Type VII collagen antibody LH 7.2 identifies basement membrane characteristics of thin malignant melanomas

Understanding the pathogenesis of recessive dystrophic epidermolysis bullosa squamous cell carcinoma

Patients with recessive dystrophic epidermolysis bullosa develop numerous life-threatening skin cancers. The reasons for this remain unclear. Parallels exist with other scarring skin conditions, such as Marjolin ulcer. We summarize observational and experimental data and discuss proposed theories for the development of such aggressive skin cancers. A context-driven situation seems to be emerging, but more focused research is required to elucidate the pathogenesis of epidermolysis bullosa-associated squamous cell carcinoma.

Role of cancer microenvironment in metastasis: focus on colon cancer

One person on three will receive a diagnostic of cancer during his life. About one third of them will die of the disease. In most cases, death will result from the formation of distal secondary sites called metastases. Several events that lead to cancer are under genetic control. In particular, cancer initiation is tightly associated with specific mutations that affect proto-oncogenes and tumour suppressor genes. These mutations lead to unrestrained growth of the primary neoplasm and a propensity to detach and to progress through the subsequent steps of metastatic dissemination. This process depends tightly on the surrounding microenvironment. In fact, several studies support the point that tumour development relies on a continuous cross-talk between cancer cells and their cellular and extracellular microenvironments. This signaling cross-talk is mediated by transmembrane receptors expressed on cancer cells and stromal cells. The aim of this manuscript is to review how the cancer microenvironment influences the journey of a metastatic cell taking liver invasion by colorectal cancer cells as a model.

Immunomagnetic detection and clinical significance of micrometastatic tumor cells in malignant melanoma patients

PURPOSE

Positive associations between the presence of micrometastatic tumor cells and disease aggressiveness have been reported in several tumor types, but the clinical implications are still not established. We wanted to test a new, sensitive immunomagnetic detection method on bone marrow (BM) and peripheral blood (PB) samples from patients with malignant melanoma and relate the findings to clinical outcome.

EXPERIMENTAL DESIGN

Samples from 210 patients admitted for relapse of cutaneous melanoma were examined. Mononuclear cell fractions isolated from BM and PB were incubated with superparamagnetic particles coated with antimelanoma antibodies. Live tumor cells with bound beads were isolated with a magnet and identified in a microscope as cell-bead rosettes. Beads without antibody or with an irrelevant antibody were used as controls. The whole procedure was completed within 2-3 h. The identity of the cells was confirmed with a new double labeling procedure with fluorescent microparticles.

RESULTS

Rosetted melanoma cells were found in BM aspirates of 35 of 186 (19%) patients, but in only 2 of 208 (1%) PB samples. The controls were all negative. After a median observation time of 1.1 year (range, 0-6.8 years), patients with tumor cells in BM showed a significantly shorter overall survival from time of BM aspiration (P = 0.009). In multiple regression analysis, a positive BM test was a strong indicator of overall survival (P = 0.021), associated with disease stage (American Joint Committee on Cancer) and with the number of metastatic sites, but not with the primary (Breslow) tumor depth and morphology.

CONCLUSIONS

The results demonstrate the prognostic significance of detecting BM micrometastasis in melanoma patients. The results strengthen the validity of the immunobead technique. In contrast to other techniques, the method identifies intact, live tumor cells that can be further characterized, making the assay attractive for extended use.

Identification of histological features associated with metastatic potential in thin (<1.0 mm) cutaneous melanoma with metastases. A study on behalf of the EORTC Melanoma Group

Contrary to expectations, a small number of thin (<1 mm) melanomas do metastasize. This collaborative study was performed in an attempt to identify the morphological basis of such aggressive behaviour. Regression was expected to be the explanation for the lack of thickness in some cases. Whether a vertical growth phase (VGP) was present in the remainder was carefully assessed. A pilot study had identified two other patterns associated with metastasis in thin melanomas. These were termed 'junctional expansion nodules' and 'melanomatous follicular invasion'. Both were seen in the absence of other dermal invasion. These two patterns were included in the study, which comprised 54 cases and 56 controls, which were thin melanomas which had not metastasized 5 years after excision. Regression was present in 50% of test cases (30.4% in controls, p=0.036) and VGP was present in 59.3% of cases and 48.2% of controls. The thinnest metastasizing melanoma without regression was 0.27 mm. Eight (14.8%) cases, however, had metastasized but showed neither regression nor VGP; seven of these showed a junctional expansion nodule, present in only three controls (p=0.016). Five of these seven also showed melanomatous follicular invasion. One of these five showed this follicular involvement without a junctional nodule. Melanomatous follicular invasion was not seen in the control cases (p=0.012). Mitoses were seen in the VGP of both test and control cases, but high counts (>3 per mm(2)) were much more common in the metastasizing lesions (p=0.007). These findings support the idea that in most cases, regression and/or a VGP are required for metastasis to occur. However, a small number of thin melanomas without these features, as conventionally described, still metastasize. This implies that VGP may require redefinition and that junctional expansion nodules and melanomatous follicular invasion may be variants of VGP.

Penetration of human metastatic melanoma cells through an authentic dermal-epidermal junction is associated with dissolution of native collagen types IV and VII

The events occurring during the penetration of melanoma cells through the dermal-epidermal junction, which is the first crucial step in the process of metastasis, are poorly understood, partly because no suitable tissue models exist. In the in vitro model reported here, two melanoma clones (T1C3, which generates lung metastases in experimental animals, and IC8, which does not) derived from a single parental cell line were co-seeded with normal allogenic keratinocytes onto acellular human de-epidermized dermis with preserved intact basement membrane and cultured for up to 1 month at an air-liquid interface. Histological, immunohistochemical and ultrastructural studies showed that melanoma cells from the metastatic clone (T1C3), but not from the non-metastatic clone (IC8), penetrated the dermal-epidermal junction to invade the dermis after 3 weeks of culture. Local invasion was associated with the dissolution of the native epidermal basement membrane collagens type IV and VII. Confocal laser scanning microscopy analysis demonstrated that numerous T1C3 cells were able to colonize the interstitial dermis and to rapidly penetrate empty dermal cavities. Our model represents a significant technical advance over others currently available since: (i) the organized three-dimensional architecture of the native dermal-epidermal junction is preserved; (ii) the active invasion process coincides with the dissolution of native components of the epidermal basement membrane, i.e. collagen types IV and VII; and (iii) the ability of melanoma cells to cross the dermal-epidermal junction correlates with their metastatic potential. This model provides a valuable tool for the study of the time-course of the cellular and molecular events that occur during the earliest steps of invasion in cutaneous melanoma. It also offers new opportunities to study the possible role of the keratinocyte environment in melanoma invasion.

Modified basement membrane composition during bronchopulmonary tumor progression

During tumor progression, the extracellular matrix (ECM) and particularly the basement membrane (BM) appear to be dynamic structures that are not only degraded but also deposited around tumor clusters. In this study we examined by immunohistochemistry the localization of three chains of Type IV collagen (alpha1, alpha3 and alpha5), Type VII collagen, and laminin 5 at different stages of bronchopulmonary cancers. In normal tissues, alpha1(IV) chain was detected in all BMs (bronchial, vascular, alveolar, and glandular), alpha5(IV) chain was present only in vascular BM, and laminin 5 and Type VII collagen were co-localized in bronchial and glandular BMs, whereas alpha3(IV) immunolabeling was totally absent from normal bronchi. In well-differentiated carcinomas, alpha3(IV) chain staining was found in some neosynthetized BMs interfacing the tumor cell and the stromal compartment, contrasting with the total absence of labeling in normal tissues. alpha1(IV) chain showed strong reactivity in all BM. Laminin 5 and Type VII collagen were also detected in neosynthetized BM. In poorly differentiated invasive cancers, alpha3(IV) chain and Type VII collagen were not found, whereas laminin 5 and alpha1(IV) chain persisted. The most important modifications in BM composition during tumor progression therefore appear to be the appearance of the alpha3 (IV) chain in well-differentiated carcinomas and its subsequent disappearance in poorly differentiated carcinomas, together with the loss of type VII collagen. alpha5(IV) chain distribution was restricted in vascular BM of well- and poorly differentiated carcinomas. These results show that the composition of BM is modified during the progression of bronchopulmonary tumor, emphasizing that the BM represents a dynamic element in tumor progression and has an important role in tumor cell invasiveness.

Matrix metalloproteinase-2 (72 kD type IV collagenase) expression occurs in the early stage of human melanocytic tumour progression and may have prognostic value

Matrix metalloproteinase-2 (MMP-2), a member of the matrix metalloproteinase family, participates in degradation of the pericellular and extracellular matrix during neoplastic growth and metastasis. Experimental data have substantiated its role in melanoma invasion, but there is no information at present concerning its expression in histological specimens from human melanocytic tumors. This study describes the occurrence and immunolocalization of MMP-2 in human melanocytic lesions, defining distinct steps in melanoma progression. Paraffin-embedded sections from 118 melanocytic lesions were immunostained using a specific antibody to 72 kD type IV collagenase. The material included 34 common naevocellular naevi, 14 dysplastic naevi, 21 in situ melanomas, 20 primary malignant melanomas, and 29 melanoma metastases. Intracytoplasmic MMP-2 immunoreactive protein was found in the 'naevocytic nests' of common naevi, in junctional naevus cells, and in melanoma cells. The surrounding normal skin stained negatively, except for occasional macrophages, sweat glands, and hair follicles. The number of MMP-2-positive cells increased with decreasing architectural organization and increasing atypia in the melanocytic lesions. The MMP-2 positivity in the primary and subcutaneous melanoma lesions correlated with later haematogenous metastasis. The data suggest that MMP-2 expression is an early event in melanocytic tumour progression, but is nevertheless prognostic for haematogenous metastasis in melanoma.

The borderline: basement membranes and the transition from premalignant to malignant neoplasia

In this paper, the use of immunohistochemistry for the analysis of basement membrane components and related extracellular matrix proteins in human cancer is reviewed. Basement membranes in cancer are dynamic structures that are constantly degraded but also deposited, in close collaboration between tumor cells and stromal cells. Basement membrane immunohistochemistry, using antibodies against type IV collagen and laminin, appears to be a useful tool in the analysis of lesions on the borderline between premalignant and malignant. Basement membrane interruptions, however, cannot be used as the only criterion for the diagnosis of malignancy. Type VII collagen is often degraded prior to type IV collagen and laminin in early invasion. This protein also tends to be expressed in carcinomas when it is not found in the corresponding normal tissue. Tenascin seems to play a complex role in the development of human tumors, including promotion of cell growth and differentiation, cell migration during invasion, and tissue remodeling during the development of primary and metastatic lesions. Further systemic exploration of extracellular matrix molecules in neoplasms should yield new information relevant for cancer biologists and useful in cancer diagnosis.

Patterns and composition of basement membranes in colon adenomas and adenocarcinomas

We studied the distribution of type IV collagen and type VII collagen in the basement membranes of normal mucosa of the colon, adenomas, and adenocarcinomas using immunoperoxidase and immunofluorescence techniques. In normal mucosa, we found regular type IV collagen-positive basement membranes, lining vascular structures and mucosal epithelia. These basement membranes, however, lacked type VII collagen. In adenomas of the colon, intact basement membranes were observed through type IV collagen staining. Type VII collagen staining was also detected, but only in connection with dysplastic epithelium. Adjacent to the dysplastic epithelium in adenomas, histologically normal epithelium also showed type VII collagen staining along the basement membrane, but this was restricted to the epithelium of the luminal surface. These areas were also investigated for expression of keratins 8, 18, and 19, and keratins 5 and 8 (monoclonal antibodies NCL-5D3 and RCK 102, respectively), but altered differentiation was not detected using this technique. In adenocarcinomas of the colon, type IV collagen was irregularly deposited in the basement membrane of neoplastic tubules. Type VII collagen staining was detected only in well or moderately differentiated carcinomas and in higher amounts. Our findings therefore reveal a transient expression of type VII collagen in the transition of dysplastic epithelium into carcinoma, suggesting the involvement of type VII collagen in the process of early invasion.

Cryofixed, freeze-dried and paraffin-embedded skin enables successful immunohistochemical staining of skin basement membrane antigens

Conventional chemical fixation and paraffin-embedding procedures give good preservation of morphology, although the antigenicity of many proteins in the tissue sample is destroyed. On the other hand, fresh frozen sections can preserve the antigenicity, but provide poor morphological preservation. To overcome this dilemma, cryofixation and freeze drying were used on human skin tissue, applying methodology which has only been used to study lymphoid tissue. First, fresh human skin was cryofixed in liquid isopentane (-160 degrees C) cooled by liquid nitrogen. The skin was then freeze-dried at -40 degrees C and 10(-2) atmospheric pressure for 72 h, followed by embedding in paraffin. Sections 4 microns thick taken from this cryofixed, freeze-dried, and paraffin-embedded skin were stained with hematoxylin-eosin or used for immunolabeling with antibodies against basement membrane antigen, including type IV and type VII collagen, bullous pemphigoid antigen, epidermolysis bullosa acquisita antigen, and GB3 antigen. The morphological preservation of these sections was as good as that of routine formalin-fixed and paraffin-embedded skin sections. The basement membrane was clearly immunostained with all antibodies used, and the intensity of the reaction was as strong as that seen in frozen sections. Evaluation of antigen distribution in conjunction with the detailed skin structure was therefore possible in the same sections.

Breslow thickness of cutaneous malignant melanoma in paraffin wax and frozen sections

Breslow tumour thickness was measured in frozen and paraffin wax sections from 21 excision biopsies of cutaneous malignant melanomas by two observers. There was no consistent variation between frozen and paraffin wax sections, with recorded differences ranging from +0.3 mm to -0.2 mm. Interobserver differences ranged from +0.4 mm to -0.2 mm. The interobserver variations exceeded the intraobserver variations, but neither were significant. These findings show conclusively that, when using high quality frozen sections, there is no significant difference between Breslow thickness measured in frozen or paraffin wax sections and therefore that frozen sections can be used to microstage melanoma. Interobserver variations seem to be a more likely source of erroneous measurements of tumour thickness.