Expression of the stem cell marker nestin in peripheral blood of patients with melanoma

Circulating tumor cells in solid malignancies: From advanced isolation technologies to biological understanding and clinical relevance in early diagnosis and prognosis

Circulating tumor cells (CTCs) are shed from primary tumors and travel through the body via circulation, eventually settling to form micrometastases under favorable conditions. Numerous studies have identified CTCs as a negative prognostic indicator for survival across various cancer types. CTCs mirror the current heterogeneity and genetic and biological state of tumors, making their study invaluable for understanding tumor progression, cell senescence, and cancer dormancy. However, their isolation and characterization still poses a major challenge that limits their clinical translation. A wide array of methods, each with different levels of specificity, utility, cost, and sensitivity, have been developed to isolate and characterize CTCs. Moreover, innovative techniques are emerging to address the limitations of existing methods. In this review, we provide insights into CTC biology addressing spectra of markers employed for molecular analysis and functional characterization. It also emphasizes current label-dependent and label-independent isolation procedures, addressing their strengths and limitations. SIGNIFICANCE: A comprehensive overview of CTC biology, their molecular and functional characterization, along with their current clinical utility will help in understanding the present-day extent to which the clinical potential of CTCs is getting tapped in personalized medicine.

Dysregulated megakaryocyte distribution associated with nestin+ mesenchymal stem cells in immune thrombocytopenia

Impaired megakaryocyte (MK) maturation and reduced platelet production are important causes of immune thrombocytopenia (ITP). However, MK distribution and bone marrow (BM) niche alteration in ITP are unclear. To investigate the maturation and distribution of MKs in the BM niche and examine the components of BM niche regulation of MK migration, BM and peripheral blood were obtained from 30 ITP patients and 28 healthy donors. Nestin⁺ mesenchymal stem cells (MSCs) and CD41⁺ MKs were sorted by fluorescence-activated cell sorting. The components of the BM niche and related signaling were analyzed via immunofluorescence, flow cytometry, enzyme-linked immunosorbent assay, reverse transcription polymerase chain reaction, and western blot analysis. The number of MKs in the BM vascular niche was reduced in ITP. Moreover, the concentrations of CXCL12 and CXCR4⁺ MKs in the BM were decreased in ITP. Further investigation demonstrated that nestin⁺ MSCs and CXCL12 messenger RNA (mRNA) in nestin⁺ MSCs were both reduced whereas the apoptosis of nestin⁺ MSCs was significantly increased in ITP. Sympathetic nerves, Schwann cells, the proportion of β3-adrenoreceptor (β3-AR)⁺ nestin⁺ MSCs, and β3-AR mRNA in nestin⁺ MSCs were all markedly reduced in ITP. Moreover, matrix metalloproteinase 9, vascular endothelial growth factor (VEGF), and VEGF receptor 1 were significantly reduced in ITP. Our data show that impaired MK distribution mediated by an abnormal CXCL12/CXCR4 axis is partially involved in reduced platelet production in ITP. Moreover, sympathetic neuropathy and nestin⁺ MSC apoptosis may have an effect on the alterations of BM CXCL12 in ITP.

The Emerging Role of Cytoskeletal Proteins as Reliable Biomarkers

Cytoskeletal proteins are essential building blocks of cells. More than 100 cytoskeletal and cytoskeleton-associated proteins are known and for some, their function and regulation are understood in great detail. Apart from cell shape and support, they facilitate many processes such as intracellular signaling and transport, and cancer related processes such as proliferation, migration, and invasion. During the last decade, comparative proteomic studies have identified cytoskeletal proteins as in vitro markers for tumor progression and metastasis. Here, these results are summarized and a number of unrelated studies are highlighted, identifying the same cytoskeletal proteins as potential biomarkers. These findings might indicate that the abundance of these potential markers of tumor progression is associated with the biological outcome and are independent of the cancer origin. This correlates well with recently published results from the Cancer Genome Atlas, indicating that cancers show remarkable similarities in their analyzed molecular information, independent of their organ of origin. It is postulated that the quantification of cytoskeletal proteins in healthy tissues, tumors, in adjacent tissues, and in stroma, is a great source of molecular information, which might not only be used to classify tumors, but more importantly to predict patients' outcome or even best treatment choices.

Intracellular Notch1 Signaling in Cancer-Associated Fibroblasts Dictates the Plasticity and Stemness of Melanoma Stem/Initiating Cells

Cancer stem cells (CSCs) play critical roles in cancer initiation, metastasis, recurrence, and drug resistance. Recent studies have revealed involvement of cancer‐associated fibroblasts (CAFs) in regulating CSCs. However, the intracellular molecular mechanisms that determine the regulatory role of CAFs in modulating the plasticity of CSCs remain unknown. Here, we uncovered that intracellular Notch1 signaling in CAFs serves as a molecular switch, which modulates tumor heterogeneity and aggressiveness by inversely controlling stromal regulation of the plasticity and stemness of CSCs. Using mesenchymal stem cell‐derived fibroblasts (MSC‐DF) harboring reciprocal loss‐of‐function and gain‐of‐function Notch1 signaling, we found that MSC‐DF^{Notch1−/−} prompted cocultured melanoma cells to form more spheroids and acquire the phenotype (CD271⁺ and Nestin⁺) of melanoma stem/initiating cells (MICs), whereas MSC‐DF^N1IC+/+ suppressed melanoma cell sphere formation and mitigated properties of MICs. MSC‐DF^{Notch1−/−} increased stemness of CD271⁺ MIC, which resultantly exhibited stronger aggressiveness in vitro and in vivo, by upregulating Sox2/Oct4/Nanog expression. Consistently, when cografted with melanoma cells into NOD scid gamma (NSG) mice, MSC‐DF^{Notch1−/−} increased, but MSC‐DF^N1IC+/+ decreased, the amounts of CD271⁺ MIC in melanoma tissue. The amounts of CD271⁺ MIC regulated by MSC‐DF carrying high or low Notch1 pathway activity is well correlated with capability of melanoma metastasis, supporting that melanoma metastasis is MIC‐mediated. Our data demonstrate that intracellular Notch1 signaling in CAFs is a molecular switch dictating the plasticity and stemness of MICs, thereby regulating melanoma aggressiveness, and therefore that targeting the intracellular Notch1 signaling pathway in CAFs may present a new therapeutic strategy for melanoma. stem cells2019;37:865–875

BRAF and MEK inhibitor therapy eliminates Nestin-expressing melanoma cells in human tumors

Little is known about the in vivo impacts of targeted therapy on melanoma cell abundance and protein expression. Here, 21 antibodies were added to an established melanoma mass cytometry panel to measure 32 cellular features, distinguish malignant cells, and characterize dabrafenib and trametinib responses in BRAFV600mut melanoma. Tumor cells were biopsied before neoadjuvant therapy and compared to cells surgically resected from the same site after 4 weeks of therapy. Approximately 50,000 cells per tumor were characterized by mass cytometry and computational tools t-SNE/viSNE, FlowSOM, and MEM. The resulting single-cell view of melanoma treatment response revealed initially heterogeneous melanoma tumors were consistently cleared of Nestin-expressing melanoma cells. Melanoma cell subsets that persisted to week 4 were heterogeneous but expressed SOX2 or SOX10 proteins and specifically lacked surface expression of MHC I proteins by MEM analysis. Traditional histology imaging of tissue microarrays from the same tumors confirmed mass cytometry results, including persistence of NES- SOX10+ S100β+ melanoma cells. This quantitative single-cell view of melanoma treatment response revealed protein features of malignant cells that are not eliminated by targeted therapy.

Cancer Stem Cells or Tumor Survival Cells?

Research endeavors originally generated stem cell definitions for the purpose of describing normally sustainable developmental and tissue turnover processes in various species, including humans. The notion of investigating cells that possess a vague capacity of “stamm (phylum)” can be traced back to the late 19th century, mainly concentrating on cells that could produce the germline or the entire blood system. Lately, such undertakings have been recapitulated for oncogenesis, tumor growth, and cancer cell resistance to oncolytic therapies. However, due to the complexity and basic life-origin mechanisms comprising the genetic and epigenetic repertoire of the stemness in every developing or growing cell, presently there are ongoing debates regarding the biological essentials of the stem cell-like tumor initiation cells (ie, cancer stem cells; CSCs). This conceptual analysis focuses on the potential pitfalls of extrapolating that CSCs bear major traits of stemness. We propose a novel nomenclature of Tumor Survival Cells (TSCs) to further define tumor cells behaving like CSCs, based on the ruthless and detrimental features of Cancer Cell Survivology that appears fundamentally different from stem cell biology. Hence, precise academic separation of TSCs from all the stem cell-related labels applied to these unique tumor cells may help to improve scientific reasoning and strategies to decode the desperado-like survival behaviors of TSCs to eventually overcome cancer.

Nestin expression in primary and metastatic uveal melanoma - possible biomarker for high-risk uveal melanoma

PURPOSE

Nestin, a member of the intermediate filament protein family, has been described as a putative cancer stem cell marker (CSC) in uveal melanoma and poor prognostic factor in a variety of tumours, including cutaneous melanoma. In this study, we examined the expression of nestin in primary (PUM) and metastatic uveal melanoma (MUM) samples, and correlated the findings with histological, clinical and survival data.

METHODS

Nestin expression was assessed by immunohistochemistry in 141 PUM and 26 MUM samples; 11 PUM cases were matched with their corresponding metastases. The percentage of tumour cells expressing nestin was scored by three independent observers. Statistical analysis of all data was performed with SPSS.

RESULTS

Nestin expression was identified in both the cytoplasm and membrane of UM cells. Increased expression of nestin in PUM samples was associated with known poor prognostic parameters, including epithelioid cell morphology (p < 0.001), closed loops (p = 0.001), higher mitotic count (p < 0.001), monosomy 3 (p = 0.007) and chromosome 8q gain (p < 0.001). Primary uveal melanoma (PUM) with nestin expression levels above a cut-off value of 10% [as determined by receiver operating characteristic (ROC) analysis] was associated with a significantly reduced survival time (Log-rank, p = 0.002). In MUM, a higher percentage of nestin-positive tumour cells combined with poor prognostic markers in the PUM led to a shorter survival time following the development of metastases.

CONCLUSION

In conclusion, increased nestin expression in PUM is a predictor of a tumour phenotype associated with metastatic progression and reduced survival time at onset of metastasis.

Inflammatory regulation of stem-like cells in melanoma

The link between inflammation, immunity and cancer is well established. In the last decade, there has been considerable excitement over cancer stem cells, believed to be a subset of tumour cells responsible for their initiation, propagation and resistance to conventional chemoradiotherapy. In this review, we discuss the characterization of cancer stem cells and describe their modulation by inflammation with a focus on melanoma.

From Normal Skin to Squamous Cell Carcinoma: A Quest for Novel Biomarkers

Squamous cells carcinoma (SCC) is the second most frequent of the keratinocyte-derived malignancies after basal cell carcinoma and is associated with a significant psychosocial and economic burden for both the patient himself and society. Reported risk factors for the malignant transformation of keratinocytes and development of SCC include ultraviolet light exposure, followed by chronic scarring and inflammation, exposure to chemical compounds (arsenic, insecticides, and pesticides), and immune-suppression. Despite various available treatment methods and recent advances in noninvasive or minimal invasive diagnostic techniques, the risk recurrence and metastasis are far from being negligible, even in patients with negative histological margins and lymph nodes. Analyzing normal, dysplastic, and malignant keratinocyte proteome holds special promise for novel biomarker discovery in SCC that could be used in the future for early detection, risk assessment, tumor monitoring, and development of targeted therapeutic strategies.

Circulating biomarkers in malignant melanoma

Melanoma is an aggressive tumor with increasing incidence worldwide. Biomarkers are valuable tools to minimize the cost and improve efficacy of treatment of this deadly disease. Serological markers have not widely been introduced in routine clinical practice due to their insufficient diagnostic sensitivity and specificity. It is likely that the lack of objective responses with traditional treatment hinder biomarker research and development in melanoma. Recently, new drugs and therapies have, however, emerged in advanced melanoma with noticeable objective response ratio and survival. In this new scenario, serological tumor markers should be revisited. In addition, other potential circulating biomarkers such as cell-free DNA, exosomes, microRNA, and circulating tumor cells have also been identified. In this review, we summarize classical and emerging tumor markers and discuss their possible roles in emerging therapeutics.

Circulating tumour cells: the evolving concept and the inadequacy of their enrichment by EpCAM-based methodology for basic and clinical cancer research

Increasing evidence suggests that circulating tumour cells (CTCs) are responsible for metastatic relapse and this has fuelled interest in their detection and quantification. Although numerous methods have been developed for the enrichment and detection of CTCs, none has yet reached the 'gold' standard. Since epithelial cell adhesion molecule (EpCAM)-based enrichment of CTCs offers several advantages, it is one of the most commonly used and has been adapted for high-throughput technology. However, emerging evidence suggests that CTCs are highly heterogeneous: they consist of epithelial tumour cells, epithelial-to-mesenchymal transition (EMT) cells, hybrid (epithelial/EMT(+)) tumour cells, irreversible EMT(+) tumour cells, and circulating tumour stem cells (CTSCs). The EpCAM-based approach does not detect CTCs expressing low levels of EpCAM and non-epithelial phenotypes such as CTSCs and those that have undergone EMT and no longer express EpCAM. Thus, the approach may lead to underestimation of the significance of CTCs, in general, and CTSCs and EMT(+) tumour cells, in particular, in cancer dissemination. Here, we provide a critical review of research literature on the evolving concept of CTCs and the inadequacy of their enrichment by EpCAM-based technology for basic and clinical cancer research. The review also outlines future perspectives in the field.

CD133 expression in normal skin and in epithelial cutaneous tumors

Background. Expression of human CD133 (human prominin-1) in cancer cells has been postulated to be a marker of stemness and is considered as a putative marker of cancer stem cells (CSCs). We designed a study to describe the expression pattern of CD133 in normal skin and in epithelial cutaneous neoplasms. Methods. The CD133 immunohistochemical expression of forty-three eccrine and apocrine tumors was compared to that observed in other epithelial tumors of the skin. In addition, flow cytometry was used to detect the CD133 expression of four epithelial skin neoplasms, including one porocarcinoma. Results. CD133 immunoreactivity at the apical or at the apicolateral surface of cells forming glandular structures was observed. Cells from solid areas of benign or malignant tumors were not stained. The porocarcinoma derived culture cells showed a 22% of CD133 positive cells using flow cytometry, while squamous cell carcinoma cultures contained less than 0.1%. Conclusions. These observations indicate that CD133 is a specific marker of glandular differentiation that could be included in the diagnostic panel of cutaneous tumors with possible eccrine or apocrine differentiation. However, the use of CD133 expression as a marker of CSCs should be interpreted with caution in experiments of skin.

CD10 expression by melanoma cells is associated with aggressive behavior in vitro and predicts rapid metastatic progression in humans

BACKGROUND

No biological or molecular marker of primary melanoma tumor cells has been shown to predict clinical outcome in melanoma.

OBJECTIVE

To determine whether CD10, CD133, nestin and CD20 may evaluate the prognosis of melanoma.

METHODS

The differential expression of these molecules was assessed in pairs of cell lines. We evaluated, by both immunohistochemical staining and RT-qPCR, their expression in a cohort of 32 patients (68 samples) with a history of metastatic melanoma, divided into two groups according to their clinical outcome profile.

RESULTS

CD10 over expression in cancer cell lines was associated with more aggressive behavior in vitro. A CD10-positive staining was more frequent in patients in the "rapidly progressive" group than those in the "long survivor" group (23/35 versus 2/18, p<10(-4)). CD10 expression was associated with a lower median overall survival (1.15 year - IQR: [0.50-2.58] versus 4.27 - IQR: [1.66-6.33]; p=10(-4)). The Odds Ratio of displaying a "rapidly progressive" melanoma when tumor cells expressed CD10 was 15 (95% confidence interval: [3-78]). After adjusting for confounding factors, CD10 expression in melanoma tumor cells remained associated with an increased risk of death and more rapid disease progression (p=6×10(-4); HR=3.71).

CONCLUSION

CD10 may predict clinical outcome in melanoma patients.

The immune system--a hidden treasure for biomarker discovery in cutaneous melanoma

This chapter describes how skin immune system (SIS) is specifically involved in the development of cutaneous melanoma. Local immune surveillance is presented as a complex process that comprises markers to be monitored in disease's evolution and in therapy. The ranking of tissue or soluble immune markers in a future panel of diagnostic/prognostic panel are evaluated. Taking into account the difficulties of cutaneous melanoma patients' management, this chapter shows the immune surveillance at the skin level, the conditions that favor the tumor escape from the immunological arm, the immune pattern of skin melanoma with diagnostic/prognostic relevance, the circulatory immune markers, and, last but not least, how immune markers are used in immune-therapy monitoring. The chapter cannot be exhaustive but will give the reader a glimpse of the complex immune network that lies within tumor escape and where to search for immune-therapeutical targets in skin melanoma.

Circulating tumor cells in melanoma patients

Circulating tumor cells (CTCs) are of recognized importance for diagnosis and prognosis of cancer patients. With melanoma, most studies do not show any clear relationship between CTC levels and stage of disease. Here, CTCs were enriched (∼400X) from blood of melanoma patients using a simple centrifugation device (OncoQuick), and 4 melanocyte target RNAs (TYR, MLANA, MITF, and MIF) were quantified using QPCR. Approximately one-third of melanoma patients had elevated MIF and MLANA transcripts (p<0.0001 and p<0.001, respectively) compared with healthy controls. In contrast, healthy controls had uniformly higher levels of TYR and MITF than melanoma patients (p<0.0001). There was a marked shift of leukocytes into the CTC-enriched fractions (a 430% increase in RNA recovery, p<0.001), and no relationship between CTC levels and stage of disease was found. CTCs were captured on microfabricated filters and cultured. Captured melanoma CTCs were large cells, and consisted of 2 subpopulations, based on immunoreactivity. One subpopulation (∼50%) stained for both pan-cytokeratin (KRT) markers and the common leukocyte marker CD-45, whereas the second subpopulation stained for only KRT. Since similar cells are described in many cancers, we also examined blood from colorectal and pancreatic cancer patients. We observed analogous results, with most captured CTCs staining for both CD-45/KRT markers (and for the monocyte differentiation marker CD-14). Our results suggest that immature melanocyte-related cells (expressing TYR and MITF RNA) may circulate in healthy controls, although they are not readily detectable without considerable enrichment. Further, as early-stage melanomas develop, immature melanocyte migration into the blood is somehow curtailed, whereas a significant proportion of patients develop elevated CTC levels (based on MIF and MLANA RNAs). The nature of the captured CTCs is consistent with literature describing leukocyte/macrophage-tumor cell fusion hybrids, and their role in metastatic progression.

Novel biomarkers and therapeutic targets for optimizing the therapeutic management of melanomas

Cutaneous malignant melanoma is the most aggressive form of skin cancer with an extremely poor survival rate for the patients diagnosed with locally invasive and metastatic disease states. Intensive research has led in last few years to an improvement of the early detection and curative treatment of primary cutaneous melanomas that are confined to the skin by tumor surgical resection. However, locally advanced and disseminated melanomas are generally resistant to conventional treatments, including ionizing radiation, systemic chemotherapy, immunotherapy and/or adjuvant stem cell-based therapies, and result in the death of patients. The rapid progression of primary melanomas to locally invasive and/or metastatic disease states remains a major obstacle for an early effective diagnosis and a curative therapeutic intervention for melanoma patients. Importantly, recent advances in the melanoma research have led to the identification of different gene products that are often implicated in the malignant transformation of melanocytic cells into melanoma cells, including melanoma stem/progenitor cells, during melanoma initiation and progression to locally advanced and metastatic disease states. The frequent deregulated genes products encompass the oncogenic B-RafV600E and N-RasQ61R mutants, different receptor tyrosine kinases and developmental pathways such as epidermal growth factor receptor (EGFR), stem cell-like factor (SCF) receptor KIT, hedgehog, Wnt/β-catenin, Notch, stromal cell-derived factor-1 (SDF-1)/CXC chemokine receptor-4 (CXCR4) and vascular endothelial growth factor (VEGF)/VEGFR receptor. These growth factors can cooperate to activate distinct tumorigenic downstream signaling elements and epithelial-mesenchymal transition (EMT)-associated molecules, including phosphatidylinositol 3’-kinase (PI3K)/Akt/ molecular target of rapamycin (mTOR), nuclear factor-kappaB (NF-κB), macrophage inhibitory cytokine-1 (MIC-1), vimentin, snail and twist. Of therapeutic relevance, these deregulated signal transduction components constitute new potential biomarkers and therapeutic targets of great clinical interest for improving the efficacy of current diagnostic and prognostic methods and management of patients diagnosed with locally advanced, metastatic and/or relapsed melanomas.

Finding the root of the problem: the quest to identify melanoma stem cells

Melanoma is an exceptionally aggressive cancer with limited treatment options. As such, the idea that a minority of tumor cells, termed melanoma stem cells, are actually responsible for the progression of the disease offers up new possibilities for targeted therapies. However, reliable identification of these melanoma stem cells is complicated by the lack of clearly defined markers to distinguish them from the general tumor cell population. Additionally, there is evidence that under permissive conditions, a high proportion of melanoma cells are capable of forming tumors in mice. This review summarizes a number of the possible markers being considered for identifying melanoma stem cells, the potential role of transcription factors that regulate pluripotency and stem cell maintenance in melanoma, and evidence that may undermine the applicability of the cancer stem cell hypothesis to melanoma.

Negative enrichment by immunomagnetic nanobeads for unbiased characterization of circulating tumor cells from peripheral blood of cancer patients

BACKGROUND

A limitation of positive selection strategies to enrich for circulating tumor cells (CTCs) is that there might be CTCs with insufficient expression of the surface target marker which may be missed by the procedure. We optimized a method for enrichment, subsequent detection and characterization of CTCs based on depletion of the leukocyte fraction.

METHODS

The 2-step protocol was developed for processing 20 mL blood and based on red blood cell lysis followed by leukocyte depletion. The remaining material was stained with the epithelial markers EpCAM and cytokeratin (CK) 7/8 or for the melanoma marker HMW-MAA/MCSP. CTCs were detected by flow cytometry. CTCs enriched from blood of patients with carcinoma were defined as EpCAM+CK+CD45-. CTCs enriched from blood of patients with melanoma were defined as MCSP+CD45-. One-hundred-sixteen consecutive blood samples from 70 patients with metastatic carcinomas (n = 48) or metastatic melanoma (n = 22) were analyzed.

RESULTS

CTCs were detected in 47 of 84 blood samples (56%) drawn from carcinoma patients, and in 17 of 32 samples (53%) from melanoma patients. CD45-EpCAM-CK+ was detected in pleural effusion specimens, as well as in peripheral blood samples of patients with NSCLC. EpCAM-CK+ cells have been successfully cultured and passaged longer than six months suggesting their neoplastic origin. This was confirmed by CGH. By defining CTCs in carcinoma patients as CD45-CK+ and/or EpCAM+, the detection rate increased to 73% (61/84).

CONCLUSION

Enriching CTCs using CD45 depletion allowed for detection of epithelial cancer cells not displaying the classical phenotype. This potentially leads to a more accurate estimation of the number of CTCs. If detection of CTCs without a classical epithelial phenotype has clinical relevance need to be determined.

Melanoma stem cells: not rare, but well done

Since the identification of self-renewing cells in the hematopoietic system, stem cells have transformed the study of medicine. Cancer biologists have identified stem-like cells in multiple malignancies, including those of solid organs. This has led to the development of a stem cell theory of cancer, which purports that a subpopulation of self-renewing tumor cells is responsible for tumorigenesis. This contrasts with the stochastic model of tumor development, which advances that all tumor cells are capable of tumor formation. Within the field of melanoma, the identity and existence of cancer stem cells has been the subject of recent debate. Much of the controversy may be traced to differences in interpretations and definitions related to the cancer stem cell theory, and the use of dissimilar methodologies to study melanoma cells. Accumulating evidence suggests that cancer stem cells may exist in melanoma, although their frequency may vary and they may be capable of phenotypic plasticity. Importantly, these primitive melanoma cells are not only capable of self-renewal and differentiation plasticity, but also may confer virulence via immune evasion and multidrug resistance, and potentially via vasculogenic mimicry and transition to migratory and metastasizing derivatives. Therapeutic targeting of melanoma stem cells and the pathways that endow them with virulence hold promise for the design of more effective strategies for amelioration and eradication of this most lethal form of skin cancer.

SOX2 and nestin expression in human melanoma: an immunohistochemical and experimental study

SOX2 is an embryonic neural crest stem-cell transcription factor recently shown to be expressed in human melanoma and to correlate with experimental tumor growth. SOX2 binds to an enhancer region of the gene that encodes for nestin, also a neural progenitor cell biomarker. To define further the potential relationship between SOX2 and nestin, we examined co-expression patterns in 135 melanomas and 37 melanocytic nevi. Immunohistochemical staining in 27 melanoma tissue sections showed an association between SOX2 positivity, spindle cell shape and a peripheral nestin distribution pattern. In contrast, SOX2-negative cells were predominantly epithelioid, and exhibited a cytoplasmic pattern for nestin. In tissue microarrays, co-expression correlated with tumor progression, with only 11% of nevi co-expressing SOX2 and nestin in contrast to 65% of metastatic melanomas, and preliminarily, with clinical outcome. Human melanoma lines that differentially expressed constitutive SOX2 revealed a positive correlation between SOX2 and nestin expression. Experimental melanomas grown from these respective cell lines in murine subcutis and dermis of xenografted human skin maintained the association between SOX2-positivity, spindle cell shape, and peripheral nestin distribution. Moreover, the cytoplasmic pattern of nestin distribution was observed in xenografts generated from SOX2-knockdown A2058 melanoma cells, in contrast to the peripheral nestin pattern seen in tumors grown from A2058 control cells transfected with non-target shRNA. In aggregate, these data further support a biologically significant linkage between SOX2 and nestin expression in human melanoma.

Immune-related biomarkers for diagnosis/prognosis and therapy monitoring of cutaneous melanoma

Skin melanoma, a life-threatening disease, has a recently reported worldwide increase in incidence, despite primary prevention. Skin melanoma statistics emphasize the need for finding markers related to the immune response of the host. The mechanisms that are able to over-power the local immune surveillance comprise molecules that can be valuable markers for diagnosis and prognosis. This article summarizes the immune markers that can monitor the disease stage and evaluate the efficacy of therapeutic interventions. Recent data regarding immunotherapy are presented in the context of tumor escape from immune surveillance and the immune molecules that are both targets and a means of monitoring. Perspectives for developing immune interventions for skin melanoma management and the position of tissue or soluble immune markers as a diagnostic/prognostic panel are evaluated. State-of-the-art technology is emphasized for developing immune molecular signatures for a complex characterization of the patient's immunological status.

Nestin in gastrointestinal and other cancers: Effects on cells and tumor angiogenesis

Nestin is a class VI intermediate filament protein that was originally described as a neuronal stem cell marker during central nervous system (CNS) development, and is currently widely used in that capacity. Nestin is also expressed in non-neuronal immature or progenitor cells in normal tissues. Under pathological conditions, nestin is expressed in repair processes in the CNS, muscle, liver, and infarcted myocardium. Furthermore, increased nestin expression has been reported in various tumor cells, including CNS tumors, gastrointestinal stromal tumors, pancreatic cancer, prostate cancer, breast cancer, malignant melanoma, dermatofibrosarcoma protuberances, and thyroid tumors. Nestin is reported to correlate with aggressive growth, metastasis, and poor prognosis in some tumors; however, the roles of nestin in cancer cells have not been well characterized. Furthermore, nestin is more specifically expressed in proliferating small-sized tumor vessels in glioblastoma and gastric, colorectal, and prostate cancers than are other tumor vessel markers. These findings indicate that nestin may be a marker for newly synthesized tumor vessels and a therapeutic target for tumor angiogenesis. It has received a lot of attention recently as a cancer stem cell marker in various cancer cells including brain tumors, malignant rhabdoid tumors, and uterine, cervical, prostate, bladder, head and neck, ovarian, testicular, and pancreatic cancers. The purpose of this review is to clarify the roles of nestin in cancer cells and in tumor angiogenesis, and to examine the association between nestin and cancer stem cells. Nestin has the potential to serve as a molecular target for cancers with nestin-positive cancer cells and nestin-positive tumor vasculature.