Objective: To demonstrate the molecular mechanism of poor prognosis in HER-2 overexpressing breast carcinoma, to study the correlation between angiogenesis/lymphangiogenesis and HER-2, and the effect of them in the progression and prognosis, so as to provide novel molecular markers for lymph node metastasis and prognosis in breast carcinoma.
Methods: (1) By using TaqMan real-time quantitative reverse transcription polymerase chain reaction (real-time qRT-PCR) technique and immunohistochemistry (IHC), the mRNA and protein expression of VEGF-C were detected in SKBR-3 and MDA-MB-231 cell lines before and after the interference with Herceptin. (2) Real-time qRT-PCR was performed to detect the mRNA expression of VEGF-C and -D genes in 67 cases of primary breast infiltrating ductal carcinoma. (3) 160 formalin-fixed paraffin-embedded infiltrating ductal carcinomas were selected. The protein expression of HER-2, VEGF-C, lymphatic vessel density (LVD) and lymphatic vessel invasion (LVI) were detected by IHC.
Result: (1) After interference with Herceptin, the VEGF-C mRNA and protein expression of sKBR-3 the cells decreased significantly. In primary breast cancer, the protein expression of HER-2 was positively correlated with VEGF-C protein expression (r = 0.215, P < 0.05). There was a significantly positive correlation between VEGF-C protein expression and LVD (r = 0.248, P < 0.01). (2) VEGF-C mRNA expression in the patients with lymph node metastasis was higher than that in the patients without lymph node metastasis (1.6 +/- 0.5 vs 1.1 +/- 0.5) (t = 2.196, P < 0.05). Logistic regression model showed HER-2, LVD and LVI were important factors influencing lymph node metastasis (all P < 0.05). (3) Kaplan-Meier analysis indicated that HER-2 protein overexpression, VEGF-C protein overexpression, and high LVD and LVI were associated with patient's worse disease-free survival (P(uni) < 0.05). Cox regression analysis indicated that HER-2 and LVI were the independent prognostic factors of breast cancer (both P(mult) < 0.05).
Conclusion: Through up-regulating VEGF-C expression, HER-2 overexpression induces lymphangiogenesis, promotes metastasis, and results in the poor prognosis of breast cancer. VEGF-C expression, LVD and LVI are novel prognostic indicators of breast cancer.