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Asporin Is a Fibroblast-Derived TGF-β1 Inhibitor and a Tumor Suppressor Associated with Good Prognosis in Breast Cancer.

Maris P, Blomme A, Palacios AP, Costanza B, Bellahcène A, Bianchi E, Gofflot S, Drion P, Trombino GE, Di Valentin E, Cusumano PG, Maweja S, Jerusalem G, Delvenne P, Lifrange E, Castronovo V, Turtoi A - PLoS Med. (2015)

Bottom Line: In two in vivo murine models of TNBC, we observed that tumors expressing asporin exhibit significantly reduced growth (2-fold; p = 0.01) and metastatic properties (3-fold; p = 0.045).Survival analysis, based on gene expression (n = 375; 25-y follow-up), confirmed that low asporin levels are associated with a reduced likelihood of survival (hazard ratio = 0.58; 95% CI 0.37-0.91; p = 0.017).High asporin expression is significantly associated with less aggressive tumors, stratifying patients according to the clinical outcome.

View Article: PubMed Central - PubMed

Affiliation: Metastasis Research Laboratory, GIGA-Cancer, University of Liège, Liège, Belgium.

ABSTRACT

Background: Breast cancer is a leading malignancy affecting the female population worldwide. Most morbidity is caused by metastases that remain incurable to date. TGF-β1 has been identified as a key driving force behind metastatic breast cancer, with promising therapeutic implications.

Methods and findings: Employing immunohistochemistry (IHC) analysis, we report, to our knowledge for the first time, that asporin is overexpressed in the stroma of most human breast cancers and is not expressed in normal breast tissue. In vitro, asporin is secreted by breast fibroblasts upon exposure to conditioned medium from some but not all human breast cancer cells. While hormone receptor (HR) positive cells cause strong asporin expression, triple-negative breast cancer (TNBC) cells suppress it. Further, our findings show that soluble IL-1β, secreted by TNBC cells, is responsible for inhibiting asporin in normal and cancer-associated fibroblasts. Using recombinant protein, as well as a synthetic peptide fragment, we demonstrate the ability of asporin to inhibit TGF-β1-mediated SMAD2 phosphorylation, epithelial to mesenchymal transition, and stemness in breast cancer cells. In two in vivo murine models of TNBC, we observed that tumors expressing asporin exhibit significantly reduced growth (2-fold; p = 0.01) and metastatic properties (3-fold; p = 0.045). A retrospective IHC study performed on human breast carcinoma (n = 180) demonstrates that asporin expression is lowest in TNBC and HER2+ tumors, while HR+ tumors have significantly higher asporin expression (4-fold; p = 0.001). Assessment of asporin expression and patient outcome (n = 60; 10-y follow-up) shows that low protein levels in the primary breast lesion significantly delineate patients with bad outcome regardless of the tumor HR status (area under the curve = 0.87; 95% CI 0.78-0.96; p = 0.0001). Survival analysis, based on gene expression (n = 375; 25-y follow-up), confirmed that low asporin levels are associated with a reduced likelihood of survival (hazard ratio = 0.58; 95% CI 0.37-0.91; p = 0.017). Although these data highlight the potential of asporin to serve as a prognostic marker, confirmation of the clinical value would require a prospective study on a much larger patient cohort.

Conclusions: Our data show that asporin is a stroma-derived inhibitor of TGF-β1 and a tumor suppressor in breast cancer. High asporin expression is significantly associated with less aggressive tumors, stratifying patients according to the clinical outcome. Future pre-clinical studies should consider options for increasing asporin expression in TNBC as a promising strategy for targeted therapy.

No MeSH data available.


Related in: MedlinePlus

Asporin is overexpressed in breast cancer tissues.(A) Tissue-specific pattern of mRNA expression of asporin (ASPN), biglycan (BGN), and decorin (DCN). Source: BioGPS (http://biogps.org). The data are presented as mean ± standard deviation (SD). (B) Representative IHC staining of asporin expression in ductal carcinoma and adjacent non-tumoral breast tissue (left panel) and normal breast tissue obtained from patients undergoing mammary reduction surgery (right panel). Asporin is almost exclusively expressed in breast cancer lesions, while a very low signal is detectable in the adjacent non-tumoral regions. Normal breast tissues are negative. Images of representative fields were taken at 100× and 400× magnification. (C) Western blot analysis of asporin expression in tumoral breast cancer tissues (T) and the adjacent normal counterpart (AdN) of six ductal adenocarcinoma patients. Ponceau red staining was used as loading control.
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pmed.1001871.g001: Asporin is overexpressed in breast cancer tissues.(A) Tissue-specific pattern of mRNA expression of asporin (ASPN), biglycan (BGN), and decorin (DCN). Source: BioGPS (http://biogps.org). The data are presented as mean ± standard deviation (SD). (B) Representative IHC staining of asporin expression in ductal carcinoma and adjacent non-tumoral breast tissue (left panel) and normal breast tissue obtained from patients undergoing mammary reduction surgery (right panel). Asporin is almost exclusively expressed in breast cancer lesions, while a very low signal is detectable in the adjacent non-tumoral regions. Normal breast tissues are negative. Images of representative fields were taken at 100× and 400× magnification. (C) Western blot analysis of asporin expression in tumoral breast cancer tissues (T) and the adjacent normal counterpart (AdN) of six ductal adenocarcinoma patients. Ponceau red staining was used as loading control.

Mentions: We analyzed a publicly available gene expression repository (BioGPS, Scripps Research Institute) and compared the gene expression profiles in normal tissues of asporin and two other well-studied members of the SLRP family, biglycan and decorin (Fig 1A). The analysis showed that both biglycan and decorin are expressed in many normal tissues, whereas asporin expression was very low or not detected in most normal tissues, except the uterus. Next, we analyzed asporin expression using IHC in breast ductal adenocarcinoma (n = 30) as well as in adjacent non-tumoral tissue and normal breast tissue from breast reduction surgery (n = 10) (Fig 1B). Strong asporin expression was detectable in the stroma of the cancer lesions, with epithelial cancer cells being negative for asporin expression. Adjacent non-tumoral tissue showed a moderate positivity in the extracellular matrix and no positivity in non-tumoral epithelial cells. Healthy breast tissue was negative for asporin expression. Western blot analysis on fresh tissue extracts from matched tumoral and adjacent non-tumoral parts of the resected breast specimens confirmed our IHC observations (Fig 1C).


Asporin Is a Fibroblast-Derived TGF-β1 Inhibitor and a Tumor Suppressor Associated with Good Prognosis in Breast Cancer.

Maris P, Blomme A, Palacios AP, Costanza B, Bellahcène A, Bianchi E, Gofflot S, Drion P, Trombino GE, Di Valentin E, Cusumano PG, Maweja S, Jerusalem G, Delvenne P, Lifrange E, Castronovo V, Turtoi A - PLoS Med. (2015)

Asporin is overexpressed in breast cancer tissues.(A) Tissue-specific pattern of mRNA expression of asporin (ASPN), biglycan (BGN), and decorin (DCN). Source: BioGPS (http://biogps.org). The data are presented as mean ± standard deviation (SD). (B) Representative IHC staining of asporin expression in ductal carcinoma and adjacent non-tumoral breast tissue (left panel) and normal breast tissue obtained from patients undergoing mammary reduction surgery (right panel). Asporin is almost exclusively expressed in breast cancer lesions, while a very low signal is detectable in the adjacent non-tumoral regions. Normal breast tissues are negative. Images of representative fields were taken at 100× and 400× magnification. (C) Western blot analysis of asporin expression in tumoral breast cancer tissues (T) and the adjacent normal counterpart (AdN) of six ductal adenocarcinoma patients. Ponceau red staining was used as loading control.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4556693&req=5

pmed.1001871.g001: Asporin is overexpressed in breast cancer tissues.(A) Tissue-specific pattern of mRNA expression of asporin (ASPN), biglycan (BGN), and decorin (DCN). Source: BioGPS (http://biogps.org). The data are presented as mean ± standard deviation (SD). (B) Representative IHC staining of asporin expression in ductal carcinoma and adjacent non-tumoral breast tissue (left panel) and normal breast tissue obtained from patients undergoing mammary reduction surgery (right panel). Asporin is almost exclusively expressed in breast cancer lesions, while a very low signal is detectable in the adjacent non-tumoral regions. Normal breast tissues are negative. Images of representative fields were taken at 100× and 400× magnification. (C) Western blot analysis of asporin expression in tumoral breast cancer tissues (T) and the adjacent normal counterpart (AdN) of six ductal adenocarcinoma patients. Ponceau red staining was used as loading control.
Mentions: We analyzed a publicly available gene expression repository (BioGPS, Scripps Research Institute) and compared the gene expression profiles in normal tissues of asporin and two other well-studied members of the SLRP family, biglycan and decorin (Fig 1A). The analysis showed that both biglycan and decorin are expressed in many normal tissues, whereas asporin expression was very low or not detected in most normal tissues, except the uterus. Next, we analyzed asporin expression using IHC in breast ductal adenocarcinoma (n = 30) as well as in adjacent non-tumoral tissue and normal breast tissue from breast reduction surgery (n = 10) (Fig 1B). Strong asporin expression was detectable in the stroma of the cancer lesions, with epithelial cancer cells being negative for asporin expression. Adjacent non-tumoral tissue showed a moderate positivity in the extracellular matrix and no positivity in non-tumoral epithelial cells. Healthy breast tissue was negative for asporin expression. Western blot analysis on fresh tissue extracts from matched tumoral and adjacent non-tumoral parts of the resected breast specimens confirmed our IHC observations (Fig 1C).

Bottom Line: In two in vivo murine models of TNBC, we observed that tumors expressing asporin exhibit significantly reduced growth (2-fold; p = 0.01) and metastatic properties (3-fold; p = 0.045).Survival analysis, based on gene expression (n = 375; 25-y follow-up), confirmed that low asporin levels are associated with a reduced likelihood of survival (hazard ratio = 0.58; 95% CI 0.37-0.91; p = 0.017).High asporin expression is significantly associated with less aggressive tumors, stratifying patients according to the clinical outcome.

View Article: PubMed Central - PubMed

Affiliation: Metastasis Research Laboratory, GIGA-Cancer, University of Liège, Liège, Belgium.

ABSTRACT

Background: Breast cancer is a leading malignancy affecting the female population worldwide. Most morbidity is caused by metastases that remain incurable to date. TGF-β1 has been identified as a key driving force behind metastatic breast cancer, with promising therapeutic implications.

Methods and findings: Employing immunohistochemistry (IHC) analysis, we report, to our knowledge for the first time, that asporin is overexpressed in the stroma of most human breast cancers and is not expressed in normal breast tissue. In vitro, asporin is secreted by breast fibroblasts upon exposure to conditioned medium from some but not all human breast cancer cells. While hormone receptor (HR) positive cells cause strong asporin expression, triple-negative breast cancer (TNBC) cells suppress it. Further, our findings show that soluble IL-1β, secreted by TNBC cells, is responsible for inhibiting asporin in normal and cancer-associated fibroblasts. Using recombinant protein, as well as a synthetic peptide fragment, we demonstrate the ability of asporin to inhibit TGF-β1-mediated SMAD2 phosphorylation, epithelial to mesenchymal transition, and stemness in breast cancer cells. In two in vivo murine models of TNBC, we observed that tumors expressing asporin exhibit significantly reduced growth (2-fold; p = 0.01) and metastatic properties (3-fold; p = 0.045). A retrospective IHC study performed on human breast carcinoma (n = 180) demonstrates that asporin expression is lowest in TNBC and HER2+ tumors, while HR+ tumors have significantly higher asporin expression (4-fold; p = 0.001). Assessment of asporin expression and patient outcome (n = 60; 10-y follow-up) shows that low protein levels in the primary breast lesion significantly delineate patients with bad outcome regardless of the tumor HR status (area under the curve = 0.87; 95% CI 0.78-0.96; p = 0.0001). Survival analysis, based on gene expression (n = 375; 25-y follow-up), confirmed that low asporin levels are associated with a reduced likelihood of survival (hazard ratio = 0.58; 95% CI 0.37-0.91; p = 0.017). Although these data highlight the potential of asporin to serve as a prognostic marker, confirmation of the clinical value would require a prospective study on a much larger patient cohort.

Conclusions: Our data show that asporin is a stroma-derived inhibitor of TGF-β1 and a tumor suppressor in breast cancer. High asporin expression is significantly associated with less aggressive tumors, stratifying patients according to the clinical outcome. Future pre-clinical studies should consider options for increasing asporin expression in TNBC as a promising strategy for targeted therapy.

No MeSH data available.


Related in: MedlinePlus