Leukemia (2010) 24, 544-551; doi:10.1038/leu.2009.280; published online 14 January 2010″
“Children with acute lymphoblastic leukemia (ALL) diagnosed with resistant phenotypes, and those who relapse, have a dismal prognosis for cure. The antifolate methotrexate (MTX), a
universal component of ALL therapies, is metabolized by folylpoly-gamma-glutamate synthetase (FPGS) into long-chain polyglutamates (MTX-PG(3-7)), resulting in enhanced cytotoxicity from prolonged inhibition of dihydrofolate reductase (DHFR) and thymidylate synthetase (TS). Using DNasel assays, we identified a hypersensitive site upstream from exon-1, suggesting chromatin remodeling could alter FPGS BAY 1895344 in vitro expression. We demonstrated that histone deacetylase-1 (HDAC1)
is recruited by NFY and Sp1 transcription factors to the FPGS promoter in ALL cell lines. We examined the effect of histone deacetylase inhibitors (HDACIs) sodium butyrate and suberoylanilide hydroxamic acid (SAHA) on the expression of FPGS and other folate-related genes. HDACIs increased FPGS mRNA expression by 2- to 5-fold, whereas DHFR and TS mRNA expression was decreased. Combination treatment with MTX plus SAHA significantly increased cytotoxicity and apoptosis in B- 3-Methyladenine and T-ALL cell lines as compared with each drug alone (CI <= 0.8). SAHA increased the intracellular accumulation of long-chain MTX-PG(3-7). Therefore, HDACI-induced FPGS expression increases the accumulation of MTX-PG(3-7) and cytotoxicity in ALL cell lines, which is potentiated by DHFR and TS downregulation. The synergism exhibited by the combination of MTX and SAHA warrants clinical testing in ALL patients. Leukemia (2010) 24, 552-562; doi:10.1038/leu.2009.282; published online 14 January 2010″
“Side-population (SP) analysis identifies precursor
cells in normal and malignant tissues. Cells selleck chemicals with this phenotype have increased resistance to many cytotoxic agents, and may represent a primary drug-resistant population in malignant diseases. To discover whether drug-resistant malignant SP cells are nonetheless sensitive to immune-mediated killing, we first established the presence of a malignant CD5(+) CD19(+) SP subset in the blood of 18/21 subjects with B-cell chronic lymphocytic leukemia (B-CLL). We examined the fate of these cells in six of these individuals who received autologous human CD40 ligand and interleukin-2 (hCD40L/IL-2) gene-modified tumor cells as part of a tumor vaccine study. Vaccinated patients showed an increase in B-CLL-reactive T cells followed by a corresponding decline in circulating CD5(+) CD19(+) SP cells. T-cell lines and clones generated from vaccinated patients specifically recognized B-CLL SP tumor cells.