Loss of heterozygosity at 7p21 in adult renal tumors Three of the 36 adult patients samples analyzed showed LOH in the 2.4 Mb region of interest (Figure 2). Two of these patients had clear cell renal carcinoma (RCC-1 and RCC-614); while one had a less common oncocytoma (RCC-635). Patient RCC-614 showed LOH
over much of the area, while RCC-1 and RCC-635 showed LOH at approximately 15-20% of informative SNPs. Direct sequencing of Milciclib SOSTDC1 exons in adult tumors also showed LOH in patients RCC-614 and RCC-635 in several locations of exon 1 (Table 1). Additionally, patients RCC-129 and RCC-737 also showed LOH in one SNP each. The adult tumors displaying LOH did so at some but not all loci, selleck compound even within the SOSTDC1 gene itself. This is in contrast to what was observed within the Wilms tumors, where the samples with LOH displayed complete LOH at every heterozygous allele. Among all samples (adult and pediatric), LOH within SOSTDC1 was
observed mostly in the putative exon 1, with no observed heterozygosity loss in the regions of the gene that are known to be transcribed. Whether adult or Wilms, for each SNP that showed LOH in more than one sample, the same allele was lost. For example, at the beginning of exon 1 (position 16,536,641) the G is absent from the C/G in RCC-614 and RCC-635 (Table 1). Impact of SOSTDC1 LOH on protein expression We hypothesized that SOSTDC1 LOH might lead to decreased protein expression in the RCC and Wilms tumor samples. To Luminespib ic50 address this possibility, the SOSTDC1 protein expression of tumor samples with and without LOH at SOSTDC1 was analyzed by immunohistochemistry. Antiserum from rabbits immunized with a peptide corresponding to the 18 C-terminal amino
acids of the SOSTDC1 protein was used for this analysis. The antiserum has Meloxicam been used previously in an immunohistochemical application and additional characterization is included (; see Additional file 4). When tumor samples were stained for SOSTDC1, the protein showed defined perinuclear and diffuse cytosolic localization in both adult and pediatric renal tumors. Representative images are shown in Figure 3. SOSTDC1 expression was not markedly reduced within tumor samples with SOSTDC1 LOH in either Wilms tumors or RCC [compare Wilms -LOH (W-8178) to Wilms +LOH (W-733) in Figure 3A and adult renal tumors -LOH (RCC-347) to +LOH (RCC-614) in Figure 3B]. Other samples with SOSTDC1 LOH similarly exhibited no observable variations in SOSTDC1 protein expression or localization. As the SOSTDC1 -specific LOH in these samples was largely in the putative or regulatory exon 1 (Table 1), this observation is not necessarily unexpected. Figure 3 Immunohistochemical analyses of SOSTDC1 and β-catenin protein levels and localization. A) Pediatric Wilms tumor samples and B) adult renal cell carcinoma samples with and without SOSTDC1 LOH were stained with antibodies directed against SOSTDC1 and β-catenin.