Clinical and prognostic significance of CC chemokine receptor type 8 protein expression in gastrointestinal stromal tumors

Unveiling the structural mechanisms of nonpeptide ligand recognition and activation in human chemokine receptor CCR8

The human CC chemokine receptor 8 (CCR8) is an emerging therapeutic target for cancer immunotherapy and autoimmune diseases. Understanding the molecular recognition of CCR8, particularly with nonpeptide ligands, is valuable for drug development. Here, we report three cryo-electron microscopy structures of human CCR8 complexed with Gi trimers in the ligand-free state or activated by nonpeptide agonists LMD-009 and ZK 756326. A conserved Y1.39Y3.32E7.39 motif in the orthosteric binding pocket is shown to play a crucial role in the chemokine and nonpeptide ligand recognition. Structural and functional analyses indicate that the lack of conservation in Y1143.33 and Y1724.64 among the CC chemokine receptors could potentially contribute to the selectivity of the nonpeptide ligand binding to CCR8. These findings present the characterization of the molecular interaction between a nonpeptide agonist and a chemokine receptor, aiding the development of therapeutics targeting related diseases through a structure-based approach.

Advances in immunology and immunotherapy for mesenchymal gastrointestinal cancers

Mesenchymal gastrointestinal cancers are represented by the gastrointestinal stromal tumors (GISTs) which occur throughout the whole gastrointestinal tract, and affect human health and economy globally. Curative surgical resections and tyrosine kinase inhibitors (TKIs) are the main managements for localized GISTs and recurrent/metastatic GISTs, respectively. Despite multi-lines of TKIs treatments prolonged the survival time of recurrent/metastatic GISTs by delaying the relapse and metastasis of the tumor, drug resistance developed quickly and inevitably, and became the huge obstacle for stopping disease progression. Immunotherapy, which is typically represented by immune checkpoint inhibitors (ICIs), has achieved great success in several solid tumors by reactivating the host immune system, and been proposed as an alternative choice for GIST treatment. Substantial efforts have been devoted to the research of immunology and immunotherapy for GIST, and great achievements have been made. Generally, the intratumoral immune cell level and the immune-related gene expressions are influenced by metastasis status, anatomical locations, driver gene mutations of the tumor, and modulated by imatinib therapy. Systemic inflammatory biomarkers are regarded as prognostic indicators of GIST and closely associated with its clinicopathological features. The efficacy of immunotherapy strategies for GIST has been widely explored in pre-clinical cell and mouse models and clinical experiments in human, and some patients did benefit from ICIs. This review comprehensively summarizes the up-to-date advancements of immunology, immunotherapy and research models for GIST, and provides new insights and perspectives for future studies.

HAMP as a Prognostic Biomarker for Colorectal Cancer Based on Tumor Microenvironment Analysis

Colorectal cancer (CRC) is the most common digestive tumor in the world and has a high mortality rate. The development and treatment of CRC are related to the immune microenvironment, but immune response-related prognostic biomarkers are lacking. In this study, we used The Cancer Genome Atlas (TCGA) to explore the tumor microenvironment (TME) and weighted gene coexpression network analysis (WGCNA) to identify significant prognostic genes. We also identified differentially expressed genes in the TCGA data and explored immune-related genes and transcription factors (TFs). Then, we built a TF regulatory network and performed a comprehensive prognostic analysis of an lncRNA-associated competitive endogenous RNA network (ceRNA network) to build a prognostic model. CCR8 and HAMP were identified both in the WGCNA key module and as immune-related genes. HAMP had good prognostic value for CRC and was highly expressed in CRC tissues and had a negative correlation with CD4⁺ T cells and M0 macrophages based on immunohistochemistry and immunofluorescence staining of clinical specimens.We found that HAMP had high prognostic and therapeutic target value for CRC and was associated with liver metastasis. These analysis results revealed that HAMP may be a candidate immune-related prognostic biomarker for CRC.

Prognostic Factors and Management of Colorectal Gastrointestinal Stromal Tumors

Introduction The gastrointestinal stromal tumor (GIST) is the most common mesenchymal neoplasm of the gastrointestinal tract. Even though it can be found in any location of the digestive tract, the colorectal GIST is rare. With this study, we aim to review the current knowledge regarding the prognosis and management of colorectal GIST.

Methods A literature search was conducted in PubMed, and 717 articles were collected. After analyzing these studies, 60 articles were selected to use in this review.

Results The mitotic index, as well as tumor size and location were identified as good discriminators of prognosis in various studies. Surgery remains the only curative therapy for potentially resectable tumors. However, even after surgical resection, some patients develop disease recurrence and metastasis, especially those with high-risk tumors. Therefore, surgical resection alone might be inadequate for the management of all colorectal GISTs. The discovery of GIST's molecular pathway led to a shift in its therapy, insofar as tyrosine kinase inhibitors became part of the treatment schemes for this tumor, revolutionizing the treatment's outcome and prognosis.

Discussion/Conclusion The controversy concerning colorectal GIST prognosis and treatment can be, in part, attributed to the limited number of studies in the literature. In this review, we gathered the most recent knowledge about the prognosis and management of GIST in this rare location and propose two algorithms for its approach. Lastly, we highlight the importance of an individualized approach in the setting of a multidisciplinary team.

Clinical and Prognostic Significance of Tumor-Infiltrating CD8+ T Cells and PD-L1 Expression in Primary Gastrointestinal Stromal Tumors

Purpose

Immunotherapy for gastrointestinal stromal tumors (GISTs) remains a clinical challenge. The present study aimed to explore the clinical and prognostic significance of immune cell infiltration and PD-L1 expression in GISTs.

Methods

A total of 507 clinical tissue specimens of primary GISTs were collected for immunohistochemical analysis of immune cell infiltration and PD-L1 expression. Influencing factors of survival were evaluated by Kaplan–Meier analysis. Univariate and multivariate analyses were performed using the Cox regression model.

Results

There were significant differences in sex, tumor location, size, mitotic index, NIH risk grade, and cell morphology between different gene mutation types of GISTs. Immune cell infiltration in GISTs mainly involved macrophages and T cells. PD-1 was expressed in 48.5% of the tissue specimens, and PD-L1 expression was detected in 46.0% of the samples. PD-L1 expression was negatively correlated with the tumor size and mitotic index but positively correlated with the number of CD8+ T cells. There were significant differences in the number of CD8+ T cells between different gene mutation types. Wild type-mutant GISTs were enriched with CD8+ T cells as compared with KIT- and PDGFRA-mutant GISTs. The number of CD8+ T cells was higher in non-gastric GISTs. PD-L1 and CD8+ T cells were independent predictors for better relapse-free survival of GISTs.

Conclusions

PD-L1 expression is a predictive biomarker for better prognosis of GISTs. Non-gastric GIST patients with wild-type mutations may be the beneficiaries of PD-1/PD-L1 inhibitors.

Improved understanding of gastrointestinal stromal tumors biology as a step for developing new diagnostic and therapeutic schemes

A gastrointestinal stromal tumor (GIST) is the most common mesenchymal tumor of the human gastrointestinal tract, with an estimated incidence of 10-15 per 1 million per year. While preparing holistic care for patients with GIST diagnosis, scientists might face several difficulties - insufficient risk stratification, acquired or secondary resistance to imatinib, or the need for an exceptional therapy method associated with wild-type tumors. This review summarizes recent advances associated with GIST biology that might enhance diagnostic and therapeutic strategies. New molecules might be incorporated into risk stratification schemes due to their proven association with outcomes; however, further research is required. Therapies based on the significant role of angiogenesis, immunology, and neural origin in the GIST biology could become a valuable enhancement of currently implemented treatment schemes. Generating miRNA networks that would predict miRNA regulatory functions is a promising approach that might help in better selection of potential biomarkers and therapeutical targets in cancer, including GISTs.

The Therapeutic Potential of Regulatory T Cells: Challenges and Opportunities

Regulatory T cells (Tregs) are an immunosuppressive subgroup of CD4+ T cells which are identified by the expression of forkhead box protein P3 (Foxp3). The modulation capacity of these immune cells holds an important role in both transplantation and the development of autoimmune diseases. These cells are the main mediators of self-tolerance and are essential for avoiding excessive immune reactions. Tregs play a key role in the induction of peripheral tolerance that can prevent autoimmunity, by protecting self-reactive lymphocytes from the immune reaction. In contrast to autoimmune responses, tumor cells exploit Tregs in order to prevent immune cell recognition and anti-tumor immune response during the carcinogenesis process. Recently, numerous studies have focused on unraveling the biological functions and principles of Tregs and their primary suppressive mechanisms. Due to the promising and outstanding results, Tregs have been widely investigated as an alternative tool in preventing graft rejection and treating autoimmune diseases. On the other hand, targeting Tregs for the purpose of improving cancer immunotherapy is being intensively evaluated as a desirable and effective method. The purpose of this review is to point out the characteristic function and therapeutic potential of Tregs in regulatory immune mechanisms in transplantation tolerance, autoimmune diseases, cancer therapy, and also to discuss that how the manipulation of these mechanisms may increase the therapeutic options.