Investigation of the effectiveness of new pro-oxidative strategies in the treatment of B-cell acute lymphoblastic leukemia

Hypothesis: Accumulating evidence suggests that redox imbalance selectively kills cancer cells, and that some antioxidant enzymes are important therapeutic targets. Thioredoxins (TXN), and members of the same family of peroxyredoxin (PRDX) proteins are antioxidant enzymes that ensure redox balance is maintained. Our preliminary studies showed significantly elevated levels of reactive oxygen species in B-cell acute lymphoblastic leukemia (B-ALL) cells. Moreover, both in B-ALL cell lines and in patients' lymphoblasts, we observed an increased level of expression of antioxidant enzymes from the TXN family. The expression level of these enzymes increased in patients in the relapse stage. Moreover, in B-ALL lines we observed that PRDX1 promotes the proliferation of leukemic cells. We suspect that enzymes from the TXN family are one of the factors improving the survival of leukemic cells under oxidative stress conditions and may be new therapeutic targets. Research objective: In this project we will investigate the effectiveness of a new pro-oxidative strategy in the treatment of B-ALL. The most important goal of the project is to validate PRDX1 and other TXN family enzymes as potential new therapeutic targets for B-ALL. We also plan to investigate how PRDX1 supports the proliferation and survival of B-ALL cells. In addition, we would like to assess whether inhibitors of the TXN family of enzymes sensitize B-ALL cells to the chemotherapeutic agents used to treat B-ALL. Research method: To achieve the above goals, we plan to use several research models: B-ALL cell lines (NAM-6 and SEMK2), clinical material collected from B-ALL patients (bone marrow lymphoblasts, serum), and an in vivo mouse model. Three research tasks will be carried out: Task 1. Validation of PRDX1 and other antioxidant enzymes from the TXN family as therapeutic targets in B-ALL in cell line models. 1A. To study the effects of inhibition of PRDX1 expression on B-ALL cell survival and proliferation. 1B. To test whether the inhibition of leukemic cell proliferation resulting from blockade of PRDX1 expression depends on cysteines. 1C. To study the transcriptional response of leukemic cells to the inhibition of PRDX1 expression using high-throughput genetic methods. 1D. Study of the effectiveness of therapies combining inhibitors of antioxidant enzymes from the TXN family with chemotherapeutic agents used in the treatment of B-ALL. Task 2. Examination of the biomarkers of oxidative stress and the expression of antioxidant enzymes from the TXN family in the material collected from patients with B-ALL. 2 A. Collection of material from patients and clinical base of adults and children diagnosed with B-ALL 2 B. Assessment of biomarkers of oxidative stress in serum from B-ALL 2 patients C. Evaluation of the expression level of TXN family enzymes in B-ALL 2 patients D. Statistical analysis of redox parameters in relation to clinical data Task 3. Investigation of the effects of blocking the TXN family antioxidant enzymes in vivo in a mouse model of human leukemia. Effect of the results: B-ALL is the most common pediatric neoplasm. Classical chemotherapy is almost exclusively used to treat B-ALL. Most patients respond well to remission inducing therapy, but relapse, often refractory to treatment, occurs in approximately 20% of patients. Better understanding of the biology of B-ALL and the molecular mechanisms responsible for the proliferation and survival of lymphoblasts, in particular the role of antioxidant enzymes from the TXN family, will improve the effectiveness of existing treatments and may indicate new targets in B-ALL therapy. As a peroxide metabolizing enzyme, PRDX1 has important signaling functions.Additionally, under oxidative stress, PRDX1 can act as a chaperone. Not all functions of the PRDX1 are dependent on the peroxide removal activity. So far it is unclear whether the anti-apoptotic function of PRDX1 depends on cysteines and activity related to the metabolism of peroxides. In this project we will try to answer this question. A better understanding of the anti-apoptotic activity of PRDX1 will contribute to the development of new, more selective inhibitors of this enzyme.