A Novel l-Asparaginase with low l-Glutaminase Coactivity Is Highly Efficacious against Both T- and B-cell Acute Lymphoblastic Leukemias In Vivo.

Acute lymphoblastic leukemia (ALL) is the most common type of pediatric cancer, although about 4 of every 10 cases occur in adults. The enzyme drug l-asparaginase serves as a cornerstone of ALL therapy and exploits the asparagine dependency of ALL cells. In addition to hydrolyzing the amino acid l-asparagine, all FDA-approved l-asparaginases also have significant l-glutaminase coactivity. Since several reports suggest that l-glutamine depletion correlates with many of the side effects of these drugs, enzyme variants with reduced l-glutaminase coactivity might be clinically beneficial if their antileukemic activity would be preserved. Here we show that novel low l-glutaminase variants developed on the backbone of the FDA-approved Erwinia chrysanthemi l-asparaginase were highly efficacious against both T- and B-cell ALL, while displaying reduced acute toxicity features. These results support the development of a new generation of safer l-asparaginases without l-glutaminase activity for the treatment of human ALL.Significance: A new l-asparaginase-based therapy is less toxic compared with FDA-approved high l-glutaminase enzymes Cancer Res; 78(6); 1549-60. ©2018 AACR.

LIGHT Elevation Enhances Immune Eradication of Colon Cancer Metastases.

The majority of patients with colon cancer will develop advanced disease, with the liver being the most common site of metastatic disease. Patients with increased numbers of tumor-infiltrating lymphocytes in primary colon tumors and liver metastases have improved outcomes. However, the molecular factors that could empower antitumor immune responses in this setting remain to be elucidated. We reported that the immunostimulatory cytokine LIGHT (TNFSF14) in the microenvironment of colon cancer metastases associates with improved patient survival, and here we demonstrate in an immunocompetent murine model that colon tumors expressing LIGHT stimulate lymphocyte proliferation and tumor cell-specific antitumor immune responses. In this model, increasing LIGHT expression in the microenvironment of either primary tumors or liver metastases triggered regression of established tumors and slowed the growth of liver metastases, driven by cytotoxic T-lymphocyte-mediated antitumor immunity. These responses corresponded with significant increases in tumor-infiltrating lymphocytes and increased expression of lymphocyte-homing signals in the metastatic tumors. Furthermore, we demonstrated evidence of durable tumor-specific antitumor immunity. In conclusion, increasing LIGHT expression increased T-cell proliferation, activation, and infiltration, resulting in enhanced tumor-specific immune-mediated tumor regressions in primary tumors and colorectal liver metastases. Mechanisms to increase LIGHT in the colon cancer microenvironment warrant further investigation and hold promise as an immunotherapeutic strategy. Cancer Res; 77(8); 1880-91. ©2017 AACR.

CD11b+GR1+ myeloid cells secrete NGF and promote trigeminal ganglion neurite growth: implications for corneal nerve regeneration.

PURPOSE: We characterized fluorescent bone marrow cells (YFP(+) BMCs) in the thy1-YFP mouse and determine if they promote trigeminal ganglion (TG) cell neurite growth. METHODS: Excimer laser annular keratectomy was performed in thy1-YFP mice, and corneas were imaged. BMCs were harvested from femur and tibia, and the expression of surface markers on YFP(+) BMCs was analyzed by flow cytometry. The immunosuppressive action of BMCs (YFP(+) and YFP(-)) was evaluated in an allogenic mixed lymphocyte reaction (MLR). Neurotrophic action of BMCs (YFP(+) and YFP(-)) was determined in compartmental and transwell cultures of dissociated TG cells. RESULTS: Following annular keratectomy, YFP(+) BMCs infiltrated the cornea. YFP(+) BMCs shared surface markers (CD11b+Gr1+Ly6C+Ly6G-F4/80(low)) with monocytic myeloid-derived suppressor cells (MDSCs), had similar morphology, and suppressed T-cell proliferation in allogenic MLR in a dose-dependent manner. YFP(+) BMCs, but not YFP(-) BMCs, significantly increased growth of TG neurites in vitro. When cultured in a transwell with TG neurites, YFP(+) BMCs expressed neurotrophins and secreted nerve growth factor (NGF) in conditioned medium. YFP(+) BMCs that infiltrated the cornea maintained their phenotype and actions (neuronal and immune). CONCLUSIONS: YFP(+) BMCs in thy1-YFP mice have immunophenotypic features of MDSCs. They secrete NGF and promote neuroregeneration. Their immunosuppressive and neurotrophic actions are preserved after corneal infiltration. These findings increase our understanding of the beneficial roles played by leukocyte trafficking in the cornea and may lead to therapeutic strategies that use NGF-secreting myeloid cells to repair diseased or injured neurons.

Phosphorylation of forkhead transcription factors by erythropoietin and stem cell factor prevents acetylation and their interaction with coactivator p300 in erythroid progenitor cells.

The mammalian forkhead transcription factors, FOXO3a (FKHRL1), FOXO1a (FKHR) and FOXO4 (AFX) are negatively regulated by PKB/Akt kinase. In the present study we examined the engagement of forkhead family of transcription factors in erythropoietin (Epo)- and stem cell factor (SCF)-mediated signal transduction. Our data show that all three forkhead family members, FOXO3a, FOXO1a and FOXO4 are phosphorylated in human primary erythroid progenitors. Experiments performed to determine various upstream signaling pathways contributing to phosphorylation of forkhead family members show that only PI-3-kinase pathway is required for inactivation of FOXO3a. Our data also demonstrate that during Epo deprivation FOXO3a interacts with the transcriptional coactivator p300 and such interaction is disrupted by stimulation of cells with Epo. To determine the domains in FOXO3a, mediating its interaction with p300, we performed GST pull-down assays and found that the N-terminus region containing the first 52 amino acids was sufficient for binding p300. Finally, our data demonstrate that FOXO3a and FOXO1a are acetylated during growth factor deprivation and such acetylation is reversed by stimulation with Epo. Thus mammalian forkhead transcription factors are involved in Epo and SCF signaling in primary erythroid progenitors and may play a role in the induction of apoptotic and mitogenic signals.