Cortactin Expression is a Novel Biomarker for Risk Stratification of T-Cell Acute Lymphoblastic Leukemia

Relationship Between Cytotoxic T-Lymphocyte-Associated Antigen-4: Programmed Death-1 Genes Polymorphisms and Susceptibility to Pediatric B-Cell Acute Lymphoblastic Leukemia

Programmed death-1 (PD1) and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) have a vital role in immune checkpoint pathways. Single nucleotide polymorphisms (SNPs) of PD1 and CTLA4 have been reported to be associated with susceptibility to certain autoimmune diseases and cancers. The potential association between SNPs in these immune checkpoint genes and risk of acute lymphoblastic leukemia (ALL) still unclear. The aim of this study is to clarify the effect of PD1 and CTLA4 SNPs on the risk of developing ALL and the prognosis of the disease. The study was performed on 100 pediatric B-ALL patients and 100 controls. The PD1 and CTLA4 SNPs were examined by RFLP technique. The study revealed that CTLA4 (rs11571316) was associated with high risk of B-ALL developments OR 1.492 (CI: 1157 to 1924) (P=0.002). PD1 (rs36084323) GA genotype was significantly associated with protective effect against nonremission (P=0.007). PD1 (rs36084323) A allele were associated with protective effect against relapse (P=0.008). CTLA4 and PD1 genotypes did not have significant impact on B-ALL patients outcome. The current study displayed for the first time that genetic variations of the CTLA-4, was associated with susceptibility to B-ALL and that PD1 (rs36084323) GA genotype was significantly associated with protective effect against nonremission, while PD1 (rs36084323) A allele was associated with protective effect against relapse.

T cell functions and organ infiltration by leukemic T cells require cortactin

T cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy that is still fatal in many cases. T cell blasts are characterized by hyperactivation and strong proliferative and migratory capacities. The chemokine receptor CXCR4 is involved in mediating malignant T cell properties, and cortactin has been shown to control CXCR4 surface localization in T-ALL cells. We have previously shown that cortactin overexpression is correlated with organ infiltration and relapse in B-ALL. However, the role of cortactin in T cell biology and T-ALL remains elusive. Here, we analyzed the functional relevance of cortactin for T cell activation and migration and the implications for T-ALL development. We found that cortactin is upregulated in response to T cell receptor engagement and recruited to the immune synapse in normal T cells. Loss of cortactin caused reduced IL-2 production and proliferation. Cortactin-depleted T cells showed defects in immune synapse formation and migrated less due to impaired actin polymerization in response to T cell receptor and CXCR4 stimulation. Leukemic T cells expressed much higher levels of cortactin compared to normal T cells that correlated with greater migratory capacity. Xenotransplantation assays in NSG mice revealed that cortactin-depleted human leukemic T cells colonized the bone marrow significantly less and failed to infiltrate the central nervous system, suggesting that cortactin overexpression drives organ infiltration, which is a major complication of T-ALL relapse. Thus, cortactin could serve as a potential therapeutic target for T-ALL and other pathologies involving aberrant T cell responses.