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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

Short term activation of NF-κB in mammary epithelium leads to ducts with filled lumens. Intact 6 week old virgin IKMV and control littermates were dox-treated (2 g/L) for 3 days prior to sacrifice. a Haematoxylin stained whole mounts of control and IKMV glands reveal changes in IKMV ducts. In H&E stained sections (below), we observed a complete occlusion of IKMV ducts throughout the gland. b Increased size of individual IKMV ducts is apparent in 20X images with calibration bars (150 μm). Multiple measurements of duct area across samples are quantified at right (n = 3 control, n = 3 IKMV glands, total of 65 individual ducts were measured; *** p < 0.001). c Double transgenic IKMV virgin females were kept on normal water at the 6 week virgin time point and collected 3 days later along with the dox-treated cohort. Images of H&E stained mammary tissue show ducts of untreated controls have normal morphology, with no lumen-filling or hyperplastic growth (10X magnification at left, 20X at right)
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Fig3: Short term activation of NF-κB in mammary epithelium leads to ducts with filled lumens. Intact 6 week old virgin IKMV and control littermates were dox-treated (2 g/L) for 3 days prior to sacrifice. a Haematoxylin stained whole mounts of control and IKMV glands reveal changes in IKMV ducts. In H&E stained sections (below), we observed a complete occlusion of IKMV ducts throughout the gland. b Increased size of individual IKMV ducts is apparent in 20X images with calibration bars (150 μm). Multiple measurements of duct area across samples are quantified at right (n = 3 control, n = 3 IKMV glands, total of 65 individual ducts were measured; *** p < 0.001). c Double transgenic IKMV virgin females were kept on normal water at the 6 week virgin time point and collected 3 days later along with the dox-treated cohort. Images of H&E stained mammary tissue show ducts of untreated controls have normal morphology, with no lumen-filling or hyperplastic growth (10X magnification at left, 20X at right)

Mentions: In our transplant studies, outgrowth of the mammary ducts and NF-κB activation had been simultaneous, starting when the hosts were 3 weeks of age. In order to better model early tumorigenesis without the overlay of developmental abnormalities, we induced NF-κB signaling after a subset of normal ductal structures had already formed. To do this, we took 6 week old virgin, intact IKMV and control females and dox-treated them for 3 days prior to collection. Surprisingly, we found that after this short pulse of transgene induction, striking changes had occurred throughout the IKMV ductal structure. The lumens of the IKMV ducts were completely filled with cells and the ducts were significantly enlarged (Fig. 3a,b). This phenotype is fully penetrant and occurs in 100 % of the ducts throughout the IKMV glands. As an added control, non-dox treated, double transgenic IKMV females were collected at the same 6 week old, virgin time-point. Mammary tissue from these untreated controls appeared normal, with no lumen-filling or hyperplastic ducts (Fig. 3c). This confirmed that the phenotype in the dox-treated IKMV mice occurred within the 3 day induction window.Fig. 3


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)

Short term activation of NF-κB in mammary epithelium leads to ducts with filled lumens. Intact 6 week old virgin IKMV and control littermates were dox-treated (2 g/L) for 3 days prior to sacrifice. a Haematoxylin stained whole mounts of control and IKMV glands reveal changes in IKMV ducts. In H&E stained sections (below), we observed a complete occlusion of IKMV ducts throughout the gland. b Increased size of individual IKMV ducts is apparent in 20X images with calibration bars (150 μm). Multiple measurements of duct area across samples are quantified at right (n = 3 control, n = 3 IKMV glands, total of 65 individual ducts were measured; *** p < 0.001). c Double transgenic IKMV virgin females were kept on normal water at the 6 week virgin time point and collected 3 days later along with the dox-treated cohort. Images of H&E stained mammary tissue show ducts of untreated controls have normal morphology, with no lumen-filling or hyperplastic growth (10X magnification at left, 20X at right)
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Related In: Results  -  Collection

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Fig3: Short term activation of NF-κB in mammary epithelium leads to ducts with filled lumens. Intact 6 week old virgin IKMV and control littermates were dox-treated (2 g/L) for 3 days prior to sacrifice. a Haematoxylin stained whole mounts of control and IKMV glands reveal changes in IKMV ducts. In H&E stained sections (below), we observed a complete occlusion of IKMV ducts throughout the gland. b Increased size of individual IKMV ducts is apparent in 20X images with calibration bars (150 μm). Multiple measurements of duct area across samples are quantified at right (n = 3 control, n = 3 IKMV glands, total of 65 individual ducts were measured; *** p < 0.001). c Double transgenic IKMV virgin females were kept on normal water at the 6 week virgin time point and collected 3 days later along with the dox-treated cohort. Images of H&E stained mammary tissue show ducts of untreated controls have normal morphology, with no lumen-filling or hyperplastic growth (10X magnification at left, 20X at right)
Mentions: In our transplant studies, outgrowth of the mammary ducts and NF-κB activation had been simultaneous, starting when the hosts were 3 weeks of age. In order to better model early tumorigenesis without the overlay of developmental abnormalities, we induced NF-κB signaling after a subset of normal ductal structures had already formed. To do this, we took 6 week old virgin, intact IKMV and control females and dox-treated them for 3 days prior to collection. Surprisingly, we found that after this short pulse of transgene induction, striking changes had occurred throughout the IKMV ductal structure. The lumens of the IKMV ducts were completely filled with cells and the ducts were significantly enlarged (Fig. 3a,b). This phenotype is fully penetrant and occurs in 100 % of the ducts throughout the IKMV glands. As an added control, non-dox treated, double transgenic IKMV females were collected at the same 6 week old, virgin time-point. Mammary tissue from these untreated controls appeared normal, with no lumen-filling or hyperplastic ducts (Fig. 3c). This confirmed that the phenotype in the dox-treated IKMV mice occurred within the 3 day induction window.Fig. 3

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