MiR-615 inhibits cell proliferation, migration and invasion by targeting EGFR in human glioblastoma

Microglia-derived exosomes modulate myelin regeneration via miR-615-5p/MYRF axis

Demyelination and failure of remyelination in the central nervous system (CNS) characterize a number of neurological disorders. Spontaneous remyelination in demyelinating diseases is limited, as oligodendrocyte precursor cells (OPCs), which are often present in demyelinated lesions in abundance, mostly fail to differentiate into oligodendrocytes, the myelinating cells in the CNS. In addition to OPCs, the lesions are assembled numbers of activated resident microglia/infiltrated macrophages; however, the mechanisms and potential role of interactions between the microglia/macrophages and OPCs are poorly understood. Here, we generated a transcriptional profile of exosomes from activated microglia, and found that miR-615-5p was elevated. miR-615-5p bound to 3'UTR of myelin regulator factor (MYRF), a crucial myelination transcription factor expressed in oligodendrocyte lineage cells. Mechanistically, exosomes from activated microglia transferred miR-615-5p to OPCs, which directly bound to MYRF and inhibited OPC maturation. Furthermore, an effect of AAV expressing miR-615-5p sponge in microglia was tested in experimental autoimmune encephalomyelitis (EAE) and cuprizone (CPZ)-induced demyelination model, the classical mouse models of multiple sclerosis. miR-615-5p sponge effectively alleviated disease progression and promoted remyelination. This study identifies miR-615-5p/MYRF as a new target for the therapy of demyelinating diseases.

Synthesis, photophysical properties, anticancer evaluation, and molecular docking studies of new pyrimidine linked 4-arylidene-thiazolidin-4-ones as potent anticancer agents

The reaction of 4-(chloroacetamido)pyrimidine (1) with ammonium thiocyanate gave 2-(pyrimidin-4-ylimino)thiazolidin-4-one (2), which, when condensed with four substituted benzaldehyde analogues, gave the consequent 5-arylidine-2-(pyrimidin-4-ylimino)thiazolidin-4-ones 3a-d. In addition, the absorbance and fluorescence behaviours of pyrimidinylimino-thiazolidin-4-one hybrids 3a-d in various organic solvents were investigated. The emphasis was on studying UV absorption capacities and the effect of various structural components on photophysical qualities such as the 5-arylidene-2-(pyrimidin-4-ylimino)thiazolidin-4-ones and N,N-dimethylamino tail. The cytotoxic effect of four pyrimidinylimino-thiazolidin-4-one hybrids 3a-d on tumour cell lines (HepG2, HCT-116, PC3, MCF-7) and a normal cell line (WI38) is investigated in this work. The cytotoxicity was measured by comparing the half-maximal inhibitory concentration (IC50 ) to the reference medication, 5-fluorouracil. The findings indicate that these hybrid compounds had varying cytotoxic effects on the cell lines examined; hybrids 3b and 3c demonstrated significant anticancer activity against MCF-7 with IC50 values of 7.53 ± 0.43 and 9.17 ± 0.31 μM, respectively. The inhibitory efficacy of various synthesized hybrids on the epidermal growth factor receptor (EGFR) kinase was investigated. EGFR is a crucial target in cancer treatment because inhibiting it may reduce tumour development and proliferation. The IC50 value was used to calculate the inhibitory activity, which is the concentration of inhibitor necessary to induce half-maximal inhibition of EGFR kinase activity. In addition, the predicted ADME results show that pyrimidinylimino-thiazolidin-4-one hybrids have good pharmacokinetic properties; hybrid 3d is more lipophilic than the other compounds. It has a medium molecular weight, a small number of hydrogen bond acceptors and donors, and a large number of aromatic heavy atoms. Moreover, molecular docking simulations revealed precise information on the interactions of pyrimidinylimino-thiazolidin-4-one hybrids 3a-d and 5-Fu with their respective protein targets. These interactions point to possible pathways for their biological activities and call for more testing to establish their effectiveness as bioactive molecules or therapeutic candidates.

Y-box protein-1 modulates circSPECC1 to promote glioma tumorigenesis via miR-615-5p/HIP1/AKT axis

Y-box binding protein-1 (YB-1) is upregulated in glioma and plays an important role in its occurrence and drug resistance. However, the involved regulatory processes and downstream pathways are still unclear. Since various circular RNAs (circRNAs) and microRNAs (miRNAs) also play roles in the pathogenesis of glioma, we hypothesize that YB-1 may exert its function through a circRNA-miRNA-protein interaction network. In this study, we use the RNA binding protein immunoprecipitation assay and quantitative reverse transcription polymerase chain reaction to determine the circRNAs involved in the regulation of YB-1 and further elucidate their biological functions. The level of circSPECC1 (hsa_circ_0000745) modulated by YB-1 is significantly upregulated in the U251 and U87 glioma cell lines. Downregulation of circSPECC1 markedly inhibits the proliferation and invasiveness of U251 and U87 cells by inducing apoptosis. Bioinformatics analysis reveals that miR-615-5p could interact with circSPECC1 and huntingtin-interacting protein-1 (HIP-1). Then we determine the interactions between miR-615-5p, circSPECC1, and HIP1 using dual luciferase reporter system and pull-down assays. Mechanistic analysis indicates that the downregulation of circSPECC1 results in a decreased HIP1 expression. This study demonstrates that circSPECC1 modulated by YB-1 is increased in glioma cell lines. In addition, circSPECC1 promotes glioma growth through the upregulation of HIP1 by sponging miR-615-5p and targeting the HIP1/AKT pathway. This indicates that YB-1 and circSPECC1 may both be promising targets for glioma treatment.

Pro-inflammatory Cytokines Promote the Occurrence and Development of Colitis-associated Colorectal Cancer by Inhibiting miR-615-5p

BACKGROUND

Patients with ulcerative colitis (UC) may be prone to colitis-associated colorectal cancer (CAC), but there is still a poor understanding of the underlying mechanism so far. This study intended to clarify the role of pro-inflammatory cytokines and miR-615-5p in this process.

METHODS

This experiment first detected miR-615-5p expressions in paraffin-embedded sections of colonic tissues from patients with UC and CAC. Then, we investigated the mechanism through which pro-inflammatory cytokines affected miR-615-5p. Furthermore, in vivo and in vitro tests were performed to identify how miR-615-5p affected colorectal cancer (CRC). Dual-luciferase reporter assay was then employed to identify the targeting relationship between miR-615-5p and stanniocalcin-1 (STC1).

RESULTS

The miR-615-5p was lowly expressed in both cancerous and noncancerous colonic tissues of patients with CAC. Pro-inflammatory cytokines downregulated miR-615-5p expression. Overexpression of miR-615-5p reduced the proliferation and migration of CRC cells and had a certain therapeutic effect on in human CRC xenograft mice. Stanniocalcin-1 was identified to be a target gene of miR-615-5p and was involved in the effect of miR-615-5p on CRC.

CONCLUSIONS

During the progression from UC to CAC, pro-inflammatory cytokines downregulate miR-615-5p, which may induce the upregulation of STC1, and promote the occurrence and development of tumors. These findings offer new insights into the mechanism of CAC and may indicate novel tumor markers or therapeutic targets.

Integrated co-expression analysis of regulatory elements (miRNA, lncRNA, and TFs) in bovine monocytes induced by Str. uberis

Non-coding RNAs, including long non-coding RNAs (lncRNAs) and microRNAs (miRNAs), together with transcription factors, are critical pre-, co-, and post-transcriptional regulators. In addition to their criteria as ideal biomarkers, they have great potential in disease prognosis, diagnosis, and treatment of complex diseases. Investigation of regulatory mechanisms in the context of bovine mastitis, as most common and economic disease in the dairy industry, to identify elements influencing the expression of candidate genes as key regulators of the mammary immune response is not yet fully understood. Transcriptome profiles (50 RNA-Seq and 50 miRNA-Seq samples) of bovine monocytes induced by Str. uberis were used for co-expression module detection and preservation analysis using the weighted gene co-expression network analysis (WGCNA) approach. Assigned mi-, lnc-, and m-modules used to construct the integrated regulatory networks and miRNA-lncRNA-mRNA regulatory sub-networks. Remarkably, we have identified 18 miRNAs, five lncRNAs, and seven TFs as key regulators of str. uberis-induced mastitis. Most of the genes introduced here, mainly involved in immune response, inflammation, and apoptosis, were new to mastitis. These findings may help to further elucidate the underlying mechanisms of bovine mastitis, and the discovered genes may serve as signatures for early diagnosis and treatment of the disease.

Cellular Conversations in Glioblastoma Progression, Diagnosis and Treatment

Glioblastoma (GBM) is the most frequent malignancy among primary brain tumors in adults and one of the worst 5-year survival rates (< 7%) among all human cancers. Till now, treatments that target particular cell or intracellular metabolism have not improved patients' survival. GBM recruits healthy brain cells and subverts their processes to create a microenvironment that contributes to supporting tumor progression. This microenvironment encompasses a complex network in which malignant cells interact with each other and with normal and immune cells to promote tumor proliferation, angiogenesis, metastasis, immune suppression, and treatment resistance. Communication can be direct via cell-to-cell contact, mainly through adhesion molecules, tunneling nanotubes, gap junctions, or indirect by conventional paracrine signaling by cytokine, neurotransmitter, and extracellular vesicles. Understanding these communication routes could open up new avenues for the treatment of this lethal tumor. Hence, therapeutic approaches based on glioma cells` communication have recently drawn attention. This review summarizes recent findings on the crosstalk between glioblastoma cells and their tumor microenvironment, and the impact of this conversation on glioblastoma progression. We also discuss the mechanism of communication of glioma cells and their importance as therapeutic targets and diagnostic and prognostic biomarkers. Overall, understanding the biological mechanism of specific interactions in the tumor microenvironment may help in predicting patient prognosis and developing novel therapeutic strategies to target GBM.

Functions of non-coding RNAs in regulating cancer drug targets

With the development of precision medicine, the efficiency of tumor treatment has been significantly improved. More attention has been paid to targeted therapy and immunotherapy as the key to precision treatment of cancer. Targeting epidermal growth factor receptor (EGFR) has become one of the most important targeted treatments for various cancers. Comparing with traditional chemotherapy drugs, targeting EGFR is highly selective in killing tumor cells with better safety, tolerability and less side effect. In addition, tumor immunotherapy has become the fourth largest tumor therapy after surgery, radiotherapy and chemotherapy, especially immune checkpoint inhibitors. However, these treatments still produce a certain degree of drug resistance. Non-coding RNAs (ncRNAs) were found to play a key role in carcinogenesis, treatment and regulation of the efficacy of anticancer drugs in the past few years. Therefore, in this review, we aim to summarize the targeted treatment of cancers and the functions of ncRNAs in cancer treatment.

Iodine-125 seed represses the growth and facilitates the apoptosis of colorectal cancer cells by suppressing the methylation of miR-615 promoter

BACKGROUND

Colorectal cancer (CRC) represents a common malignancy in gastrointestinal tract. Iodine-125 (¹²⁵I) seed implantation is an emerging treatment technology for unresectable tumors. This study investigated the mechanism of ¹²⁵I seed in the function of CRC cells.

METHODS

The CRC cells were irradiated with different doses of ¹²⁵I seed (0.4, 0.6 and 0.8 mCi). miR-615 expression in CRC tissues and adjacent tissues was detected by RT-qPCR. miR-615 expression was intervened with miR-615 mimic or miR-615 inhibitor, and then the CRC cells were treated with 5-AZA (methylation inhibitor). The CRC cell growth, invasion and apoptosis were measured. The methylation level of miR-615 promoter region was detected. The xenograft tumor model irradiated by ¹²⁵I seed was established in nude mice. The methylation of miR-615, Ki67 expression and CRC cell apoptosis were detected.

RESULTS

¹²⁵I seed irradiation repressed the growth and facilitated apoptosis of CRC cells in a dose-dependent manner. Compared with adjacent tissues, miR-615 expression in CRC tissues was downregulated and miR-615 was poorly expressed in CRC cells. Overexpression of miR-615 suppressed the growth of CRC cells. ¹²⁵I seed-irradiated CRC cells showed increased miR-615 expression, reduced growth rate and enhanced apoptosis. The methylation level of miR-615 promoter region in CRC cells was decreased after ¹²⁵I seed treatment. In vivo experiments confirmed that ¹²⁵I seed-irradiated xenograft tumors showed reduced methylation of the miR-615 promoter and increased miR-615 expression, as well as decreased Ki67 expression and enhanced apoptosis. The target genes of miR-615 and its regulatory downstream pathway were further predicted by bioinformatics analysis.

CONCLUSIONS

¹²⁵I seed repressed the growth and facilitated the apoptosis of CRC cells by suppressing the methylation of the miR-615 promoter and thus activating miR-615 expression. The possible mechanism was that miR-615-5p targeted MAPK13, thus affecting the MAPK pathway and the progression of CRC.

circular RNAs 0000515 and 0011385 as potential biomarkers for disease monitoring and determining prognosis in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is extremely fatal and potential biomarkers for precision medicine of patients with PDAC are yet to be elucidated. Moreover, the clinical values of circular RNAs (circRNAs) in PDAC management are yet to be investigated. The aim of the present study was to perform a secondary analysis of two PDAC public datasets (GSE69362 and GSE79634), to identify the candidate circRNAs, to validate the expression of these circRNAs, and to determine their association with the clinicopathological characteristics and survival of patients with PDAC. A total of 60 patients with PDAC were retrospectively reviewed in the present study. The expression levels of these candidate circRNAs were detected in PDAC tissues and paired adjacent normal tissues via reverse transcription-quantitative PCR analysis. In addition, the clinicopathological characteristics and overall survival (OS) of patients with PDAC were recorded. Bioinformatics analysis identified 22 overlapping differentially expressed (DE) circRNAs between the GSE69362 and GSE79634 datasets, among which nine DEcircRNAs with accordant expression trends (the DEcircRNAs that were upregulated or downregulated in tumor tissues compared with paired adjacent normal tissues in both datasets) were selected as candidate circRNAs, including circ_0000515, circ_0000517, circ_0000520, circ_0000514, circ_0011385, circ_0055033, circ_0072088, circ_0003528 and circ_0008514. In the 60 patients with PDAC, the expression levels of circ_0000515, circ_0000517, circ_0000520, circ_0000514, circ_0011385, circ_0055033, circ_0072088 and circ_0003528 were notably upregulated in PDAC tissues compared with paired adjacent normal tissues. Furthermore, circ_0000515, circ_0000520, circ_0000514, circ_0011385 and circ_0072088 were positively associated with T stage, N stage and/or TNM stage in patients with PDAC. Notably, circ_0000515 and circ_0011385 were negatively associated with OS in patients with PDAC. Taken together, the results of the present study suggest that circ_0000515 and circ_0011385 may serve as prognostic biomarkers for patients with PDAC.

LncRNA PITPNA-AS1 stimulates cell proliferation and suppresses cell apoptosis in glioblastoma via targeting miR-223-3p/EGFR axis and activating PI3K/AKT signaling pathway

Glioblastoma (GBM) is a kind of malignant primary brain tumor, which is difficult to cure. Continuous researches have underlined that long non-coding RNAs (lncRNAs) get widely involved in the occurrence and progression of tumors, and glioblastoma is included. In this paper, we identified lncRNA PITPNA antisense RNA 1 (PITPNA-AS1) and explored its in-depth regulatory mechanism in glioblastoma cells. Firstly, RT-qPCR examined that PITPNA-AS1 was highly expressed in glioblastoma. Then, PITPNA-AS1 role in glioblastoma was assessed via functional assays. The results demonstrated that depletion of PITPNA-AS1 inhibited the proliferation and promoted the apoptosis of glioblastoma cells. After confirming that PITPNA-AS1 mainly existed in cell cytoplasm, we conducted mechanism assays which disclosed that PITPNA-AS1 sequestered microRNA-223-3p (miR-223-3p) and modulated epidermal growth factor receptor (EGFR) expression, thereby participating in the activation of PI3K/AKT signaling pathway. Eventually, rescue assays validated PITPNA-AS1 sponged miR-223-3p to promote EGFR expression, thus activating PI3K/AKT signaling pathway to accelerate proliferation and inhibit apoptosis of GBM cells. Overall, PITPNA-AS1 played an oncogenic role in glioblastoma which might be developed as a potential biomarker for glioblastoma diagnosis and treatment in the future.[Figure: see text].

Design, synthesis, and analysis of antiproliferative and apoptosis-inducing activities of nitrile derivatives containing a benzofuran scaffold: EGFR inhibition assay and molecular modelling study

New cyanobenzofurans derivatives 2-12 were synthesised, and their antiproliferative activity was examined compared to doxorubicin and Afatinib (IC₅₀ = 4.17-8.87 and 5.5-11.2 µM, respectively). Compounds 2 and 8 exhibited broad-spectrum activity against HePG2 (IC₅₀ = 16.08-23.67 µM), HCT-116 (IC₅₀ = 8.81-13.85 µM), and MCF-7 (IC₅₀ = 8.36-17.28 µM) cell lines. Compounds 2, 3, 8, 10, and 11 were tested as EGFR-TK inhibitors to demonstrate their possible anti-tumour mechanism compared to gefitinib (IC₅₀ = 0.90 µM). Compounds 2, 3, 10, and 11 displayed significant EGFR TK inhibitory activity with IC₅₀ of 0.81-1.12 µM. Compounds 3 and 11 induced apoptosis at the Pre-G phase and cell cycle arrest at the G2/M phase. They also increased the level of caspase-3 by 5.7- and 7.3-fold, respectively. The molecular docking analysis of compounds 2, 3, 10, and 11 indicated that they could bind to the active site of EGFR TK.

mTOR-Rictor-EGFR axis in oncogenesis and diagnosis of glioblastoma multiforme

Glioblastoma multiforme (GBM) is one of the aggressive brain cancers with patients having less survival period upto 12-15 months. Mammalian target of rapamycin (mTOR) is a serine/threonine kinase, belongs to the phosphatidylinositol 3-kinases (PI3K) pathway and is involved in various cellular processes of cancer cells. Cancer metabolism is regulated by mTOR and its components. mTOR forms two complexes as mTORC1 and mTORC2. Studies have identified the key component of the mTORC2 complex, Rapamycin-insensitive companion of mammalian target of rapamycin (Rictor) plays a prominent role in the regulation of cancer cell proliferation and metabolism. Apart, growth factor receptor signaling such as epidermal growth factor signaling mediated by epidermal growth factor receptor (EGFR) regulates cancer-related processes. In EGFR signaling various other signaling cascades such as phosphatidyl-inositol 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR pathway) and Ras/Raf/mitogen-activated protein kinase/ERK kinase (MEK)/extracellular-signal-regulated kinase (ERK) -dependent signaling cross-talk each other. From various studies about GBM, it is very well established that Rictor and EGFR mediated signaling pathways majorly playing a pivotal role in chemoresistance and tumor aggressiveness. Recent studies have shown that non-coding RNAs such as microRNAs (miRs) and long non-coding RNAs (lncRNAs) regulate the EGFR and Rictor and sensitize the cells towards chemotherapeutic agents. Thus, understanding of microRNA mediated regulation of EGFR and Rictor will help in cancer prevention and management as well as a future therapy.

Clinical and In Silico Outcomes of the Expression of miR-130a-5p and miR-615-3p in Tumor Compared with Non-Tumor Adjacent Tissues of Patients with BC

BACKGROUND

Breast Cancer (BC) is the most common malignancy among women with a high mortality rate. The blockade of asparagine-related pathways may be an effective measure to control the progression and reduction of BC metastasis potential. Recently, it has been shown that various miRNAs, as part of small non-coding RNAs, have a great role in cancer development, especially asparagine-related pathways, to modulate the invasiveness.

OBJECTIVE

This study aimed to evaluate the expression of miR-130a-5p and miR-615-3p in tumoral and nontumoral adjacent tissues of patients with BC.

METHODS

There is a chance that asparagine metabolism is influenced by miR-130a-5p and miR-615-3p as confirmed by bioinformatics analysis. Hence, real-time PCR was conducted on eighty BC tumoral and non-tumoral adjacent tissues to evaluate the expression level of the two miRNAs. To predict the potential biological process and molecular pathways of miR-130a-5p, an in silico analysis was performed.

RESULTS

This study indicated that miR-130a was downregulated in tumoral tissues compared to non-tumoral adjacent tissues (P-value= 0.01443 and fold change= -2.5137), while miR-615-3p did not show a significant difference between the two groups. Furthermore, the subgroup studies did not reveal any significant correlation between the expression of these two miRNAs and subfactors. Furthermore, in silico studies unraveled several biological processes related to amino-acid metabolism, as well as pathways related to tumor development such as Phosphatase and Tensin Homolog (PTEN) and JAK-STAT pathways among miR-130a-5p target genes.

CONCLUSION

Our findings indicate that miRNA-130a-5p is downregulated in BC tissues and may play a tumor suppressor role in patients with BC. Therefore, it may be suggested as a potential diagnostic and therapeutic target for BC.

Notch intracellular domain regulates glioblastoma proliferation through the Notch1 signaling pathway

Notch intracellular domain (NICD), also known as the activated form of Notch1 is closely associated with cell differentiation and tumor invasion. However, the role of NICD in glioblastoma (GBM) proliferation and the underlying regulatory mechanism remains unclear. The present study aimed to investigate the expression of NICD and Notch1 downstream gene HES5 in human GBM and normal brain samples and to further detect the effect of NICD on human GBM cell proliferation. For this purpose, western blotting and immunohistochemical staining were performed to analyze the expression of NICD in human GBM tissues, while western blotting and reverse-transcription quantitative PCR experiments were used to analyze the expression of Hes5 in human GBM tissues. A Flag-NICD vector was used to overexpress NICD in U87 cells and compound E and small interfering (si) Notch1 were used to downregulate NICD. Cellular proliferation curves were generated and BrdU assays performed to evaluate the proliferation of U87 cells. The results demonstrated that compared with normal brain tissues, the level of NICD protein in human GBM tissues was upregulated and the protein and mRNA levels of Hes5 were also upregulated in GBM tissues indicating that the Notch1 signaling pathway is activated in GBM. Overexpression of NICD promoted the proliferation of U87 cells in vitro while downregulation of NICD by treatment with compound E or siNotch1 suppressed the proliferation of U87 cells in vitro. In conclusion, NICD was upregulated in human GBM and NICD promoted GBM proliferation via the Notch1 signaling pathway. NICD may be a potential diagnostic marker and therapeutic target for GBM treatment.

MicroRNAs involved in the EGFR pathway in glioblastoma

Glioblastoma (GBM) is the most common primary malignant tumor in adults, and its morbidity and mortality are very high. Although progress has been achieved in the treatment of GBM, such as surgery, chemotherapy and radiotherapy, in recent years, the prognosis of patients with GBM has not improved significantly. MicroRNAs (miRNAs) are endogenous noncoding single-stranded RNAs consisting of approximately 20-22 nucleotides that regulate gene expression at the posttranscriptional level by binding to target protein-encoding mRNAs. Notably, miRNAs regulate various carcinogenic pathways, one of which is the epidermal growth factor receptor (EGFR) signaling pathway, which controls cell proliferation, invasion, migration, angiogenesis and apoptosis. In this review, we summarize the novel discoveries of roles for miRNAs targeting the factors in the EGFR signaling pathway in the occurrence and development of GBM. In addition, we describe their potential roles as biomarkers for the diagnosis and prognosis of GBM and for determining the treatment resistance of GBM and the efficacy of therapeutic drugs.

MicroRNA-126-5p suppresses cell proliferation, invasion and migration by targeting EGFR in liver cancer

BACKGROUND

The expression status and potential mechanistic involvement of microRNA (miR)-126-5p in hepatocellular carcinoma (HCC) are still elusive currently. Here we set out to address this issue both in cell lines and in patients' tissues.

METHODS

The relative expression levels of endogenous miR-126-5p and epidermal growth factor receptor (EGFR) were quantified by real-time polymerase chain reaction. Cell viability and proliferation were measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and clonogenic assays, respectively. Cell invasive and migrative capacities were determined by transwell and wound healing assays, respectively. The regulatory action of miR-126-5p on EGFR was interrogated by luciferase reporter assay. Translational level of EGFR was analyzed by Western blotting.

RESULTS

MiR-126-5p was significantly down-regulated in both HCC patients' tissues and cell lines. Forced expression of miR-126-5p greatly compromised cell viability, proliferation, invasion and migration, while miR-126-5p-specific inhibitor promoted these oncogenic phenotypes. MiR-126-5p mimics inhibited endogenous expression of EGFR and suppressed EGFR 3'-untranslated region-fused luciferase activity. Co-expression of EGFR in miR-126-5p-proficient cells completely restored cell migrative and invasive capacities, while co-transfection with EGFR siRNA significantly inhibited miR-126-5p inhibitor-induced cell invasion and migration.

CONCLUSION

MiR-126-5p was aberrantly decreased in HCC and subsequently relieved the suppression on EGFR expression, which consequently contributed to the tumor biology of HCC.

miRNA signature in glioblastoma: Potential biomarkers and therapeutic targets

MicroRNAs (miRNAs) are transcripts with sizes of about 22 nucleotides, which are produced through a multistep process in the nucleus and cytoplasm. These transcripts modulate the expression of their target genes through binding with certain target regions, particularly 3' suntranslated regions. They are involved in the pathogenesis of several kinds of cancers, such as glioblastoma. Several miRNAs, including miR-10b, miR-21, miR-17-92-cluster, and miR-93, have been up-regulated in glioblastoma cell lines and clinical samples. On the other hand, expression of miR-7, miR-29b, miR-32, miR-34, miR-181 family members, and a number of other miRNAs have been decreased in this type of cancer. In the current review, we explain the role of miRNAs in the pathogenesis of glioblastoma through providing a summary of studies that reported dysregulation of these epigenetic effectors in this kind of brain cancer.

MicroRNA-615 functions as a tumor suppressor in osteosarcoma through the suppression of HK2

At present, the regulatory mechanisms of various microRNAs (miRNAs/miRs) have been elucidated in human cancers including osteosarcoma (OS). This study mainly focused on the role of miR-615 in OS, which has not yet been reported. Ninety-two OS tissues and normal samples were used in this study. Human osteoblast hFOB1.19 cells and OS cell line HOS were utilized to detect the expression of miR-615. The expression of miR-615 and gene expression were assessed by RT-qPCR and western blot analysis. Transwell, MTT and luciferase reporter assays were used to investigate the regulatory mechanism of miR-615 in OS. The results revealed that miR-615 expression was reduced in OS tissues and cells, and was associated with poor clinical outcomes and prognosis in OS patients. In addition, overexpression of miR-615 restrained cell viability and metastasis in OS. Furthermore, hexokinase 2 (HK2) was confirmed as a direct target of miR-615. Upregulation of HK2 was detected in OS tissues. The upregulation of HK2 weakened the tumor-suppressive effect of miR-615 in OS. Moreover, miR-615 blocked epithelial-mesenchymal transition (EMT) and inactivated the PI3K/AKT pathway in OS. To conclude, miR-615 acts as a tumor suppressor in OS, thus miR-615 can be used as a target for OS treatment.

miR-615 Fine-Tunes Growth and Development and Has a Role in Cancer and in Neural Repair

MicroRNAs (miRNAs) are small noncoding RNAs that function as epigenetic modulators regulating almost any gene expression. Similarly, other noncoding RNAs, as well as epigenetic modifications, can regulate miRNAs. This reciprocal interaction forms a miRNA-epigenetic feedback loop, the deregulation of which affects physiological processes and contributes to a great diversity of diseases. In the present review, we focus on miR-615, a miRNA highly conserved across eutherian mammals. It is involved not only during embryogenesis in the regulation of growth and development, for instance during osteogenesis and angiogenesis, but also in the regulation of cell growth and the proliferation and migration of cells, acting as a tumor suppressor or tumor promoter. It therefore serves as a biomarker for several types of cancer, and recently has also been found to be involved in reparative processes and neural repair. In addition, we present the pleiad of functions in which miR-615 is involved, as well as their multiple target genes and the multiple regulatory molecules involved in its own expression. We do this by introducing in a comprehensible way the reported knowledge of their actions and interactions and proposing an integral view of its regulatory mechanisms.

Exosomal Transfer of lncRNA H19 Promotes Erlotinib Resistance in Non-Small Cell Lung Cancer via miR-615-3p/ATG7 Axis

Background

Drug resistance restrains the effect of drug therapy in non-small cell lung cancer (NSCLC). However, the mechanism of the acquisition of drug resistance remains largely unknown. This study aims to investigate the effect of exosomal lncRNA H19 on erlotinib resistance in NSCLC and the underlying mechanism.

Methods

HCC827 and A549 cells were continuously grafted into erlotinib-containing culture medium to establish erlotinib-resistant cell lines. The expression of H19 and miR-615-3p was detected by qRT-PCR. The protein levels of MMP2, MMP9, CD9, CD63 and ATG7 were measured by Western blot. Cell viability and proliferation were determined by Cell Counting Kit-8 (CCK-8) and 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay, respectively. Migration and invasion were assessed by transwell assay. Xenograft tumor models were used to investigate the effect of H19 on erlotinib resistance in vivo. Online software and dual-luciferase reporter assay were used to predicate the downstream targets and confirm the targeted relationships.

Results

H19 was upregulated in erlotinib-resistant cells, and knockdown of H19 inhibited cell proliferation, migration and invasion in erlotinib-resistant cells. Extracellular H19 can be packaged into exosomes. Exosomes containing H19 induced erlotinib resistance of sensitive cells, while knockdown of H19 abolished this effect. miR-615-3p was a target of H19 and can bind to ATG7. Exosomal H19 affected erlotinib resistance of erlotinib-resistant NSCLC cells via targeting miR-615-3p to regulate ATG7 expression. In addition, the serum exosomal H19 was upregulated in patients with erlotinib resistance. Furthermore, downregulated H19 decreased the resistance of tumor cells to erlotinib in vivo.

Conclusion

Our study demonstrated that exosomal H19 facilitated erlotinib resistance in NSCLC via miR-615-3p/ATG7 axis, which might provide a potential target for the diagnosis and treatment of NSCLC.

MiR-615 Regulates NSC Differentiation In Vitro and Contributes to Spinal Cord Injury Repair by Targeting LINGO-1

LINGO-1(LRR and Ig domain-containing NOGO receptor interacting protein 1) is a viable target for spinal cord injury (SCI) repair due to its potent negative regulation in neuron survival and axonal regeneration. Although promising, the intracellular mechanism underlying LINGO-1 regulation is unclear. Here, we identified miR-615 as a potential microRNA (miRNA) that directly targets LINGO-1 by binding its 3'-untranslated region (3'-UTR) and caused the translation inhibition of LINGO-1. MiR-615 negatively regulated LINGO-1 during neural stem cell (NSC) differentiation and facilitated its neuronal differentiation in vitro. Interestingly, compared to the control, neurons differentiated from miR-615-treated NSCs were immature with short processes. Further results showed LINGO-1/epidermal growth factor receptor (EGFR) signaling may be involved in this process, as blockade of EGFR using specific antagonist resulted in mature neurons with long processes. Furthermore, intrathecal administration of miR-615 agomir in SCI rats effectively knocked down LINGO-1, increased neuronal survival, enhanced axonal extension and myelination, and improved recovery of hindlimbs motor functions. This work thus uncovers miR-615 as an effective miRNA that regulates LINGO-1 in NSC and SCI animals, and suggests miR-615 as a potential therapeutic target for traumatic central nervous system (CNS) injury.

EGFRvIII: An Oncogene with Ambiguous Role

Epidermal growth factor receptor variant III (EGFR^vIII) seems to constitute the perfect therapeutic target for glioblastoma (GB), as it is specifically present on up to 28–30% of GB cells. In case of other tumor types, expression and possible role of this oncogene still remain controversial. In spite of EGFR^vIII mechanism of action being crucial for the design of small active anticancer molecules and immunotherapies, i.e., CAR-T technology, it is yet to be precisely defined. EGFR^vIII is known to be resistant to degradation, but it is still unclear whether it heterodimerizes with EGF-activated wild-type EGFR (EGFR^WT) or homodimerizes (including covalent homodimerization). Constitutive kinase activity of this mutated receptor is relatively low, and some researchers even claim that a nuclear, but not a membrane function, is crucial for its activity. Based on the analyses of recurrent tumors that are often lacking EGFR^vIII expression despite its initial presence in corresponding primary foci, this oncogene is suggested to play a marginal role during later stages of carcinogenesis, while even in primary tumors EGFR^vIII expression is detected only in a small percentage of tumor cells, undermining the rationality of EGFR^vIII-targeting therapies. On the other hand, EGFR^vIII-positive cells are resistant to apoptosis, more invasive, and characterized with enhanced proliferation rate. Moreover, expression of this oncogenic receptor was also postulated to be a marker of cancer stem cells. Opinions regarding the role that EGFR^vIII plays in tumorigenesis and for tumor aggressiveness are clearly contradictory and, therefore, it is crucial not only to determine its mechanism of action, but also to unambiguously define its role at early and advanced cancer stages.

Expression level of EGFR and MET receptors regulates invasiveness of melanoma cells

Epidermal and hepatocyte growth factors can stimulate invasive abilities of melanoma cells, while treatment with combination of their receptors' (EGFR and MET, respectively) inhibitors reduces viability of these cells, as we have previously shown. Proposed therapy has potential; however, used drugs block more than one goal effectively, what raises the question about the real target of analysed inhibitors. For this reason, we analysed direct involvement of these receptors in the invasion of melanoma cells inducing EGFR and MET up‐ and down‐regulations in examined cells. Results were acquired with assays evaluating cell migration and invasion (scratch wound assay, Transwell filter‐based method and single‐cell tracking). We revealed that cells' motile abilities are increased after EGFR overexpression and decreased following EGFR and MET silencing. This outcome correlates with elevated (EGFR up‐regulation) or reduced (EGFR/MET down‐regulation) number of formed invadopodia, visualized with immunofluorescence, and their rate of proteolytic abilities, evaluated by fluorescent gelatin degradation assay, and gelatin zymography, compared to control cells. Above‐mentioned data indicate that both—EGFR and MET signalling is directly connected with melanoma cells invasion, what establishes these receptors as promising targets for anti‐cancer treatment.