Immunohistochemical staining Formalin-fixed and paraffin-embedded clear cell renal carcinoma tissue blocks were from the The First Clinical Hospital of Jilin University. Tissue blocks were sectioned and deparaffinized in xylene and rehydrated through a graded ethanol series. Tissue slides were then subjected to antigen retrieval by boiling in 0.01 M sodium citrate buffer (pH 6) in a microwave oven for 10 min. Endogenous peroxidase was blocked by incubation for 10 min in 3% hydrogen peroxide in methanol. Finally, the reactions were detected using the DAB detection kit (Dako). Anti-MYST1 and acetylated H4K16 polyclonal antibodies were used at a 1:500 dilution. MYST1 protein expression
status and the histone H4K16 acetylation levels were estimated #selleck chemicals randurls[1|1|,|CHEM1|]# in a four-step scale (none, weak, moderate, strong). The determination criteria
are shown below: score 0 = none, no staining or nuclear staining <10% of tumor cells; score 1 = weak, partial or weak complete nuclear staining >10% of tumor cells; score 2 = moderate complete nuclear staining >10% of tumor cells; score 3 = strong and complete nuclear staining in >10% of tumor cells . Transient transfection Human embryonic kidney (HEK) 293T cells, renal cell carcinomas 786–0 and OS-RC-2 cells were cultured in 6 well tissue culture plates (~2 × 105 cells/well) in DMEM containing 10% fetal bovine serum and antibiotics. The cells were transiently transfected with 0.25~2 μg of hMOF cDNAs TPX-0005 in vitro using polyethylenimine
(PEI). At 48 hrs post-transfection, cells were harvested and lysed for immunoblot and RT-PCR analysis. Statistical analysis The expression difference of genes and proteins between ccRCC and normal tissues were statistically analyzed. Statistical analysis was completed with SPSS 17.0 (SPSS, Inc., Chicago IL). Statistical comparisons were analyzed using the student’s t-test. Values of P < 0.05 were considered to be statistically significant. Results Downregulation of hMOF mRNA in primary renal cell carcinoma tissues In order to know whether the hMOF is involved in the pathogenesis of primary RCC or not, we first examined the mRNA levels of hMOF and other hypoxia signature genes including CA9, VEGF and HIF1α in 4 random cases of 2-hydroxyphytanoyl-CoA lyase newly diagnosed ccRCC (Figure 1A) by reverse transcription PCR (RT-PCR) and quantitative real-time PCR (qPCR). As shown in Figure 1B, the gene expression levels of hMOF were markedly decreased in all ccRCC tissues compared to matched normal tissues (p<0.001). In contrast, CA9 expression levels were significantly increased in all ccRCC tissues (p<0.01). However, no significant difference was observed in VEGF and HIF1α expression. Additional 16 paired clinical ccRCC and matched normal tissues were used to further validate the frequent downregulation of hMOF mRNA expression in primary ccRCC. Analysis of performed mRNA expression of 16 samples revealed significant (>2-fold decreased) downregulation of hMOF mRNA in 87.