Abstract 5502: Therapeutic Efficacy Prediction by Quantitative Protein Analysis in Response to Anti-Cancer Agents

Background: The conventional chemosensitivity test employs a growth suppression assay. However, surgically removed specimens often have low viability which makes the assay unreliable, since the poor cell growth may be associated with the low viability instead of the chemosensitivity of the cell. On the other hand, we do know that the level of proteins involved in signal transduction is changed prior to cellular responses to the anti-cancer agents. In the present study, we investigated if protein signaling within a 24-hour exposure of the anti-cancer agents can predict the cellular fate at 72-hour time points. Materials and Methods: The human colon cancer cell line, HCT116, was exposed to three different DNA-damaging anti-cancer agents including gamma irradiation, ultraviolet, and doxorubicin. The anti-cancer agent-exposed cell pellets from different conditions (e.g., doses, and time-points) were collected to produce a lysate array, which finally accommodated more than 500 samples on a single glass slide. Array image and quantitative protein analyses were performed with the P-SCAN and ProteinScan programs. Results: A total of 19 protein species were tested on a lysate array, providing kinetic information of the protein. In response to all three agents, p53 protein was stabilized and the level increased over time in a dose-dependent manner. Upon detailed time-course analysis, however, an oscillation was seen in response to gamma irradiation, indicating the presence of a feedback loop. Comparing the rate of increasing levels of p21 and CyclinD3 within 24 hours in response to doxorubicin administration, the rates are well associated with the status of cell fate. In other words, when the rate of p21 is higher than CyclinD3, it is associated with a G2 arrest at 72 hours, whereas a higher CyclinD3 rate is associated with apoptosis at 72 hours after drug administration. Conclusion: Some events occurring at 72 hours can be predicted by seeing the quantitative level of protein kinetics within 24 hours. Most of the primary culture cells can survive for only a short period of time. The protein kinetics may be a useful clinical chemosensitivity predictor even when using low viability specimens. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5502.