A comparison of the patterns of laminin expression in fibroadenoma, fibrocystic diseases, pre-invasive and invasive ductal breast carcinoma

Correlation between Laminin and Cathepsin D Expressions in Breast Carcinoma

Aims and Background

Laminin is a major glycoprotein component of basement membrane which is an important barrier to tumor cells which must be breached before metastatic spread can occur. Proteolytic enzymes play an important role in mediating the passage of cancer cells through the basement membrane(BM) and extracellular matrix. We have compared the patterns of laminin and cathepsin D (CD) expressions in a range of benign and malignant breast lesions to better understand the process of tumor progression.

Methods

One hundred and sixty-two cases of breast samples comprising 18 fibroadenomas, 22 cases of fibrocystic disease, 96 cases of invasive ductal carcinoma and 26 carcinomas with intraductal components were evaluated for laminin and cathepsin D expressions by immunohistochemical staining.

Results

The prevalence of CD positivity in both neoplastic and stromal cell components were significantly higher in higher histological grade tumors compared to lower grades (P <0.01). Various severity of BM disruption correlated with histological grade of the carcinomas (P <0.001). There was a negative correlation between the laminin expression and CD presence.

Conclusions

It was confirmed that in a process of cancer cell invasion and metastasis, it could be necessary with the basement membrane disruption by proteinase secreted by cancer cells and especially by stroma cells of cancer.

The extracellular matrix in breast cancer predicts prognosis through composition, splicing, and crosslinking

The extracellular matrix in the healthy breast has an important tumor suppressive role, whereas the abnormal ECM in tumors can promote aggressiveness, and has been linked to breast cancer relapse, survival and resistance to chemotherapy. This review article gives an overview of the elements of the ECM which have been linked to prognosis of breast cancers, including changes in ECM protein composition, splicing, and microstructure.

Evidence for a role of tumor-derived laminin-511 in the metastatic progression of breast cancer

Most studies investigating laminins (LMs) in breast cancer have focused on LM-111 or LM-332. Little is known, however, about the expression and function of alpha5 chain-containing LM-511/521 during metastatic progression. Expression of LM-511/521 subunits was examined in genetically related breast tumor lines and corresponding primary tumors and metastases in a syngeneic mouse model using real-time quantitative polymerase chain reaction, in situ hybridization, and immunohistochemistry. The results from our investigation indicate that LM-511 rather than LM-111, -332, or -521 correlates with metastatic potential in mouse mammary tumors. LM-511 was a potent adhesive substrate for both murine and human breast carcinoma cells and promoted strong haptotactic responses in metastatic lines. Haptotaxis was mediated by alpha3 integrin in both MCF-7 and MDA-MB-231 cells and was strongly inhibited by blocking antibodies against this integrin subunit. However, whereas nonmetastatic MCF-7 cells migrated toward LM-511 primarily via alpha3beta1 integrin, results from antibody perturbation experiments and flow cytometry analysis suggest that this response is mediated by an as yet unidentified alpha3beta integrin heterodimer (other than alpha3beta1) in MDA-MB-231 cells. These results are consistent with earlier reports implicating alpha3 integrins in breast cancer progression and support the role of LM-511 as a functional substrate regulating breast cancer metastasis.

Ductal carcinoma in situ-like structures in metastatic breast carcinoma

In this report, we present two cases of axillary lymph node metastatic breast carcinoma with features mimicking ductal carcinoma in situ (DCIS): one was of the comedo-like type and the other was suggestive of the micropapillary type. In the first case, the primary tumor presented DCIS of the comedo type; however, in the second case, the primary tumor consisted only of the invasive ductal component. Immunohistochemistry against smooth muscle actin, S100-protein, CK5/6, CD10, P63, and 34betaE12 did not identify myoepithelial cells either in DICS of the first primary tumor or in both metastases. These features probably do not represent the true DCISs, but only mimic them. This observation suggests that a proportion of "primary DCIS" may constitute an invasive pseudo-DCIS carcinoma, and immunohistochemical identification of myoepithelial cells may be helpful in such cases.

Functional Imaging of Proteolysis: Stromal and Inflammatory Cells Increase Tumor Proteolysis

The underlying basement membrane is degraded during progression of breast and colon carcinoma. Thus, we imaged degradation of a quenched fluorescent derivative of basement membrane type IV collagen (DQ-collagen IV) by living human breast and colon tumor spheroids. Proteolysis of DQ-collagen IV by HCT 116 and HKh-2 human colon tumor spheroids was both intracellular and pericellular. In contrast, proteolysis of DQ-collagen IV by BT20 human breast tumor spheroids was pericellular. As stromal elements can contribute to proteolytic activities associated with tumors, we also examined degradation of DQ-collagen IV by human monocytes/macrophages and colon and breast fibroblasts. Fibroblasts themselves exhibited a modest amount of pericellular degradation. Degradation was increased 4–17-fold in cocultures of fibroblasts and tumor cells as compared to either cell type alone. Inhibitors of matrix metalloproteinases, plasmin, and the cysteine protease, cathepsin B, all reduced degradation in the cocultures. Monocytes did not degrade DQ-collagen IV; however, macrophages degraded DQ-collagen IV intracellularly. In coculture of tumor cells, fibroblasts, and macrophages, degradation of DQ-collagen IV was further increased. Imaging of living tumor and stromal cells has, thus, allowed us to establish that tumor proteolysis occurs pericellularly and intracellularly and that tumor, stromal, and inflammatory cells all contribute to degradative processes.

Loss of types XV and XIX collagen precedes basement membrane invasion in ductal carcinoma of the female breast

Ductal and lobular carcinomas comprise most malignancies of the female breast and the morbidity and mortality associated with breast cancer. During the progression from in situ to invasive stages, tumour cells penetrate the epithelial and vascular basement membranes (BM) to realize full metastatic potential. While the definition of these structures has primarily resulted from analysis of laminin and type IV collagen, characterization of newly discovered BM/BM zone (BMZ) proteins will further elucidate the interactions between tumour cells and the host stroma. We have studied the expression of two non-fibrillar BMZ collagens, the type XV proteoglycan and collagen XIX, in breast cancer where a linear, well-formed BM becomes fragmented and even lost in the progression of epithelial malignancy. In the normal breast, types XV and XIX were found in all BMZ: epithelial, muscle, neural, endothelial, and fat. In in situ lesions, these two collagens, and particularly type XV, were often absent from the BM/BMZ displaying a continuous or just focally disrupted type IV/laminin staining pattern. In contrast, infiltrating ductal carcinomas showed only rare traces of laminin and collagen IV reactivity adjacent to the glands and tumour nests, and similarly there was little if any evidence of types XV and XIX collagen. All four molecules were, however, detected in the interstitium associated with some of the invasive carcinomas. The data suggest that types XV and XIX collagen are lost early in the development of invasive tumours, prior to penetration and eventual dissolution of the epithelial BM. Disappearance of these proteins from the BM/BMZ may signal remodelling of the extracellular matrix to promote tumour cell infiltration.