miR-214 modulates cisplatin sensitivity of osteosarcoma cells through regulation of anaerobic glycolysis

Deciphering chemoresistance in osteosarcoma: Unveiling regulatory mechanisms and function through the lens of noncoding RNA

Osteosarcoma (OS) is a primary malignant bone tumor and is prevalent in children, adolescents, and elderly individuals. It has the characteristics of high invasion and metastasis. Neoadjuvant chemotherapy combined with surgical resection is the most commonly used treatment for OS. However, the efficacy of OS is considerably diminished by chemotherapy resistance. In recent years, noncoding RNAs (ncRNAs), including microRNAs, long noncoding RNAs, and circular RNAs, are hot topics in the field of chemotherapy resistance research. Several studies have demonstrated that ncRNAs are substantially associated with chemoresistance in OS. Thus, the present study overviews the abnormally expressed ncRNAs in OS and the molecular mechanisms involved in chemoresistance, with an emphasis on their function in promoting or inhibiting chemoresistance. ncRNAs are expected to become potential therapeutic targets for overcoming drug resistance and predictive biomarkers in OS, which are of great significance for enhancing the therapeutic effect and improving the prognosis.

Non-coding RNAs in metabolic reprogramming of bone and soft tissue sarcoma: Fundamental mechanism and clinical implication

Sarcomas, comprising approximately 1% of human malignancies, show a poor response to treatment and easy recurrence. Metabolic reprogramming play an important role in tumor development in sarcomas. Accumulating evidence shows that non-coding RNAs (ncRNAs) participate in regulating the cellular metabolism of sarcomas, which improves the understanding of the development of therapy-resistant tumors. This review addresses the regulatory roles of metabolism-related ncRNAs and their implications for sarcoma initiation and progression. Dysregulation of metabolism-related ncRNAs is common in sarcomas and is associated with poor survival. Emerging studies show that abnormal expression of metabolism-related ncRNAs affects cellular metabolism, including glucose, lipid, and mitochondrial metabolism, and leads to the development of aggressive sarcomas. This review summarizes recent advances in the roles of dysregulated metabolism-related ncRNAs in sarcoma development and stemness and describes their potential to serve as biological biomarkers for disease diagnosis and prognosis prediction, as well as therapeutic targets for treating refractory sarcomas.

Advances in the Biological Functions and Mechanisms of miRNAs in the Development of Osteosarcoma

Osteosarcoma is one of the most common primary malignant bone tumors, mainly occurring in children and adolescents, and is characterized by high morbidity and poor prognosis. MicroRNAs, a class of noncoding RNAs consisting of 19 to 25 nucleotides, are involved in cell proliferation, invasion, metastasis, and apoptosis to regulate the development and progression of osteosarcoma. Studies have found that microRNAs are closely related to the diagnosis, treatment, and prognosis of osteosarcoma patients and have an important role in improving drug resistance in osteosarcoma. This paper reviews the role of microRNAs in the pathogenesis of osteosarcoma and their clinical value, aiming to provide a new research direction for diagnosing and treating osteosarcoma and achieving a better prognosis.

Noncoding RNAs in triple negative breast cancer: Mechanisms for chemoresistance

Triple-negative breast cancer (TNBC) is the most aggressive subtype among breast cancers with high recurrence and this condition is partly due to chemoresistance. Therefore, fully understanding the mechanism of TNBC-resistance is the key to overcoming chemoresistance, which will be an effective strategy for TNBC therapy. Various potential mechanisms involved in the chemoresistance of TNBC have been investigated and indicated that noncoding RNAs (ncRNAs) especially microRNAs (miRNAs), long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs) take part in most TNBC resistance. The ncRNA-induced chemoresistance process is involved in the alteration of many activities. here, we mainly summarize the mechanisms of ncRNAs in the chemoresistance of TNBC and discuss the potential clinical application of ncRNAs in the treatment of TNBC, indicating that targeting ncRNAs might be a promising strategy for resensitization to chemotherapies.

Lnc-RP11-536 K7.3/SOX2/HIF-1α signaling axis regulates oxaliplatin resistance in patient-derived colorectal cancer organoids

Background

Resistance to oxaliplatin is a major obstacle for the management of locally advanced and metastatic colon cancer (CC). Although long noncoding RNAs (lncRNAs) play key roles in CC, the relationships between lncRNAs and resistance to oxaliplatin have been poorly understood yet.

Methods

Chemo-sensitive and chemo-resistant organoids were established from colon cancer tissues of the oxaliplatin-sensitive or -resistant patients. Analysis of the patient cohort indicated that lnc-RP11-536 K7.3 had a potential oncogenic role in CC. Further, a series of functional in vitro and in vivo experiments were conducted to assess the effects of lnc-RP11-536 K7.3 on CC proliferation, glycolysis, and angiogenesis. RNA pull-down assay, luciferase reporter and fluorescent in situ hybridization assays were used to confirm the interactions between lnc-RP11-536 K7.3, SOX2 and their downstream target HIF-1α.

Results

In this study, we identified a novel lncRNA, lnc-RP11-536 K7.3, was associated with resistance to oxaliplatin and predicted a poor survival. Knockout of lnc-RP11-536 K7.3 inhibited the proliferation, glycolysis, and angiogenesis, whereas enhanced chemosensitivity in chemo-resistant organoids and CC cells both in vitro and in vivo. Furthermore, we found that lnc-RP11-536 K7.3 recruited SOX2 to transcriptionally activate USP7 mRNA expression. The accumulative USP7 resulted in deubiquitylation and stabilization of HIF-1α, thereby facilitating resistance to oxaliplatin.

Conclusion

In conclusion, our findings indicated that lnc-RP11-536 K7.3 could promote proliferation, glycolysis, angiogenesis, and chemo-resistance in CC by SOX2/USP7/HIF-1α signaling axis. This revealed a new insight into how lncRNA could regulate chemosensitivity and provide a potential therapeutic target for reversing resistance to oxaliplatin in the management of CC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-02143-x.

Knockdown of microRNA-203 reduces cisplatin chemo-sensitivity to osteosarcoma cell lines MG63 and U2OS in vitro by targeting RUNX2

Clinical studies have reported that miRNAs abnormal expression are associated with the generation of cisplatin-resistant to osteosarcoma. Our previous research found that miR-203 is downregulated in osteosarcoma cells and overexpressed miR-203 exerts antitumor properties on osteosarcoma cells. However, the role and mechanism of miR-203 in regulating the sensitivity of cisplatin in osteosarcoma cells remains unclear. This study aimed to investigate the effects of miR-203 in cisplatin therapy for osteosarcoma cells in vitro and determined the underlying mechanism. In this study, we found that miR-203 was significantly upregulated in osteosarcoma cells after exposure to cisplatin. miR-203 knockdown reduced the sensitivity of osteosarcoma cells to cisplatin by suppressing cell apoptosis, cell cycle arrest, and inducing invasion. Meanwhile, we found that miR-203 knockdown reduces the therapeutic sensitivity of osteosarcoma cells by upregulating RUNX2. Moreover, we found that RUNX2 silencing sensitizes osteosarcoma cells to chemotherapy treatment of cisplatin. In summary, our findings demonstrated that miR-203 knockdown reduces cisplatin chemo-sensitivity to osteosarcoma cells in vitro by targeting RUNX2, and speculated that miR-203 may be a target for drug resistance of osteosarcoma to cisplatin.

Noncoding RNAs in osteosarcoma: Implications for drug resistance

Osteosarcoma is the most frequent bone malignancy in children and adolescents. Despite advances of surgery and chemotherapy in osteosarcoma over the past decades, overall survival rates of osteosarcoma have reached a plateau. The development of multi-drug resistance (MDR) has become the main obstacle in improving chemotherapeutic effects in osteosarcoma treatment. Therefore, understanding detailed mechanisms of chemoresistance and developing novel therapeutic targets to overcome chemoresistance are crucial to improve the prognosis of osteosarcoma patients. Accumulating evidence has proved that multiple noncoding RNAs (ncRNAs), including microRNAs (miRNAs), long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs) play pivotal roles in osteosarcoma progression. Notably, a great number of ncRNAs are abnormally expressed and can regulate chemosensitivity through various mechanisms in osteosarcoma. In this review, we systematically summarize the roles of ncRNAs as well as the molecular mechanisms in modulating drug resistance of osteosarcoma and discuss the potential roles of ncRNAs as biomarkers and novel therapeutic targets for osteosarcoma.

LncRNA-SARCC sensitizes osteosarcoma to cisplatin through the miR-143-mediated glycolysis inhibition by targeting Hexokinase 2

Chemotherapy is one of the primary treatments used against cancer. Cisplatin is a conventional chemotherapy drug used to treat osteosarcoma; however, due to the development of cisplatin resistance, advantageous therapeutic outcomes and prognosis of osteosarcoma remain low. Thus, investigation of the specific targeted therapies to circumvent the anti-chemoresistance of osteosarcoma depends on understanding the molecular mechanisms underlying cisplatin resistance. Tumor cells display an increased utilization of glycolysis rather than oxidative phosphorylation. This phenomenon is called the "Warburg effect," which presents a survival advantage for tumor cells, leading to chemoresistance. To date, the molecular mechanism underlying osteosarcoma cisplatin resistance remains to be fully elucidated. In this study, we reported the significant down-regulation of the long noncoding RNA-Suppressing Androgen Receptor in Renal Cell Carcinoma (lncRNA-SARCC) in the cells of osteosarcoma and in the specimens from osteosarcoma patients. Moreover, we observed a negative correlation between the lncRNA-SARCC and cisplatin resistance in the osteosarcoma tissues. Overexpression of the lncRNA-SARCC sensitizes osteosarcoma cells to cisplatin. From microarray analysis, we screened several miRNAs, which are significantly regulated by the lncRNA-SARCC in osteosarcoma cells, and revealed that lncRNA-SARCC promoted microRNA-43 (miR-143) expression in osteosarcoma. Interestingly, miR-143 showed the same expression pattern with the lncRNA-SARCC in osteosarcoma patient specimens. By establishing a cisplatin-resistant cell line from Sarcoma Osteogenic-2 (Saos-2), we found the cisplatin-resistant cells with down-regulated expressions of the lncRNA-SARCC and miR-143, but with a higher glycolysis rate compared to that in parental cells. We identified the glycolysis key enzyme, Hexokinase 2 (HK2), as a direct target for miR-143 in osteosarcoma. Restoration of the HK2 expression in the lncRNA-SARCC-overexpressing osteosarcoma cells reversed cisplatin resistance, suggesting that lncRNA-SARCC-mediated cisplatin sensitivity may be via glycolysis in the miR-143-inhibited osteosarcoma cells. Finally, results from both in vitro and in vivo xenograft models demonstrated that the lncRNA-SARCC was an effective therapeutic agent for overcoming cisplatin resistance in osteosarcoma. Our findings suggest an essential axis of the lncRNA-SARCC-miR-143-HK2 in regulation of osteosarcoma chemosensitivity, presenting the lncRNA-SARCC as a new therapeutic target against cisplatin-resistant osteosarcoma.

miR-16-5p Suppresses Progression and Invasion of Osteosarcoma via Targeting at Smad3

Background

MicroRNAs are known to regulate carcinogenesis of osteosarcoma. Although, miR-16-5p is known to exert inhibitory effects on several forms of cancers, its effects on the growth and invasion of osteosarcoma have not been studied.

Methods

We collected human osteosarcoma specimens and adjacent tissues to detect the expression of miR-16-5p by real-time polymerase chain reaction, immunoblotting, and immunohistochemistry. The proliferation, migration, and invasion of MG63 and HOS cells following miR-16-5p overexpression and inhibition were detected with cell counting kit-8, wound healing assay, and Transwell assay, respectively. An expression vector carrying a mutated 3'-untranslated region of mothers against decapentaplegic homolog 3 (Smad3) was constructed.

Results

The results showed that miR-16-5p expression was downregulated in osteosarcoma tissues and cells as compared with adjacent counterparts, while Smad3 was overexpressed in osteosarcoma cells. The overexpression of miR-16-5p resulted in the inhibition of the proliferation, migration, and invasion of osteosarcoma cells and enhanced the therapeutic effect of cisplatin. These effects were attenuated with miR-16-5p expression inhibition. In cells transfected with miR-16-5p mimic, Smad3 expression decreased, while this effect was absent in the cells carrying mutated Smad3.

Conclusions

Therefore, miR-16-5p inhibits the growth and invasion of osteosarcoma by targeting Smad3.

The role of microRNA in cisplatin resistance or sensitivity

INTRODUCTION

Cisplatin is a chemotherapy drug that has been used to treat a number of cancers for decades, and is still one of the most commonly used anti-cancer agents. However, some patients do not respond to cisplatin while other patients who were originally sensitive to cisplatin eventually develop chemoresistance, leading to treatment failure or/and tumor recurrence.

AREAS COVERED

Different mechanisms contribute to cisplatin resistance or sensitivity, involving multiple pathways or/and processes such as DNA repair, DNA damage response, drug transport, and apoptosis. Among the various mechanisms, it appears that microRNAs play an important role in determining the resistance or sensitivity. In this article, we analyzed and summarized recent findings in this area, with the aim that these data can aid further research and understanding, leading to the eventual reduction of cisplatin resistance.

EXPERT COMMENTARY

microRNAs can positively or negatively regulate cisplatin resistance by acting on molecules or/and pathways related to apoptosis, autophagy, hypoxia, cancer stem cells, NF-κB, and Notch1. It appears that the modulation of relevant microRNAs can effectively re-sensitize cancer cells to cisplatin regimen in certain types of cancers including breast, colorectal, gastric, liver, lung, ovarian, prostate, testicular, and thyroid cancers.

miR-16-5p/PDK4-Mediated Metabolic Reprogramming Is Involved in Chemoresistance of Cervical Cancer

Cervical cancer is one of the most prevalent malignancies in women worldwide. Therefore, investigation about molecular pathogenesis and related therapy targets of cervical cancer is an emergency. The molecular mechanisms responsible for the chemoresistance of cervical cancer were investigated by the use of doxorubicin (Dox)-resistant HeLa/Dox and SiHa/Dox cells. Our data showed that chemoresistant cells exhibited significantly higher glucose consumption, lactate production rate, and ATP levels than that of their parental cells. Among metabolic and glycolytic related genes, the expression of PDK4 was upregulated in Dox-resistant cells. Knockdown of PDK4 can decrease glucose consumption, lactate production rate, and ATP levels and further sensitize resistant cervical cancer cells to Dox treatment. By screening microRNAs (miRNAs), which can regulate expression of PDK4, we found that miR-16-5p was downregulated in chemoresistant cells. Overexpression of miR-16-5p can decrease the expression of PDK4 and sensitize the resistant cells to Dox treatment. Xenograft models confirmed that knockdown of PDK4 can increase chemotherapy efficiency for in vivo tumor growth. Collectively, our data suggested that miR-16-5p/PDK4-mediated metabolic reprogramming is involved in chemoresistance of cervical cancer.

Targeting Nuclear NAD+ Synthesis Inhibits DNA Repair, Impairs Metabolic Adaptation and Increases Chemosensitivity of U-2OS Osteosarcoma Cells

Osteosarcoma (OS) is the most common bone tumor in children and adolescents. Modern OS treatment, based on the combination of neoadjuvant chemotherapy (cisplatin + doxorubicin + methotrexate) with subsequent surgical removal of the primary tumor and metastases, has dramatically improved overall survival of OS patients. However, further research is needed to identify new therapeutic targets. Here we report that expression level of the nuclear NAD synthesis enzyme, nicotinamide mononucleotide adenylyltransferase-1 (NMNAT1), increases in U-2OS cells upon exposure to DNA damaging agents, suggesting the involvement of the enzyme in the DNA damage response. Moreover, genetic inactivation of NMNAT1 sensitizes U-2OS osteosarcoma cells to cisplatin, doxorubicin, or a combination of these two treatments. Increased cisplatin-induced cell death of NMNAT1^−/− cells showed features of both apoptosis and necroptosis, as indicated by the protective effect of the caspase-3 inhibitor z-DEVD-FMK and the necroptosis inhibitor necrostatin-1. Activation of the DNA damage sensor enzyme poly(ADP-ribose) polymerase 1 (PARP1), a major consumer of NAD⁺ in the nucleus, was fully blocked by NMNAT1 inactivation, leading to increased DNA damage (phospho-H2AX foci). The PARP inhibitor, olaparib, sensitized wild type but not NMNAT1^−/− cells to cisplatin-induced anti-clonogenic effects, suggesting that impaired PARP1 activity is important for chemosensitization. Cisplatin-induced cell death of NMNAT1^−/− cells was also characterized by a marked drop in cellular ATP levels and impaired mitochondrial respiratory reserve capacity, highlighting the central role of compromised cellular bioenergetics in chemosensitization by NMNAT1 inactivation. Moreover, NMNAT1 cells also displayed markedly higher sensitivity to cisplatin when grown as spheroids in 3D culture. In summary, our work provides the first evidence that NMNAT1 is a promising therapeutic target for osteosarcoma and possibly other tumors as well.

MiR-138 Suppresses the PDK1 Expression to Decrease the Oxaliplatin Resistance of Colorectal Cancer

Background

Oxaliplatin is one kind of platinum-based drug. It is effective and commonly used in the treatment of colorectal cancer (CRC). However, development of acquired drug resistance is still a big obstacle during the oxaliplatin therapy. It is urgent to take strategies to decrease the oxaliplatin resistance of CRC.

Materials and Methods

Oxaliplatin-resistant HT29 and SW480 (HT29/R and SW480/R) cells were acquired through long-term exposure to oxaliplatin by using the routine HT29 and SW480 cells. Relative glucose consumption, lactate generation and LDH activity were tested to evaluate the glycolysis of CRC cell lines. MTT assays were conducted to evaluate the differences of oxaliplatin sensitivity between HT29/R (SW480/R) cells and their parental HT29 (SW480) cells. Regulation of miR-138 on PDK1 was confirmed through qRT-PCR, Western blot and dual-luciferase reporter assays. Reactive oxygen species (ROS) levels were measured by flow cytometry.

Results

HT29/R and SW480/R cells exhibited higher glucose consumption, lactate production and LDH activity compared to their parental HT29 and SW480 cells. However, oxygen consumption rate (OCR) in HT29/R and SW480/R cells is lower than that in HT29 and SW480 cells, respectively. Results of MTT assays showed that treatment with miR-138 can increase the cytotoxicity of oxaliplatin to HT29/R and SW480/R cells. Research on mechanisms showed that PDK1 was the target of miR-138. Overexpression of miR-138 can inhibit the expression of PDK1, and thus increase the OCR of HT29/R and SW480/R cells. Under the treatment of oxaliplatin, the miR-138-overexpressed HT29/R and SW480/R cells generated more amount of ROS to get into the apoptosis process.

Conclusion

Overexpression of miR-138 suppressed the PDK1 expression to decrease the oxaliplatin resistance of CRC.

Efficient miRNA Inhibitor with GO-PEI Nanosheets for Osteosarcoma Suppression by Targeting PTEN

BACKGROUND

Gene therapy is considered a novel way to treat osteosarcoma, and microRNAs are potential therapeutic targets for osteosarcoma. miR-214 has been found to promote osteosarcoma aggression and metastasis. Graphene oxide (GO) is widely used for gene delivery for the distinct physiochemical properties and minimal cytotoxicity.

METHODS

Polyethyleneimine (PEI)-functionalized GO complex was well-prepared and loaded with miR-214 inhibitor at different concentrations. The load efficacy was tested by gel retardation assay and the cy3-labeled fluorescence of cellular uptake. The experiments of wound healing, immunofluorescence staining, Western blot, qRT-PCR and immunohistochemical staining were performed to measure the inhibitory effect of the miR-214 inhibitor systematically released from the complexes against MG63, U2OS cells and xenograft tumors.

RESULTS

The systematic mechanistic elucidation of the efficient delivery of the miR-214 inhibitor by GO-PEI indicated that the inhibition of cellular miR-214 caused a decrease in osteosarcoma cell invasion and migration and an increase in apoptosis by targeting phosphatase and tensin homolog (PTEN). The synergistic combination of the GO-PEI-miR-214 inhibitor and CDDP chemotherapy showed significant cell death. In a xenograft mouse model, the GO-PEI-miR-214 inhibitor significantly inhibited tumor volume growth.

CONCLUSION

This study indicates the potential of functionalized GO-PEI as a vehicle for miRNA inhibitor delivery to treat osteosarcoma with low toxicity and miR-214 can be a good target for osteosarcoma therapy.

miRNA signatures in childhood sarcomas and their clinical implications

Progresses in multimodal treatments have significantly improved the outcomes for childhood cancer. Nonetheless, for about one-third of patients with Ewing sarcoma, rhabdomyosarcoma, or osteosarcoma steady remission has remained intangible. Thus, new biomarkers to improve early diagnosis and the development of precision-targeted medicine remain imperative. Over the last decade, remarkable progress has been made in the basic understanding of miRNAs function and in interpreting the contribution of their dysregulation to cancer development and progression. On this basis, this review focuses on what has been learned about the pivotal roles of miRNAs in the regulation of key genes implicated in childhood sarcomas.

Downregulation of miRNA-214 inhibits cisplatin resistance, cell migration, and epithelial interstitial transformation in gastric cancer SGC-7901/DDP cells

BACKGROUND

Gastric cancer (GC) is one of the common tumors of the digestive system, and resistance to chemotherapy is the bottleneck that restricts the therapeutic effect of chemotherapy in GC. Therefore, it is of great significance to explore the mechanism of reversal of chemotherapy resistance.

AIM

To investigate the effect of miRNA-214 (miR-214) knockdown on cisplatin resistance, cell migration, and epithelial mesenchymal transformation (EMT) in GC SGC-7901/DDP cells, and to explore the preliminary mechanism.

METHODS

After transfection of SGC-7901/DDP cells with miR-214 inhibitor using the Lipofectamine^TM2000 method, the change of cell resistance to cisplatin was evaluated by the CCK-8 assay, cell migration was evaluated by wound healing assay, and the protein expression levels of E-cadherin (E-cad), Vimentin, N-cadherin (N-cad), NF-κB, and Bcl-2 were detected by Western blot.

RESULTS

After transfection with miR-214 inhibitor, the resistance of SGC-7901/DDP cells to cisplatin was significantly reduced (P < 0.05), and the ability of cell migration was obviously decreased (P < 0.05). The expression level of E-cad protein was significantly increased (P < 0.05), while the expression levels of Vimentin and N-cad proteins were significantly decreased (P < 0.05). Moreover, the expression levels of NF-κB and Bcl-2 protein in SGC-7901/DDP cells were significantly decreased (P < 0.05).

CONCLUSION

Down-regulation of miR-214 can reduce the resistance of SGC-7901/DDP cells to cisplatin and inhibit cell migration and EMT. This effect may be related to the down-regulation of NF-κB and Bcl-2 expression.

Upregulation of miR-214 Induced Radioresistance of Osteosarcoma by Targeting PHLDA2 via PI3K/Akt Signaling

Osteosarcoma is an aggressive bone tumor with high resistance to radiotherapy. Pleckstrin homology-like domain family A member 2 (PHLDA2) displays low expression in human osteosarcoma as a proapoptosis factor. miRNAs have been shown to be important in modulating translation and therapeutic responsiveness in solid tumors. Herein, we used luciferase assay to show that miR-214 downregulates the PHLDA2 expression by targeting its 3′-untranslated region (UTR). A high level of miR-214 was identified in tumor tissues from 30 osteosarcoma patients via qPCR analysis, associated positively with lung metastasis. Ectopic expression miR-214 enhanced radioresistance in osteosarcoma cells, with decreased IR-induced apoptosis. Moreover, the depletion of miR-214 enhanced radiosensitivity in both osteosarcoma cells and mouse xenograft models. Importantly, we showed that miR-214 regulated the activation of phosphatidylinositol-3-kinase/Akt signaling pathway by inhibiting PHLDA2. Finally, the introduction of PHLDA2 cDNA lacking the 3′-UTR or treatment with Akt inhibitor LY294002 partially abrogated miR-214-induced radioresistance. In summary, our results reveal that the upregulation of miR-214 as a frequent event in osteosarcoma contributes to radioresistance by regulating the PHLDA2/Akt pathway. The miR-214/PHLDA2/Akt axis provides a new avenue toward understanding the mechanism of radiosensitivity and may be a potential target for osteosarcoma intervention.

Prognostic significance of circulating microRNA-214 and -126 in dogs with appendicular osteosarcoma receiving amputation and chemotherapy

BACKGROUND

Dogs with appendicular osteosarcoma (OSA) receiving standard amputation and adjuvant chemotherapy demonstrate variable outcome with treatment; however, additional biomarkers would be helpful for predicting their outcome. In the present study, we assessed the potential of circulating microRNA-214 (miR-214) and - 126 (miR-126) to predict time to metastasis and death in dogs with OSA treated with amputation and chemotherapy.

RESULTS

Seventy-six dogs that fully met inclusion criteria were included in the analysis. The criteria included (1) a diagnosis of appendicular OSA without metastases at diagnosis, (2) treatment by amputation and chemotherapy using carboplatin, doxorubicin, cisplatin, or a combination of these agents. Circulating miR-214 and -126 levels at the time before treatment were measured by using RT-qPCR. High circulating miR-214 and serum alkaline phosphatase (ALP) significantly predicted short disease-free survival (DFS) and overall survival (OS). Conversely, high circulating miR-126 significantly predicted prolonged DFS and OS. An integrated approach using circulating miR-214, - 126, and serum ALP showed better accuracy in the prediction of DFS and OS and identification of long-term survivors than prediction using only ALP. Other variables (age, weight, sex, monocyte counts, and primary tumor site) were associated with neither DFS nor OS. miRNA levels did not strongly correlate with histopathological indices.

CONCLUSIONS

Circulating miR-214, - 126, and an integrated prognostic score have strong potential to predict the outcome of canine appendicular OSA patients receiving amputation and chemotherapy.

MicroRNA-504 modulates osteosarcoma cell chemoresistance to cisplatin by targeting p53

Chemoresistance implicates the therapeutic value of cisplatin and remains a primary obstacle to its clinical use. MicroRNAs (miRs) negatively modulate the expression of their target genes and are associated with the occurrence and progression of various types of tumor. The abnormal expression of miR-504 has been reported in certain types of human tumor and has been associated with tumor prognosis. However, the association between miR-504 and cisplatin in human osteosarcoma remains unclear. The present study therefore aimed to assess the in vitro effects and possible mechanism of miR-504 in cell proliferation, apoptosis and cisplatin resistance in MG63 osteosarcoma cells. The results demonstrated that miR-504 was overexpressed in osteosarcoma tissues and cells. This overexpression also induced cell proliferation, as determined by MTT and EdU staining assays. Furthermore, miR-504 suppressed cisplatin-induced apoptosis, which was demonstrated via MTT, cell morphology analysis and flow cytometry. Cisplatin-induced G₁ arrest was also suppressed, which was determined by flow cytometry. The potential target genes of miR-504 were predicted using bioinformatics. p53 was confirmed to be a direct target of miR-504 using a luciferase reporter assay and western blot analysis revealed that miR-504 negatively regulated p53 expression at a molecular level. These results indicate that miR-504 contributes to cisplatin resistance in MG63 osteosarcoma cells by suppressing p53. miR-504 may therefore be a potential biomarker for cisplatin resistance in patients with osteosarcoma.

Exosomal transfer of miR-214 mediates gefitinib resistance in non-small cell lung cancer

Recent studies have demonstrated that exosomal miRNAs mediate as intercellular bio-messengers of drug resistance in lung cancer. Our objective was to investigate whether exosomes derived from gefitinib resistant non-small cell lung cancer cells could confer resistance to its recipient cells. Exosomes were successfully isolated by ultracentrifugation and exosomes morphologies and sizes were determined by transmission electron microscopy and dynamic light scattering analysis. Fluorescent PKH-67 labeled exosomes derived from PC-9GR cells could be taken up and internalized by PC-9 cells. CCK8 measurement showed that PC-9GR-derived exosomes could confer gefitinib resistance in PC-9 cells. MiRNA-214 was upregulated in gefitinib resistant PC-9GR cells and its derived exosomes by qPCR analysis. Inhibition of exosomal miR-214 with antagomir reversed gefitinib resistance conferred by PC-9GR-derived exosomes in vitro, which was confirmed by flow cytometry analysis and westernblot of apoptotic protein (caspase-3, caspase-3 cleaved, bax) and anti-apoptotic protein (bcl-2). Finally, exosomes enriched with miR-214 antagomir was further confirmed to reverse gefitinib resistance in vivo. Our results are the first to show that exosomes derived from gefitinib-resistant PC-9GR cells could transfer resistance to its recipient sensitive PC-9 cells, which might be mediated by exosomal transfer of miR-214.

Screening circular RNA related to chemotherapeutic resistance in osteosarcoma by RNA sequencing

Aim: To identify circular RNAs (circRNAs) related to osteosarcoma (OS) chemoresistance. Materials & methods: CircRNA expression profile was performed in three paired human chemoresistant and chemosensitive OS cell lines by next-generation sequencing. Quantitative real-time-PCR (qRT-PCR) was used to confirm next-generation sequencing data. Bioinformatics analysis was conducted to predict their functions. Results: Eighty circRNAs were dysregulated in the chemoresistant OS cells compared with the control, after validated by qRT-PCR. Bioinformatics analysis showed that some pathways related to drug metabolism were significantly enriched. Additionally, hsa_circ_0004674 was distinctly increased in OS chemoresistant cells and tissues, related to poor prognosis. CircRNA-miRNA-mRNA pathways related to hsa_circ_0004674 were constructed by TargetScan and miRanda. Conclusion: CircRNAs may play a role in OS chemoresistance and hsa_circ_0004674 might be a candidate target.

LncRNA-p23154 promotes the invasion-metastasis potential of oral squamous cell carcinoma by regulating Glut1-mediated glycolysis

The dysregulation of glycolysis has been suggested to lead to alteration of cell drug resistance signals, proliferation and metastasis. Emerging evidence indicates that lncRNAs play a key role in the cellular processes of tumor cells, including glycolysis, growth, and movement. However, the role and potential mechanism of lncRNAs in glycolysis-mediated metastasis has not been explored. In this study, we identified a novel lncRNA lnc-p23154 which is associated with OSCC patient metastasis and the promotion of OSCC cell migration and invasion in vitro and in vivo. Furthermore, we found that lnc-p23154 also participates in OSCC glycolysis by facilitating Glut1 expression. Rescue of lnc-p23154 reversed the suppression of OSCC cell migration and invasion induced by Glut1 knockdown. In addition, lnc-p23154 is mainly located in the nucleus and binds to the promoter region of miR-378a-3p, which represses Glut1 expression by targeting to its 3'UTR directly. Therefore, we concluded that lnc-p23154 may play an important role in Glut1-mediated glycolysis by inhibiting miR-378a-3p transcription and accelerate OSCC metastasis.

Down-regulation of miR-214 inhibits proliferation and glycolysis in non-small-cell lung cancer cells via down-regulating the expression of hexokinase 2 and pyruvate kinase isozyme M2

Glycolysis is a metabolic pathway that is enhanced in cancer cells. miR-214 plays an important role in cancer development and can modulate glycolysis. However, whether miR-214 can regulate glycolysis in non-small-cell lung cancer (NSCLC) cells has not yet been investigated. The expression levels of miR-214 in 7 NSCLC cell lines were measured by qRT-PCR. MTT assay was performed to evaluate the cell proliferation. Glucose consumption and lactate production were measured to assess the level of glycolysis. The expression of hexokinase 2 (HK2) and pyruvate kinase isozyme M2 (PKM2) was measured by qRT-PCR and western blot analysis. Luciferase reporter assay was carried out to confirm the target gene of miR-214. The levels of PTEN, p-Akt, Akt, p-mTOR, mTOR, p-S6K, and S6K were assessed by western blot analysis. Results showed that miR-214 levels were significantly increased in the 7 NSCLC cell lines compared with those in the human bronchial epithelial cell line. Down-regulation of miR-214 inhibited cell proliferation, glucose consumption, lactate production, and expression of HK2 and PKM2 in NSCLC cells. We also confirmed that miR-214 directly targeted PTEN and regulated the PTEN/Akt/mTOR pathway. Inhibition of the PTEN/Akt/mTOR pathway attenuated the effect of miR-214 mimics on glucose consumption, lactate production, and expression of HK2 and PKM2 in NSCLC cells. These results demonstrated that miR-214 down-regulation inhibited cell proliferation and glycolysis by down-regulating the expression of HK2 and PKM2 via the PTEN/Akt/mTOR pathway in NSCLC cells. Hence, our findings suggested that miR-214 might serve as a novel therapeutic target for NSCLC.