Long Non-coding RNA MRUL Contributes to Osteosarcoma Progression Through the miR-125a-5p/FUT4 Axis

Osteosarcoma in a ceRNET perspective

Osteosarcoma (OS) is the most prevalent and fatal type of bone tumor. It is characterized by great heterogeneity of genomic aberrations, mutated genes, and cell types contribution, making therapy and patients management particularly challenging. A unifying picture of molecular mechanisms underlying the disease could help to transform those challenges into opportunities.This review deeply explores the occurrence in OS of large-scale RNA regulatory networks, denominated "competing endogenous RNA network" (ceRNET), wherein different RNA biotypes, such as long non-coding RNAs, circular RNAs and mRNAs can functionally interact each other by competitively binding to shared microRNAs. Here, we discuss how the unbalancing of any network component can derail the entire circuit, driving OS onset and progression by impacting on cell proliferation, migration, invasion, tumor growth and metastasis, and even chemotherapeutic resistance, as distilled from many studies. Intriguingly, the aberrant expression of the networks components in OS cells can be triggered also by the surroundings, through cytokines and vesicles, with their bioactive cargo of proteins and non-coding RNAs, highlighting the relevance of tumor microenvironment. A comprehensive picture of RNA regulatory networks underlying OS could pave the way for the development of innovative RNA-targeted and RNA-based therapies and new diagnostic tools, also in the perspective of precision oncology.

Silencing FUT4 Inhibits the Progression of Osteosarcoma through Activation of FOXO1

BACKGROUND

It has been reported that inhibition of Fucosyltransferase4 (FUT4) to activate Forkhead box O1 (FOXO1) can lead to apoptosis of cancer cells, however, the mechanism in osteosarcoma is still unclear.

OBJECTIVE

To explore the biological significance of the connection between FUT4 and FOXO1 in osteosarcoma growth.

METHODS

In vitro tests were conducted using the human osteoblast cell line and the osteosarcoma cell lines. QRT-PCR assay as well as western blot assay were used to ascertain the relative expression levels of FUT4 and FOXO1 in the cells. By using the CCK-8 assay, colony assay, EDU assay, wound healing assay and Transwell assay, osteosarcoma cells' ability to proliferate, migrate and invade were examined in relation to si- FUT4. TUNEL test was used to evaluate Si-impact FUT4's on KHOS and U2OS apoptosis in osteosarcoma cells. Western blot assay was used to identify the expression of proliferative, migrating and apoptosis-related protein markers in osteosarcoma cells KHOS and U2OS and the expression of important proteins in the Wnt/ β-catenin signaling pathway.

RESULTS

In comparison with osteoblasts, osteosarcoma cells expressed more FUT4. The osteosarcoma cells' capacities to proliferate, invade, and migrate were markedly inhibited by the inhibition of FUT4 expression, which also increased osteosarcoma cell apoptosis. The Wnt/β-catenin signaling pathway was blocked by upregulating FOXO1 expression, which was in turn inhibited by inhibiting FUT4 expression.

CONCLUSION

Osteosarcoma cells express more FUT4. The Wnt/β-catenin signaling pathway has a significant effect on osteosarcoma cell death, and inhibition of FUT4 expression may target FOXO1 activation to decrease osteosarcoma cells' ability to proliferate, invade, and migrate.

Overexpression of miR-125a-5p Inhibits Hepatocyte Proliferation through the STAT3 Regulation In Vivo and In Vitro

microRNAs (miRNAs) are critically involved in liver regeneration (LR). miR-125a-5p (miR-125a) is a tumor-suppressing miRNA, but its role in LR has not been studied. Our previous studies have proved that miR-125a was related to LR at the initiation phase, while the mechanism hepatocyte proliferation triggered by miR-125a in LR has been rarely evaluated. Herein, we mainly studied the molecular mechanism of miR-125a in triggering hepatocyte proliferation and the proliferation stage of LR. Firstly, a striking reduction of miR-125a was found at 24 h as well as 30 h following partial hepatectomy (PH) in rat liver tissue by miRNAs expression profiles as well as qRT-PCR analysis. Furthermore, in vitro, upregulation of miR-125a decreased proliferation as well as G1/S conversion, which promoted hepatocytes apoptosis. STAT3 was the target of miR-125a. In vivo, upregulation of miR-125a by tail vein injection of agomir inhibited LR index. Upregulation of miR-125a inhibited LR index and hepatocytes proliferation by STAT3/p-STAT3/JUN/BCL2 axis. In summary, these current discoveries indicated that miR-125a inhibited hepatocytes proliferation as well as LR by targeting STAT3 and via acting on the STAT3/p-STAT3/JUN/BCL2 axis.

The potential roles of exosomal noncoding RNAs in osteosarcoma

Clinically, it is difficult to efficaciously screen and diagnose osteosarcoma (OS) in advance due to the low sensitivity and poor specificity of the existing tumor markers. Exosomes (Exos) are nanoscale vesicles containing RNAs, lipids, and proteins with a diameter of 30-100 nm. They are multivesicular bodies formed during the invagination of lysosomal particles in cells and released extracellularly after fusing with cell membranes. Besides, Exos are important carriers of cell-to-cell communication signals and genetic materials in the tumor microenvironment. During tumorigenesis, the tumor cells interplay with immune cells, endothelial cells, and related fibroblasts through Exos and boost cancer development. After altering the surrounding microenvironment, the Exos drive tumor cells to proliferate, speed up angiogenesis, and boost cancers to develop along with body fluid transportation. Currently, Exos are becoming novel noninvasive tumor diagnostic markers with high sensitivity, exerting pivotal impacts in fundamental research and clinical applications. Here, we review the existing literature on the roles of exosomal noncoding RNAs in OS progression and their potential clinical applications as novel biomarkers and therapeutics.

LINC00511 Promotes Osteosarcoma Tumorigenesis and Invasiveness through the miR-185-3p/E2F1 Axis

Osteosarcoma is a malignant tumor that seriously threatens human health. Numerous studies have pointed out the potential of long noncoding RNAs (lncRNAs) as new therapeutic targets for various human cancers. Therefore, we mainly investigate whether there is a new type of lncRNA pathway involved in regulating the development of osteosarcoma. The present study shows the higher expression levels of LINC00511 correlates to a shorter overall survival and disease-free survival time in patients with sarcoma. It is significantly higher in the clinical samples of osteosarcoma patients than in normal adjacent cancer tissues. We used U373 and SW1353 osteosarcoma cells to determine the effect of lncRNA on osteosarcoma proliferation and invasion by knocking down LINC00511 compared with controls. The results showed that the LINC00511 knockdown significantly suppressed osteosarcoma cell growth and metastasis. To explore the mechanisms of LINC00511 in osteosarcoma, we tested whether LINC00511 could competitively stimulate miR-185-3p and regulate E2F1 as a ceRNA. The results showed that LINC00511 knockdown induced the increased level of miR-185-3p levels; however, miR-185-3p overexpression suppressed LINC00511 levels. In addition, the results also demonstrated that LINC00511 knockdown or miR-185-3p overexpression could reduce E2F1 levels in osteosarcoma cells. The dual-luciferase reporter assay verified the direct interaction between miR-185-3p and LINC00511 or E2F1. These results may offer an explanation of how the lncRNA affects the progression of osteosarcoma, and our study shows that LINC00511 can be a novel biomarker in osteosarcoma.