Evaluation of the Prognostic Relevance of Differential Claudin Gene Expression Highlights Claudin-4 as Being Suppressed by TGFβ1 Inhibitor in Colorectal Cancer

Bioinformatics analysis of colorectal cancer transcriptomic data reveals novel prognostic signature and potential biomarker genes

OBJECTIVE

Colorectal cancer (CRC) is a type of digestive system cancer. At the molecular level, some factors, including genetic and epigenetic factors, as well as various signaling pathways such as oxidative stress and inflammation, play an active role in the onset of CRC. Genetic and epigenetic mutations, particularly in oncogenes and tumor suppressor genes, occur during colorectal adenocarcinoma development as a result of a change in gastrointestinal epithelial cell proliferation and self-renewal rates. This study aimed to determine the genes and molecular mechanisms that play a role in the emergence of this disease by analyzing the CRC data.

MATERIAL AND METHODS

Microarray data selected for bioinformatics analysis is Gene Expression data stored with the code GSE110224 in the National Center for Biotechnology Information (NCBI) Gene Expression Omnibus (GEO) database. Gene expression analysis, functional clustering analysis, enrichment analysis, and pathway analysis were performed using this data set.

RESULTS

Analysis of raw transcriptomic data revealed 1770 common DEGs in CRC. While the expression level of 769 of these genes increased, the expression level of 1001 genes decreased. A Protein-protein interaction (PPI) network was created from the first 25 genes with increased expression levels and 11 signature genes were identified. Increased expression of REG1A, MMP3, FOXQ1 and CEMIP genes and decreased expression of AQP8, CA1, CLDN8, PYY, CA4, CEACAM7 and SLC30A10 genes were observed.

CONCLUSIONS

This approach revealed a CRC-specific molecular profile and may provide some guidance for further investigation of potential biomarkers for diagnosis and prognosis prediction of CRC patients.

MTCH2 promotes the malignant progression of ovarian cancer through the upregulation of AIMP2 expression levels, mitochondrial dysfunction and by mediating energy metabolism

Ovarian cancer (OC) is a gynecological malignancy that ranks among the most common female cancers worldwide and notably reduces a patient's quality of life. Mitochondrial carrier homology 2 (MTCH2) is a mitochondrial outer membrane protein that serves a regulatory role in mitochondrial metabolism and cell death. The precise contribution and underlying molecular pathways of MTCH2 in the context of OC development is currently unclear. The present study aimed to investigate the roles of MTCH2 in the energy metabolism, cell proliferation and metastatic potential of OC cells and evaluate the regulatory relationship between MTCH2, aminoacyl transfer RNA synthetase-interacting multifunctional protein 2 (AIMP2) and claudin-3. An analysis of 67 patients with high-grade serous OC demonstrated increased expression levels of MTCH2, AIMP2 and claudin-3 in OC tumor tissue samples compared with in corresponding normal tissues adjacent to OC tissue samples. MTCH2 overexpression was significantly associated with the International Federation of Gynecology and Obstetrics stage and tumor differentiation of the OC tumor samples. In vitro experiments using the SK-OV-3 OC cell line demonstrated that MTCH2 exerts a regulatory effect on the cell proliferation, invasion and migratory capabilities of these cells. Knockdown of MTCH2 reduced ATP production, induced mitochondrial dysfunction and promoted cytoskeleton remodeling and apoptosis in SK-OV-3 OC cells. In addition, MTCH2 knockdown downregulated the expression levels of both claudin-3 and AIMP2 proteins. Knockdown of AIMP2 inhibited the regulatory effect of MTCH2. Co-immunoprecipitation experiments demonstrated that MTCH2 interacts with AIMP2 and claudin-3. The present study provides novel insights into the treatment of OC metastasis, as MTCH2 was demonstrated to serve roles in the progression of OC cells through the regulation of claudin-3 via AIMP2, which could provide novel insights into the treatment of ovarian cancer metastasis.

Tight Junctions and Cancer: Targeting Claudin-1 and Claudin-4 in Thyroid Pathologies

Purpose: Claudins are tight junction proteins partaking in epithelial-mesenchymal transition and cancer progression. In this study, we investigated the expression patterns of claudin-1 and claudin-4 in thyroid pathologies, discussed their links with the pathogenesis of thyroid cancers, and reviewed the therapeutic potential of targeting claudins in cancers. Methods: The research group 162 cores of thyroid samples from patients (70 female and 11 male) diagnosed with thyroid adenoma, goiter, papillary, medullary, and anaplastic thyroid cancers. All samples were stained for the expression of claudin-1 and claudin-4, and the analysis of IHC was performed. Results: Goiter samples showed negative claudin-1 and mostly positive expression of claudin-4. Papillary thyroid cancer and thyroid adenoma showed positive expression of claudin-1, while claudin-4 was positive in papillary thyroid cancers, goiters, and adenomas. In The Cancer Genome Atlas cohort, claudin-1 and claudin-4 were overexpressed in papillary thyroid cancer compared to normal thyroid tissues. Patients with high claudin-1 expression had significantly lower 5-year overall survival than patients with low claudin-1 levels (86.75% vs. 98.65, respectively). In multivariate analysis, high claudin-1 expression (HR 7.91, CI 95% 1.79-35, p = 0.006) and advanced clinical stage remained statistically significant prognostic factors of poor prognosis in papillary thyroid cancer. Conclusions: The pattern of claudin-1 staining was pathology-specific and changed between cancers of different histology. This phenomenon may be associated with the different pathogenesis of thyroid cancers and early metastasis. The loss of claudin-1 and claudin-4 characterized more aggressive cancers. Several studies have shown the benefits of targeting claudins in cancers, but their implementation into clinical practice requires further trials.

Claudins in Cancer: A Current and Future Therapeutic Target

Claudins are a family of 27 proteins that have an important role in the formation of tight junctions. They also have an important function in ion exchange, cell mobility, and the epithelial-to-mesenchymal transition, the latter being very important in cancer invasion and metastasis. Therapeutic targeting of claudins has been investigated to improve cancer outcomes. Recent evidence shows improved outcomes when combining monoclonal antibodies against claudin 18.2 with chemotherapy for patients with gastroesophageal junction cancer. Currently, chimeric antigen receptor T-cells targeting claudin 18 are under investigation. In this review, we will discuss the major functions of claudins, their distribution in the normal as well as cancerous tissues, and their effect in cancer metastasis, with a special focus on the therapeutic targeting of claudins to improve cancer outcomes.

CCL21 and CLDN11 Are Key Driving Factors of Lymph Node Metastasis in Gastric Cancer

BACKGROUND

Gastric cancer (GC) is a leading cause of cancer-related deaths worldwide. Understanding the molecular mechanisms of GC metastasis is crucial for improving patient survival outcomes.

METHODS

RNA sequencing and analysis were performed on tissue samples from primary and lymph node metastatic lesions of gastric cancer. Differential gene analysis and functional pathway analysis were conducted. Immune infiltrating environment and protein expression levels were evaluated using immunohistochemistry. Cell experiments were conducted to investigate the role of CCL21 in GC metastasis.

RESULTS

ACTG2, CNN1, DES, MUC6, and PGC were significantly upregulated in primary tumor cells, while CCL21, MS4A1, CR2, CLDN11, and FDCSP were significantly upregulated in metastatic tumor cells. Functional pathway analysis revealed enrichment in pathways related to immune response. CLDN11 and CCL21 were found to play important roles in promoting gastric cancer metastasis. Cell experiments confirmed the role of CCL21 in promoting GC cell growth and metastasis. CCL21 is highly expressed in GC tissues and binds to CCR7, leading to upregulation of CLDN11. This results in GC-lymph node metastasis and abnormal activation of immune cells (B cells and CD4+ T cells).

CONCLUSION

Inhibition of CCL21 and CLDN11 proteins may be a promising strategy for treating GC and preventing lymph node metastasis. These findings provide specific molecular markers for early lymph node metastases of GC, which can aid in developing treatment strategies and predicting patient prognosis.