sirolimus and parthenolide

Although multidrug approaches to cancer therapy are common, few strategies are based on rigorous scientific principles. Rather, drug combinations are largely dictated by empirical or clinical parameters. In the present study we developed a strategy for rational design of a regimen that selectively targets human acute myelogenous leukemia (AML) stem cells. As a starting point, we used parthenolide, an agent shown to target critical mechanisms of redox balance in primary AML cells. Next, using proteomic, genomic, and metabolomic methods, we determined that treatment with parthenolide leads to induction of compensatory mechanisms that include up-regulated NADPH production via the pentose phosphate pathway as well as activation of the Nrf2-mediated oxidative stress response pathway. Using this knowledge we identified 2-deoxyglucose and temsirolimus as agents that can be added to a parthenolide regimen as a means to inhibit such compensatory events and thereby further enhance eradication of AML cells. We demonstrate that the parthenolide, 2-deoxyglucose, temsirolimus (termed PDT) regimen is a potent means of targeting AML stem cells but has little to no effect on normal stem cells. Taken together our findings illustrate a comprehensive approach to designing combination anticancer drug regimens.

Topics: Antineoplastic Combined Chemotherapy Protocols; Deoxyglucose; Female; Gene Expression Regulation, Leukemic; Humans; Leukemia, Myeloid, Acute; Male; NADP; Neoplasm Proteins; Neoplastic Stem Cells; NF-E2-Related Factor 2; Sesquiterpenes; Sirolimus; Up-Regulation

To maintain bone mass turnover and bone mineral density (BMD), bone marrow (BM) mesenchymal stem cells (MSCs) are constantly recruited and subsequently differentiated into osteoblasts. HIV-infected patients present lower BMD than non-HIV infected individuals and a higher prevalence of osteopenia/osteoporosis. In antiretroviral treatment (ART)-naive patients, encoded HIV proteins represent pathogenic candidates. They are released by infected cells within BM and can impact on neighbouring cells. In this study, we tested whether HIV proteins Tat and/or Nef could induce senescence of human BM-MSCs and reduce their capacity to differentiate into osteoblasts. When compared to nontreated cells, MSCs chronically treated with Tat and/or Nef up to 30 days reduced their proliferative activity and underwent early senescence, associated with increased oxidative stress and mitochondrial dysfunction. The antioxidant molecule N-acetyl- cysteine had no or minimal effects on Tat- or Nef-induced senescence. Tat but not Nef induced an early increase in NF-κB activity and cytokine/chemokine secretion. Tat-induced effects were prevented by the NF-κB inhibitor parthenolide, indicating that Tat triggered senescence via NF-κB activation leading to oxidative stress. Otherwise, Nef- but not Tat-treated cells displayed early inhibition of autophagy. Rapamycin, an autophagy inducer, reversed Nef-induced senescence and oxidative stress. Moreover, Tat+Nef had cumulative effects. Finally, Tat and/or Nef decreased the MSC potential of osteoblastic differentiation. In conclusion, our in vitro data show that Tat and Nef could reduce the number of available precursors by inducing MSC senescence, through either enhanced inflammation or reduced autophagy. These results offer new insights into the pathophysiological mechanisms of decreased BMD in HIV-infected patients.

Topics: Acetylcysteine; Antioxidants; Autophagy; Bone Marrow Cells; Cell Differentiation; Cell Proliferation; Cellular Senescence; Gene Expression Regulation; Humans; Interleukin-6; Interleukin-8; Mesenchymal Stem Cells; Mitochondria; nef Gene Products, Human Immunodeficiency Virus; NF-kappa B; Osteoblasts; Osteocalcin; Oxidative Stress; Primary Cell Culture; Recombinant Proteins; Sesquiterpenes; Signal Transduction; Sirolimus; tat Gene Products, Human Immunodeficiency Virus

We have previously shown that the plant-derived compound parthenolide (PTL) can impair the survival and leukemogenic activity of primary human acute myeloid leukemia (AML) stem cells. However, despite the activity of this agent, PTL also induces cellular protective responses that likely function to reduce its overall cytotoxicity. Thus, we sought to identify pharmacologic agents that enhance the antileukemic potential of PTL. Toward this goal, we used the gene expression signature of PTL to identify compounds that inhibit cytoprotective responses by performing chemical genomic screening of the Connectivity Map database. This screen identified compounds acting along the phosphatidylinositol 3-kinase and mammalian target of rapamycin pathways. Compared with single agent treatment, exposure of AML cells to the combination of PTL and phosphatidylinositol 3-kinase/mammalian target of rapamycin inhibitors significantly decreased viability of AML cells and reduced tumor burden in vitro and in murine xenotransplantation models. Taken together, our data show that rational drug combinations can be identified using chemical genomic screening strategies and that inhibition of cytoprotective functions can enhance the eradication of primary human AML cells.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Biomarkers, Tumor; Blotting, Western; Bone Marrow; Cell Proliferation; Cells, Cultured; Drug Synergism; Enzyme Inhibitors; Flow Cytometry; Gene Expression Profiling; Humans; Leukemia, Myeloid, Acute; Mice; Mice, Inbred NOD; Mice, SCID; Oligonucleotide Array Sequence Analysis; Phosphatidylinositol 3-Kinases; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Sesquiterpenes; Sirolimus; TOR Serine-Threonine Kinases