RESUMEN
<p><b>OBJECTIVE</b>To explore the Notch1 mRNA and protein expression in human breast cancers and normal mammary tissues, and their relationship with the clinical indicators of breast cancers were analyzed.</p><p><b>METHODS</b>Notch1 gene of human breast invasive ductal carcinoma (IDC) and normal mammary gland tissues were amplified by RT-PCR, and the expression of Notch1 protein was detected by immunohistochemical Streptavidin-Biotin Complex (SP) stain in 60 IDC, 30 ductal carcinoma in situ (DCIS) and 60 normal mammary tissues.</p><p><b>RESULTS</b>Notch1 gene of human IDC and normal mammary tissues both could express in a transcription level; the positive rates of Notch1 protein expression in normal mammary tissues and DCIS were 55% and 70%. Respectively, which did not differ statistically (P > 0.05), while the positive rate in IDC was 90%, significantly higher than that of the normal mammary tissues and DCIS (P < 0.05). The high expression of Notch1 protein in IDC correlate significantly with lymph node metastasis, pathological grades and TNM stages.</p><p><b>CONCLUSIONS</b>Notch1 protein was over expressed in breast IDC. A high Notch1 protein expression is considered associating with the evolution and malignant transformation of the breast tumor. The expression of Notch1 gene maybe impact the effect of on the progression of breast cancers.</p>