Identification and diagnostic potential of hsa_circ_101303 in colorectal cancer: unraveling a regulatory network.

BACKGROUND: The role of novel circular RNAs (circRNAs) in colorectal cancer (CRC) remains to be determined. This study aimed to identify a novel circRNA involved in CRC pathogenesis, assess its diagnostic value, and construct a regulatory network. METHODS: Differential expression analysis was conducted using circRNA datasets to screen for differentially expressed circRNAs. The expression of selected circRNAs was validated in external datasets and clinical samples. Diagnostic value of plasma circRNA levels in CRC was assessed. A competing endogenous RNA (ceRNA) network was constructed for the circRNA using TCGA dataset. RESULTS: Analysis of datasets revealed that hsa_circ_101303 was significantly overexpressed in CRC tissues compared to normal tissues. The upregulation of hsa_circ_101303 in CRC tissues was further confirmed through the GSE138589 dataset and clinical samples. High expression of hsa_circ_101303 was associated with advanced N stage, M stage, and tumor stage in CRC. Plasma levels of hsa_circ_101303 were markedly elevated in CRC patients and exhibited moderate diagnostic ability for CRC (AUC = 0.738). The host gene of hsa_circ_101303 was also found to be related to the TNM stage of CRC. Nine miRNAs were identified as target miRNAs for hsa_circ_101303, and 27 genes were identified as targets of these miRNAs. Subsequently, a ceRNA network for hsa_circ_101303 was constructed to illustrate the interactions between the nine miRNAs and 27 genes. CONCLUSIONS: The study identifies hsa_circ_101303 as a highly expressed circRNA in CRC, which is associated with the progression of the disease. Plasma levels of hsa_circ_101303 show promising diagnostic potential for CRC. The ceRNA network for hsa_circ_101303 provides valuable insights into the regulatory mechanisms underlying CRC.

TCF7L1 regulates colorectal cancer cell migration by repressing GAS1 expression.

Dysregulated Wnt/ß-catenin signaling is a common feature of colorectal cancer (CRC). The T-cell factor/lymphoid enhancer factor (TCF/LEF; hereafter, TCF) family of transcription factors are critical regulators of Wnt/ß-catenin target gene expression. Of the four TCF family members, TCF7L1 predominantly functions as a transcriptional repressor. Although TCF7L1 has been ascribed an oncogenic role in CRC, only a few target genes whose expression it regulates have been characterized in this cancer. Through transcriptome analyses of TCF7L1 regulated genes, we noted enrichment for those associated with cellular migration. By silencing and overexpressing TCF7L1 in CRC cell lines, we demonstrated that TCF7L1 promoted migration, invasion, and adhesion. We localized TCF7L1 binding across the CRC genome and overlapped enriched regions with transcriptome data to identify candidate target genes. The growth arrest-specific 1 (GAS1) gene was among these and we demonstrated that GAS1 is a critical mediator of TCF7L1-dependent CRC cell migratory phenotypes. Together, these findings uncover a novel role for TCF7L1 in repressing GAS1 expression to enhance migration and invasion of CRC cells.

CILP2 is a potential biomarker for the prediction and therapeutic target of peritoneal metastases in colorectal cancer.

Peritoneal metastases (PM) in colorectal cancer (CRC) is associated with a dismal prognosis. Identifying and exploiting new biomarkers, signatures, and molecular targets for personalised interventions in the treatment of PM in CRC is imperative. We conducted transcriptomic profiling using RNA-seq data generated from the primary tissues of 19 CRC patients with PM. Using our dataset established in a previous study, we identified 1422 differentially expressed genes compared to non-metastatic CRC. The profiling demonstrated no differential expression in liver and lung metastatic CRC. We selected 12 genes based on stringent criteria and evaluated their expression patterns in a validation cohort of 32 PM patients and 84 without PM using real-time reverse transcription-polymerase chain reaction. We selected cartilage intermediate layer protein 2 (CILP2) because of high mRNA expression in PM patients in our validation cohort and its association with a poor prognosis in The Cancer Genome Atlas. Kaplan-Meier survival analysis in our validation cohort demonstrated that CRC patients with high CILP2 expression had significantly poor survival outcomes. Knockdown of CILP2 significantly reduced the proliferation, colony-forming ability, invasiveness, and migratory capacity and downregulated the expression of molecules related to epithelial-mesenchymal transition in HCT116 cells. In an in vivo peritoneal dissemination mouse knockdown of CILP2 also inhibited CRC growth. Therefore, CILP2 is a promising biomarker for the prediction and treatment of PM in CRC.

Molecular Approach to Colorectal Carcinoma: Current Evidence and Clinical Application.

Colorectal carcinoma is one of the most common cancer types in men and women, responsible for both the third highest incidence of new cancer cases and the third highest cause of cancer deaths. In the last several decades, the molecular mechanisms surrounding colorectal carcinoma's tumorigenesis have become clearer through research, providing new avenues for diagnostic testing and novel approaches to therapeutics. Laboratories are tasked with providing the most current information to help guide clinical decisions. In this review, we summarize the current knowledge surrounding colorectal carcinoma tumorigenesis and highlight clinically relevant molecular testing.

Nivolumab plus relatlimab in patients with previously treated microsatellite instability-high/mismatch repair-deficient metastatic colorectal cancer: the phase II CheckMate 142 study.

BACKGROUND: Programmed death-1 (PD-1) inhibitors, including nivolumab, have demonstrated long-term survival benefit in previously treated patients with microsatellite instability-high/mismatch repair-deficient (MSI-H/dMMR) metastatic colorectal cancer (CRC). PD-1 and lymphocyte-activation gene 3 (LAG-3) are distinct immune checkpoints that are often co-expressed on tumor-infiltrating lymphocytes and contribute to tumor-mediated T-cell dysfunction. Relatlimab is a LAG-3 inhibitor that has demonstrated efficacy in combination with nivolumab in patients with melanoma. Here, we present the results from patients with MSI-H/dMMR metastatic CRC treated with nivolumab plus relatlimab in the CheckMate 142 study. METHODS: In this open-label, phase II study, previously treated patients with MSI-H/dMMR metastatic CRC received nivolumab 240 mg plus relatlimab 160 mg intravenously every 2 weeks. The primary end point was investigator-assessed objective response rate (ORR). RESULTS: A total of 50 previously treated patients received nivolumab plus relatlimab. With median follow-up of 47.4 (range 43.9-49.2) months, investigator-assessed ORR was 50% (95% CI 36% to 65%) and disease control rate was 70% (95% CI 55% to 82%). The median time to response per investigator was 2.8 (range 1.3-33.1) months, and median duration of response was 42.7 (range 2.8-47.0+) months. The median progression-free survival per investigator was 27.5 (95% CI 5.3 to 43.7) months with a progression-free survival rate at 3 years of 38%, and median overall survival was not reached (95% CI 17.2 months to not estimable), with a 56% overall survival rate at 3 years. The most common any-grade treatment-related adverse events (TRAEs) were diarrhea (24%), asthenia (16%), and hypothyroidism (12%). Grade 3 or 4 TRAEs were reported in 14% of patients, and TRAEs of any grade leading to discontinuation were observed in 8% of patients. No treatment-related deaths were reported. CONCLUSIONS: Nivolumab plus relatlimab provided durable clinical benefit and was well tolerated in previously treated patients with MSI-H/dMMR metastatic CRC. TRIAL REGISTRATION NUMBER: NCT02060188.

Deep neural network for the prediction of KRAS, NRAS, and BRAF genotypes in left-sided colorectal cancer based on histopathologic images.

BACKGROUND: The KRAS, NRAS, and BRAF genotypes are critical for selecting targeted therapies for patients with metastatic colorectal cancer (mCRC). Here, we aimed to develop a deep learning model that utilizes pathologic whole-slide images (WSIs) to accurately predict the status of KRAS, NRAS, and BRAFV600E. METHODS: 129 patients with left-sided colon cancer and rectal cancer from the Third Affiliated Hospital of Sun Yat-sen University were assigned to the training and testing cohorts. Utilizing three convolutional neural networks (ResNet18, ResNet50, and Inception v3), we extracted 206 pathological features from H&E-stained WSIs, serving as the foundation for constructing specific pathological models. A clinical feature model was then developed, with carcinoembryonic antigen (CEA) identified through comprehensive multiple regression analysis as the key biomarker. Subsequently, these two models were combined to create a clinical-pathological integrated model, resulting in a total of three genetic prediction models. RESULT: 103 patients were evaluated in the training cohort (1782,302 image tiles), while the remaining 26 patients were enrolled in the testing cohort (489,481 image tiles). Compared with the clinical model and the pathology model, the combined model which incorporated CEA levels and pathological signatures, showed increased predictive ability, with an area under the curve (AUC) of 0.96 in the training and an AUC of 0.83 in the testing cohort, accompanied by a high positive predictive value (PPV 0.92). CONCLUSION: The combined model demonstrated a considerable ability to accurately predict the status of KRAS, NRAS, and BRAFV600E in patients with left-sided colorectal cancer, with potential application to assist doctors in developing targeted treatment strategies for mCRC patients, and effectively identifying mutations and eliminating the need for confirmatory genetic testing.

Construction and Validation of Novel Ferroptosis-related Risk Score Signature and Prognostic Prediction Nomogram for Patients with Colorectal Cancer.

Background: Colorectal cancer (CRC) has a high morbidity and mortality. Ferroptosis is a phenomenon in which metabolism and cell death are closely related. The role of ferroptosis-related genes in the progression of CRC is still not clear. Therefore, we screened and validated the ferroptosis-related genes which could determine the prevalence, risk and prognosis of patients with CRC. Methods: We firstly screened differentially expressed ferroptosis-related genes by The Cancer Genome Atlas (TCGA) database. Then, these genes were used to construct a risk-score model using the least absolute shrinkage and selection operator (LASSO) regression algorithm. The function and prognosis of the ferroptosis-related genes were confirmed using multi-omics analysis. The gene expression results were validated using publicly available databases and qPCR. We also used publicly available data and ferroptosis-related genes to construct a prognostic prediction nomogram. Results: A total of 24 differential expressed genes associated with ferroptosis were screened in this study. A three-gene risk score model was then established based on these 24 genes and GPX3, CDKN2A and SLC7A11 were selected. The significant prognostic value of this novel three-gene signature was also assessed. Furthermore, we conducted RT-qPCR analysis on cell lines and tissues, and validated the high expression of CDKN2A, GPX3 and low expression of SLC7A11 in CRC cells. The observed mRNA expression of GPX3, CDKN2A and SLC7A11 was consistent with the predicted outcomes. Besides, eight variables including selected ferroptosis related genes were included to establish the prognostic prediction nomogram for patients with CRC. The calibration plots showed favorable consistency between the prediction of the nomogram and actual observations. Also, the time-dependent AUC (>0.7) indicated satisfactory discriminative ability of the nomogram. Conclusions: The present study constructed and validated a novel ferroptosis-related three-gene risk score signature and a prognostic prediction nomogram for patients with CRC. Also, we screened and validated the ferroptosis-related genes GPX3, CDKN2A, and SLC7A11 which could serve as novel biomarkers for patients with CRC.

[Multi-omics research progress in early-onset colorectal cancer].

Globally, the incidence of early-onset colorectal cancer (EOCRC) among individuals younger than 50 is escalating. Compared to late-onset colorectal cancer, EOCRC exhibits distinct clinical, pathological, and molecular features, with a higher prevalence in the left colon and rectum. However, the occurrence and development of EOCRC is a multi-factor and multi-stage evolution process, which is the result of the mutual effect of environmental, genetic and biological factors, and involves the multi-level regulation mechanism of other organisms. With the development and improvement of high-throughput sequencing technology, the application of multi-omics analysis has become an important development direction to resolve the pathogenesis of complex diseases and individualized treatment plans. This article aims to review the research progress of EOCRC at the multi-omics level, providing a theoretical foundation for earlier diagnosis and more precise treatment of this diseases.

Enterotoxin-related genes PPFIA4 and SCN3B promote colorectal cancer development and progression.

To identify the role of enterotoxin-related genes in colorectal cancer (CRC) development and progression. Upregulated differentially expressed genes shared by three out of five Gene Expression Omnibus (GEO) data sets were included to screen the key enterotoxin-induced oncogenes (EIOGs) according to criteria oncogene definition, enrichment, and protein-protein interaction (PPI) network analysis, followed by prognosis survival, immune infiltration, and protential drugs analyses was performed via integration of RNA-sequencing data and The Cancer Genome Atlas-derived clinical profiles. We screened nine common key EIOGs from at least three GEO data sets. A Cox proportional hazards regression models verified that more alive cases, decreased overall survival, and highest 4-year survival prediction in CRC patients with high-risk score. Protein tyrosine phosphatase receptor type F polypeptide-interacting protein alpha-4 (PPFIA4), STY11, SCN3B, and SPTBN5 were shared in the same PPI network. Immune infiltration results showed that SCN3B and synaptotagmin 11 expression were obviously associated with B cell, macrophage, myeloid dendritic cell, neutrophils, and T cell CD4+ and CD8+ in both colon adenocarcinoma and rectal adenocarcinoma. CHIR-99021, MLN4924, and YK4-279 were identified as the potential drugs for treatment. Finally, upregulated EIOGs genes PPFIA4 and SCN3B were found in colon adenocarcinoma and PPFIA4 and SCN3B were proved to promote cell proliferation and migration in vitro. We demonstrated here that EIOGs promoting a malignancy phenotype was related with poor survival and prognosis in CRC, which might be served as novel therapeutic targets in CRC management.

Assessing Mismatch Repair Expression by Immunohistochemistry in Colorectal Adenocarcinoma -Insight from a Tertiary Care Centre.

BACKGROUND: Microsatellite instability (MSI) is a pattern of hyper mutation that occurs at microsatellite level in the genome and result due to error in the mismatch repair system. MSI is caused by defective mismatch repair (MMR) genes associated with either hyper methylation of MMR genes or BRAF mutations. Anti-MLH-1, anti-MSH-2, anti-MSH-6 and anti-PMS2 monoclonal antibodies are used for Immunohistochemical analysis. METHODS: The immunohistochemical expression of MSI proteins were assessed in 72 cases of colorectal carcinoma. These were classified based on the expression of MLH1, MSH2, MSH6 and PMS2 proteins. RESULTS: There were 57 percent of cases showing loss of at least one antibodies, and 43 percent cases showing intact expression of all antibodies (MLH1, MSH2, MSH6 and PMS2). CONCLUSION: In conclusion, our study provides valuable insights into the expression of mismatch repair in colorectal adenocarcinoma through immunohistochemistry analysis conducted at our tertiary care centre. These findings hold significant clinical implications, suggesting further testing for BRAF and MLH1 Promoter Hypermethylation to confirm possibility of Lynch syndrome. KEY WORDS: IHC, MMR, CRC.

Long non-coding RNA RP11-197K6.1 as ceRNA promotes colorectal cancer progression via miR-135a-5p/DLX5 axis.

BACKGROUND: Colorectal cancer (CRC) remains a major global health challenge, with high incidence and mortality rates. The role of long noncoding RNAs (lncRNAs) in cancer progression has received considerable attention. The present study aimed to investigate the function and mechanisms underlying the role of lncRNA RP11-197K6.1, microRNA-135a-5p (hsa-miR-135a-5p), and DLX5 in CRC development. METHODS: We analyzed RNA sequencing data from The Cancer Genome Atlas Colorectal Cancer dataset to identify the association between lncRNA RP11-197K6.1 and CRC progression. The expression levels of lncRNA RP11-197K6.1 and DLX5 in CRC samples and cell lines were determined by real-time quantitative PCR and western blotting assays. Fluorescence in situ hybridization was used to confirm the cellular localization of lncRNA RP11-197K6.1. Cell migration capabilities were assessed by Transwell and wound healing assays, and flow cytometry was performed to analyze apoptosis. The interaction between lncRNA RP11-197K6.1 and miR-135a-5p and its effect on DLX5 expression were investigated by the dual-luciferase reporter assay. Additionally, a xenograft mouse model was used to study the in vivo effects of lncRNA RP11-197K6.1 on tumor growth, and an immunohistochemical assay was performed to assess DLX5 expression in tumor tissues. RESULTS: lncRNA RP11-197K6.1 was significantly upregulated in CRC tissues and cell lines as compared to that in normal tissues, and its expression was inversely correlated with patient survival. It promoted the migration and metastasis of CRC cells by interacting with miR-135a-5p, alleviated suppression of DLX5 expression, and facilitated tumor growth. CONCLUSION: This study demonstrated the regulatory network and mechanism of action of the lncRNA RP11-197K6.1/miR-135a-5p/DLX5 axis in CRC development. These findings provided insights into the molecular pathology of CRC and suggested potential therapeutic targets for more effective treatment of patients with CRC.

Identification of ROS and KEAP1-related genes and verified targets of α-hederin induce cell death for CRC.

In this study, we analyzed and verified differentially expressed genes (DEGs) in ROS and KEAP1 crosstalk in oncogenic signatures using GEO data sets (GSE4107 and GSE41328). Multiple pathway enrichment analyses were finished based on DEGs. The genetic signature for colorectal adenocarcinoma (COAD) was identified by using the Cox regression analysis. Kaplan-Meier survival and receiver operating characteristic curve analysis were used to explore the prognosis value of specific genes in COAD. The potential immune signatures and drug sensitivity prediction were also analyzed. Promising small-molecule agents were identified and predicted targets of α-hederin in SuperPred were validated by molecular docking. Also, expression levels of genes and Western blot analysis were conducted. In total, 48 genes were identified as DEGs, and the hub genes such as COL1A1, CXCL12, COL1A2, FN1, CAV1, TIMP3, and IGFBP7 were identified. The ROS and KEAP1-associated gene signatures comprised of hub key genes were developed for predicting the prognosis and evaluating the immune cell responses and immune infiltration in COAD. α-hederin, a potential anti-colorectal cancer (CRC) agent, was found to enhance the sensitivity of HCT116 cells, regulate CAV1 and COL1A1, and decrease KEAP1, Nrf2, and HO-1 expression significantly. KEAP1-related genes could be an essential mediator of ROS in CRC, and KEAP1-associated genes were effective in predicting prognosis and evaluating individualized CRC treatment. Therefore, α-hederin may be an effective chemosensitizer for CRC treatments in clinical settings.

Detecting colorectal cancer using genetic and epigenetic biomarkers: screening and diagnosis.

Colorectal cancer (CRC) is one of the most frequent types of cancer, with high incidence rates and mortality globally. The extended timeframe for developing CRC allows for the potential screening and early identification of the disease. Furthermore, studies have shown that survival rates for patients with cancer are increased when diagnoses are made at earlier stages. Recent research suggests that the development of CRC, including its precancerous lesion, is influenced not only by genetic factors but also by epigenetic variables. Studies suggest epigenetics plays a significant role in cancer development, particularly CRC. While this approach is still in its early stages and faces challenges due to the variability of CRC, it shows promise as a potential method for understanding and addressing the disease. This review examined the current evidence supporting genetic and epigenetic biomarkers for screening and diagnosis. In addition, we also discussed the feasibility of translating these methodologies into clinical settings. Several markers show promising potential, including the methylation of vimentin (VIM), syndecan-2 (SDC2), and septin 9 (SEPT9). However, their application as screening and diagnostic tools, particularly for early-stage CRC, has not been fully optimized, and their effectiveness needs validation in large, multi-center patient populations. Extensive trials and further investigation are required to translate genetic and epigenetic biomarkers into practical clinical use. biomarkers, diagnostic biomarkers.

An inflammation-related subtype classification for analyzing tumor microenvironment and clinical prognosis in colorectal cancer.

Background: The inflammatory response plays an essential role in the tumor microenvironment (TME) of colorectal cancer (CRC) by modulating tumor growth, progression, and response to therapy through the recruitment of immune cells, production of cytokines, and activation of signaling pathways. However, the molecular subtypes and risk score prognostic model based on inflammatory response remain to be further explored. Methods: Inflammation-related genes were collected from the molecular signature database and molecular subtypes were identified using nonnegative matrix factorization based on the TCGA cohort. We compared the clinicopathological features, immune infiltration, somatic mutation profile, survival prognosis, and drug sensitivity between the subtypes. The risk score model was developed using LASSO and multivariate Cox regression in the TCGA cohort. The above results were independently validated in the GEO cohort. Moreover, we explored the biological functions of the hub gene, receptor interacting protein kinase 2 (RIPK2), leveraging proteomics data, in vivo, and in vitro experiments. Results: We identified two inflammation-related subtypes (inflammation-low and inflammation-high) and have excellent internal consistency and stability. Inflammation-high subtype showed higher immune cell infiltration and increased sensitivity to common chemotherapeutic drugs, while inflammation-low subtype may be more suitable for immunotherapy. Besides, the two subtypes differ significantly in pathway enrichment and biological functions. In addition, the 11-gene signature prognostic model constructed from inflammation-related genes showed strong prognostic assessment power and could serve as a novel prognostic marker to predict the survival of CRC patients. Finally, RIPK2 plays a crucial role in promoting malignant proliferation of CRC cell validated by experiment. Conclusions: This study provides new insights into the heterogeneity of CRC and provides novel opportunities for treatment development and clinical decision making.

Investigation of ENO2 as a promising novel marker for the progression of colorectal cancer with microsatellite instability-high.

BACKGROUND: Microsatellite instability-high (MSI-H) has emerged as a significant biological characteristic of colorectal cancer (CRC). Studies reported that MSI-H CRC generally had a better prognosis than microsatellite stable (MSS)/microsatellite instability-low (MSI-L) CRC, but some MSI-H CRC patients exhibited distinctive molecular characteristics and experienced a less favorable prognosis. In this study, our objective was to explore the metabolic transcript-related subtypes of MSI-H CRC and identify a biomarker for predicting survival outcomes. METHODS: Single-cell RNA sequencing (scRNA-seq) data of MSI-H CRC patients were obtained from the Gene Expression Omnibus (GEO) database. By utilizing the copy number variation (CNV) score, a malignant cell subpopulation was identified at the single-cell level. The metabolic landscape of various cell types was examined using metabolic pathway gene sets. Subsequently, functional experiments were conducted to investigate the biological significance of the hub gene in MSI-H CRC. Finally, the predictive potential of the hub gene was assessed using a nomogram. RESULTS: This study revealed a malignant tumor cell subpopulation from the single-cell RNA sequencing (scRNA-seq) data. MSI-H CRC was clustered into two subtypes based on the expression profiles of metabolism-related genes, and ENO2 was identified as a hub gene. Functional experiments with ENO2 knockdown and overexpression demonstrated its role in promoting CRC cell migration, invasion, glycolysis, and epithelial-mesenchymal transition (EMT) in vitro. High expression of ENO2 in MSI-H CRC patients was associated with worse clinical outcomes, including increased tumor invasion depth (p = 0.007) and greater likelihood of perineural invasion (p = 0.015). Furthermore, the nomogram and calibration curves based on ENO2 showed potential prognosis predictive performance. CONCLUSION: Our findings suggest that ENO2 serves as a novel prognostic biomarker and is associated with the progression of MSI-H CRC.

Identification of potential mediators of the relationship between body mass index and colorectal cancer: a Mendelian randomization analysis.

BACKGROUND: Colorectal cancer (CRC) is the third-most-common cancer worldwide and its rates are increasing. Elevated body mass index (BMI) is an established risk factor for CRC, although the molecular mechanisms behind this association remain unclear. Using the Mendelian randomization (MR) framework, we aimed to investigate the mediating effects of putative biomarkers and other CRC risk factors in the association between BMI and CRC. METHODS: We selected as mediators biomarkers of established cancer-related mechanisms and other CRC risk factors for which a plausible association with obesity exists, such as inflammatory biomarkers, glucose homeostasis traits, lipids, adipokines, insulin-like growth factor 1 (IGF1), sex hormones, 25-hydroxy-vitamin D, smoking, physical activity (PA) and alcohol consumption. We used inverse-variance weighted MR in the main univariable analyses and performed sensitivity analyses (weighted-median, MR-Egger, Contamination Mixture). We used multivariable MR for the mediation analyses. RESULTS: Genetically predicted BMI was positively associated with CRC risk [odds ratio per SD (5 kg/m2) = 1.17, 95% CI: 1.08-1.24, P-value = 1.4 × 10-5] and robustly associated with nearly all potential mediators. Genetically predicted IGF1, fasting insulin, low-density lipoprotein cholesterol, smoking, PA and alcohol were associated with CRC risk. Evidence for attenuation was found for IGF1 [explained 7% (95% CI: 2-13%) of the association], smoking (31%, 4-57%) and PA (7%, 2-11%). There was little evidence for pleiotropy, although smoking was bidirectionally associated with BMI and instruments were weak for PA. CONCLUSIONS: The effect of BMI on CRC risk is possibly partly mediated through plasma IGF1, whereas the attenuation of the BMI-CRC association by smoking and PA may reflect confounding and shared underlying mechanisms rather than mediation.

Microsatellite instability in mismatch repair proficient colorectal cancer: clinical features and underlying molecular mechanisms.

BACKGROUND: Both defects in mismatch repair (dMMR) and high microsatellite instability (MSI-H) have been recognised as crucial biomarkers that guide treatment strategies and disease management in colorectal cancer (CRC). As MMR and MSI tests are being widely conducted, an increasing number of MSI-H tumours have been identified in CRCs with mismatch repair proficiency (pMMR). The objective of this study was to assess the clinical features of patients with pMMR/MSI-H CRC and elucidate the underlying molecular mechanism in these cases. METHODS: From January 2015 to December 2018, 1684 cases of pMMR and 401 dMMR CRCs were enrolled. Of those patients, 93 pMMR/MSI-H were identified. The clinical phenotypes and prognosis were analysed. Frozen and paraffin-embedded tissue were available in 35 patients with pMMR/MSI-H, for which comprehensive genomic and transcriptomic analyses were performed. FINDINGS: In comparison to pMMR/MSS CRCs, pMMR/MSI-H CRCs exhibited significantly less tumour progression and better long-term prognosis. The pMMR/MSI-H cohorts displayed a higher presence of CD8+ T cells and NK cells when compared to the pMMR/MSS group. Mutational signature analysis revealed that nearly all samples exhibited deficiencies in MMR genes, and we also identified deleterious mutations in MSH3-K383fs. INTERPRETATION: This study revealed pMMR/MSI-H CRC as a distinct subgroup within CRC, which manifests diverse clinicopathological features and long-term prognostic outcomes. Distinct features in the tumour immune-microenvironment were observed in pMMR/MSI-H CRCs. Pathogenic deleterious mutations in MSH3-K383fs were frequently detected, suggesting another potential biomarker for identifying MSI-H. FUNDING: This work was supported by the Science and Technology Commission of Shanghai Municipality (20DZ1100101).

Cell type specific long non-coding RNA targets identified by integrative analysis of single-cell and bulk colorectal cancer transcriptomes.

Long non-coding RNAs (lncRNAs) represent an emerging class of genes which play significant and diverse roles in human cancers. Nevertheless, the functional repertoires of lncRNAs in cancer cell subtypes remains unknown since most studies are focused on protein coding genes. Here, we explored the contribution of lncRNAs in Colorectal Cancer (CRC) heterogeneity. We analyzed 49'436 single-cells from 29 CRC patients and showed that lncRNAs are significantly more cell type specific compared to protein-coding genes. We identified 996 lncRNAs strongly enriched in epithelial cells. Among these, 98 were found to be differentially expressed in tumor samples compared to normal controls, when integrating 270 bulk CRC profiles. We validated the upregulation of two of them (CASC19 and LINC00460) in CRC cell lines and showed their involvement in CRC proliferation by CRISPR-Cas9 knock down experiments. This study highlights a list of novel RNA targets for potential CRC therapeutics, substantiated through experimental validation.

Gene mutation profiling in microsatellite instability colorectal cancer and its association with the efficacy of immunotherapy: A retrospective study.

BACKGROUND: Microsatellite instability-high (MSI-H) colorectal cancer (CRC) is known for its heightened responsiveness to immunotherapy. However, establishing robust predictive markers for immunotherapy efficacy remains imperative. This retrospective study aimed to elucidate the genetic landscape of MSI-H CRC and correlate these genetic alterations with immunotherapy outcomes in a cohort of 121 patients. METHODS: We analyzed clinical and molecular data from 121 patients with MSI-H CRC. We conducted a thorough genetic analysis of MSI-H CRC patients, with a specific emphasis on the APC, TP53, RAS, and MMR genes. We further analyzed the relationship between gene mutations and immunotherapy efficacy. The primary endpoints analyzed were objective response rate (ORR) and progression-free survival (PFS). All statistical analysis was conducted using SPSS26.0 and R 4.2.0 software. RESULTS: Our findings underscored the complexity of the genetic landscape in MSI-H CRC, shedding light on the intricate interplay of these genes in CRC development. Notably, mutations in MMR genes exhibited a distinctive pattern, providing insights into the underlying mechanisms of MSI-H. Furthermore, our results revealed correlations between specific genetic alterations and immunotherapy outcomes, with a particular focus on treatment response rates and progression-free survival. CONCLUSION: This study represents a significant step toward unraveling the genetic nuances of MSI-H CRC. The distinctive pattern of MMR gene mutations not only adds depth to our understanding of MSI-H CRC but also hints at potential avenues for targeted therapies. This research sets the stage for future investigations aimed at refining therapeutic strategies and improving outcomes for patients with MSI-H CRC.

Role of MEK1 and DIAPH3 expression in colorectal adenoma-carcinoma sequence.

BACKGROUND: It is well established that most colorectal carcinomas arise from conventional adenomas through the adenoma-carcinoma sequence (ACS) model. mitogen-activated protein kinases (MAPKs) pathway has been reported as a crucial player in tumorigenesis. The MAPK signaling pathway is activated by different extracellular signals involving the "mitogen-activated/extracellular signal-regulated kinase 1 (MEK1)", and this induces the expression of genes involved in proliferation and cellular transformation. Diaphanous-related formin-3 (DIAPH3) acts as a potential metastasis regulator through inhibiting the cellular transition to amoeboid behavior in different cancer types. OBJECTIVE: The aim of the study was to investigate the pattern of immunohistochemical expression of MEK1 and DIAPH3 in colorectal adenoma (CRA) and corresponding colorectal carcinoma (CRC) specimens. METHODS: The immunohistochemical expression of DIAPH3 and MEK1 was examined in 43 cases of CRC and their associated adenomas using tissue microarray technique. RESULTS: MEK1 was overexpressed in 23 CRC cases (53.5%) and in 20 CRA cases (46.5%). DIAPH3 was overexpressed in 11 CRA cases (about 29%) which were significantly lower than CRC (22 cases; 58%) (P = 0.011). Both MEK1 and DIAPH3 overexpression were significantly correlated in CRC (P = 0.009) and CRA cases (P = 0.002). Tumors with MEK1 overexpression had a significantly higher tumor grade (P = 0.050) and perineural invasion (P = 0.017). CONCLUSIONS: Both MEK1 and DIAPH3 are overexpressed across colorectal ACS with strong correlation between them. This co- expression suggests a possible synergistic effect of MEK1 and DIAPH-3 in colorectal ACS. Further large-scale studies are required to investigate the potential functional aspects of MEK1 and DIAPH3 in ACS and their involvement in tumor initiation and the metastatic process.