Abstract PR09: Cellular heterogeneity of ovarian carcinoma cells and its impact on tumor behavior

Abstract

Abstract One of the most challenging aspects of cancer treatment is intratumoral heterogeneity (ITH). However it is been extremely difficult to monitor the extent to which individual clonal populations contribute to and affect tumor behavior because of the inability to culture tumor cells from patients in vitro without clonal selection under standard culture conditions, which lead to a loss in initial heterogeneity. Using a medium developed by Dr. Tan Ince that allows primary tumor cells to undergo continuous population doublings with minimal, if any, selection for or against specific clones, we generated 80 clonal populations from a Clear Cell Carcinoma (CCC) patient sample and monitored the extent of phenotypic and genomic heterogeneity among 12 of the clonal populations. These clones showed striking heterogeneity in copy number alterations as well as morphologic and phenotypic heterogeneity in vitro in assays such as anoikis, growth in soft agar, population doubling time, and growth in 3D reconstituted basement membrane cultures. To examine correlations between in vitro properties and tumor formation in vivo, we tagged the clones with Gaussia-Luciferase (Gluc), a secreted luciferase, which allowed us to monitor tumor burden over time using a blood-based assay. Based on tumor growth at 10 weeks, only two clonal populations were able to grow in the peritoneum when injected alone, one of which (#31) showed a much more rapid growth rate than the other; however #31 was still limited in its tumorigenic capacity, generating only ascitic tumor populations. To address whether functional crosstalk between clones affects tumor progression, we injected mixtures of the clones. Interestingly, mixtures of the 12 clones resulted in the generation of more aggressive in vivo phenotypes, e.g. the formation of solid peritoneal tumors and metastasis to lungs and brain, behaviors not detected with any individual clones. These results suggest that there is cooperativity between the clones to enhance growth and induce metastasis. The study has provided evidence that cell lines generated from individual clones vary significantly in their functional activities in vitro and in vivo. Moreover, by studying the single cell clones, we have found evidence for the existence of interclonal crosstalk during tumor progression and are currently studying the nature and impact of such cross talks on tumor progression and metastasis. This abstract is also presented as Poster A57. Citation Format: Suha Naffar-Abu Amara, Laura M. Selfors, Marit Krohn, Tan A. Ince, Bo R. Rueda, Rosemary Foster, Gordon B. Mills, Joan S. Brugge. Cellular heterogeneity of ovarian carcinoma cells and its impact on tumor behavior. [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research: From Concept to Clinic; Sep 18-21, 2013; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2013;19(19 Suppl):Abstract nr PR09.