Gene Expression Profile Identifies LncRNA AL355974.3 As a Potential Glioma Biomarker.

OBJECTIVE: Glioma is a central nervous system tumor arising from glial cells. Despite significant advances in diagnosis and treatment, most patients with high-grade gliomas have a poor prognosis. Many studies have shown that long noncoding RNAs (lncRNAs) may play important roles in the development, progression and treatment of many tumors, including gliomas. Molecularly targeted therapy may be a new direction for the adjuvant treatment of glioma. Therefore, we hope that by studying differentially expressed lncRNAs (DElncRNAs) in glioma, we can discover lncRNAs that can serve as biomarkers for glioma and provide better therapeutic modalities for glioma patients. METHODS: First, the expression of lncRNAs in 5 normal brain (NB) tissues and 10 glioma tissues was examined by RNA sequencing (RNA-seq). Next, we performed Kaplan-Meier analysis of data from The Cancer Genome Atlas (TCGA) database to assess the prognostic value of these variables. Finally, functional analysis of the DElncRNAs was performed by means of Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. RESULTS: RNA sequencing analysis revealed 85 upregulated miRNAs and 71 downregulated lncRNAs in low-grade glioma (LGG) and 50 upregulated lncRNAs and 70 downregulated lncRNAs in glioblastoma (GBM). Among them, AL355974.3 was the most upregulated lncRNA. LINC00632 was the most downregulated lncRNA. Second, LGG patients with higher AL355974.3 expression had worse overall survival according to Kaplan-Meier analysis of the TCGA database. Finally, bioinformatics analysis revealed that the target genes of these DElncRNAs were enriched in various biological processes and signaling pathways, such as cell metabolic and developmental processes. CONCLUSION: Our findings provide evidence that AL355974.3 may be a new biomarker for glioma.

Establishment of Human Pituitary Neuroendocrine Tumor Derived Organoid and Its Pilot Application for Drug Screening.

CONTEXT: Precision medicine for pituitary neuroendocrine tumors (PitNETs) is limited by the lack of reliable research models. OBJECTIVE: To generate patient-derived organoids (PDOs), which could serve as a platform for personalized drug screening for PitNET patients. DESIGN: From July 2019 to May 2022, a total of 32 human PitNET specimens were collected for the establishment of organoids with an optimized culture protocol. SETTING: This study was conducted at Sun Yat-Sen University Cancer Center. PATIENTS: PitNET patients who were pathologically confirmed were enrolled in this study. INTERVENTIONS: Histological staining and whole-exome sequencing were utilized to confirm the pathologic and genomic features of PDOs. A drug response assay on PDOs was also performed. MAIN OUTCOME MEASURES: PDOs retained key genetic and morphological features of their parental tumors. RESULTS: PDOs were successfully established from various types of PitNET samples with an overall success rate of 87.5%. Clinical nonfunctioning PitNETs-derived organoids (22/23, 95.7%) showed a higher likelihood of successful generation compared to those from functioning PitNETs (6/9, 66.7%). Preservation of cellular structure, subtype-specific neuroendocrine profiles, mutational features, and tumor microenvironment heterogeneity from parental tumors was observed. A distinctive response profile in drug tests was observed among the organoids from patients with different subtypes of PitNETs. With the validation of key characteristics from parental tumors in histological, genomic, and microenvironment heterogeneity consistency assays, we demonstrated the predictive value of the PDOs in testing individual drugs. CONCLUSION: The established PDOs, retaining typical features of parental tumors, indicate a translational significance in innovating personalized treatment for refractory PitNETs.

A population-based study of Helicobacter pylori: Does asymptomatic infection mean no gastroscopic lesions?

OBJECTIVES: We determined the common clinical characteristics of patients infected with Helicobacter pylori (H. pylori) and investigated the relationship between H. pylori infection, and clinical symptoms, and gastroscopic manifestations. Our focus was specifically on the clinical manifestations in asymptomatic patients. METHODS: We obtained the physical examination data of patients who underwent the 14C urea breath test between January 2018 and December 2020 at our Hospital. Basic demographic data, questionnaire data on clinical symptoms, and clinical examination data of the patients were also collected, and the correlation analysis was performed. RESULTS: A total of 2863 participants were included in the study. The overall H. pylori infection rate was 26.30%. The clinical symptoms between H. pylori-positive patients and H. pylori-negative patients did not differ significantly (P > .05). However, H. pylori-positive patients exhibited more severe gastroscopic manifestations (P < .001). The 14C urea breath test disintegrations per minute (DPM) values in H. pylori-positive patients correlated with their serum pepsinogen and gastrin-17 levels. With an increase in the DPM value, more combinations of clinical symptoms appeared in the patients. Among H. pylori-positive patients, DPM levels in asymptomatic patients were lower than those in symptomatic patients (P < .001). However, gastroscopic manifestations did not vary significantly between asymptomatic and symptomatic patients (P > .05). CONCLUSION: Patients infected with H. pylori showed no specific gastrointestinal symptoms. Patients with asymptomatic infection showed lower DPM levels, but their gastroscopic manifestations were similar to those of patients with symptomatic infection, and their lesions were more severe than H. pylori-negative people.

Effects of Stool Sample Preservation Methods on Gut Microbiota Biodiversity: New Original Data and Systematic Review with Meta-Analysis.

Here, we aimed to compare the effects of different preservation methods on outcomes of fecal microbiota. We evaluated the effects of different preservation methods using stool sample preservation experiments for up to 1 year. The stool samples from feces of healthy volunteers were grouped based on whether absolute ethanol was added and whether they were hypothermically preserved. Besides, we performed a systematic review to combine current fecal microbiota preservation evidence. We found that Proteobacteria changed significantly and Veillonellaceae decreased significantly in the 12th month in the room temperature + absolute ethanol group. The four cryopreservation groups have more similarities with fresh sample in the 12 months; however, different cryopreservation methods have different effects on several phyla, families, and genera. A systematic review showed that the Shannon diversity and Simpson index of samples stored in RNAlater for 1 month were not statistically significant compared with those stored immediately at -80°C (P = 0.220 and P = 0.123, respectively). The -80°C refrigerator and liquid nitrogen cryopreservation with 10% glycerine can both maintain stable microbiota of stool samples for long-term preservation. The addition of absolute ethanol to cryopreserved samples had no significant difference in the effect of preserving fecal microbial characteristics. Our study provides empirical insights into preservation details for future studies of the long-term preservation of fecal microbiota. Systematic review and meta-analysis found that the gut microbiota structure, composition, and diversity of samples preserved by storage methods, such as preservation solution, are relatively stable, which were suitable for short-term storage at room temperature. IMPORTANCE The study of gut bacteria has become increasingly popular, and fecal sample preservation methods and times need to be standardized. Here, we detail a 12-month study of fecal sample preservation, and our study provides an empirical reference about experimental details for long-term high-quality storage of fecal samples in the field of gut microbiology research. The results showed that the combination of -80°C/liquid nitrogen deep cryopreservation and 10% glycerol was the most effective method for the preservation of stool samples, which is suitable for long-term storage for at least 12 months. The addition of anhydrous ethanol to the deep cryopreserved samples did not make a significant difference in the preservation of fecal microbiological characteristics. Combined with the results of systematic reviews and meta-analyses, we believe that, when researchers preserve fecal specimens, it is essential to select the proper preservation method and time period in accordance with the goal of the study.

Poor Karnofsky performance status is not a contraindication for neurosurgical resection in patients with lung cancer brain metastases: a multicenter, retrospective PSM-IPTW cohort study.

BACKGOUND: Neurosurgical resection is a standard local treatment for lung cancer brain metastases (BMs). This study aims to investigate whether neurosurgical resection provides survival benefit in lung cancer BMs with poor KPS. MATERIALS AND METHODS: This multicenter retrospective study included 386 lung cancer BMs with pretreatment KPS ≤ 70 among a total of 1177 lung cancer BMs treated at three centers from August 2010 to July 2021. Data analysis was performed from July to September 2022. Inverse probability of treatment weighting (IPTW) and propensity scores matching (PSM) based on propensity scoring were used to minimize bias. The main outcome was overall survival (OS) after diagnosis of BMs. Risk factors of OS were estimated using Cox proportional hazards regression models. All Characteristics were included in the multivariate Cox regression. RESULTS: 386 patients with pretreatment KPS ≤ 70 were included (age mean [SD], 57.85 [10.36] years; KPS mean [SD], 60.91 [10.11]). Among them, 111 patients received neurosurgical resection, while 275 patients did not. Baseline characteristics were balanced between groups after IPTW or PSM. Neurosurgical resection was associated with significantly better prognosis in unadjusted multivariate COX analysis (hazard ratio [HR]: 0.68, 95% confidence interval [CI]: 0.51-0.91, P = 0.01), and PSM-adjusted multivariate COX analysis (HR: 0.61, 95%CI: 0.39-0.94, P = 0.03), IPTW-adjusted multivariate COX analysis (HR: 0.58, 95%CI: 0.40-0.84, P = 0.004). OS was significantly longer in neurosurgical resection group compared with non-surgical resection group according to unadjusted data (Median OS, surgery vs non-surgery, 14.7 vs 12.5 months, P = 0.01), PSM-adjusted data (median OS, 17.7 vs 12.3 months, P < 0.01) and IPTW-adjusted data (median OS, 17.7 vs 12.5 months, P < 0.01). CONCLUSIONS: Neurosurgical resection was associated with improved survival in patients with lung cancer BMs with poor KPS, suggesting that poor KPS is not a contraindication for neurosurgical resection in these patients.

Survival Benefits of Radiotherapy and Surgery in Lung Cancer Brain Metastases with Poor Prognosis Factors.

BACKGROUND: Radiotherapy and surgery are the standard local treatments for lung cancer brain metastases (BMs). However, limited studies focused on the effects of radiotherapy and surgery in lung cancer BMs with poor prognosis factors. METHODS: We retrospectively analyzed 714 patients with lung cancer BMs. Analyses of overall survival (OS) and risk factors for OS were assessed by the log-rank test and Cox proportional hazard model. RESULTS: Age ≥ 65 years, a Karnofsky Performance Scale (KPS) score ≤ 70, anaplastic large-cell lymphoma kinase (ALK)/epidermal growth factor receptor (EGFR) wild type, and extracranial metastases were related to poor prognosis. Patients were stratified according to these poor prognosis factors. In patients with the ALK/EGFR wild type, whole brain radiotherapy (WBRT), stereotactic radiosurgery (SRS), and surgery improved the OS of patients. WBRT and SRS were the independent protective factors for OS. In patients with extracranial metastases, patients who received WBRT plus SRS or WBRT alone had longer OS than those who did not receive radiotherapy. WBRT plus SRS and WBRT were the independent protective factors for OS. CONCLUSIONS: Radiotherapy and surgery are associated with improved survival for lung cancer BMs with the ALK/EGFR wild type. Radiotherapy is associated with improved survival in lung cancer BMs with extracranial metastases.

Adaptive multi-degree-of-freedom in situ bioprinting robot for hair-follicle-inclusive skin repair: A preliminary study conducted in mice.

Skin acts as an essential barrier, protecting organisms from their environment. For skin trauma caused by accidental injuries, rapid healing, personalization, and functionality are vital requirements in clinical, which are the bottlenecks hindering the translation of skin repair from benchside to bedside. Herein, we described a novel design and a proof-of-concept demonstration of an adaptive bioprinting robot to proceed rapid in situ bioprinting on a full-thickness excisional wound in mice. The three-dimensional (3D) scanning and closed-loop visual system integrated in the robot and the multi-degree-of-freedom mechanism provide immediate, precise, and complete wound coverage through stereotactic bioprinting, which hits the key requirements of rapid-healing and personalization in skin repair. Combined with the robot, epidermal stem cells and skin-derived precursors isolated from neonatal mice mixed with Matrigel were directly printed into the injured area to replicate the skin structure. Excisional wounds after bioprinting showed complete wound healing and functional skin tissue regeneration that closely resembling native skin, including epidermis, dermis, blood vessels, hair follicles and sebaceous glands etc. This study provides an effective strategy for skin repair through the combination of the novel robot and a bioactive bioink, and has a promising clinical translational potential for further applications.

Analysis of the potential role of photocurable hydrogel in patient-derived glioblastoma organoid culture through RNA sequencing.

Patient-derived glioblastoma organoid (GBO) growth in hydrogels recapitulates key features of parental tumors, making GBOs a useful tool for fundamental research on cancer biology and offer deeper insight into the development of innovative therapeutic strategies for cancer treatment. Matrigel as a natural hydrogel has been widely used for 3D culture in most tumor organoid studies, but the volatility in its biochemical and biophysical properties makes it difficult to be further applied in GBO cultures. Thus, several kinds of biomimetic hydrogels from synthetic or biological polymers have been developed for tumor organoid growth. Here, we innovatively utilize a photocurable hydrogel-based biomimetic instructive system containing gelatin methacryloyl (GelMA) mixed with a hyaluronic acid (HA) hydrogel as a scaffold for generating GBOs. Furthermore, we evaluated the GBO biological properties at the transcriptome level, which showed that GBOs cultured with this hydrogel retain the expression profile of key neurodevelopmental markers, driving mutations and alternative splicing of parental tumors. Notably, GBOs cultured with the photocurable hydrogel may provide a platform for precision cancer medicine, bridging the gap between basic research and clinical application. Although significant challenges remain, biomimetic hydrogels can provide an exceptional window for the construction of tumor organoids to ensure the accuracy of the research and clinical data.

Preparation of a "Branch-Fruit" structure chitosan nanofiber physical hydrogels with high mechanical strength and pH-responsive controlled drug release properties.

The poor mechanical properties of chitosan physical hydrogels seriously hinder their application in the biomedical field. Inspired by the structure of cell tissues, a novel chitosan nanofiber (CSNF)/Hyaluronic acid (HA)/ß-glycerophosphate disodium (ß-GP) drug-loaded hydrogel was prepared by micro-dissolution and physical crosslinking. The hydrogel has a "Branch-Fruit" structure and exhibits excellent mechanical properties, good biocompatibility and cell-adhesion properties. Human cancer cells (HeLa) can adhere to the hydrogel surface, which might facilitate tumor site-specific administration of drugs. This material also exhibits high pH sensitivity, with which drug release can be triggered under acidic conditions at pH 4.00. The mechanical strength and drug release behavior of this hydrogel can be easily adjusted by varying the CSNF content.

Survival Benefit from Surgical Resection in Lung Cancer Patients with Brain Metastases: a Single-Center, Propensity-Matched Analysis Cohort Study.

BACKGROUND: Brain metastases (BMs) are the most serious complication of lung cancer, affecting the prognosis of lung cancer patients, and pose distinct clinical challenges. This study was designed to explore the prognostic factors related to lung cancer BM and the value of surgical resection in BMs from lung cancer. METHODS: A retrospective analysis was performed on 714 patients with lung cancer BMs screened between January 2010 and January 2018 at the Sun Yat-sen University Cancer Center. A 1:1 propensity score matching analysis was performed to reduce the potential bias between the surgery and the nonsurgery group. In both the raw and the propensity-score matched dataset, univariate and multivariate Cox proportional hazards regression analyses were used to evaluate risk factors for survival. RESULTS: After matching, 258 patients (129 surgery, 129 no surgery) were analyzed. Multivariate analyses after propensity score matching demonstrated that surgical resection was an independent protective factor for overall survival (OS), and older age, lower Karnofsky Performance Scale (KPS) score, and extracranial metastases were independent risk factors for worse OS. Patients without extracranial metastases, without synchronous BM and with a single BM had a better prognosis. CONCLUSIONS: The findings showed that surgical resection, age, KPS score, and extracranial metastases are independent prognostic factors for predicting the OS of patients with lung cancer BMs, and surgical resection for brain metastatic lesions could significantly improve the OS. However, only certain groups of patients with BMs can benefit from intracranial lesion resection, such as no extracranial metastases and metachronous metastases.

Electrospun poly (L-lactic acid)/gelatine membranes loaded with doxorubicin for effective suppression of glioblastoma cell growth in vitro and in vivo.

Electrospun membranes are attracting interest as a drug delivery system because of their material composition flexibility and versatile drug loading. In this study, the electrospun membrane was loaded with doxorubicin (DOX) via electrostatic adsorption for long-term drug delivery. DOX loading process was optimized by varying temperature, time, drug concentration, pH and ionic strength of solutions. The loading process did not impair the structural properties of the membrane. Next, we investigated the drug release kinetics using spectroscopic techniques. The composite membranes released 22% of the adsorbed DOX over the first 48 h, followed by a slower and sustained release over 4 weeks. The DOX release was sensitive to acidic solutions that the release rate at pH 6.0 was 1.27 times as that at pH 7.4. The DOX-loaded membranes were found to be cytotoxic to U-87 MG cells in vitro that decreased the cell viability from 82.92% to 25.49% from 24 to 72 h of co-incubation. These membranes showed strong efficacy in suppressing tumour growth in vivo in glioblastoma-bearing mice that decreased the tumour volume by 77.33% compared with blank membrane-treated group on Day 20. In conclusion, we have developed an effective approach to load DOX within a clinically approved poly (L-lactic acid)/gelatine membrane for local and long-term delivery of DOX for the treatment of glioblastoma.

Immunogenomic Profiling Demonstrate AC003092.1 as an Immune-Related eRNA in Glioblastoma Multiforme.

Enhancer RNAs, a type of long non-coding RNAs (lncRNAs), play a critical role in the occurrence and development of glioma. RNA-seq data from 161 glioblastoma multiforme (GBM) samples were acquired from The Cancer Genome Atlas database. Then, 70 eRNAs were identified as prognosis-related genes, which had significant relations with overall survival (log-rank test, p < 0.05). AC003092.1 was demonstrated as an immune-related eRNA by functional enrichment analysis. We divided samples into two groups based on AC003092.1 expression: AC003092.1 High (AC003092.1_H) and AC003092.1 Low (AC003092.1_L) and systematically analyzed the influence of AC003092.1 on the immune microenvironment by single-sample gene-set enrichment analysis and CIBERSORTx. We quantified AC003092.1 and TFPI2 levels in 11 high-grade gliomas, 5 low-grade gliomas, and 7 GBM cell lines. Our study indicates that AC003092.1 is related to glioma-immunosuppressive microenvironment, and these results offer innovative sights into GBM immune therapy.

Membranes for bioethanol production by pervaporation.

BACKGROUND: Bioethanol as a renewable energy resource plays an important role in alleviating energy crisis and environmental protection. Pervaporation has achieved increasing attention because of its potential to be a useful way to separate ethanol from the biomass fermentation process. RESULTS: This overview of ethanol separation via pervaporation primarily concentrates on transport mechanisms, fabrication methods, and membrane materials. The research and development of polymeric, inorganic, and mixed matrix membranes are reviewed from the perspective of membrane materials as well as modification methods. The recovery performance of the existing pervaporation membranes for ethanol solutions is compared, and the approaches to further improve the pervaporation performance are also discussed. CONCLUSIONS: Overall, exploring the possibility and limitation of the separation performance of PV membranes for ethanol extraction is a long-standing topic. Collectively, the quest is to break the trade-off between membrane permeability and selectivity. Based on the facilitated transport mechanism, further exploration of ethanol-selective membranes may focus on constructing a well-designed microstructure, providing active sites for facilitating the fast transport of ethanol molecules, hence achieving both high selectivity and permeability simultaneously. Finally, it is expected that more and more successful research could be realized into commercial products and this separation process will be deployed in industrial practices in the near future.

A novel Foxp3-related immune prognostic signature for glioblastoma multiforme based on immunogenomic profiling.

Foxp3+ regulatory T cells (Treg) play an important part in the glioma immunosuppressive microenvironment. This study analyzed the effect of Foxsp3 on the immune microenvironment and constructed a Foxp3-related immune prognostic signature (IPS)for predicting prognosis in glioblastoma multiforme (GBM). Immunohistochemistry (IHC) staining for Foxp3 was performed in 72 high-grade glioma specimens. RNA-seq data from 152 GBM samples were obtained from The Cancer Genome Atlas database (TCGA) and divided into two groups, Foxp3 High (Foxp3_H) and Foxp3 Low (Foxp3_L), based on Foxp3 expression. We systematically analyzed the influence of Foxp3 on the immune microenvironment. Least Absolute Shrinkage and Selection Operator (LASSO) Cox analysis was conducted for immune-related genes that were differentially expressed between Foxp3_H and Foxp3_L GBM patients. We found a differential expression of Foxp3 in high-grade glioma tissues. The presence of Foxp3 was significantly associated with poor OS. From the four-gene IPS developed, GBM patients were stratified into low-risk and high-risk groups in both the training set and validation sets. Furthermore, we developed a novel nomogram to evaluate the overall survival in GBM patients. This study offers innovative insights into the GBM immune microenvironment and these findings contribute to individualized treatment and improvement in the prognosis for GBM patients.

Assessment of circulating tumor DNA in cerebrospinal fluid by whole exome sequencing to detect genomic alterations of glioblastoma.

BACKGROUND: Cerebrospinal fluid (CSF) has been demonstrated as a better source of circulating tumor DNA (ctDNA) than plasma for brain tumors. However, it is unclear whether whole exome sequencing (WES) is qualified for detection of ctDNA in CSF. The aim of this study was to determine if assessment of ctDNA in CSF by WES is a feasible approach to detect genomic alterations of glioblastoma. METHODS: CSFs of ten glioblastoma patients were collected pre-operatively at the Department of Neurosurgery, Sun Yat-sen University Cancer Center. ctDNA in CSF and genome DNA in the resected tumor were extracted and subjected to WES. The identified glioblastoma-associated mutations from ctDNA in CSF and genome DNA in the resected tumor were compared. RESULTS: Due to the ctDNA in CSF was unqualified for exome sequencing for one patient, nine patients were included into the final analysis. More glioblastoma-associated mutations tended to be detected in CSF compared with the corresponding tumor tissue samples (3.56 ±â€Š0.75 vs. 2.22 ±â€Š0.32, P = 0.097), while the statistical significance was limited by the small sample size. The average mutation frequencies were similar in CSF and tumor tissue samples (74.1% ±â€Š6.0% vs. 73.8% ±â€Š6.0%, P = 0.924). The R132H mutation of isocitrate dehydrogenase 1 and the G34V mutation of H3 histone, family 3A (H3F3A) which had been reported in the pathological diagnoses were also detected from ctDNA in CSF by WES. Patients who received temozolomide chemotherapy previously or those whose tumor involved subventricular zone tended to harbor more mutations in their CSF. CONCLUSION: Assessment of ctDNA in CSF by WES is a feasible approach to detect genomic alterations of glioblastoma, which may provide useful information for the decision of treatment strategy.

SRSF3 functions as an oncogene in colorectal cancer by regulating the expression of ArhGAP30.

BACKGROUND: Splicing factor SRSF3 is an oncogene and overexpressed in various kinds of cancers, however, the function and mechanism involved in colorectal cancer (CRC) remained unclear. The aim of this study was to explore the relationship between SRSF3 and carcinogenesis and progression of CRC. METHODS: The expression of SRSF3 in CRC tissues was detected by immunohistochemistry. The proliferation and invasion rate was analyzed by CCK-8 assay, colony formation assay, transwell invasion assay and xenograft experiment. The expression of selected genes was detected by western blot or real time PCR. RESULTS: SRSF3 is overexpressed in CRC tissues and its high expression was associated with CRC differentiation, lymph node invasion and AJCC stage. Upregulation of SRSF3 was also associated with shorter overall survival. Knockdown of SRSF3 in CRC cells activated ArhGAP30/Ace-p53 and decreased cell proliferation, migration and survival; while ectopic expression of SRSF3 attenuated ArhGAP30/Ace-p53 and increases cell proliferation, migration and survival. Targeting SRSF3 in xenograft tumors suppressed tumor progression in vivo. CONCLUSIONS: Taken together, our data identify SRSF3 as a regulator for ArhGAP30/Ace-p53 in CRC, and highlight potential prognostic and therapeutic significance of SRSF3 in CRC.

Rise of PD-L1 expression during metastasis of colorectal cancer: Implications for immunotherapy.

OBJECTIVE: Programmed death-ligand 1 (PD-L1) expression in colorectal cancer (CRC) was implicated in predicting anti-PD-1/PD-L1 therapy efficacy. However, therapeutic response has also been found in patients without PD-L1 expression in the primary tumor. In the present study, we aimed to clarify the prevalence of PD-L1 in primary and metastatic CRC. METHODS: The expression of PD-L1 was determined by immunohistochemistry in matched primary and metastatic CRC. RESULTS: PD-L1 expression was significantly more prevalent in metastatic CRCs than in primary tumors, and the expression of PD-L1 in primary CRC may not represent the tumors that spread to distant organs. Positive expression of PD-L1 was found in 81.8% of metastatic CRC, being significantly more prevalent than in primary CRC (40.9%; P = 0.012, Fisher's exact test). While comparing the primary and metastatic lesions of the same patients, we found that PD-L1 expression frequently increased during the metastatic process. However, PD-L1 expression was rarely decreased in metastatic lesions. Intratumoral heterogeneity expression of PD-L1 was found in both metastatic CRC (22.2%) and primary CRCs (33.3%). PD-L1 was prevalently expressed in metastatic CRC, and increased PD-L1 expression was frequently found in metastatic CRC as compared to primary tumors. CONCLUSION: PD-L1 expression in metastatic CRC should be considered as an independent factor while evaluating the suitability of patients for immunotherapy.