Cytokeratin-18 fragments predict treatment response and overall survival in gastric cancer in a randomized controlled trial

KRT18 regulates trophoblast cell migration and invasion which are essential for embryo implantation

Female infertility is a worldwide concern that impacts the quality of life and well-being of affected couples. Failure of embryo implantation is a major cause of early pregnancy loss and is precisely regulated by a programmed molecular mechanism. Recent studies have shown that proper trophoblast adhesion and invasion are essential for embryo implantation. However, the potential regulatory mechanism involved in trophoblast adhesion and invasion has yet to be fully elucidated. KRT18 has been reported to play a critical role in early embryonic development, but its physiological function in embryo implantation remains unclear. In the present study, we revealed that KRT18 was highly expressed in trophoblast cells and that knockdown of KRT18 in mouse embryos inhibited embryo adhesion and implantation. In vitro experiments further showed that silencing KRT18 disturbed trophoblast migration and invasion. More importantly, we provide evidence that KRT18 directly binds to and stabilizes cell surface E-cadherin in trophoblast cells through microscale thermophoresis (MST) analysis and molecular biology experiments. In brief, our data reveal that KRT18, which is highly expressed in trophoblast cells, plays an important role in the regulation of trophoblast invasion and adhesion during embryo implantation by directly binding to E-cadherin.

A programmed cell death-related model based on machine learning for predicting prognosis and immunotherapy responses in patients with lung adenocarcinoma

Background

lung adenocarcinoma (LUAD) remains one of the most common and lethal malignancies with poor prognosis. Programmed cell death (PCD) is an evolutionarily conserved cell suicide process that regulates tumorigenesis, progression, and metastasis of cancer cells. However, a comprehensive analysis of the role of PCD in LUAD is still unavailable.

Methods

We analyzed multi-omic variations in PCD-related genes (PCDRGs) for LUAD. We used cross-validation of 10 machine learning algorithms (101 combinations) to synthetically develop and validate an optimal prognostic cell death score (CDS) model based on the PCDRGs expression profile. Patients were classified based on their median CDS values into the high and low-CDS groups. Next, we compared the differences in the genomics, biological functions, and tumor microenvironment of patients between both groups. In addition, we assessed the ability of CDS for predicting the response of patients from the immunotherapy cohort to immunotherapy. Finally, functional validation of key genes in CDS was performed.

Results

We constructed CDS based on four PCDRGs, which could effectively and consistently stratify patients with LUAD (patients with high CDS had poor prognoses). The performance of our CDS was superior compared to 77 LUAD signatures that have been previously published. The results revealed significant genetic alterations like mutation count, TMB, and CNV were observed in patients with high CDS. Furthermore, we observed an association of CDS with immune cell infiltration, microsatellite instability, SNV neoantigens. The immune status of patients with low CDS was more active. In addition, CDS could be reliable to predict therapeutic response in multiple immunotherapy cohorts. In vitro experiments revealed that high DNA damage inducible transcript 4 (DDIT4) expression in LUAD cells mediated protumor effects.

Conclusion

CDS was constructed based on PCDRGs using machine learning. This model could accurately predict patients' prognoses and their responses to therapy. These results provide new promising tools for clinical management and aid in designing personalized treatment strategies for patients with LUAD.

Novel Biomarkers of Gastric Adenocarcinoma: Current Research and Future Perspectives

Simple Summary

Gastric cancer is characterized by poor survival rates despite surgery and chemotherapy. Current research focuses on biomarkers to improve diagnosis and prognosis, and to enable targeted treatment strategies. The aim of our review was to give an overview over the wide range of novel biomarkers in gastric cancer. These biomarkers are targets of a specific treatment, such as antibodies against human epidermal growth factor receptor 2. Other promising biomarkers for targeted therapies that have shown relevance in clinical trials are vascular endothelial growth factor, programmed cell death protein 1, and Claudin 18.2. There is a vast number of biomarkers based on DNA, RNA, and protein expression, as well as detection of circulating tumor cells and the immune tumor microenvironment.

Abstract

Overall survival of gastric cancer remains low, as patients are often diagnosed with advanced stage disease. In this review, we give an overview of current research on biomarkers in gastric cancer and their implementation in treatment strategies. The HER2-targeting trastuzumab is the first molecular targeted agent approved for gastric cancer treatment. Other promising biomarkers for targeted therapies that have shown relevance in clinical trials are VEGF and Claudin 18.2. Expression of MET has been shown to be a negative prognostic factor in gastric cancer. Targeting the PD-1/PD-L1 pathway with immune checkpoint inhibitors has proven efficacy in advanced gastric cancer. Recent technology advances allow the detection of circulating tumor cells that may be used as diagnostic and prognostic indicators and for therapy monitoring in gastric cancer patients. Prognostic molecular subtypes of gastric cancer have been identified using genomic data. In addition, transcriptome profiling has allowed a comprehensive characterization of the immune and stromal microenvironment in gastric cancer and development of novel risk scores. These prognostic and predictive markers highlight the rapidly evolving field of research in gastric cancer, promising improved treatment stratification and identification of molecular targets for individualized treatment in gastric cancer.

Elevated SYNC Expression Is Associated with Gastric Tumorigenesis and Infiltration of M2-Polarized Macrophages in the Gastric Tumor Immune Microenvironment

Aims: To assess the expression and epigenetic regulation of Syncoilin, intermediate filament protein (SYNC) in gastric cancer tissues, and to determine its associations with clinicopathological features; immune infiltration of macrophages in tumors; and patient survival. Materials and Methods: Clinicopathological features, expression profiles, and methylation data of the SYNC gene were obtained from multi-institutional real-world public datasets. A total of 1601 samples from patients with gastric cancer were examined. The associations between clinicopathological features and SYNC expression levels were assessed by the chi-square test; survival was assessed using the Kaplan-Meier analysis. The infiltration levels of M1, 2-polarized tumor-associated macrophages (TAMs) in a gastric tumor immune microenvironment were quantified using deconvolution, and the correlation between SYNC expression level and M1, 2-polarized macrophages' infiltration was examined using the Pearson correlation test. SYNC gene methylation data were analyzed to investigate epigenetic control of its expression. Results: SYNC expression was elevated in gastric cancer tissues (p < 0.01), and was associated with a poorer overall survival (p < 0.01) and poorer postprogression survival (p = 0.01). Higher SYNC levels were significantly associated with more aggressive clinicopathological features in gastric cancer patients (p < 0.05). SYNC was also associated with the infiltration of M2-polarized TAMs in the gastric tumor immune microenvironment (p < 0.001). Hypomethylation was shown to be associated with SYNC's upregulation (p < 0.05). Conclusion: SYNC is highly expressed in gastric cancer tissues and has the potential to be a therapeutic target and to serve as a prognostic marker.

Serum caspase-cleaved cytokeratin-18 fragment as a prognostic biomarker in hematological patients with febrile neutropenia

The study aim was to determine the benefit of the measurement of serum caspase-cleaved cytokeratin-18 (CK-18) fragment as a prognostic marker of febrile neutropenia (FN) in hematological patients. The study population consisted of 86 consecutive patients with FN who received intensive chemotherapy for hematological malignancy at the adult hematology ward of Kuopio University Hospital. Twenty-three patients (27%) had acute myeloid leukemia, and 63 patients (73%) were autologous stem cell transplant recipients. Serum caspase-cleaved CK-18 fragment M30, C-reactive protein (CRP) and procalcitonin (PCT) were measured at the onset of FN (d0), on day 1 (d1), and on day 2 (d2). Eight patients (9%) developed severe sepsis, including three patients with septic shock. Eighteen patients (21%) had a blood culture-positive infection. Serum CK-18 fragment peaked on the first day after fever onset in patients with severe sepsis. Higher CK-18 level was associated with severe sepsis, intensive care unit treatment, and fatal outcome, but not with blood culture positivity. In ROC curve analysis, d1 serum CK-18 fragment predicted severe sepsis with an area under the curve (AUC) of 0.767, CRP with an AUC of 0.764, and PCT with an AUC of 0.731. On d2, the best predictive capacity was observed for CRP with an AUC of 0.832. The optimal cutoff of caspase-cleaved CK-18 fragment M30 for predicting severe sepsis was 205 U/L on d1. In hematological patients, serum CK-18 fragment was found to be a potential prognostic marker of severe sepsis at early stages of FN.

KRT18 Modulates Alternative Splicing of Genes Involved in Proliferation and Apoptosis Processes in Both Gastric Cancer Cells and Clinical Samples

Keratin 18 (KRT18), one of the most abundant keratins in epithelial and endothelial cells, has been reported to be aberrantly expressed in many malignancies and extensively regarded as a biomarker and important regulator in multiple cancers, including gastric cancer (GC). But the molecular regulatory mechanisms of KRT18 in GC patients and cells are largely unknown. In the present study, we analyzed the expression level of KRT18 in 450 stomach adenocarcinoma tissue samples from TCGA database and found a significantly higher expression level in tumor tissues. We then explored the potential functions of KRT18 in AGS cells (human gastric adenocarcinoma cell line) by KRT18 knockdown using siRNA and whole transcriptome RNA-seq analysis. Notably, KRT18 selectively regulates expression of cell proliferation and apoptotic genes. Beyond this, KRT18 affects the alternative splicing of genes enriched in apoptosis, cell cycle, and other cancer-related pathways, which were then validated by reverse transcription-quantitative polymerase chain reaction approach. We validated KRT18-KD promoted apoptosis and inhibited proliferation in AGS cells. We then used RNA-seq data of GC samples to further demonstrate the modulation of KRT18 on alternative splicing regulation. These results together support the conclusion that KRT18 extensively modulates diverse alternative splicing events of genes enriched in proliferation and apoptosis processes. And the dysregulated splicing factors at transcriptional or posttranscriptional level by KRT18 may contribute to the alternative splicing change of many genes, which expands the functional importance of keratins in apoptotic and cell cycle pathways at the posttranscriptional level in GC.

Molecular Tumor Subtypes of HPV-Positive Head and Neck Cancers: Biological Characteristics and Implications for Clinical Outcomes

Until recently, research on the molecular signatures of Human papillomavirus (HPV)-associated head and neck cancers mainly focused on their differences with respect to HPV-negative head and neck squamous cell carcinomas (HNSCCs). However, given the continuing high incidence level of HPV-related HNSCC, the time is ripe to characterize the heterogeneity that exists within these cancers. Here, we review research thus far on HPV-positive HNSCC molecular subtypes, and their relationship with clinical characteristics and HPV integration into the host genome. Different omics data including host transcriptomics and epigenomics, as well as HPV characteristics, can provide complementary viewpoints. Keratinization, mesenchymal differentiation, immune signatures, stromal cells and oxidoreductive processes all play important roles.

Generation of Rat Monoclonal Antibody for Cytokeratin 18 by Immunization of Three-Dimensional-Cultured Cancer Cells

Cytokeratin (CK) 18 is an intermediate filament protein that plays a major functional role in the integrity and mechanical stability of cells. Since both CK8 and CK18 are major components of simple epithelia, in the context of tumors, they are expressed in most carcinomas, and have been studied as diagnostic and prognostic markers in tumor pathology. CK18 is also cleaved by some caspases during apoptosis. Three-dimensional (3D)-cultured cancer cells are useful for cancer research as an intermediate model between in vitro cancer cell line cultures and in vivo tumors. In this study, we produced rat monoclonal antibodies (mAbs) through immunization of the lysate from 3D-cultured DLD-1 cells to elucidate a characteristic feature of a tumor, and our results showed that mAb 2H7 recognized human CK18. Furthermore, we indicated that mAb 2H7 was useful for immunoblotting, immunoprecipitation, and immunofluorescence staining. Therefore, it may be useful as a diagnostic tool for evaluating malignancy.

Prognostic value of non-invasive serum Cytokeratin 18 detection in gastrointestinal cancer: a meta-analysis

Background: Gastrointestinal cancer is one of the most common neoplasms. Cytokeratin 18(CK18) is widely expressed in many different organs and cancers. Emerging data suggested conflicting results about the role of CK18 during carcinogenesis. The aim of this study is to systematically review the prognostic value of circulating CK18 (M65) and caspase-Cleaved CK18 (M30) in digestive cancers.

Materials and Methods: We searched major database for manuscripts reporting the effect of pretreatment CK18 on survival of digestive cancer patients. Revman5.3 and R were the software used for analysis. Pooled multivariable-adjusted hazard ratios (HR) for overall survival (OS) were calculated in all patients and many different subgroup analyses by stratifying on tumor type, metastasis stage, and ethnicity.

Results: 11 original studies were included for analysis. A low level of M30 and M65 were shown to be a protective factor for all cancer patients (HR 0.49, 95%CI 0.33-0.73, P=0.0003; HR 0.48, 95% CI 0.32-0.70, P =0.0001, respectively). The low M30 remained to be a protective factor for metastasized cancer patients while M65 had no statistically significant correlation with prognosis.

Conclusions: Non-invasive total and cleaved CK18 level detection by ELISA could be potentially a useful predictor of prognosis of digestive cancer patients. Further studies are warranted to investigate the molecular mechanisms of CK18.

KRT18 is correlated with the malignant status and acts as an oncogene in colorectal cancer

Keratin 18 (KRT18) has been suggested to be overexpressed in most types of human tumor, but the expression pattern of KRT18 in colorectal cancer (CRC) remained unknown. In our research, KRT18 protein expression was markedly increased in CRC cancer tissues and cell lines compared with adjacent normal colorectal tissues and normal colonic epithelial cell line, respectively. Meanwhile, we observed high KRT18 expression was associated with advanced clinical stage, deep tumor invasion, lymph node metastasis, distant metastasis, poor differentiation and unfavorable prognosis in CRC patients. Multivariate Cox regression analysis showed high expression of KRT18 was an unfavorable independent predictor for overall survival in CRC patients. The in vitro studies indicated down-regulation of KRT18 expression depressed CRC cell viability, migration and invasion. In conclusion, KRT18 serves as an oncogenic role in CRC progression and may be a therapeutic target for promoting CRC patients' prognosis.

Preparation of the Low Molecular Weight Serum Proteome for Mass Spectrometry Analysis

The ability to cure or manage many diseases is highly dependent on the ability to correctly diagnose them at the earliest possible stage. Diagnosis relies heavily on biomarkers whether these be visual symptoms or molecules found within samples acquired from the patient. For conditions that lack useful biomarkers, researchers are often faced with the task of sifting through very complex biological samples (i.e., serum, plasma, urine, tissue, cells, etc.) with the hope of discovering a small number of molecules that are exquisitely diagnostic for the condition of interest. One discovery strategy that has been frequently used is to fractionate the biological samples being studied into simpler aliquots that can be more easily characterized using existing technologies. One such fractionation method is to isolate a specific portion based on a specific property (i.e., size, phosphorylation state, charge, etc.) of the proteins within the sample. This method provides a simplified sample that can be characterized at a higher coverage level than the complex sample from which it was derived. This chapter details one of these methods, the extraction and analysis of the low molecular weight proteome of human serum.

Cytokeratin 18 regulates the transcription and alternative splicing of apoptotic‑related genes and pathways in HeLa cells

Cytokeratin 18 (CK18), one of the major components of intermediate filaments (IF) in simple epithelial cells, undergoes caspase-mediated cleavage upon epithelial cell necrosis and apoptosis. CK18 has been used as a biomarker of several cancers and has been reported to be dysregulated in cervical cancers. The effects of dysregulated expression of CK18 at a molecular level are, however, unclear. In the present study, the function of CK18 in HeLa cells, a cell line derived from a cervical cancer cells, was investigated using shRNA knockdown. Reduced levels of CK18 led to a significant decrease in cell apoptosis, compared with control cells. Notably, RNA-seq analysis of the transcriptomes of HeLa cells, with or without CK18 knockdown, revealed that genes in the NF-κB pathway, and certain apoptosis pathways, were under global transcriptional and alternative splicing regulation. Quantitative RT-PCR confirmed the CK18-regulated transcription of apoptotic genes FAS and FADD, as well as immune genes CXCL2 and CD79B, in addition to alternative splicing of FAS and CTNNB1. Western blot analysis further revealed that CK18 knockdown led to reduced expression of CASP8. In conclusion, the present study indicated that CK18 played a role in apoptosis, which may be mediated via a feed-back regulation loop and may involve regulation of transcription and alternative splicing of a number of genes in apoptotic pathways.