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Background: Colorectal cancer (CRC) is a major cause of cancer-related deaths worldwide, and chemoresistance is a major obstacle in its treatment. Despite advances in therapy, the molecular mechanism underlying chemoresistance in CRC is not fully understood. Recent studies have implicated the key roles of long noncoding RNAs (lncRNAs) in the regulation of CRC chemoresistance., Methods: In this study, we investigated the role of the lncRNA LINC01852 in CRC chemoresistance. LINC01852 expression was evaluated in multiple CRC cohorts using quantitative reverse transcription PCR. We conducted in vitro and in vivo functional experiments using cell culture and mouse models. RNA pull-down, RNA immunoprecipitation, chromatin immunoprecipitation, and dual luciferase assays were used to investigate the molecular mechanism of LINC01852 in CRC., Results: Our findings revealed that a lncRNA with tumor-inhibiting properties, LINC01852, was downregulated in CRC and inhibited cell proliferation and chemoresistance both in vitro and in vivo. Further mechanistic investigations revealed that LINC01852 increases TRIM72-mediated ubiquitination and degradation of SRSF5, inhibiting SRSF5-mediated alternative splicing of PKM and thereby decreasing the production of PKM2. Overexpression of LINC01852 induces a metabolic switch from aerobic glycolysis to oxidative phosphorylation, which attenuates the chemoresistance of CRC cells by inhibiting PKM2-mediated glycolysis., Conclusions: Our results demonstrate that LINC01852 plays an important role in repressing CRC malignancy and chemoresistance by regulating SRSF5-mediated alternative splicing of PKM, and that targeting the LINC01852/TRIM72/SRSF5/PKM2 signaling axis may represent a potential therapeutic strategy for CRC., (© 2024. The Author(s).)

Long noncoding RNAs (lncRNAs) play an important role in tumor progression. Small nucleolar RNA host gene 15 (SNHG15) is a lncRNA that has been confirmed to play an oncogenic role in multiple cancer types. However, its role in glycolysis and chemoresistance in colorectal cancer (CRC) is unclear. The expression of SNHG15 in CRC was analyzed using data from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases by bioinformatics methods. Cell Counting Kit-8 (CCK-8) and colony formation assays were used to evaluate cell viability. Cell sensitivity to 5-fluorouracil (5-FU) was detected by CCK-8. Glucose absorption and lactate production were used to evaluate the impact of SNHG15 on glycolysis. RNA-seq, real-time fluorescence quantitative reverse transcription PCR (RT-qPCR) and Western blotting (WB) were used to reveal the potential molecular mechanism of SNHG15 in CRC. SNHG15 was upregulated in CRC tissues compared with paired noncancerous tissues. Ectopic SNHG15 expression increased proliferation, 5-FU chemoresistance, and glycolysis in CRC cells. In contrast, SNHG15 knockdown inhibited CRC proliferation, 5-FU chemoresistance and glycolysis. Multiple pathways, including apoptosis and glycolysis, were potentially regulated by SNHG15 based on RNA-seq and pathway enrichment analyses. RT-qPCR and WB experiments confirmed that SNHG15 promoted the expression of TYMS, BCL2, GLUT1 and PKM2 in CRC cells. In conclusion, SNHG15 promotes 5-FU chemoresistance and glycolysis in CRC by potentially regulating the expression of TYMS, BCL2, GLUT1 and PKM2 and appears to be a new target for cancer therapy., Competing Interests: Declaration of Competing Interest The authors have no conflicts of interest to declare., (Copyright © 2023 The Authors. Published by Elsevier GmbH.. All rights reserved.)

Signaling receptor and transporter of retinol STRA6 (STRA6) plays a primary role in transporting retinol. Several studies have reported that STRA6 is involved in several pathways related to tumorigenesis and progression. However, the exact functions and mechanisms of STRA6 in colorectal cancer (CRC) remain unclear. In our work, STRA6 was highly up-regulated in CRC and promoted the proliferation of CRC cells. Additionally, we discovered that STRA6 suppresses apoptosis partly by controlling BCL2 expression, which in turn causes CRC to become resistant to LOHP treatment. Our study demonstrates that STRA6 is a potential prognostic factor and oncogene in CRC by promoting CRC growth and chemoresistance., Competing Interests: Declaration of Competing Interest The authors report no declarations of interest., (Copyright © 2023 Elsevier GmbH. All rights reserved.)

Background: Long noncoding RNAs (lncRNAs) have driven research focused on their effects as oncogenes or tumor suppressors involved in carcinogenesis. However, the functions and mechanisms of most lncRNAs in colorectal cancer (CRC) remain unclear., Methods: The expression of DLGAP1-AS2 was assessed by quantitative RT-PCR in multiple CRC cohorts. The impacts of DLGAP1-AS2 on CRC growth and metastasis were evaluated by a series of in vitro and in vivo assays. Furthermore, the underlying mechanism of DLGAP1-AS2 in CRC was revealed by RNA pull down, RNA immunoprecipitation, RNA sequencing, luciferase assays, chromatin immunoprecipitation, and rescue experiments., Results: We discovered that DLGAP1-AS2 promoted CRC tumorigenesis and metastasis by physically interacting with Elongin A (ELOA) and inhibiting its protein stability by promoting tripartite motif containing 21 (Trim21)-mediated ubiquitination modification and degradation of ELOA. In particular, we revealed that DLGAP1-AS2 decreases phospholysine phosphohistidine inorganic pyrophosphate phosphatase (LHPP) expression by inhibiting ELOA-mediated transcriptional activating of LHPP and thus blocking LHPP-dependent suppression of the AKT signaling pathway. In addition, we also demonstrated that DLGAP1-AS2 was bound and stabilized by cleavage and polyadenylation specificity factor (CPSF2) and cleavage stimulation factor (CSTF3)., Conclusions: The discovery of DLGAP1-AS2, a promising prognostic biomarker, reveals a new dimension into the molecular pathogenesis of CRC and provides a prospective treatment target for this disease., (© 2022. The Author(s).)

Background: SLCO4A1-AS1 was found to be upregulated in several cancer types, including colorectal cancer (CRC). However, the detailed roles of SLCO4A1-AS1 in CRC remain to be elucidated. Therefore, we investigated the functions, mechanism, and clinical significance of SLCO4A1-AS1 in colorectal tumourigenesis., Methods: We measured the expression of SLCO4A1-AS1 in CRC tissues using qRT-PCR and determined its correlation with patient prognosis. Promoter methylation analyses were used to assess the methylation status of SLCO4A1-AS1. Gain- and loss-of-function assays were used to evaluate the effects of SLCO4A1-AS1 on CRC growth in vitro and in vivo. RNA pull-down, RNA immunoprecipitation, RNA-seq, luciferase reporter and immunohistochemistry assays were performed to identify the molecular mechanism of SLCO4A1-AS1 in CRC., Results: SLCO4A1-AS1 was frequently upregulated in CRC tissues based on multiple CRC cohorts and was associated with poor prognoses. Aberrant overexpression of SLCO4A1-AS1 in CRC is partly attributed to the DNA hypomethylation of its promoter. Ectopic SLCO4A1-AS1 expression promoted CRC cell growth, whereas SLCO4A1-AS1 knockdown repressed CRC proliferation both in vitro and in vivo. Mechanistic investigations revealed that SLCO4A1-AS1 functions as a molecular scaffold to strengthen the interaction between Hsp90 and Cdk2, promoting the protein stability of Cdk2. The SLCO4A1-AS1-induced increase in Cdk2 levels activates the c-Myc signalling pathway by promoting the phosphorylation of c-Myc at Ser62, resulting in increased tumour growth., Conclusions: Our data demonstrate that SLCO4A1-AS1 acts as an oncogene in CRC by regulating the Hsp90/Cdk2/c-Myc axis, supporting SLCO4A1-AS1 as a potential therapeutic target and prognostic factor for CRC., (© 2022. The Author(s).)

Tumor-associated macrophages (TAMs) are one of the most abundant cell types in colorectal cancer (CRC) tumor microenvironment (TME). Recent studies observed complicated "cross-talks" between cancer cells and macrophages in TME. However, the underlying mechanisms are still poorly elucidated. Here, PD-L1 levels are very low in CRC cells but highly abundant in TAMs, and a specific PD-L1 + CD206 + macrophage subpopulation are identified, which is induced by tumor cells and associated with a poor prognosis. Mechanistic investigations reveal that CRC cells can secrete small extracellular vesicles (sEVs) taken up by macrophages that induce M2 like polarization and PD-L1 expression, resulting in increased PD-L1 + CD206 + macrophage abundance and decreased T cell activity in CRC TME. sEV-derived miR-21-5p and miR-200a are identified as key signaling molecules mediating the regulatory effects of CRC on macrophages. Further studies reveal that CRC-derived miR-21-5p and miR-200a synergistically induces macrophage M2 like polarization and PD-L1 expression by regulating the PTEN/AKT and SCOS1/STAT1 pathways, resulting in decreased CD8 + T cell activity and increased tumor growth. This study suggests that inhibiting the secretion of specific sEV-miRNAs from CRC and targeting PD-L1 in TAMs may serve as novel methods for CRC treatment as well as a sensitization method for anti-PD-L1 therapy in CRC., Competing Interests: The authors declare no conflict of interest., (© 2022 The Authors. Advanced Science published by Wiley‐VCH GmbH.)

Background: Small nucleolar RNA host gene (SNHG) long noncoding RNAs (lncRNAs) are frequently dysregulated in human cancers and involved in tumorigenesis and progression. SNHG17 has been reported as a candidate oncogene in several cancer types, however, its regulatory role in colorectal cancer (CRC) is unclear., Methods: SNHG17 expression in multiple CRC cohorts was assessed by RT-qPCR or bioinformatic analyses. Cell viability was evaluated using Cell Counting Kit-8 (CCK-8) and colony formation assays. Cell mobility and invasiveness were assessed by Transwell assays. Tumor xenograft and metastasis models were applied to confirm the effects of SNHG17 on CRC tumorigenesis and metastasis in vivo. Immunohistochemistry staining was used to measure protein expression in cancer tissues. RNA pull-down, RNA immunoprecipitation, chromatin immunoprecipitation, and dual luciferase assays were used to investigate the molecular mechanism of SNHG17 in CRC., Results: Using multiple cohorts, we confirmed that SNHG17 is aberrantly upregulated in CRC and correlated with poor survival. In vitro and in vivo functional assays indicated that SNHG17 facilitates CRC proliferation and metastasis. SNHG17 impedes PES1 degradation by inhibiting Trim23-mediated ubiquitination of PES1. SNHG17 upregulates FOSL2 by sponging miR-339-5p, and FOSL2 transcription activates SNHG17 expression, uncovering a SNHG17-miR-339-5p-FOSL2-SNHG17 positive feedback loop., Conclusions: We identified SNHG17 as an oncogenic lncRNA in CRC and identified abnormal upregulation of SNHG17 as a prognostic risk factor for CRC. Our mechanistic investigations demonstrated, for the first time, that SNHG17 promotes tumor growth and metastasis through two different regulatory mechanisms, SNHG17-Trim23-PES1 axis and SNHG17-miR-339-5p-FOSL2-SNHG17 positive feedback loop, which may be exploited for CRC therapy., (© 2021. The Author(s).)

Background: Accumulating evidences have shown that long noncoding RNAs (lncRNAs) play key roles in many diseases, including cancer. Several studies reported that MCM3AP antisense RNA 1 (MCM3AP-AS1) was associated with the tumorigenesis and progression. However, the specific function and mechanism of MCM3AP-AS1 in colorectal cancer (CRC) have not been fully understood., Methods: The expression of MCM3AP-AS1 was detected by quantitative reverse transcription PCR (RT-qPCR) in CRC tissues and matched noncancerous tissues (NCTs). CCK-8 assay, colony formation assay, transwell assay, xenograft and lung metastasis mouse models were used to examine the tumor-promoting function of MCM3AP-AS1 in vitro and in vivo. The binding relationship between MCM3AP-AS1, miR-193a-5p and sentrin-specific peptidase 1 (SENP1) were screened and identified by databases, RT-qPCR, dual luciferase reporter assay and western blot., Results: In the present study, we got that the expression of MCM3AP-AS1 was higher in CRC tissues than in paired NCTs, and increased MCM3AP-AS1 expression was associated with adverse outcomes in CRC patients. Functional experiments in vitro revealed that silencing of MCM3AP-AS1 could inhibit the proliferation, colony formation, migratory, and invasive abilities of CRC cells. The mouse models of xenograft and lung metastasis further confirmed that in vivo silencing MCM3AP-AS1 could significantly inhibit the growth and metastasis of CRC. Further mechanism studies indicated that MCM3AP-AS1 could sponge miR-193a-5p and inhibit the activity of it. What is more, SENP1 was proved to be a novel target of miR-193a-5p and could be upregulated by MCM3AP-AS1. At last, we observed that SENP1 overexpression in CRC tissues was closely related to unfavorable prognosis., Conclusion: Taken together, we identified in CRC the MCM3AP-AS1/miR-193a-5p/SENP1 regulatory axis, which affords a therapeutic possibility for CRC., (© 2021 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.)

Recently, a growing body of studies has demonstrated that long non-coding RNA (lncRNA) can act as microRNA (miRNA) sponges to regulate protein-coding gene expression and play essential roles in tumor initiation and progression. In the present study, we constructed a competitive endogenous RNA (ceRNA) network and identified potential regulatory axes in colorectal cancer (CRC) through both bioinformation and experimental validation. Firstly, we obtained differentially expressed (DE) lncRNAs, miRNAs, and mRNAs by analyzing the RNA expression profiles of CRC retrieved from The Cancer Genome Atlas (TCGA) database and CRC patients' data from affiliated Hospital of Jiangnan University, respectively. Then, we established a ceRNA regulatory network of CRC that includes 23 lncRNAs, 7 miRNAs and 244 mRNAs. To further identify these lncRNA-miRNA-mRNA regulatory axes which might play vital roles in CRC tumorigenesis and prognosis, we performed additional analyses using comprehensive bioinformatic methods. Several ceRNA regulatory axes, which consist of 2 lncRNAs, 2 miRNAs and 5 mRNAs, were obtained from the network. Finally, the interactions and correlations among these ceRNA networks were validated by experiments on CRC cell lines and clinical tumor tissues, and a potential IGF2-AS/miR-150/IGF2 axis that perfectly conform to the ceRNA theory was determined. According to the qRT-PCR results, miR-150 overexpression remarkably decreased IGF2-AS and IGF2 expression. Meanwhile, IGF2-AS expression was positively correlated with IGF2 expression in tumor tissue of CRC patients. Besides, dual luciferase reporter assays indicated that miR-150 could bound to IGF2-AS and the 3'UTR of and IGF2. In general, the constructed novel IGF2-AS/miR-150/IGF2 network might provide potential mechanisms of CRC development, and could act as a promising target for CRC treatment., (Copyright © 2020 Elsevier GmbH. All rights reserved.)

Background: Chemoresistance is a common problem for cancer treatment worldwide. Circulating exosomal microRNAs (miRNAs) have been considered as promising biomarkers of cancers. However, few studies have assessed the relationship between serum/plasma exosomal microRNAs and chemoresistance in colorectal cancer (CRC)., Methods: Based on previous microarray analysis, we selected 30 miRNAs which are aberrantly expressed during CRC progression and then detected their expression levels in three pairs of oxaliplatin/5-fluorouracil-resistant CRC cell lines and the corresponding secreted exosomes. Six candidate exosomal miRNAs were identified for further evaluating potential value in predicting chemotherapeutic effect in advanced CRC patients. Finally, the molecular mechanisms of these miRNAs in drug resistance were explored by bioinformatics preliminarily., Results: We observed that the expression of 14 miRNAs was significantly higher in three drug-resistant CRC cells comparing with their parental cells. Among these miRNAs, miR-21-5p, miR-1246, miR-1229-5p, miR-135b, miR-425 and miR-96-5p are also up-regulated in exosomes from culture media of resistant cells. Clinical sample analysis confirmed that the expression levels of miR-21-5p, miR-1246, miR-1229-5p and miR-96-5p in serum exosomes were significantly higher in chemoresistant patients in contrast with chemosensitive controls. ROC curve showed that the combination of the four miRNAs had an area of under the curve (AUC) of 0.804 (P < 0.05). In addition, GO analysis and KEGG pathway analysis revealed that these miRNAs were enriched in PI3K-Akt signaling pathway, FoxO signaling pathway and autophagy pathway., Conclusions: Our study demonstrates that a panel of serum exosomal miRNAs containing miR-21-5p, miR-1246, miR-1229-5p and miR-96-5p could significantly distinguish the chemotherapy-resistant group from advanced colorectal cancer patients. Targeting these miRNAs may promote chemosensitivity to oxaliplatin and 5-fluorouracil, and might be promising strategy for CRC treatment.

The incidence and death rate of colorectal cancer (CRC) is very high, which brings great need to understand the early molecular events of CRC. These studies demonstrate that long noncoding RNA (lncRNA) plays an important role in the occurrence and development of human cancer. Small nucleolar RNA host gene 15 (SNHG15) was recently identified as a cancer-related lncRNA. In this study, we aimed to evaluate the function and mechanism of SNHG15 in CRC. The expression of SNHG15 was detected by quantitative RT-PCR (qRT-PCR) in CRC tissues and matched noncancerous tissues (NCTs). CCK-8 assay, colony formation assay, flow cytometric analysis, and nude mouse xenograft mode were used to examine the tumor-promoting function of SNHG15 in vitro and in vivo. The binding relationship between SNHG15, miR-338-3p and the target genes of miR-338-3p were screened and identified by databases, qRT-PCR, dual luciferase reporter assay and western blot. Our results showed that SNHG15 was up-regulated in CRC tissues compared with paired NCTs (P < 0.0001). High level of SNHG15 expression predicted poor prognosis of CRC (P = 0.0051). SNHG15 overexpression could promote cell proliferation and inhibit cell apoptosis. Animal experiments showed that up-regulation of SNHG15 promoted tumor growth in vivo. The results of mechanism experiments showed that SNHG15 could bind to miR-338-3p and block its inhibition on the expression and activity of FOS or RAB14. In conclusion SNHG15 promotes cell proliferation through SNHG15/miR-338-3p/FOS-RAB14 axis in CRC., (© 2019 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.)

Purpose: Long non-coding RNAs (lncRNAs) play key roles in human cancers. Here, FEZF1-AS1, a highly overexpressed lncRNA in colorectal cancer, was identified by lncRNA microarrays. We aimed to explore the roles and possible molecular mechanisms of FEZF1-AS1 in colorectal cancer. Experimental Design: LncRNA expression in colorectal cancer tissues was measured by lncRNA microarray and qRT-PCR. The functional roles of FEZF1-AS1 in colorectal cancer were demonstrated by a series of in vitro and in vivo experiments. RNA pull-down, RNA immunoprecipitation and luciferase analyses were used to demonstrate the potential mechanisms of FEZF1-AS1. Results: We identified a series of differentially expressed lncRNAs in colorectal cancer using lncRNA microarrays, and revealed that FEZF1-AS1 is one of the most overexpressed. Further validation in two expanded colorectal cancer cohorts confirmed the upregulation of FEZF1-AS1 in colorectal cancer, and revealed that increased FEZF1-AS1 expression is associated with poor survival. Functional assays revealed that FEZF1-AS1 promotes colorectal cancer cell proliferation and metastasis. Mechanistically, FEZF1-AS1 could bind and increase the stability of the pyruvate kinase 2 (PKM2) protein, resulting in increased cytoplasmic and nuclear PKM2 levels. Increased cytoplasmic PKM2 promoted pyruvate kinase activity and lactate production (aerobic glycolysis), whereas FEZF1-AS1-induced nuclear PKM2 upregulation further activated STAT3 signaling. In addition, PKM2 was upregulated in colorectal cancer tissues and correlated with FEZF1-AS1 expression and patient survival. Conclusions: Together, these data provide mechanistic insights into the regulation of FEZF1-AS1 on both STAT3 signaling and glycolysis by binding PKM2 and increasing its stability. Clin Cancer Res; 24(19); 4808-19. ©2018 AACR ., (©2018 American Association for Cancer Research.)

Long non-coding RNAs (lncRNAs) have been shown to play important roles in tumor formation and development. Small nucleolar RNA host gene 6 (SNHG6) is a recently identified cancer-related lncRNA, and its role in colorectal cancer (CRC) remains to be explored. The aim of this study was to evaluate the expression and function of SNHG6 in CRC. The expression of SNHG6 was detected by real time quantitative RT-PCR (qRT-PCR) in 74 CRC tissues and matched noncancerous tissues (NCTs). Relationships between the expression levels of SNHG6 and various clinicopathological features were analyzed by Chi-square test. The Kaplan-Meier method and log-rank test were applied to compare the survival distribution between different groups. CCK8 assay and colony formation assay were used to measure the effect of SNGH6 on cell proliferation. Flow cytometric analysis was performed to measure the effect of SNHG6 on cell cycle and apoptosis. Our results showed that SNHG6 was up-regulated more than 1.5-fold in 50.0% (37/74) of CRC tissues compared with paired NCTs (P < 0.0001). High level of SNHG6 expression was strongly associated with advanced tumor stage (P = 0.026) and predicted poor prognosis of CRC (P = 0.0215). The Cox proportional hazards model demonstrated that SNHG6 expression was an independent prognostic factor for CRC (HR, 2.568; 95% CI, 1.055-6.252; P = 0.038). Furthermore, SNHG6 knockdown by siRNA could inhibit cell proliferation, cell cycle progression, and induce apoptosis. Taken together, SNHG6 functions as an oncogene in CRC and appears as a novel prognositic factor for CRC patients., (Copyright © 2018 Elsevier GmbH. All rights reserved.)

Purpose: Tumor-associated macrophages (TAMs) are frequently associated with poor prognosis in human cancers. However, the effects of TAMs in colorectal cancer are contradictory. We therefore investigated the functions, mechanisms, and clinical significance of TAMs in colorectal cancer. Experimental Design: We measured the macrophage infiltration (CD68), P-gp, and Bcl2 expression in colorectal cancer tissues using IHC staining. Coculture of TAMs and colorectal cancer cells both in vitro and in vivo models was used to evaluate the effects of TAMs on colorectal cancer chemoresistance. Cytokine antibody arrays, ELISA, neutralizing antibody, and luciferase reporter assay were performed to uncover the underlying mechanism. Results: TAM infiltration was associated with chemoresistance in patients with colorectal cancer. Colorectal cancer-conditioned macrophages increased colorectal cancer chemoresistance and reduced drug-induced apoptosis by secreting IL6, which could be blocked by a neutralizing anti-IL6 antibody. Macrophage-derived IL6 activated the IL6R/STAT3 pathway in colorectal cancer cells, and activated STAT3 transcriptionally inhibited the tumor suppressor miR-204-5p. Rescue experiment confirmed that miR-204-5p is a functional target mediating the TAM-induced colorectal cancer chemoresistance. miR-155-5p, a key miRNA regulating C/EBPβ, was frequently downregulated in TAMs, resulting in increased C/EBPβ expression. C/EBPβ transcriptionally activated IL6 in TAMs, and TAM-secreted IL6 then induced chemoresistance by activating the IL6R/STAT3/miR-204-5p pathway in colorectal cancer cells. Conclusions: Our data indicate that the maladjusted miR-155-5p/C/EBPβ/IL6 signaling in TAMs could induce chemoresistance in colorectal cancer cells by regulating the IL6R/STAT3/miR-204-5p axis, revealing a new cross-talk between immune cells and tumor cells in colorectal cancer microenvironment. Clin Cancer Res; 23(23); 7375-87. ©2017 AACR ., (©2017 American Association for Cancer Research.)

Multidrug resistance (MDR), a phenomenon that often occurs with drug treatment and is characterized by relapse or attenuation of drug efficacy, is almost unavoidable in colorectal cancer (CRC) patients receiving 5-fluorouracil (5-FU)-based chemotherapy. MicroRNAs (miRNAs) are small noncoding RNAs that post-transcriptionally regulate gene expression. Our previous study has identified miR-139-5p as a potential tumor suppressor in CRC, but its role in chemoresistance of CRC has not been elucidated. In this study, we demonstrated that miR-139-5p was down-regulated either in CRC tumors receiving chemotherapy or in 5-FU-resistant CRC cell lines (HCT-8/5-FU and HCT-116/5-FU). Ectopic expression of miR-139-5p sensitized CRC cells to 5-FU by increasing 5-FU-induced apoptosis. In addition, miR-139-5p inhibited the expression of the miR-139-5p target gene NOTCH-1 and its downstream molecules MRP-1 and BCL-2, two key MDR-associated genes. Furthermore, silencing NOTCH-1 expression promoted the chemotherapeutic effects of 5-FU, and up-regulation of NOTCH-1 abrogated miR-139-5p-mediated sensitization to 5-FU in LoVo and HCT-116 cells. Taken together, our data indicate a new role of miR-139-5p/NOTCH-1 pathway in the drug resistance of CRC cells to 5-FU, which may be a promising therapeutic target for the anti-MDR treatment of CRC., (Copyright © 2016 Elsevier GmbH. All rights reserved.)

As a potential tumor suppressor, the detailed clinical application value of sorting nexin 1 (SNX1) has not been elucidated in colorectal cancer (CRC). The aim of the present study was to evaluate the expression of SNX1 in CRC tissues and to determine its correlation with clinicopathologic characteristics and its impact on patient's prognosis. We detected the expression of SNX1 mRNA in 72 CRC patients and SNX1 protein in 237 CRC patients by real-time polymerase chain reaction (RT-PCR) and immunohistochemical staining, respectively. Relationship between the expression of SNX1 and various clinicopathological features in these patients was evaluated. Both the mRNA and protein expression of SNX1 were remarkably decreased in CRC tissues compared with paired non-cancerous tissues, and the down-regulation of SNX1 protein was strongly associated with poor differentiation and poor overall survival (OS) rate of CRC patients. Ectopic SNX1 expression repressed CRC cell growth and promoted tumor sensitivity to most commonly used chemotherapeutic drugs (oxaliplatin and 5-Fluorouracil). In conclusion, overexpression of SNX1 may serve as a new therapeutic strategy for CRC.

Recent preliminary studies reported the in vitro tumor-promoting effects of long non-coding RNA urothelial carcinoma associated 1 (UCA1) in colorectal cancer (CRC). However, the in vivo functions and molecular mechanism of UCA1 in CRC remain unclear. Therefore, we investigated the detailed role and mechanism of UCA1 in CRC. We found that UCA1 was up-regulated in CRCs and negatively correlated with survival time in two CRC cohorts. Functional assays revealed the in vitro and in vivo growth-promoting function of UCA1 and revealed that UCA1 can decrease the sensitivity of CRC cells to 5-FU by attenuating apoptosis. Further mechanistic studies revealed that UCA1 could sponge endogenous miR-204-5p and inhibit its activity. We also identified CREB1 as a new target of miR-204-5p. The protein levels of CREB1 were significantly up-regulated in CRCs, negatively associated with survival time and positively correlated with the UCA1 expression. The present work provides the first evidence of a UCA1-miR-204-5p-CREB1/BCL2/RAB22A regulatory network in CRC and reveals that UCA1 and CREB1 are potential new oncogenes and prognostic factors for CRC.

The development of colorectal cancers (CRC) is accompanied with the acquisition and maintenance of specific genomic alterations. These alterations can emerge in premalignant adenomas and faithfully maintained in highly advanced tumors. miRNAs are a class of small non-coding RNAs that are frequently deregulated in human cancers and negatively regulate a wide variety of protein coding genes. To identify the sequential alterations of miRNAs and its regulatory networks during CRC development and progression, we detected the miRNA expression profiles of tissue samples from normal colon, colorectal adenoma and CRC using miRNA microarray. qRT-PCR assay was used to validate and select the miRNAs with differential expression among the three groups, and the computer-aided algorithms of TargetScan, miRanda, miRwalk, RNAhybrid and PicTar were used to search for the possible targets of the selected 8 miRNAs (miR-18a, miR-18b, miR-31, miR-142-5p, miR-145, miR-212, miR-451, and miR-638) with continuous alterated expression. These potential target genes were enriched in several key signal transduction pathways (KEGG pathway analysis), which have been proved to be closely related to colorectal tumorigenesis. To confirm the reliability of the analyses, we identified that the metastasis-related gene ZO-1 is a certain target of miR-212 in CRC and keeps declining during CRC progression. By following these analyses, we might gain an in-depth understanding of the molecular regulatory networks of colorectal tumorigenesis and provide new potential targets for the diagnostic and therapeutic interventions of this disease., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Originally discovered in neuronal guidance, the Slit-Robo pathway is emerging as an important player in human cancers. However, its involvement and mechanism in colorectal cancer (CRC) remains to be elucidated. Here, we report that Slit2 expression is reduced in CRC tissues compared with adjacent noncancerous tissues. Extensive promoter hypermethylation of the Slit2 gene has been observed in CRC cells, which provides a mechanistic explanation for the Slit2 downregulation in CRC. Functional studies showed that Slit2 inhibits CRC cell migration in a Robo-dependent manner. Robo-interacting ubiquitin-specific protease 33 (USP33) is required for the inhibitory function of Slit2 on CRC cell migration by deubiquitinating and stabilizing Robo1. USP33 expression is downregulated in CRC samples, and reduced USP33 mRNA levels are correlated with increased tumor grade, lymph node metastasis and poor patient survival. Taken together, our data reveal USP33 as a previously unknown tumor-suppressing gene for CRC by mediating the inhibitory function of Slit-Robo signaling on CRC cell migration. Our work suggests the potential value of USP33 as an independent prognostic marker of CRC., (© 2014 UICC.)

The expression of miR-638 was found downregulated in colorectal carcinoma (CRC) in our previous study. However, the role of miR-638 in CRC remains unknown. The aim of this study was to determine the function and mechanism of miR-638 in CRC. Here, we verified that miR-638 was frequently downregulated in CRC tissues compared with corresponding noncancerous tissues (NCTs) in an expanded CRC cohort, and survival analysis showed that the downregulation of miR-638 in CRC was associated with poor prognoses. The ectopic expression of miR-638 inhibited CRC cell proliferation, invasion and arrest the cell cycle in G1 phase, whereas the repression of miR-638 significantly promoted CRC cell growth, invasion and cell cycle G1/S transition. Subsequent mechanism analyses revealed that miR-638 inhibited CRC cell growth, invasion and cell cycle progression by targeting TSPAN1. TSPAN1 protein levels were upregulated in CRC samples and were inversely correlated with miR-638 levels. More importantly, high TSPAN1 expression levels in CRC tissues predicted poor overall survival, and appears to be an independent prognostic factor for CRC survival. Furthermore, CpG island methylation analyses revealed that the miR-638 promoter was hypermethylated in CRC and that attenuating promoter methylation was sufficient to restore miR-638 expression in CRC cells. Taken together, our current data demonstrate that miR-638 functions as a tumor suppressor in human CRC by inhibiting TSPAN1, and that TSPAN1 is a potential prognostic factor for CRC.

Purpose: miR-204-5p was found to be downregulated in colorectal cancer tissues in our preliminary microarray analyses. However, the function of miR-204-5p in colorectal cancer remains unknown. We therefore investigated the role, mechanism, and clinical significance of miR-204-5p in colorectal cancer development and progression., Experimental Design: We measured the expression of miR-204-5p and determined its correlation with patient prognoses. Ectopic expression in colorectal cancer cells, xenografts, and pulmonary metastasis models was used to evaluate the effects of miR-204-5p on proliferation, migration, and chemotherapy sensitivity. Luciferase assay and Western blotting were performed to validate the potential targets of miR-204-5p after the preliminary screening by a microarray analysis and computer-aided algorithms., Results: miR-204-5p is frequently downregulated in colorectal cancer tissues, and survival analysis showed that the downregulation of miR-204-5p in colorectal cancer was associated with poor prognoses. Ectopic miR-204-5p expression repressed colorectal cancer cell growth both in vitro and in vivo. Moreover, restoring miR-204-5p expression inhibited colorectal cancer migration and invasion and promoted tumor sensitivity to chemotherapy. Mechanistic investigations revealed that RAB22A, a member of the RAS oncogene family, is a direct functional target of miR-204-5p in colorectal cancer. Furthermore, RAB22A protein levels in colorectal cancer tissues were frequently increased and negatively associated with miR-204-5p levels and survival time., Conclusions: Our results demonstrate for the first time that miR-204-5p acts as a tumor suppressor in colorectal cancer through inhibiting RAB22A and reveal RAB22A to be a new oncogene and prognostic factor for colorectal cancer., (©2014 American Association for Cancer Research.)

MicroRNAs (miRNAs) that exert function by posttranscriptional suppression have recently brought insight in our understanding of the role of non-protein-coding RNAs in carcinogenesis and metastasis. In this study, we described the function and molecular mechanism of miR-139-5p in colorectal cancer (CRC) and its potential clinical application in CRC. We found that miR-139-5p was significantly downregulated in 73.8% CRC samples compared with adjacent noncancerous tissues (NCTs), and decreased miR-139-5p was associated with poor prognosis. Functional analyses demonstrated that ectopic expression of miR-139-5p suppressed CRC cell migration and invasion in vitro and metastasis in vivo. Mechanistic investigations revealed that miR-139-5p suppress CRC cell invasion and metastasis by targeting AMFR and NOTCH1. Knockdown of the two genes phenocopied the inhibitory effect of miR-139-5p on CRC metastasis. Furthermore, the protein levels of the two genes were upregulated in CRC samples compared with NCTs, and inversely correlated with the miR-139-5p expression. Increased NOTCH1 protein expression was correlated with poor prognosis of CRC patients. Together, our data indicate that miR-139-5p is a potential tumor suppressor and prognostic factor for CRC, and targeting miR-139-5p may repress the metastasis of CRC and improve survival.

Double minute chromosomes (DMs) are a hallmark of gene amplification. The relationship between the formation of DMs and the amplification of DM-carried genes remains to be clarified. The human colorectal cancer cell line NCI-H716 and human malignant primitive neuroectodermal tumor cell line SK-PN-DW are known to contain many DMs. To examine the amplification of DM-carried genes in tumor cells, we performed Affymetrix SNP Array 6.0 analyses and verified the regions of amplification in NCI-H716 and SK-PN-DW tumor cells. We identified the amplification regions and the DM-carried genes that were amplified and overexpressed in tumor cells. Using RNA interference, we downregulated seven DM-carried genes, (NDUFB9, MTSS1, NSMCE2, TRIB1, FAM84B, MYC and FGFR2) individually and then investigated the formation of DMs, the amplification of the DM-carried genes, DNA damage and the physiological function of these genes. We found that suppressing the expression of DM-carried genes led to a decrease in the number of DMs and reduced the amplification of the DM-carried genes through the micronuclei expulsion of DMs from the tumor cells. We further detected an increase in the number of γH2AX foci in the knockdown cells, which provides a strong link between DNA damage and the loss of DMs. In addition, the loss of DMs and the reduced amplification and expression of the DM-carried genes resulted in a decrease in cell proliferation and invasion ability., (© 2013 The Authors. Published by Wiley Periodicals, Inc. on behalf of UICC.)