Blood MUC-18/MCAM expression in patients with melanoma: a suitable marker of poor outcome

Epithelial-to-Mesenchymal Transition Gene Signature in Circulating Melanoma Cells: Biological and Clinical Relevance

The most promising method for monitoring patients with minimal morbidity is the detection of circulating melanoma cells (CMCs). We have shown that CD45^-CD146⁺ABCB5⁺ CMCs identify a rare primitive stem/mesenchymal CMCs population associated with disease progression. The epithelial-to-mesenchymal transition (EMT) confers cancer cells a hybrid epithelial/mesenchymal phenotype promoting metastatization. Thus, we investigated the potential clinical value of the EMT gene signature of these primitive CMCs. A reliable quantitative real-time polymerase chain reaction (qRT-PCR) protocol was settled up using tumor cell lines RNA dilutions. Afterwards, immune-magnetically isolated CMCs from advanced melanoma patients, at onset and at the first checkpoint (following immune or targeted therapy), were tested for the level of EMT hallmarks and EMT transcription factor genes. Despite the small cohort of patients, we obtained promising results. Indeed, we observed a deep gene rewiring of the EMT investigated genes: in particular we found that the EMT gene signature of isolated CMCs correlated with patients' clinical outcomes. In conclusion, We established a reliable qRT-PCR protocol with high sensitivity and specificity to characterize the gene expression of isolated CMCs. To our knowledge, this is the first evidence demonstrating the impact of immune or targeted therapies on EMT hallmark gene expressions in CMCs from advanced melanoma patients.

MCAM/MUC18/CD146 as a Multifaceted Warning Marker of Melanoma Progression in Liquid Biopsy

Human malignant melanoma shows a high rate of mortality after metastasization, and its incidence is continuously rising worldwide. Several studies have suggested that MCAM/MUC18/CD146 plays an important role in the progression of this malignant disease. MCAM/MUC18/CD146 is a typical single-spanning transmembrane glycoprotein, existing as two membrane isoforms, long and short, and an additional soluble form, sCD146. We previously documented that molecular MCAM/MUC18/CD146 expression is strongly associated with disease progression. Recently, we showed that MCAM/MUC18/CD146 and ABCB5 can serve as melanoma-specific-targets in the selection of highly primitive circulating melanoma cells, and constitute putative proteins associated with disease spreading progression. Here, we analyzed CD146 molecular expression at onset or at disease recurrence in an enlarged melanoma case series. For some patients, we also performed the time courses of molecular monitoring. Moreover, we explored the role of soluble CD146 in different cohorts of melanoma patients at onset or disease progression, rather than in clinical remission, undergoing immune therapy or free from any clinical treatment. We showed that MCAM/MUC18/CD146 can be considered as: (1) a membrane antigen suitable for identification and enrichment in melanoma liquid biopsy; (2) a highly effective molecular "warning" marker for minimal residual disease monitoring; and (3) a soluble protein index of inflammation and putative response to therapeutic treatments.

Recognize the role of CD146/MCAM in the osteosarcoma progression: an in vitro study

Background

Osteosarcoma (OS) is a common malignant bone tumor with poor prognosis. We previously reviewed that CD146 is correlated with multiple cancer progression, while its impact on OS is currently not systematically studied.

Methods

MG63 was transfected with lentivirus to express CD146 ectopically, and anti-CD146 neutralizing antibody ab75769 was used to inhibit 143B. Cyclic migration of MG63 and co-culture between MG63 and 143B were used to explore the role of OS malignancy in CD146 expression. The effect of OS cell medium (CM) on endothelium behaviors was assessed, and the expression changes of CD146 before and after co-culture of endothelium and OS were evaluated. Finally, the expression of CD146 in OS was detected under different culture conditions, including hyperoxia, low oxygen, high glucose and low glucose conditions.

Results

CD146 promoted the colony formation, migration, invasion and homotypic adhesion of OS cells, and reducing the concentration of soluble CD146 in the OS medium inhibited the proliferation, migration and lumen formation of the cultured endothelium. However, CD146 did not affect the adhesion between OS and endothelium, nor did co-culture of both sides affect the CD146 expression. Similarly, the proliferation, migration and CD146 expression of MG63 remained unchanged after many cycles of migration itself, as did its co-culture with 143B for expressing CD146. In addition, we also showed that high glucose promoted the expression of CD146 in OS, while hypoxia had the opposite effect.

Conclusions

These findings demonstrate that CD146 promotes OS progression by mediating pro-tumoral and angiogenic effects. Thus, CD146 could be a potential therapeutic target for OS, especially for OS patients with diabetes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02006-7.

Minimal Residual Disease in Melanoma:molecular characterization of in transit cutaneous metastases and Circulating Melanoma Cells recognizes an expression panel potentially related to disease progression

Isolating circulating melanoma cells (CMCs) represents a powerful method to monitor minimal residual disease. We documented that MCAM/MUC18/CD146 expression is strongly associated with disease progression. ABCB5 is melanoma-stem antigen with self-renewal, proliferation, differentiation, tumorigenicity capabilities. These findings supported us to improve CMC detection, investigating MCAM/MUC18/CD146 and ABCB5 as enrichment targets in MM progression. Moreover, we decided to compare possible molecular diversity of these CMC fractions with metastatic tissue expression, collecting concomitantly cutaneous in transit metastases (CTM). We enriched CMCs from eight melanoma patients staged ≥pT1b AJCC, who developed CTMs at baseline or during follow up. We assessed a gene expression panel comprising ABCB5, the differentiation markers (Tyrosinase, MART1), angiogenic factors (VEGF, bFGF), the cell-cell adhesion molecules (MCAM/MUC18/CD146 5'-portion, Long, and Short isoforms, E-Cadherin, N-Cadherin, VE-Cadherin) and matrix-metallo-proteinases (MMP2 and MMP9) via high-sensitive RT-PCR. Preliminary findings defined three distinct sub-populations: "endothelial" CD45-CD146+CMCs, "stem" CD45-ABCB5+CMCs and a "hybrid- stem-endothelial"- CD45-MCAM+ABCB5+CMCs. The expression panel documented that - almost high expression found in CTMs - like in 73.5% of CMCs resulted positive for at least one transcript at baseline, showing gene-expression variability. Longitudinal monitoring documented shut-down of all gene-expressions in "endothelial"- and "hybrid stem-endothelial"-subsets, whilst persistency or acquisition of MCAM/MUC18/CD146, VE-CADH and MMPs was documented in disease-progression status.Conversely, a drastic expression shut-down was documented when patients achieved clinical remission. The "stem"- CMCs fraction" showed quite lower gene expression frequencies. MCAM/MUC18/CD146 and ABCB5 as melanoma-specific-targets are effective in the selection of highly primitive CMCs and highlights those putative genes associated with disease spreading progression.

Stem-Mesenchymal Signature Cell Genes Detected in Heterogeneous Circulating Melanoma Cells Correlate With Disease Stage in Melanoma Patients

During the process of metastasis, cancer cells dissociate from primary tumors, migrate to distal sites, and finally colonize, eventually leading to the formation of metastatic tumors. These cancer cells, defined circulating tumor cells (CTCs) spreading through the blood stream, may develop metastatic lesions or remain dormant. Some emerging clinical evidence supports that some tumor cells may possess metastatic properties already in the earlier stages of tumorigenesis. Because the initiation and progression of vertical growth in human melanoma is fundamental to the notion of tumor virulence and progression, we decided to immune-magnetic collect and molecularly characterize circulating melanoma cells (CMCs) from melanoma patients AJCC staged = pT1b (i.e., transition from radial to vertical phase). CMCs are phenotypically and molecularly heterogeneous, thus we performed a "home-made Liquid-Biopsy," by targeting the melanoma-associated-antigen, MCAM/MUC18/CD146, and/or the melanoma-initiating marker, ABCB5. We assessed a biomarker qualitative expression panel, contemplating the angiogenic-potential, melanoma-initiating and melanoma-differentiation drivers, cell-cell adhesion molecules, matrix-metallo-proteinases, which was performed on three enriched subpopulations from a total of 61 blood-samples from 21 melanoma patients. At first, a significant differential expression of the specific transcripts was documented between and within the CMC fractions enriched with MCAM-, ABCB5-, and both MCAM/ABCB5-coated beads, when analyzing two distinct groups: early AJCC- (stage I-II) and advanced- staged patients (stage II-IV). Moreover, in the early-AJCC staged-group, we could distinguish "endothelial," CD45-MCAM+ enriched-, "stem" S-CMCs, CD45-ABCB5+ enriched- and a third hybrid bi-phenotypic CD45-MCAM+/ABCB5+ enriched-fractions, due to three distinct gene-expression profiles. In particular, the endothelial-CMCs were characterized by positive expression of genes involved in migration and invasion, whilst the stem CMC-fraction only expressed stem and differentiation markers. The third subpopulation isolated based on concurrent MCAM and ABCB5 protein expression showed an invasive phenotype. All three distinct CMCs sub-populations, exhibited a primitive, "stem-mesenchymal" profile suggesting a highly aggressive and metastasizing phenotype. This study confirms the phenotypic and molecular heterogeneity observed in melanoma and highlights those putative genes involved in early melanoma spreading and disease progression.

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.

Minimal residual disease in melanoma: circulating melanoma cells and predictive role of MCAM/MUC18/MelCAM/CD146

Circulating tumour cells (CTCs), identified in numerous cancers including melanoma, are unquestionably considered valuable and useful as diagnostic and prognostic markers. They can be detected at all melanoma stages and may persist long after treatment. A crucial step in metastatic processes is the intravascular invasion of neoplastic cells as circulating melanoma cells (CMCs). Only a small percentage of these released cells are efficient and capable of colonizing with a strong metastatic potential. CMCs' ability to survive in circulation express a variety of genes with continuous changes of signal pathways and proteins to escape immune surveillance. This makes it difficult to detect them; therefore, specific isolation, enrichment and characterization of CMC population could be useful to monitor disease status and patient clinical outcome. Overall and disease-free survival have been correlated with the presence of CMCs. Specific melanoma antigens, in particular MCAM (MUC18/MelCAM/CD146), could be a potentially useful tool to isolate CMCs as well as be a prognostic, predictive biomarker. These are the areas reviewed in the article.

MCAM, as a novel receptor for S100A8/A9, mediates progression of malignant melanoma through prominent activation of NF-κB and ROS formation upon ligand binding

The dynamic interaction between tumor cells and their microenvironment induces a proinflammatory milieu that drives cancer development and progression. The S100A8/A9 complex has been implicated in chronic inflammation, tumor development, and progression. The cancer microenvironment contributes to the up-regulation of this protein complex in many invasive tumors, which is associated with the formation of pre-metastatic niches and poor prognosis. Changing adhesive preference of cancer cells is at the core of the metastatic process that governs the reciprocal interactions of cancer cells with the extracellular matrices and neighboring stromal cells. Cell adhesion molecules (CAMs) have been confirmed to have high-level expression in various highly invasive tumors. The expression and function of CAMs are profoundly influenced by the extracellular milieu. S100A8/A9 mediates its effects by binding to cell surface receptors, such as heparan sulfate, TLR4 and RAGE on immune and tumor cells. RAGE has recently been identified as an adhesion molecule and has considerably high identity and similarity to ALCAM and MCAM, which are frequently over-expressed on metastatic malignant melanoma cells. In this study, we demonstrated that ALCAM and MCAM also function as S100A8/A9 receptors as does RAGE and induce malignant melanoma progression by NF-κB activation and ROS formation. Notably, MCAM not only activated NF-κB more prominently than ALCAM and RAGE did but also mediated intracellular signaling for the formation of lung metastasis. MCAM is known to be involved in malignant melanoma development and progression through several mechanisms. Therefore, MCAM is a potential effective target in malignant melanoma treatment.

The multifaceted role of CD146/MCAM in the promotion of melanoma progression

Human malignant melanoma is a common primary malignant cutaneous tumour derived from transformed epidermal melanocytes. Patients with melanoma have a high rate of mortality due to resistance to chemotherapeutic drugs, a major obstacle to a successful treatment. Several reports have suggested that CD146 plays an important role as a signalling molecule in human melanoma. This role includes CD146 as a participant in inflammation, differentiation, adhesion, tumourigenicity, metastasis, invasion and angiogenesis among other processes, which suggests that this molecule promotes the progression of human melanoma as a multifaceted regulator. In this article, we explore the effects and corresponding mechanisms with respect to the role of CD146/MUC18 in the promotion of human melanoma progression. Collectively, the studies indicated that targeting CD146, because it is a suitable marker of poor patient outcome, might be useful in the design of future strategies for the prevention and treatment of human melanoma.

Sequential molecular analysis of circulating MCAM/MUC18 expression: a promising disease biomarker related to clinical outcome in melanoma

MCAM/MUC18 is a cell adhesion molecule associated with higher incidence of relapse in melanoma. The purpose of our study was to evaluate its role as a promising disease biomarker of progression through sequential molecular MCAM/MUC18 RT-PCR assay on serial blood samples collected during the clinical follow-up of 175 melanoma patients in different American Joint Committee on Cancer (AJCC) stages. MCAM/MUC18 molecular detection, found at least once in 22 out of the 175 patients, was significantly associated with poor prognosis and death (p < 0.001), regardless of the AJCC stages. Positive expression, either if primarily present or later acquired, was associated with melanoma progression, whereas patients primarily negative or with subsequent loss gained clinical remission or stable disease, even if in advanced stages (p < 0.005). Six AJCC advanced stages always MCAM/MUC18 negative are in complete remission or with a stable disease (p < 0.007). Semiquantitative immunohistochemical MCAM/MUC18 staining on corresponding primary melanomas was related to peripheral molecular expression. Correlations between circulating molecular and tissutal immunohistochemical detection, primary tumour thickness, AJCC stages and clinical outcome were statistically evaluated using Student's t test, ANOVA, Spearman's rank correlation test, Pearson χ (2)-test and McNemar's test. In our investigation, MCAM/MUC18 expression behaves as a "molecular warning of progression" even in early AJCC patients otherwise in disease-free conditions. Achievement of this molecule predicted the emergence of a clinically apparent status, whereas absence or persistent loss was related to a stable disease or to a disease-free status. If confirmed in larger case series, MCAM/MUC18 molecular expression could predict good or poor clinical outcome, possibly becoming a promising prognostic factor.