The Long-Term Outcome of Laparoscopic Resection for Perihilar Cholangiocarcinoma Compared with the Open Approach: A Real-World Multicentric Analysis.

OBJECTIVE: The aim of this study was to compare the short- and long-term outcomes of laparoscopic surgery (LS) and open surgery (OP) for perihilar cholangiocarcinoma (PHC) using a large real-world dataset in China. METHODS: Data of patients with PHC who underwent LS and OP from January 2013 to October 2018, across 10 centers in China, were extracted from medical records. A comparative analysis was performed before and after propensity score matching (PSM) in the LS and OP groups and within the study subgroups. The Cox proportional hazards mixed-effects model was applied to estimate the risk factors for mortality, with center and year of operation as random effects. RESULTS: A total of 467 patients with PHC were included, of whom 161 underwent LS and 306 underwent OP. Postoperative morbidity, such as hemorrhage, biliary fistula, abdominal abscess, and hepatic insufficiency, was similar between the LS and OP groups. The median overall survival (OS) was longer in the LS group than in the OP group (NA vs. 22 months; hazard ratio [HR] 1.19, 95% confidence interval [CI] 1.02-1.39, p = 0.024). Among the matched datasets, OS was comparable between the LS and OP groups (NA vs. 35 months; HR 0.99, 95% CI 0.77-1.26, p = 0.915). The mixed-effect model identified that the surgical method was not associated with long-term outcomes and that LS and OP provided similar oncological outcomes. CONCLUSIONS: Considering the comparable long-term prognosis and short-term outcomes of LS and OP, LS could be a technically feasible surgical method for PHC patients with all Bismuth-Corlett types of PHC.

Intracapsular approach used in laparoscopic duodenum-preserving total pancreatic head resection for pancreatic head benign or low-grade malignant tumors.

PURPOSE: Laparoscopic duodenum-preserving total pancreatic head resection (LDPPHRt) is used for treating benign or low-grade malignant tumors of the pancreatic head. However, preservation of the duodenum and biliary tract integrity remains challenging. We present a new approach for LDPPHRt and evaluate its feasibility and safety. METHODS: From April 2020 to December 2020, 30 patients successfully underwent LDPPHRt using the intracapsular approach in our center. Their medical records were reviewed for relevant clinical characteristics, pathologic findings, postoperative complications, and survival. RESULTS: The median diameter of the lesions was 3.6 cm (range, 2.0-5.5 cm). The median operative time was 234.7 min (range, 195-310 min). The median blood loss was 66.7 ml (range, 20-250 ml). The morbidity rate was 26.7%, including POPF, hemorrhage, lymphatic leakage, wound infection, pulmonary infection, and delayed gastric emptying. Five patients developed pancreatic fistula type A, and two patients had type B, classified according to the International Study Group on Pancreatic Fistula. No biliary tract injury or duodenal leakage was observed. The median postoperative hospital stay was 11.5 days (range, 6-25), and the operative mortality rate was 0%. CONCLUSION: The intracapsular approach is a feasible and safe surgical procedure in LDPPHRt for patients with benign or low-grade malignant tumors, especially those without severe pancreatic head fibrosis or peripancreatic adhesions.

Prognostic validity of the American joint committee on cancer eighth edition staging system for well-differentiated pancreatic neuroendocrine tumors.

BACKGROUND: The American Joint Committee on Cancer (AJCC) made improvements for staging pancreatic neuroendocrine tumors (pNETs) in its 8th Edition; however, multicenter studies were not included. METHODS: We collected multicenter datasets (n = 1,086, between 2004 and 2018) to validate the value of AJCC 8 and other coexisting staging systems through univariate and multivariate analysis for well-differentiated (G1/G2) pNETs. RESULTS: Compared to other coexisting staging systems, AJCC 7 only included 12 (1.1%) patients with stage III tumors. Patients with European Neuroendocrine Tumor Society (ENETS) stage IIB disease had a higher risk of death than patients with stage IIIA (hazard ratio [HR]: 4.376 vs. 4.322). For the modified ENETS staging system, patients with stage IIB disease had a higher risk of death than patients with stage III (HR: 6.078 vs. 5.341). According to AJCC 8, the proportions of patients with stage I, II, III, and IV were 25.7%, 40.3%, 23.6%, and 10.4%, respectively. As the stage advanced, the median survival time decreased (NA, 144.7, 100.8, 72.0 months, respectively), and the risk of death increased (HR: II = 3.145, III = 5.925, and IV = 8.762). CONCLUSION: These findings suggest that AJCC 8 had a more reasonable proportional distribution and the risk of death was better correlated with disease stage.

CircSEC24A upregulates TGFBR2 expression to accelerate pancreatic cancer proliferation and migration via sponging to miR-606.

BACKGROUND: Circular RNA (circRNA), producing by special selective splicing, was widely expressed in the cytoplasm of eukaryotic cells as a newly non-coding RNAs. It played different roles in a variety of diseases including cancer and performed different functions. Nonetheless, reports on the specific function of circRNA in pancreatic cancer (PC) were still rarely so far. In particular, the role of circSEC24A in PC remains unclear. METHODS: Real-time fluorescent quantitative PCR was used to evaluate the expression level of circSEC24A in pancreatic cancer tissues and cell lines. Furthermore, we used some functional experiments, such as EDU and Transwell assays, to explore the effects of circSEC24A on the proliferation and invasiveness of pancreatic cancer. Finally, the corresponding relationship among circSEC24A, miR-606 and TGFBR2 was explored by dual luciferase reporter and other mechanism studies. RESULTS: The expression of circSEC24A in both pancreatic cancer tissues and cell lines was evidently up-regulated. Furthermore, knockdown of circSEC24A significantly inhibited the proliferative, migration and invasive capacity of pancreatic cancer cells, whereas miR-606 inhibitor obviously counteracted these effects. Further study confirmed that circSEC24A alleviated suppression on target TGFBR2 expression by directly sponging miR-606 and then influenced the tumorigenesis of pancreatic cancer. CONCLUSIONS: These findings indicated that the progression of pancreatic cancer can be driven by circSEC24A influencing miR-606/TGFBR2 axis. Therefore, circSEC24A might be used as a critical biomarker influencing the early diagnosis and prognosis of pancreatic cancer.

Upregulation of METTL14 mediates the elevation of PERP mRNA N6 adenosine methylation promoting the growth and metastasis of pancreatic cancer.

BACKGROUND: Pancreatic cancer is one of the most lethal human cancers. N6-methyladenosine (m6A), a common eukaryotic mRNA modification, plays critical roles in both physiological and pathological processes. However, its role in pancreatic cancer remains elusive. METHODS: LC/MS was used to profile m6A levels in pancreatic cancer and normal tissues. Bioinformatics analysis, real-time PCR, immunohistochemistry, and western blotting were used to identify the role of m6A regulators in pancreatic cancer. The biological effects of methyltransferase-like 14 (METTL14), an mRNA methylase, were investigated using in vitro and in vivo models. MeRIP-Seq and RNA-Seq were used to assess the downstream targets of METTL14. RESULTS: We found that the m6A levels were elevated in approximately 70% of the pancreatic cancer samples. Furthermore, we demonstrated that METTL14 is the major enzyme that modulates m6A methylation (frequency and site of methylation). METTL14 overexpression markedly promoted pancreatic cancer cell proliferation and migration both in vitro and in vivo, via direct targeting of the downstream PERP mRNA (p53 effector related to PMP-22) in an m6A-dependent manner. Methylation of the target adenosine lead to increased PERP mRNA turnover, thus decreasing PERP (mRNA and protein) levels in pancreatic cancer cells. CONCLUSIONS: Our data suggest that the upregulation of METTL14 leads to the decrease of PERP levels via m6A modification, promoting the growth and metastasis of pancreatic cancer; therefore METTL14 is a potential therapeutic target for its treatment.

Imbedding pancreaticojejunostomy used in pure laparoscopic pancreaticoduodenectomy for nondilated pancreatic duct.

BACKGROUND: LPD has been cautiously regarded as feasible and safe for resection and reconstruction. However, anastomosis of the remnant pancreas is still thought to be a critical obstacle to the dissemination of LPD in general practice. This study presents a new technique of pancreaticojejunostomy for nondilated pancreatic duct and evaluates its safety and reliability. METHODS: From July 2014 to June 2015, a total of 52 patients underwent LPD with the new technique. A modified technique of duct-to-mucosa PJ was performed with transpancreatic interlocking mattress sutures, named the imbedding duct-to-mucosa PJ. Then the morbidity and mortality was calculated. RESULTS: This technique was applied in 52 patients after LPD all with nondilated pancreatic duct (1-3 mm). The mean operation time was 4.6 h (range, 3.5-8.3 h) and the median time for the anastomosis was 37 min (range, 24-53 min). Operative mortality was zero, and morbidity was 21.2 % (n = 11), including hemorrhage (n = 3, 5.8 %), biliary fistula (n = 1, 1.9 %), pulmonary infection (n = 1, 1.9 %), delayed gastric emptying (n = 2, 3.8 %), abdominal abscess caused by biliary fistula or PF formation (n = 2, 3.8 %), and POPF (n = 2, 3.8 %). Two patients developed a pancreatic fistula (one type A, one type B) classified according to the International Study Group on Pancreatic Fistula. CONCLUSIONS: The described technique is a simple and safe reconstruction procedure after LPD, especially for patients with nondilated pancreatic duct.

MiR-200b-3p elevates 5-FU sensitivity in cholangiocarcinoma cells via autophagy inhibition by targeting KLF4.

Cholangiocarcinoma is one of the most lethal human cancers, and chemotherapy failure is a major cause of recurrence and poor prognosis. We previously demonstrated that miR-200 family members are downregulated in clinical samples of cholangiocarcinoma and inhibit cholangiocarcinoma tumorigenesis and metastasis. However, the role of differentially expressed miR-200b-3p in 5-fluorouracil chemosensitivity remains unclear. Here, we examined how miR-200b-3p modulates 5-fluorouracil chemosensitivity in cholangiocarcinoma. We observed that miR-200b-3p was associated with 5-fluorouracil sensitivity in cholangiocarcinoma and increased 5-fluorouracil-induced mitochondrial apoptosis in cholangiocarcinoma cells. Mechanistically, miR-200b-3p suppressed autophagy in cholangiocarcinoma cells to mediate 5-fluorouracil sensitivity. Further, we identified KLF4 as an essential target of miR-200b-3p in cholangiocarcinoma. Notably, the miR-200b-3p/KLF4/autophagy pathway augmented the chemosensitivity of cholangiocarcinoma cells to 5-fluorouracil. Our findings underscore the key role of miR-200b-3p in chemosensitivity to 5-fluorouracil and highlight the miR-200b-3p/KLF4/autophagy axis as a potential therapeutic target for cholangiocarcinoma.

Signature of Altered Retinal Microstructures and Electrophysiology in Schizophrenia Spectrum Disorders Is Associated With Disease Severity and Polygenic Risk.

BACKGROUND: Optical coherence tomography and electroretinography studies have revealed structural and functional retinal alterations in individuals with schizophrenia spectrum disorders (SSDs). However, it remains unclear which specific retinal layers are affected; how the retina, brain, and clinical symptomatology are connected; and how alterations of the visual system are related to genetic disease risk. METHODS: Optical coherence tomography, electroretinography, and brain magnetic resonance imaging were applied to comprehensively investigate the visual system in a cohort of 103 patients with SSDs and 130 healthy control individuals. The sparse partial least squares algorithm was used to identify multivariate associations between clinical disease phenotype and biological alterations of the visual system. The association of the revealed patterns with individual polygenic disease risk for schizophrenia was explored in a post hoc analysis. In addition, covariate-adjusted case-control comparisons were performed for each individual optical coherence tomography and electroretinography parameter. RESULTS: The sparse partial least squares analysis yielded a phenotype-eye-brain signature of SSDs in which greater disease severity, longer duration of illness, and impaired cognition were associated with electrophysiological alterations and microstructural thinning of most retinal layers. Higher individual loading onto this disease-relevant signature of the visual system was significantly associated with elevated polygenic risk for schizophrenia. In case-control comparisons, patients with SSDs had lower macular thickness, thinner retinal nerve fiber and inner plexiform layers, less negative a-wave amplitude, and lower b-wave amplitude. CONCLUSIONS: This study demonstrates multimodal microstructural and electrophysiological retinal alterations in individuals with SSDs that are associated with disease severity and individual polygenic burden.

Suppression of amino acid transporter LAT3 expression on proliferation of K562 cells.

The activity of the mTOR pathway is frequently increased in acute myeloid leukemia, and is tightly related with cellular proliferation. Leucine is tightly linked to the mTOR pathway and can activate it, thereby stimulating cellular proliferation. LAT3 is a major transporter for leucine, and suppression of its expression can reduce cell proliferation. Here, we show that suppression of LAT3 expression can reduce proliferation of the acute leukemia cell line, K562. We investigated the mRNA and protein expression of LAT3 in several leukemia cell lines and normal peripheral blood mononuclear cells (PBMNCs) using RT-PCR and Western blotting. We also evaluated cell viability using a methyl thiazolyl tetrazolium (MTT) assay after blocking LAT3 expression with either shRNA targeted to LAT3 or a small molecular inhibitor BCH (2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid). LAT3 mRNA and protein expression was detected in leukemia cell lines, but not in normal PBMNCs. Using K562 cells, it was found that cellular proliferation and mTOR pathway activity were significantly reduced when LAT3 was blocked with either shRNA or BCH. Our results suggest that leukemia cell proliferation can be significantly suppressed by blocking LAT3. This finding may lead to a new strategy to develop clinical therapy for the treatment of acute myeloid leukemia.

N6-methyladenosine reader YTHDF family in biological processes: Structures, roles, and mechanisms.

As the most abundant and conserved internal modification in eukaryote RNAs, N6-methyladenosine (m6A) is involved in a wide range of physiological and pathological processes. The YT521-B homology (YTH) domain-containing family proteins (YTHDFs), including YTHDF1, YTHDF2, and YTHDF3, are a class of cytoplasmic m6A-binding proteins defined by the vertebrate YTH domain, and exert extensive functions in regulating RNA destiny. Distinct expression patterns of the YTHDF family in specific cell types or developmental stages result in prominent differences in multiple biological processes, such as embryonic development, stem cell fate, fat metabolism, neuromodulation, cardiovascular effect, infection, immunity, and tumorigenesis. The YTHDF family mediates tumor proliferation, metastasis, metabolism, drug resistance, and immunity, and possesses the potential of predictive and therapeutic biomarkers. Here, we mainly summary the structures, roles, and mechanisms of the YTHDF family in physiological and pathological processes, especially in multiple cancers, as well as their current limitations and future considerations. This will provide novel angles for deciphering m6A regulation in a biological system.

An E3 ubiquitin-proteasome gene signature for predicting prognosis in patients with pancreatic cancer.

Pancreatic cancer is the seventh leading cause of cancer death worldwide, which is demonstrated with remarkable resistance to radiotherapy and chemotherapy. The identification of prognosis signature and novel prognostic markers will facilitate patient stratification and an individualized precision therapy strategy. In this study, TCGA-PAAD was used to screen prognostic E3 ubiquitin ligases and establish prognostic signatures, and GEO database was used to verify the accuracy of prognostic signatures. Functional analysis, in vitro experiments and clinical cohort studies were used to analyze the function and prognostic efficacy of the target gene. An E3 ligase-based signature of 9 genes and the nomogram were developed, and the signature was proved to accurately predict the prognosis of patients with pancreatic cancer. WDR37 might be the most prognostic E3 ubiquitin ligase in pancreatic cancer, and the clinical cohort analyses suggested a tumor-suppressive role. The results of functional analysis and in vitro experiments indicated that WDR37 may promote the degradation of TCP1 complex to inhibit tumor and improve immune cell infiltration. The E3 ligase-based signature accurately predicted the prognosis of patients with pancreatic cancer, so it can be used as a decision-making tool to guide the treatment of patients with pancreatic cancer. At the same time, WDR37, the main gene in E3PMP signature, can be used as the most prognostic E3 ubiquitin ligase in the treatment of pancreatic cancer.

LILRB2/PirB mediates macrophage recruitment in fibrogenesis of nonalcoholic steatohepatitis.

Inhibition of immunocyte infiltration and activation has been suggested to effectively ameliorate nonalcoholic steatohepatitis (NASH). Paired immunoglobulin-like receptor B (PirB) and its human ortholog receptor, leukocyte immunoglobulin-like receptor B (LILRB2), are immune-inhibitory receptors. However, their role in NASH pathogenesis is still unclear. Here, we demonstrate that PirB/LILRB2 regulates the migration of macrophages during NASH by binding with its ligand angiopoietin-like protein 8 (ANGPTL8). Hepatocyte-specific ANGPTL8 knockout reduces MDM infiltration and resolves lipid accumulation and fibrosis progression in the livers of NASH mice. In addition, PirB-/- bone marrow (BM) chimeras abrogate ANGPTL8-induced MDM migration to the liver. And yet, PirB ectodomain protein could ameliorate NASH by sequestering ANGPTL8. Furthermore, LILRB2-ANGPTL8 binding-promoted MDM migration and inflammatory activation are also observed in human peripheral blood monocytes. Taken together, our findings reveal the role of PirB/LILRB2 in NASH pathogenesis and identify PirB/LILRB2-ANGPTL8 signaling as a potential target for the management or treatment of NASH.

Chromatin Immunoprecipitation Assay in Primary Mouse Hepatocytes and Mouse Liver.

Non-alcoholic steatohepatitis (NASH) is an advanced form of non-alcoholic fatty liver disease characterized by hepatosteatosis, liver cell injury, and inflammation. The pathogenesis of NASH involves dysregulated transcription of genes involved in critical processes in the liver, including metabolic homeostasis and inflammation. Chromatin immunoprecipitation (ChIP) utilizes antibody-mediated immunoprecipitation followed by the detection of associated DNA fragments via real-time PCR or high-throughput sequencing to quantitatively profile the interactions of proteins of interest with functional chromatin elements. Here, we present a detailed protocol to study the interactions of DNA and chromatin-associated proteins (e.g., transcription factors, co-activators, co-repressors, and chromatin modifiers) and modified histones (e.g., acetylated and methylated) in isolated primary mouse hepatocytes and mouse liver. The application of these methods can enable the identification of molecular mechanisms that underpin dysregulated hepatic processes in NASH.

Generation of Adenovirus for In Vitro and In Vivo Studies of Hepatocytes.

Although non-alcoholic steatohepatitis (NASH) can progress to liver cancer and liver failure, no FDA-approved drugs exist to treat NASH. Deciphering the molecular mechanisms underlying the pathogenesis of NASH will facilitate the development of effective treatments for NASH, and requires loss- or gain-of-function experimental approaches. While genetically modified animals provide important information about the function of a gene, adenovirus is a fast, effective, and versatile tool that allows transient knockdown, knockout, or overexpression of one or more genes of interest (GOIs) in primary hepatocytes in vitro and in mouse liver in vivo. In addition, adenovirus is a promising treatment method in preclinical animal models, including rodents and non-human primates, and is used in many clinical trials. Here, we describe a step-by-step protocol to generate adenovirus for basic medical research. We discuss critical steps during virus propagation and purification and provide notes about how to avoid common pitfalls.

Downregulation of hepatic ceruloplasmin ameliorates NAFLD via SCO1-AMPK-LKB1 complex.

Copper deficiency has emerged to be associated with various lipid metabolism diseases, including non-alcoholic fatty liver disease (NAFLD). However, the mechanisms that dictate the association between copper deficiency and metabolic diseases remain obscure. Here, we reveal that copper restoration caused by hepatic ceruloplasmin (Cp) ablation enhances lipid catabolism by promoting the assembly of copper-load SCO1-LKB1-AMPK complex. Overnutrition-mediated Cp elevation results in hepatic copper loss, whereas Cp ablation restores copper content to the normal level without eliciting detectable hepatotoxicity and ameliorates NAFLD in mice. Mechanistically, SCO1 constitutively interacts with LKB1 even in the absence of copper, and copper-loaded SCO1 directly tethers LKB1 to AMPK, thereby activating AMPK and consequently promoting mitochondrial biogenesis and fatty acid oxidation. Therefore, this study reveals a mechanism by which copper, as a signaling molecule, improves hepatic lipid catabolism, and it indicates that targeting copper-SCO1-AMPK signaling pathway ameliorates NAFLD development by modulating AMPK activity.

MiR-146b-3p regulates proliferation of pancreatic cancer cells with stem cell-like properties by targeting MAP3K10.

Purpose: Cancer stem cells (CSCs) initiate and maintain tumorigenesis due to their unique pluripotency. However, pancreatic stem cell gene signatures are not completely revealed yet. Here, we isolated pancreatic cancer stem cells (P-CSCs) and exploited their distinct genome-wide mRNA and miRNA expression profiles using microarrays. Methods: CD24+ CD44+ ESA+ cells were isolated from two pancreatic xenograft cells by the flow cytometry and identified the stem cell-like properties by the tumor formation, self-renew and chemoresistance. Microarrays and qRT-PCR were used to exploit their distinct Genome-wide mRNA and miRNA expression profiles. The function and candidate target genes of key microRNA were detected after Ectopic restoration in the pancreatic cancer cell lines MIA Paca-2 (CSChigh) and BxPC-3 (CSClow). Results: In this study, we isolated P-CSCs from two xenografts cells. Genome-wide profiling experiments showed 479 genes and 15 microRNAs specifically expressed in the P-CSCs, including genes involved in TGF-ß and p53 signaling pathways and particularly miR-146b-3p as the most significantly downregulated miRNA. We confirmed miR-146b-3p as a downregulated signature in pancreatic cancer tissues and cell line MIA Paca-2 (CSChigh) cells. Ectopic restoration of miR-146b-3p expression with pre-miR reduced cell proliferation, induced apoptosis, increased G1 phase and reduced S phase in cell cycle in MIA Paca-2 (CSChigh), but not in BxPC-3 (CSClow). Re-expression of miR-146b-3p with lentivirus significantly inhibited tumorigenicity in vivo in MIA Paca-2, but slightly in BxPC-3. Furthermore, we demonstrated that miR-146b-3p directly targeted MAP3K10 and might activate Hedgehog pathway as well through DYRK2 and GLI2. Conclusions: These results suggest that P-CSCs have distinct gene expression profiles. MiR-146b-3p inhibits proliferation and induced apoptosis in P-CSCs high cells lines by targeting MAP3K10. Targeting P-CSCs specific genes may provide novel strategies for therapeutic purposes.

TAZ inhibits glucocorticoid receptor and coordinates hepatic glucose homeostasis in normal physiological states.

The elucidation of the mechanisms whereby the liver maintains glucose homeostasis is crucial for the understanding of physiological and pathological states. Here, we show a novel role of hepatic transcriptional co-activator with PDZ-binding motif (TAZ) in the inhibition of glucocorticoid receptor (GR). TAZ is abundantly expressed in pericentral hepatocytes and its expression is markedly reduced by fasting. TAZ interacts via its WW domain with the ligand-binding domain of GR to limit the binding of GR to the GR response element in gluconeogenic gene promoters. Therefore, liver-specific TAZ knockout mice show increases in glucose production and blood glucose concentration. Conversely, the overexpression of TAZ in mouse liver reduces the binding of GR to gluconeogenic gene promoters and glucose production. Thus, our findings demonstrate that hepatic TAZ inhibits GR transactivation of gluconeogenic genes and coordinates gluconeogenesis in response to physiological fasting and feeding.

New staging classification for pancreatic neuroendocrine neoplasms combining TNM stage and WHO grade classification [].

AJCC TNM stage and WHO grade (G) are two widely used staging systems to guide clinical management for pancreatic neuroendocrine neoplasms (panNENs), based on clinical staging and pathological grading information, respectively. We proposed to integrate TNM stage and G grade into one staging system (TNMG) and to evaluate its clinical application as a prognostic indicator for panNENs. Accordingly, 5254 patients diagnosed with panNENs were used to evaluate and to validate the applicability of TNMG to panNENs. The predictive accuracy of TNMG system was compared with that of each separate staging/grading system. We found that TNM stage and G grade were independent risk factors for survival in both the Surveillance, Epidemiology, and End Result (SEER) and multicenter series. The interaction effect between TNM stage and G grade was significant. Twelve subgroups combining the TNM stage and G grade were proposed in the TNMG stage, which were classified into five stages TNMG. According to the TNMG staging classification in the SEER series, the estimated median survival for stages I, II, III, IV, and V were 203, 174, 112, 61, and 8 months, respectively. The predictive accuracy of TNMG stage was higher than that of TNM stage and G grade used independently. The TNMG stage classification was more accurate in predicting panNEN patient's prognosis than either the TNM stage or G grade.

Large amplitude vibrations of imperfect spider web structures.

Due to the high-efficiency energy absorption and high-tension strength material properties of spider silk, many researchers have studied the mechanical properties and microstructure of the spider web. The concept of spider web structure has been recognized to be adopted for structural engineering aspect. The structure of spider web and its material properties have been studied for decades. However, the fundamental free vibration mode shapes and their corresponding frequencies have never been fully investigated. This study investigates the nonlinear characteristics in the large-amplitude free vibration of imperfect spider web structures using finite element analysis. The spider web applies the concept of elastic cables taking only axial deformation into account. The finite element models of a spider web considering geometric nonlinearities are employed. It should be noted that spider web could experience large deformation when the spider uses its silk to catch prey. This research aims at analyzing the linear and geometric nonlinear behaviour of imperfect spider web structure. Four different types of imperfect spider web: spiral imperfect spider web, radial imperfect spider web, central imperfect spider web, and circular rings imperfect spider web, are considered. It is found that pretension in spider silk plays a significant role in nonlinear vibration characteristics of the spider web. Moreover, the radial thread damaged tends to have a greater effect on structural free vibration of spider web in comparison with other imperfections. The outcome will help a structural engineer to adapt the concept of spider web, its properties, and damage patterns for any larger structures.