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PubMed2006

Regulation of germline stem cell proliferation downstream of nutrient sensing.

Stem cells have recently attracted significant attention largely due to their potential therapeutic properties, but also because of their role in tumorigenesis and their resemblance, in many aspects, to cancerous cells. Understanding how stem cells are regulated, namely with respect to the control of their proliferation and differentiation within a functional organism, is thus primordial to safely profit from their therapeutic benefits. Here, we review recent advances in the understanding of germline stem cell proliferation control by factors that respond to the nutritional status and/or insulin signaling, through studies performed in C. elegans and Drosophila. Together, these data uncover some shared fundamental features that underlie the central control of cellular proliferation within a target stem cell population in an organism. These features may indeed be conserved in higher organisms and may apply to various other stem cell populations.

Journal Article↗
PubMed1997

Induction, mobilization of peripheral blood stem cells (PBSC), high-dose chemotherapy and PBSC infusion in patients with untreated stage IV breast cancer: outcomes by intent to treat analyses.

We investigated the outcomes of patients with breast cancer undergoing induction chemotherapy, mobilization of peripheral blood stem cells (PBSC) and high-dose chemotherapy (HDC) with PBSC infusion. One hundred and fourteen patients with untreated stage IV breast cancer, with a median age of 46 years (range 24-62), were entered on a phase II trial consisting of; (1) doxorubicin, 5-flurouracil, methotrexate (AFM) x 4 courses at 2 week intervals; (2) cyclophosphamide (4 g/m2), etoposide (600 mg/m2), cisplatin (105 mg/m2) (CEP), filgrastim (6 micrograms/kg/day) and PBSC collection; (3) cyclophosphamide (6 g/m2), thiotepa (500 mg/m2), carboplatin (800 mg/m2), (CTCb) followed by PBSC infusion. All patients received AFM, 107 (94%) received CEP, 93 (82%) received CTCb and PBSC as per protocol and 99 (87%) ultimately received HDC and PBSC. There was one infectious death after AFM and all other deaths were associated with progressive disease. Fifty-two patients (46%) are alive, 21 (18%) without progression, at a median 31 months (range 22-47). The probabilities of survival and progression-free survival at 3.5 years were 0.40 and 0.17, respectively. All 62 patients with visceral disease and/or a prior history of doxorubicin adjuvant therapy have relapsed or progressed. We conclude that the sequential administration of AFM, CEP and CTCb followed by PBSC resulted in long-term PFS only in patients who were NED, had bone-only disease or had lymph node or soft tissue disease with or without bone disease. Other strategies, aimed at improving responses to initial therapy, improving HDC regimens and/or developing immunomodulatory therapies, will be necessary to improve PFS for patients who fail doxorubicin adjuvant or who have visceral disease.

Adult↗
PubMed2006

The pivotal role of CXCL12 (SDF-1)/CXCR4 axis in bone metastasis.

Tumor cells are known to adapt to and utilize existing physiological mechanisms to promote survival and metastasis. The role of the microenvironment in the establishment of a metastatic lesion has become increasingly important as several factors secreted by stromal cells regulate metastatic pattern in a variety of tumor types. Tumor cells interact with osteoblasts, osteoclasts and bone matrix to form a vicious cycle that is essential for successful metastases. Here we review the current concepts regarding the role of an important chemokine/chemokine receptor (SDF-1 or CXCL12/CXCR4) pathway in tumor development and metastasis. CXCL12 secretion by stromal cells is known to attract cancer cells via stimulation of the CXCR4 receptor that is up regulated by tumor cells. CXCL12/CXCR4 activation regulates the pattern of metastatic spread with organs expressing high levels of CXCL12 developing secondary tumors (i.e., the bone marrow compartment). CXCL12 has a wide range of effects in regards to tumor development but the primary role of CXCL12 appears to be the mobilization of hematopoietic stem cells and the establishment of the cancer stem-like cell niche where high levels of CXCL12 recruit a highly tumorigenic population of tumor cells and promotes cell survival, proliferation, angiogenesis, and metastasis.

Animals↗
PubMed1993

Autologous bone marrow transplantation for the treatment of lung cancer.

Non-small cell lung cancer is extremely difficult to treat in all stages, and small cell lung cancer patients are cured rarely despite initial responsiveness to conventional chemoradiation therapy, even when diagnosed in limited stage. Intensive cytotoxic therapy has been explored in both small cell and non-small cell lung cancer patients, since a number of agents showed an increased response when given in high dose followed by autologous bone marrow reinfusion. The antitumor responses of single-agent high-dose trials were short-lived, but set the stage for combination chemotherapy trials given in earlier disease stages, ie, as consolidation or intensification therapy in lung cancer. In 11 published trials, 204 small cell lung cancer patients have undergone autologous bone marrow transplants. Although the transplant-related mortality rate in these studies was 7%, the long-term disease-free survival rate was 14% in a heterogeneous group of patients receiving a variety of regimens. The data gleaned from these studies suggested that a subpopulation of lung cancer patients may benefit from the use of this approach if it were to be administered at a time when the tumor burden was low. Because of the great cost of this procedure, however, third-party payers seldom provide financial coverage for these procedures. Hence, while great strides have been made in the therapy of other solid tumors, such as breast, testicular, and ovarian cancers, the role of autologous stem cell transplantation in small cell and non-small cell lung cancer remains yet to be defined.

Antineoplastic Agents↗
PubMed2002

The multidrug resistance transporter ABCG2 (breast cancer resistance protein 1) effluxes Hoechst 33342 and is overexpressed in hematopoietic stem cells.

The human ATP-binding cassette superfamily G (White) member 2 (ABCG2) gene and its murine homologue breast cancer resistance protein 1 (Bcrp1) are recently described ATP-binding cassette transporters associated with drug resistance in tumor cell lines, including the MCF-7 cell line, selected for its resistance to mitoxantrone (MCF-7/MitoR). Infection of MCF-7 cells with the retroviral vector containing ABCG2 cDNA (G1-ABCG2) resulted in cells (MCF-7/ABCG2) that were resistant to mitoxantrone at levels similar to those observed in MCF-7/MitoR cells. Previous studies have shown that pluripotent hematopoietic stem cells overexpress the multidrug-resistant transport (MDR1) gene and efflux rhodamine, a substrate for the MDR1 transporter. Other studies have identified a primitive hematopoietic stem cell population, or side population (SP) cells, which are identified by their efflux of the fluorescent dye, Hoechst 33342. In an attempt to identify the transport genes responsible for this phenotype, we examined the uptake of Hoechst 33342 into MCF-7, MCF-7/MitoR, and MCF-7 cells infected with a retroviral vector expressing the ABCG2 gene (MCF-7/ABCG2). MCF-7/MitoR cells as well as MCF-7/ABCG2 cells demonstrated lower levels of Hoechst 33342 uptake compared with the parental MCF-7 cells. We also examined the level of the mouse Bcrp1 RNA in SP cells and non-SP cells isolated from mouse hematopoietic cells. Mouse SP cells expressed relatively high levels of Bcrp1 mRNA relative to non-SP cells. These results suggest that Hoechst 33342 is a substrate for the ABCG2 transporter and that ABCG2/Bcrp1 expression may serve as a marker for hematopoietic stem cells in hematopoietic cells.

ATP Binding Cassette Transporter, Subfamily G, Mem↗
PubMed1995

Cost aspects of palliative cancer care.

Increasing concern is evident about the cost of palliative cancer care, a concern stemming from both government interest in cost containment and the growing nongovernment use of payment rates that are fixed in advance. In general, data on the cost-effectiveness of palliative cancer care are mixed; some types of palliative care appear to increase costs, while other forms may reduce overall costs of treatment. Pain management, however, is an area that seems to present significant opportunity for cost savings in palliative care if oral medications are used instead of high-technology modalities.

Antineoplastic Agents↗
PubMed1994

Maturation arrest of stem cell differentiation is a common pathway for the cellular origin of teratocarcinomas and epithelial cancers.

Analysis of the cellular origin of carcinomas of different organs indicates that there is in each instance, a determined stem cell required for tissue renewal that is the cell of origin for carcinomas. The normal tissue-determined stem cells are the result of differentiation in the embryo and are little changed, if at all, from the embryonic cells. Malignant stem cells are derived from these normal stem cells of adult tissues. The resultant tumors are caricatures of the normal process of tissue renewal with many stem cells and imperfect differentiation (14). This imparts an undifferentiated appearance to the tumors, not a dedifferentiated one. Study of the regulation of normal stem cells in the embryo should lead to rational therapies for malignant ones, and conversely, study of secretions and regulation of malignant stem cells will provide insights into normal regulation. The cancer-derived differentiated cells are benign (12, 74) if not normal (39, 53) leading to the conclusion that attempts to direct normal differentiation of malignant stem cells might serve as an alternative to cytotoxic therapy. Attempts to develop such therapies are currently underway (208). The degree of differentiation of a carcinoma depends on the proportion of undifferentiated tumor stem cells, the stage of maturation arrest of the majority of cells in the tumor, and on the ability of some cells to escape arrest and to differentiate (Fig. 1). These concepts of the stem cell contribution to tumors originated largely from studies of teratocarcinoma (209) and were not widely accepted because many considered the lessons learned were unique to teratocarcinomas and would not apply to other tissues. On the basis of the concepts covered in this review, it is clear that teratocarcinomas are unique only in the potential of their stem cells. Other stem cells have more limited potential. The balance of expression of the differentiated histiotype of the tumor cell lineage and the undifferentiated phenotype of the tumor stem cells determine the morphology of the tumor. Normal tissue renewal of epithelial organs is also from stem cells or their differentiating progeny. The cellular events during liver development and regeneration and the changes that precede the development of liver cancer during hepatocarcinogenesis are similar to the cellular response in pancreas, prostate, breast, lung, and gut. In liver, as in the leukopoietic system, the primitive tissue-specific stem cell is not primarily involved in renewal because that would be too slow a process; individuals would die before generation of sufficient replacement cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Adenocarcinoma↗
PubMedDate not supplied

[Intensive chemotherapy in the treatment of patients with metastatic breast cancer].

PURPOSE: Phase II study with intensive chemotherapy and autologous stem cells support in patients with metastatic breast cancer. METHODS: Forty-nine patients were treated with high-doses of two cytotoxic drugs and support with stem cells obtained from several leukapheresis without movilitation. The cells were reinfused forty-eight hours after finishing the administration of chemotherapy. RESULTS: Twenty-one patients (47%, CI-95%: 32.4-63.3%) achieved a complete remission. The objective responses rate was 73% (CI-95%: 57.2-85%). Overall and progression-free survival up to 4 years were 31% and 20%, respectively. Ten patients remain progression-free among 17 and 46 months. The most frequent extramedullary toxicity was hepatic and renal. Three patients (6%) died during the procedure. CONCLUSIONS: Intensive chemotherapy with hematopoietic support yields, with a moderate toxicity, a high objective response and complete remission rate. A small group of patients achieves a long progression-free survival.

Acute Kidney Injury↗
PubMedDate not supplied

Acute hematologic feasibility of G-CSF supported dose-escalated FEC therapy as adjuvant treatment after breast cancer surgery.

A study of the feasibility of gradually increased epirubicin and cyclophosphamide dosage in an FEC regimen with G-CSF (granulocyte colony stimulating factor) support in 18 high-risk breast cancer patients as adjuvant treatment was carried out. The FEC regimen was initiated with 5-fluorouracil 600 mg/m2, epirubicin 75 mg/m2 and cyclophosphamide 900 mg/m2 together with G-CSF 5 micrograms/kg subcutaneously on days 2-15 q 3 weeks for nine cycles, increasing individually through four dose levels to a maximum of 5-FU 600 mg/m2 (not escalated), epirubicin 120 mg/m2 and cyclophosphamide 1800 mg/m2. Transient cytopenias were regularly observed without major clinical complications. Rapid recovery and a biphasic overshoot of granulocytes required individualization of G-CSF support. During the 6-month treatment period, a general decline in granulocytes, platelets and haemoglobin was observed, resulting in maximal dose intensity in the middle of the treatment period. Compared to a conventional FEC regimen (5-Fluorouracil 600 mg/m2, Epirubicin 60 mg/m2, Cyclophosphamide 600 mg/m2 q 3 w) without dose reductions, it was feasible to increase the dose of epirubicin by more than 50 per cent with an increased dose intensity between 25 and 70 per cent. The dose of cyclophosphamide was increased by more than 100 per cent. All patients suffered from complete alopecia and moderate nausea, but there was no acute cardiac or severe mucosal toxicity. It was concluded that intensified, G-CSF supported FEC therapy can be safely administered in an outpatient setting, provided the patients are thoroughly informed and adequately monitored. High-risk patients are enrolled in a study comparing the described regimen and a myeloablative regimen including peripheral stem-cell support. Breast cancer seems to respond to chemotherapy in a dose dependent manner, suggesting the use of dose intensified regimens (1,8,9,11). This approach is currently under investigation in studies comparing standard regimens with myelo-ablative regimens in high-risk primary breast cancer (3,10). In a Scandinavian multicenter study (2), two high dose regimens, G-CSF supported dose-escalated FEC and myeloablative cyclophosphamide-thiotepacarboplatin with peripheral stem cell support, are compared as adjuvant therapy in operable high-risk breast cancer. This phase I study was performed to assess the feasibility and achievable dose intensity of an individually dose-escalated FEC regimen not in previous use.

Adult↗
PubMed2004

The use of high-dose cyclophosphamide, carmustine, and thiotepa plus autologous hematopoietic stem cell transplantation as consolidation therapy for high-risk primary breast cancer after primary surgery or neoadjuvant chemotherapy.

We assessed the 5-year results of a high-dose cyclophosphamide, carmustine, and thiotepa (CBT) regimen plus autologous hematopoietic stem cell transplantation (AHST) as an adjuvant consolidation therapy for high-risk primary breast cancer patients with > or =10 positive axillary lymph nodes after primary surgery or > or =4 positive axillary lymph nodes after neoadjuvant chemotherapy and surgery. The associations of various potential prognostic factors with the relapse-free survival (RFS) rate and overall survival (OS) rate were determined. Between October 1992 and March 2000, 177 eligible patients (median age, 46 years) were given high-dose CBT followed by AHST. At a median follow-up of 63 months, the acute treatment-related mortality was 4.5%. Estimated 5-year RFS and OS rates were 62% and 68%, respectively, for all patients. For patients with > or =10 positive axillary lymph nodes after primary surgery, the 5-year RFS and OS rates were 71% and 70%, respectively, and for patients with > or =4 positive axillary lymph nodes after neoadjuvant chemotherapy, the 5-year RFS and OS rates were 53% and 66%, respectively. In 2-sided log-rank tests, earlier disease stage, a lower lymph node ratio, and a lower tumor score were associated with a prolonged RFS and OS. In a multivariate proportional hazards model, disease stage and lymph node ratio remained significant. We concluded that high-dose CBT with AHST for high-risk primary breast cancer is feasible, with comparable efficacy to other phase II studies. More than a 50% estimated 5-year survival rate was seen in all high-risk primary breast cancer patients. In accordance with results from recent randomized studies, we need to continue high-dose chemotherapy with AHST for patients with high-risk primary breast cancer in the phase III randomized setting.

Adult↗
PubMed1996

Treatment of children with newly diagnosed brain stem gliomas with intravenous recombinant beta-interferon and hyperfractionated radiation therapy: a childrens cancer group phase I/II study.

BACKGROUND: Prognosis for the majority of children with brain stem gliomas is dismal. In previous studies, recombinant beta-interferon (r beta IF) has been shown to be effective for children with recurrent brain stem gliomas and may also act synergistically with radiotherapy (RT). METHODS: Thirty-two children with diffuse intrinsic brain stem gliomas were treated with (r beta IF) and 7200 centigray (cGy) of hyperfractionated RT (100 cGy twice-daily fractions) to determine the toxicity of treatment and the tolerance of the brain stem to this regimen, as well as to assess survival. Patients were treated with r beta IF 3 times per week during RT and then for 8 weeks following RT. Initially, a dose escalation trial was performed. RESULTS: Interferon was initially begun at 12.5 x 10(6) IU/m2 and escalated up to 400 x 10(6) IU/m2. The safe starting dose was determined to be 100 x 10 (6) IU/m2. Due to unacceptable toxicity, the maintenance dose was reduced to 200 x 10 (6) IU/m2. Therapy was relatively well tolerated, although 13 of the patients required dose modifications due to hepatic or hematologic toxicity. Four of the patients had to discontinue treatment due to this toxicity. One patient died while receiving maintenance IF of encephalopathy, seizures, and brain stem dysfunction; believed possibly due to the r beta IF. Thirty of the 32 patients have developed progressive disease. The median time to progression from study entry was five months and the median time to death was 9 months. CONCLUSIONS: We conclude that r beta IF plus hyperfractionated therapy can be tolerated by children with newly diagnosed brain stem gliomas, although there is occasional dose-limiting hepatic, blood, and central nervous system toxicity. This therapy did not result in a higher rate of disease control.

Adolescent↗
PubMed2003

A randomised study of 10 microg/kg/day (single dose) vs 2 x 5 microg/kg/day (split dose) G-CSF as stem cell mobilisation regimen in high-risk breast cancer patients.

A randomised trial in breast cancer patients was designed to compare the number of peripheral blood progenitor cells collected after mobilisation with a single dose of 10 microg/kg/day granulocyte colony-stimulating factor (G-CSF) (n=14) or a split dose of 5 microg/kg twice daily (n=14). Both groups were well balanced. No significant differences were observed between groups regarding aphereses parameters. The total number of CD34+ cells collected was higher in the split-dose group (mean of 7.1 and median of 7.4 x 10(6)/kg) than in the single-dose group (5.6 and 5.8 x 10(6)/kg, respectively) (P=0.26). The mean of CD34+ cells collected after the first apheresis procedure was 3.9 x 10(6)/kg for the split dose group and 3.1 x 10(6)/kg for the single-dose group (P=0.24). Circulating CD34+ cells before the first apheresis were higher for the split-dose group (mean 79.7 vs 59.2 x 10(6)/l) (P=0.14). All bone pain scores applied were significantly higher for the split-dose group. Our primary end point of improving the mean of total CD34+ cells collected to 2.5 x 10(6)/kg was not achieved with twice-daily G-CSF administration. Further studies evaluating different mobilisation schedules with G-CSF are needed to determine the optimal regimen.

Adult↗
PubMed1997

Tandem high-dose therapy with ifosfamide, epirubicin, carboplatin and peripheral blood stem cell support is an effective adjuvant treatment for high-risk primary breast cancer.

We evaluated the therapeutic efficacy and toxicity of a tandem high-dose therapy with peripheral blood stem cell (PBSC) support in 40 patients with high-risk, primary breast cancer (stage II-III) and involvement of ten or more positive axillary lymph nodes. Their median age was 44 years (range 23-56). Two cycles of cytotoxic chemotherapy with ifosfamide (10000 mg/m2) and epirubicin (100 mg/m2) were administered. Granulocyte colony-stimulating factor (G-CSF) was given to hasten neutrophil reconstitution and to mobilise PBSC during marrow recovery. Leukaphereses were performed following the first and/or second cycle. Tandem high-dose therapy consisted of two cycles with ifosfamide (15 or 12 g/m2) and epirubicin (150 mg/m2), while carboplatin (900 mg/m2) was added for the last 24 patients included. Using an immunocytochemical method, two of 11 patients had cytokeratin-positive tumour cells in three leukapheresis products that were collected following the first G-CSF-supported cycle with ifosfamide and epirubicin, whereas only two harvests obtained following the second cycle in 26 patients contained cytokeratin-positive tumour cells. The number of CD34+ cells/kg re-infused following both high-dose cycles was similar (4.20 +/- 0.29 x 10(6), first cycle and 5.25 +/- 0.63 x 10(6), second cycle), and no notable difference was noted in the speed of haematological reconstitution. An absolute neutrophil count (ANC) of 0.5 x 10(9)/1 was reached after a median time of 13 days, while an unsupported platelet count of 20.0 x 10(9)/1 was achieved after a median time of 8 (first cycle) and 9 (second cycle) days post-transplantation. Patients autografted with more than 7.5 x 10(6) CD34+ cells/kg had platelet counts above 20 x 10(9)/1 within less than 10 days. 6 patients relapsed between 7 and 11 months (median 8 months) post-transplantation. 37 patients are alive and in remission with a median follow-up time of 11 months (range 1-38). This translates into a probability of disease-free survival (DFS) of 77% (95% CI 32-95%) at 38 months. The probability of overall survival is 85%, since 3 patients with local relapse achieved a second complete remission following surgery and involved-field radiotherapy. In conclusion, a sequential high-dose therapy including ifosfamide, epirubicin, carboplatin and PBSC support is well tolerated and effective in patients with high-risk primary breast cancer. Involved-field irradiation should be performed post-transplantation to reduce the risk of local relapse.

Adult↗
PubMed2005

Incidence and etiology of cerebrovascular disease in patients with malignancy.

Cerebrovascular disease is common in cancer patients and often arises from mechanisms unique to malignancy. Direct tumor effects include intratumoral hemorrhage, arterial and venous sinus invasion by tumor mass or leptomeningeal infiltrates, and tumor emboli. Complications of chemotherapy, radiation therapy, and hematopoietic stem-cell transplantion for cancer can occur before, during, or years after treatment. Coagulopathic conditions involve disseminated intravascular coagulation, thrombocytopenia, nonbacterial thrombotic endocarditis, and cerebral intravascular coagulation. Finally, septic infarction from fungal or bacterial sepsis and infectious vasculitis manifest in cancer patients immunocompromised by malignancy or cancer therapy. In many cases a combination of mechanisms is causative, and both hemorrhagic and ischemic stroke can occur simultaneously. Stroke type and mechanism, as well as the stage and pathology of the neoplasm, dictate proper management and help delineate prognosis.

Antineoplastic Agents↗
PubMed2005

A multicenter randomized clinical trial evaluating interleukin-2 activated hematopoietic stem cell transplantation and post-transplant IL-2 for high risk breast cancer patients.

PURPOSE: This Phase III randomized multicenter trial compared progression-free (PFS) and overall survival (OS) for autologous peripheral blood stem cell (aPBSC) transplantation with or without immunotherapy in high-risk breast cancer patients. METHODS: Eligible patients had American Joint Committee on Cancer (AJCC) 5th Edition Stage II/IIIA with > or = 4 axillary nodes, Stage IIIB, or chemotherapy-sensitive or stable Stage IV disease. Following treatment with cyclophosphamide, thiotepa and carboplatin (STAMP V), patients were randomized to aPBSC transplant with or without immunotherapy. Patients on immunotherapy received cells that were incubated in interleukin-2 (IL-2) for 24 h followed by parenteral IL-2 for 5 days then 2 days of rest for 4 weeks. RESULTS: Fifty-nine patients were treated (35 Stage II/IIIA; 13 Stage IIIB; 11 Stage IV), 30 patients were randomized to immunotherapy and 29 patients to no immunotherapy. Neutrophils engrafted a median of 10 days post-transplant in both groups. The median times to platelet engraftment were 9 and 10 days after transplant in the no-immunotherapy and immunotherapy groups, respectively (p = 0.03). There was no statistical evidence (p = 0.61) of a difference in progression-free and surviving (PFS) at 3 years for patients receiving immunotherapy (53%) compared with no immunotherapy (48%). There was some evidence of superiority in overall survival (OS) at 3 years for patients receiving immunotherapy (83%) compared with no immunotherapy (69%), but the difference between survival curves was not statistically significant (p = 0.08). Also, there was some evidence that patients developing acute graft versus host disease (aGVHD) had superior PFS (p = 0.02) but not OS (p = 0.19) than patients not developing aGVHD. Toxicities were transient and similar between groups, with no treatment-related deaths. CONCLUSIONS: This phase III study of high-risk breast cancer patients randomized to immunotherapy or no immunotherapy demonstrated that a well-tolerated immunotherapy regimen added to aPBSC transplant did not improve PFS, but there was some improvement in OS, but not by an amount that was statistically significant (p = 0.08).

Adolescent↗
PubMed2005

Biological purging of breast cancer cell lines using a replication-competent oncolytic virus in human stem cell autografts.

Autologous hematological stem cell transplantation (ASCT) is used for the treatment of many hematological and several solid cancers. ASCT, however, has proven disappointing as a therapeutic strategy for breast cancer. Our group and others have previously shown that breast cancer micrometastases found in patients' apheresis products (APs) predict shorter progression-free and overall survival. The implications of this finding are twofold: (i) contaminating tumor cells (CTCs) in AP reflect a higher systemic disease burden and/or (ii) reinfused CTCs contribute to relapse/progressive disease. To date, purging strategies have been disappointing. We have previously demonstrated the oncolytic properties of reovirus in in vitro, in vivo and ex vivo systems. In the present study, we tested the hypothesis that reovirus purges CTCs in a breast cancer cell line purging model. Reovirus-infected human breast cancer cell lines (HTB 133, HTB 132, SKBR3 and MCF7) exhibited cell death within days. Admixtures of AP with cells from breast tumor cell lines, which were then exposed to reovirus, showed complete purging of CTCs (assessed via flow cytometry/tumor cell outgrowth analysis) without deleterious effect on CD34+ cells. Our results provide preclinical support for the ex vivo use of reovirus as a purging modality for breast cancer during ASCT.

Antigens, CD34↗
PubMed2006

Melanoma, a tumor based on a mutant stem cell?

Stem cells play a critical role in normal tissue maintenance, and mutations in these stem cells may give rise to cancer. We hypothesize that melanoma develops from a mutated stem cell and therefore residual stem cell characteristics should be able to be identified in melanoma cell lines. We studied three metastatic melanoma cell lines that exhibited multiple morphologic forms in culture and demonstrated the capacity to pigment. We used the ability to efflux Hoechst 33342 dye, a technique known to enrich for stem cells in many tissues, to segregate cell populations. The cells with the greatest ability to efflux the dye were (1) small in size, (2) had the capacity to give rise to larger cell forms, and (3) had the greatest ability to expand in culture. The small cells were found to have a decreased proliferative rate and were less melanized. Large dendritic cells that appeared to be nonproliferative were identified in cultures. Treatment with cytosine beta-D-arabinofuranoside hydrochloride (Ara-C) expanded the large cell population but the residual proliferative capacity, both in vitro and in vivo, remained concentrated in the smaller cell fraction. Antigenic staining patterns were variable and heterogeneous. Nestin (a neural stem cell marker) and gp100 (premelanosomal marker) favored the smaller cell population, while nerve growth factor receptor often labeled larger cells. Morphologic and antigenic heterogeneity remained intact after clonal purification. These findings are consistent with the behavior expected for a tumor based on stem cell biology; this finding has diagnostic and therapeutic implications for melanocytic neoplasias.

Antigens, Neoplasm↗