Katharina L. Kopp

Diagnostic microRNA profiling in cutaneous T-cell lymphoma (CTCL)

Cutaneous T-cell lymphomas (CTCLs) are the most frequent primary skin lymphomas. Nevertheless, diagnosis of early disease has proven difficult because of a clinical and histologic resemblance to benign inflammatory skin diseases. To address whether microRNA (miRNA) profiling can discriminate CTCL from benign inflammation, we studied miRNA expression levels in 198 patients with CTCL, peripheral T-cell lymphoma (PTL), and benign skin diseases (psoriasis and dermatitis). Using microarrays, we show that the most induced (miR-326, miR-663b, and miR-711) and repressed (miR-203 and miR-205) miRNAs distinguish CTCL from benign skin diseases with > 90% accuracy in a training set of 90 samples and a test set of 58 blinded samples. These miRNAs also distinguish malignant and benign lesions in an independent set of 50 patients with PTL and skin inflammation and in experimental human xenograft mouse models of psoriasis and CTCL. Quantitative (q)RT-PCR analysis of 103 patients with CTCL and benign skin disorders validates differential expression of 4 of the 5 miRNAs and confirms previous reports on miR-155 in CTCL. A qRT-PCR-based classifier consisting of miR-155, miR-203, and miR-205 distinguishes CTCL from benign disorders with high specificity and sensitivity, and with a classification accuracy of 95%, indicating that miRNAs have a high diagnostic potential in CTCL.

Immature truncated O-glycophenotype of cancer directly induces oncogenic features

Significance Cancer cells characteristically express proteins with immature O-glycosylation, but how and why cancer cells express immature O-glycans has remained poorly understood. Here, we report that one prevalent mechanism in pancreatic cancer is epigenetic silencing, rather than somatic mutations in a key chaperone, core 1 β3-Gal-T-specific molecular chaperone (COSMC), required for mature elongated O-glycosylation. We also demonstrate, with the use of well-defined cell systems generated by precise gene editing, that the aberrant O-glycophenotype by itself induces oncogenic features with enhanced growth and invasion. Our study suggests that the characteristic aberrant O-glycophenotype is critical for the development and behavior of cancer and further provides support for immunotherapeutic strategies that target aberrant O-glycans. Aberrant expression of immature truncated O-glycans is a characteristic feature observed on virtually all epithelial cancer cells, and a very high frequency is observed in early epithelial premalignant lesions that precede the development of adenocarcinomas. Expression of the truncated O-glycan structures Tn and sialyl-Tn is strongly associated with poor prognosis and overall low survival. The genetic and biosynthetic mechanisms leading to accumulation of truncated O-glycans are not fully understood and include mutation or dysregulation of glycosyltransferases involved in elongation of O-glycans, as well as relocation of glycosyltransferases controlling initiation of O-glycosylation from Golgi to endoplasmic reticulum. Truncated O-glycans have been proposed to play functional roles for cancer-cell invasiveness, but our understanding of the biological functions of aberrant glycosylation in cancer is still highly limited. Here, we used exome sequencing of most glycosyltransferases in a large series of primary and metastatic pancreatic cancers to rule out somatic mutations as a cause of expression of truncated O-glycans. Instead, we found hypermethylation of core 1 β3-Gal-T-specific molecular chaperone, a key chaperone for O-glycan elongation, as the most prevalent cause. We next used gene editing to produce isogenic cell systems with and without homogenous truncated O-glycans that enabled, to our knowledge, the first polyomic and side-by-side evaluation of the cancer O-glycophenotype in an organotypic tissue model and in xenografts. The results strongly suggest that truncation of O-glycans directly induces oncogenic features of cell growth and invasion. The study provides support for targeting cancer-specific truncated O-glycans with immunotherapeutic measures.

Malignant cutaneous T-cell lymphoma cells express IL-17 utilizing the Jak3/Stat3 signaling pathway.

IL-17 is a proinflammatory cytokine that is crucial for the hosts protection against a range of extracellular pathogens. However, inappropriately regulated expression of IL-17 is associated with the development of inflammatory diseases and cancer. In cutaneous T-cell lymphoma (CTCL), malignant T cells gradually accumulate in skin lesions characterized by massive chronic inflammation, suggesting that IL-17 could be involved in the pathogenesis. In this study we show that IL-17 protein is present in 10 of 13 examined skin lesions but not in sera from 28 CTCL patients. Importantly, IL-17 expression is primarily observed in atypical lymphocytes with characteristic neoplastic cell morphology. In accordance, malignant T-cell lines from CTCL patients produce IL-17 and the synthesis is selectively increased by IL-2 receptor β chain cytokines. Small-molecule inhibitors or small interfering RNA against Jak3 and signal transducer and activator of transcription 3 (Stat3) reduce the production of IL-17, showing that the Jak3/Stat3 pathway promotes the expression of the cytokine. In summary, our findings indicate that the malignant T cells in CTCL lesions express IL-17 and that this expression is promoted by the Jak3/Stat3 pathway.

STAT5-mediated expression of oncogenic miR-155 in cutaneous T-cell lymphoma

The pathogenesis of cutaneous T-cell lymphoma (CTCL) remains elusive. Recent discoveries indicate that the oncogenic microRNA miR-155 is overexpressed in affected skin from CTCL patients. Here, we address what drives the expression of miR-155 and investigate its role in the pathogenesis of CTCL. We show that malignant T cells constitutively express high levels of miR-155 and its host gene BIC (B cell integration cluster). Using ChIP-seq, we identify BIC as a target of transcription factor STAT5, which is aberrantly activated in malignant T cells and induced by IL-2/IL-15 in non-malignant T cells. Incubation with JAK inhibitor or siRNA-mediated knockdown of STAT5 decreases BIC/miR-155 expression, whereas IL-2 and IL-15 increase their expression in cell lines and primary cells. In contrast, knockdown of STAT3 has no effect, and BIC is not a transcriptional target of STAT3, indicating that regulation of BIC/miR-155 expression by STAT5 is highly specific. Malignant proliferation is significantly inhibited by an antisense-miR-155 as well as by knockdown of STAT5 and BIC. In conclusion, we provide the first evidence that STAT5 drives expression of oncogenic BIC/miR-155 in cancer. Moreover, our data indicate that the STAT5/BIC/miR-155 pathway promotes proliferation of malignant T cells, and therefore is a putative target for therapy in CTCL.

Elucidating the role of interleukin-17F in cutaneous T-cell lymphoma

Inappropriately regulated expression of interleukin (IL)-17A is associated with the development of inflammatory diseases and cancer. However, little is known about the role of other IL-17 family members in carcinogenesis. Here, we show that a set of malignant T-cell lines established from patients with cutaneous T-cell lymphoma (CTCL) spontaneously secrete IL-17F and that inhibitors of Janus kinases and Signal transducer and activator of transcription 3 are able to block that secretion. Other malignant T-cell lines produce IL-17A but not IL-17F. Upon activation, however, some of the malignant T-cell lines are able to coexpress IL-17A and IL-17F, leading to formation of IL-17A/F heterodimers. Clinically, we demonstrate that IL-17F messenger RNA expression is significantly increased in CTCL skin lesions compared with healthy donors and patients with chronic dermatitis. IL-17A expression is also increased and a significant number of patients express high levels of both IL-17A and IL-17F. Concomitantly, we observed that the expression of the IL-17 receptor is significantly increased in CTCL skin lesions compared with control subjects. Importantly, analysis of a historic cohort of 60 CTCL patients indicates that IL-17F expression is associated with progressive disease. These findings implicate IL-17F in the pathogenesis of CTCL and suggest that IL-17 cytokines and their receptors may serve as therapeutic targets.

COX-2-dependent PGE(2) acts as a growth factor in mycosis fungoides (MF).

Cancer often originates from a site of persistent inflammation, and the mechanisms turning chronic inflammation into a driving force of carcinogenesis are intensely investigated. Cyclooxygenase-2 (COX-2) is an inducible key modulator of inflammation that carries out the rate-limiting step in prostaglandin synthesis. Aberrant COX-2 expression and prostaglandin E2 (PGE2) production have been implicated in tumorigenesis. In this study we show that COX-2 is ectopically expressed in malignant T-cell lines from patients with cutaneous T-cell lymphoma (CTCL) as well as in situ in lymphocytic cells in 21 out of 22 patients suffering from mycosis fungoides (MF) in plaque or tumor stage. COX-2 is not expressed in lymphocytes of 11 patients with patch-stage MF, whereas sporadic COX-2 staining of stromal cells is observed in the majority of patients. COX-2 expression correlates with a constitutive production of PGE2 in malignant T cells in vitro. These cells express prostaglandin receptors EP3 and EP4 and the receptor antagonist as well as small interfering RNA (siRNA) directed against COX-2, and specific COX-2 inhibitors strongly reduce their spontaneous proliferation. In conclusion, our data indicate that COX-2 mediated PGE2 exerts an effect as a tumor growth factor in MF.

A novel xenograft model of cutaneous T-cell lymphoma.

Please cite this paper as: A novel xenograft model of cutaneous T‐cell lymphoma. Experimental Dermatology 2010; 19: 1096–1102.

Programmed cell death-10 enhances proliferation and protects malignant T cells from apoptosis

Lauenborg B, Kopp K, Krejsgaard T, Eriksen KW, Geisler C, Dabelsteen S, Gniadecki R, Zhang Q, Wasik MA, Woetmann A, Odum N. Programmed cell death‐10 enhances proliferation and protects malignant T cells from apoptosis. APMIS 2010; 118: 719–28.

Expression of miR-155 and miR-126 in situ in cutaneous T-cell lymphoma.

Recently, miR‐155 has been implicated in cutaneous T‐cell lymphoma (CTCL). Thus, elevated levels of miR‐155 were observed in skin lesions from CTCL patients as judged from qPCR and micro‐array analysis and aberrant, high miR‐155 expression was associated with severe disease. Moreover, miR‐155 promoted proliferation of malignant T cells in vitro. Little is, however, known about which cell types express miR‐155 in vivo in CTCL skin lesions. Here, we study miR‐155 expression using in situ hybridization (ISH) with a miR‐155 probe, a negative control (scrambled), and a miR‐126 probe as a positive control in nine patients with mycosis fungoides, the most frequent subtype of CTCL. We provide evidence that both malignant and non‐malignant T cells stain weakly to moderately positive with the miR‐155 probe, but generally negative with the miR‐126 and negative control probes. Reversely, endothelial cells stain positive for miR‐126 and negative for miR‐155 and the control probe. Solitary T cells with a malignant morphology display brighter staining with the miR‐155 probe. Taken together, our findings suggest that both malignant and non‐malignant T cells express miR‐155 in situ in CTCL. Moreover, they indicate heterogeneity in miR‐155 expression among malignant T cells.

Validation of a diagnostic microRNA classifier in cutaneous T-cell lymphomas

Troels Marstrand 1 * , Charlotte B. Ahler 1,2 * , Ulrik Ralfkiaer 3,4 , Anders Clemmensen 5 , Katharina L. Kopp 3 , Nina A. Sibbesen 3 , Thorbj ø rn Krejsgaard 3 , Thomas Litman 1 , Mariusz A. Wasik 6 , Charlotte M. Bonefeld 3 , Kirsten Gr ø nb æ k 4 , Lise Mette Rahbek Gjerdum 7 , Robert Gniadecki 8 , Elisabeth Ralfkiaer 7 , Carsten Geisler 3 , Anders Woetmann 3 , Mads A. R ø pke 1 , Christian Glue 2 , Lone Skov 5 & Niels Odum 2