Dimethylfumarate (DMF) inhibits signals transmitted by Rel proteins and is used for the treatment of inflammatory skin diseases such as psoriasis, but potential effects of DMF on tumor progression have yet not been analyzed. We show that DMF reduced melanoma growth and metastasis in severe combined immunodeficient mouse models. To identify targets of DMF action, we analyzed mRNA expression in DMF-treated melanomas by gene chip arrays. Using BiblioSphere software for data analysis, significantly regulated genes were mapped to Gene Ontology terms cell death, cell growth, and cell cycle. Indeed, we found that DMF inhibited proliferation of human melanoma cells A375 and M24met in vitro. The cell cycle was arrested at the G₂-M boundary. Moreover, DMF was proapoptotic, as shown by cell cycle analysis and by Annexin V and Apo2.7 staining. These results were confirmed in vivo. DMF reduced proliferation rates of tumor cells as assessed by Ki-67 immunostaining and increased apoptosis as assessed by terminal deoxyribonucleotidyl transferase–mediated dUTP nick end labeling staining. In conclusion, DMF is antiproliferative and proapoptotic and reduces melanoma growth and metastasis in animal models. (Cancer Res 2006; 66(24): 11888-96)

“Spleen tyrosine kinase” (Syk) is a member of the group of non-receptor type protein-tyrosine kinases that contains as a specified feature two Src Homology 2 domains located on the amino-terminal end of the protein. Syk is widely expressed in hematopoietic cells, but more recently Syk expression has been noted in multiple non-hematopoietic tissues including the liver ( Tsuchida et al, 2000 x Tsuchida et al., 2000 Tsuchida, S., Yanagi, S., Inatome, R. et al. Purification of a 72-kDa protein-tyrosine kinase from rat liver and its identification as Syk: Involvement of Syk in signaling events of hepatocytes. J Biochem. 2000; 127: 321–327 Crossref | PubMed | Scopus (37) | Google Scholar See all References Tsuchida et al, 2000 ), nasal epithelium ( Yamada et al, 2001 x Yamada et al., 2001 Yamada, T., Fujieda, S., Yanagi, S., Yamamura, H., Inatome, R., Sunaga, H., and Saito, H. Protein-tyrosine kinase Syk expressed in human nasal fibroblasts and its effect on RANTES production. J Immunol. 2001; 166: 538–543 Crossref | PubMed | Scopus (49) | Google Scholar See all References Yamada et al, 2001 ), and breast epithelium ( Coopman et al, 2000 x Coopman et al., 2000 Coopman, P.J., Do, M.T., Barth, M. et al. The Syk tyrosine kinase suppresses malignant growth of human breast cancer cells. Nature. 2000; 406: 742–747 Crossref | PubMed | Scopus (261) | Google Scholar See all References Coopman et al, 2000 ). The overwhelming part of functional data however still comes from hematopoietic cells where Syk exerts essential functions in immunoreceptor signalling, natural killer cell-mediated cytotoxicity or maturation of lymphocytes ( Cheng et al, 1995 x Cheng et al., 1995 Cheng, A.M., Rowley, B., Pao, W., Hayday, A., Bolen, J.B., and Pawson, T. Syk tyrosine kinase required for mouse viability and B-cell development. Nature. 1995; 378: 303–306 Crossref | PubMed | Scopus (489) | Google Scholar See all References Cheng et al, 1995 ; Turner et al, 1995 x Turner et al., 1995 Turner, M., Mee, P.J., Costello, P.S. et al. Perinatal lethality and blocked B-cell development in mice lacking the tyrosine kinase Syk. Nature. 1995; 378: 298–302 Crossref | PubMed | Scopus (572) | Google Scholar See all References Turner et al, 1995 ; Lin et al, 1996 x Lin et al., 1996 Lin, S., Cicala, C., Scharenberg, A.M., and Kinet, J.P. The Fc(epsilon)RI beta subunit functions as an amplifier of Fc(epsilon)RIgamma-mediated cell activation signals. Cell. 1996; 85: 985–995 Abstract | Full Text | Full Text PDF | PubMed | Scopus (278) | Google Scholar See all References Lin et al, 1996 ; Brumbaugh et al, 1997 x Brumbaugh et al., 1997 Brumbaugh, K.M., Binstadt, B.A., Billadeau, D.D., Schoon, R.A., Dick, C.J., Ten, R.M., and Leibson, P.J. Functional role for Syk tyrosine kinase in natural killer cell-mediated natural cytotoxicity. J Exp Med. 1997; 186: 1965–1974 Crossref | PubMed | Scopus (112) | Google Scholar See all References Brumbaugh et al, 1997 ).

Functional intestinal disorders constitute major, potentially lethal health problems in humans. Consequently, research focuses on elucidating the underlying pathobiological mechanisms and establishing therapeutic strategies. In this context, intestinal organoids have emerged as a potent in vitro model as they faithfully recapitulate the structure and function of the intestinal segment they represent. Interestingly, human-like intestinal diseases also affect dogs, making canine intestinal organoids a promising tool for canine and comparative research. Therefore, we generated organoids from canine duodenum, jejunum and colon, and focused on simultaneous long-term expansion and cell differentiation to maximize applicability. Following their establishment, canine intestinal organoids were grown under various culture conditions and then analyzed with respect to cell viability/apoptosis and multi-lineage differentiation by transcription profiling, proliferation assay, cell staining, and transmission electron microscopy. Standard expansion medium supported long-term expansion of organoids irrespective of their origin, but inhibited cell differentiation. Conversely, transfer of organoids to differentiation medium promoted goblet cell and enteroendocrine cell development, but simultaneously induced apoptosis. Unimpeded stem cell renewal and concurrent differentiation was achieved by culturing organoids in the presence of tyrosine kinase ligands. Our findings unambiguously highlight the characteristic cellular diversity of canine duodenum, jejunum and colon as fundamental prerequisite for accurate in vitro modelling.

Bovine papillomavirus types 1 and 2 (BPV-1 and BPV-2) are known to induce common equine skin tumours, termed sarcoids. Recently, it was demonstrated that vaccination with BPV-1 virus-like particles (VLPs) is safe and highly immunogenic in horses. To establish a BPV-1 challenge model for evaluation of the protective potential of BPV-1 VLPs, four foals were injected intradermally with infectious BPV-1 virions and with viral genome-based and control inocula, and monitored daily for tumour development. Blood was taken before inoculation and at weekly intervals. BPV-1-specific serum antibodies were detected by a pseudo-virion neutralization assay. Total nucleic acids extracted from tumours, intact skin and PBMCs were tested for the presence of BPV-1 DNA and mRNA using PCR and RT-PCR, respectively. Intralesional E5 oncoprotein expression was determined by immunofluorescence. Pseudo-sarcoids developed exclusively at sites inoculated with virions. Tumours became palpable 11–32 days after virion challenge, reached a size of ≤20 mm in diameter and then resolved in ≤6 months. No neutralizing anti-BPV-1 serum antibodies were detectable pre- or post-challenge. BPV-1 DNA was present in lesions but not in intact skin. In PBMCs, viral DNA was already detectable before lesions were first palpable, in concentrations correlating directly with tumour growth kinetics. PBMCs from two of two foals also harboured E5 mRNA. Immunofluorescence revealed the presence of the E5 protein in tumour fibroblasts, but not in the apparently normal epidermis overlying the lesions. Together with previous findings obtained in horses and cows, these data suggest that papillomavirus infection may include a viraemic phase.