MicroRNA‑22 inhibits the proliferation and migration, and increases the cisplatin sensitivity, of osteosarcoma cells

A comprehensive overview of liquid biopsy applications in pediatric solid tumors

Liquid biopsies are emerging as an alternative source for pediatric cancer biomarkers with potential applications during all stages of patient care, from diagnosis to long-term follow-up. While developments within this field are reported, these mainly focus on dedicated items such as a specific liquid biopsy matrix, analyte, and/or single tumor type. To the best of our knowledge, a comprehensive overview is lacking. Here, we review the current state of liquid biopsy research for the most common non-central nervous system pediatric solid tumors. These include neuroblastoma, renal tumors, germ cell tumors, osteosarcoma, Ewing sarcoma, rhabdomyosarcoma and other soft tissue sarcomas, and liver tumors. Within this selection, we discuss the most important or recent studies involving liquid biopsy-based biomarkers, anticipated clinical applications, and the current challenges for success. Furthermore, we provide an overview of liquid biopsy-based biomarker publication output for each tumor type based on a comprehensive literature search between 1989 and 2023. Per study identified, we list the relevant liquid biopsy-based biomarkers, matrices (e.g., peripheral blood, bone marrow, or cerebrospinal fluid), analytes (e.g., circulating cell-free and tumor DNA, microRNAs, and circulating tumor cells), methods (e.g., digital droplet PCR and next-generation sequencing), the involved pediatric patient cohort, and proposed applications. As such, we identified 344 unique publications. Taken together, while the liquid biopsy field in pediatric oncology is still behind adult oncology, potentially relevant publications have increased over the last decade. Importantly, steps towards clinical implementation are rapidly gaining ground, notably through validation of liquid biopsy-based biomarkers in pediatric clinical trials.

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.

Osteosarcoma-enriched transcripts paradoxically generate osteosarcoma-suppressing extracellular proteins

Osteosarcoma (OS) is the common primary bone cancer that affects mostly children and young adults. To augment the standard-of-care chemotherapy, we examined the possibility of protein-based therapy using mesenchymal stem cells (MSCs)-derived proteomes and OS-elevated proteins. While a conditioned medium (CM), collected from MSCs, did not present tumor-suppressing ability, the activation of PKA converted MSCs into induced tumor-suppressing cells (iTSCs). In a mouse model, the direct and hydrogel-assisted administration of CM inhibited tumor-induced bone destruction, and its effect was additive with cisplatin. CM was enriched with proteins such as calreticulin, which acted as an extracellular tumor suppressor by interacting with CD47. Notably, the level of CALR transcripts was elevated in OS tissues, together with other tumor-suppressing proteins, including histone H4, and PCOLCE. PCOLCE acted as an extracellular tumor-suppressing protein by interacting with amyloid precursor protein, a prognostic OS marker with poor survival. The results supported the possibility of employing a paradoxical strategy of utilizing OS transcriptomes for the treatment of OS.

Circulating MicroRNAs as Novel Potential Diagnostic Biomarkers for Osteosarcoma: A Systematic Review

Osteosarcoma (OS) is a fast-progressing bone tumor with high incidence in children and adolescents. The main diagnostic methods for OS are imaging exams and biopsies. In spite of the several resources available for detecting the disease, establishing an early diagnosis is still difficult, resulting in worse prognosis and lower survival rates for patients with OS. The identification of novel biomarkers would be helpful, and recently, circulating microRNAs (miRNAs) have been pointed to as possible non-invasive biomarkers. In order to assess the effectiveness of miRNA research, we performed a systematic review to assess the potential role of circulating miRNAs as biomarkers for OS diagnosis. We performed a search in various databases—PubMed, LILACS (Literatura Latino-americana e do Caribe em Ciências da Saúde), VHL (Virtual Health Library), Elsevier, Web of Science, Gale Academic One File—using the terms: “Circulating microRNAs” OR “plasma microRNAs” OR “serum microRNAs” OR “blood microRNAs” OR “cell-free microRNAs” OR “exosome microRNAs” OR “extracellular vesicles microRNAs” OR “liquid biopsy” AND “osteosarcoma” AND “diagnostic”. We found 35 eligible studies that were independently identified and had had their quality assessed according to Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) guidelines. Despite the useful number of publications on this subject and the fact that several microRNAs showed excellent diagnostic performance for OS, the lack of consistency in results suggests that additional prospective studies are needed to confirm the role of circulating miRNAs as non-invasive biomarkers in OS.

Research Progress of MicroRNA in Chemotherapy Resistance of Osteosarcoma

Osteosarcoma (OS) is a malignant tumor prevalent in adolescents; however, a clinically effective treatment for this malignancy is lacking. The lack of effective treatment methods and factors, such as recurrence and drug resistance, further dampen the prospect of clinically treating OS. In recent years, small molecule microRNAs (miRNAs) with a length of approximately 20-24 nucleotides have gradually attracted the attention of the medical community. Studies have found that miRNAs can regulate the cell cycle, apoptosis, cell proliferation, and cell proliferation. The metabolic response of cancer cells, invasion and metastasis of cancer cells, and angiogenesis play an important role in the process of tumorigenesis. miRNAs regulate gene expression by regulating mRNA expression after transcription. A large amount of data from many studies indicate that they have diagnostic and prognostic biomarker effects in OS and are involved in regulating the metabolism of cancer cells and resistance or sensitivity to chemotherapy drugs. Chemotherapy resistance is one of the most critical problems in clinically treating OS. A large number of basic studies and systematic summaries are required to provide a theoretical basis for elucidating the mechanism and drug development of chemotherapeutic agents. Therefore, this article discusses the role of miRNAs in OS resistance. Herein, the related research progress of the studies is reviewed to provide more useful information for the development of effective therapy.

The therapeutic potential of exosomal miR-22 for cervical cancer radiotherapy

Cervical cancer is the fourth-most prevalent malignancy in women. For advanced cervical cancer, radiotherapy is a major treatment. Micro RNAs (miRNAs) are small, noncoding RNAs that negatively regulate the target gene expression posttranscriptionally. miR-22 is frequently downregulated in various cancers including cervical cancer, and is associated with a poor prognosis in cervical cancer. Exosomes are small endosomally secreted vesicles that carry components such as proteins, messenger RNA (mRNA), DNA and miRNA. We investigated whether or not exosomes can efficiently deliver miR-22 to recipient cervical cancer cells and affect the gene expression in the cells, as well as assessed the role of exosomal miR-22 in radiosensitivity. Exosomes containing high levels of miR-22 were extracted by ultracentrifugation and then characterized by Western blotting, a nanoparticle tracking analysis and electron microscopy. The high presence of miR-22 in the exosome was confirmed by real-time polymerase chain reaction. After the administration of the collected exosomal miR-22 to SKG-II and C4-I cervical cancer cells, the level of miR-22 in the cells was significantly increased, indicating the absorption of the exosomal miR-22. When miR-22 encapsulated in exosomes was administered to the SKG-II cells, the level of c-Myc binding protein (MYCBP) and human telomerase reverse transcriptase (hTERT) was significantly decreased in correlation with increased radiosensitivity determined by a clonogenic assay. Taken together, these results suggest that the administration of exosomal miR-22 may be a novel drug delivery system for cervical cancer radiotherapy.

MiR-455-3p downregulation facilitates cell proliferation and invasion and predicts poor prognosis of osteosarcoma

Background

Osteosarcoma (OS) is one of the most primary malignant bone tumors, mainly attracting children and young adults. The microRNAs are mentioned to play vital roles in many cancers, including OS. The purpose of this study was to explore the expression and function of miR-455-3p in OS and predict the potential effects in clinical diagnosis and prognosis.

Method

We conducted quantitative real-time PCR to assess the expression of miR-455-3p in OS tissues and cell lines. The Cell Counting Kit-8 assay, Transwell assay, and flow cytometry were performed to assess the ability of miR-455-3p on cell proliferation, migration, invasion, and apoptosis. Kaplan–Meier curve and Cox regression analysis were used to demonstrate the survival outcome.

Results

This study revealed that the expression of miR-455-3p was decreased in OS tissues and cell lines. The dysregulation of miR-455-3p was in association with tumor size, distant metastasis, and clinical stage. Patients with high miR-455-3p expression had a satisfying survival rate. Multivariate Cox analysis indicated that miR-455-3p was a promising prognostic indicator. Expression of miR-455-3p could inhibit the proliferation, migration, and invasion, and facilitate apoptosis of OS cells in vitro.

Conclusion

These results indicated the miR-455-3p was a potential clinical therapeutic target and prognostic biomarker by suppressing the proliferation, migration, and invasion, as well as enhancing cell apoptosis.

MicroRNA‑22 regulates autophagy and apoptosis in cisplatin resistance of osteosarcoma

Osteosarcoma (OS) is a primary malignant tumor of bone tissue. Effective chemotherapy may improve the survival of patients with OS. MicroRNAs (miRs) serve significant roles in the regulatory function of tumorigenesis and chemosensitivity of different types of cancer. miR‑22 has been revealed to inhibit the proliferation and migration of OS cells, as well as increasing their sensitivity to cisplatin (CDDP). The mechanisms of action behind the functions of miR‑22 in OS drug resistance require investigation. Therefore, in the present study, the human OS cell lines (MG‑63, U2OS, Saos2 and OS9901) and a drug‑resistant cell line (MG‑63/CDDP) were cultured. Cell proliferation, apoptosis and autophagy assays were performed to investigate the proliferation, apoptosis and autophagy of cell lines transfected with miR‑22 mimic. Reverse transcription‑quantitative polymerase chain reaction and western blot analysis were performed to investigate the expression levels of associated genes. The results revealed that miR‑22 inhibited the proliferation of MG‑63 cells and MG‑63/CDDP cells, and enhanced the anti‑proliferative ability of CDDP. miR‑22 induced apoptosis and inhibited autophagy of MG‑63 cells and MG‑63/CDDP cells. Apoptosis‑related genes, including caspase‑3 and Bcl‑2‑associated X protein were upregulated, while B‑cell lymphoma‑2 was downregulated in both cell lines transfected with the miR‑22 mimic. Autophagy protein 5, beclin1 and microtubules‑associated protein 1 light chain 3 were downregulated in both cell lines transfected with miR‑22 mimic. Furthermore, the in vitro and in vivo expression levels of metadherin (MTDH) in the OS/OS‑CDDP‑resistant models were downregulated following transfection with the miR‑22 mimic. Therefore, the results of the present study suggested that miR‑22 promoted CDDP sensitivity by inhibiting autophagy and inducing apoptosis in OS cells, while MTDH may serve a positive role in inducing CDDP resistance of OS cells.

Investigation of Targeting Relationship between Micro-Rna-22 and Vegfr3 in Lung Squamous Cell Carcinoma

AIM

The present study explored the clinical significance of microRNA-22 (miR-22) expression in lung squamous cell carcinoma and to explore the targeting relationship with vascular endothelial growth factor receptor 3 (VEGFR3).

METHODS

A total of 49 patients with lung squamous cell carcinoma who underwent surgical treatment were selected. The expression of miR-22 was detected by fluorescence quantitative realtime PCR (qPCR), the expression of VEGFR3 was detected by Western blotting assays, and D240 labeled microlymphatic vessels density (MLVD) was detected by immunohistochemistry (IHC). Lung squamous cell carcinoma cell line SK-MES-1 was selected and the targeting relationship between miR-22 and VEGFR3 was analyzed by double luciferase reporter gene assay. Western blotting assays were used to detect the expression of vascular endothelial growth factor-D (VEGFD) and D240 in the blank control group, empty vector transfection group, miR-22 transfection group, miR-22 and VEGFR3 co-transfection group.

RESULTS

The expression range of miR-22 in lung squamous cell carcinoma was 0.8-3.5. The expression of miR-22 in lung squamous cell carcinoma was significantly different by tumor maximum diameter, lymph node metastasis, vascular invasion and TNM stage. The expression of miR-22 was linked to survival time. There was a negative correlation between miR-22 and VEGFR3, miR-22 and MLVD. Double luciferase reporter gene assays showed that miR-22 reduced the luciferase activity of pGL3-VEGFR3-WT transfected cells. Compared with the control group, the expression of VEGF-D and D2-40 in the miR-22 transfection group was significantly decreased. However, VEGF-D and D240 in the miR-22 and VEGFR3 co-transfection group reversed the changes.

CONCLUSION

We assumed that the abnormal expression of miR-22 in lung squamous cell carcinoma may be involved in the development and progression of lung squamous cell carcinoma. MiR-22 negatively regulated the target gene VEGFR3 to mediate lymphangiogenesis. The expression of miR-22 may also be linked to the prognosis of the disease.

miR-22 Suppresses Tumor Invasion and Metastasis in Colorectal Cancer by Targeting NLRP3

Purpose

This study aimed to investigate the effects of microRNA (miR)-22 on biological behaviors of colon cancer cells and to explore the relationship between miR-22 and NLRP3.

Materials and Methods

First, human colon cancer HCT116 cells were transfected with a miR-22 mimic, miR-22 inhibitor, control mimic, and control inhibitor, respectively. CCK8, colony formation, and transwell assays were performed to observe cell proliferation, migration, and invasion. Western blotting was used to analyze the expression of recombinant NLRP3 (NLR family, pyrin domain-containing protein 3) and epithelial–mesenchymal transformation (EMT)-related proteins. The target relationship between miR-22 and NLRP3 was verified by double luciferase report. Second, an NLRP3 inhibitor and NLRP3 mimic were transfected into HCT116 cells, and the biological behaviors and EMT-related proteins were again observed. Finally, a nude mouse xenograft model was constructed to verify the above results.

Results

In vitro, compared with the control group, administration of the miR-22 mimic significantly decreased proliferation, migration, and invasion of HCT116 cells, whereas the miR-22 inhibitor markedly increased their proliferation and invasion (p<0.05). Levels of NLRP3, interleukin-1β (IL-1β), matrix metalloproteinase-9 (MMP-9), MMP-2, N-cadherin, and vimentin were significantly reduced after miR-22 mimic transfection (p<0.05). Furthermore, silencing of NLRP3, a downstream gene of miR-22 in HCT116 cells, suppressed proliferation, migration, and invasion of HCT116 cells. However, overexpression of NLRP3 weakened the effects of the miR-22 mimic. In vivo, overexpression of miR-22 slowed the growth rate of tumors and reduced Ki-67 expression in tumor tissues compared with the model group (p<0.05). In tumor tissues, overexpression of miR-22 also decreased expression of NLRP3, IL-1β, MMP-9, MMP-2, N-cadherin, and vimentin compared with the model group (p<0.05). Overexpression of NLRP3 weakened the role of miR-22 overexpression in vivo.

Conclusion

miR-22 suppresses cell proliferation, migration, and invasion in colorectal cancer by targeting NLRP3.

MicroRNA‑22 mediates the cisplatin resistance of osteosarcoma cells by inhibiting autophagy via the PI3K/Akt/mTOR pathway

Osteosarcoma (OS) is the most common primary malignant tumor of the bone affecting children and adolescents. Chemotherapy is now considered as a standard component of OS treatment, not only for children, but also for adults. However, chemoresistance continues to pose a challenge to therapy. Inhibition of autophagy has been demonstrated to decrease chemoresistance in OS. Moreover, microRNA-22 (miR-22) inhibits autophagy, leading to an improvement in the sensitivity of cisplatin (CDDP) in OS. The aim of the present study was therefore to investigate whether miR-22 could mediate the CDDP resistance of OS cells by inhibiting autophagy via the phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway. Cell proliferation assay, LC3 flow cytometry assay and monodansylcadaverine staining in MG63 cells and CDDP resistance cells (MG63/CDDP) were performed to explore to role of miR-22 and CDDP in OS chemoresistance. Inoculation of tumor cells in an in vivo model, reverse transcription-quantitative PCR (RT-qPCR) assay, western blot analysis, and immunohistochemistry analysis were performed to investigate the role of miR-22 and CDDP in the PI3K/Akt/mTOR pathway as it is affected by autophagy. The results revealed that miR-22 inhibited the proliferation of MG63 and MG63/CDDP cells, and enhanced the anti-proliferative ability of CDDP in vivo and in vitro. miR-22 mediated the CDDP resistance of OS cells by inhibiting autophagy and decreasing CDDP-induced autophagy via downregulation of the expression of PI3K, Akt, and mTOR at the mRNA level, and the expression of PI3K, phosphorylated (p)-Akt, and p-mTOR at the protein level. It was also convincingly demonstrated that miR-22 mediates the CDDP resistance of OS by inhibiting autophagy via the PI3K/Akt/mTOR pathway. Furthermore, in the MG63 cells that were affected by CDDP, the role of miR-22 was shown to be similar to that of the investigated inhibitor of PI3K (wortmannin) in terms of regulating the PI3K/Akt/mTOR pathway, and wortmannin could also promote the effect of miR-22. Interestingly, CDDP was demonstrated to induce autophagy by inhibiting the PI3K/Akt/mTOR pathway, whereas the pathway was upregulated in the state of chemoresistance. In conclusion, downregulation of the PI3K/Akt/mTOR pathway was shown to assist in the process of preventing chemoresistance.

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.

Network vulnerability-based and knowledge-guided identification of microRNA biomarkers indicating platinum resistance in high-grade serous ovarian cancer

Background

High-grade serous ovarian cancer (HGSC), the most common ovarian carcinoma type, is associated with the highest mortality rate among all gynecological malignancies. As chemoresistance has been demonstrated as the major challenge in improving the prognosis of HGSC patients, we here aimed to identify microRNA (miRNA) biomarkers for predicting platinum resistance and further explore their functions in HGSC.

Results

We developed and applied our network vulnerability-based and knowledge-guided bioinformatics model first time for the study of drug-resistance in cancer. Four miRNA biomarkers (miR-454-3p, miR-98-5p, miR-183-5p and miR-22-3p) were identified with potential in stratifying platinum-sensitive and platinum-resistant HGSC patients and predicting prognostic outcome. Among them, miR-454-3p and miR-183-5p were newly discovered to be closely implicated in platinum resistance in HGSC. Functional analyses highlighted crucial roles of the four miRNA biomarkers in platinum resistance through mediating transcriptional regulation, cell proliferation and apoptosis. Moreover, expression patterns of the miRNA biomarkers were validated in both platinum-sensitive and platinum-resistant ovarian cancer cells.

Conclusions

With bioinformatics modeling and analysis, we identified and confirmed four novel putative miRNA biomarkers, miR-454-3p, miR-98-5p, miR-183-5p and miR-22-3p that could serve as indicators of resistance to platinum-based chemotherapy, thereby contributing to the improvement of chemotherapeutic efficiency and optimization of personalized treatments in HGSC.

MiR-19a Promotes Migration And Invasion By Targeting RHOB In Osteosarcoma

Introduction

Osteosarcoma is the most common bone tumor with high metastasis and recurrence rate. MicroRNA-19a (miR-19a) has been reported to act as tumor oncogene in multiple cancers. The objective of the study was to explore the molecular mechanisms of miR-19a in osteosarcoma cell migration and invasion.

Materials and methods

Real-time quantitative polymerase chain reaction (RT-qPCR) and Western blotting were employed to measure the levels of miR-19a and RhoB in osteosarcoma tissues and cell lines. Transwell assay was employed to analyze the tissues and cell lines’ migratory and invasive abilities. Dual luciferase reporter assay was utilized to analyze the association between miR-19a and RhoB.

Results

MiR-19a was overexpressed in osteosarcoma tissues and cell lines. MiR-19a promoted osteosarcoma cell migration and invasion in vitro. RhoB was thus confirmed as a direct and functional target of miR-19a, and it could partially reverse the function of miR-19a. Knockdown miR-19a inhibited osteosarcoma cell epithelial-mesenchymal transition (EMT) and suppressed osteosarcoma xenograft growth.

Conclusion

MiR-19a enhanced cell migration, invasion and EMT through RhoB in osteosarcoma. The newly identified miR-19a/RhoB axis provides novel insight into the progression of osteosarcoma and offers a promising target for osteosarcoma therapy.

miR-361 enhances sensitivity to 5-fluorouracil by targeting the FOXM1-ABCC5/10 signaling pathway in colorectal cancer

Colorectal cancer (CRC) is one of most common malignancies worldwide. 5-fluorouracil (5-FU) is a mainstay of CRC treatment, particularly in patients with advanced stages of the disease; however, 5-FU-based chemotherapy is not always effective and may result in progression of the disease. The present study investigated several candidate microRNAs (miRs) in parental and 5-FU-resistant HCT116 and HT29 cells, and identified miR-361 as a novel regulator of chemosensitivity. Overexpression of miR-361 enhanced the 5-FU susceptibility of parental and resistant HCT116 and HT29 cells in vitro. Impaired colony formation capacity and increased cell apoptosis (as determined via flow cytometry) was observed in resistant HCT116 and HT29 cells. Furthermore, forkhead box M1 (FOXM1) was identified as a target gene of miR-361 using a dual-luciferase reporter assay, western blotting and reverse transcription-quantitative PCR. Additionally, FOXM1 knockdown improved the cytotoxicity of 5-FU in resistant CRC. ATP binding cassette subfamily C members 5 and 10 (ABCC5/10) were found to be downstream effectors of miR-361. In conclusion, miR-361 increased chemosensitivity, at least in part, via modulation of FOXM1-ABCC5/10. miR-361 may serve as a potential therapeutic target for patients with CRC.

Roles of microRNA-22 in Suppressing Proliferation and Promoting Sensitivity of Osteosarcoma Cells via Metadherin-mediated Autophagy

Objective

To analyze the effect of microRNA‐22 on autophagy and proliferation and to investigate the underlying molecular mechanism of osteosarcoma cell chemotherapy sensitivity.

Methods

MG‐63 cells were divided into four groups, including a control group, a negative control (NC) group, a cisplatin group, and a cisplatin + miR‐22 group. Proliferation of MG‐63 cells that had been treated with cisplatin and transfected with miR‐22 mimics was determined using MTT assay and colony formation assay. We assessed the degree of autophagy using flow cytometry through cellular staining of the autophagy lysosomal marker monodansylcadaverine (MDC). The effect of microRNA‐22 on autophagy was observed along with the expression levels of Beclin1, LC3, metadherin (MTDH) and ATG5 by western blot and quantitative reverse transcription polymerase chain reaction (qRT‐PCR). Luciferase reporter assay revealed the targeted binding site between miR‐22 and the 3′‐untranslated region (3′‐UTR) of MTDH mRNA. Western blot and qRT‐PCR were used to explore the level of MTDH in the control group, the NC group, the cisplatin group, and the miR‐22 group for 6, 12, and 24 h.

Results

In the in vitro study, the MTT results indicated that the MG‐63 cells with overexpression of miR‐22 exhibited a significant decline in the proliferation capacity compared with the control group (0.513 ± 0.001, P < 0.0005). Similar to the MTT results, MG‐63 cells that were transfected with miR‐22 mimic (101.0 ± 10.58) formed fewer colonies compared with the cisplatin group (129.7 ± 4.163). MDC staining revealed that miR‐22‐overexpressing osteosarcoma (OS) cells treated with cisplatin showed a significant decrease in the expression of autophagy (7.747 ± 0.117, P < 0.0001). Our data revealed that miR‐22 could regulate not only autophagy but also proliferation in the chemosensitivity of osteosarcoma cells. We found that miR‐22 sensitized osteosarcoma cells to cisplatin treatment by regulating autophagy‐related genes. In addition, Luciferase Reporter Assay revealed that miR‐22 negatively regulated autophagy through direct targeting of MTDH. We performed western blot analysis to detect the MTDH expression level. The results revealed that the overexpression of miR‐22 obviously decreased the expression of MTDH (1.081 ± 0.023, P < 0.001).

Conclusion

Inhibition of miR‐22 ameliorated the anticancer drug‐induced cell proliferation decrease in osteosarcoma cells. MTDH was identified as the miR‐22 target in OS cells and MTDH‐triggered autophagy played a key function in the miR‐22‐associated chemotherapy sensitivity.