Recently, a new and highly effective method termed suppressive subtractive hybridization (SSH) has been introduced to clone differentially expressed mRNAs. Genes expressed in androgen-independent but not in androgen-dependent tumors, and vice versa, are obviously significant to delineate the mechanisms of androgen dependency/independency of these tumors. Mouse mammary cancer (Shionogi carcinoma-115) has been extensively used to analyze the mechanism of androgen-dependent cancer growth.
Methods: We cloned androgen-independent and androgen-dependent Shionogi carcinoma-115 specific mRNAs by the SSH method. Cloned sequences were compared with known sequences using NCBI BLAST across the Internet. Two clones were positive for cDNA insert when androgen-independent cDNA was used as tester cDNA, while no clones were positive using the androgen-dependent tester cDNA. One of the former was mouse protein kinase C beta-II while the other was a new DNA sequence. Mouse protein kinase C beta-II mRNA and the new mRNA were shown to be differentially expressed by RT-PCR analysis in androgen-independent but not androgen-dependent Shionogi carcinoma. Two mRNA species differentially expressed in androgen-independent but not androgen-dependent Shionogi carcinoma were cloned by the SSH method. The significance of these mRNAs for androgen-dependency/independency of Shionogi carcinoma should be explained in future studies.