LncRNA GAS6-AS1 contributes to 5-fluorouracil resistance in colorectal cancer by facilitating the binding of PCBP1 with MCM3.

5-Fluorouracil (5-FU) resistance has always been a formidable obstacle in the adjuvant treatment of advanced colorectal cancer (CRC). In recent years, long non-coding RNAs have emerged as key regulators in various pathophysiological processes including 5-FU resistance. TRG is a postoperative pathological score of the chemotherapy effectiveness for CRC, of which TRG 0-1 is classified as chemotherapy sensitivity and TRG 3 as chemotherapy resistance. Here, RNA-seq combined with weighted gene correlation network analysis confirmed the close association of GAS6-AS1 with TRG. GAS6-AS1 expression was positively correlated with advanced clinicopathological features and poor prognosis in CRC. GAS6-AS1 increased the 50% inhibiting concentration of 5-FU, enhanced cell proliferation and accelerated G1/S transition, both with and without 5-FU, both in vitro and in vivo. Mechanistically, GAS6-AS1 enhanced the stability of MCM3 mRNA by recruiting PCBP1, consequently increasing MCM3 expression. Furthermore, PCBP1 and MCM3 counteracted the effects of GAS6-AS1 on 5-FU resistance. Notably, the PDX model indicated that combining chemotherapeutic drugs with GAS6-AS1 knockdown yielded superior outcomes in vivo. Together, our findings elucidate that GAS6-AS1 directly binds to PCBP1, enhancing MCM3 expression and thereby promoting 5-FU resistance. GAS6-AS1 may serve as a robust biomarker and potential therapeutic target for combination therapy in CRC.

A one-stop approach to diagnosing hereditary colorectal cancer in the Chinese population.

BACKGROUND AND AIM: The current procedure for identifying hereditary colorectal cancer (HCRC) is time consuming in clinical practice. This study aimed to develop a time-saving approach to diagnosing HCRC. METHODS: A total of 100 suspected HCRC patients were prospectively enrolled (cohort 1) and 116 colorectal cancer patients with DNA mismatch repair-deficient were retrospectively included (cohort 2). Next-generation sequencing (NGS) tests were performed on tumors and matched white blood cells (WBCs) or normal tissues. Using the conventional method upon WBC/normal tissue-based NGS data as a reference, the performance of the ColonCore method using tumor-only-based NGS data in predicting germline variants was explored in cohort 1 and validated in cohort 2. RESULTS: In cohort 1, the ColonCore method diagnosed 17 Lynch syndrome (LS) and 14 familial adenomatous polyposis (FAP); and by the conventional method, the cases were 16 and 10, respectively. The ColonCore method showed sensitivities of 100% in diagnosing LS (positive predictive value [PPV] 94.1%) and FAP (PPV 71.4%). Moreover, two of seven patients with multiple adenomas/polyps who did not meet existing clinical criteria for HCRC were predicted to harbor germline variants in APC and MUTYH. Additionally, the sensitivity of the ColonCore method in identifying LS patients from cohort 2 reached 85.7% with a PPV of 85.7%. CONCLUSION: The ColonCore method might be an acceptable tool for predicting germline variants associated with HCRC. Our work indicates the essentiality of NGS tests in CRC patients for precision diagnosis and treatment.

Cuproptosis-related miRNAs signature and immune infiltration characteristics in colorectal cancer.

BACKGROUND: A novel form of cell death termed cuproptosis was proposed recently. miRNAs play important roles in colorectal cancer (CRC). However, their relationships have not been reported. METHODS: miRNAs that negatively regulate 16 cuproptosis regulators were predicted using Targetscan database. The univariate Cox, LASSO, and multivariate Cox regression analyses were performed to select cuproptosis-related miRNAs. GSEA and ssGSEA analysis was carried out for functional enrichment analysis. The immune cell proportion score (IPS) and the efficiencies of multiple chemotherapy drugs were compared between different risk groups. The CCK8, cell colony, edu, and flow cytometry assays were performed to validate the roles of miRNA. Luciferase reporter assay confirmed the regulatory mechanism of miRNA on cuproptosis. RESULTS: Six cuproptosis-related miRNAs (hsa-miR-653, hsa-miR-216a, hsa-miR-3684, hsa-miR-4437, hsa-miR-641, and hsa-miR-552) were screened out for model construction. The risk score could act as an independent prognostic indicator in CRC (p < 0.001, 95% HR = 1.243 (1.129-1.369)). The nomogram could efficiently predict the overall survival rate (AUC = 0.836). Then, the level of immunosuppressive pathways, immunosuppressive cells, stromal-activated genes, and stromal score was higher in the high-risk group. The IPS analysis showed a better response to immunotherapy in the low-risk group. Also, the risk score was closely correlated with efficiencies of multiple chemotherapy drugs. Furthermore, miR-653 was highly expressed in CRC tissues (p < 0.001), closely correlated with T stage (p < 0.001), metastasis (p < 0.001), and tumor stage (p < 0.001). High expression of miR-653 predicted a shorter overall survival (p = 0.0282) and disease-free survival (p = 0.0056). In addition, miR-653 promoted cell proliferation, inhibited apoptosis, and negatively regulated the expression of DLD through directly binding to the 3'-UTR of DLD mRNA. CONCLUSION: We constructed a cuproptosis-related miRNA signature for the prediction of CRC patient survival and immunotherapy sensitivity. miR-653 was highly expressed in CRC tissues, promoted cell proliferation, and inhibited apoptosis by negatively regulating the expression of DLD.

Molecular Profiling Provides Clinical Insights Into Targeted and Immunotherapies as Well as Colorectal Cancer Prognosis.

BACKGROUND & AIMS: Tumor genetic testing is indispensable in the management of primary and metastatic colorectal cancer (CRC), yet the indications for genomics-guided precision medicine and immunotherapy must be better understood and defined. METHODS: We prospectively sequenced tumors from 869 Chinese patients with CRC by a large panel and evaluated the clinical significance of single-gene somatic mutations and co-occurring events in metastatic CRC, as well as their functional effects and tumorigenic mechanisms. We systematically assessed the heterogeneity of the tumor immune microenvironment in different genomic contexts through the combined analysis of Immunoscore, multiplex immunostaining, whole-exome sequencing, transcriptome, and single-cell sequencing. RESULTS: Single-gene somatic mutations in BRAF or RBM10 were associated with shorter progression-free survival in patients with metastatic CRC. Functional studies suggested RBM10 acts as a tumor suppressor in CRC development. Co-mutations of KRAS/AMER1 or KRAS/APC were enriched in the metastatic cohort, which had poor progression-free survival and did not benefit from bevacizumab due to accelerated drug metabolism. Forty patients (4.6%) carried pathogenic or likely pathogenic germline alterations in the DNA damage repair pathway and 37.5% of these tumors had secondary-hit events with loss of heterozygosity or biallelic alterations. A high tumor insertion or deletion burden with high microsatellite instability suggested immunogenicity with numerous activated tumor-infiltrating lymphocytes, whereas polymerase epsilon exonuclease mutation with ultrahigh tumor mutation burden indicated a relatively quiescent immunophenotype. The heterogeneous genomic-immunologic interactions were reflected in the divergent neoantigen presentation and depletion, immune checkpoint expression, PD-1/PD-L1 interaction, and T-cell responsiveness to pembrolizumab. CONCLUSIONS: Our integrated analysis provides insights into CRC prognostic stratification, drug response, and personalized genomics-guided targeted and immunotherapies.

Protective effects of palbociclib on colitis-associated colorectal cancer.

Background: Chronic or recurrent inflammatory injury to the intestinal mucosa is closely related to inflammation-related colorectal cancer (CRC). This study aimed to examine the protective effects of palbociclib, a stimulator of interferon genes (STING) antagonist, on colitis-related colorectal carcinogenesis. Methods: Bioinformatic analyses, including Gene Ontology (GO) enrichment, gene set enrichment analysis (GSEA), and network analysis, were conducted. Male C57BL/6 mice were administered azoxymethane (AOM) and dextran sulfate sodium (DSS), followed by treatment with palbociclib for 6 weeks. The general conditions of mice were observed and recorded. The colon histopathology was assessed based on hematoxylin and eosin (H&E) staining results. Relative messenger RNA (mRNA) expression levels of interferon b1 (Ifnb1), interleukin 6 (Il6), and interleukin 1b (Il1b) in colon were estimated based on quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) analysis. Results: The STING signaling pathway was significantly upregulated in stages III and IV of CRC in The Cancer Genome Atlas (TCGA)-CRC cohort. After treatment with AOM/DSS, the weight of mice decreased significantly, whereas administration of palbociclib partially reversed this trend. The mouse colon treated with AOM/DSS showed significant pathological damages, disorderly epithelial cell structure, atypical hyperplasia, and infiltration of several inflammatory cell types; however, the colon damage was remarkably reduced upon treatment with palbociclib. It was also found that palbociclib almost abolished the increase in the downstream effectors of STING-mediated transcription in the colon tissue treated with AOM/DSS, as evidenced by the transcription levels of Ifnb1, Il6, and Il1b. Conclusions: These findings indicate that the STING pathway is closely associated with CRC. Palbociclib significantly alleviates tumor development in AOM/DSS-induced colitis-associated CRC.

Comprehensive analysis of cuproptosis-related lncRNAs to predict prognosis and immune infiltration characteristics in colorectal cancer.

Background: Cuproptosis is a novel form of cell death discovered in recent. A great quantity of researches has confirmed the close relationships and crucial roles between long non-coding RNAs (lncRNAs) with the progression of colorectal cancer (CRC). However, the relationship between cuproptosis and lncRNAs remains unclear in CRC. Methods: 1,111 co-expressed lncRNAs with 16 cuproptosis regulators were retrieved from CRC samples of The Cancer Genome Atlas (TCGA) database. Through univariate Cox and least absolute shrinkage and selection operator regression analysis, a prognosis model was constructed with 15 lncRNAs. The Kaplan-Meier, receiver operating characteristic curve, C-index and principal component analysis identified the prognostic power. Furthermore, a cuproptosis-related cluster was generated based on the 15 lncRNAs by unsupervised methods. The correlations between the cuproptosis-related signatures with immune cell infiltration and anti-tumor therapy were explored by multiple algorithms. Results: A risk score and nomogram with great prediction ability were constructed for CRC prognosis evaluation. The immune activate pathways, immune infiltration cells, immune functions, immune score and immune activation genes were remarkably enriched in the high risk group. The cuproptosis-related cluster was generated, of which the cluster 2 showed longer overall survival. The immune cell infiltration analysis indicated the similar results of cluster 2 with the high risk group, implying a significant marker for "hot tumor." The cluster 2 also presented high expression of immune checkpoint molecules, MSI-H status and higher susceptibility to multiple immunotherapy drugs. Conclusion: We appraised a novel cuproptosis-related prognosis model and molecular signature associated with prognosis, immune infiltration and immunotherapy. The identification of cuproptosis-related lncRNAs improved our understanding of immune infiltration and provided a significant marker for prognosis and immunotherapy in CRC.

A novel cuproptosis-related molecular pattern and its tumor microenvironment characterization in colorectal cancer.

Cuproptosis, or copper-induced cell death, has been reported as a novel noncanonical form of cell death in recent times. However, the potential roles of cuproptosis in the alteration of tumor clinicopathological features and the formation of a tumor microenvironment (TME) remain unclear. In this study, we comprehensively analyzed the cuproptosis-related molecular patterns of 1,274 colorectal cancer samples based on 16 cuproptosis regulators. The consensus clustering algorithm was conducted to identify cuproptosis-related molecular patterns and gene signatures. The ssGSEA and ESTIMATE algorithms were used to evaluate the enrichment levels of the infiltrated immune cells and tumor immune scores, respectively. The cuproptosis score was established to assess the cuproptosis patterns of individuals with principal component analysis algorithms based on the expression of cuproptosis-related genes. Three distinct cuproptosis patterns were confirmed and demonstrated to be associated with distinguishable biological processes and clinical prognosis. Interestingly, the three cuproptosis patterns were revealed to be consistent with three immune infiltration characterizations: immune-desert, immune-inflamed, and immune-excluded. Enhanced survival, activation of immune cells, and high tumor purity were presented in patients with low cuproptosisScore, implicating the immune-inflamed phenotype. In addition, low scores were linked to high tumor mutation burden, MSI-H and high CTLA4 expression, showing a higher immune cell proportion score (IPS). Taken together, our study revealed a novel cuproptosis-related molecular pattern associated with the TME phenotype. The formation of cuproptosisScore will further strengthen our understanding of the TME feature and instruct a more personalized immunotherapy schedule in colorectal cancer.

Thermal ablation versus hepatic resection for colorectal cancer with synchronous liver metastases: a propensity score matching study.

OBJECTIVES: Several studies have compared the efficacy of hepatic resection (HR) and thermal ablation (TA) for unresectable tumors; however, results remain inconsistent. Most cohorts in previous studies were heterogeneous groups of synchronous colorectal liver metastases (CRLM) and extrahepatic metastases. This retrospective study aimed to compare the therapeutic efficacy between TA and HR in synchronous CRLM without extrahepatic metastases. METHODS: Cases with initially synchronous CRLM without extrahepatic metastases between January 2007 and December 2018 were enrolled. Of the 448 cases, 346 received HR and 102 TA. Propensity score matching with a 1:1 ratio was used to improve the comparability between the HR and TA groups. Technical success, complications, disease-free survival (DFS), and overall survival (OS) were compared before and after matching. RESULTS: All patients achieved technical success. Major complication rates in the HR and TA groups were, respectively, 36.7% and 8.8% (p < 0.001). Before matching, the 5-year OS and DFS (p = 0.004 and p = 0.020, respectively) were significantly higher in the HR group than in the TA group. After matching, no significant difference in the 5-year OS and DFS was found between the groups (p = 0.770 and p = 0.939, respectively). Local tumor progression rate was significantly higher in the TA group both before (p = 0.027) and after (p = 0.029) matching. CONCLUSIONS: For patients with CRC with synchronous CRLM, TA and HR provide comparable OS and DFS. TA is preferable if complete ablation is predicted. KEY POINTS: • Thermal ablation and hepatic resection provide comparable overall survival and disease-free survival. • Thermal ablation is a safe and effective treatment for patients with colorectal cancer with synchronous liver metastases and has a lower major complication rate and higher repeatability than hepatic resection. • Thermal ablation is preferable if complete ablation is predicted.

Plasma Extracellular Vesicle Long RNAs Have Potential as Biomarkers in Early Detection of Colorectal Cancer.

Background: Early detection of colorectal cancer (CRC) is crucial to the treatment and prognosis of patients. Traditional screening methods have disadvantages. Methods: 231 blood samples were collected from 86 CRC, 56 colorectal adenoma (CRA), and 89 healthy individuals, from which extracellular vesicle long RNAs (exLRs) were isolated and sequenced. An CRC diagnostic signature (d-signature) was established, and prognosis-associated cell components were evaluated. Results: The exLR d-signature for CRC was established based on 17 of the differentially expressed exLRs. The d-signature showed high diagnostic efficiency of CRC and control (CRA and healthy) samples with an area under the curve (AUC) of 0.938 in the training cohort, 0.943 in the validation cohort, and 0.947 in an independent cohort. The d-signature could effectively differentiate early-stage (stage I-II) CRC from healthy individuals (AUC 0.990), as well as differentiating CEA-negative CRC from healthy individuals (AUC 0.988). A CRA d-signature was also generated and could differentiate CRA from healthy individuals both in the training (AUC 0.993) and validation (AUC 0.978) cohorts. The enrichment of class-switched memory B-cells, B-cells, naive B-cells, and mast cells showed increasing trends between CRC, CRA, and healthy cohorts. Class-switched memory B-cells, mast cells, and basophils were positively associated with CRC prognosis while natural killer T-cells, naive B-cells, immature dendritic cells, and lymphatic endothelial cells were negatively associated with prognosis. Conclusions: Our study identified that the exLR d-signature could differentiate CRC from CRA and healthy individuals with high efficiency and exLR profiling also has potential in CRA screening and CRC prognosis prediction.

Prognostic Value of KRAS Exon 3 and Exon 4 Mutations in Colorectal Cancer Patients.

Background: The clinical significance of KRAS exon 3/4 mutations in colorectal cancer (CRC) remains unclear. We aimed to assess the prognostic value of KRAS exons 3 and 4 mutations to determine the necessity for their testing. Methods: KRAS mutations in exon 2/3/4 were evaluated in 1816 stage I-IV patients with colorectal adenocarcinoma. Results: The mutation rates of KRAS and KRAS exons 2, 3, and 4 were 49.0%, 43.0%, 1.9%, and 4.1%, respectively. Univariate survival analysis showed that patients with exon 3 mutation had worse overall survival (OS) compared to those with KRAS exon 2 mutation or wild-type KRAS (P = 0.044, and P = 0.001). Meanwhile, there was no difference in survival between patients with wild-type KRAS and with exon 4 mutation (P = 0.128). In multivariate analysis, KRAS mutations in exon 3 and 2 were both independent factors for worse OS (Exon 3, P = 0.032, HR = 1.861, 95% CI: 1.021-3.391; Exon 2, P = 0.049, HR = 1.298, 95% CI: 1.002-1.682). Among the patients with KRAS exon 2 mutations, those that had mutations in codon 13 had significantly worse prognosis than those with wild-type KRAS (P = 0.001) or KRAS codon 12 mutations (P = 0.003). Conclusions: In KRAS-mutated CRC, exon 3 mutations predict the worst prognosis, while exon 4 mutations predict the best prognosis. Among KRAS exon 2 mutated patients, codon 13 mutations predict worse prognosis than codon 12 mutations. Mutations of different KRAS exons should be analyzed separately.

Risk scoring system for recurrence after simultaneous resection of colorectal cancer liver metastasis.

BACKGROUND: The simultaneous resection of synchronous colorectal cancer liver metastasis (SCRLM) has been widely applied. It is necessary to establish a risk scoring system to predict post-operative recurrence, especially in patients with neoadjuvant treatment. METHODS: The medical records of 221 patients undergoing simultaneous resection of CRLM were assessed in this study with a further 128 patients allocated to a validation group. All patients in the study group were classified according to their history of neoadjuvant treatment and univariate and multivariate analyses were applied to study independent risk factors. A score model was then generated according to the factors included. Our data set were also applied to validate three other existing scoring models [Fong clinical recurrence score (CRS), Konopke, and Zakaria disease-free survival (DFS) score], and the concordance index was calculated for comparison among these models. RESULTS: CRLM involving more than three nodes positive for a primary tumor was considered an independent risk factor for progression in patients without neoadjuvant treatment and all score models could discretely stratify patients according to disease free survival. In patients receiving neoadjuvant treatment, CRLM involving more than one node and transfusion invasion were major determinants in patients after treatment. However, only our scoring system and Fong's CRS score could discretely discriminate patients. In the validation group, patients were significantly classified with the score system. CONCLUSIONS: Existing score models had better values for determining prognosis in patients with SCRLM, especially in those undertaking neoadjuvant treatment. Larger cohorts, along with more detailed clinical features and multicenter validation should be undertaken before utilization.

HNRNPL Circularizes ARHGAP35 to Produce an Oncogenic Protein.

Circular RNAs (circRNAs) are an intriguing class of widely prevalent endogenous RNAs, the vast majority of which have not been characterized functionally. Here, we identified a novel oncogenic circRNA originating from the back-splicing of Exon2 and Exon3 of a tumor suppressor gene, ARHGAP35 (also known as P190-A), termed as circARHGAP35. have observe that circARHGAP35 and linear ARHGAP35 have antithetical expression and functions. Interestingly, circARHGAP35 contains a 3867 nt long ORF with an m6A-modified start codon and encodes a truncated protein comprising four FF domains and lacking the Rho GAP domain. Mechanistically, circARHGAP35 protein promotes cancer cell progression by interacting with TFII-I protein in the nucleus. The RNA binding protein, HNRNPL, facilitates the formation of circARHGAP35. Clinically, circARHGAP35 is associated with poor survival in cancer patients. Our findings characterize an oncogenic circRNA and demonstrate a novel mechanism of oncogene activation in cancer by circRNA through the production of a truncated protein.

The impact of COVID-19 pandemic on colorectal cancer patients: a single-center retrospective study.

BACKGROUND: Since December 2019, China has experienced a public health emergency from the coronavirus disease, which has become a pandemic and is impacting the care of cancer patients worldwide. This study evaluated the impact of the pandemic on colorectal cancer (CRC) patients at our center and aimed to share the lessons we learned with clinics currently experiencing this impact. METHODS: We retrospectively collected data on CRC patients admitted between January 1, 2020 and May 3, 2020; the control group comprised patients admitted between January 1, 2019 and May 3, 2019. RESULTS: During the pandemic, outpatient volumes decreased significantly, especially those of nonlocal and elderly patients, whereas the number of patients who received chemotherapy and surgery remained the same. During the pandemic, 710 CRC patients underwent curative resection. The proportion of patients who received laparoscopic surgeries was 49.4%, significantly higher than the 39.5% during the same period in 2019. The proportion of major complication during the pandemic was not significantly different from that of the control group. The mean hospital stay was significantly longer than that of the control group. CONCLUSIONS: CRC patients confirmed to be infection-free can receive routine treatment. Using online medical counseling and appropriate identification, treatment and follow-up can be effectively maintained. Adjuvant and palliative chemotherapy should not be discontinued. Endoscopic polypectomy, elective, palliative, and multidisciplinary surgeries can be postponed, while curative surgery should proceed as usual. For elderly CRC patients, endoscopic surgery and neoadjuvant radiotherapy are recommended.

Comparison of long-term outcomes between Lynch sydrome and sporadic colorectal cancer: a propensity score matching analysis.

BACKGROUND: Lynch syndrome (LS) is the most common hereditary colorectal cancer (CRC) syndrome. Comparison of prognosis between LS and sporadic CRC (SCRC) were rare, with conflicting results. This study aimed to compare the long-term outcomes between patients with LS and SCRC. METHODS: Between June 2008 and September 2018, a total of 47 patients were diagnosed with LS by genetic testing at Fudan University Shanghai Cancer Center. A 1:2 propensity score matching was performed to obtain homogeneous cohorts from SCRC group. Thereafter, 94 SCRC patients were enrolled as control group. All of enrolled patients received curative surgeries and standardized postoperative monitoring. The long-term survival rates between the two groups were compared, and the prognostic factors were also analyzed. RESULTS: The 5-year overall survival rate of LS group was 97.6%, which was significantly higher than of 82.6% for SCRC group (χ2 = 4.745, p = 0.029). The 5-year recurrence free survival rate showed no significant differences between the two groups (78.0% for LS group vs. 70.6% for SCRC patients; χ2 = 1.260, p = 0.262). The 5-year tumor free survival rates in LS group was 62.1% for LS patients, which were significantly lower than of 70.6% for SCRC group (χ2 = 4.258, p = 0.039). Subgroup analysis of recurrent patients show that the LS group had longer overall survival than the SCRC group after combined chemotherapy. By multivariate analysis, we found that tumor recurrence of primary CRC [Risk ratio (95% (confidence interval): 48.917(9.866-242.539); p < 0.001] and late TNM staging [Risk ratio (95% (confidence interval): 2.968(1.478-5.964); p = 0.002] were independent risk factors for OS. CONCLUSION: LS patients have better long-term survival prognosis than SCRC patients, even though the two groups have statistically comparable recurrence free survival. Combined chemotherapy is an effective treatment for LS patients who developed primary CRC recurrence. Standardized postoperative monitoring for LS patients may enable detection of metachronous tumors at earlier stages, which was a guarantee of a favorable prognosis despite lower tumor free survival.

HIF1α promotes tumor chemoresistance via recruiting GDF15-producing TAMs in colorectal cancer.

Chemoresistance is a tremendous challenge to efficacy of systemic chemotherapy which is the preferred treatment for the advanced CRC patients. More tumor-associated macrophages (TAMs) are recruited into the CRC tumor under chemotherapy, which are highly implicated in the chemoresistance development, but the underlying molecular mechanism is unclear. Here, we present that activated HIF1α signaling in CRC cells under chemotherapy drives the expression of HMGB1to promotes macrophage infiltration and in turn chemoresistance development. Chemotherapeutic treatment with 5-FU leads to increased recruitment of macrophages into tumors, which display tumor-protective alternative activation. Mechanistically, tumor HIF1α signaling activated by chemo-induced ROS drives the transcription of HMGB1 to promote more macrophage infiltration into CRC tumor. Furthermore, high levels of GDF15 produced by TAMs impair the chemosensitity of tumor cells via enhancing fatty acids ß-oxidation. Together, our current study reveals a new insight into the cross-talking between tumor cells and immune cells, and provides novel drug targets for clinic treatments for CRC.

LncRNA SNHG11 facilitates tumor metastasis by interacting with and stabilizing HIF-1α.

Epigenetic alteration is one of the hallmarks of colorectal cancer (CRC). Many driver genes are regulated by DNA methylation in CRC. However, the role of DNA methylation regulating lncRNAs remain elusive. Here, we identify that SNHG11 (small nucleolar RNA host gene 11) is upregulated by promotor hypomethylation in CRC and is associated with poor prognosis in CRC patients. SNHG11 can promote CRC cell migration and metastasis under hypoxia. Interestingly, the DNA-binding motif of SNHG11 is similar to that of HIF-1α. In addition, SNHG11-associated genes are enriched with members of the HIF-1 signaling pathway in CRC. Mechanistically, SNHG11 binds to the pVHLrecognition sites on HIF-1α, thus blocking the interaction of pVHL with HIF-1α and preventing its ubiquitination and degradation. Moreover, SNHG11 upregulates the expression of HIF-1α target genes, i.e., AK4, ENO1, HK2, and Twist1. Notably, SNHG11 can bind to the HRE sites in the promoter of these genes and increase their transcription. In summary, these results identify a SNHG11/ HIF-1α axis that plays a pivotal role in tumor invasion and metastasis.

Comparison Between Familial Colorectal Cancer Type X and Lynch Syndrome: Molecular, Clinical, and Pathological Characteristics and Pedigrees.

OBJECTIVE: This study aimed to compare the molecular, clinical, and pathological characteristics and pedigrees of familial colorectal cancer type X (FCCTX) with those of Lynch syndrome (LS) to provide a theoretical basis for the management of FCCTX. METHODS: Overall, 46 cases of FCCTX and 47 LS probands and affected families were enrolled between June 2008 and September 2018 for this study. Multigene cancer panel tests that included 139 genes were performed for all patients, and variants in each group were described. The clinical, pathological, and pedigree characteristics were also compared between the two groups. RESULTS: In total, 42 variants were detected in 27 (58.7%) cases in the FCCTX group, with BRCA1, BRCA2, POLE, POLD1, ATR, and ATM being the most frequently mutated genes. The mean onset age of colorectal cancer (CRC) was significantly older in the FCCTX group than in the LS group (53.57 ± 12.88 years vs. 44.36 ± 11.26 years, t = -9.204, p < 0.001). The proportion of patients with rectal cancer was also higher in the FCCTX group than in the LS group [43.5% (20/46) vs. 10.6% (5/47), χ2 = 12.823, p = 0.005]. Within a median follow-up time of 53.9 ± 37.0 months, the proportion of patients who developed metachronous CRC was significantly higher in the LS group than in the FCCTX group [34.0% (16/47) vs. 13.0% (6/46), χ2 = 5.676, p = 0.017]. When comparing pedigrees, older age at cancer onset and rectal cancer clustering were observed in the FCCTX families. A higher prevalence in male patients was also observed in the FCCTX families. CONCLUSION: FCCTX is an entity distinct from LS, but its genetic etiology remains unknown. A larger multigene panel would be recommended for determining the underlying pathogenic variants. Considering the pathology and moderate penetrance of the CRC link to FCCTX, less stringent surgical treatments and colonoscopy surveillance would be preferable. Rectum preference is a typical feature of FCCTX. Colonoscopy surveillance in FCCTX families could be less intensive, and more attention should be given to male members.

Comparison of Molecular, Clinicopathological, and Pedigree Differences Between Lynch-Like and Lynch Syndromes.

In this study, we compared the molecular, clinical, and pathological characteristics, as well as pedigrees, between patients with Lynch-like syndrome (LLS) and confirmed Lynch syndrome (LS) to develop appropriate management strategies for patients with LLS and their affected family members. Between June 2008 and September 2018, 81 patients with LLS and 47 patients with LS who developed colorectal cancer (CRC) were enrolled in this study. Multigene panel testing included 139 genes and was performed for all patients. The variants identified in each group were described, and clinicopathological characteristics and pedigrees were compared between the two groups. In the LLS group, a total of 52 variants were detected in 44 (54.3%) patients. Among the 52 variants, 17 were variants of unknown significance in mismatch repair genes, and the other most frequently mutated genes were MUYTH, POLE, BRCA2, and GJB2. The proportion of early-onset patients was significantly higher among the LS probands than among the LLS probands (74.5 and 53.1%, respectively; χ2 = 5.712, P = 0.017). On the other hand, the proportion of primary CRC developed in the rectum was higher in the LLS group than in the LS group (25.9 and 10.6%, respectively; χ2 = 2.358, P = 0.046). There were no significant differences in the occurrence of metachronous CRC (P = 0.632) and extra-colorectal cancer (extra-CRC) (P = 0.145) between the two groups. However, analysis of pedigrees showed that more patients developed CRC in the LS families (P = 0.013), whereas more patients with extra-CRC were observed in the LLS families (P = 0.045). A higher prevalence of male patients was observed in the LLS families (P = 0.036). In conclusion, LLS should be classified as a mixed entity, containing cases of LS, other hereditary cancer syndromes, and sporadic CRC. The high risks of CRC and extra-CRCs, which were found in this study, suggest tailored management policy and surveillance should be formulated based on individual and family risk. The surveillance regimen can be based on the presence of confirmed pathogenic/likely pathogenic germline variant(s) and family history.

Hypoxia Induces Growth Differentiation Factor 15 to Promote the Metastasis of Colorectal Cancer via PERK-eIF2α Signaling.

Hypoxia plays an essential role in orchestrating Epithelial-mesenchymal transition and promoting metastasis of colorectal cancer. However, the underlying mechanisms are still not well elucidated. Here, we present that hypoxic exposure causes endoplasmic reticulum stress and activates the unfolded protein response pathways, which drives GDF15 expression in colorectal cancer cells. Mechanistically, upregulated CHOP led by activated PERK-eIF2α signaling promotes GDF15 transcription via directly binding to its promoter. Further study implicates that hypoxia-induced GDF15 is required for the EMT and invasion of colorectal cancer cells; enforced expression of GDF15 promotes the mitochondrial oxidation of fatty acids in colorectal cancer cells. Moreover, the abrogation of GDF15 results in smaller xenograft tumors in size and impaired metastasis. GDF15 is expressed much more in tumor tissues of CRC patients and displays positive correlations with CHOP and HIF1α in mRNA levels. Our study demonstrates a novel molecular mechanism underlying hypoxia-promoted metastasis of CRC and provides PERK signaling-regulated GDF15 as a new and promising therapeutic target for clinical treatment and drug discovery.

Hypoxia induced LUCAT1/PTBP1 axis modulates cancer cell viability and chemotherapy response.

BACKGROUND: Hypoxic tumors are refractory to DNA damage drugs. However, the underlying mechanism has yet to be elucidated. We aimed to identify lncRNAs that upregulated under hypoxia and their effects on colorectal cancer (CRC). METHODS: CRC cells were treated with 1% O2 to identify lncRNAs that upregulated under hypoxia. We integrated these lncRNAs with RNA-seq of 4 paired CRC tissues and TCGA data to get candidate lncRNAs. Multiple in vitro and in vivo assays were used to explore the role of LUCAT1 in CRC. RESULTS: We identified a hypoxia-induced lncRNA LUCAT1 that facilitated the growth of CRC cells and contributed to drug resistance of CRC cells both in vitro and in vivo. Mechanically, LUCAT1 interacts with polypyrimidine tract binding protein 1 (PTBP1) in CRC cells, facilitates the association of a set of DNA damage related genes with PTBP1, thus resulting in altered alternative splicing of these genes. Moreover, ectopic expression of PTBP1 in CRC cells with knockdown of LUCAT1 abrogated the effects induced by LUCAT1 knockdown. Chemotherapeutics drug combined with LUCAT1 knockdown via antisense oligonucleotides (ASO) would get a better outcome in vivo, compared with group treated with chemotherapeutic drug only. Notably, LUCAT1 is upregulated in CRC tissues, compared to adjacent normal tissues; and CRC patients with higher LUCAT1 have a worse prognosis and poorly responded to chemotherapy in the clinic. CONCLUSIONS: Our data suggested CRC cells utilizes LUCAT1 to develop resistance to DNA damage drugs, and disrupting the LUCAT1/PTBP1 axis might be a promising therapeutic strategy for refractory hypoxic tumors.