Accelerated Preclinical Testing Using Transplanted Tumors from Genetically Engineered Mouse Breast Cancer Models

Abstract

Purpose: The use of genetically engineered mouse (GEM) models for preclinical testing of anticancer therapies is hampered by variable tumor latency, incomplete penetrance, and complicated breeding schemes. Here, we describe and validate a transplantation strategy that circumvents some of these difficulties. Experimental Design: Tumor fragments from tumor-bearing MMTV-PyMTor cell suspensions from MMTV-PyMT, -Her2/neu, -wnt1, -wnt1/p53 +/À , BRCA1/p53, and C3(1)T-Ag mice were transplanted into the mammary fat pad or s.c. into naI« ve syngeneic or immunosuppressed mice. Tumor development was monitored and tissues were processed for histopathology and gene expression profiling. Metastasis was scored 60 days after the removal of transplanted tumors. Results: PyMT tumor fragments and cell suspensions from anterior glands grew faster than posterior tumors in serial passages regardless of the site of implantation. Microarray analysis revealed genetic differences between these tumors. The transplantation was reproducible using anterior tumors from multiple GEM, and tumor growth rate correlated with the number of transplanted cells. Similar morphologic appearances were observed in original and transplanted tumors. Metastasis developed in >90% of mice transplanted with PyMT, 40% with BRCA1/ p53 +/À and wnt1/p53 +/À , and 15% with Her2/neu tumors. Expansion of PyMTand wnt1tumors by serial transplantation for two passages did not lead to significant changes in gene expression. PyMT-transplanted tumors and anterior tumors of transgenic mice showed similar sensitivities to cyclophosphamide and paclitaxel. Conclusions: Transplantation of GEM tumors can provide a large cohort of mice bearing mammary tumors at the same stage of tumor development and with defined frequency of metastasis in a well-characterized molecular and genetic background.

Molecular characterisation of side population cells with cancer stem cell-like characteristics in small-cell lung cancer

“…The differences with reports from solid tumours were attributed to use of a syngeneic model. However, studies comparing tumour growth rates of cells from transgenic Wnt1 mouse mammary tumours implanted into syngeneic, nude or SCID mice did not show appreciative differences (Varticovski et al, 2007;Svirshchevskaya et al, 2008). Thus, the high capacity of tumour reconstitution using haematopoietic tumour cells may be an intrinsic feature of haematopoietic malignancies.…”

“…Tumour growth was measured biweekly and the weights (in milligrams) were calculated using the formula for a prolate ellipsoid and assuming a specific gravity of 1.0 g cm À3 using the formula L Â W 2 Â 0.5 (Plowman et al, 1997). For isolation of cells from xenografts, freshly isolated tumours were made into single-cell suspension as described (Varticovski et al, 2007).…”

IGF1 dependence of dietary energy balance effects on murine Met1 mammary tumor progression, epithelial-to-mesenchymal transition, and chemokine expression

“…Mice were individually housed with free access to water and exposed to a 12 h light:12 h darkness cycle and allowed to acclimate for 1 week before syngeneic orthotopic transplantation of Wnt1 mammary tumor brei, as previously described (Nunez et al 2008). In brief, a suspension of MMTV-Wnt1 mammary tumor cells was derived (Varticovski et al 2007) from six spontaneously developed mammary carcinomas in MMTV-Wnt1 FVB/NJ (002934; Jackson Laboratory, Bar Harbor, ME, USA, http:// www.jax.org). MMTV-Wnt1 FVB/NJ mice were euthanized with CO 2 , and tumors were collected aseptically using blunt dissection, trimmed of extraneous tissues, mechanically dissociated by mincing and passage through a 40-micron mesh sterile screen, and suspended in serumfree RPMI 1640 (Quality Biological, Gaithersburg, MD, USA).…”

Genetically Engineered Mouse Models in Preclinical Anti-Cancer Drug Development

“…Like most of the other "first generation" transgenic oncomice, many of these models have a low tumor penetrance and widely variable latency period, making them difficult to use directly in large scale preclinical drug screenings. These limitations are partially overcome by resecting and transplanting transgenically induced tumors into many syngeneic recipient animals, generating a large cohort of tumor-bearing animals for drugscreening purposes (Maglione et al, 2004;Varticovski et al, 2007).…”