INCREASED EXPRESSION OF MUC18 CORRELATES WITH THE METASTATIC PROGRESSION OF MOUSE PROSTATE ADENOCARCINOMA IN THE TRAMP MODEL

METCAM Is a Potential Biomarker for Predicting the Malignant Propensity of and as a Therapeutic Target for Prostate Cancer

Prostate cancer is the second leading cause of cancer-related death worldwide. This is because it is still unknown why indolent prostate cancer becomes an aggressive one, though many risk factors for this type of cancer have been suggested. Currently, many diagnostic markers have been suggested for predicting malignant prostatic carcinoma cancer; however, only a few, such as PSA (prostate-specific antigen), Prostate Health Index (PHI), and PCA3, have been approved by the FDA. However, each biomarker has its merits as well as shortcomings. The serum PSA test is incapable of differentiating prostate cancer from BPH and also has an about 25% false-positive prediction rate for the malignant status of cancer. The PHI test has the potential to replace the PSA test for the discrimination of BPH from prostate cancer and for the prediction of high-grade cancer avoiding unnecessary biopsies; however, the free form of PSA is unstable and expensive. PCA3 is not associated with locally advanced disease and is limited in terms of its prediction of aggressive cancer. Currently, several urine biomarkers have shown high potential in terms of being used to replace circulating biomarkers, which require a more invasive method of sample collection, such as via serum. Currently, the combined multiple tumor biomarkers may turn out to be a major trend in the diagnosis and assessment of the treatment effectiveness of prostate cancer. Thus, there is still a need to search for more novel biomarkers to develop a perfect cocktail, which consists of multiple biomarkers, in order to predict malignant prostate cancer and follow the efficacy of the treatment. We have discovered that METCAM, a cell adhesion molecule in the Ig-like superfamily, has great potential regarding its use as a biomarker for differentiating prostate cancer from BPH, predicting the malignant propensity of prostate cancer at the early premalignant stage, and differentiating indolent prostate cancers from aggressive cancers. Since METCAM has also been shown to be able to initiate the spread of prostate cancer cell lines to multiple organs, we suggest that it may be used as a therapeutic target for the clinical treatment of patients with malignant prostate cancer.

METCAM/MUC18 Plays a Tumor Suppressor Role in the Development of Nasopharyngeal Carcinoma Type I

From previous studies of negatively correlating the expression of human METCAM/MUC18 with the pathology of nasopharyngeal carcinoma (NPC), we have suggested that human METCAM/MUC18 (huMETCAM/MUC18) might play a tumor suppressor role in the development of nasopharyngeal carcinoma. To scrutinize this hypothesis, we investigated the effects of huMETCAM/MUC18′s over-expression on in vitro cellular behavior and on the in vivo tumorigenesis of one NPC cell line (NPC-TW01). HuMETCAM/MUC18 cDNA was first transfected into the NPC-TW01 cell line, which was established from NPC type I, and many G418-resistant clones were obtained. Then, two NPC-TW01 clones, which expressed high and medium levels of huMETCAM/MUC18, respectively, and one empty vector (control) clone were used to test the effects of huMETCAM/MUC18′s over-expression on in vitro behaviors and on in vivo tumorigenesis (via subcutaneous injection) in athymic nude mice (Balb/cAnN.Cg-Foxnl^nu/Cr1Nar1). The time course of tumor proliferation and the final tumor weights were determined. Tumor sections were used for the histology and immunohistochemistry (IHC) studies. Tumor lysates were used for determining the expression levels of huMETCAM/MUC18 and various downstream key effectors. HuMETCAM/MUC18′s over-expression reduced in vitro motility and invasiveness and altered growth behaviors in 3D basement membrane culture assays, and it decreased the in vivo tumorigenicity of the NPC-TW01 cells. The tumor cells from a high-expressing clone were clustered and confined in small areas, whereas those from a vector control clone were more spread out, suggesting that the tumor cells from the high-expressing clone appeared to stay dormant in micro-clusters. Expression levels of the proliferation index, an index of the metabolic switch to aerobic glycolysis, angiogenesis indexes, and survival pathway indexes were reduced, whereas the pro-apoptosis index increased in the corresponding tumors. The over-expression of huMETCAM/MUC18 in the NPC-TW01 cells decreased the epithelial-to-mesenchymal transition and the in vitro and in vitro tumorigenesis, suggesting that it plays a tumor suppressor role in the development of type I NPC, perhaps by increasing apoptosis and decreasing angiogenesis, proliferation, and the metabolic switch to aerobic glycolysis.

Soluble CD146 as a Potential Target for Preventing Triple Negative Breast Cancer MDA-MB-231 Cell Growth and Dissemination

Background: Triple Negative Breast Cancers (TNBC) are the most aggressive breast cancers and lead to poor prognoses. This is due to a high resistance to therapies, mainly because of the presence of Cancer Stem Cells (CSCs). Plasticity, a feature of CSCs, is acquired through the Epithelial to Mesenchymal Transition (EMT), a process that has been recently shown to be regulated by a key molecule, CD146. Of interest, CD146 is over-expressed in TNBC. Methods: The MDA-MB-231 TNBC cell line was used as a model to study the role of CD146 and its secreted soluble form (sCD146) in the development and dissemination of TNBC using in vitro and in vivo studies. Results: High expression of CD146 in a majority of MDA-MB-231 cells leads to an increased secretion of sCD146 that up-regulates the expression of EMT and CSC markers on the cells. These effects can be blocked with a specific anti-sCD146 antibody, M2J-1 mAb. M2J-1 mAb was able to reduce tumour development and dissemination in a model of cells xenografted in nude mice and an experimental model of metastasis, respectively, in part through its effects on CSC. Conclusion: We propose that M2J-1 mAb could be used as an additional therapeutic approach to fight TNBC.

Validating METCAM/MUC18 as a Novel Biomarker to Predict the Malignant Potential of Prostate Cancer at an Early Stage by Using a Modified Gold Nanoparticles-Based Lateral Flow Immunoassay

(1) Background: To further validate METCAM/MUC18 as a diagnostic biomarker for prostate cancer, a modified Lateral Flow Immune Assay (LFIA) with increased sensitivity and specificity was designed by taking advantage of the extremely high affinity between biotin and streptavidin and used. (2) Methods: The combination of a commercial biotinylated rabbit antibody (EPP11278), or the home-made biotinylated chicken antibody, and the nano-gold conjugated home-made chicken antibody or a commercial rabbit antibody (EPP11278), had the higher sensitivity and specificity in this modified LFIA to establish calibration curves from the two recombinant METCAM/MUC18 proteins and were used for determining METCAM/MUC18 concentrations in serum specimens from normal individuals, benign prostatic hyperplasia (BPH) patients, prostatic intraepithelial neoplasia (PIN) patients, prostate cancer patients with various Gleason scores, and treated patients. (3) Results: Data obtained by this modified LFIA were statistically better than traditional LFIA and prostate-specific antigen (PSA) test. Interestingly, serum METCAM/MUC18 concentrations were higher in pre-malignant PIN patients than prostate cancer patients and both were higher than normal individuals, BPH patients, and treated patients. Serum METCAM/MUC18 concentrations were directly proportional to most serum PSA. (4) Conclusions: Elevated serum METCAM/MUC18 concentrations may be used for predicting the malignant potential of prostate cancer at an early premalignant (PIN) stage, which is not achievable by the current PSA test.

METCAM/MUC18 is a new early diagnostic biomarker for the malignant potential of prostate cancer: Validation with Western blot method, enzyme-linked immunosorbent assay and lateral flow immunoassay

BACKGROUND

METCAM/MUC18 expression was increased with the malignant progression of prostate cancer and also a bona fide metastatic gene, capable of initiating and driving the metastasis of a non-metastatic human prostate cancer cell line to multiple organs.

OBJECTIVE

We explored if METCAM/MUC18 was detectable in human serum and a novel biomarker to predict malignant propensity of prostate cancer.

MATERIALS AND METHODS

Two antibodies were identified by Western blot analysis having the highest sensitivity and specificity to establish calibration curves from the recombinant METCAM/MUC18 proteins. They were used in ELISA and LFIA to determine the METCAM/MUC18 concentrations in serum samples from 8 normal individuals, 4 BPH patients, 1 with PIN, 6 with high-grade prostate cancer, and 2 treated cancer patients.

RESULTS

Serum METCAM/MUC18 concentrations were statistically significantly higher in the patients with PIN and prostate cancer than those with BPH, the treated patients and normal individuals. The LFIA results were statistically better than ELISA and Western blot methods. Serum METCAM/MUC18 concentrations were in direct proportional to most of serum PSA concentrations.

Therapeutic targeting of soluble CD146/MCAM with the M2J-1 monoclonal antibody prevents metastasis development and procoagulant activity in CD146-positive invasive tumors

Initially discovered in human melanoma, CD146/MCAM is expressed on many tumors and is correlated with cancer progression and metastasis. However, targeting CD146 remains challenging since it is also expressed on other cell types, as vessel cells, where it displays important physiological functions. We previously demonstrated that CD146 is shed as a soluble form (sCD146) that vectorizes the effects of membrane CD146 on tumor angiogenesis, growth and survival. We thus generated a novel monoclonal antibody, the M2J-1 mAb, which specifically targets sCD146, but not membrane CD146, and counteracts these effects. In our study, we analyzed the effects of sCD146 on the dissemination and the associated procoagulant phenotype in two highly invasive human CD146-positive cancer cell lines (ovarian and melanoma). Results show that sCD146 induced epithelial to mesenchymal transition, favored the generation of cancer stem cells and increased the membrane expression of tissue factor. Treatment of cancer cells with sCD146 in two experimental models (subcutaneous xenografting and intracardiac injection of cancer cells in nude mice) led to increased tumor dissemination and procoagulant activity. The M2J-1 mAb drastically reduced metastasis but also procoagulant activity, in particular by decreasing the number of circulating tumor microparticles, and blocked the relevant signaling pathways as demonstrated by RNA expression profiling experiments. Thus, our findings demonstrate that sCD146 mediates important pro-metastatic and procoagulant effects in two CD146-positive tumors. Targeting sCD146 with the newly generated M2J-1 mAb could constitute an innovative strategy for preventing dissemination and thromboembolism in many CD146-positive tumors.

CD146 (Cluster of Differentiation 146)

CD146 (cluster of differentiation 146) is an adhesion molecule that is expressed by different cells constituting vessels, particularly endothelial cells. The last 30 years of research in this field have shown that CD146 plays a key role in the control of several vessel functions. Three forms of CD146 have been described, including 2 transmembrane isoforms and a soluble protein that is detectable in the plasma. These CD146 forms mediate pleiotropic functions through homophilic and heterophilic interactions with proteins present on surrounding partners. Several studies used neutralizing antibodies, siRNA, or genetically modified mice to demonstrate the involvement of CD146 in the regulation of angiogenesis, vascular permeability, and leukocyte transmigration. In this review, we will focus on the current knowledge of the roles of CD146 in vascular homeostasis and diseases associated with endothelial dysfunction.

The Prevalence of CD146 Expression in Breast Cancer Subtypes and Its Relation to Outcome

CD146, involved in epithelial-to-mesenchymal transition (EMT), might affect cancer aggressiveness. We here investigated the prevalence of CD146 expression in breast cancer subtypes, its relation to prognosis, the relation between CD146 and EMT and the outcome to tamoxifen. Primary breast cancer tissues from 1342 patients were available for this retrospective study and immunohistochemically stained for CD146. For survival analyses, pure prognosis was studied by only including lymph-node negative patients who did not receive (neo)adjuvant systemic treatment (n = 551). 11% of the tumors showed CD146 expression. CD146 expression was most prevalent in triple-negative cases (64%, p < 0.001). In univariable analysis, CD146 expression was a prognostic factor for both metastasis-free survival (MFS) (p = 0.020) and overall survival (OS) (p = 0.037), but not in multivariable analysis (including age, tumor size, grade, estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2) and Ki-67). No correlation between CD146 and EMT nor difference in outcome to first-line tamoxifen was seen. In this large series, our data showed that CD146 is present in primary breast cancer and is a pure prognostic factor for MFS and OS in breast cancer patients. We did not see an association between CD146 expression and EMT nor on outcome to tamoxifen.

A novel anti-CD146 antibody specifically targets cancer cells by internalizing the molecule

CD146 is an adhesion molecule present on many tumors (melanoma, kidney, pancreas, breast, ...). In addition, it has been shown to be expressed on vascular endothelial and smooth muscle cells. Generating an antibody able to specifically recognize CD146 in cancer cells (designated as tumor CD146), but not in normal cells, would thus be of major interest for targeting tumor CD146 without affecting the vascular system.

We thus generated antibodies against the extracellular domain of the molecule produced in cancer cells and selected an antibody that specifically recognizes tumor CD146. This antibody (TsCD146 mAb) was able to detect CD146-positive tumors in human biopsies and in vivo, by PET imaging, in a murine xenograft model. In addition, TsCD146 mAb antibody was able to specifically detect CD146-positive cancer microparticles in the plasma of patients. TsCD146 mAb displayed also therapeutic effects since it was able to reduce the growth of human CD146-positive cancer cells xenografted in nude mice. This effect was due to a decrease in the proliferation and an increase in the apoptosis of CD146-positive cancer cells after TsCD146-mediated internalization of the cell surface CD146.

Thus, TsCD146 mAb could be of major interest for diagnostic and therapeutic strategies against CD146-positive tumors in a context of personalized medicine.

CD146, a novel target of CD44-signaling, suppresses breast tumor cell invasion

Background

We have previously validated three novel CD44-downstream positively regulated transcriptional targets, including Cortactin, Survivin and TGF-β2, and further characterized the players underlying their separate signaling pathways. In the present study, we identified CD146 as a potential novel target, negatively regulated by CD44. While the exact function of CD146 in breast cancer (BC) is not completely understood, substantial evidence from our work and others support the hypothesis that CD146 is a suppressor of breast tumor progression.

Methods

Therefore, using molecular and pharmacological approaches both in vitro and in breast tissues of human samples, the present study validated CD146 as a novel target of CD44-signaling suppressed during BC progression.

Results

Our results revealed that CD44 activation could cause a substantial decrease of CD146 expression with an equally notable converse effect upon CD44-siRNA inhibition. More interestingly, activation of CD44 decreased cellular CD146 and increased soluble CD146 through CD44-dependent activation of MMP.

Conclusion

Here, we provide a possible mechanism by which CD146 suppresses BC progression as a target of CD44-downstream signaling, regulating neovascularization and cancer cell motility.

Immunohistochemical Expression of MCAM/CD146 in Canine Melanoma

MCAM/CD146 (melanoma cell adhesion molecule/CD146) is a transmembrane immunoglobulin superfamily cell adhesion molecule involved in transendothelial migration and signal transduction. It is expressed in melanoma, squamous cell carcinoma, prostatic, ovarian, cervical and endometrial cancers and promotes tumour growth, angiogenesis and metastasis. Melanoma is the most common malignant oral tumour of dogs and also arises in the skin, nail bed and footpad. The aim of this study was to investigate the immunohistochemical expression of MCAM/CD146 in 51 canine melanomas, including oral, cutaneous and ocular tumours. Seventeen of the 51 (33.3%) cases were negative, eight (15.7%) were weakly positive, seven (13.7%) were moderately positive and 19 (37.3%) were strongly positive. MCAM/CD146 was expressed by both oral and cutaneous melanomas; however, the intensity and the extent of the immunoreactivity was higher in oral (P = 0.009) than in cutaneous tumours (P = 0.058). Most ocular melanomas did not express MCAM/CD146 (P = 0.256). Expression of MCAM/CD146 by canine melanomas may suggest the molecule as a target for treatment, especially in oral melanomas.

Significance of expression of human METCAM/MUC18 in nasopharyngeal carcinomas and metastatic lesions

Human METCAM/MUC18, a cell adhesion molecule (CAM) in the immunoglobulin-like gene super family, plays a dual role in the progression of several epithelium cancers; however, its role in the nasopharyngeal carcinoma (NPC) remains unclear. To initiate the study we determined human METCAM/MUC18 expression in tissue samples of normal nasopharynx (NP), NPCs, and metastatic lesions, and in two established NPC cell lines. Immunoblotting analysis was used for the determination in lysates of frozen tissues, and immunohistochemistry (IHC) for expression in formalin-fixed, paraffin-embedded tissue sections of 7 normal nasopharynx specimens, 94 NPC tissue specimens, and 3 metastatic lesions. Human METCAM/MUC18 was expressed in 100% of the normal NP, not expressed in 73% of NPC specimens (or expressed at very low levels in only about 27% of NPC specimens), and expressed again in all of the metastatic lesions. The level of human METCAM/MUC18 expression in NPC tissues was about one fifth of that in the normal NP and metastatic lesions. The low level of human METCAM/ MUC18 expression in NPC specimens was confirmed by a weak signal of RT-PCR amplification of the mRNA. Low expression levels of human METCAM/MUC18 in NPC tissues were also reflected in the seven established NPC cell lines. These findings provided the first evidence that diminished expression of human METCAM/MUC18 is an indicator for the emergence of NPC, but increased expression then occurs with metastatic progression, suggesting that huMETCAM/MUC18, perhaps similar to TGF-β, may be a tumor suppressor, but a metastasis promoter for NPC.

CD146, a multi-functional molecule beyond adhesion

CD146 is a cell adhesion molecule (CAM) that is primarily expressed at the intercellular junction of endothelial cells. CD146 was originally identified as a tumor marker for melanoma (MCAM) due to its existence only in melanoma but not in the corresponding normal counterpart. However CD146 is not just a CAM for the inter-cellular and cell-matrix adhesion. Recent evidence indicates that CD146 is actively involved in miscellaneous processes, such as development, signaling transduction, cell migration, mesenchymal stem cells differentiation, angiogenesis and immune response. CD146 has increasingly become an important molecule, especially identified as a novel bio-marker for angiogenesis and for cancer. Here we have reviewed the dynamic research of CD146, particularly newly identified functions and the underlying mechanisms of CD146.

CD146 expression in human breast cancer cell lines induces phenotypic and functional changes observed in Epithelial to Mesenchymal Transition

BACKGROUND

Metastasis is an important step in tumor progression leading to a disseminated and often incurable disease. First steps of metastasis include down-regulation of cell adhesion molecules, alteration of cell polarity and reorganization of cytoskeleton, modifications associated with enhanced migratory properties and resistance of tumor cells to anoikis. Such modifications resemble Epithelial to Mesenchymal Transition (EMT). In breast cancer CD146 expression is associated with poor prognosis and enhanced motility.

METHODOLOGY/PRINCIPAL FINDINGS

On 4 different human breast cancer cell lines, we modified CD146 expression either with shRNA technology in CD146 positive cells or with stable transfection of CD146 in negative cells. Modifications in morphology, growth and migration were evaluated. Using Q-RT-PCR, we analyzed the expression of different EMT markers. We demonstrate that high levels of CD146 are associated with loss of cell-cell contacts, expression of EMT markers, increased cell motility and increased resistance to doxorubicin or docetaxel. Experimental modulation of CD146 expression induces changes consistent with the above described characteristics: morphology, motility, growth in anchorage independent conditions and Slug mRNA variations are strictly correlated with CD146 expression. These changes are associated with modifications of ER (estrogen receptor) and Erb receptors and are enhanced by simultaneous and opposite modulation of JAM-A, or exposure to heregulin, an erb-B4 ligand.

CONCLUSIONS

CD146 expression is associated with an EMT phenotype. Several molecules are affected by CD146 expression: direct or indirect signaling contributes to EMT by increasing Slug expression. CD146 may also interact with Erb signaling by modifying cell surface expression of ErbB3 and ErbB4 and increased resistance to chemotherapy. Antagonistic effects of JAM-A, a tight junction-associated protein, on CD146 promigratory effects underline the complexity of the adhesion molecules network in tumor cell migration and metastasis.

CD146 gene expression in clear cell renal cell carcinoma: a potential marker for prediction of early recurrence after nephrectomy

OBJECTIVES

To investigate whether CD146 gene expression could provide useful information to predict early recurrence after nephrectomy.

METHODS

This study included 84 patients with clear cell renal cell carcinoma (cRCC), and 44 subjects without tumor were used as controls. Quantitative RT-PCR was used to measure the CD146 gene expression.

RESULTS

The mean value of CD146 expression in patients with metastatic cRCC (0.0438±0.0024) was significantly higher than in those with localized cRCC (0.0374±0.0012, P=0.018) or in controls (0.0344±0.0010, P=0.001). Of patients with localized cRCC, those with recurrence had a significantly higher CD146 expression than those without recurrence (P=0.029). The univariate analysis showed that CD146 was associated with early recurrence. The recurrence-free survival curve indicated that patients with a high CD146 expression had a significantly higher recurrence rate than those with a low CD146 expression (P=0.018).

CONCLUSIONS

CD146 gene expression can be useful for predicting early recurrence and stratifying the patients into risk groups for possible adjuvant treatment.

CD146 expression correlates with epithelial-mesenchymal transition markers and a poor prognosis in gastric cancer

CD146 has been regarded as a novel potential therapeutic target for multiple cancers. The aim of the study was to investigate the expression of CD146 in gastric cancer and evaluate its clinical-pathological and prognostic significance. The expression of CD146 and three epithelial-mesenchymal transition (EMT)-related proteins (E-cadherin, β-catenin and vimentin) was examined in 144 gastric cancers by immunohistochemistry. Fifty-nine cases (41.0%) were defined as positive for CD146 expression. We found that CD146 expression correlated positively with lymph node involvement and a poor prognosis, and retained an independent prognostic factor for gastric cancer patients. Furthermore, positive expression of CD146 was strongly associated with loss of the epithelial marker E-cadherin and acquisition of the expression of the mesenchymal markers nuclear β-catenin and vimentin. These findings suggest that CD146 might promote EMT and progression in gastric cancer, and thus may be a potential therapeutic target for patients with gastric cancers.

Dual Roles of METCAM in the Progression of Different Cancers

METCAM, an integral membrane cell adhesion molecule (CAM) in the Ig-like gene superfamily, is capable of performing typical functions of CAMs, such as mediating cell-cell and cell-extracellular interactions, crosstalk with intracellular signaling pathways, and modulating social behaviors of cells. METCAM is expressed in about nine normal cells/tissues. Aberrant expression of METCAM has been associated with the progression of several epithelial tumors. Further in vitro and in vivo studies show that METCAM plays a dual role in the progression of different tumors. It can promote the malignant progression of several tumors. On the other hand, it can suppress the malignant progression of other tumors. We suggest that the role of METCAM in the progression of different cancer types may be modulated by different intrinsic factors present in different cancer cells and also in different stromal microenvironment. Many possible mechanisms mediated by this CAM during early tumor development and metastasis are suggested.

Alterations of protein profile in zebrafish liver cells exposed to methyl parathion: a membrane proteomics approach

Methyl parathion (MP) is an extensively used organophosphorus pesticide, which has been associated with a wide spectrum of toxic effects on environmental organisms. The aim of this study is to investigate the alterations of membrane protein profiles in zebrafish liver (ZFL) cell line exposed to MP for 24 h using proteomic approaches. Two-dimensional gel electrophoresis revealed a total of 13 protein spots, whose expression levels were significantly altered by MP. These differential proteins were subjected to matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry analysis, and nine proteins were identified to be membrane proteins, among which seven were up-regulated, while two were down-regulated. In addition, the mRNA levels corresponding to these differential membrane proteins were further analyzed by quantitative real-time PCR. And the differential expression of arginase-2 was specially validated via Western blotting. Regarding the physiological functions, these proteins are involved in molecular chaperon, cytoskeleton system, cell metabolism, signal transduction, transport and hormone receptor respectively, suggesting the complexity of MP-mediated toxicity to ZFL cell. These data could provide useful insights for better understanding the hepatotoxic mechanisms of MP and develop novel protein biomarkers for effectively monitoring MP contamination level in aquatic environment.

Cell surface glycoproteomic analysis of prostate cancer-derived PC-3 cells

Most clinically approved biomarkers of cancer are glycoproteins, and those residing on the cell surface are of particular interest in biotherapeutics. We report a method for selective labeling, affinity enrichment, and identification of cell-surface glycoproteins. PC-3 cells and primary human prostate cancer tissue were treated with peracetylated N-azidoacetylgalactosamine, resulting in metabolic labeling of cell surface glycans with the azidosugar. We used mass spectrometry to identify over 70 cell surface glycoproteins and biochemically validated CD146 and integrin beta-4, both of which are known to promote metastatic behavior. These results establish cell-surface glycoproteomics as an effective technique for discovery of cancer biomarkers.

Cytochrome P450 17 (CYP17) is involved in endometrial cancinogenesis through apoptosis and invasion pathways

Cytochrome P450 17 (CYP17) encodes cytochrome P450c17α, an enzyme with 17α-hydroxylase and 17, 20-lyase activities involved in estradiol biosynthesis. Here we examine the role of CYP17 gene in endometrial carcinogenesis. Immunohistochemistry staining of endometrial carcinoma and corresponding uninvolved tissues showed that CYP17 is upregulated in endometrial cancers (15 of 24, 62.5%). To understand the functional significance of this upregulation, we silenced CYP17 gene by introduction of siRNA into endometrial cancer cell line KLE followed by functional studies. Further, to understand the molecular basis of the role of CYP17, we profiled the expression of key pathway-specific genes and identified several components of the apoptosis and invasion pathways that are potentially regulated by CYP17. Silencing of CYP17 caused decreased cell proliferation and induced apoptosis. Significantly, CYP17 depletion leads to downregulation of anti-apoptotic genes B cell lymphoma 2 (Bcl-2) and telomerase reverse transcriptase (TERT), indicating induced apoptosis. Also, attenuation of CYP17 decreased the cellular invasion ability and regulated expression of several invasion pathway components such as melanoma cell adhesion molecule (MCAM), matrix metallopeptidase 2 and 9 (MMP-2 and MMP-9), and tissue inhibitor of metalloproteinase 3 (TIMP3). In conclusion, this is the first report documenting that upregulation of CYP17 in endometrial cancers play a crucial role in endometrial carcinogenesis by targeting multiple components of apoptosis and invasion pathways. Further studies are required to understand the detailed mechanisms underlying CYP17-mediated regulation of these components.

Towards understanding the mode of action of the multifaceted cell adhesion receptor CD146

CD146, also known as melanoma cell adhesion molecule or MCAM, is a key cell adhesion protein in vascular endothelial cell activity and angiogenesis. CD146 promotes tumor progression of many cancers including melanoma and prostate. Strikingly, its expression is frequently lost in breast carcinoma cells, and it may act as a suppressor of breast cancer progression. While upstream mechanisms regulating CD146 are well documented, our understanding of the downstream molecular events underlying its mode of action remains to be elucidated. This review aims to focus on the progress in understanding the signaling mechanisms and the functional relevance of CD146, a multifaceted molecule, in cancer with particular emphasis on its role in inhibiting breast cancer progression.

In-depth proteomics to define the cell surface and secretome of ovarian cancer cells and processes of protein shedding

Current proteomics technologies allow substantial depth of analysis of cellular and subcellular proteomes as shown in the proteomic profiling of ovarian cancer cells. This in-depth analysis has elucidated the repertoire of proteins expressed on the cell surface and proteins released into the extracellular milieu, uncovering extensive shedding of extracellular domains of cell adhesion proteins and a highly dynamic protein secretion process. The protein sets identified provide a rich resource of potential circulating markers and targets for imaging and therapeutics for ovarian cancer.

CD146 expression is associated with a poor prognosis in human breast tumors and with enhanced motility in breast cancer cell lines

Introduction

Metastasis is a complex process involving loss of adhesion, migration, invasion and proliferation of cancer cells. Cell adhesion molecules play a pivotal role in this phenomenon by regulating cell–cell and cell–matrix interactions. CD146 (MCAM) is associated with an advanced tumor stage in melanoma, prostate cancer and ovarian cancer. Studies of CD146 expression and function in breast cancer remain scarce except for a report concluding that CD146 could act as a tumor suppressor in breast carcinogenesis.

Methods

To resolve these apparent discrepancies in the role of CD146 in tumor cells, we looked at the association of CD146 expression with histoclinical features in human primary breast cancers using DNA and tissue microarrays. By flow cytometry, we characterized CD146 expression on different breast cancer cell lines. Using siRNA or shRNA technology, we studied functional consequences of CD146 downmodulation of MDA-MB-231 cells in migration assays. Wild-type, mock-transfected and downmodulated transfected cells were profiled using whole-genome DNA microarrays to identify genes whose expression was modified by CD146 downregulation.

Results

Microarray studies revealed the association of higher levels of CD146 with histoclinical features that belong to the basal cluster of human tumors. Expression of CD146 protein on epithelial cells was detected in a small subset of cancers with histoclinical features of basal tumors. CD146⁺ cell lines displayed a mesenchymal phenotype. Downmodulation of CD146 expression in the MDA-MB-231 cell line resulted in downmodulation of vimentin, as well as of a set of genes that include both genes associated with a poor prognosis in a variety of cancers and genes known to promote cell motility. In vitro functional assays revealed decreased migration abilities associated with decreased CD146 expression.

Conclusions

In addition to its expression in the vascular compartment, CD146 is expressed on a subset of epithelial cells in malignant breast. CD146 may directly or indirectly contribute to tumor aggressiveness by promoting malignant cell motility. Changes in molecular signatures following downmodulation of CD146 expression suggest that CD146 downmodulation is associated with the reversal of several biological characteristics associated with epithelial to mesenchymal transition, and the phenomenon associated with the metastatic process.

A subset of host B lymphocytes controls melanoma metastasis through a melanoma cell adhesion molecule/MUC18-dependent interaction: evidence from mice and humans

Host immunity affects tumor metastasis but the corresponding cellular and molecular mechanisms are not entirely clear. Here, we show that a subset of B lymphocytes (termed B-1 population), but not other lymphocytes, has prometastatic effects on melanoma cells in vivo through a direct heterotypic cell-cell interaction. In the classic B16 mouse melanoma model, one mechanism underlying this phenomenon is a specific up-regulation and subsequent homophilic interaction mediated by the cell surface glycoprotein MUC18 (also known as melanoma cell adhesion molecule). Presence of B-1 lymphocytes in a panel of tumor samples from melanoma patients directly correlates with MUC18 expression in melanoma cells, indicating that the same protein interaction exists in humans. These results suggest a new but as yet unrecognized functional role for host B-1 lymphocytes in tumor metastasis and establish a biochemical basis for such observations. Our findings support the counterintuitive central hypothesis in which a primitive layer of the immune system actually contributes to tumor progression and metastasis in a mouse model and in melanoma patients. Given that monoclonal antibodies against MUC18 are in preclinical development but the reason for their antitumor activity is not well understood, these translational results are relevant in the setting of human melanoma and perhaps of other cancers.

Inhibition of prostate carcinogenesis by combined active immunoprophylaxis

The aim of this study is to investigate whether an active immunoprophylactic approach combining specific antigens and adjuvant stimuli would be able to inhibit prostate carcinogenesis in transgenic TRAMP mice. A vaccine consisting of allogeneic large T antigen (TAg)-positive SV40-transformed cells combined with systemic recombinant IL-12 was administered to TRAMP mice, starting from when they were still tumor-free at 5-6 weeks of age. The combined vaccine significantly inhibited prostate carcinogenesis, giving a more than doubled median latency time of prostatic tumors (53 weeks in comparison to 26 weeks in control mice). Vaccination with cells alone or IL-12 treatment alone was poorly effective (median latency of 30 and 39 weeks, respectively). The combined vaccine induced a very high CD4 response biased toward the Th1 pathway, with the induction of a humoral response that included TAg-specific antibodies. Therefore, such active immunoprophylactic approach based on the combination of allogeneic SV40 TAg-positive cells and systemic administration of recombinant IL-12 significantly delayed autochthonous urogenital carcinogenesis driven by SV40 TAg in TRAMP mice.

Potential clinical relevance of Eph receptors and ephrin ligands expressed in prostate carcinoma cell lines

The family of Eph and ephrin receptors is involved in a variety of functions in normal cells, and the alterations in their expression profiles have been observed in several cancers. We have compared the transcripts for Eph receptors and ephrin ligands in cell lines established from normal prostate epithelium and several carcinoma cell lines isolated from prostate tumors of varying degree of metastasis. These cell lines included NPTX, CTPX, LNCaP, DU145, PC-3, and PC-3ML. The cell lines displayed characteristic pattern of expression for specific Eph receptors and ephrin ligands, thus allowing identification of Eph receptor signatures for a particular cell line. The sensitivity of these transcripts to genome methylation is also investigated by treating the cells with 5-aza-2'-deoxycytidine. The comparison of expression profiles revealed that normal prostate and primary prostate tumor cell lines differ in the expression of EphA3, EphB3, and ephrin A3 that are over-expressed in normal prostate. Furthermore, the transcript levels for EphA1 decrease progressively from normal prostate to primary prostate tumor cell line and metastatic tumor cells. A converse relationship was observed for ephrin B2. The treatment of cells with 5-aza-2'-deoxycytidine revealed the sensitivity of EphA3, EphA10, EphB3, and EphB6 to methylation status of genomic DNA. The utility of methylation specific PCR to identify prostate tumor cells and the importance of specific Eph receptors and ephrin ligands in initiation and progression of prostate tumor are discussed.