Development of Novel Informative Preclinical Animal Models - CAPR Infrastructure

Division Of Basic Sciences - Nci

Investigators

Linked publications, trials & patents

Abstract

We have developed and characterized multiple GEM, GEM-derived allograft (GDA), and since recently patient-derived (PDX) murine models for diverse cancer indications for subsequent applications towards preclinical biomarker and therapeutic development. In addition, responding to growing preclinical needs and supporting collaborative activities initiated by CCR clinical investigators, CAPR specialists also recently embarked on a mission to establish several patient-derived xenograft models (PDX), to be employed for therapeutic discovery in oligo-proliferative lung cancer cases. On the path of building a state-of-art portfolio of preclinical models, CAPR major recent accomplishments include: 1. CAPR successfully generated multiple oncogenic driver-specific GEM and GDA metastatic human-relevant SEOC models along with multiple cell cultures for each Inducible models that have been shown to develop SEOC that resembles the human disease in both molecular and biological properties. To expand CAPR selection of ovarian carcinoma models, novel models have been assembled in which epithelial cells in murine oviduct structure (that is anatomically equivalent to a human fallopian tube) are genetically programmed to give rise to SEOC carcinogenesis thus representing a current paradigm that the secretory cells of human fallopian tubes represent the cell of origin for SEOC cancer. This project, in collaboration with and supported by the Division of Cancer Prevention (Dr. Robert Shoemaker's laboratory) pursues an ultimate objective of exploring these novel ovarian cancer models for biomarker and molecular aspects of disease evaluation, interrogating specific cancer signaling pathway vulnerabilities and corresponding drug targets and eventually use of these models in preclinical drug development workflows. 2. CAPR scientists established and characterized a novel genetic model for non-gestational choriocarcinoma (NGCO) - an unmet need rare clinical malignancy generally with poor prognosis. GEM mouse model for choriocarcinoma features inducible alterations in Brca2, Trp53, and pRb loci and develop with high penetrance (47%) the NGCO malignancy characterized by cellular features such as high presence of cytotrophoblasts and syncytiotrophoblasts, as well as expression of chorionic gonadotropin biomarker. This novel model for NGCO malignancy will provide an informative preclinical platform for mechanistic disease evaluation, establishing disease endpoints, developing imaging and other diagnostic options, as well as evaluating novel treatment strategies towards improving clinical outcomes in patients suffering from choriocarcinoma. 3. Multiple early passage cell cultures have been established from both primary and metastatic site pancreatic adenocarcinoma lesions developing in the so called KPC GEM model (established by Drs. Tuveson and Hingorani). These cells, when transplanted orthotopically into the pancreas of recipient immunocompetent mice, develop metastatic pancreatic adenocarcinomas with complete set of characteristics typical for the parental tumor. These models have the highest metastatic rate of any GEM PDAC model reported thus far. 4. We have completed the construction and extensively validated three novel GEM strains for the most common p53 missense mutations identified in human cancer cases (R172H, R270H, and R270C). Pancreatic Ductal Adenocarcinoma (PDAC) models harboring these p53 alleles have been generated by inter-crossing these alleles with mice harboring the inducible RasG12D allele and PDX-Cre activating transgene. Mice harboring the common p53-172 mutant have been characterized and shown to develop PDAC with properties similar to the KPC model. We are investigating at present molecular differences and pathway variabilities among these novel PDAC models by employing tumor single cell RNA sequencing and transcriptome evaluation methodologies. CAPR scientists are also collaborating with CCR clinical investigators to see applications of this pathway-specific models for pancreatic malignancy in assessment of therapeutic options targeting e.g. selected types of Kras mutations. 5. Via homologous recombination in ES cells, CAPR model development experts have constructed and validated a CreERT expressing tamoxifen-inducible 'deletor' mouse strain in which an expression of tamoxifen-dependent CreERT2 recombinase is controlled by the endogenous locus for dopachrome tauto-isomerase 1 (Dct1), known to be active in neural crest derived cells, such as melanocyte progenitor cells called melanoblasts. Upon extensive molecular validation of this new strain, we have intercrossed the Dct-1-CreERT2 allele with two conditional strains carrying Cre-inducible alleles for Braf-V600E mutation (very common in clinical metastatic melanoma cases) and PTEN (also reported lost in melanoma tumors). Tri-allelic animals displayed robust carcinogenesis upon induction with tamoxifen, forming rapidly progressing cutaneous neoplasms. Intriguingly, histopathologic and biomarker assessment suggested these tumors to represent peripheral nerve sheath tumors (or PNST) variety of cutaneous malignancies, that can be explained by the activity of Dct1 promotor in neural crest cells that also give raise to Schwann cells of the peripheral nervous system. At present, a representative collection of RNA samples isolated from PNST/MPNST malignancies induced in these GEM models are evaluated by high-throughput transcriptome analyses with a hope of identifying novel pathways accountable for the progression of sporadic peripheral nerve sheath malignancies. We also aim at comparing at the whole transcriptome level RNA composition of sporadic vs. NF1-dependent MPNST malignancies to detect molecular patterns specific for these two MPNST subtypes. 6. In collaboration with Dr. Sheue-yann Cheng, we have established and characterized a new Tpo-CreERT2 allele that has been shown to selectively express an inducible isoform of Cre recombinase in thyroid gland. This strain is currently used to assemble a genetic model for medullary thyroid carcinoma, using as oncogenic drivers conditional p53 missense mutation alleles generated at CAPR that has been also shared with Dr. Cheng. By employing different breeding schemes to incorporate distinct oncogenic drivers in the ultimate thyroid cancer models, we aim at developing murine models for both papillary and anaplastic types of thyroid malignancy. 7. In collaboration with Dr. Christine Heske (POB Branch), CAPR established orthotropic PDX models for Ewing sarcoma malignancy and conducted a multi-purpose study to evaluate PK profiles, tolerability and anti-tumor efficacy of topoisomerase-I inhibitors as promising therapeutic agents for clinical Ewing sarcomas. 8. CAPR preclinical and model development scientists are assisting Dr. Laurie Krug of HIV and AIDS Malignancy Branch to establish PDX models from clinical Kaposi sarcoma samples as a valuable resource to understand the biology of Kaposi sarcomas and provide experimental platform for evaluating drug formulations effective against this type of malignancy frequently affecting population of patients suffering from AIDS or other immunologic deficiency syndromes.