TY  - JOUR
A1  - Adam, Christian
A1  - Baeurle, Anne
A1  - Brodsky, Jeffrey L.
A1  - Schrama, David
A1  - Wipf, Peter
A1  - Becker, Jürgen Christian
A1  - Houben, Roland
T1  - The HSP70 Modulator MAL3-101 Inhibits Merkel Cell Carcinoma
N2  - 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.
KW  - apoptosis
KW  - cancer treatment
KW  - cell staining
KW  - cultured fibroplasts
KW  - heat shock response
KW  - membrans proteins
KW  - polymerase chain reaction
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-112795
ER  - 
TY  - JOUR
A1  - Hafner, Christian
A1  - Houben, Roland
A1  - Baeurle, Anne
A1  - Ritter, Cathrin
A1  - Schrama, David
A1  - Landthaler, Michael
A1  - Becker, Jürgen C.
T1  - Activation of the PI3K/AKT Pathway in Merkel Cell Carcinoma
JF  - PLoS One
N2  - 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.
KW  - rare
KW  - T-antigen
KW  - PIK3CA mutations
KW  - squamous cell
KW  - melanoma
KW  - polymavirus
KW  - cancer
KW  - tumors
KW  - akt
KW  - expression
Y1  - 2012
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-131398
VL  - 7
IS  - 2
ER  -