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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.


Related in: MedlinePlus

Metastatic profiles of tumors generated from enriched mammary epithelial cell populations. a Representative bright-field (left panel) and fluorescent (right panel) images of the same lung. Arrowheads indicate metastases (scale bar = 1 mm). b Representative image of hematoxylin and eosin staining of a metastatic lung section. Arrows indicate metastases (scale bar = 1 mm). c Percentage of mice with lung metastases per tumor group. Luminal CD133+ cell tumors were less metastatic than the other tumor groups (two proportion z test; n = number of mice). d Number of metastatic lung foci per tumor group. Luminal CD133+ cell tumors generated fewer metastatic foci than the other tumor groups (Mann–Whitney U test; median values shown). e Quantification of metastasis area per unique metastatic site in serial lung sections. No difference in size of tumor metastasis was detected between the tumor groups (n = number of mice). f Normalized number of circulating tumor cells in mice with luminal CD133+ tumors compared with all other tumor groups. ZsGreen signaling in whole blood isolated from tumor bearing mice was analyzed by fluorescence-activated cell sorting and normalized to no-tumor control signal. Luminal CD133+ tumor-bearing mice had fewer circulating tumor cells. Mice with non-metastatic tumors are represented by green, and those with metastatic tumors are represented by black (unpaired t test; mean values shown; n = number of mice). g Quantification of the number of lung tumor foci per tail vein injection of metastatic luminal CD133+ tumor cells (tumor 1), non-metastatic luminal CD133+ tumor cells (tumor 2), or metastatic luminal CD133− tumor cells (tumors 3 and 4) (unpaired t test; mean values shown; n = number of mice). Data shown in (a)–(e) represent spontaneous metastasis occurring from primary tumors, and data shown in (f) are from non-spontaneous tail vein injection assays. *p < 0.05, **p < 0.01, ***p < 0.0005, ****p < 0.0001
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Fig4: Metastatic profiles of tumors generated from enriched mammary epithelial cell populations. a Representative bright-field (left panel) and fluorescent (right panel) images of the same lung. Arrowheads indicate metastases (scale bar = 1 mm). b Representative image of hematoxylin and eosin staining of a metastatic lung section. Arrows indicate metastases (scale bar = 1 mm). c Percentage of mice with lung metastases per tumor group. Luminal CD133+ cell tumors were less metastatic than the other tumor groups (two proportion z test; n = number of mice). d Number of metastatic lung foci per tumor group. Luminal CD133+ cell tumors generated fewer metastatic foci than the other tumor groups (Mann–Whitney U test; median values shown). e Quantification of metastasis area per unique metastatic site in serial lung sections. No difference in size of tumor metastasis was detected between the tumor groups (n = number of mice). f Normalized number of circulating tumor cells in mice with luminal CD133+ tumors compared with all other tumor groups. ZsGreen signaling in whole blood isolated from tumor bearing mice was analyzed by fluorescence-activated cell sorting and normalized to no-tumor control signal. Luminal CD133+ tumor-bearing mice had fewer circulating tumor cells. Mice with non-metastatic tumors are represented by green, and those with metastatic tumors are represented by black (unpaired t test; mean values shown; n = number of mice). g Quantification of the number of lung tumor foci per tail vein injection of metastatic luminal CD133+ tumor cells (tumor 1), non-metastatic luminal CD133+ tumor cells (tumor 2), or metastatic luminal CD133− tumor cells (tumors 3 and 4) (unpaired t test; mean values shown; n = number of mice). Data shown in (a)–(e) represent spontaneous metastasis occurring from primary tumors, and data shown in (f) are from non-spontaneous tail vein injection assays. *p < 0.05, **p < 0.01, ***p < 0.0005, ****p < 0.0001

Mentions: We investigated whether the enriched MEC populations expressing PyMT could generate tumors with different metastatic capacities. Metastasis was measured in mice with similar tumor latency, tumor size (2 cm), and tumor burden (single tumor). Similar to other PyMT-driven models, primary tumors generated from each MEC population metastasized to the lungs (Fig. 4a, b) [16]. Metastases to other organs were not detected. The metastatic burden in lungs was quantified by whole mount fluorescent imaging and H&E staining of serial lung sections from mice with similar tumor size and latency. Interestingly, although no significant differences in tumor prevalence or progression were observed between the four tumor-initiating populations (Fig. 1d), tumors derived from the luminal CD133+ cell population were significantly less metastatic than all other tumor groups (Fig. 4c). Furthermore, these cells formed significantly fewer lung tumor foci than the other tumor groups (Fig. 4d); however, there was no difference in the average area per metastatic focus (Fig. 4e).Fig. 4


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)

Metastatic profiles of tumors generated from enriched mammary epithelial cell populations. a Representative bright-field (left panel) and fluorescent (right panel) images of the same lung. Arrowheads indicate metastases (scale bar = 1 mm). b Representative image of hematoxylin and eosin staining of a metastatic lung section. Arrows indicate metastases (scale bar = 1 mm). c Percentage of mice with lung metastases per tumor group. Luminal CD133+ cell tumors were less metastatic than the other tumor groups (two proportion z test; n = number of mice). d Number of metastatic lung foci per tumor group. Luminal CD133+ cell tumors generated fewer metastatic foci than the other tumor groups (Mann–Whitney U test; median values shown). e Quantification of metastasis area per unique metastatic site in serial lung sections. No difference in size of tumor metastasis was detected between the tumor groups (n = number of mice). f Normalized number of circulating tumor cells in mice with luminal CD133+ tumors compared with all other tumor groups. ZsGreen signaling in whole blood isolated from tumor bearing mice was analyzed by fluorescence-activated cell sorting and normalized to no-tumor control signal. Luminal CD133+ tumor-bearing mice had fewer circulating tumor cells. Mice with non-metastatic tumors are represented by green, and those with metastatic tumors are represented by black (unpaired t test; mean values shown; n = number of mice). g Quantification of the number of lung tumor foci per tail vein injection of metastatic luminal CD133+ tumor cells (tumor 1), non-metastatic luminal CD133+ tumor cells (tumor 2), or metastatic luminal CD133− tumor cells (tumors 3 and 4) (unpaired t test; mean values shown; n = number of mice). Data shown in (a)–(e) represent spontaneous metastasis occurring from primary tumors, and data shown in (f) are from non-spontaneous tail vein injection assays. *p < 0.05, **p < 0.01, ***p < 0.0005, ****p < 0.0001
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4589945&req=5

Fig4: Metastatic profiles of tumors generated from enriched mammary epithelial cell populations. a Representative bright-field (left panel) and fluorescent (right panel) images of the same lung. Arrowheads indicate metastases (scale bar = 1 mm). b Representative image of hematoxylin and eosin staining of a metastatic lung section. Arrows indicate metastases (scale bar = 1 mm). c Percentage of mice with lung metastases per tumor group. Luminal CD133+ cell tumors were less metastatic than the other tumor groups (two proportion z test; n = number of mice). d Number of metastatic lung foci per tumor group. Luminal CD133+ cell tumors generated fewer metastatic foci than the other tumor groups (Mann–Whitney U test; median values shown). e Quantification of metastasis area per unique metastatic site in serial lung sections. No difference in size of tumor metastasis was detected between the tumor groups (n = number of mice). f Normalized number of circulating tumor cells in mice with luminal CD133+ tumors compared with all other tumor groups. ZsGreen signaling in whole blood isolated from tumor bearing mice was analyzed by fluorescence-activated cell sorting and normalized to no-tumor control signal. Luminal CD133+ tumor-bearing mice had fewer circulating tumor cells. Mice with non-metastatic tumors are represented by green, and those with metastatic tumors are represented by black (unpaired t test; mean values shown; n = number of mice). g Quantification of the number of lung tumor foci per tail vein injection of metastatic luminal CD133+ tumor cells (tumor 1), non-metastatic luminal CD133+ tumor cells (tumor 2), or metastatic luminal CD133− tumor cells (tumors 3 and 4) (unpaired t test; mean values shown; n = number of mice). Data shown in (a)–(e) represent spontaneous metastasis occurring from primary tumors, and data shown in (f) are from non-spontaneous tail vein injection assays. *p < 0.05, **p < 0.01, ***p < 0.0005, ****p < 0.0001
Mentions: We investigated whether the enriched MEC populations expressing PyMT could generate tumors with different metastatic capacities. Metastasis was measured in mice with similar tumor latency, tumor size (2 cm), and tumor burden (single tumor). Similar to other PyMT-driven models, primary tumors generated from each MEC population metastasized to the lungs (Fig. 4a, b) [16]. Metastases to other organs were not detected. The metastatic burden in lungs was quantified by whole mount fluorescent imaging and H&E staining of serial lung sections from mice with similar tumor size and latency. Interestingly, although no significant differences in tumor prevalence or progression were observed between the four tumor-initiating populations (Fig. 1d), tumors derived from the luminal CD133+ cell population were significantly less metastatic than all other tumor groups (Fig. 4c). Furthermore, these cells formed significantly fewer lung tumor foci than the other tumor groups (Fig. 4d); however, there was no difference in the average area per metastatic focus (Fig. 4e).Fig. 4

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