Use of suppression subtractive hybridization strategy for cloning and identifying specifically expressed genes of renal cell carcinoma

Using suppression subtractive hybridization, a renal cell carcinoma (RCC) cDNA subtractive library which only contains differently expressed cDNAs between human RCC and normal kidney has been constructed. 200 clones were picked out randomly to perform enzyme digest analysis, a part of them underwent sequence analysis and Northern blot to identify RCC specially expressed genes. Results showed that 190 clones contain 50-400 bp inserts respectively. Sequence analysis was performed in 10 clones. All the 10 sequences were unknown before and derived from 6 unique novel genes among which the cDNA insert RCC18 has five copies. Northern blot analysis showed that RCC18 cDNA expressed highly in RCC, but there was no signal detected in normal kidney, and the full length of RCC18 was about 2.5 kb. The constructed cDNA subtractive library of human RCC is a highly efficient one and lays the solid foundation for large-scale screening and cloning new and specific oncogenes or tumor suppressor genes of RCC. The novel

Aberrant activity of Wnt/Frizzled signaling pathway in renal cancer cell lines

The expression of Wnt, Wnt receptor-Frizzled, and several other key components in Wnt pathway in renal cancer cell lines was studied. The result of semi-quantitative RT-PCR has shown that the expression level of Wnt5A and hFz5 mRNA were higher in renal cancer cell line (GRC-1) than in normal renal cell line (HK-2). This result has been confirmed by in situ hybridization. The expression of p-catenin protein was obviously higher in GRC-1 than in HK-2 (P【0.01), but there were no different expressions of its mRNA between 3 lines. The reasons of the overexpression of β-catenin has been investigated by means of immunocytochemistry, SSCP and so on, no mutation of β-catenin gene and APC were found. That means that the overexpression of Wnt5A/hFz5 might be the reason of overexpression of β-catenin. It was concluded that the aberrant activity of Wnt pathway might play an important role in renal cell carcinoma.

Interaction of hTCF4 by yeast two-hybrid system

To investigate the interaction of hTCF4, the yeast two-hybrid system has been used for testing the interaction of mutants of hTCF4 with themselves. Mutants of hTCF4 (hTCF4 Ⅰ ) and hTCF4 Ⅱ) have been obtained by polymerase chain reaction (PCR). Bait (hTCF4 Ⅰ -pDBLeu and hTCF4Ⅱ-pDBLeu) and prey (hTCF4 Ⅰ -pPC86 and hTCF4Ⅱ-pPC86) have been constructed by DNA recombination for yeast two-hybrid. Interaction of hTCF4Ⅱ with itself is found in the reverse yeast two-hybrid system (GIBCOBRL Co.). However, no interactions are found in hTCF4Ⅱ with hTCF4 Ⅰ and in hTCF4 Ⅰ with hTCF4 Ⅰ . These results suggest that hTCF4 could interact with itself to form homodimer or homocopolymer and perform the transcriptional activating function through LZ or HLH motifs in nucleus of renal cell carcinoma.

Androgen receptor coregulator ARA267-α interacts with death receptor-6 revealed by the yeast two-hybrid

ARA267-a is a newly identified androgen receptor coactivator. In order to further elucidate its precise role in cells, using the ARA267- a fragment containing four PHD and one SET conserved domains as bait we revealed an ARA267-a-PHD-SET-interacting protein, death receptor-6 (DR6), in the yeast two-hybrid screening. DR6 is the member of TNF receptor family and has a death domain in its intracellular cytoplasmic portion (DR6cp) to mediate the cell apoptosis. The interaction between ARA267-a-PHD-SET and DR6cp was confirmed in vitro and in vivo. Our finding implied that androgen signaling pathway might cross talk with apoptosis sig-naling pathway through the interaction between ARA267-a and DR6.