Histologic evaluation of 12 direct xenografts established from 11 different patient tumors identified a subset cells that strongly express ALDH1 relative to all other tumor cells in all but one specimen . The patient specimen, MDA-PATX10, in which ALDH1 was undetectable by immunohistochemistry also did not express detectable ALDH1 in derived xenografts , suggesting that the xeno-transplantation process did not affect ALDH1 expression. Again consistent with ALDH1 expression in human tumor specimens, intra-tumoral heterogeneity of ALDH1 expression in direct xenograft tumors was demonstrated through intense staining for ALDH1 in only a subset of luminal tumor cells relative to all other cells within tumor . All of these characteristics were maintained in subsequent direct xenograft generations . We next sought to identify and quantify overlapping and nonoverlapping cell populations Selumetinib MEK inhibitor expressing putative pancreatic CSC markers in direct xenograft tumors by flow cytometry. Pancreatic tumors of NOD/SCID mice underwent mechanical and enzymatic digestion into single cell suspensions and were subsequently stained with AldefluorH reagent and directly conjugated anti-CD133 antibodies as described in buy BYL719 Materials and Methods. After exclusion of debris and cells of mouse origin, viable human cells were analyzed by flow cytometry . The results demonstrated ALDHhigh and ALDHlow in all patient-derived xenografts examined, but the proportion of each varied widely . However, within a given patient xenograft lineage, the relative percentage of cells with high ALDH activity remained conserved through at least two passages in NOD/SCID mice as did the percentage of cell populations with low ALDH activity. We therefore compared ALDH activity and CD133 expression in xenograft tumors established from patient tumors treated with chemotherapy and radiation therapy relative to untreated specimens by flow cytometry. No general enrichment of either ALDH or CD133 expressing cell populations was observed in tumor specimens previously exposed to neoadjuvant therapy relative to treatment na?��ve tumor specimens . However, because the percent cell populations of ALDH or CD133 expressing cells remains unknown in original patient tumors, we are unable to determine whether such cell populations become enriched or diluted in formed direct xenograft tumors. We demonstrate that selection for cells with high ALDH activity from direct pancreatic cancer xenograft tumors enriches for TICs in the NOD/SCID xeno-transplantation model, with implantation of only 100 ALDHhigh cells resulting in a 100 percent incidence of tumor formation.
Month: October 2017
In the gene family may provide insights into the evolutionary process of many other genes
In contrast, in the treatment group receiving AMD3100, FDA-approved Compound Library leukemic cell cluster regrowth was inhibited in the portal area . As a result, the macroscopic size of the liver and spleen in AMD3100-treated leukemic mice was smaller than that in control mice , and leukemic cell counts and organ volumes of the liver and spleen were significantly reduced . Interestingly, the largest decrease in leukemic cell count was observed in the liver of AMD3100-treated mice , and was seemingly correlated to the frequency of CXCR4-positive leukemic cells in each organ . During the long-term administration of AMD3100 or NS up to 60 days after AraC treatment, significantly fewer leukemic cells were present in the PB of AMD3100-treated mice compared with control mice receiving NS . Consequently, the control mice lost a significant amount of body weight, while the body weight of the AMD3100-treated mice was not significantly different compared with that of normal NOG mice . Furthermore, the AMD3100-treated mice demonstrated a higher overall survival, as estimated by the Kaplan-Meier method . Overall, these results strongly indicate that the SDF-1/CXCR4 signaling pathway plays a crucial role in re-expansion of ALL leukemic cells in the hepatic niche after chemotherapy and provide a novel anti-leukemic therapy that targets the extramedullary microenvironment. In this paper, we propose that leukemic extramedullary DAPT citations pathology is due to not only migrating, but also resident proliferating leukemic cells in the extramedullary niche. Using xeno-transplantation model, previous reports showed that human leukemic cells infiltrate the liver ; however, those reports lacked pathological or molecular assessment. Here, through the analysis of h-leukemic NOG model, we have demonstrated that hepatic extramedullary microenvironments provide a niche which harbors and propagates leukemic cells. We also demonstrated that the SDF-1/CXCR4 axis plays a crucial role in causing liver pathology. Recent studies revealed SDF- 1/CXCR4 axis involvement in the development and metastasis of solid tumor . This axis has also been known to play an indispensable role in the homing, proliferation, and survival of both normal hematopoietic and leukemic cells in the BM niche . In pediatric ALL patients, high expression of CXCR4 in leukemic cells was strongly predictive of extramedullary organ involvement , which is compatible with the findings in our murine xeno-transplantation model.