Comprehensive Analysis of CPA4 as a Poor Prognostic Biomarker Correlated with Immune Cells Infiltration in Bladder Cancer

Integrated analysis reveals a novel 5-fluorouracil resistance-based prognostic signature with promising implications for predicting the efficacy of chemotherapy and immunotherapy in patients with colorectal cancer

BACKGROUND

5-Fluorouracil (5-FU) has been used as a standard first-line treatment for colorectal cancer (CRC) patients. Although 5-FU-based chemotherapy and immune checkpoint blockade (ICB) have achieved success in treating CRC, drug resistance and low response rates remain substantial limitations. Thus, it is necessary to construct a 5-FU resistance-related signature (5-FRSig) to predict patient prognosis and identify ideal patients for chemotherapy and immunotherapy.

METHODS

Using bulk and single-cell RNA sequencing data, we established and validated a novel 5-FRSig model using stepwise regression and multiple CRC cohorts and evaluated its associations with the prognosis, clinical features, immune status, immunotherapy, neoadjuvant therapy, and drug sensitivity of CRC patients through various bioinformatics algorithms. Unsupervised consensus clustering was performed to categorize the 5-FU resistance-related molecular subtypes of CRC. The expression levels of 5-FRSig, immune checkpoints, and immunoregulators were determined using quantitative real-time polymerase chain reaction (RT‒qPCR). Potential small-molecule agents were identified via Connectivity Map (CMap) and molecular docking.

RESULTS

The 5-FRSig and cluster were confirmed as independent prognostic factors in CRC, as patients in the low-risk group and Cluster 1 had a better prognosis. Notably, 5-FRSig was significantly associated with 5-FU sensitivity, chemotherapy response, immune cell infiltration, immunoreactivity phenotype, immunotherapy efficiency, and drug selection. We predicted 10 potential compounds that bind to the core targets of 5-FRSig with the highest affinity.

CONCLUSION

We developed a valid 5-FRSig to predict the prognosis, chemotherapeutic response, and immune status of CRC patients, thus optimizing the therapeutic benefits of chemotherapy combined with immunotherapy, which can facilitate the development of personalized treatments and novel molecular targeted therapies for patients with CRC.

Macrophage-Induced Carboxypeptidase A4 Promotes the Progression of Anaplastic Thyroid Cancer

Background: The density of tumor-associated macrophages in the tumor microenvironment of anaplastic thyroid cancer (ATC) is associated with poor prognosis. However, the crosstalk between macrophages and ATC cells is poorly understood. This study aimed to examine the impact of macrophages on cancer cell phenotypes. We found a new mediator between M2 macrophages and ATC cells through proteomics analysis. Methods: The role of macrophages in proliferation, migration, and invasion of ATC cells was evaluated using coculture assay and conditioned medium (CM). Secretory factors in the CM from single or coculture were identified using liquid chromatography-tandem mass spectrometry proteomics analysis. We evaluated the role of the secretory factor in proliferation, migration, and invasion of cancer cells. In vivo xenograft model was used to evaluate the effect of the factor. Results: M2 macrophages significantly increased the proliferation, migration, and invasion of ATC cells, whereas M1 macrophages decreased the proliferation, migration, and invasion of ATC cells. Based on proteomic analysis of CM, we identify carboxypeptidase A4 (CPA4) as a mediator of the crosstalk between macrophages and ATC cells. CPA4 was only detected in the coculture media of M2 macrophage/8505C, and its expression in cancer cells increased by M2 macrophage. The expression of CPA4 protein was significantly higher in human thyroid cancers, particularly in ATCs, than normal and benign tissues. A bioinformatics analysis of public data revealed that CPA4 expression was associated with poor prognosis and dedifferentiation of thyroid cancer. Knockdown of CPA4 suppressed proliferation, colony formation, migration, and invasion of ATC cells, consistent with the decrease of STAT3, ERK, and AKT/mTOR phosphorylation and epithelial-mesenchymal transition (EMT) marker expression. In addition, the increased expression of CPA4 in cancer cells by M2 macrophage stimulation induced the polarization of macrophages to the M2 phenotype, which formed a positive feedback loop. Xenograft tumors did not develop after CPA4 knockdown. Conclusions: Our data suggest that CPA4 stimulates the progression of thyroid cancer by mediating between M2 macrophages and ATC cells. CPA4 can be a new therapeutic target for the treatment of patients with ATC.

CPA4 as a biomarker promotes the proliferation, migration and metastasis of clear cell renal cell carcinoma cells

Clear cell renal cell carcinoma (ccRCC) is a commonly occurring and highly aggressive urological malignancy characterized by a significant mortality rate. Current therapeutic options for advanced ccRCC are limited, necessitating the discovery of novel biomarkers and therapeutic targets. Carboxypeptidase A4 (CPA4) is a zinc-containing metallocarboxypeptidase with implications in various cancer types, but its role in ccRCC remains unexplored. The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) databases were utilized in order to investigate the differential expression patterns of CPA4. The expression of CPA4 in ccRCC patients was further verified using immunohistochemical (IHC) examination of 24 clinical specimens. A network of protein-protein interactions (PPI) was established, incorporating CPA4 and its genes that were expressed differentially. Functional enrichment analyses were conducted to anticipate the contribution of CPA4 in the development of ccRCC. To validate our earlier study, we conducted real-time PCR and cell functional tests on ccRCC cell lines. Our findings revealed that CPA4 is overexpressed in ccRCC, and the higher the expression of CPA4, the worse the clinical outcomes such as TNM stage, pathological stage, histological grade, etc. Moreover, patients with high CPA4 expression had worse overall survival, disease-specific survival and progress-free interval than patients with low expression. The PPI network analysis highlighted potential interactions contributing to ccRCC progression. Functional enrichment analysis indicated the involvement of CPA4 in the regulation of key pathways associated with ccRCC development. Additionally, immune infiltration analysis suggested a potential link between CPA4 expression and immune response in the tumour microenvironment. Finally, cell functional studies in ccRCC cell lines shed light on the molecular mechanisms underlying the role of CPA4 in promoting ccRCC formation. Overall, our study unveils CPA4 as a promising biomarker with prognostic potential in ccRCC. The identified interactions and pathways provide valuable insights into its implications in ccRCC development and offer a foundation for future research on targeted therapies. Further investigation of CPA4's involvement in immune responses may contribute to the development of immunotherapeutic strategies for ccRCC treatment.

Angiopoietin-1 promotes triple-negative breast cancer cell proliferation by upregulating carboxypeptidase A4

Angiopoietin-1 (ANG1) is a pro-angiogenic regulator that contributes to the progression of solid tumors by stimulating the proliferation, migration and tube formation of vascular endothelial cells, as well as the renewal and stability of blood vessels. However, the functions and mechanisms of ANG1 in triple-negative breast cancer (TNBC) are unclear. The clinical sample database shows that a higher level of ANG1 in TNBC is associated with poor prognosis compared to non-TNBC. In addition, knockdown of ANG1 inhibits TNBC cell proliferation and induces cell cycle G1 phase arrest and apoptosis. Overexpression of ANG1 promotes tumor growth in nude mice. Mechanistically, ANG1 promotes TNBC by upregulating carboxypeptidase A4 (CPA4) expression. Overall, the ANG1-CPA4 axis can be a therapeutic target for TNBC.

Knockdown of carboxypeptidase A4 (CPA4) inhibits gastric cancer cell progression via cell cycle arrest and apoptosis

Background

Gastric cancer is one of the most prevalent cancers, with a low survival rate at the later stages. Carboxypeptidase A4 (CPA4) is associated with the aggressiveness and growth in cancer. However, its regulatory role in gastric cancer remains unknown. Therefore, we investigated the role of CPA4 in gastric cancer progression in vitro.

Methods

The human gastric adenocarcinoma cell line (AGS cell line) was used in the present study. CPA4 knockdown lentiviruses were constructed. Western blot analysis was performed to evaluate the protein expression levels of epithelial-mesenchymal transition (EMT) transcription factors, EMT biomarkers, and proteins involved in the Wnt signaling pathway, mitogen-activated protein kinase (MAPK) signaling pathway, and phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis was carried out to evaluate the mRNA expression level of CPA4. The String database was employed for protein-protein interaction (PPI) network analysis. Cell colony formation, proliferation, migration, invasion, apoptosis, and cell cycle analyses were performed using corresponding kits.

Results

CPA4 is highly expressed in gastric cancer cell lines. Overexpressed CPA4 was associated with the induction of EMT. Knockdown of CPA4 inhibited cell colony formation, proliferation, migration, and invasion of gastric cancer cells. Knockdown of CPA4 also promoted cell apoptosis of gastric cancer cells.

Conclusions

Knockdown of CPA4 inhibited cell progression via arresting the cell cycle and inducing EMT in gastric cancer.

Special Issue on Bioinformatics and Machine Learning for Cancer Biology

Cancer is a leading cause of death worldwide, claiming millions of lives each year [...]