Autophagy-regulating microRNAs: potential targets for improving radiotherapy

Critical role of the long non-coding RNAs (lncRNAs) in radiotherapy (RT)-resistance of gastrointestinal (GI) cancer: Is there a way to defeat this resistance?

Radiotherapy (RT) is a frequently used treatment for cervical cancer, effectively decreasing the likelihood of the disease returning in the same area and extending the lifespan of individuals with cervical cancer. Nevertheless, the primary reason for treatment failure in cancer patients is the cancer cells' resistance to radiation therapy (RT). Long non-coding RNAs (LncRNAs) are a subset of RNA molecules that do not code for proteins and are longer than 200 nucleotides. They have a significant impact on the regulation of gastrointestinal (GI) cancers biological processes. Recent research has shown that lncRNAs have a significant impact in controlling the responsiveness of GI cancer to radiation. This review provides a concise overview of the composition and operation of lncRNAs as well as the intricate molecular process behind radiosensitivity in GI cancer. Additionally, it compiles a comprehensive list of lncRNAs that are linked to radiosensitivity in such cancers. Furthermore, it delves into the potential practical implementation of these lncRNAs in modulating radiosensitivity in GI cancer.

Decoding the interaction between miR-19a and CBX7 focusing on the implications for tumor suppression in cancer therapy

Cancer is a complex and multifaceted disease characterized by uncontrolled cell growth, genetic alterations, and disruption of normal cellular processes, leading to the formation of malignant tumors with potentially devastating consequences for patients. Molecular research is important in the diagnosis and treatment, one of the molecular mechanisms involved in various cancers is the fluctuation of gene expression. Non-coding RNAs, especially microRNAs, are involved in different stages of cancer. MicroRNAs are small RNA molecules that are naturally produced within cells and bind to the 3'-UTR of target mRNA, repressing gene expression by regulating translation. Overexpression of miR-19a has been reported in human malignancies. Upregulation of miR-19a as a member of the miR-17-92 cluster is key to tumor formation, cell proliferation, survival, invasion, metastasis, and drug resistance. Furthermore. bioinformatics and in vitro data reveal that the miR-19a-3p isoform binds to the 3'UTR of CBX7 and was identified as the miR-19a-3p target gene. CBX7 is known as a tumor suppressor. This review initially describes the regulation of mir-19a in multiple cancers. Accordingly, the roles of miR-19 in affecting its target gene expression CBX7 in carcinoma also be discussed.

Non-coding RNAs in radiotherapy resistance: Roles and therapeutic implications in gastrointestinal cancer

Radiotherapy has become an indispensable and conventional means for patients with advanced solid tumors including gastrointestinal cancer. However, innate or acquired radiotherapy resistance remains a significant challenge and greatly limits the therapeutic effect, which results in cancer relapse and poor prognosis. Therefore, it is an urgent need to identify novel biomarkers and therapeutic targets for clarify the biological characteristics and mechanism of radiotherapy resistance. Recently, lots of studies have revealed that non-coding RNAs (ncRNAs) are the potential indicators and regulators of radiotherapy resistance via the mediation of various targets/pathways in different cancers. These findings may serve as a potential therapeutic strategy to overcome radiotherapy resistance. In this review, we will shed light on the recent findings regarding the functions and regulatory mechanisms of ncRNAs following radiotherapy, and comprehensively discuss their potential as biomarkers and therapeutic targets in radiotherapy resistance of gastrointestinal cancer.

Multifaceted roles of aerobic glycolysis and oxidative phosphorylation in hepatocellular carcinoma

Liver cancer is a common malignancy with high morbidity and mortality rates. Changes in liver metabolism are key factors in the development of primary hepatic carcinoma, and mitochondrial dysfunction is closely related to the occurrence and development of tumours. Accordingly, the study of the metabolic mechanism of mitochondria in primary hepatic carcinomas has gained increasing attention. A growing body of research suggests that defects in mitochondrial respiration are not generally responsible for aerobic glycolysis, nor are they typically selected during tumour evolution. Conversely, the dysfunction of mitochondrial oxidative phosphorylation (OXPHOS) may promote the proliferation, metastasis, and invasion of primary hepatic carcinoma. This review presents the current paradigm of the roles of aerobic glycolysis and OXPHOS in the occurrence and development of hepatocellular carcinoma (HCC). Mitochondrial OXPHOS and cytoplasmic glycolysis cooperate to maintain the energy balance in HCC cells. Our study provides evidence for the targeting of mitochondrial metabolism as a potential therapy for HCC.

MiR-19a suppresses ferroptosis of colorectal cancer cells by targeting IREB2

Colorectal cancer (CRC) is the most common malignant tumor occurred in digestive system. However, the prognosis of CRC patients is poor. Therefore, it is urgent to illuminate the mechanism suppressing CRC and explore novel targets or therapies for CRC treatment. MicroRNAs (miRNAs) are a class of non-coding RNAs with a length of 20–23 nucleotides encoded by endogenous genes, which are associated with the development of a variety of cancers, including CRC. Studies have shown that miR-19a is identified as oncogenic miRNA and promotes the proliferation, migration and invasion of CRC cells. However, the relationship between miR-19a and ferroptosis in CRC remains unknown. Here, we reported that iron-responsive element-binding protein 2 (IREB2), as an inducer of ferroptosis, was negatively regulated by miR-19a. IREB2 is a direct target of miR-19a. In addition, ferroptosis was suppressed by miR-19a through inhibiting IREB2. Thus, we proposed a novel mechanism of ferroptosis mediated by miR-19a in CRC cells, which could give rise to a new strategy for the therapy of CRC.

Engineering Nanoplatform for Combined Cancer Therapeutics via Complementary Autophagy Inhibition

Despite advances in the development of tumor treatments, mortality from cancer continues to increase. Nanotechnology is expected to provide an innovative anti-cancer therapy, to combat challenges such as multidrug resistance and tumor recurrence. Nevertheless, tumors can greatly rely on autophagy as an alternative source for metabolites, and which desensitizes cancer cells to therapeutic stress, hindering the success of any current treatment paradigm. Autophagy is a conserved process by which cells turn over their own constituents to maintain cellular homeostasis. The multistep autophagic pathway provides potentially druggable targets to inhibit pro-survival autophagy under various therapeutic stimuli. In this review, we focus on autophagy inhibition based on functional nanoplatforms, which may be a potential strategy to increase therapeutic sensitivity in combinational cancer therapies, including chemotherapy, radiotherapy, phototherapy, sonodynamic therapy, and immunotherapy.

The Combination of Radiotherapy With Immunotherapy and Potential Predictive Biomarkers for Treatment of Non-Small Cell Lung Cancer Patients

Radiotherapy is an effective local treatment modality of NSCLC. Its capabilities of eliminating tumor cells by inducing double strand DNA (dsDNA) damage and modulating anti-tumor immune response in irradiated and nonirradiated sites have been elucidated. The novel ICIs therapy has brought hope to patients resistant to traditional treatment methods, including radiotherapy. The integration of radiotherapy with immunotherapy has shown improved efficacy to control tumor progression and prolong survival in NSCLC. In this context, biomarkers that help choose the most effective treatment modality for individuals and avoid unnecessary toxicities caused by ineffective treatment are urgently needed. This article summarized the effects of radiation in the tumor immune microenvironment and the mechanisms involved. Outcomes of multiple clinical trials investigating immuno-radiotherapy were also discussed here. Furthermore, we outlined the emerging biomarkers for the efficacy of PD-1/PD-L1 blockades and radiation therapy and discussed their predictive value in NSCLC.

Immunogenic Cell Death Induction by Ionizing Radiation

Immunogenic cell death (ICD) is a form of regulated cell death (RCD) induced by various stresses and produces antitumor immunity via damage-associated molecular patterns (DAMPs) release or exposure, mainly including high mobility group box 1 (HMGB1), calreticulin (CRT), adenosine triphosphate (ATP), and heat shock proteins (HSPs). Emerging evidence has suggested that ionizing radiation (IR) can induce ICD, and the dose, type, and fractionation of irradiation influence the induction of ICD. At present, IR-induced ICD is mainly verified in vitro in mice and there is few clinical evidence about it. To boost the induction of ICD by IR, some strategies have shown synergy with IR to enhance antitumor immune response, such as hyperthermia, nanoparticles, and chemotherapy. In this review, we focus on the molecular mechanisms of ICD, ICD-promoting factors associated with irradiation, the clinical evidence of ICD, and immunogenic forms of cell death. Finally, we summarize various methods of improving ICD induced by IR.

Graphene Oxide Biosensors Based on Hybridization Chain Reaction Signal Amplification for Detecting Biomarkers of Radiation-Resistant Nasopharyngeal Carcinoma and Imaging in Living Cells

Since microRNA-205 (miRNA-205) is a predictive biomarker for antiradiation of nasopharyngeal carcinoma (NPC), quantitative detection of miRNA-205 is important for developing personalized strategies for the treatment of NPC. In this investigation, based on the graphene oxide (GO) sensor and hybridization chain reaction (HCR) for fluorescence signal amplification, a highly sensitive and selective detection method for miRNA-205 was designed. A target-recycling mechanism is employed, where a single miRNA-205 target triggers the signal amplification of many DNA signal probes. The biosensor shows the ability to analyze miRNA-205 in solution, and it can detect miRNA-205 at concentrations as low as 311.96 pM. Furthermore, the method is specific in that it distinguishes between a target miRNA and a sequence with single-, double-, and three-base mismatches, as well as other miRNAs. Considering its simplicity and superior sensitivity, it was also verified in 1‰ serum with a detection limit of 111.65 pM. Importantly, the method successfully demonstrated that miRNA-205 could be imaged in living cells, which provided the possibility of localizing target molecules in live cell imaging applications. This method has great clinical application potential in the determination of miRNA-205, a biomarker for radiation-resistant NPC.

Crucial Roles of microRNA-Mediated Autophagy in Urologic Malignancies

Urologic oncologies are major public health problems worldwide. Both microRNA and autophagy, separately or concurrently, are involved in a variety of the cellular and molecular processes of multiple cancers, including urologic malignancies. In this review, we have summarized the related studies and found that microRNA-mediated autophagy acted as carcinogenic factors or suppressors in prostate cancer, kidney cancer, and bladder cancer. MiRNAs, targeted genes, and the different signaling pathways constitute a complex network that orchestrates autophagy regulation, militating the oncogenic and tumor-suppressive effects in urologic malignancies. Aberrant expression of miRNAs may induce the dysregulation of the autophagy process, resulting in tumorigenesis, progression, and resistance to anticancer therapies. Targeting specific miRNAs for autophagy modulation may present as reliable diagnostic and prognostic biomarkers or promising therapeutic strategies for urologic oncologies.

Investigation of miR-93-5p and its effect on the radiosensitivity of breast cancer

Accumulating evidence suggests that intrinsic resistance to radiotherapy reduces the survival of patients with cancer. The present study investigated whether miR-93-5p affects proliferation, migration, apoptosis, and radiosensitivity of breast cancer (BC) cells. MDA-MB-468, MCF-7, and MDA-MB-231 BC cells were incubated with hsa-miR-93-5p mimics, hsa-miR-93-5p inhibitor, and negative control RNA with or without exposure to ionizing radiation to determine cell proliferation, migration, and apoptosis using the Cell Counting Kit-8 assay, wound healing assay and apoptotic assay, respectively. Overexpression of miR-93-5p inhibited the migratory abilities (P = 0.001) and decreased the cell proliferation (P = 0.049) of MCF-7 cells. In MCF-7 cells, a significant increase in apoptosis was detected after treatment with miR-93-5p compared with the negative control (P = 0.001) and miR-93-5p inhibitor (P = 0.004). In MDA-MB-468 cells, the proportion of apoptotic cells increased following exposure to ionizing radiation (P = 0.001). The percentage of apoptotic MDA-MB-231 cells in the miR-93-5p group was significantly increase compared with that determined in the negative control (P = 0.044) and hsa-miR-93-5p inhibitor (P = 0.046) groups. In conclusion, our findings showed that miR-93-5p reduces BC cell proliferation and migratory capacity, and increases the ratio of apoptotic cells. Overexpression of miR-93-5p could increase radiosensitivity in BC cells by increasing apoptosis. This evidence provides new insight into the treatment of BC and identifies miR-93-5p as a potential therapeutic target.

Radiosensitizing effects of curcumin alone or combined with GLUT1 siRNA on laryngeal carcinoma cells through AMPK pathway-induced autophagy

In this study, we investigated the ability of curcumin alone or in combination with GLUT1 siRNA to radiosensitize laryngeal carcinoma (LC) through the induction of autophagy. Protein levels in tumour tissues and LC cells were measured by immunohistochemistry and Western blotting. In vitro, cell proliferation, colony formation assays, cell death and autophagy were detected. A nude mouse xenograft model was established through the injection of Tu212 cells. We found that GLUT1 was highly expressed and negatively associated with autophagy-related proteins in LC and that curcumin suppressed radiation-mediated GLUT1 overexpression in Tu212 cells. Treatment with curcumin, GLUT1 siRNA, or the combination of the two promoted autophagy. Inhibition of autophagy using 6-amino-3-methypourine (3-MA) promoted apoptosis after irradiation or treatment of cells with curcumin and GLUT1 siRNA. 3-MA inhibited curcumin and GLUT1 siRNA-mediated non-apoptotic programmed cell death. The combination of curcumin, GLUT1 siRNA and 3-MA provided the strongest sensitization in vivo. We also found that autophagy induction after curcumin or GLUT1 siRNA treatment implicated in the AMP-activated protein kinase-mTOR-serine/threonine-protein kinase-Beclin1 signalling pathway. Irradiation primarily caused apoptosis, and when combined with curcumin and GLUT1 siRNA treatment, the increased radiosensitivity of LC occurred through the concurrent induction of apoptosis and autophagy.

MicroRNA: a novel implication for damage and protection against ionizing radiation

Ionizing radiation (IR) is a form of high energy. It poses a serious threat to organisms, but radiotherapy is a key therapeutic strategy for various cancers. It is significant to reduce radiation injury but maximize the effect of radiotherapy. MicroRNAs (miRNAs) are posttranscriptionally regulatory factors involved in cellular radioresponse. In this review, we show how miRNAs regulate important genes on cellular response to IR-induced damage and how miRNAs participate in IR-induced carcinogenesis. Additionally, we summarize the experimental and clinical evidence for miRNA involvement in radiotherapy and discuss their potential for improvement of radiotherapy. Finally, we highlight the role that miRNAs play in accident exposure to IR or radiotherapy as predictive biomarker. miRNA therapeutics have shown great perspective in radiobiology; miRNA may become a novel strategy for damage and protection against IR.

Knockdown of lncRNA X inactive specific transcript (XIST) radiosensitizes non-small cell lung cancer (NSCLC) cells through regulation of miR-16-5p/WEE1 G2 checkpoint kinase (WEE1) axis

Long non-coding RNA (lncRNA) X inactive specific transcript (XIST) is reported to play an oncogenic role in non-small cell lung cancer (NSCLC). However, the role of XIST in regulating the radiosensitivity of NSCLC cells remains unclear. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect the expressions of XIST and miR-16-5p in NSCLC in tissues and cells, and Western blot was used to assess the expression of WEE1 G2 checkpoint kinase (WEE1). Cell counting kit-8 (CCK-8), colony formation and flow cytometry assays were used to determine cell viability and apoptosis after NSCLC cells were exposed to different doses of X-rays. The interaction between XIST and miR-16-5p was confirmed by StarBase database, qRT-PCR and dual-luciferase reporter gene assays. TargetScan database was used to predict WEE1 as a target of miR-16-5p, and their targeting relationship was further validated by Western blot, qRT-PCR and dual-luciferase reporter gene assays. XIST was highly expressed in both NSCLC tissue and cell lines, and knockdown of XIST repressed NSCLC cell viability and cell survival, and facilitated apoptosis under the irradiation. MiR-16-5p was a target of XIST, and rescue experiments demonstrated that miR-16-5p inhibitors could reverse the role of XIST knockdown on radiosensitivity in NSCLC cells. WEE1 was validated as a target gene of miR-16-5p, and WEE1 could be negatively regulated by XIST. XIST promotes the radioresistance of NSCLC cells by regulating the expressions of miR-16-5p and WEE1, which can be a novel target for NSCLC therapy.

MiR-137 promotes anoikis through modulating the AKT signaling pathways in Pancreatic Cancer

Anoikis resistance is a fundamental feature of the survival of metastatic cancer cells during cancer progression. However, the mechanisms underlying anoikis resistance in pancreatic cancer (PC) are still unclear. MicroRNA-137 (miR-137) is a tumor suppressor that inhibits the proliferation and invasion of cancer cells through targeting multiple oncogenes. However, the effects and molecular mechanism of miR-137 on anoikis of PC are still unclear. Here we demonstrated that miR-137 was downregulated after the induction of anoikis model in time dependent. Function assays revealed that miR-137 promoted the pancreatic cancer cells anoikis in vitro and vivo. According to bioinformation analysis of clinical databases, we predicted that paxillin (PXN) was a target of miR-137. Further, TCGA analysis revealed that PXN was closely associated with the development of PC. Through loss-of-function studies, we demonstrated that PXN was a functional target of miR-137 on anoikis of PC cells. Moreover, we found that PXN promoted the activation of the AKT signaling pathways which was involving in the cancer cells anoikis. Together, our findings reveal that miR-137 plays a novel role during anoikis and may serve as a potential target for the detection and treatment of PC.

MIR106A-5p upregulation suppresses autophagy and accelerates malignant phenotype in nasopharyngeal carcinoma

Dysregulated microRNAs (miRNAs) are involved in carcinoma progression, metastasis, and poor prognosis. We demonstrated that in nasopharyngeal carcinoma (NPC), transactivated MIR106A-5p promotes a malignant phenotype by functioning as a macroautophagy/autophagy suppressor by targeting BTG3 (BTG anti-proliferation factor 3) and activating autophagy-regulating MAPK signaling. MIR106A-5p expression was markedly increased in NPC cases based on quantitative real-time PCR, miRNA microarray, and TCGA database analysis findings. Moreover, MIR106A-5p was correlated with advanced stage, recurrence, and poor clinical outcomes in NPC patients. In addition to three-dimensional cell culture assays, zebrafish and BALB/c mouse tumor models revealed that overexpressed MIR106A-5p targeted BTG3 and accelerated the NPC malignant phenotype by inhibiting autophagy. BTG3 promoted autophagy, and its expression was correlated with poor prognosis in NPC. Attenuation of autophagy, mediated by the MIR106A-5p-BTG3 axis, occurred because of MAPK pathway activation. MIR106A-5p overexpression in NPC was due to increased transactivation by EGR1 and SOX9. Our findings may lead to novel insights into the pathogenesis of NPC.

Abbreviations: ACTB: actin beta; ATG: autophagy-related; ATG5: autophagy related 5; BLI: bioluminescence; BTG3: BTG anti-proliferation factor 3; CASP3: caspase 3; ChIP: chromatin immunoprecipitation; CQ: chloroquine; Ct: threshold cycle; DAPI: 4ʹ,6-diamidino-2-phenylindole; DiL: 1,1ʹ-dioctadecyl-3,3,3ʹ,3ʹ-tetramethylindocarbocyanine perchlorate; EBSS: Earle’s balanced salt solution; EGR1: early growth response 1; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GEO: Gene Expression Omnibus; GFP: green fluorescent protein; IF: immunofluorescence; IHC: immunohistochemistry; ISH: in situ hybridization; MAP1LC3B: microtubule associated protein 1 light chain 3 beta; MIR106A-5p: microRNA 106a-5p; miRNAs: microRNAs; MKI67: marker of proliferation ki-67; mRNA: messenger RNA; MTOR: mechanistic target of rapamycin kinase; NPC: nasopharyngeal carcinoma; qRT-PCR: quantitative real-time PCR; siRNA: small interfering RNA; SOX9: SRY-box transcription factor 9; SQSTM1: sequestosome 1; TCGA: The Cancer Genome Atlas; WB: western blot.

Effect of combination of curcumin and GLUT-1 AS-ODN on radiosensitivity of laryngeal carcinoma through regulating autophagy

BACKGROUND

This study is to explore the role of curcumin and GLUT-1 antisense oligodeoxynucleotides (AS-ODN) on autophagy modulation-initiated radiosensitivity.

METHODS

BALB/c mice were employed to establish xenograft model using Tu212 cell. The expression of autophagy- and apoptosis-related proteins was determined by WB. Autophagosome was observed under transmission electron microscope. Apoptosis of tumor tissue were detected by TUNEL staining.

RESULTS

Combinations of curcumin and GLUT-1 AS-ODN with 10 Gy inhibited the tumor growth by inducing apoptosis of laryngeal cancer cells followed with the enhancement of autophagy. 3-MA also had a promotion effect on irradiation-mediated growth inhibition possibly by depressing PI3K and on curcumin/GLUT-1 AS-ODN-mediated growth inhibition potentially by regulating autophagic events. Of note, a de-escalation of radiotherapy dose (5 Gy) along with curcumin, GLUT-1 AS-ODN or 3-MA produced a stronger effect than high dosage of radiotherapy (10 Gy) alone.

CONCLUSIONS

Curcumin and GLUT-1 AS-ODN improve the radiosensitivity of laryngeal carcinoma through regulating autophagy and inducing apoptosis.

MicroRNAs play an essential role in autophagy regulation in various disease phenotypes

Autophagy is a highly conserved catabolic process and fundamental biological process in eukaryotic cells. It recycles intracellular components to provide nutrients during starvation and maintains quality control of organelles and proteins. In addition, autophagy is a well-organized homeostatic cellular process that is responsible for the removal of damaged organelles and intracellular pathogens. Moreover, it also modulates the innate and adaptive immune systems. Micro ribonucleic acids (microRNAs) are a mature class of post-transcriptional modulators that are widely expressed in tissues and organs. And, it can suppress gene expression by targeting messenger RNAs for translational repression or, at a lesser extent, degradation. Research indicates that microRNAs regulate autophagy through different pathways, playing an essential role in the treatment of various diseases. It is an important regulator of fundamental cellular processes such as proliferation, autophagy, and cell apoptosis. In this review article, we first review the current knowledge of autophagy and the function of microRNAs. Then, we summarize the mechanism of autophagy and the signaling pathways related to autophagy by citing at least the main proteins involved in the different phases of the process. Second, we introduce other members of RNA and report some examples in various pathologies. Finally, we review the current literature regarding microRNA-based therapies for cancer, atherosclerosis, cardiac disease, tuberculosis, and viral diseases. MicroRNAs can cause autophagy upregulation or downregulation by targeting genes or affecting autophagy-related signaling pathways. Therefore, the microRNAs have a huge potential in autophagy regulation, and it is the function as diagnostic and prognostic markers.

Cellular Stress Responses in Radiotherapy

Radiotherapy is one of the major cancer treatment strategies. Exposure to penetrating radiation causes cellular stress, directly or indirectly, due to the generation of reactive oxygen species, DNA damage, and subcellular organelle damage and autophagy. These radiation-induced damage responses cooperatively contribute to cancer cell death, but paradoxically, radiotherapy also causes the activation of damage-repair and survival signaling to alleviate radiation-induced cytotoxic effects in a small percentage of cancer cells, and these activations are responsible for tumor radio-resistance. The present study describes the molecular mechanisms responsible for radiation-induced cellular stress response and radioresistance, and the therapeutic approaches used to overcome radioresistance.

125I suppressed the Warburg effect viaregulating miR-338/PFKL axis in hepatocellular carcinoma

OBJECTIVES

Iodine-125 (¹²⁵I) irradiation has been widely applied in the treatment of advanced multiple malignant tumors. However, the underlying mechanism of ¹²⁵I exerted an anti-tumor effect on hepatocellular carcinoma (HCC) was largely unknown.

METHODS

In both HCCLM3 and SMMC-7721 cells, the effect of ¹²⁵I irradiation on the glycolysis was detected. The mRNA in HCC tissues and cell lines were detected by RT-qPCR. Cell proliferation, invasion and migration, and apoptosis were examined by CCK-8, Transwell, wound healing assay and flow cytometry assay, respectively. The interaction between miR-338 and PFKL (6-phosphofructokinase) were verified by dual-luciferase reporter gene assay. Western blotting was used to detect the expression of glycolysis-related proteins. We also evaluated the effect of ¹²⁵I seed implantation on the tumor growth and Warburg effect in vivo.

RESULTS

¹²⁵I irradiation significantly decreased the Warburg effect, cell proliferation, invasion and migration, and induced apoptosis of HCCLM3 and SMMC-7721 cells. miR-338 was upregulated in HCC cells treated with ¹²⁵I irradiation, which was a negative correlation with tumor size, tumor metastasis, and tumor development. Moreover, miR-338 directly interacted with PFKL and suppressed its expression. Mechanistically, ¹²⁵I irradiation significantly decreased the Warburg effect and exhibited anti-tumorigenesis function through upregulating the inhibitory effect of miR-338 on PFKL expression.

CONCLUSION

¹²⁵I irradiation upregulated the suppression of miR-338 on PFKL to downregulate the Warburg effect and anti-tumorigenesis in HCC and provided a new potential strategy for HCC clinical treatment.

Molecular mechanisms of lncRNAs in regulating cancer cell radiosensitivity

Radiotherapy is one of the main modalities of cancer treatment. However, tumor recurrence following radiotherapy occurs in many cancer patients. A key to solving this problem is the optimization of radiosensitivity. In recent years, long non-coding RNAs (lncRNAs), which affect the occurrence and development of tumors through a variety of mechanisms, have become a popular research topic. LncRNAs have been found to influence radiosensitivity by regulating various mechanisms, including DNA damage repair, cell cycle arrest, apoptosis, cancer stem cells regulation, epithelial-mesenchymal transition, and autophagy. LncRNAs are expected to become a potential therapeutic target for radiotherapy in the future. This article reviews recent advances in the role and mechanism of lncRNAs in tumor radiosensitivity.

Clinical Significance of microRNA-196b-5p in Hepatocellular Carcinoma and its Potential Molecular Mechanism

Objective: To enquire into the clinical significance and potential molecular mechanism of microRNA (miRNA)-196b-5p in hepatocellular carcinoma (HCC).

Methods: Quantitative reverse transcription and polymerase chain reaction (qRT-PCR) were utilized to examine miR-196b-5p expression level in 67 HCC paraffin embedded tissues and corresponding adjacent tissues. Correlations of miR-196b-5p expression level with clinicopathological characteristics were analyzed in our study. The expression level and clinical significance of miR-196b-5p in HCC were also evaluated in The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) database. We made predictions of the target genes of miR-196b-5p by twelve online software and then selected genes predicted by at least 5 software. Subsequently, in order to obtain the potential target genes of miR-196b-5p, we overlapped the predicted target genes and down-regulated mRNAs in HCC based on TCGA database. Then, we performed the Gene Ontology (GO) and the Disease Ontology (DO) functional annotation, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis and Protein-Protein Interaction (PPI) network construction of those miR-196b-5p potential target genes.

Results: Higher expression level of miR-196b-5p was seen in HCC tissues than in the corresponding adjacent tissues based on qRT-PCR (P = 0.0007). The expression level of miR-196b-5p was linked with tumor size (P = 0.03), tumor node (P = 0.024), vascular invasion (P = 0.029) and capsular invasion (P = 0.026) in HCC patients. Comprehensive meta-analysis of miR-196b-5p expression based on TCGA, GEO and qRT-PCR verified that higher expression level of miR-196b-5p was observed in HCC tissues than in normal control liver tissues (SMD = 0.56, 95%CI: 0.39-0.72, P_{heterogeneity} = 0.275, I² = 18.3%). GO annotation revealed that the top terms in biological process, cellular component and molecular function were single-organism catabolic process, neuronal cell body and transmembrane receptor protein kinase activity, respectively. The most relevant disease in DO annotation was arteriosclerosis. The tryptophan metabolism pathway ranked first in KEGG pathway enrichment analysis. The PPI network showed that IGF1, FOXO1, AR and FOS were mostly likely to become the core genes of miR-196b-5p potential target genes, which however required further experiments for validation.

Conclusion: The miR-196b-5p was observed to show higher expression in HCC tissues than in normal control liver tissues. Moreover, the miR-196b-5p expression level had correlations with the clinicopathological parameters such as vascular invasion of HCC, but the molecular mechanisms of miR-196b-5p in HCC still need further elucidation and verification.

CircRNA CBL.11 suppresses cell proliferation by sponging miR-6778-5p in colorectal cancer

BACKGROUND

Radiotherapy (RT) is considered an important therapeutic strategy in the fight against colorectal cancer (CRC). However, the existence of some radioresistance factors becomes the main challenge for the RT. Recently, non-coding RNAs (ncRNAs) have shown an important role in modulating cancer cell responses to ionizing radiation (IR). It is therefore of great significance to elucidate the exact mechanisms of ncRNAs in IR-mediated responses to CRC.

METHODS

Microarrays were used to identify specific miRNAs that may be altered in response to IR. Bioinformatics, luciferase reporter analyses were used to explore the targets of miR-6778-5p. CircRNA CBL.11 was identified to bind with miR-6778-5p by bioinformatic analysis, AGO2 immunoprecipitation and biotinylated RNA pull-down assay. Functional experiments, including CCK-8 assay, cell colony formation assay and EdU incorporation were conducted to investigate the biological roles of miR-6778-5p and circular RNA CBL.11.

RESULTS

MiR-6778-5p was suppressed in CRC cells after irradiation. Results of functional experiments indicated that miR-6778-5p promoted the proliferation of CRC cells. Luciferase reporter analyses showed that YWHAE was a target of miR-6778-5p, which mediated the function of miR-6778-5p in the proliferation of CRC cells via the p53 pathway. Furthermore, we have noticed that after carbon ion irradiation, circRNA CBL.11 was increased in CRC cells and could function as a competing endogenous RNA (ceRNA) to regulate YWHAE expression by sponging miR-6778-5p, resulting in regulation the proliferation of CRC cells.

CONCLUSION

CircRNA CBL.11 may play an important role in improving the efficacy of carbon ion RT against CRC.

MiR-203 acts as a radiosensitizer of gastric cancer cells by directly targeting ZEB1

Objective: Gastric cancer (GC) is a common tumor malignancy with high incidence and poor prognosis. Radiotherapy is one of the main strategies for GC treatment, while development of radioresistance limits the effectiveness. microRNA-203 (miR-203) has been reported to participate in progression of GC, whereas its interaction with radiosensitivity of GC and the related mechanism remain largely unclear. Methods: The expressions of miR-203 and zinc finger E-box binding homeobox 1 (ZEB1) were measured in GC tissues and cells by quantitative real-time polymerase chain reaction or western blot. Survival fraction, cell viability and apoptosis were measured in GC cells after treatment of radiation by colony formation, 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay or flow cytometry, respectively. Tumor volume and weight were detected in murine xenograft model after radiation treatment. The interaction between miR-203 and ZEB1 was explored by bioinformatics analysis and luciferase activity assay. Results: miR-203 expression was down-regulated and ZEB1 mRNA level was up-regulated in GC. The expression of miR-203 was associated with radiosensitivity of GC cells. Moreover, overexpression of miR-203 decreased survival fraction, cell viability and tumor growth but promoted cell apoptosis in radiation-treated GC cells. However, knockdown of miR-203 played an opposite effect. ZEB1 was validated as a target of miR-203, and it was involved in miR-203-mediated radiosensitivity of GC cells in vitro and in vivo. Conclusion: miR-203 promoted radiosensitivity of GC cells by targeting ZEB1, indicating miR-203 as a promising radiosensitizer for GC treatment.

Copper Oxide Nanoparticles Induce Enhanced Radiosensitizing Effect via Destructive Autophagy

Emerging nanotechnologies for radiotherapy are attracting increasing interest from researchers in recent years. To improve the radiotherapeutic performance, developing nanoparticles that can efficiently generate toxic reactive oxygen species (ROS) under X-ray irradiation are highly desirable. Here, we investigate the potential of copper oxide nanoparticles (CuO NPs) as nanoradiosensitizers. Increased cancer cell inhibition is observed in colony formation assay and real-time cell analysis after the combined treatment with CuO NPs and X-ray irradiation, whereas the CuO NPs alone do not have any negative influence on cell viability, indicating the radiosensitization effect of CuO NPs. Importantly, the significantly increased ROS level in cells contributes to the enhanced damage to cancer cells under the combined treatment. Besides, the cell cycle is regulated to the X-ray-sensitive phase (G₂/M phase) by CuO NPs, which may also account for the inhibited proliferation of cancer cells. Furthermore, results from Western blot analysis and colony formation assay reveal that the increased cell death may be mainly attributed to the excessive autophagy induced by both CuO NPs and X-ray irradiation. Moreover, in vivo experiments verify the radiosensitization of CuO NPs and their favorable biosafety. The current study suggests that CuO NPs can be utilized as nanoradiosensitizers for increasing the efficiency of cancer radiotherapy.