LINC00266-1/miR-548c-3p/SMAD2 feedback loop stimulates the development of osteosarcoma

Biochemical targets of the micropeptides encoded by lncRNAs

Long non-coding RNAs (lncRNAs) are a group of transcripts longer than 200 nucleotides, which play important roles in regulating various cellular activities by the action of the RNA itself. However, about 40% of lncRNAs in human cells are potentially translated into micropeptides (also referred to as microproteins) usually shorter than 100 amino acids. Thus, these lncRNAs may function by both RNAs directly and their encoded micropeptides. The micropeptides encoded by lncRNAs may regulate transcription, translation, protein phosphorylation or degradation, or subcellular membrane functions. This review attempts to summarize the biochemical targets of the micropeptides-encoded by lncRNAs, which function by both RNAs and micropeptides, and discuss their associations with various diseases and their potentials as drug targets.

Pan-inhibition of the three H2S synthesizing enzymes restrains tumor progression and immunosuppression in breast cancer

BACKGROUND

Hydrogen sulfide (H2S) is a significant endogenous mediator that has been implicated in the progression of various forms of cancer including breast cancer (BC). Cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE), and 3-mercaptopyruvate sulfurtransferase (3MST) are the three principal mammalian enzymes responsible for H2S production. Overexpression of CBS, CSE and 3MST was found to be associated with poor prognosis of BC patients. Moreover, H2S was linked to an immune-suppressive tumor microenvironment in BC. Recently it was observed that BC cells, in response to single or dual inhibition of H2S synthesizing enzymes, develop an escape mechanism by overexpressing alternative sources of H2S generation. Thus, the aim of this work is to escape the H2S compensatory mechanism by pan repressing the three enzymes using microRNAs (miRNAs) and to investigate their impact on the oncogenic and immunogenic profile of BC cells.

METHODS

BC female patients (n = 25) were recruited. In-silico analysis was used to identify miRNAs targeting CBS, CSE, and 3MST. MDA-MB-231 cells were cultured and transfected using oligonucleotides. Total RNA was extracted using Biazol, reverse transcribed and quantified using qRT-PCR. H2S levels were measured using AzMc assay. BC hallmarks were assessed using trans-well migration, wound healing, MTT, and colony forming assays.

RESULTS

miR-193a and miR-548c were validated by eight different bioinformatics software to simultaneously target CBS, CSE and 3MST. MiR-193a and miR-548c were significantly downregulated in BC tissues compared to their non-cancerous counterparts. Ectopic expression of miR-193a and miR-548c in MDA-MB-231 TNBC cells resulted in a marked repression of CBS, CSE, and 3MST transcript and protein levels, a significant decrease in H2S levels, reduction in cellular viability, inhibition of migration and colony forming ability, repression of immune-suppressor proteins GAL3 GAL9, and CD155 and upregulation of the immunostimulatory MICA and MICB proteins.

CONCLUSION

This study sheds the light onto miR-193a and miR-548c as potential pan-repressors of the H2S synthesizing enzymes. and identifies them as novel tumor suppressor and immunomodulatory miRNAs in TNBC.

ACSL4 accelerates osteosarcoma progression via modulating TGF-β/Smad2 signaling pathway

Osteosarcoma (OS) is a malignant bone sarcoma arising from mesenchymal stem cells. The biological role of Acyl-CoA synthetase long-chain family member 4 (ACSL4), recently identified as an oncogene in numerous tumor types, remains largely unclear in OS. In this study, we investigated the expression of ACSL4 in OS tissues using immunohistochemistry staining (IHC) staining of a human tissue microarray and in OS cells by qPCR assay. Our findings revealed a significant up-regulation of ACSL4 in both OS tissues and cells. To further understand its biological effects, we conducted a series of loss-of-function experiments using ACSL4-depleted MNNG/HOS and U-2OS cell lines, focusing on OS cell proliferation, migration, and apoptosis in vitro. Our results demonstrated that ACSL4 knockdown remarkably suppressed OS cell proliferation, arrested cells in the G2 phase, induced cell apoptosis, and inhibited cell migration. Additionally, a subcutaneous xenograft mice model was established to validate the in vivo impact of ACSL4, revealing ACSL4 silencing impaired tumor growth in the OS xenograft mice. Additionally, we discovered that ACSL4 could regulate the phosphorylation level of Smad2 through cooperative interactions, and treatment with a TGF-β inhibitor weakened the promoting effects of ACSL4 overexpression. In short, ACSL4 regulated OS progression by modulating TGF-β/Smad2 signaling pathway. These findings underscore ACSL4 as a promising therapeutic target for OS patients and contribute novel insights into the pathogenesis of OS.

SMAD Proteins in TGF-β Signalling Pathway in Cancer: Regulatory Mechanisms and Clinical Applications

Suppressor of mother against decapentaplegic (SMAD) family proteins are central to one of the most versatile cytokine signalling pathways in metazoan biology, the transforming growth factor-β (TGF-β) pathway. The TGF-β pathway is widely known for its dual role in cancer progression as both an inhibitor of tumour cell growth and an inducer of tumour metastasis. This is mainly mediated through SMAD proteins and their cofactors or regulators. SMAD proteins act as transcription factors, regulating the transcription of a wide range of genes, and their rich post-translational modifications are influenced by a variety of regulators and cofactors. The complex role, mechanisms, and important functions of SMAD proteins in tumours are the hot topics in current oncology research. In this paper, we summarize the recent progress on the effects and mechanisms of SMAD proteins on tumour development, diagnosis, treatment and prognosis, and provide clues for subsequent research on SMAD proteins in tumours.

Roles of lncRNAs in childhood cancer: Current landscape and future perspectives

According to World Health Organization (WHO), cancer is the leading cause of death for children and adolescents. Leukemias, brain cancers, lymphomas and solid tumors, such as neuroblastoma, ostesarcoma and Wilms tumors are the most common types of childhood cancers. Approximately 400,000 children and adolescents between the ages of 0 and 19 are diagnosed with cancer each year worldwide. The cancer incidence rates have been rising for the past few decades. Generally, the prognosis of childhood cancers is favorable, but the survival rate for many unresectable or recurring cancers is substantially worse. Although random genetic mutations, persistent infections, and environmental factors may serve as contributing factors for many pediatric malignancies, the underlying mechanisms are yet unknown. Long non-coding RNAs (lncRNAs) are a group of transcripts with longer than 200 nucleotides that lack the coding capacity. However, increasing evidence indicates that lncRNAs play vital regulatory roles in cancer initiation and development in both adults and children. In particular, many lncRNAs are stable in cancer patients' body fluids such as blood and urine, suggesting that they could be used as novel biomarkers. In support of this notion, lncRNAs have been identified in liquid biopsy samples from pediatric cancer patients. In this review, we look at the regulatory functions and underlying processes of lncRNAs in the initiation and progression of children cancer and discuss the potential of lncRNAs as biomarkers for early detection. We hope that this article will help researchers explore lncRNA functions and clinical applications in pediatric cancers.

Novel insights into noncanonical open reading frames in cancer

With technological advances, previously neglected noncanonical open reading frames (nORFs) are drawing ever-increasing attention. However, the translation potential of numerous putative nORFs remains elusive, and the functions of noncanonical peptides have not been systemically summarized. Moreover, the relationship between noncanonical peptides and their counterpart protein or RNA products remains elusive and the clinical implementation of noncanonical peptides has not been explored. In this review, we highlight how recent technological advances such as ribosome profiling, bioinformatics approaches and CRISPR/Cas9 facilitate the research of noncanonical peptides. We delineate the features of each nORF category and the evolutionary process underneath the nORFs. Most importantly, we summarize the diversified functions of noncanonical peptides in cancer based on their subcellular location, which reflect their extensive participation in key pathways and essential cellular activities in cancer cells. Meanwhile, the equilibrium between noncanonical peptides and their corresponding transcripts or counterpart products may be dysregulated under pathological states, which is essential for their roles in cancer. Lastly, we explore their underestimated potential in clinical application as diagnostic biomarkers and treatment targets against cancer.

MicroRNA-181a-5p Promotes Osteosarcoma Progression via PTEN/AKT Pathway

Osteosarcoma is the most common primary malignant bone tumor in children and adolescents with poor prognosis. MicroRNA-181a-5p (miR-181a-5p) is involved in the progression of various tumors; however, its role and underlying mechanism in osteosarcoma remains unclear. In this study, we found that miR-181a-5p was upregulated in human osteosarcoma cells and tissues. miR-181a-5p mimic significantly promoted, while miR-181a-5p inhibitor blocked the proliferation, colony formation, migration, invasion, and cell cycle progression of osteosarcoma cells. Mechanistically, miR-181a-5p bound to the 3′-untranslational region of phosphatase and tensin homolog (PTEN) and reduced its protein expression, thereby activating protein kinase B (PKB/AKT) pathway. Either PTEN overexpression or AKT inhibition notably blocked the tumor-promoting effects of miR-181a-5p. Moreover, we observed that miR-181a-5p mimic further inhibited growth of human osteosarcoma cells in the presence of adriamycin or cisplatin. Overall, miR-181a-5p promotes osteosarcoma progression via PTEN/AKT pathway and it is a promising therapeutic target to treat osteosarcoma.

Circ_0000527 Drives Retinoblastoma Progression by Regulating miR-1236-3p/SMAD2 Pathway

PURPOSE

Circular RNAs (circRNAs) play essential roles in the progression of human tumors, including retinoblastoma (RB). In this study, we aimed to explore the functions and potential mechanisms of circ_0000527 in RB.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR), Western blot assay and immunohistochemistry (IHC) assay were conducted to determine the levels of circ_0000527, microRNA-1236-3p (miR-1236-3p) and SMAD family member 2 (SMAD2). RNase R assay and actinomycin D assay were conducted to analyze the characteristic of circ_0000527. Cell Counting Kit-8 (CCK-8) assay, 5-ethynyl-2'-deoxyuridine (EdU) assay, and colony formation assay were performed for cell proliferation ability. Wound healing assay and transwell assay were applied to assess cell migration and invasion. Tube formation assay was utilized for angiogenesis ability. Flow cytometry analysis was adopted to analyze cell apoptosis. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were performed to analyze the relationships among circ_0000527, miR-1236-3p, and SMAD2. Murine xenograft model assay was conducted for the role of circ_0000527 in vivo.

RESULTS

Circ_0000527 was overexpressed in RB patients and related to advanced TNM stages, optic nerve invasion and choroidal invasion. Circ_0000527 knockdown suppressed cell proliferation, migration, invasion and angiogenesis and promoted apoptosis in RB cells in vitro. Circ_0000527 sponged miR-1236-3p, which directly targeted SMAD2. MiR-1236-3p level was decreased in RB tissues and cells. MiR-1236-3p inhibition reversed circ_0000527 knockdown-mediated effects on RB cell malignant behaviors. Moreover, miR-1236-3p overexpression suppressed RB cell progression, with SMAD2 elevation abrogated the effect. Additionally, circ_0000527 knockdown restrained tumor formation in vivo.

CONCLUSIONS

Circ_0000527/miR-1236-3p/SMAD2 axis played a positive role in the progression of RB.

Functional Peptides Encoded by Long Non-Coding RNAs in Gastrointestinal Cancer

Gastrointestinal cancer is by far the most common malignancy and the most common cause of cancer-related deaths worldwide. Recent studies have shown that long non-coding RNAs (lncRNAs) play an important role in the epigenetic regulation of cancer cells and regulate tumor progression by affecting chromatin modifications, gene transcription, translation, and sponge to miRNAs. In particular, lncRNA has recently been found to possess open reading frame (ORF), which can encode functional small peptides or proteins. These peptides interact with its targets to regulate transcription or the signal axis, thus promoting or inhibiting the occurrence and development of tumors. In this review, we summarize the involvement of lncRNAs and the function of lncRNAs encoded small peptides in gastrointestinal cancer.

Knockdown of HCG18 Inhibits Cell Viability, Migration and Invasion in Pediatric Osteosarcoma by Targeting miR-188-5p/FOXC1 Axis

Understanding the underlying mechanisms of pediatric osteosarcoma (OS) migration and invasion is important for prognosis and treatment. We tried to measure the expression of long non-coding RNA HLA complex group 18 (HCG18) in OS and reveal its function in the malignant behaviors of OS cells. This study detected the expression of HCG18, miR-188-5p and forkhead box C1 (FOXC1) in OS tissues and cell lines by quantitative real-time PCR (qRT-PCR). The relevance between miR-188-5p and HCG18 or FOXC1 was affirmed by dual-luciferase reporter (DLR) assay. Cell viability was analyzed by MTT assay. Transwell assay was utilized to test cell invasion and migration. FOXC1 protein expression was detected by western blot. HCG18 expression was elevated in OS tissues, and enhanced HCG18 expression was related to metastasis. HCG18 silencing repressed the viability, migration and invasion of OS cells. Moreover, HCG18 interacted with miR-188-5p. MiR-188-5p up-regulation repressed cell viability, invasion and migration in OS cells. FOXC1, a known target of miR-188-5p, was negatively modulated by miR-188-5p. Furthermore, miR-188-5p inhibition or FOXC1 over-expression partially abolished the reduced of cell viability, invasion and migration mediated by HCG18 silencing in OS cell lines. This study revealed that HCG18 knockdown repressed the viability, invasion and migration of OS cells by targeting miR-188-5p and regulating FOXC1 expression. Thus, HCG18/ miR-188-5p/FOX may be a hopeful target for OS therapy.

Regulation of TGFβ/SMAD signaling by long non-coding RNAs in different cancers: Dark Knight in the Castle of molecular oncology

One of the complex themes in recent years has been the multi-layered regulation of TGFβ signaling in cancer cells. TGFβ/SMAD signaling pathway is a highly complicated web of proteins which work spatio-temporally to regulate multiple steps of carcinogenesis. TGFβ/SMAD has been shown to dualistically regulate cancer progression. Therefore, TGFβ/SMAD signaling behaves as a “double-edged sword” in molecular oncology. Accordingly, regulation of TGFβ/SMAD is multi-layered because of oncogenic and tumor suppressor long non-coding RNAs (LncRNAs). In this review, we have summarized most recent breakthroughs in our understanding related to regulation of TGFβ/SMAD signaling by lncRNAs. We have comprehensively analyzed how different lncRNAs positively and negatively regulate TGFβ/SMAD signaling in different cancers. We have gathered missing pieces of an incomplete jig-saw puzzle of lncRNA-interactome ranging from “sponge effects” of lncRNAs to mechanistic modulation of TGFβ/SMAD signaling by lncRNAs.

Long noncoding RNA LINC00520 accelerates lung adenocarcinoma progression via miR-1252-5p/FOXR2 pathway

It has been corroborated that long noncoding RNA (lncRNA) played fundamental function in various human malignancies development including lung adenocarcinoma (lung ADC). In our study, LINC00520 roles in lung ADC tumorigenesis were explored. We found that LINC00520 level was elevated in lung ADC tissues and cell lines. Besides, the LINC00520 expression had a negative connection with miR-1252-5p level in lung ADC tissues. Additionally, our results demonstrated the reciprocal repression influence between LINC00520 and miR-1252-5p. Moreover, luciferase reporter assays, RIP (RNA-binding protein immunoprecipitation) and pull down assays revealed that miR-1252-5p regulated LINC00520 in RISC-dependent. Furthermore, knockdown of LINC00520 inhibited lung ADC cells proliferation, migration and invasion, while co-transfection with a miR-1252-5p inhibitor inverted these influences. Additionally, the findings also demonstrated that FOXR2 was a target of miR-1252-5p; thus, LINC00520 could regulate FOXR2 level. Moreover, LINC00520 silencing suppressed the tumor growth of lung ADC in vivo. In summary, our data indicated that LINC00520 may act as a ceRNA to modulated FOXR2 level by sponging miR-1252-5p, which might bring a potential and effective biomarker to lung ADC treatment.

Long Noncoding RNA LINC01426 Sequesters microRNA-519d-5p to Promote Non-Small Cell Lung Cancer Progression by Increasing ETS1 Expression

PURPOSE

Recent studies have identified important roles for long intergenic non-protein coding RNA 1426 (LINC01426) in glioma and clear cell renal cell carcinoma. The present study evaluated the expression profile of LINC01426 in non-small cell lung cancer (NSCLC) tissues and cell lines. Furthermore, the function of LINC01426 in NSCLC and the molecular mechanisms involved were extensively studied.

METHODS

The abundance of LINC01426 in NSCLC tissues and cell lines was determined using quantitative reverse transcription-polymerase chain reaction. The cell counting kit-8 assay, flow cytometry, transwell experiments for migration and invasion, and xenograft tumor model were used to assess the function of LINC01426 in NSCLC cells. Mechanistic studies were performed using the luciferase reporter assay and RNA immunoprecipitation.

RESULTS

Significant LINC01426 upregulation was observed in NSCLC tissues and cell lines. Silencing LINC01426 inhibited proliferation, migration, and invasion of NSCLC cells and facilitated cell apoptosis in vitro. Furthermore, interference of LINC01426 restricted tumor growth of NSCLC cells in vivo. In addition, LINC01426 showed the ability to directly bind to microRNA-519d-5p (miR-519d-5p) and act as a molecular sponge for miR-519d-5p in NSCLC cells. Furthermore, the ETS proto-oncogene 1 (ETS1) was identified as a direct target of miR-519d-5p and LINC01426 could indirectly upregulate ETS1 expression by sponging miR-519d-5p. Moreover, the cancer-inhibiting activities of LINC01426 knockdown in NSCLC cells were partially offset by miR-519d-5p inhibition.

CONCLUSION

LINC01426 increases ETS1 expression by sequestering miR-519d-5p, thereby aggravating the malignant progression of NSCLC. The LINC01426/miR-519d-5p/ETS1 competing endogenous RNA pathway may provide a target for designing therapeutic agents for NSCLC treatment.

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.