Breast carcinomas are highly malignant tumor that the angiogenesis factor, vascular endothelial growth factor and its receptors are overexpressed. To elucidate the role of Angiopoietin-2 (ANG2) and ANG2 receptor Tie-2 in invasive ductal carcinoma, we examined the expression of ANG2, and Tie-2 at the mRNA and protein levels in human breast cancer cell lines and samples.

Total RNA from 22 breast cancer patient biopsies were extracted. ANG2 and Tie-2 mRNA expression was measured by means of reverse transcription-PCR assay.

RT-PCR indicated that the ANG2 and Tie-2 mRNA levels in carcinoma samples were significantly higher than those of the adjacent non-neoplastic breast tissues. For ANG2 and Tie-2, 41 of 71 invasive ductal carcinomass (58%) showed high expressions in Immunohistochemistry. Immunohistochemical analysis demonstrated that ANG2 and Tie-2 were expressed by both tumor cells and endothelial elements. Expression in tumor cells were confirmed by studying a panel of human breast carcinoma cell lines cultured by RT-PCR. Our study showed that the ANG2 positivity was correlated with axillary lymph node metastasis among the clinicopathological parameter and confirmed that high expressions of ANG2 correlated highly with the axillary lymph node metastases, histological grade, positive PR status, and age, and Tie-2 expression correlated significantly with the p53 status. Moreover, ANG2 and Tie-2 co-expression correlated significantly with the axillary lymph node metastases, compared with ANG2(-)/Tie-2 (-) and ANG2 (+)/Tie-2 (-) or ANG2 (-)/Tie-2 (+) cases.

These findings suggested that ANG2 and Tie-2 might be involved in the progression of invasive ductal carcinomas through autocrine and paracrine signaling and that it may be clinically useful in selecting patients who could benefit from adjuvant treatment by further study.