@article{OroujiPeitschOroujietal.2020,
  author    = {Orouji, Elias and Peitsch, Wiebke K. and Orouji, Azadeh and Houben, Roland and Utikal, Jochen},
  title     = {Unique role of histone methyltransferase PRDM8 in the tumorigenesis of virus-negative Merkel cell carcinoma},
  series = {Cancers},
  volume    = {12},
  journal   = {Cancers},
  number    = {4},
  issn      = {2072-6694},
  doi       = {10.3390/cancers12041057},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-203815},
  year      = {2020},
  abstract  = {Merkel cell carcinoma (MCC) is a deadly skin cancer, and about 80\% of its cases have been shown to harbor integrated Merkel polyomavirus in the tumor cell genome. Viral oncoproteins expressed in the tumor cells are considered as the oncogenic factors of these virus-positive Merkel cell carcinoma (VP-MCC). In contrast, the molecular pathogenesis of virus-negative MCC (VN-MCC) is less well understood. Using gene expression analysis of MCC cell lines, we found histone methyltransferase PRDM8 to be elevated in VN-MCC. This finding was confirmed by immunohistochemical analysis of MCC tumors, revealing that increased PRDM8 expression in VN-MCC is also associated with increased H3K9 methylation. CRISPR-mediated silencing of PRDM8 in MCC cells further supported the histone methylating role of this protein in VN-MCC. We also identified miR-20a-5p as a negative regulator of PRDM8. Taken together, our findings provide insights into the role of PRDM8 as a histone methyltransferase in VN-MCC tumorigenesis.},
  language  = {en}
}
@article{HesbacherPfitzerWiedorferetal.2016,
  author    = {Hesbacher, Sonja and Pfitzer, Lisa and Wiedorfer, Katharina and Angermeyer, Sabrina and Borst, Andreas and Haferkamp, Sebastian and Scholz, Claus-J{\"u}rgen and Wobser, Marion and Schrama, David and Houben, Roland},
  title     = {RB1 is the crucial target of the Merkel cell polyomavirus Large T antigen in Merkel cell carcinoma cells},
  series = {Oncotarget},
  volume    = {7},
  journal   = {Oncotarget},
  number    = {22},
  doi       = {10.18632/oncotarget.8793},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-177858},
  pages     = {32956-32968},
  year      = {2016},
  abstract  = {The pocket protein (PP) family consists of the three members RB1, p107 and p130 all possessing tumor suppressive properties. Indeed, the PPs jointly control the G1/S transition mainly by inhibiting E2F transcription factors. Notably, several viral oncoproteins are capable of binding and inhibiting PPs. Merkel cell polyomavirus (MCPyV) is considered as etiological factor for Merkel cell carcinoma (MCC) with expression of the viral Large T antigen (LT) harboring an intact PP binding domain being required for proliferation of most MCC cells. Therefore, we analyzed the interaction of MCPyV-LT with the PPs. Co-IP experiments indicate that MCPyV-LT binds potently only to RB1. Moreover, MCPyV-LT knockdown-induced growth arrest in MCC cells can be rescued by knockdown of RB1, but not by p107 or p130 knockdown. Accordingly, cell cycle arrest and E2F target gene repression mediated by the single PPs can only in the case of RB1 be significantly reverted by MCPyV-LT expression. Moreover, data from an MCC patient indicate that loss of RB1 rendered the MCPyV-positive MCC cells LT independent. Thus, our results suggest that RB1 is the dominant tumor suppressor PP in MCC, and that inactivation of RB1 by MCPyV-LT is largely sufficient for its growth supporting function in established MCPyV-positive MCC cells.},
  language  = {en}
}
@article{FreyHoubenBroecker2010,
  author    = {Frey, Li­dia M. and Houben, Roland and Br{\"o}cker, Eva-B.},
  title     = {Pigmentation, Melanocyte Colonization, and p53 Status in Basal Cell Carcinoma},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68283},
  year      = {2010},
  abstract  = {Basal cell carcinoma (BCC) is the most common neoplasm in the Caucasian population. Only a fraction of BCC exhibits pigmentation. Lack of melanocyte colonization has been suggested to be due to p53-inactivating mutations in the BCC cells interfering with the p53-proopiomelanocortin pathway and the production of alpha melanocyte-stimulating hormone in the tumor. To evaluate this, we determined tumor pigmentation as well as expression of melan-A and of p53 in 49 BCC tissues bymeans of immunohistochemistry. As expected, we observed a positive relation between tumor pigmentation and melan-A positive intratumoral melanocytes.Melanocyte colonization and, to a lesser extent, p53 overexpression showed intraindividual heterogeneity in larger tumors. p53 overexpression, which is indicative of p53 mutations, was not correlated to melanocyte colonization of BCC. Sequencing of exon 5-8 of the p53 gene in selected BCC cases revealed that colonization by melanocytes and BCC pigmentation is neither ablated by p53 mutations nor generally present in BCCs with wild-type p53.},
  subject      = {Medizin},
  language  = {en}
}
@article{HoubenHesbacherSchmidetal.2011,
  author    = {Houben, Roland and Hesbacher, Sonja and Schmid, Corinna P. and Kauczok, Claudia S. and Flohr, Ulrike and Haferkamp, Sebastian and M{\"u}ller, Cornelia S. L. and Schrama, David and Wischhusen, J{\"o}rg and Becker, J{\"u}rgen C.},
  title     = {High-Level Expression of Wild-Type p53 in Melanoma Cells is Frequently Associated with Inactivity in p53 Reporter Gene Assays},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-69012},
  year      = {2011},
  abstract  = {Background: Inactivation of the p53 pathway that controls cell cycle progression, apoptosis and senescence, has been proposed to occur in virtually all human tumors and p53 is the protein most frequently mutated in human cancer. However, the mutational status of p53 in melanoma is still controversial; to clarify this notion we analysed the largest series of melanoma samples reported to date. Methodology/Principal Findings: Immunohistochemical analysis of more than 180 melanoma specimens demonstrated that high levels of p53 are expressed in the vast majority of cases. Subsequent sequencing of the p53 exons 5-8, however, revealed only in one case the presence of a mutation. Nevertheless, by means of two different p53 reporter constructs we demonstrate transcriptional inactivity of wild type p53 in 6 out of 10 melanoma cell lines; the 4 other p53 wild type melanoma cell lines exhibit p53 reporter gene activity, which can be blocked by shRNA knock down of p53. Conclusions/Significance: In melanomas expressing high levels of wild type p53 this tumor suppressor is frequently inactivated at transcriptional level.},
  subject      = {Krebs <Medizin>},
  language  = {en}
}
@article{HaferkampHesbacherWeyandtetal.2014,
  author    = {Haferkamp, Sebastian and Hesbacher, Sonja and Weyandt, Gerhard and Vetter-Kauczok, Claudia S. and Becker, J{\"u}rgen C. and Motschenbacher, Stephanie and Wobser, Marion and Maier, Melissa and Schmid, Corinna P. and Houben, Roland},
  title     = {p53 regulation by TRP2 is not pervasive in melanoma},
  doi       = {10.1371/journal.pone.0087440},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-111396},
  year      = {2014},
  abstract  = {p53 is a central tumor suppressor protein and its inhibition is believed to be a prerequisite for cancer development. In approximately 50\% of all malignancies this is achieved by inactivating mutations in the p53 gene. However, in several cancer entities, including melanoma, p53 mutations are rare. It has been recently proposed that tyrosinase related protein 2 (TRP2), a protein involved in melanin synthesis, may act as suppressor of the p53 pathway in melanoma. To scrutinize this notion we analyzed p53 and TRP2 expression by immunohistochemistry in 172 melanoma tissues and did not find any correlation. Furthermore, we applied three different TRP2 shRNAs to five melanoma cell lines and could not observe a target specific effect of the TRP2 knockdown on either p53 expression nor p53 reporter gene activity. Likewise, ectopic expression of TRP2 in a TRP2 negative melanoma cell line had no impact on p53 expression. In conclusion our data suggest that p53 repression critically controlled by TRP2 is not a general event in melanoma.},
  language  = {en}
}
@article{VamanVSPoppeHoubenetal.2015,
  author    = {Vaman V. S., Anjana and Poppe, Heiko and Houben, Roland and Grunewald, Thomas G. P. and Goebeler, Matthias and Butt, Elke},
  title     = {LASP1, a Newly Identified Melanocytic Protein with a Possible Role in Melanin Release, but Not in Melanoma Progression},
  series = {PLoS One},
  volume    = {10},
  journal   = {PLoS One},
  number    = {6},
  doi       = {10.1371/journal.pone.0129219},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-125994},
  pages     = {e0129219},
  year      = {2015},
  abstract  = {The LIM and SH3 protein 1 (LASP1) is a focal adhesion protein. Its expression is increased in many malignant tumors. However, little is known about the physiological role of the protein. In the present study, we investigated the expression and function of LASP1 in normal skin, melanocytic nevi and malignant melanoma. In normal skin, a distinct LASP1 expression is visible only in the basal epidermal layer while in nevi LASP1 protein is detected in all melanocytes. Melanoma exhibit no increase in LASP1 mRNA compared to normal skin. In melanocytes, the protein is bound to dynamin and mainly localized at late melanosomes along the edges and at the tips of the cell. Knockdown of LASP1 results in increased melanin concentration in the cells. Collectively, we identified LASP1 as a hitherto unknown protein in melanocytes and as novel partner of dynamin in the physiological process of membrane constriction and melanosome vesicle release.},
  language  = {en}
}
@article{HafnerHoubenBaeurleetal.2012,
  author    = {Hafner, Christian and Houben, Roland and Baeurle, Anne and Ritter, Cathrin and Schrama, David and Landthaler, Michael and Becker, J{\"u}rgen C.},
  title     = {Activation of the PI3K/AKT Pathway in Merkel Cell Carcinoma},
  series = {PLoS One},
  volume    = {7},
  journal   = {PLoS One},
  number    = {2},
  doi       = {10.1371/journal.pone.0031255},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-131398},
  pages     = {e31255},
  year      = {2012},
  abstract  = {Merkel cell carcinoma (MCC) is a highly aggressive skin cancer with an increasing incidence. The understanding of the molecular carcinogenesis of MCC is limited. Here, we scrutinized the PI3K/AKT pathway, one of the major pathways activated in human cancer, in MCC. Immunohistochemical analysis of 41 tumor tissues and 9 MCC cell lines revealed high levels of AKT phosphorylation at threonine 308 in 88\% of samples. Notably, the AKT phosphorylation was not correlated with the presence or absence of the Merkel cell polyoma virus (MCV). Accordingly, knock-down of the large and small T antigen by shRNA in MCV positive MCC cells did not affect phosphorylation of AKT. We also analyzed 46 MCC samples for activating PIK3CA and AKT1 mutations. Oncogenic PIK3CA mutations were found in 2/46 (4\%) MCCs whereas mutations in exon 4 of AKT1 were absent. MCC cell lines demonstrated a high sensitivity towards the PI3K inhibitor LY-294002. This finding together with our observation that the PI3K/AKT pathway is activated in the majority of human MCCs identifies PI3K/AKT as a potential new therapeutic target for MCC patients.},
  language  = {en}
}
@article{BehrPeitschHametneretal.2014,
  author    = {Behr, Daniel S. and Peitsch, Wiebke K. and Hametner, Christian and Lasitschka, Felix and Houben, Roland and Sch{\"o}nhaar, Kathrin and Michel, Julia and Dollt, Claudia and Goebeler, Matthias and Marx, Alexander and Goerdt, Sergij and Schmieder, Astrid},
  title     = {Prognostic value of immune cell infiltration, tertiary lymphoid structures and PD-L1 expression in Merkel cell carcinomas},
  series = {International Journal of Clinical and Experimental Pathology},
  volume    = {7},
  journal   = {International Journal of Clinical and Experimental Pathology},
  number    = {11},
  issn      = {1936-2625},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-117720},
  pages     = {7610-7621},
  year      = {2014},
  abstract  = {Merkel cell carcinoma (MCC) is an aggressive, virus-associated, neuroendocrine tumor of the skin mainly affecting immunocompromised patients. Higher intratumoral infiltration with CD3 and CD8 positive T-cells is associated with a better prognosis, highlighting the relevance of the immune system for MCC development and progression. In this study 21 primary MCCs were stained with immune cell markers including CD3, CD4, CD8, CD68, CD20, and S100. Furthermore, tumor-infiltrating neutrophils, tertiary lymphoid structures and PD-L1 expression were analyzed and correlated with overall and recurrence free survival. All MCCs were Merkel Cell Polyomavirus positive. Overall and recurrence-free survival did not correlate with intra-and peritumoral CD3 and CD8 T-cell infiltration. In addition, no significant association regarding prognosis was found for tumor-associated neutrophils, tumor-associated macrophages or PD-L1 positivity in MCCs. Interestingly, the presence of tertiary lymphoid structures (TLS) in the tumor microenvironment significantly correlated with recurrence-free survival (P=0.025). In addition, TLS were significantly associated with a higher CD8/CD4 ratio in the tumor periphery (P=0.032), but not in the center of the tumor (P > 0.999). These results demonstrate for the first time that TLS, easily assessed in paraffin-embedded tissue in the tumor periphery of MCCs, may be a valuable prognostic factor indicating prolonged recurrence free survival.},
  language  = {en}
}
@article{AdamBaeurleBrodskyetal.2014,
  author    = {Adam, Christian and Baeurle, Anne and Brodsky, Jeffrey L. and Schrama, David and Wipf, Peter and Becker, J{\"u}rgen Christian and Houben, Roland},
  title     = {The HSP70 Modulator MAL3-101 Inhibits Merkel Cell Carcinoma},
  doi       = {10.1371/journal.pone.0092041},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-112795},
  year      = {2014},
  abstract  = {Merkel Cell Carcinoma (MCC) is a rare and highly aggressive neuroendocrine skin cancer for which no effective treatment is available. MCC represents a human cancer with the best experimental evidence for a causal role of a polyoma virus. Large T antigens (LTA) encoded by polyoma viruses are oncoproteins, which are thought to require support of cellular heat shock protein 70 (HSP70) to exert their transforming activity. Here we evaluated the capability of MAL3-101, a synthetic HSP70 inhibitor, to limit proliferation and survival of various MCC cell lines. Remarkably, MAL3-101 treatment resulted in considerable apoptosis in 5 out of 7 MCC cell lines. While this effect was not associated with the viral status of the MCC cells, quantitative mRNA expression analysis of the known HSP70 isoforms revealed a significant correlation between MAL3-101 sensitivity and HSC70 expression, the most prominent isoform in all cell lines. Moreover, MAL3-101 also exhibited in vivo antitumor activity in an MCC xenograft model suggesting that this substance or related compounds are potential therapeutics for the treatment of MCC in the future.},
  language  = {en}
}
@article{WobserSiedelKneitzetal.2013,
  author    = {Wobser, Marion and Siedel, Claudia and Kneitz, Hermann and Br{\"o}cker, Eva-Bettina and Goebeler, Mathias and Houben, Roland and Geissinger, Eva},
  title     = {Microvessel Density and Expression of Vascular Endothelial Growth Factor and its Receptors in Different Subtypes of Primary Cutaneous B-cell Lymphoma},
  series = {Acta Dermato-Venereologica},
  volume    = {93},
  journal   = {Acta Dermato-Venereologica},
  number    = {6},
  doi       = {10.2340/00015555-1589},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-128608},
  pages     = {656-662},
  year      = {2013},
  abstract  = {A proangiogenic micromilieu is associated with a worse prognosis in systemic lymphoma. Hence, targeting the tumour microenvironment and its vasculature has evolved as a promising novel treatment strategy. The role of tumour neoangiogenesis in cutaneous B-cell lymphoma, however, has not yet been elucidated. Therefore, we examined the expression of vascular endothelial growth factor (VEGF) and its receptors VEGFR-1 and VEGFR-2, as well as microvessel density by immunohistochemistry in paraffin-embedded specimens of different subtypes of primary cutaneous B-cell lymphomas, systemic diffuse large B-cell lymphoma, and cutaneous B-cell pseudolymphoma. Primary cutaneous large B-cell lymphoma (PCLBCL) were characterized by significantly higher intratumoral expression levels of VEGF and its receptors in comparison with the indolent lymphoma subtypes. Moreover, PCLBCL exhibited significantly higher intratumoral microvessel counts. Our study provides evidence that the most aggressive subtype of cutaneous B-cell lymphoma, PCLBCL, is characterized by a proangiogenic micromilieu.},
  language  = {en}
}