Expression In Colorectal Cancer Cells Research Articles

Sophoridine Inhibits Human Colorectal Cancer Progression via Targeting MAPKAPK2.

Radian Sophorae flavescentis is a traditional Chinese medicine commonly used to treat cancer in China. However, its active components and underlying mechanism remain ambiguous. In this study, we have screened the pharmacokinetic parameters of the main chemical constituents of Radian Sophorae flavescentis by Traditional Chinese Medicine Systems Pharmacology (TCMSP) Database and Analysis Platform and have found that Sophoridine is one of the best antitumor active ingredients. We have found that MAPKAPK2 is a potential target for Sophoridine by the PharmMapper and KEGG databXase analysis. Moreover, we have found that Sophoridine selectively inactivates phospho-MAPKAPK2 (Thr222) and directly binds into the ATP site of MAPKAPK2 by molecular docking. Furthermore, we have found out a direct binding between MAPKAPK2 and Sophoridine by cellular thermal shift assay and drug affinity responsive targets stability assay. The inhibition effects are further confirmed by Western blot: Sophoridine significantly decreases phospho-MAPKAPK2 (Thr222) in a time-dependent manner, but there is no obvious change in its total expression in colorectal cancer cells. Clinical studies have shown that a higher level of MAPKAPK2 is associated with a poorer percent survival rate (prognosis). Furthermore, a higher level of MAPKAPK2 is positively associated with the enrichment of downregulation of apoptosis and autophagy by gene set enrichment analysis, as well as upregulation of proliferation and cell-cycle arrest. Taken together, our results suggest that the MAPKAPK2 plays a key role in Sophoridine-inhibited growth and invasion in colorectal cancers. IMPLICATIONS: These studies show that Sophoridine may be a promising therapeutic strategy that blocks tumorigenesis in colorectal cancers.

MiR-663b promotes colorectal cancer progression by activating Ras/Raf signaling through downregulation of TNK1.

MiR-663b has been demonstrated to be abnormally expressed in several cancer types and was involved in the progression of cancer. Although overexpression of miR-663b in colorectal cancer was observed, the role of miR-663b in colorectal cancer cells has not been identified yet. In this study, we analyzed expression of miR-663b in colorectal tumors and explored the molecular mechanism of miR-663b in colorectal cancer cells. MiR-663b was significantly overexpressed in colorectal tumors and cell lines. Downregulation of miR-663b inhibited cell proliferation and sphere forming ability in colorectal cancer cells. In addition, miR-663b downregulation inactivated Ras/Raf signaling activity and subsequently decreased YAP1 and CD44 expression in colorectal cancer cells. Using TargetScan software, TNK1, a negative regulator of Ras/Raf signaling, was predicted to be a target gene of miR-663b. Western blotting and RT-qPCR showed that TNK1 expression was negatively regulated by miR-663b. In addition, the direct binding of miR-663b to TNK1 mRNA was proved by dual luciferase reporter assay. Furthermore, downregulation of miR-663b inhibited colorectal cancer cell proliferation and stemness, which was reversed after siRNA-mediated silencing of TNK1. In conclusion, the current study revealed a pivotal role of miR-663b in the progression of colorectal cancer.

MiR-6803-5p Promotes Cancer Cell Proliferation and Invasion via PTPRO/NF-κB Axis in Colorectal Cancer.

Accumulated studies have implicated microRNAs (miRNAs) exert modifying effects on colorectal cancer (CRC). Protein tyrosine phosphatase, receptor type O (PTPRO) has been identified as a tumor suppressor in several kinds of cancer, including CRC. Previously, we have found that exosome-encapsulated miR-6803-5p is increased in CRC. However, the mechanism of miR-6803-5p in CRC is not clear yet. This study is aimed at elucidating the effect of miR-6803-5p in colorectal carcinogenesis. Expression of miR-6803-5p and PTPRO mRNA in peripheral blood mononuclear cells of CRC patients is estimated by real-time PCR. PTPRO protein in CRC cells is detected by western blot. To verify the association of miR-6803-5p with PTPRO, luciferase reporter assay is performed. CCK-8 and EdU assays are conducted to assess cell proliferation. Real-time PCR and ELISA are applied to detect cytokine expression in CRC cells. Cell invasion and migration assays are evaluated by transwell and scratch tests. Immunofluorescence is carried out to determine the activation of NF-κB in HCT116 cells. Negative correlation is demonstrated between miR-6803-5p and PTPRO in CRC. PTPRO is demonstrated to be a direct target of miR-6803-5p. miR-6803-5p can promote cancer cell proliferation and invasion and enhance inflammation through PTPRO/NF-κB axis in CRC, which serves as a useful target for CRC.

PLOD2 promotes aerobic glycolysis and cell progression in colorectal cancer by upregulating HK2.

The purpose of this study was to characterize the expression of procollagen-lysine, 2-oxoglutarate 5-dioxygenase 2 (PLOD2), a membrane-bound homodimeric enzyme that specifically hydroxylates lysine in the telopeptide of procollagens, and assess the clinical significance of PLOD2 in colorectal cancer (CRC). Our results show that PLOD2 is highly expressed in CRC tumor tissues and cell lines, both at the mRNA and protein levels. Next, we found that PLOD2 was positively correlated with tumor grade (P = 0.001), T stage (P = 0.001), N stage (P < 0.001), and an advanced TNM stage (P < 0.001). Knockdown of PLOD2 attenuated CRC cell proliferation, migration, and invasiveness, in vitro. Our analysis of the mechanism behind the effects of PLOD2 suggests that PLOD2 affected glycolysis by regulating the expression of hexokinase 2 (HK2). HK2 reverses the inhibitory effects of PLOD2 knockdown in CRC. Furthermore, the data suggest that PLOD2 regulates the expression of HK2 via the STAT3 signaling pathway. Survival analysis revealed that high expression levels of PLOD2 (HR = 3.800, P < 0.001) and HK2 expression (HR = 10.222, P < 0.001) correlated with the overall survival rate. After analyzing their expression and correlation, PLOD2 positively correlated with HK2 (r = 0.590, P < 0.001). Our findings have revealed that PLOD2 is a novel regulatory factor in glucose metabolism, exerted via controlling HK2 expression in CRC cells, suggesting PLOD2 as a promising therapeutic target for CRC treatment.

Long noncoding MAGI2-AS3 promotes colorectal cancer progression through regulating miR-3163/TMEM106B axis.

Colorectal cancer (CRC), is mostly derived from normal colon epithelial cells, and has been reported to be one of most common gastrointestinal malignancies globally. An increasing number of researchers have claimed that long noncoding RNAs (lncRNAs) exert significant functions in tumor progression. Nevertheless, the function of MAGI2-AS3 remains uncertain in CRC. The expression of MAGI2-AS3, miR-3163, and transmembrane protein 106B (TMEM106B) messenger RNA was examined by quantitative real-time polymerase chain reaction. Cell apoptosis was measured by caspase-3 activity test. Cell proliferation was tested by cell-counting kit 8 and 5-ethynyl-2'-deoxyuridine assays. Cell migration was detected by transwell assay. Western blot analysis examined the protein expression of TMEM106B. The expression of Ki-67 was evaluated by immunohistochemistry assay. The binding capacity between miR-3163 and MAGI2-AS3 (or TMEM106B) was studied by radioimmunoprecipitation and luciferase reporter assays. The expression of MAGI2-AS3 and TMEM106B was conspicuously upregulated whereas miR-3163 presented lower expression in CRC cells. MAGI2-AS3 deficiency facilitated cell apoptosis but hampered cell proliferation and migration. MAGI2-AS3 combined with miR-3163 and negatively regulated miR-3163 expression. In addition, the administration of sh-MAGI2-AS3 or miR-3163 mimics suppressed CRC cell growth in vivo. Subsequently, miR-3163 targeted TMEM106B and the transfection of sh-MAGI2-AS3 or miR-3163 mimics downregulated TMEM106B expression. Rescue assays verified that TMEM106B overexpression recovered the effects of MAGI2-AS3 inhibition on cell apoptosis, proliferation, and migration in CRC. MAGI2-AS3 drives CRC progression through regulating miR-3163/TMEM106B axis. This supplies innovative insights on the investigation of molecular mechanism in CRC progression.

MiR-145-5p restrained cell growth, invasion, migration and tumorigenesis via modulating RHBDD1 in colorectal cancer via the EGFR-associated signaling pathway.

miR-145-5p has been reported to be downregulated and described functioning as a tumor suppressive gene in colorectal cancer (CRC), yet its detailed regulatory function and mechanism in malignant progression of the disease have not been thoroughly understood. In our study, miR-145-5p and rhomboid domain containing 1 (RHBDD1) in CRC tissues and cells were examined by qRT-PCR and western blot. MTT, colony formation, wound healing, Transwell invasion, and flow cytometry assays were performed to evaluate the malignant phenotypes of CRC cells. Xenograft tumor, qRT-PCR, and western blot assays were applied to validate the roles and mechanism of miR-145-5p in CRC in vivo. The interaction between miR-145-5p and RHBDD1 was investigated by luciferase reporter assay and western blot. The changes of the EGFR/Raf/MEK/ERK pathway were detected by western blot. We found miR-145-5p was lowly expressed and low miR-145-5p predicted poor prognosis in CRC, while RHBDD1 was greatly enhanced in CRC cells and tissues. RHBDD1 silencing resulted in inhibiting cell proliferative, invasive, and migratory potentials as well as elevating apoptotic ones in CRC cells. miR-145-5p was inversely related with RHBDD1 expression in CRC tissues. miR-145-5p was found to directly bind to RHBDD1 and restrained its expression in CRC cells. miR-145-5p overexpression repressed CRC cell proliferation, invasion, migration and induced apoptosis, and these effects were reversed by RHBDD1 upregulation. Moreover, in CRC xenograft tumor, its growth was impeded by miR-145-5p via suppressing RHBDD1. Furthermore, miR-145-5p inhibited the expression of EGFR, p-MEK1/2 and p-ERK1/2, in vitro and in vivo by targeting RHBDD1. In conclusion, our study revealed that miR-145-5p overexpression inhibited tumorigenesis in CRC by downregulating RHBDD1 via suppressing the EGFR-associated signaling pathway (EGFR/Raf/MEK/ERK cascades).

Targeting bromodomain-containing protein 4 (BRD4) inhibits MYC expression in colorectal cancer cells

The transcriptional regulator BRD4 has been shown to be important for the expression of several oncogenes including MYC. Inhibiting of BRD4 has broad antiproliferative activity in different cancer cell types. The small molecule JQ1 blocks the interaction of BRD4 with acetylated histones leading to transcriptional modulation. Depleting BRD4 via engineered bifunctional small molecules named PROTACs (proteolysis targeting chimeras) represents the next-generation approach to JQ1-mediated BRD4 inhibition. PROTACs trigger BRD4 for proteasomale degradation by recruiting E3 ligases. The aim of this study was therefore to validate the importance of BRD4 as a relevant target in colorectal cancer (CRC) cells and to compare the efficacy of BRD4 inhibition with BRD4 degradation on downregulating MYC expression. JQ1 induced a downregulation of both MYC mRNA and MYC protein associated with an antiproliferative phenotype in CRC cells. dBET1 and MZ1 induced degradation of BRD4 followed by a reduction in MYC expression and CRC cell proliferation. In SW480 cells, where dBET1 failed, we found significantly lower levels of the E3 ligase cereblon, which is essential for dBET1-induced BRD4 degradation. To gain mechanistic insight into the unresponsiveness to dBET1, we generated dBET1-resistant LS174t cells and found a strong downregulation of cereblon protein. These findings suggest that inhibition of BRD4 by JQ1 and degradation of BRD4 by dBET1 and MZ1 are powerful tools for reducing MYC expression and CRC cell proliferation. In addition, downregulation of cereblon may be an important mechanism for developing dBET1 resistance, which can be evaded by incubating dBET1-resistant cells with JQ1 or MZ1.

MiR-140-3p Suppresses Cell Growth And Induces Apoptosis In Colorectal Cancer By Targeting PD-L1.

BackgroundA variety of miRNAs have been recently reported to be abnormally expressed in colorectal cancer (CRC). A growing number of studies have demonstrated that aberrantly expressed miRNAs are closely related to the development and progression of CRC. It has been found that miR-140-3p plays a vital role in several cancers. However, its expression, roles and mechanisms in CRC are remain unknown.Materials and methodsReverse transcription-quantitative polymerase chain reaction (RT-qPCR) were used to determine miR-140-3p expression in CRC tissues and cell lines. CCK8, migration, invasion and flow cytometric assays were used to determine the influence of miR-140-3p upregulation on cell proliferation, migration, invasion and apoptosis of CRC cells. Luciferase reporter assays and Western blots were utilized to identify the target genes of miR-140-3p. In addition, the potential mechanism of miR-140-3p action in CRC cells was elucidated.ResultsIn our study, miR-140-3p expression was significantly decreased in CRC tissues and cell lines. Overexpression of miR-140-3p attenuated proliferation, migration, and invasion and induced the apoptosis of CRC cells. Bioinformatics analyse and luciferase reporter analysis identified PD-L1 as a putative target gene of miR-140-3p. PD-L1 was overexpressed in CRC tissues and inversely correlated with miR-140-3p expression. Suppression of PD-L1 expression in CRC cells generated biological behaviours in CRC cells that were similar to those observed after treated with miR-140-3p mimics. Restoration of PD-L1 expression partially attenuated the inhibitory effect of miR-140-3p on CRC cells. Western blot were used to verify the effect of PD-L1 expression on PI3K/AKT pathway. In addition, overexpression of miR-140-3p could inhibit CRC tumor growth in vivo.ConclusionIn general, these data demonstrate that miR-140-3p acts as a tumour suppressor in CRC by directly targeting PD-L1 and inactivating PI3K/AKT pathway, suggesting that miR-140-3p might be a novel target for CRC diagnosis and treatment.

Intratumoral Cytotoxic T-Lymphocyte Density and PD-L1 Expression Are Prognostic Biomarkers for Patients with Colorectal Cancer.

Background and objectives: Cytotoxic T-lymphocyte (CTL)-mediated inflammatory response to tumors plays a crucial role in preventing the progression of some cancers. Programmed cell death ligand 1 (PD-L1), a cell-surface glycoprotein, has been reported to repress T-cell-mediated immune responses against tumors. However, the clinical significance of PD-L1 in colorectal cancer (CRC) remains unclear. Our aim was to elucidate the prognostic significance of PD-L1 expression and CD8+ CTL density in CRC. Materials and methods: CD8 and PD-L1 immunostaining was conducted on 157 pathologic specimens from patients with CRC. The CD8+ CTL density and PD-L1 expression within the tumor microenvironment were assessed by immunohistochemistry. Results: Tumor invasion (pT) was significantly correlated with intratumoral (p = 0.011) and peritumoral (p = 0.016) CD8+ CTLs density in the tumor microenvironment. In addition, there was a significant difference in the intensity of CD8+ CTLs between patients with and without distant metastases (intratumoral p = 0.007; peritumoral p = 0.037, T-test). Lymph node metastasis (pN) and TNM stage were significantly correlated with PD-L1 expression in CRC cells (p = 0.015, p = 0.029, respectively). Multivariate analysis revealed a statistically significant relationship between the intratumoral CD8+ CTL density and disease-free survival (DFS) (hazard ratio [HR] 2.06; 95% confidence interval [CI]: 1.01–4.23; p = 0.043). The DFS was considerably shorter in patients with a high expression of PD-L1 in cancer cells than those with a low expression (univariate HR 2.55; 95% CI 1.50–4.34; p = 0.001; multivariate HR 0.48; 95% CI 0.28–0.82; p = 0.007). Conversely, patients with high PD-L1 expression in tumor-infiltrating lymphocytes had a longer DFS in both univariate analysis (HR 0.25; 95% CI: 0.14–0.44; p < 0.001) and multivariate analysis (HR 3.42; 95% CI: 1.95–6.01; p < 0.001). Conclusion: The CD8+ CTL density and PD-L1 expression are prognostic biomarkers for the survival of patients with CRC.

MicroRNA-520e targets AEG-1 to suppress the proliferation and invasion of colorectal cancer cells through Wnt/GSK-3β/β-catenin signalling.

MicroRNA-520e (miR-520e) is increasingly being recognized as a cancer-related miRNA in multiple cancer types; however, little is known about its role in colorectal cancer. In this study, we determined the specific role of miR-520e in colorectal cancer. Expression of miR-520e was lower in colorectal cancer tissues compared to normal tissues. Overexpression of miR-520e significantly decreased the proliferation, colony formation and invasion of colorectal cancer cells, while inhibition of miR-520e exhibited the opposite effect. Moreover, miR-520e was found to target the 3'-untranslated region of astrocyte elevated gene-1 (AEG-1) and inhibit AEG-1 expression in colorectal cancer cells. An inverse correlation between miR-520e and AEG-1 expression was confirmed in colorectal cancer tissues. Notably, miR-520e suppressed the phosphorylation of glycogen synthase kinase-3β and decreased the expression of β-catenin, leading to inactivation of Wnt/β-catenin signalling in colorectal cells. A rescue assay confirmed that miR-520e regulates cell proliferation, invasion and Wnt/β-catenin signalling through targeting AEG-1. Taken together, these results indicate that miR-520e plays a critical role in regulating colorectal cancer cell proliferation and invasion by inhibiting Wnt/β-catenin signalling via AEG-1. Our study highlights the importance of the miR-520e/AEG-1/Wnt/β-catenin signalling axis in colorectal cancer, thus targeting miR-520e may represent an effective therapeutic strategy.

SNAIL1 employs β-Catenin-LEF1 complexes to control colorectal cancer cell invasion and proliferation.

The transcription factor SNAIL1 is a master regulator of epithelial-to-mesenchymal transition (EMT), a process entailing massive gene expression changes. To better understand SNAIL1-induced transcriptional reprogramming we performed time-resolved transcriptome analysis upon conditional SNAIL1 expression in colorectal cancer cells. Gene set variation analyses indicated that SNAIL1 strongly affected features related to cell cycle and Wnt/β-Catenin signalling. This correlated with upregulation of LEF1, a nuclear binding partner of β-Catenin. Likewise, transcriptomes of cell lines and colorectal cancers, including poor-prognosis mesenchymal tumours, exhibit positively correlated SNAI1 and LEF1 expression, and elevated LEF1 levels parallel increased patient mortality. To delineate the functional contribution of LEF1 to SNAIL1-induced EMT, we used the CRISPR/Cas9 system to knock-out LEF1 in colorectal cancer cells, and to engineer cells that express LEF1 mutants unable to interact with β-Catenin. Both complete LEF1-deficiency and prevention of the β-Catenin-LEF1 interaction impaired the ability of SNAIL1 to elicit expression of an alternative set of Wnt/β-catenin targets, and to promote cancer cell invasion. Conversely, overexpression of wildtype, but not of mutant LEF1, stimulated alternative Wnt/β-Catenin target gene expression, and caused cell-cycle arrest. Moreover, like SNAIL1, LEF1 retarded tumour growth in xenotransplantations. Thus, LEF1 phenocopies SNAIL1 with respect to several critical aspects of EMT. Indeed, comparative transcriptomics suggested that 35% of SNAIL1-induced transcriptional changes are attributable to LEF1. However, LEF1 did not autonomously induce EMT. Rather, LEF1 appears to be a strictly β-Catenin-dependent downstream effector of SNAIL1. Apparently, SNAIL1 employs β-Catenin-LEF1 complexes to redirect Wnt/β-Catenin pathway activity towards pro-invasive and anti-proliferative gene expression.

MiR-532 promotes colorectal cancer invasion and metastasis by targeting NKD1

The aim of this study was to investigate the effect of microRNA-532 (miR-532) on invasion and metastasis of colorectal cancer (CRC) cells, and the underlying mechanism. Human CRC cell line (HCT116) and normal colon (FHC) cells were used for this study. The cells were transfected with naked cuticle homolog 1 (NKD1) overexpression plasmid, miR-532 mimics, miR-532 inhibitor or miR-532 non-homologous sequence using lipofectamine 2000. Real-time quantitative polymerase chain reaction (qRT-PCR) was used to determine the expression of miR-532 in CRC cells, and a combination of scratch and Transwell assays was used to assess the effect of miR-532 on migration and invasion of CRC cells. Western blotting was used to determine the effect of miR-532 on NKD1 expression in CRC cells. Bioinformatics analysis and luciferase reporter gene assay were used to assess the regulatory effect of miR-532 on NKD1. The expression of miR-532 was upregulated in CRC cells relative to normal colon cells (p &lt; 0.05). The HCT116 cells transfected with miR-532 mimics migrated faster than those of miR-532 negative control (miR532-NC) group (p &lt; 0.05). The migration ability of HCT116 cells transfected with miR-532 inhibitor was significantly reduced, when compared with that of miR532-NC group (p &lt; 0.05). The invasive ability of HCT116 cells transfected with miR-532 mimics was significantly higher than that of miR532-NC cells (p &lt; 0.05). However, inhibition of miR-532 expression significantly reduced the invasive ability of HCT116 cells (p &lt; 0.05). Results of bioinformatics showed that miR-532 had specific binding sequence with the 3'UTR region of NKD1. After cloning the sequence into the luciferase reporter plasmid, miR-532 significantly inhibited the expression of NKD1 (p &lt; 0.05). However, miR-532 had no inhibitory effect on mutated NKD1 3'UTR (p &gt; 0.05). Results of Western blotting showed that increased miR-532 expression significantly reduced the expression of NKD1, while decreased miR-532 expression promoted the expression of NKD1 (p &lt; 0.05). Overexpression of NKD1 significantly down-regulated miR-532 overexpression and promoted CRC cell invasion and metastasis (p &lt; 0.05). miR-532 is highly expressed in CRC cells and directly inhibits NKD1 expression, while enhancing invasion and metastasis of CRC cells. It promotes the development of CRC by inhibiting the expression of NKD1.

ZEB1 promotes inflammation and progression towards inflammation-driven carcinoma through repression of the DNA repair glycosylase MPG in epithelial cells

ObjectiveChronic inflammation is a risk factor in colorectal cancer (CRC) and reactive oxygen species (ROS) released by the inflamed stroma elicit DNA damage in epithelial cells. We sought to identify...

MiR‑501‑3p promotes colorectal cancer progression via activation of Wnt/β‑catenin signaling

Aberrant activation of Wnt/β-catenin signaling is observed in >90% of colorectal cancer cases. microRNAs (miRNAs) regulate the expression of key genes in Wnt/β-catenin signaling. As a result, abnormal expression of miRNAs regulates the activation of Wnt/β-catenin signaling in several types of cancer. In the current study, it was demonstrated that miR-501-3p was overexpressed in colorectal tumor tissues compared to the adjacent normal tissues. Downregulation of miR-501-3p inhibited cell proliferation and sphere formation, while it induced cell cycle arrest at the G1 phase in colorectal cancer cells. Bioinformatics analysis results predicted that adenomatous polyposis coli (APC), a negative regulator of Wnt/β-catenin signaling, was a potential target gene of miR-501-3p. Inhibition of miR-501-3p increased APC expression in colorectal cancer cells. Additionally, β-catenin was destabilized following miR-501-3p inhibition; immunofluorescence analysis revealed that β-catenin translocated from nucleus to cytoplasm. In addition, cyclin D1 and c-Myc, two well-characterized target genes of Wnt/β-catenin signaling, were downregulated following miR-501-3p inhibition. Transfection of APC small interfering RNA re-activated β-catenin and stimulated the expression of cyclin D1 and c-Myc. Furthermore, silencing of APC reversed the miR-501-3p inhibitor-induced cell cycle disruption, and the inhibition of cell proliferation and sphere formation in colorectal cancer cells. In conclusion, the present study identified miR-501-3p as a novel regulator of Wnt/β-catenin signaling in colorectal cancer cells via targeting APC, suggesting that miR-501-3p may act as a novel oncogenic miRNA in colorectal cancer.

A novel lncRNA NR4A1AS up-regulates orphan nuclear receptor NR4A1 expression by blocking UPF1-mediated mRNA destabilization in colorectal cancer.

Long non-coding RNAs (lncRNAs) play important roles in tumorigenesis and cancer progression. The orphan nuclear receptor subfamily 4 group A member 1 (NR4A1) acts as an oncogene, and is involved in colorectal cancer (CRC) development. However, the mechanism through which lncRNA regulates NR4A1 expression remains unknown. We aimed to identify lncRNAs that regulate NR4A1 and assess their underlying mechanisms in CRC. We first identified an antisense lncRNA of NR4A1 that was up-regulated in CRC tissues and cells with rapid amplification of cDNA ends (RACE), and designated it as NR4A1AS. Spearman correlation analysis showed that NR4A1AS was positively correlated with NR4A1 mRNA levels in 37 CRC tissues. Mechanistically, NR4A1AS stabilized NR4A1 mRNA by forming RNA-RNA complexes via partial base-pairing and up-regulated NR4A1 expression in CRC cells. RNA immunoprecipitation (RIP) assays revealed that knockdown of NR4A1AS expression by siRNA enhanced up-frameshift 1 (UPF1) recruitment to NR4A1 mRNA, thereby decreasing NR4A1 mRNA stability. Moreover, depletion of NR4A1AS was found to mimic the effect of NR4A1 knockdown, specifically by suppressing cell proliferation, migration and invasion, and inducing apoptosis and cell cycle arrest. Accordingly, restoring NR4A1 expression ameliorated the effects of NR4A1AS knockdown on tumor growth and metastasis of CRC cells in vitro and in vivo Thus, we conclude that NR4A1AS up-regulates NR4A1 expression by forming RNA-RNA complexes and blocking UPF1-mediated mRNA destabilization, and it functions in tumor growth and metastasis of CRC cells at least partly through regulating NR4A1, suggesting that NR4A1AS might be as a potential target for RNA-based anti-CRC drug studies.

Abstract 4375: Overexpression of CD36 promotes colorectal cancer cell proliferation via upregulation of survivin

Abstract Altered fatty acid metabolism has is a hallmark of cancer and continues to be a potential target for therapeutic intervention in cancer. Fatty Acid Translocase (CD36), a multifunctional glycoprotein, has been shown to have an important role in fatty acid metabolism as a fatty acid transporter. Fatty Acid Synthase (FASN), a critical enzyme involved in de novo lipogenesis, has been shown to be upregulated and associated with a poor prognosis in many cancers including colorectal cancer (CRC). However, the role of CD36 in CRC as well as its relation to de novo fatty acid synthesis is not understood. The purpose of our study was: (i) to determine the functional importance of CD36 in CRC and (ii) investigate potential relationships between CD36 and FASN expression in CRC cells. METHODS. Expression of CD36 and FASN was assessed by immunohistochemistry (IHC) using a CRC TMA with 2 sets of tissues: (i) Primary tumors with matched normal colon tissue; [n=56]; (ii) primary and metastatic tumors (liver [n=12] and lung metastasis [n=5]) with matched normal colon. Cellular proliferation was assessed in control and CD36 shRNA knockdown CRC cells, and in primary CRC cells established from patient derived xenografts treated with CD36 inhibitor Sulfo-N-succinimidyl oleate (SSO) in combination with FASN inhibitor TVB-3664. CD36 knockdown was confirmed by qRT-PCR. Expression of pro-survival and apoptotic markers was assessed via western blot in CD36 knockdown and overexpression CRC cells, as well as CD36+ and CD36- isogenic cells. CD36 localization was assessed via confocal imaging. RESULTS. We found that CD36 is overexpressed in primary tumors as compared to normal colon mucosa and its expression positively correlates with expression of FASN. Cellular proliferation was significantly reduced when CD36 was inhibited by SSO and a further reduction in proliferation was observed when SSO treatment was combined with TVB-3664. Knockdown and chemical inhibition of CD36 decreased expression of survivin, a member of the inhibitor of apoptosis (IAP) family of proteins, which was shown to promote cancer cell survival in many tumor types. Conversely, overexpression of CD36 increased survivin expression in CRC cells. Additionally, shRNA knockdown of FASN induced CD36 expression in CRC cells. Immunofluorescence imaging of primary CRC cells treated with TVB-3664 showed an upregulation of membrane-bound CD36. CONCLUSION. Our studies indicate that CD36 upregulation is associated with an increase in cellular proliferation via upregulation of survivin in CRC cells. The correlation between CD36 expression and FASN suggest a connection between CD36 and de novo lipid synthesis. Furthermore, a decrease in FASN expression is associated with CD36 induction, suggesting a possible mechanism of resistance to FASN inhibition. Better understanding of the role of CD36 in CRC may provide new therapeutic approaches for treatment of CRC patients Citation Format: James Drury, Naser Jafari, B. Mark Evers Evers, Yekaterina Y. Zaytseva. Overexpression of CD36 promotes colorectal cancer cell proliferation via upregulation of survivin [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4375.

Long non-coding RNA GClnc1 promotes progression of colorectal cancer by inhibiting p53 signaling pathway.

The aim of this study was to investigate whether long non-coding RNA (lncRNA) GClnc1 was involved in the development of colorectal cancer, and to explore its possible mechanisms. Quantitative Real Time-Polymerase Chain Reaction (qRT-PCR) was conducted to detect GClnc1 expression in 48 colorectal cancer tissues and normal colon tissues. The Kaplan-Meier method was used to analyze the relationship between GClnc1 expression and survival rate of patients with colorectal cancer. In addition, GClnc1 expression in colorectal cancer cell lines and normal colonic epithelial cell lines were analyzed. After knockdown and over-expression of GClnc1 in colorectal cancer cells, Cell Counting Kit-8 (CCK-8) and colony formation assay were performed to detect the viability and proliferation of cells, respectively. RNA pull-down and RNA-binding protein immunoprecipitation (RIP) were applied to examine the specific interaction between GClnc1 and p53. After over-expression of GClnc1 in colorectal cancer cells, qPCR and Western blot were performed to evaluate the expression levels of p53, p21 and BAX. Meanwhile, the Luciferase reporter gene assay was established to reveal the activity of p53 after over-expression of GClnc1. ChIP assay was applied to figure out whether GClnc1 could affect the binding ability of p53 to the promoter region of p21. After p53 or GClnc1 knock-down in colorectal cancer cells, the protein level of p53 was analyzed using Western blot. Finally, qRT-PCR, CCK-8 and colony formation assay were used to detect the levels of p21 and BAX, the viability, as well as the proliferation ability of cells, respectively. The expression of GClnc1 in colorectal cancer tissues was significantly higher than that of para-cancerous tissues. Meanwhile, GClnc1 expression in T3 and T4 tumors was markedly higher than that of T1 and T2. The survival analysis revealed that patients with a higher level of GClnc1 showed remarkably lower overall survival than those with lower expression of GClnc1. QRT-PCR results indicated that GClnc1 expression in colorectal cancer cells (including SW620 and HCT116) was conspicuously higher than that of normal colonic epithelial cells (NCM640). After knocking down GClnc1 in SW620 cells, the viability and proliferation abilities were conspicuously decreased. Meanwhile, the expression level of GClnc1, as well as the viability and colony formation ability of cells, were significantly increased after over-expression of GClnc1 in HCT116 cells. Subsequently, the qRT-PCR assay demonstrated that GClnc1 was mainly localized in the nucleus. RNA pull-down and RIP experiments revealed that there was a specific interaction between GClnc1 and p53. Moreover, qRT-PCR and Western blot analysis indicated that the expression level of p53 was not affected after over-expression of GClnc. However, the expressions of p21 and BAX were remarkably decreased. The Luciferase reporter gene assay revealed that GClnc1 over-expression markedly weakened the Luciferase activity of p53. Meanwhile, ChIP experiments demonstrated that GClnc1 up-regulation affected the binding condition of p53 to p21. Western blot analysis showed that knockdown of p53 reversed the increased mRNA level of p21 as well as BAX. Furthermore, p53 down-regulation significantly weakened cell viability and colony formation ability caused by knockdown of GClnc1. LncRNA GClnc1 was highly expressed in colorectal cancer tissues. Meanwhile, it could increase the proliferation of colorectal cancer cells by reducing the expression of p21 as well as BAX via p53 signaling pathway, thereby promoting the progression of colorectal cancer.

MiR-873-5p suppresses cell proliferation and epithelial\u2013mesenchymal transition via directly targeting Jumonji domain-containing protein 8 through the NF-\u03baB pathway in colorectal cancer

Colorectal cancer (CRC) is one of the most common leading causes of cancer-related deaths in the world. Recent studies showed that microRNAs (miRNAs) play important roles in the development of diseases, such as CRC. However, the role of miR-873-5p in CRC remains unclear. In this study, we found that miR-873-5p expression was down-regulated in CRC tissues and cell lines, and the down-regulation of miR-873-5p expression was associated with poor survival in patients with CRC. MiR-873-5p could function as a tumour suppressor in CRC. It could inhibit the growth, proliferation, migration and invasion of CRC cells; influence the cell cycle and enhance apoptosis of CRC cells. Bioinformatics and luciferase reporter analyses demonstrated that Jumonji domain-containing protein 8 (JMJD8) was a target of miR-873-5p that could directly target the 3’UTR of JMJD8 and significantly inhibit its expression in CRC cells. This study also verified that JMJD8 functioned as an oncogene in CRC cells. The over-expression of JMJD8 could partly save the harmful effects induced by miR-873-5p in CRC cells, demonstrating that miR-873-5p suppressed carcinogenesis by targeting JMJD8 in CRC. We also verified that miR-873-5p over-expression could suppress CRC cell growth by inhibiting JMJD8 and its downstream NF-κB pathway in CRC. Hence, miR-873-5p inhibited tumour growth, and it may be a potential biomarker and a promising treatment for CRC.

Induction of let-7e gene expression attenuates oncogenic phenotype in HCT-116 colorectal cancer cells through targeting of DCLK1 regulation

AimsMicroRNAs (miRNAs) are small noncoding RNAs that negatively control gene expression at the translational level. There are compelling evidences indicating that the expression of let-7e is downregulated in various cancers, however, the role of let-7e in colorectal cancer (CRC) and its mechanism has been remained unknown. Here, we investigated the potential role of let-7e in regulating CRC cells phenotypes. Main methodsLet-7e and DCLK1 siRNA were transfected in HCT-116 cells. Colony formation assay, scratch test, Annexin V/PI flow cytometry, and sphere formation assay were performed to examine the cell proliferation, migration, apoptosis, and stemness, respectively. The expression of let-7e, epithelial-mesenchymal transition (EMT)-related genes, Doublecortin like kinase protein 1 (DCLK1), and cancer stem cells (CSCs) were assessed using RT-qPCR while the protein level of DCLK1 was determined by western blotting. Key findingsOverexpression of let-7e effectively inhibited cell proliferation, suppressed migration, reduced sphere formation, and precluded EMT process as well as stemness factors. Furthermore, let-7e suppressed DCLK1 expression. Additionally, we found that the expression of let-7e was negatively correlated with DCLK1 expression in CRC cells. SignificanceLet-7e plays an important role as tumor suppressor miRNA in CRC probably through inhibition of DCLK1 expression.

Tumour-Derived Laminin α5 (LAMA5) Promotes Colorectal Liver Metastasis Growth, Branching Angiogenesis and Notch Pathway Inhibition.

Hepatic metastatic growth is dependent upon stromal factors including the matrisomal proteins that make up the extracellular matrix (ECM). Laminins are ECM glycoproteins with several functions relevant to tumour progression including angiogenesis. We investigated whether metastatic colon cancer cells produce the laminins required for vascular basement membrane assembly as a mechanism for the promotion of angiogenesis and liver metastasis growth. qPCR was performed using human-specific primers to laminin chains on RNA from orthotopic human colorectal liver metastases. Laminin α5 (LAMA5) expression was inhibited in colon cancer cells using shRNA. Notch pathway gene expression was determined in endothelia from hepatic metastases. Orthotopic hepatic metastases expressed human laminin chains α5, β1 and γ1 (laminin 511), all of which are required for vascular basement membrane assembly. The expression of Laminin 511 was associated with reduced survival in several independent colorectal cancer cohorts and angiogenesis signatures or vessel density significantly correlated with LAMA5 expression. Colorectal cancer cells in culture made little LAMA5, but its levels were increased by culture in a medium conditioned by tumour-derived CD11b+ myeloid cells through TNFα/NFκB pathway signalling. Down-regulation of LAMA5 in cancer cells impaired liver metastatic growth and resulted in reduced intra-tumoural vessel branching and increased the expression of Notch pathway genes in metastasis-derived endothelia. This data demonstrates a mechanism whereby tumour inflammation induces LAMA5 expression in colorectal cancer cells. LAMA5 is required for the successful growth of hepatic metastases where it promotes branching angiogenesis and modulates Notch signalling.