A novel ankyrin repeat-containing gene (Kank) located at 9p24 is a growth suppressor of renal cell carcinoma

By a combination of genome subtraction and comprehensive analysis of loss of heterozygosity based on mapping hemizygous deletions for a potential tumor-related locus, a minimum overlapping region of deletions at 9p24 the size of 165 kb was identified and found to harbor a new potential tumor suppressor gene for renal cell carcinoma, the Kank gene. Kank (for kidney ankyrin repeat-containing protein) contains four ankyrin repeats at its C terminus. Expression of the gene was suppressed in 6 of 8 or 6 of 10 cancer tissues examined by reverse transcription-PCR or Western blotting, respectively, and in several kidney tumor cell lines due to methylation at CpG sites in the gene. Epigenetic methylation or imprinting seemed to be the first hit, which was followed by a second hit of deletion, resulting in loss of function in many of these deletion cases. Expression of this gene in expression-negative HEK293 cells induced growth retardation at G₀/G₁ as well as morphological changes.