Structural characterization of the DNA binding mechanism of retinoic acid-related orphan receptor gamma.

Retinoic acid-related orphan receptor gamma (RORγ) plays critical roles in regulating various biological processes and has been linked to immunodeficiency disorders and cancers. DNA recognition is essential for RORγ to exert its functions. However, the underlying mechanism of the DNA binding by RORγ remains unclear. In this study, we present the crystal structure of the complex of RORγ1 DNA-binding domain (RORγ1-DBD)/direct repeat DNA element DR2 at 2.3 Å resolution. We demonstrate that RORγ1-DBD binds the DR2 motif as a homodimer, with the C-terminal extension (CTE) region of RORγ1-DBD contributing to the DNA recognition and the formation of dimeric interface. Further studies reveal that REV-ERB-DBD and RXR-DBD, also bind the DR2 site as a homodimer, while NR4A2-DBD binds DR2 as a monomer. Our research uncovers a binding mechanism of RORγ1 to the DR2 site and provides insights into the biological functions of RORγ1 and the broader RORs subfamily.

Epigenetic modifications in obesity-associated diseases.

The global prevalence of obesity has reached epidemic levels, significantly elevating the susceptibility to various cardiometabolic conditions and certain types of cancer. In addition to causing metabolic abnormalities such as insulin resistance (IR), elevated blood glucose and lipids, and ectopic fat deposition, obesity can also damage pancreatic islet cells, endothelial cells, and cardiomyocytes through chronic inflammation, and even promote the development of a microenvironment conducive to cancer initiation. Improper dietary habits and lack of physical exercise are important behavioral factors that increase the risk of obesity, which can affect gene expression through epigenetic modifications. Epigenetic alterations can occur in early stage of obesity, some of which are reversible, while others persist over time and lead to obesity-related complications. Therefore, the dynamic adjustability of epigenetic modifications can be leveraged to reverse the development of obesity-associated diseases through behavioral interventions, drugs, and bariatric surgery. This review provides a comprehensive summary of the impact of epigenetic regulation on the initiation and development of obesity-associated cancers, type 2 diabetes, and cardiovascular diseases, establishing a theoretical basis for prevention, diagnosis, and treatment of these conditions.

An Investigation of the Immune Microenvironment and Genome during Lung Adenocarcinoma Development.

Background: Adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) are two consecutive pathological processes that occur before invasive lung adenocarcinoma (LUAD). However, our understanding of the immune editing patterns during the progression of LUAD remains limited. Furthermore, we know very little about whether alterations in driver genes are involved in forming the tumor microenvironment (TME). Therefore, it is necessary to elucidate the regulatory role of TME in LUAD development from multiple dimensions, including immune cell infiltration, molecular mutation events, and oncogenic signaling pathways. Methods: We collected 145 surgically resected pulmonary nodule specimens, including 28 cases of AIS, 52 cases of MIA, and 65 cases of LUAD. Immunohistochemistry (IHC) was used to detect the expression of immune markers CD3, CD4, CD8, CD68 and programmed death ligand 1 (PD-L1). Genomic data and TMB generated by targeted next-generation sequencing (NGS). Results: LUAD exhibited higher levels of immune cell infiltration, tumor mutation burden (TMB), and activation of oncogenic pathways compared to AIS and MIA. In LUAD, compared to epidermal growth factor receptor (EGFR) single mutation and wild-type (WT) samples, cases with EGFR co-mutations showed a more pronounced rise in the CD4/CD8 ratio and CD68 infiltration. Patients with low-density lipoprotein (LDL) receptor-related protein 1B (LRP1B) mutation have higher TMB and PD-L1 expression. The transition from AIS to LUAD tends to shift the TME towards the PD-L1+CD8+ subtype (adaptive resistance). Progression-associated mutations (PAMs) were enriched in the lymphocyte differentiation pathway and related to exhausted cells' phenotype. Conclusion: Tumor-infiltrating immune cells tend to accumulate as the depth of LUAD invasion increases, but subsequently develop into an immune exhaustion and immune escape state. Mutations in EGFR and LRP1B could potentially establish an immune niche that fosters tumor growth. PAMs in LUAD may accelerate disease progression by promoting T cell differentiation into an exhausted state.

BRCC36 Deubiquitinates HMGCR to Regulate the Interplay Between Ferroptosis and Pyroptosis.

Various forms of programmed cell death (PCD) exhibit distinct characteristics depending on their specific molecular mechanisms, and there are interactions among these different forms. Ferroptosis, which is related to autophagy and apoptosis, has an unknown potential interaction with pyroptosis. This study revealed a mutually antagonistic relationship between ferroptosis and pyroptosis, with 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) playing a key role in their interaction. It is found that HMGCR predominantly localized to mitochondria during ferroptosis but shifted to the endoplasmic reticulum following treatment with a pyroptosis inducer. Furthermore, this study demonstrated that BRCC36 (BRCA1/BRCA2-containing complex subunit 36) deubiquitinated HMGCR in a manner dependent on deubiquitinating enzyme (DUB) activity, and inhibited ferroptosis and promoted pyroptosis. Moreover, as an oncogene in hepatocellular carcinoma (HCC), BRCC36 promoted cancer cell proliferation, migration, invasion, and tumor growth. Thiolutin, an inhibitor of BRCC36, effectively suppressed the interaction between BRCC36 and HMGCR, leading to the inhibition of HCC growth. Therefore, targeting BRCC36 can offer a novel and promising therapeutic strategy for HCC treatment. In conclusion, these findings provide new theoretical evidence for further characterizing tumor heterogeneity and offer new molecular targets for the diagnosis and treatment of HCC.

Disulfidptosis-related signature predicts prognosis and characterizes the immune microenvironment in hepatocellular carcinoma.

BACKGROUND: Disulfidptosis is a type of programmed cell death caused by excessive cysteine-induced disulfide bond denaturation leading to actin collapse. Liver cancer has a poor prognosis and requires more effective intervention strategies. Currently, the prognostic and therapeutic value of disulfidptosis in liver cancer is not clear. METHODS: We investigated the features of 16 disulfidptosis-related genes (DRGs) of HCC patients in the TCGA and classified the patients into two disulfidptosis pattern clusters by consensus clustering analysis. Then, we constructed a prognostic model using LASSO Cox regression. Next, the microenvironment and drug sensitivity were evaluated. Finally, we used qPCR and functional analysis to verify the reliability of hub DRGs. RESULTS: Most of the DRGs showed significantly higher expression in cancer tissues than in adjacent tissues. Our prognostic model, the DRG score, can well predict the survival of HCC patients. There were significant differences in survival, features of the microenvironment, effects of immunotherapy, and drug sensitivity between the high- and low-DRG score groups. Ultimately, we demonstrated that a few hub DRGs have differential mRNA expression between liver cancer cells and normal cells and that the protective gene LCAT can inhibit liver cancer metastasis in vitro. CONCLUSION: We established a novel risk model based on DRG scores to predict HCC patient prognosis, drug sensitivity and immunotherapy efficacy, which provides new insight into the relationship between disulfidptosis and HCC and provides valuable assistance for the personalized treatment of HCC.

CT energy spectral parameters of creeping fat in Crohn's disease and correlation with inflammatory activity.

OBJECTIVES: Creeping fat is a kind of unique abnormal mesenteric tissue at the sites of diseased bowel of Crohn's disease. By using dual-energy CT enterography, this study aimed to evaluate the feasibility of spectral parameters in the quantitative analysis of mesenteric adipose tissue or creeping fat. METHODS: In this study, patients with known or suspected Crohn's disease who underwent dual-energy CT enterography from March 1, 2019, to March 31, 2021, were enrolled. Among them, 40 patients with surgery and pathology-proven creeping fat were selected as the creeping fat Crohn's disease group, and 40 normal patients were selected as the control group. The quantitative spectral parameters including the slope of the Hounsfield unit curve, normalised fat-water concentration, normalised fat-iodine concentration, and normalised fat volume fraction at the enteric phases were obtained. Mann-Whitney U test, Kruskal-Wallis H test, and receiver operating characteristic curve analysis were applied to compare quantitative parameters among various groups. RESULTS: A significant difference was observed in the slope of the Hounsfield unit curve, normalised fat-water concentration, normalised fat-iodine concentration, and normalised fat volume fraction between mesenteric adipose tissue and creeping fat with Crohn's disease at the enteric phase (all p < 0.001). The slope of the Hounsfield unit curve of creeping fat at the enteric phase had a better capability to distinguish inactive and active Crohn's disease (AUC = 0.93, p < 0.001). CONCLUSION: Dual-energy CT enterography with quantitative spectral parameters is a potentially novel noninvasive tool for evaluating creeping fat in Crohn's disease. CRITICAL RELEVANCE STATEMENT: Energy spectral parameters of creeping fat in Crohn's disease are significantly different from normal mesenteric adipose tissues and are correlated with inflammatory activity. KEY POINTS: • Dual-energy CT enterography allows quantitatively assessing creeping fat with spectral parameters. • The creeping fat has distinct spectral parameters to normal mesenteric adipose. • The spectral parameters accurately differentiate active and inactive Crohn's disease.

ATR-dependent ubiquitin-specific protease 20 phosphorylation confers oxaliplatin and ferroptosis resistance.

Oxaliplatin (OXA) resistance is a major clinic challenge in hepatocellular carcinoma (HCC). Ferroptosis is a kind of iron-dependent cell death. Triggering ferroptosis is considered to restore sensitivity to chemotherapy. In the present study, we found that USP20 was overexpressed in OXA-resistant HCC cells. High expression of USP20 in HCC was associated with poor prognosis. USP20 contributes OXA resistance and suppress ferroptosis in HCC. Pharmacological inhibition or knockdown of USP20 triggered ferroptosis and increased the sensitivity of HCC cells to OXA both in vitro and in vivo. Coimmunoprecipitation results revealed that the UCH domain of USP20 interacted with the N terminal of SLC7A11. USP20 stabilized SLC7A11 via removing K48-linked polyubiquitination of SLC7A11 protein at K30 and K37. Most importantly, DNA damage-induced ATR activation was required for Ser132 and Ser368 phosphorylation of USP20. USP20 phosphorylation at Ser132 and Ser368 enhanced its stability and thus conferred OXA and ferroptosis resistance of HCC cells. Our study reveals a previously undiscovered association between OXA and ferroptosis and provides new insight into mechanisms regarding how DNA damage therapies always lead to therapeutic resistance. Therefore, targeting USP20 may mitigate the development of drug resistance and promote ferroptosis of HCC in patients receiving chemotherapy.

Targeting USP8 Inhibits O-GlcNAcylation of SLC7A11 to Promote Ferroptosis of Hepatocellular Carcinoma via Stabilization of OGT.

Hepatocellular carcinoma (HCC) is a lethal and aggressive human malignancy. The present study examins the anti-tumor effects of deubiquitylating enzymes (DUB) inhibitors in HCC. It is found that the inhibitor of ubiquitin specific peptidase 8 (USP8) and DUB-IN-3 shows the most effective anti-cancer responses. Targeting USP8 inhibits the proliferation of HCC and induces cell ferroptosis. In vivo xenograft and metastasis experiments indicate that inhibition of USP8 suppresses tumor growth and lung metastasis. DUB-IN-3 treatment or USP8 depletion decrease intracellular cystine levels and glutathione biosynthesis while increasing the accumulation of reactive oxygen species (ROS). Mechanistical studies reveal that USP8 stabilizes O-GlcNAc transferase (OGT) via inhibiting K48-specific poly-ubiquitination process on OGT protein at K117 site, and STE20-like kinase (SLK)-mediated S716 phosphorylation of USP8 is required for the interaction with OGT. Most importantly, OGT O-GlcNAcylates solute carrier family 7, member 11 (SLC7A11) at Ser26 in HCC cells, which is essential for SLC7A11 to import the cystine from the extracellular environment. Collectively, this study demonstrates that pharmacological inhibition or knockout of USP8 can inhibit the progression of HCC and induce ferroptosis via decreasing the stability of OGT, which imposes a great challenge that targeting of USP8 is a potential approach for HCC treatment.

LINC02774 inhibits glycolysis in glioma to destabilize HIF-1α dependent on transcription factor RP58.

Glioma, the most common of malignant tumors in the brain, is responsible for the majority of deaths from primary brain tumors. The regulation of long noncoding RNAs (lncRNAs) in HIF-1α-driven tumor development remains unclear. LINC02774 is a nuclear lncRNA and that it is being reported for the first time in this study. We found the downregulation of LINC02774 in glioma and decreased with the degree of malignant, with its expression showing a negative correlation with the relative index of enhanced magnetic resonance (RIEMR). RIEMR-associated LINC02774 was found to inhibit glycolysis by modulating the hypoxia pathway rather than the hypoxia response itself. LINC02774 interacted with its neighboring gene, RP58 (ZBTB18), to enhance the expression of PHD3, which catalyzed HIF-1α hydroxylase and ubiquitination, leading to the downregulation of HIF-1α expression. We also found that the function of LINC02774, dependent on PHD3, was diminished upon RP58 depletion. Notably, higher expression of RIEMR-associated LINC02774 was associated with a favorable prognosis. In conclusion, these findings reveal the role of RIEMR-associated LINC02774, which relies on its neighbor gene, RP58, to regulate the hypoxia pathway as a novel tumor suppressor, suggesting its potential to be a prognostic marker and a molecular target for the therapy of glioma.

The DUBA-SLC7A11-c-Myc axis is critical for stemness and ferroptosis.

Ferroptosis is characterized by the accumulation of lipid peroxidation as a unique iron-dependent cell death. However, the interplay between stemness and ferroptosis remains unknown. Here, we demonstrate that undifferentiated cells are more sensitive to ferroptosis than differentiated cells, and cystine transporter SLC7A11 protein is highly up-regulated by deubiquitinase DUBA in differentiated cells. Additionally, DUBA promotes stemness by deubiquitinating SLC7A11. Moreover, SLC7A11 drastically increases the expression of c-Myc through cysteine, the combination of sorafenib and c-Myc inhibitor EN4 has a synergetic effect on cancer therapy. Together, our results reveal that enhanced stemness increases the susceptibility to ferroptosis, and the DUBA-SLC7A11-c-Myc axis is pivotal for differentiated cancer stem cells (CSCs) resistant to ferroptosis, providing a promised targets to eradicate CSCs through ferroptosis.

The NLRP11 Protein Bridges the Histone Lysine Acetyltransferase KAT7 to Acetylate Vimentin in the Early Stage of Lung Adenocarcinoma.

Accumulation of vimentin is the core event in epithelial-mesenchymal transition (EMT). Post-translational modifications have been widely reported to play crucial roles in imparting different properties and functions to vimentin. Here, a novel modification of vimentin, acetylated at Lys104 (vimentin-K104Ac) is identified, which is stable in lung adenocarcinoma (LUAD) cells. Mechanistically, NACHT, LRR, and PYD domain-containing protein 11 (NLRP11), a regulator of the inflammatory response, bind to vimentin and promote vimentin-K104Ac expression, which is highly expressed in the early stages of LUAD and frequently appears in vimentin-positive LUAD tissues. In addition, it is observed that an acetyltransferase, lysine acetyltransferase 7 (KAT7), which binds to NLRP11 and vimentin, directly mediates the acetylation of vimentin at Lys104 and that the cytoplasmic localization of KAT7 can be induced by NLRP11. Malignant promotion mediated by transfection with vimentin-K104Q is noticeably greater than that mediated by transfection with vimentin-WT. Further, suppressing the effects of NLRP11 and KAT7 on vimentin noticeably inhibited the malignant behavior of vimentin-positive LUAD in vivo and in vitro. In summary, these findings have established a relationship between inflammation and EMT, which is reflected via KAT7-mediated acetylation of vimentin at Lys104 dependent on NLRP11.

The ubiquitin-specific protease 5 mediated deubiquitination of LSH links metabolic regulation of ferroptosis to hepatocellular carcinoma progression.

Epigenetic regulators and posttranslational modifications of proteins play important roles in various kinds of cancer cell death, including ferroptosis, a non-apoptotic form of cell death. However, the interplay of chromatin modifiers and deubiquitinase (DUB) in ferroptosis remains unclear. Here, we found that ubiquitin-specific protease 5 (USP5) is regarded as a bona fide DUB of lymphoid-specific helicase (LSH), a DNA methylation repressor, in hepatocellular carcinoma (HCC). Functional studies reveal that USP5 interacts with LSH and stabilizes LSH by a deubiquitylation activity-dependent process. Furthermore, the USP5-mediated deubiquitination of LSH facilitates the tumorigenesis of HCC by upregulating solute carrier family 7 member 11 (SLC7A11) to suppress ferroptosis of liver cancer cells. Moreover, the USP5 inhibitor degrasyn inhibits DUB activities of USP5 to LSH to suppress the progression of HCC. Additionally, USP5 and LSH are positively correlated and both are overexpressed and linked to poor prognosis in HCC patients. Together, our findings show that USP5 interacts with LSH directly and enhances LSH protein stability through deubiquitination, which, in turn, promotes the development of HCC by suppressing ferroptosis of liver cancer cells, suggesting that USP5 may be a potential therapeutic target for HCC.

Effects of radiation therapy on tumor microenvironment: an updated review.

ABSTRACT: Cancer is a major threat to human health and causes death worldwide. Research on the role of radiotherapy (RT) in the treatment of cancer is progressing; however, RT not only causes fatal DNA damage to tumor cells, but also affects the interactions between tumor cells and different components of the tumor microenvironment (TME), including immune cells, fibroblasts, macrophages, extracellular matrix, and some soluble products. Some cancer cells can survive radiation and have shown strong resistance to radiation through interaction with the TME. Currently, the complex relationships between the tumor cells and cellular components that play major roles in various TMEs are poorly understood. This review explores the relationship between RT and cell-cell communication in the TME from the perspective of immunity and hypoxia and aims to identify new RT biomarkers and treatment methods in lung cancer to improve the current status of unstable RT effect and provide a theoretical basis for further lung cancer RT sensitization research in the future.

Structural basis of the farnesoid X receptor/retinoid X receptor heterodimer on inverted repeat DNA.

Farnesoid X receptor (FXR) is a ligand-activated transcription factor known as bile acid receptor (BAR). FXR plays critical roles in various biological processes, including metabolism, immune inflammation, liver regeneration and liver carcinogenesis. FXR forms a heterodimer with the retinoid X receptor (RXR) and binds to diverse FXR response elements (FXREs) to exert its various biological functions. However, the mechanism by which the FXR/RXR heterodimer binds the DNA elements remains unclear. In this study, we aimed to use structural, biochemical and bioinformatics analyses to study the mechanism of FXR binding to the typical FXRE, such as the IR1 site, and the heterodimer interactions in the FXR-DBD/RXR-DBD complex. Further biochemical assays showed that RAR, THR and NR4A2 do not form heterodimers with RXR when bound to the IR1 sites, which indicates that IR1 may be a unique binding site for the FXR/RXR heterodimer. Our studies may provide a further understanding of the dimerization specificity of nuclear receptors.

High expression of PD-L1 mainly occurs in non-small cell lung cancer patients with squamous cell carcinoma or poor differentiation.

Background: Lung cancer is one of the most lethal cancers worldwide, but studies have shown that the higher the expression of programmed cell death protein 1 ligand 1 (PD-L1) in non-small cell lung cancer (NSCLC), the more likely it will benefit from anti-PD-L1 immunotherapy. The purpose of our study was to collect and analyze abundant clinical samples in order to provide evidence for clinicians and patients who might consider anti-PD-L1 immunotherapy while jointly formulating treatment plans. Methods: On the one hand, we obtained cases from The Cancer Genome Atlas (TCGA) database, including 498 lung squamous cell cancer (LUSC) patients and 515 lung adenocarcinoma (LUAD) patients. We studied the lung caner driver gene in LUSC and LUAD. On the other hand, PD-L1 expression was detected in lung cancer tissues of 1,008 NSCLC patients with immunohistochemistry staining (IHC), and we studied the correlation between PD-L1 protein expression and clinicopathological characteristics. Results: PD-L1 expression was higher in LUSC than in LUAD at the mRNA level. In univariate analysis, PD-L1 expression at the protein level was higher in patients who were males, were LUSC, were smokers, had a tumor diameter >3 cm, had poor differentiation, or had stages III~IV disease. In multivariate analysis, PD-L1 expression was higher in patients who were LUSC or in poor differentiation. Conclusion: In term of protein level, PD-L1 expression was higher in NSCLC patients who were LUSC or in poor differentiation. We recommend that PD-L1 IHC detection can be routinely performed in such populations that are likely to benefit most from PD-L1 immunotherapy.

Signaling pathways in cancer metabolism: mechanisms and therapeutic targets.

A wide spectrum of metabolites (mainly, the three major nutrients and their derivatives) can be sensed by specific sensors, then trigger a series of signal transduction pathways and affect the expression levels of genes in epigenetics, which is called metabolite sensing. Life body regulates metabolism, immunity, and inflammation by metabolite sensing, coordinating the pathophysiology of the host to achieve balance with the external environment. Metabolic reprogramming in cancers cause different phenotypic characteristics of cancer cell from normal cell, including cell proliferation, migration, invasion, angiogenesis, etc. Metabolic disorders in cancer cells further create a microenvironment including many kinds of oncometabolites that are conducive to the growth of cancer, thus forming a vicious circle. At the same time, exogenous metabolites can also affect the biological behavior of tumors. Here, we discuss the metabolite sensing mechanisms of the three major nutrients and their derivatives, as well as their abnormalities in the development of various cancers, and discuss the potential therapeutic targets based on metabolite-sensing signaling pathways to prevent the progression of cancer.

Mutations and expressions of breast cancer 1/2 in lung cancer.

BACKGROUND: Breast cancer 1 (BRCA1) and breast cancer 2 (BRCA2) tumor suppressor genes play crucial roles in DNA repair and regulation of transcription. Mutations in these genes are closely associated with the occurrence of cancers. However, the mutation status of BRCA gene in central south Chinese lung cancer patients remains unclear, and its expression levels in lung cancer also need to be further explored. METHODS: In this study, we use next-generation sequencing (NGS) technology to analyze the BRCA genes mutations in 462 central south Chinese lung cancer patients. Public databases including cBioportal, Catalogue Of Somatic Mutations In Cancer (COSMIC), The Cancer Genome Atlas (TCGA), Human Protein Atlas (HPA) and Expression Profiling Interactive Analysis (GEPIA) are also applied to explore the expression level and mutation status of BRCA in lung cancer patients and their relationships with the prognosis. RESULTS: We found that the mutation rate of BRCA1/2 in central south Chinese lung cancer patients is 4.3% and 6.5% respectively, and missense mutations account for the majority in both BRCA1/2, which are similar to the international status of BRCA1/2 from public databases. In addition, 45 novel mutations of BRCA1/2 in lung cancer are reported in this study. Furthermore, we find that the BRCA2 mutations are negatively correlated with overall survival rate in lung cancer using cBioportal. Last, we demonstrate that both of the mRNA and protein levels of BRCA1/2 are upregulated in lung cancer, and the elevated mRNA expression levels are positively linked with poor prognosis. CONCLUSION: In general, our study better complements knowledge of the BRCA1/2 mutation status in the Chinese lung cancer patients, and firstly reveals the association between BRCA1/2 expression levels and prognosis of lung cancer patients, which may provide great value for the early diagnosis and clinical treatment of lung cancer.

Microsatellite Status Detection of Colorectal Cancer: Evaluation of Inconsistency between PCR and IHC.

Objective: An essential component of precision medical treatment for colorectal cancer (CRC) is the use of microsatellite state in combination with polymerase chain reaction (PCR) and immunohistochemistry (IHC) as the primary clinical detection methods. Microsatellite instability-high (MSI-H) or mismatch-repair deficiency (dMMR) accounts for about 15% of all CRC patients. Characterized by a high mutation burden, MSI-H is a predictive biomarker of immune checkpoint inhibitors (ICIs). Misdiagnosis of microsatellite status has been shown to be an important cause of resistance to immune checkpoint inhibitors. Therefore, a rapid and accurate assessment of microsatellite status can be beneficial for precision medicine in CRC. Methods: We evaluated the rate of discordance between PCR and IHC detection of microsatellite status from a cohort of patients that had 855 colorectal cancers. PCR-based microsatellite assay was performed using a set of five monomorphic mononucleotide makers (NR-24, BAT-25, CAT-25, BAT-26, MONO-27) and two polymorphic pentanucleotide (Penta D and Penta E). IHC was used to detect the absence of mismatch repair proteins (MLH1, MSH2, MSH6, and PMS2). The inconsistency rates of the two assays were evaluated. Results: Among 855 patients,15.6% (134 to 855) cases were identified as MSI-H by PCR, whereas 16.9% (145 to 855) cases were identified as dMMR by IHC. There were 45 patients with discordant results between IHC and PCR. Of these, 17 patients were classified as MSI-H/pMMR and 28 patients as MSS/dMMR. When the clinicopathological characteristics of these 45 patients were compared to those of the 855 patients, it was found that more patients were younger than 65 years old (80% to 63%), more were male (73% to 62%), more were located in the right colon (49% to 32%), and more were poorly differentiated (20% to 15%). Conclusion: Our study demonstrated a high concordance between the PCR and IHC results. In order to reduce the ineffective treatment of ICIs due to MSI misdiagnosis, the patient's age, gender, tumor location and degree of differentiation should be included in the clinician's selection of MSI testing in colorectal cancer.