MEMD/ALCAM: A Potential Marker for Tumor Invasion and Nodal Metastasis in Esophageal Squamous Cell Carcinoma

Soluble adhesion molecules in human cancers: sources and fates

Adhesion molecules endow tumor cells with the necessary cell-cell contacts and cell-matrix interactions. As such, adhesion molecules are involved in cell signalling, proliferation and tumor growth. Rearrangements in the adhesion repertoire allow tumor cells to migrate, invade and form metastases. Besides these membrane-bound adhesion molecules several soluble adhesion molecules are detected in the supernatant of tumor cell lines and patient body fluids. Truncated soluble adhesion molecules can be generated by several conventional mechanisms, including alternative splicing of mRNA transcripts, chromosomal translocation, and extracellular proteolytic ectodomain shedding. Secretion of vesicles (ectosomes and exosomes) is an alternative mechanism mediating the release of full-length adhesion molecules. Soluble adhesion molecules function as modulators of cell adhesion, induce proteolytic activity and facilitate cell signalling. Additionally, adhesion molecules present on secreted vesicles might be involved in the vesicle-target cell interaction. Based on currently available data, released soluble adhesion molecules contribute to cancer progression and therefore should not be regarded as unrelated and non-functional side products of tumor progression.

Increased expression of ALCAM/CD166 in pancreatic cancer is an independent prognostic marker for poor survival and early tumour relapse

Background:

ALCAM (activated leucocyte cell adhesion molecule, synonym CD166) is a cell adhesion molecule, which belongs to the Ig superfamily. Disruption of the ALCAM-mediated adhesiveness by proteolytic sheddases such as ADAM17 has been suggested to have a relevant impact on tumour invasion. Although the expression of ALCAM is a valuable prognostic and predictive marker in several types of epithelial tumours, its role as a prognostic marker in pancreatic cancer has not yet been reported.

Methods:

In this study, paraffin-embedded samples of 97 patients with pancreatic cancer undergoing potentially curative resection were immunostained against ALCAM, ADAM17 and CK19. Expression of ALCAM and ADAM17 was semiquantitatively evaluated and correlated to clinical and histopathological parameters.

Results:

We could show that in normal pancreatic tissue, ALCAM is predominantly expressed at the cellular membrane, whereas in pancreatic tumour cells, it is mainly localised in the cytoplasm. In addition, univariate and multivariate analyses show that increased expression of ALCAM is an adverse prognostic factor for recurrence-free and overall survival. Overexpression of ADAM17 in pancreatic cancer, however, failed to be a significant prognostic marker and was not coexpressed with ALCAM.

Conclusions:

Our findings support the hypothesis that the disruption of ALCAM-mediated adhesiveness is a relevant step in pancreatic cancer progression. Moreover, ALCAM overexpression is a relevant independent prognostic marker for poor survival and early tumour relapse in pancreatic cancer.

[Expression of activated leukocyte cell adhesion molecule in breast cancer. Predictability of the response to taxane-free chemotherapy]

AIMS

Activated leukocyte cell adhesion molecule (ALCAM) is a cell surface immunoglobulin expressed in breast cancer (BC) and is assumed to be implicated in tumourigenesis and tumour progression. The importance of the adhesion molecule ALCAM for the response to taxane-free adjuvant chemotherapy was investigated.

MATERIALS AND METHODS

Tissue specimens from 162 primary breast cancer patients were analyzed. Immunohistochemical staining (IHC) and Western blots (WB) were performed using monoclonal antibody against ALCAM. Relative protein amounts in WB bands were determined densitometrically. ALCAM mRNA expression was evaluated by microarray analysis (Affymetrix).

RESULTS

In the normal breast ALCAM is expressed in luminal and basal epithelial cells. In BC samples, WB analysis showed a significant positive correlation of ALCAM levels with estrogen receptor status (p=0.04). For patients who received a taxane-free chemotherapy, a high ALCAM expression was predictive for a good response to chemotherapy. Median mRNA expression of ALCAM was 4.5-fold higher in patients alive at the time of follow-up compared to those who died of breast cancer.

CONCLUSIONS

Higher ALCAM expression showed a positive correlation with estrogen receptor status and is a useful predictive marker for the response to taxane-free chemotherapy.

Cytoplasmic accumulation of activated leukocyte cell adhesion molecule is a predictor of disease progression and reduced survival in oral cancer patients

Activated leukocyte cell adhesion molecule (ALCAM) has been proposed to function as a cell surface sensor for cell density, controlling the transition between local cell proliferation and tissue invasion in cancer progression. Herein, we determined ALCAM expression in 107 oral squamous cell carcinomas (OSCCs), 78 oral lesions (58 hyperplasias and 20 dysplasias) and 30 histologically normal oral tissues using immunohistochemistry and correlated with clinicopathological parameters. Significant increase in ALCAM immunopositivity was observed from normal oral mucosa, hyperplasia, dysplasia to OSCCs (p(trend) < 0.001). Increased ALCAM expression was observed in cytoplasm of epithelial cells as early as in hyperplasia (p = 0.001, OR = 3.8). Sixty-five of 107 (61%) OSCCs showed significant overexpression of ALCAM protein in cytoplasm/membrane of tumor cells (p = 0.043; OR = 3.3) in comparison with the normal oral tissues. Among OSCCs, cytoplasmic ALCAM was associated with advanced tumor size, tumor stage and tobacco consumption. Importantly, cytoplasmic ALCAM was an independent predictor of poor prognosis of OSCCs in multivariate analysis (p = 0.012, OR = 6.2). In an attempt to understand the molecular basis of cytoplasmic localization of ALCAM, 14-3-3 zeta and 14-3-3 sigma were identified as its novel binding partners in oral cancer cells. In conclusion, increased expression of ALCAM is an early event in oral tumorigenesis; its cytoplasmic accumulation in tumor cells is a predictor of poor prognosis of OSCCs, underscoring its potential as a candidate prognostic marker for oral cancer.

Attenuation of melanoma invasion by a secreted variant of activated leukocyte cell adhesion molecule

Activated leukocyte cell adhesion molecule (ALCAM/CD166/MEMD), a marker of various cancers and mesenchymal stem cells, is involved in melanoma metastasis. We have exploited a secreted NH(2)-terminal fragment, sALCAM, to test the hypothesis that ALCAM coordinates tissue growth and cell migration. Overexpression of sALCAM in metastatic melanoma cells disturbed clustering of endogenous ALCAM and inhibited activation of matrix metalloproteinase-2 (MMP-2). Exposure of HT1080 fibrosarcoma cells to sALCAM similarly inhibited MMP-2, suggesting a broader effect on ALCAM-positive tumor cells. In contrast to the previously reported, promotive effects of an NH(2)-terminally truncated, transmembrane variant (DeltaN-ALCAM), sALCAM impaired the migratory capacity of transfected cells in vitro, reduced basement membrane penetration in reconstituted human skin equivalents, and diminished metastatic capacity in nude mice. Remarkably, L1 neuronal cell adhesion molecule (L1CAM/CD171), another progression marker of several cancers including melanoma, was suppressed upon sALCAM overexpression but was up-regulated by DeltaN-ALCAM. The partially overlapping and opposite effects induced by alternative strategies targeting ALCAM functions collectively attribute an integrative role to ALCAM in orchestrating cell adhesion, growth, invasion, and proteolysis in the tumor tissue microenvironment and disclose a therapeutic potential for sALCAM.

Protein alterations in ESCC and clinical implications: a review

Esophageal squamous cell carcinoma (ESCC) is the predominant histological subtype of esophageal cancer in Asia, characterized by high incidence and mortality rate. Although significant progress has been made in surgery and adjuvant chemoradiotherapy, the prognosis of the patients with this cancer still remains poor. Investigation into protein alterations that occurred in tumors can provide clues to discover new biomarkers for improving diagnosis and guiding targeted therapy. Hundreds of papers have appeared over the past several decades concerning protein alterations in ESCC. This review summarizes all the dysregulated proteins investigated in the disease from 187 published papers and analyzes their contributions to tumor development and progression. We document protein alterations associated with tumor metastasis and the transition from normal esophageal epithelia to dysplasia in order to reveal the most useful markers for prediction of clinical outcome, early detection, and identification of high-risk patients for targeted therapies. In particular, we discuss the largest and most rigorous studies on prognostic implications of proteins in ESCC, in which cyclin D1, p53, E-cadherin and VEGF appeared to have the strongest evidence as independent predictors of patient outcome.

Activated leukocyte cell adhesion molecule: a new paradox in cancer

The activated leukocyte cell adhesion molecule [ALCAM/CD166/melanoma metastasis clone D (MEMD)] is an immunoglobulin superfamily cell adhesion molecule. It is expressed developmentally in cells of all 3 embryonic lineages. The ALCAM expression is limited to subsets of cells in most adult tissues. ALCAM is localized at intercellular junctions in epithelium presumably as part of the adhesive complex that maintains tissue architecture. Over the past decade, alterations in expression of ALCAM have been reported in several human tumors (melanoma, prostate cancer, breast cancer, colorectal carcinoma, bladder cancer, and esophageal squamous cell carcinoma). This review summarizes the current knowledge of the role of ALCAM in malignancies.

Predictive impact of activated leukocyte cell adhesion molecule (ALCAM/CD166) in breast cancer

Activated Leukocyte Cell Adhesion Molecule (ALCAM, also called CD 166, MEMD) as cell surface immunoglobulin is reported as prognostic marker in breast cancer, but its predictive value has not yet been evaluated. We have analyzed ALCAM protein expression by Western Blot analysis (n = 160) and mRNA expression by cDNA microarray analysis (n = 162) in primary mammary carcinomas. Both expression results were obtained in 133 cases, showing a strong positive correlation between protein expression and mRNA expression (P < 0.001). Neither ALCAM protein nor mRNA expression are correlated to histological type, grading, stage or age of patient. However, ALCAM protein expression correlates positively with estrogen receptor status (ER) (P = 0.025). A stratified subgroup analysis showed positive correlation of high ALCAM mRNA expression with longer overall survival (OAS; P = 0.0012) in patients treated with adjuvant chemotherapy (n = 100). In contrast, patients with high ALCAM mRNA expression who did not receive chemotherapy tended to have a worse prognosis. Similar but weaker correlations were found regarding ALCAM protein expression data. The predictive impact of ALCAM mRNA expression in chemotherapy treated patients was corroborated by multivariate Cox regression analysis also including histopathological markers (P = 0.001 for OAS). Our overall results reveal that high ALCAM expression levels in primary tumors might be a suitable marker for prediction of the response to adjuvant chemotherapy in breast cancer.

Isolation of cardiac cells from E8.5 yolk sac by ALCAM (CD166) expression

It is known that the adhesion molecule ALCAM (CD166) mediates metastasis of malignant cells and organogenesis in embryos. We show here that embryonic day 8.5 (E8.5) murine yolk sac cells express ALCAM protein and that ALCAM expression can be used to define endothelial and cardiac precursors from hematopoietic precursors in E8.5 yolk sacs. ALCAM high+ cells exclusively give rise to endothelial and cardiac cells in matrigel assays but generate no hematopoietic colonies in methylcellulose assays. ALCAM low+ and ALCAM- populations predominantly give rise to hematopoietic cells in methylcellulose, but do not generate any cell clusters in matrigel. The ALCAM high+ population contains both Flk-1+ and Flk-1- cells. The former population exclusively contains endothelial cells whereas the latter give rise to cardiac cells when cultured on OP9 stromal cells. We also show that cardiac lineage marker genes such as Nkx-2.5, and the endothelial marker VE-cadherin are expressed in the ALCAM high+ fraction, whereas the hematopoietic marker GATA1 and Runx1 are expressed in the ALCAM low+/- fraction. However, we did not detect expression of the cardiac structural protein cTn-T in cells from yolk sac cells until these had had been differentiated on OP9 for 5 days. Altogether, these results indicate that cells retaining a potential to differentiate to the cardiac lineage are present in E8.5 yolk sacs and can be isolated as ALCAM high+, Flk-1- cells. Our report provides novel insights into the origin and differentiation process of cardiac cells in the formation of the circulatory system.

Novel molecular targets of smokeless tobacco (khaini) in cell culture from oral hyperplasia

Knowledge of molecular mechanism(s) implicated in smokeless tobacco (ST) associated oral carcinogenesis is meager. In an attempt to identify genes that are modulated by ST, we recently reported establishment of an oral epithelial cell culture, AMOL III from oral hyperplasia with hyperkeratosis of a khaini consumer. Herein we aimed to identify novel molecular targets of ST (khaini) in AMOL III cells using differential display. Fourteen novel differentially expressed genes (12 upregulated and 2 downregulated) were identified. These differentially expressed cDNAs were amplified, cloned, sequenced and confirmed by reverse northern blotting. Mainly these genes are components of transcriptional machinery, cell-cell adhesion, signaling, growth and transformation processes. The important novel molecular targets identified included activated leucocyte cell adhesion molecule (ALCAM), CDP-diacylglycerol-inositol 3-phosphatidyl transferase (phosphatidylinositol synthase), CDIPT, an important enzyme in phosphatidyl inositol biosynthesis, ribosomal protein (RPS23), KIAA0121 and growth and transformation factor, E2IG5. Semi-quantitative RT-PCR analysis of these five genes confirmed over-expression of these genes in oral pre-malignant lesions (OPLs) and oral squamous cell carcinomas (OSCCs) of ST consumers underscoring their biological relevance in ST-associated oral tumorigenesis. In depth studies are warranted to determine the functional significance of ALCAM and CDIPT in oral carcinogenesis.

Cytoplasmic overexpression of ALCAM is prognostic of disease progression in breast cancer

BACKGROUND

Activated leucocyte cell adhesion molecule (ALCAM, CD166) is a cell surface member of the immunoglobulin superfamily. ALCAM expression has prognostic relevance in prostate and colon cancer.

OBJECTIVE

To evaluate ALCAM protein expression in breast cancer by immunohistochemistry and to correlate expression levels with clinicopathological data.

METHODS

162 primary breast carcinomas with a mean clinical follow up time of 53 months were immunostained using a monoclonal ALCAM antibody. The staining was evaluated as an immunoreactive score (IRS) and grouped into low v high for both membranous and cytoplasmic staining.

RESULTS

Intraductal and invasive carcinomas showed a higher ALCAM expression (median IRS 4 and 6 respectively) than normal breast tissue (IRS 2). In univariate survival analyses a significant association of high cytoplasmic ALCAM expression with shortened patient disease-free survival (mean (SD) five year non-progression rate, 69.4 (4.6)% v 49.4 (11.1)%, p = 0.0142) was found. In multivariate analyses of disease-free survival times, high cytoplasmic ALCAM expression (relative risk (RR) = 2.086, p = 0.026) and nodal status (RR = 2.246, p = 0.035) were significantly associated with earlier disease progression, whereas tumour grading (RR = 1.6, p = 0.052) was of borderline significance.

CONCLUSIONS

The data suggest that strong cytoplasmic ALCAM expression in primary breast cancer, as detected by immunohistochemistry, might be a new marker for a more aggressive breast cancer biology.

ALCAM (CD166) Is a Surface Marker for Early Murine Cardiomyocytes

ALCAM (activated leukocyte cell adhesion molecule, CD166) belongs to the immunoglobulin superfamily and is involved in axon guidance, hematopoiesis, immune response and tumor metastasis. During embryogenesis, mRNA encoding ALCAM was expressed in the cardiac crescent and the neural groove at embryonic day (E) 7.75 and predominately in the tubular heart at E8.5. A newly generated monoclonal antibody against the ALCAM molecule (ALC-48) exclusively stained cardiomyocytes at E8.25-10.5. However, ALCAM expression was lost by cardiomyocytes by E12.5 and its expression shifts to a variety of organs during later stages. ALCAM was found to be a prominent surface marker for cardiomyocytes in early embryonic hearts. The transient expression of ALCAM during early developmental stages marks specific developmental stages in cardiomyocyte differentiation.