Investigating different cell population kinetics in solid tumors on an in vitro tumor heterogeneity model

Aim and Hypothesis: In this study, we aimed to generate an in vitro intratumoral heterogeneity model by florescent tagging isogenic subclones derived from the same cancer cell line. Hypothesis of this thesis is that intratumoral aneuploidy alterations affect cancer progression at different levels. Methods: Isogenic near-diploid and near-tetraploid cell lines were established from the colon cancer DLD-1 cell line via FACS-sorting and confirmed by genetic analyses. We tagged these subclones with different fluorescent labeled vectors. Correlation between individual genetic profiles and functional assays under different microenvironmental conditions (chemotherapy, radiation, and hypoxia) were examined. We have identified cellular kinetics and genetic variations that could possibly lead to drug resistance in tumors. Results: DLD-1 subclones were characterized and stable fluorescence-tagged successfully. Generated in vitro intratumoral heterogeneity models were monitored time-wise and under the effects of various therapeutics. Results obtained from the experiments performed in order to determine population behaviours of subclones were compared to genomic analyses data performed at Ried Lab in NIH to designate cancer drug resistance mechanisms at molecular level. Conclusion: One of the major underlying reasons for cancer therapy resistance is intratumoral cellular heterogeneity. It is now known that clones that harbour mutations and/or epigenetic patterns that provide a survival advantage under changing microenvironment conditions are the main culprits of therapy resistance. Therefore it is very important to define the genotype of these clones to overcome the problem of resistance. By means of this study, a big step towards illuminating mechanisms related to cancer drug resistance was taken.