GFRA1 promotes cisplatin-induced chemoresistance in osteosarcoma by inducing autophagy

Long noncoding RNA highly upregulated in liver cancer promotes the progression of hepatocellular carcinoma and attenuates the chemosensitivity of oxaliplatin by regulating miR-383-5p/vesicle-associated membrane protein-2 axis

We aimed to explore the function and underlying mechanism of highly upregulated in liver cancer (HULC; an long noncoding RNAs) in hepatocellular carcinoma (HCC) and chemosensitivity of oxaliplatin (Oxa). The expression of HULC, miR-383-5p, and vesicle-associated membrane protein-2 (VAMP2) was detected by quantitative real-time polymerase chain reaction. Western blot assay was applied for measuring the protein expression of cyclinD1, cleaved-caspase-3, light Chain 3 I/II, p62, and VAMP2. Cell viability and Oxa IC50 value were determined by Cell Counting Kit-8 assay. A colony formation assay was conducted to evaluate colony formation ability. Cell apoptosis was assessed by flow cytometry. The interaction between miR-383-5p and HULC or VAMP2 was predicted by bioinformatics analysis and verified by dual-luciferase reporter assay and RNA immunoprecipitation assay. The mice xenograft model was established to investigate the roles of HULC in vivo. HULC and VAMP2 were overexpressed whereas miR-383-5p was lowly expressed in HCC tissues. HULC overexpression promoted the progression of HCC cells and inhibited chemosensitivity of Oxa by increasing cell proliferation and protective autophagy and inhibiting apoptosis, whereas HULC silence presented opposite effects. Moreover, miR-383-5p was a direct target of HULC and miR-383-5p reversed the effects of HULC on the progression of HCC cells and chemosensitivity of Oxa. Besides, HULC acted as a molecular sponge of miR-383-5p to regulate VAMP2 expression. HULC promoted the progression of HCC and inhibited Oxa sensitivity by regulating miR-383-5p/VAMP2 axis, elucidating a novel regulatory mechanism for chemosensitivity of Oxa and providing a potential lncRNA-targeted therapy for HCC.

Knockdown circular RNA circGFRA1 inhibits glioma cell proliferation and migration by upregulating microRNA-99a

Glioma is the most widespread and malignant brain tumor in the central nervous system of adult, causing multiple cancer-associated deaths worldwide. Here, we identified the impact of circGFRA1 on glioma, and aimed to uncover the underlying molecular mechanism. The expression of circGFRA1 of glioma specimens was evaluated by using quantitative reverse transcription PCR. Cell viability, proliferation, colony formation, apoptosis and migration were estimated utilizing CCK-8, EdU staining, colony formation assay, TUNEL staining and Transwell assay, respectively. Bioinformatics analysis, luciferase assay and RNA co-immunoprecipitation was utilized for verification of direct binding between circGFRA1 and miR-99a. Western blot was applied to investigate protein expression in U251 cells. The results showed that circGFRA1 expression was overexpressed in glioma specimens. Knockdown circGFRA1 declined viability, colony formation, proliferation and migrative potential, but enhanced U251 cell apoptosis. Moreover, circGFRA1 acts as a microRNA sponge for miR-99a. Furthermore, miR-99a was involved in the circGFRA1-regulated glioma cell behaviors. Silencing circGFRA1 reduced p/t-AKT, p/t-FOXO1 and p/t-mTOR expression levels via upregulating miR-99a expression. In conclusion, our study demonstrated that knockdown circGFRA1 inhibits glioma cell proliferation and migration by upregulating microRNA-99a.

CXCR4 blockade sensitizes osteosarcoma to doxorubicin by inducing autophagic cell death via PI3K‑Akt‑mTOR pathway inhibition

Doxorubicin is one of the most frequently used chemotherapy drugs in the treatment of osteosarcoma (OS), but the emergence of chemoresistance often leads to treatment failure. C-X-C motif chemokine receptor 4 (CXCR4) has been demonstrated to regulate OS progression and metastasis. However, whether CXCR4 is also involved in OS chemoresistance and its molecular mechanisms has yet to be fully elucidated. In the present study, CXCR4-mediated autophagy for OS chemotherapy was investigated by western blot analysis, transmission electron microscopy and confocal microscopy. CXCR4 silencing enhanced doxorubicin-induced apoptosis by reducing P-glycoprotein in CXCR4⁺ LM8 cells, while CXCR4 overexpression promoted OS doxorubicin resistance in CXCR4⁻Dunn cells. Furthermore, CXCR4 silencing with or without doxorubicin increased the expression of beclin 1 and light chain 3B, and the number of autophagosomes and autolysosomes, as well as induced autophagic flux activation by suppressing the PI3K/AKT/mTOR signaling pathway. In addition, pretreatment with the autophagy inhibitor bafilomycin A1 attenuated CXCR4 abrogation-induced cell death. Finally, the CXCR4 antagonist AMD3100 synergistically reinforced the antitumor effect of doxorubicin in an orthotopic OS mouse model. Taken together, the present study revealed that CXCR4 inhibition sensitizes OS to doxorubicin by inducing autophagic cell death. Therefore, targeting the CXCR4/autophagy axis may be a promising therapeutic strategy to overcome OS chemotherapy resistance.

Development of a Machine Learning-Based Autophagy-Related lncRNA Signature to Improve Prognosis Prediction in Osteosarcoma Patients

Background

Osteosarcoma is a frequent bone malignancy in children and young adults. Despite the availability of some prognostic biomarkers, most of them fail to accurately predict prognosis in osteosarcoma patients. In this study, we used bioinformatics tools and machine learning algorithms to establish an autophagy-related long non-coding RNA (lncRNA) signature to predict the prognosis of osteosarcoma patients.

Methods

We obtained expression and clinical data from osteosarcoma patients in the Therapeutically Applicable Research to Generate Effective Treatments (TARGET) and Gene Expression Omnibus (GEO) databases. We acquired an autophagy gene list from the Human Autophagy Database (HADb) and identified autophagy-related lncRNAs by co-expression analyses. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses of the autophagy-related lncRNAs were conducted. Univariate and multivariate Cox regression analyses were performed to assess the prognostic value of the autophagy-related lncRNA signature and validate the relationship between the signature and osteosarcoma patient survival in an independent cohort. We also investigated the relationship between the signature and immune cell infiltration.

Results

We initially identified 69 autophagy-related lncRNAs, 13 of which were significant predictors of overall survival in osteosarcoma patients. Kaplan-Meier analyses revealed that the 13 autophagy-related lncRNAs could stratify patients based on their outcomes. Receiver operating characteristic curve analyses confirmed the superior prognostic value of the lncRNA signature compared to clinically used prognostic biomarkers. Importantly, the autophagy-related lncRNA signature predicted patient prognosis independently of clinicopathological characteristics. Furthermore, we found that the expression levels of the autophagy-related lncRNA signature were significantly associated with the infiltration levels of different immune cell subsets, including T cells, NK cells, and dendritic cells.

Conclusion

The autophagy-related lncRNA signature established here is an independent and robust predictor of osteosarcoma patient survival. Our findings also suggest that the expression of these 13 autophagy-related lncRNAs may promote osteosarcoma progression by regulating immune cell infiltration in the tumor microenvironment.

[Inhibiting autophagy by silencing ATG5 and ATG7 enhances inhibitory effect of DDP on DDP-resistant I-10 testicular cancer cells]

OBJECTIVE

To observe the changes in autophagy of cisplatin-resistant I-10 testicular cancer cells (I-10/DDP cells) in response to cisplatin treatment and the effect of silencing ATG5 and ATG7 on autophagy and proliferation of cisplatin-treated cells.

OBJECTIVE

I-10/DDP cells treated with 15 μmol/L cisplatin for 12 h were examined for expressions of LC3 and p62 by Western blotting and for autophagy level through transmission electron microscopy and mCherry-GFP-LC3B. I-10/DDP cells were transfected with short hairpin RNAs shRNA-ATG5 or shRNA-ATG7 via Lipfectamine2000, the empty vector (NC group), or Lipfectamine2000 alone (blank control group), and the cellular expressions of ATG5 and ATG7 were detected with Western blotting. The transfected cells were treated with 15 μmol/L cisplatin for 12 h, after that the expressions of LC3 and p62 were detected with Western blotting. Transmission electron microscopy and mCherry-GFP-LC3B were used to detect autophagy level in the cells. MTT assay and colony-forming assay were performed to assess the cell survival fraction and colony formation ability of the treated cells, respectively.

OBJECTIVE

After cisplatin treatmert, the expression level of LC3 II increased significantly (P < 0.001), the expression level of p62 decreased (P < 0.05), and the number of autophagosomes increased in I-10/DDP cells. The cells transfected with shRNA-ATG5 or shRNA-ATG7 showed significantly decreased expressions of ATG5 or ATG7 (P=0.005 or P < 0.001). Cisplatin treatment of the transfected cells obviously reduced the cellular expression of LC3 II (P < 0.001), increased the expression of p62 (P < 0.001), and decreased the number of autophagosomes, cell survival fraction and colony formation ability of the cells (P < 0.001).

OBJECTIVE

Silencing ATG5 and ATG7 inhibits cisplatin-mediated autophagy and enhances the inhibitory effect of cisplatin on inhibiting cell proliferation.

The effects and mechanism of α-mangostin on chemosensitivity of gastric cancer cells

This work investigated the effect of α-mangostin (α-M) on gastric cancer (GC) cell chemoresistance and its underlying mechanisms. Different concentrations of α-M and CDDP were applied to treat GC cells (SGC7901) and CDDP-resistant GC cells (SGC7901/CDDP) for 24 or 48 h. CCK-8 assays were used to measure the inhibitory effect of CDDP or α-M on SGC7901 and SGC7901/CDDP cells as well as the half-maximal inhibitory concentrations (IC50) of α-M for SGC7901 and SGC7901/CDDP cells. The optimal concentration and induction time of CDDP or α-M were determined. SGC7901/CDDP cells were treated with CDDP or/and α-M, where some of them were transfected with pcDNA3.1 or pcDNA3.1-EBI3. Cell proliferation and apoptosis were assessed as well as the levels of EBI3, STAT3, p-STAT3, autophagy-related proteins, and apoptosis-related proteins. CDDP inhibited SGC7901 cell proliferation in a dose-dependent manner. The IC50 of α-M for SGC7901 cells was 12.86 μM and that for SGC7901/CDDP cells was 13.69 μM. The optimal concentrations of CDDP and α-M for SGC7901/CDDP cells were 2 and 15 μM, respectively, and the optimal time was 48 h. The SGC7901/CDDP cells in the CDDP+/α-M+ group had elevated inhibition of proliferation and apoptosis rates. Western blot analysis revealed enhanced levels of LC3-II/I and Beclin1, reduced p62 level, decreased Bcl2 level, and increased levels of Bax and cleaved caspase-3/9. The EBI3/STAT3 pathway was implicated in the effect of α-M on SGC7901/CDDP cell development. α-M increases the chemosensitivity of GC cells by facilitating autophagy and inactivating the EBI3/STAT3 pathway.

Identification of Gene as Predictive Biomarkers for the Occurrence and Recurrence of Osteosarcoma

Purpose

Osteosarcoma is the most common malignant bone cancer affecting adolescents and young adults. This study aimed to screen potential diagnostic and therapeutic markers for osteosarcoma.

Methods

Differential expression analysis between osteosarcoma and control was performed in GSE99671, the differentially expressed genes (DEGs) were subjected to co-expression analysis. Enrichment analysis was employed to identify the biological functions and KEGG signaling pathways of module genes. In addition, a differential analysis was also performed between recurrent and non-recurrent osteosarcoma samples in GSE39055, and enrichment analysis was performed for DEGs. Further, Kaplan–Meier curve analysis was performed on the module genes, and receiver operating characteristic (ROC) curve was drawn. Comparison of the module with the highest correlation to osteosarcoma identified key genes. Cox regression model was utilized to identify the predictive ability of key genes for the prognosis of osteosarcoma.

Results

A total of 13 co-expression modules were identified from 4871 DEGs of GSE99671, module 1 had the highest positive correlation with osteosarcoma. Module genes were mainly enriched in autophagy and macrophage migration functions. A total of 1126 DEGs were obtained from GSE39055, significantly involved in neutrophil mediated immunity. Screening of genes with area under the ROC curve (AUC) values greater than 0.73 in both GSE99671 and GSE39055 identified 5 key genes when compared with genes from module 1. The nomogram results showed that ATF5, CHCHD8, ENOPH1, and LOC286367 might predict 5-year or 8-year survival time of osteosarcoma patients. The Cox model results confirmed that the signals of ATF5, CHCHD8, and LOC286367 were robust, and it may be used in the diagnosis, treatment, and prognosis of osteosarcoma.

Conclusion

We found that ATF5, CHCHD8, and LOC286367 can effectively identify osteosarcoma tumorigenesis and even recurrence status. This is helpful for early diagnosis and treatment, improving the clinical treatment of patients with osteosarcoma.

EF24 induces ferroptosis in osteosarcoma cells through HMOX1

PURPOSE

EF24, a synthetic analogue of curcumin, was developed as an anti-tumor compound to induce apoptosis, inhibit proliferation and metastasis in various cancers. However, whether EF24 induces ferroptosis in osteosarcoma cells or not, and its underlying mechanism remains largely elusive.

METHODS

After EF24 combining with or without other compounds treatments, mRNA expression profiles were proceeded by RNA sequencing. Cytotoxicity was measured by cell counting kit-8 assay. Cell death was quantified by flow cytometer. Gene expression was quantified by real-time PCR. Protein level was detected by western blot. Malonydialdehyde (MDA) level was measured by lipid peroxidation MDA assay kit. Reactive oxygen species (ROS) level was measured by ROS Assay Kit. Ferric ion was measured by Iron Assay kit.

RESULTS

EF24 significantly induced cell death in osteosarcoma cell lines, and this effect was significantly reversed by ferrostatin-1, but not Z-VAD(Ome)-FMK, MRT68921 or necrosulfonamide. EF24 significantly increased MDA level, ROS level and intracellular ferric ion level, these effects were significantly attenuated by ferrostatin-1. EF24 upregulated HMOX1 expression in a dose dependent manner, overexpression of HMOX1 facilitated EF24 to induce ferroptosis in osteosarcoma cell lines. HMOX1 knockdown attenuated EF24-induced cytotoxicity and attenuated EF24-induced inhibition of Glutathione Peroxidase 4 (GPX4) expression.

CONCLUSION

Our results showed that EF24 upregulated HMOX1 to suppress GPX4 expression to induce ferroptosis by increasing MDA level, ROS level and intracellular ferric ion level. Thus, EF24 might serve as a potential agent for the treatment of HMOX1-positive osteosarcoma patients.

Zoledronic Acid Enhanced the Antitumor Effect of Cisplatin on Orthotopic Osteosarcoma by ROS-PI3K/AKT Signaling and Attenuated Osteolysis

Osteoclasts can interact with osteosarcoma to promote the growth of osteosarcoma. Cisplatin is common in adjuvant chemotherapy of osteosarcoma. However, due to chemoresistance, the efficacy is profoundly limited. Previous studies have found that zoledronic acid (ZA) has osteoclast activation inhibition and antitumor effect. However, the combined effect of ZA and cisplatin on osteosarcoma remains unclear. In vitro, the effects of ZA and cisplatin alone or in combination on 143B cell activity, proliferation, apoptosis, and ROS-PI3K/AKT signaling were detected. At the same time, the effect of ZA and cisplatin on osteoclast formation, survival, and activity was detected by TRAP staining and bone plate absorption test. These were further verified in mice. The results showed that in vitro, compared with the single treatment and control, the combination of ZA and cisplatin could significantly inhibit the activity and proliferation of 143B cells and induced their apoptosis and further promoted the generation of ROS and inhibited the phosphorylation of PI3K and AKT. ROS scavenger and the agonist of the PI3K/AKT pathway could reverse these results. In addition, cisplatin in synergy with ZA could significantly inhibit osteoclast formation and survival to reduce bone plate absorption. In vivo, compared with the single group, the tumor volume and cell proliferation were significantly reduced, apoptosis and necrosis of tumor cells increased, and TRAP⁺ osteoclasts and osteolysis destruction decreased in the combined group. In conclusion, ZA enhanced the antitumor effect of cisplatin on osteosarcoma by ROS-PI3K/AKT signaling, reducing the chemoresistance and osteoclast activation to enhance chemotherapy and inhibit osteolysis. And this present study raised the possibility that combining ZA and cisplatin may represent a novel strategy against osteosarcoma.

Girdin Knockdown Increases Gemcitabine Chemosensitivity to Pancreatic Cancer by Modulating Autophagy

Chemotherapy is crucial for the treatment of pancreatic cancer (PC). Gemcitabine (GEM) as the first-line chemotherapy drug has a high resistance rate. Increasing the sensitivity of gemcitabine is currently the objectives and challenges of this study. Our previous study showed Girdin was closely related to the progression and prognosis of PC, indicating that Girdin may be associated with chemosensitivity. In the current study, we use recombinant adenovirus to specifically knockdown Girdin in PC cell lines to determine the effect of Girdin in the process of gemcitabine chemosensitivity. Autophagy is one of the pathways affecting the gemcitabine chemosensitivity in PC. Further research validated that Girdin may activate autophagy by interacting with autophagy protein p62/SQSTM1, which could enhance chemotherapy resistance to gemcitabine in PC. Down-regulation of Girdin may therefore increase gemcitabine chemosensitivity in PC. Our results reveal that Girdin acted as a negative regulator of gemcitabine chemosensitivity in PC. Increased autophagy activity caused by abnormally high Girdin expression may be one of the main factors for the reduction in chemosensitivity, which may provide new perspectives on understanding chemosensitization in PC.

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.

KDM4A-mediated histone demethylation of SLC7A11 inhibits cell ferroptosis in osteosarcoma

Osteosarcoma (OS) is the most common type of bone tumor that seriously affects limb function and induces great pain in patients. Lung metastasis and chemotherapy resistance are two key issues leading to the poor prognosis of OS patients, therefore new treatment targets and strategies are urgently needed. In our study, we uncovered the role of histone demethylase KDM4A in regulating OS cell ferroptosis and tumor progression. KDM4A was significantly upregulated in OS specimens and high KDM4A expression was associated with poorer prognosis in OS patients. Our data indicated that targeting KDM4A significantly increased OS cell death, enhanced cisplatin response, and attenuated migration ability in vitro. KDM4A depletion dramatically inhibited tumor progression and lung metastasis of OS in vivo Further experiments confirmed that KDM4A knockdown promoted OS cell ferroptosis, a special non-apoptotic form of cell death. KDM4A regulates SLC7A11 transcription and OS cell ferroptosis by controlling H3K9me3 demethylation in the promoter region of SLC7A11. Our findings deepened the recognition of epigenetic regulatory mechanism in OS tumorigenesis, chemoresistance, and metastasis, suggesting that KDM4A activity may be a potential therapeutic target for future OS treatment.

High expression of ABCG2 is associated with chemotherapy resistance of osteosarcoma

Objectives

Previous studies showed overexpression of ABCG2 in a variety of tumor tissues, which could potentially indicate the probability of chemotherapy resistance. This study aimed to reveal the role of ABCG2 in the development of chemotherapy resistance and the prognosis of osteosarcoma (OS).

Methods

Sixty-eight OS patients were included in this study. Tumor tissues were collected for each patient during surgery. DOX-resistant OS cell lines were induced by consecutive exposure of gradually increasing concentration of DOX to the parental cell lines. Lentivirus was used for the knockdown of ABCG2 in OS cells. Cells were treated with the gradient concentration of DOX, and the viability was assessed by CCK8 assay. Total RNA was isolated from the tumor tissues or tumor cells, and the expression of ABCG2 was analyzed by qPCR. The relationship between ABCG2 expression and clinicopathological characteristics of the patients was analyzed using Student’s t test or the Chi-square test. The overall survival time was calculated by the Kaplan-Meier method and analyzed by the log-rank test. p < 0.05 was considered statistically significant.

Results

DOX-resistant OS cells were successfully established through continuous exposure to DOX. Forty-eight hours after DOX exposure, the IC 50 value of DOX-resistant HOS cells and DOX-resistant U2OS was 3.5 μM and 3.25 μM, respectively. By contrast, those of the untreated HOS and U2OS cells were 1.15 μM and 0.93 μM, respectively (p < 0.01). The mRNA expression level of ABCG2 was significantly increased in DOX-resistant cell lines. The CCK-8 assay showed that the DOX-resistant HOS cells and DOX-resistant U2OS cells transfected with ShABCG2 were more sensitive to the DOX treatment than those transfected with ShCtrl. Analysis of gene expression in OS tissues showed remarkably higher expression of ABCG2 as compared with adjacent normal tissues (p < 0.01). Patients with high expression level of ABCG2 had obviously decreased overall survival time than the patients with normal expression (p < 0.01).

Conclusions

ABCG2 expression level was significantly associated with the resistance to chemotherapy and the overall survival of OS patients. ABCG2 may be a promising therapeutic target for OS patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13018-021-02204-z.

RASSF1A Enhances Chemosensitivity of NSCLC Cells Through Activating Autophagy by Regulating MAP1S to Inactivate Keap1-Nrf2 Pathway

Objective

Cisplatin (DDP) is an effective first-line therapy for non-small cell lung cancer (NSCLC) treatment; however, it can cause resistance and thus pose an obstacle to the efficacy of chemotherapy in NSCLC. This study aims to detect the effect of RASSF1A on DDP resistance of NSCLC and the underlying mechanism.

Methods

The expression levels of RASSF1A and microtubule-associated protein 1S (MAP1S) were investigated by qRT-PCR and Western blot and their interaction was testified by co-immunoprecipitation (Co-IP) analysis. The IC₅₀ value of DDP on A549 and A549/DDP cells (DDP-resistant cells) was measured. A549/DDP cells were transfected with pCDNA3.1-RASSF1A, pCDNA3.1-MAP1S, or si-RASSF1A, followed by treated with DDP. Cell counting kit-8 (CCK-8) and 5-ethynyl-2'-deoxyuridine (EDU) were employed to measure cell survival rate. Western blot was applied to test the levels of autophagy-associated proteins p62, LC3II, and LC3I. Immunofluorescence staining was used to detect the green fluorescent protein (GFP)-LC3 puncta to evaluate the level of autophagy. Finally, a xenograft model in nude mice using A549/DDP cells was developed.

Results

RASSF1A and MAP1S were lowly expressed and positively correlated in NSCLC tissues. We observed that RASSF1A and MAP1S overexpression significantly enhanced DDP-induced effects in A549 and A549/DDP cells, including decreased cell viability, as well as increased autophagy levels. Besides, investigations into the mechanism between RASSF1A and MAP1S disclosed that RASSF1A could regulate MAP1S to inactivate the Keap1-Nrf2 pathway, thus activating autophagy to enhance chemosensitivity. Moreover, consistent results were confirmed in vivo experiments.

Conclusion

RASSF1A increases chemosensitivity in NSCLC by facilitating autophagy via MAP1S-mediated Keap1-Nrf2 pathway.

CircRNA GFRA1 promotes hepatocellular carcinoma progression by modulating the miR-498/NAP1L3 axis

Circular RNAs (circRNAs) play essential roles in tumorigenesis and tumor progression. CircRNA GFRA1 (circGFRA1) was dysregulated in many cancer samples and acted as an independent marker for prediction of survivals in various cancer patients. However, the functions and molecular mechanisms of circGFRA1 in hepatocellular carcinoma (HCC) remain unclear. We collected 62 HCC tissues and normal adjacent tissues to evaluate the expression of circGFRA1 and the relationship between circGFRA1 expression and HCC patients' survival. We carried out a list of characterization experiments to investigate the roles and underling mechanisms of circGFRA1 and miR-498 in HCC progressions. CircGFRA1 was greatly increased in HCC tissues and cells, and the over-expression of circGFRA1 was intimately related with the advanced clinical stage and poor survival of HCC patients. The expression of circGFRA1 was negatively correlated with the expression of miR-498, but a positive correlation was found between circGFRA1 and NAP1L3 expression in HCC tissues. Silencing circGFRA1 inhibited the growth and invasion of hepatocellular carcinoma. Moreover, miR-498 over-expression or NAP1L3 inhibition could abrogate the oncogene role of circGFRA1 in HCC in vivo. Our findings indicated that circGFRA1 contributed to HCC progression by modulating the miR-498/NAP1L3 axis in HCC.

miR-128-3p serves as an oncogenic microRNA in osteosarcoma cells by downregulating ZC3H12D

Osteosarcoma is the second leading cause of cancer-associated mortality worldwide in children and adolescents. ZC3H12D has been shown to negatively regulate Toll-like receptor signaling and serves as a possible tumor suppressor gene. MicroRNAs (miRNAs/miRs) are known to play an important role in the proliferation of human osteosarcoma cells. However, whether miRNAs can affect tumor development by regulating the expression of ZC3H12D has not yet been investigated. The aim of the present study was to investigate the role of miR128-3p in regulating ZC3H12D expression, as well as its function in tumor cell proliferation, apoptosis, and metastasis. Reverse transcription-quantitative PCR, western blotting and dual luciferase reporter assays were performed to analyze the regulation of ZC3H12D expression by miR-128-3p. MTT, colony formation and flow cytometry assays were also used to analyze the effect of miR-128-3p on cell proliferation and apoptosis. A wound healing assay was performed to investigate the cell migration ability. The results demonstrated that miR-128-3p directly targeted ZC3H12D and downregulated its expression, thereby promoting cell proliferation and migration. miR-128-3p overexpression also improved resistance to cisplatin in MG-63 and 143B cell lines, supporting the hypothesis that miR-128-3p may function as an oncogene in osteosarcoma cells. The potential clinical significance of miR-128-3p as a biomarker and therapeutic target provides rationale for further investigation into the miR-128-3p-mediated molecular pathway and how it is associated with osteosarcoma development.

Cisplatin-resistant osteosarcoma cell-derived exosomes confer cisplatin resistance to recipient cells in an exosomal circ_103801-dependent manner

Studies have shown that exosomes can mediate the chemoresistance of drug-resistant cells by transmitting circular RNAs (circRNAs). However, the role of exosome-derived hsa_circ_103801 (exosomal hsa_circ_103801) in osteosarcoma (OS) remains unclear. The level of hsa_circ_103801 was upregulated in the serum exosomes from patients with OS, and OS patients with high hsa_circRNA_103801 expression had a shorter survival time relative to patients with low hsa_circ_103801 expression. The expression of hsa_circ_103801 was upregulated in cisplatin-resistant MG63 (MG63/CDDP) cells compared with that in MG63 cells. In addition, hsa_circ_103801 was highly enriched in exosomes derived from CDDP-resistant OS cells and could be delivered to MG63 and U2OS cells through exosomes. Exosomes derived from CDDP-resistant cells were shown to reduce the sensitivity of MG63 and U2OS cells to CDDP, inhibit apoptosis, and increase the expression of multidrug resistance-associated protein 1 and P-glycoprotein. Moreover, exosomal hsa_circ_103801 could strengthen the promotive effect of exosomes on the chemoresistance of MG63 and U2OS cells to CDDP. Hence, serum exosomal hsa_circ_103801 may serve as an effective prognostic biomarker for OS, and exosomal hsa_circ_103801 could be a potential target for overcoming OS chemoresistance.

LncRNA SNHG15 contributes to doxorubicin resistance of osteosarcoma cells through targeting the miR-381-3p/GFRA1 axis

Background

Osteosarcoma is a common primary malignant bone cancer. Long noncoding RNA small nucleolar RNA host gene 15 (SNHG15) has been reported to play an oncogenic role in many cancers. Nevertheless, the role of SNHG15 in the doxorubicin (DXR) resistance of osteosarcoma cells has not been fully addressed.

Methods

Cell Counting Kit-8 assay was conducted to measure the half-maximal inhibitory concentration value of DXR in osteosarcoma cells. Western blotting was carried out to examine the levels of autophagy-related proteins and GDNF family receptor alpha-1 (GFRA1). Quantitative reverse transcription-polymerase chain reaction was performed to determine the levels of SNHG15, miR-381-3p, and GFRA1. The proliferation of osteosarcoma cells was measured by MTT assay. The binding sites between miR-381-3p and SNHG15 or GFRA1 were predicted by Starbase bioinformatics software, and the interaction was confirmed by dual-luciferase reporter assay. Murine xenograft model was established to validate the function of SNHG15 in vivo.

Results

Autophagy inhibitor 3-methyladenine sensitized DXR-resistant osteosarcoma cell lines to DXR. SNHG15 was upregulated in DXR-resistant osteosarcoma tissues and cell lines. SNHG15 knockdown inhibited the proliferation, DXR resistance, and autophagy of osteosarcoma cells. MiR-381-3p was a direct target of SNHG15, and GFRA1 bound to miR-381-3p in osteosarcoma cells. SNHG15 contributed to DXR resistance through the miR-381-3p/GFRA1 axis in vitro. SNHG15 depletion contributed to the inhibitory effect of DXR on osteosarcoma tumor growth through the miR-381-3p/GFRA1 axis in vivo.

Conclusions

SNHG15 enhanced the DXR resistance of osteosarcoma cells through elevating the autophagy via targeting the miR-381-3p/GFRA1 axis. Restoration of miR-381-3p expression might be an underlying therapeutic strategy to overcome the DXR resistance of osteosarcoma.

MNAT1 promotes proliferation and the chemo-resistance of osteosarcoma cell to cisplatin through regulating PI3K/Akt/mTOR pathway

Background

MNAT1 (menage a trois 1, MAT1), a cyclin-dependent kinase-activating kinase (CAK) complex, highly expressed in diverse cancers and was involved in cancer molecular pathogenesis. However, its deliverance profile and biological function in osteosarcoma (OS) remain unclear.

Methods

The expression of MNAT1 in OS was detected by western blot (WB) and immunohistochemistry (IHC). The potential relationship between MNAT1 molecular level expression and OS clinical expectations were analyzed according to tissues microarray (TMA). Proliferation potential of OS cells was evaluated in vitro based on CCK8 and OS cells colony formation assays, while OS cells transwell and in situ tissue source wound healing assays were employed to analyze the OS cells invasion and migration ability in vitro. A nude mouse xenograft model was used to detect tumor growth in vivo. In addition, ordinary bioinformatics analysis and experimental correlation verification were performed to investigate the underlying regulation mechanism of OS by MNAT1.

Results

In this research, we found and confirmed that MNAT1 was markedly over-expressed in OS tissue derived in situ, also, highly MNAT1 expression was closely associated with bad clinical expectations. Functional studies had shown that MNAT1 silencing could weaken the invasion, migration and proliferation of OS cells in vitro, and inhibit OS tumor growth in vivo. Mechanism study indicated that MNAT1 contributed to the progression of OS via the PI3K/Akt/mTOR pathway. We further verified that the MNAT1 was required in the regulation of OS chemo-sensitivity to cisplatin (DDP).

Conclusions

Taken together, the data of the present study demonstrate a novel molecular mechanism of MNAT1 involved in the formation of DDP resistance of OS cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-020-07687-3.

Hypomethylation of GDNF family receptor alpha 1 promotes epithelial-mesenchymal transition and predicts metastasis of colorectal cancer

Tumor metastasis is the major cause of poor prognosis and mortality in colorectal cancer (CRC). However, early diagnosis of highly metastatic CRC is currently difficult. In the present study, we screened for a novel biomarker, GDNF family receptor alpha 1 (GFRA1) based on the expression and methylation data in CRC patients from The Cancer Genome Altlas (TCGA), followed by further analysis of the correlation between the GFRA1 expression, methylation, and prognosis of patients. Our results show DNA hypomethylation-mediated upregulation of GFRA1 in invasive CRC, and it was found to be correlated with poor prognosis of CRC patients. Furthermore, GFRA1 methylation-modified sequences were found to have potential as methylation diagnostic markers of highly metastatic CRC. The targeted demethylation of GFRA1 by dCas9-TET1CD and gRNA promoted CRC metastasis in vivo and in vitro. Mechanistically, demethylation of GFRA1 induces epithelial-mesenchymal transition (EMT) by promoting AKT phosphorylation and increasing c-Jun expression in CRC cells. Collectively, our findings indicate that GFRA1 hypomethylation can promote CRC invasion via inducing EMT, and thus, GFRA1 methylation can be used as a biomarker for the early diagnosis of highly metastasis CRC.

Abnormal DNA methylation, one of important characteristics in tumor cells, is exploited as biomarkers for cancer diagnosis and prognosis prediction. Early diagnosis of highly metastatic CRC will be helpful for the clinical management, thus prolongs patient survival. However, it is currently difficult to make early diagnosis of highly metastatic CRC in clinical practice. Currently, we screened a novel biomarker gene, GFRA1, which associated with the invasion and poor prognosis of CRC. The targeted demethylation of GFRA1 exerted a significant promoting effect on CRC metastasis, and GFRA1 methylation-modified sequences are valuable diagnostic biomarker for CRC metastasis risk assessment. Mechanically, demethylation of GFRA1 induced epithelial-mesenchymal transition (EMT) by upregulating AKT phosphorylation and c-Jun expression in CRC cells. Our results demonstrate the promoting effect of GFRA1 demethylation on CRC invasion and GFRA1 methylation may be a potential prognostic marker for predicting metastasis of CRC.

New Insights into Therapy-Induced Progression of Cancer

The malignant tumor is a complex heterogeneous set of cells functioning in a no less heterogeneous microenvironment. Like any dynamic system, cancerous tumors evolve and undergo changes in response to external influences, including therapy. Initially, most tumors are susceptible to treatment. However, remaining cancer cells may rapidly reestablish the tumor after a temporary remission. These new populations of malignant cells usually have increased resistance not only to the first-line agent, but also to the second- and third-line drugs, leading to a significant decrease in patient survival. Multiple studies describe the mechanism of acquired therapy resistance. In past decades, it became clear that, in addition to the simple selection of pre-existing resistant clones, therapy induces a highly complicated and tightly regulated molecular response that allows tumors to adapt to current and even subsequent therapeutic interventions. This review summarizes mechanisms of acquired resistance, such as secondary genetic alterations, impaired function of drug transporters, and autophagy. Moreover, we describe less obvious molecular aspects of therapy resistance in cancers, including epithelial-to-mesenchymal transition, cell cycle alterations, and the role of intercellular communication. Understanding these molecular mechanisms will be beneficial in finding novel therapeutic approaches for cancer therapy.

Non-coding RNAs: the new central dogma of cancer biology

The central dogma of molecular biology states that the functions of RNA revolve around protein translation. Until the last decade, most researches were geared towards characterization of RNAs as intermediaries in protein translation, namely, messenger RNAs (mRNAs) as temporary copies of genetic information, ribosomal RNAs (rRNAs) as a main component of ribosome, or translators of codon sequence (tRNAs). The statistical reality, however, is that these processes account for less than 2% of the genome, and insufficiently explain the functionality of 98% of transcribed RNAs. Recent discoveries have unveiled thousands of unique non-coding RNAs (ncRNAs) and shifted the perception of them from being "junk" transcriptional products to "yet to be elucidated"-and potentially monumentally important-RNAs. Most ncRNAs are now known as key regulators in various networks in which they could lead to specific cellular responses and fates. In major cancers, ncRNAs have been identified as both oncogenic drivers and tumor suppressors, indicating a complex regulatory network among these ncRNAs. Herein, we provide a comprehensive review of the various ncRNAs and their functional roles in cancer, and the pre-clinical and clinical development of ncRNA-based therapeutics. A deeper understanding of ncRNAs could facilitate better design of personalized therapeutics.

Circular RNA hsa_circ_0085131 is involved in cisplatin-resistance of non-small-cell lung cancer cells by regulating autophagy

Non-small-cell lung carcinoma (NSCLC) continues to top the list of cancer mortalities worldwide. The role of circular RNAs (circRNAs) in tumorigenesis has been increasingly appreciated, although it is relatively unexplored in NSCLC. Herein, we reported the role of hsa_circ_0085131 in NSCLC. In the present study, NSCLC tumor specimens exhibited a higher hsa_circ_0085131 level in comparison to para-tumor samples. And the higher level of hsa_circ_0085131 was associated with recurrence and poorer survival of NSCLC. Moreover, hsa_circ_0085131 promoted cell proliferation and cisplatin (DDP)-resistance. Furthermore, hsa_circ_0085131 regulated cell DDP-resistance by modulating autophagy. Hsa_circ_0085131 acted as a competing endogenous RNA of miR-654-5p to release autophagy-associated factor ATG7 expression, thereby promoting cell chemoresistance. In conclusion, hsa_circ_0085131 enhances DDP-resistance of NSCLC cells through sequestering miR-654-5p to upregulate ATG7, leading to cell autophagy. Therefore, these findings advocate targeting the hsa_circ_0085131/miR-654-5p/ATG7 axis as a potential therapeutic option for patients with NSCLC who are resistant to DDP.

Adverse effects of chemoradiotherapy on invasion and metastasis of tumor cells

The phenomenon of enhanced invasion and metastasis of residual tumor cells has been observed in an increasing number of patients receiving chemoradiotherapy recently, and tumor metastasis will undoubtedly limit patient prognosis. However, the key mechanism by which chemoradiotherapy affects the invasion and metastasis of tumor cells remains unclear. Studies have shown that chemoradiotherapy may directly act on tumor cells and alter the tumor microenvironment, or induce cell apoptosis and autophagy to promote tumor cell survival and metastasis. In this review, we summarize the potential mechanisms by which chemoradiotherapy may affect the biological behavior of tumor cells and open up new avenues for reducing tumor recurrence and metastasis after treatment. These insights will improve the efficacy of chemoradiotherapy.

RND2 attenuates apoptosis and autophagy in glioblastoma cells by targeting the p38 MAPK signalling pathway

BACKGROUND

Inhibition of p38 MAPK signalling leads to glioblastoma multiform (GBM) tumourigenesis. Nevertheless, the molecular mechanism that induces p38 MAPK signalling pathway silencing during GBM genesis has yet to be determined. Identifying new factors that can regulate p38 MAPK signalling is important for tumour treatment.

METHODS

Flow cytometry, TUNEL assays, immunofluorescence, JC-1 assays, and western blot analyses were used to detect the apoptosis of GBM cells. The specific methods used to detect autophagy levels in GBM cells were western blot analysis, LC3B protein immunofluorescence, LC3B puncta assays and transmission electron microscopy. The functions of these critical molecules were further confirmed in vivo by intracranial xenografts in nude mice. Tumour tissue samples and clinical information were used to identify the correlation between RND2 and p62 and LC3B expression, survival time of patients, and tumour volumes in clinical patients.

RESULTS

By summarizing data from the TCGA database, we found that expression of the small GTPase RND2 was significantly increased in human glioblastomas. Our study demonstrated that RND2 functions as an endogenous repressor of the p38 MAPK phosphorylation complex. RND2 physically interacted with p38 and decreased p38 phosphorylation, thereby inhibiting p38 MAPK signalling activities. The forced expression of RND2 repressed p38 MAPK signalling, which inhibited glioblastoma cell autophagy and apoptosis in vitro and induced tumour growth in the xenografted mice in vivo. By contrast, the downregulation of RND2 enhanced p38 MAPK signalling activities and promoted glioma cell autophagy and apoptosis. The inhibition of p38 phosphorylation abolished RND2 deficiency-mediated GBM cell autophagy and apoptosis. Most importantly, our study found that RND2 expression was inversely correlated with patient survival time and was positively correlated with tumour size.

CONCLUSIONS

Our findings revealed a new function for RND2 in GBM cell death and offered mechanistic insights into the inhibitory effects of RND2 with regard to the regulation of p38 MAPK activation.

Receptor Tyrosine Kinases in Osteosarcoma Treatment: Which Is the Key Target?

Recent clinical trials have shown several multi-target tyrosine kinase inhibitors (TKIs) to be effective in the treatment of osteosarcoma. However, these TKIs have a number of targets, and it is yet unclear which of these targets has a key role in osteosarcoma treatment. In this review, we first summarize the TKIs that were studied in clinical trials registered on ClinicalTrials.gov. Further, we compare and discuss the targets of these TKIs. We found that TKIs with promising therapeutic effect for osteosarcoma include apatinib, cabozantinib, lenvatinib, regorafenib, and sorafenib. The key targets for osteosarcoma treatment may include VEGFRs and RET. The receptor tyrosine kinases (RTKs) MET, IGF-1R, AXL, PDGFRs, KIT, and FGFRs might be relevant but unimportant targets for osteosarcoma treatment. Inhibition of one type of RTK for the treatment of osteosarcoma is not effective. It is necessary to inhibit several relevant RTKs simultaneously to achieve a breakthrough in osteosarcoma treatment. This review provides comprehensive information on TKI targets relevant in osteosarcoma treatment, and it will be useful for further research in this field.

LncRNA LINC00210 regulated radiosensitivity of osteosarcoma cells via miR-342-3p/GFRA1 axis

BACKGROUND

Radiotherapy is an effective strategy for preventing cancer metastasis, including osteosarcoma. However, cancer radioresistance limits the efficiency of radiotherapy. Therefore, it is essential to investigate the mechanism of osteosarcoma radioresistance.

METHODS

The osteosarcoma tissues and adjacent healthy tissues were collected from 53 osteosarcoma patients. The expression of LINC00210, miR-342-3p, and GFRA1 mRNA were determined using qRT-PCR. Cell viability, cell apoptosis, and cell surviving fraction were determined by MTT assay, flow cytometry, and colony formation assay, respectively. Western blot was performed to detect the protein levels. Luciferase assay was conducted to verify the relationship between LINC00210, miR-342-3p, and GFRA1.

RESULTS

LINC00210 and GFRA1 were up-regulated, and miR-342-3p was down-regulated in osteosarcoma tissues and cells. The expression of LINC00210 in osteosarcoma was negatively related to miR-342-3p expression and positively associated with GFRA1. Besides, there was a negative correlation between LINC00210 and GFRA1 expression in osteosarcoma. Also, LINC00210 and GFRA1 were up-regulated, and miR-342-3p was down-regulated in osteosarcoma cells exposed to 4 Gy irradiation treatment. Furthermore, either LINC00210 knockdown or miR-342-3p overexpression enhanced the radiosensitivity of osteosarcoma cells. Moreover, LINC00210 increased GFRA1 expression via sponging miR-342-3p. Additionally, LINC00210 knockdown improved the radiosensitivity of osteosarcoma cells by regulating GFRA1 expression via sponging miR-342-3p.

CONCLUSION

LINC00210 modulated the radiosensitivity of osteosarcoma cells via the miR-342-3p/GFRA1 axis, making LINC00210 a novel target for improving radiotherapy efficiency in osteosarcoma.

Integrated Genome-Wide Methylation and Expression Analyses Reveal Key Regulators in Osteosarcoma

Osteosarcoma (OS) is one of the most common types of primary bone tumors in early adolescence with unsatisfied prognosis. Aberrant DNA methylation had been demonstrated to be related to tumorigenesis and progression of multiple cancers and could serve as the potential biomarkers for the prognosis of human cancers. In conclusion, this study identified 18 downregulated hypomethylation genes and 52 upregulated hypomethylation genes in OS by integrating the analysis the GSE97529 and GSE42572 datasets. Bioinformatics analysis revealed that OS-specific methylated genes were involved in regulating multiple biological processes, including chemical synaptic transmission, transcription, response to drug, and regulating immune response. KEGG pathway analysis showed that OS-specific methylated genes were associated with the regulation of Hippo, cAMP calcium, MAPK, and Wnt signaling pathways. By analyzing R2 datasets, this study showed that the dysregulation of these OS-specific methylated genes was associated with the metastasis-free survival time in patients with OS, including CBLN4, ANKMY1, BZW1, KRTCAP3, GZMB, KRTDAP, LY9, PFKFB2, PTPN22, and CLDN7. This study provided a better understanding of the molecular mechanisms underlying the progression and OS and novel biomarkers for the prognosis of OS.

RET-independent signaling by GDNF ligands and GFRα receptors

The discovery in the late 1990s of the partnership between the RET receptor tyrosine kinase and the GFRα family of GPI-anchored co-receptors as mediators of the effects of GDNF family ligands galvanized the field of neurotrophic factors, firmly establishing a new molecular framework besides the ubiquitous neurotrophins. Soon after, however, it was realized that many neurons and brain areas expressed GFRα receptors without expressing RET. These observations led to the formulation of two new concepts in GDNF family signaling, namely, the non-cell-autonomous functions of GFRα molecules, so-called trans signaling, as well as cell-autonomous functions mediated by signaling receptors distinct from RET, which became known as RET-independent signaling. To date, the best studied RET-independent signaling pathway for GDNF family ligands involves the neural cell adhesion molecule NCAM and its association with GFRα co-receptors. Among the many functions attributed to this signaling system are neuronal migration, neurite outgrowth, dendrite branching, spine formation, and synaptogenesis. This review summarizes our current understanding of this and other mechanisms of RET-independent signaling by GDNF family ligands and GFRα receptors, as well as their physiological importance.

Sphingosine kinase 1 contributes to doxorubicin resistance and glycolysis in osteosarcoma

Osteosarcoma (OS) is one of the most common and aggressive malignancies in children and adolescents worldwide. Sphingosine kinase 1 (SphK1) has recently been reported to serve a role in OS progression. The present study aimed to investigate the role of SphK1 in the development of chemoresistance and glycolysis in OS cell lines. SphK1 expression levels in OS cell lines (U2OS, MG63 and SaoS2) were analyzed using western blotting and reverse transcription-quantitative PCR (RT-qPCR). A cell survival assay was conducted to determine doxorubicin-resistance in OS cells, and glycolysis was also evaluated. SphK1 expression was increased in the U2OS and SaoS2 cell lines, and both cell lines were more resistant to doxorubicin when compared with the MG63 cell line. SphK1 knockdown or overexpression altered doxorubicin resistance and the viability of OS cell lines. In addition, hypoxia inducible factor-1α (HIF-1α) expression was positively associated with SphK1 expression, and partly mediated SphK1-induced effects on doxorubicin resistance and glycolysis. The present study suggested that SphK1 participated in the development of doxorubicin resistance and contributed to glycolysis in OS cells by regulating HIF-1α expression. However, further studies investigating the application of SphK1 associated therapies for patients with OS are required.

The role of significantly deregulated MicroRNAs in osteosarcoma based on bioinformatic analysis

OBJECTIVE

This study aimed to identify potential key microRNAs (miRNAs) in osteosarcoma and construct miRNA-mRNA negative regulatory networks through analysis of the Gene Expression Omnibus (GEO) database.

METHODS

The differentially expressed miRNAs (DE-miRNAs) in GSE28423 were screened, and their prognostic value was assessed with the prognostic data of GSE39058. The target genes of prognostic DE-miRNAs were predicted and underwent Gene Ontology (GO) classification and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. In addition, the expression of all predicted target genes were assessed using the mRNA array data of GSE28424. Finally, the gene-drug interaction network was constructed.

RESULTS

We identified 205 DE-miRNAs between osteosarcoma cells and normal bone. Among them, high expression of miR-411-3p and miR-487b-5p were correlated with prolonged survival. Furthermore, 2659 genes predicted as targets of miR-411-3p or miR-487b-5p were clustered in 42 significant GO categories, including "regulation of neurotransmitter secretion" and "phosphoprotein binding", as well as 23 significant KEGG pathways, such as "MAPK signaling pathway" and "Ras signaling pathway". Five of the 75 overlapping target genes of miR-411-3p and miR-487b-5p were downregulated in osteosarcoma, including ZBTB20, ADAMTS4, GLIPR2, CLIC5 and CBX7.

CONCLUSIONS

Our findings might help clarify molecular mechanisms underlying the oncogenesis and development, and offer potential targets for osteosarcoma.

Fructose-coated Angstrom silver inhibits osteosarcoma growth and metastasis via promoting ROS-dependent apoptosis through the alteration of glucose metabolism by inhibiting PDK

Osteosarcoma is a common malignant bone cancer easily to metastasize. Much safer and more efficient strategies are still needed to suppress osteosarcoma growth and lung metastasis. We recently presented a pure physical method to fabricate Ångstrom-scale silver particles (AgÅPs) and determined the anti-tumor efficacy of fructose-coated AgÅPs (F-AgÅPs) against lung and pancreatic cancer. Our study utilized an optimized method to obtain smaller F-AgÅPs and aimed to assess whether F-AgÅPs can be used as an efficient and safe agent for osteosarcoma therapy. We also investigated whether the induction of apoptosis by altering glucose metabolic phenotype contributes to the F-AgÅPs-induced anti-osteosarcoma effects. Methods: A modified method was developed to prepare smaller F-AgÅPs. The anti-tumor, anti-metastatic and pro-survival efficacy of F-AgÅPs and their toxicities on healthy tissues were compared with that of cisplatin (a first-line chemotherapeutic drug for osteosarcoma therapy) in subcutaneous or orthotopic osteosarcoma-bearing nude mice. The pharmacokinetics, biodistribution and excretion of F-AgÅPs were evaluated by testing the levels of silver in serum, tissues, urine and feces of mice. A series of assays in vitro were conducted to assess whether the induction of apoptosis mediates the killing effects of F-AgÅPs on osteosarcoma cells and whether the alteration of glucose metabolic phenotype contributes to F-AgÅPs-induced apoptosis. Results: The newly obtained F-AgÅPs (9.38 ± 4.11 nm) had good stability in different biological media or aqueous solutions and were more effective than cisplatin in inhibiting tumor growth, improving survival, attenuating osteolysis and preventing lung metastasis in osteosarcoma-bearing nude mice after intravenous injection, but were well tolerated in normal tissues. One week after injection, about 68% of F-AgÅPs were excreted through feces. F-AgÅPs induced reactive oxygen species (ROS)-dependent apoptosis of osteosarcoma cells but not normal cells, owing to their ability to selectively shift glucose metabolism of osteosarcoma cells from glycolysis to mitochondrial oxidation by inhibiting pyruvate dehydrogenase kinase (PDK). Conclusion: Our study suggests the promising prospect of F-AgÅPs as a powerful selective anticancer agent for osteosarcoma therapy.

Metformin Affects Paclitaxel Sensitivity of Ovarian Cancer Cells Through Autophagy Mediated by Long Noncoding RNASNHG7/miR-3127-5p Axis

Background: Ovarian cancer is the public health issue worldwide. Paclitaxel is a first-line chemotherapy drug for ovarian cancer, but the paclitaxel resistance weakens the therapeutic effect. Metformin (Met) improved the paclitaxel sensitivity in a mouse model of ovarian cancer. However, the mechanism of Met on paclitaxel sensitivity is still unclear in ovarian cancer. Methods: Cell viability, apoptosis, migration, and invasion were measured by Cell Counting Kit-8 (CCK8), flow cytometry, and transwell assays severally. The expression of long noncoding RNA (lncRNA) small nucleolar RNA host gene 7 (SNHG7) and microRNA-3127-5p (miR-3127-5p) were detected by real-time quantitative polymerase chain reaction. The protein levels of poly (ADP-ribose) polymerase, microtubule-associated protein 1 light chain 3 (LC3)-I, LC3-II, and Beclin 1 were examined by western blot assay. RNA immunoprecipitation assay detected the relationship between SNHG7 and miR-3127-5p. Then, the binding correlation between SNHG7 and miR-3127-5p was predicted by starBase and verified by the dual-luciferase reporter. The effects of Met and SNHG7 on tumor growth were tested in ovarian cancer mice model. Results: Met inhibited cell viability, migration, invasion, SNHG7 level, and autophagy and promoted apoptosis in paclitaxel-resistant ovarian cancer cells. Moreover, Met partly reversed SNHG7-mediated paclitaxel sensitivity and autophagy in ovarian cancer cells. SNHG7 directly bound to miR-3127-5p. Met abolished the promoting effect of SNHG7 overexpression on tumor growth and autophagy in vivo. Conclusion: The authors' findings indicated that Met expedited paclitaxel sensitivity by regulating SNHG7/miR-3127-5p-mediated autophagy in ovarian cancer cells.

Long noncoding RNA lncARSR confers resistance to Adriamycin and promotes osteosarcoma progression

One of the significant challenges for chemotherapy is the appearance of resistance to compounds. Although several signaling pathways have been implicated in the development of Adriamycin (ADM) resistance, mechanisms involved in ADM-resistant osteosarcoma progression remain unknown. The present study attempted to illustrate the role of long noncoding RNA ARSR (lncARSR) in the development of adapted ADM resistance. We found lncARSR overexpressed in the Adriamycin-resistant cell lines U2OS/ADM and MG63/ADM, accompanied with acquired multidrug resistance against to paclitaxel and cisplatin. Overexpression of lncARSR triggered rhodamine 123 efflux and survival, as well as the migration of Adriamycin-resistant cells. Inversely, the depletion of lncARSR promoted rhodamine 123 retention and apoptosis, while reducing the motility of ADM-resistant cells. Further investigation revealed that the upregulation of lncARSR enhanced multidrug resistance-associated protein-1 (MRP1), apoptosis inhibitor Survivin, and matrix metalloproteinase-2 (MMP2) through activating AKT. The reduction of lncARSR overcame the resistance to ADM in U2OS/ADM mouse model. The current study gained novel evidence for understanding the mechanisms underlying adaptive ADM resistance and provided rationales to improve clinical outcomes of refractory osteosarcoma.

Circular RNA circTUBGCP3 Is Up-Regulated and Promotes Cell Proliferation, Migration and Survivability via Sponge mir-30b in Osteosarcoma

Purpose

Prevailing evidences have demonstrated that circular RNAs (circRNAs) are closely associated with various stages of carcinogenesis. However, very few studies have delineated the specific mechanism of association between circRNAs and osteosarcoma (OS). It offers a novel insight that circRNAs can be explored as a potential therapeutic strategy for OS.

Materials and Methods

In this study, circTUBGCP3 was chosen from the existing reported circRNA microarray data obtained from OS cell lines and normal bone cells. Subsequently, qRT-PCR was performed to evaluate the expression level of circTUBGCP3 in OS samples and cell lines. Functional assays were conducted to estimate the impact of circTUBGCP3 on human OS cells proliferation, vitality, survivability, and migration. Western blot, luciferase reporter and in vivo tumorigenesis assays were performed to analyze the signaling pathways underlying the interaction of circTUBGCP3, miR-30b, and Vimentin.

Results

The data indicate that circTUBGCP3 may act as a sponge of miR-30b that further alters the expression of Vimentin, and promotes the proliferation and metastatic properties of OS cells.

Conclusion

circTUBGCP3 serves as a tumor promoter in tumorigenesis by increasing the possibilities of OS initiation and proliferation.

The multiple function of long noncoding RNAs in osteosarcoma progression, drug resistance and prognosis

Osteosarcoma is a bone tumor prevalent in children and young adults. LncRNAs are a family of non-protein-coding transcripts longer than 200 nucleotides. The tumor-related pathological functions of lncRNAs include proliferation, migration, and chemotherapy resistance, all of which have been widely acknowledged in research on osteosarcoma. In addition, compelling evidence suggests that lncRNAs could serve as diagnostic indicators, prognostic biomarkers, and targets for disease treatment. In this review, we systematically summarize how lncRNAs regulate tumorigenesis, invasion and therapeutic resistance. By deepening our knowledge of the relationship between lncRNAs and osteosarcoma, we hope to translate research findings into clinical applications as soon as possible.

Plumbagin Enhances the Anticancer Efficacy of Cisplatin by Increasing Intracellular ROS in Human Tongue Squamous Cell Carcinoma

Cisplatin is widely used in the treatment of tongue squamous cell carcinoma (TSCC), but its clinical efficacy is limited by drug resistance and toxic side effects. Hence, a novel compound capable of enhancing the anticancer effect of cisplatin while reducing the side effects is urgently needed. We have previously shown that plumbagin (PLB), an anticancer phytochemical, is able to inhibit the growth of TSCC in vitro and in vivo. The objective of this study was to investigate the effect of PLB in reversing the resistance of TSCC to cisplatin as well as its molecular mechanisms. Here, we found that PLB enhances cisplatin-induced cytotoxicity, apoptosis, and autophagy in CAL27 and cisplatin-resistant CAL27/CDDP cells. PLB could inhibit the viability and growth of TSCC cells by increasing the production of intracellular reactive oxygen species (ROS). In addition, the combination treatment of PLB and cisplatin resulted in a synergistic inhibition of TSCC viability, apoptosis, and autophagy by increasing intracellular ROS, which may be achieved by activating JNK and inhibiting AKT/mTOR signaling pathways. Finally, the synergistic treatment was also demonstrated in vivo. Therefore, PLB combined with cisplatin is a potential therapeutic strategy against therapy TSCC cisplatin resistance.

PTBP1 modulates osteosarcoma chemoresistance to cisplatin by regulating the expression of the copper transporter SLC31A1

Chemoresistance is the main obstacle of treatment in patients with osteosarcoma. RNA‐binding protein PTBP1 has been identified as an oncogene in various cancers. However, the role of PTBP1 in osteosarcoma, especially in chemoresistant osteosarcoma, and the underlying mechanism remain unclear. In this study, we aimed to explore the functions of PTBP1 in chemoresistance of osteosarcoma. We found that PTBP1 was significantly increased in chemotherapeutically insensitive osteosarcoma tissues and cisplatin‐resistant osteosarcoma cell lines (MG‐63_CISR and U‐2OS_CISR) as compared to chemotherapy‐sensitive osteosarcoma tissues and cell lines. Knock‐down of PTBP1 can enhance the anti‐proliferation and apoptosis‐induced effects of cisplatin in MG‐63_CISR and U‐2OS_CISR cells. Moreover, PTBP1 knock‐down significantly up‐regulated the expression of the copper transporter SLC31A1, as indicated by transcriptome sequencing. Through RNA immunoprecipitation, dual‐luciferase reporter assay and RNA stability detection, we confirmed that PTBP1 binds to SLC31A1 mRNA and regulates the expression level of SLC31A1 by affecting mRNA stability. Additionally, SLC31A1 silencing abrogated the chemosensitizing effect of PTBP1 knock‐down in MG‐63_CISR and U‐2OS_CISR cells. Using a nude mouse xenograft model, we further confirmed that PTBP1 knock‐down enhanced chemoresistant osteosarcoma responsiveness to cisplatin treatment in vivo. Collectively, the present study suggests that PTBP1 is a crucial determinant of chemoresistance in osteosarcoma.

The Drug-Resistance Mechanisms of Five Platinum-Based Antitumor Agents

Platinum-based anticancer drugs, including cisplatin, carboplatin, oxaliplatin, nedaplatin, and lobaplatin, are heavily applied in chemotherapy regimens. However, the intrinsic or acquired resistance severely limit the clinical application of platinum-based treatment. The underlying mechanisms are incredibly complicated. Multiple transporters participate in the active transport of platinum-based antitumor agents, and the altered expression level, localization, or activity may severely decrease the cellular platinum accumulation. Detoxification components, which are commonly increasing in resistant tumor cells, can efficiently bind to platinum agents and prevent the formation of platinum–DNA adducts, but the adducts production is the determinant step for the cytotoxicity of platinum-based antitumor agents. Even if adequate adducts have formed, tumor cells still manage to survive through increased DNA repair processes or elevated apoptosis threshold. In addition, autophagy has a profound influence on platinum resistance. This review summarizes the critical participators of platinum resistance mechanisms mentioned above and highlights the most potential therapeutic targets or predicted markers. With a deeper understanding of the underlying resistance mechanisms, new solutions would be produced to extend the clinical application of platinum-based antitumor agents largely.

SIRT1 Mediates Effects of FGF21 to Ameliorate Cisplatin-Induced Acute Kidney Injury

Acute kidney injury (AKI) is a common complication in cancer patients. Kidney function is closely related to patients’ quality of life and tumor prognosis. Cisplatin is a highly effective anti-tumor drug. However, the use of cisplatin is limited by its nephrotoxicity. It has been reported that FGF21 has a renal-protective function, but the mechanisms by which it does so remain unclear. In this study, we show that the expression of FGF21 is significantly upregulated in both in vitro and in vivo cisplatin-induced AKI models. Administration of recombinant FGF21 to cisplatin-induced AKI mice resulted in significantly decreased blood urea nitrogen (BUN) and serum creatinine levels, as well as significantly reduced protein levels of kidney injury molecule-1 (TIM-1), C-caspase 3, and Bax. H&E-stained kidney sections from cisplatin-induced AKI mice treated with recombinant FGF21 showed a relatively normal renal tissue structure, a reduced number of necrotic sites and vacuolar changes, and decreased casts, suggesting alleviated renal tubular injury. Experiments with an AKI cell model (cisplatin-treated HK-2 cells) yielded similar results as the mouse model; recombinant FGF21 significantly downregulated protein expression levels of TIM-1, C-caspase 3, and Bax. Furthermore, administration of recombinant FGF21 to cisplatin-treated AKI models significantly increased SIRT1 expression, and the beneficial effects of FGF21 on kidney injury were reversed by SIRT1 knockdown. Collectively, our results suggest that SIRT1 mediates the protective effect of FGF21 on cisplatin-induced kidney injury.

Downregulation of METTL14 increases apoptosis and autophagy induced by cisplatin in pancreatic cancer cells

Pancreatic cancer is a leading cause of cancer-related death worldwide. Cisplatin is an essential drug treating patients with BRCA1/2 or PALB2 mutations. Whether other genetic determinants of cisplatin sensitivity exist and their underlying mechanisms remain unclear. Immunohistochemistry was used to determine METTL14 expression in pancreatic cancer tissues and non-tumoural tissues. Cell proliferation was detected with CCK-8 assays. Apoptosis was analysed via Western blotting and flow cytometry, and autophagy was analysed via Western blotting and immunofluorescence. In this work, we found higher METTL14 expression in pancreatic cancer tissues than in non-tumoural tissues, and METTL14 expression was associated with pathological characteristics. Downregulation of METTL14 with siRNA sensitized pancreatic cancer cells to cisplatin. Specifically, apoptosis and autophagy were significantly enhanced in METT14 knockdown cells compared with control cells after treatment with cisplatin. Mechanistically, the AMPKα, ERK1/2 and mTOR signalling pathways were disturbed by downregulation of METTL14. We further found that METTL14 knockdown-mediated autophagy was dependent on mTOR signalling and that mTOR activation decreased autophagy to the level observed in the control group. Collectively, our results indicate that METTL14 is upregulated in pancreatic cancer, downregulation of METTL14 sensitizes pancreatic cancer cells to cisplatin by enhancing apoptosis, and autophagy is improved via an mTOR signalling-dependent pathway.

FOXO3/TRIM22 axis abated the antitumor effect of gemcitabine in non-small cell lung cancer via autophagy induction

Background

Non-small cell lung cancer (NSCLC) accounts for more than 80% of the total lung cancer and gemcitabine (GEM)-based chemotherapy is the first-line therapeutic approach for NSCLC treatment. Owing to acquired chemo-resistance, the prognosis of NSCLC patients receiving GEM treatment is still poor.

Methods

Dysregulation of mRNAs in GEM-resistant (GR) NSCLC cells comparing to parental cells were profiled by analyzing GSEA6914 datasets from GEO database. Additionally, qRT-PCR were performed on clinically collected patient serum samples and transplanted tumor tissues and GEM-resistant (GR)/sensitive (GS) cell lines. In order to explore the functional role of tripartite motif protein 22 (TRIM22), gain and loss-of-function cell models were constructed in A549 and A549/GR respectively. MTT and Annexin V-FITC/propidium iodide (PI) staining assay were carried out to access the response to GEM of A549 and A549/GR cells. Observation of RFP-LC3 puncta and western blot detection of autophagy markers were used to evaluate autophagy. Bi-luciferase reporter assay was used to confirm the transcriptional regulatory relationship. Rescue experiments were carried out to confirm the FOXO3/TRIM22 regulatory axis in GEM susceptibility.

Results

TRIM22 was significantly upregulated in GR patient serum samples, transplanted tumor tissues and NSCLC cells which was negatively transcriptional regulated by FOXO3. TRIM22 overexpression attenuated the sensitivity of A549 to GEM and its depletion promoted the sensitivity of A549/GR to GEM. Additionally, TRIM22 promoted GEM-induced pro-survival autophagy to protected NSCLC cells from apoptosis.

Conclusions

TRIM22 was significantly upregulated in GR lung adenocarcinoma cell line A549 which is negatively transcriptional regulated by FOXO3. Due to the enhancement of pro-survival autophagy induced by TRIM22, the A549 cells became less sensitive to GEM. This study may provide a basis for screening target of liquid biopsy for predicting GEM sensitivity in NSCLC.

Insight Into the Role of Autophagy in Osteosarcoma and Its Therapeutic Implication

Osteosarcoma is an aggressive bone cancer that frequently metastasizes to the lungs. The cytotoxicity of most chemotherapeutics and targeted drugs in the treatment of osteosarcoma is partially lessened. Furthermore, there is a poor response to current chemo- and radiotherapy for both primary lesions and pulmonary metastases of osteosarcoma. There is a clear need to explore promising drug candidates that could improve the efficacy of osteosarcoma treatment. Autophagy, a dynamic and highly conserved catabolic process, has dual roles in promoting cell survival as well as cell death. The role of autophagy has been investigated extensively in different tumor types, and a growing body of research has highlighted the potential value of using autophagy in clinical therapy. Here, we address significant aspects of autophagy in osteosarcoma, including its functions, modulation, and possible therapeutic applications.

Molecular Mechanisms Underlying Autophagy-Mediated Treatment Resistance in Cancer

Despite advances in diagnostic tools and therapeutic options, treatment resistance remains a challenge for many cancer patients. Recent studies have found evidence that autophagy, a cellular pathway that delivers cytoplasmic components to lysosomes for degradation and recycling, contributes to treatment resistance in different cancer types. A role for autophagy in resistance to chemotherapies and targeted therapies has been described based largely on associations with various signaling pathways, including MAPK and PI3K/AKT signaling. However, our current understanding of the molecular mechanisms underlying the role of autophagy in facilitating treatment resistance remains limited. Here we provide a comprehensive summary of the evidence linking autophagy to major signaling pathways in the context of treatment resistance and tumor progression, and then highlight recently emerged molecular mechanisms underlying autophagy and the p62/KEAP1/NRF2 and FOXO3A/PUMA axes in chemoresistance.

Targeting autophagy is a promising therapeutic strategy to overcome chemoresistance and reduce metastasis in osteosarcoma

Osteosarcoma (OS) is the most common primary bone malignancy, mainly affecting children and adolescents. Currently, surgical resection combined with adjuvant chemotherapy has been standardized for OS treatment. Despite great advances in chemotherapy for OS, its clinical prognosis remains far from satisfactory; this is due to chemoresistance, which has become a major obstacle to improving OS treatment. Autophagy, a catabolic process through which cells eliminate and recycle their own damaged proteins and organelles to provide energy, can be activated by chemotherapeutic drugs. Accumulating evidence has indicated that autophagy plays the dual role in the regulation of OS chemoresistance by either promoting drug resistance or increasing drug sensitivity. The aim of the present review was to demonstrate thatautophagy has both a cytoprotective and an autophagic cell death function in OS chemoresistance. In addition, methods to detect autophagy, autophagy inducers and inhibitors, as well as autophagy‑mediated metastasis, immunotherapy and clinical prognosis are also discussed.

CircRNAs in cancer metabolism: a review

Altered energy metabolism is a hallmark of tumors aiming at supplying necessary nutrients for tumorigenesis and development. These redirected metabolic pathways associated with carbohydrate, lipid and amino acid are orchestrated not only by carcinogenic proteins but by non-coding RNAs. Among them, circular RNA (circRNA), as a kind of novel identified non-coding RNAs, has become the focus of attention. Through binding with corresponding microRNAs or directly contacting proteins, circRNA plays a primarily important role in regulating cellular metabolism. Herein, we analyze the emerging findings and select circRNAs contributing to mutant glycolysis, lipogenesis and lipolysis, glutam inolysis, and oxidative respiration to deepen the understanding about the cancer metabolic regulatory network. In addition, we also discuss the possibility of circRNAs exerting their functions via exosomes and cancer stem cells. Owing to their unique structures and wide impacts, circRNAs may help reap huge fruits in developing clinical treatments targeting cancer metabolism.

Circular RNAs: epigenetic regulators in cancerous and noncancerous skin diseases

The most frequent kind of malignancy in the universe is skin cancer, which has been categorized into non-melanoma and melanoma skin cancer. There are no complete information of the skin carcinogenesis process. A variety of external and internal agents contribute to the non-melanoma and melanoma skin cancer pathogenesis. These factors are epigenetic changes, X-rays, genetic, arsenic compounds, UV rays, and additional chemical products. It was found that there could be a relationship between the appearing novel and more suitable therapies for participants in this class of diseases and detection of basic molecular paths. A covalently closed loop structure bond connecting the 5' and 3' ends characterizes a new group of extensively expressed endogenous regulatory RNAs, which are called circular RNAs (circRNAs). Mammals commonly express circRNAs. They are of high importance in tumorigenesis. Multiple lines evidence indicated that a variety of circular RNAs are associated with initiation and development of skin-related diseases such as skin cancers. Given that different circular RNAs (hsa_circ_0025039, hsa_circRNA006612, circRNA005537, and circANRIL) via targeting various cellular and molecular targets (e.g., CDK4, DAB2IP, ZEB1, miR-889, and let-7c-3p) exert their effects on skin cancers progression. Herein, for first time, we summarized different circular RNAs in skin cancers and noncancerous diseases. Moreover, we highlighted crosstalk between circular RNAs and ceRNAs in cancerous conditions.