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MMP-9 expression varies according to molecular subtypes of breast cancer.

Yousef EM, Tahir MR, St-Pierre Y, Gaboury LA - BMC Cancer (2014)

Bottom Line: We next ascertained MMP-9 expression in both normal breast tissue and in human breast carcinoma tissue microarrays.Significant increase in MMP-9 expression was found in breast cancer cells where compared to normal breast tissue.Lastly, the clinical relevance of MMP-9 overexpression is strongly supported by its significant association with a higher incidence of metastasis and relapse.

View Article: PubMed Central - PubMed

Affiliation: Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Canada. louis.gaboury@umontreal.ca.

ABSTRACT

Background: In 2014, breast cancer remains a major cause of mortality worldwide mostly due to tumor relapse and metastasis. There is currently a great interest in identifying cancer biomarkers and signalling pathways mechanistically related to breast cancer progression. Matrix metalloproteinase-9 (MMP-9) is a member of matrix degrading enzymes involved in cancer development, invasion and metastasis. Our objective was to investigate MMP-9 expression in normal human breast tissue and to compare it to that of breast cancer of various histological grades and molecular subtypes. We also sought to correlate MMP-9 expression with the incidence of metastasis, survival rates and relapse in breast cancer patients.

Methods: MMP-9 was first studied using in silico analysis on available DNA microarray and RNA sequencing data of human breast cancer tissues and human breast cancer cell lines. We next ascertained MMP-9 expression in both normal breast tissue and in human breast carcinoma tissue microarrays.

Results: Significant increase in MMP-9 expression was found in breast cancer cells where compared to normal breast tissue. A positive correlation could also be established between elevated levels of MMP-9 and breast cancer of high histological grade. Furthermore, our results indicate that not only MMP-9 is differentially expressed between each molecular subset but also, more importantly MMP-9 overexpression revealed itself as a startling feature of triple-negative and HER2-positive breast cancers. Lastly, the clinical relevance of MMP-9 overexpression is strongly supported by its significant association with a higher incidence of metastasis and relapse.

Conclusions: Differential expression of MMP-9 reflects the extent of cellular differentiation in breast cancer cells and is closely related to the most aggressive subtypes of breast cancer. Hence, MMP-9 is a promising prognostic biomarker of high-grade breast cancer. In our opinion, MMP-9 expression could help segregate subsets of aggressive breast cancer into clinically meaningful subtypes.

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Related in: MedlinePlus

Validation of MMP-9 antibody specificity for IHC studies. (A) Human colorectal carcinoma with intense cytoplasmic labeling of the cancer cells after incubating the section with MMP-9 primary antibody. (B) Adjacent section from the same colorectal tumor incubated with a non-immune serum that contains IgG (same isotype/ same species) showing complete lack of expression of MMP-9. (C) Benign myofibroblastoma of breast tissue and (D) Benign breast fibroadenoma do not express MMP-9. Magnification 20X (A-D).
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Fig3: Validation of MMP-9 antibody specificity for IHC studies. (A) Human colorectal carcinoma with intense cytoplasmic labeling of the cancer cells after incubating the section with MMP-9 primary antibody. (B) Adjacent section from the same colorectal tumor incubated with a non-immune serum that contains IgG (same isotype/ same species) showing complete lack of expression of MMP-9. (C) Benign myofibroblastoma of breast tissue and (D) Benign breast fibroadenoma do not express MMP-9. Magnification 20X (A-D).

Mentions: Optimization of MMP-9 immune reactivity was a prerequisite to validating the specificity of the IHC reaction. In accordance with the Human Protein Atlas [30] and a review of the literature, human colorectal carcinoma was used as a positive control to assess the levels of MMP-9 expression in human cancers [31]. Our results are in complete agreement with this prediction as shown by the strong cytoplasmic labeling observed in colorectal carcinoma cells (Figure 3A). Additional adjacent sections from the same colonic tumor incubated with a non-immune serum containing IgG (same isotype/same species) remained entirely negative. Of note, all subsequent steps of the immunostaining reaction such as addition of the secondary antibody and the revealing reaction were carried out in a strictly identical fashion (Figure 3B). We also thought fit to include benign breast lesions such as myofibroblastoma (Figure 3C) and fibroadenoma (Figure 3D) as negative controls [20]. Again, no immune reactivity could be detected after the successive addition of MMP-9 primary antibody, secondary antibody and chromogen.


MMP-9 expression varies according to molecular subtypes of breast cancer.

Yousef EM, Tahir MR, St-Pierre Y, Gaboury LA - BMC Cancer (2014)

Validation of MMP-9 antibody specificity for IHC studies. (A) Human colorectal carcinoma with intense cytoplasmic labeling of the cancer cells after incubating the section with MMP-9 primary antibody. (B) Adjacent section from the same colorectal tumor incubated with a non-immune serum that contains IgG (same isotype/ same species) showing complete lack of expression of MMP-9. (C) Benign myofibroblastoma of breast tissue and (D) Benign breast fibroadenoma do not express MMP-9. Magnification 20X (A-D).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4150970&req=5

Fig3: Validation of MMP-9 antibody specificity for IHC studies. (A) Human colorectal carcinoma with intense cytoplasmic labeling of the cancer cells after incubating the section with MMP-9 primary antibody. (B) Adjacent section from the same colorectal tumor incubated with a non-immune serum that contains IgG (same isotype/ same species) showing complete lack of expression of MMP-9. (C) Benign myofibroblastoma of breast tissue and (D) Benign breast fibroadenoma do not express MMP-9. Magnification 20X (A-D).
Mentions: Optimization of MMP-9 immune reactivity was a prerequisite to validating the specificity of the IHC reaction. In accordance with the Human Protein Atlas [30] and a review of the literature, human colorectal carcinoma was used as a positive control to assess the levels of MMP-9 expression in human cancers [31]. Our results are in complete agreement with this prediction as shown by the strong cytoplasmic labeling observed in colorectal carcinoma cells (Figure 3A). Additional adjacent sections from the same colonic tumor incubated with a non-immune serum containing IgG (same isotype/same species) remained entirely negative. Of note, all subsequent steps of the immunostaining reaction such as addition of the secondary antibody and the revealing reaction were carried out in a strictly identical fashion (Figure 3B). We also thought fit to include benign breast lesions such as myofibroblastoma (Figure 3C) and fibroadenoma (Figure 3D) as negative controls [20]. Again, no immune reactivity could be detected after the successive addition of MMP-9 primary antibody, secondary antibody and chromogen.

Bottom Line: We next ascertained MMP-9 expression in both normal breast tissue and in human breast carcinoma tissue microarrays.Significant increase in MMP-9 expression was found in breast cancer cells where compared to normal breast tissue.Lastly, the clinical relevance of MMP-9 overexpression is strongly supported by its significant association with a higher incidence of metastasis and relapse.

View Article: PubMed Central - PubMed

Affiliation: Institute for Research in Immunology and Cancer, Université de Montréal, Montréal, Canada. louis.gaboury@umontreal.ca.

ABSTRACT

Background: In 2014, breast cancer remains a major cause of mortality worldwide mostly due to tumor relapse and metastasis. There is currently a great interest in identifying cancer biomarkers and signalling pathways mechanistically related to breast cancer progression. Matrix metalloproteinase-9 (MMP-9) is a member of matrix degrading enzymes involved in cancer development, invasion and metastasis. Our objective was to investigate MMP-9 expression in normal human breast tissue and to compare it to that of breast cancer of various histological grades and molecular subtypes. We also sought to correlate MMP-9 expression with the incidence of metastasis, survival rates and relapse in breast cancer patients.

Methods: MMP-9 was first studied using in silico analysis on available DNA microarray and RNA sequencing data of human breast cancer tissues and human breast cancer cell lines. We next ascertained MMP-9 expression in both normal breast tissue and in human breast carcinoma tissue microarrays.

Results: Significant increase in MMP-9 expression was found in breast cancer cells where compared to normal breast tissue. A positive correlation could also be established between elevated levels of MMP-9 and breast cancer of high histological grade. Furthermore, our results indicate that not only MMP-9 is differentially expressed between each molecular subset but also, more importantly MMP-9 overexpression revealed itself as a startling feature of triple-negative and HER2-positive breast cancers. Lastly, the clinical relevance of MMP-9 overexpression is strongly supported by its significant association with a higher incidence of metastasis and relapse.

Conclusions: Differential expression of MMP-9 reflects the extent of cellular differentiation in breast cancer cells and is closely related to the most aggressive subtypes of breast cancer. Hence, MMP-9 is a promising prognostic biomarker of high-grade breast cancer. In our opinion, MMP-9 expression could help segregate subsets of aggressive breast cancer into clinically meaningful subtypes.

Show MeSH
Related in: MedlinePlus