Sensitivity of transplantable melanoma cells to cytokines with regard to their spontaneous apoptosis.

OBJECTIVES: Changes in the sensitivity of two lines of transplantable melanoma cells to the antiproliferative activity of interleukin 6 (IL-6), oncostatin M (OSM), tumor necrosis factor-alpha (TNF-alpha) during melanoma progression were the subject of this study. We were looking for a correlation between these changes and the ability of melanoma cells to undergo spontaneous apoptosis. METHODS: The influence of exogenous cytokines on the proliferation of melanoma cells was measured by colorimetric methods with MTT and apoptosis of these cells was estimated by staining with annexin V/propidium iodide, measurement of DNA degradation and cell cycle analysis. RESULTS: It was observed that during melanoma progression the sensitivity of those two melanoma line cells to the antiproliferative effect of IL-6 and OSM did not change, while a spontaneous alteration of the melanotic line into an amelanotic one seemed to be accompanied by resistance of the amelanotic melanoma cells to the antiproliferative activity of TNF-alpha. Simultaneously, we observed a decreased ability of amelanotic melanoma cells (in comparison with the native line) to undergo spontaneous apoptosis. CONCLUSIONS: The observed resistance to the TNF-alpha antiproliferative effect which appears during melanoma progression seems to be correlated with a lower ability of the amelanotic melanoma cells to undergo spontaneous apoptosis.     

Osteoblasts and stromal cells isolated from femora in rheumatoid arthritis (RA) and osteoarthritis (OA) patients express IL-11, leukaemia inhibitory factor and oncostatin M

We investigated both in vitro and ex vivo the role of mature osteoblasts (OB) and bone marrow stromal cells (BMSC) in RA and OA by analysing the expression of the following IL-6-type cytokines: IL-11, leukaemia inhibitory factor (LIF), oncostatin M (OSM) and IL-6. OB and BMSC were isolated from femora of RA, OA and post-traumatic (PT) patients, cultured in vitro in the presence or absence of IL-1beta and tumour necrosis factor-alpha (TNF-alpha), and assessed for the production and mRNA expression of IL-6-type cytokines. Trabecular bone biopsies were obtained from the inner portions of femoral heads and used for cytokine in situ immunostaining. Cultured OB and BMSC from different patients constitutively secreted IL-11 and IL-6 but not OSM. LIF was secreted only by BMSC, at very low levels. Interestingly, IL-11 basal production was significantly higher in BMSC than in OB in all three groups tested. IL-1beta and TNF-alpha strongly stimulated IL-6-type cytokine release (except for OSM) by both OB and BMSC. OSM was expressed only at mRNA levels in all groups studied. Cytokine immunostaining on bone biopsies confirmed the data obtained on cultured cells: IL-11, IL-6 and LIF proteins were detected both in mesenchymal (BMSC and OB) and mononuclear cells; OSM was found only in mononuclear cells. These data demonstrate that IL-6-type cytokines are constitutively expressed in the bone compartment in RA, OA and PT patients and can be secreted by bone cells at different stages of differentiation (BMSC and OB). This suggests that these cytokines may be involved in the mechanisms of bone remodelling in OA and RA.     

Prothymosin α1 modulates lymphokine-activated killer cell activity and IL-2 production by peripheral blood lymphocytes from melanoma patients in vitro

The effects of prothymosin α1 (Pro α1) on the natural killer (NK), lymphokine (IL-2)-activated killer (LAK) cell activity and the phytohaemagglutinin (PHA)-induced IL-2 secretion of peripheral blood T-lymphocytes (PBL) from 34 malignant melanoma patients of all clinical stages were studied in vitro. On average, melanoma patients showed lower NK and LAK cell activities than healthy donors. In particular, patients with metastases revealed an impaired NK cell activity. However, individuals showed a broad range of LAK cell sensitivity to Pro α1 depending, among other factors, on the disease stage. LAK cell activities were not correlated to tumour stage. Patients' impaired LAK cell activity could be restored by Pro α1. Only patients at stage II (regional metastases) responded to Pro α1. The IL-2 secretion from PBL melanoma and healthy donors did not differ; Pro al administration was without any significant effect. However, stage III (distant metastases) PBL expressed significantly lower IL-2 levels, compared to stage I (primary tumours). The highest IL-2 level was found to be associated with tumour stage II. Pro al enhanced the IL-2 secretion from stage I PBL. Therefore Pro α1 administration abrogated the defective LAK cell activity and IL-2 secretion of PBL, mainly from patients at early melanoma stages.     

Tumour-infiltrating lymphocytes in primary melanoma: functional consequences of differential IL-2 receptor expression

Tumour-infiltrating lymphocytes (TIL) have been isolated from early primary melanoma (Clark level III) and expanded in vitro using culture conditions with low concentrations of IL-2 (50 U/ml). Immediately after isolation TIL consisted of mainly CD3⁺ T cells, and the portion of CD56⁺ natural killer (NK) cells was below 20%. Fresh TIL cultures could be distinguished by CD25 expression since some contained up to 33%, others less than 5% CD25⁺ cells. These showed differences in subsequent development during in vitro expansion. CD25-cxprcssing cultures remained stable in their phenotype, whereas the second TIL type showed major changes: CD3 (ca 70–30%) expression decrease. CD25 (ca 5–35%) and CD56(ca 15–55%) expression increase. The TIL type, which remained dominated by CD3⁺ T cells, killed autologous tumour cells efficiently (⁵¹Cr-rclcase greater than 30% at a E/T ratio of 20:1). which could be blocked by MoAbs against MHC class I molecules. In contrast, the other TIL type exhibited weak cytotoxicity (less than 17%⁵¹Cr-release at an E/T ratio of 20:1) against the autologous tumour. Therefore, the expression of CD25 on freshly isolated TIL is a good marker for tumour specificity of in vitro expanded TIL.     

Defective lymphokine production by most CD8+ and CD4+ tumor-specific T cell clones derived from human melanoma-infiltrating lymphocytes in response to autologous tumor cells in vitro

Human melanomas are infiltrated by tumor-reactive T lymphocytes. However, the ability of these cells to elicit a specific anti-tumor response in vivo remains to be established. Because lymphokine production is critical for T cell functions, we have analyzed the capacity of melanoma-specific tumor-infiltrating lymphocyte (TIL) clones to produce major lymphokines: interleukin-2 (IL-2), interferon-γ (IFN-γ) and interleukin-4 (IL-4), as well as tumor necrosis factor (TNF), in response to direct antigen presentation by autologous and allogeneic tumor cells. We report here that, upon stimulation by autologous melanoma cells, all TIL clones secreted TNF but only a few of them produced significant amounts of IL-2, IL-4 or IFN-γ. Nonetheless, all these clones consistently produced two or three of these last lymphokines upon stimulation with phorbol myristate acetate and calcium ionophore, as well as IL-2 upon CD3 stimulation, showing the existence of three lymphokine profiles among them: Th1, Th0 and a profile characterized by IL-2 and IL-4, but not IFN-γ secretion. Stimulation of TIL clones by allogeneic melanoma lines sharing the appropriate HLA-peptide complexes revealed that defective IL-2 production seemed to be a constant feature for some clones, while it was, for other clones, dependent on the antigen-presenting tumor cells. For this last type of clone, we further showed that defective IL-2 induction resulted from an LFA-3 defect of some melanoma cells or from distinct yet undefined defects of other melanoma lines. Our data suggest that defective lymphokine secretion may be an essential component of the in vivo failure of melanoma-reactive TIL to control tumor development. Interestingly both CD4⁺ and CD8⁺ TIL clones from one patient were fully activated by the autologous melanoma cells in vitro, supporting a potential role of such TIL in spontaneous or induced tumor rejection.     

Melanoma antigen recognition by tumour-infiltrating T lymphocytes (TIL): effect of differential expression of melan-A/MART-1

We have isolated, from an individual patient with metastatic melanoma, a series of eight TIL clones capable of lysing autologous melanoma cell targets. Six of the eight clones expressed TCRAV2S1 and lysed targets expressing HLA-A2 and the Melan-A/MART-1 peptide: AAGIGILTV. Polymerase chain reaction-single stranded conformational polymorphism (PCR-SSCP) analysis showed that the Melan-A/MART-1-specific clones were predominant in the bulk culture prior to cloning. However, the tumour progressed in vivo even in the presence of these tumour cell-lytic clones. Using the anti-Melan-A/MART-1 MoAb (A-103), we noted that Melan-A/MART-1 expression on three melanoma cell lines varied considerably during in vitro culture, in the absence of T cell immunoselection, relative to cell density. Tumour cells which spontaneously decreased Melan-A/MART-1 expression were less susceptible to specific TIL lysis. Melan-A/MART-1 expression and susceptibility to lysis increased in cells cultured at lower density. These data suggest that modulation of tumour antigen may account for tumour progression in the presence of tumour cell-lytic T lymphocytes. The observations suggest a possible explanation for the common finding of Melan-A/MART-1-specific lytic TIL in clinically progressing melanomas, as well as a possible pathway for therapeutic intervention.     

Prognostic significance of the histological features of malignant melanoma

A review of 694 patients with localized cutaneous malignant melanoma (clinical stage I) revealed that three histological features of the primary lesion had no effect of their own on survival rate but derived their prognostic significance only because of their close correlation with tumour thickness. Primary lesions of superficial spreading histogenetic type, or of low mitotic activity or showing evidence of partial regression appeared to have a more favourable prognosis than lesions of nodular histogenetic type or of high mitotic activity or showing no regression. However, the former three histological features were predominant in thin lesions which had a better prognosis than thicker lesions. It was concluded that these features exerted only an indirect effect upon survival, tumour thickness being the most important prognostic determinant.     

Cancer Immunotherapy

This review summarises the evolution of recent major advances in cancer immunotherapy, using metastatic melanoma as a model. The first true clinical progress with immunotherapy developed from the application of recombinant DNA technology for the large scale production of immunostimulant cytokines. Clinical trials demonstrated that the systemic administration of recombinant high-dose bolus intravenous interleukin-2 (IL-2; 720 000 IU/kg every 8 hours) mediated objective tumour progression in 20% of patients with metastatic renal cancer and in 17% of patients with metastatic melanoma, with complete responses of 9% and 7%, respectively. The use of adoptive immunotherapy (the transfer of immune cells with anti-tumour activity to the tumour-bearing host) focused interest on T lymphocyte-mediated tumour recognition. Clinical trials described the systemic administration of lymphokine activated killer (LAK) cells and subsequently tumour infiltrating lymphocytes (TIL) to patients with advanced cancer. Although able to kill tumour targets in vitro, LAK cells did not prove useful for the treatment of patients with metastatic melanoma and renal cancer. A randomised trial, in which IL-2 was administered alone or with LAK cells, failed to show a difference in response rate or survival. In contrast, the treatment of 86 patients with metastatic melanoma using TIL plus IL-2 resulted in a 34% objective response rate, which included patients who had previously failed treatment with high-dose IL-2 alone. The focus on cellular immune responses, combined with rapid biotechnological advances, resulted in the identification of tumour specific antigens, such as MART-1 and gp100, that could be recognised by autologous TIL. This provided fundamental evidence of the existence of melanoma-associated antigens that were recognised in vivo by effector cells of the immune system. In vitro studies demonstrated immunodominant epitopes from MART-1 and gp100 that could induce in vitro-specific cytotoxic T lymphocyte reactivity. To enhance in vitro immunogenicity, single amino acid substitutions were made to identify peptides with higher affinity for HLA-A*0201. Modified peptides from gp100 were compared with the parental peptide for increased immunogenicity based on their ability to induce anti-tumour lymphocytes in vitro. From these studies, a candidate peptide was identified (G9-209-2M) which had increased immunogenic reactivity in vitro. Clinical trials demonstrated that the modified G9-209-2M peptide was more effective. Unfortunately, objective tumour regression was still low. However, when high-dose IL-2 was combined with G9-209-2M objective clinical responses increased to 42%. Efforts to find better ways to immunise against self antigens are ongoing and involve further peptide immunisations, as well as recombinant viral vectors, adjuvant cytokine therapy and cellular adjuvants such as dendritic cells.     

T cell receptor gene rearrangements and cytotoxic activities of clones isolated from tumour-infiltrating lymphocytes (TIL) from melanoma patients

The lymphocytes which infiltrate tumours and are grown in vitro to be used in adoptive immunotherapy are often characterized by dominant rearrangement of their T cell receptor (TCR) genes. To investigate the frequency and function of cells contributing to the ‘dominant’ rearrangement, we have cloned two bulk cell lines of TIL derived from melanoma patients (TIL-1 and TlL-5). These IL-2-propagaled TIL cell lines had a CD8⁺ phenotype and exerted strong cytotoxic activity against autologous melanoma cells, but not against the natural killer (NK)-sensitive K-562 cell line or LAK targets such as Daudi cells. We derived 40 clones from TIL-1 and 23 from TIL-5. All tested clones were CD3⁺, CD4^?, CD8⁺ and expressed the α/β TCR. From TIL-1.27 of 40 clones, and 13/19 of the TIL-5 clones lysed autologous tumour cells. In contrast to the NK, -negative bulk cultures, K-562 killing was detected in 21 of the TIL-1 clones and 17 of the TIL-5 clones. TIL-1 contained eight clones and TiL-5 two clones with lytic capacity against neither autologous tumour cells nor the K562 cell line, although these clones possessed lytic potential as evidenced in a lectimediated lysis assay. LAK activity was not detected in most clones. Cytotoxic activity against autologous tumour could be inhibited by preincubation with anti-CD3 or anti-HLA class I MoAbs, Of the 34 TlL-1 clones analysed, 15 shared a rearranged TCRβ EcoR1 restriction fragment of approximately 9 5 kb with the bulk culture. Clones sharing the EcoR1 10 5-kb dominant band present in TIL-5 bulk culture were also isolated. When the pattern of TCRβ rearrangement was compared with the cytotoxic functions, the following conclusions could be drawn: (i) clones contributing to the dominant band had heterogeneous functions. Most killed autologous tumour cells, but clones with no cytotoxic activity or even with no proliferative capacity in response lo autologous tumour cells were also detected among those contributing to the dominant rearrangement; (ii) some clones that share an apparently identical rearranged band different from the “dominant” rearrangement, may demonstrate the same cytotoxic function. In addition, our data suggest that many of the clones that share the dominant rearrangement originated from diverse progenitors. The high frequency of clonally diverse anti-tumour reactive TIL is likely to be a reflection of the in vivo selection of the TCR repertoire at the site of tumour. Further study of the TCR gene rearrangements should help to clarify how selection at this level can benefit future immunotherapeutic approaches.     

Tenascin-C in primary malignant melanoma of the skin

AIMS: To investigate the expression and the prognostic role of glycoprotein Tenascin-C (Tn-C) in primary melanoma of the skin. METHODS AND RESULTS: The immunohistochemical expression of Tn-C was studied in 98 primary melanomas and related to inflammation, invasion, and patient outcome. Patients were followed up for disease recurrence for 0.04-7.4 years (median 3.9) and for survival for 0.5 to 12.1 years (median 9.3). The expression of Tn-C was evaluated for each tumour invasion border; the stromal and intracytoplasmic Tn-C of the melanoma islets were also recorded. Tn-C is widely expressed in primary melanoma samples, the staining pattern varying from focal to diffuse in different parts of the tumour. No correlation existed between intensity of Tn-C staining and inflammation. No stromal Tn-C was detected at the upper dermal lateral border in 12 patients, nor at the deep, dermal or subcutaneous border in 14 patients. These patients showed better disease-free survival (DFS) than did those cases with focal or diffuse staining (P = 0.06, P = 0.05). Also, absence of intracytoplasmic Tn-C was a beneficial prognostic factor for DFS (P = 0.04). In multivariate analysis, tumour ulceration and intracytoplasmic Tn-C expression of melanoma cells were independent adverse prognostic factors for DFS. CONCLUSIONS: In primary melanoma of the skin, absence of Tn-C in the stroma of invasion fronts and within tumour cells seems to be related to a more benign disease behaviour with a lower risk of developing metastases.     

PAS-positive loops and networks as a prognostic indicator in cutaneous malignant melanoma.

Recently, microvascular channels, as detected by PAS histochemistry, were positively correlated with poor prognosis in uveal malignant melanoma. Since uveal melanomas are not penetrated by lymphatic vessels, while cutaneous melanomas are, the question arises as to whether these loops and networks are also of prognostic relevance in cutaneous melanoma. Histochemically and immunohistochemically detected loops and networks in 100 cases of cutaneous malignant melanoma were correlated with the occurrence of metastasis in a 10-year follow-up study. To detect these patterns, the significance of various methods (PAS reaction with/without nuclear counterstain, anti-laminin immunohistochemistry) was investigated. The presence of loops and networks was a highly significant prognostic marker (p<0.0001) for metastasis in cutaneous malignant melanoma. The presence of these patterns proved to have higher prognostic relevance for metastasis than Breslow's tumour thickness, especially for stage IB and stage IIA tumours (intermediate thickness/risk). PAS reaction without nuclear counterstain proved to be the best method to detect these patterns. Compared with the conventional staging of Breslow's tumour thickness, and especially so for stage IB and IIA melanomas, the determination of PAS-positive loops and networks in cutaneous malignant melanoma provides additional prognostic information.     

Genetically modified tumour vaccines (GMTV) in melanoma clinical trials

Since melanoma is a model immunogenic malignancy incurable in the disseminated phase of its natural course different immunotherapeutic approaches are tested in clinical trials. A number of tumour vaccines genetically modified (GMTV), with various immunostimulatory factors, are tested in phase I/II clinical trials. These factors include cytokines, tumour antigens (TA), costimulatory molecules or HLA antigens. We have designed a novel, mixed auto/allogeneic cellular melanoma vaccine modified with the IL-6 and the sIL-6R genes. Preclinical studies in a mouse model demonstrated that the IL-6/sIL-6R based vaccine is able to elicit efficient anti-tumour responses, mediated by CD8+ and NK cells, which resulted in inhibition of the tumour growth, metastases formation and prolonged survival of the animals treated. Irradiation of vaccine cells does not only lead to their sterilisation but also causes increased secretion of exogenous IL-6 and sIL-6R. Since January 1996 we have vaccinated more than one hundred metastatic melanoma patients. Promising clinical results (22% CR+PR, 32% SD) and the evidence of immune responses in the vaccinated patients have prompted us to design a phase III clinical trial which is to be open in 2000.     

树突状细胞在人皮肤黑色素瘤组织中抗原提呈效应的形态学观察

目的探讨人皮肤黑色素瘤组织中肿瘤浸润树突状细胞（TIDC）的抗肿瘤效应。方法采用光镜、透射电镜和免疫组化方法观察19例手术切除的人皮肤黑色素瘤中TIDC和肿瘤浸润淋巴细胞（TIL）抗肿瘤效应的形态学表现。结果早期人皮肤黑色素瘤组织中的类高内皮微静脉和淋巴管内、外均可见大量淋巴细胞和树突状细胞集聚和迁移;病变早期TIDC和TIL浸润比晚期明显（P〈0．01）。透射电镜下,TIDC大致有两种形态。一种TIDC体积大,表面有许多树枝状突起,核不规则,胞浆内有丰富的细胞器;另一种TIDC突起较少,细胞器也较少。TIDC与肿瘤细胞、TIDC与TIL、TIL与TIL、TIL与肿瘤细胞之间存在多种形式的膜接触。与TIL接触的肿瘤细胞呈凋亡状态。晚期病变组织中TIDC与TIL数量明显减少,于癌巢内常见凋亡的TIDC与TIL。结论人皮肤黑色素瘤组织中存在不同形态的TIDC与TIL,并通过类高内皮微静脉和淋巴管迁移;TIDC、TIL、癌细胞彼此密切作用,在肿瘤局部即可发生抗肿瘤免疫应答反应,反应程度与肿瘤进展呈负相关。     

Expression of interleukin-8 detected by in situ hybridization correlates with worse prognosis in primary cutaneous melanoma

Previous in vitro studies have demonstrated that endogenously produced human interleukin-8 (IL-8) can act as an important growth factor for human melanoma cells in vitro. The present study, has investigated whether IL-8 mRNA expression in primary melanomas may be of prognostic relevance with regard to melanoma progression and metastatic spread. In order to evaluate the clinical significance of IL-8 mRNA expression of melanoma cells in vivo, 59 melanocytic tissue specimens (37 primary melanomas and 22 melanocytic naevi) were studied using a semiquantitative in situ hybridization technique. Significant mRNA expression of IL-8 was found in 59 per cent (22/37) of melanomas. In 19 per cent (7/37) of the malignant melanomas, additional hybridization signals were noted within keratinocytes of the overlying epidermis. In contrast, paralesional normal-appearing epidermis and melanocytes in non-malignant lesions (melanocytic naevi) showed no IL-8 mRNA. Analysis of the relationship between IL-8 expression and clinico-histopathological features showed a significant association between IL-8 mRNA expression and the histological melanoma subtype (IL-8 mRNA: 14/19 in superficial spreading melanoma versus 4/12 in nodular melanoma, p< 0.05). Furthermore, IL-8 expression in primary tumours could be correlated with the patients' clinical course, with time to progression being significantly reduced in primary tumours expressing IL-8 in either the tumour cells or keratinocytes of the overlying epidermis. These results demonstrate for the first time that IL-8 expression, as detected by in situ hybridization in primary tumours, may serve as a significant prognostic factor for tumour progression in human malignant melanoma.     

Detection of ABCB5 tumour antigen‐specific CD8+ T cells in melanoma patients and implications for immunotherapy

ATP binding cassette subfamily B member 5 (ABCB5) has been identified as a tumour‐initiating cell marker and is expressed in various malignancies, including melanoma. Moreover, treatment with anti‐ABCB5 monoclonal antibodies has been shown to inhibit tumour growth in xenotransplantation models. Therefore, ABCB5 represents a potential target for cancer immunotherapy. However, cellular immune responses against ABCB5 in humans have not been described so far. Here, we investigated whether ABCB5‐reactive T cells are present in human melanoma patients and tested the applicability of ABCB5‐derived peptides for experimental induction of human T cell responses. Peripheral blood mononuclear cells (PBMNC) isolated from blood samples of melanoma patients (n = 40) were stimulated with ABCB5 peptides, followed by intracellular cytokine staining (ICS) for interferon (IFN)‐γ and tumour necrosis factor (TNF)‐α. To evaluate immunogenicity of ABCB5 peptides in naive healthy donors, CD8 T cells were co‐cultured with ABCB5 antigen‐loaded autologous dendritic cells (DC). ABCB5 reactivity in expanded T cells was assessed similarly by ICS. ABCB5‐reactive CD8⁺ T cells were detected ex vivo in 19 of 29 patients, melanoma antigen recognised by T cells (MART‐1)‐reactive CD8⁺ T cells in six of 21 patients. In this small, heterogeneous cohort, reactivity against ABCB5 was significantly higher than against MART‐1. It occurred significantly more often and independently of clinical characteristics. Reactivity against ABCB5 could be induced in 14 of 16 healthy donors in vitro by repeated stimulation with peptide‐loaded autologous DC. As ABCB5‐reactive CD8 T cells can be found in the peripheral blood of melanoma patients and an ABCB5‐specific response can be induced in vitro in naive donors, ABCB5 could be a new target for immunotherapies in melanoma.     

The relationships between PD-L1 expression,CD8+ TILs and clinico-histomorphological parameters in malignant melanomas

IntroductionMalignant melanomas (MM) are often connected with the expression of PD-L1 protein and the presence of tumor-infiltrating lymphocytes (TILs), however, their impact on prognosis remains controversial. Due to their supposed clinical significance and lack of convincing data, we decided to establish the relationships between CD8 + TIL count, PD-L1 level and certain clinical and histopathological parameters in patients with malignant melanoma, especially those associated with unfavorable prognosis.Materials and methodsWe performed immunohistochemistry for PD-L1 and CD8 on 56 formalin-fixed paraffin-embedded specimens from patients with cutaneous and metastatic malignant melanomas. PD-L1 expression levels were determined by immunohistochemistry (clone 28-8) and subsequently the tumor proportion scores (TPS) were evaluated. CD8 + TIL expressions were classified as either grade 0, 1+, 2+ or 3+, based on the density and distribution of the infiltrating lymphocytes.ResultsThe PD-L1 expression was detected in 20 out of 56 cases (35,71 %). The expression of PD-L1 on tumor cells was significantly increased with higher TILs infiltration in the tumor microenvironment (p = 0,038). Lower TIL score corresponds with poor prognostic clinicopathological parameters such as higher number of mitotic figures (p = 0,005), Clark's level (p = 0,007) and Breslow's depth (p = 0,010).ConclusionsOur results suggest a favorable prognostic value for CD8 + TIL infiltration. Moreover, TIL density was strongly correlated and geographically associated to PD-L1 expression. This analysis provides more insight into the role of TIL count and PD-L1 level in MM and their relationship with each other and association with other prognostic indicators.     

Anorectal melanomas do not harbour the Kaposi sarcoma-associated human herpesvirus type 8 DNA

Anorectal melanomas are similar to cutaneous melanomas with regard to the mode of spread and to the immunophenotype. When compared with patients with cutaneous melanoma, those suffering from anorectal melanoma have a much worse outcome. The etiology of anorectal melanomas is as yet completely unknown. For anatomical reasons, ultra-violet (UV-B) radiation can not cause anorectal melanomas as in cutaneous tumours, that are associated with exposure of the skin to UV-B radiation. As the cytokine interleukin-6 (IL-6) is known to stimulate melanoma tumour cell proliferation and a functional homologue of human IL-6 has been identified recently in the HHV-8 genome, this tumorigenic virus might be involved in the pathogenesis of anorectal melanomas. Twelve formalin fixed and paraffin embedded primary anorectal melanomas from seven female and five male patients with a mean age at diagnosis of 71 years (range 38-88 years) were investigated for the presence of HHV-8 DNA. Using a specific and highly sensitive polymerase chain reaction protocol, this tumorigenic gamma-herpesvirus was not detectable in any tumour. This data indicates that HHV-8 is not involved in the development of anorectal melanomas.     

The status of microRNA-21 expression and its clinical significance in human cutaneous malignant melanoma

Dysregulation of microRNA-21 plays critical roles in tumor initiation and progression. The purpose of this study was to investigate the status of microRNA-21 expression in human cutaneous malignant melanoma and determine its clinical significance. TaqMan^® real-time RT-PCR assay was performed to examine the expression of microRNA-21 in 10 cases of dysplastic nevi, 86 cases of primary cutaneous melanomas, 10 cases of melanoma metastases. The correlation of microRNA-21 expression with clinicopathological factors or prognosis of patients with cutaneous melanoma was statistically analyzed. Additionally, the effects of microRNA-21 expression on growth, apoptosis and chemo- or radiosensitivity of melanoma cells were also investigated by transfection of microRNA-21 inhibitor. We firstly showed that increased levels of microRNA-21 expression were shown from dysplastic nevi to primary cutaneous melanomas to melanoma metastases. Moreover, high miR-21 expression was found to be correlated with Breslow thickness and advanced clinical stage. Patients with high microRNA-21 expression showed shorter 5-year disease-free or overall survival than those with low microRNA-21 expression. Furthermore, multivariate regression analysis showed that the status of microRNA-21 expression was an independent prognostic factor for overall survival of patients. Antisense-mediated microRNA-21 inhibition could significantly suppress growth, increase apoptosis and enhance chemo- or radiosensitivity of human cutaneous melanoma cells by inducing the increased Bax/Bcl-2 ratio. Thus, the status of microRNA-21 might be an independent prognostic factor for patients with cutaneous melanoma, and microRNA-21 has the potential of being a novel molecular target for the treatment of human cutaneous melanoma.     

Interferon-alpha (IFN-alpha) stimulates anti-melanoma cytotoxic T lymphocyte (CTL) generation in mixed lymphocyte tumour cultures (MLTC)

IFN-alpha administration after primary tumour resection improves the survival of melanoma patients at high risk of relapse. To investigate whether this response might be due to stimulation of anti-tumour immunity, the effect of IFN-alpha on anti-melanoma CTL generation in MLTC was measured. IFN-alpha increased both allogeneic and autologous anti-melanoma CTL generation from peripheral blood lymphocytes stimulated with irradiated primary melanoma cultures. IFN-alpha up-regulated MHC class I expression on primary melanoma cultures, whereas IFN-gamma up-regulated both MHC class I and II expression. However, the effect of IFN-alpha on anti-melanoma CTL generation was often more potent than that of IFN-gamma, equalling the effect of the optimal combination of IL-2 and IL-12. Pre-treatment of primary melanoma cultures with IFN-gamma was sufficient for CTL generation in MLTC, whereas IFN-alpha needed to be present during the MLTC. While direct anti-proliferative effects of IFN-alpha on some tumour cells have been described, IFN-alpha did not inhibit proliferation of primary melanoma cultures. These results suggest that the clinical effects of IFN-alpha in melanoma patients may be immune-mediated.