The antihistamines clemastine and desloratadine inhibit STAT3 and c-Myc activities and induce apoptosis in cutaneous T-cell lymphoma cell lines.

Mycosis fungoides and its leukaemic counterpart Sézary syndrome are the most frequent cutaneous T-cell lymphomas (CTCL), and there is no cure for these diseases. We evaluated the effect of clinically approved antihistamines on the growth of CTCL cell lines. CTCL cell lines as well as blood lymphocytes from patients with Sézary syndrome were cultured with antihistamines, and the cell were analysed for proliferation, apoptosis and expression of programmed death molecules and transcription factors. The two antihistamines clemastine and desloratadine, currently used for symptom alleviation in allergy, induced potent reduction of the activities of the constitutively active transcription factors c-Myc, STAT3, STAT5a and STAT5b in mycosis fungoides and Sézary syndrome cell lines. This inhibition was followed by apoptosis and cell death, especially in the Sézary syndrome-derived cell line Hut78 that also showed increased expression of the programmed death-1 (PD-1) after clemastine treatment. In lymphocytes isolated from Sézary syndrome patients, the CD4-positive fraction underwent apoptosis after clemastine treatment, while CD4-negative lymphocytes were little affected. Because both c-Myc and STAT transcription factors are highly expressed in proliferating tumours, their inhibition by clemastine, desloratadine and other inhibitors could complement established chemotherapies not only for cutaneous T-cell lymphomas but perhaps also other cancers.

Consequences of p16 tumor suppressor gene inactivation in mycosis fungoides and Sézary syndrome and role of the bmi-1 and ras oncogenes in disease progression.

In examining the expression of oncogenes and tumor suppressor genes in mycosis fungoides and Sézary syndrome, we found the cell cycle-regulating protein p16 to be absent in T cells. Immunohistochemical staining with p16-specific antibodies showed that the number of p16-expressing cells in cutaneous lesions decreases in late stages. The repression of p16 was not attributable to deletion or methylation of this gene; however, the Bmi-1 oncogene, a known suppressor of p16, was present in mycosis fungoides and Sézary syndrome cell lines and skin lesions. The absence of p16 correlated with the phosphorylation of the retinoblastoma protein on cyclin D/CDK4- or cyclin D/CDK6-specific sites. Ki-ras, which stimulates phosphorylation of retinoblastoma via cyclin-dependent kinases, was found in all tested cutaneous T-cell lymphoma samples; and its expression generally was stronger in advanced stages. Thus, cutaneous T-cell lymphoma cells show changes in oncogene and tumor suppressor gene expression that increase proliferation.

Transcription factor profiling shows new ways towards new treatment options of cutaneous T cell lymphomas.

Most oncogenes encode activators of transcription factors or transcription factors themselves. Transcription factors that are induced by growth stimuli are, in contrast to transcription factors that regulate house keeping genes, tightly regulated and only active, when a stimulus (e.g. cytokines or other growth factors) is given. Examples of such transcription factors are members of the jun, fos, myc, NFkB and STAT gene families. In cancer cells this regulation is interrupted, resulting in constitutive activities of transcription factors that are normally silent. This in turn results in the increased expression of target genes that are necessary for growth and protection from apoptosis. Since inducible transcription factors are activated by specific pathways, the identification of unusual constitutively active transcription factors also identifies the involved signal transduction pathway. Inhibitors of the components of these pathways may be effective anti-cancer agents, as they interrupt the abnormal signalling and in cancer cells. We applied this strategy for two forms of cutaneous T cell lymphomas and identified several groups of agents that may be the prototypes of new drugs to fight these diseases.

Cutaneous malignant lymphomas: update 2006.

Cutaneous lymphomas represent a unique group of lymphomas and are the second most frequent extranodal lymphomas. As with other neoplasias, the pathogenesis is based mainly on a stepwise accumulation of mutations of suppressor genes and oncogenes caused by genetic, environmental or infectious factors. The diagnostic work-up includes clinical, histological, imaging and hematological investigations and in many cases immunohistochemical and molecular biological analyses. The current WHO/EORTC classification of cutaneous lymphomas differentiates "mature T-cell and NK-cell lymphomas", "mature B-cell lymphomas" and "immature hematopoietic malignancies", their variants and subgroups. It is compatible with the WHO classification for neoplasias of the hematopoietic and lymphoid tissue and respects the organ-specific peculiarities of primary cutaneous lymphomas. The assignment of the various types of cutaneous lymphomas into prognostic categories (pre-lymphomatous "abortive" disorders; definite malignant lymphomas of low-grade malignancy; definite malignant lymphomas of high-grade malignancy) provides essential information on the biological behavior and allows an appropriate planning of the therapeutic strategy, which may be topical or systemic and aggressive or non-aggressive. Besides the classical options for therapy, there are new and "experimental" strategies, the efficacy of which has to be studied in clinical trials.

From inflammation to neoplasia: new concepts in the pathogenesis of cutaneous lymphomas.

Mycosis fungoides is a clinicopathologic term which describes a neoplasm of cerebriform T lymphocytes that form plaques and tumors. We further suggest that mycosis fungoides arises in a background of chronic inflammation or as a response to chronic antigenic stimulation. Subsequently, a series of mutations results in the stepwise progression from eczematous patches, to plaques, tumors and eventual hematogenous dissemination. The pathogenetic process is driven by various, probably individually different, exogenous factors, e.g. environmental foreign antigens, bacterial superantigen, and/or endogenous factors, e.g. autocrine cytokine loops, CD40/CD40L and B7/CD28 interaction.

In vivo switching of human melanoma cells between proliferative and invasive states.

Metastatic melanoma represents a complex and heterogeneous disease for which there are no therapies to improve patient survival. Recent expression profiling of melanoma cell lines identified two transcription signatures, respectively, corresponding with proliferative and invasive cellular phenotypes. A model derived from these findings predicts that in vivo melanoma cells may switch between these states. Here, DNA microarray-characterized cell lines were subjected to in vitro characterization before s.c. injection into immunocompromised mice. Tumor growth rates were measured and postexcision samples were assessed by immunohistochemistry to identify invasive and proliferative signature cells. In vitro tests showed that proliferative signature melanoma cells are faster growing but less motile than invasive signature cells. In vivo proliferative signature cells initiated tumor growth in 14 +/- 3 days postinjection. By comparison, invasive signature cells required a significantly longer (P < 0.001) period of 59 +/- 11 days. Immunohistochemistry showed that regardless of the seed cell signature, tumors showed evidence for both proliferative and invasive cell types. Furthermore, proliferative signature cell types were detected most frequently in the peripheral margin of growing tumors. These data indicate that melanoma cells undergo transcriptional signature switching in vivo likely regulated by local microenvironmental conditions. Our findings challenge previous models of melanoma progression that evoke one-way changes in gene expression. We present a new model for melanoma progression that accounts for transcription signature plasticity and provides a more rational context for explaining observed melanoma biology.

[Perspective of cutaneous lymphoma reserach]. / Perspektiven der Forschung bei kutanen Lymphomen.

Primary cutaneous lymphomas are characterized by an expansion of hematopoietic cells in the special microenvironment of the skin. They represent a special challenge both for researches and for clinicians who treat patients with these disorders. New research data concerning the biology of lymphocytes and the cutaneous microenvironment have increased our knowledge of these diseases in the last decades. The new WHO/EORTC classification definitely will facilitate a more detailed investigation of the various subtypes.

Expression of apoptosis regulators in cutaneous T-cell lymphoma (CTCL) cells.

This study examined cutaneous T-cell lymphoma (CTCL) cell lines and cutaneous lesions for the presence of Bcl-2 gene family members and found that the two apoptosis-inhibiting members Bcl-xL and Mcl-1 and the two apoptosis-supporting members Bad and Bax were expressed. However, Bad was at least partially inactivated by phosphorylation. In skin lesions, the translocation of Bad from the nucleus to the cytoplasm may reflect the Bad inactivation by phosphorylation identified in vivo. Bax is also ineffective, as the non-steroidal anti-inflammatory drug sulindac, whose cytotoxic effect is mediated by Bax, could not induce apoptosis in CTCL cell lines. The expression of Bcl-2, Bcl-xL, and Mcl-1 may therefore be sufficient to guarantee the survival of malignant CTCL cells. The Bcl-x, Mcl-1, Bad, and Bax proteins were also expressed in all CTCL skin lesions tested. In two patients from whom two biopsies from two different time points of the disease were available, a significant increase in Mcl-1 expression was found in the later-stage skin lesion. Overexpression of Mcl-1 and synthesis of non-functional Bax may be responsible for the resistance of CTCL cells to the anti-cancer drugs chlorambucil and sulindac.

Galectin-1-mediated apoptosis in mycosis fungoides: the roles of CD7 and cell surface glycosylation.

Sezary cells, the malignant T cells in mycosis fungoides/Sezary syndrome, resist a variety of apoptosis-inducing agents, a feature that contributes to the poor response to therapy in mycosis fungoides. Galectin-1 is a mammalian lectin that triggers T cell apoptosis. For T cells to be susceptible to galectin-1-induced apoptosis, the T cells must express specific glycoprotein receptors, such as CD7, that bear the specific oligosaccharides recognized by galectin-1. Because Sezary cells are characteristically CD7(-), lack of CD7 expression has been proposed to render Sezary cells resistant to galectin-1-induced death. However, the role played by aberrant cell surface glycosylation in resistance of Sezary cells to galectin-1 has not been examined. In this study, we demonstrated abundant galectin-1 in mycosis fungoides skin lesions, indicating that Sezary cells are exposed to galectin-1 in vivo. To determine specific characteristics of Sezary cells that contribute to galectin-1 resistance, we assessed CD7 expression and cell surface glycosylation of Sezary cells in mycosis fungoides lesions and of four Sezary T cell lines. Sezary cells in primary lesions and Sezary T cell lines demonstrated a characteristic "glycotype" with sialylated core 1 O-glycans that promote galectin-1 resistance. Expression of CD7 was necessary but not sufficient for galectin-1-induced death of Sezary cell lines. In addition, CD7(-) Sezary cell lines, and Sezary cells within mycosis fungoides lesions, expressed galectin-1, whereas CD7-positive Sezary cell lines did not express galectin-1. We propose that both loss of CD7 expression and altered cellular glycosylation contribute to apoptosis resistance of malignant T cells in mycosis fungoides.