MiR-21 modulates radiosensitivity of cervical cancer through inhibiting autophagy via the PTEN/Akt/HIF-1α feedback loop and the Akt-mTOR signaling pathway

Reciprocal regulations between miRNAs and HIF-1α in human cancers

Hypoxia inducible factor-1α (HIF-1α) is a central molecule involved in mediating cellular processes. Alterations of HIF-1α and hypoxically regulated microRNAs (miRNAs) are correlated with patients' outcome in various cancers, indicating their crucial roles on cancer development. Recently, an increasing number of studies have revealed the intricate regulations between miRNAs and HIF-1α in modulating a wide variety of processes, including proliferation, metastasis, apoptosis, and drug resistance, etc. miRNAs are a class of small noncoding RNAs which function as negative regulators by directly targeting mRNAs. Evidence shows that miRNAs can be regulated by HIF-1α at transcriptional level. In turn, HIF-1α itself can be modulated by many miRNAs whose alterations have been implicated in tumorigenesis, thus forming a reciprocal regulation network. These findings add a new layer of complexity to our understanding of HIF-1α regulatory networks. Here, we will provide a comprehensive overview of the current advances about the bidirectional interactions between HIF-1α and miRNAs in human cancers. Besides, the review will summarize the roles of miRNAs/HIF-1α crosstalk according to various cellular processes. Finally, the potential values of miRNAs/HIF-1α loops in clinical applications are discussed.

Regulatory effects of lncRNAs and miRNAs on autophagy in malignant tumorigenesis

Autophagy is an important process in endogenous substrate degradation by lysosomes within cells, with a degree of evolutionary conservation. Like apoptosis and cell senescence, cell autophagy is a very important biological phenomenon involving the development and growth of biological processes. Abnormal autophagy may lead to tumorigenesis. In recent years, increasing studies have demonstrated that long non-coding RNAs (lncRNAs) and miRNAs can regulate cell autophagy by modulating targetting gene expression. In this review, we will provide an overview of lncRNAs and miRNAs in autophagy modulation and new insights into the underlying mechanisms, as well as their potential utilization in disease diagnosis, prognosis, and therapy.

Overview upon miR-21 in lung cancer: focus on NSCLC

Considering the high mortality rate encountered in lung cancer, there is a strong need to explore new biomarkers for early diagnosis and also improved therapeutic targets to overcome this issue. The implementation of microRNAs as important regulators in cancer and other pathologies expanded the possibilities of lung cancer management and not only. MiR-21 represents an intensively studied microRNA in many types of cancer, including non-small cell lung cancer (NSCLC). Its role as an oncogene is underlined in multiple studies reporting the upregulated expression of this sequence in patients diagnosed with this malignancy; moreover, several studies associated this increased expression of miR-21 with a worse outcome within NSCLC patients. The same pattern is supported by the data existent in the Cancer Genome Atlas (TCGA). The carcinogenic advantage generated by miR-21 in NSCLC resides in the target genes involved in multiple pathways such as cell growth and proliferation, angiogenesis, invasion and metastasis, but also chemo- and radioresistance. Therapeutic modulation of miR-21 by use of antisense sequences entrapped in different delivery systems has shown promising results in impairment of NSCLC. Hereby, we review the mechanisms of action of miR-21 in cancer and the associated changes upon tumor cells together a focused perspective on NSCLC signaling, prognosis and therapy.

Autophagy: A New Mechanism of Prosurvival and Drug Resistance in Multiple Myeloma

Autophagy is an intracellular self-degradative process that balances cell energy source and regulates tissue homeostasis. In physiological condition, autophagy funnels cytoplasmic constituents to autophagolysosomes for degradation and is an alternative way for cell-death behavior. Here, we inspected autophagy as a prosurvival mechanism essential for drug resistance in multiple myeloma (MM). Accordingly, autophagy inhibitors used in association to conventional anti-MM drugs might enforce the effect against resistant MM plasma cells and render autophagy a new therapeutic target.

Emerging Role of mTOR Signaling-Related miRNAs in Cardiovascular Diseases

Mechanistic/mammalian target of rapamycin (mTOR), an atypical serine/threonine kinase of the phosphoinositide 3-kinase- (PI3K-) related kinase family, elicits a vital role in diverse cellular processes, including cellular growth, proliferation, survival, protein synthesis, autophagy, and metabolism. In the cardiovascular system, the mTOR signaling pathway integrates both intracellular and extracellular signals and serves as a central regulator of both physiological and pathological processes. MicroRNAs (miRs), a class of short noncoding RNA, are an emerging intricate posttranscriptional modulator of critical gene expression for the development and maintenance of homeostasis across a wide array of tissues, including the cardiovascular system. Over the last decade, numerous studies have revealed an interplay between miRNAs and the mTOR signaling circuit in the different cardiovascular pathophysiology, like myocardial infarction, hypertrophy, fibrosis, heart failure, arrhythmia, inflammation, and atherosclerosis. In this review, we provide a comprehensive state of the current knowledge regarding the mechanisms of interactions between the mTOR signaling pathway and miRs. We have also highlighted the latest advances on mTOR-targeted therapy in clinical trials and the new perspective therapeutic strategies with mTOR-targeting miRs in cardiovascular diseases.

Ailanthone Promotes Human Vestibular Schwannoma Cell Apoptosis and Autophagy by Downregulation of miR-21

Ailanthone (AIL) is a quassinoid isolated from the traditional Chinese medicinal herb Ailanthus altissima. The antitumor activities of AIL have been reported in several cancers. The purpose of the present study was to explore the effect of AIL on vestibular schwannomas (VSs). Various concentrations of AIL (0-1 μM) were used to treat human primary VS cells, and then cell viability, proliferation, apoptosis, and autophagy were assessed. Expression of miR-21 in VS cells was altered by miRNA transfection. The functional actions of AIL on miR-21 dysregulated cells were also assessed. AIL significantly reduced the viability of VS cells, and the IC50 value was 0.48 ± 0.023 μM. In response to 0.6 μM AIL, BrdU+ cell rate and cyclin D1 expression were reduced, apoptotic cell rate was increased, caspase 3 and caspase 9 were cleaved, Beclin-1 and LC3-II were accumulated, and p62 was downregulated. miR-21 was lowly expressed in AIL-treated cells, and AIL-induced apoptosis and autophagy were attenuated by miR-21 overexpression. In addition, AIL downregulated Ras and Raf and deactivated MEK, ERK, mTOR, and p70S6K, while the downregulation and deactivation induced by AIL were reversed by miR-21 overexpression. To conclude, AIL inhibited VS cell proliferation and induced apoptosis and autophagy. The antitumor activities of AIL in VS cells were realized possibly via downregulation of miR-21 and blocking the Ras/Raf/MEK/ERK and mTOR pathways.

The role of HIF-1α in chemo-/radioresistant tumors

Chemo-/radioresistance is a major obstacle in clinical oncology. The precise failure mechanisms of chemo-/radioresistance are multifactorial failures. It is now widely accepted that a tumor hypoxia microenvironment contributes significantly to chemo-/radioresistance. Hypoxia is the most common and obvious neoplastic microenvironment and is due to the rapid proliferation of tumor cells. HIF-1α is a principal molecular mediator of adaptability to hypoxia in tumor cells. HIF-1α activation leads to the transcription of a plethora of target genes that promote physiological changes associated with chemo-/radioresistance, including increasing the ability of DNA repair, the inhibition of apoptosis, and alterations of the cellular metabolism. Moreover, recent findings suggest that HIF-1α-activated autophagy is a crucial factor in the promotion of cell survival under the distressed microenvironment, thereby leading to the chemo-/radioresistance. This chapter presents an overview of the role of HIF-1α in chemo-/radioresistance of tumor cells.

Exosome-mediated gefitinib resistance in lung cancer HCC827 cells via delivery of miR-21

Acquired resistance to gefitinib remains a major challenge in cancer treatment. In the present study, the effect of exosomes on the transmission of gefitinib resistance from gefitinib-resistant HCC827 lung cancer cells (H827R) to their gefitinib-sensitive counterparts and the potential underlying mechanisms by which this occurs was investigated. Exosomes were obtained from the cell supernatant using ultracentrifugation and the ExoQuick-TC exosome precipitation solution. Drug resistance was assessed by flow cytometry, apoptosis assays and cell counting kit-8 assays. The expression of microRNA (miR)-21 was analyzed by reverse transcription-quantitative polymerase chain reaction. Exosomes released by H827R cells (R/exo) may decrease the sensitivity of the human NSCLC HCC827 cell line to gefitinib. The results indicated that miR-21 expression was increased in R/exo and R/exo-treated H827S cells. However, miR-21 inhibition abrogated exosome-mediated drug resistance. Phosphorylated-protein kinase B (p-Akt), which is downstream of miR-21, was downregulated following gefitinib treatment; however, R/exo pretreatment elevated p-Akt levels and promoted the activation of Akt. By contrast, miR-21 inhibition reduced p-Akt expression. Therefore, the induction of miR-21 via exosomes and the activation of Akt may be mechanisms by which exosomes mediate the transfer of drug resistance.

Role of metabolism in cancer cell radioresistance and radiosensitization methods

BACKGROUND

Radioresistance is a major factor leading to the failure of radiotherapy and poor prognosis in tumor patients. Following the application of radiotherapy, the activity of various metabolic pathways considerably changes, which may result in the development of resistance to radiation.

MAIN BODY

Here, we discussed the relationships between radioresistance and mitochondrial and glucose metabolic pathways, aiming to elucidate the interplay between the tumor cell metabolism and radiotherapy resistance. In this review, we additionally summarized the potential therapeutic targets in the metabolic pathways.

SHORT CONCLUSION

The aim of this review was to provide a theoretical basis and relevant references, which may lead to the improvement of the sensitivity of radiotherapy and prolong the survival of cancer patients.

Time-course differential lncRNA and mRNA expressions in radioresistant hypopharyngeal cancer cells

Radioresistance remains a major problem in the treatment of patients with hypopharyngeal squamous cell carcinoma (HSCC). Long noncoding RNAs (lncRNAs) have important roles in the development, invasion, and metastasis of various tumors, including HSCC, but little is known about the role of lncRNAs in cancer radioresistance. The aim of this study was to identify radioresistance-related lncRNAs and mRNAs in radioresistant (RS) hypopharyngeal cancer subclone RS-FaDu cells. In this study, we performed microarray analysis to find the differences in time-course lncRNA and mRNA expression profiles between RS-FaDu and parent FaDu cells after 4 Gy radiation therapy, whose reliability was confirmed by validation experiment. Among these consistently dysregulated lncRNAs, we found that some lncRNAs (e.g., TCONS_00018436) might control resistance of HSCC cells to radiation. Furthermore, our bioinformatics analyses from mRNA/lncRNA microarray data showed that certain lncRNAs or mRNAs potentially are involved in radioresistance of HSCC. Our results from this study laid the foundation for further investigating the roles of these lncRNAs and mRNAs as promising candidates in the occurrence and development of HSCC radioresistance.

Pterostilbene increases PTEN expression through the targeted downregulation of microRNA-19a in hepatocellular carcinoma

Pterostilbene (Pter) is reported to exhibit an anticancer effect in hepatocellular carcinoma (HCC). In order to explore the anticancer mechanism in HCC cells, the present study aimed to investigate whether pterostilbene (Pter) may increase phosphatase and tensin homolog (PTEN) expression through targeted downregulation of microRNA (miRNA/miR)-19a in hepatocellular carcinoma (HCC). The proliferation, apoptosis and cell cycle was analyzed in the SMMC-7721 HCC cell line by MTT assays and flow cytometry methods. Cells were divided into five treatment groups: Pter treatment, miR-19a inhibitor transfection, Pter + miR-19a inhibitor, negative control transfection and blank control. The expression of miR-19a and PTEN was detected by reverse transcription-quantitative polymerase chain reaction and western blot analysis following treatment. Furthermore, a luciferase reporter gene assay was performed to determine whether the PTEN gene was a direct target of miR-19a. The results demonstrated that Pter treatment or miR-19a inhibitor transfection downregulated miR-19a and induced PTEN/Akt pathway regulation, which led to proliferation inhibition, cell cycle arrest in the S phase, increased apoptosis and reduced cell invasion. These results indicated that Pter may increase PTEN expression through the direct downregulation of miR-19a in HCC. Therefore, miR-19a may have potential as a novel molecular marker for HCC and Pter may be a promising clinical target with the potential to be developed as a HCC therapy.

miR‑328‑3p enhances the radiosensitivity of osteosarcoma and regulates apoptosis and cell viability via H2AX

Osteosarcoma is a kind of high-risk sarcoma of the skeleton typically observed in people under 25 years old. Currently, radiotherapy is widely applied in cancer treatment. However, osteosarcoma is radioresistant and accordingly new, more effective radiosensitizers are needed. miRNAs have been reported to play an important role in osteosarcoma radiosensitivity. We examined the modulating effect of miR-328-3p in vivo and in vitro. miR-328-3p was downregulated in HOS-2R cells. The overexpression of miR-328-3p enhanced the radiosensitivity of osteosarcoma cells. miR-328-3p inhibited proliferation and promoted apoptosis in osteosarcoma cells under radiation conditions. In cells overexpressing miR-328-3p, H2AX expression was downregulated. We found that miR-328-3p targets H2AX and inhibits its expression. It was concluded, that miR-328-3p enhances the radiosensitization of osteosarcoma following X-ray irradiation, and determined that it directly targets H2AX to regulate radiosensitization.

Radiation-Induced Changes of microRNA Expression Profiles in Radiosensitive and Radioresistant Leukemia Cell Lines with Different Levels of Chromosome Abnormalities

In our study, we estimate an effect from chromosome aberrations and genome mutations on changes in microRNA expression profiles in cancer cell lines demonstrating different radiosensitivity. Here, cell viability and microRNA spectrum have been estimated 1, 4, and 24 h after irradiation. MiSeq high-throughput sequencing system (Illumina, San Diego, CA, USA) is employed to perform microRNA spectrum estimation. In the K562 cell line, the number of expressed microRNAs in chromosomes demonstrates a more pronounced variation. An analysis of microRNA effects on signaling pathway activity demonstrates differences in post-transcriptional regulation of the expression of genes included into 40 signaling pathways. In the K562 cell line, microRNA dynamics analyzed for their dependence on chromosome localization show a wider scattering of microRNA expression values for a pair of chromosomes compared to the HL-60 cell line. An analysis of microRNAs expression in the K562 and HL-60 cell lines after irradiation has shown that chromosome abnormalities can affect microRNA expression changes. A study of radiation-induced changes of microRNA expression profiles in the K562 and HL-60 cell lines has revealed a dependence of microRNA expression changes on the number of chromosome aberrations and genome mutations.

Role of microRNA-21 in radiosensitivity in non-small cell lung cancer cells by targeting PDCD4 gene

This study aims to explore the effects of microRNA-21 (miR-21) on radiosensitivity in non-small cell lung cancer (NSCLC) by targeting programmed cell deanth 4 (PDCD4) and regulating PI3K/AKT/mTOR signaling pathway. Cancer tissues and adjacent normal tissues were collected from 97 NSCLC patients who received a standard radiotherapy regimen. TUNEL assay was applied to determine cell apoptosis in tissues. The qRT-PCR assay was used to detect the expressions of miR-21 expression and PDCD4 mRNA. The protein expressions of PDCD4 and PI3K/AKT/mTOR signaling pathway-related proteins were determined by Western blotting. Colony formation assay was used to observe the sensitivity to radiotherapy of NSCLC cells. Flow cytometry was adopted to testify cell apoptosis. Compared with adjacent normal tissues, miR-21 expression was significantly increased and the mRNA and protein expressions of PDCD4 were decreased in NSCLC tissues. Higher miR-21 expression was associated with attenuated radiation efficacy and shorter median survival time. PDCD4 was the target gene of miR-21. The miR-21 mimics and siRNA-PDCD4 decreased the sensitivity to radiotherapy and cell apoptosis of A549 and H1299 cells and activated PI3K/AKT/mTOR pathway. The sensitivity of A549 and H1299 cells was strengthened in the miR-21 inhibitors group and the PI3K/AKT/mTOR inhibitors group. The siRNA-PDCD4 could reverse the effects of miR-21 inhibitors on sensitivity to radiotherapy and cell apoptosis of NSCLC cells. Our findings provide strong evidence that miR-21 could inhibit PDCD4 expression and activate PI3K/AKT/mTOR signaling pathway, thereby affecting the radiation sensitivity of NSCLC cells.

miR-144 may regulate the proliferation, migration and invasion of trophoblastic cells through targeting PTEN in preeclampsia

Previous studies indicated that microRNAs (miRNAs) were aberrantly expressed in the placentas of patients with Preeclampsia (PE); however, the underlying mechanism still requires further investigation. The aim of this study is to investigate the roles of miR-144 in preeclampsia and the related mechanism. The expression of miR-144 and PTEN in 30 placentas of patients with PE and 30 normal placentas was compared; next, HTR8/SVneo cells were transfected with miR-144 mimics and miR-144 inhibitors and cultured for 48h, and the proliferation and apoptosis, cell migration and invasion of the cells were examined; furthermore, the expression PTEN, Caspase-3 and Bcl-2 was examined; next, dual luciferase reporter assay has been performed to confirm that PTEN is a direct target of miR-144; finally, HTR-8/SVneo cells were transfected with either PTEN overexpression plasmid or PTEN RNAi to determine whether knockdown or overexpression of PTEN can mimic the effect of miR-144 We have observed that the expression of miR-144 was significantly decreased and the expression of PTEN was markedly increased in placentas of patients with PE compared with normal placentas; moreover, transfection of miR-144 mimics in trophoblastic cells induced significant increase in cell proliferation, migration, invasion, and decrease in cell apoptosis, and also affected the cell cycles; on the other hand, transfection of miR-144 inhibitors has shown the opposite effects; furthermore, transient overexpression of miR-144 induced marked decrease in the expression of PTEN, Caspase-3 and increase in expression of Bcl-2 (P<0.01), while transfection of miR-144 inhibitors showed the opposite effects; finally, PTEN has been confirmed as a direct target of miR-144; finally, transfection of PTEN overexpression plasmid or PTEN RNAi can mimic the results of miR-144 inhibitor or miR-144 mimics, respectively. In conclusion, miR-144 was down-regulated in PE, and miR-144 may play important roles in the pathogenesis of PE through targeting PTEN in trophoblastic cells. These results suggested that miR-144 has the potential to become a therapeutic target for the treatment of PE.

Regulatory effects of COL1A1 on apoptosis induced by radiation in cervical cancer cells

Background

Cervical cancer is a common cancer of women in developing countries, and radiotherapy still remains its predominant therapeutic treatment. Collagen type I alpha 1 (COL1A1) has been shown to have a radioresistance effect in previous studies. However, such effect of COL1A1 has not yet been revealed in cervical cancer.

Methods

Expression of COL1A1 in cervical cancer tissues and normal tissues was assessed by qRT-PCR and immunohistochemistry. The effect of COL1A1 on radioresistance of human cervical cancer cell lines HeLa and CaSki was assessed using the colony formation assay. Apoptosis alterations were analyzed by flow cytometry. In addition, western blotting was used assessed the alterations of several critical apoptosis and signaling pathway related proteins.

Results

The expression of COL1A1 was significantly increased in cervical cancer tissues compared with normal tissues at the mRNA and protein level. Further, based on COL1A1 knock down and COL1A1 activation cell models, a negative correlation was observed between COL1A1 expression level and radiosensitivity. Moreover, the findings are further supported by apoptosis analysis that COL1A1 activation could inhibit the apoptosis of cervical cancer cells. Subsequently, a significantly decreased expression of p-AKT and Bcl-2, increased expression of Caspase-3 were observed in the LY294002 plus radiation group compared with radiation alone group, while these influences caused by LY294002 or X-ray radiation were reversed after COL1A1 activation.

Conclusions

To our knowledge, this is the only study to profile the mechanisms that COL1A1 plays a crucial role in cervical cells anti-apoptosis induced by radiation. Therefore, our identification of radioresistance-related COL1A1 in cervical cancer could be a starting point to explore the function of collagens, adding a new dimension to our understanding of the cervical cancer, assisting cancer biologists and clinical oncologists in novel therapeutic strategies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12935-017-0443-5) contains supplementary material, which is available to authorized users.

Regulation of Autophagy by MiRNAs and Their Emerging Roles in Tumorigenesis and Cancer Treatment

Autophagy is a conserved catabolic process for the degradation and recycling of cytosolic components or organelles through a lysosome-dependent pathway. Autophagy can be induced in response to multiple stress conditions, such as nutrient deprivation, hypoxia, energy depletion, etc. As a result, autophagy can regulate many biological processes, including cell survival, metabolism, differentiation, senescence, and cell death. MicroRNAs (MiRNAs) are small noncoding molecules that regulate gene expression by silencing mRNA targets. MiRNA dysregulation exhibits great regulatory potential during organismal development, hematopoiesis, immunity, cell proliferation and death, and autophagy. Recently, increasing studies have linked MiRNAs to autophagic regulation during cancer initiation and development. Although the relationship between MiRNAs and autophagy is quite complicated and has not been well elucidated, MiRNAs may underlie key aspects of autophagy and cancer biology. Increasing evidence shows that MiRNAs play important roles as both oncogenic MiRNAs and tumor suppressive MiRNAs in cancer initiation and development. Thus, understanding the novel relationship between MiRNAs and autophagy may allow us to develop promising cancer biomarkers and therapeutic targets.

miR-138 suppresses the proliferation, metastasis and autophagy of non-small cell lung cancer by targeting Sirt1

The present study determined the role and mechanism of miR-138 in non-small cell lung cancer (NSCLC). In total, 45 freshly resected clinical NSCLC tissues were collected. The expression of miR-138 in tissues and cell lines were determined by real-time quantitative PCR. miR-138 mimics were transfected into A549 and Calu-3 cells in vitro, and then the effects of miR-138 on lung cancer cell proliferation, cell cycle, invasion and metastasis were investigated by CCK-8 assay, Transwell and flow cytometry, respectively. The protein expression of the potential target gene Sirt1 in lung cancer cells were determined by western blot analysis. Dual-Luciferase reporter assay was performed to further confirm whether Sirt1 was the target gene of miR-138. The expression of miR-138 was significantly lower in lung cancer tissues and was negatively correlated to the differentiation degree and lymph node metastasis of lung cancer. In vitro experiment results showed that miR-138 inhibited lung cancer cell proliferation, invasion and migration. It was verified that miR-138 could downregulate Sirt1 protein expression, inhibit epithelial-mesenchymal transition (EMT), decrease the activity of AMPK signaling pathway and elevate mTOR phosphorylation level. Dual-Luciferase reporter assay demonstrated that miR-138 could directly regulate Sirt1. Downregulation of Sirt1 alone can also cause the same molecular and biological function changes. Western blot analysis and confocal microscopy results indicated that overexpression of miR-138 or interference of Sirt1 expression could inhibit lung cancer cell autophagy activity possibly through AMPK-mTOR signaling pathway. miR-138 plays a tumor suppressor function in lung cancer. It may inhibit the proliferation, invasion and migration of lung cancer through downregulation of Sirt1 expression and activation of cell autophagy. The downregulation of miR-138 is closely related to the development of lung cancer.

Autophagy-Regulating microRNAs and Cancer

Macroautophagy (autophagy herein) is a cellular stress response and a survival pathway that is responsible for the degradation of long-lived proteins, protein aggregates, as well as damaged organelles in order to maintain cellular homeostasis. Consequently, abnormalities of autophagy are associated with a number of diseases, including Alzheimers’s disease, Parkinson’s disease, and cancer. According to the current view, autophagy seems to serve as a tumor suppressor in the early phases of cancer formation, yet in later phases, autophagy may support and/or facilitate tumor growth, spread, and contribute to treatment resistance. Therefore, autophagy is considered as a stage-dependent dual player in cancer. microRNAs (miRNAs) are endogenous non-coding small RNAs that negatively regulate gene expression at a post-transcriptional level. miRNAs control several fundamental biological processes, and autophagy is no exception. Furthermore, accumulating data in the literature indicate that dysregulation of miRNA expression contribute to the mechanisms of cancer formation, invasion, metastasis, and affect responses to chemotherapy or radiotherapy. Therefore, considering the importance of autophagy for cancer biology, study of autophagy-regulating miRNA in cancer will allow a better understanding of malignancies and lead to the development of novel disease markers and therapeutic strategies. The potential to provide study of some of these cancer-related miRNAs were also implicated in autophagy regulation. In this review, we will focus on autophagy, miRNA, and cancer connection, and discuss its implications for cancer biology and cancer treatment.

Inhibition of Beclin-1-Mediated Autophagy by MicroRNA-17-5p Enhanced the Radiosensitivity of Glioma Cells

The role of miRNAs in the radiosensitivity of glioma cells and the underlying mechanism is still far from clear. In the present study, we detected six downregulated and seven upregulated miRNAs in the serum after radiotherapy compared with paired serum samples before radiotherapy via miRNA panel PCR. Among these, miR-17-5p was highly reduced (fold change = −4.21). Further, we validated the levels of miR-17-5p in all serum samples with qRT-PCR. In addition, statistical analysis suggested that a reduced miR-17-5P level was positively associated with advanced clinical stage of glioma, incidence of relapse, and tumor differentiation. Moreover, we provided evidence that irradiation markedly activated autophagy and decreased miR-17-5p in the glioma cell line. Further, we demonstrated that irradiation-induced autophagy activation was mediated by beclin-1, and downregulation of beclin-1 via siRNA significantly abolished the irradiation-activated autophagy. Interestingly, we demonstrated that miR-17-5p could directly target beclin-1 via luciferase gene reporter assay. Exotic expression of miRNA-17-5p decreased autophagy activity in vitro. In nude mice, miRNA-17-5p upregulation sensitized the xenograft tumor to irradiation and suppressed irradiation-induced autophagy. Finally, pharmacal inhibition of autophagy markedly enhanced the cytotoxicity of irradiation in RR-U87 cells.

Clarifying the molecular mechanism associated with carfilzomib resistance in human multiple myeloma using microarray gene expression profile and genetic interaction network

Carfilzomib is a Food and Drug Administration-approved selective proteasome inhibitor for patients with multiple myeloma (MM). However, recent studies indicate that MM cells still develop resistance to carfilzomib, and the molecular mechanisms associated with carfilzomib resistance have not been studied in detail. In this study, to better understand its potential resistant effect and its underlying mechanisms in MM, microarray gene expression profile associated with carfilzomib-resistant KMS-11 and its parental cell line was downloaded from Gene Expression Omnibus database. Raw fluorescent signals were normalized and differently expressed genes were identified using Significance Analysis of Microarrays method. Genetic interaction network was expanded using String, a biomolecular interaction network JAVA platform. Meanwhile, molecular function, biological process and signaling pathway enrichment analysis were performed based on Gene Ontology and Kyoto Encyclopedia of Genes and Genomes. Totally, 27 upregulated and 36 downregulated genes were identified and a genetic interaction network associated with the resistant effect was expanded basing on String, which consisted of 100 nodes and 249 edges. In addition, signaling pathway enrichment analysis indicated that cytokine–cytokine receptor interaction, autophagy, ErbB signaling pathway, microRNAs in cancer and fatty acid metabolism pathways were aberrant in carfilzomib-resistant KMS-11 cells. Thus, in this study, we demonstrated that carfilzomib potentially conferred drug resistance to KMS-11 cells by cytokine–cytokine receptor interaction, autophagy, ErbB signaling pathway, microRNAs in cancer and fatty acid metabolism pathways, which may provide some potential molecular therapeutic targets for drug combination therapy against carfilzomib resistance.