Ke-Chih Lin

Abstract B039: Multinucleation precedes the emergence of drug resistance in prostate cancer

Metastatic prostate cancer remains a lethal disease. Taxane chemotherapy used to be restricted to the hormone-resistant metastatic setting in which most patients with castration-resistant prostate cancer (CRPC) develop therapeutic resistance to chemotherapy, achieving limited therapeutic benefit. Recently, two trials demonstrated adjuvant chemohormonal therapy to increase survival in men with high-risk metastatic hormone-sensitive prostate cancer. Although chemotherapy has been extensively used for decades, how it affects tumor heterogeneity at the molecular level is poorly understood. Experiments with drug gradients in our engineered microfluidic device have shown that docetaxel therapy leads to multinucleation with a stiff distribution pattern of heterogeneous cell populations across the concentration gradient. Furthermore, in these experiments, multinucleation always preceded the development of drug resistance. To confirm these findings, we conducted experiments in conventional cell culture using different chemotherapeutic agents in several prostate cancer cell lines and confirmed multinucleation was a common feature among them. Interestingly, multinucleation occurred to some extent, independently of the mechanism of action of the drug tested. Aneuploidy, an inherent consequence of multinucleation, has been described as a common characteristic of tumors and proposed to drive tumor progression by increasing the potential for cellular transformation. However, whether this is a cause or a consequence of cancer remains unclear. Aneuploidy can be caused by very diverse molecular mechanisms such as mitotic slippage, endo-replication, or cell fusion. In cancer biology, it has been associated with epithelial-mesenchymal transition as well as with gain of stem-like potential. Recent data in prostate cancer demonstrated the association of multinucleation with chemotherapy, androgen-deprivation therapy, and radiotherapy. Although the data supporting the association of multinucleation with drug resistance are extensive, the effects of these therapies on tumor heterogeneity remain unknown. A better understanding of the resistance mechanisms might reveal new targets for cancer therapy. In this work, we focus on the characterization of the subset of cells within the tumor population that leads to the multinucleated phenotype, particularly the subpopulation with the potential to reverse polyploidy and repopulate tumor heterogeneity after therapy. Citation Format: Gonzalo Torga, Ke-Chih Lin, Robert H. Austin, Kenneth J. Pienta. Multinucleation precedes the emergence of drug resistance in prostate cancer [abstract]. In: Proceedings of the AACR Special Conference: Prostate Cancer: Advances in Basic, Translational, and Clinical Research; 2017 Dec 2-5; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(16 Suppl):Abstract nr B039.

Cancer dormancy and criticality from a game theory perspective

BackgroundThe physics of cancer dormancy, the time between initial cancer treatment and re-emergence after a protracted period, is a puzzle. Cancer cells interact with host cells via complex, non-linear population dynamics, which can lead to very non-intuitive but perhaps deterministic and understandable progression dynamics of cancer and dormancy.ResultsWe explore here the dynamics of host-cancer cell populations in the presence of (1) payoffs gradients and (2) perturbations due to cell migration.ConclusionsWe determine to what extent the time-dependence of the populations can be quantitively understood in spite of the underlying complexity of the individual agents and model the phenomena of dormancy.

Abstract 2418: Microenvironment-on-chip: Development of a microfluidics-based tumor ecosystem

Despite its limited clinical predictive capacity, conventional cell culture remains the most frequently used preclinical model in biomedical research. For many years, microfluidics-based organ-on-chips have been proposed to overcome conventional cell culture limitations but given their inability to provide reliable and reproducible data, their usage remains anecdotal. Immune, stromal and cancer cells constitute a complex adaptive system in each tumor microenvironment. To study the causes and consequences of tumor heterogeneity in these complex adaptive systems, we have developed a platform to model and investigate tumor microenvironments at primary and metastatic sites in which multiple nuclear-labelled cell types can be grown in a multi-welled, communicating habitat with controlled gradients for temperature, pH, nutrients, and oxygen tension. In conjunction with labelled-nuclei, genetically-engineered cell lines with fluorescence-based biosensors can be generated to detect specific genetic expression changes in response to cell to cell interactions as well as varying environmental conditions over time. One of the major caveats for microfluidics prototypes is reproducibility. The proposed design is easily adaptable to most of the commercially available incubation microscopy systems, allowing the experiments to be replicated by independent groups in an effort to provide reliable and reproducible data. The ability to establish dynamic gradients within individual habitats longitudinally over time and space provides the capacity to study the effect of chemokines and drugs on the tumor ecosystem in order to discover key interactions between host cells and cancer cells and to develop improved therapeutic strategies. In contrast to previous organ-on-chip models, our technology is not limited to a mere observational platform for automated cell counting and tracking but also provides flexibility for downstream capacities such as immunofluorescence, in situ hybridization or single-cell sequencing, as well as retrieval of single cells or specific subpopulations based on the fluorescent reporters and labelled nuclei. The presented engineered microenvironment allows continued in vitro quantitative studies of the interactions of multiple cell types as well as varying environmental conditions. Here we propose a cancer-on-chip platform that is able to recapitulate key components and interactions to mimic different tumor microenvironments in a comprehensive manner, yet simple enough to provide reliable and reproducible data. Citation Format: Gonzalo Torga, Ke-Chih Lin, Robert H. Austin, Kenneth J. Pienta. Microenvironment-on-chip: Development of a microfluidics-based tumor ecosystem. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 2418.