Dual role of carcinoembryonic antigen-related cell adhesion molecule 6 expression in predicting the overall survival of gastric cancer patients

Characteristics of Carcinoembryonic Antigen-Related Cell Adhesion Molecules and Their Relationship to Cancer

Carcinoembryonic antigen-related cell adhesion molecules (CEACAM), such as carcinoembryonic antigen (CEA) and the oncofetal glycoprotein family, are tumor markers. The CEACAMs consist of 12 different human CEACAMs and 5 different murine CEACAMs. The CEACAM family of proteins participates in multiple biological processes that include the immune response, angiogenesis, and cancer. CEACAMs play a significant role in cancer initiation and development. Increasing evidence suggests that family members may be new cancer biomarkers and targets in that CEACEAMs tend to be aberrantly expressed and therefore may have potential diagnostic and therapeutic importance. This review systematically summarizes the biogenesis, biological properties, and functions of CEACAMs, with a focus on their relationship with cancer and potential clinical application. As our knowledge of the relationships among CEACAMs and cancer increases, and as our understanding of the involved molecular mechanisms improves, new therapeutic strategies will evolve for cancer prevention and treatment of patients with cancer.

CEACAM6 expression and function in tumor biology: a comprehensive review

Carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) is an immunoglobulin superfamily protein primarily expressed on epithelial surfaces and myeloid cells. It plays a significant role in cancer progression by inhibiting apoptosis, promoting drug resistance, and facilitating cancer cell invasion and metastasis. Overexpression of CEACAM6 has been observed in various cancers, including lung, breast, colorectal, and hepatocellular cancers, and is associated with poorer overall survival and disease-free survival. Its differential expression on tumor cell surfaces makes it a promising cancer marker. This review aims to provide a comprehensive summary of CEACAM6's role in different cancer types, its involvement in signaling pathways, and recent advancements in CEACAM6-targeted treatments.

MicroRNA 29a therapy for CEACAM6-expressing lung adenocarcinoma

BACKGROUND

Non-coding microRNAs (miRNAs) play critical roles in tumor progression and hold great promise as therapeutic agents for multiple cancers. MicroRNA 29a (miR-29a) is a tumor suppressor miRNA that inhibits cancer cell growth and tumor progression in non-small cell lung cancer. Carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6), which plays an important role in lung cancer progression, has been identified as a target of miR-29a. Here, we evaluated the therapeutic efficacy of a peptide vector capable of delivering miR-29a intracellularly using the acidic tumor microenvironment in a lung adenocarcinoma xenograft mouse model.

METHODS

A miRNA delivery vector was constructed by tethering the peptide nucleic acid form of miR-29a to a peptide with a low pH-induced transmembrane structure (pHLIP) to enable transport of the miRNAs across the plasma membrane. Tumor suppressive effects of pHLIP-miR29a on lung adenocarcinoma development in vivo were assessed using a BALB/c xenograft model injected with A549 cells.

RESULTS

Incubation of A549 cells with pHLIP-miR-29a at an acidic pH downregulated endogenous CEACAM6 expression and reduced cell viability. Intravenous injection of the mice with pHLIP-miR-29a inhibited tumor growth by up to 18.1%. Intraperitoneal injection of cisplatin reduced tumor volume by 29.9%. Combined pHLIP-miR-29a + cisplatin treatment had an additive effect, reducing tumor volume up to 39.7%.

CONCLUSIONS

Delivery of miR-29a to lung adenocarcinoma cells using a pHLIP-mediated method has therapeutic potential as a unique cancer treatment approach.

T cell-mediated elimination of cancer cells by blocking CEACAM6–CEACAM1 interaction

Carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6), a cell surface receptor, is expressed on normal epithelial tissue and highly expressed in cancers of high unmet medical need, such as non-small cell lung, pancreatic, and colorectal cancer. CEACAM receptors undergo homo- and heterophilic interactions thereby regulating normal tissue homeostasis and angiogenesis, and in cancer, tumor invasion and metastasis. CEACAM6 expression on malignant plasma cells inhibits antitumor activity of T cells, and we hypothesize a similar function on epithelial cancer cells.

The interactions between CEACAM6 and its suggested partner CEACAM1 on T cells were studied. A humanized CEACAM6-blocking antibody, BAY 1834942, was developed and characterized for its immunomodulating effects in co-culture experiments with T cells and solid cancer cells and in comparison to antibodies targeting the immune checkpoints programmed cell death protein 1 (PD-1), programmed death-ligand 1 (PD-L1), and T cell immunoglobulin mucin-3 (TIM-3).

The immunosuppressive activity of CEACAM6 was mediated by binding to CEACAM1 expressed by activated tumor-specific T cells. BAY 1834942 increased cytokine secretion by T cells and T cell-mediated killing of cancer cells. The in vitro efficacy of BAY 1834942 correlated with the degree of CEACAM6 expression on cancer cells, suggesting potential in guiding patient selection. BAY 1834942 was equally or more efficacious compared to blockade of PD-L1, and at least an additive efficacy was observed in combination with anti-PD-1 or anti-TIM-3 antibodies, suggesting an efficacy independent of the PD-1/PD-L1 axis.

In summary, CEACAM6 blockade by BAY 1834942 reactivates the antitumor response of T cells. This warrants clinical evaluation.

CEACAM6 promotes cisplatin resistance in lung adenocarcinoma and is regulated by microRNA-146a and microRNA-26a

Background

Carcinoembryonic antigen (CEA)‐related cell adhesion molecule 6 (CEACAM6) is a glycophosphoinositol‐anchored glycoprotein which mediates cell‐cell interactions. Here, we aimed to explore the specific functions and regulatory mechanisms of CEACAM6 on cisplatin (DDP) in lung adenocarcinoma (LUAD).

Methods

RNA sequencing was performed in the DDP‐resistant A549/DDP cell line and parental A549 cell line; miRNA expression profiling of the two cell lines was analyzed using GEO data (GSE43249). Gain‐ and loss‐of‐function experiments were used to investigate the biological function of CEACAM6 in vitro. The expression status and prognostic value of CEACAM6 in LUAD were verified using The Cancer Genome Atlas (TCGA) database.

Results

CEACAM6 was first screened to be one of the most significantly upregulated genes in the DDP‐resistant A549/DDP cell line compared to the parental A549 cell line. Combined with computational prediction of candidate miRNAs that target CEACAM6, miR‐146a and miR‐26a were selected and verified by qPCR and luciferase reporter assay. The knockdown of CEACAM6 expression in A549/DDP cells inhibited cell proliferation, invasion and migration, decreased the IC₅₀ values of DDP, and caused a significant downregulation of N‐cadherin, vimentin, Sox2, Oct4 and GTP‐RhoA and upregulation of E‐cadherin; while CEACAM6 overexpression in A549 cells resulted in the opposite effects. Of note, both miR‐146a and miR‐26a could counteract the biological effects of CEACAM6. Furthermore, CEACAM6 mRNA expression was significantly unregulated in DDP‐resistant LUAD tissues of TCGA database.

Conclusions

CEACAM6 promotes DDP resistance in LUAD by affecting the epithelial‐mesenchymal transition (EMT) phenotype and stemness, which is post‐transcriptionally regulated by miR‐146a and miR‐26a.

Therapeutic Effect of pHLIP-mediated CEACAM6 Gene Silencing in Lung Adenocarcinoma

Carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) plays an important role in lung cancer progression. Here, we examined the therapeutic efficacy of CEACAM6 gene silencing using an siRNA delivery platform targeting the acidic tumour microenvironment in a lung adenocarcinoma xenograft mouse model. An siRNA delivery vector was constructed by tethering the peptide nucleic acid form of an siRNA targeting CEACAM6 (siCEACAM6) to a peptide with a low pH-induced transmembrane structure (pHLIP) to transport siRNAs across the plasma membrane. Specific binding of the pHLIP-siCEACAM6 conjugate to A549 lung adenocarcinoma cells at low pH was demonstrated by flow cytometry. A549 cells incubated with pHLIP-siCEACAM6 at an acidic pH showed downregulated expression of endogenous CEACAM6 protein and reduced cell viability. The in vivo tumour-suppressing effects of pHLIP-siCEACAM6 in lung adenocarcinoma were assessed in a xenograft model generated by injecting BALB/c nude mice with A549 cells. pHLIP-siCEACAM6 treatment alone resulted in tumour growth inhibition of up to 35.5%. When combined with cisplatin treatment, pHLIP-siCEACAM6 markedly enhanced tumour growth inhibition by up to 47%. In conclusion, the delivery of siCEACAM6 to lung adenocarcinoma using the pHLIP peptide has therapeutic potential as a unique cancer treatment approach.

Levels of CEACAM6 in Peripheral Blood Are Elevated in Patients with Plasma Cell Disorders: A Potential New Diagnostic Marker and a New Therapeutic Target?

INTRODUCTION

The prognosis of multiple myeloma is still unfavorable due to inherent characteristics of the disease and the often-delayed diagnosis due to widespread and unspecific symptoms such as back pain and fatigue. Therefore, a simple diagnostic blood test would be helpful to speed up the diagnostic procedure in such patients (pts.). Here, we evaluated the diagnostic value of plasma levels of carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) in the peripheral blood and bone marrow of pts. with plasma cell disorders and in healthy controls.

MATERIALS AND METHODS

Immunoreactive CEACAM6 was determined in the peripheral blood and bone marrow (n = 95/100) of pts. with monoclonal gammopathy of unknown significance (MGUS: 28/37), newly diagnosed multiple myeloma (NDMM: 42/40), and relapsed/refractory multiple myeloma (RRMM: 25/23) by sandwich ELISA.

RESULTS

Median CEACAM6 levels in the peripheral blood of pts. with plasma cell disorders were significantly higher than those of healthy controls (healthy controls: 15.2 pg/ml (12.1-17.1); MGUS: 19.0 pg/ml (16.4-22.5); NDMM: 18.0 pg/ml (13.4-21.2); and RRMM: 18.9 pg/ml (15.2-21.5); p < 0.001). Plasma levels of CEACAM6 discriminated healthy subjects from MGUS/NDMM pts. (AUC = 0.71, 95% CI: 0.6-0.8); i.e., a CEACAM6 level > 17.3 pg/ml has an 82% (95% CI: 70-90) predictive probability for the identification of MGUS or NDMM. Moreover, CEACAM6 levels in the bone marrow were significantly higher in RRMM pts. than in NDMM pts. (p = 0.04), suggesting a role of this molecule in disease progression.

CONCLUSION

CEACAM6 plasma levels can noninvasively identify pts. with a plasma cell disorder and should be evaluated prospectively as a potential diagnostic marker. Moreover, due to high CEACAM6 levels in the bone marrow in RRMM pts., this adhesion molecule might be a therapeutic target in multiple myeloma pts.