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Aberrant activation of NF-κB signaling in mammary epithelium leads to abnormal growth and ductal carcinoma in situ.

Barham W, Chen L, Tikhomirov O, Onishko H, Gleaves L, Stricker TP, Blackwell TS, Yull FE - BMC Cancer (2015)

Bottom Line: We found that even a short pulse of NF-κB activation could induce profound remodeling of mammary ductal structures.These results indicate that aberrant NF-κB activation within mammary epithelium can lead to molecular and morphological changes consistent with the earliest stages of breast cancer.Thus, inhibition of NF-κB signaling following acute inflammation or the initial signs of hyperplastic ductal growth could represent an important opportunity for breast cancer prevention.

View Article: PubMed Central - PubMed

Affiliation: Department of Cancer Biology, Vanderbilt University Medical Center, 23rd Ave S and Pierce PRB 325, Nashville, TN, 37232, USA. Whitney.Barham@vanderbilt.edu.

ABSTRACT

Background: Approximately 1 in 5 women diagnosed with breast cancer are considered to have in situ disease, most often termed ductal carcinoma in situ (DCIS). Though recognized as a risk factor for the development of more invasive cancer, it remains unclear what factors contribute to DCIS development. It has been shown that inflammation contributes to the progression of a variety of tumor types, and nuclear factor kappa B (NF-κB) is recognized as a master-regulator of inflammatory signaling. However, the contributions of NF-κB signaling to tumor initiation are less well understood. Aberrant up-regulation of NF-κB activity, either systemically or locally within the breast, could occur due to a variety of commonly experienced stimuli such as acute infection, obesity, or psychological stress. In this study, we seek to determine if activation of NF-κB in mammary epithelium could play a role in the formation of hyperplastic ductal lesions.

Methods: Our studies utilize a doxycycline-inducible transgenic mouse model in which constitutively active IKKβ is expressed specifically in mammary epithelium. All previously published models of NF-κB modulation in the virgin mammary gland have been constitutive models, with transgene or knock-out present throughout the life and development of the animal. For the first time, we will induce activation at later time points after normal ducts have formed, thus being able to determine if NF-κB activation can promote pre-malignant changes in previously normal mammary epithelium.

Results: We found that even a short pulse of NF-κB activation could induce profound remodeling of mammary ductal structures. Short-term activation created hyperproliferative, enlarged ducts with filled lumens. Increased expression of inflammatory markers was concurrent with the down-regulation of hormone receptors and markers of epithelial differentiation. Furthermore, the oncoprotein mucin 1, known to be up-regulated in human and mouse DCIS, was over-expressed and mislocalized in the activated ductal tissue.

Conclusions: These results indicate that aberrant NF-κB activation within mammary epithelium can lead to molecular and morphological changes consistent with the earliest stages of breast cancer. Thus, inhibition of NF-κB signaling following acute inflammation or the initial signs of hyperplastic ductal growth could represent an important opportunity for breast cancer prevention.

No MeSH data available.


Related in: MedlinePlus

MUC1 oncoprotein is up-regulated and mislocalized in IKMV mammary epithelium. RNA was isolated from mammary glands of IKMV and control mice after 3 days of dox treatment (6 week time point). a The hyperplastic IKMV ducts have increased expression of MUC1 via qRT-PCR (n = 5 control, n = 6 IKMV samples; *p = 0.0119). b Staining for MUC1 indicates that it is properly localized to the apical surface of luminal epithelium in control ducts but it has become repositioned to the entire cell membrane in many of the cells within the IKMV hyperplastic ducts (red staining is MUC1, blue is DAPI; 40X images are shown; images at bottom are magnified to show detail)
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Fig8: MUC1 oncoprotein is up-regulated and mislocalized in IKMV mammary epithelium. RNA was isolated from mammary glands of IKMV and control mice after 3 days of dox treatment (6 week time point). a The hyperplastic IKMV ducts have increased expression of MUC1 via qRT-PCR (n = 5 control, n = 6 IKMV samples; *p = 0.0119). b Staining for MUC1 indicates that it is properly localized to the apical surface of luminal epithelium in control ducts but it has become repositioned to the entire cell membrane in many of the cells within the IKMV hyperplastic ducts (red staining is MUC1, blue is DAPI; 40X images are shown; images at bottom are magnified to show detail)

Mentions: To further strengthen correlations between the IKMV phenotype and DCIS, we analyzed the expression and localization of Mucin 1 (MUC1). This protein is normally expressed on the apical surface of mammary epithelium where, similar to other mucins, it plays a role in host defense against pathogens. Beyond this role in normal physiology, MUC1 is considered an oncoprotein, as its overexpression can functionally drive malignant transformation in breast epithelium [33]. When luminal epithelial cells lose their polarity due to stress or transformation, MUC1 can be expressed around the entire cell membrane rather than staying localized to the apical surface. This repositioning of MUC1 has been noted in both ductal hyperplasia with atypia and in DCIS of the breast [34]. We analyzed our 6 week virgin, 3 day dox treated samples for MUC1 expression and observed a significant up-regulation of MUC1 in IKMV tissue via qRT-PCR (Fig. 8a). Further, we completed immunofluorescent staining and found that IKMV ducts contained MUC1 positive cells dispersed throughout the filled lumens (Fig. 8b). These positive cells displayed MUC1 staining around the entire cell membrane. This was in contrast to the control ducts, which had appropriately localized MUC1 along the apical surface of each lumen.Fig. 8


Aberrant activation of NF-κB signaling in mammary epithelium leads to abnormal growth and ductal carcinoma in situ.

Barham W, Chen L, Tikhomirov O, Onishko H, Gleaves L, Stricker TP, Blackwell TS, Yull FE - BMC Cancer (2015)

MUC1 oncoprotein is up-regulated and mislocalized in IKMV mammary epithelium. RNA was isolated from mammary glands of IKMV and control mice after 3 days of dox treatment (6 week time point). a The hyperplastic IKMV ducts have increased expression of MUC1 via qRT-PCR (n = 5 control, n = 6 IKMV samples; *p = 0.0119). b Staining for MUC1 indicates that it is properly localized to the apical surface of luminal epithelium in control ducts but it has become repositioned to the entire cell membrane in many of the cells within the IKMV hyperplastic ducts (red staining is MUC1, blue is DAPI; 40X images are shown; images at bottom are magnified to show detail)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4590702&req=5

Fig8: MUC1 oncoprotein is up-regulated and mislocalized in IKMV mammary epithelium. RNA was isolated from mammary glands of IKMV and control mice after 3 days of dox treatment (6 week time point). a The hyperplastic IKMV ducts have increased expression of MUC1 via qRT-PCR (n = 5 control, n = 6 IKMV samples; *p = 0.0119). b Staining for MUC1 indicates that it is properly localized to the apical surface of luminal epithelium in control ducts but it has become repositioned to the entire cell membrane in many of the cells within the IKMV hyperplastic ducts (red staining is MUC1, blue is DAPI; 40X images are shown; images at bottom are magnified to show detail)
Mentions: To further strengthen correlations between the IKMV phenotype and DCIS, we analyzed the expression and localization of Mucin 1 (MUC1). This protein is normally expressed on the apical surface of mammary epithelium where, similar to other mucins, it plays a role in host defense against pathogens. Beyond this role in normal physiology, MUC1 is considered an oncoprotein, as its overexpression can functionally drive malignant transformation in breast epithelium [33]. When luminal epithelial cells lose their polarity due to stress or transformation, MUC1 can be expressed around the entire cell membrane rather than staying localized to the apical surface. This repositioning of MUC1 has been noted in both ductal hyperplasia with atypia and in DCIS of the breast [34]. We analyzed our 6 week virgin, 3 day dox treated samples for MUC1 expression and observed a significant up-regulation of MUC1 in IKMV tissue via qRT-PCR (Fig. 8a). Further, we completed immunofluorescent staining and found that IKMV ducts contained MUC1 positive cells dispersed throughout the filled lumens (Fig. 8b). These positive cells displayed MUC1 staining around the entire cell membrane. This was in contrast to the control ducts, which had appropriately localized MUC1 along the apical surface of each lumen.Fig. 8

Bottom Line: We found that even a short pulse of NF-κB activation could induce profound remodeling of mammary ductal structures.These results indicate that aberrant NF-κB activation within mammary epithelium can lead to molecular and morphological changes consistent with the earliest stages of breast cancer.Thus, inhibition of NF-κB signaling following acute inflammation or the initial signs of hyperplastic ductal growth could represent an important opportunity for breast cancer prevention.

View Article: PubMed Central - PubMed

Affiliation: Department of Cancer Biology, Vanderbilt University Medical Center, 23rd Ave S and Pierce PRB 325, Nashville, TN, 37232, USA. Whitney.Barham@vanderbilt.edu.

ABSTRACT

Background: Approximately 1 in 5 women diagnosed with breast cancer are considered to have in situ disease, most often termed ductal carcinoma in situ (DCIS). Though recognized as a risk factor for the development of more invasive cancer, it remains unclear what factors contribute to DCIS development. It has been shown that inflammation contributes to the progression of a variety of tumor types, and nuclear factor kappa B (NF-κB) is recognized as a master-regulator of inflammatory signaling. However, the contributions of NF-κB signaling to tumor initiation are less well understood. Aberrant up-regulation of NF-κB activity, either systemically or locally within the breast, could occur due to a variety of commonly experienced stimuli such as acute infection, obesity, or psychological stress. In this study, we seek to determine if activation of NF-κB in mammary epithelium could play a role in the formation of hyperplastic ductal lesions.

Methods: Our studies utilize a doxycycline-inducible transgenic mouse model in which constitutively active IKKβ is expressed specifically in mammary epithelium. All previously published models of NF-κB modulation in the virgin mammary gland have been constitutive models, with transgene or knock-out present throughout the life and development of the animal. For the first time, we will induce activation at later time points after normal ducts have formed, thus being able to determine if NF-κB activation can promote pre-malignant changes in previously normal mammary epithelium.

Results: We found that even a short pulse of NF-κB activation could induce profound remodeling of mammary ductal structures. Short-term activation created hyperproliferative, enlarged ducts with filled lumens. Increased expression of inflammatory markers was concurrent with the down-regulation of hormone receptors and markers of epithelial differentiation. Furthermore, the oncoprotein mucin 1, known to be up-regulated in human and mouse DCIS, was over-expressed and mislocalized in the activated ductal tissue.

Conclusions: These results indicate that aberrant NF-κB activation within mammary epithelium can lead to molecular and morphological changes consistent with the earliest stages of breast cancer. Thus, inhibition of NF-κB signaling following acute inflammation or the initial signs of hyperplastic ductal growth could represent an important opportunity for breast cancer prevention.

No MeSH data available.


Related in: MedlinePlus