Complex Epigenetic Regulation of Chemotherapy Resistance and Biohlogy in Esophageal Squamous Cell Carcinoma via MicroRNAs

Use of exosome transcriptome-based analysis to identify novel biomarkers in patients with locally advanced esophageal squamous cell carcinoma undergoing neoadjuvant chemoradiotherapy

Background

The prognosis of esophageal squamous cell carcinoma (ESCC) is improved by neoadjuvant chemoradiotherapy (nCRT), especially for patients with pathologic complete response (pCR). Despite the efforts to predict treatment response using multimodality, no molecule has proven to be a strong biomarker. This study aimed to profile the expression of exosome transcriptome that could predict pCR in ESCC before and after nCRT.

Methods

We collected paired blood samples of 15 patients with ESCC who received nCRT and radical surgery. They were divided into 3 groups: (A) residual tumor in the first clinical response evaluation (CRE-1), (B) no residual tumor in CRE-1 but with residual tumor in CRE-2 which was performed after 5-6 weeks, and (C) no residual tumor in CRE-1 or CRE-2. For each patient, the blood sample was collected before nCRT (time point 0); and then 6 weeks after nCRT, the clinical response was evaluated, and another blood sample was collected (time point 1).

Results

Using the intersection of different sets, we found 23 progression-associated messenger RNAs (mRNAs) and 67 remission-associated mRNAs. Between remission-associated mRNAs and the targets of progression-associated (carcinogenic) microRNAs (miRNAs), the intersection was acquired, and 2 miRNA-mRNA networks (IFIT2-miR-3615-IFIT2-miR-484 and BTN3A3-miR-6803-3p) were identified. Among the intersection of progression-associated (carcinogenic) mRNAs and the targets of remission-associated miRNAs, there is a network with miR-132-3p (remission-associated miRNA) located at the core, matched with DICER1, KLHL8, ANKRD12, ASH1L, and IMP4.

Conclusions

Our findings identified altered plasma exosome RNAs among the different groups and between different time points of nCRT, as well as the corresponding enrichments and regulatory networks, which may serve as potentially predictors of treatment response for patients with ESCC after nCRT.

MiR-129-2-3p Inhibits Esophageal Carcinoma Cell Proliferation, Migration, and Invasion via Targeting DNMT3B

PURPOSE

The study aims to explore the regulatory mechanism of miR-129-2-3p underlying esophageal carcinoma (EC) cell progression and generate new ideas for targeted treatment of EC.

METHODS

Mature miRNA expression data and total RNA sequencing data of EC in the TCGAESCA dataset were utilized to explore differentially expressed miRNAs (DEmiRNAs). StarBase database was then utilized to predict targets of miRNA. MiR-129-2-3p and DNMT3B expression in EC cell lines was assayed through qRT-PCR and Western blot. CCK-8, scratch healing, and transwell assays were conducted to assess the impact of miR-129-2-3p on EC cell phenotypes. In addition, a dual-luciferase assay was completed to identify the binding relationship between DNMT3B and miR-129-2-3p.

RESULTS

MiR-129-2-3p was noticeably less expressed in EC cell lines, while DNMT3B was highly expressed. MiR-129-2-3p could bind to DNMT3B. Furthermore, in vitro functional experiments uncovered that overexpressed miR-129-2-3p repressed EC cell progression while further overexpressing DNMT3B would restore the above inhibitory effect.

CONCLUSION

MiR-129-2-3p is a cancer repressor in EC cells, and it could target DNMT3B, thus hampering the progression of EC cells.

Identification of a novel ceRNA network related to prognosis and immunity in HNSCC based on integrated bioinformatic investigation

Head and neck squamous cell carcinoma (HNSCC) is characterized by an immunosuppression environment and necessitates the development of new immunotherapy response predictors. The study aimed to build a prognosis-related competing endogenous RNA (ceRNA) network based on immune-related genes (IRGs) and analyze its immunological signatures. Differentially expressed IRGs were identified by bioinformatics analysis with Gene Expression Omnibus (GEO), The Cancer Genome Atlas (TCGA) and ImmPort databases. Finally, via upstream prognosis-related microRNAs (miRNAs) and long noncoding RNAs (lncRNAs) prediction and co-expression analysis, we built an immune-related ceRNA network (LINC00052/hsa-miR-148a-3p/PLAU) related to HNSCC patient prognosis. CIBERSORT analysis demonstrated that there were substantial differences in 11 infiltrating immune cells in HNSCC, and PLAU was closely correlated with 10 type cells, including T cells CD8+ (R =  - 0.329), T cells follicular helper (R = - 0.342) and macrophage M0 (R = 0.278). Methylation and Tumor Immune Dysfunction and Exclusion (TIDE) analyses revealed that PLAU upregulation was most likely caused by hypomethylation and that high PLAU expression may be associated with tumor immune evasion in HNSCC, respectively.

MIR600HG sponges miR-125a-5p to regulate glycometabolism and cisplatin resistance of oral squamous cell carcinoma cells via mediating RNF44

There is increasing evidence that dysregulated long non-coding RNA (lncRNA) is implicated in tumorigenesis and progression. We aim to explore the role of lncRNA MIR600HG in glycometabolism and cisplatin (DDP) resistance of oral squamous cell carcinoma (OSCC) cells via regulating microRNA-125a-5p (miR-125a-5p) and RING finger 44 (RNF44). Expression of MIR600HG, miR-125a-5p, and RNF44 in OSCC clinical samples, cell lines, and DDP-resistant OSCC cells (SCC-9/DDP) was determined. In SCC-9 cells, proliferation, IC50 value of DDP, migration, invasion, and apoptosis were detected; in SCC-9/DDP cells, proliferation, IC50 value of DDP, apoptosis, glucose consumption, and production of lactic acid and ATP were evaluated. The interaction of MR600HG, miR-125a-5p, and RNF44 was verified. MIR600HG and RNF44 were upregulated while miR-125a-5p was downregulated in OSCC tissues and cell lines, and also in SCC-9/DDP cells. In SCC-9 cells, MIR600HG overexpression improved cell growth, metastasis, and inhibited cell susceptibility to DDP; in SCC-9/DDP cells, silencing of MIR600HG promoted apoptosis, improved DDP sensitivity, and inhibited cell glycolysis. Downregulation of miR-125a-5p showed the opposite effect to downregulation of MIR600HG. MIR600HG bound to miR-125a-5p and miR-125a-5p targeted RNF44. Downregulation of miR-125a-5p reversed the improvement of DDP sensitivity and the inhibition of cell glycolysis by downregulated MIR600HG on SCC-9/DDP cells. Downregulating RNF44 reversed the promotion of DDP resistance and cell glycolysis of SCC-9/DDP cells mediated by downregulation of miR-125a-5p. Collectively, our study addresses that MIR600HG downregulation elevates miR-125a-5p and reduces RNF44 expression, thereby improving DDP sensitivity and inhibiting glycolysis in DDP-resistant OSCC cells.

Molecular mechanisms associated with chemoresistance in esophageal cancer

Esophageal cancer (EC) is one of the most incident and lethal tumors worldwide. Although surgical resection is an important approach in EC treatment, late diagnosis, metastasis and recurrence after surgery have led to the management of adjuvant and neoadjuvant therapies over the past few decades. In this scenario, 5-fluorouracil (5-FU) and cisplatin (CISP), and more recently paclitaxel (PTX) and carboplatin (CBP), have been traditionally used in EC treatment. However, chemoresistance to these agents along EC therapeutic management represents the main obstacle to successfully treat this malignancy. In this sense, despite the fact that most of chemotherapy drugs were discovered several decades ago, in many cases, including EC, they still represent the most affordable and widely employed treatment approach for these tumors. Therefore, this review summarizes the main mechanisms through which the response to the most widely chemotherapeutic agents used in EC treatment is impaired, such as drug metabolism, apoptosis resistance, cancer stem cells (CSCs), cell cycle, autophagy, energetic metabolism deregulation, tumor microenvironment and epigenetic modifications.

Novel Implications of MicroRNAs, Long Non-coding RNAs and Circular RNAs in Drug Resistance of Esophageal Cancer

Esophageal cancer is the eighth most common malignancy and the sixth leading cause of cancer-related deaths worldwide. Chemotherapy based on platinum drugs, 5-fluorouracil, adriamycin, paclitaxel, gemcitabine, and vinorelbine, as well as targeted treatment and immunotherapy with immune checkpoint inhibitors improved the prognosis in a portion of patients with advanced esophageal cancer. Unfortunately, a number of esophageal cancer patients develop drug resistance, resulting in poor outcomes. Multiple mechanisms contributing to drug resistance of esophageal cancer have been reported. Notably, non-coding RNAs (ncRNAs), including microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), have been identified to play crucial roles in modulating esophageal cancer drug resistance. In the present review, we highlight the underlying mechanisms how miRNAs, lncRNAs, and circRNAs impact the drug resistance of esophageal cancer. Several miRNAs, lncRNAs, and circRNAs may have potential clinical implications as novel biomarkers and therapeutic targets for esophageal cancer.

Ursolic Acid Accelerates Paclitaxel-Induced Cell Death in Esophageal Cancer Cells by Suppressing Akt/FOXM1 Signaling Cascade

Ursolic acid (UA), a pentacyclic triterpenoid extracted from various plants, inhibits cell growth, metastasis, and tumorigenesis in various cancers. Chemotherapy resistance and the side effects of paclitaxel (PTX), a traditional chemotherapy reagent, have limited the curative effect of PTX in esophageal cancer. In this study, we investigate whether UA promotes the anti-tumor effect of PTX and explore the underlying mechanism of their combined effect in esophageal squamous cell carcinoma (ESCC). Combination treatment with UA and PTX inhibited cell proliferation and cell growth more effectively than either treatment alone by inducing more significant apoptosis, as indicated by increased sub-G1 phase distribution and protein levels of cleaved-PARP and cleaved caspase-9. Similar to the cell growth suppressive effect, the combination of UA and PTX significantly inhibited cell migration by targeting uPA, MMP-9, and E-cadherin in ESCC cells. In addition, combination treatment with UA and PTX significantly activated p-GSK-3β and suppressed the activation of Akt and FOXM1 in ESCC cells. Those effects were enhanced by the Akt inhibitor LY2940002 and inverted by the Akt agonist SC79. In an in vivo evaluation of a murine xenograft model of esophageal cancer, combination treatment with UA and PTX suppressed tumor growth significantly better than UA or PTX treatment alone. Thus, UA effectively potentiates the anti-tumor efficacy of PTX by targeting the Akt/FOXM1 cascade since combination treatment shows significantly more anti-tumor potential than PTX alone both in vitro and in vivo. Combination treatment with UA and PTX could be a new strategy for curing esophageal cancer patients.

miR-130a-3p Enhances the Chemosensitivity of Y79 Retinoblastoma Cells to Vincristine by Targeting PAX6 Expression

PURPOSE

Chemoresistance remains the primary obstacle threatening the prognosis of retinoblastoma (RB). microRNAs (miRNAs) are acknowledged as critical regulators of drug resistance. This study explored the molecular mechanism of miR-130a-3p affecting the chemosensitivity of RB to vincristine (VCR).

METHODS

miR-130a-3p expression of human retinal astrocytes and RB cell lines (Y79, WERI-Rb-1, SO-Rb50, and SO-Rb70) was detected using RT-qPCR. VCR-resistant RB cell line Y79/VCR was induced. miR-130a-3p expression of Y79/VCR cell line and its corresponding parental cell line was detected. Y79/VCR cells were subjected to miR-130a-3p overexpression treatment. The cell proliferation was measured using MTT assay, and the IC50 value and drug resistance index were examined using CCK-8 assay. The targeting relationship between miR-130a-3p and PAX6 was predicted through bioinformatics analysis and verified using dual-luciferase assay. Functional rescue experiments were conducted to confirm the role of PAX6 in chemosensitivity of RB cells. The effect of miR-130a-3p on tumorigenesis and VCR sensitivity was observed in vivo.

RESULTS

miR-130a-3p was downregulated in VCR-resistant RB cells. Overexpression of miR-130a-3p repressed the proliferation of Y79/VCR cells and enhanced chemosensitivity. miR-130a-3p targeted PAX6 expression. Overexpression of PAX6 reversed the effect of miR-130a-3p on chemosensitivity of Y79/VCR cells. Overexpression of miR-130a-3p suppressed tumor growth and reduced VCR resistance in vivo.

CONCLUSIONS

miR-130a-3p enhanced the chemosensitivity of Y79 RB cells to VCR by targeting PAX6 expression.

Circular RNA circ-CHI3L1.2 modulates cisplatin resistance of osteosarcoma cells via the miR-340-5p/LPAATβ axis

Resistance to chemotherapy drugs is a major factor affecting the surgical outcome and prognosis of osteosarcoma patients. Circular RNAs (circRNAs) play an important role in tumor resistance to chemotherapy. In the present study, we aimed to investigate the role and mechanism of circRNA circ-chitinase 3-like 1.2 (CHI3L1.2) in resistance to cisplatin chemotherapy in osteosarcoma. We found that circ-CHI3L1.2 levels were higher in cisplatin-resistant cells than in their parent cells. circ-CHI3L1.2 knockdown decreased the half-maximal inhibitory concentration (IC₅₀) of cisplatin and the expression levels of P-glycoprotein (P-gp), multidrug-resistance protein 1 (MRP1), and glutathione-S-transferase Pi1 (GSTP1), and promoted apoptosis of cisplatin-resistant osteosarcoma cells. In addition, circ-CHI3L1.2 knockdown induced mesenchymal to epithelial transition (MET) and suppressed cell migration and invasion. The competitive endogenous RNA (ceRNA) mechanism indicated that circ-CHI3L1.2 targets the micro-RNA (miR)-340-5p-lysophosphatidic acid acyltransferase β (LPAATβ) axis, and inhibition of miR-340-5p alleviates the effect of circ-CHI3L1.2 knockdown. In conclusion, circ-CHI3L1.2 levels were increased in cisplatin-resistant osteosarcoma cells and circ-CHI3L1.2 knockdown sensitized cisplatin-resistant osteosarcoma cells to cisplatin through the miR-340-5p-LPAATβ axis.

Hypoxia induces chemoresistance of esophageal cancer cells to cisplatin through regulating the lncRNA-EMS/miR-758-3p/WTAP axis

Hypoxia contributes significantly to the development of chemoresistance of many malignancies including esophageal cancer (EC). Accumulating studies have indicated that long non-coding RNAs play important roles in chemotherapy resistance. Here, we identified a novel lncRNA-EMS/miR-758-3p/WTAP axis that was involved in hypoxia-mediated chemoresistance to cisplatin in human EC. Hypoxia induced the expressions of lncRNA EMS and WTAP, and reduced the expression of miR-758-3p in EC cell line ECA-109. In addition, the expressions of EMS and WTAP were required for the hypoxia-induced drug resistance to cisplatin in EC cells, while overexpression of miR-758-3p reversed such chemoresistance. The targeting relationships between EMS and miR-758-3p, as well as miR-758-3p and WTAP, were verified by luciferase-based reporter assays and multiple quantitative assays after gene overexpression/knockdown. Moreover, we found significant correlations between tumor expressions of these molecules. Notably, higher levels of EMS/WTAP, or lower levels of miR-758-3p in tumors predicted worse survivals of EC patients. Furthermore, in a xenograft mouse model, targeted knockdown of EMS and WTAP in ECA-109 cells markedly attenuated the resistance of tumors to cisplatin treatments. Our study uncovers a critical lncRNA-EMS/miR-758-3p/WTAP axis in regulating hypoxia-mediated drug resistance to cisplatin in EC.

NOTCH3 limits the epithelial-mesenchymal transition and predicts a favorable clinical outcome in esophageal cancer

BACKGROUND

Esophageal squamous cell carcinoma (ESCC) is the deadliest of all human squamous cell carcinomas and is characterized by chemotherapy resistance and poor prognosis associated with the epithelial-mesenchymal transition (EMT). A subset of ESCC displays loss-of-function mutations in genes encoding Notch receptor family members, including NOTCH3. Although Notch signaling regulates EMT in ESCC cells, the role of NOTCH3 in EMT and chemotherapy resistance remains elusive. This study aimed to examine the role of NOTCH3 in EMT and chemotherapy resistance, and determine whether NOTCH3 expression can be used to predict the response to chemotherapy.

METHODS

In vitro and in vivo assays were conducted to clarify the contribution of NOTCH3 to chemotherapy resistance. Using specimens from 120 ESCC patients treated with neoadjuvant chemotherapy, we compared the expression levels of NOTCH3 and genes involved in EMT according to the degree of chemotherapy sensitivity.

RESULTS

In ESCC cells, chemotherapy resistance was associated with NOTCH3 downregulation and concurrent activation of EMT. RNA interference to silence NOTCH3 resulted in induction of the EMT marker Vimentin (VIM), leading to chemotherapy resistance in ESCC cells. Conversely, ectopic expression of the activated form of NOTCH3 suppressed EMT and sensitized cells to chemotherapy. Results of chromatin immunoprecipitation assays suggested that NOTCH3 may repress transcription of the VIM.

CONCLUSIONS

Our findings suggest that NOTCH3 may control chemotherapy sensitivity by regulating EMT. NOTCH3 may serve as a novel biomarker to predict better clinical outcomes in ESCC patients.

Mutant p53 Mediates Sensitivity to Cancer Treatment Agents in Oesophageal Adenocarcinoma Associated with MicroRNA and SLC7A11 Expression

TP53 gene mutations occur in 70% of oesophageal adenocarcinomas (OACs). Given the central role of p53 in controlling cellular response to therapy we investigated the role of mutant (mut-) p53 and SLC7A11 in a CRISPR-mediated JH-EsoAd1 TP53 knockout model. Response to 2 Gy irradiation, cisplatin, 5-FU, 4-hydroxytamoxifen, and endoxifen was assessed, followed by a TaqMan OpenArray qPCR screening for differences in miRNA expression. Knockout of mut-p53 resulted in increased chemo- and radioresistance (2 Gy survival fraction: 38% vs. 56%, p < 0.0001) and in altered miRNA expression levels. Target mRNA pathways analyses indicated several potential mechanisms of treatment resistance. SLC7A11 knockdown restored radiosensitivity (2 Gy SF: 46% vs. 73%; p = 0.0239), possibly via enhanced sensitivity to oxidative stress. Pathway analysis of the mRNA targets of differentially expressed miRNAs indicated potential involvement in several pathways associated with apoptosis, ribosomes, and p53 signaling pathways. The data suggest that mut-p53 in JH-EsoAd1, despite being classified as non-functional, has some function related to radio- and chemoresistance. The results also highlight the important role of SLC7A11 in cancer metabolism and redox balance and the influence of p53 on these processes. Inhibition of the SLC7A11-glutathione axis may represent a promising approach to overcome resistance associated with mut-p53.

MicroRNA Biomarkers of High-Grade Cervical Intraepithelial Neoplasia in Liquid Biopsy

New prevention strategies are needed to detect cervical intraepithelial neoplasia (CIN). The microRNA expression analysis has already been reported as molecular biomarkers in the early detection of cervical cancer (CC) through minimally invasive samples, such as liquid biopsy, obtained through collection using liquid-based cytology (LBC). In this study, we aimed to identify molecular signatures of microRNAs in cervical precursor lesions from LBC cervical and the molecular pathways potentially associated with the CC progression. We analyzed 31 LBC cervical samples from women who underwent colposcopy. These samples were divided into two groups: the first group was composed of samples without precursor lesions of CC, considering the control group, referred to as healthy female subjects (HFS; n = 11). The second group corresponded to women diagnosed with cervical interepithelial neoplasia grade 3 (CIN 3; n = 20). We performed microRNA and gene expression profiling using the nCounter® miRNA Expression Assays (NanoString Technology) and PanCancer Pathways (NanoString Technology), respectively. A microRNA target prediction was performed by mirDIP, and molecular pathway interaction was constructed using Cytoscape. Bidirectional in silico analyses and Pearson's correlation were performed for associated the relation between genes, and miRNAs differentially expressed related cervical cancer progression were performed. We found that the expression of nine microRNAs was significantly higher, two were downregulated (miR-381-3p and miR-4531), and seven miRNAs were upregulated (miR-205-5p, miR-130a-3p, miR-3136-3p, miR-128-2-5p, let-7f-5p, miR-202-3p, and miR-323a-5p) in CIN 3 (fold change ≥ 2 and p ≤ 0.05). The miRNA expression patterns were independent of hr-HPV infection. We identified four miRNAs (miR-205-5p, miR-130a-3p, miR-4531, and miR-381-3p) that could be used as biomarkers for CIN 3 in LBC samples through multiple logistic regression analyses. We found 16 genes differentially expressed between CIN 3 and HSF samples (fold change ≥ 2 and p ≤ 0.05). We found the correlation between miR-130a-3p and CCND1(R = −0.52; p = 0.0029), miR-205-5p and EGFR (R = 0.53; p = 0.0021), and miR-4531 and SMAD2 (R = −0.54; p = 0.0016). In addition, we demonstrated the most significant pathways of the targets associated with cervical cancer progression (FDR-corrected p < 0.001). This study demonstrated that miRNA biomarkers may distinguish healthy cervix and CIN 3 and regulate important molecular pathways of carcinogenesis.

Identification novel prognostic signatures for Head and Neck Squamous Cell Carcinoma based on ceRNA network construction and immune infiltration analysis

Background: Head and neck squamous cell carcinoma (HNSCC) is a common malignancy with high mortality and morbidity worldwide, but the underlying biological mechanisms of molecules and tumor infiltrating-immune cells (TIICs) are still unknown. Methods and Results: We obtained mRNAs, lncRNAs, and miRNAs expression profiles of 546 HNSCC from The Cancer Genome Atlas (TCGA) database to develop a ceRNA network. CIBERSORT was employed to estimate the fraction of 22 types of TIICs in HNSCC. Univariate and multivariate Cox regression and lasso regression analyses were used to develop prognostic signatures. Then, two novel risk signatures were constructed respectively based on six ceRNAs (ANLN, KIT, PRKAA2, NFIA, PTX3 and has-miR-148a-3p) and three immune cells (naïve B cells, regulatory T cells and Neutrophils). Kaplan-Meier (K-M) analysis and Cox regression analysis further proved that these two signatures were significant prognostic factors independent of multiple clinicopathological characteristics. Two nomograms were built based on ceRNAs-riskScore and TIICs-riskScore that could be used to predict the prognosis of HNSCC. Co-expression analysis showed significant correlations between miR-148a-3p and naive B cells, naive B cells and plasmas cells. Conclusion: Through construction of the ceRNA network and estimation of TIICs, we established two risk signatures and their nomograms with excellent utility, which indicated the potential molecular and cellular mechanisms, and predicted the prognosis of HNSCC.

MicroRNA Profiling in Oesophageal Adenocarcinoma Cell Lines and Patient Serum Samples Reveals a Role for miR-451a in Radiation Resistance

Many patients with Oesophageal Adenocarcinoma (OAC) do not benefit from chemoradiotherapy treatment due to therapy resistance. To better understand the mechanisms involved in resistance and to find potential biomarkers, we investigated the association of microRNAs, which regulate gene expression, with the response to individual treatments, focusing on radiation. Intrinsic radiation resistance and chemotherapy drug resistance were assessed in eight OAC cell lines, and miRNA expression profiling was performed via TaqMan OpenArray qPCR. miRNAs discovered were either uniquely associated with resistance to radiation, cisplatin, or 5-FU, or were common to two or all three of the treatments. Target mRNA pathway analyses indicated several potential mechanisms of treatment resistance. miRNAs associated with the in vitro treatment responses were then investigated for association with pathologic response to neoadjuvant chemoradiotherapy (nCRT) in pre-treatment serums of patients with OAC. miR-451a was associated uniquely with resistance to radiation treatment in the cell lines, and with the response to nCRT in patient serums. Inhibition of miR-451a in the radiation resistant OAC cell line OE19 increased radiosensitivity (Survival Fraction 73% vs. 87%, p = 0.0003), and altered RNA expression. Pathway analysis of effected small non-coding RNAs and corresponding mRNA targets suggest potential mechanisms of radiation resistance in OAC.

MicroRNA-338-5p reverses chemoresistance and inhibits invasion of esophageal squamous cell carcinoma cells by targeting Id-1

5‐Fluorouracil (5‐FU) is a chemotherapeutic agent commonly used to treat esophageal squamous cell carcinoma (ESCC), but acquisition of chemoresistance frequently occurs and the underlying mechanisms are not fully understood. We found that microRNA (miR)‐338‐5p was underexpressed in ESCC cells with acquired 5‐FU chemoresistance. Forced expression of miR‐338‐5p in these cells resulted in downregulation of Id‐1, and restoration of both in vitro and in vivo sensitivity to 5‐FU treatment. The effects were abolished by reexpression of Id‐1. In contrast, miR‐338‐5p knockdown induced 5‐FU resistance in chemosensitive esophageal cell lines, and knockdown of both miR‐338‐5p and Id‐1 resensitized the cells to 5‐FU. In addition, miR‐338‐5p had suppressive effects on migration and invasion of ESCC cells. Luciferase reporter assay confirmed a direct interaction between miR‐338‐5p and the 3′‐UTR of Id‐1. We also found that miR‐338‐5p was significantly downregulated in tumor tissue and serum samples of patients with ESCC. Notably, low serum miR‐338‐5p expression level was associated with poorer survival and poor response to 5‐FU/cisplatin‐based neoadjuvant chemoradiotherapy. In summary, we found that miR‐338‐5p can modulate 5‐FU chemoresistance and inhibit invasion‐related functions in ESCC by negatively regulating Id‐1, and that serum miR‐338‐5p could be a novel noninvasive prognostic and predictive biomarker in ESCC.

MicroRNA-652 inhibits the biological characteristics of esophageal squamous cell carcinoma by directly targeting fibroblast growth factor receptor 1

Numerous studies have demonstrated that microRNAs (miRNAs) are dysregulated in esophageal squamous cell carcinoma (ESCC). Changes in miRNA expression may be associated with ESCC formation and progression. Therefore, the identification of ESCC-associated miRNAs may facilitate the development of effective therapeutic approaches for patients with ESCC. Recently, miRNA-652 (miR-652) was recognized as a cancer-associated miRNA in a number of different types of cancer. However, the expression status and roles of miR-652 in ESCC as well as the molecular mechanisms modulated or altered by it remain largely unknown. In the present study, it was demonstrated that miR-652 was downregulated in ESCC tissues and cell lines. Functional assays showed that upregulation of miR-652 expression decreased proliferation and invasion of ESCC cells. Mechanistically, fibroblast growth factor receptor 1 (FGFR1) was determined to be a direct target of miR-652 in ESCC cells. Additionally, FGFR1 was upregulated in ESCC tissues, and the expression of FGFR1 was inversely correlated with miR-652 expression. Furthermore, restoring FGFR1 expression abolished the suppressive effects of miR-652 overexpression on the proliferation and invasion of ESCC cells. These findings demonstrated that miR-652 inhibits the proliferation and invasion of ESCC cells by directly targeting FGFR1.

miR-145 Regulates the sensitivity of esophageal squamous cell carcinoma cells to 5-FU via targeting REV3L

Aberrant expression of miR-145 was associated with chemotherapy in multitype cancers. However, the underlying role and molecular mechanism of miR-145 in the sensitivity of esophageal squamous cell carcinoma (ESCC) to 5-FU remained largely unknown. Cell viability was determined by Cell Counting Kit-8 (CCK-8) assay. Gene expression levels were detected by real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR). Protein expression levels were evaluated by Western blot. TargetScan was used for the prediction of binding sites for miRNA in mRNAs. The interaction between mRNA 3' UTR and miRNA was verified by dual luciferase reporter assay. The results showed that miR-145 was downregulated in ESCC tumor tissues and cells, while REV3L was upregulated in ESCC tumor tissues. Overexpression of miR-145 decreased REV3L mRNA and protein level in ESCC cell line KYSE150, while decreased miR-145 increased REV3L mRNA and protein level in esophageal epithelium cell line (HEEC). In addition, the luciferase activity of ESCC cells was decreased after the treatment of miR-145 mimic and mRNA 3'UTR-WT. Overexpressed miR-145 significantly inhibited cell viability and elevated cell apoptosis rate upon 5-FU treatment. Additionally, transfection of miR-145 mimic further altered expression of key genes involved in cell apoptosis (Bcl-2, Bax, Caspase3) in ESCC cells treated with 5-FU. miR-145 might be a therapeutic target for the treatment of ESCC.

miR-148a-3p Suppresses the Proliferation and Invasion of Esophageal Cancer by Targeting DNMT1

AIM

To identify whether miR-148a-3p interacts with DNA (cytosine-5)-methyltransferase 1 (DNMT1) in esophageal cancer.

METHODS

A luciferase assay and immunoblotting were performed to detect the relationship between miR-148a-3p and DNMT1. The MTT method, Annexin V/propidium iodide staining, and Transwell assays were adopted to assess the biological behaviors in EC109 cells. The association between the expression level of miR-148a-3p, clinical features, and prognosis were evaluated by chi-square test and univariate survival analysis.

RESULTS

In this study, DNMT1 was identified as a direct target of miR-148a-3p by luciferase assay and Western blot. Real-time quantitative PCR analyses showed that the relative expression levels of miR-148a-3p and DNMT1 were reduced in esophageal cancer samples compared with adjacent tissues; and a negative relationship between both was indicated. Upon overexpression of miR-148a-3p in esophageal cancer cells, proliferation and invasion were significantly suppressed, and apoptosis was promoted. A higher level of miR-148a-3p was correlated with better patient outcomes.

CONCLUSIONS

Our study indicated that miR-148a-3p, by targeting DNMT1, likely regulates cell proliferation and invasion in esophageal cancer. miR-148a-3p might also be used prognostically in esophageal cancer and serve as a therapeutic target in the future.

Correction: Complex Epigenetic Regulation of Chemotherapy Resistance and Biology in Esophageal Squamous Cell Carcinoma via MicroRNAs. Int. J. Mol. Sci. 2018, 19, 499

We would like to submit a correction to the published paper [...].

Complex role of miR-130a-3p and miR-148a-3p balance on drug resistance and tumor biology in esophageal squamous cell carcinoma

miRNAs play a crucial role in cancer development and progression. However, results on the impact of miRNAs on drug sensitivity and tumor biology vary, and most studies to date focussed on either increasing or decreasing miRNA expression levels. Therefore, the current study investigated the role of different expression levels of miR-130a-3p and miR-148a-3p on drug resistance and tumor biology in four esophageal squamous cell carcinoma cell lines. Interestingly, up- and downregulation of both miRNAs significantly increased sensitivity towards chemotherapy. MiRNA modulation also reduced adherence and migration potential, and increased apoptosis rates. Target analyses showed that up- and downregulation of both miRNAs activated the apoptotic p53-pathway via increased expression of either BAX (miR-148a-3p) or Caspase 9 (miR-130a-3p). miR-148a-3p downregulation seemed to mediate its effects primarily via regulation of Bim rather than Bcl-2 levels, whereas we found the opposite scenario following miR-148a-3p upregulation. A similar effect was observed for miR-130a-3p regulating Bcl-2 and XIAP. Our data provide the first evidence that miRNA modulation in both directions may lead to similar effects on chemotherapy response and tumor biology in esophageal squamous cell carcinoma. Most interestingly, up- and downregulation seem to mediate their effects via modulating the balance of several validated or predicted targets.