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MUC4 overexpression augments cell migration and metastasis through EGFR family proteins in triple negative breast cancer cells.

Mukhopadhyay P, Lakshmanan I, Ponnusamy MP, Chakraborty S, Jain M, Pai P, Smith LM, Lele SM, Batra SK - PLoS ONE (2013)

Bottom Line: Moreover, our studies also showed that knockdown of MUC4 in TNBC cells induced molecular changes suggestive of mesenchymal to epithelial transition.We further demonstrate that MUC4 is differentially over-expressed in invasive TNBC tissues compared to normal breast tissue.MUC4 mucin expression is associated with TNBC pathobiology, and its knockdown reduced aggressiveness in vitro, and tumorigenesis and metastasis in vivo.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska, USA.

ABSTRACT

Introduction: Current studies indicate that triple negative breast cancer (TNBC), an aggressive breast cancer subtype, is associated with poor prognosis and an early pattern of metastasis. Emerging evidence suggests that MUC4 mucin is associated with metastasis of various cancers, including breast cancer. However, the functional role of MUC4 remains unclear in breast cancers, especially in TNBCs.

Method: In the present study, we investigated the functional and mechanistic roles of MUC4 in potentiating pathogenic signals including EGFR family proteins to promote TNBC aggressiveness using in vitro and in vivo studies. Further, we studied the expression of MUC4 in invasive TNBC tissue and normal breast tissue by immunostaining.

Results: MUC4 promotes proliferation, anchorage-dependent and-independent growth of TNBC cells, augments TNBC cell migratory and invasive potential in vitro, and enhances tumorigenicity and metastasis in vivo. In addition, our studies demonstrated that MUC4 up-regulates the EGFR family of proteins, and augments downstream Erk1/2, PKC-γ, and FAK mediated oncogenic signaling. Moreover, our studies also showed that knockdown of MUC4 in TNBC cells induced molecular changes suggestive of mesenchymal to epithelial transition. We also demonstrated in this study, for the first time, that knockdown of MUC4 was associated with reduced expression of EGFR and ErbB3 (EGFR family proteins) in TNBC cells, suggesting that MUC4 uses an alternative to ErbB2 mechanism to promote aggressiveness. We further demonstrate that MUC4 is differentially over-expressed in invasive TNBC tissues compared to normal breast tissue.

Conclusions: MUC4 mucin expression is associated with TNBC pathobiology, and its knockdown reduced aggressiveness in vitro, and tumorigenesis and metastasis in vivo. Overall, our findings suggest that MUC4 mucin promotes invasive activities of TNBC cells by altering the expression of EGFR, ErbB2, and ErbB3 molecules and their downstream signaling.

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Related in: MedlinePlus

Differential over-expression of MUC4 mucin in TNBC tissues compared with normal breast tissues.Immunohistological analyses were performed using the anti-MUC4 mouse monoclonal antibody (2214, generated in our laboratory, against a sequence close to the N-terminus of human MUC4) on tumor microarrays (BR1503 and BR10010) containing normal breast and invasive TNBC tissues and observed under a Nikon light microscope. MUC4 expression in invasive primary (n = 35) TNBC tissues were compared with normal breast tissue (n = 6) in a set of arrays. High immune-reactivity for MUC4 was detected in invasive TNBC tissues, but not in normal breast tissues. The image presented was taken at 4× magnification, and the higher magnification images (marked with a red box) were taken at 10× magnification.
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pone-0054455-g006: Differential over-expression of MUC4 mucin in TNBC tissues compared with normal breast tissues.Immunohistological analyses were performed using the anti-MUC4 mouse monoclonal antibody (2214, generated in our laboratory, against a sequence close to the N-terminus of human MUC4) on tumor microarrays (BR1503 and BR10010) containing normal breast and invasive TNBC tissues and observed under a Nikon light microscope. MUC4 expression in invasive primary (n = 35) TNBC tissues were compared with normal breast tissue (n = 6) in a set of arrays. High immune-reactivity for MUC4 was detected in invasive TNBC tissues, but not in normal breast tissues. The image presented was taken at 4× magnification, and the higher magnification images (marked with a red box) were taken at 10× magnification.

Mentions: To determine the clinical relevance of MUC4 expression in TNBCs, immunohistological analyses were performed on TNBC tumor microarrays using anti-MUC4 antibody [37]. While expression of MUC4 was not detected in normal breast tissues, primary invasive TNBC tissues were found to be positive for MUC4 expression (Figure 6). A total of 35 primary tissues, and 6 normal breast tissues were examined. No expression of MUC4 was observed in the normal breast tissues (0/6, composite score 0±0), however, 54% (20/35, composite score 2.7±1.3, p = 0.018) primary invasive TNBC tissues were found to be positive for MUC4 expression. Composite score calculated based on only 20 MUC4 positive samples was 4.8±2.7, p = 0.0002.


MUC4 overexpression augments cell migration and metastasis through EGFR family proteins in triple negative breast cancer cells.

Mukhopadhyay P, Lakshmanan I, Ponnusamy MP, Chakraborty S, Jain M, Pai P, Smith LM, Lele SM, Batra SK - PLoS ONE (2013)

Differential over-expression of MUC4 mucin in TNBC tissues compared with normal breast tissues.Immunohistological analyses were performed using the anti-MUC4 mouse monoclonal antibody (2214, generated in our laboratory, against a sequence close to the N-terminus of human MUC4) on tumor microarrays (BR1503 and BR10010) containing normal breast and invasive TNBC tissues and observed under a Nikon light microscope. MUC4 expression in invasive primary (n = 35) TNBC tissues were compared with normal breast tissue (n = 6) in a set of arrays. High immune-reactivity for MUC4 was detected in invasive TNBC tissues, but not in normal breast tissues. The image presented was taken at 4× magnification, and the higher magnification images (marked with a red box) were taken at 10× magnification.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3569463&req=5

pone-0054455-g006: Differential over-expression of MUC4 mucin in TNBC tissues compared with normal breast tissues.Immunohistological analyses were performed using the anti-MUC4 mouse monoclonal antibody (2214, generated in our laboratory, against a sequence close to the N-terminus of human MUC4) on tumor microarrays (BR1503 and BR10010) containing normal breast and invasive TNBC tissues and observed under a Nikon light microscope. MUC4 expression in invasive primary (n = 35) TNBC tissues were compared with normal breast tissue (n = 6) in a set of arrays. High immune-reactivity for MUC4 was detected in invasive TNBC tissues, but not in normal breast tissues. The image presented was taken at 4× magnification, and the higher magnification images (marked with a red box) were taken at 10× magnification.
Mentions: To determine the clinical relevance of MUC4 expression in TNBCs, immunohistological analyses were performed on TNBC tumor microarrays using anti-MUC4 antibody [37]. While expression of MUC4 was not detected in normal breast tissues, primary invasive TNBC tissues were found to be positive for MUC4 expression (Figure 6). A total of 35 primary tissues, and 6 normal breast tissues were examined. No expression of MUC4 was observed in the normal breast tissues (0/6, composite score 0±0), however, 54% (20/35, composite score 2.7±1.3, p = 0.018) primary invasive TNBC tissues were found to be positive for MUC4 expression. Composite score calculated based on only 20 MUC4 positive samples was 4.8±2.7, p = 0.0002.

Bottom Line: Moreover, our studies also showed that knockdown of MUC4 in TNBC cells induced molecular changes suggestive of mesenchymal to epithelial transition.We further demonstrate that MUC4 is differentially over-expressed in invasive TNBC tissues compared to normal breast tissue.MUC4 mucin expression is associated with TNBC pathobiology, and its knockdown reduced aggressiveness in vitro, and tumorigenesis and metastasis in vivo.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska, USA.

ABSTRACT

Introduction: Current studies indicate that triple negative breast cancer (TNBC), an aggressive breast cancer subtype, is associated with poor prognosis and an early pattern of metastasis. Emerging evidence suggests that MUC4 mucin is associated with metastasis of various cancers, including breast cancer. However, the functional role of MUC4 remains unclear in breast cancers, especially in TNBCs.

Method: In the present study, we investigated the functional and mechanistic roles of MUC4 in potentiating pathogenic signals including EGFR family proteins to promote TNBC aggressiveness using in vitro and in vivo studies. Further, we studied the expression of MUC4 in invasive TNBC tissue and normal breast tissue by immunostaining.

Results: MUC4 promotes proliferation, anchorage-dependent and-independent growth of TNBC cells, augments TNBC cell migratory and invasive potential in vitro, and enhances tumorigenicity and metastasis in vivo. In addition, our studies demonstrated that MUC4 up-regulates the EGFR family of proteins, and augments downstream Erk1/2, PKC-γ, and FAK mediated oncogenic signaling. Moreover, our studies also showed that knockdown of MUC4 in TNBC cells induced molecular changes suggestive of mesenchymal to epithelial transition. We also demonstrated in this study, for the first time, that knockdown of MUC4 was associated with reduced expression of EGFR and ErbB3 (EGFR family proteins) in TNBC cells, suggesting that MUC4 uses an alternative to ErbB2 mechanism to promote aggressiveness. We further demonstrate that MUC4 is differentially over-expressed in invasive TNBC tissues compared to normal breast tissue.

Conclusions: MUC4 mucin expression is associated with TNBC pathobiology, and its knockdown reduced aggressiveness in vitro, and tumorigenesis and metastasis in vivo. Overall, our findings suggest that MUC4 mucin promotes invasive activities of TNBC cells by altering the expression of EGFR, ErbB2, and ErbB3 molecules and their downstream signaling.

Show MeSH
Related in: MedlinePlus