Long non-coding RNA MIR503HG inhibits the proliferation, migration and invasion of colon cancer cells via miR-107/Par4 axis

The regulation of LRPs by miRNAs in cancer: influencing cancer characteristics and responses to treatment

The low-density lipoprotein receptor-related protein (LRP) family is a group of cell surface receptors that participate in a variety of biological processes, including lipid metabolism, Wnt signaling, and bone metabolism. miRNAs are small non-coding RNA molecules that regulate gene expression and play a role in many biological processes, including the occurrence and development of tumors. Accumulating evidence demonstrates that LRP members are modulated by miRNAs across multiple cancer types, influencing key oncogenic processes-including tumor cell proliferation, apoptosis suppression, extracellular matrix remodeling, cell adhesion, and angiogenesis. The LRPs, miRNAs, their upstream lncRNAs, and downstream signaling molecules often form complex signaling pathways to regulate the activity of tumor cells. However, the tissue-specific roles and mechanistic underpinnings of these pathways remain incompletely understood. When examining the emerging concept of the interaction between miRNAs and LRPs, we emphasize the significance of these complex regulatory layers in the initiation and progression of cancer. Collectively, these findings are critical for advancing our understanding of the role of the LRPs family in the occurrence and development of tumors, as well as for the development of new strategies for cancer treatment.

The oncogenic lncRNA MIR503HG suppresses cellular senescence counteracting supraphysiological androgen treatment in prostate cancer

BACKGROUND

The androgen receptor (AR), a ligand-dependent transcription factor, plays a key role in regulating prostate cancer (PCa) growth. The novel bipolar androgen therapy (BAT) uses supraphysiological androgen levels (SAL) that suppresses growth of PCa cells and induces cellular senescence functioning as a tumor suppressive mechanism. The role of long non-coding RNAs (lncRNAs) in the regulation of SAL-mediated senescence remains unclear. This study focuses on the SAL-repressed lncRNA MIR503HG, examining its involvement in androgen-controlled cellular senescence in PCa.

METHODS

Transcriptome and ChIP-Seq analyses of PCa cells treated with SAL were conducted to identify SAL-downregulated lncRNAs. Expression levels of MIR503HG were analyzed in 691 PCa patient tumor samples, mouse xenograft tumors and treated patient-derived xenografts. Knockdown and overexpression experiments were performed to assess the role of MIR503HG in cellular senescence and proliferation using senescence-associated β-Gal assays, qRT-PCRs, and Western blotting. The activity of MIR503HG was confirmed in PCa tumor spheroids.

RESULTS

A large patient cohort analysis shows that MIR503HG is overexpressed in metastatic PCa and is associated with reduced patient survival, indicating its potential oncogenic role. Notably, SAL treatment suppresses MIR503HG expression across four different PCa cell lines and patient-derived xenografts but interestingly not in the senescence-resistant LNCaP Abl EnzaR cells. Functional assays reveal that MIR503HG promotes PCa cell proliferation and inhibits SAL-mediated cellular senescence, partly through miR-424-5p. Mechanistic analyses and rescue experiments indicate that MIR503HG regulates the AKT-p70S6K and the p15INK4b-pRb pathway. Reduced expression of MIR503HG by SAL or knockdown resulted in decreased BRCA2 levels suggesting a role in DNA repair mechanisms and potential implications for PARP inhibitor sensitivity by SAL used in BAT clinical trial.

CONCLUSIONS

The lncRNA MIR503HG acts as an oncogenic regulator in PCa by repressing cellular senescence. SAL-induced suppression of MIR503HG enhances the tumor-suppressive effects of AR signaling, suggesting that MIR503HG could serve as a biomarker for BAT responsiveness and as a target for combination therapies with PARP inhibitors.

Long non-coding RNA H19X as a regulator of mononuclear cell adhesion to the endothelium in systemic sclerosis

OBJECTIVE

To define the functional relevance of H19 X-linked (H19X) co-expressed long non-coding RNA (lncRNA) in endothelial cell (EC) activation as a key process in SSc vasculopathy.

METHODS

H19X expression in SSc skin biopsies was analysed from single-cell RNA sequencing (scRNA-seq) data. Differential expression and pathway enrichment analysis between cells expressing (H19Xpos) and non-expressing H19X (H19Xneg) cells was performed. H19X function was investigated in human dermal microvascular ECs (HDMECs) by silencing. H19X and EC adhesion molecule levels were analysed by real-time quantitative PCR and western blot after stimulation with pro-inflammatory cytokines. Cytoskeletal rearrangements were analysed by fluorescent staining. Endothelial adhesion was evaluated by co-culture of HDMECs and fluorescent-labelled peripheral blood mononuclear cells (PBMCs). Shedding vascular cell adhesion protein 1 (VCAM1) was evaluated by ELISA on HDMEC supernatant.

RESULTS

The scRNA-seq data showed significant upregulation of H19X in SSc compared with healthy ECs. In HDMECs, H19X was consistently induced by IFN type I and II. H19X knockdown lead to a significant decrease in the mRNA of several adhesion molecules. In particular, VCAM1 was significantly reduced at the protein and mRNA levels. Co-expression analysis of the scRNA-seq data confirmed higher expression of VCAM1 in H19Xpos ECs. ECs were also strongly associated with the 'cell adhesion molecule' pathway. Moreover, the VCAM1 downstream pathway displayed less activation following H19X knockdown. Contractility of HDMECs, PBMC adhesion to HDMECs and VCAM1 shedding were also reduced following H19X knockdown.

CONCLUSIONS

lncRNA H19X may contribute to EC activation in SSc vasculopathy, acting as a regulator of expression of adhesion molecules in ECs.

Exploring the Key Signaling Pathways and ncRNAs in Colorectal Cancer

Colorectal cancer (CRC) is the third most prevalent cancer to be diagnosed, and it has a substantial mortality rate. Despite numerous studies being conducted on CRC, it remains a significant health concern. The disease-free survival rates notably decrease as CRC progresses, emphasizing the urgency for effective diagnostic and therapeutic approaches. CRC development is caused by environmental factors, which mostly lead to the disruption of signaling pathways. Among these pathways, the Wingless/Integrated (Wnt) signaling pathway, Phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) signaling pathway, Mitogen-Activated Protein Kinase (MAPK) signaling pathway, Transforming Growth Factor-β (TGF-β) signaling pathway, and p53 signaling pathway are considered to be important. These signaling pathways are also regulated by non-coding RNAs (ncRNAs), including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs). They have emerged as crucial regulators of gene expression in CRC by changing their expression levels. The altered expression patterns of these ncRNAs have been implicated in CRC progression and development, suggesting their potential as diagnostic and therapeutic targets. This review provides an overview of the five key signaling pathways and regulation of ncRNAs involved in CRC pathogenesis that are studied to identify promising avenues for diagnosis and treatment strategies.

Enhancing protein production and growth in chinese hamster ovary cells through miR-107 overexpression

Chinese Hamster Ovary (CHO) cells are widely employed as host cells for biopharmaceutical production. The manufacturing of biopharmaceuticals poses several challenges, including restricted growth potential and inadequate productivity of the host cells. MicroRNAs play a crucial role in regulating gene expression and are considered highly promising tools for cell engineering to enhance protein production. Our study aimed to evaluate the effects of miR-107, which is recognized as an onco-miR, on erythropoietin-producing CHO cells (CHO-hEPO). To assess the impact of miR-107 on CHO cells, a DNA plasmid containing miR-107 was introduced to CHO-hEPO cells through transfection. Cell proliferation and viability were assessed using the trypan blue dye exclusion method. Cell cycle analysis was conducted by utilizing propidium iodide (PI) staining. The quantification of EPO was determined using an immunoassay test. Moreover, the impact of miR-107 on the expression of downstream target genes was evaluated using qRT-PCR. Our findings highlight and underscore the substantial impact of transient miR-107 overexpression, which led to a remarkable 2.7-fold increase in EPO titers and a significant 1.6-fold increase in the specific productivity of CHO cells (p < 0.01). Furthermore, this intervention resulted in significant enhancements in cell viability and growth rate (p < 0.05). Intriguingly, the overexpression of miR‑107 was linked to the downregulation of LATS2, PTEN, and TSC1 genes while concurrently driving upregulation in transcript levels of MYC, YAP, mTOR, and S6K genes within transgenic CHO cells. In conclusion, this study collectively underscores the feasibility of utilizing cancer-associated miRNAs as a powerful tool for CHO cell engineering. However, more in-depth exploration is warranted to unravel the precise molecular intricacies of miR-107's effects in the context of CHO cells.

Potential Clinical Role of LncRNA miR503HG in Multiple Myeloma and its Effect on the Proliferation and Adhesion of Myeloma Cells

This study mainly explored the role of lncRNA miR503HG in multiple myeloma and the potential downstream regulatory mechanism affecting disease. Real-time quantitative polymerase chain reaction was used to measure the expression levels of miR503HG and miR-103. A cell counting kit-8 assay was performed to detect cell viability. The concentrations of adhesion-related factors (MUC-1, VCAM-1, ICAM-1) were determined using enzyme-linked immunosorbent assay. The targeting relationship between miR503HG and miR-103 was detected by dual-luciferase reporter assay. The miR503HG expression in peripheral blood of multiple myeloma patients was lower than that of normal healthy individuals and associated with ISS stage and worse overall survival. miR-103 was identified as the downstream target of miR503HG. Upregulation of miR503HG could inhibit cell proliferation and adhesion of multiple myeloma cell lines, which could partially reverse the inhibition of adhesion and proliferation by high expression of miR-103. lncRNA miR503HG expression was downregulated in multiple myeloma and had potential diagnostic/prognostic value. MiR503HG exerts a molecular sponge effect on miR-103 and affects its expression, thus achieving the inhibitory effect on multiple myeloma.

Effect of silkworm pupae (Bombyx mori) protein on colon cancer in nude mice: inhibition of tumor growth, oxidative stress and inflammatory response

Silkworm pupa (bombyx mori) protein (SPP) is a potential therapeutic bioactive substance that has anti-tumor activity against breast, liver, and gastric cancers. The aim of this study was to investigate the antitumor effect of SPP on colon cancer nude mice. Using a subcutaneous tumor formation method, we validated the therapeutic effect of SPP on colon cancer nude mice in vivo. Results showed that SPP was cytotoxic to tumor cells. SPP could protect the liver of the nude mice by lowering hepatic oxidative stress and regulating serum inflammation levels by decreasing TNF-α and IL-2 levels while in-creasing INF-γ levels. In addition, diminished Ki-67 protein, enhanced cleaved caspase-3 protein, di-minished Vimentin, enhanced E-cadherin. These findings suggested that SPP's antitumor activity may be achieved by reducing inflammation, inhibiting tumor proliferation and metastasis, and inducing apoptosis in cancer cells. In the future, SPP could be used as an anticancer drug, potentially providing a new source of drugs for the treatment of colon cancer.

MIR503HG: A potential diagnostic and therapeutic target in human diseases

LncRNAs are involved in many physiological and pathological processes, including chromatin remodeling, transcription, posttranscriptional gene expression, mRNA stability, translation, and posttranslational modification, and their functions depend on subcellular localization. MIR503HG is a lncRNA as well as a host gene for the miRNAs miR-503 and miR-424. MIR503HG functions independently or synergistically with miR-503. MIR503HG affects cell proliferation, invasion, metastasis, apoptosis, angiogenesis, and other biological behaviors. The mechanism of MIR503HG in disease includes interaction with protein, sponging miRNA to regulate downstream target gene, and participation in NF-κB, TGF-β, ERK/MAPK, and PI3K/AKT signaling pathways. In this review, we summarize the molecular mechanisms of MIR503HG in disease and its potential applications in diagnosis, prognosis, and treatment. We also raise some unanswered questions in this area, providing insights for future research.

Lipid Handling Protein Gene Expression in Colorectal Cancer: CD36 and Targeting miRNAs

The reprogramming of lipid metabolism has been highlighted in colorectal cancer (CRC) studies, suggesting a critical role for the scavenger receptor CD36 and fatty acid synthase (FASN) in this malignancy. In this study, we analyzed the gene expression levels of CD36, FASN, the cell surface glypican 4 (GPC4), and the two transporters SLC27A3 and SLC27A4 in 39 paired tumoral and peritumoral tissues from patients with CRC compared with 18 normal colonic mucosae. Moreover, the levels of seven miRNAs targeting CD36 and most of the analyzed genes were evaluated. We found a significant impairment of the expression of all the analyzed genes except GPC4 as well as the differential expression of miR-16-5p, miR-26b-5p, miR-107, miR-195-5p, and miR-27a-3p in the colonic mucosa of CRC patients. Interestingly, CD36 and miR-27a-3p were downregulated and upregulated, respectively, in tumoral tissues compared to peritumoral and control tissues, with a significant negative correlation in the group of patients developing lymph node metastasis. Our results sustain the relationship between CRC and fatty acid metabolism and emphasize the importance of related miRNAs in developing new therapeutic strategies.

Overexpression of LncRNA MNX1-AS1/PPFIA4 Activates AKT/HIF-1α Signal Pathway to Promote Stemness of Colorectal Adenocarcinoma Cells

PURPOSE

The purpose of this study was to explore the role of the lncRNA MNX1-AS1 and its related downstream signaling pathways in colorectal adenocarcinoma (COAD).

METHODS

COAD tissues and cells were prepared and treated with sh-MNX1-AS1, pcDNA-MNX1-AS1, sh-PPFIA4, LY29004, and their controls. CCK8 and colony formation assays were undertaken for evaluating cell proliferation. Tumor cell migratory ability was detected by transwell assay. Apoptosis detection was processed by YO-PRO-1/PI Staining. The regulated relationship between lncRNA MNX1-AS1 and PPFIA4 was confirmed by RIP-ChIP assay. Q-PCR was applied to detect genes related to tumor cell stemness, proliferation, migration, and apoptosis in each group. Finally, a xenograft tumor model was constructed to verify the result in vivo.

RESULTS

COAD patients with high expression of the lncRNA MNX1-AS1 have poor prognosis. LncRNA MNX1-AS1 promotes the stemness of COAD cells. PPFIA4 mediates lncRNA MNX1-AS1 expression and affects COAD cell stemness. LncRNA MNX1-AS1 accelerates proliferation and migration, while it suppresses apoptosis. LncRNA MNX1-AS1/PPFIA4 accelerates tumor growth in COAD model. LncRNA MNX1-AS1/PPFIA4 activates the downstream AKT/HIF-1α signaling pathway to promote COAD development. LY29004 significantly inhibits the tumorigenic ability of lncRNA MNX1-AS1 and PPFIA4.

CONCLUSION

LncRNA MNX1-AS1/PPFIA4 activates AKT/HIF-1α signal pathway to promote the stemness of COAD cells, which could be a new target for COAD treatment.

Transcriptome profiling and co-expression network analysis of lncRNAs and mRNAs in colorectal cancer by RNA sequencing

Background

Long non-coding RNAs (lncRNAs) are widely involved in the pathogenesis of cancers. However, biological roles of lncRNAs in occurrence and progression of colorectal cancer (CRC) remain unclear. The current study aimed to evaluate the expression pattern of lncRNAs and messenger RNAs (mRNAs).

Methods

RNA sequencing (RNA-Seq) in CRC tissues and adjacent normal tissues from 6 CRC patients was performed and functional lncRNA-mRNA co-expression network was constructed afterwards. Gene enrichment analysis was demonstrated using DAVID 6.8 tool. Reverse transcription quantitative polymerase chain reaction (RT-qPCR) was used to validate the expression pattern of differentially expressed lncRNAs. Pearson correlation analysis was applied to evaluate the relationships between selected lncRNAs and mRNAs.

Results

One thousand seven hundred and sixteenth differentially expressed mRNAs and 311 differentially expressed lncRNAs were screened out. Among these, 568 mRNAs were up-regulated while 1148 mRNAs down-regulated, similarly 125 lncRNAs were up-regulated and 186 lncRNAs down-regulated. In addition, 1448 lncRNA–mRNA co-expression pairs were screened out from 940,905 candidate lncRNA-mRNA pairs. Gene enrichment analysis revealed that these lncRNA-related mRNAs are associated with cell adhesion, collagen adhesion, cell differentiation, and mainly enriched in ECM-receptor interaction and PI3K-Akt signaling pathways. Finally, RT-qPCR results verified the expression pattern of lncRNAs, as well as the relationships between lncRNAs and mRNAs in 60 pairs of CRC tissues.

Conclusions

In conclusion, these results of the RNA-seq and bioinformatic analysis strongly suggested that the dysregulation of lncRNA is involved in the complicated process of CRC development, and providing important insight regarding the lncRNAs involved in CRC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09878-6.

MIR503HG impeded ovarian cancer progression by interacting with SPI1 and preventing TMEFF1 transcription

MIR503 host gene (MIR503HG) acts as an important tumor suppressor in many human cancers, but its role and regulatory mechanism in ovarian cancer need to be further studied. In this study, lower expressed MIR503HG was observed in ovarian tumor tissues and cells than in adjacent normal tissues and normal human ovarian epithelial cells. MIR503HG overexpression impaired the proliferative, invasive and EMT properties, and facilitated cell apoptosis in ovarian cancer cells. Nuclear and cytoplasmic separation test suggested that MIR503HG was mainly expressed in the nucleus. RNA immunoprecipitation and RNA pull-down assays confirmed that MIR503HG could bind to transcription factor SPI1 (Spi-1 proto-oncogene), and dual luciferase reporter gene and Chromatin immunoprecipitation assays verified that SPI1 could bind to TMEFF1 (Transmembrane protein with EGF like and two follistatin like domains 1) promoter, suggesting that MIR503HG suppressed TMEFF1 expression by competitively binding SPI1 and blocking transcriptional activation of TMEFF1. Moreover, interference with TMEFF1 reversed the promotion effect of MIR503HG silence on the malignant behaviors of ovarian cancer cells. Moreover, MIR503HG knockdown activated the MAPK and PI3K/AKT pathways by increasing the expression of TMEFF1. In addition, overexpression of MIR503HG in vivo suppressed the tumorigenic ability in nude mice. In conclusion, MIR503HG acted as a tumor suppressor lncRNA in ovarian cancer by suppressing transcription factor SPI1-mediated transcriptional activation of TMEFF1.

MCP mediated active targeting calcium phosphate hybrid nanoparticles for the treatment of orthotopic drug-resistant colon cancer

BACKGROUND

Colon cancer is a most common malignant cancer in digestive system, and it is prone to develop resistance to the commonly used chemotherapy drugs, leading to local recurrence and metastasis. Paris saponin VII (PSVII) could not only inhibit the proliferation of colon cancer cells but also effectively induce apoptosis of drug-resistant colon cancer cells and reduce the metastasis of drug-resistant colon cancer cells as well. However, PSVII was insoluble in water and fat. It displayed no selective distribution in body and could cause severe hemolysis. Herein, colon cancer targeting calcium phosphate nanoparticles were developed to carry PSVII to treat drug-resistant colon cancer.

RESULTS

PSVII carboxymethyl-β-cyclodextrin inclusion compound was successfully encapsulated in colon cancer targeting calcium phosphate nanoparticles (PSVII@MCP-CaP) by using modified citrus pectin as stabilizer agent and colon cancer cell targeting moiety. PSVII@MCP-CaP significantly reduced the hemolysis of PSVII. Moreover, by specific accumulating in orthotopic drug-resistant colon cancer tissue, PSVII@MCP-CaP markedly inhibited the growth of orthotopic drug-resistant colon cancer in nude mice. PSVII@MCP-CaP promoted the apoptosis of drug-resistant colon cancer cells through mitochondria-mediated apoptosis pathway. Moreover, PSVII@MCP-CaP significantly inhibited the invasion and migration of drug-resistant colon cancer cells by increasing E-cadherin protein expression and reducing N-cadherin and MMP-9 protein expression.

CONCLUSION

PSVII@MCP-CaP has great potential in the treatment of drug-resistant colon cancer. This study also explores a new method to prepare active targeting calcium phosphate nanoparticles loaded with a fat and water insoluble compound in water.

Four Prognosis-Associated lncRNAs Serve as Biomarkers in Ovarian Cancer

Long non-coding RNAs (lncRNAs) play crucial roles in ovarian cancer (OC) development. However, prognosis-associated lncRNAs (PALs) for OC have not been completely elucidated. Our study aimed to identify the PAL signature of OC. A total of 663 differentially expressed lncRNAs were identified in the databases. According to the weighted gene coexpression analysis, the highly correlated genes were clustered into seven modules related to the clinical phenotype of OC. A total of 25 lncRNAs that were significantly related to overall survival were screened based on univariate Cox regression analysis. The prognostic risk model constructed contained seven PALs based on the parameter λ_min, which could stratify OC patients into two risk groups. The results showed that the risk groups had different overall survival rates in both The Cancer Genome Atlas (TCGA) and two verified Gene Expression Omnibus (GEO) databases. Univariate and multivariate Cox regression analyses confirmed that the risk model was an independent risk factor for OC. Gene enrichment analysis revealed that the identified genes were involved in some pathways of malignancy. The competitive endogenous RNA (ceRNA) network included five PALs, of which four were selected for cell function assays. The four PALs were downregulated in 33 collected OC tissues and 3 OC cell lines relative to the control. They were shown to regulate the proliferative, migratory, and invasive potential of OC cells via Cell Counting Kit-8 (CCK-8) and transwell assays. Our study fills the gaps of the four PALs in OC, which are worthy of further study.

LncRNA EPB41L4A-AS2 represses Nasopharyngeal Carcinoma Metastasis by binding to YBX1 in the Nucleus and Sponging MiR-107 in the Cytoplasm

Nasopharyngeal carcinoma (NPC) is known for its potential to progress to the lymph nodes and distant metastases at an early stage. As an important regulator in tumorigenesis biological processes, the functions of lncRNA in NPC tumor development remain largely unclear. In this research, the expression of EPB41L4A-AS2 in NPC tissues and cells was analyzed via real-time quantitative polymerase chain reaction (qRT-PCR). CCK8, colony formation, and EDU experiments were used to determine the viability of NPC cells. Transwell and wound healing assays were performed to test NPC cell migration and invasion. RNA pull-down and mass spectrometry analysis were used to identify potential binding proteins. Then, a popliteal lymph node metastasis model was established to test NPC metastasis. EPB41L4A-AS2 is repressed by transforming growth factor-beta, which is downregulated in NPC cells and tissue. It is associated with the presence of distant metastasis and adverse outcomes. The univariate and multivariate survival assays confirmed that EPB41L4A-AS2 expression was an independent predictor of progression-free survival (PFS) in patients with NPC. Biological analyses showed that overexpression of EPB41L4A-AS2 reduced the metastasis and invasion of NPC in vitro and in vivo, but had no significant effect on cell proliferation. Mechanistically, in the nucleus we identified that EPB41L4A-AS2 relies on binding to YBX1 to reduce the stability of Snail mRNA to enhance the expression of E-cadherin and reverse the progression of epithelial-to-mesenchymal transition (EMT). In the cytoplasm, we found that EPB41L4A-AS2 blocked the invasion and migration of NPC cells by promoting LATS2 expression via sponging miR-107. In a whole, the findings of this study help to further understand the metastasis mechanism of NPC and could help in the prevention and treatment of NPC metastasis.

lncRNA MIR503HG inhibits cell proliferation and promotes apoptosis in TNBC cells via the miR-224-5p/HOXA9 axis

Triple-negative breast cancer (TNBC) is a highly invasive subtype of breast cancer. This study investigated the molecular mechanism and influences of MIR503HG, miR-224-5p, and homeobox A9 (HOXA9) on TNBC cell growth and migration. Dual-luciferase reporter gene and RNA immunoprecipitation were performed to examine the regulation of MIR503HG, miR-224-5p, and HOXA9. Cell proliferation, apoptosis, migration, and invasion were evaluated by colony formation, flow cytometry, and Transwell assays. Finally, nude mice were employed to investigate the influence of MIR503HG on TNBC tumor growth. HOXA9 protein levels were detected by immunohistochemical staining. MIR503HG and HOXA9 expression were reduced in TNBC, while miR-224-5p was increased. Overexpression of MIR503HG or HOXA9 reduced the cell migration ability and proliferation and promoted apoptosis, and knockdown of MIR503HG or overexpression of miR-224-5p exhibited the opposite effects. Furthermore, MIR503HG promoted HOXA9 expression by inhibiting miR-224-5p. Overexpression of miR-224-5p reversed the effects of MIR503HG overexpression on TNBC cells, while overexpression of HOXA9 reversed the effect of MIR503HG knockdown. Additionally, an in vivo study proved that MIR503HG inhibited TNBC tumor growth via the miR-224-5p/HOXA9 axis. MIR503HG inhibited cell proliferation and promoted the apoptosis of TNBC cells via the miR-224-5p/HOXA9 axis, which may function as a novel target for the treatment of TNBC.