Expression of the CD44 variant isoforms 6 and 4/5 in breast cancer. Correlation with established prognostic parameters

Epithelial-to-Mesenchymal Transition and Phenotypic Marker Evaluation in Human, Canine, and Feline Mammary Gland Tumors

Epithelial-to-mesenchymal transition (EMT) is a process by which epithelial cells acquire mesenchymal properties. EMT has been closely associated with cancer cell aggressiveness. The aim of this study was to evaluate the mRNA and protein expression of EMT-associated markers in mammary tumors of humans (HBC), dogs (CMT), and cats (FMT). Real-time qPCR for SNAIL, TWIST, and ZEB, and immunohistochemistry for E-cadherin, vimentin, CD44, estrogen receptor (ER), progesterone receptor (PR), ERBB2, Ki-67, cytokeratin (CK) 8/18, CK5/6, and CK14 were performed. Overall, SNAIL, TWIST, and ZEB mRNA was lower in tumors than in healthy tissues. Vimentin was higher in triple-negative HBC (TNBC) and FMTs than in ER+ HBC and CMTs (p < 0.001). Membranous E-cadherin was higher in ER+ than in TNBCs (p < 0.001), whereas cytoplasmic E-cadherin was higher in TNBCs when compared with ER+ HBC (p < 0.001). A negative correlation between membranous and cytoplasmic E-cadherin was found in all three species. Ki-67 was higher in FMTs than in CMTs (p < 0.001), whereas CD44 was higher in CMTs than in FMTs (p < 0.001). These results confirmed a potential role of some markers as indicators of EMT, and suggested similarities between ER+ HBC and CMTs, and between TNBC and FMTs.

Hyaluronan-CD44 interactions as potential targets for cancer therapy

It is becoming increasingly clear that signals generated in tumor microenvironments are crucial to tumor cell behavior, such as survival, progression and metastasis. The establishment of these malignant behaviors requires that tumor cells acquire novel adhesion and migration properties to detach from their original sites and to localize to distant organs. CD44, an adhesion/homing molecule, is a major receptor for the glycosaminoglycan hyaluronan, which is one of the major components of the tumor extracellular matrix. CD44, a multistructural and multifunctional molecule, detects changes in extracellular matrix components, and thus is well positioned to provide appropriate responses to changes in the microenvironment, i.e. engagement in cell-cell and cell-extracellular matrix interactions, cell trafficking, lymph node homing and the presentation of growth factors/cytokines/chemokines to co-ordinate signaling events that enable the cell responses that change in the tissue environment. The potential involvement of CD44 variants (CD44v), especially CD44v4-v7 and CD44v6-v9, in tumor progression has been confirmed for many tumor types in numerous clinical studies. The downregulation of the standard CD44 isoform (CD44s) in colon cancer is postulated to result in increased tumorigenicity. CD44v-specific functions could be caused by their higher binding affinity than CD44s for hyaluronan. Alternatively, CD44v-specific functions could be caused by differences in associating molecules, which may bind selectively to the CD44v exon. This minireview summarizes how the interaction between hyaluronan and CD44v can serve as a potential target for cancer therapy, in particular how silencing CD44v can target multiple metastatic tumors.

CD44s is useful in the differentiation of benign and malignant papillary lesions of the breast

BACKGROUND/AIMS

CD44s, the standard form of CD44, has been shown to be downregulated during malignant transformation of breast cancers. It has also been reported recently to be a useful marker in differentiating between benign and malignant papillary lesions of the breast, with high expression in the former. CD44s expression in benign and malignant papillary lesions was evaluated.

METHODS

CD44s expression was assessed by immunohistochemistry in 101 benign papillomas and 59 papillary carcinomas (seven invasive papillary carcinomas, 41 papillary ductal carcinomas in situ, and 11 ductal carcinomas involving papillomas).

RESULTS

Patients' age and tumour size were significantly different between the papilloma and papillary carcinoma groups (p < 0.0001). CD44s showed positive staining in 45 papillomas (45%) and five papillary carcinomas (8%), and the difference was significant (p < 0.0001). The myoepithelial cells, when present, were also positive for CD44s in both groups, with no observable differences. Using CD44s positive staining to differentiate between benign and malignant papillary lesions gives a sensitivity, specificity, and accuracy of 45%, 92%, and 62%, respectively.

CONCLUSIONS

CD44s may be useful as an adjunct in the evaluation of morphologically problematic cases of papillary lesion of the breast.

Adhesion molecules: opportunities for modulation and a paradigm for novel therapeutic approaches in cancer

In the past decade, there have been major advances in the elucidation of processes underlying tumour invasion and metastasis, in which adhesion molecules play a critical role. These advances have revolutionised our ability to devise novel approaches for cancer treatment. This review gives an insight into the adhesion pathways, and highlights the current status of adhesion molecules as potential therapeutic targets.

Clinicopathological associations of CD44 mRNA and protein expression in primary breast carcinomas

AIMS

The purpose of this study was to examine the occurrence of CD44 isoforms in breast carcinomas and their role in predicting clinical outcome.

METHODS AND RESULTS

Shock-frozen tumour tissues from 110 patients with breast carcinoma were examined by immunohistochemistry using antibodies directed against CD44s, v5, v6, v7 and v3-10. In addition, 80 of these tumours were available for quantitative real-time reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of CD44s and CD44v6. Immunohistochemically, the positive tumours showed cytoplasmic and/or membranous staining with all antibodies. Staining results did not correlate with histological subtype, lymph node status, status of steroid receptors, tumour size or age. Neither was any correlation found for overall and disease-free survival. Quantitative real-time RT-PCR of CD44s and CD44v6, however, revealed that expression of CD44v6 mRNA was significantly associated with lower pathological grade (Pearson chi(2) test P = 0.009; linear-by-linear association P = 0.003). Linear-by-linear association between CD44s mRNA expression and lower pathological grade was also seen (P = 0.02). Survival analysis with the Kaplan-Meier method demonstrated that increased CD44s mRNA expression was significantly associated with both disease-free survival and overall survival (P = 0.0185 and P = 0.0344, respectively). A similar trend for CD44v6 mRNA expression was seen in these cases, but the difference was not significant.

CONCLUSIONS

Quantitative real-time RT-PCR revealed clinical correlations of CD44s and CD44v6 mRNA expression in breast carcinomas while immunohistochemistry for the protein expression of CD44s and other CD44 variants did not. This contradictory result merits further studies concerning the clinical impact of CD44 molecules in breast carcinomas.

[Expression of the adhesion molecule CD44v6 in infiltrating ductal carcinomas of the breast is associated with hormone dependence. Our experience with 168 cases]

In order to investigate the possible hormone-dependence of CD44v6 in human breast cancer, we assayed the concentrations of this isoform in the membrane fraction of 168 invasive ductal carcinomas (IDC) and in 26 normal breast tissue samples, 18 fibradenomas (FAD), 3 fibrocystic disease specimens (FD), 7 mucinous carcinomas and 4 medullary carcinomas using the ELISA method. The results were compared with those of the estrogen (ER) and progesterone (PR) receptors, pS2, tissue type plasminogen activator (t-PA), cathepsin D, epidermal growth factor receptor (EGFR) and c-erbB2/neu oncoprotein concentrations. Menopausal status, size of the tumor in the cases of cancers, axillary lymph node involvement, histologic grade, ploidy, cellular synthesis phase, multifocality and multicentricity were also considered as variables. The cut-off value for CD44v6-positivity was set at 5 ng/mg prt. membrane protein content. 64/138 (38.1%) infiltrating ductal carcinomas scored positive. This was significantly higher than for the normal breast tissue (0/26; p: 0.0001), similar to that seen in the FAD (3/18), fibrocystic disease (0/3), infiltrating mucinous carcinomas (4/7) and lobular (3/15) and significantly lower than for the infiltrating medullary carcinomas (4/4; p: 0.027). There were no significant differences with the other groups of tissues studied. Furthermore, CD44v6-positive IDC showed significantly higher concentrations of ER, PR and cathepsin D and lower (p: 0.051) concentrations of EGFR when compared to their CD44v6-negative counterparts. The significant coexpression of ER, PR and cathepsin D seems to indicate a possible role for hormonal regulation of CD44v6 expression while the role of pS2 and t-PA, estrogen related proteins, was very reduced.

CD44s as a surrogate marker for distinguishing intraductal papilloma from papillary carcinoma of the breast

BACKGROUND

It has been shown that CD44 variants are differentially expressed in normal and neoplastic breast tissues. The diagnostic value of these markers in distinguishing benign from malignant breast lesions has not been well examined.

AIMS

To evaluate the diagnostic value of CD44s in distinguishing between intraductal papillomas and papillary carcinomas of the breast, which may be difficult morphologically.

METHODS

Expression of CD44s detected by immunohistochemistry was studied in a series of intraductal papillomas (11) and papillary carcinomas (10). The normal breast tissues surrounding the lesions of these cases served as a control. The number of CD44s positive epithelial cells was scored and categorised as < 10%, 10-70%, or > 70%.

RESULTS

Normal breast epithelial cells and all intraductal papillomas (11 of 11) expressed CD44s in a high proportion of cells (> 70%). In contrast, the majority of papillary carcinoma cases (eight of 10) expressed this marker in < 10% of the cells. In the remaining two papillary carcinoma cases, positivity was seen in more than 10% but still less than 70% of the cells.

CONCLUSIONS

CD44s detection by immunohistochemistry is useful in distinguishing intraductal papillomas from papillary carcinomas of the breast.

Cytosol concentrations of CD44 isoforms in breast cancer tissue

The role of the adhesion molecule CD44 in the natural history of breast cancer is controversial. We investigated the CD44 isoform CD44v5 and CD44v6 concentrations in the cytosol of 90 breast cancer specimens, 9 fibroadenomas and 22 normal breast tissue specimens by means of ELISA. CD44v5 and CD44v6 cytosol concentrations were statistically significantly higher in breast cancer compared with fibroadenoma and normal breast tissue (Mann-Whitney U-test, p = 0.009 and p < 0.001, respectively). When CD44 isoforms were correlated with lymph node involvement, histological grading, histological type, tumor stage and age at diagnosis, we found no statistically significant correlation with any of the investigated clinico-pathological parameters. In univariate and multivariate analyses, CD44v5 and CD44v6 were of no prognostic relevance regarding disease-free survival in breast cancer patients (log-rank test, p = 0.16 and p = 0.08, respectively). Our results indicate that CD44 isoforms are increased in samples from tumors relative to normal tissue. Our data show that CD44v5 and CD44v6 isoform expression, although up-regulated by malignant transformation, is not required to acquire a metastatic phenotype in breast cancer. Furthermore, our data support the assumption that cytosolic CD44 isoforms are of no prognostic relevance for disease-free survival of breast cancer patients.

CD44v6 is not a prognostic factor in primary breast cancer

BACKGROUND

CD44 is an adhesion molecule and represents a highly variable family of isoforms. The isoform CD44v6 has been associated with metastasis formation and poor prognosis in animal models and human colon cancer. Results of studies in primary breast cancer are relatively small and contradictory.

PATIENTS AND METHODS

The immunohistochemical expression of CD44v6 was studied in a series of 338 patients with primary breast tumours, uniformly staged and treated in a single center with a long median follow-up of 128 months. The prognostic significance of CD44v6 as well as the correlation with several clinicopathological features were analysed.

RESULTS

Two hundred nineteen of 338 (64.8%) of the breast cancer were CD44v6-positive (> 5% of tumour cells with positive staining). CD44v6 expression had no value for prognosticating disease-free or overall survival at this or any other cut-off point.

CONCLUSION

CD44v6 expression is not a prognostic factor in primary breast cancer.

The role of angiogenesis, laminin and CD44 expression in metastatic behavior of early-stage low-grade invasive breast carcinomas

To investigate the role of tumor angiogenesis, laminin and CD44 expression in metastatic potential of breast cancers, 35 early-stage (T1) and/or low-grade (grade 1) invasive breast carcinomas including 18 metastasizing and 17 non-metastasizing cases were analyzed in the present study. Angiogenesis was assessed by a stereologic method after immunohistochemical staining of vascular endothelium for factor VIII. The quantification of the tumor vascularization was based on the vascular surface density (VSD) and the microvessel number (NVES). The expressions of laminin and CD44 were evaluated by scoring the intensity and distribution of the immunostaining. The assessment of NVES and VSD resulted in a statistically significant difference between the two groups (P < 0.05, independent-samples t-test). In the breast cancers with metastatic spread, NVES was found to be 16.0+/-2.9 mm(-2) whereas it was 8.1+/-0.7 mm(-2) in the metastasizing group. VSD was found to be 59.0+/-12.6 mm(-1) in the metastasizing group and was significantly lower in the non-metastasizing group (33.8+/-2.6 mm[-1]). Immunohistochemistry exhibited strongly positive staining for CD44 in 22% of the breast cancers with metastasis, while 65% of the non-metastasizing cases were found to be negative. The statistical analysis also resulted in a significant difference (P = 0.034, chi2 test). However, the immunohistochemical staining for laminin did not yield any significant difference (P = 0.347, chi2 test). Approximately half of the cases being either metastasizing or non-metastasizing stained weakly positive for laminin. We concluded that angiogenesis and CD44 expression in breast cancers correlated significantly with lymph node or distant metastasis. However, the immunodetection of laminin expression in our study did not help to evaluate its role in the metastatic potential of breast cancers. We concluded that vascular parameters, such as an increase in microvessel number, and CD44 expression might be useful prognostic indicators of metastasis in breast cancer.

CD44 in inflammation and metastasis

CD44 is a major cell surface receptor for the glycosaminoglycan, hyaluronan (HA). CD44 binds HA specifically, although certain chondroitin-sulfate containing proteoglycans may also be recognized. CD44 binding of HA is regulated by the cells in which it is expressed. Thus, CD44 expression alone does not correlate with HA binding activity. CD44 is subject to a wide array of post-translational carbohydrate modifications, including N-linked, O-linked and glycosaminoglycan side chain additions. These modifications, which differ in different cell types and cell activation states, can have profound effects on HA binding function and are the main mechanism of regulating CD44 function that has been described to date. Some glycosaminoglycan modifications also affect ligand binding specificity, allowing CD44 to interact with proteins of the extracellular matrix, such as fibronectin and collagen, and to sequester heparin binding growth factors. It is not yet established whether the HA binding function of CD44 is responsible for its proposed involvement in inflammation. It has been shown, however, that CD44/HA interactions can mediate leukocyte rolling on endothelial and tissue substrates and that CD44-mediated recognition of HA can contribute to leukocyte activation. Changes in CD44 expression (mainly up-regulation, occasionally down-regulation, and frequently alteration in the pattern of isoforms expressed) are associated with a wide variety of cancers and the degree to which they spread; however, in other cancers, the CD44 pattern remains unchanged. Increased expression of CD44 is associated with increased binding to HA and increased metastatic potential in some experimental tumor systems; however, in other systems increased HA binding and metastatic potential are not correlated. CD44 may contribute to malignancy through changes in the regulation of HA recognition, the recognition of new ligands and/or other new biological functions of CD44 that remain to be discovered.