The desmoplastic response: induction of collagen synthesis by melanoma cells in vitro

Proline Dehydrogenase/Proline Oxidase (PRODH/POX) Is Involved in the Mechanism of Metformin-Induced Apoptosis in C32 Melanoma Cell Line

The role of proline dehydrogenase/proline oxidase (PRODH/POX) in the mechanism of antineoplastic activity of metformin (MET) was studied in C32 melanoma cells. PRODH/POX is a mitochondrial enzyme-degrading proline that is implicated in the regulation of cancer cell survival/apoptosis. The enzyme is activated by AMP kinase (AMPK). It has been found that MET induced a significant decrease in cell viability and DNA biosynthesis accompanied by an increase in the expressions of AMPK and PRODH/POX in C32 cells. The mechanism for MET-dependent cytotoxicity on C32 cells was found at the level of PRODH/POX-induced ROS generation and activation of Caspase-3 and Caspase-9 expressions in these cells. The effects were not observed in MET-treated PRODH/POX knock-out C32 cells. Of interest is an MET-dependent increase in the concentration of proline, which is a substrate for PRODH/POX. This phenomenon is due to the MET-dependent inhibition of collagen biosynthesis, which is the main proline-utilizing process. It has been found that the underlying mechanism of anticancer activity of MET involves the activation of AMPK, PRODH/POX, increase in the cytoplasmic concentration of proline, inhibition of collagen biosynthesis, and stimulation of PRODH/POX-dependent ROS generation, which initiate the apoptosis of melanoma cells.

Morphologic and gene expression analysis of periodontal ligament fibroblasts subjected to pressure

INTRODUCTION

Force application (FA) during orthodontic tooth movement is mediated through periodontal ligament (PDL) fibroblasts. FA on deciduous teeth has an inherent risk of root resorption, which is less in permanent teeth. Currently, the root resorption mechanism is poorly understood. We hypothesized that FA alters the morphology and gene expression of PDL fibroblasts. This study was designed to achieve homogenous PDL fibroblast cultures, establish an in-vitro FA model, analyze fibroblast morphology after FA, and compare the gene expressions of PDL fibroblasts of deciduous and permanent teeth after FA.

METHODS

Fibroblasts were sorted from primary cultures of deciduous and permanent tooth PDLs. Cell viability was evaluated in the Opticell (Thermo Scientific, Waltham, Mass) FA model. Cellular morphology was analyzed using immunofluorescence staining for actin and focal adhesion complexes. Gene expressions of untreated or pressure-treated PDL fibroblasts of deciduous and permanent teeth were compared by gene array and confirmed by real-time polymerase chain reaction.

RESULTS

Cell sorting resulted in cultures containing 98% of PDL fibroblasts. The Opticell model showed 94% cell survival after FA. FA increased fibroblasts' adhesion. Gene arrays and real-time polymerase chain reactions indicated greater up-regulation of DKK2 mRNA in untreated PDL fibroblasts of deciduous teeth and greater up-regulation of ADAMTS1 mRNA in pressurized PDL fibroblasts of deciduous and permanent teeth.

CONCLUSIONS

Cell sorting is an efficient method to establish homogenous PDL fibroblast cultures. Using the Opticell FA model allows the maintenance of excellent cell viability. FA increased the surface adherence of fibroblasts. Up-regulation of ADAMTS1 after FA may indicate its involvement in the remodeling of the periodontium during orthodontic tooth movement. Understanding root resorption mechanisms under FA will help to prevent it during orthodontic treatment.

Desmoplastic Melanoma of the Head and Neck: Histopathologic and Immunohistochemical Study of 28 Cases

Studies of the immunohistochemical profiles and clinical course of desmoplastic melanoma have produced conflicting results. We identified 28 cases of desmoplastic melanoma after a search of our files for spindle cell neoplasms of the head and neck from 1960 through 1995. The 17 male (61%) and 11 female (39%) patients averaged 65 years of age. The cheek was the most common location (12 cases, 43%). The average length of follow-up was 5 years. Overall 5-year survival rate was 46%. Melan A and tyrosinase positivity (P = 0.0195), smooth muscle actin positivity (P = 0.0328), tumor size (P = 0.0297), and tumor thickness (P = 0.0419) were significantly associated with local progression-free survival. No histologic or immunohistochemical marker was associated with overall or metastasis-free survival.

Melanoma: Clinical Presentations

The malignant cell in melanoma is the melanocyte. Because melanocytes are located in the basal layer of the epidermis, melanoma is most commonly seen on the skin. However, melanoma can also arise on mucosal surfaces such as the oral cavity, the upper gastrointestinal mucosa, the genital mucosa, as well as the uveal tract of the eye and leptomeninges. Melanomas tend to be pigmented but can also present as pink or red lesions. They can mimic benign or other malignant skin lesions. This chapter presents the spectrum of typical and less typical presentations of melanoma, as well as patterns of spread. It is divided into (1) cutaneous lesions; (2) patterns of regional spread, (3) non-cutaneous lesions; and (4) distant metastases.

Chronic Myelogenous Leukemia Cells Contribute to the Stromal Myofibroblasts in Leukemic NOD/SCID Mouse In Vivo

We recently reported that chronic myelogenous leukemia (CML) cells converted into myofibroblasts to create a microenvironment for proliferation of CML cells in vitro. To analyze a biological contribution of CML-derived myofibroblasts in vivo, we observed the characters of leukemic nonobese diabetes/severe combined immunodeficiency (NOD/SCID) mouse. Bone marrow nonadherent mononuclear cells as well as human CD45-positive cells obtained from CML patients were injected to the irradiated NOD/SCID mice. When the chimeric BCR-ABL transcript was demonstrated in blood, human CML cells were detected in NOD/SCID murine bone marrow. And CML-derived myofibroblasts composed with the bone marrow-stroma, which produced significant amounts of human vascular endothelial growth factor A. When the parental CML cells were cultured with myofibroblasts separated from CML cell-engrafted NOD/SCID murine bone marrow, CML cells proliferated significantly. These observations indicate that CML cells make an adequate microenvironment for their own proliferation in vivo.

The molecular basis of melanomagenesis and the metastatic phenotype

The last two decades have seen spectacular advances in our understanding of the biology of melanoma and, in particular, have elucidated the mechanisms operative in disease initiation and progression. With respect to the former, the genetics of melanoma and in particular the impact of genetic defects on dysregulation of the cell cycle are key issues in malignant transformation and are a major focus of this review. With respect to the latter, consideration also is given to the acquisition of growth factor autonomy and the capacity for invasion and metastasis from the standpoint of cell adhesion, motility, and matrix digestion. These events have specific morphologic correlates that will be briefly addressed. Where relevant, we will address certain of the modern pharmacogenetic strategies that flow from these novel observations concerning melanoma biology.

Characterization of human lung tumor-associated fibroblasts and their ability to modulate the activation of tumor-associated T cells

The tumor microenvironment of human non-small cell lung cancer (NSCLC) is composed largely of stromal cells, including fibroblasts, yet these cells have been the focus of few studies. In this study, we established stromal cell cultures from primary NSCLC through isolation of adherent cells. Characterization of these cells by flow cytometry demonstrated a population which expressed a human fibroblast-specific 112-kDa surface molecule, Thy1, alpha-smooth muscle actin, and fibroblast activation protein, but failed to express CD45 and CD11b, a phenotype consistent with that of an activated myofibroblast. A subset of the tumor-associated fibroblasts (TAF) was found to express B7H1 (PD-L1) and B7DC (PD-L2) constitutively, and this expression was up-regulated by IFN-gamma. Production of cytokines and chemokines, including IFN-gamma, monokine induced by IFN-gamma, IFN-gamma-inducible protein-10, RANTES, and TGF-beta1 was also demonstrated in these cells. Together, these characteristics provide multiple opportunities for the TAF to influence cellular interactions within the tumor microenvironment. To evaluate the ability of TAF to modulate tumor-associated T cell (TAT) activation, we conducted coculture experiments between autologous TAF and TAT. In five of eight tumors, TAF elicited a contact-dependent enhancement of TAT activation, even in the presence of a TGF-beta1-mediated suppressive effect. In the three other tumors, TAF had a net suppressive effect upon TAT activation, and, in one of these cases, blockade of B7H1 or B7DC was able to completely abrogate the TAF-mediated suppression. We conclude that TAF in human NSCLC are functionally and phenotypically heterogeneous and provide multiple complex regulatory signals that have the potential to enhance or suppress TAT function in the tumor microenvironment.

Procollagen 1 ? a marker of fibroblastic and fibrohistiocytic skin tumors

BACKGROUND

When dealing with tumors of presumed fibroblastic or fibrohistiocytic origin, immunohistochemistry is traditionally done to exclude a tumor of non-fibroblastic or non-fibrohistiocytic nature, because a reliable marker of fibroblastic or fibrohistiocytic cell origin is still to be introduced. This study investigates whether procollagen 1 is a useful marker of skin tumors composed of cells derived from fibroblasts or fibrohistiocytes.

MATERIALS AND METHODS

Twenty-nine different types of skin tumors, including tumors composed of spindle cells as well as some additional epithelial and melanocytic tumors, were stained immunohistochemically with antibodies against procollagen 1. The total number of cases tested was 154.

RESULTS

Tumors composed of cells of fibroblastic or fibrohistiocytic origin in general showed a high expression of procollagen 1, whereas tumors composed of non-fibroblastic cells in general showed no expression. However, there were a few exceptions, e.g., leiomyosarcoma and desmoplastic melanoma.

CONCLUSIONS

The study suggests that immunohistochemical staining for procollagen 1 is a valuable marker for skin tumors composed of spindle cells derived from fibroblasts or fibrohistiocytes. However, in cases of spindle cell tumors with a morphology suggesting malignancy, it is recommended to use a panel of antibodies, which besides procollagen 1 includes markers such as S100, CD68, CD34, h-caldesmon, and pancytokeratin.

Assessment of the role of sentinel lymph node biopsy for primary cutaneous desmoplastic melanoma

BACKGROUND

The role of sentinel lymph node biopsy (SLNB) in the treatment of desmoplastic melanoma (DM) remains undefined. The purpose of this study was to evaluate the use of SLNB for DM.

METHODS

In all, 1850 patients with cutaneous melanoma underwent wide local excision and SLNB. Patients with DM were identified and stratified as 'pure' DM or 'mixed' DM (i.e., DM associated with at least one other common histologic subtype).

RESULTS

Of the 1850 patients, 65 (3.5%) had DM. Of these, 46 (70.8%) had pure DM and 19 (29.2%) had mixed DM. Patients with pure DM had a median tumor thickness of 3.5 mm and 6.5% were ulcerated. Compared with patients with pure DM, patients with either mixed DM or non-DM (n = 1785) had thinner primary tumors (median, 1.7 mm and 1.5 mm, respectively, each P < 0.001 vs. pure DM) that were more likely to be ulcerated (27.7% and 21.3%, respectively, each P < 0.05 vs. pure DM). Although the incidence of a positive SLN was similar in patients with mixed DM (15.8%) and non-DM (17.5%), patients with pure DM were less likely to have a positive SLN (2.2%) (each P < 0.01 vs. non-DM and mixed DM). At a median follow-up of 2.9 years, no patient with pure DM had recurred.

CONCLUSIONS

Despite having thicker primary tumors, patients with pure DM have a lower incidence of positive SLNs compared with patients with non-DM. Whereas the treatment approach for patients with mixed DM should be similar to that of other melanoma patients, patients with pure DM are unlikely to have metastatic disease in regional lymph nodes and SLNB may not be warranted.

Prognosticators of melanoma, the melanoma report, and the sentinel lymph node

Since the 1960s, the clinical characteristics of melanoma, its histopathology and its biological basis have been the subject of intense study at pigmented lesion clinics in North America, Europe, and Australia. More recently, the immense database of the Melanoma Committee of the American Joint Committee on Cancer (AJCC) has been exploited through complex mathematical models to measure the impact of various histologic features of primary melanomas and of sentinel lymph node deposits and to correlate these parameters with patient survival. The wealth of modern information available to pathologists and clinicians has become of vital interest to the prognostication of the individual patient with melanoma. The purpose of this review is to bring to the attention of anatomic pathologists the essential characteristics of the pathology report for primary cutaneous melanoma in the modern era.

Unusual histological variants of cutaneous malignant melanoma with some clinical and possible prognostic correlations

Malignant melanoma is known for the wide range of histological patterns it can assume mimicking other malignant tumors. We present a review of most of the unusual histological variants of cutaneous melanoma and describe their immunohistochemical features, associate clinical findings, and possible behavior related to the histological subtype. In addition, we propose their classification into four groups corresponding to the (1) architectural patterns; (2) cytologic features; (3) stromal changes; and (4) the possible association of these findings (i.e. architectural + cytologic features). Although most of these unusual variants have the same prognosis as conventional melanomas, with Breslow thickness and ulceration, being the most important predictor of survival in clinical stage I, some of them have a peculiar biologic behavior that the clinicians and the dermatopathologists should know in order to give melanoma patients all educational information available.

Cutaneous desmoplastic melanoma

Desmoplastic melanoma (DM) is a fibrosing variant of spindle cell melanoma. It most often presents as an indurated lesion in chronically sun-damaged skin. Due to the lack of characteristic clinical features, early detection is uncommon. At the time of excision, the tumors usually extend into the reticular dermis or deeper. DM is prone to misdiagnosis. It may simulate histologically sclerosing melanocytic nevi as well as various benign and malignant nonmelanocytic lesions. There is significant morphologic variability among tumors classified as DM. Desmoplasia may be prominent throughout the entire tumor ("pure" DM) or represent a portion of an otherwise nondesmoplastic melanoma ("combined" DM). Some tumors show neuroma-like features with prominent nerve involvement, in which case the term "desmoplastic neurotropic melanoma" is used. Immunophenotypically, DMs are usually strongly and homogeneously positive for S-100 protein but are often negative or only focally positive for melanocyte differentiation antigens such as tyrosinase, gp100, Melan-A, and microphthalmia transcription factor. DM differs from conventional melanoma in its clinical course. It is associated with a higher tendency for local recurrence, but metastases to regional lymph nodes are less common. Evidence is also emerging that for patients with thick melanomas, the presence of a paucicellular fibrosing tumor histology (pure DM) is a favorable prognostic factor for survival.

Interactions between human colon carcinoma cells, fibroblasts and monocytic cells in coculture--regulation of cathepsin B expression and invasiveness

To elucidate the importance of the tumor/host interaction in malignant tumors, we investigated the colon carcinoma cell line HT-29 in coculture with monocytic cells (THP-1) and fibroblasts (175BR) for cathepsin B expression and activity. The tumor cells were grown in monolayer cultures or as multicellular tumor spheroids. After coculture, the three cell types were separated by labeled magnetic beads for cathepsin B mRNA and protein analysis. The invasive potential was studied in in vitro invasion assays. The expression level of cathepsin B was found to be 10-fold increased in three dimensional spheroids of HT-29 compared to HT-29 monolayers. The coculture of HT-29 with THP-1 cells and/or human fibroblasts led to a considerable increase in cathepsin B mRNA expression in both tumor and tumor-associated cells. The invasive potential of the tumor cells was 5 times increased by adding monocytic cells to the assay system. This is dependent on the functional activity of cathepsin B as shown by specific siRNA's and seems to be regulated by activation of ERK1/2 and p38 signal transduction pathways.

Application of a clinical grade CD34-mediated method for the enrichment of microvascular endothelial cells from fat tissue

BACKGROUND

Microvascular endothelial cells (MVEC) derived from s.c. fat are seeded on vascular grafts to prevent early occlusion. We have demonstrated the presence of contaminating cells contributing to MVEC seeding-related intimal hyperplasia in MVEC isolates from fat tissue. We found that cell isolates additionally purified after the isolation process, were associated with a reduced thrombogenicity and development of intimal hyperplasia in vitro. A combination of 11Fibrau (F11)- and CD14-coated Dynabeads was used to deplete the contaminating cells, fibroblasts, and monocytes/macrophages. Unfortunately, clinical-grade F11 is not available, and thus cannot be used for clinical practice. CD34 selection with clinical-grade products is widely used for the isolation of hematopoietic progenitors, and endothelial cells (EC) express CD34 on their surfaces. The aims of this study were to test the effectiveness of two different CD34-selection techniques for purification of MVEC, and to compare the results with those of the F11/CD14-method.

METHODS

Liposuction fat was enzymatically digested and centrifuged twice to remove adipocytes and collagenase. CD34 selection was performed using the commercially available methods from Nexell or Miltenyi. Both techniques were modified for our use. The purity after isolation and culture, and recovery were determined by flow-cytometry (CD31-expression) and compared with that of cells purified with the F11/CD14-method.

RESULTS

Besides MVEC, the contaminating fibroblasts and macrophages/monocytes weakly expressed the CD34 Ag. Enrichment of MVEC was not successful with the Miltenyi method. Variations in neither the dose of Ab nor the use of direct selection and different separation programs improved the results. With the Nexell method, MVEC were enriched to 86%, a comparable purity to that obtained with the F11/CD14-method. However, a lower recovery was achieved with the Nexell method.

CONCLUSION

Enrichment of MVEC could be achieved with a modified protocol of the clinical grade CD34(+) selection method from Nexell, but not with the CD34 method from Miltenyi.

Desmoplastic melanoma: a diagnostic trap for the unwary

Desmoplastic melanoma (DM) is an uncommon type of spindle cell melanoma in which the malignant cells are separated by collagen fibres or fibrous stroma. DM is prone to misdiagnosis because of unfamiliarity with its often bland appearance and dissimilarity to other conventional types of melanoma. It displays variable cytological atypia, cellularity and stromal fibrosis and more often than not has an accompanying atypical junctional component. Neurotropism is a common associated feature (in at least 30% of cases) and when it occurs such tumours are termed 'desmoplastic neurotropic melanomas' (DNM). The neurotropism may be perineural or intraneural and often extends beyond the desmoplastic component. In addition, some DMs show evidence of neural differentiation ('neural transformation'). DM may also present as a recurrence or occasionally as a metastasis from other types of melanoma. A high index of suspicion and knowledge of its often subtle morphological appearance are necessary to avoid misdiagnosis.

Desmoplastic hairless hypopigmented naevus: a variant of giant congenital melanocytic naevus

Desmoplasia has been described in melanoma and Spitz naevus but not in giant congenital melanocytic naevus (GCMN). In melanoma desmoplasia is associated with a better survival. Four paediatric patients with hard, ligneous, progressively hypopigmented and alopecic GCMN were seen among 143 cases of GCMN at the Department of Dermatology of the National Institute of Paediatrics, Mexico City. Clinically, induration was progressive in three patients and regressive in one. Pigmentation was regressive in all. Histopathologically, all four patients showed intense dermal fibrosis, scarce naevus cells, and hypotrophic or absent hair follicles. Follow-up and serial biopsies in three patients documented the progressive nature of fibrosis and naevus cell depletion. No evidence of malignant transformation was found. Naevus cell depletion resulted in pigment loss and may have reduced the risk of malignant transformation. Although the cause of fibrosis is unknown, the possibility of an immune reaction to naevus cells is postulated.

Current concepts in the management of patients with melanoma

Melanoma is a significant health problem. Despite public education and free cancer screenings, the incidence and mortality of melanoma continues to rise; however, many currently diagnosed melanomas are thin lesions, suggesting that education and awareness is having an impact. In addition, there are still subsets of patients who need increased surveillance in order to increase their survival. Although large congenital nevi may be precursors of melanoma, small and medium congenital nevi have an insignificant risk for melanoma development. Large congenital nevi, which are axial in location, appear to be more likely to develop melanoma and are associated with melanocytosis and melanoma of the CNS, both of which portend a poor prognosis. Recently, the recommended margins of excision have become more conservative so that many of the surgical defects can be closed primarily. Lymphoscintigraphy and sentinel node biopsy have replaced elective node dissections, thus decreasing the morbidity associated with the surgical management of melanoma. Although controversy still exists as to whether or not sentinel lymph node biopsy alters a patient's prognosis, it has been shown to be a powerful prognostic indicator. Although most melanomas are managed by routine surgical excision, other modalities are sometimes employed. For example, cryosurgery or radiation therapy may be indicated in the frail, elderly individual with a large facial lentigo maligna. Mohs surgery is the treatment of choice for head and neck melanomas and those located in areas where maximum preservation of tissue is required and for desmoplastic and acral lentiginous melanomas. Much more work remains in the area of adjuvant therapy, chemotherapy, and immunotherapy. Dacarbazine remains the drug of choice in disseminated melanoma, but remissions are usually short lived. Interleukin and biochemotherapy has yielded good results but the percentage benefiting is small. Although high dose interferon increases disease-free and overall survival in some patients, it remains a controversial drug which is not easily tolerated. In the new staging system for melanoma, ulceration is second only to Breslow's thickness. In transit (satellite) lesions have also been included in this new system. The new system also recognizes that patients with only microscopic metastatic nodal disease fare better than patients with clinically enlarged metastatic nodes and that it is the number of nodes involved with metastases, not their size, that determines the patient's prognosis. Except for lesions <1mm thick, the Clark's level of invasion has been de-emphasized.

Human renal fibroblast contraction of collagen I lattices is an integrin-mediated process

BACKGROUND

Expression of the beta1 family of integrins allows dermal fibroblasts in wounds to contribute to the healing process through migration, adhesion, synthesis, and rearrangement of extracellular matrix. To date the ability of human renal fibroblasts to reorganize collagens and the role of cell surface receptors in this process remain unknown.

METHODS

Renal fibroblasts were grown from the cortical tissue of surgically removed human kidneys. The ability of human renal fibroblasts to reorganize interstitial collagen I was examined in vitro using solidified collagen I lattices. Integrin function was blocked by incubating fibroblasts with isotype-specific antibodies prior to addition to collagen I lattices.

RESULTS

Human renal fibroblasts embedded in collagen I lattices progressively decreased lattice diameter to 60.6+/-11.4% of initial diameter at 48 h post-release (P:<0.01). Fibroblasts incubated in the presence of antibody to beta1 integrin failed to contract collagen I lattices, whilst fibroblasts incubated with non-specific antibody reduced lattice diameter to 60.1+/-12.4% of initial diameter at 48 h post-release (P:<0.01). Further characterization of integrin alpha subunits showed that blocking alpha2beta1 integrin prevented lattice contraction (P:<0.05, alpha2beta1 integrin antibody vs non-specific antibody), whilst blocking of alpha5beta1, alpha3beta1 and alpha1beta1 integrins did not influence this process.

CONCLUSIONS

We postulate that collagen I fibril rearrangement by human renal fibroblasts in vitro appears to be an integrin-mediated process involving the alpha2beta1 integrin.

Effect of tumor-conditioned medium on intercellular communication and proliferation of Balb/c 3T3 cells

The possible role of tumor cell-derived factors in the regulation of gap junctional intercellular communication and proliferation of fibroblasts was studied in a model system of Balb/c 3T3 cells growing in tumor conditioned medium by Lucifer Yellow CH dye-transfer and BrdU incorporation assays. Six to 24 h incubation of Balb/c 3T3 cells in a medium conditioned by WiDr adenocarcinoma cells enhanced the gap junctional communication between the cells by 25-40% as revealed by intercellular transfer of a fluorescent dye Lucifer Yellow CH. Simultaneously the cell proliferation rates were examined and found to be reduced by 23% at 24 h treatment. Since adenocarcinoma cells are known to secrete different growth factor-like polypeptides into their conditioned medium, we suppose that tumors that produce these molecules might alter their host environment through the enhancement of cell-cell communication thereby facilitating the exchange of modulatory factors.

Desmoplastic malignant melanoma of the palatal alveolar mucosa: sustained disease-free survival after surgery and postoperative radiotherapy

Aggressive surgical and radiotherapeutic management of a patient with desmoplastic malignant melanoma arising from the mucosa of the oral cavity has resulted in disease-free survival of more than 2(1/2) years after diagnosis. This case represents only the tenth reported instance of desmoplastic malignant melanoma arising from the oral cavity and only the third for which survival has exceeded 2 years. Details of the clinical, histopathologic, and therapeutic features of the case are provided to augment the paucity of literature available to clinicians managing this rare disease.

Actin-rich desmoplastic malignant melanoma: report of three cases

We report three cases of desmoplastic malignant melanoma (DMM) rich in smooth muscle actin. They occurred in two men (Cases 1 and 3) and in one woman (Case 2). Cases 1 and 2 were recurrent lesions from common melanomas excised, respectively, 3 and 1 years previously. In Case 3, DMM was associated with lentigo maligna at the time of presentation. Morphologically, DMMs were composed of spindle neoplastic cells organized in haphazardly orientated long fascicles separated by collagen bundles. Perineural invasion was present and mitotic activity was prominent in all cases. The neoplastic spindle cells were intensely positive with S100 protein and smooth muscle actin antisera and negative with HMB45 and Melan-A (Mart-1) antibodies. Double staining for smooth muscle actin and S100 protein revealed no definite coexpression of the two antigens. Follow-up was available for patients 1 and 2 who had local recurrences and are still alive. It is possible that actin rich elements differentiate toward mesenchymal elements, paralleling the phenotypic changes seen in sarcomatoid carcinomas. Therefore, multidirectional differentiation may explain the mesenchymal (sarcomatoid) differentiation of neoplastic melanocytes and may be responsible for the different biologic behavior of DMMs, which is closer to mesenchymal tumors than to conventional melanomas.

Myofibroblasts are responsible for collagen synthesis in the stroma of human hepatocellular carcinoma: an in vivo and in vitro study

BACKGROUND/AIMS

Marked changes in extracellular matrix occur in the stroma of hepatocellular carcinoma, as compared to normal or cirrhotic liver. The cell types responsible for extracellular matrix synthesis within hepatocellular carcinoma have not been clearly identified.

METHODS

In vivo collagen synthesis was studied by in situ hybridization and immunohistochemistry for types I, IV, V and VI collagen, together with immunolabeling of alpha-smooth muscle actin, a myofibroblast marker, and CD34, an endothelial cell marker. In vitro, extracellular matrix deposition by cultured myofibroblasts was studied by reticulin staining, immunocytochemistry and RNase protection.

RESULTS

All collagens studied were expressed in the stroma of the tumor, with a higher level of type VI and IV collagens than of type I and V. The majority of the cells expressing collagen transcripts in human hepatocellular carcinoma stroma were alpha-actin positive and CD 34 negative. In vitro experiments demonstrated that the hepatocellular carcinoma cell lines HepG2, HuH7 and Hep3B markedly increased extracellular matrix deposition by human liver myofibroblasts. This increase was mediated by a soluble mediator present in tumor cell conditioned medium. It was not explained by an increase in mRNA levels of extracellular matrix components, nor by a decrease in the secretion of matrix-degrading proteinases by myofibroblasts.

CONCLUSIONS

Myofibroblasts are the main source of collagens in the stroma of hepatocellular carcinoma. Our data also indicate that tumoral hepatocytes increase extracellular matrix deposition by cultured myofibroblasts, probably by post-transcriptional mechanisms. The generation of hepatocellular carcinoma stroma by myofibroblasts could thus be under control of tumoral cells.

Expression of fibrogenic cytokines in desmoplastic malignant melanoma

Desmoplastic malignant melanoma (DMM) consists of amelanotic spindle-shaped melanoma cells and is accompanied by desmoplasia with fibrous stromata. It has a strong tendency for local infiltrative growth and recurrence and a propensity for neurotropism. It is not yet known which cytokine is responsible for the desmoplasia in DMM. In the present study, we investigated the roles of several fibrogenic cytokines and cytokine receptors in DMM: basic fibroblast growth factor (bFGF), connective tissue growth factor (CTGF), transforming growth factor-beta, platelet-derived growth factor (PDGF) and PDGF receptors. Immunostaining and in situ hybridization were conducted in four cases of DMM and four cases of amelanotic malignant melanoma (AMM) as negative controls for desmoplasia. PDGF-beta receptor, bFGF and CTGF were intensely expressed in the DMM specimens in comparison with the AMM specimens. The reaction of PDGF-B ligand and CTGF to PDGF-beta receptor, in addition to the expression of bFGF, may contribute to the desmoplasia in DMM.

Histologic differentiation of desmoplastic melanoma from cicatrices

Desmoplastic malignant melanoma (DMM) is a rare variant of melanoma that can be very difficult to diagnose correctly both clinically and histologically. The problem is compounded by the fact that many lesions persist at previous biopsy or excision sites so that scar tissue is often present admixed with or adjacent to the spindle cell neoplasm which may exhibit fibroblastic differentiation itself. In order to assess this problem, we compared and contrasted the histologic features of six DMM with 15 examples of cicatrices from various sources. Mature scars were readily differentiated from DMM by light microscopy. In contrast, immature scar and DMM had many features in common including hypercellularity, nodular lymphoid infiltrates, myxoid stroma, and atypical nuclei. The presence of a melanocytic proliferation within the epidermis above the dermal component, neurotropism, and S-100 and/or HMB-45 positivity of neoplastic cells were the only features that permitted reliable differentiation between the two. Clinical correlation and review of previous biopsy specimens are crucial in preventing a delayed diagnosis of DMM. Re-excision is advised in all questionable cases.

Desmoplastic neurotropic melanoma

Desmoplastic neurotropic melanoma (DNM) is a rare variant of a spindle cell melanoma. The majority of these tumors occur on the head and neck of elderly patients. The rather variable clinical appearance (e.g. frequent lack of pigmentation) makes initial diagnosis often difficult. Histologically, DNM may show a lentiginous melanocytic proliferation with atypia and pleomorphic spindle cells in the dermis. Immunostaining for S-100 is usually positive although staining for HMB-45 is frequently absent. As with other melanomas, surgery is the first line treatment for DNM. Unlike other melanomas, however, survival for DNM may be better compared with other forms of melanoma.

Melanocyte mediated paracrine induction of extracellular matrix degrading proteases in squamous cell carcinoma cells

The expression of extracellular-matrix (ECM)-degrading proteases has been shown to be necessary for invasion of tumor cells into surrounding tissue. For several tumor types, overexpression of these proteases is dependent upon interactions with adjacent fibroblast cell populations. We previously demonstrated activation of matrix metalloprotease (MMP) and urokinase-type plasminogen activator (uPa) expression in a coculture model consisting of squamous cell carcinoma cells (SCC) with dermal fibroblasts. In the present study we have examined whether melanocytes, which are known to interact closely with keratinocytes of the basal epidermal layer, might influence ECM-degrading protease expression in SCC cells as well. Upon coculture of the human SCC cell line II-4 with the nontumorigenic mouse melanocyte cell line Melan-a or treatment of II-4 cells with Melan-a conditioned media, induction of expression of the MMP matrilysin and uPa was observed. In contrast, no induction was observed for stromelysin-1 or 92-kDa type IV collagenase. Matrilysin/uPa-inducing activity was found to act at the level of gene transcription for both matrilysin and uPa and was ubiquitously expressed among six different human melanocytic cell strains/lines, ranging from primary normal melanocytes to cell lines established from metastatic melanoma lesions. These data demonstrate that melanocytic cells can exert a paracrine influence in SCC cells on the expression of specific proteases involved in ECM turnover and tumor invasiveness.

Regulation of matrilysin expression in cells of squamous cell carcinoma by E-cadherin-mediated cell-cell contact

A critical attribute of invasive carcinomas is their ability to degrade components of the extracellular matrix, a process achieved by the matrix metalloproteases. In the human squamous cell carcinoma cell line II-4, mRNA and protein expression of the matrix metalloprotease matrilysin was observed to be significantly higher in confluent than in log-phase growth conditions. The purpose of this study was to determine the basis for this switch in constitutive matrilysin expression. Conditioned medium from confluent cultures did not induce matrilysin in log-phase cultures, nor did conditioned medium from log-phase cultures repress matrilysin expression in confluent cultures. Thus, matrilysin expression was found not to be controlled by factors autocrine product. Matrilysin protein levels were, however, found to be directly correlated to the degree of cell-cell contact. Incubation of confluent cultures in 30 microM calcium medium, which disrupts E-cadherin-mediated cell-cell contact, was subsequently found to inhibit matrilysin expression, as did treatment with an anti-E-cadherin-neutralizing antibody. These results demonstrate that the degree of cell-cell contact mediated by the E-cadherin cell-adhesion molecule can influence constitutive metalloprotease expression levels in cultured squamous cell carcinoma cells.

Desmoplastic malignant melanoma of the gingiva: case report and review of the literature

A rare case of desmoplastic melanoma arising from the maxillary gingiva of a 66-year-old woman is reported. This tumour metastasised to the submandibular lymph node 5 years after extirpation, and local recurrence was observed 2 years later. The gingival tumour showed the histopathological characteristics of desmoplastic melanoma and the metastasised tumour cells were immunohistochemically positive for S-100 protein, neuron specific enolase, HMB-45 highly specific for conventional melanoma, and Fontana-Masson staining. The gingival tumour, originally regarded as benign clinically, was actually a desmoplastic melanoma.

Expression of basic fibroblast growth factor in desmoplastic melanoma

Basic fibroblast growth factor (bFGF) is an established growth factor for melanocytes and a potent angiogenic factor. The expression of bFGF was investigated in 23 desmoplastic melanomas. (DM) (12 males, median age 64 years, and 11 females, median age 54 years) by immunostaining of formalin-fixed, paraffin-embedded sections with high-affinity purified antibody raised against recombinant human bFGF (Scios Nova, Inc.). The tumors were characterized by level II invasion in 1 case (5%), level IV invasion in 11 cases (48%), level V invasion in 8 cases (35%), and indeterminate in 3 cases. bFGF expression was observed in 22 of 23 tumors (95%), either immune localized to tumor cell nuclei in 17 of 22 tumors (77%), or to the cytoplasm of tumor cells in 5 of 22 tumors (23%). Also in these cases, bFGF was strongly expressed in the nuclei of vascular endothelial cells. Maximal expression was noted in the peripheral blood vessels of 20 tumors (91%) versus intratumoral vessels of 13 DM (59%). In conclusion, the expression of predominantly nuclear bFGF by tumor cells in DM suggests a role in mediating the desmoplastic phenotype. In addition, the localization of bFGF to vascular endothelium, particularly at the periphery of the tumor, may be relevant to tumor angiogenesis.

Desmoplastic neurotropic melanoma. A clinicopathologic analysis of 28 cases

BACKGROUND

Desmoplastic neurotropic melanoma (DNM) is a rare variant of malignant melanoma, the natural history and histogenesis of which still are being defined.

METHODS

The clinical and histologic features of 28 cases of DNM were studied. All published cases of DNM to date were reviewed. Paraffin sections from 26 cases were investigated with a panel of 10 tissue markers. The ultrastructural features of seven cases were evaluated.

RESULTS

A comparison of this study's findings with that of other published cases revealed many similarities regarding clinical and pathologic findings and outcome. The patients were white (15 men:13 women; mean and median age, 59 years; range, 22-83 years). Most tumors were located on the head and neck (75%) and were nonpigmented (57%). An associated intraepidermal melanocytic proliferation was identified in 85% of the patients (lentigo maligna in 56%). Histologically, the dermal tumors were composed of tapered, nonpigmented spindle cells in peripheral nerve sheath patterns resembling neuromas, schwannomas, neurofibromas, and perineurial proliferations accompanied by variable neurotropism and desmoplasia; desmoplasia was the most notable feature in most tumors. The mean depth of tumor invasion was 4.1 mm (range, 0.32-9.0 mm). Tumors with continuity between the epidermal and dermal components had a significantly thinner depth of invasion and a more extensive intraepidermal melanocytic proliferation than those tumors with a grenz zone between the two components (2.3 mm vs. 4.6 mm, P = 0.015). Mitotic activity ranged from 0/HPF in 10 cases, 1-6/high power field (HPF) in 12 cases, and to greater than 6/HPF in 4 cases. An ulcer was present in 5/27 tumors, regression in 4/27, a microsatellite in 1, and brisk and had nonbrisk tumor infiltrating lymphocytic responses in 2 and 14, respectively. Vimentin was uniformly positive and keratins AE1.3 and Cam 5.2 and Leu-7 were uniformly negative. S100 protein, also uniformly positive, had patchy reactivity in most tumors that expressed EMA (43%). Smooth muscle actin (52%), neuron-specific enolase (42%), and FXIIIa (30%) had patchy positivity. HMB-45 was reactive only in the epidermal and superficial papillary dermal component in 21% of cases. Ultrastructurally, the common features were long, often intertwining cellular processes, intercellular junctions, and discontinuous basal lamina. Melanosomes were not identified. Follow-up data available on 26/28 patients (mean, 36 months; median, 24 months; range, 5-132 months) showed 20 (70%) alive without disease, 2 alive with disease and 3 dead from disease. Seven patients had recurrent local tumor (multiple in four); four had lymph node metastases, and three had visceral metastases. Patients with recurrent disease of any type had significantly thicker tumors (5.4 mm vs. 3.4 mm, P = 0.046) and were more likely to have an ulcerated tumor (P = 0.03). Actuarial 5-year survival for tumors with greater than a 4-mm thickness was 72%, which was greater than that for other types of melanoma with greater than a 4-mm thickness.

CONCLUSIONS

Desmoplastic neurotropic melanomas are neuroectodermal tumors that usually arise from an intraepidermal melanocytic proliferation but rarely develop de novo in the dermis. Schwannian and perineurial differentiation may account for the desmoplasia and neurotropism encountered in these neoplasms. Desmoplastic neurotropic melanomas present at a more advanced stage locally and may be associated with a better survival than associated with conventional melanomas of similar depth of invasion.

A heterologous in vitro coculture system to study interaction between human bladder cancer cells and fibroblasts

Three-dimensional multicellular spheroids of two fibroblast cell lines (WI-38 and N1) and two differently differentiated bladder carcinoma cell lines (RT4 and J82) were used for cocultures of multicellular tumor spheroids with multicellular spheroids of fibroblasts. The aim of the study was the establishment and characterization of a standardized three-dimensional model for studies of tumor cell-fibroblast interaction as one aspect of tumor-stromal cell interactions of in vivo tumor tissue. Interaction of multicellular spheroids of both fibroblast cell types was analyzed by staining with antibodies against cytokeratin, vimentin and different extracellular matrix molecules. Further, proliferation assessment and phenotypic characterization of the cocultures are presented. Interactions varied with tumor cell type and fibroblast cell type, reflecting intrinsic properties of tumor cells and fibroblasts. The coculture of tumor cells with N1 reflected the in vivo situation the closest, since invasive properties of J82 as well as noninvasive properties of RT4 were characteristics seen in coculture.

Desmoplastic malignant melanoma: a clinicopathological study of 25 cases

Sixteen cases of malignant melanoma which showed prominent desmoplastic and/or neurotropic features occurring throughout the tumour were compiled from the St John's Dermatology Centre histopathological archives. A further nine melanomas in which both conventional and desmoplastic melanoma were present concomitantly were also studied (three tumours with 66% desmoplastic change, two with 50%, and four with less than 50%). There were 14 males and 11 females, with a mean age of 64 years (range 39-86). The mean interval between presentation and diagnosis was 8 months. Eighteen of the 25 tumours were located on the head and neck, three were on the trunk, one was on the upper limb and three were on the lower limb. Histological review revealed 21 of 25 tumours with overlying atypical lentiginous hyperplasia, lentigo maligna melanoma, or superficial spreading malignant melanoma. Neurotropism was present in nine tumours, with the changes confined to local recurrences in two instances; neuroid differentiation was present in four tumours, and neural and perineural tumour spread was present in four tumours. The depth of invasion exceeded 6 mm in seven tumours, and was 2-6 mm in 16, and less than 2 mm in two. Eighteen of the 25 tumours were incompletely excised at the time of the first excision. Lymphoid aggregates were present in 16 tumours, but in most cases were limited to a few lymphoid foci. Melanin was identified in the dermal component of only five tumours, but not in areas showing typical histological features of desmoplastic malignant melanoma. Treatment was by surgical excision in all cases, and was preceded by radiotherapy in one case. Details of follow-up were obtained in all cases, and the duration ranged from 9 months to 10 years (mean, 3 years 11 months). Eleven patients had died; nine from melanoma and two from other causes. One patient was alive, with deep, inoperable local recurrence. Thirteen patients were alive and clinically free from tumour, including two patients in whom there had been local recurrence. A lower rate of neurotropism was present in the nine patients with partial desmoplastic change compared with those with desmoplasic change throughout the tumour, and represented the only significant difference between the two groups of patients.