Class I histone deacetylases 1, 2 and 3 are highly expressed in renal cell cancer

We investigated the expression of HDAC 1, 2 and 3 in 106 renal cell carcinomas and corresponding normal renal tissue by immunohistochemistry on tissue micro arrays and correlated expression data with clinico-pathological parameters including patient survival.Almost 60% of renal cell carcinomas expressed the HDAC isoforms 1 and 2. In contrast, HDAC 3 was only detected in 13% of all renal tumours, with particular low expression rates in the clear cell subtype. HDAC 3 was significantly higher expressed in pT1/2 tumours in comparison to pT3/4 tumours. Expression of class I HDAC isoforms correlated with each other and with the proliferative activity of the tumours. We found no prognostic value of the expression of any of the HDAC isoforms in this tumour entity.Class I HDAC isoforms 1 and 2 are highly expressed in renal cell cancer, while HDAC 3 shows low, histology dependent expression rates. These unexpected differences in the expression patterns suggests alternative regulatory mechanisms of class I HDACs in renal cell cancer and should be taken into account when trials with isoform selective HDI are being planned. Whether HDAC expression in renal cancers is predictive of responsiveness for HDI will have to be tested in further studies.The family of histone deacetylases (HDAC) comprises 18 isoforms which are categorized into four classes. Functionally, HDACs have been demonstrated to be involved in the deacetylation of histone tails in the nucleosomal organization units which leads to a tighter wrapping of the DNA around the histone core, which in turn results in an activation or inhibition of gene transcription [1]. In addition, HDACs influence the direct acetylation pattern of a variety of tumour relevant non-histone proteins, thus influencing their subcellular localization, interaction partners and functions [2,3]. Expression patterns of HDACs in solid human tumours have been in the focus of our group and many oncological researchers alike [4-9]. This research has be