Biochemical control of breast aromatase

Aromatase activity is increased in breast tumors and it is possible that this results from stimulation by cytokines and/or prostaglandin E₂ (PGE₂) which regulate the activity of this enzyme. As different promoters can be used to control aromatase gene expression in normal and malignant breast tissues, which are regulated by different factors, we are currently investigating the relative roles of cytokines and PGE₂ in controlling breast tumor aromatase activity. No significant effect of PGE₂ on aromatase activity in MCF-7 breast cancer cells has so far been detected. However, preliminary evidence was obtained, from co-cultures of MCF-7 cells and breast tumor-derived fibroblasts, that MCF-7 cells secrete a factor, possibly a cytokine, which can act in a paracrine manner to enhance aromatase activity in stromal cells. Understanding the complex regulation of aromatase activity in breast tumors could lead to novel therapies for specifically inhibiting tumor estrogen synthesis.     

Fibroblast-directed expression and localization of 92-kDa type IV collagenase along the tumor-stroma interface in an in vitro three-dimensional model of human squamous cell carcinoma

The malignant dissemination of tumors has been shown to require expression of one or more members of the matrix metalloprotease (MMP) enzyme family, whose function is to catalyze degradation of extracellular matrix proteins. In human squamous cell carcinoma (SCC) of the skin, expression of the MMP 92-kDa type IV collagenase (MMP-9), was previously shown to localize to malignant keratinocytes residing along the tumor/stromal interface. The purpose of the study presented here was to determine whether this localized expression pattern is due to interactions between SCC cells and adjacent stromal fibroblasts. To examine this question, SCC cells were grown as organotypic skin cultures, an in vitro three-dimensional model of reconstructed human epidermis in which keratinocytes are grown on a type 1 collagen gel embedded with human dermal fibroblasts. In this study, MMP-9 expression was compared in organotypic cultures (constructed with SCC cells or the non-tumorigenic keratinocyte cell line HaCaT), in which human dermal fibroblasts were either included or excluded from the underlying stromal layer. In the absence of fibroblasts, expression of MMP-9 was slightly higher in SCC than HaCaT cultures. In cultures constructed with fibroblasts, however, induction of MMP-9 mRNA was observed in SCC but not HaCaT cultures. This induction of MMP-9 mRNA was accompanied by high levels of MMP-9 protein expression along the SCC/stromal interface. These data provide strong evidence that interactions between malignant keratinocytes and adjacent stromal fibroblasts are critical in directing expression of MMP-9 to the tumor-stroma interface in human SCC tumors. Mol. Carcinog. 19:258–266, 1997. © 1997 Wiley-Liss, Inc.     

Tumor-Derived Matrix Metalloproteinase-13 (MMP-13) Expression in Benign and Malignant Breast Lesions

Introduction: Breast carcinoma is the most common malignancy and the leading cause of cancer death in women. Matrix metalloproteinase-13 (MMP-13) is a hypothetical prognostic marker in invasive breast cancer. This study aimed to determine MMP-13 expression in benign and malignant breast lesions and to evaluate the correlation between MMP-13 expression and tumor characteristics in invasive ductal carcinoma (IDC). Materials and Method: We evaluated cytoplasmic expression of MMP-13 based on staining index using immunohistochemistry (IHC) in epithelial cells, stromal fibroblasts of IDC (n=90) and benign epithelial breast (n=90) lesions. Correlation between IHC and tumor size, lymph node status, distance metastasis, estrogen receptor (ER), progesterone receptor (PR) and Her-2/neu was assessed. Results: MMP-13 expression was 45% and 38.8% in malignant epithelial cells and peritumoral fibroblasts, respectively. Only low level of MMP-13 expression was seen in benign breast lesions (8.8% in epithelial component and 2.2% in stromal fibroblasts), while high level of MMP-13 expression was noted in malignant tumors, mainly grade II or III. Cytoplasmic MMP-13 expressions in epithelial tumor cells was correlated significantly with peritumoral fibroblasts. MMP-13 expression was directly correlated with distant metastasis and tumor stage in epithelial tumoral cells and was inversely correlated with progesterone expression in both tumoral and stromal cells. Conclusion: This study showed that MMP-13 was a moderator for tumor invasion and metastasis and could be an independent predictor of poor prognosis in breast cancer. The role of MMP-13 in predicting the risk of malignant transformation in benign lesions should be further investigated.     

Co-culture of human breast adenocarcinoma MCF-7 cells and human dermal fibroblasts enhances the production of matrix metalloproteinases 1, 2 and 3 in fibroblasts.

No measurable amounts of matrix metalloproteinases (MMPs) were produced by human breast adenocarcinoma cell lines MCF-7 and BT-20 in culture. When MCF-7 cells were co-cultured with human dermal fibroblasts enhanced production of precursors of MMP-1 (interstitial collagenase), MMP-2 (gelatinase A), MMP-3 (stromelysin 1) and tissue inhibitor of metalloproteinase type 1 (TIMP-1) was observed. Immunohistochemical studies indicated that these pro-MMPs originated primarily from the fibroblasts, suggesting that MCF-7 cells have a stimulatory effect on stromal cells to produce at least three pro-MMPs and TIMP-1. BT-20 cells also enhanced the production of pro-MMP-2 and TIMP-1 in the dermal fibroblasts, but not of pro-MMP-1 and pro-MMP-3. Normal mammary epithelial cells promoted only TIMP-1 production. To investigate further the stimulatory factors from MCF-7 cells, the conditioned medium and the cell membrane were prepared and examined. The cell membrane fraction enhanced the production of pro-MMP-1 and -3 and TIMP-1, but not of pro-MMP-2. The conditioned medium, on the other hand, augmented the production of all four proteins in the fibroblasts. These observations suggest that breast adenocarcinoma MCF-7 cells in culture produce both soluble and membrane-bound factor(s) which stimulate the production of pro-MMPs and TIMP-1 in neighbouring stromal cells, but the factor(s) released into the medium and that associated with cell membranes are probably different. Such communication between the normal and malignant cell types may, in part, assist the cancer cells to invade and metastasise.     

Differential regulation of breast tumor cell proliferation by stromal fibroblasts of various breast tissue sources

A stromal fibroblast-mediated paracrine regulation of epithelial tumor cell proliferation and differentiation plays an important role in the development and progression of breast tumors. We have studied the paracrine growth regulation of various phenotypically different breast cancer cell lines using conditioned serum-free media (C-SFM) from primary breast fibroblasts. Fibroblast cultures were established from malignant primary tumors and adjacent normal breast tissue, benign fibroadenomas, cosmetic reduction mammoplasties and breast skin tissues. All fibroblast-conditioned media were shown to stimulate the proliferation of breast cancer cell lines. However, the C-SFM-induced MCF-7 proliferative response was shown to be significantly higher than the proliferative response observed with any of the other cell lines tested. More importantly, the MCF-7 proliferative response obtained with malignant tumor tissue fibroblast C-SFM was shown to be significantly higher than the response to C-SFM from paired (and unpaired) normal adjacent breast tissue fibroblasts. The MCF-7 proliferative response to fibroblast C-SFM from normal tissue (adjacent to the tumor) was further shown to be comparable to the MCF-7 response using benign or reduction mammoplastic tissue fibroblast C-SFM. In addition, we show that IGFs are only partly responsible for the observed proliferative effect of the C-SFMs, while EGF, TGFα and basic-FGF are shown not to be involved. We conclude that stromal fibroblasts can differentially regulate breast cancer cell proliferation. Both the fibroblast's tissue source as well as the target tumor cell's phenotype will determine the extent of the proliferative response. © 1996 Wiley-Liss, Inc.     

p16(INK4A) represses the paracrine tumor-promoting effects of breast stromal fibroblasts

Cancer-associated fibroblasts (CAFs), the most abundant and probably the most active cellular component of breast cancer-associated stroma, promote carcinogenesis through paracrine effects; however, the molecular basis remains elusive. We have shown here that p16(INK4A) expression is reduced in 83% CAFs as compared with their normal adjacent counterparts cancer-free tissues isolated from the same patients. This decrease is mainly due to AUF1-dependent higher turnover of the CDKN2A mRNA in CAFs. Importantly, p16(INK4A) downregulation using specific siRNA activated breast fibroblasts and increased the expression/secretion levels of stromal cell-derived factor 1 (SDF-1) and matrix metalloproteinase (MMP)-2. Consequently, media conditioned with these cells stimulated the proliferation of epithelial cells. Furthermore, the migration/invasion of breast cancer cells was also enhanced in an SDF-1-dependent manner. This effect was mediated through inducing an epithelial-mesenchymal transition state. By contrast, increase in p16(INK4A) level through ectopic expression or AUF1 downregulation, reduced the secreted levels of SDF-1 and MMP-2 and suppressed the pro-carcinogenic effects of CAFs. In addition, p16(INK4A)-defective fibroblasts accelerated breast tumor xenograft formation and growth rate in mice. Importantly, tumors formed in the presence of p16(INK4A)-defective fibroblasts exhibited higher levels of active Akt, Cox-2, MMP-2 and MMP-9, showing their greater aggressiveness as compared with xenografts formed in the presence of p16(INK4A)-proficient fibroblasts. These results provide the first indication that p16(INK4A) downregulation in breast stromal fibroblasts is an important step toward their activation.     

Matrix metalloproteinase-2 status in stromal fibroblasts, not in tumor cells, is a significant prognostic factor in non-small-cell lung cancer.

PURPOSE: The purpose is to assess clinical significance of matrix metalloproteinase (MMP)-2 and MMP-9 status, especially MMP-2 status, in stromal cells in non-small-cell lung cancer (NSCLC) because experimental studies have revealed that stromal MMP-2 plays important roles in progression of malignant tumors, but most clinical studies focused on tumoral MMP-2 expression, not stromal MMP-2 expression. EXPERIMENTAL DESIGN: We conducted a retrospective study on MMP-2 and MMP-9 expression as evaluated immunohistochemically in a total of 218 consecutive patients with completely resected pathological stage I-IIIA, NSCLC. RESULTS: Strong MMP-2 expression in tumor cells and stromal fibroblasts were documented in 54 (24.8%) and 132 (60.6%) patients, respectively. Strong MMP-2 expression in stromal fibroblasts was more frequently seen in squamous cell carcinoma (72.7%) than in adenocarcinoma (54.9%; P = 0.016). Tumors showing strong MMP-2 expression in stromal fibroblasts showed a significantly higher intratumoral microvessel density (IMVD) than weak stromal MMP-2 tumors (mean intratumoral microvessel density, 50.9 versus 32.4, P = 0.003). In addition, postoperative prognosis of strong stromal MMP-2 patients was significantly poorer than that of weak stromal MMP-2 patients (5-year survival rate, 77.5 versus 60.2%, P = 0.032), and the prognostic significance was enhanced in squamous cell carcinoma patients but disappeared in adenocarcinoma patients. Multivariate analyses confirmed that strong stromal MMP-2 expression was a significant factor to predict a poor prognosis in squamous cell carcinoma patients, not in adenocarcinoma patients. In contrast, MMP-2 or MMP-9 status in tumor cells was not a significant prognostic factor. CONCLUSIONS: MMP-2 status in stromal fibroblasts, not in tumor cells, was a significant prognostic factor associated with angiogenesis in NSCLC.     

紫花牡荆素抑制乳腺癌MCF-7细胞增殖与侵袭能力的研究

目的观察紫花牡荆素对乳腺癌MCF-7细胞株增殖与侵袭能力的影响并探讨其分子机制。方法应用四甲基偶氮唑蓝（MTT）比色法与侵袭实验检测紫花牡荆素对MCF-7细胞增殖与侵袭能力的影响,应用反转录PCR、Western blot法、Tunel法检测紫花牡荆素对基因表达、蛋白表达、细胞凋亡的影响。结果不同浓度紫花牡荆素均抑制MCF-7细胞增殖水平,同未加药对照组比较差异均有统计学意义（P〈0．05）,5、10、20μmol／L紫花牡荆素作用后,MCF-7细胞迁移数与未处理组相比分别降低20.3％、44．4％和50．3％（P〈0．05）。以10μmol／L紫花牡荆素处理后,凋亡细胞数增多,可以上调Bax与Caspase-3蛋白的表达水平,下调基质金属蛋白酶（MMP）-2与MMP-9的mRNA和蛋白表达水平。结论紫花牡荆素对于乳腺癌细胞恶性增殖与侵袭能力具有显著抑制作用。     

Tumor-derived Cyr61(CCN1) promotes stromal matrix metalloproteinase-1 production and protease-activated receptor 1-dependent migration of breast cancer cells

Matrix metalloproteinases (MMPs) play a central role in remodeling the tumor-stromal microenvironment. We recently determined that stromal-derived MMP-1 also acts as a signaling molecule by cleaving protease-activated receptor 1 (PAR1) to cause breast cancer cell migration and invasion. Here, we show that ectopic PAR1 expression induces expression of the angiogenic factor Cyr61(CCN1) in breast cancer cells. The tumor-derived Cyr61 acts as an invasogenic signaling molecule that induces MMP-1 expression in adjacent stromal fibroblasts. Gene silencing of Cyr61 in breast cancer cells suppresses MMP-1 induction in stromal fibroblasts resulting in a major loss in migration of the cancer cells toward the fibroblasts. Cyr61-dependent loss of migration was complemented by exogenous MMP-1 and required the presence of the functional PAR1 receptor on the breast cancer cells. These results suggest that interrupting tumor-stromal cell communication by targeting Cyr61 may provide an alternative therapeutic approach for the treatment of invasive breast cancer.     

Expression of thrombospondin-1 in human pancreatic adenocarcinomas: Role in matrix metalloproteinase-9 production

Human pancreatic adenocarcinoma, an aggressive malignant disease, shows a strong desmoplastic reaction characterized by a remarkable proliferation of interstitial connective tissues. Thrombospondin-1 (TSP-1), a 450 kDa platelet and matrix glycoprotein, has been implicated in tumor invasion, angiogenesis and metastasis. TSP-1 and MMP-9 expression in pancreatic adenocarcinoma and control pancreas tissues was measured by immunohistochemistry. TSP-1 expression in pancreatic carcinoma cell lines, fibroblasts, and endothelial cells was measured by a competitive TSP-1 enzyme linked immunosorbent assay (ELISA). The effect of TSP-1 on MMP-9 production in pancreatic carcinoma cell lines was measured by zymography and Western blot analysis. Eighty five per cent (23/27) of cases of pancreatic adenocarcinoma showed increased TSP-1 staining in the desmoplastic stroma adjacent to tumor cells. No specific positive staining for TSP-1 was observed in the normal pancreatic tissues and the inflammatory areas. TSP-1 localized in tumor stroma surrounding the tumor cells expressing MMP-9. Using TSP-1 competitive ELISA, the secretion of TSP-1 by different pancreatic cancer cell lines into culture medium varied from 11.45 plus minus 14.08 to 275.82 plus minus 45.56 ng/10 6 cells/24 hours. The amounts of TSP-1 detected in both culture media and cell extracts from fibroblasts or endothelial cells were at least 2-3 fold higher than those from pancreatic cancer cells. TSP-1 augmented the production of matrix metalloproteinase-9, a matrix degrading enzyme, in pancreatic cancer cells in vitro. Stromally-derived TSP-1 up-regulates the production of MMP-9 by pancreatic adenocarcinoma. These data are consistent with the conclusion that TSP-1-rich stroma is involved in regulating matrix remodeling in tumor invasion.     

Growth factor messenger RNA expression by human breast fibroblasts from benign and malignant lesions

Breast tumors are a complex mix of epithelial, stromal, and vascular elements. We examined primary cultures of breast fibroblasts derived from benign and malignant lesions for expression of various growth factors. All fibroblast cultures, regardless of whether they were derived from benign or malignant lesions, expressed platelet-derived growth factor A chain, basic fibroblast growth factor, fibroblast growth factor 5, and transforming growth factor beta 1 mRNA. None expressed platelet-derived growth factor B chain or transforming growth factor alpha mRNA. However, examination of mRNA expression for the insulin-like growth factors revealed that 7 of 8 fibroblasts derived from benign lesions expressed insulin-like growth factor I (IGF-I) mRNA, while only 1 of 9 fibroblasts derived from malignancies expressed IGF-I mRNA. The opposite picture was seen for insulin-like growth factor II (IGF-II) mRNA expression, in which 1 of 9 benign-derived fibroblasts expressed IGF-II mRNA, while 5 of 9 malignant-derived fibroblasts expressed IGF-II. This correlated with previous in situ hybridization data, which showed IGF-I mRNA expression confined to the stroma of benign breast tissue. PDGF treatment of tumor fibroblasts resulted in a 3-fold increase in IGF-II mRNA. Thus there was an apparent dichotomy between IGF-I mRNA expression in the majority of fibroblasts derived from benign lesions and IGF-II mRNA expression in the majority of tumor-derived fibroblasts. Since the insulin-like growth factors are potent mitogens for breast tumor epithelial cells, this further supports the notion of a paracrine growth-promoting role for the insulin-like growth factors in breast lesions and suggests that IGF-II may be the more important growth promoter in malignant lesions.     

Amino-biphosphonate-mediated MMP-9 inhibition breaks the tumor-bone marrow axis responsible for myeloid-derived suppressor cell expansion and macrophage infiltration in tumor stroma

BALB-neuT mice expressing an activated rat c-erbB-2/neu transgene under the mouse mammary tumor virus long terminal repeat show enhanced hematopoiesis with hyperproduction of myeloid-derived suppressor cells (MDSC) because of vascular endothelial growth factor (VEGF) secreted by the tumor. Here, we show that both tumor and stromal cells express matrix metalloproteinase-9 (MMP-9), thereby increasing the levels of pro-MMP-9 in the sera of tumor-bearing mice. Treatment with amino-biphosphonates impaired tumor growth, significantly decreased MMP-9 expression and the number of macrophages in tumor stroma, and reduced MDSC expansion both in bone marrow and peripheral blood by dropping serum pro-MMP-9 and VEGF. We dissected the role of tumor-derived MMP-9 from that secreted by stromal leukocytes by transplanting bone marrow from MMP-9 knockout mice into BALB-neuT mice. Although bone marrow progenitor-derived MMP-9 had a major role in driving MDSC expansion, amino-biphosphonate treatment of bone marrow chimeras further reduced both myelopoiesis and the supportive tumor stroma, thus enhancing tumor necrosis. Moreover, by reducing MDSC, amino-biphosphonates overcome the tumor-induced immune suppression and improved the generation and maintenance of antitumor immune response induced by immunization against the p185/HER-2. Our data reveal that suppression of MMP-9 activity breaks the vicious loop linking tumor growth and myeloid cell expansion, thus reducing immunosuppression. Amino-biphosphonates disclose a specific MMP-9 inhibitory activity that may broaden their application above their current usage.     

HRPAP20: a novel calmodulin-binding protein that increases breast cancer cell invasion

We previously reported the identification of HRPAP20 (hormone-regulated proliferation-associated protein 20), a novel hormone-regulated, proliferation-associated protein. In tumor cell lines, constitutive HRPAP20 expression enhanced proliferation and suppressed apoptosis, characteristics frequently associated with malignant progression. Here, we report that highly invasive breast cancer cell lines and human breast tumor specimens express elevated HRPAP20, which in transfection experiments in MCF-7 and MDA-MB-231 cells, increased invasion. Results from mechanistic studies revealed that HRPAP20 bound to calmodulin (CaM) via a conserved CaM-binding motif. Transfection of MCF-7 breast cancer cells with HRPAP20 harboring a mutated CaM-binding motif (HRPAP20K73A) inhibited its interaction with CaM and failed to increase invasion. Other experiments revealed that transfection with HRPAP20, but not HRPAP20K73A, increased secretion of matrix metalloproteinase-9 (MMP-9). Moreover, knockdown of HRPAP20 with small interfering RNA in MCF-7/HRPAP20 transfectants and wild-type MDA-MB-231 cells reduced invasion and inhibited secretion of MMP-9. Together these observations suggest that HRPAP20 may be an important regulator of breast tumor cell invasion by a CaM-mediated mechanism that leads to increased MMP-9 secretion. We conclude that dysregulation of HRPAP20 expression in tumor cells may contribute to the observed phenotypic changes associated with breast cancer progression.     

Histopathological and immunohistochemical features associated with clinical response to neoadjuvant gefitinib therapy in early stage non-small cell lung cancer

Background

Matrix metalloproteinases (MMPs) are considered important players in angiogenesis and cancer progression. Several drugs developed for targeting MMPs have until now been without clinical efficacy. As both malignant cells and cells of the surrounding stroma contribute to tumor growth, we have explored the impact of MMP-2, -7 and -9 expression in both the tumor and stromal compartment of non-small-cell lung cancers (NSCLC).

Patients and methods

From 335 unselected stage I to IIIA NSCLC carcinomas, duplicate tumor and tumor-associated stromal cores were collected in tissue microarrays (TMAs). Immunohistochemistry was used to detect the expression of MMP-2, -7 and -9 in tumor and stromal cells.

Results

In univariate analyses, high tumor cell MMP-7 expression (P = 0.029) and high stromal MMP-9 expression (P = 0.001) were positive prognostic factors. In the multivariate analysis, high tumor cell MMP-7 expression (HR 1.58, CI 1.08-2.32, P = 0.020) and high stromal MMP-9 expression (HR 1.92, CI 1.25-2.96, P = 0.003) were independent positive prognostic factors for disease-specific survival.

Conclusion

High levels of MMP-7 in tumor cells and high levels of MMP-9 in tumor associated stroma were independent positive prognostic factors in NSCLC patients.     

Stromal influences on breast cancer cell growth.

Paracrine influences from fibroblasts derived from different sources of breast tissue on epithelial breast cancer cell growth in vitro were investigated. Medium conditioned (CM) by fibroblasts derived from tumours, adjacent normal breast tissue, and normal breast tissue obtained from reduction mammoplasty or from skin tissue significantly stimulated the growth of the steroid-receptor positive cell lines MCF-7 and ZR 75.1. The proliferation index (PI) on MCF-7 cells with CM from fibroblasts derived from breast tumour tissue was significantly higher than that obtained with fibroblasts derived from adjacent normal breast tissue (2p less than 0.05, n = 8). The PI obtained with CM from normal fibroblast cultures from reduction mammoplasty tissue, like normal tissue adjacent to the tumour, fell in the lower range of values. Skin fibroblast, like tumour tissue derived fibroblast, CM caused a high range PI. MDA-MB-231 and Evsa-T, two steroid-receptor negative cell lines, showed only a minor growth stimulatory responses with some of the fibroblast CM's. Evsa-T was occasionally inhibited by CM's. In conclusion, stromal factors play a role in the growth regulation of human breast cancer cells. The effects on cancer cell growth are, however, varying depending on the source of the stroma and the characteristics of the epithelial tumour cells.