Circumvention of chemotherapy-induced myelosuppression by transfer of the mdr1 gene

The Protective Effect of Sweet Potato Root Tuber on Chemotherapy-Induced Thrombocytopenia

SCOPE

Sweet potato (Ipomoea batatas L.) is one of the leading crops worldwide, containing high nutritional components such as fiber and polyphenols. Root tuber of Simon 1 (SIMON), a cultivar of sweet potato, is a folk food in China with a hemostasis function but lacking experimental data support.

METHODS AND RESULTS

Now the protective effect of SIMON on chemotherapy-induced thrombocytopenia (CIT), a serious complication of cancer treatment, is investigated for the first time by a CIT mouse model induced by intraperitoneal injection of carboplatin. As a result, SIMON raises the number of peripheral platelets, white blood cells, and bone marrow nucleated cells in CIT mice significantly. Besides, carboplatin-induced atrophy of the thymus, spleen, and disordered metabolism of the inflammatory immune system and glycerophospholipids are also reversed by SIMON. Phytochemical analysis of SIMON indicates 16 compounds including eight phenolic derivatives, which might be associated with its anti-CIT bioactivity.

CONCLUSION

Sweet potato (SIMON) may be an efficient function food in the prevention of bleeding disorders.

Computational analysis of cancer genome sequencing data

Distilling biologically meaningful information from cancer genome sequencing data requires comprehensive identification of somatic alterations using rigorous computational methods. As the amount and complexity of sequencing data have increased, so has the number of tools for analysing them. Here, we describe the main steps involved in the bioinformatic analysis of cancer genomes, review key algorithmic developments and highlight popular tools and emerging technologies. These tools include those that identify point mutations, copy number alterations, structural variations and mutational signatures in cancer genomes. We also discuss issues in experimental design, the strengths and limitations of sequencing modalities and methodological challenges for the future.

Effect of human WEE1 and stem cell factor on human CD34+ umbilical cord blood cell damage induced by chemotherapeutic agents

Myelosuppression is one of the major side-effects of most anticancer drugs. To achieve myeloprotection, one bicistronic vector encoding anti-apoptotic protein human WEE1 (WEE1Hu) and proliferation-stimulating stem cell factor (SCF) was generated. In this study, we selected human umbilical cord blood CD34+ cells as the in vitro model in an attempt to investigate whether WEE1Hu, rather than conventional drug-resistant genes, can be introduced to rescue cells from the damage by chemotherapeutic agents such as cisplatin, adriamycin, mitomycin-c and 5-fluorouracil. Cell viability and cytotoxicity assay, colony-forming units in culture assay and externalization of phospholipid phosphatidylserine analysis showed that the expression of WEE1Hu and SCF in CD34+ cells provided the cells with some protection. These findings suggest that the expression of WEE1Hu and SCF might rescue CD34+ cells from chemotherapy-induced myelosuppression.

Optimization of multidrug resistance 1 gene transfer confers chemoprotection to human hematopoietic cells engrafted in immunodeficient mice

OBJECTIVE

To investigate whether an optimization of MDR1 gene transfer protocol would result in stable hematopoietic stem cell (HSC) engraftment and myeloprotection in non-obese diabetic/severe combined immunodeficient (NOD/SCID) mice after paclitaxel chemotherapy.

METHODS

We transplanted freshly isolated CD34+ cells or MDR1-transduced CD34+ cells derived from human umbilical cord blood (UCB) into sublethally irradiated NOD/SCID mice. Twenty-eight days after transplantation, mice received paclitaxel chemotherapy and peripheral blood (PB) was collected for analysis of WBC, RBC and PLT counts once every week.

RESULTS

We found that MDR1-transduced human hematopoietic cells could facilitate hematopoietic recovery and completely reconstitute hematopoiesis in mice as well as freshly isolated CD34+ cells. Mice transplanted with MDR1-transduced human hematopoietic cells were protected from paclitaxel chemotherapy with higher survival rate and higher level of WBC counts and RBC counts compared with mice transplanted with untransduced HSCs. We also demonstrated that hematopoietic cells transduced with MDR1 gene were enriched in vivo after paclitaxel chemotherapy determined by the higher percentage of human Rh-123(dull) CD45+ cells in bone marrow of mice.

CONCLUSION

Our results demonstrated successful chemoprotection against myelosuppression in mice by MDR1-transduced repopulating human hematopoietic cells with an optimized transduction protocol.

Chemoprotection effect of multidrug resistance 1 (MDR1) gene transfer to hematopoietic progenitor cells and engrafted in mice with cancer allows intensified chemotherapy

Increasing the proportion of bone marrow cells expression human multidrug resistance (MDR) 1 gene to prevent or circumvent bone morrow toxicity from chemotherapy agent is a high priority of dose intensification protocols. In this study, we have used a BALB/c mouse tumor-bearing model to investigate the chemoprotection effect of MDR1 gene by transfecting retroviral vectors containing and expressing the MDR gene in vivo. Hematopoietic progenitor cells served as a target of MDR1 gene transfer by the mediation of retrovirus vector and engrafted into the BALB/c mice with 60Co-gamma ray exposure in advance. Doxorubicin (5, 10, and 20 mg/kg) suppressed tumor growth of the xenograft significantly in dose-dependence mode if supported by suitable peripheral WBC. WBCs count revealed that the mice that had received gene-transduced cells showed a significant increase in WBCs count compared with their gene-transduced-naive counterparts. The function and expression of MDR1 gene were detected by flow cytometry, RT-PCR and immunohistochemistry (IC) method. MDRl mRNA expression could be detected in BM. Spleens contained measurable amounts of MDRl mRNA. Tail vein blood and tumor tissue detected MDRl DNA but no MDRl mRNA expression. FACS analysis of infected BM cells obtained 6 weeks later showed high levels of P-gp function. Based on these results we conclude that cytostatic drug resistance gene therapy may provide some degree of chemoprotection so can increase the chemotherapy dose to kill tumor cells.

New positron emission tomography tracer [(11)C]carvedilol reveals P-glycoprotein modulation kinetics

Imaging of P-glycoprotein (P-gp) function in the blood-brain barrier (BBB) may support development of strategies, which will improve drug delivery to the brain. [(11)C]verapamil has been developed as a positron emission tomography (PET) tracer, to image P-gp function in vivo. Ideally, for the purpose of brain imaging, tracers should have a log P between 0.9 and 2.5. The beta-receptor antagonist carvedilol is a P-gp substrate with a log P=2.0, and can be labeled with [(11)C]. The aim of this study was to determine whether the P-gp substrate [(11)C]carvedilol can be used as a PET tracer for visualisation and quantification of the P-gp function in the BBB. Cellular [(11)C]carvedilol accumulation in GLC(4), GLC(4)/P-gp, and GLC(4)/Adr cells increased three-fold in the GLC(4)/P-gp cells after pretreatment with cyclosporin A (CsA) whereas no effect of MK571 could be determined in the GLC(4)/Adr cells. Ex vivo [(11)C]carvedilol biodistribution studies showed that [(11)C]carvedilol uptake in the brain was increased by CsA. [(11)C]carvedilol uptake in other organs was not affected by CsA. Autoradiography studies of rat brains showed that [(11)C]carvedilol was homogeneously distributed over the brain and that pretreatment with CsA increased [(11)C]carvedilol uptake. In vivo PET experiments were performed with and without P-gp modulation by CsA. P-gp mediated transport was quantified by Logan analysis of the PET data, calculating the distribution volume (DV) of [(11)C]carvedilol in the brain. Logan analysis resulted in excellent fits, revealing that [(11)C]carvedilol is not trapped in the brain. Brain DV of [(11)C]carvedilol showed a dose-dependent increase of maximal three-fold after CsA pretreatment. Above 15 mg kg(-1), no change in DV was found. Compared to [(11)C]verapamil less CsA was needed to reach maximal DV, suggesting that [(11)C]carvedilol kinetics is a more sensitive tool to in vivo measure P-gp function.

Chemoprotection effect of retroviral vector encoding multidrug resistance 1 gene to allow intensified chemotherapy in vivo

Increasing the expression of human multidrug resistance (MDR) 1 gene in bone marrow cells to prevent or circumvent bone morrow toxicity from chemotherapy agent is a high priority of dose intensification protocols. In this study, we have used a tumor-bearing model to investigate the chemoprotection effect of MDR1 gene by transfecting retroviral vectors containing and expressing the MDR gene in vivo. Hematopoietic progenitor cells were served as target of MDR1 gene transferred by the mediation of retrovirus vector and engrafted into the BALB/c mice with 60Co-gamma ray exposure in advance. Doxorubicin (5, 10, and 20 mg/kg) suppressed tumor growth of the xenograft significantly in a dose-dependence mode if supported by suitable peripheral WBC. WBC count revealed that the mice that had received gene-transduced cells showed a significant increase in WBC count compared with their gene-transduced naive counterparts. The function and expression of MDR1 gene were detected by flow cytometry, RT-PCR, and immunohistochemistry (IC) method. MDRl mRNA expression could be detected in BM. Spleens contained measurable amounts of MDRl mRNA. Tail vein blood and tumor tissue detected MDRl DNA but no MDRl mRNA expression. FACS analysis of infected BM cells obtained 6 weeks later showed high levels of P-gp function. Based on these results we conclude that cytostatic drug resistance gene therapy may provide some degree of chemoprotection and so can increase the chemotherapy dose to kill tumor cells.

Strategies for cancer gene therapy

Gene therapy offers new opportunities for cancer treatment and prevention through the use of targeted, relatively nontoxic treatments that can identify, disable, and destroy malignant cells. This article reviews the principles behind oncogene inactivation, tumor suppressor gene replacement, inhibition of angiogenesis, immunopotentiation, molecular chemotherapy, and addition of drug resistance genes. The adcantages and limitations of viral and nonviral vectors for delivery of the therapeutic genes are presented.

MDR1 gene expression in NOD/SCID repopulating cells after retroviral gene transfer under clinically relevant conditions

We have adapted a recently published protocol for retroviral gene transfer into hematopoietic cells [A. J. Schilz et al. (1998) Blood 92: 3163-3171] with respect to clinical requirements such as large-volume vector stock generation, adequate cell source, high cell numbers, and serum-free conditions. We present data on transduction efficacy and expression of the multidrug resistance 1 (MDR1) gene in human CD34(+) cells from mobilized peripheral blood (PB) mediated by a gibbon ape leukemia virus (GALV)-pseudotyped retroviral vector. Using a 1-day cytokine-mediated prestimulation, consisting of human interleukin (IL)-3, IL-6, stem cell factor (SCF), Flt-3 ligand (FL), and thrombopoietin (TPO), followed by a 3-day transduction procedure, we were able to detect up to 51% CD34(+) cells expressing MDR1. Xenotransplantation of transduced cells into NOD/LtSz-scid/scid (NOD/SCID) mice resulted in a mean engraftment level of 23% (0.1 to 87%). As shown by quantitative PCR analysis, a mean of 12.7% (range 0.3 to 55%) of the engrafted human cells in the bone marrow of chimeric mice contained the MDR1 cDNA. Furthermore, enhanced expression of MDR1 above control levels was detected in up to 15% of the engrafted human cell population. Our data suggest that NOD/SCID repopulating cells derived from mobilized PB can be transduced efficiently with existing retroviral vector systems under clinically applicable conditions.

Quantitative assessment of retroviral transfer of the human multidrug resistance 1 gene to human mobilized peripheral blood progenitor cells engrafted in nonobese diabetic/severe combined immunodeficient mice

Mobilized peripheral blood progenitor cells (PBPC) are a potential target for the retrovirus-mediated transfer of cytostatic drug-resistance genes. We analyzed nonobese diabetic/severe combined immunodeficient (NOD/SCID) mouse-repopulating CD34+ PBPC from patients with cancer after retroviral transduction in various cytokine combinations with the hybrid vector SF-MDR, which is based on the Friend mink cell focus-forming/murine embryonic stem-cell virus and carries the human multidrug resistance 1 (MDR1) gene. Five to 13 weeks after transplantation of CD34+ PBPC into NOD/SCID mice (n = 84), a cell dose-dependent multilineage engraftment of human leukocytes up to an average of 33% was observed. The SF-MDR provirus was detected in the bone marrow (BM) and in its granulocyte fractions in 96% and 72%, respectively, of chimeric NOD/SCID mice. SF-MDR provirus integration assessed by quantitative real-time polymerase chain reaction (PCR) was optimal in the presence of Flt-3 ligand/thrombopoietin/stem-cell factor, resulting in a 6-fold (24% ± 5% [mean ± SE]) higher average proportion of gene-marked human cells in NOD/SCID mice than that achieved with IL-3 alone (P < .01). A population of clearly rhodamine-123dull human myeloid progeny cells could be isolated from BM samples from chimeric NOD/SCID mice. On the basis of PCR and rhodamine-123 efflux data, up to 18% ± 4% of transduced cells were calculated to express the transgene. Our data suggest that the NOD/SCID model provides a valid assay for estimating the gene-transfer efficiency to repopulating human PBPC that may be achievable in clinical autologous transplantation. P-glycoprotein expression sufficient to prevent marrow aplasia in vivo may be obtained with this SF-MDR vector and an optimized transduction protocol.

Biochemical, genetic, and metabolic adaptations of tumor cells that express the typical multidrug-resistance phenotype. Reversion by new therapies

Among the genetic and metabolic alterations that cancer cells undergo, several allow their survival under extreme environmental conditions. The resulting aberrant metabolism is compatible with tumor progression at the expenses of high energy needs, especially for maintaining high division rate. When treated with chemotherapeutic drugs many cancer cells take advantage of their ability to develop a resistance phenotype, as part of an adaptative mechanism. Two main actors of this multidrug phenotype (MDR) are represented by the P-glycoprotein and by the more recently discovered multidrug-resistance associated protein (MRP), two membrane proteins of the ABC superfamily of transporters that can extrude chemotherapeutic drugs under an ATP-dependent mechanism. We will briefly review the major metabolic aberrations that several cancers develop, followed by the molecular, genetic, structural, and functional aspects related mainly to P-glycoprotein, with a concern for the regulation of mdr gene expression. We will point out the role that membrane cholesterol may play in the MDR phenotype, relate this phenotype to bioenergetic considerations, and review the ways of modulating it by the use of new therapeutic approaches.

In vivo drug-selectable genes: a new concept in gene therapy

Chemoresistance genes, initially considered to be a major impediment to the successful treatment of cancer, may become useful tools for gene therapy of cancer and of genetically determined disorders. Various target cells are rendered resistant to anticancer drugs by transfer of chemoresistance genes encoding P-glycoprotein, the multidrug resistance-associated protein-transporter, dihydrofolate reductase, glutathione-S-transferase, O6-alkylguanine DNA alkyltransferase, or aldehyde reductase. These genes can be used for selection in vivo because of the pharmacology and pharmacokinetics of their substrates. In contrast, several other selectable marker genes conferring resistance to substrates like neomycin or hygromycin can only be utilized in tissue culture. Possible applications for chemoresistance genes include protection of bone marrow and other organs from adverse effects caused by the toxicity of chemotherapy. Strategies have also been developed to introduce and overexpress nonselectable genes in target cells by cotransduction with chemoresistance genes. Thereby expression of both transgenes can be increased following selection with drugs. Moreover, treatment with chemotherapeutic agents should restore transgene expression when or if expression levels decrease after several weeks or months. This approach may improve the efficacy of somatic gene therapy of hematopoietic disorders which is hampered by low or unstable gene expression in progenitor cells. In this article we review preclinical studies in tissue culture and animal models, and ongoing clinical trials on transfer of chemoresistance genes to hematopoietic precursor cells of cancer patients.

Pharmaceutical approach to somatic gene therapy

The pharmaceutical approach to somatic gene therapy is based on consideration of a gene as a chemical entity with specific physical, chemical and colloidal properties. The genes that are required for gene therapy are large molecules (> 1 x 10(6) Daltons, > 100 nm diameter) with a net negative charge that prevents diffusion through biological barriers such as an intact endothelium, the plasma membrane or the nuclear membrane. New methods for gene therapy are based on increasing knowledge of the pathways by which DNA may be internalized into cells and traffic to the nucleus, pharmaceutical experience with particulate drug delivery systems, and the ability to control gene expression with recombined genetic elements. This article reviews two themes in the development of gene therapies: first, the current approaches involving the administration of cells, viruses and plasmid DNA; second, the emerging pharmaceutical approach to gene therapy based on the pharmaceutical characteristics of DNA itself and methods for advanced drug delivery.

Prospects for human gene therapy

Gene therapy is a rapidly developing discipline both in experimental and clinical medicine. This paper summarizes the areas where gene therapy is expected to be beneficial and describes the most frequently applied methods of gene transfer and their use in clinical trials.

Hematopoietic stem cell transplantation for cancer therapy

Bone marrow transplantation has become well established in the treatment of malignant disorders. High-dose chemotherapy with hematopoietic stem cell support is widely used for most hematological malignancies, as well as for some solid tumors. In the light of recent developments in blood progenitor cell harvest, there have been clinical trials with autologous and allogeneic transplants. In particular, the availability of large numbers of blood stem cells, mobilized by granulocyte colony-stimulating factor and collected by leukapheresis, has made it possible to overcome histocompatibility barriers in HLA-mismatched leukemia patients. Other recent developments include new methods for blood progenitor cells mobilization and ex vivo expansion, the use of umbilical cord blood as an alternative source of stem cells, and molecular techniques that may, in the future, provide other modalities of purging tumor cells from autologous grafts.