[show abstract][hide abstract] ABSTRACT: We have been investigating gene-expression profiles in estrogen receptor (ER)-negative breast cancers to identify molecules involved in breast carcinogenesis and to select genes or gene products that might be useful as diagnostic markers or targets for new molecular therapies. Here we report evidence that the gene encoding retinoic acid-induced protein 3 (RAI3) is a potential molecular target for treatment of breast cancers. Using quantitative reverse transcription-PCR (RT-PCR), we documented increased expression of RAI3 in 19 of 25 primary breast cancers and in 6 of 11 breast-cancer cell lines examined, by comparison with normal mammary-gland tissue. Treatment of human embryonic kidney (HEK293) cells with siRNA against RAI3 suppressed expression of RAI3 and also suppressed cell growth. Transfection of siRNA into breast-cancer cell lines MCF7 and T47D also suppressed RAI3 mRNA and growth of the cancer cells. Because our data imply that up-regulation of RAI3 function is a frequent feature of breast carcinogenesis, we suggest that selective suppression of signal from RAI3 might hold promise for development of a new strategy for treating breast cancers.
Endocrine Related Cancer 04/2005; 12(1):65-73. · 5.26 Impact Factor
[show abstract][hide abstract] ABSTRACT: Estrogen receptor (ER) status is an essential determinant of clinical and biological behavior of human breast cancers. While ER-positive breast cancers respond well to adjuvant hormone therapy, ER-negative tumors are generally resistant. To date, no attempts have succeeded in finding molecular markers for classifying ER-negative breast cancers with respect to postoperative prognosis. To identify a set of prognostic markers for this type of cancer, we used a cDNA microarray consisting of 25,344 human genes to investigate expression profiles of ten primary breast cancers from patients who had died of breast cancer within 5 years after surgery (5y-D) and 10 from patients who had survived disease-free for more than 5 years (5y-S). Sets of genes characterizing each group were identified by Mann-Whitney and random-permutation tests. We documented 71 genes with higher expression in the 5y-D group than in the 5y-S group, and 15 with higher expression in the 5y-S group than in the 5y-D group. Semi-quantitative RT-PCR experiments were carried out to confirm the results of the microarray analysis. We established a scoring system for predicting postoperative prognosis of ER-negative breast cancers on the basis of aberrant gene expression. The list of genes reported here provides valuable information with regard to progression of breast cancer and is a source of possible target molecules for development of novel drugs to treat patients with ER-negative breast cancers.
Cancer Science 04/2004; 95(3):218-25. · 3.48 Impact Factor