| Purpose To investigate the change of PTEN gene and its protein expression in breast cancer, study its correlations with integrin 1, MMP-2, MMP-9, TIMP-1 and cyclinDl, so as to understand its roles in tumor invasion and metastasis and to evaluate its clinicopathological significance. Methods Immunohistochemical staining, S-P method, was used to detect the positivity of PTEN in 23 cases of normal breast tissues, 28 cases of proliferative breast disease including 8 cases of atypical hyperplasia (ADH), 8 cases of ductal carcinoma in situ (DCIS) and 98 cases of breast cancer. Meanwhile, cyclinDl, integrin l, MMP-2, MMP-9, TIMP-1 and microvessel density(MVD) marked with Factor VIII-related antigen were also investigated in 98 cases of breast cancer. PCR-PAUGE was used to detect loss of heterozygosity (LOH) and microsatellite instability (MSI) near PTEN loci in 98 cases of breast cancer. Results 1. PTEN was weakly expressed in normal breast tissues. Atypical hyperplasia and DCIS expressed higher levels of PTEN than normal tissues(P<0.05), but had no remarkable distinction with invasive breast cancer. The expression of PTEN was negatively correlated to histological grading, axillary lymph node metastasis, clinical staging and MVD. 2. The frequency of loss of flanking marker D10S215 around PTEN was 32.7%(32/98). In the cases with PTEN-LOH, 5 of 32 were PTEN-negative. PTEN-LOH was positive correlated to clinical staging, axillary lymph node metastasis. But microsatellite analysis showed that there was no microsatellite instability about D10S215 of PTEN gene existed in all these samples. 3. A negative relationship existed between the expression of PTEN and cyclinDl, integrinpl, MMP-2, MMP-9. And a positive relationship existed between the expression of PTEN and TIMP-1. 4. With weak and no expression of PTEN, there was a positive correlation between the expression of cyclinDl andhistological grading, axillary lymph node metastasis, a positive correlation between the expression of MMP-2, MMP-9 and axillary lymph node metastasis, but no correlations between the expression of integrinβ1, TIMP-1 and axillary lymph node metastasis. 5. With strong expression of PTEN, there was a positive correlation between the expression of integrinβ1, MMP-2, MMP-9 and axillary lymph node metastasis, a negative correlation between TIMP-1 expression and axillary lymph node metastasis, but no correlations between cyclinDl expression and axillary lymph node metastasis. Conclusion 1. The change of PTEN expression is an early event in malignant transformation of breast epithelium. Significant correlation between the expression of PTEN and cyclinDl also suggests that the down regulation of PTEN expression in breast cancer correlating with histological grading, axillary lymph node metastasis, clinical stage and MVD may be considered as a potential indicator to judge the differentiation and metastasis of breast cancer. 2. LOH of PTEN gene may be a relatively late event in breast cancer development, which may play important roles on invasion and metastasis in breast cancer. And no microsatellite instability about D10S215 of PTEN gene suggests that it might not be the main change in breast cancer. 3. Immunohistochemistry is useful for the detection of LOH of PTEN gene on D10S215 in breast cancer. 4. The effect of cyclinDl on axillary lymph node metastasis of breast cancer may partly be under the regulation of PTEN. 5. There is a PTEN-independent regulation pathway for MMP-2 and MMP-9 on metastasis and invasion in breast cancer. However, the effect of TIMP-1 and integrinβl may be under the regulation of PTEN. |
