Mullerian inhibiting substance preferentially inhibits stem/progenitors in human ovarian cancer cell lines compared with chemotherapeutics

Cancer stem cells are proposed to be tumor-initiating cells capable of tumorigenesis, recurrence, metastasis, and drug resistance, and, like somatic stem cells, are thought to be capable of unlimited self-renewal and, when stimulated, proliferation and differentiation. Here we select cells by expression of a panel of markers to enrich for a population with stem cell-like characteristics. A panel of eight was initially selected from 95 human cell surface antigens as each was shared among human ovarian primary cancers, ovarian cancer cell lines, and normal fimbria. A total of 150 combinations of markers were reduced to a panel of three--CD44, CD24, and Epcam--which selected, in three ovarian cancer cell lines, those cells which best formed colonies. Cells expressing CD44, CD24, and Epcam exhibited stem cell characteristics of shorter tumor-free intervals in vivo after limiting dilution, and enhanced migration in invasion assays in vitro. Also, doxorubicin, cisplatin, and paclitaxel increased this enriched population which, conversely, was significantly inhibited by Müllerian inhibiting substance (MIS) or the MIS mimetic SP600125. These findings demonstrate that flow cytometry can be used to detect a population which shows differential drug sensitivity, and imply that treatment of patients can be individualized to target both stem/progenitor cell enriched and nonenriched subpopulations. The findings also suggest that this population, amenable to isolation by flow cytometry, can be used to screen for novel treatment paradigms, including biologic agents such as MIS, which will improve outcomes for patients with ovarian cancer.     

Ovarian cancer side population defines cells with stem cell-like characteristics and Mullerian Inhibiting Substance responsiveness

The recent identification of "side population" (SP) cells in a number of unrelated human cancers and their normal tissue sources has renewed interest in the hypothesis that cancers may arise from somatic stem/progenitor cells. The high incidence of recurrence attributable to multidrug resistance and the multiple histologic phenotypes indicative of multipotency suggests a stem cell-like etiology of ovarian cancer. Here we identify and characterize SP cells from two distinct genetically engineered mouse ovarian cancer cell lines. Differential efflux of the DNA-binding dye Hoechst 33342 from these cell lines defined a human breast cancer-resistance protein 1-expressing, verapamil-sensitive SP of candidate cancer stem cells. In vivo, mouse SP cells formed measurable tumors sooner than non-SP (NSP) cells when equal numbers were injected into the dorsal fat pad of nude mice. The presence of Mullerian Inhibiting Substance (MIS) signaling pathway transduction molecules in both SP and NSP mouse cells led us to investigate the efficacy of MIS against these populations in comparison with traditional chemotherapies. MIS inhibited the proliferation of both SP and NSP cells, whereas the lipophilic chemotherapeutic agent doxorubicin more significantly inhibited the NSP cells. Finally, we identified breast cancer-resistance protein 1-expressing verapamil-sensitive SPs in three of four human ovarian cancer cell lines and four of six patient primary ascites cells. In the future, individualized therapy must incorporate analysis of the stem cell-like subpopulation of ovarian cancer cells when designing therapeutic strategies for ovarian cancer patients.     

Mullerian Inhibiting Substance enhances subclinical doses of chemotherapeutic agents to inhibit human and mouse ovarian cancer

Mullerian Inhibiting Substance (MIS), a biological modifier that causes regression of Mullerian ducts in male embryos, is effective as a single agent in vitro and in vivo against human and mouse ovarian cancer cell lines expressing MIS type II receptor; however, little is known about how recombinant human MIS (rhMIS), now being scaled for preclinical trials, could be used in combination with cytotoxic or targeted chemotherapeutic agents. Mouse serous and endometrioid ovarian carcinoma cell lines were tested in vitro against rhMIS alone and with doxorubicin, paclitaxel, or cisplatin as agents in clinical use. Because MIS releases FK506 binding protein (FKBP12), which activates the mammalian target of rapamycin (mTOR) downstream of Akt, rhMIS and rapamycin combinations were tested. MIS increases p16 protein levels, and 5'-Aza-2'-deoxycytidine (AzadC) induces p16 mRNA; therefore, they were used in combination in vitro and in vivo with a human ovarian cancer cell line. A paclitaxel-resistant human ovarian cancer cell line and its parental line both respond to rhMIS in vitro. Additivity, synergy, or competition was observed with MIS and rapamycin, AzadC, doxorubicin, cisplatin, and paclitaxel, suggesting that MIS in combination with selective targeted therapies might achieve greater activity against ovarian cancer than the use of each individual agent alone. These assays and statistical analyses could be useful in selecting rhMIS and chemotherapeutic agent combinations that enhance clinical efficacy and reduce toxicity.     

卵巢癌CD90^＋肿瘤细胞的分离及其肿瘤干细胞生物学特性观察

目的：分离人卵巢癌细胞系SKOV3和原代卵巢癌细胞中的CD90^＋细胞,并观察其肿瘤干细胞的生物学特性。方法从卵巢癌患者腹水中分离原代卵巢癌细胞,采用流式细胞术检测人卵巢癌细胞系SKOV3和原代卵巢癌细胞的CD133、CD90阳性率。流式分选得到CD90^＋、CD90^-细胞后,采用RT-PCR法检测其干细胞及上皮间质化（EMT）相关基因mRNA相对表达,Transwell小室侵袭试验观察细胞侵袭力,克隆形成试验观察细胞增殖分化能力,悬浮成球试验观察干细胞潜能,免疫缺陷小鼠体内有限稀释成瘤试验观察成瘤时间和成瘤率。结果人卵巢癌细胞系SKOV3的CD133和CD90阳性率均低于原代卵巢癌细胞,P均＜0．05。在人卵巢癌细胞系SKOV3和原代卵巢癌细胞中,CD90^＋细胞干细胞相关基因（CD133、OCT4）和EMT间质标志相关基因（N-cadherin、Vimentine、MMP9）相对表达、穿到膜背面的细胞数、细胞克隆数、悬浮成球数均高于CD90^-细胞,EMT上皮标志相关基因E-cadherin相对表达均低于CD90^-细胞,P均＜0．05。随着接种细胞数目的增加,CD90^＋、CD90^-细胞的成瘤率和成瘤时间均升高,CD90^＋细胞升高更明显。结论卵巢癌细胞中,CD90^＋细胞高表达间质属性基因和干细胞相关基因,具备更高的侵袭力、增殖分化能力、体内成瘤能力和干细胞潜能,CD90^＋细胞分离可能成为卵巢癌干细胞分离的新方法。     

Neuroblastoma stem cells - mechanisms of chemoresistance and histonedeacetylase inhibitors

Cancer stem cells (CSCs) form a?small proportion of tumor cells that have stem cell properties: self-renewal capacity, the ability to develop into different lineages and proliferative potential. The interest in CSCs emerged from their expected role in initiation, progression and recurrence of many tumors. They are generally resistant to conventional chemotherapy and radiotherapy. There are two hypotheses about their origin: The first assumes that CSCs may arise from normal stem cells, and the second supposes that differentiated cells acquire the properties of CSCs. Both hypotheses are not mutually exclusive, as it is possible that CSCs have a?diverse origin in different tumors. CD133+ cells (CD133 is marker of CSC in some tumors) isolated from NBL, osteosarcoma and Ewing sarcoma cell lines are resistant to cisplatin, carboplatin, etoposide and doxorubicin than the CD133- ones. Being resistant to chemotherapy, there were many attempts to target CSCs epigenetically including the use of histone deacetylase inhibitors. The diverse influence of valproic acid (histone deacetylase inhibitor) on normal and cancer stem cells was proved in different experiments. We have found an increase percentage of CD133+ NBL cells after their incubation with VPA in a?dose that does not induce apoptosis. Further researches on CSCs and clinical application for their detection are necessary: (i) to define the CSC function in carcinogenesis, cancer development and their role in metastasis; (ii) to find a?specific marker for CSCs in different tumors; (iii) to explain the role of different pathways that determine their behavior and (iv) to explain mechanisms of chemoresistance of CSCs. Keywords: Cancer stem cells; CD133; Neuroblastoma; Histone deacetylase inhibitors.     

Ovarian cancer stem cells

Because of its semi-solid character in dissemination and growth, advanced ovarian cancer with its hundreds of peritoneal tumor nodules and plaques appears to be an excellent in vivo model for studying the cancer stem cell hypothesis. The most important obstacle, however, is to adequately define and isolate these tumor-initiating cells endowed with the properties of anoikis-resistance and unlimited self-renewal. Until now, no universal single marker or marker constellation has been found to faithfully isolate (ovarian) cancer stem cells. As these multipotent cells are known to possess highly elaborated efflux systems for cytotoxic agents, these pump systems have been exploited to outline putative stem cells as a?side-population (SP) via dye exclusion analysis. Furthermore, the cells in question have been isolated via flow cytometry on the basis of cell surface markers thought to be characteristic for stem cells.In the Vienna variant of the ovarian cancer cell line A2780 a?proof-of-principle model with both a?stable SP and a?stable ALDH1A1+ cell population was established. Double staining clearly revealed that both cell fractions were not identical. Of note, A2780V cells were negative for expression of surface markers CD44 and CD117 (c-kit). When cultured on monolayers of healthy human mesothelial cells, green-fluorescence-protein (GFP)-transfected SP of A2780V exhibited spheroid-formation, whereas non-side-population (NSP) developed a?spare monolayer growing over the healthy mesothelium. Furthermore, A2780V SP was found to be partially resistant to platinum. However, this resistance could not be explained by over-expression of the "excision repair cross-complementation group 1" (ERCC1) gene, which is essentially involved in the repair of platinated DNA damage. ERCC1 was, nonetheless, over-expressed in A2780V cells grown as spheres under stem cell-selective conditions as compared to adherent monolayers cultured under differentiating conditions. The same was true for the primary ovarian cancer cells B-57.In summary our investigations indicate that even in multi-passaged cancer cell lines hierarchic government of growth and differentiation is conserved and that the key cancer stem cell population may be composed of small overlapping cell fractions defined by various arbitrary markers. Keywords: ovarian cancer, stem cell, side-population, mesothelium-co-culture, flow cytometry, ERCC1.     

Detection of tumor stem cell markers in pancreatic carcinoma cell lines

IntroductionT he cell population of most tumors is hetero- geneous with regard to its proliferation capacity, apoptosis-resistance mechanisms, and ability to reconstitute the tumor upon xeno-transplantation. This phenomenon arises as the result of accumulation of multiple genetic and epigenetic changes. Current evidence suggests that only a few cells within the tumor, the cancer stem cells, possess unlimited proliferative capacity and give rise to tumors that phenotypically resemble their init…     

Mullerian Inhibiting Substance inhibits cervical cancer cell growth via a pathway involving p130 and p107

In addition to causing regression of the Mullerian duct in the male embryo, Mullerian Inhibiting Substance (MIS) inhibits the growth of epithelial ovarian cancer cells, which are known to be of Mullerian origin. Because the uterine cervix is derived from the same Mullerian duct precursor as the epithelium of the ovary, we tested the hypothesis that cervical cancer cells might also respond to MIS. A number of cervical cancer cell lines express the MIS type II receptor, and MIS inhibits the growth of both human papilloma virus-transformed and non-human papilloma virus-transformed cervical cell lines, with a more dramatic effect seen in the latter. As in the ovarian cancer cell line OVCAR8, suppression of growth of the C33A cervical cancer cell line by MIS is associated with induction of the p16 tumor suppressor protein. However, in contrast to OVCAR8 cells, induction of p130 and p107 appears to play an important role in the inhibition of growth of C33A cells by MIS. Finally, normal cervical tissue expresses the MIS type II receptor in vivo, supporting the idea that MIS could be a targeted therapy for cervical cancer.     

A subpopulation of CD24⁺ cells in colon cancer cell lines possess stem cell characteristics

Cancer stem cells (CSCs) have been shown to contribute to the resistance and relapse in a range of cancer types such as breast cancer and glioma. However, colon cancer stem cells remain poorly characterized. Here we reported that CD24+ subpopulation in colon cancer cell lines HCT116 and SW480 exhibited cancer stem cell-like characteristics. Using flow cytometry candidate CSCs markers were selected after initial screening of known CSCs markers from other types of cancer on colon cancer cell lines HCT116, SW480 and HT29. CD24 was expressed in the minority of bulk cell population of HCT116 and SW480 cell lines. Moreover, functional tests demonstrated that CD24+ cells exhibited enhanced chemotherapy-resistance, self-renewal and tumorigenic capacity both in vitro and in vivo, compared to CD24- subpopulations. These results suggest that CD24+ subpopulation in colon cancer cell lines HCT116 and SW480 exhibits CSCs like characteristics, and represents a nice model to study and develop effective strategies to overcome chemo-resistance and relapse of colon cancer.     

The use of Shiga-like toxin 1 in cancer therapy.

The ribosome-inactivating protein, Shiga-like toxin-1 (SLT-1, SLT-I, Verotoxin 1, VT1) targets cells that express the glycolipid globotriaosylceramide (CD77) on their surface. The frequent occurrence of SLT-1 receptors on tumor cells derived from patients with hematological cancers (follicular lymphoma, multiple myeloma, chronic lymphocytic leukemia) and their absence on human CD34(+) hematopoietic stem cells suggest the ex vivo use of Shiga-like toxin-1 in purging CD77(+) tumor cells from autologous stem cell transplants. SLT-1 receptors are also commonly expressed on breast cancer, ovarian cancer and astrocytoma cells. In particular, the sensitivity of astrocytoma cell lines to this toxin provides an opportunity for using SLT-1 in vivo in the context of treating patients afflicted by this common form of brain tumor. Finally, the known structural features of SLT-1 allow one to contemplate altering its receptor specificity in an effort to target CD77(-) tumor cell populations.     

胃癌干细胞的分离鉴定以及干细胞特性研究

背景:肿瘤干细胞(CSCs)已成为当前肿瘤研究的热点之一,开展相关研究的首要问题是CSCs的分离和鉴定,悬浮培养法是分离CSCs的重要方法。目的:分离、鉴定胃癌干细胞(GCSCs)并评价其干细胞特性。方法:人胃癌细胞株MKN45、MGC803、SGC7901以含表皮生长因子(EGF)、碱性成纤维细胞生长因子(bFGF)的无血清培养基悬浮培养。对培养得到的第三代肿瘤球,以集落形成实验检测其克隆形成能力,免疫荧光法检测GCSCs标记物,细胞划痕实验和Transwell小室细胞侵袭实验检测其迁移、侵袭能力,CCK-8实验检测其对顺铂的耐药性。结果:培养得到的肿瘤球高表达干细胞标记物CD44、CD54,低表达胃壁细胞标记物H+/K+-ATPase,克隆形成能力、划痕愈合速度和Transwell小室穿膜细胞数明显大于或多于普通胃癌细胞,差异有统计学意义(P0.05)。顺铂对肿瘤球的50%抑制浓度明显高于普通胃癌细胞。结论:应用无血清培养基悬浮培养法能成功获得GCSCs富集的肿瘤球;肿瘤球具有较强的自我更新、增殖、迁移、侵袭能力和多向分化潜能,对化疗药物更易产生耐药性。     

Adenovirus-mediated delivery of p53 results in substantial apoptosis to myeloma cells and is not cytotoxic to flow-sorted CD34(+) hematopoietic progenitor cells and normal lymphocytes

Multiple myeloma (MM) is an incurable disease; therefore, there is a need for new modalities of treatment for this disease. We designed a study to test the sensitivity of MM cell lines, freshly isolated myeloma cells, and CD34(+) hematopoietic progenitor cells to adenovirus-mediated delivery of wild-type p53 (Ad-p53). Replication-deficient Ad-p53, previously used in phase I-II clinical trial for treatment of patients with solid tumors, was used in this study. Myeloma cells from seven MM cell lines with mutated or w.t. p53 and varying expression of bcl-2 were used. Fresh myeloma cells (CD38(bright)CD45(-)) and fresh CD34(+) hematopoietic stem cells and CD34(-) cells were purified by flow sorting of apheresis collections of MM patients undergoing high-dose chemotherapy and stem cell rescue. The effect of Ad-p53 on colony-forming unit granulocyte-macrophage (CFU-GM) and burst-forming unit erythroid (BFU-E) colony formation in methylcellulose was tested on purified CD34(+) and CD34(-) cells to evaluate bone marrow toxicity.Myeloma cells from cell lines, or freshly isolated myeloma cells, were sensitive to Ad-p53 only if they had mutated p53 and had low expression of bcl-2. CD34(+) cells were resistant to Ad-p53-mediated apoptosis, and CFU-GM and BFU-E colony formation was not affected by treatment with Ad-p53.Ad-p53 is a potent inducer of apoptosis in MM cell lines and in freshly isolated myeloma cells expressing low levels of bcl-2. Ad-p53 is not overtly cytotoxic to normal hematopoietic stem cells or normal lymphocytes; therefore, it could be considered for a phase I clinical trial of MM patients with mutated p53.     

Endometrial cancer is a receptor-mediated target for Mullerian Inhibiting Substance

Mullerian Inhibiting Substance (MIS), a 140-kDa homodimer glycoprotein member of the TGF-beta superfamily of biological-response modifiers, causes regression of the Mullerian ducts in developing male embryos. MIS also can induce growth arrest and apoptosis in ovarian and cervical cancer cell lines. The embryonic progenitor of the ovarian and cervical epithelium is the coelomic epithelium, the same tissue that regresses under the direction of MIS in the male. The endometrium and uterus also arise from the coelomic epithelium and the Mullerian ducts. Here, we show that both normal human endometrium and endometrial cancers express the receptor for MIS and that MIS can inhibit the proliferation of a number of human endometrial cancer cell lines that express the MIS type II receptor. In the representative endometrial cancer cell line AN3CA, MIS affects the expression of key cell-cycle regulatory proteins. This work broadens the scope of tumors that MIS can potentially control and, by elucidating the MIS signaling pathway, identifies other potential avenues for intervention.     

Haemopoietic colony-forming cells from peripheral blood stem cells harvests: cytokine requirements and lineage potential

Summary. We have measured the in vitro growth requirements of progenitor cells released into the blood of cancer patients following administration of chemotherapy and cytokines. In order to distinguish the direct effects of cytokines on progenitors from those activating acessory cells, we have comparied clonogenic grwoth before and after CD34-positive selection of progenitors, in serum-free conditions. CD34 selection had little effect on the cytokine requirements of erythroid colony-forming cells and single cytokines, particularly interleukin-3, could support considerable colony growth in both mononulear and CD34+ cell suspensions. Optimal erythroid colony grwoth, however, usually required the addition of a combination of stem cells factor and interleukin-3, in addition to erythoropoietin, which was was always required. Maximal numbers of granulocyte monocyte progenitors in mononuclear cell cultures, could be achieved with a mixture of stem cell factros, ionterleukin-3 and granulocyte-monocyte colony stimulating factor. How ever, after CD34 selection, full myeloid colony growth was only achieved when granulocyte colony stimulating factor was added to the above mixture. This presumably reflects loss of accessory cells, during CD34 selection, which produced this cytokine. When transplanted after 8 d of culutre. 16/22 myeloid colonies from erythorpoietin-free cultures of peripheral blood stem cell harvests, could generate secondary multipotential. However, surface marker analysis of individual erythroid colonies revealed only the occasional presence of granulocytes and monocytes. These date demonstrate that cytokine mixtures are required for optimal colony growth, particuarly after CD34 selection, a nd that most mobilizied, blood clonogenic cells are multipotential.     

FoxP3+ Regulatory T Cells in Peripheral Blood of Patients with Epithelial Ovarian Cancer

Background: Ovarian cancer is the fifth leading cause of death from malignancy in women. CD4 +CD25+FoxP3+ regulatory T (Treg) cells are a subset of T lymphocytes with great inhibitory impact on immune response. Objectives: To investigate the percentage of CD4 +CD25+FoxP3+ regulatory T cells in the peripheral blood of the Iranian patients with epithelial ovarian cancer compared to healthy women and to evaluate the correlation of the Treg cell percentage with clinicopathological characteristics including cancer stage and CA-125 serum level. Methods: Seventeen women with epithelial ovarian cancer and 20 healthy subjects were enrolled in the study. Peripheral blood mononuclear cells were stained at the surface, for CD4 and CD25 molecules, followed by fixation, permeabilization and intracellular staining for FoxP3 molecule. After processing and flowcytometry analysis, prevalence of Treg cells was determined as the percentages of CD25 +FoxP3+ cells among CD4+ lymphocytes. Results: Despite no difference in the percentage of total CD4+ lymphocytes, analysis indicated that Treg cell percentage was significantly higher in ovarian cancer patients than controls (5.7 ± 3.1% versus 2.8 ± 1.4%, p=0.002). A trend toward higher Treg cells was observed in higher stages of ovarian cancer (III+IV) in comparison to lower stages (I+II) (6.5 ± 3.2% vs. 4.44 ± 2.7%, p=0.2). Higher percentage of Treg cells was also observed in the patients with high CA125 (CA-125 >100 U/mL) in comparison to those with low CA-125 serum level (CA-125 ≤100 U/mL) although the difference was not significant (6.44 versus 4.18%, p=0.19). Conclusion: Increased frequency of Tregs in ovarian cancer might participate in immune suppression in these patients. The findings collectively suggest the likely impact of Treg cell–targeted immunotherapy in ovarian cancer.     

Circulation of CD34+ hematopoietic stem cells in the peripheral blood of high-dose cyclophosphamide-treated patients: enhancement by intravenous recombinant human granulocyte-macrophage colony-stimulating factor

We report that hematopoietic progenitor cells expressing the CD34 antigen (CD34+ cells) transiently circulate in the peripheral blood (PB) of cancer patients treated with 7 g/m2 cyclophosphamide (HD-CTX) with or without recombinant human granulocyte macrophage-colony stimulating factor (rHuGM-CSF). In adult humans, CD34+ cells represent a minor fraction (1% to 4%) of bone marrow (BM) cells, comprising virtually all hematopoietic colony-forming progenitors in vitro and probably also stem cells capable of restoring hematopoiesis of lethally irradiated hosts. We show that CD34+ cell circulation is fivefold enhanced by rHuGM-CSF 5.5 protein micrograms/kg/day by continuous intravenous infusion for 14 days after HD-CTX. During the third week after HD-CTX (ie, when CD34+ cells peak in the circulation), large-scale collection of PB leukocytes by three to four continuous-flow leukaphereses allows the yield of 2.19 to 2.73 x 10(9) or 0.45 to 0.56 x 10(9) CD34+ cells depending on whether or not patients receive rHuGM-CSF. The number of CD34+ cells retrieved from the circulation by leukaphereses exceeds the number that can be harvested by multiple BM aspirations under general anesthesia. Thus, after therapy with HD-CTX and rHuGM-CSF, PB represents a rich source of hematopoietic progenitors possibly usable for restoring hematopoiesis after myeloablative chemoradiotherapy. To determine whether CD34+ cells found in the PB are equivalent to their marrow counterpart, we evaluated their in vitro growth characteristics and immunological phenotype by colony assays and dual-color immunofluorescence, respectively. We show that PB CD34+ cells possess qualitatively normal hematopoietic colony growth and high cloning efficiency comparable to that observed with BM CD34+ cells. In addition, PB CD34+ cells display heterogeneous surface membrane differentiation antigens analogous to BM CD34+ cells. The availability of large quantities of CD34+ cells by leukapheresis is relevant to the field of stem cell transplantation and possibly to genetic manipulations of the hematopoietic system in humans.     

Mode of interaction between butyroyloxymethyl-diethyl phosphate (AN-7) and doxorubicin in MCF-7 and resistant MCF-7/Dx cell lines

Purpose To investigate the anticancer activity and mode of action of butyroyloxymethyl-diethyl phosphate (AN-7), a prodrug of butyric acid and formaldehyde, as a single agent and in combination with doxorubicin in human carcinoma MCF-7 and the multidrug resistant MCF-7 Dx cell lines. Methods The anti-cancer activity of AN-7 as a single agent or in combination with doxorubicin was measured by the Hoechst cell viability and colony forming assays as well as by FACS analyses of cells stained with propidium iodide and annexin V-FITC. Modulations of protein expression and acetylation were measured by Western blot analyses. The number of doxorubicin–DNA adducts formed was evaluated using ¹⁴C-labeled doxorubicin. Results The AN-7 and homologous prodrugs exhibited similar growth inhibition effects against drug resistant and sensitive cells, and elicited their anticancer effect partially by inhibition of HDAC. The AN-7 transiently augmented histone acetylation and increase of p21 expression. Synergy between AN-7 and doxorubicin was demonstrated in the sensitive and the resistant cell lines by viability and colony formation assays and was further confirmed by FACS analysis showing an increase in cell mortality. The number of doxorubicin–DNA adducts in total genomic DNA isolated from cells treated with ¹⁴C-labeled doxorubicin and AN-7 increased substantially compared to treatment with doxorubicin only. Treatment with AN-7 or doxorubicin increased p53 acetylation that was further potentiated by their combination. Conclusion The AN-7 combined with doxorubicin overcame drug resistance; at least in part by the intracellularly releasable formaldehyde that augmented formation of doxorubicin–DNA adducts and butyric acid that induced histone and p53 acetylation. Since the use of doxorubicin is limited by toxicity, the combination could offer an effective treatment modality with lower toxicity for breast cancer.This work is supported by a grant 542/00-3 from Israel Science Foundation (A.R. and A.N.); a project grant from the Israel Cancer Research Fund, Israel Cancer Association; The Marcus Center for Pharmaceutical and Medicinal Chemistry at Bar Ilan University (A.N.), Australian Research Council (S.M.C. and D.R.P.). This work was performed by D. Engel as part of the requirements for Ph.D. degree in Bar Ilan University     

Sequential generations of hematopoietic colonies derived from single nonlineage-committed CD34+CD38- progenitor cells.

Multiparameter flow cytometry was applied on normal human bone marrow (BM) cells to study the lineage commitment of progenitor cells ie, CD34+ cells. Lineage commitment of the CD34+ cells into the erythroid lineage was assessed by the coexpression of high levels of the CD71 antigen, the myeloid lineage by coexpression of the CD33 antigen and the B-lymphoid lineage by the CD10 antigen. Three color immunofluorescence experiments showed that all CD34+ BM cells that expressed the CD71, CD33, and CD10 antigens, concurrently stained brightly with anti-CD38 monoclonal antibodies (MoAbs). In addition, the CD38 antigen was brightly expressed on early T lymphocytes in human thymus, characterized by CD34, CD5, and CD7 expression. Only 1% of the CD34+ cells, 0.01% of nucleated cells in normal BM, did not express the CD38 antigen. The CD34+, CD38- cell population lacked differentiation markers and were homogeneous primitive blast cells by morphology. In contrast the CD34+, CD38 bright cell populations were heterogeneous in morphology and contained myeloblasts and erythroblasts, as well as lymphoblasts. These features are in agreement with properties expected from putative pluripotent hematopoietic stem cells; indeed, the CD34 antigen density decreased concurrently with increasing CD38 antigen density suggesting an upregulation of the CD38 antigen on differentiation of the CD34+ cells. Further evidence for a strong enrichment of early hematopoietic precursors in the CD34+, CD38- cell fraction was obtained from culture experiments in which CD34+ cell fractions with increasing density of the CD38 antigen were sorted singularly and assayed for blast colony formation. On day 14 of incubation, interleukin-3 (IL-3), IL-6, and GM-CSF, G-CSF, and erythropoietin (Epo) were added in each well. Twenty-five percent of the single sorted cells that expressed CD34 but lacked CD38 antigen gave rise to primitive colonies 28 to 34 days after cell sorting. The ability to form primitive colonies decreased rapidly with increasing density of the CD38 antigen. During 120 days of culture, up to five sequential generations of colonies were obtained after replating of the first-generation primitive colonies. This study provides direct evidence for the existence of a single class of progenitors with extensive proliferative capacity in human BM and provides an experimental approach for their purification, manipulation, and further characterization.     

Tissue-engineered cells producing complex recombinant proteins inhibit ovarian cancer in vivo

Techniques of tissue engineering and cell and molecular biology were used to create a biodegradable scaffold for transfected cells to produce complex proteins. Mullerian Inhibiting Substance (MIS) causes regression of Mullerian ducts in the mammalian embryo. MIS also causes regression in vitro of ovarian tumor cell lines and primary cells from ovarian carcinomas, which derive from Mullerian structures. In a strategy to circumvent the complicated purification protocols for MIS, Chinese hamster ovary cells transfected with the human MIS gene were seeded onto biodegradable polymers of polyglycolic acid fibers and secretion of MIS confirmed. The polymer-cell graft was implanted into the right ovarian pedicle of severe combined immunodeficient mice. Serum MIS in the mice rose to supraphysiologic levels over time. One week after implantation of the polymer-cell graft, IGROV-1 human tumors were implanted under the renal capsule of the left kidney. Growth of the IGROV-1 tumors was significantly inhibited in the animals with a polymer-cell graft of MIS-producing cells, compared with controls. This novel MIS delivery system could have broader applications for other inhibitory agents not amenable to efficient purification and provides in vivo evidence for a role of MIS in the treatment of ovarian cancer.