Exosomal Plasma Gelsolin Is an Immunosuppressive Mediator in the Ovarian Tumor Microenvironment and a Determinant of Chemoresistance

Comprehensive analysis of basement membrane-related gene based on single-cell and bulk RNA sequencing data to predict prognosis and evaluate immune characteristics in colorectal cancer

AIMS

Basement membrane-related genes (BMs) participate in regulating cell polarity, invasion, metastasis, and survival across different tumor types. Nevertheless, the specific functions of BMs in colorectal cancer (CRC) remain uncertain.

METHODS

To investigate the clinical relevance of BMs in CRC, we retrieved both gene expression and clinical data from The Cancer Genome Atlas (TCGA) datasets for subsequent analysis. The Kaplan-Meier (K-M) survival curve was employed to evaluate prognosis in high- and low-risk groups. Furthermore, additional analyses, including nomogram construction, functional enrichment, examination of the tumor immune microenvironment, prediction of small-molecule drugs, and more, were conducted to delve into the significance of BM-related signatures in CRC. Single-cell data from seven CRC patients were obtained from the TISCH2 database, and expression validation and cell source exploration of BM-related signatures were performed. Lastly, the expression and function of TIMP1, a key gene in BMs that may play a role in the progression of CRC, was validated in vitro through a series of basic experiments.

RESULTS

We constructed a seven BMs-based model to categorize CRC patients into high-risk and low-risk groups. K-M survival analysis indicated a poorer prognosis for high-risk CRC patients. Cox regression analysis further identified the risk score as an independent prognostic factor for CRC patients. The nomogram model exhibited superior discrimination and calibration abilities of CRC patients. Based on the results from GO/KEGG and GSEA, genes in the high-risk subgroup were implicated in immune-related pathways and exhibited a positive correlation with immune checkpoints. In single-cell data, we found that TIMP1 is highly expressed in many cells, especially in malignant tumor cells. We also observed up-regulation of TIMP1 in CRC cell lines, promoting cancer invasion and migration in vitro.

CONCLUSIONS

Our study has discovered a novel prognostic index derived from BM-related genes in CRC patients. Specifically, the new model enables patient stratification, improving the selection of individuals likely to benefit from immunotherapy.

Generation and Characterization of Trastuzumab/Pertuzumab-Resistant HER2-Positive Breast Cancer Cell Lines

The combination of trastuzumab and pertuzumab as first-line therapy in patients with HER2-positive breast cancer has shown significant clinical benefits compared to trastuzumab alone. However, despite initial therapeutic success, most patients eventually progress, and tumors develop acquired resistance and invariably relapse. Therefore, there is an urgent need to improve our understanding of the mechanisms governing resistance in order to develop targeted therapeutic strategies with improved efficacy. We generated four novel HER2-positive cell lines via prolonged exposure to trastuzumab and pertuzumab and determined their resistance rates. Long-term resistance was confirmed by a significant increase in the colony-forming capacity of the derived cells. We authenticated the molecular identity of the new lines via both immunohistochemistry for the clinical phenotype and molecular profiling of point mutations. HER2 overexpression was confirmed in all resistant cell lines, and acquisition of resistance to trastuzumab and pertuzumab did not translate into differences in ER, PR, and HER2 receptor expression. In contrast, changes in the expression and activity of other HER family members, particularly HER4, were observed. In the same vein, analyses of the receptor and effector kinase status of different cellular pathways revealed that the MAPK pathway may be involved in the acquisition of resistance to trastuzumab and pertuzumab. Finally, proteomic analysis confirmed a significant change in the abundance patterns of more than 600 proteins with implications in key biological processes, such as ribosome formation, mitochondrial activity, and metabolism, which could be relevant mechanisms in the generation of resistance in HER2-positive breast cancer. We concluded that these resistant BCCLs may be a valuable tool to better understand the mechanisms of acquisition of resistance to trastuzumab and pertuzumab-based anti-HER2 therapy.

The role of coagulome in the tumor immune microenvironment

The rising incidence and persistent thrombosis in multiple cancers including those that are immunosuppressive highlight the need for understanding the tumor coagulome system and its role beyond hemostatic complications. Immunotherapy has shown significant benefits in solid organ tumors but has been disappointing in the treatment of hypercoagulable cancers, such as glioblastoma and pancreatic ductal adenocarcinomas. Thus, targeting thrombosis to prevent immunosuppression seems a clinically viable approach in cancer treatment. Hypercoagulable tumors often develop fibrin clots within the tumor microenvironment (TME) that dictates the biophysical characteristics of the tumor tissue. The application of systems biology and single-cell approaches highlight the potential role of coagulome or thrombocytosis in shaping the tumor immune microenvironment (TIME). In-depth knowledge of the tumor coagulome would provide unprecedented opportunities to better predict the hemostatic complications, explore how thrombotic stroma modulates tumor immunity, reexamine the significance of clinical biomarkers, and enable steering the stromal versus systemic immune response for boosting the effectiveness of immune checkpoint inhibitors in cancer treatment. We focus on the role of coagulation factors in priming a suppressive TIME and the huge potential of existing anticoagulant drugs in the clinical settings of cancer immunotherapy.