The S-Nitrosylation of Septin2 (SNO-Septin2) axis: A novel potential therapeutic target for treating aneurysms and dissection.

Aortic aneurysm and aortic dissection (AAD) are severe life-threatening cardiovascular disorders for which no approved pharmaceutical therapies are currently available. Protein S-nitrosylation (SNO) is a typical redox-dependent posttranslational modification whose role in AAD has yet to be described. Recently, Zhang et al. revealed for the first time that SNO modification of macrophage cytoskeletal protein septin2 promotes vascular inflammation and extracellular matrix degradation in aortic aneurysm. Mechanically, the TIAM1-RAC1(T lymphoma invasion and metastasis-inducing protein 1-Ras-related C3 botulinum toxin substrate 1) axis participates in the progression of AAD induced with S-nitrosylated septin2. More importantly, developing R-ketorolac and NSC23766 compounds that specifically target the TIAM1-RAC1 pathway may be new a potential strategy for alleviating AAD.

Pilot Study by Liquid Biopsy in Gastrointestinal Stromal Tumors: Analysis of PDGFRA D842V Mutation and Hypermethylation of SEPT9 Presence by Digital Droplet PCR.

Tissue biopsy remains the standard for diagnosing gastrointestinal stromal tumors (GISTs), although liquid biopsy is emerging as a promising alternative in oncology. In this pilot study, we advocate for droplet digital PCR (ddPCR) to diagnose GIST in tissue samples and explore its potential for early diagnosis via liquid biopsy, focusing on the PDGFRA D842V mutation and SEPT9 hypermethylated gene. We utilized ddPCR to analyze the predominant PDGFRA mutation (D842V) in surgical tissue samples from 15 GIST patients, correlating with pathologists' diagnoses. We expanded our analysis to plasma samples to compare DNA alterations between tumor tissue and plasma, also investigating SEPT9 gene hypermethylation. We successfully detected the PDGFRA D842V mutation in GIST tissues by ddPCR. Despite various protocols to enhance mutation detection in early-stage disease, it remained challenging, likely due to the low concentration of DNA in plasma samples. Additionally, the results of Area Under the Curve (AUC) for the hypermethylated SEPT9 gene, analyzing concentration, ratio, and abundance were 0.74 (95% Confidence Interval (CI): 0.52 to 0.97), 0.77 (95% CI: 0.56 to 0.98), and 0.79 (95% CI: 0.59 to 0.99), respectively. As a rare disease, the early detection of GIST through such biomarkers is particularly crucial, offering significant potential to improve patient outcomes.

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

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

The concerted action of SEPT9 and EPLIN modulates the adhesion and migration of human fibroblasts.

Septins are cytoskeletal proteins that participate in cell adhesion, migration, and polarity establishment. The septin subunit SEPT9 directly interacts with the single LIM domain of epithelial protein lost in neoplasm (EPLIN), an actin-bundling protein. Using a human SEPT9 KO fibroblast cell line, we show that cell adhesion and migration are regulated by the interplay between both proteins. The low motility of SEPT9-depleted cells could be partly rescued by increased levels of EPLIN. The normal organization of actin-related filopodia and stress fibers was directly dependent on the expression level of SEPT9 and EPLIN. Increased levels of SEPT9 and EPLIN enhanced the size of focal adhesions in cell protrusions, correlating with stabilization of actin bundles. Conversely, decreased levels had the opposite effect. Our work thus establishes the interaction between SEPT9 and EPLIN as an important link between the septin and the actin cytoskeleton, influencing cell adhesion, motility, and migration.

Circulating-tumour DNA methylation of HAND1 gene: a promising biomarker in early detection of colorectal cancer.

BACKGROUND: Colorectal cancer (CRC) is one of the significant global health concerns with an increase in cases. Regular screening tests are crucial for early detection as it is often asymptomatic in the initial stages. Liquid biopsies, a non-invasive approach that examines biomarkers in biofluids, offer a promising future in diagnosing and screening cancer. Circulating-tumour DNA (ctDNA) is the genetic material in biofluids released into the circulatory system by cells. ctDNA is a promising marker for monitoring patients since cancer cells display distinct DNA methylation patterns compared to normal cells. The potential of our research to contribute to early detection and improved patient outcomes is significant. AIMS: The primary objective of this research project was to explore the HAND1 methylation levels in plasma ctDNA as a potential biomarker for diagnosing CRC and evaluate the methylation level of the well-established gene SPET9 to compare it with the methylation level of HAND1. MATERIALS AND METHODS: Plasma samples were collected from 30 CRC patients and 15 healthy individuals, with CRC samples obtained pre-treatment. ctDNA was extracted and treated with bisulfite for methylation status assessment. Quantitative methylation-specific PCR (qMS-PCR) was performed for HAND1 and SEPT9, using ß-actin (ACTB gene) as a reference. The study aims to evaluate the potential of these genes as diagnostic biomarkers for CRC, contributing to early detection and improved patient outcomes. RESULTS: Our study yielded significant results: 90% of CRC patients (27 out of 30) had hypermethylation in the SEPT9 gene, and 83% (25 out of 30) exhibited hypermethylation in the HAND1 gene. The methylation levels of both genes were significantly higher in CRC patients than in healthy donors. These findings underscore the potential of SEPT9 and HAND1 methylation as promising biomarkers for diagnosing CRC, potentially leading to early detection and improved patient outcomes. CONCLUSION: These findings highlight the potential of SEPT9 and HAND1 methylation as promising biomarkers for diagnosing CRC. However, further research and validation studies are needed to confirm these findings and to explore their clinical utility in CRC diagnosis and management.

Septin-coated microtubules promote maturation of multivesicular bodies by inhibiting their motility.

The microtubule cytoskeleton consists of microtubule subsets with distinct compositions of microtubule-associated proteins, which instruct the position and traffic of subcellular organelles. In the endocytic pathway, these microtubule-associated cues are poorly understood. Here, we report that in MDCK cells, endosomes with multivesicular body (MVB) and late endosome (LE) markers localize preferentially to microtubules coated with septin GTPases. Compared with early endosomes, CD63-containing MVBs/LEs are largely immotile on septin-coated microtubules. In vitro reconstitution assays revealed that the motility of isolated GFP-CD63 endosomes is directly inhibited by microtubule-associated septins. Quantification of CD63-positive endosomes containing the early endosome antigen (EEA1), the Rab7 effector and dynein adaptor RILP or Rab27a, showed that intermediary EEA1- and RILP-positive GFP-CD63 preferentially associate with septin-coated microtubules. Septin knockdown enhanced GFP-CD63 motility and decreased the percentage of CD63-positive MVBs/LEs with lysobiphosphatidic acid without impacting the fraction of EEA1-positive CD63. These results suggest that MVB maturation involves immobilization on septin-coated microtubules, which may facilitate multivesiculation and/or organelle-organelle contacts.

BCAT1, IKZF1 and SEPT9: methylated DNA biomarkers for detection of pan-gastrointestinal adenocarcinomas.

INTRODUCTION: Methylated circulating tumour DNA (ctDNA) blood tests for BCAT1/IKZF1 (COLVERA) and SEPT9 (Epi proColon) are used to detect colorectal cancer (CRC). However, there are no ctDNA assays approved for other gastrointestinal adenocarcinomas. We aimed to characterize BCAT1, IKZF1 and SEPT9 methylation in different gastrointestinal adenocarcinoma and non-gastrointestinal tumours to determine if these validated CRC biomarkers might be useful for pan-gastrointestinal adenocarcinoma detection. METHODS: Tissue DNA methylation data from colorectal (COAD, READ), gastroesophageal (ESCA, STAD), pancreatic (PAAD) and cholangiocarcinoma (CHOL) adenocarcinoma cohorts within The Cancer Genome Atlas were used for differential methylation analyses. Clinicodemographic predictors of BCAT1, IKZF1 and SEPT9 methylation, and the selectivity of hypermethylated BCAT1, IKZF1 and SEPT9 for colorectal adenocarcinomas in comparison to other cancers were each explored with beta regression. RESULTS: Hypermethylated BCAT1, IKZF1 and SEPT9 were each differentially methylated in colorectal and gastroesophageal adenocarcinomas. IKZF1 was differentially methylated in pancreatic adenocarcinoma. Hypermethylated DNA biomarkers BCAT1, IKZF1 and SEPT9 were largely stable across different stages of disease and were highly selective for gastrointestinal adenocarcinomas relative to other cancer types. DISCUSSION: Existing CRC methylated ctDNA blood tests for BCAT1/IKZF1 and SEPT9 might be usefully repurposed for use in other gastrointestinal adenocarcinomas and warrant further prospective ctDNA studies.

Septin-dependent defense mechanisms against Pseudomonas aeruginosa are stalled in cystic fibrosis bronchial epithelial cells.

Airway epithelial cells form a physical barrier against inhaled pathogens and coordinate innate immune responses in the lungs. Bronchial cells in people with cystic fibrosis (pwCF) are colonized by Pseudomonas aeruginosa because of the accumulation of mucus in the lower airways and an altered immune response. This leads to chronic inflammation, lung tissue damage, and accelerated decline in lung function. Thus, identifying the molecular factors involved in the host response in the airways is crucial for developing new therapeutic strategies. The septin (SEPT) cytoskeleton is involved in tissue barrier integrity and anti-infective responses. SEPT7 is critical for maintaining SEPT complexes and for sensing pathogenic microbes. In the lungs, SEPT7 may be involved in the epithelial barrier resistance to infection; however, its role in cystic fibrosis (CF) P. aeruginosa infection is unknown. This study aimed to investigate the role of SEPT7 in controlling P. aeruginosa infection in bronchial epithelial cells, particularly in CF. The study findings showed that SEPT7 encages P. aeruginosa in bronchial epithelial cells and its inhibition downregulates the expression of other SEPTs. In addition, P. aeruginosa does not regulate SEPT7 expression. Finally, we found that inhibiting SEPT7 expression in bronchial epithelial cells (BEAS-2B 16HBE14o- and primary cells) resulted in higher levels of internalized P. aeruginosa and decreased IL-6 production during infection, suggesting a crucial role of SEPT7 in the host response against this bacterium. However, these effects were not observed in the CF cells (16HBE14o-/F508del and primary cells) which may explain the persistence of infection in pwCF. The study findings suggest the modification of SEPT7 expression as a potential approach for the anti-infective control of P. aeruginosa, particularly in CF.

Discovery of a septin-4 covalent binder with antimetastatic activity in a mouse model of melanoma.

Cancer spreading through metastatic processes is one of the major causes of tumour-related mortality. Metastasis is a complex phenomenon which involves multiple pathways ranging from cell metabolic alterations to changes in the biophysical phenotype of cells and tissues. In the search for new effective anti-metastatic agents, we modulated the chemical structure of the lead compound AA6, in order to find the structural determinants of activity, and to identify the cellular target responsible of the downstream anti-metastatic effects observed. New compounds synthesized were able to inhibit in vitro B16-F10 melanoma cell invasiveness, and one selected compound, CM365, showed in vivo anti-metastatic effects in a lung metastasis mouse model of melanoma. Septin-4 was identified as the most likely molecular target responsible for these effects. This study showed that CM365 is a promising molecule for metastasis prevention, remarkably effective alone or co-administered with drugs normally used in cancer therapy, such as paclitaxel.

S-Nitrosylation of Septin2 Exacerbates Aortic Aneurysm and Dissection by Coupling the TIAM1-RAC1 Axis in Macrophages.

BACKGROUND: S-Nitrosylation (SNO), a prototypic redox-based posttranslational modification, is involved in cardiovascular disease. Aortic aneurysm and dissection are high-risk cardiovascular diseases without an effective cure. The aim of this study was to determine the role of SNO of Septin2 in macrophages in aortic aneurysm and dissection. METHODS: Biotin-switch assay combined with liquid chromatography-tandem mass spectrometry was performed to identify the S-nitrosylated proteins in aortic tissue from both patients undergoing surgery for aortic dissection and Apoe-/- mice infused with angiotensin II. Angiotensin II-induced aortic aneurysm model and ß-aminopropionitrile-induced aortic aneurysm and dissection model were used to determine the role of SNO of Septin2 (SNO-Septin2) in aortic aneurysm and dissection development. RNA-sequencing analysis was performed to recapitulate possible changes in the transcriptome profile of SNO-Septin2 in macrophages in aortic aneurysm and dissection. Liquid chromatography-tandem mass spectrometry and coimmunoprecipitation were used to uncover the TIAM1-RAC1 (Ras-related C3 botulinum toxin substrate 1) axis as the downstream target of SNO-Septin2. Both R-Ketorolac and NSC23766 treatments were used to inhibit the TIAM1-RAC1 axis. RESULTS: Septin2 was identified S-nitrosylated at cysteine 111 (Cys111) in both aortic tissue from patients undergoing surgery for aortic dissection and Apoe-/- mice infused with Angiotensin II. SNO-Septin2 was demonstrated driving the development of aortic aneurysm and dissection. By RNA-sequencing, SNO-Septin2 in macrophages was demonstrated to exacerbate vascular inflammation and extracellular matrix degradation in aortic aneurysm. Next, TIAM1 (T lymphoma invasion and metastasis-inducing protein 1) was identified as a SNO-Septin2 target protein. Mechanistically, compared with unmodified Septin2, SNO-Septin2 reduced its interaction with TIAM1 and activated the TIAM1-RAC1 axis and consequent nuclear factor-κB signaling pathway, resulting in stronger inflammation and extracellular matrix degradation mediated by macrophages. Consistently, both R-Ketorolac and NSC23766 treatments protected against aortic aneurysm and dissection by inhibiting the TIAM1-RAC1 axis. CONCLUSIONS: SNO-Septin2 drives aortic aneurysm and dissection through coupling the TIAM1-RAC1 axis in macrophages and activating the nuclear factor-κB signaling pathway-dependent inflammation and extracellular matrix degradation. Pharmacological blockade of RAC1 by R-Ketorolac or NSC23766 may therefore represent a potential treatment against aortic aneurysm and dissection.

Septin9 DNA methylation is associated with breast cancer recurrence or metastasis.

OBJECTIVE: We aimed to explore the prognostic value of Septin9 DNA methylation in breast cancer. METHODS: Breast cancer patients with and without recurrence or metastasis and matched non-breast cancer patients were screened retrospectively from 2014 to 2016. Bisulfite conversion and fluorescence quantitative methylation-specific polymerase chain reaction were used to detect the Septin9 methylation status and distribution levels in patient breast tissues. RESULTS: Septin9 DNA methylation was more frequent in breast cancer tissues than in non-breast cancer tissues, but was not significantly correlated with any relevant breast cancer patient clinicopathological characteristic. Septin9 methylation rates were higher in patients with recurrence or metastasis. Septin9 methylation, tumor size, lymph node status, and progesterone receptor (PR) expression could influence prognosis. Septin9 methylation was significantly associated with worse disease-free survival in breast cancer patients, with receiver operating characteristic curve analysis indicating that it had good prognostic ability, with an area under the curve (AUC) value of 0.719. The AUC values increased when Septin9 methylation was combined with tumor size, lymph node status, and PR to predict prognosis. CONCLUSIONS: Septin9 DNA methylation was an independent predictors of breast cancer prognostic risk. This could possibly help improve comprehensive prognosis prediction methods when combined with other risk factors.

Association of Methylenetetrahydrofolate Reductase rs1801133 Gene Polymorphism with Cancer Risk and Septin 9 Methylation in Patients with Colorectal Cancer.

PURPOSE: Colorectal cancer (CRC) is one of the most common malignancies, with a high incidence and mortality worldwide. Methylated Septin 9 (mSEPT9) has been used clinically as an auxiliary tool for CRC screening. The aim of the present study was to investigate the association of the methylenetetrahydrofolate reductase (MTHFR) rs1801133 polymorphism with the risk of CRC and the methylation status of Septin 9 in CRC. METHODS: Information of 540 patients with a confirmed diagnosis of CRC and with a physical examination were utilized to assess the association of the MTHFR rs1801133 polymorphism with CRC and the methylation of SEPT9. MTHFR rs1801133 polymorphism was genotyped using polymerase chain reaction (PCR). The commercial Septin 9 Gene Methylation(mSEPT9) Detection Kit was used for plasma SEPT9 methylation analysis. RESULTS: Among 540 patients, 61.48% were men and the median age was 54.47 ± 13.14. 65.37% of all colorectal tumors developed in the rectum. 195 patients had negative mSEPT9 methylation, while 345 had positive results. 87 individuals with stage I, 90 with stage II, 287 with stage III, and 76 with stage IV colorectal cancer were included in the sample. The results demonstrated that the positivity rate and degree of methylation of mSEPT9 were remarkably higher in patients with more advanced TNM stages than in those with less advanced stages. The frequencies of the MTHFR rs1801133 CC genotype and allele C carriers in patients with CRC were significantly higher than those in healthy individuals (P = 0.006 and P = 0.001, respectively). The positivity rate of the mSEPT9 assay was significantly higher among the MTHFR rs1801133 TT genotype and allele T carriers than among the CC and allele C carriers respectively. The MTHFR rs1801133 TT genotype and allele T carriers were positively associated with the methylation of SEPT9 (OR = 3.320, 95% CI 1.485-7.424, P = 0.003 and OR = 1.783, 95% CI 1.056-3.010, P = 0.030, respectively). CONCLUSION: In conclusion, individuals harboring the MTHFR rs1801133 CC genotype had a higher risk of CRC and the MTHFR rs1801133 TT carriers were more susceptible to Septin 9 gene methylation.

External quality assessment for detection of colorectal cancer by Septin9 DNA methylation in clinical laboratories.

BACKGROUND AND AIMS: The incidence and mortality rate of colorectal cancer (CRC) are increasing worldwide. Septin9 methylated (mSEPT9) DNA in circulation can be used as a non-invasive detection method to assist in the early diagnosis of CRC; however, the detection methods and procedures are complicated. This study aimed to evaluate the ability of clinical laboratories to detect Septin9 methylation in plasma cell-free DNA (cfDNA). MATERIALS AND METHODS: We prepared a sample panel consisting of positive and negative Septin9 methylation cells and CRC cells. Three positive samples with different methylation levels, one negative sample and one duplicate sample, two samples containing interference, three different CRC cell samples, and a fictitious case report were included. The panel was distributed to 59 laboratories for mSEPT9 analysis, result comparison, and scoring. RESULTS: The sample panel, validated by National Medical Products Administration (NMPA)-approved tests and targeted bisulfite sequencing, met expectations and could be used for external quality assessment (EQA). Among the 59 laboratories, 55 (93.22%) correctly reported the mSEPT9 results for all samples, while four (6.79%) reported 15 false negatives and were considered improvable. All false negatives originated from four laboratories using laboratory-developed tests (LDTs), with three failing to detect weakly positive samples, samples containing interference, and samples from different CRC cells, and one reported erroneous results on all positive samples. CONCLUSION: Our results illustrated that the detection of mSEPT9 in cfDNA is satisfactory in China. EQA is indispensable because it can help improve the diagnostic capability and quality management of the laboratories, and provide suggestions for the problems existing in mSEPT9 detection.

Methylation of Septin9, SRSF1, and PAX8 in Early Screening of Colorectal Cancer in the Population Undergoing Physical Examinations.

BACKGROUND: The aim was to investigate the value of blood Septin9, SRSF1, and PAX8 gene methylation detection techniques in early screening of colorectal cancer (CRC). METHODS: A prospective cohort study enrolled 3,000 participants undergoing routine physical examination at Shizong County People's Hospital Health Management Center from December 2021 through November 2022, including 1,512 males and 1,488 females, ranging in age from 20 to 90 years, with a median age of 49 years. Fresh blood samples were collected and tested for Septin9, SRSF1, and PAX8 gene methylation. Positive or negative results were reported. Colonoscopy was recommended for positive results and telephone follow-up for negative results. A chi-squared test analyzed the positive rate of initial screening, colonoscopy compliance, and the detection rate of colorectal lesions. Finally, combined with the follow-up data, the screening effect of Septin9, SRSF1, and PAX8 methylation detection on CRC was evaluated. RESULTS: Among 3,000 cases, 215 cases were preliminarily positive, with a positive rate of 7.1% (215/3,000). The positive rate of Septin9 gene methylation was the highest (6%, 180/3000), followed by SRSF1 (4.1%, 124/3000) and PAX8 (3.6%, 108/3000). The sensitivity of combined detection of Septin9, SRSF1, and PAX8 methylation in the diagnosis of CRC was higher than that of the three alone, and the specificity, positive predictive value, and negative predictive value of combined detection were higher than that of the single detection of blood Septin9, SRSF1, and PAX8 DNA methylation. In addition, the positive rate of initial screening increased with age (χ2 = 32.135, p < 0.001). A total of 150 cases underwent further colonoscopy, and the colonoscopy compliance rate was 69.8% (150/215). Among 150 cases who completed colonoscopy, 5 cases of CRC (3.4%), 25 cases of advanced adenoma (16.0%), 78 cases of non-advanced adenoma (52.0%), and 24 cases of non-adenomatous polyps (22.7%) were detected. The positive predictive value of Septin9, SRSF1, and PAX8 methylation was 94% (141/150) for all colorectal lesions, and 70.0% (105/150) for colorectal cancer and precancerous lesions. CONCLUSIONS: Blood Septin9, SRSF1, and PAX8 gene methylation detection, combined with colonoscopy, can effectively detect colorectal cancer and precancerous lesions. This strategy may be an effective way to carry out large-scale colorectal cancer screening in the general risk population. Combined detection of the three genes can improve the detection rate of colorectal cancer, but Septin9 methylation is the most sensitive, which can be used for screening and efficacy evaluation of CRC.

Serum methylation of GALNT9, UPF3A, WARS, and LDB2 as noninvasive biomarkers for the early detection of colorectal cancer and advanced adenomas.

BACKGROUND: Early detection has proven to be the most effective strategy to reduce the incidence and mortality of colorectal cancer (CRC). Nevertheless, most current screening programs suffer from low participation rates. A blood test may improve both the adherence to screening and the selection to colonoscopy. In this study, we conducted a serum-based discovery and validation of cfDNA methylation biomarkers for CRC screening in a multicenter cohort of 433 serum samples including healthy controls, benign pathologies, advanced adenomas (AA), and CRC. RESULTS: First, we performed an epigenome-wide methylation analysis with the MethylationEPIC array using a sample pooling approach, followed by a robust prioritization of candidate biomarkers for the detection of advanced neoplasia (AN: AA and CRC). Then, candidate biomarkers were validated by pyrosequencing in independent individual cfDNA samples. We report GALNT9, UPF3A, WARS, and LDB2 as new noninvasive biomarkers for the early detection of AN. The combination of GALNT9/UPF3A by logistic regression discriminated AN with 78.8% sensitivity and 100% specificity, outperforming the commonly used fecal immunochemical test and the methylated SEPT9 blood test. CONCLUSIONS: Overall, this study highlights the utility of cfDNA methylation for CRC screening. Our results suggest that the combination methylated GALNT9/UPF3A has the potential to serve as a highly specific and sensitive blood-based test for screening and early detection of CRC.

The value of serum methylated septin 9 and carcinoembryonic antigen in efficacy evaluation and follow-up monitoring of colorectal cancer.

This study explored the value of the detection of serum methylated septin 9 (mSEPT9) and carcinoembryonic antigen (CEA) in the auxiliary diagnosis, curative effect evaluation, and follow-up monitoring of colorectal cancer (CRC). The diagnosis and treatment data of 208 CRC patients in the First Affiliated Hospital of Xinjiang Medical University (China) were collected from March 2019 to December 2019, and these patients were followed up. The correlation between serum CEA, mSEPT9 levels, and tumor location and size were analyzed. Serum mSEPT9 and CEA were detected before and after surgery and during follow-up after treatment to analyze the value of mSEPT9 in efficacy evaluation and follow-up monitoring. In 87 patients with CRC patients who underwent surgery, the average size of poorly differentiated tumors was the largest (25.01±14.08 cm2), which was significantly different from that of moderately differentiated tumors (P =0.039). There was a statistically significant difference in serum CEA level among different degrees of differentiation (P=0.018). The level of CEA was relatively low when tumors occurred in the transverse and ascending colon. When the level of CEA was high, negative mSEPT9 suggested that the probability of a tumor occurring in the cecum was high; positive mSEPT9 indicated that the tumor was highly likely to occur in the descending or sigmoid colon. Detection before and after surgery revealed that the level of mSEPT9 may be related to the tumor-bearing state of patients. A Follow-up study also showed that the sensitivity and specificity of mSEPT9 for recurrence and metastasis were 83.3% and 97.7%, respectively, and the sensitivity and specificity of CEA were 61.1% and 89.5%, respectively. The combined detection of mSEPT9 and CEA can indicate the location and size of colorectal cancer, while the detection of serum mSEPT9 may have clinical significance in the efficacy evaluation and follow-up monitoring of colorectal cancer. KEY WORDS: Colorectal Cancer, mSEPT9, Recurrence, Metastasis, CEA.

Reconstituted in vitro systems to reveal the roles and functions of septins.

Septins are essential cytoskeletal proteins involved in key cellular processes and have also been implicated in diseases from cancers to neurodegenerative pathologies. However, they have not been as thoroughly studied as other cytoskeletal proteins. In vivo, septins interact with other cytoskeletal proteins and with the inner plasma membrane. Hence, bottom-up in vitro cell-free assays are well suited to dissect the roles and behavior of septins in a controlled environment. Specifically, in vitro studies have been invaluable in describing the self-assembly of septins into a large diversity of ultrastructures. Given that septins interact specifically with membrane, the details of these septin-membrane interactions have been analyzed using reconstituted lipid systems. In particular, at a membrane, septins are often localized at curvatures of micrometer scale. In that context, in vitro assays have been performed with substrates of varying curvatures (spheres, cylinders or undulated substrates) to probe the sensitivity of septins to membrane curvature. This Review will first present the structural properties of septins in solution and describe the interplay of septins with cytoskeletal partners. We will then discuss how septins interact with biomimetic membranes and induce their reshaping. Finally, we will highlight the curvature sensitivity of septins and how they alter the mechanical properties of membranes.

Methylated Septin9 identified patients with colorectal carcinoma and showed higher sensitivity than conventional biomarkers in detecting tumor.

INTRODUCTION: It is worth noting the limitations in sensitivity of the existing biomarkers carcinoembryonic antigen (CEA) and carbohydrate antigen (CA 19-9) in detection of colorectal cancer (CRC). In our study, we address the performance of the liquid biopsy biomarker "methylated septin 9" (mSEPT9) in the detection and disease surveillance of CRC. MATERIALS AND METHODS: The monocentric prospective survey encompassed 120 patients diagnosed with CRC who underwent planned curative resection between December 2018 and December 2020. Blood samples were collected from the participants preoperatively as well as at 7 days, 6 weeks, and 3 months postoperatively. The presence of mSEPT9, CEA, and CA 19-9 was detected using the pro Epi Colon® 2.0 CE test, Elecsys® CEA, and Elecsys® CA19-9 electrochemiluminescence immunoassay, respectively. RESULTS: In the preoperative setting, mSEPT9 demonstrated superior capability in identifying patients with CRC compared to CEA and CA 19-9, with detection rates of 57%, 32%, and 18% respectively. Combining all three biomarkers increased the overall sensitivity to 66% preoperatively. In considering UICC stage and T-status, mSEPT9 exhibited higher sensitivity across all stages in comparison with conventional tumor markers, and 65% of patients with metastases were identified postoperatively through mSEPT9. Tumor recognition after surgery was achieved with the sensitivity of 72% and specificity of 91%. CONCLUSIONS: We recommend using mSEPT9 as a non-invasive diagnostic tool for the ongoing monitoring of patients with CRC. The sensitivity and specificity exhibited by mSEPT9 in recognition of tumor after surgery, highlights its particular potential for monitoring of CRC patients.

Mechanistic model for nuclear migration in hyphae during mitosis.

Saccharomyces cerevisiae and Candida albicans, the two well-known human pathogens, can be found in all three morphologies, i.e., yeast, pseudohyphae, and true hyphae. The cylindrical daughter-bud (germ tube) grows very long for true hyphae, and the cell cycle is delayed compared to the other two morphologies. The place of the nuclear division is specific for true hyphae determined by the position of the septin ring. However, the septin ring can localize anywhere inside the germ tube, unlike the mother-bud junction in budding yeast. Since the nucleus often migrates a long path in the hyphae, the underlying mechanism must be robust for executing mitosis in a timely manner. We explore the mechanism of nuclear migration through hyphae in light of mechanical interactions between astral microtubules and the cell cortex. We report that proper migration through constricted hyphae requires a large dynein pull applied on the astral microtubules from the hyphal cortex. This is achieved when the microtubules frequently slide along the hyphal cortex so that a large population of dyneins actively participate, pulling on them. Simulation shows timely migration when the dyneins from the mother cortex do not participate in pulling on the microtubules. These findings are robust for long migration and positioning of the nucleus in the germ tube at the septin ring.

Septin 9 Orients the Apico-Basal Polarity Axis and Controls Plasticity Signals.

The cytoskeleton is a master organizer of the cellular cortex and membrane trafficking and therefore plays a crucial role in apico-basal polarity. Septins form a family of GTPases that assemble into non-polar filaments, which bind to membranes and recruit cytoskeletal elements such as microtubules and actin using their polybasic (PB) domains, to perform their broad biological functions. Nevertheless, the role of septins and the significance of their membrane-binding ability in apico-basal polarity remains under-investigated. Here, using 3D cultures, we demonstrated that septin 9 localizes to the basolateral membrane (BM). Its depletion induces an inverted polarity phenotype, decreasing ß-catenin at BM and increasing transforming growth factor (TGFß) and Epithelial-Mesenchymal Transition (EMT) markers. Similar effects were observed after deleting its two PB domains. The mutant became cytoplasmic and apical. The cysts with an inverted polarity phenotype displayed an invasive phenotype, with src and cortactin accumulating at the peripheral membrane. The inhibition of TGFß-receptor and RhoA rescued the polarized phenotype, although the cysts from overexpressed septin 9 overgrew and presented a filled lumen. Both phenotypes corresponded to tumor features. This suggests that septin 9 expression, along with its assembly through the two PB domains, is essential for establishing and maintaining apico-basal polarity against tumor development.