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Transformation of enriched mammary cell populations with polyomavirus middle T antigen influences tumor subtype and metastatic potential.

Drobysheva D, Smith BA, McDowell M, Guillen KP, Ekiz HA, Welm BE - Breast Cancer Res. (2015)

Bottom Line: Breast cancer exhibits significant molecular, histological, and pathological diversity.In the present study, we assessed the molecular, histological, and metastatic outcomes in distinct mammary cell populations transformed with the PyMT gene.The data demonstrate that luminal CD133+ cells give rise to less metastatic tumors, luminal CD133- cells preferentially establish basal tumors, and the cell of origin for squamous metaplasia likely resides in the basal and stem cell populations.

View Article: PubMed Central - PubMed

Affiliation: Department of Oncological Sciences, University of Utah, 315 South 1400 East, Salt Lake City, UT, 84112, USA. daria.drobysheva@hci.utah.edu.

ABSTRACT

Introduction: Breast cancer exhibits significant molecular, histological, and pathological diversity. Factors that impact this heterogeneity are poorly understood; however, transformation of distinct normal cell populations of the breast may generate different tumor phenotypes. Our previous study demonstrated that the polyomavirus middle T antigen (PyMT) oncogene can establish diverse tumor subtypes when broadly expressed within mouse mammary epithelial cells. In the present study, we assessed the molecular, histological, and metastatic outcomes in distinct mammary cell populations transformed with the PyMT gene.

Methods: Isolated mouse mammary epithelial cells were transduced with a lentivirus encoding PyMT during an overnight infection and then sorted into hormone receptor-positive luminal (CD133+), hormone receptor-negative luminal (CD133-), basal, and stem cell populations using the cell surface markers CD24, CD49f, and CD133. Each population was subsequently transplanted into syngeneic cleared mouse mammary fat pads to generate tumors. Tumors were classified by histology, estrogen receptor status, molecular subtype, and metastatic potential to investigate whether transformation of different enriched populations affects tumor phenotype.

Results: Although enriched mammary epithelial cell populations showed no difference in either the ability to form tumors or tumor latency, differences in prevalence of solid adenocarcinomas and squamous, papillary, and sebaceous-like tumors were observed. In particular, squamous metaplasia was observed more frequently in tumors derived from basal and stem cells than in luminal cells. Interestingly, both molecularly basal and luminal tumors developed from luminal CD133+, basal, and stem cell populations; however, luminal CD133- cells gave rise exclusively to molecularly basal tumors. Tumors arising from the luminal CD133-, basal, and stem cell populations were highly metastatic; however, luminal CD133+ cells generated tumors that were significantly less metastatic, possibly due to an inability of these tumor cells to escape the primary tumor site.

Conclusions: Expression of PyMT within different mammary cell populations influences tumor histology, molecular subtype, and metastatic potential. The data demonstrate that luminal CD133+ cells give rise to less metastatic tumors, luminal CD133- cells preferentially establish basal tumors, and the cell of origin for squamous metaplasia likely resides in the basal and stem cell populations.

No MeSH data available.


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Analysis and prevalence of histology in tumors derived from mammary epithelial cell (MEC) populations. a through f Representative images of hematoxylin and eosin and cytokeratin staining of tumor histologies: acinar (a), papillary (b), solid adenocarcinoma (c), squamous (d), lipid rich (e), and sebaceous-like (f). Immunofluorescence staining was performed for basal keratin 14 (K14; red) and luminal keratin 8 (K8; green) (scale bar = 100 μm). ZsGreen fluorescence was not detected in the processed sections. Histological area per tumor was derived from luminal CD133+ cells (g), luminal CD133− cells (h), basal cells (i), and stem cells (j). Boxes above each column indicate tumors that were used for microarray analysis. Red boxes = basal subgroup; green boxes = luminal subgroup. Black circles mark tumors that were metastatic. k Average area of histology per MEC group (unpaired t test; n = number of tumors). l Representative images of estrogen receptor (ESR1) staining, including negative (left panel) and positive staining (right panel) (scale bar = 50 μm; n = number of tumors). m Quantification of ESR1 staining per MEC group (two proportion z test). n Quantification of ESR1 staining per histological specimen (two proportion z test). *p < 0.05, **p < 0.01, ***p < 0.0005, ****p < 0.0001
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Fig2: Analysis and prevalence of histology in tumors derived from mammary epithelial cell (MEC) populations. a through f Representative images of hematoxylin and eosin and cytokeratin staining of tumor histologies: acinar (a), papillary (b), solid adenocarcinoma (c), squamous (d), lipid rich (e), and sebaceous-like (f). Immunofluorescence staining was performed for basal keratin 14 (K14; red) and luminal keratin 8 (K8; green) (scale bar = 100 μm). ZsGreen fluorescence was not detected in the processed sections. Histological area per tumor was derived from luminal CD133+ cells (g), luminal CD133− cells (h), basal cells (i), and stem cells (j). Boxes above each column indicate tumors that were used for microarray analysis. Red boxes = basal subgroup; green boxes = luminal subgroup. Black circles mark tumors that were metastatic. k Average area of histology per MEC group (unpaired t test; n = number of tumors). l Representative images of estrogen receptor (ESR1) staining, including negative (left panel) and positive staining (right panel) (scale bar = 50 μm; n = number of tumors). m Quantification of ESR1 staining per MEC group (two proportion z test). n Quantification of ESR1 staining per histological specimen (two proportion z test). *p < 0.05, **p < 0.01, ***p < 0.0005, ****p < 0.0001

Mentions: We next analyzed the histology of tumors originating from each of the enriched MEC populations. We classified tumors by H&E staining and cytokeratin expression and identified the following histologies: acinar, papillary, solid adenocarcinoma, squamous, lipid-rich, and sebaceous-like (Fig. 2a–f, Table 1). The frequency of a specific histology was quantified by estimating its area in two or three different sections per tumor (Fig. 2g–k). Data are presented as the total percentage area of a histological feature in each tumor (Fig. 2g–k) and as the predominant tumor histology of each tumor (Additional file 4). Tumors that produced lung metastases and those used for microarray analysis are also indicated.Fig. 2


Transformation of enriched mammary cell populations with polyomavirus middle T antigen influences tumor subtype and metastatic potential.

Drobysheva D, Smith BA, McDowell M, Guillen KP, Ekiz HA, Welm BE - Breast Cancer Res. (2015)

Analysis and prevalence of histology in tumors derived from mammary epithelial cell (MEC) populations. a through f Representative images of hematoxylin and eosin and cytokeratin staining of tumor histologies: acinar (a), papillary (b), solid adenocarcinoma (c), squamous (d), lipid rich (e), and sebaceous-like (f). Immunofluorescence staining was performed for basal keratin 14 (K14; red) and luminal keratin 8 (K8; green) (scale bar = 100 μm). ZsGreen fluorescence was not detected in the processed sections. Histological area per tumor was derived from luminal CD133+ cells (g), luminal CD133− cells (h), basal cells (i), and stem cells (j). Boxes above each column indicate tumors that were used for microarray analysis. Red boxes = basal subgroup; green boxes = luminal subgroup. Black circles mark tumors that were metastatic. k Average area of histology per MEC group (unpaired t test; n = number of tumors). l Representative images of estrogen receptor (ESR1) staining, including negative (left panel) and positive staining (right panel) (scale bar = 50 μm; n = number of tumors). m Quantification of ESR1 staining per MEC group (two proportion z test). n Quantification of ESR1 staining per histological specimen (two proportion z test). *p < 0.05, **p < 0.01, ***p < 0.0005, ****p < 0.0001
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Fig2: Analysis and prevalence of histology in tumors derived from mammary epithelial cell (MEC) populations. a through f Representative images of hematoxylin and eosin and cytokeratin staining of tumor histologies: acinar (a), papillary (b), solid adenocarcinoma (c), squamous (d), lipid rich (e), and sebaceous-like (f). Immunofluorescence staining was performed for basal keratin 14 (K14; red) and luminal keratin 8 (K8; green) (scale bar = 100 μm). ZsGreen fluorescence was not detected in the processed sections. Histological area per tumor was derived from luminal CD133+ cells (g), luminal CD133− cells (h), basal cells (i), and stem cells (j). Boxes above each column indicate tumors that were used for microarray analysis. Red boxes = basal subgroup; green boxes = luminal subgroup. Black circles mark tumors that were metastatic. k Average area of histology per MEC group (unpaired t test; n = number of tumors). l Representative images of estrogen receptor (ESR1) staining, including negative (left panel) and positive staining (right panel) (scale bar = 50 μm; n = number of tumors). m Quantification of ESR1 staining per MEC group (two proportion z test). n Quantification of ESR1 staining per histological specimen (two proportion z test). *p < 0.05, **p < 0.01, ***p < 0.0005, ****p < 0.0001
Mentions: We next analyzed the histology of tumors originating from each of the enriched MEC populations. We classified tumors by H&E staining and cytokeratin expression and identified the following histologies: acinar, papillary, solid adenocarcinoma, squamous, lipid-rich, and sebaceous-like (Fig. 2a–f, Table 1). The frequency of a specific histology was quantified by estimating its area in two or three different sections per tumor (Fig. 2g–k). Data are presented as the total percentage area of a histological feature in each tumor (Fig. 2g–k) and as the predominant tumor histology of each tumor (Additional file 4). Tumors that produced lung metastases and those used for microarray analysis are also indicated.Fig. 2

Bottom Line: Breast cancer exhibits significant molecular, histological, and pathological diversity.In the present study, we assessed the molecular, histological, and metastatic outcomes in distinct mammary cell populations transformed with the PyMT gene.The data demonstrate that luminal CD133+ cells give rise to less metastatic tumors, luminal CD133- cells preferentially establish basal tumors, and the cell of origin for squamous metaplasia likely resides in the basal and stem cell populations.

View Article: PubMed Central - PubMed

Affiliation: Department of Oncological Sciences, University of Utah, 315 South 1400 East, Salt Lake City, UT, 84112, USA. daria.drobysheva@hci.utah.edu.

ABSTRACT

Introduction: Breast cancer exhibits significant molecular, histological, and pathological diversity. Factors that impact this heterogeneity are poorly understood; however, transformation of distinct normal cell populations of the breast may generate different tumor phenotypes. Our previous study demonstrated that the polyomavirus middle T antigen (PyMT) oncogene can establish diverse tumor subtypes when broadly expressed within mouse mammary epithelial cells. In the present study, we assessed the molecular, histological, and metastatic outcomes in distinct mammary cell populations transformed with the PyMT gene.

Methods: Isolated mouse mammary epithelial cells were transduced with a lentivirus encoding PyMT during an overnight infection and then sorted into hormone receptor-positive luminal (CD133+), hormone receptor-negative luminal (CD133-), basal, and stem cell populations using the cell surface markers CD24, CD49f, and CD133. Each population was subsequently transplanted into syngeneic cleared mouse mammary fat pads to generate tumors. Tumors were classified by histology, estrogen receptor status, molecular subtype, and metastatic potential to investigate whether transformation of different enriched populations affects tumor phenotype.

Results: Although enriched mammary epithelial cell populations showed no difference in either the ability to form tumors or tumor latency, differences in prevalence of solid adenocarcinomas and squamous, papillary, and sebaceous-like tumors were observed. In particular, squamous metaplasia was observed more frequently in tumors derived from basal and stem cells than in luminal cells. Interestingly, both molecularly basal and luminal tumors developed from luminal CD133+, basal, and stem cell populations; however, luminal CD133- cells gave rise exclusively to molecularly basal tumors. Tumors arising from the luminal CD133-, basal, and stem cell populations were highly metastatic; however, luminal CD133+ cells generated tumors that were significantly less metastatic, possibly due to an inability of these tumor cells to escape the primary tumor site.

Conclusions: Expression of PyMT within different mammary cell populations influences tumor histology, molecular subtype, and metastatic potential. The data demonstrate that luminal CD133+ cells give rise to less metastatic tumors, luminal CD133- cells preferentially establish basal tumors, and the cell of origin for squamous metaplasia likely resides in the basal and stem cell populations.

No MeSH data available.


Related in: MedlinePlus