Targeting tumor­associated macrophages: Critical players in tumor progression and therapeutic strategies (Review).

Tumor­associated macrophages (TAMs) are essential components of the tumor microenvironment (TME) and display phenotypic heterogeneity and plasticity associated with the stimulation of bioactive molecules within the TME. TAMs predominantly exhibit tumor­promoting phenotypes involved in tumor progression, such as tumor angiogenesis, metastasis, immunosuppression and resistance to therapies. In addition, TAMs have the potential to regulate the cytotoxic elimination and phagocytosis of cancer cells and interact with other immune cells to engage in the innate and adaptive immune systems. In this context, targeting TAMs has been a popular area of research in cancer therapy, and a comprehensive understanding of the complex role of TAMs in tumor progression and exploration of macrophage­based therapeutic approaches are essential for future therapeutics against cancers. The present review provided a comprehensive and updated overview of the function of TAMs in tumor progression, summarized recent advances in TAM­targeting therapeutic strategies and discussed the obstacles and perspectives of TAM­targeting therapies for cancers.

Asymptomatic low-grade appendiceal mucinous neoplasm: A case report.

BACKGROUND: Low-grade appendiceal neoplasms (LAMN) are characterized by low incidence and atypical clinical presentations, often leading to misdiagnosis as acute or chronic appendicitis before surgery. The primary diagnostic tool for LAMN is abdominal computed tomography (CT) imaging. Surgical resection remains the cornerstone of LAMN management, necessitating en bloc tumor excision to minimize the risk of iatrogenic rupture. Laparoscopy, known for its minimal invasiveness, reduced postoperative discomfort, and expedited recovery, is a safe and reliable approach for LAMN treatment. Despite the possibility of pseudomyxoma peritonei development, appendectomy and partial appendectomy generally result in negative tumor margins and favorable outcomes, which can be attributed to the disease's slow growth and lower malignancy. CASE SUMMARY: A 71-year-old male patient was admitted to our hospital with a pelvic space-occupying lesion detected 1 mo prior. Physical examination showed a soft abdomen without tenderness or rebound and no palpable masses. No shifting dullness was noted, and digital rectal examination revealed no palpable mass. Enteroscopy revealed a raised, smooth-surfaced mass measuring 3.0 cm in the cecum. Abdominal contrast-enhanced CT showed a markedly thickened and dilated appendix with visible cystic shadows. Laparoscopic surgery was performed and revealed a significantly dilated appendix, leading to laparoscopic resection of the appendix and part of the cecum. Post-surgical pathologic analysis confirmed LAMN. The patient received symptomatic and supportive post-operative care and was discharged on postoperative day 4 without complications such as abdominal bleeding, intestinal obstruction, or incision infection. No tumor recurrence was observed during a 7-mo follow-up period. CONCLUSION: LAMN is a rare disease that lacks specific clinical manifestations. Abdominal CT plays a crucial role in diagnosing LAMN, and laparoscopic surgery is a safe and effective diagnostic and therapeutic approach.

Comparison of manual sutures and laparoscopic stapler for pancreatic stump closure techniques in robotic distal pancreatectomy: a single-center experience.

BACKGROUND: Postoperative pancreatic fistulas (POPFs) are prevalent and major postoperative complications of distal pancreatectomy (DP). There are numerous ways to manage the pancreatic stump. However, no single approach has been shown to be consistently superior. Moreover, the potential role of robotic systems in reducing POPFs has received little attention. METHODS: The clinical data of 119 patients who had consecutively received robotic distal pancreatectomy between January 2019 and December 2022 were retrospectively analyzed. Patients were divided into two groups according to the method of handling the pancreatic stump. The attributes of the patients and the variables during the perioperative period were compared. RESULTS: The analysis included 72 manual sutures and 47 stapler procedures. The manual suture group had a shorter operative time (removing installation time) than the stapler group (125.25 ± 63.04 min vs 153.30 ± 62.03 min, p = 0.019). Additionally, the manual suture group had lower estimated blood loss (50 mL vs 100 mL, p = 0.009) and a shorter postoperative hospital stay. There were no significant differences in the incidence of clinically relevant POPFs between the two groups (18.1% vs 23.4%, P > 0.05). No perioperative death occurred in either group. CONCLUSION: The manual suturing technique was shown to have an incidence of POPFs similar to the stapler technique in robotic distal pancreatectomy and to be safe and feasible.

Protocadherin-1 serves as a prognostic biomarker and promotes pancreatic cancer progression by suppressing CD8+ T cell infiltration through CCL5-CCR5 axis.

Previous studies have shown that Protocadherins (PCDHs) enhance tumor proliferation, invasion, and metastasis; yet their role in pancreatic cancer (PC) progression and the tumor immune microenvironment remains unclear. This study aims to elucidate the role of PCDH1 in different cancer types, with a particular focus on its impact on immune suppression in PC. Utilizing data from TCGA, GTEx, and Gent2 databases, we assessed the expression of PCDH1 across various cancer types. The prognostic value of PCDH1 was demonstrated through Cox regression, Kaplan-Meier analysis, and ROC curve, while its relationship with gene mutations, tumor mutational burden (TMB), immune cell infiltration, and other clinical factors was investigated using Spearman correlation. Furthermore, the effect of PCDH1 on PC malignancy was experimentally validated by a series of in vitro and in vivo assays. Our results show a significant upregulation of PCDH1 in various tumor types, which is associated with poor prognosis, suggesting its potential application as an independent prognostic biomarker. Notably, in PC, PCDH1 exhibited significant associations with gene mutations, TMB, and immune cell infiltration. Clinical validations revealed a correlation between high PCDH1 expression and poor prognosis, coupled with a low level of CD8+ T cell infiltration. Furthermore, both in vitro and in vivo experiments confirmed the role of PCDH1 in promoting PC cell proliferation and migration while inhibiting CD8+ T cell recruitment through its modulation of CCL5-CCR5 axis. In conclusion, PCDH1 regulates the proliferation and migration of PC cells as well as CD8+ T cell infiltration in PC. PCDH1 may serve as a prognostic biomarker in multiple tumor types.

Electrostatic Nanocage-Confined Probe for Electrochemical Detection of CA19-9 in Human Serum.

Prompt and accurate detection of CA19-9 in human serum has great clinical significance for the early diagnosis and disease monitoring of cancer. Herein, we develop a convenient and antifouling electrochemical sensor for CA19-9 determination by immobilization of both an electrochemical redox probe [methylene blue (MB)] and immunorecognition element (CA19-9 antibody) on an electrostatic nanocage consisting of bipolar silica nanochannel array (bp-SNA). bp-SNA is composed of a negatively charged inner layer (n-SNA) and positively charged outer layer (p-SNA), which could be stably prepared on indium tin oxide (ITO) in several seconds using a two-step electrochemically assisted self-assembly approach and display asymmetric surface charges for confinement and enrichment of cationic MB into the inner n-SNA layer through electrostatic interaction. Modification of the CA19-9 antibody on the top surface of bp-SNA confers the sensing interface with specific recognition capacity. An antibody-antigen complex formed at the as-prepared immunosensor causes the decreased electrochemical signals of MB, achieving sensitive determination of CA19-9 with a wider linear dynamic range from 10 µU/mL to 50 U/mL and a low detection limit (3 µU/mL). Furthermore, accurate and feasible analysis of the CA19-9 amount in human serum samples by our proposed probe-integrated electrochemical immunosensor is realized.

Causal effect between gut microbiota and pancreatic cancer: a two-sample Mendelian randomization study.

BACKGROUND: Gut microbiota (GM) comprises a vast and diverse community of microorganisms, and recent studies have highlighted the crucial regulatory roles of various GM and their secreted metabolites in pancreatic cancer (PC). However, the causal relationship between GM and PC has yet to be confirmed. METHODS: In the present study, we used two-sample Mendelian randomization (MR) analysis to investigate the causal effect between GM and PC, with genome-wide association study (GWAS) from MiBioGen consortium as an exposure factor and PC GWAS data from FinnGen as an outcome factor. Inverse variance weighted (IVW) was used as the primary method for this study. RESULTS: At the genus level, we observed that Senegalimassilia (OR: 0.635, 95% CI: 0.403-0.998, P = 0.049) exhibited a protective effect against PC, while Odoribacter (OR:1.899, 95%CI:1.157-3.116, P = 0.011), Ruminiclostridium 9(OR:1.976,95%CI:1.128-3.461, P = 0.017), Ruminococcaceae (UCG011)(OR:1.433, 95%CI:1.072-1.916, P = 0.015), and Streptococcus(OR:1.712, 95%CI:1.071-1.736, P = 0.025) were identified as causative factors for PC. Additionally, sensitivity analysis, Cochran's Q test, the Mendelian randomization pleiotropy residual sum and outlier (MR-PRESSO), and MR-Egger regression indicated no heterogeneity, horizontal pleiotropy, or reverse causality between GM and PC. CONCLUSIONS: Our analysis establishes a causal effect between specific GM and PC, which may provide new insights into the potential pathogenic mechanisms of GM in PC and the assignment of effective therapeutic strategies.

Digestive tract reconstruction after laparoscopic proximal gastrectomy for Gastric cancer: A systematic review.

The incidence of gastroesophageal junction adenocarcinoma has gradually increased. Proximal gastrectomy or total gastrectomy is recommended for early gastric cancer of the upper third of the stomach. Because total gastrectomy is often accompanied by body mass loss and nutrient absorption disorders, such as severe hypoproteinemia and anemia, Proximal gastrectomy is more frequently recommended by researchers for early upper gastric cancer (T1N0M0) and Siewert II gastroesophageal junction cancer less than 4 cm in length. Although some functions of the stomach are retained after proximal gastrectomy, the anatomical structure of the gastroesophageal junction can be destroyed, and the anti-reflux effect of the cardia is lost. In recent years, as various reconstruction methods for anti-reflux function have been developed, some functions of the stomach are retained, and serious reflux esophagitis is avoided after proximal gastrectomy. In this article, we summarized the indications, advantages, and disadvantages of various classic reconstruction methods and latest improved reconstruction method including esophageal and residual stomach anastomosis, tubular gastroesophageal anastomosis, muscle flap anastomosis, jejunal interposition, and double-tract reconstruction.

Biological characteristics of pancreatic ductal adenocarcinoma: Initiation to malignancy, intracellular to extracellular.

Pancreatic ductal adenocarcinoma (PDAC) is a highly life-threatening tumour with a low early-detection rate, rapid progression and a tendency to develop resistance to chemotherapy. Therefore, understanding the regulatory mechanisms underlying the initiation, development and metastasis of pancreatic cancer is necessary for enhancing therapeutic effectiveness. In this review, we summarised single-gene mutations (including KRAS, CDKN2A, TP53, SMAD4 and some other less prevalent mutations), epigenetic changes (including DNA methylation, histone modifications and RNA interference) and large chromosome alterations (such as copy number variations, chromosome rearrangements and chromothripsis) associated with PDAC. In addition, we discussed variations in signalling pathways that act as intermediate oncogenic factors in PDAC, including PI3K/AKT, MAPK/ERK, Hippo and TGF-ß signalling pathways. The focus of this review was to investigate alterations in the microenvironment of PDAC, particularly the role of immunosuppressive cells, cancer-associated fibroblasts, lymphocytes, other para-cancerous cells and tumour extracellular matrix in tumour progression. Peripheral axons innervating the pancreas have been reported to play a crucial role in the development of cancer. In addition, tumour cells can influence the behaviour of neighbouring non-tumour cells by secreting certain factors, both locally and at a distance. In this review, we elucidated the alterations in intracellular molecules and the extracellular environment that occur during the progression of PDAC. Altogether, this review may enhance the understanding of the biological characteristics of PDAC and guide the development of more precise treatment strategies.

Reoperation for heterochronic intraductal papillary mucinous neoplasm of the pancreas after bile duct neoplasm resection: A case report.

BACKGROUND: Intraductal papillary neoplasm of the bile duct (IPNB) and intraductal papillary mucinous neoplasm (IPMN) of the pancreas have similar pathological manifestations. However, they often develop separately and it is rare for both to occur together. Patients presenting with heterochronic IPMN after IPNB are prone to be misdiagnosed with tumor recurrence. CASE SUMMARY: A 67-year-old male patient was admitted 8.5 years after IPNB carcinoma and 4 years after the discovery of a pancreatic tumor. A left hepatic bile duct tumor with distal bile duct dilatation was found 8.5 years ago by the computed tomography; therefore, a left hepatectomy was performed. The postoperative pathological diagnosis was malignant IPNB with negative cutting edge and pathological stage T1N0M0. Magnetic resonance imaging 4 years ago showed cystic lesions in the pancreatic head with pancreatic duct dilatation, and carcinoembryonic antigen continued to increase. Positron emission tomography showed a maximum standard uptake value of 11.8 in the soft tissue mass in the pancreatic head, and a malignant tumor was considered. Radical pancreatoduodenectomy was performed. Postoperative pathological diagnosis was pancreatic head IPMN with negative cutting edge, pancreaticobiliary type, stage T3N0M0. He was discharged 15 d after the operation. Follow-up for 6 mo showed no tumor recurrence, and quality of life was good. CONCLUSION: IPNB and IPMN are precancerous lesions with similar pathological characteristics and require active surgery and long-term follow-up.

Factors predicting recurrence after left­sided pancreatectomy for pancreatic ductal adenocarcinoma.

BACKGROUND: Recurrence after resection is the main factor for poor survival. The relationship between clinicopathological factors and recurrence after curative distal pancreatectomy for PDAC has rarely been reported separately. METHODS: Patients with PDAC after left­sided pancreatectomy between May 2015 and August 2021 were retrospectively identified. RESULTS: One hundred forty-one patients were included. Recurrence was observed in 97 patients (68.8%), while 44 (31.2%) patients had no recurrence. The median RFS was 8.8 months. The median OS was 24.9 months. Local recurrence was the predominant first detected recurrence site (n = 36, 37.1%), closely followed by liver recurrence (n = 35, 36.1%). Multiple recurrences occurred in 16 (16.5%) patients, peritoneal recurrence in 6 (6.2%) patients, and lung recurrence in 4 (4.1%) patients. High CA19-9 value after surgery, poor differentiation grade, and positive lymph nodes were found to be independently associated with recurrence. The patients receiving adjuvant chemotherapy had a decreased likelihood of recurrence. In the high CA19-9 value cohort, the median PFS and OS of the patients with or without chemotherapy were 8.0 VS. 5.7 months and 15.6 VS. 13.8 months, respectively. In the normal CA19-9 value cohort, there was no significant difference in PFS with or without chemotherapy (11.7 VS. 10.0 months, P = 0.147). However, OS was significantly longer in the patients with chemotherapy (26.4 VS. 13.8 months, P = 0.019). CONCLUSIONS: Tumor biologic characteristics, such as T stage, tumor differentiation and positive lymph nodes, affecting CA19-9 value after surgery are associated with patterns and timing of recurrence. Adjuvant chemotherapy significantly reduced recurrence and improved survival. Chemotherapy is strongly recommended in patients with high CA199 after surgery.

Roles of lncRNAs in pancreatic ductal adenocarcinoma: Diagnosis, treatment, and the development of drug resistance.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal cancers, primarily due to its late diagnosis, high propensity to metastasis, and the development of resistance to chemo-/radiotherapy. Accumulating evidence suggests that long non-coding RNAs (lncRNAs) are intimately involved in the treatment resistance of pancreatic cancer cells via interacting with critical signaling pathways and may serve as potential diagnostic/prognostic markers or therapeutic targets in PDAC. DATA SOURCES: We carried out a systematic review on lncRNAs-based research in the context of pancreatic cancer and presented an overview of the updated information regarding the molecular mechanisms underlying lncRNAs-modulated pancreatic cancer progression and drug resistance, together with their potential value in diagnosis, prognosis, and treatment of PDAC. Literature mining was performed in PubMed with the following keywords: long non-coding RNA, pancreatic ductal adenocarcinoma, pancreatic cancer up to January 2022. Publications relevant to the roles of lncRNAs in diagnosis, prognosis, drug resistance, and therapy of PDAC were collected and systematically reviewed. RESULTS: LncRNAs, such as HOTAIR, HOTTIP, and PVT1, play essential roles in regulating pancreatic cancer cell proliferation, invasion, migration, and drug resistance, thus may serve as potential diagnostic/prognostic markers or therapeutic targets in PDAC. They participate in tumorigenesis mainly by targeting miRNAs, interacting with signaling molecules, and involving in the epithelial-mesenchymal transition process. CONCLUSIONS: The functional lncRNAs play essential roles in pancreatic cancer cell proliferation, invasion, migration, and drug resistance and have potential values in diagnosis, prognostic prediction, and treatment of PDAC.

Functions and clinical applications of exosomes in pancreatic cancer.

Pancreatic cancer (PC) is one of the most malignant tumors and has an abysmal prognosis, with a 5-year survival rate of only 11%. At present, the main clinical dilemmas in PC are the lack of biomarkers and the unsatisfactory therapeutic effects. The treatments for and outcomes of PC have improved, but remain unsatisfactory. Exosomes are nanosized extracellular vesicles, and an increasing number of studies have found that exosomes play an essential role in tumor pathology. In this review, we describe the process of exosome biogenesis, as well as exosome extraction methods and identification strategies, and we then explain in detail the roles and mechanisms of exosomes in invasion, metastasis, chemoresistance and immunosuppression in PC. Finally, we summarize the clinical applications of exosomes. Our observations indicate that exosomes represent a novel direction in the clinical treatment of PC.

PBRM1 presents a potential prognostic marker and therapeutic target in duodenal papillary carcinoma.

BACKGROUND: Due to its rarity, duodenal papillary carcinoma (DPC) is seldom studied as a unique disease and no specific molecular features or treatment guidelines are provided. METHODS: Whole-exome sequencing was performed to gain new insights into the DPC mutation landscape and to identify potential signalling pathways and therapeutic targets. Mechanistically, immunohistochemistry (IHC), immunofluorescence, RNA-seq, ATAC-seq and in vitro cell function experiments were performed to confirm the underlying mechanisms. RESULTS: We described the mutational landscape of DPC for the first time as a group of rare tumours with a high frequency of dysregulation in the chromatin remodelling pathway, particularly PBRM1-inactivating mutations that are significantly higher than duodenal adenocarcinomas and ampullary adenocarcinoma (27% vs. 0% vs. 7%, p < .01). In vitro cell experiments showed that downregulation of PBRM1 expression could significantly promote the cancer progression and epithelial-to-mesenchymal transition via the PBRM1-c-JUN-VIM axis. The IHC data indicated that PBRM1 deficiency (p = .047) and c-JUN expression (p < .001) were significantly associated with poor prognosis. Meanwhile, the downregulation of PBRM1 expression in HUTU-80 cells was sensitive to radiation, which may be due to the suppression of c-JUN by irradiation. CONCLUSIONS: Our findings define a novel molecular subgroup of PBRM1-inactivating mutations in DPC. PBRM1 play an important role in DPC progression and may serve as a potential therapeutic target and prognostic indicator.

The Role and Therapeutic Potential of Macropinocytosis in Cancer.

Macropinocytosis, a unique endocytosis pathway characterized by nonspecific internalization, has a vital role in the uptake of extracellular substances and antigen presentation. It is known to have dual effects on cancer cells, depending on cancer type and certain microenvironmental conditions. It helps cancer cells survive in nutrient-deficient environments, enhances resistance to anticancer drugs, and promotes invasion and metastasis. Conversely, overexpression of the RAS gene alongside drug treatment can lead to methuosis, a novel mode of cell death. The survival and proliferation of cancer cells is closely related to macropinocytosis in the tumor microenvironment (TME), but identifying how these cells interface with the TME is crucial for creating drugs that can limit cancer progression and metastasis. Substantial progress has been made in recent years on designing anticancer therapies that utilize the effects of macropinocytosis. Both the induction and inhibition of macropinocytosis are useful strategies for combating cancer cells. This article systematically reviews the general mechanisms of macropinocytosis, its specific functions in tumor cells, its occurrence in nontumor cells in the TME, and its application in tumor therapies. The aim is to elucidate the role and therapeutic potential of macropinocytosis in cancer treatment.

Clinical outcome comparison of laparoscopic radical antegrade modular pancreatosplenectomy vs. laparoscopic distal pancreatosplenectomy for left-sided pancreatic ductal adenocarcinoma surgical resection.

Background: Laparoscopic radical antegrade modular pancreatosplenectomy (LRAMPS) is a validated surgical treatment for patients with left-sided pancreatic ductal adenocarcinoma (PDAC). In addition, laparoscopic distal pancreatectomy (LDPS) has purported benefits. However, there is a limited analysis comparing the results between LRAMPS and LDPS. Thus, this study aims to compare the short-term and long-term outcomes of patients who underwent LRAMPS and LDPS for PDAC treatment. Methods: Patients with left-sided PDAC that underwent LRAMPS or LDPS from 2015 to 2021 were retrospectively identified. Demographic and clinic pathologic data were collected. Disease-free survival (DFS) and overall survival (OS) probabilities were obtained. Results: The number of lymph nodes retrieved was significantly greater in the LRAMPS group than in the LDPS group. Several clinicopathological factors, including CA19-9 levels greater than 37 U/ml, positive lymph nodes, moderate to poor tumor differentiation, and peripancreas fat invasion, were associated with DFS. Moderate with poor tumor differentiation was associated with poor DFS (HR 0.568; 95% CI 0.373-0.921; P = 0.021). Levels of CA19-9 greater than 37 U/ml, CEA levels greater than 5 µg/ml, larger tumor size, positive lymph nodes, moderate with poor tumor differentiation, peripancreas fat invasion, and adjuvant chemotherapy were all associated with OS. LRAMPS nearly improved OS but did not reach statistical significance. Serum carcinoembryonic antigen (CEA) levels greater than 5 ug/ml (HR 1.693; 95% CI 1.200-1.132; P = 0.001), and positive lymph nodes (HR 2.410; 95% CI 1.453-3.995; P = 0.001) were independently associated with poor OS. Treatment with adjuvant chemotherapy was associated with improved OS (HR 0.491; 95% CI 0.248-0.708; P = 0.001). Conclusions: The LRAMPS procedure achieved comparable results to standard LDPS in terms of postoperative outcomes. Treatment with chemotherapy is important for the prognosis of patients with left-sided pancreatic cancer.

Spontaneous healing after conservative treatment of isolated grade IV pancreatic duct disruption caused by trauma: A case report.

BACKGROUND: Trauma is a common cause of pancreatic duct disruption. Surgical treatment is recommended in current clinical guidelines for adult pancreatic injury because non-surgical treatments have higher risks of serious complications or even death compared with surgical treatment. CASE SUMMARY: A 22-year-old woman was admitted to Tiantai People's Hospital of Zhejiang Province after 1-h duration of abdominal pain and distension following trauma. The diagnosis was "traumatic pancreatic rupture". The patient's symptoms were not severe, her vital signs were stable, and signs of peritonitis were not obvious. Therefore, conservative treatment could be considered, with the possibility of emergency surgery if necessary. After 2 mo of conservative treatment with duct drainage, the pancreatic duct healed spontaneously with no significant complications. CONCLUSION: We report a case of pancreatic duct disruption in the head and neck caused by trauma that was treated conservatively and healed spontaneously, providing a new choice for clinical practice. For isolated pancreatic injury with rupture of the pancreatic duct in the head and neck, conservative treatment under close observation is feasible.

The crosstalk effect between ferrous and other ions metabolism in ferroptosis for therapy of cancer.

Ferroptosis is an iron-dependent cell death process characterized by excessive accumulation of reactive oxygen species and lipid peroxidation. The elucidation of ferroptosis pathways may lead to novel cancer therapies. Current evidence suggests that the mechanism of ferroptosis can be summarized as oxidative stress and antioxidant defense mechanisms. During this process, ferrous ions play a crucial role in cellular oxidation, plasma membrane damage, reactive oxygen species removal imbalance and lipid peroxidation. Although, disregulation of intracellular cations (Fe2+, Ca2+, Zn2+, etc.) and anions (Cl-, etc.) have been widely reported to be involved in ferroptosis, their specific regulatory mechanisms have not been established. To further understand the crosstalk effect between ferrous and other ions in ferroptosis, we reviewed the ferroptosis process from the perspective of ions metabolism. In addition, the role of ferrous and other ions in tumor therapy is briefly summarized.

Identification of Genes Related to 5-Fluorouracil Based Chemotherapy for Colorectal Cancer.

Background: Colorectal cancer (CRC) is one of the most common malignancies and its incidence and mortality are increasing yearly. 5-Fluorouracil (5-FU) has long been used as a standard first-line treatment for CRC patients. Although 5-FU-based chemotherapy is effective for advanced CRC, the consequent resistance remains a key problem and causes the poor prognosis of CRC patients. Thus, there is an urgent need to identify new biomarkers to predict the response to 5-FU-based chemotherapy. Methods: CRC samples were retrieved from Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA). The immune-related genes were retrieved from the ImmPort database. Single-cell sequencing results from colorectal cancer were obtained by the ArrayExpress database. 5-FU resistance-related genes were filtered and validated by R packages. ESTIMATE algorithms were used to assess the tumor microenvironment (TME). KEGG and GO analysis were performed to explore the biological signaling pathway for resistant-response patients and sensitive-response patients in the tumor microenvironment. pRRophetic algorithms were used to predict 5-FU sensitivity. GSEA and GSVA analysis was performed to excavate the biological signaling pathway of the RBP7 gene. Results: Nine immune-related genes were identified to be associated with 5-FU resistance and poor disease-free survival (DFS) of CRC patients and the signature of these genes was developed in a DFS-prognostic model. Four immune-related genes were determined to be associated with 5-FU resistance and overall survival (OS) of CRC patients. The signature of these genes was developed an OS-prognostic model. ESTIMATE scores showed a significant difference between 5-FU resistant and 5-FU sensitive CRC patients. Resistant-response patients and sensitive-response patients to 5-FU based chemotherapy showed different GO and KEGG enrichment on the tumor microenvironment. RBP7, as a tumor immune microenvironment (TIME) related gene, was found to have the potential of predicting chemotherapy resistance and poor prognosis of CRC patients. GSEA analysis showed multiple signaling differences between the high and low expression of RBP7 in CRC patients. Hypoxia and TNFα signaling via NFκB gene sets were significantly different between chemotherapy resistant (RBP7High) and chemotherapy sensitive (RBP7Low) patients. Single-cell RNA-seq suggested RBP7 was centrally distributed in endothelial stalk cells, endothelial tip cells, and myeloid cells. Conclusions: Immune-related genes will hopefully be potential prognostic biomarkers to predict chemotherapy resistance for CRC. RBP7 may function as a tumor microenvironment regulator to induce 5-FU resistance, thereby affecting the prognosis of CRC patients.