1
|
Cho Y, Kim YK. Cancer Stem Cells as a Potential Target to Overcome Multidrug Resistance. Front Oncol 2020; 10:764. [PMID: 32582535 PMCID: PMC7280434 DOI: 10.3389/fonc.2020.00764] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Accepted: 04/21/2020] [Indexed: 12/21/2022] Open
Abstract
Multidrug resistance (MDR), which is a significant impediment to the success of cancer chemotherapy, is attributable to various defensive mechanisms in cancer. Initially, overexpression of ATP-binding cassette (ABC) transporters such as P-glycoprotein (P-gp) was considered the most important mechanism for drug resistance; hence, many investigators for a long time focused on the development of specific ABC transporter inhibitors. However, to date their efforts have failed to develop a clinically applicable drug, leaving only a number of problems. The concept of cancer stem cells (CSCs) has provided new directions for both cancer and MDR research. MDR is known to be one of the most important features of CSCs and thus plays a crucial role in cancer recurrence and exacerbation. Therefore, in recent years, research targeting CSCs has been increasing rapidly in search of an effective cancer treatment. Here, we review the drugs that have been studied and developed to overcome MDR and CSCs, and discuss the limitations and future perspectives.
Collapse
Affiliation(s)
| | - Yong Kee Kim
- Research Institute of Pharmaceutical Sciences, College of Pharmacy, Sookmyung Women's University, Seoul, South Korea
| |
Collapse
|
2
|
Gillet JP, Macadangdang B, Fathke RL, Gottesman MM, Kimchi-Sarfaty C. The development of gene therapy: from monogenic recessive disorders to complex diseases such as cancer. Methods Mol Biol 2009; 542:5-54. [PMID: 19565894 DOI: 10.1007/978-1-59745-561-9_1] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
During the last 4 decades, gene therapy has moved from preclinical to clinical studies for many diseases ranging from monogenic recessive disorders such as hemophilia to more complex diseases such as cancer, cardiovascular disorders, and human immunodeficiency virus (HIV). To date, more than 1,340 gene therapy clinical trials have been completed, are ongoing, or have been approved in 28 countries, using more than 100 genes. Most of those clinical trials (66.5%) were aimed at the treatment of cancer. Early hype, failures, and tragic events have now largely been replaced by the necessary stepwise progress needed to realize clinical benefits. We now understand better the strengths and weaknesses of various gene transfer vectors; this facilitates the choice of appropriate vectors for individual diseases. Continuous advances in our understanding of tumor biology have allowed the development of elegant, more efficient, and less toxic treatment strategies. In this introductory chapter, we review the history of gene therapy since the early 1960s and present in detail two major recurring themes in gene therapy: (1) the development of vector and delivery systems and (2) the design of strategies to fight or cure particular diseases. The field of cancer gene therapy experienced an "awkward adolescence." Although this field has certainly not yet reached maturity, it still holds the potential of alleviating the suffering of many individuals with cancer.
Collapse
Affiliation(s)
- Jean-Pierre Gillet
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | | | | | | | | |
Collapse
|
3
|
Abstract
The concept of introducing genes into human cells for therapeutic purposes developed nearly 50 years ago as diseases due to defects in specific genes were recognized. Development of recombinant DNA techniques in the 1970s and their application to the study of mouse tumor viruses facilitated the assembly of the first gene transfer vectors. Vectors of several different types have now been developed for specific applications and over the past decade, efficacy has been demonstrated in many animal models. Clinical trials began in 1989 and by 2002 there was unequivocal evidence that children with severe combined immunodeficiency could be cured by gene transfer into primitive hematopoietic cells. Emerging from these successful trials was the realization that proto-oncogene activation by retroviral integration could contribute to leukemia. Much current effort is focused on development of safer vectors. Successful gene therapy applications have also been developed for control of graft-versus-host disease and treatment of various viral infections, leukemias, and lymphomas. The hemophilias seem amenable to gene therapy intervention and informative clinical trials have been conducted. The hemoglobin disorders, an early target for gene therapy, have proved particularly challenging although ongoing research is yielding new information that may ultimately lead to successful clinical trials.
Collapse
|
4
|
Abstract
Gene therapy aims to correct the disease process by restoring, modifying or enhancing cellular functions through the introduction of a functional gene into a target cell. Whilst the concept of gene therapy is simple, the practical reality of translating this new technology to the clinic has proven to be more difficult than first imagined. Recent progress in gene transfer technology has shown impressive clinical success in infants with immunodeficiency. However, two of these children have subsequently developed leukaemia as a result of insertional mutagenesis, thus, raising important questions about the safety of genetic therapeutics. This article reviews the current status of gene therapy and outlines the challenges faced by this emerging technology that holds so much promise for many suffering from catastrophic disorders.
Collapse
Affiliation(s)
- Amit C Nathwani
- Department of Haematology, University College London, London, UK.
| | | | | |
Collapse
|
5
|
O'Shaughnessy JA. Joyce Ann O'Shaughnessy, MD: A Conversation with the Editor. Proc (Bayl Univ Med Cent) 2004. [DOI: 10.1080/08998280.2004.11927967] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
|
6
|
Vollweiler JL, Zielske SP, Reese JS, Gerson SL. Hematopoietic stem cell gene therapy: progress toward therapeutic targets. Bone Marrow Transplant 2003; 32:1-7. [PMID: 12815471 DOI: 10.1038/sj.bmt.1704081] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The concept of hematopoietic stem cell gene therapy is as exciting as that of stem cell transplantation itself. The past 20 years of research have led to improved techniques for transferring and expressing genes in hematopoietic stem cells and preclinical models now routinely indicate the ease with which new genes can be expressed in repopulating stem cells of multiple species. Both modified murine oncoretroviruses and lentiviruses transmit genes into the genome of hematopoietic stem cells and allow expression in the host following transplantation. Using oncoretroviruses, therapeutic genes for severe combined immunodeficiency, common variable gamma chain immunodeficiency, chronic granulomatous disease, Hurler's and Gaucher's Disease have all been used clinically with only modest success except for the patients with immunodeficiency in whom a partial T-cell chimerism has been dramatic. Since stem cell selection in vivo appears important to the therapeutic success of gene transfer, drug resistance selection, most recently using the MGMT gene, has been developed and appears to be safe. Future trials combining a drug resistance and therapeutic gene are planned, as are trials using safety-modified lentiviruses. The therapeutic potential of hematopoietic stem cell gene therapy, particularly given recent advances in stem cell plasticity, remains an exceptionally exciting area of clinical research.
Collapse
Affiliation(s)
- J L Vollweiler
- Division of Hematology-Oncology, Comprehensive Cancer Center at University Hospitals of Cleveland, Case Western Reserve University School of Medicine, USA
| | | | | | | |
Collapse
|
7
|
Lee CG, Vieira WD, Pastan I, Gottesman MM. An episomally maintained MDR1 gene for gene therapy. Hum Gene Ther 2001; 12:945-53. [PMID: 11387059 DOI: 10.1089/104303401750195908] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Potential applications of the MDR1 multidrug transporter in gene therapy include protecting sensitive bone marrow cells against cytotoxic drugs during cancer chemotherapy and serving as a dominant selectable marker when coexpressed with a corrective passenger gene. To address safety concerns associated with integrating viral systems, such as retroviruses, we tested the feasibility of maintaining a nonvirally delivered MDR1 gene (pEpiHaMA) episomally. An MDR1 vector containing the Epstein-Barr virus (EBV) origin of replication (OriP) and its nuclear retention protein (EBNA-1) was transfected into human (KB-3-1) cells. MDR1 was expressed at a higher level in cells carrying the episomal vector, pEpiHaMA, compared with the vector lacking sequences needed for episomal maintenance (pHaMA). Furthermore, more drug-resistant KB-3-1 colonies were obtained on selection after transfection with pEpiHaMA. These observations correlated with longer maintenance of episomes in cells transfected with pEpiHaMA. In addition, episomes could still be recovered for more than 1 month from tumor explants in nude mice that were injected with pEpiHaMA-liposome complexes after drug selection, suggesting that these constructs can be maintained extrachromosomally in vivo.
Collapse
Affiliation(s)
- C G Lee
- Department of Biochemistry, National University of Singapore, Singapore
| | | | | | | |
Collapse
|
8
|
Elwood NJ, Smith CA. Current status of retroviral vector mediated gene transfer into human hematopoietic stem cells. Leuk Lymphoma 2001; 41:465-82. [PMID: 11378565 DOI: 10.3109/10428190109060338] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Genetic modification of hematopoietic stem cells (HSCs) has been proposed as a treatment strategy for a variety of hematologic diseases, tracking marked cells or conferring resistance to chemotherapeutic agents. Despite early enthusiasm, the results of clinical studies involving gene transfer into HSCs has not resulted in therapeutic benefits for the vast majority of treated patients. This review describes the limitations and advances that have been made in the areas of gene transfer vectors, identification of the appropriate HSCs to target for genetic modifications and the methods used to perform gene transfer.
Collapse
Affiliation(s)
- N J Elwood
- Center for Genetic and Cellular Therapies, Department of Medicine, Box 2601, Duke University Medical Center, Durham, NC 27710, USA
| | | |
Collapse
|
9
|
Elwood NJ, Smith CA. Current status of retroviral vector mediated gene transfer into human hematopoietic stem cells. Leuk Lymphoma 2001; 41:1-18. [PMID: 11342353 DOI: 10.3109/10428190109057950] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Genetic modification of hematopoietic stem cells (HSCs) has been proposed as a treatment strategy for a variety of hematologic diseases, tracking marked cells or conferring resistance to chemotherapeutic agents. Despite early enthusiasm, the results of clinical studies involving gene transfer into HSCs have not resulted in therapeutic benefits for the vast majority of treated patients. This review describes the limitations and advances that have been made in the areas of gene transfer vectors, identification of the appropriate HSCs to target for genetic modifications and the methods used to perform gene transfer.
Collapse
Affiliation(s)
- N J Elwood
- Center for Genetic and Cellular Therapies, Department of Medicine, Box 2601, Duke University Medical Center, Durham, NC 27710, USA
| | | |
Collapse
|
10
|
Takebe N, Zhao SC, Adhikari D, Mineishi S, Sadelain M, Hilton J, Colvin M, Banerjee D, Bertino JR. Generation of dual resistance to 4-hydroperoxycyclophosphamide and methotrexate by retroviral transfer of the human aldehyde dehydrogenase class 1 gene and a mutated dihydrofolate reductase gene. Mol Ther 2001; 3:88-96. [PMID: 11162315 DOI: 10.1006/mthe.2000.0236] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The genetic transfer of drug resistance to hematopoietic cells is an attractive approach to overcoming myelosuppression caused by high-dose chemotherapy. Because cyclophosphamide (CTX) and methotrexate (MTX) are commonly used non-cross-resistant drugs, generation of dual drug resistance in hematopoietic cells that allows dose intensification may increase anti-tumor effects and circumvent the emergence of drug-resistant tumors. We constructed a retroviral vector containing both a human cytosolic ALDH-1 cDNA and a human doubly mutated DHFR cDNA (Phe22/Ser31; termed F/S in the description of constructs) to generate increased resistance to both CTX and MTX. Infection of NIH3T3 cells resulted in increased resistance to both 4-hydroperoxycyclophosphamide (4HC) (1.9 +/- 0.1-fold) and MTX (73 +/- 2.8-fold). Transduced human CD34(+) enriched hematopoietic progenitor cells were also resistant to both 4HC and MTX by CFU-GM readout. Lethally irradiated mice transplanted with SFG-ALDH-IRES-F/S or mock-transduced bone marrow cells were treated with high-dose pulse CTX or high-dose CTX/MTX. Animals receiving marrow not transduced with ALDH-1 or mutated DHFR cDNA died from CTX or CTX/MTX toxicity, whereas mice transduced with ALDH-1 and mutated DHFR cDNA-containing marrow were able to tolerate the same doses of CTX or CTX/MTX treatment posttransplant. These data taken together indicate that ALDH-1 overexpression and mutant DHFR increased both 4HC and MTX resistance in vitro and in the in vivo mouse model. This construct may be useful for protecting patients from high-dose CTX- and MTX-induced myelosuppression.
Collapse
Affiliation(s)
- N Takebe
- Department of Medicine, Program of Molecular Pharmacology and Experimental Therapeutics, Sloan-Kettering Institute, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue No. 78, New York, New York 10021, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Montemurro F, Ueno NT, Rondón G, Aglietta M, Champlin RE. High-dose chemotherapy with hematopoietic stem-cell transplantation for breast cancer: current status, future trends. Clin Breast Cancer 2000; 1:197-209; discussion 210. [PMID: 11899644 DOI: 10.3816/cbc.2000.n.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
High-dose chemotherapy with hematopoietic stem-cell transplantation (HDC/HSCT) has been extensively studied as a potential treatment for breast cancer. A literature search of MEDLINE from January 1990 through December 1999 identified 497 published full papers. Of these articles, 120 reported the results of clinical trials, 78 were reviews, and 299 reported on issues related to the technology of peripheral stem cells, supportive care, and toxicity. The phase II data must be interpreted with caution, as it is subject to selection bias; transplant recipients tended to be younger, rigorously staged, and selected to be chemotherapy responsive. There continues to be controversy regarding the role of high-dose therapy in this disease. Only a few fully published randomized trials are available; these studies were powered only to detect large differences in survival and no benefit was shown. Several large controlled trials are either in progress or are too early for definitive analysis. This review analyzes the current literature on HDC/HSCT for breast cancer, identifying prognostic factors and discussing ongoing research designed to improve antitumor effects.
Collapse
Affiliation(s)
- F Montemurro
- Department of Oncology and Hematology, University of Turin, Institute for Cancer Research and Treatment, Candiolo, Turin, Italy.
| | | | | | | | | |
Collapse
|
12
|
Matsunaga T, Sakamaki S, Kuga T, Kuroda H, Kusakabe T, Akiyama T, Konuma Y, Hirayama Y, Kobune M, Kato J, Sasaki K, Kogawa K, Koyama R, Niitsu Y. GST-pi gene-transduced hematopoietic progenitor cell transplantation overcomes the bone marrow toxicity of cyclophosphamide in mice. Hum Gene Ther 2000; 11:1671-81. [PMID: 10954901 DOI: 10.1089/10430340050111322] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Autologous transplantation of bone marrow cells (BMCs) transduced with the multidrug resistance 1 (MDR1) gene or dihydrofolate reductase (DHFR) gene has already been applied in clinical chemoprotection trials. However, anticancer drugs frequently used in high-dose chemotherapy (HDC), such as alkylating agents, are not relevant to MDR1 or DHFR gene products. In this context, we have previously reported that glutathione S-transferase-pi (GST-pi) gene-transduced human CD34(+) cells showed resistance in vitro against 4-hydroperoxicyclophosphamide, an active form of cyclophosphamide (CY). In the present study, a subsequent attempt was made in a murine model to evaluate the effectiveness of transplantation of GST-pi-transduced BMCs to protect bone marrow against high-dose CY. The gene transfection was carried out retrovirally, employing a recombinant fibronectin fragment. Transfection efficiency into CFU-GM was 30%. After the transplantation, recipient mice (GST-pi mice) received three sequential courses of high-dose CY. As the chemotherapy courses advanced, both shortening of recovery period from WBC nadir and shallowing of WBC nadir were observed. In contrast to the fact that three of seven control mice died, possibly due to chemotoxicity, all seven GST-pi mice were alive after the third course, at which point the vector GST-pi gene was detected in 50% of CFU-GM derived from their BMCs and peripheral blood mononuclear cells. When BMCs obtained from these seven mice were retransplanted into secondary recipient mice, 20% of CFU-GM from BMCs showed positive signals for vector GST-pi DNA after 6 months. These data indicate that the GST-pi gene can confer resistance to bone marrow against CY by being transduced into long-term repopulating cells.
Collapse
Affiliation(s)
- T Matsunaga
- Fourth Department of Internal Medicine, Sapporo Medical University School of Medicine, Japan
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Abstract
Alkylating agents represent a highly cytotoxic class of chemotherapeutic compounds that are extremely effective anti-tumor agents. Unfortunately, alkylating agents damage both malignant and non-malignant tissues. Bone marrow is especially sensitive to damage by alkylating agent chemotherapy, and is a dose-limiting tissue when treating cancer patients. One strategy to overcome bone marrow sensitivity to alkylating agent exposure involves gene transfer of the DNA repair protein O(6)-methylguanine DNA methyltransferase (O(6)MeG DNA MTase) into bone marrow cells. O(6)MeG DNA MTase is of particular interest because it functions to protect against the mutagenic, clastogenic and cytotoxic effects of many chemotherapeutic alkylating agents. By increasing the O(6)MeG DNA MTase repair capacity of bone marrow cells, it is hoped that this tissue will become alkylation resistant, thereby increasing the therapeutic window for the selective destruction of malignant tissue. In this review, the field of O(6)MeG DNA MTase gene transfer into bone marrow cells will be summarized with an emphasis placed on strategies used for suppressing the deleterious side effects of chemotherapeutic alkylating agent treatment.
Collapse
Affiliation(s)
- R B Roth
- Department of Cancer Cell Biology, Harvard School of Public Health, 665 Huntington Avenue, Boston, MA, USA
| | | |
Collapse
|
14
|
Wu T, Kim HJ, Sellers SE, Meade KE, Agricola BA, Metzger ME, Kato I, Donahue RE, Dunbar CE, Tisdale JF. Prolonged high-level detection of retrovirally marked hematopoietic cells in nonhuman primates after transduction of CD34+ progenitors using clinically feasible methods. Mol Ther 2000; 1:285-93. [PMID: 10933944 DOI: 10.1006/mthe.2000.0034] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Low-level retroviral transduction and engraftment of hematopoietic long-term repopulating cells in large animals and humans remain primary obstacles to the successful application of hematopoietic stem cell (HSC) gene transfer in humans. Recent studies have reported improved efficiency by including stromal cells (STR), or the fibronectin fragment CH-296 (FN), and various cytokines such as flt3 ligand (FLT) during ex vivo culture and transduction in nonhuman primates. In this work, we extend our studies using the rhesus competitive repopulation model to further explore optimal and clinically feasible peripheral blood (PB) progenitor cell transduction methods. First, we compared transduction in the presence of either preformed autologous STR or immobilized FN. Long-term clinically relevant gene marking levels in multiple hematopoietic lineages from both conditions were demonstrated in vivo by semiquantitative PCR, colony PCR, and genomic Southern blotting, suggesting that FN could replace STR in ex vivo transduction protocols. Second, we compared transduction on FN in the presence of IL-3, IL-6, stem cell factor (SCF), and FLT (our best cytokine combination in prior studies) with a combination of megakaryocyte growth and development factor (MGDF), SCF, and FLT. Gene marking levels were equivalent in these animals, with no significant effect on retroviral gene transfer efficiency assessed in vivo by the replacement of IL-3 and IL-6 with MGDF. Our results indicate that SCF/G-CSF-mobilized PB CD34+ cells are transduced with equivalent efficiency in the presence of either STR or FN, with stable long-term marking of multiple lineages at levels of 10-15% and transient marking as high as 54%. These results represent an advance in the field of HSC gene transfer using methods easily applied in the clinical setting.
Collapse
Affiliation(s)
- T Wu
- Hematology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Omori F, Juopperi T, Chan CK, Chang YN, Phipps S, Nanji S, Zhao Y, Stewart AK, Dubé ID. Retroviral-mediated transfer and expression of the multidrug resistance protein 1 gene (MRP1) protect human hematopoietic cells from antineoplastic drugs. JOURNAL OF HEMATOTHERAPY & STEM CELL RESEARCH 1999; 8:503-14. [PMID: 10791901 DOI: 10.1089/152581699319957] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Multidrug resistance protein (MRP1) is a member of the ATP-binding cassette (ABC) transmembrane transporter superfamily that confers multidrug resistance. The transfer and expression of the MRP1 gene in human hematopoietic stem cells may be a useful alternative to multidrug resistance (MDR1) gene transfer for protection from the myelosuppressive effects of chemotherapy in cancer patients. We constructed a gibbon ape leukemia virus packaging cell line (PG13) using the human MRP1 cDNA in a Moloney murine leukemia virus (MoMuLV) backbone containing a modified LTR. This PG13-based cell line, designated MRP1-PG13, produces retroviral vectors bearing the MRP1 gene at a titer of 1.7x10(5) viral particles/ml. Transduction of the human leukemic cell line K562 showed that viral MRP1-PG13 supernatants routinely transfer the MRP1 gene to approximately 35% of target K562 cells, of which at least one third are capable of proliferating in the presence of otherwise toxic concentrations of etoposide. Southern blot analyses indicated that most clones had only one proviral integration. Northern blot analysis of expanded K562 clones showed the presence of a major full-length approximately 8-kb MRP1 transcript as well as a minor approximately 6-kb transcript in all clones. Flow cytometric analysis of the producer cells and clones of transduced K562 cells demonstrated significantly increased MRP1 expression in these cells (approximately 30-fold increase). Human bone marrow mononuclear cells and CD34+ cells were also transduced with MRP1-PG13 supernatants on fibronectin-coated culture flasks in the presence of SCF, IL-3, and IL-6. PCR analysis of individual hematopoietic colonies in methylcellulose cultures demonstrated proviral DNA in approximately 10% of unselected human hematopoietic progenitor cells cultured from nonsorted mononuclear cell samples and in up to approximately 75% of progenitors when CD34-enriched cell populations were targeted. To assess functional MRP1 gene expression, normal human hematopoietic progenitors and K562 cells were cultured in methylcellulose assays containing vincristine or etoposide. All transduced samples gave rise to approximately 10% drug-resistant colonies, which were shown to be provirus-positive by PCR. Our studies document the development of an amphotropic MRP1 retroviral vector producer cell line and pave the way for large animal and preclinical studies of chemoprotection by MRP1 gene transfer.
Collapse
Affiliation(s)
- F Omori
- Department of Laboratory Medicine, Sunnybrook and Women's College Health Science Centre, Toronto, Ontario, Canada
| | | | | | | | | | | | | | | | | |
Collapse
|
16
|
Licht T, Aran JM, Goldenberg SK, Vieira WD, Gottesman MM, Pastan I. Retroviral transfer of human MDR1 gene to hematopoietic cells: effects of drug selection and of transcript splicing on expression of encoded P-glycoprotein. Hum Gene Ther 1999; 10:2173-85. [PMID: 10498249 DOI: 10.1089/10430349950017167] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Protection of hematopoietic cells of patients undergoing anticancer chemotherapy by MDR1 gene transfer is currently being studied in clinical trials. From animal studies, it has been suggested that aberrant splicing due to cryptic donor and acceptor sites in the MDR1 cDNA could be a major reason for failure to obtain high-level expression of P-glycoprotein in bone marrow. We investigated effects of drug selection on protein expression levels and on splicing of MDR1 transcripts in murine bone marrow cells (BMCs) in vitro. To this end, retroviruses were generated through an identical plasmid, pHaMDR1/A, introduced into different packaging cells. GP + E86- but not PA317-derived producer cells were found to express truncated in addition to full-length message. In BMCs transduced with GP + E86-derived viruses, both messages were increased after treatment with colchicine or daunomycin. Similar results were obtained with NIH 3T3 fibroblasts. However, transduced and drug-selected BMCs displayed the spliced transcript even if the respective PA317-derived producer cells contained no truncated RNA as detected in transduced NIH 3T3 fibroblasts. Short-term drug selection in BMCs transduced with either ecotropic or amphotropic retroviruses resulted in a striking increase in P-glycoprotein expression. Thus, aberrant splicing failed to abrogate P-glycoprotein expression in BMCs. We also studied a vector in which MDR1 was coexpressed with glucocerebrosidase, using an internal ribosomal entry site. Although chemoprotection was less efficient than with pHaMDR1/A, augmentation of protein expression was observed at low selecting drug concentrations. Our study shows that drug selection can partially compensate for inefficient transduction of hematopoietic cells, and may help to develop strategies by which unstable expression of transduced genes can be overcome.
Collapse
Affiliation(s)
- T Licht
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892-4255, USA
| | | | | | | | | | | |
Collapse
|
17
|
Machiels JP, Govaerts AS, Guillaume T, Bayat B, Feyens AM, Lenoir E, Goeminne JC, Cole S, Deeley R, Caruso M, Bank A, Symann M, D'Hondt V. Retrovirus-mediated gene transfer of the human multidrug resistance-associated protein into hematopoietic cells protects mice from chemotherapy-induced leukopenia. Hum Gene Ther 1999; 10:801-11. [PMID: 10210147 DOI: 10.1089/10430349950018553] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Utilization of chemotherapy for the treatment of tumors is mainly limited by its hematological toxicity. Because of the low-level expression of drug resistance genes, transduction of hematopoietic progenitors with multidrug resistance 1 (MDR1) or multidrug resistance-associated protein (MRP) genes should provide protection from chemotherapeutic agent toxicity. Successful transfer of drug resistance genes into hematopoietic cells may allow the administration of higher doses of chemotherapy and, thus, increase regression of chemosensitive tumors. The interest in the use of MRP as an alternative to MDR1 for bone marrow protection lies in its different modulation. This would allow, in the same patient, the use of MDR1 reversal agents to decrease MDR1 tumor resistance without reversing bone marrow (BM) protection of the MRP-transduced hematopoietic cells, since MRP expression is not reversed by these agents. We have constructed MRP-containing retroviral vectors using the phosphoglycerate kinase promoter and generated ecotropic producer cells. Lethally irradiated mice were engrafted with BM cells transduced by coculture with MRP producer cells. Evidence of long-term (9 months) gene transfer was provided by PCR of peripheral blood from MRP-transduced mice. Southern blot analysis confirmed the integrity of the provirus in the MRP-transduced mice. Long-term MRP expression (>5 months) was detected by RT-PCR and fluorescence-activated cell sorting of blood from living mice. High-level expression of MRP in murine hematopoietic cells reduces doxorubicin-induced leukopenia and mortality. Furthermore, we show in vivo selection of MRP-transduced cells following doxorubicin administration, with better and more significant chemoprotection after the second chemotherapy cycle. These data indicate that MRP retroviral gene transfer may be useful for chemoprotection and selection.
Collapse
Affiliation(s)
- J P Machiels
- Laboratory of Experimental Hematology and Oncology, Université Catholique de Louvain, Brussels, Belgium
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
18
|
Clay TM, Custer MC, Spiess PJ, Nishimura MI. Potential use of T cell receptor genes to modify hematopoietic stem cells for the gene therapy of cancer. Pathol Oncol Res 1999; 5:3-15. [PMID: 10079371 DOI: 10.1053/paor.1999.0003] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
The purpose of this review is to illustrate some of the technical and biological hurdles that need to be addressed when developing new gene therapy based clinical trials. Gene transfer approaches can be used to "mark" cells to monitor their persistence in vivo in patients, to protect cells from toxic chemotherapeutic agents, correct a genetic defect within the target cell, or to confer a novel function on the target cell. Selection of the most suitable vector for gene transfer depends upon a number of factors such as the target cell itself and whether gene expression needs to be sustained or transient. The TCR gene transfer approach described here represents one innovative strategy being pursued as a potential therapy for metastatic melanoma. Tumor reactive T cells can be isolated from the tumor infiltrating lymphocytes (TIL) of melanoma patients. A retroviral vector has been constructed containing the T cell receptor (TCR) alpha and beta chain genes from a MART-1-specific T cell clone (TIL 5). Jurkat cells transduced with this virus specifically release cytokine in response to MART-1 peptide pulsed T2 cells, showing that the virus can mediate expression of a functional TCR. HLA-A2 transgenic mice are being used to examine whether transduced bone marrow progenitor cells will differentiate in vivo into mature CD8+ T cells expressing the MART-1-specific TCR. Expression of the human TCR alpha and beta chain genes has been detected by RT-PCR in the peripheral blood of HLA-A2 transgenic mice reconstituted with transduced mouse bone marrow. Expression of the TIL 5 TCR genes in the peripheral blood of these mice was maintained for greater than 40 weeks after bone marrow reconstitution. TIL 5 TCR gene expression was also maintained following transfer of bone marrow from mice previously reconstituted with transduced bone marrow to secondary mouse recipients, suggesting that a pluripotent progenitor or lymphocyte progenitor cell has been transduced.
Collapse
MESH Headings
- Animals
- COS Cells
- Cell Differentiation
- Epitopes/immunology
- Gene Expression
- Genetic Therapy
- Genetic Vectors/genetics
- Graft Survival
- HLA-A2 Antigen/genetics
- Hematopoietic Stem Cell Transplantation
- Hematopoietic Stem Cells/metabolism
- Humans
- Jurkat Cells/metabolism
- Lymphocytes, Tumor-Infiltrating/immunology
- Lymphokines/metabolism
- Melanoma/immunology
- Melanoma/pathology
- Melanoma/therapy
- Mice
- Mice, Inbred C3H
- Mice, Inbred C57BL
- Mice, Transgenic
- Neoplasm Metastasis
- Neoplasm Proteins/immunology
- Radiation Chimera
- Receptors, Antigen, T-Cell, alpha-beta/genetics
- Receptors, Antigen, T-Cell, alpha-beta/immunology
- Retroviridae/genetics
- Reverse Transcriptase Polymerase Chain Reaction
- T-Lymphocytes, Cytotoxic/immunology
- Transfection
Collapse
Affiliation(s)
- T M Clay
- National Cancer Institute, National Institutes of Health, Surgery Branch, Bethesda, MD 20892, USA.
| | | | | | | |
Collapse
|
19
|
Licht T, Gottesman MM, Pastan I. MDR1 Gene Transfer to Hematopoietic Cells. Gene Ther 1999. [DOI: 10.1007/978-3-0348-7011-5_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
20
|
Bunnell BA, Kluge KA, Lee-Lin SQ, Byrne ER, Orlic D, Metzger ME, Agricola BA, Wersto RP, Bodine DM, Morgan RA, Donahue RE. Transplantation of transduced nonhuman primate CD34+ cells using a gibbon ape leukemia virus vector: restricted expression of the gibbon ape leukemia virus receptor to a subset of CD34+ cells. Gene Ther 1999; 6:48-56. [PMID: 10341875 DOI: 10.1038/sj.gt.3300808] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The transduction efficiencies of immunoselected rhesus macaque (Macaca mulatta) CD34+ cells and colony-forming progenitor cells based on polymerase chain reaction (PCR) analysis were comparable for an amphotropic Moloney murine leukemia virus (MLV) retroviral vector and a retroviral vector derived from the gibbon ape leukemia virus (GaLV) packaging cell line, PG13. On performing autologous transplantation studies using immunoselected CD34+ cells transduced with the GaLV envelope (env) retroviral vector, less than 1% of peripheral blood (PB) contained provirus. This was true whether bone marrow (BM) or cytokine-mobilized PB immunoselected CD34+ cells were reinfused. This level of marking was evident in two animals whose platelet counts never fell below 50,000/microliter and whose leukocyte counts had recovered by days 8 and 10 after having received 1.7 x 10(7) or greater of cytokine-mobilized CD34+ PB cells/kg. Reverse transcriptase(RT)-PCR analysis of CD34+ subsets for both the GaLV and amphotropic receptor were performed. The expression of the GaLV receptor was determined to be restricted to CD34+ Thy-1+ cells, and both CD34+ CD38+ and CD34+ CD38dim cells, while the amphotropic receptor was present on all CD34+ cell subsets examined. Our findings suggest that, in rhesus macaques, PG13-derived retroviral vectors may only be able to transduce a subset of CD34+ cells as only CD34+ Thy-1+ cells express the GaLV receptor.
Collapse
Affiliation(s)
- B A Bunnell
- Clinical Gene Therapy Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
21
|
Aran JM, Pastan I, Gottesman MM. Therapeutic Strategies Involving the Multidrug Resistance Phenotype: The MDRI Gene as Target, Chemoprotectant, and Selectable Marker in Gene Therapy. ADVANCES IN PHARMACOLOGY 1999; 46:1-42. [PMID: 10332500 DOI: 10.1016/s1054-3589(08)60468-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- J M Aran
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892-4255, USA
| | | | | |
Collapse
|
22
|
Beauséjour CM, Le NL, Létourneau S, Cournoyer D, Momparler RL. Coexpression of cytidine deaminase and mutant dihydrofolate reductase by a bicistronic retroviral vector confers resistance to cytosine arabinoside and methotrexate. Hum Gene Ther 1998; 9:2537-44. [PMID: 9853520 DOI: 10.1089/hum.1998.9.17-2537] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
The transfer of a drug resistance gene into hematopoietic cells is an approach being investigated to overcome the problem of myelosuppression produced by anticancer drugs. Chemotherapeutic agents are often given in combination in order to increase their effectiveness. Consequently, there is an advantage in designing vectors for gene transfer that are capable of expressing two drug resistance genes. We have constructed a bicistronic retroviral vector, MFG-DHFR-IRES/CD, which contains the mutated human dihydrofolate reductase (DHFR) cDNA with a phenylalanine-to-serine substitution at codon 31 (F31S) and the human cytidine deaminase (CD) cDNA. Murine fibroblast and hematopoietic cells were transduced with this vector and evaluated for their resistance to methotrexate (MTX) and cytosine arabinoside (ARA-C). The transduced fibroblast cells showed high levels of resistance to MTX and to ARA-C as determined by a clonogenic assay. Using enzymatic assays, we observed a coordinate increase in resistance to MTX and DHFR enzyme activity following an ARA-C selection. In addition, MTX selection produced an increase in CD enzyme activity and ARA-C resistance. Murine hematopoietic cells transduced with the bicistronic vector also showed drug resistance to both MTX and ARA-C. Interestingly, the double-gene construct conferred an equivalent level of drug resistance compared with single-gene vectors bearing only CD or DHFR genes in the hematopoietic cells. These results demonstrate the potential of the MFG-DHFR-IRES/CD vector to confer drug resistance to both MTX and ARA-C and may have future application in chemoprotection of normal hematopoietic cells in patients with cancer.
Collapse
Affiliation(s)
- C M Beauséjour
- Département de Pharmacologie, Université de Montréal, Centre de Recherche Pédiatrique, Hôpital Ste-Justine, Quebec, Canada
| | | | | | | | | |
Collapse
|
23
|
Coexpression of Cytidine Deaminase and Mutant Dihydrofolate Reductase by a Bicistronic Retroviral Vector Confers Resistance to Cytosine Arabinoside and Methotrexate. Hum Gene Ther 1998. [DOI: 10.1089/10430349850019373] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
|
24
|
Affiliation(s)
- M Baudard
- Department of Hematology, Hôpital Hôtel-Dieu, Paris, France
| |
Collapse
|
25
|
Licht T, Gottesman MM, Pastan I. Retroviral transfer of multidrug transporter to murine hematopoietic stem cells. Methods Enzymol 1998; 292:546-57. [PMID: 9711582 DOI: 10.1016/s0076-6879(98)92043-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- T Licht
- Laboratory of Molecular Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | | | | |
Collapse
|
26
|
Rahman ZU, Hortobagyi GN, Buzdar AU, Champlin R. High-dose chemotherapy with autologous stem cell support in patients with breast cancer. Cancer Treat Rev 1998; 24:249-63. [PMID: 9805506 DOI: 10.1016/s0305-7372(98)90060-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Z U Rahman
- Department of Breast Medical Oncology, University of Texas M.D. Anderson Cancer Center, Houston, USA
| | | | | | | |
Collapse
|
27
|
Suzuki M, Sugimoto Y, Tsuruo T. Efficient protection of cells from the genotoxicity of nitrosoureas by the retrovirus-mediated transfer of human O6-methylguanine-DNA methyltransferase using bicistronic vectors with human multidrug resistance gene 1. Mutat Res 1998; 401:133-41. [PMID: 9639692 DOI: 10.1016/s0027-5107(98)00002-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Retrovirus-mediated transfer of O6-methylguanine-DNA methyltransferase (MGMT; E.C. 2.1.1.63) and a human multidrug-resistance gene (MDR1) confers resistance to nitrosoureas and natural product antitumor agents, respectively. In a previous study, we constructed two bicistronic retroviral vectors, Ha-MDR-IRES-MGMT and Ha-MGMT-IRES-MDR, that allow co-expression of the MGMT gene and the MDR1 gene to protect cells from the toxicity of combination chemotherapy. Each cell transduced with Ha-MDR-IRES-MGMT or Ha-MGMT-IRES-MDR showed high-level resistance to vincristine and 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitrosou rea (ACNU), indicating that the two drug-resistance genes can be functionally co-expressed from these vectors. In the present study, we examined whether the expression of MGMT from these MDR1-MGMT bicistronic retroviral vectors could protect cells from the genotoxicity of nitrosoureas. Three independent Ha-MDR-IRES-MGMT-transduced clones and three independent Ha-MGMT-IRES-MDR-transduced clones of HeLa MR cells showed 12-23-fold and 27-30-fold higher MGMT activity than the parental cells. These clones are more resistant to ACNU mutagenicity measured by the frequency of the emergence of 6-thioguanine-resistant colonies after ACNU treatment over the frequency seen in the parental cells. The ACNU-induced sister chromatid exchange (SCE) was markedly suppressed in these clones. Murine bone marrow cells were transduced with either Ha-MDR-IRES-MGMT or Ha-MGMT-IRES-MDR. Non-selected populations of the transduced cells showed only marginal increases in drug resistance and MGMT activity. Remarkable increase in drug resistance and MGMT activity were observed after a short exposure of the transduced cells to vincristine. The Ha-MDR-IRES-MGMT-transduced, vincristine-selected bone marrow cells showed 27-fold resistance to vincristine, 7-fold resistance to ACNU, and 10-fold higher MGMT activity than the non-transduced, non-selected cells. The Ha-MGMT-IRES-MDR-transduced, vincristine-selected cells showed 8-fold resistance to vincristine, 16-fold resistance to ACNU and 19-fold higher MGMT activity than the non-transduced, non-selected cells. The rates of ACNU-induced SCE in the vincristine-selected cells were as follows: non-transduced cells (non-selected) and HaMDR-transduced cells>Ha-MDR-IRES-MGMT-transduced cells>Ha-MGMT-IRES-MDR-transduced cells. Again, the only marginal levels of increases in the rates of ACNU-induced SCE were observed in non-selected population of the transduced cells. These results indicate that the MDR1-MGMT bicistronic retrovirus vectors would be useful to protect normal hematopoietic cells from nitrosourea-induced mutagenesis, and drug-selectable bicistronic constructs would have great advantage over non-selectable vectors.
Collapse
Affiliation(s)
- M Suzuki
- Cancer Chemotherapy Center, Japanese Foundation for Cancer Research, Tokyo 170, Japan
| | | | | |
Collapse
|
28
|
Niitsu Y, Takahashi Y, Ban N, Takayama T, Saito T, Katahira T, Umetsu Y, Nakajima T, Ohi M, Kuga T, Sakamaki S, Matsunaga T, Hirayama Y, Kuroda H, Homma H, Kato J, Kogawa K. A proof of glutathione S-transferase-pi-related multidrug resistance by transfer of antisense gene to cancer cells and sense gene to bone marrow stem cell. Chem Biol Interact 1998; 111-112:325-32. [PMID: 9679563 DOI: 10.1016/s0009-2797(97)00169-5] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In order to directly prove the involvement of GST-pi in drug resistance, it's antisense gene was transduced into human colorectal cancer cell line which has been shown to express high level of GST-pi and the sensitivity of this cell line to anticancer drugs were assessed. The transfectant showed higher sensitivity to adriamycin (3.3-fold), Cisplatnum (2.3-fold), Melphalan (2.2-fold), Etoposode (2.2-fold) than the parental cell, while the sensitivity to vincristine, mitomicin C, 5-fluorouracil was unchanged by transfection. When the transfectant and parental cells were innoculated in nude mice and treated with adriamycin, a significant suppression of tumor growth was observed with the transfectant as compared to the parental cell. On the basis of this observation, we then transduced sense GST-pi gene into human bone marrow stem cells (CD34+ cells) to protect them from toxicity of anticancer drug. The gene transduced CD34+ cells formed more CFU-GM than nontransduced CD34+ cell in the presence of adriamycin (30 ng/ml). Thus, the autotransplantation of GST-pi gene transduced cell into cancer patients to protect the bone marrow from subsequent highdose chemotherapy is considered to be a new strategy for cancer gene therapy.
Collapse
Affiliation(s)
- Y Niitsu
- Fourth Department of Internal Medicine, Sapporo Medical University School of Medicine, Japan
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Fantz CR, Shaw D, Moore JG, Spencer HT. Retroviral coexpression of thymidylate synthase and dihydrofolate reductase confers fluoropyrimidine and antifolate resistance. Biochem Biophys Res Commun 1998; 243:6-12. [PMID: 9473470 DOI: 10.1006/bbrc.1997.8059] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Retroviral gene transfer of dominant selectable markers into hematopoietic cells can be used to select genetically modified cells in vivo or to attenuate the toxic effects of chemotherapeutic agents. We show that retroviral gene transfer of thymidylate synthase (TS) confers resistance to TS directed anticancer agents and that co-expression of TS and dihydrofolate reductase (DHFR) confers resistance to TS and DHFR cytotoxic agents. Retroviral vectors encoding Escherichia coli TS, human TS, and the Tyr-to-His at residue 33 variant of human TS (Y33HhTS) were constructed and fibroblasts transfected with these vectors conferred comparable resistance to the TS-directed agent fluorodeoxyuridine (FdUrd, approximately 4-fold). Retroviral vectors that encode dual expression of Y33HhTS and the human L22Y DHFR (L22YhDHFR) variants conferred resistance to FdUrd (3- to 5-fold) and trimetrexate (30- to 140-fold). A L22YhDHFR-Y33HhTS chimeric retroviral vector was also constructed and transduced cells were resistant to FdUrd (3-fold), AG337 (3-fold), trimetrexate (100-fold) and methotrexate (5-fold). These results show that recombinant retroviruses can be used to transfer the cDNA that encodes both TS and DHFR and dual expression in transduced cells is sufficiently high to confer resistance to TS and DHFR directed anticancer agents.
Collapse
Affiliation(s)
- C R Fantz
- Department of Chemistry and Biochemistry, University of South Carolina, Columbia 29208, USA
| | | | | | | |
Collapse
|
30
|
Protection of Hematopoietic Progenitor Cells from Chemotherapy Toxicity by Transfer of Drug Resistance Genes. Gene Ther 1998. [DOI: 10.1007/978-3-662-03577-1_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
|
31
|
Cortner J, Vande Woude S, Vande Woude GF. Genes involved in oncogenesis. ADVANCES IN VETERINARY MEDICINE 1997; 40:51-102. [PMID: 9395729 DOI: 10.1016/s0065-3519(97)80004-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- J Cortner
- National Cancer Institute, National Institutes of Health, Division of Basic Sciences, Bethesda, Maryland 20892, USA
| | | | | |
Collapse
|
32
|
Kuga T, Sakamaki S, Matsunaga T, Hirayama Y, Kuroda H, Takahashi Y, Kusakabe T, Kato I, Niitsu Y. Fibronectin fragment-facilitated retroviral transfer of the glutathione-S-transferase pi gene into CD34+ cells to protect them against alkylating agents. Hum Gene Ther 1997; 8:1901-10. [PMID: 9382956 DOI: 10.1089/hum.1997.8.16-1901] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
To protect bone marrow cells from the toxicity of chemotherapy, a multidrug resistant gene or a dihydrofolate reductase gene has been introduced into stem cells. These genes, however, are not capable of conferring refractoriness to alkylating agents (AA), which are some of the most commonly used agents in chemotherapy regimens. In the present study, an attempt was made to endow human stem cell (CD34+ cells) with resistance to cyclophosphamide, a well-known AA, and adriamycin (ADM) by transducing the glutathione-S-transferase pi (GST-pi) gene whose product is thought to detoxify AA by conjugating them with glutathione and to remove a toxic peroxide formed by ADM. The gene transduction was carried out retrovirally with a virus titer of 1 x 10(5) FFU/ml, employing a recombinant fibronectin fragment; transduction efficiency was extremely low without the fragment. Incubation with interleukin-6 and stem cell factor enhanced the expression of fibronectin ligands VLA4 and VLA5 on CD34+ cells. This enhanced expression of VLA4 and VLA5 was considered to facilitate a close contact of the CD34+ cell to the retroviral vector via fibronectin fragments and the subsequent transduction process. The GST-pi gene-transduced CD34+ cells formed almost 3- and 2.5-fold more CFU-GM than neo gene-transduced CD34+ cells in the presence of 2.5 microg/ml of 4-hydroperoxycyclophosphamide (4-HC), an active form of cyclophosphamide, and 30 ng/ml ADM, respectively. The transfectants formed an appreciable number of colonies, even at higher concentrations of these drugs (5.0 microg/ml of 4-HC, 50 ng/ml of ADM) whereas neo gene-transduced or nontransduced CD34+ cells formed no colonies at all, indicating the possibility of selecting out the transfectants by exposing them to these anticancer drugs. Thus, we were able to demonstrate that transduction of the GST-pi gene confers resistance to cyclophosphamide as well as to ADM, and therefore this approach can be applied clinically for high-dose chemotherapy.
Collapse
Affiliation(s)
- T Kuga
- 4th Department of Internal Medicine, Sapporo Medical University School of Medicine, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
33
|
Abstract
OBJECTIVES To describe the basics of gene transfer and specific applications in marrow ablative therapy. DATA SOURCES Review articles, research studies, and book chapters pertaining to gene therapy. CONCLUSIONS Gene therapy will be a major factor in healthcare options for the 21st century. Genetically engineered biopharmaceuticals will probably have a place in the blood cell transplant regimens of the future. IMPLICATIONS FOR NURSING PRACTICE Nurses are in a position to guide the successful implementation of gene therapy through their roles as patient educator, counselor, direct-care coordinator, consultant, and through development of resource materials.
Collapse
Affiliation(s)
- L J Cuaron
- Schering Laboratories, Kenilworth, NJ 07033, USA
| | | |
Collapse
|
34
|
Abstract
OBJECTIVES To provide oncology nurses with the basic concepts of gene therapy related to cancer and to outline their practice roles. DATA SOURCE Published professional articles, clinical protocols, and textbooks. CONCLUSION Oncology nurses will need to become knowledgeable about the methods and applications of gene therapy for cancer to participate in clinical trials and to develop relevant nursing development plans. IMPLICATIONS FOR NURSING PRACTICE Advances in genetic testing and gene therapies will extend oncology nursing roles in direct patient care, education, advocacy, provision of genetic services, and nursing research. Oncology nurses will also participate in dialogue and development of social policies with regard to the safety, ethical, and social issues related to cancer gene therapy.
Collapse
Affiliation(s)
- D H Lea
- Clinical Genetics Foundation for Blood Research, Scarborough, ME 04070, USA
| |
Collapse
|
35
|
|
36
|
Monitoring of Tumor Cell Purging After Highly Efficient Immunomagnetic Selection of CD34 Cells From Leukapheresis Products in Breast Cancer Patients: Comparison of Immunocytochemical Tumor Cell Staining and Reverse Transcriptase–Polymerase Chain Reaction. Blood 1997. [DOI: 10.1182/blood.v89.1.337] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractWe studied the efficiency of indirect tumor cell purging via enrichment of CD34+ hematopoietic progenitor cells from leukapheresis products (LP) in breast cancer patients based on immunomagnetic selection of CD34+ cells. Detection of tumor cells was made by immunocytochemical staining. In addition, we evaluated the capacity of cytokeratin 19 (CK19)- and a novel epidermal growth factor receptor (EGF-R)-specific reverse transcriptase–polymerase chain reaction (RT-PCR) for monitoring tumor cell depletion. LP from 13 breast cancer patients were analyzed. Twenty-three CD34 selection procedures were performed. A median of 1.4 × 1010 total nucleated cells ([TNC] range, 0.88 to 3.5 × 1010) with a median CD34 purity of 2.5% (range, 0.4% to 6.3%) were entered into the selection procedure. Immunomagnetic CD34 enrichment resulted in a median purity of 83.3% (range, 45% to 95.4%) and a median recovery of 73.2% (range, 22% to 95%). Retransfusion of CD34-selected cells after high-dose chemotherapy resulted in a rapid and sustained hematologic recovery, reaching an absolute neutrophil count of 500/μL at day +10 and platelet count of 20,000/μL at day +11. Tumor cell depletion was quantified by immunocytochemical detection of CK19-positive cells. By this method, a median tumor cell depletion of 1.9 log (range, 0.7 to <3 log) could be demonstrated. Immunocytochemical detection of tumor cells was more sensitive than RT-PCR, yielding positive results in 81% of LP (17 to 21) versus 58% positive LP (10 of 17). However, EGF-R–based RT-PCR was much more sensitive than CK19-based RT-PCR (10 of 17 v 1 of 17). Despite highly efficient CD34 selection, tumor cells were still detectable after CD34 enrichment using immunocytochemistry and EGF-R–specific RT-PCR. Thus, this novel EGF-R–specific RT-PCR appears to be of value as an additional method to detect contaminating breast cancer cells within LP.
Collapse
|
37
|
Bhatia R, McGlave PB. Autologous stem cell transplantation for the treatment of chronic myelogenous leukemia. Cancer Treat Res 1997; 77:357-74. [PMID: 9071511 DOI: 10.1007/978-1-4615-6349-5_16] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- R Bhatia
- Department of Hematology and Bone Marrow Transplantation, City of Hope National Medical Center, Duarte, CA 91010, USA
| | | |
Collapse
|
38
|
Licht T, Herrmann F, Gottesman MM, Pastan I. In vivo drug-selectable genes: a new concept in gene therapy. Stem Cells 1997; 15:104-11. [PMID: 9090786 DOI: 10.1002/stem.150104] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
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.
Collapse
Affiliation(s)
- T Licht
- Laboratory of Molecular Biology, National Cancer Institute, Bethesda, Maryland 20892-4255, USA
| | | | | | | |
Collapse
|
39
|
Monitoring of Tumor Cell Purging After Highly Efficient Immunomagnetic Selection of CD34 Cells From Leukapheresis Products in Breast Cancer Patients: Comparison of Immunocytochemical Tumor Cell Staining and Reverse Transcriptase–Polymerase Chain Reaction. Blood 1997. [DOI: 10.1182/blood.v89.1.337.337_337_344] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We studied the efficiency of indirect tumor cell purging via enrichment of CD34+ hematopoietic progenitor cells from leukapheresis products (LP) in breast cancer patients based on immunomagnetic selection of CD34+ cells. Detection of tumor cells was made by immunocytochemical staining. In addition, we evaluated the capacity of cytokeratin 19 (CK19)- and a novel epidermal growth factor receptor (EGF-R)-specific reverse transcriptase–polymerase chain reaction (RT-PCR) for monitoring tumor cell depletion. LP from 13 breast cancer patients were analyzed. Twenty-three CD34 selection procedures were performed. A median of 1.4 × 1010 total nucleated cells ([TNC] range, 0.88 to 3.5 × 1010) with a median CD34 purity of 2.5% (range, 0.4% to 6.3%) were entered into the selection procedure. Immunomagnetic CD34 enrichment resulted in a median purity of 83.3% (range, 45% to 95.4%) and a median recovery of 73.2% (range, 22% to 95%). Retransfusion of CD34-selected cells after high-dose chemotherapy resulted in a rapid and sustained hematologic recovery, reaching an absolute neutrophil count of 500/μL at day +10 and platelet count of 20,000/μL at day +11. Tumor cell depletion was quantified by immunocytochemical detection of CK19-positive cells. By this method, a median tumor cell depletion of 1.9 log (range, 0.7 to <3 log) could be demonstrated. Immunocytochemical detection of tumor cells was more sensitive than RT-PCR, yielding positive results in 81% of LP (17 to 21) versus 58% positive LP (10 of 17). However, EGF-R–based RT-PCR was much more sensitive than CK19-based RT-PCR (10 of 17 v 1 of 17). Despite highly efficient CD34 selection, tumor cells were still detectable after CD34 enrichment using immunocytochemistry and EGF-R–specific RT-PCR. Thus, this novel EGF-R–specific RT-PCR appears to be of value as an additional method to detect contaminating breast cancer cells within LP.
Collapse
|
40
|
Abstract
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.
Collapse
Affiliation(s)
- F D Ledley
- GENEMEDICINE, INC., Woodlands, Texas 77381, USA
| |
Collapse
|
41
|
Rafferty JA, Hickson I, Chinnasamy N, Lashford LS, Margison GP, Dexter TM, Fairbairn LJ. Chemoprotection of normal tissues by transfer of drug resistance genes. Cancer Metastasis Rev 1996; 15:365-83. [PMID: 9034597 DOI: 10.1007/bf00046348] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The effectiveness of many types of antitumour agent is limited by (i) acute dose limiting cytotoxicity, principally myelosuppression but also lung, liver and gastrointestinal tract toxicity, (ii) the risk of therapy related secondary malignancy and (iii) the inherent or acquired drug-resistance of tumour cells. As the management of the acute toxic effects improve, the more insidious effects, and particularly haematological malignancies, are anticipated to increase. Furthermore, attempts to overcome tumour cell resistance to treatment can lead to increased collateral damage in normal tissues. One approach to circumventing both the acute toxic and chronic carcinogenic effects of chemotherapy would be to use gene therapy to achieve high levels of expression of drug resistance proteins in otherwise drug-sensitive tissues. To date the products of the multi-drug resistance (MDR-1) and the human O6-alkylguanine-DNA-alkyltransferase (ATase) gene have been used in preclinical experiments to demonstrate proof of principle, and the former of these is now being tested in a clinical situation. Here we discuss the potential of drug-resistance gene therapy to provide chemoprotection to normal tissues and examine the prospects for a dual approach which combines this with pharmacological sensitisation of tumours to chemotherapeutic agents.
Collapse
Affiliation(s)
- J A Rafferty
- CRC Department of Carcinogenesis, Paterson Institute for Cancer Research, Christie Hospital (NHS)-Trust, Manchester, UK
| | | | | | | | | | | | | |
Collapse
|
42
|
Affiliation(s)
- M Baudard
- Service d'Hématologie, Hôpital Hôtel-Dieu, Paris, France
| | | | | |
Collapse
|
43
|
Kane SE. Multidrug resistance of cancer cells. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/s0065-2490(96)80005-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
|
44
|
Ford JM, Yang JM, Hait WN. P-glycoprotein-mediated multidrug resistance: experimental and clinical strategies for its reversal. Cancer Treat Res 1996; 87:3-38. [PMID: 8886447 DOI: 10.1007/978-1-4613-1267-3_1] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The study of the cellular, biochemical, and molecular biology and pharmacology of MDR has provided one of the most active and exciting areas within cancer research and one that holds great promise for translation into clinical benefit. While convincing evidence for the functional role of P-gp in mediating clinical drug resistance in humans remains elusive, studies of the clinical expression of P-gp and trials of chemosensitizers with cancer chemotherapy suggest "resistance modification" strategies may be effective in some tumors with intrinsic or acquired drug resistance. However, even if P-gp-associated MDR proves to be a relevant and reversible cause of clinical drug resistance, numerous problems remain to be solved before effective clinical chemosensitization may be achieved. Such factors as absorption, distribution, and metabolism; the effect of chemosensitizers on chemotherapeutic drug clearance; toxicity to normal tissues expressing P-gp; and the most efficacious modulator regimens all remain to be defined in vivo. Clearly, the identification of more specific, potent, and less clinically toxic chemosensitizers for clinical use remains critical to the possible success of this approach. Nonetheless, the finding that a number of pharmacological agents can antagonize a well-characterized form of experimental drug resistance provides promise for potential clinical applications. Further study of chemosensitizers in humans and the rational design of novel chemosensitizers with improved activity should define the importance of MDR in clinically resistant cancer.
Collapse
Affiliation(s)
- J M Ford
- Department of Biological Sciences, Herrin Biology Laboratories, Stanford University, CA 94305-5020, USA
| | | | | |
Collapse
|
45
|
Affiliation(s)
- A M Casazza
- Bristol-Myers Squibb Pharmaceutical Research Institute, Princeton, NJ 08543-4000, USA
| | | |
Collapse
|
46
|
Fruehauf S, Boesen JJ, Breems DA, Höft R, Hundsdörfer P, Zeller WJ, Löwenberg B, Ploemacher RE, Haas R, Valerio D. Retroviral transfer of the multidrug resistance-1 gene into lineage-committed and primitive hemopoietic cells. Stem Cells 1995; 13 Suppl 3:93-9. [PMID: 8747995 DOI: 10.1002/stem.5530130715] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Transfer of the multidrug resistance-1 (MDR1) gene to hemopoietic cells for myeloprotection against cytostatic agents is a new and rapidly developing field in "cancer gene therapy." Before clinical application, safety and efficacy criteria need to be met. The retroviral producer cell lines and the retroviral supernatant need to be tested for replication-competent retrovirus and contamination with adventitious agents. The cell source needs to contain sufficient hemopoietic cells with repopulating ability. We used CD34(+)-selected mobilized peripheral blood progenitor cells (PBPC) for MDR1 transductions in order to obtain a favorable vector to target cell ratio. An analysis of 249 patients who had undergone PBPC harvesting revealed that primarily solid tumor and non-Hodgkin's lymphoma patients are eligible for CD34+ selection. They can be expected to retain sufficient CD34+ cells for rapid and sustained engraftment after myeloablative therapy if the CD34+ cell loss (approximately 50%) during the procedure is taken into account. Clinical MDR1 gene therapy protocols focus on these two patient groups. Next we characterized MDR1 gene transfer into lineage-committed and primitive hemopoietic cells. Provirus-specific polymerase chain reactions showed a high efficiency gene transfer into colony-forming-units granulocyte-macrophage and long-term culture cells. The level of the conferred P-glycoprotein expression was estimated by fluorescence-activated cell sorting analysis to be up to 3 log above mock-transduced controls. The cobblestone area forming cell assay, which is a stroma-dependent long-term culture assay measuring frequencies of stem cell subsets in a limiting-dilution set-up, allowed demonstration of sustained expression of the MDR1 gene in the progeny of primitive hemopoietic cells. This is a favorable basis for a clinical MDR1 gene therapy trial.
Collapse
Affiliation(s)
- S Fruehauf
- Department of Internal Medicine V, University of Heidelberg, Germany
| | | | | | | | | | | | | | | | | | | |
Collapse
|
47
|
Abstract
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.
Collapse
Affiliation(s)
- Y Reisner
- Department of Membrane Research and Biophysics, Weizmann Institute of Science, Rehovot, Israel
| | | |
Collapse
|
48
|
Blaese M, Blankenstein T, Brenner M, Cohen-Haguenauer O, Gansbacher B, Sorrentino B, Velu T. European School of Oncology position paper. Gene therapy for the medical oncologist. Eur J Cancer 1995; 31A:1531-7. [PMID: 7577084 DOI: 10.1016/0959-8049(95)00295-t] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- M Blaese
- Division of Bone Marrow Transplantation, St Jude Children's Research Hospital, Memphis, Tennessee 38101-0318, USA
| | | | | | | | | | | | | |
Collapse
|
49
|
Dunbar CE, Emmons RV. Gene transfer into hematopoietic progenitor and stem cells: progress and problems. Stem Cells 1994; 12:563-76. [PMID: 7881358 DOI: 10.1002/stem.5530120604] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Gene transfer to hematopoietic cells for the purpose of "gene therapy" is a new and rapidly developing field with clinical trials in progress. A fundamental goal of research in this field is the incorporation of exogenous genes into the chromosomes of the most primitive hematopoietic progenitor cells--stem cells. Recombinantly engineered retroviral vectors are the best characterized and are currently the only vector type in clinical trials directed at the hematopoietic system. High efficiency gene transfer and expression in murine stem cells and their progeny is now routine, but in larger animal models such as dogs or primates and preliminary clinical trials, gene transfer has been less successful. Problems such as retroviral efficiency, gene expression, insertional mutagenesis and helper virus contamination are being addressed. A promising new vector, the adeno-associated virus (AAV), has shown promise and may allow production of high titer, stable, recombinant virions without helper contamination and with potentially better safety parameters. However, the technology for AAV gene transfer is currently underdeveloped, and issues related to the reproducible production of vectors must be addressed. Other non-viral vector systems are being explored, but little data are available on applications to hematopoietic cells. Better preclinical models are needed to study gene targeting and expression in human cells. An overview of recombinant retroviral and adeno-associated viral vector production, preclinical data and preliminary clinical data will be given, and problems needing to be addressed at all stages of development before broad clinical utility can be achieved will be discussed.
Collapse
Affiliation(s)
- C E Dunbar
- Hematology Branch, National Heart, Lung and Blood Institute, Bethesda, MD 20892
| | | |
Collapse
|