A mouse model for Luminal epithelial like ER positive subtype of human breast cancer

<p>Abstract</p> <p>Background</p> <p>Generation of novel spontaneous ER positive mammary tumor animal model from heterozygous NIH nude mice.</p> <p>Methods</p> <p>Using brother-sister mating with pedigree expansion system, we derived a colony of heterozygous breeding females showing ER-Positive tumors around the age of 6 months. Complete blood picture, differential leukocyte count, and serum levels of Estrogen, Alanine amino transferase (SGPT), Aspartate amino transferase (SGOT), total protein and albumin were estimated. Aspiration biopsies and microbiology were carried out. Gross pathology of the tumors and their metastatic potential were assessed. The tumors were excised and further characterized using histopathology, cytology, electron microscopy (EM), molecular markers and Mouse mammary Tumor Virus – Long Terminal Repeats (MMTV LTR) specific RT-PCR.</p> <p>Results</p> <p>The tumors originated from 2^ndor 5^thor both the mammary glands and were multi-nodulated with variable central necrosis accompanied with an accumulation of inflammatory exudate. Significant increases in estrogen, SGPT, SGOT and neutrophils levels were noticed. Histopathologically, invasive nodular masses of pleomorphic tubular neoplastic epithelial cells invaded fibro-vascular stroma, adjacent dermis and subcutaneous tissue. Metastatic spread through hematogenous and regional lymph nodes, into liver, lungs, spleen, heart and dermal lymphatics was observed. EM picture revealed no viral particles and MMTV-negativity was confirmed through MMTV LTR-specific RT-PCR. High expression of ER α, moderate to high expression of proliferating cell nuclear antigen (PCNA), moderate expression of vimentin and Cytokeratin 19 (K19) and low expression of p53 were observed in tumor sections, when compared with that of the normal mammary gland.</p> <p>Conclusion</p> <p>Since 75% of human breast cancer were classified ER-positive and as our model mimics (in most of the characteristics, such as histopathology, metastasis, high estrogen levels) the ER-positive luminal epithelial-like human breast cancer, this model will be an attractive tool to understand the biology of estrogen-dependant breast cancer in women. To our knowledge, this is the first report of a spontaneous mammary model displaying regional lymph node involvement with both hematogenous and lymphatic spread to liver, lung, heart, spleen and lymph nodes.</p

A mouse model for Luminal epithelial like ER positive subtype of human breast cancer-7

<p><b>Copyright information:</b></p><p>Taken from "A mouse model for Luminal epithelial like ER positive subtype of human breast cancer"</p><p>http://www.biomedcentral.com/1471-2407/7/180</p><p>BMC Cancer 2007;7():180-180.</p><p>Published online 20 Sep 2007</p><p>PMCID:PMC2094712.</p><p></p>7 and C3H mice (426 bp); 6 & 7 – RNA from c57 and c3H mice; 8 & 9 – CDNA from tumor sample with β actin primers (432 bp)

A mouse model for Luminal epithelial like ER positive subtype of human breast cancer-1

<p><b>Copyright information:</b></p><p>Taken from "A mouse model for Luminal epithelial like ER positive subtype of human breast cancer"</p><p>http://www.biomedcentral.com/1471-2407/7/180</p><p>BMC Cancer 2007;7():180-180.</p><p>Published online 20 Sep 2007</p><p>PMCID:PMC2094712.</p><p></p>zed cluster with loosely cohesive round cells with hyper chromatic nucleus. C&D. A Large cluster with very loosely cohesive signet ring cells with eccentric, hyperchromatic, pleomorphic nuclei. E&F A large cluster with loosely cohesive round to polygonal foamy cells with hyperchromatic nuclei. G. Giant-sized foamy cells with eccentric nuclei. H. Giant binucleated foamy cell. Magnification (Giemsa, × 100)

A mouse model for Luminal epithelial like ER positive subtype of human breast cancer-4

<p><b>Copyright information:</b></p><p>Taken from "A mouse model for Luminal epithelial like ER positive subtype of human breast cancer"</p><p>http://www.biomedcentral.com/1471-2407/7/180</p><p>BMC Cancer 2007;7():180-180.</p><p>Published online 20 Sep 2007</p><p>PMCID:PMC2094712.</p><p></p>ary with well differentiated secretory glands (1-H&E, ×100 ; 2- H&E, × 200).3 & 4. Metastatic foci in liver. (arrow)- 3 -H&E, ×200 ; 4- H&E, × 400).5 & 6. Metastatic nodules growing on the vascular endothelium of aorta (5-H&E, ×100 ; 6- H&E, × 200). 7 & 8 Sebaceous glands showing pleomorphism, moderate differentiation and loss of polarity (arrow) (7-H&E, ×200 ; 8- H&E, × 200)

A mouse model for Luminal epithelial like ER positive subtype of human breast cancer-3

<p><b>Copyright information:</b></p><p>Taken from "A mouse model for Luminal epithelial like ER positive subtype of human breast cancer"</p><p>http://www.biomedcentral.com/1471-2407/7/180</p><p>BMC Cancer 2007;7():180-180.</p><p>Published online 20 Sep 2007</p><p>PMCID:PMC2094712.</p><p></p>layers of pleomorphic epithelial cells. (arrow) (A-H&E, ×200 ; B- H&E, × 400). C. Lobules separated by stroma (arrow). H&E, ×100 D.A lobule surrounded by stoma (arrow). H&E, ×200. E&F. Tumor mass pushing the adjacent dermis, H&E, ×200.G&H. Neutrophils invading the necrosed areas in the tumor mass (arrow). H&E, ×200. I&J. Neoplastic epithelial cells with hyperchromatic nucleus invading the underlying muscle layers (arrow)(I-H&E, ×100; J- H&E, × 200)

A mouse model for Luminal epithelial like ER positive subtype of human breast cancer-5

<p><b>Copyright information:</b></p><p>Taken from "A mouse model for Luminal epithelial like ER positive subtype of human breast cancer"</p><p>http://www.biomedcentral.com/1471-2407/7/180</p><p>BMC Cancer 2007;7():180-180.</p><p>Published online 20 Sep 2007</p><p>PMCID:PMC2094712.</p><p></p>ke particles detected. Magnification × 6000

Intensity of Greenfluorescence indicates the expression level of the correspondingmolecular markers

<p><b>Copyright information:</b></p><p>Taken from "A mouse model for Luminal epithelial like ER positive subtype of human breast cancer"</p><p>http://www.biomedcentral.com/1471-2407/7/180</p><p>BMC Cancer 2007;7():180-180.</p><p>Published online 20 Sep 2007</p><p>PMCID:PMC2094712.</p><p></p> A, B, C – Normal mammary gland section of respectivemarker; D, E, F – Tumor section of respective marker. Magnification ×1000. A – FITC alone; B – PI alone; C – Dual (FITC & PI). D -FITC alone; E – PI alone; F – Dual (FITC & PI). ER: Higher expression inneoplastic epithelial cells (F) than normal controls(C). P53: Lowerexpression in neoplastic epithelial cells (F) than normal controls C. PCNA: Moderate to higher expression in neoplastic epithelial cells (F) than normal controls(C). K19: Moderate expression in neoplastic epithelial cells (F) than normal controls(C). Vimentin: High expression of vimentin in the stromal cells (F) than normal controls (C)