

Long Non-coding RNA RP11-395G23.3 Acts as a Competing Endogenous RNA of miR-124-3p to Regulate ROR1 in Anaplastic Thyroid Carcinoma

Anaplastic thyroid carcinoma (ATC) is one of the most aggressive human malignancies with poor prognosis. However, the underlying mechanisms of ATC remain to be elucidated. Recently, increasing studies have focused on competitive endogenous RNA (ceRNA) to discover valuable biomarkers for the diagnosis of ATC. The present study identified 705 differentially expressed mRNAs and 47 differentially expressed lncRNAs. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses were also conducted. Additionally, an lncRNA/miRNA/mRNA network was constructed which included 1103 regulatory relations. The upregulation of RP11-395G23.3 in ATC cells was confirmed by quantitative reverse transcription polymerase chain reaction (qRT-PCR). In the loss of function assays, results suggested silencing of RP11-395G23.3 inhibited cell proliferation and induced cell apoptosis. Mechanically, RP11-395G23.3 could increase ROR1 via sponging miR-124-3p as a ceRNA. Moreover, ROR1 expression was decreased with the downregulation of RP11-395G23.3, but was rescued by the co-transfection of the miR-124-3p inhibitor in ATC cells. Our research suggested that the RP11-395G23.3/miR-124-3p/ROR1 axis potentially acted as a potential target for the diagnosis of ATC.

LINC00667/miR-449b-5p/YY1 axis promotes cell proliferation and migration in colorectal cancer

Background

Long non-coding RNAs (lncRNAs) have been defined as vital regulators in the progression of human cancers, including colorectal cancer (CRC). Long intergenic non-protein coding RNA 667 (LINC00667) is a tumor promoter in several cancer types, while its role in CRC remains to be unmasked. This study focused on exploring the potential function and regulatory mechanism of LINC00667 in CRC.

Methods

qRT-PCR analysis was applied to detect the expression of LINC00667 in CRC cells. Loss-of function assays revealed the role of LINC00667 silencing in regulating CRC cell proliferation, apoptosis and migration. In vivo study demonstrated the effect of LINC00667 silencing on CRC cell growth. Mechanism experiments were conducted to determine the upstream or the downstream molecular mechanism of LINC00667 in CRC cells.

Results

LINC00667 was expressed at high level in CRC cells. LINC00667 knockdown significantly inhibited CRC cell growth and migration. YY1 transcription factor induced the upregulation of LINC00667 in CRC cells by transcriptionally activating LINC00667. In addition, miR-449b-5p could interact with LINC00667 in CRC cells. Intriguingly, miR-449b-5p directly targeted to YY1, thus inhibiting YY1 expression. YY1 recovered the CRC cell functions impaired by LINC00667 silencing.

Conclusions

LINC00667 is transcriptionally activated by YY1 and promotes cell proliferation and migration in CRC by sponging miR-449b-5p to upregulate YY1.

The biological implications of Yin Yang 1 in the hallmarks of cancer

Tumorigenesis is a multistep process characterized by the acquisition of genetic and epigenetic alterations. During the course of malignancy development, tumor cells acquire several features that allow them to survive and adapt to the stress-related conditions of the tumor microenvironment. These properties, which are known as hallmarks of cancer, include uncontrolled cell proliferation, metabolic reprogramming, tumor angiogenesis, metastasis, and immune system evasion. Zinc-finger protein Yin Yang 1 (YY1) regulates numerous genes involved in cell death, cell cycle, cellular metabolism, and inflammatory response. YY1 is highly expressed in many cancers, whereby it is associated with cell proliferation, survival, and metabolic reprogramming. Furthermore, recent studies also have demonstrated the important role of YY1-related non-coding RNAs in acquiring cancer-specific characteristics. Therefore, these YY1-related non-coding RNAs are also crucial for YY1-mediated tumorigenesis. Herein, we summarize recent progress with respect to YY1 and its biological implications in the context of hallmarks of cancer.

The Two Sides of YY1 in Cancer: A Friend and a Foe

Yin Yang 1 (YY1), a dual function transcription factor, is known to regulate transcriptional activation and repression of many genes associated with multiple cellular processes including cellular differentiation, DNA repair, autophagy, cell survival vs. apoptosis, and cell division. Owing to its role in processes that upon deregulation are linked to malignant transformation, YY1 has been implicated as a major driver of many cancers. While a large body of evidence supports the role of YY1 as a tumor promoter, recent reports indicated that YY1 also functions as a tumor suppressor. The mechanism by which YY1 brings out opposing outcome in tumor growth vs. suppression is not completely clear and some of the recent reports have provided significant insight into this. Likewise, the mechanism by which YY1 functions both as a transcriptional activator and repressor is not completely clear. It is likely that the proteins with which YY1 interacts might determine its function as an activator or repressor of transcription as well as its role as a tumor suppressor or promoter. Hence, a collection of YY1-protein interactions in the context of different cancers would help us gain an insight into how YY1 promotes or suppresses cancers. This review focuses on the YY1 interacting partners and its target genes in different cancer models. Finally, we discuss the possibility of therapeutically targeting the YY1 in cancers where it functions as a tumor promoter.