Abstract 345: Sensitivity of human leukemic sup-t1 cells to chemotherapeutic agents
Authors: Gisis Andrew D. , Medh Rheem D. 
Published: May 2015

Background: Lymphoid cell apoptosis plays an important role in the development and functioning of the immune system. The ability of chemotherapeutic agents such as antimetabolites, topoisomerase poisons, alkylating agent mimics, anti-tumor antibiotics, and glucocorticoids to target the apoptotic pathway is instrumental in their potency as anti-leukemic agents. Resistance to chemotherapeutic agents is a hindrance to disease-free survival. An understanding of the genetic basis for apoptosis induction is essential to the development of more effective chemotherapeutic regimens. Studies in our laboratory, and by other investigators, have suggested that induction of a proapoptotic Bcl-2 family member, Bim, facilitates drug-induced apoptosis of T-lymphocytic leukemia cells in culture. We have identified E4BP4 and Bcl11b as transcriptional regulators of Bim expression. Both E4BP4 and Bcl11b are vital for normal immune cell development and are known to have reciprocal effects on T-cell differentiation and survival. E4BP4 is required for maturation of Induced T-cell derived Natural Killer cells (ITNK) while Bcl11b expression is required for maintenance of T-cell identity. In separate experiments, Bcl11b repression and E4BP4 upregulation have been associated with T-cell apoptosis. In the studies presented here, we are establishing a relationship between E4BP4 and Bcl11b expression, leukemic cell apoptosis, and sensitivity to chemotherapeutic agents in cell culture models of T-lympboblastic leukemia.

Methods: The sensitivity of human Leukemic T-lymphoblast cell line, Sup-T1, to each class of anti-leukemic agent is being evaluated by trypan blue dye exclusion assays and flow cytometric analysis. Drug-induced alterations in E4BP4, Bcl11b, and Bim transcripts were evaluated by RT-qPCR, and the data are being interpreted via Pfaffl analysis.

Results: Sup-T1 cells were resistant to the synthetic glucocorticoid Dexamethasone, and the alkylating agent mimic Cisplatin. Sup-T1 showed moderate sensitivity to the topoisomerase poison Etoposide. Marked sensitivity to the anti-tumor antibiotic Daunorubicin and the antimetabolite 5-fluorouracil was indicated. E4BP4 and Bim transcript levels seem to be induced by Daunorubicin and 5-fluorouracil, when compared to the reference gene β-actin. Bcl11b regulation is being investigated currently and all results are being tested against a new reference gene, GAPDH.

Conclusions: Our data support our hypothesis of a correlation between sensitivity to chemotherapeutic agents and upregulation of E4BP4 and Bim in Sup-T1 cells. Analysis of Bcl11b expression data is ongoing.

Acknowledgements: This project is funded by NIH grant (SC3 GM 081099) awarded to RDM.

Citation Format: Andrew D. Gisis, Rheem D. Medh. Sensitivity of human leukemic sup-t1 cells to chemotherapeutic agents. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 345. doi:10.1158/1538-7445.AM2014-345