Adriamycin Resistance Research Articles

Expression of GnT-III decreases chemoresistance via negatively regulating P-glycoprotein expression: Involvement of the TNFR2-NF-κB signaling pathway

The phenomenon of multidrug resistance (MDR) is called chemoresistance with respect to the treatment of cancer, and it continues to be a major challenge. The role of N-glycosylation in chemoresistance, however, remains poorly understood. Here, we established a traditional model for adriamycin resistance in K562cells, which are also known as K562/adriamycin-resistant (ADR) cells. Lectin blot, mass spectrometry, and RT-PCR analysis showed that the expression levels of N-acetylglucosaminyltransferase III (GnT-III) mRNA and its products, bisected N-glycans, are significantly decreased in K562/ADR cells, compared with the levels in parent K562cells. By contrast, the expression levels of both P-glycoprotein (P-gp) and its intracellular key regulator, NF-κB signaling, are significantly increased in K562/ADR cells. These upregulations were sufficiently suppressed by the overexpression of GnT-III in K562/ADR cells. We found that the expression of GnT-III consistently decreased chemoresistance for doxorubicin and dasatinib, as well as activation of the NF-κB pathway by tumor necrosis factor (TNF) α, which binds to two structurally distinct glycoproteins, TNF receptor 1 (TNFR1) and TNF receptor 2 (TNFR2), on the cell surface. Interestingly, our immunoprecipitation analysis revealed that only TNFR2, but not TNFR1, contains bisected N-glycans. The lack of GnT-III strongly induced TNFR2's autotrimerization without ligand stimulation, which was rescued by the overexpression of GnT-III in K562/ADR cells. Furthermore, the deficiency of TNFR2 suppressed P-gp expression while it increased GnT-III expression. Taken together, these results clearly show that GnT-III negatively regulates chemoresistance via the suppression of P-gp expression, which is regulated by the TNFR2-NF/κB signaling pathway.

Echinacoside hampers malignant progression of breast cancer MCF-7 cells by modulating AKR1B10/ERK signal transduction

This study analyzes the impact of echinacoside(ECH) in the proliferation, metastasis and adriamycin(ADR) resistance of breast cancer(BC) MCF-7 cells via the modulation of aldo-keto reductase family 1 member 10(AKR1B10)/extracellular signal-regulated kinase(ERK) pathway. The chemical structure of ECH was firstly confirmed. MCF-7 cells were treated with different concentration(0, 10, 20, 40 μg·mL~(-1)) of ECH for 48 h. Western blot was used to analyze expression of AKR1B10/ERK pathway-associated proteins and cell counting kit-8(CCK-8) assay to determine cell viability. MCF-7 cells were collected and classified into control group, ECH group, ECH + Ov-NC group, and ECH + Ov-AKR1B10 group. Then Western blot was employed to analyze the expression of AKR1B10/ERK pathway-associated proteins. CCK-8 and 5-ethynyl-2'-deoxyuridine(EdU) assay were used to examine cell proliferation. Cell migration was appraised with scratch assay, Transwell assay, and Western blot. Eventually, MCF-7 cells were treated with ADR for 48 h to induce ADR resistance. Cell viability was tested by CCK-8 assay and cell apoptosis was estimated based on terminal-deoxynucleoitidyl transferase mediated nick end labeling(TUNEL) assay and Western blot. Based on Protein Data Bank(PDB) and molecular docking, the binding affinity of ECH to AKR1B10 was assessed. Various doses of ECH decreased the expression of AKR1B10/ERK pathway-associated proteins in a dose-dependent manner and declined cell viability compared with the control group. Compared with the control group, 40 μg·mL~(-1) ECH blocked the AKR1B10/ERK pathway in MCF-7 cells and inhibited the proliferation, metastasis and ADR resistance of the cells. Compared with the ECH + Ov-NC group, ECH + Ov-AKR1B10 group showed the recovery of some biological behaviors of MCF-7 cells. ECH also targeted AKR1B10. ECH can inhibit the proliferation, metastasis, and ADR resistance of BC cells by blocking AKR1B10/ERK pathway.

Linc-ROR drive adriamycin resistance by targeting AP-2α/Wnt/β-catenin axis in hepatocellular carcinoma.

Adriamycin is widely used as a chemotherapeutic strategy for advanced hepatocellular carcinoma (HCC). However, the clinical response was disappointing because of the acquired drug resistance with long-term usage. Revealing the underlying mechanism could provide promising therapeutics for the drug-resistant patients. The recently identified linc-ROR (long intergenic non-protein-coding RNA, regulator of reprogramming) has been found to be an oncogene in various cancers, and it also demonstrated to mediate drug resistance and metastasis. We thereby wonder whether this lincRNA could mediate adriamycin chemoresistance in HCC. In this study, linc-ROR was found to be upregulated in adriamycin-resistant HCC cells. And its overexpression accelerated epithelial-mesenchymal transition (EMT) program and adriamycin resistance. Conversely, its silence suppressed EMT and made HCC cells sensitize to adriamycin in vitro and in vivo. Further investigation revealed that linc-ROR physically interacted with AP-2α, mediated its stability by a post-translational modification manner, and sequentially activated Wnt/β-catenin pathway. Furthermore, linc-ROR expression was positively associated with β-catenin expression in human clinical specimens. Taken together, linc-ROR promoted tumorigenesis and adriamycin resistance in HCC via a linc-ROR/AP-2α/Wnt/β-catenin axis, which could be developed as a potential therapeutic target for the adriamycin-resistant patients.

Bim downregulation by activation of NF-κB p65, Akt, and ERK1/2 is associated with adriamycin and dexamethasone resistance in multiple myeloma cells.

Multiple myeloma (MM) frequently acquires multidrug resistance (MDR), which is due to poor prognosis. Our previous study indicated that high expression of Survivin and multidrug resistance protein 1 (MDR1) and decreased expression of Bim are associated with MDR in adriamycin- and dexamethasone-resistant cells. However, the fundamental mechanism of MDR in adriamycin- and dexamethasone-resistant MM cells is still unidentified. In this study, we examined the MDR mechanism in adriamycin- and dexamethasone-resistant cells. RPMI8226/ADM, ARH-77/ADM, RPMI8226/DEX, and ARH-77/DEX cells exhibited enhanced nuclear factor κB (NF-κB) p65, Akt, and extracellular signal-regulated kinase 1/2 (ERK1/2) activation. Combination treatment with NF-κB p65, phosphoinositide 3-kinase (PI3K), and mitogen-activated protein kinase 1/2 (MEK1/2) inhibitors resensitized to adriamycin and dexamethasone via increased Bim expression. Although treatment with MDR1 or Survivin siRNA did not overcome adriamycin and dexamethasone resistance in RPMI8226/ADM and RPMI8226/DEX cells, administration of Bim siRNA induced adriamycin and dexamethasone resistance in RPMI8226 cells. Moreover, low expression of Bim was related to poor prognosis in MM patients. These results indicate that activation of NF-κB p65, Akt, and ERK1/2 is associated with adriamycin and dexamethasone resistance via decreasing Bim expression, and these signal inhibitor combinations overcome drug resistance in MM. These findings suggest that combination treatment with these inhibitors and adriamycin or dexamethasone may be a promising therapy for adriamycin- and dexamethasone-resistant MM.

PLAGL2 increases adriamycin resistance and EMT in breast cancer cells by activating the Wnt pathway.

Adriamycin (ADR) is an effective treatment for breast cancer; nevertheless, it is often linked with acquired resistance in breast cancer cells, reducing ADR's therapeutic efficacy and increasing the risk of recurrence and poor prognosis. It has been revealed that the zinc-finger transcription factor pleomorphic adenoma gene like-2 (PLAGL2) is required for epithelial to mesenchymal transition (EMT) in cancer cells. Recent data indicates that PLAGL2 is also involved in regulating chemotherapeutic drug resistance, albeit the exact mechanism by which this happens remains unknown. This study examines the effect of PLAGL2 on adriamycin resistance and EMT in breast cancer cells. The small interfering RNA (siRNA) targeting PLAGL2 was transfected to breast cancer cells to alter PLAGL2 expression. Cell counting kit-8 (CCK-8) and colony formation assay detected cell growth and proliferation rate. Moreover, wound-healing and transwell assays were conducted to evaluate migration and invasion. Western blot (WB) checked the apoptosis and EMT-associated proteins. PLAGL2 expression is associated with breast cancer cells' acquired resistance to ADR in this investigation. Additionally, deletion of PLAGL2 was associated with enhanced sensitivity to ADR, reduced proliferation, migration, and invasion capabilities, increased E-cadherin levels, and reduced Wnt6, β-catenin, and DVL1 levels in ADR-resistant breast cancer cells (MCF-7/ADR and MDA-MB-231/ADR cells). PLAGL2 could bind to the promoter region of Wnt6 and promote its expression. Additionally, the results of this research established that Wnt signaling is implicated in breast cancer cells' resistance to ADR since BML-284, a Wnt signaling activator partly restored the sensitivity of MCF-7/ADR and MDA-MB-231/ADR cells to ADR. PLAGL2 promotes adriamycin resistance and cell aggressiveness in breast cancer cells via activating the Wnt signaling pathway.

LncRNA DDX11-AS1 Promotes Chemoresistance through LIN28A-Mediated ATG12 mRNA Stabilization in Breast Cancer

Introduction: During breast cancer chemotherapy, the chemoresistance that frequently accompanies the treatment has become a big challenge. Long noncoding RNAs (LncRNAs) have been related to the development of chemoresistance in multiple cancer types. LncRNA DDX11-AS1 has shown a carcinogenic role in lung and colorectal cancer and was reported to enhance oxaliplatin resistance in gastric cancer and Taxol insensitivity in esophageal cancer. But its role in breast cancer chemotherapy drug resistance remains unknown. This study aimed to investigate the function and mechanism of lncRNA DDX11-AS1 in breast cancer chemoresistance. Methods: The relationship between DDX11-AS1 and adriamycin (ADR) resistance was confirmed by qPCR, cell viability tests, and survival analysis. Then, RNA immunoprecipitation was conducted to evaluate the interaction between DDX11-AS1 and RNA-binding protein LIN28A. The regulation effect of LIN28A on autophagy-related genes ATG7 or ATG12 was detected by RNA stability assay and Western blot. Their correlation analysis was evaluated in GEO datasets and further validated by immunohistochemical results. The clinical significance of DDX11-AS1, ATG7, or ATG12 was evaluated by Kaplan-Meier Plotter analysis. Results: Here, we reported DDX11-AS1 was significantly upregulated in chemoresistant breast cancer cells and overexpression of DDX11-AS1 promoted ADR resistance in breast cancer. LIN28A could interact with DDX11-AS1 and was involved in DDX11-AS1-mediated ADR resistance. Interfering with LIN28A reversed DDX11-AS1-induced ADR resistance. LIN28A could increase the protein level of ATG7 and ATG12 by increasing their mRNA stability. Survival analysis showed that ATG12 expression level was negatively correlated with the prognosis of breast cancer patients. Conclusion: This study clarifies the role of DDX11-AS1 in breast cancer chemoresistance and revealed a new mechanism, that is, interacting with LIN28A to stabilize ATG7 and ATG12 and jointly promote chemorefractory. These findings warrant further in vivo investigations to study DDX11-AS1 as a potential target to overcome chemoresistance.

Circ_0001667 Promotes Adriamycin Resistance and Malignant Progression via Targeting the miR-193a-5p/Rap2A Molecular Axis in Breast Cancer

BackgroundThe therapeutic effect of adriamycin (ADM) has been limited by chemoresistance in breast cancer (BC). Circular RNAs are involved in resistance regulation by mediating the miRNA/mRNA axis. Circ_0001667 enhanced ADM resistance via the miR-4458/NCOA3 axis in BC. This study was to investigate the other miRNA/mRNA network for circ_0001667. MethodsThe level detection of circ_0001667, microRNA-193a-5p (miR-193a-5p) or Ras-Related Protein 2a (Rap2A) was conducted by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Half inhibitory concentration (IC50) of ADM was detected through cell counting kit-8 (CCK-8) assay. The proliferation analysis was performed by colony formation assay and EdU assay. Flow cytometry was used for assessing apoptosis. Transwell assay was applied for examining cell migration and invasion. The protein detection was carried out by western blot. In vivo assay was performed using xenograft tumor model. Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were implemented to validate the target interaction. ResultsCirc_0001667 was highly expressed in ADM-resistant BC tissues and cells. Downregulation of circ_0001667 reduced ADM resistance and inhibited proliferation, migration, invasion in ADM-resistant BC cells. Tumor growth was repressed by circ_0001667 knockdown in ADM-resistant xenograft model. Circ_0001667 has induced the sponge effect on miR-193a-5p. The circ_0001667 function was partly achieved by targeting miR-193a-5p. Rap2A expression was positively regulated by circ_0001667 through sponging miR-193a-5p. The miR-193a-5p upregulation restrained chemoresistance and BC progression by the downregulation of Rap2A. ConclusionAll results unraveled that circ_0001667 contributed to ADM resistance and tumor development in BC via the miR-193a-5p-mediated Rap2A expression change, providing a novel regulatory mechanism for circ_0001667.

Novel Sigma-2 receptor ligand A011 overcomes MDR in adriamycin-resistant human breast cancer cells by modulating ABCB1 and ABCG2 transporter function.

Multidrug resistance (MDR) is thought to be one of the main reasons for the failure of chemotherapy in cancers. ATP-binding cassette subfamily B member 1 (ABCB1) or P-glycoprotein (P-gp) and ATP-binding cassette subfamily G member 2 (ABCG2) play indispensable roles in cancer cell MDR. Sigma-2 (σ2) receptor is considered to be a cancer biomarker and a potential therapeutic target due to its high expression in various proliferative tumors. Recently, σ2 receptor ligands have been shown to have promising cytotoxic effects against cancer cells and to modulate the activity of P-glycoprotein (ABCB1) in vitro experiments, but their specific effects and mechanisms remain to be elucidated. We found that A011, a σ2 receptor ligand with the structure of 6,7-dimethoxy-1,2,3,4-tetrahydroisoquinoline, showed promising cytotoxicity against breast cancer MCF-7 and adriamycin-resistant MCF-7 (MCF-7/ADR), induced apoptosis, and reversed adriamycin (ADR) and paclitaxel resistance in MCF-7/ADR cells. Furthermore, we demonstrated that A011 increased the accumulation of rhodamine 123 and mitoxantrone in MCF-7/ADR cells. A011 significantly decreased the ATPase activity of the ABCB1 and down-regulated ABCG2 protein expression. In addition, A011, administered alone or in combination with ADR, significantly inhibited tumor growth in the MCF-7/ADR tumor-bearing nude mouse model. A011 may be a potential therapeutic agent for the treatment of tumor resistance.

HDAC2- and EZH2-Mediated Histone Modifications Induce PDK1 Expression through miR-148a Downregulation in Breast Cancer Progression and Adriamycin Resistance.

Simple SummaryEpigenetic modification plays an important regulatory role in breast cancer progression. However, the relationship between epigenetic modification with tumor metabolism has not yet been fully elucidated. PDK1, as a key enzyme in glucose metabolism, mediates multiple tumors development. But, the mechanism of epigenetic modification in regulating PDK1 remains unclear in breast cancer. Here, we demonstrated that HDAC2 and EZH2 upregulated PDK1 expression through inhibiting miR-148a. Importantly, miR-148a targeting PDK1 regulated breast cancer cells glycolysis, invasion, epithelial-mesenchymal transition (EMT) and Adriamycin resistance. Our results suggested that the HDAC2/EZH2/miR-148a/PDK1 axis may be a promising potential therapeutic strategy.Background: Breast cancer has one of highest morbidity and mortality rates for women. Abnormalities regarding epigenetics modification and pyruvate dehydrogenase kinase 1 (PDK1)-induced unusual metabolism contribute to breast cancer progression and chemotherapy resistance. However, the role and mechanism of epigenetic change in regulating PDK1 in breast cancer remains to be elucidated. Methods: Gene set enrichment analysis (GSEA) and Pearson’s correlation analysis were performed to analyze the relationship between histone deacetylase 2 (HDAC2), enhancer of zeste homologue 2 (EZH2), and PDK1 in database and human breast cancer tissues. Dual luciferase reporters were used to test the regulation between PDK1 and miR-148a. HDAC2 and EZH2 were found to regulate miR-148a expression through Western blotting assays, qRT-PCR and co-immunoprecipitation assays. The effects of PDK1 and miR-148a in breast cancer were investigated by immunofluorescence (IF) assay, Transwell assay and flow cytometry assay. The roles of miR-148a/PDK1 in tumor growth were investigated in vivo. Results: We found that PDK1 expression was upregulated by epigenetic alterations mediated by HDAC2 and EZH2. At the post-transcriptional level, PDK1 was a new direct target of miR-148a and was upregulated in breast cancer cells due to miR-148a suppression. PDK1 overexpression partly reversed the biological function of miR-148a—including miR-148a’s ability to increase cell sensitivity to Adriamycin (ADR) treatment—inhibiting cell glycolysis, invasion and epithelial–mesenchymal transition (EMT), and inducing apoptosis and repressing tumor growth. Furthermore, we identified a novel mechanism: DNMT1 directly bound to EZH2 and recruited EZH2 and HDAC2 complexes to the promoter region of miR-148a, leading to miR-148a downregulation. In breast cancer tissues, HDAC2 and EZH2 protein expression levels also were inversely correlated with levels of miR-148a expression. Conclusion: Our study found a new regulatory mechanism in which EZH2 and HDAC2 mediate PDK1 upregulation by silencing miR-148a expression to regulate cancer development and Adriamycin resistance. These new findings suggest that the HDAC2/EZH2/miR-148a/PDK1 axis is a novel mechanism for regulating cancer development and is a potentially promising target for therapeutic options in the future.

Circ_0002113 facilitates adriamycin resistance and malignant development of breast cancer by completely binding to miR-653-5p to induce upregulation of SPIN1

Circ_0002113 facilitates adriamycin resistance and malignant development of breast cancer by completely binding to miR-653-5p to induce upregulation of SPIN1

Tanshinone IIA attenuates the stemness of breast cancer cells via targeting the miR-125b/STARD13 axis

BackgroundTanshinone II A is an effective component extracted from Salvia miltiorrhiza and the roles of Tanshinone IIA in regulating the stemness of tumor cells remain unclear. This work aims to explore the roles and underlying mechanisms of Tanshinone IIA in breast cancer stemness.MethodsIn vitro mammary spheroid formation, flow cytometry assay on CD24−/CD44+ sub-population, ALDH activity detection, cell viability assay and western blot analysis, and in vivo tumor-initiating analysis were performed to examine the effects of Tanshinone IIA on the stemness of breast cancer cells. MiRNAs-based transcriptome sequencing and data analysis, online dataset analysis, luciferase reporter assay combined with rescuing experiments were constructed to explore the underlying mechanisms.ResultsTanshinone IIA attenuated the stemness of breast cancer cells, evident by downregulating the expression of stemness markers, hindering the capacity of spheroid formation, decreasing the CD24−/CD44+ sub-population in a concentration-dependent manner and reducing the tumor-initiating ability of breast cancer cells. Additionally, Tanshinone IIA enhanced adriamycin sensitivity and attenuated adriamycin resistance of breast cancer cells. Combined with miRNAs-based transcriptome sequencing assay, it was found that Tanshinone IIA downregulated miR-125b level and upregulated its target gene STARD13 (StAR-related lipid transfer protein 13) level, thus inactivating the miR-125b/STARD13 axis, which had been previously confirmed to promote breast cancer progression. Notably, miR-125b overexpression enhanced the stemness of breast cancer cells, and miR-125b overexpression or STARD13 knockdown impaired the inhibitory effects of Tanshinone IIA on the stemness of breast cancer cells.ConclusionsTanshinone IIA could attenuate the stemness of breast cancer cells via targeting the miR-125b/STARD13 axis.

D Rhamnose β-Hederin Reverses NAP1l5-Mediated Adriamycin Resistance in Breast Cancer

The persistent use of anticancer medicines can cause multidrug resistance in many tumors and serious cytotoxicity for healthy cells, including adriamycin (ADR), a treatment for breast cancer (BC). Cell resistance to ADR in patients with recurrent advanced BC can occur. Creating effective treatments that can grapple with multidrug resistance is still challenging. Traditional Chinese medicine (TCM) may offer a solution in D Rhamnose beta-hederin (DRβ-H), an oleanane type of triterpenoid saponin.The study intended to assess the ability of DRβ-H to inhibit the ADR resistance of two BC-lineage cell lines, MCF-7 and SUM-1315, and to explore the causal link between DRβ-H and the reversal of chemoresistance.The research team performed a cell biology study.The study took place at laboratory in China.The research team: (1) assessed cell viability and the migration and invasion the cell lines; (2) investigated the molecular mechanism and identified the downstream targets of DRβ-H, and (3) comprehensively examined the expression pattern, underlying functions, and evident prognostic significance of NAP1L5 in BC by gathering the online information available.DRβ-H can inhibit the viability of the MCF-7/ADR and SUM-1315/ADR cancer cells in a dosage-dependent manner. NAP1L5 might be the main target of DRβ-H in reversing ADR resistance. Its expression decreased in BC cells, and the more advanced the BC was, the lower the NAP1L5 expression was.DRβ-H at nontoxic concentrations was related to ADR resistance in BC through its downstream target NAP1L5. NAP1L5 is potentially a preferable prognostic marker for BC.

Retraction: Exosomal MicroRNA-221-3p Confers Adriamycin Resistance in Breast Cancer Cells by Targeting PIK3R1.

[This retracts the article DOI: 10.3389/fonc.2020.00441.].

Effect of m6A methyltransferase METTL3 -mediated MALAT1/E2F1/AGR2 axis on adriamycin resistance in breast cancer.

N6-methyladenosine (m6A) methyltransferase METTL3 has been implicated in carcinogenesis, which may be associated the overexpression of MALAT1. However, the downstream mechanics actions remain largely unknown. This study intends to probe the downstream mechanism of the N6-methyladenosine (m6 A) methyltransferase METTL3 and MALAT1 in adriamycin resistance in breast cancer. Through Bioinformatics databases lncMAP, TCGA and GTEx, we predicted the downstream transcription factors E2F1 and AGR2 of MALAT1 in breast cancer. The Cancer Genome Atlas and Genotype-Tissue Expression (GTEx) databases were used to screen the downstream target genes of MALAT1. MeRIP-qPCR was used to detect the m6 A level of MALAT1 in cells. RIP was used to detect the binding between MALAT1 and E2F1, and chromatin immunoprecipitation (ChIP) for the binding of E2F1 to AGR2 promoter. Cell Counting Kit-8 and colony formation assays were used to detect cell viability. Transwell was used to detect cell invasion. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) and western blot were used to detect the expression of related genes and proteins. A nude mouse xenograft tumor model was established to observe the effect of METTL3 on adriamycin resistance of breast cancer. The total survival of mice after exogenous gene silencing was analyzed by the Kaplan-Meier method. METTL3 was highly expressed in adriamycin-resistant breast cancer cells. METTL3 promotes adriamycin resistance in breast cancer cells. METTL3 mediates the expression of MALAT1 in adriamycin-resistant breast cancer through m6 A. MALAT1 increases adriamycin resistance in breast cancer cells by recruiting E2F1 to activate AGR2 transcription. METTL3 can regulate the expression of MALAT1 through m6 A, mediate the E2F1/AGR2 axis, and promote the adriamycin resistance of breast cancer. METTL3 may modify MALAT1 protein through m6 A, recruit E2F1 and activate downstream AGR2 expression, thus promoting adriamycin resistance in breast cancer.

CircRNA_0044556 diminishes the sensitivity of triple‑negative breast cancer cells to adriamycin by sponging miR‑145 and regulating NRAS.

CircRNAs are associated with adriamycin (ADM) resistance in triple-negative breast cancer (TNBC), but the mechanism is unknown. Reverse transcription-quantitative PCR was applied to quantify circular RNA (circRNA)_0044556, microRNA (miR)-145 and NRAS proto-oncogene, GTPase (NRAS) in TNBC tissues and cells with or without ADM treatment. Following ADM treatment, the effects of circRNA_0044556 on the viability, ADM resistance, apoptosis and migration of TNBC cells were investigated by cell function experiments (Cell Counting Kit-8, flow cytometry and Transwell assays). The targeting relationship between circRNA_0044556 and miR-145 was investigated via bioinformatics analysis, dual-luciferase reporter assay and RNA immunoprecipitation. The effects of the circRNA_0044556/miR-145 axis on the TNBC cells were revealed by rescue experiments. Correlations among circRNA_0044556, miR-145 and NRAS were analyzed by Pearson's correlation test. CircRNA_0044556 was highly expressed in TNBC tissues and cells with or without ADM-resistance. The overexpression of circRNA_0044556 promoted cell viability, ADM-resistance and migration, while inhibiting the apoptosis by sponging miR-145. Upregulation of miR-145 reversed the effects of circRNA_0044556 on the TNBC cells. CircRNA_0044556 was negatively correlated with miR-145 yet positively correlated with NRAS, the target gene of miR-145, in addition to the discovery suggesting the negative regulatory effects of circRNA_0044556 on miR-145. CircRNA_0044556 diminished the sensitivity of TNBC cells to ADM via the miR-145/NRAS axis.

N6-methyladenosine (m6A)-mediated lncRNA DLGAP1-AS1enhances breast canceradriamycin resistance through miR-299-3p/WTAP feedback loop

ABSTRACT Chemotherapy resistance is identified as an obstacle for breast cancer (BC) therapy, and, besides, increasing evidence indicates that long-noncoding RNAs (lncRNAs) participate in the regulation of BC adriamycin (ADR) resistance. Here, our work shows that lncRNA DLGAP1 antisense RNA 1 (DLGAP1-AS1) is up-regulated in ADR-resistant BC cells (MCF-7/ADR). Clinically, higher DLGAP1-AS1 expression was closely correlated to poorer clinical prognosis. Results showed that DLGAP1-AS1 promoted the ADR IC50 and proliferation of ADR-resistant cells. Moreover, N6-methyladenosine (m6A) methyltransferase WT1 associated protein (WTAP) binds to the m6A modified site of DLGAP1-AS1 and motivates its stability. Mechanistically, DLGAP1-AS1 sponged miR-299-3p through 3ʹ-untranslated region (3ʹ-UTR) binding, which in turn relieved the repression of WTAP and thus upregulated WTAP expression. In conclusion, above findings conclude that lncRNA DLGAP1-AS1 promotes BC ADR-resistance through WTAP/DLGAP1-AS1/miR-299-3p feedback loop.

RBM38 is negatively regulated by miR-320b and enhances Adriamycin resistance in breast cancer cells.

Breast cancer (BC) is a common type of malignant tumor that is frequently accompanied by drug resistance, which is a significant challenge in the treatment of BC. Adriamycin (ADM) is a commonly used drug for the treatment of BC. The aim of the present study was to demonstrate the association between RNA binding motif protein 38 (RBM38) and ADM resistance in BC. The results revealed that the expression levels of RBM38 were significantly upregulated in ADM-resistant BC tissues and the ADM-resistant cell line, MCF-7/A, as demonstrated using reverse transcription-quantitative PCR and western blotting. In addition, the results of the MTT assay revealed that the overexpression of RBM38 enhanced the resistance of MCF-7/A cells to ADM, promoted invasiveness, as determined using a Transwell assay, inhibited the apoptosis of resistant cells, as determined using flow cytometry, and accelerated cell cycle progression from the G0 to the S phase. The results of the dual luciferase reporter assay demonstrated the binding relationship between microRNA (miR)-320b and RBM38, and the expression levels of miR-320b were significantly downregulated in ADM-resistant BC tissues and MCF-7/A cells. Overexpression of miR-320b reversed ADM resistance, suppressed invasiveness, promoted apoptosis and arrested MCF-7/A cells in the G0 phase. In addition, RBM38 was discovered to be negatively regulated by miR-320b, which was able to restore the sensitivity of BC cells to ADM by downregulating RBM38. Further exploration of the underlying regulatory mechanism revealed that the miR-320b/RBM38 signaling axis mediated the development of ADM resistance in BC by altering the expression of cell cycle-, drug resistance- and PI3K/AKT signaling pathway-related proteins. In conclusion, the results of the present study suggested that RBM38 may be negatively regulated by miR-320b, which accelerates drug resistance in BC.

Ad-Apoptin-hTERTp-E1a Regulates Autophagy Through the AMPK-mTOR-eIF4F Signaling Axis to Reduce Drug Resistance of MCF-7/ADR Cells.

Ad-VT (Ad-Apoptin-hTERTp-E1a) is a type of oncolytic adenovirus with dual specific tumor cell death ability. It can effectively induce cell death of breast cancer cells and has better effect when used in combination with chemotherapy drugs. However, it has not been reported whether Ad-VT reduces the resistance of breast cancer cells to chemotherapy drugs. The purpose of this study is to investigate the effect of Ad-VT on drug resistance of Adriamycin-resistant breast cancer cells. For this, the effects of different doses of Ad-VT on the resistance of breast cancer cells to Adriamycin were analyzed using qualitative and quantitative experiments in vitro and in vivo. The Ad-VT can reduce the resistance of MCF-7/ADR to adriamycin, which is caused by the reduction of MRP1 protein level in MCF-7/ADR cells after treatment with Ad-VT, and MRP1 can be interfered with by autophagy inhibitors. Subsequently, the upstream signal of autophagy was analyzed and it was found that Ad-VT reduced the resistance of cells to doxorubicin by reducing the level of mTOR, and then the analysis of the upstream and downstream proteins of mTOR found that Ad-VT increased the sensitivity of MCF-7/ADR cells to adriamycin by activating AMPK-mTOR-eIF4F signaling axis. Ad-VT can not only significantly induce cell death in MCF-7/ADR cells, but also improved their sensitivity to Adriamycin. Therefore, the combination of Ad-VT and chemotherapy drugs may become a new strategy for the treatment of breast cancer in overcoming Adriamycin resistance.

Microribonucleic Acid-15a-5p Alters Adriamycin Resistance in Breast Cancer Cells by Targeting Cell Division Cycle-Associated Protein 4.

ObjectiveAlthough chemotherapy is one of the first line clinical treatment of tumors, the efficacy of chemotherapy has been severely restricted by the frequent occurrence of drug resistance phenomenon. Multiple studies found that miRNAs can regulate the chemosensitivity of tumor cells. Here, this study aimed to assess the potential role of the miR-15a-5p/cell division cycle-related protein 4 (CDCA4) axis in breast cancer (BC) resistance to Adriamycin.MethodsIn the present study, the relative expression of miRNA-15a-5p in MCF-7/ADR, MCF-7 and Hs578Bst was measured by qRT-PCR. MCF-7/ADR cells underwent transfection with an miR-15a-5p mimic and inhibitor, respectively. Transwell assays, flow cytometry and CCK8 were performed to examine the potential effects of the abnormal expression of miR-15a-5p. The association of aberrant miR-15a-5p expression with Adriamycin resistance in BC was determined in cultured MCF-7/ADR cells. Bioinformatics was employed to predict the genes targeted by miR-15a-5p. Moreover, the correlation between miR-15a-5p and its target gene, CDCA4, was evaluated based on qRT-PCR data.ResultsThe expression of miR-15a-5p was significantly downregulated in MCF/ADR cells compared with MCF-7 and Hs578Bst cell lines. In the presence of Adriamycin, miR-15a-5p overexpression significantly increased cell chemosensitivity, as well as MCF-7/ADR cell proliferation, invasion, and migration, while promoting apoptosis and inducing cell-cycle arrest in the synthesis phase. CDCA4 RNA interference enhanced these effects as shown in our previous study. Bioinformatics identified CDCA4 as an miR-15a-5p target gene. qRT-PCR further demonstrated that CDCA4 and miR-15a-5p expression levels were inversely correlated.ConclusionAdriamycin resistance in BC cells was, at least in part, altered by mRNA-15a-5p via regulation of its target gene, CDCA4, by controlling the cell cycle, which may provide some novel ideas for BC chemotherapy in the future.

Curcumin attenuates Adriamycin-resistance of acute myeloid leukemia by inhibiting the lncRNA HOTAIR/miR-20a-5p/WT1 axis

Acute myeloid leukemia (AML) is a common subtype of leukemia, and a large proportion of patients with AML eventually develop drug resistance. Curcumin exerts cancer suppressive effects and increases sensitivity to chemotherapy in several diseases. This study aimed to investigate the mechanism by which curcumin affects the resistance of AML to Adriamycin by regulating HOX transcript antisense RNA (HOTAIR) expression. Cell viability, colony-formation, flow cytometry, and Transwell assays were used to assess cell proliferation, apoptosis, and migration. A dual-luciferase reporter assay was used to verify the interaction between microRNA (miR)-20a-5p and HOTAIR or Wilms' tumor 1 (WT1). RT-qPCR and Western blotting assays were performed to detect gene and protein expression. The results showed that curcumin suppressed the resistance to Adriamycin, inhibited the expression of HOTAIR and WT1, and promoted the expression of miR-20a-5p in human acute leukemia cells (HL-60) or Adriamycin-resistant HL-60 cells (HL-60/ADR). Furthermore, curcumin suppressed proliferation and promoted apoptosis of HL-60/ADR cells. Overexpression of HOTAIR reversed the regulatory effect of curcumin on apoptosis and migration and restored the effect of curcumin on inducing the expression of cleaved caspase3, Bax, and P27. In addition, HOTAIR upregulated WT1 expression by targeting miR-20a-5p, and inhibition of miR-20a-5p reversed the regulation of Adriamycin resistance by curcumin in AML cells. Finally, curcumin inhibited Adriamycin resistance by suppressing the HOTAIR/miR-20a-5p/WT1 pathway in vivo. In short, curcumin suppressed the proliferation and migration, blocked the cell cycle progression of AML cells, and sensitized AML cells to Adriamycin by regulating the HOTAIR/miR-20a-5p/WT1 axis. These findings suggest a potential role of curcumin and HOTAIR in AML treatment.The authors show that curcumin suppresses the proliferation and migration of acute myeloid leukemia (AML) cells. Curcumin also blocks cell cycle progression and sensitizes AML cells to Adriamycin by regulating the HOTAIR/miR-20a-5p/WT1 axis. These findings suggest a potential role of curcumin and HOTAIR in AML treatment.