[Study of the correlation between HER-2 gene and lymphangiogenesis and their prognostic significance in human breast cancer].

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.