Radiosensitivity Of Colorectal Cancer Cells Research Articles

M6A-modified circ_0124554 promotes colorectal cancer progression and radioresistance through the miR-1184/LASP1 pathway

BackgroundCircular RNAs (circRNAs) are believed to regulate the progression of various cancers including colorectal cancer (CRC). However, the role and mechanism of circ_0124554 in regulating the sensitivity of CRC to radiation remain unknown. MethodsThe RNA levels of circ_0124554, LIM and SH3 protein 1 (LASP1), and methyltransferase 3, N6-adenosine-methyltransferase complex catalytic subunit (METTL3) were detected by quantitative real-time polymerase chain reaction. Protein expression was checked by western blot. Cell proliferation, apoptosis, migration, and invasion were investigated by 5-Ethynyl-2′-deoxyuridine (EdU) assay, flow cytometry analysis, and transwell assay, respectively. The sensitivity of CRC cells to radiation was analyzed by cell colony formation assay. Xenograft mouse model assay was conducted to disclose the role of circ_0001023 in the sensitivity of tumors to radiation in vivo. The binding relationships among circ_0124554, miR-1184 and LASP1 were confirmed by a dual-luciferase reporter assay. m6A RNA immunoprecipitation assay was performed to identify the association of METTL3 with circ_0124554. ResultsCirc_0124554 expression was upregulated in CRC tissues and cells in comparison with normal colorectal tissues and cells. Circ_0124554 knockdown inhibited proliferation, migration and invasion and promoted apoptosis and radiosensitivity of CRC cells. Moreover, circ_0124554 depletion inhibited tumor formation and improved radiosensitivity in vivo. MiR-1184 was identified as a target miRNA of circ_0124554 and targeted LASP1. Additionally, LASP1 overexpression rescued circ_0124554 knockdown-mediated effects in CRC cells. METTL3 mediated m6A methylation of circ_0124554. Further, circ_0124554 overexpression attenuated METTL3 depletion-induced effects in CRC cells. Conclusionm6A-modified circ_0124554 promoted CRC progression and radioresistance by inducing LASP1 expression through interaction with miR-1184.

SUMO-Activating Enzyme Subunit 1 Is Associated with Poor Prognosis, Tumor Progression, and Radio-Resistance in Colorectal Cancer.

Concurrent chemoradiotherapy is an effective treatment option for patients with low-grade colorectal cancer (CRC) in the local disease stage. At present, the principle of the Taiwan Medical Center is to treat CRC patients with combination radiotherapy and chemotherapy (high-dose 5-FU) for a period of about five weeks prior to surgery. Radical resection of the tumor is performed at least six to eight weeks after concurrent chemoradiotherapy (CCRT). However, this approach fails to produce the desired therapeutic effect in approximately 20% to 30% of patients, and such patients are unnecessarily exposed to the risks of radiation and drug toxicity posed by this therapy. Therefore, it is crucial to explore new biomarkers to predict the prognosis of CRC. SUMO-activating enzyme subunit 1 (SAE1) plays an important role in SUMOylation, a post-translational modification involved in cellular functions, such as cell proliferation, cell cycle, and apoptosis. In our study, to explore the clinical-pathological role of SAE1 protein in CRC, we evaluated the clinical data and paraffin sections from CRC patients. The expression of SAE1 was evaluated using immunohistochemical analysis, and clinical parameters were analyzed using chi-square and Kaplan-Meier survival tests. The results of in vitro proliferation and radiosensitive assays were compared between control groups and SAE1 siRNA groups. Western blotting was also used to detect the expressions of the SAE1, PARP, cyclin D1, p-NF-κB, and NF-κB proteins. Flow cytometry and colony formation assays were used to detect the effect of SAE-1 on radiosensitivity. In vivo, we detected the growth curve in a mouse xenograft model. The results showed that SAE-1 was revealed to be an independent prognostic biomarker of CRC. SAE1 knockdown inhibited CRC proliferation in vitro and in vivo, and led to the cleavage of PARP, downregulation of cyclin D1 protein expression, and downregulation of p-NF-κB/NF-κB. Additionally, SAE1 knockdown promoted radiosensitivity in CRC cells. Therefore, it was inferred that SAE1 may be used as a potential therapeutic target in CRC treatment.

SENP5 promotes homologous recombination-mediated DNA damage repair in colorectal cancer cells through H2AZ deSUMOylation

BackgroundNeoadjuvant radiotherapy has been used as the standard treatment of colorectal cancer (CRC). However, radiotherapy resistance often results in treatment failure. To identify radioresistant genes will provide novel targets for combined treatments and prognostic markers.MethodsThrough high content screening and tissue array from CRC patients who are resistant or sensitive to radiotherapy, we identified a potent resistant gene SUMO specific peptidase 5 (SENP5). Then, the effect of SENP5 on radiosensitivity was investigated by CCK8, clone formation, comet assay, immunofluorescence and flow cytometric analysis of apoptosis and cell cycle to investigate the effect of SENP5 on radiosensitivity. SUMO-proteomic mass spectrometry combined with co-immunoprecipitation assay were used to identify the targets of SENP5. Patient-derived organoids (PDO) and xenograft (PDX) models were used to explore the possibility of clinical application.ResultsWe identified SENP5 as a potent radioresistant gene through high content screening and CRC patients tissue array analysis. Patients with high SENP5 expression showed increased resistance to radiotherapy. In vitro and in vivo experiments demonstrated that SENP5 knockdown significantly increased radiosensitivity in CRC cells. SENP5 was further demonstrated essential for efficient DNA damage repair in homologous recombination (HR) dependent manner. Through SUMO mass spectrometry analysis, we characterized H2AZ as a deSUMOylation substrate of SENP5, and depicted the SUMOylation balance of H2AZ in HR repair and cancer resistance. By using PDO and PDX models, we found targeting SENP5 significantly increased the therapeutic efficacy of radiotherapy.ConclusionOur findings revealed novel role of SENP5 in HR mediated DNA damage repair and cancer resistance, which could be applied as potent prognostic marker and intervention target for cancer radiotherapy.

Metformin is a metabolic modulator and radiosensitiser in rectal cancer.

Resistance to neoadjuvant chemoradiation therapy, is a major challenge in the management of rectal cancer. Increasing evidence supports a role for altered energy metabolism in the resistance of tumours to anti-cancer therapy, suggesting that targeting tumour metabolism may have potential as a novel therapeutic strategy to boost treatment response. In this study, the impact of metformin on the radiosensitivity of colorectal cancer cells, and the potential mechanisms of action of metformin-mediated radiosensitisation were investigated. Metformin treatment was demonstrated to significantly radiosensitise both radiosensitive and radioresistant colorectal cancer cells in vitro. Transcriptomic and functional analysis demonstrated metformin-mediated alterations to energy metabolism, mitochondrial function, cell cycle distribution and progression, cell death and antioxidant levels in colorectal cancer cells. Using ex vivo models, metformin treatment significantly inhibited oxidative phosphorylation and glycolysis in treatment naïve rectal cancer biopsies, without affecting the real-time metabolic profile of non-cancer rectal tissue. Importantly, metformin treatment differentially altered the protein secretome of rectal cancer tissue when compared to non-cancer rectal tissue. Together these data highlight the potential utility of metformin as an anti-metabolic radiosensitiser in rectal cancer.

A positive feedback loop between ID3 and PPARγ via DNA damage repair regulates the efficacy of radiotherapy for rectal cancer

ObjectiveTo study the effect of inhibitor of differentiation 3 (ID3) on radiotherapy in patients with rectal cancer and to explore its primary mechanism.MethodsCell proliferation and clonogenic assays were used to study the relationship between ID3 and radiosensitivity. Co-immunoprecipitation and immunofluorescence were performed to analyze the possible mechanism of ID3 in the radiosensitivity of colorectal cancer. At the same time, a xenograft tumor model of HCT116 cells in nude mice was established to study the effect of irradiation on the tumorigenesis of ID3 knockdown colorectal cancer cells in vivo. Immunohistochemistry was performed to analyze the relationship between ID3 expression and the efficacy of radiotherapy in 46 patients with rectal cancer.ResultsProliferation and clonogenic assays revealed that the radiosensitivity of colorectal cancer cells decreased with ID3 depletion through p53–independent pathway. With the decrease in ID3 expression, MDC1 was downregulated. Furthermore, the expression of ID3, MDC1, and γH2AX increased and formed foci after irradiation. ID3 interacted with PPARγ and form a positive feedback loop to enhance the effect of ID3 on the radiosensitivity of colorectal cancer. Irradiation tests in nude mice also confirmed that HCT116 cells with ID3 knockdown were more affected by irradiation. Immunohistochemical study showed that rectal cancer patients with low expression of ID3 had better radiotherapy efficacy.ConclusionsID3 and PPARγ influence the radiosensitivity of colorectal cancer cells by interacting with MDC1 to form a positive feedback loop that promotes DNA damage repair. Patients with low expression of ID3 who received neoadjuvant chemoradiotherapy can obtain a better curative effect.

PRDM15 interacts with DNA-PK-Ku complex to promote radioresistance in rectal cancer by facilitating DNA damage repair

Neoadjuvant radiotherapy is a standard treatment for locally advanced rectal cancer, however, resistance to chemoradiotherapy is one of the main obstacles to improving treatment outcomes. The goal of this study was to explore the role of PRDM15 involved in the radioresistance of colorectal cancer and to clarify the underlying mechanism. In present study, we demonstrated that, after DNA damage, PRDM15 was upregulated and localized to DNA damage sites, co-localizing with γ-H2AX. Knockdown of PRDM15 inhibited DNA damage repair and increased radiosensitivity in colorectal cancer cells. Mechanistically, PRDM15 promoted DNA repair by interacting with DNA-PKcs and Ku70/Ku80 complex. In preclinical models of rectal cancer, knockdown of PRDM15 sensitized cell derived xenograft and patient derived xenograft to radiotherapy. In 80 rectal cancer patients treated with neoadjuvant chemoradiotherapy, higher PRDM15 expression was observed associated with weaker tumor regression and poorer prognosis. Our findings revealed that inhibiting PRDM15 was potent to overcome radioresistance through abrogating DNA repair in colorectal cancer cells. Additionally, the expression level of PRDM15 could be applied to predict radiotherapy responsiveness and the outcome of neoadjuvant radiotherapy in rectal cancer patients.

Upregulation of Long Noncoding RNA MALAT1 in Colorectal Cancer Promotes Radioresistance and Aggressive Malignance.

Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), a conserved transcript with 8000 nt, is highly associated with malignancy of numerous cancer types. However, the function of MALAT1 plays in regulating the response to radiotherapy in colorectal cancer (CRC) remains unclear. Thus, the object of this study is to investigate the functions of MALAT1 in CRC radioresistance. First, the expression of MALAT1 in colon adenocarcinoma (COAD) was analyzed through the Cancer Genome Atlas (TCGA) database. Then, we detected the expression level of MALAT1 in tumor tissues and CRC cell lines and analyzed the relevance of MALAT1 and clinicopathological parameters. In the end, the effect of silencing MALAT1 on the radiosensitivity of CRC cells was investigated, and its potential mechanism was preliminarily illustrated. The analysis of TCGA data showed that MALAT1 was closely related to the type of tumor, and high expression of MALAT1 was remarkably relevant to poor outcome. MALAT1 was highly expressed in CRC tissues and cell lines and related to tumor stages. Knockdown of MALAT1 could significantly suppress colony survival, proliferation, and migration and increase apoptosis, G2/M phase arrest, and formation of gamma-H2AX foci in HCT116, whether in combination with X-rays or not. Moreover, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis demonstrated that the regulated proteins were principally enriched in the glycosaminoglycan degradation pathway after silencing MALAT1. Our results implied that MALAT1 was highly expressed in CRC and associated with tumor stage and prognosis. Silencing MALAT1 can increase HCT116 cell radiosensitivity, which may be potentially influenced by glycosaminoglycan degradation pathway.

SOCS1 counteracts ROS-mediated survival signals and promotes apoptosis by modulating cell cycle to increase radiosensitivity of colorectal cancer cells

As negative regulators of cytokine signaling pathways, suppressors of cytokine signaling (SOCS) proteins have been reported to possess both pro-tumor and anti-tumor functions. Our recent studies have demonstrated suppressive effects of SOCS1 on epithelial to mesenchymal signaling in colorectal cancer cells in response to fractionated ionizing radiation or oxidative stress. The objective of the present study was to determine the radiosensitizing action of SOCS1 as an anti-tumor mechanism in color-ectal cancer cell model. In HCT116 cells exposed to ionizing radiation, SOCS1 over-expression shifted cell cycle arrest from G2/M to G1 and promoted radiation-induced apoptosis in a p53-dependent manner with down-regulation of cyclin B and up-regulation of p21. On the other hand, SOCS1 knock-down resulted in a reduced apoptosis with a decrease in G1 arrest. The regulatory action of SOCS1 on the radiation response was mediated by inhibition of radiation-induced Jak3/STAT3 and Erk activities, thereby blocking G1 to S transition. Radiation-induced early ROS signal was responsible for the activation of Jak3/Erk/STAT3 that led to cell survival response. Our data col-lectively indicate that SOCS1 can promote radiosensitivity of colorectal cancer cells by counteracting ROS-mediated survival signal, thereby blocking cell cycle progression from G1 to S. The resulting increase in G1 arrest with p53 activation then contributes to the promotion of apoptotic response upon radiation. Thus, induction of SOCS1 expression may increase therapeutic efficacy of radiation in tumors with low SOCS1 levels.

Effects of Long Non-Coding RNA TRIM52 Antisense RNA 1 on the Proliferation, Apoptosis and Radiosensitivity of Colorectal Cancer Cells by Targeting MicroRNA-361-5p

The aim of this study was to explore the effect of long non-coding RNA TRIM52 antisense RNA 1 on the proliferation, apoptosis and radiosensitivity of colorectal cancer cells and its possible mechanism. Real-time quantitative reverse transcription polymerase chain reaction method was used to detect the expression of long non-coding RNA TRIM52 antisense RNA 1 and microRNA-361-5p in adjacent tissues, colorectal cancer tissues and human normal colorectal mucosal cell lines, fetal human cells and human colorectal cancer cell lines. The transplanted tumor experiment in nude mice was used to detect the influence of the expression changes of long non-coding RNA TRIM52 antisense RNA 1 and microRNA-361-5p on the transplanted tumor growth. The expression of long non-coding RNA TRIM52 antisense RNA 1 in colorectal cancer tissues and cell lines was increased, while the expression of microRNA-361-5p was decreased (p<0.05). After transfection of small interfering long non-coding RNA TRIM52 antisense RNA 1 or microRNA-361-5p mimics, cell viability and cell survival score were decreased, the number of cell clone formation was decreased and cell apoptosis rate was increased (p<0.05). Transfection of small interfering long non-coding RNA TRIM52 antisense RNA 1 could inhibit the growth of transplanted tumors in nude mice. Long non-coding RNA TRIM52 antisense RNA 1 could target the microRNA-361-5p expression. The expression of long non-coding RNA TRIM52 antisense RNA 1 could inhibit colorectal cancer cell proliferation and clone formation and promote cell apoptosis by targeted regulation of microRNA-361-5p expression and could enhance the radiosensitivity of colorectal cancer cells.

MiRNA‐31 increases radiosensitivity through targeting STK40 in colorectal cancer cells

ObjectiveTo propose and verify that miRNA‐31 increases the radiosensitivity of colorectal cancer and explore its potential mechanism.MethodA bioinformatics analysis was performed to confirm that the expression of miRNA‐31 was higher in colorectal cancer than in normal colorectal tissue. The expression of miRNA‐31 was detected to verify the change in its expression in a radiotherapy‐resistant cell line. Methylation was detected to explore the cause of the decrease in miRNA‐31 expression. Overexpression or inhibition of miRNA‐31 further confirmed the change in its expression in colorectal cancer cell lines. Bioinformatics methods were used to screen the downstream target genes and for experimental verification. A luciferase assay was performed to determine the miRNA‐31 binding site in STK40. Overexpression or inhibition of STK40 in colorectal cancer cell lines further confirmed the change in STK40 expression in vitro.ResultsThe bioinformatics results showed higher expression of miRNA‐31 in tumors than in normal tissue, and miRNA‐31 mainly participated in the pathway related to cell replication. Next, we observed the same phenomenon: miRNA‐31 was expressed at higher levels in colorectal tumors than in normal colorectal tissue and its expression decreased in radiation‐resistant cell lines after radiation, implying that miRNA‐31 increased the radiosensitivity of colorectal cancer cell lines. No significant change in upstream methylation was observed. miRNA‐31 regulated the radiosensitivity of colorectal cancer cell lines by inhibiting STK40. Notably, miRNA‐31 played a role by binding to the 3′ untranslated region of SK40. STK40 negatively regulated the radiosensitivity of colorectal cancer cells.ConclusionsmiRNA‐31 increases the radiosensitivity of colorectal cancer cells by targeting STK40; miRNA‐31 and STK40 are expected to become potential biomarkers for increasing the sensitivity of tumor radiotherapy in clinical treatment.

IFI35 is involved in the regulation of the radiosensitivity of colorectal cancer cells

BackgroundInterferon regulatory factor-1 (IRF1) affects the proliferation of colorectal cancer (CRC). Recombinant interferon inducible protein 35 (IFI35) participates in immune regulation and cell proliferation. The aim of the study was to examine whether IRF1 affects the radiation sensitivity of CRC by regulating IFI35.MethodsCCL244 and SW480 cells were divided into five groups: blank control, IFI35 upregulation, IFI35 upregulation control, IFI35 downregulation, and IFI35 downregulation control. All groups were treated with X-rays (6 Gy). IFI35 activation by IRF1 was detected by luciferase reporter assay. The GEPIA database was used to examine IRF1 and IFI35 in CRC. The cells were characterized using CCK-8, EdU, cell cycle, clone formation, flow cytometry, reactive oxygen species (ROS), and mitochondrial membrane potential. Nude mouse animal models were used to detect the effect of IFI35 on CRC.ResultsIRF1 can bind to the IFI35 promoter and promote the expression of IFI35. The expression consistency of IRF1 and IFI35 in CRC, according to GEPIA (R = 0.68, p < 0.0001). After irradiation, the upregulation of IFI35 inhibited cell proliferation and colony formation and promoted apoptosis and ROS, while IFI35 downregulation promoted proliferation and colony formation and reduced apoptosis, ROS, and mitochondrial membrane potential were also reduced. The in vivo experiments supported the in vitro ones, with smaller tumors and fewer liver metastases with IFI35 upregulation.ConclusionsIRF1 can promote IFI35 expression in CRC cells. IFI35 is involved in the regulation of radiosensitivity of CRC cells and might be a target for CRC radiosensitization.

Silence of circBANP increases radiosensitivity of colorectal cancer cells and inhibits growth of subcutaneous xenografts by up-regulating miR-338-3p expression

Objective: To investigate the effect of circBANP on radiosensitivity of colorectal cancer cells and subcutaneous transplanted tumor in nude mice and its potential molecular mechanism. Methods: The carcinoma and adjacent normal mucosal tissues of 20 patients with colorectal cancer who were surgically resected in Henan People's Hospital from January 2018 to January 2019 were selected. The radio-resistant colorectal cancer cell LoVo/R was established. Real-time quantitative polymerase chain reaction (RT-qPCR) was used to detect the expressions of circBANP and miR-338-3p. The radiation sensitivity was determined by cell clone formation experiment. Cell vitality was detected by using methyl thiazolyl tetrazolium (MTT). The expressions of autophagy-related protein microtubule-associated protein light chain 3 (LC3) and p62 were detected by western blot. The fluorescence intensity of LC3 in cells was detected by immunofluorescence assay. The downstream microRNAs (miRNAs) of circBANP were predicted by Circular RNA Interactome website and further verified by dual luciferase reporter gene assay. The transplanted tumor model of LoVo/R cells in nude mice was established, and the effect of circBANP on the growth of transplanted tumor after radiation was observed. Results: The expression levels of circBANP and miR-338-3p in colorectal cancer tissues were 3.21+ 0.29 and 0.47+ 0.04, respectively, which were significantly higher than 1.00+ 0.07 and 1.00+ 0.05 in adjacent tissues (P<0.05). The circBANP expression level of LoVo/R cells was 3.21±0.34, higher than 1.00±0.07 of LoVo cells (P<0.05), and the expression level of miR-338-3p of LoVo/R cells was 0.33±0.04, lower than 1.00±0.08 of LoVo cells (P<0.05). After 4 Gy irradiation, compared with the control group, the viability of LoVo/R cells in the circBANP silencing group [(34±4)% vs (62±6)%, P<0.05], the cell survival fraction (0.07±0.02 vs 0.27±0.04, P<0.05) were decreased, and the radiation sensitization ratio was 1.843, the expression of LC3Ⅱ/Ⅰin LoVo/R cells increased while p62 expression decreased, the cell autophagy was observed. Autophagy inhibitor chloroquine reversed the increased expression of LC3Ⅱ/Ⅰ and inhibited expression of p62 in LoVo/R cells induced by radiation, and promoted the suppression of cell viability and survival induced by radiation, the radiotherapy sensitization ratio was 1.780. Compared with control group after 4 Gy irradiation, the relative fluorescence intensity of LC3 in circBANP silencing LoVo/R cells decreased (0.11±0.01 vs 1.00±0.12, P<0.05), the expression of LC3-Ⅱ/Ⅰdecreased (1.25±0.13 vs 3.84±0.39, P<0.05) while p62 expression increased (2.76±0.29 vs 1.00±0.08, P<0.05). As predicted by Circular RNA Interactome website and confirmed by double luciferase reporter gene assay, miR-338-3p was the target gene of circBANP. The relative fluorescence intensity of LC3 in circBANP silencing + anti-miR-338-3p + 4 Gy group increased (7.32±0.72 vs 1.00±0.09, P<0.05), the expression level of LC3-Ⅱ/Ⅰ increased (4.13±0.43 vs 2.31±0.23, P<0.05) while p62 expression decreased (0.34±0.03 and 1.00±0.11, P<0.05), the radiotherapy sensitization ratio was 0.596. Nude mice subcutaneously transplanted tumor experiment showed that the tumor volume and weight of circBANP silencing group on 13, 16, 19, 22, 25, 28, and 31 days were lower than those of control group (P<0.05), while the tumor volume and weight of circBANP silencing + anti-miR-338-3p group on days of 13, 16, 19, 22, 25, 28 and 31 after inoculated were higher than those of circBANP+ anti-miR-NC group (P<0.05). Conclusions: CircBANP can regulate the radiosensitivity of colorectal cancer cells by regulating the expression of miR-338-3p, and affect the growth of transplanted tumor in nude mice. CircBANP may be a potential target for enhancing radiosensitivity of colorectal cancer cells.

O11: MYOFERLIN: A NOVEL BIOMARKER OF RADIOSENSITIVITY IN LOCALLY ADVANCED RECTAL CANCER

Abstract Introduction Our proteomic data has validated that high levels of the protein myoferlin confers poorer response to neoadjuvant chemoradiotherapy in locally advanced rectal cancer. Myoferlin plays a role in membrane repair and VEGF signal transduction, and is associated with worse prognosis in numerous other epithelial cancers. We aim to assess the impact of myoferlin on the radiosensitivity of rectal cancer. Method Clonogenic assays were performed using immortalised colorectal cancer cells (HCT116,HT29,LIM,MDST8) to assess survival at escalating radiation doses following knockdown with myoferlin siRNA or a small molecular inhibitor(WJ460). 3D models (spheroids) were used to examine the effect of WJ460 on tumour growth. Result Quantification of myoferlin using immunoblotting demonstrated that MDST8 and LIM were higher expressors than HCT116 and HT29. Higher levels correlated with increasing radio-resistance as calculated by colony formation efficiency (CFE). Using clonogenic assays, cells treated with myoferlin siRNA or WJ460 demonstrated increased radiosensitivity compared to controls across all radiation doses, most significantly at 4Gy. Treatment of spheroids with WJ460 significantly reduced growth compared to controls at all radiation doses (p&amp;lt;0.05), with WJ460 limiting growth considerably more than treatment with the current gold standard 5-FU. HCT116 spheroid volume day 15; WJ460 4.96um3,5-FU 6.74um3,DMSO 24.9um3. Conclusion Inhibition of myoferlin is associated with increased radiosensitivity of colorectal cancer cells, and treatment with a small molecular inhibitor significantly reduces growth in spheroid models. Further work is required further validate its potential use as a biomarker in locally advanced rectal cancer. Take-home message We have found that myoferlin is a protein associated with poor response to neoadjuvant chemoradiotherapy in locally advanced rectal cancer. Manipulation of this protein sensitises the cancer cells to radiotherapy.

Downregulation of miR-423-5p Contributes to the Radioresistance in Colorectal Cancer Cells.

Resistance to radiotherapy is the main reason causing treatment failure in locally advanced rectal cancer. MicroRNAs (miRNAs) have been well demonstrated to regulate cancer development and progression. However, how miRNAs regulate radiotherapy resistance in colorectal cancer remains unknown. Herein, we established two human colorectal cancer cell lines resistant to radiotherapy, named HCT116-R and RKO-R, using the strategy of fractionated irradiation. The radioresistant phenotypical changes of the two cell lines were validated by cell viability assay, colony formation assay and apoptosis assay. The miRNA expression profilings of HCT116-R and RKO-R were determined using RNA-seq analyses, and further confirmed by quantitative real-time PCR. Multiple miRNAs, including miR-423-5p, miR-7-5p, miR-522-3p, miR-3184-3p, and miR-3529-3p, were identified with altered expression in both of the radiotherapy-resistant cells, compared to the parental cells. The downregulation of miR-423-5p was further validated in the rectal cancer tissues from radiotherapy-resistant patients. Silencing of miR-423-5p in parental HCT116 and RKO cells decreased the sensitivity to radiation treatment, and inhibited the radiation-induced apoptosis. In consistence, overexpression of miR-423-5p in HCT116-R and RKO-R cells partially rescued their sensitivity to radiotherapy, and promoted the radiation-induced apoptosis. Bcl-xL (Bcl-2-like protein 1) was predicted to be a potential target gene for miR-423-5p, and miR-423-5p/Bcl-xL axis could be a critical mediator of radiosensitivity in colorectal cancer cells. The current finding not only revealed a novel role of miR-423-5p in regulating the radiosensitivity in colorectal cancer, but also suggested miR-423-5p as a molecular candidate for combination therapy with radiation to treat colorectal cancer.

γ-H2AX as a potential indicator of radiosensitivity in colorectal cancer cells.

Preoperative radiotherapy improves local disease control and disease-free survival in patients with advanced rectal cancer; however, a reliable predictive biomarker for the effectiveness of irradiation has yet to be elucidated. Phosphorylation of H2A histone family member X (H2AX) to γ-H2AX is induced by DNA double-strand breaks and is associated with the development of colorectal cancer (CRC). The current study aimed to clarify the relationship between γ-H2AX expression and CRC radiosensitivity in vitro and in vivo. H2AX levels were analyzed in datasets obtained from cohort studies and γ-H2AX expression was investigated by performing immunohistochemistry and western blotting using clinical CRC samples from patients without any preoperative therapy. In addition, the CRC cell lines WiDr and DLD-1 were subjected to irradiation and/or small interfering RNA-H2AX, after which the protein levels of γ-H2AX were examined in samples obtained from patients undergoing preoperative chemoradiotherapy. To quantify the observable effect of treatment on cancer cells, outcomes were graded as follows: 1, mild; 2, moderate; and 3, marked, with defined signatures of cellular response. Datasets obtained from cohort studies demonstrated that H2AX mRNA levels were significantly upregulated and associated with distal metastasis and microsatellite instability in CRC tissues, in contrast to that of normal tissues. In addition, γ-H2AX was overexpressed in clinical samples. In vitro, following irradiation, γ-H2AX expression levels increased and cell viability decreased in a time-dependent manner. Combined irradiation and γ-H2AX knockdown reduced the viability of each cell line when compared with irradiation or γ-H2AX knockdown alone. Furthermore, among clinical CRC samples from patients undergoing preoperative chemoradiotherapy, levels of γ-H2AX in the grade 1 group were significantly higher than those in grade 2 or grade 3. In conclusion, γ-H2AX may serve as a novel predictive marker and target for preoperative radiotherapy effectiveness in patients with CRC.

Allicin enhances the radiosensitivity of colorectal cancer cells via inhibition of NF‐κB signaling pathway

Radioresistance is an important factor affecting the radiotherapy effect of colorectal cancer (CRC). Allicin is a versatile sulfur-containing organic compound extracted from garlic (Allium sativum L.), which has many pharmacological effects. However, the effect of allicin on the sensitivity of CRC radiotherapy has not been confirmed. The present study is to observe the radiosensitivity effects of allicin and to explore its mechanism in CRC radiotherapy. The proliferation inhibition effects of allicin combined with X-ray radiotherapy in HCT116 cells were measured by growth curve of cell and colony formation assays. The cell apoptosis was detected by Hoechst 33258 nucleus staining assay. The migration ability of cells was detected by Transwell chamber migration assay. The animal model of CRC was established in BALB/c mice via transplantation of CT26 cell, and the radiosensitization effect of allicin on CRC was detected in vivo. The mRNA expressions of NF-κB, IKKβ, and IκBα were analyzed by reverse transcription-polymerase chain reaction (RT-PCR). The protein expressions of NF-κB, p-NF-κB, IKKβ, p-IKKβ, IκBα, and p-IκBα were detected by western blotting. Our results showed that allicin improves the sensitivity of X-ray radiotherapy in CRC, and its mechanism may be associated with inhibition of NF-κB signaling pathway. These findings suggest that allicin may be used as a potential sensitizer for tumor radiotherapy in the clinic.

Long noncoding RNA lnc-RI regulates DNA damage repair and radiation sensitivity of CRC cells through NHEJ pathway.

A percentage of colorectal cancer (CRC) patients display low sensitivity to radiotherapy, which affects its therapeutic effect. Cancer cells DNA double-strand breaks (DSBs) repair capacity is crucial for radiosensitivity, but the roles of long noncoding RNAs (lncRNAs) in this process are largely uncharacterized. This study aims to explore whether lnc-RI regulates CRC cell growth and radiosensitivity by regulating the nonhomologous end-joining (NHEJ) repair pathway. CRC cells in which lnc-RI has been silenced showed lower cell growth and higher apoptosis rates due to increased DSBs and cell cycle arrest. We found that miR-4727-5p targets both lnc-RI and LIG4 mRNA and inhibit their expression. CRC cells showed increased radiosensitivity when lnc-RI was silenced. These results reveal novel roles for lnc-RI in both DNA damage repair and radiosensitivity regulation in CRC cells. Our study revealed that lnc-RI regulates LIG4 expression through lnc-RI/miR-4727-5p/LIG4 axis and regulates NHEJ repair efficiency to participate in DNA damage repair. The level of lnc-RI was negatively correlated with the radiosensitivity of CRC cells, indicates that lnc-RI may be a potential target for CRC therapy. We also present the first report of the function of miR-4727-5p.

Effect of lncRNA CRNDE targeting miR-384 on radiosensitivity of colorectal cancer cells

Objective To study the effect of LncRNA CRNDE on radiosensitivity of colorectal cells and underlying mechanism. Methods Colorectal cancer HT-29 cells were transfected with CRNDE shRNA and the interference efficiency was determined by Real time PCR. HT-29 cells transfected with CRNDE shRNA or co-transfected with CRNDE shRNA and miR-384 inhibitor were irradiated at 8 Gy dose, then cell proliferation and apoptosis were detected by MTT and flow cytometry assay, respectively, and cell radiosensitivity was evaluated by cloning assay. It was predicted by a bioinformatics software that CRNDE and miR-384 have complementary binding sites, and this was identified by a luciferase reporting system. Results CRNDE shRNA reduced the expression of CRNDE in HT-29 cells(1.00±0.08 vs. 0.42±0.06, t=10.051, P<0.05). Both CRNDE shRNA and radiation inhibited the proliferation and induced apoptosis of HT-29 cells, and their combination treatment had synergistic effect in apoptosis induction [Apoptosis rates: (2.27±0.13)%, (23.58±2.35)%, (26.91±2.81)%, (36.84±3.24)%, F=24.660, P<0.05; A values: 0.45±0.06, 0.30±0.02, 0.28±0.03, 0.20±0.02, F=106.207, P<0.05]. Transfection of CRNDE shRNA increased the radiosensitivity of HT-29 cells with a radiosensitization ratio of 1.374. CRNDE negatively regulated the expression of its target miR-384. The miR-384 inhibitor antagonized the effect of CRNDE shRNA on proliferation inhibition and apoptosis promotion of radiation-treated colorectal cancer cells. Conclusions Down-regulation of LncRNA expression enhances the radiosensitivity of colorectal cancer cells by regulating miR-384 expression. Key words: Colorectal cancer; Colorectal neoplasia differentially expressed(CRNDE); miR-384; Radiosensitivity

LncRNA ANRIL target miR-195 experimental study of radiation sensitivity of HCT116 cells and nude mouse transplant tumors

Objective To investigate the effect and mechanism of LncRNA ANRIL on the radiosensitivity of HCT116 cells line and nude mouse transplant tumors. Methods The expression of LncRNA ANRIL in colorectal cancer cells was detected by qPCR. The negative control siRNA, ANRIL siRNA, miR-NC mimic, miR-195 mimic, miR-NC inhibitor and miR-195 inhibitor were transfected into HCT116 cells, and marked as negative control group, silencing ANRIL group, overexpressing miR-NC group, overexpressing miR-195 group, inhibiting miR-NC group and inhibiting miR-195 group, and the HCT116 cells without any treatment were marked as the blank control group. The clone formation assay was used to detect radiosensitivity of colorectal cancer cells, flow cytometry was used to detect apoptosis. The web site, StarBase, was used to predict the downstream miRNAs of ANRIL and dual luciferase reporter gene assay was used to further verify. Subcutaneous tumor transplantation assay was used to detect the effect of ANRIL on the growth of colorectal cancer cells after irradiation. Results After irradiation with 2, 4, 6 and 8 Gy, the cell survival fraction of silencing ANRIL group was significantly decreased when compared with that of negative control group (P<0.05), and the radiosensitivity ratio was 1.52. The apoptosis rate of the silencing ANRIL+ 4 Gy group was significantly higher than that of the negative control+ 4 Gy group ((27.86±2.78)% vs. (12.06±1.46)%, P<0.05). The results of the experiment on nude mouse transplant tumors showed that the tumor volume in the negative control group was lower than that of the silent ANRIL group on days 13, 16, 19, 22 and 25 ((234±66) mm3, (273±63) mm3, (296±72) mm3, (321±85) mm3 and (403±94) mm3vs. (357±79) mm3, (485±124) mm3, (617±143) mm3, (764±174) mm3 and (985±221) mm3P<0.05). MiR-195 is a target gene of ANRIL, and inhibition of miR-195 can reverse the inhibitory effect of silencing ANRIL on radiosensitivity, apoptosis and xenografts of HCT116 cells. Conclusions LncRNA ANRIL regulates the radiosensitivity of colorectal cancer cells by miR-195, which may provide a new sensitizing target for clinical colorectal cancer radiotherapy. Key words: ANRIL gene; miR-195 gene; HCT116 cell line; Nude mouse transplant tumors; Radiosensitivity

Silencing PSME3 induces colorectal cancer radiosensitivity by downregulating the expression of cyclin B1 and CKD1.

Resistance to radiotherapy remains a severe obstacle in the treatment of high-risk colorectal cancer patients. Recent studies have indicated that proteasome activator complex subunit 3 (PSME3) participates in the development and progression of various human malignancies and is proposed to play a role in tumor radioresistance. However, the impact of PSME3 on radioresistance of colorectal cancer has been largely unknown. In the present study, the enhanced expression of PSME3 was observed in colorectal cancer cells and tissue. Upregulation of PSME3 was significantly implicated in lymph node state, lymphovascular invasion, and Dukes' stage. Furthermore, high PSME3 expression was closely linked to poorer overall and progression-free survival in patients with colorectal cancer. The study further demonstrated that the proliferative, invasive and migratory potential of colorectal cancer cells was effectively inhibited in vitro after silencing PSME3. Our results verified that knockdown of PSME3 probably triggered cell cycle arrest at the G2/M phase by downregulation of cyclinB1 and CDK1, thereby enhancing the radiosensitivity of colorectal cancer cells. These data illustrated that PSME3 is a promising biomarker predictive of colorectal cancer prognosis and silencing of PSME3 may provide with a new approach for sensitizing the radiotherapy in colorectal cancer. Impact statement It is reported that colorectal cancer (CRC) is the third most common cancer worldwide and the fourth leading cause of cancer-related death. At present, the main treatment method of colorectal cancer is surgery, supplemented by radiotherapy and chemotherapy. Among them, radiotherapy plays an important role in the treatment of locally advanced colorectal cancer, surgery, and chemotherapy. Our study found that down-regulation of PSME3 may enhance the radiosensitivity of CRC cells by triggering cell cycle arrest, which suggests that silence PSME3 may provide a new method for improving the radiosensitivity of CRC. What’more, our research also demonstrated that PSME3 may promote proliferation, invasive and migratory potential of CRC cells, which implies that PSME3 might be a biomarker of CRC for early diagnosis and treatment.