A17: Leukemic stem cells in methotrexate resistant T cell leukemia
1Indian Institute of Technology, Chennai, Chennai, Tamilnadu, Iceland
The recent breakthrough discoveries that confirmed the role of cancer stem cells (Chen et al., 2012, Driessens et al., 2012, Schepers et al., 2012) in different types of cancers proves the urgent need to identify and target these cells. Drug resistance is the major problem in treating cancers. Many cancers have been reported to show resistance to methotrexate, which is a common drug used for treatment. Cancer stem cells (CSCs) form chemotherapy resistant side population, which may result in the recurrence of disease and thus needs to be characterized and targeted
We isolated methotrexate resistant cells from human acute lymphoblastic T cell leukemic cell line, MOLT-4 by treating cells with 0.1 mM Methotrexate constantly for more than 10 passages and characterized the cells using FACS analysis for cancer stem cell markers like CD34, CD90, CD123 and CD117. The gene expression analysis was done for transcription factors and signaling pathways involved in cancer stem cells by real time PCR analysis. Additional assays for cancer stem cells like CFU and BrDu assays were also performed.
The drug resistant cells of MOLT-4 cells had highly upregulated expression of stem cell markers and showed cancer stem cell like properties. The results showed that there is enrichment of cancer stem cell like population in the T cell leukemic cell line when cultured in presence of commonly used cancer drug, methotrexate for a long period.
This indicates that prolonged drug treatment enhances the cancer stem cell population, which is responsible for chemo- resistance and cancer recurrence in T cell leukemia. Hence, there needs to be an alternative therapeutic strategy to circumvent the chemo-resistance in cancer like targeted therapy. We are currently working on targeting these drug resistant cells using specific immunotoxins.