Carcinoembryonic antigen-related cell adhesion molecules as surrogate markers for EGFR inhibitor sensitivity in human lung adenocarcinoma

CEACAM6 serves as a biomarker for leptomeningeal metastasis in lung adenocarcinoma

BACKGROUND AND AIMS

Diagnosis of leptomeningeal metastasis (LM) is challenging. In our previous study, CEACAM6 mRNA was found to be highly expressed in the circulating tumor cells of cerebrospinal fluid (CSF) from patients with lung adenocarcinoma with LM (LUAD-LM). The aim of this study was to identify whether CEACAM6 could be used as a biomarker for LUAD-LM.

MATERIALS AND METHODS

The level of CEACAM6 was determined by enzyme-linked immunosorbent assay (ELISA) in CSF from 40 LUAD-LM and 44 normal controls, and additional serum samples from 138 LUAD patients, including 12 LUAD-LM patients, and 30 healthy controls. Carcinoembryonic antigen (CEA), cytokeratin 19 fragment (CYFRA 21-1) and neuron-specific enolase (NSE) levels in the CSF and sera were detected by chemiluminescent immunoassay. Receiver operating characteristic curve was plotted to evaluate the diagnostic performance for LUAD-LM.

RESULTS

CSF CEACAM6 level was higher in LUAD-LM than that in normal controls. In serum, LUAD patients had a higher level of CAECAM6 than healthy controls, and LM patients had the highest level among them. Serum CEACAM6 had a higher AUC than CEA in differentiating LM from non-LM in LUAD patients (0.95 vs. 0.64, p < 0.001).

CONCLUSION

CEACAM6 may serve as a potential biomarker in diagnosing LUAD-LM.

CEACAMS 1, 5, and 6 in disease and cancer: interactions with pathogens

The CEA family comprises 18 genes and 11 pseudogenes located at chromosome 19q13.2 and is divided into two main groups: cell surface anchored CEA-related cell adhesion molecules (CEACAMs) and the secreted pregnancy-specific glycoproteins (PSGs). CEACAMs are highly glycosylated cell surface anchored, intracellular, and intercellular signaling molecules with diverse functions, from cell differentiation and transformation to modulating immune responses associated with infection, inflammation, and cancer. In this review, we explore current knowledge surrounding CEACAM1, CEACAM5, and CEACAM6, highlight their pathological significance in the areas of cancer biology, immunology, and inflammatory disease, and describe the utility of murine models in exploring questions related to these proteins.

LINC02126 is a potential diagnostic, prognostic and immunotherapeutic target for lung adenocarcinoma

Background

Adenocarcinoma has long been an independent histological class of lung cancer, which leads to high morbidity and mortality. We aimed to investigate the contribution of LINC02126 in lung adenocarcinoma.

Methods

RNA sequencing data and clinical information were downloaded. Diagnostic efficiency and survival analysis of LINC02126 were performed, followed by functional analysis of genes co-expressed with LINC02126 and differentially expressed genes (DEGs) in different LINC02126 expression groups. Tumor immune microenvironment (TIME) cell infiltration and correlation analysis of tumor mutation burden were performed in different LINC02126 expression groups.

Results

In lung adenocarcinoma, the expression level of LINC02126 was significantly decreased. Significant expression differences of LINC02126 were found in some clinical variables, including T staging, M staging, sex, stage, and EGFR mutation. LINC02126 had potential diagnostic and prognostic value for patients. In the low LINC02126 expression group, the infiltration degree of most immune cells was significantly lower than that in the high LINC02126 expression group. Tumor mutation burden level and frequency of somatic mutation in patients with low LINC02126 expression group were significantly higher than in patients with high LINC02126 expression group.

Conclusions

LINC02126 could be considered as a diagnostic, prognostic and immunotherapeutic target for lung adenocarcinoma.

Prognostic value of the immune target CEACAM6 in cancer: a meta-analysis

Background:

Identification of membrane proteins differentially expressed on tumor cells is a key step in drug development. The carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) is a cell adhesion protein belonging to the immunoglobulin superfamily. Here, we explore the prognostic role CEACAM6 expression on patient outcome in cancer.

Methods:

A systematic search for studies evaluating the association between tumor expression of CEACAM6 and overall survival (OS) and disease-free survival (DFS) was performed. Hazard ratios (HR) were pooled in a meta-analysis using generic inverse variance and random effect modeling. Subgroup analyses were conducted based on tumor type and method of HR extraction.

Results:

Sixteen studies met the inclusion criteria. CEACAM6 expression was associated with worse OS [HR = 1.96, 95% confidence interval (CI) = 1.51–2.53], and DFS (HR = 2.49, 95% CI = 2.01–3.07) with subgroup analysis showing no significant differences between disease site subgroups.

Conclusions:

High expression of CEACAM6 is associated with worse OS and DFS in different malignancies. CEACAM6 is a target for the future development of novel therapeutics.

CEACAM6 promotes cholangiocarcinoma migration and invasion by inducing epithelial-mesenchymal transition through inhibition of the SRC/PI3K/AKT signaling pathway

The immunoglobulin superfamily member carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) is overexpressed in a wide variety of human cancer types, and is associated with tumor invasion and migration. The aim of the present study was to determine the role of CEACAM6 in cholangiocarcinoma (CCA) invasion and migration in vitro. The results showed that CEACAM6 was highly expressed in CCA tissues, and that the expression level of CEACAM6 was negatively associated with the degree of differentiation of CCA. Silencing CEACAM6 inhibited cell viability, invasion and migration but promoted cell apoptosis in a human CCA cell line (RBE). In addition, CEACAM6 knockdown decreased the expression of an antiapoptotic protein (Bcl-2), an interstitial cell marker (N-cadherin), extracellular matrix proteins (MMP-2 and MMP-9), a transcription factor helix protein (Twist-related protein 1), an intermediate tumor cell scaffold marker (vimentin), a protein involved in tumor nutrient vascular formation (VEGFA) and a tumorigenesis factor (intercellular cell adhesion molecule-1), but increased the expression of pro-apoptotic proteins (Bax, and cleaved caspases-3, -8 and -9) and an epithelial cell marker protein (E-cadherin). Furthermore, CEACAM6-small interfering RNA reduced the expression of the SRC/PI3K/AKT signaling transduction pathway. Taken together, these results suggested that CEACAM6 may be an epithelial-mesenchymal transition biomarker and a potential therapeutic target in human CCA.

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.

Identification and expression analysis of novel splice variants of the human carcinoembryonic antigen-related cell adhesion molecule 19 (CEACAM19) gene using a high-throughput sequencing approach

Alternative splicing is commonly involved in carcinogenesis, being highly implicated in differential expression of cancer-related genes. Recent studies have shown that the human CEACAM19 gene is overexpressed in malignant breast and ovarian tumors, possessing significant biomarker attributes. In the present study, 3' rapid amplification of cDNA ends (3' RACE) and next-generation sequencing (NGS) were used for the detection and identification of novel CEACAM19 transcripts. Bioinformatical analysis of our NGS data revealed novel splice junctions between previously annotated exons and ultimately new exons. Next, fifteen novel CEACAM19 transcripts were identified with Sanger sequencing. Additionally, their expression profile was investigated in a wide panel of human cell lines, using nested PCR with variant-specific primers. The broad expression pattern of the CEACAM19 gene, along with the fact that its overexpression has previously been associated with ovarian and breast cancer progression, indicate the potential of novel CEACAM19 transcripts as putative diagnostic and/or prognostic biomarkers.

Affinity chromatography assisted comprehensive phosphoproteomics analysis of human saliva for lung cancer

Affinity chromatography is a powerful technology for phosphopeptide enrichment from body fluids. Saliva is a non-invasive body fluid for disease diagnosis, while few studies applied affinity enrichment for saliva phosphoproteome. In this study, we tested two kinds of affinity chromatography materials, Ti⁴⁺-IMAC (immobilized metal affinity chromatography) and CaTiO₃, for the enrichment of phosphopeptides. Through comparison, Ti⁴⁺-IMAC method was demonstrated as the superior one, which was utilized for the comprehensive analysis of salivary phosphoproteome. More than 360 phosphoproteins were specifically extracted and identified from human saliva. Ti⁴⁺-IMAC method was further applied to compare the phosphoprotein profiling in the saliva of lung cancer group and normal control group through label-free quantification. Accordingly, 477 and 699 phosphopeptides were enriched, respectively, which corresponded to 339 and 466 proteins. In total, 796 unique phosphopeptides were revealed for 517 saliva phosphoproteins. In particular, 709 phosphorylation sites were identified, among which 26 were up-regulated (>1.5) and 149 were down-regulated (<0.66) in lung cancer. Their corresponding proteins were mainly associated with cancer promotion, system disorder, and organismal injury. Our data collectively demonstrated that salivary phosphopeptides can be comprehensively characterized through Ti⁴⁺-IMAC method. These discovered phosphoprotein candidates might be used for lung cancer detection through salivary diagnostics.

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.

Gene coexpression analysis offers important modules and pathway of human lung adenocarcinomas

Lung adenocarcinomas injured greatly on the people worldwide. Although clinic experiments and gene profiling analyses had been well performed, to our knowledge, systemic coexpression analysis of human genes for this cancer is still limited to date. Here, using the published data GSE75037, we built the coexpression modules of genes by Weighted Gene Co-Expression Network Analysis (WGCNA), and investigated function and protein-protein interaction network of coexpression genes by Database for Annotation, visualization, and Integrated Discovery (DAVID) and String database, respectively. First, 11 coexpression modules were conducted for 5,000 genes in the 83 samples recently. Number of genes for each module ranged from 90 to 1,260, with the mean of 454. Second, interaction relationships of hub-genes between pairwise modules showed great differences, suggesting relatively high scale independence of the modules. Third, functional enrichment of the coexpression modules showed great differences. We found that genes in modules 8 significantly enriched in the biological process and/or pathways of cell adhesion, extracellular matrix (ECM)-receptor interaction, focal adhesion, and PI3K-Akt signaling pathway, and so forth. It was inferred as the key module underlying lung adenocarcinomas. Furthermore, PPI analysis revealed that the genes COL1A1, COL1A2, COL3A1, CTGF, and BGN owned the largest number of adjacency genes, unveiling that they may functioned importantly during the occurrence of lung adenocarcinomas. To summary, genes involved in cell adhesion, ECM-receptor interaction, focal adhesion, and PI3K-Akt signaling pathway play crucial roles in human lung adenocarcinomas.

Anterior Gradient 2 is Correlated with EGFR Mutation in Lung Adenocarcinoma Tissues

Background

Epidermal growth factor receptor (EGFR)–tyrosine kinase inhibitor (TKI) has demonstrated a promising therapeutic response in lung adenocarcinoma patients with EGFR gene mutations. However, the predictive factors for this therapy have not been established, except for the EGFR gene mutation status of carcinoma cells.

Methods

We first performed microarray analysis in EGFR-TKI–sensitive lung adenocarcinoma cell lines. The results indicated anterior gradient 2 (AGR2) as a potential surrogate marker of EGFR-TKI. Therefore, we then evaluated the correlation between the status of AGR2 immunoreactivity and clinicopathological factors including overall survival (OS), progression-free survival (PFS) and clinical response to EGFR-TKI, in 147 cases of surgically resected lung adenocarcinoma. The biological significance of AGR2 was further evaluated by transfecting small interfering RNA (siRNA) against AGR2 in these cells.

Results

The status of AGR2 immunoreactivity was significantly higher in lung adenocarcinoma cases with EGFR gene mutations than in those with the wild type (p<0.0001), but there were no significant differences in OS, PFS and response of EGFR-TKI between the AGR2 high and low carcinoma cases. Knockdown of AGR2 gene expression following siRNA transfection resulted in a significantly lower response to EGFR-TKI in EGFR-mutated PC-3.

Conclusions

AGR2 could serve as an adjunctive surrogate protein marker possibly reflecting EGFR gene mutations in lung adenocarcinoma patients. Results from in vitro analysis indicated that AGR2 could be a potential clinical biomarker of EGFR-TKI therapeutic sensitivity in lung adenocarcinoma cells.

Carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) promotes EGF receptor signaling of oral squamous cell carcinoma metastasis via the complex N-glycosylation

Aberrant protein glycosylation could be a distinct surface-marker of cancer cells that influences cancer progression and metastasis because glycosylation can regulate membrane protein folding which alters receptor activation and changes epitope exposure for antibody (Ab) recognition. Carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6), a glycophosphoinositol-anchored protein, is a heavily glycosylated tumor antigen. However, the clinical significance and biological effect of CEACAM6 glycosylation has not been addressed in cancers. We recently developed an anti-CEACAM6 Ab (TMU) from an immune llama library which can be engineered to a single-domain (sd)Ab or a heavy-chain (HC)Ab. The TMU HCAb specifically recognized glycosylated CEACAM6 compared to the conventional antibodies. Using the TMU HCAb, we found that glycosylated CEACAM6 was a tumor marker associated with recurrence in early-stage OSCC (oral squamous cell carcinoma) patients. CEACAM6 promoted OSCC cell invasion, migration, cytoskeletal rearrangement, and metastasis via interaction with epidermal growth factor (EGF) receptor (EGFR) and enhancing EGFR activation, clustering and intracellular signaling cascades. These functions were modulated by N-acetylglucosaminyltransferase 5 (MGAT5) which mediated N-glycosylation at Asn²⁵⁶ (N256) of CEACAM6. Finally, the TMU sdAb and HCAb treatment inhibited the migration, invasion and EGF-induced signaling in CEACAM6-overexpressing cells. In conclusion, the complex N-glycosylation of CEACAM6 is critical for EGFR signaling of OSCC invasion and metastasis. Targeting glycosylated CEACAM6 with the TMU sdAb or TMU HCAb could be a feasible therapy for OSCC.

High expression of CEACAM19, a new member of carcinoembryonic antigen gene family, in patients with breast cancer

Carcinoembryonic antigen (CEA) family members play important roles in malignancies and are introduced as biomarkers in different types of cancers. Among them CEACAM19 (CEAL1) gene, a new member of the CEA family, remains to be fully elucidated. The aim of this study was investigating the mRNA expression level of CEACAM19 in tumor samples of breast cancer patients compared to breast tissue of normal individuals. We evaluated the expression level of this gene in 75 breast tumors by using real-time quantitative PCR. Also, we studied the correlation between CEACAM19 expression and clinicopathological features and hormone receptors status, including estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 of patients. Out of the enrolled patients, six of them (7.9%) showed low expression, ten (13.2%) showed normal expression and 59 (77.6%) showed high expression of CEACAM19. There was a significant correlation between high expression of CEACAM19 gene in tumor samples compared to normal tissues (P = 0.039). No significant correlation was seen between clinicopathological factors and disease-free survival with mRNA levels of CEACAM19 in tumor samples, while the difference between the expression of CEACAM19 in ER/PR-positive and ER/PR-negative breast cancer patients was statistically significant (P = 0.046). In conclusion, CEACAM19 showed high expression in tumor samples compared to normal mammary tissue. In addition, CEACAM19 may represent as a novel therapeutic target in certain subgroups of breast cancer patients such as ER/PR-negative. Critical roles of CEA proteins in tumor progression may nominate them as robust potential targets for therapeutic intervention in near future.

FOXP3 and CEACAM6 expression and T cell infiltration in the occurrence and development of colon cancer

The transcription factor forkhead box P3 (FOXP3) is involved in immune cell regulation, and carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) is an adhesion molecule of the immunoglobulin superfamily. These two genes are associated with cancer progression. In the current study, colon tissue specimens from 78 cases of colon cancer (including 40 of stage I-II and 38 of stage III-IV), 30 cases of colonic adenoma and 12 healthy controls were collected from the First Affiliated Hospital of Soochow University between January 2010 and December 2011. The expression of cluster of differentiation (CD) 3, CD4, CD8, CD45RO, CEACAM6 and FOXP3 in colon tissues was examined by immunohistochemical analysis. In addition, a reverse transcription-quantitative polymerase chain reaction (RT-qPCR) assay, based on SYBR Green I, was used to detect CD3, CD4, CD8, CD45RO, CEACAM6 and FOXP3 mRNA levels in the paraffin block specimens. CD3⁺, CD8⁺ and CD45RO⁺ T cell infiltrations in colonic adenoma were significantly higher than in normal colonic mucosa (P<0.001, P=0.001 and P<0.001, respectively). However, CD3⁺, CD8⁺ and CD45RO⁺ lymphocytes in stage III-IV colon cancer tissues were lower than in normal control tissues (P=0.015, P=0.002 and P=0.041, respectively); consistently, CD3⁺, CD4⁺, CD8⁺ and CD45RO⁺ lymphocytes in stage III-IV tissues were even more markedly lower compared with adenoma (P=0.001, P<0.001, P<0.001 and P<0.001, respectively). Similarly, CD3⁺, CD8⁺ and CD45RO⁺ T cell infiltration was lower in stage I-II cancer tissues compared with adenoma (P=0.001, P<0.001 and P<0.001). CD3⁺, CD4⁺, CD8⁺ and CD45RO⁺ T cell infiltrations were also significantly higher in stage I-II compared with stage III-IV cancer tissues (P<0.001, P=0.045, P<0.001 and P<0.001, respectively). CEACAM6 was found to gradually increase from normal colon tissue to adenoma and cancer tissue. FOXP3 was expressed more highly in stage I-II compared with normal tissues (P=0.014), and was even higher in stage III-IV (P<0.001). These results were verified using RT-qPCR, which yielded almost identical results. In summary, the current study demonstrates that FOXP3, CEACAM6 and T cell infiltration are significantly associated with the occurrence and progression of colon cancer, and that immune reactions vary between different stages of colon cancer development.

Expression of human carcinoembryonic antigen-related cell adhesion molecule 6 and alveolar progenitor cells in normal and injured lungs of transgenic mice

Carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) is expressed in the epithelium of various primate tissues, including lung airway and alveoli. In human lung, CEACAM6 is developmentally and hormonally regulated, protects surfactant function, has anti-apoptotic activity and is dysregulated in cancers. We hypothesized that alveolar CEACAM6 expression increases in lung injury and promotes cell proliferation during repair. Studies were performed in CEABAC transgenic mice-containing human CEACAM genes. The level of CEACAM6 in adult CEABAC lung was comparable to that in human infants; expression occurred in epithelium of airways and of some alveoli but rarely co-localized with markers of type I or type II cells. Ten days after bleomycin instillation, both the number of CEACAM6(+) cells and immunostaining intensity were elevated in injured lung areas, and there was increased co-localization with type I and II cell markers. To specifically address type II cells, we crossed CEABAC mice with animals expressing EGFP driven by the SP-C promoter. After bleomycin injury, partially flattened, elongated epithelial cells were observed that expressed type I cell markers and were primarily either EGFP(+) or CEACAM6(+). In cell cycle studies, mitosis was greater in CEACAM6(+) non-type II cells versus CEACAM6(+)/EGFP(+) cells. CEACAM6 epithelial expression was also increased after hyperoxic exposure and LPS instillation, suggesting a generalized response to acute lung injuries. We conclude that CEACAM6 expression is comparable in human lung and the CEABAC mouse. CEACAM6 in this model appears to be a marker of a progenitor cell population that contributes to alveolar epithelial cell replenishment after lung injury.

Emerging Role and Targeting of Carcinoembryonic Antigen-related Cell Adhesion Molecule 6 (CEACAM6) in Human Malignancies

Background: Carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) is a member of the CEA family of cell adhesion proteins that belong to the immunoglobulin superfamily. CEACAM6 is normally expressed on the surface of myeloid (CD66c) and epithelial surfaces. Stiochiomertic expression of members of the CEA family (CEACAM1, 5, 6, 7) on epithelia maintains normal tissue architecture through homo-and hetero-philic interactions. Dysregulated over-expression of CEACAM6 is oncogenic, is associated with anoikis resistance and an invasive phenotype mediated by excessive TGFβ, AKT, FAK and SRC signaling in human malignancies. Methods: Extensive literature review through PubMed was conducted to identify relevant preclinical and clinical research publications regarding CEACAM6 over the last decade and was summarized in this manuscript. Results: CEACAM5 and 6 are over-expressed in nearly 70% of epithelial malignancies including colorectal cancer (CRC), pancreatic ductal adenocarcinoma (PDA), hepatobiliary, gastric, breast, non-small cell lung and head/neck cancers. Importantly, CEACAM6 is a poor prognostic marker in CRC, while its expression correlates with tumor stage, metastasis and post-operative survival in PDA. CEACAM6 appears to be an immune checkpoint suppressor in hematologic malignancies including acute lymphoblastic leukemia and multiple myeloma. Several therapeutic monoclonal antibodies or antibody fragments targeting CEACAM6 have been designed and developed as a targeted therapy for human malignancies. A Llama antibody targeting CEACAM6 is being evaluated in early phase clinical trials. Conclusion: This review focuses on the role of CEACAM6 in the pathogenesis and signaling of the malignant phenotype in solid and hematologic malignancies and highlights its potential as a therapeutic target for anti-cancer therapy.

A549 cells adapted to high nitric oxide show reduced surface CEACAM expression and altered adhesion and migration properties

The migration and adhesion properties of tumors affect their metastatic rate. In the present study, we investigated carcinoembryonic antigen-related cell adhesion molecule (CEACAM) 1, 5, and 6 expression in high nitric oxide (HNO)-adapted lung cancer cells compared to parent cells. We observed high transcript levels of CEACAM 1 (4S, 4L), CEACAM 5, and CEACAM 6 in HNO cells compared to parent cells. However, the surface expression was low in HNO cells. Interestingly, the intracellular protein levels were high for these three CEACAMs. We confirmed these results with immunohistochemical experiments. Further, the adhesion and migration assays showed reduced clumping in HNO-adapted A549 (A549-HNO) cells and faster migration rates, respectively. These results document the altered adhesion and migration properties of cells adapted to HNO. Further, our studies also indicate a dynamic regulation of CEACAM protein expression and surface transport in HNO cells.

CEACAM6 promotes tumor migration, invasion, and metastasis in gastric cancer

Carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) shows increased expression in a wide variety of human cancers, and its over-expression is associated with enhanced migration, invasion, and in vivo metastasis. Here, we reported that CEACAM6 was up-regulated in gastric cancer (GC) cell lines and tumor tissues. Over-expression of CEACAM6 in MKN-45 and SGC-7901 GC cells promoted migration and invasion in vitro and metastasis in athymic mice, whereas migration and invasion of MKN-28 and SNU-16 GC cells were suppressed by knockdown of CEACAM6. We also observed that steroid receptor coactivator (C-SRC) phosphorylation was increased when CEACAM6 was over-expressed in SGC-7901 cells. Taken together, these results suggested that CEACAM6 functions as an oncoprotein in GC and may be an important metastatic biomarker and therapeutic target.