Cloning of a cDNA Encoding an Isoform of Human Protein Phosphatase Inhibitor 2 from Vascularized Breast Tumor

Using modified differential display, a gene fragment was identified as being over-expressed in human vascularized breast carcinoma when compare to its neighboring normal tissue. The differentially expressed pattern was confirmed by quantitative RT-PCR. Full-length cDNA was then cloned by both 3′-end RACE and 5′-end RACE. Analysis of the full-length cDNA of this gene reveals that this cDNA encodes an open reading frame of 615 bp, which is highly homologous to human protein phosphatase inhibitor-2, with 92% identity at the nucleotide level, and 89% identity at amino acid level. The results of this study suggest that this novel isoform of human protein phosphatase inhibitor-2 (nPPI-2) may be involved in the angiogenic switch during breast tumor development.