MicroRNA-377 exerts a potent suppressive role in osteosarcoma through the involvement of the histone acetyltransferase 1-mediated Wnt axis

Inhibitory effect of miR-377 on the proliferative and invasive behaviors of prostate cancer cells through the modulation of MYC mRNA via its interaction with BCL-2/Bax, PTEN, and CDK4

The MYC gene is a regulatory and proto-oncogenic gene that is overexpressed in the majority of prostate cancers (PCa). Numerous studies have indicated that aberrant expression of microRNAs is involved in the initiation and progression of prostate cancer. In this investigation, we assessed the impact of miR-377 on MYC through luciferase assay. Real-time PCR was employed to determine whether miR-377 could reduce the levels of MYC mRNA in transfected PCa cell lines (PC-3 and DU145) and change in the mRNA levels of BCL-2/Bax, PTEN, and CDK4 as a consequence of MYC downregulation. Moreover, we analyzed the effects of miR-377 on apoptosis, proliferation, cell cycle, and wound healing. Our findings demonstrate that miR-377 effectively targets MYC mRNA, as confirmed by luciferase assay and Real-time PCR. We observed a significant reduction in BCL-2 and CDK4 expression, along with an increase in Bax and PTEN, in prostate cancer cell lines upon MYC suppression. Additionally, elevated levels of miR-377 in PCa cell lines induced apoptosis, inhibited proliferation and migration, and arrested the cell cycle. Taken together, these results unveil the inhibitory role of miR-377 in MYC function within PCa, thereby suggesting its potential as a therapeutic target for the treatment of this malignancy.

Signal Pathways and microRNAs in Osteosarcoma Growth and the Dual Role of Mesenchymal Stem Cells in Oncogenesis

The major challenges in Osteosarcoma (OS) therapy are its heterogeneity and drug resistance. The development of new therapeutic approaches to overcome the major growth mechanisms of OS is urgently needed. The search for specific molecular targets and promising innovative approaches in OS therapy, including drug delivery methods, is an urgent problem. Modern regenerative medicine focuses on harnessing the potential of mesenchymal stem cells (MSCs) because they have low immunogenicity. MSCs are important cells that have received considerable attention in cancer research. Currently, new cell-based methods for using MSCs in medicine are being actively investigated and tested, especially as carriers for chemotherapeutics, nanoparticles, and photosensitizers. However, despite the inexhaustible regenerative potential and known anticancer properties of MSCs, they may trigger the development and progression of bone tumors. A better understanding of the complex cellular and molecular mechanisms of OS pathogenesis is essential to identify novel molecular effectors involved in oncogenesis. The current review focuses on signaling pathways and miRNAs involved in the development of OS and describes the role of MSCs in oncogenesis and their potential for antitumor cell-based therapy.

Acetyl-Click Screening Platform Identifies Small-Molecule Inhibitors of Histone Acetyltransferase 1 (HAT1)

HAT1 is a central regulator of chromatin synthesis that acetylates nascent histone H4. To ascertain whether targeting HAT1 is a viable anticancer treatment strategy, we sought to identify small-molecule inhibitors of HAT1 by developing a high-throughput HAT1 acetyl-click assay. Screening of small-molecule libraries led to the discovery of multiple riboflavin analogs that inhibited HAT1 enzymatic activity. Compounds were refined by synthesis and testing of over 70 analogs, which yielded structure-activity relationships. The isoalloxazine core was required for enzymatic inhibition, whereas modifications of the ribityl side chain improved enzymatic potency and cellular growth suppression. One compound (JG-2016 [24a]) showed relative specificity toward HAT1 compared to other acetyltransferases, suppressed the growth of human cancer cell lines, impaired enzymatic activity in cellulo, and interfered with tumor growth. This is the first report of a small-molecule inhibitor of the HAT1 enzyme complex and represents a step toward targeting this pathway for cancer therapy.

A spotlight on the interplay of signaling pathways and the role of miRNAs in osteosarcoma pathogenesis and therapeutic resistance

Osteosarcoma (OS) is one of the most common bone cancers that constantly affects children, teenagers, and young adults. Numerous epigenetic elements, such as miRNAs, have been shown to influence OS features like progression, initiation, angiogenesis, and treatment resistance. The expression of numerous genes implicated in OS pathogenesis might be regulated by miRNAs. This effect is ascribed to miRNAs' roles in the invasion, angiogenesis, metastasis, proliferation, cell cycle, and apoptosis. Important OS-related mechanistic networks like the WNT/b-catenin signaling, PTEN/AKT/mTOR axis, and KRAS mutations are also affected by miRNAs. In addition to pathophysiology, miRNAs may influence how the OS reacts to therapies like radiotherapy and chemotherapy. With a focus on how miRNAs affect OS signaling pathways, this review seeks to show how miRNAs and OS are related.

Therapeutic advancements in targeting BCL-2 family proteins by epigenetic regulators, natural, and synthetic agents in cancer

Cancer is amongst the deadliest and most disruptive disorders, having a much higher death rate than other diseases worldwide. Human cancer rates continue to rise, thereby posing the most significant concerns for medical health professionals. In the last two decades, researchers have gone past several milestones in tackling cancer while gaining insight into the role of apoptosis in cancer or targeting various biomarker tools for prognosis and diagnosis. Apoptosis which is still a topic full of complexities, can be controlled considerably by B-cell lymphoma 2 (BCL-2) and its family members. Therefore, targeting proteins of this family to prevent tumorigenesis, is essential to focus on the pharmacological features of the anti-apoptotic and pro-apoptotic members, which will help to develop and manage this disorder. This review deals with the advancements of various epigenetic regulators to target BCL-2 family proteins, including the mechanism of several microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). Similarly, a rise in natural and synthetic molecules' research over the last two decades has allowed us to acquire insights into understanding and managing the transcriptional alterations that have led to apoptosis and treating various neoplastic diseases. Furthermore, several inhibitors targeting anti-apoptotic proteins and inducers or activators targeting pro-apoptotic proteins in preclinical and clinical stages have been summarized. Overall, agonistic and antagonistic mechanisms of BCL-2 family proteins conciliated by epigenetic regulators, natural and synthetic agents have proven to be an excellent choice in developing cancer therapeutics.

MicroRNA-377: A therapeutic and diagnostic tumor marker

Cancer is considered as one of the main causes of human deaths globally. Despite the recent progresses in therapeutic modalities, there is still a high rate of mortality among cancer patients. Late diagnosis in advanced tumor stages is one of the main reasons for treatment failure in cancer patients. Therefore, it is required to suggest the novel strategies for the early tumor detection. MicroRNAs (miRNAs) have critical roles in neoplastic transformation by regulation of cell proliferation, migration, and apoptosis. They are always considered as non-invasive markers due to their high stability in body fluids. Since, all of the miRNAs have tissue-specific functions in different tumors as tumor suppressor or oncogene; it is required to investigate the molecular mechanisms of every miRNA in different tumors to introduce that as a suitable non-invasive diagnostic marker in cancer patients. For the first time in the present review, we discussed the role of miR-377 during tumor progression. It has been reported that miR-377 mainly functions as a tumor suppressor through the regulation of signaling pathways and transcription factors. This review is an important step toward introducing the miR-377 as a novel diagnostic marker as well as a therapeutic target in cancer patients.

Potential Therapeutic Use of Aptamers against HAT1 in Lung Cancer

Lung cancer is one of the leading causes of death worldwide and the most common of all cancer types. Histone acetyltransferase 1 (HAT1) has attracted increasing interest as a potential therapeutic target due to its involvement in multiple pathologies, including cancer. Aptamers are single-stranded RNA or DNA molecules whose three-dimensional structure allows them to bind to a target molecule with high specificity and affinity, thus making them exceptional candidates for use as diagnostic or therapeutic tools. In this work, aptamers against HAT1 were obtained, subsequently characterized, and optimized, showing high affinity and specificity for HAT1 and the ability to inhibit acetyltransferase activity in vitro. Of those tested, the apHAT610 aptamer reduced cell viability, induced apoptosis and cell cycle arrest, and inhibited colony formation in lung cancer cell lines. All these results indicate that the apHAT610 aptamer is a potential drug for the treatment of lung cancer.

Modulation of immunosuppressive cells and noncoding RNAs as immunotherapy in osteosarcoma

The most common bone cancer is osteosarcoma (OS), which mostly affects children and teenagers. Early surgical resection combined with chemotherapy significantly improves the prognosis of patients with OS. Existing chemotherapies have poor efficacy in individuals with distant metastases or inoperable resection, and these patients may respond better to novel immunotherapies. Immune escape, which is mediated by immunosuppressive cells in the tumour microenvironment (TME), is a major cause of poor OS prognosis and a primary target of immunotherapy. Myeloid-derived suppressor cells, regulatory T cells, and tumour-associated macrophages are the main immunosuppressor cells, which can regulate tumorigenesis and growth on a variety of levels through the interaction in the TME. The proliferation, migration, invasion, and epithelial-mesenchymal transition of OS cells can all be impacted by the expression of non-coding RNAs (ncRNAs), which can also influence how immunosuppressive cells work and support immune suppression in TME. Interferon, checkpoint inhibitors, cancer vaccines, and engineered chimeric antigen receptor (CAR-T) T cells for OS have all been developed using information from studies on the metabolic properties of immunosuppressive cells in TME and ncRNAs in OS cells. This review summarizes the regulatory effect of ncRNAs on OS cells as well as the metabolic heterogeneity of immunosuppressive cells in the context of OS immunotherapies.

The clinical utility of dysregulated microRNA expression in paediatric solid tumours

MicroRNAs (miRNAs) are short, non-protein-coding genes that regulate the expression of numerous protein-coding genes. Their expression is dysregulated in cancer, where they may function as oncogenes or tumour suppressor genes. As miRNAs are highly resistant to degradation, they are ideal biomarker candidates to improve the diagnosis and clinical management of cancer, including prognostication. Furthermore, miRNAs dysregulated in malignancy represent potential therapeutic targets. The use of miRNAs for these purposes is a particularly attractive option to explore for paediatric malignancies, where the mutational burden is typically low, in contrast to cancers affecting adult patients. As childhood cancers are rare, it has taken time to accumulate the necessary body of evidence showing the potential for miRNAs to improve clinical management across this group of tumours. Here, we review the current literature regarding the potential clinical utility of miRNAs in paediatric solid tumours, which is now both timely and justified. Exploring such avenues is warranted to improve the management and outcomes of children affected by cancer.

KLF5-induced miR-487a augments the progression of osteosarcoma cells by targeting NKX3-1 in vitro

MicroRNAs (miRNAs or miRs) are involved in the development and progression of numerous types of cancer however their role in osteosarcoma has not been fully clarified. The present study aimed to use high-throughput bioinformatics analysis as well as in vitro experiments to investigate the potential role of transcription factors, miRNAs and their targets in the progression of osteosarcoma. miRNA data and clinical information of osteosarcoma were obtained from Gene Expression Omnibus database to investigate differentially expressed miRNAs. The expression of miRNAs/mRNAs in osteosarcoma cell lines was detected via reverse transcription-quantitative (RT-qPCR). MTT and colony formation assay were used to determine cell proliferation ability and transwell assay was used to observe cell invasion and migration ability. A total of four prediction algorithms for miRNA-mRNA interactions were used to determine potential target genes of miR-487a. Predicted target genes were used to intersect with overlapped differentially expressed genes (DEGs) from GSE12865 and The Cancer Genome Atlas osteosarcoma datasets. Expression of NK3 homeobox 1 (NKX3-1) was analyzed by western blotting and RT-qPCR assay. Dual luciferase assay was conducted to verify whether NKX3-1 was a direct target of miR-487a. The regulatory association between Kruppel-like factor 5 (KLF5) and miR-487a was detected using chromatin immunoprecipitation assay. miR-487a was upregulated in osteosarcoma tissue (GSE65071 and GSE28423) and cell lines (HOS and MG63). miR-487a mimic promoted proliferation, migration and invasion of osteosarcoma cells. NKX3-1 was a direct target of miR-487a and transfection of NKX3-1 plasmid reversed the effect of miR-487a on proliferation, migration and invasion of osteosarcoma cells. KLF5 enhanced miR-487a expression by directly binding to its promoter region and miR-487a inhibitor reversed the effect of KLF5 on proliferation, migration and invasion of osteosarcoma cells. The present results indicated that KLF5/miR-487a signaling promoted invasion and metastasis of osteosarcoma cells via targeting NKX3-1.

Navigating the genomic instability mine field of osteosarcoma to better understand implications of non-coding RNAs

Osteosarcoma is one of the most genomically complex cancers and as result, it has been difficult to assign genomic aberrations that contribute to disease progression and patient outcome consistently across samples. One potential source for correlating osteosarcoma and genomic biomarkers is within the non-coding regions of RNA that are differentially expressed. However, it is unsurprising that a cancer classification that is fraught with genomic instability is likely to have numerous studies correlating non-coding RNA expression and function have been published on the subject. This review undertakes the formidable task of evaluating the published literature of noncoding RNAs in osteosarcoma. This is not the first review on this topic and will certainly not be the last. The review is organized with an introduction into osteosarcoma and the epigenetic control of gene expression before reviewing the molecular function and expression of long non-coding RNAs, circular RNAs, and short non-coding RNAs such as microRNAs, piwi RNAs, and short-interfering RNAs. The review concludes with a review of the literature and how the biology of non-coding RNAs can be used therapeutically to treat cancers, especially osteosarcoma. We conclude that non-coding RNA expression and function in osteosarcoma is equally complex to understanding the expression differences and function of coding RNA and proteins; however, with the added lens of both coding and non-coding genomic sequence, researchers can begin to identify the patterns that consistently associate with aggressive osteosarcoma.

Implication of microRNAs in Carcinogenesis with Emphasis on Hematological Malignancies and Clinical Translation

MicroRNAs (miRNAs) are evolutionarily conserved small non-coding RNAs, that are involved in the multistep process of carcinogenesis, contributing to all established hallmarks of cancer. In this review, implications of miRNAs in hematological malignancies and their clinical utilization fields are discussed. As components of the complex regulatory network of gene expression, influenced by the tissue microenvironment and epigenetic modifiers, miRNAs are “micromanagers” of all physiological processes including the regulation of hematopoiesis and metabolic pathways. Dysregulated miRNA expression levels contribute to both the initiation and progression of acute leukemias, the metabolic reprogramming of malignantly transformed hematopoietic precursors, and to the development of chemoresistance. Since they are highly stable and can be easily quantified in body fluids and tissue specimens, miRNAs are promising biomarkers for the early detection of hematological malignancies. Besides novel opportunities for differential diagnosis, miRNAs can contribute to advanced chemoresistance prediction and prognostic stratification of acute leukemias. Synthetic oligonucleotides and delivery vehicles aim the therapeutic modulation of miRNA expression levels. However, major challenges such as efficient delivery to specific locations, differences of miRNA expression patterns between pediatric and adult hematological malignancies, and potential side effects of miRNA-based therapies should be considered.

Circ_0003732 promotes osteosarcoma progression through regulating miR-377-3p/CPEB1 axis and Wnt/β-catenin signaling pathway

Osteosarcoma is a prevalent malignant bone cancer. This study aimed to explore the biologic role and potential mechanism of circ_0003732 in osteosarcoma carcinogenesis. Quantitative real-time PCR was implemented to detect the RNA expression of circ_0003732, microRNA-377-3p (miR-377-3p) and cytoplasmic polyadenylation element-binding protein 1 (CPEB1). Cell proliferation was evaluated by cell counting kit-8 assay and colony formation assay. Transwell, wound healing and flow cytometry assays were employed to assess cell migration, invasion and apoptosis. In addition, the interaction between miR-377-3p and circ_0003732 or CPEB1 was validated by dual-luciferase reporter assay. The protein expression was detected by western blot assay or immunohistochemistry assay. Xenograft tumor assay was performed to explore the regulation of circ_0003732 on osteosarcoma tumor growth in vivo. Circ_0003732 was upregulated in osteosarcoma tissues and cells. Knockdown of circ_0003732 suppressed osteosarcoma cell proliferation, migration, invasion and triggered cell apoptosis in vitro, as well as reduced osteosarcoma tumor growth in vivo. Meanwhile, miR-377-3p could bind to circ_0003732 and CPEB1 and miR-377-3p inhibitor could reverse the effects of circ_0003732 silence on osteosarcoma cell progression. Furthermore, CPEB1 overexpression could overturn the suppressive impacts of miR-377-3p on osteosarcoma progression. In addition, circ_0003732 silence restrained Wnt/β-catenin signaling pathway via regulating miR-377-3p in osteosarcoma cells. Circ_0003732 might play a positive role in the malignant progression of osteosarcoma by regulating the miR-377-3p/CPEB1 axis and activating the Wnt/β-catenin signaling pathway, which might provide new insights for osteosarcoma therapy.

Targeting Wnt/β-catenin signaling by microRNAs as a therapeutic approach in chemoresistant osteosarcoma

Osteosarcoma (OS) is an adolescent and young adult malignancy that mostly occurs in long bones. The treatment of OS is still a big challenge for clinicians due to increasing chemoresistance, and many efforts are being made today to find more beneficial treatments. In this regard, the use of microRNAs has shown a high capacity to develop promising therapies. By targeting cancer-involved signaling pathways, microRNAs reduce the cellular level of these protein pathways; thereby reducing the growth and invasion of tumors, and even leading cancer cells to apoptosis. One of these oncogenic pathways that play an important role in OS development and can be targeted by microRNAs is the Wnt/β-catenin signaling pathway. Hence, the first goal of this review article is to explain the cross-talk of microRNAs and the Wnt/β-catenin signaling in OS and then discussing recent findings of the use of microRNAs as a therapeutic approach in OS.

Histone Acetylation in the Epigenetic Regulation of Bone Metabolism and Related Diseases

As the earliest studied epigenetic modification, acetylation has been explored a lot through the years. While bone tissue acts as an indispensable part of body, researches aimed at the relationship between the bone and acetylation became necessary. Some environmental factors like diet may affect the metabolism status that some metabolites especially nicotinamide adenine dinucleotide (NAD) were found able to regulate intracellular histone acetylation in bone metabolism. This review focuses on representing the interaction among acetylation, metabolism, and the bone. The results showed that acetylation connects a lot with bone metabolism, while the explorations about related metabolites like acetyl-CoA or different environmental exposures are still limited. Some acetylation-related therapy methods of bone diseases based on metabolic regulation or epigenetic enzymes were also reviewed.

microRNA-377-3p inhibits osteosarcoma progression by targeting CUL1 and regulating Wnt/β-catenin signaling pathway

OBJECTIVE

Emerging studies highlight the crucial effects of microRNAs on cancer initiation and malignant progression of various tumors. This study focused on the biological effect of miR-377-3p on CUL1 and epithelial-mesenchymal transition (EMT) and Wnt/β-catenin pathways in osteosarcoma (OS).

METHODS

We performed quantitative real-time polymerase chain reaction (qRT-PCR) to analyze miR-377-3p and CUL1 expression levels in OS tissues and MG-63 cells. Then, cell counting kit (CCK)-8 and Transwell assay were used to examine the functions of miR-377-3p in OS cell growth and metastasis abilities. Meanwhile, luciferase reporter assay was used to validate CUL1 as direct target of miR-377-3p. qRT-PCR and Western blot were then carried out to detect the impact of miR-377-3p on EMT and Wnt/β-catenin pathways. Tumor xenograft models were established to further examine the effects of miR-377-3p on OS tumorigenesis in vivo.

RESULTS

miR-377-3p downregulation was frequently identified in OS tissues and cells, which was associated with worse prognosis of OS patients. Functional experiments showed miR-377-3p restoration could dramatically repress OS cell growth and migration by regulation of EMT and Wnt/β-catenin pathways. Moreover, luciferase reporter assay revealed that CUL1 acted as a functional target of miR-377-3p. Additionally, the elevated CUL1 expressions in OS tissues also indicated poor prognosis of OS patients. Furthermore, the OS tumor growth was also obviously inhibited by miR-377-3p overexpression in vivo.

CONCLUSIONS

Collectively, all the above findings revealed that miR-377-3p exerted anti-OS functions via CUL1 and EMT and Wnt/β-catenin pathways. These results may contribute to the development of clinical OS treatment.

Osteosarcoma Pathogenesis Leads the Way to New Target Treatments

Osteosarcoma (OS) is a rare condition with very poor prognosis in a metastatic setting. Basic research has enabled a better understanding of OS pathogenesis and the discovery of new potential therapeutic targets. Phase I and II clinical trials are already ongoing, with some promising results for these patients. This article reviews OS pathogenesis and new potential therapeutic targets.

CircPVT1 Regulates Cell Proliferation, Apoptosis and Glycolysis in Hepatocellular Carcinoma via miR-377/TRIM23 Axis

Background

Recent studies reported that circular RNAs (circRNAs) exert essential functions in hepatocellular carcinoma (HCC) progression. However, the expression profile and function of circular RNA PVT1 (circPVT1) in HCC are not fully addressed. Thus, we aimed to probe into the function of circPVT1 in HCC development.

Methods

The levels of circPVT1, microRNA-377 (miR-377) and transcripts encoding tripartite motif containing 23 (TRIM23) were determined by qRT-PCR. The stability and localization of circPVT1 were examined by RNase R digestion assay and subcellular fraction assay, respectively. Cell proliferation and apoptosis were evaluated by MTT assay and flow cytometry analysis, respectively. The relationship between miR-377 and circPVT1 or TRIM23 was determined by dual-luciferase reporter assay and RNA immunoprecipitation (RIP). The protein expression of TRIM23 was measured by Western blot. The glycolysis level was assessed by specific kits and Seahorse Extracellular Flux Analyzer XF96. The function of circPVT1 in vivo was investigated in a murine xenograft model.

Results

CircPVT1 and TRIM23 levels were elevated, while miR-377 was decreased in HCC. CircPVT1 knockdown restrained proliferation and glycolysis, but enhanced apoptosis in HCC cells. CircPVT1 could bind to miR-377 and inhibition of miR-377 restored circPVT1 knockdown-mediated effect on HCC cells. TRIM23 was certified as a target of miR-377, and TRIM23 upregulation overturned the influence of miR-377 upregulation or circPVT1 silence on HCC progression. Moreover, circPVT1 knockdown restrained tumor growth in HCC in vivo.

Conclusion

CircPVT1 aggravated the progression of HCC by upregulating TRIM23 via sponging miR-377.

Role of microRNAs in the crosstalk between osteosarcoma cells and the tumour microenvironment

Osteosarcoma (OS) is the most common primary bone tumour, with a peak incidence in adolescents, and the five-year survival rate of patients with metastasis or recurrence is much lower than that of patients without metastasis and recurrence. OS is initiated and develops in a complex tumour microenvironment (TME) that contains many different components, such as osteoblasts, osteoclasts, mesenchymal stem cells, fibroblasts, immune cells, extracellular matrix (ECM), extracellular vesicles, and cytokines. The extensive interaction between OS and the TME underlies OS progression. Therefore, rather than targeting OS cells, targeting the key factors in the TME may yield novel therapeutic approaches. MicroRNAs (miRNAs) play multiple roles in the biological behaviours of OS, and recent studies have implied that miRNAs are involved in mediating the communication between OS cells and the surrounding TME. Here, we review the TME landscape and the miRNA dysregulation of OS, describe the role of the altered TME in OS development and highlight the role of miRNA in the crosstalk between OS cells and the TME.

Long Non-Coding RNA OIP5-AS1 Knockdown Enhances CDDP Sensitivity in Osteosarcoma via miR-377-3p/FOSL2 Axis

Background

Drug resistance is one of big obstacles for the treatment of tumor. Long non-coding RNA Opa-interacting protein 5-antisense RNA 1 (OIP5-AS1) was identified to involve in drug resistance. In this research, the effects of OIP5-AS1 on cisplatin (CDDP) resistance in osteosarcoma (OS) were mainly investigated.

Methods

The levels of OIP5-AS1, microRNA-377-3p (miR-377-3p), and FOS like 2 (FOSL2) were measured by quantitative real-time polymerase chain reaction. The inhibitory concentration 50 (IC₅₀) value of CDDP, cell viability and apoptotic rate was evaluated through Cell Counting Kit-8 and flow cytometry assays, respectively. The levels of multidrug resistance-associated protein 1 (MRP1), P-glycoprotein, B-cell lymphoma 2, Bcl2-associated X, cleaved-caspase-3, and FOSL2 were detected by Western blot assay. The interaction between miR-377-3p and OIP5-AS1 or FOSL2 was verified by Dual-Luciferase Reporter and RNA Immunoprecipitation assays. The function of OIP5-AS1 was detected by a xenograft tumor model in vivo.

Results

OIP5-AS1 and FOSL2 were up-regulated, while miR-377-3p was down-regulated in CDDP-resistant OS tissues and cells. OIP5-AS1 silencing inhibited cell viability and the IC₅₀ value of CDDP, and promoted apoptotic rate in CDDP-resistant OS cells. Mechanically, OIP5-AS1 was verified as a sponge to miR-377-3p and FOSL2 was a target of miR-377-3p. Moreover, OIP5-AS1 knockdown repressed OS tumor growth and enhanced CDDP sensitivity of OS in vivo.

Conclusion

OIP5-AS1 positively modulated FOSL2 expression to decrease CDDP sensitivity in OS by sponging miR-377-3p.

Upregulation of miRNA-154-5p prevents the tumorigenesis of osteosarcoma

BACKGROUND

Osteosarcoma (OS) is a primary malignant bone sarcoma in human worldwide. It has been shown that the level of microRNA-154-5p (miR-154-5p) was downregulated in human OS tissues. However, the mechanisms by which miR-154-5p regulates the proliferation, apoptosis and invasion in OS remain unclear. Thus, the present study aimed to investigate the role of miR-154-5p during the tumorigenesis of OS.

METHODS

The level of miR-154-5p in human OS tissues was detected by RT-qPCR. In addition, the effects of miR-154-5p on apoptosis and invasion of OS cells were assessed by flow cytometry and transwell assays, respectively. Meanwhile, the dual luciferase reporter system assay was performed to explore the interaction of miR-154-5p and E2F5.

RESULTS

The level of miR-154-5p was downregulated in OS tissues. Overexpression of miR-154-5p significantly inhibited the proliferation, migration and invasion of MG63 cells. In addition, upregulation of miR-154-5p obviously induced apoptosis in MG63 cells via upregulation of Bax and cleaved caspase 3, and downregulation of Bcl-2. Moreover, luciferase reporter assay identified that E2F5 was the binding target of miR-154-5p. Meanwhile, overexpression of miR-154-5p induced cell cycle arrest in MG63 cells via inhibiting the expressions of E2F5, Cyclin E1 and CDK2. Furthermore, in vivo assays indicated that overexpression of miR-154-5p notably inhibited the tumor growth in an OS xenograft model.

CONCLUSION

These results indicated that miR-154-5p may function as a potential tumor suppressor in OS. Therefore, miR-154-5p might be a novel therapeutic option for the treatment of OS.

Long noncoding RNA NR2F1-AS1 enhances the malignant properties of osteosarcoma by increasing forkhead box A1 expression via sponging of microRNA-483-3p

The long noncoding RNA NR2F1-AS1 has been found to promote the development of hepatocellular carcinoma and endometrial cancer. In this study, we measured NR2F1-AS1 expression in osteosarcoma (OS), determined the involvement of NR2F1-AS1 in the malignant properties of OS, and investigated the underlying mechanisms. NR2F1-AS1 was found to be upregulated in OS tumors and cell lines. The increased NR2F1-AS1 level was closely associated with advanced clinical stage and distant metastasis in patients with OS. Patients with OS in an NR2F1-AS1 high-expression group demonstrated significantly shorter overall survival than did patients in an NR2F1-AS1 low-expression group. NR2F1-AS1 knockdown inhibited OS cell proliferation, migration, and invasion and promoted cell cycle arrest and apoptosis in vitro and slowed tumor growth in vivo. NR2F1-AS1 was found to function as a competing endogenous RNA by directly sponging microRNA-483-3p (miR-483-3p) and upregulating its target oncogene forkhead box A1 (FOXA1). Finally, rescue experiments revealed that knockdown of miR-483-3p and recovery of FOXA1 expression both attenuated the influence of the NR2F1-AS1 knockdown on OS cells. Thus, NR2F1-AS1 plays an oncogenic role in OS through sponging miR-483-3p and thereby upregulating FOXA1, suggesting an additional target for osteosarcoma therapeutics.

MicroRNA-99b predicts clinical outcome of osteosarcoma and suppresses tumor cell proliferation, migration and invasion

BACKGROUND

Osteosarcoma (OS) is a malignancy predominantly occurred in children and adolescents. Numerous microRNAs are involved in the pathogenesis of various cancers. This study aimed to investigate the expression profiles of miR-99b and its prognostic value in OS patients, and further analyze the biological function of miR-99b in the tumor progression by using OS cells.

METHODS

Expression of miR-99b was measured using quantitative real-time PCR. Kaplan-Meier survival curves and Cox regression analysis were performed to evaluate the prognostic value of miR-99b. OS cell lines were used to investigate the effects of miR-99b on cell proliferation, migration and invasion.

RESULTS

A significant decreased expression of miR-99b was observed in the OS tissues and cell lines respectively compared with the normal tissues and cells. Aberrant expression of miR-99b was associated with the patients' metastasis and TNM stage, and could be used to predict the prognosis of OS. The expression of miR-99b was regulated in vitro by cell transfection, and we found that the overexpression of miR-99b led to suppressed cell proliferation, migration and invasion, whereas the knockdown of miR-99b resulted in the opposite results.

CONCLUSIONS

In one word, the aberrantly expressed miR-99b serves a prognostic biomarker for OS patients. OS cell proliferation, migration and invasion can be inhibited by the overexpression of miR-99b, suggesting that the methods to increase miR-99b expression may be novel therapeutic strategies in OS.

Long noncoding RNA TTN-AS1 enhances the malignant characteristics of osteosarcoma by acting as a competing endogenous RNA on microRNA-376a thereby upregulating dickkopf-1

The expression levels and detailed functions of TTN-AS1 in osteosarcoma (OS) have not yet been explored. This study aimed to measure TTN-AS1 expression in OS tissues and cell lines, investigate its specific roles in the aggressive characteristics of OS cells in vitro and in vivo, and elucidate the regulatory mechanisms of TTN-AS1 action. TTN-AS1 expression was high in OS tissue samples and cell lines; TTN-AS1 overexpression correlated with the clinical stage, distant metastasis, and shorter overall survival of the patients. A TTN-AS1 knockdown inhibited OS cell proliferation, migration, and invasion and induced apoptosis in vitro and slowed tumor growth in vivo. Mechanism investigation revealed that TTN-AS1 acts as a competing endogenous RNA on microRNA-376a-3p (miR-376a) in OS cells. Dickkopf-1 (DKK1) mRNA was identified as a direct target of miR-376a in OS cells. Resumption of DKK1 expression reversed the tumor-suppressive activities of miR-376a overexpression in OS cells. The knockdown of miR-376a counteracted the reduction in the malignant characteristics of OS cells by the downregulation of TTN-AS1. In conclusion, TTN-AS1 functions as a competing endogenous RNA targeting miR-376a and increases the malignancy of OS cells in vitro and in vivo by upregulating DKK1.

New Insights about the Wnt/β-Catenin Signaling Pathway in Primary Bone Tumors and Their Microenvironment: A Promising Target to Develop Therapeutic Strategies?

Osteosarcoma and Ewing sarcoma are the most common malignant primary bone tumors mainly occurring in children, adolescents and young adults. Current standard therapy includes multidrug chemotherapy and/or radiation specifically for Ewing sarcoma, associated with tumor resection. However, patient survival has not evolved for the past decade and remains closely related to the response of tumor cells to chemotherapy, reaching around 75% at 5 years for patients with localized forms of osteosarcoma or Ewing sarcoma but less than 30% in metastatic diseases and patients resistant to initial chemotherapy. Despite Ewing sarcoma being characterized by specific EWSR1-ETS gene fusions resulting in oncogenic transcription factors, currently, no targeted therapy could be implemented. It seems even more difficult to develop a targeted therapeutic strategy in osteosarcoma which is characterized by high complexity and heterogeneity in genomic alterations. Nevertheless, the common point between these different bone tumors is their ability to deregulate bone homeostasis and remodeling and divert them to their benefit. Therefore, targeting different actors of the bone tumor microenvironment has been hypothesized to develop new therapeutic strategies. In this context, it is well known that the Wnt/β-catenin signaling pathway plays a key role in cancer development, including osteosarcoma and Ewing sarcoma as well as in bone remodeling. Moreover, recent studies highlight the implication of the Wnt/β-catenin pathway in angiogenesis and immuno-surveillance, two key mechanisms involved in metastatic dissemination. This review focuses on the role played by this signaling pathway in the development of primary bone tumors and the modulation of their specific microenvironment.