Inter-Metastatic Heterogeneity of Tumor Marker Expression and Microenvironment Architecture in a Preclinical Cancer Model
Open Access
- 13 June 2021
- journal article
- research article
- Published by MDPI AG in International Journal of Molecular Sciences
- Vol. 22 (12), 6336
- https://doi.org/10.3390/ijms22126336
Abstract
Background: Preclinical drug development studies rarely consider the impact of a candidate drug on established metastatic disease. This may explain why agents that are successful in subcutaneous and even orthotopic preclinical models often fail to demonstrate efficacy in clinical trials. It is reasonable to anticipate that sites of metastasis will be phenotypically unique, as each tumor will have evolved heterogeneously with respect to gene expression as well as the associated phenotypic outcome of that expression. The objective for the studies described here was to gain an understanding of the tumor heterogeneity that exists in established metastatic disease and use this information to define a preclinical model that is more predictive of treatment outcome when testing novel drug candidates clinically. Methods: Female NCr nude mice were inoculated with fluorescent (mKate), Her2/neu-positive human breast cancer cells (JIMT-mKate), either in the mammary fat pad (orthotopic; OT) to replicate a primary tumor, or directly into the left ventricle (intracardiac; IC), where cells eventually localize in multiple sites to create a model of established metastasis. Tumor development was monitored by in vivo fluorescence imaging (IVFI). Subsequently, animals were sacrificed, and tumor tissues were isolated and imaged ex vivo. Tumors within organ tissues were further analyzed via multiplex immunohistochemistry (mIHC) for Her2/neu expression, blood vessels (CD31), as well as a nuclear marker (Hoechst) and fluorescence (mKate) expressed by the tumor cells. Results: Following IC injection, JIMT-1mKate cells consistently formed tumors in the lung, liver, brain, kidney, ovaries, and adrenal glands. Disseminated tumors were highly variable when assessing vessel density (CD31) and tumor marker expression (mkate, Her2/neu). Interestingly, tumors which developed within an organ did not adopt a vessel microarchitecture that mimicked the organ where growth occurred, nor did the vessel microarchitecture appear comparable to the primary tumor. Rather, metastatic lesions showed considerable variability, suggesting that each secondary tumor is a distinct disease entity from a microenvironmental perspective. Conclusions: The data indicate that more phenotypic heterogeneity in the tumor microenvironment exists in models of metastatic disease than has been previously appreciated, and this heterogeneity may better reflect the metastatic cancer in patients typically enrolled in early-stage Phase I/II clinical trials. Similar to the suggestion of others in the past, the use of models of established metastasis preclinically should be required as part of the anticancer drug candidate development process, and this may be particularly important for targeted therapeutics and/or nanotherapeutics.Funding Information
- Canadian Cancer Society and Canadian Institute for Health Rersearch (CCS 702491 and 705290; CIHR MOP-102611)
This publication has 84 references indexed in Scilit:
- Outcomes of Women with Early-Stage Breast Cancer Receiving Adjuvant TrastuzumabCurrent Oncology, 2012
- Loss of Human Epidermal Growth Factor Receptor 2 (HER2) Expression in Metastatic Sites of HER2-Overexpressing Primary Breast TumorsJournal of Clinical Oncology, 2012
- Tumor grafts derived from women with breast cancer authentically reflect tumor pathology, growth, metastasis and disease outcomesNature Medicine, 2011
- Lapatinib Distribution in HER2 Overexpressing Experimental Brain Metastases of Breast CancerPharmaceutical Research, 2011
- Vascular phenotypes in primary non-small cell lung carcinomas and matched brain metastasesBritish Journal of Cancer, 2011
- Heterogeneous Blood–Tumor Barrier Permeability Determines Drug Efficacy in Experimental Brain Metastases of Breast CancerClinical Cancer Research, 2010
- Receptor conversion in distant breast cancer metastasesBreast Cancer Research, 2010
- Far-red fluorescent tags for protein imaging in living tissuesBiochemical Journal, 2009
- Murine Models to Evaluate Novel and Conventional Therapeutic Strategies for CancerThe American Journal of Pathology, 2007
- Orthotopic models of cancer for preclinical drug evaluation: advantages and disadvantagesEuropean Journal of Cancer, 2004