One of the most significant challenges in controlling cancer is the high degree of heterogeneity within the neoplastic cells of individual tumors. While tumor cell heterogeneity has been described at many levels and an understanding of the processes that create heterogeneity is emerging, the extent to which the heterogeneous subpopulations of tumor cells vary in their functional activities and whether interactions between subpopulation influence tumor initiation and progression is poorly understood. Major barriers to investigating these questions have been the lack of methodologies to maintain the heterogeneity of human tumors in culture and to propagate distinct clonal subpopulations from individual tumors. Together with our collaborators, we have developed methodologies that overcome these barriers and make it feasible to isolate, culture, and characterize clonal populations of ovarian tumor cells and then track barcoded, epitope-tagged clonal populations within tumor xenografts generated from mixtures of transplanted clones. Using these approaches in a pilot study, we obtained evidence for interclonal collaborations that significantly affect tumor progression - most interestingly, we found that clonal populations of cancer cells which are unable to initiate tumor formation on their own, can strongly promote the expansion of primary tumors and metastasis at specific organ sites when mixed with 'tumor-initiating' clones. This supports the hypothesis that clonal subpopulations within a tumor cooperate with one another to promote tumor expansion and metastasis. In this proposal, we describe plans to use a systematic approach to test this hypothesis in human ovarian tumors by (1) isolating and characterizing the extent of genetic and phenotypic variation among a large set of clonal populations derived from ovarian tumors, (2) comparing the activities of single clonal populations to mixtures of such populations in order to investigate the existence and nature of intratumoral cross talk, (3) tracking intratumoral localization of clonal populations over time, an (4) elucidating the mechanisms responsible for phenotypes generated by intratumoral crosstalk.

Public Health Relevance

The information derived from these studies will provide important insights into the nature of cooperative interactions between tumor cell populations and mutual dependencies among tumor cell variants and reveal how these affect tumor expansion or metastasis. This approach provides a platform to investigate a wide variety of phenotypes that are influenced by intratumoral crosstalk, and information relevant to diagnosis, prognosis and treatment of cancers.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA181543-04
Application #
9250107
Study Section
Tumor Progression and Metastasis Study Section (TPM)
Program Officer
Woodhouse, Elizabeth
Project Start
2014-04-17
Project End
2019-03-31
Budget Start
2017-04-01
Budget End
2018-03-31
Support Year
4
Fiscal Year
2017
Total Cost
Indirect Cost
Name
Harvard Medical School
Department
Anatomy/Cell Biology
Type
Schools of Medicine
DUNS #
047006379
City
Boston
State
MA
Country
United States
Zip Code
02115