Optical imaging of progenitor cell homing to patient-derived tumors
ABSTRACT Capitalizing on cellular homing to cancer is a promising strategy for targeting malignant cells for diagnostic, monitoring and therapeutic purposes. Murine C17.2 neural progenitor cells (NPC) demonstrate a tropism for cell line-derived tumors, but their affinity for patient-derived tumors is unknown. We tested the hypothesis that NPC accumulate in patient-derived tumors at levels detectable by optical imaging. Mice bearing solid tumors after transplantation with patient-derived leukemia cells and untransplanted controls received 10(6) fluorescent DiR-labeled NPC daily for 1-4 days, were imaged, then sacrificed. Tissues were analyzed by immunofluorescence and flow cytometry to detect tumor cell engraftment (CD45) and NPC (FITC-β galactosidase or DiR). Tumors consisted primarily of CD45-positive cells and demonstrated mild fluorescence, corresponding to frequent clusters of FITC-β gal-positive cells. Both transplanted and control mice demonstrated the highest fluorescent signal in the spleens and other tissues of the reticuloendothelial activating system. However, only rare FITC-β gal-positive cells were detected in the mildly engrafted transplanted spleens and none in the control spleens, suggesting that their high DiR signal reflects the sequestration of DiR-positive debris. The mildly engrafted transplanted kidneys demonstrated low fluorescent signal and rare FITC-β gal-positive cells whereas control kidneys were negative. Results indicate that NPC accumulate in tissues containing patient-derived tumor cells in a manner that is detectable by ex vivo optical imaging and proportional to the level of tumor engraftment, suggesting a capacity to home to micrometastatic disease. As such, NPC could have significant clinical applications for the targeted diagnosis and treatment of cancer. Copyright © 2012 John Wiley & Sons, Ltd.
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ABSTRACT: Chronic myeloid leukemia (CML) is a hematopoietic stem cell disease with distinct biological and clinical features. The biologic basis of the stereotypical progression from chronic phase through accelerated phase to blast crisis is poorly understood. We used DNA microarrays to compare gene expression in 91 cases of CML in chronic (42 cases), accelerated (17 cases), and blast phases (32 cases). Three thousand genes were found to be significantly (P < 10(-10)) associated with phase of disease. A comparison of the gene signatures of chronic, accelerated, and blast phases suggest that the progression of chronic phase CML to advanced phase (accelerated and blast crisis) CML is a two-step rather than a three-step process, with new gene expression changes occurring early in accelerated phase before the accumulation of increased numbers of leukemia blast cells. Especially noteworthy and potentially significant in the progression program were the deregulation of the WNT/beta-catenin pathway, the decreased expression of Jun B and Fos, alternative kinase deregulation, such as Arg (Abl2), and an increased expression of PRAME. Studies of CML patients who relapsed after initially successful treatment with imatinib demonstrated a gene expression pattern closely related to advanced phase disease. These studies point to specific gene pathways that might be exploited for both prognostic indicators as well as new targets for therapy.Proceedings of the National Academy of Sciences 02/2006; 103(8):2794-9. DOI:10.1073/pnas.0510423103 · 9.81 Impact Factor
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ABSTRACT: Neural stem cells and progenitor cells migrate selectively to tumor loci in vivo. We exploited the tumor-tropic properties of HB1.F3.C1 cells, an immortalized cell line derived from human fetal telencephalon, to deliver the cDNA encoding a secreted form of rabbit carboxylesterase (rCE) to disseminated neuroblastoma tumors in mice. This enzyme activates the prodrug CPT-11 more efficiently than do human enzymes. Mice bearing multiple tumors were treated with rCE-expressing HB1.F3.C1 cells and schedules of administration of CPT-11 that produced levels of active drug (SN-38) tolerated by patients. Both HB1.F3.C1 cells and CPT-11 were given i.v. None of the untreated mice and 30% of mice that received only CPT-11 survived long term. In contrast, 90% of mice treated with rCE-expressing HB1.F3.C1 cells and 15 mg/kg CPT-11 survived for 1 year without detectable tumors. Plasma carboxylesterase activity and SN-38 levels in mice receiving both rCE-expressing HB1.F3.C1 cells (HB1.F3.C1/AdCMVrCE) and CPT-11 were comparable with those in mice receiving CPT-11 only. These data support the hypothesis that the antitumor effect of the described neural stem/progenitor cell-directed enzyme prodrug therapy (NDEPT) is mediated by production of high concentrations of active drug selectively at tumor sites, thereby maximizing the antitumor effect of CPT-11. NDEPT approaches merit further investigation as effective, targeted therapy for metastatic tumors. We propose that the described approach may have greatest use for eradicating minimum residual disease.Cancer Research 02/2007; 67(1):22-5. DOI:10.1158/0008-5472.CAN-06-3607 · 9.28 Impact Factor
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ABSTRACT: Glucose-6-phosphate dehydrogenase (G-6-PD) isoenzymes types of granulocytes were determined in eight women with chronic myelocytic leukemia (CML). The patients were heterozygous at the X-linked G-6-PD locus for the common gene, GdB, and a variant, such as GdA, so that both B and A enzyme types were found in skin cells. In contrast to these normal cells, only one G-6-PD type was found in CML granulocytes. The fact that such single-enzyme phenotypes are found in CML granulocytes, but not in nonleukemic granulocytes, provides strong evidence that the disease has a clonal origin. Single-enzyme phenotypes were also found in erythrocytes, platelets and cultured blood macrophages indicating that these cells have a common stem cell which is the site of the abnormality in CML. In the one studied patient, no evidence was found for involvement of cultured marrow fibroblasts. Clonal origin of CML virtually excludes cell recruitment as a sole pathogenetic mechanism. Either the leukemia arises as a consequence of a rare initial event in a single cell, or a series of events occurs in a clone such that it evolves into CML, or both.The American Journal of Medicine 08/1977; 63(1):125-30. DOI:10.1016/0002-9343(77)90124-3 · 5.30 Impact Factor