Abstract A49: Efficiency of 11a-N-tosyl-5-deoxi-pterocarpan (LQB-223) in a panel of myeloid leukemia cell lines with different chemoresistance backgrounds
Authors: Reis Flaviana Ruade de Souza , Mororó Janio da Silva , Silva Karina Lani , Buarque Camila D. , Costa Paulo R.R , Maia Raquel Ciuvalschi 
Published: May 2015

Introduction and Objective: Chronic myeloid leukemia (CML) is a myeloproliferative disease characterized by Philadelphia chromosome while acute myeloid leukemia (AML) is a highly heterogeneous disease, with biologically distinct profile of cytogenetic and molecular features. The chemoresistance is one of the major obstacles in treating of chronic and acute myeloid leukemias. In this context, the novel 11a-N-tosyl-5-deoxi-pterocarpan compound, LQB-223, synthesized at the Laboratory of Bioorganic Chemistry Research Center of Natural Products, UFRJ, Brazil, has shown activity in leukemias. In this study we analyzed the LQB-223 compound activity in a panel of five myeloid leukemia cell lineages.

Materials and Methods: In this study we used the human CML cells K562 and multidrug resistant (MDR) variant Lucena; three AML cell lines: Kasumi-1, HL-60 and U-937; and peripheral blood mononucleated cells (PBMC) of five healthy individuals. All cell lines were treated with LQB-223 and the cell viability was performed by MTT assay and the cell death was assessed by annexin V/propidium iodide (PI) staining and caspase-3 activation. Also, the cell cycle and DNA fragmentation were performed by PI staining using flow cytometry. Antiapoptotic proteins – XIAP and survivin – were assessed by Western blot.

Results: The PBMC samples were incubated with different concentrations of LQB-223 for 24, 48 and 72 h and our results show that concentrations of up to LQB-223 30.0 μM is innocuous to PBMC. However, LQB-223 induced significant decrease of cell viability in all leukemia cells at 2.5, 5.0 and 10.0 μM, during 24, 48 and 72 h of treatment. In addition, LQB-223 5.0 μM was effective in promoting cell death in all cell lines, associated with high levels of annexin V/PI staining and caspase-3 activation. Moreover, LQB-223 5.0 μM induced changes in cell cycle distribution and cell fragmentation in all cell lines. Furthermore, we observed G2/M arrest in CML cells after LQB-223 treatment. In AML cells, LQB-223 treatment induced reduction in XIAP and survivin expression levels.

Conclusion: The novel compound LQB-223 inhibits cell-viability and increases cell death of CML and AML leukemia cell lines. Because LQB-223 inhibits the expression of XIAP and survivin antiapoptotic proteins, it may be contributing to the compound´s cytotoxic activity. Indeed, results of Buarque CD et al., 2014, suggest that LQB-223 could reverse ABCB1/Pgp-mediated MDR. As the novel compound LQB-223 was efficient in both types of myeloid leukemias, it suggests a mechanism of action involving pathways common to both diseases. Besides, LQB-223 did not affect PBMC from healthy individuals indicating tolerance of normal cells. Together, these results point out the LQB-223 as a promising agent in CML in blastic phase and in AML.

Financial support: INCT, FAPERJ, CNPq and Programa de Oncobiologia.

Citation Format: Flaviana Ruade de Souza Reis, Janio da Silva Mororó, Karina Lani Silva, Camila D. Buarque, Paulo R.R Costa, Raquel Ciuvalschi Maia. Efficiency of 11a-N-tosyl-5-deoxi-pterocarpan (LQB-223) in a panel of myeloid leukemia cell lines with different chemoresistance backgrounds. [abstract]. In: Proceedings of the AACR Precision Medicine Series: Drug Sensitivity and Resistance: Improving Cancer Therapy; Jun 18-21, 2014; Orlando, FL. Philadelphia (PA): AACR; Clin Cancer Res 2015;21(4 Suppl): Abstract nr A49.