T-lymphoblastic Leukemia Cell Line Research Articles

Abstract 5865: Characterization and resistance mechanisms of PNP inhibitor forodesin-resistant cell lines

Abstract Background: The enzyme purine nucleoside phosphorylase (PNP) is involved in the purine salvage pathway and is present at high levels in lymphoid tissues. Children born with PNP deficiency are known to have significantly reduced T-cell counts but relatively normal B-cell immunity, suggesting PNP as one of the most promising therapeutic targets for T-cell malignancies. Forodesine (For, BCX-1777), a novel PNP inhibitor, was approved in Japan for the treatment of relapsed/refractory PTCL. To understand the cytotoxic effect of For and its mechanism of action, we established a For-resistant (For-R) leukemia cell line and explored the mechanism of resistance. Methods: We established two For-R T-lymphoblastic leukemia cell lines (CCRF-CEM and MOLT4) through repeated escalating exposure to For and 2’-deoxyguanosined(dGuo). Gene expression analysis was performed to identify the mechanisms of resistance. Results: For-R cells showed very high resistance compared to parental cells (IC50 value, CEM/CEM-R 4.2nM/>5x105nM, MOLT4/MOLT4-R 8nM/>5x105nM). When cross-resistance was examined in these For-R cells showed mild resistance to cytarabine. The expression of hENT1, a nucleoside transporter, was examined and found to be upregulated in both CEM-R and MOLT4-R cells, while the expression level of deoxycytidine kinase (dCK) was unchanged in both cells. Next, high performance liquid chromatography was used to assess the intracellular dGTP in each parental and its For-R cells. In the parental cells, intracellular dGTP levels increased promptly 4-6 hours after fosteredin administration, whereas in resistant cells, intracellular dGTP levels were higher than before fosteredin administration, and there was little change in dGTP levels after administration. Conclusion: The established For-R cell line acquired a high resistance to For and showed high intracellular dGTP levels. Imbalance in intracellular GTP levels may be involved in the induction of cell death by For. IC50 value of each cell lines Citation Format: Naoko Hosono, Kana Oiwa, Toshiki Tasaki, Rie Nishi, Luigi Scott, Owen A. O’Connor, Takahiro Yamauchi. Characterization and resistance mechanisms of PNP inhibitor forodesin-resistant cell lines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5865.

Clinical Development of Senza5TM CART5: a Novel Dual Population CD5 CRISPR-Cas9 Knocked out Anti-CD5 Chimeric Antigen Receptor T Cell Product for Relapsed and Refractory CD5+ Nodal T-Cell Lymphomas

Introduction: Chimeric antigen receptor T-cell (CART) immunotherapy is FDA-approved for B-cell lymphoblastic leukemia, B-cell non-Hodgkin lymphomas, and multiple myeloma. However, CART immunotherapy for T-cell non-Hodgkin lymphomas (T-NHL) is lagging, with only limited clinical results. T-NHL have a poor prognosis and there is an unmet need for effective and long-lasting treatments. We previously presented preliminary preclinical results of anti-CD5 CAR T cells (CART5) that had CD5 knocked out (KO) (Blood (2020) 136 (Supplement 1): 51-52.). CD5 KO not only prevented CART fratricide but also dramatically enhanced CART function. Critical challenges to developing CART cells for T-NHL are CART fratricide and normal T-cell toxicity. In this study, we addressed these challenges by improving manufacturing and including a dual-population technology to mitigate toxicity. We present the development of Senza5TM CART5 an autologous good-manufacturing practice (GMP)-grade product (Fig.1) that will be tested in a phase I clinical trial for relapsed and refractory CD5+ nodal T-cell lymphomas. Methods and Results: We first identified a single guide RNA (sgRNA) that deletes CD5 in T cells with >90% KO efficiency by flow cytometry and ICE analysis. We then assessed the specificity of the KO by performing iGUIDE sequencing. We confirmed high on-target CD5 cleavage with minimal off-targets (CALCP, C20orf85, INPP4B, XPO7, and SLC10A7). These genes have little to no expression in naïve CD4+ and CD8+ T cells by RNA-seq (DICE). Targeted functional assays are ongoing. For the CAR construct, we selected a lead CAR5 among six 4-1BB-constructs based on its superior anti-tumor function in NOD-SCID IL2Rgnull (NSG) mice engrafted with a Jurkat T-lymphoblastic leukemia cell line. Furthermore, to confirm the specificity of the CAR5 for CD5, we screened CAR5 T cells for interactions with HEK293 cells expressing 5,828 human plasma membrane proteins or cell-surface tethered secreted proteins and 398 human heterodimers (Retrogenix assay). The lead CAR5 did not bind to any targets besides CD5. For an optimized GMP-grade product, we modified our manufacturing protocol, shortening it from 10 to 5 days. Moreover, KO efficiency and safety were optimized to reduce off-target activity without loss of efficiency. We also optimized the activation strategy to decrease cell loss. Functional studies were performed to demonstrate the comparability of these methods. With these improvements, we were able to achieve >90% CD5 KO with >30% CAR transduction, thereby allowing the generation of two main populations: one of CD5KO CART5 cells and the other of CD5KO normal untransduced T cells. CD5KO CART5 are expected to target CD5+ T-NHL cells but could also lead to normal T-cell toxicity. This toxicity will be mitigated by the CD5KO normal T cells that will have a survival advantage after infusion (Fig.1) and have been demonstrated to maintain reactivity against opportunistic pathogens such as CMV and EBV. To evaluate Senza5TMCART5 safety, we performed cytokine-independent CART proliferation and long- and short-term xenograft models. Senza5TM CART5 cells did not grow aberrantly without growth/survival-associated cytokines (IL2/7/15). We then used NSG mice to exclude uncontrolled Senza5TM CART5 growth and observed enhanced expansion and proliferation of Senza5TM CART5 with a xenogeneic GVHD rate similar to that of control mice with similar wild-type CART5 expansion. Since the CAR5 does not cross-react with murine CD5, we tested non-specific toxicity in tissues using an NSG xenograft model of Jurkat. On Day 10 post-CAR T injections, animals were euthanized, and a complete necropsy was performed on all animals. Senza5TM CART5 demonstrated tumor clearance with no detection of treatment-related lesions. Mice treated with untransduced T cells or CART19 demonstrated significant overall and organ-specific weight loss compared to Senza5TM CART5. Blood analyses determined no differences in their clinical chemistry profile or complete blood counts. Conclusion: In this study, we developed a novel dual-population, full-scale GMP-ready CD5 KO anti-CD5 CART product for T-cell lymphomas characterized by enhanced anti-tumor effect and a strategy to potentially mitigate toxicity. Autologous Senza5TM CART5 will be tested for CD5+ nodal T-cell lymphomas in a phase I clinical trial. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

C9Mab-1: An Anti-Mouse CCR9 Monoclonal Antibody for Immunocytochemistry.

C-C motif chemokine receptor 9 (CCR9) is a G protein-coupled receptor, which is highly expressed in T-lymphocytes and different cancer cells. CCR9 aggravates immune diseases and cancer progression and is considered a biomarker and a therapeutic target of diseases. The development of specific monoclonal antibody (mAbs) for human CCR9 (hCCR9) is required to diagnose and treat immune diseases and cancers. Previously, we established the cell-based immunization and screening (CBIS) method, which does not need purified target proteins. Anti-hCCR9 mAb (clone C9Mab-1; mouse IgG1, kappa) was also developed using the CBIS method. C9Mab-1 is usable for flow cytometry against exogenously and endogenously expressing hCCR9. This study showed that C9Mab-1 and its recombinant antibody (recC9Mab-1) specifically detected exogenous hCCR9 stably overexpressed in Chinese hamster ovary (CHO)-K1 cells and endogenous hCCR9 expressed in a human T-lymphoblastic leukemia cell line MOLT-4 cells through immunocytochemistry. This study provides a new application of C9Mab-1 and recC9Mab-1 in immunocytochemistry.

Characterization of newly established Pralatrexate-resistant cell lines and the mechanisms of resistance

BackgroundPralatrexate (PDX) is a novel antifolate approved for the treatment of patients with relapsed/refractory peripheral T-cell lymphoma, but some patients exhibit intrinsic resistance or develop acquired resistance. Here, we evaluated the mechanisms underlying acquired resistance to PDX and explored potential therapeutic strategies to overcome PDX resistance.MethodsTo investigate PDX resistance, we established two PDX-resistant T-lymphoblastic leukemia cell lines (CEM and MOLT4) through continuous exposure to increasing doses of PDX. The resistance mechanisms were evaluated by measuring PDX uptake, apoptosis induction and folate metabolism-related protein expression. We also applied gene expression analysis and methylation profiling to identify the mechanisms of resistance. We then explored rational drug combinations using a spheroid (3D)-culture assay.ResultsCompared with their parental cells, PDX-resistant cells exhibited a 30-fold increase in half-maximal inhibitory concentration values. Induction of apoptosis by PDX was significantly decreased in both PDX-resistant cell lines. Intracellular uptake of [14C]-PDX decreased in PDX-resistant CEM cells but not in PDX-resistant MOLT4 cells. There was no significant change in expression of dihydrofolate reductase (DHFR) or folylpolyglutamate synthetase (FPGS). Gene expression array analysis revealed that DNA-methyltransferase 3β (DNMT3B) expression was significantly elevated in both cell lines. Gene set enrichment analysis revealed that adipogenesis and mTORC1 signaling pathways were commonly upregulated in both resistant cell lines. Moreover, CpG island hypermethylation was observed in both PDX resistant cells lines. In the 3D-culture assay, decitabine (DAC) plus PDX showed synergistic effects in PDX-resistant cell lines compared with parental lines.ConclusionsThe resistance mechanisms of PDX were associated with reduced cellular uptake of PDX and/or overexpression of DNMT3B. Epigenetic alterations were also considered to play a role in the resistance mechanism. The combination of DAC and PDX exhibited synergistic activity, and thus, this approach might improve the clinical efficacy of PDX.

Control of oxidative stress in Jurkat cells as a model of leukemia treatment

This paper describes proof-of-concept for antileukemia treatment based on the reactive oxygen species (ROS) induction supplemented with magnetic nanoparticles in the presence of moderate-intensity magnetic fields. The T-lymphoblastic leukemia cell line (Jurkat) was chosen as an in vitro model of acute lymphoblastic leukemia. The elevated ROS levels were generated by iron oxide magnetic nanoparticles. We found an enhanced cytotoxic effect of magnetic nanoparticles in the presence of a magnetic field on cancerous Jurkat cell line due to induced oxidative stress after cultivation in magnetic fields with an average strength of 0.26–0.36 T and the field spatial gradient up to 100 T/m. At the same conditions of nanoparticles intake, the viability of human peripheral blood mononuclear cells (model of healthy cells) was not inhibited. Thus, we demonstrated the feasibility of antileukemia treatment by magnetic nanoparticles controlled by a magnetic field.

2-Deoxyglycoside Conjugates of Lupane Triterpenoids with High Cytotoxic Activity-Synthesis, Activity, and Pharmacokinetic Profile.

A set of 41 glycosidic conjugates of pentacyclic triterpenes was synthesized in order to improve the solubility of highly cytotoxic parent compounds. Their in vitro cytotoxic activity was evaluated in 25 cancer cell lines and 2 noncancer fibroblasts. Fifteen compounds had high cytotoxicity on the T-lymphoblastic leukemia cell line CCRF-CEM and 6 of them were active in multiple cell lines of various histogenic origin and not toxic in fibroblasts. Compound 11a had IC50 of 0.64 μM in CCRF-CEM cells, 0.60 μM in K-562 cells, and 0.37 μM in PC-3 cells; compound 12a had IC50 of 0.64 μM in CCRF-CEM cells and 0.71 μM in SW620 cells; compound 17b had IC50 of 0.86 μM in HCT116 cells and 0.92 μM in PC-3 cells. Compounds 11b and 12b were slightly less active than the previously mentioned derivatives; however, their solubility was significantly better, and therefore they were selected for the in vivo evaluation of the pharmacokinetic profile in mice. In both compounds, the maximum concentration in plasma was achieved very rapidly-the highest level in plasma was found 1 h after administration (22.2, respectively, 6.4 μM). For compound 12b, the resorption was followed with fast elimination, and 12 h after administration, the compound was not detected in plasma. In contrast, compound 11b was eliminated more slowly; it was still present in plasma after 12 h, but its concentration dropped below the detection limit after 24 h. The elimination half-time determined for compound 11b was 2.4 h and for compound 12b just about 1.4 h. These values are reasonable for further drug development.

Pterostilbene increases Fas expression in T-lymphoblastic leukemia cell lines.

Treatment of acute lymphoblastic leukemia (ALL) has been promising in last decades, but side effects still persist and searching for the least toxic agents continue. Pterostilbene (PTE) is a natural compound with several anti-cancer and anti-oxidant properties. Fas, as a member of death inducing family of tumor necrosis factor (TNF) receptors with an intracellular death domain, can initiate the extrinsic apoptosis signaling pathway. Here after the half maximal inhibitory concentration (IC50) determination in cell lines, we searched for PTE effects on Fas, both in mRNA and surface levels in two ALL cell lines, Jurkat and Molt-4. After harvesting cells in optimum situations, MTS assay was used to determine IC50 concentrations. Real-time polymerase chain reaction (RT-PCR) and flow cytometry were performed for Fas mRNA and surface expression variations after exposure to PTE. The findings showed that PTE decreases cell viability with different extent in two ALL cell lines. In addition to inducing apoptosis, it can increase Fas in both gene and cell surface expression in the same concentrations. Pterostilbene as a natural anti-cancer agent can increase Fas expression both in mRNA and surface levels that results in apoptosis signal transduction improvement which sensitizes cells to apoptosis by immune effector cells. As a result, abnormal cells removal would be more efficiently with the minimum side effects on normal cells.

Pralatrexate-Resistant Cell Lines Show Intact Internalization Via RFC1 but Collateral Sensitivity to Nucleoside Analogs

BackgroundPralatrexate (PDX) is a novel dihydrofolate reductase (DHFR) inhibitor which is designed to have a high affinity for reduced folate carrier (RFC1), DHFR, and folylpolyglutamate synthetase (FPGS), resulting in greater internalization and accumulation in tumor cells than methotrexate. PDX has been approved by the U.S. FDA and many international health care ministries for the treatment of relapsed and refractory peripheral T-cell lymphoma (R/R PTCL). A recent case match control analysis has confirmed a survival advantage for patients enrolled on PROPEL compared to a well-matched population of patients receiving standard of care. Recently, PDX has demonstrated compelling activity in combination with romidepsin in R/R PTCL patients, where is role is likely to expand. In this study we explored the mechanisms of resistance to PDX and approaches to overcome them, including combination strategies using PDX-resistant (PDX-R) leukemic cell lines.MethodsT-lymphoblastic leukemia cell lines, CCRF-CEM (CEM), MOLT-4 (MOLT4), and MOLT-3 (MOLT3), were used. To establish PDX-R cell lines, the cells were initially incubated with low-concentrations of PDX, and then concentrations of the drug were gradually increased. After acquisition of PDX-R, the single-cell separation was performed by a limiting dilution. Microarray analysis was performed in CEM, MOLT4 and each PDX-R counterpart.ResultsThe 50% inhibitory concentration (IC50) values of PDX against CEM, MOLT4 and MOLT3 were 0.6 nM, 2.4 nM and 1.4 nM, respectively, while the PDX-R cell lines exhibited IC50 values of 20 nM, 80 nM and 40 nM, respectively. After 48-hour treatment with PDX, annexin-V positivity was significantly reduced in PDX-R cells (in CEM, MOLT4 and MOLT3 was 78.7%, 77.7%, 97.4% vs 4.4%, 5.9%, 6.6%, respectively). The expression of RFC1 was not altered in PDX-R cells, nor was any acquired mutation of RFC1 detected in cell lines. Intracellular uptake of [14C]-PDX was modestly decreased in CEM/PDX-R, while there was no difference of it in MOLT4/PDX-R, suggesting that the resistance mechanism was not due to the inability to internalize drug. Gene expression array revealed that the expression of DNA-methyltransferase 3 beta (DNMT3b) was significantly elevated in both CEM/PDX-R (12.8 times) and MOLT4/PDX-R (2.8 times) cells, whereas there was no significant difference in that of DHFR, FPGS and thymidylate synthase. When we explored the profile of cross-resistances in PDX-R cells, it was surprising that PDX-R cells were more sensitive to nucleoside analogs, including cytarabine (AraC) and forodesine (FDS). After 72 hours of FDS-treatment, induction of apoptosis was seen in both parental and PDX-R cells, suggesting that the mechanisms of PDX-R is not cross resistant. In addition, there was no cross-resistance to bortezomib or panobinostat in PDX-R cell lines.DiscussionWe established PDX-R cell lines which were around 30-fold resistant to PDX compared to their parental counterparts. The characteristics of PDX-R cells are as follows: (i) intact internalization of PDX, (ii) intact apoptotic mechanisms, (iii) no cross-resistance to BOR or LBH, (iv) collateral sensitive to nucleoside analogs, such as AraC and FDS. These data suggest that the mechanism of acquired resistance to PDX may be associate with not only cellular uptake of PDX, but also DNA methylation and/or nucleic-acid metabolism. These findings may be underscored by the fact that nucleoside analogs exhibited greater potency in the PDX-R cells in vitro. Next steps are focused on exploring the methylation status of these genes involved in PDX activity, and their merits of combining with hypomethylating agents.ConclusionsWe established PDX-R T-lymphoblastic leukemia cell lines which show collateral sensitivity to nucleoside analogs. The mechanisms of PDX resistance is not always cellular uptake of PDX, epigenetic alteration might contribute to the development PDX-resistance. Nevertheless, the new T-lymphoma-targeting agent, FDS can be effective in this setting. Our results may encourage further investigation to overcome resistance of PDX for patients with R/R PTCL. DisclosuresO'Connor:ADC Therapeutics: Research Funding; Seattle Genetics: Research Funding; Celgene: Research Funding.

Modulation of multidrug resistant in cancer cells by EGCG, tannic acid and curcumin

Background: Cancer is one of the most common life-threatening diseases worldwide; many patients develop multidrug resistance after treatment with anticancer drugs. The main mechanism leading to multidrug resistance is the overexpression of ABC transporters in cancer cells. Chemosensitizers are needed to inhibit the activity of ABC transporters, resulting in higer intracellular concentration of anticancer drugs. Some secondary metabolites have been reported to be chemosensitizers by inhibiting ABC transporters. Epigallocatechin gallate (EGCG), tannic acid, and curcumin were employed in this study. Different assays were used to detect whether they have the ability to inhibit P-gp activity and overcome multidrug resistance in cancer cells overexpressing P-gp. Hypothesis/Purpose: CEM/ADR 5000 and Caco-2 cell lines, which overexpress P-gp, are multidrug resistant cell lines. We first detected whether the combination of polyphenols (EGCG, tannic acid, curcumin) and doxorubicin, an anticancer drug, is synergistic or not. To further understand the potential mechanism, EGCG, tannic acid, and curcumin were tested to check whether they have the ability to inhibit P-gp activity. When P-gp activity is inhibited, the intracellular concentration of doxorubicin is higher, resulting in enhanced cytotoxicity of doxorubicin. Study design: The P-gp overexpressing human colon cancer cell line Caco-2 and human T-lymphoblastic leukemia cell line CEM/ADR 5000 were used in this study. Two-drug combinations (doxorubicin + polyphenol) and three-drug combinations (doxorubicin + polyphenol + digitonin) were tested to examine potential synergism. The potential mechanism leading to synergism would be the inhibition of P-gp activity. A Rhodamine 123 assay and Calcein-AM assay in Caco-2 and CEM/ADR 5000, respectively, were used to detect P-gp inhibition by EGCG, curcumin, and tannic acid. Methods: MTT assay was used to determine the cytotoxicity of doxorubicin, polyphenols and digitonin alone, and then their combinations. Furthermore, Rhodamine 123 and Calcein-AM were used to detect the effects of polyphenols on the activity of P-gp. Results: The results demonstrated that a combination of non-toxic concentrations of each polyphenol with doxorubicin synergistically sensitized Caco-2 and CEM/ADR 5000 cells. Furthermore, three-drug combinations (doxorubicin + polyphenol + digitonin) were much more effective. In addition, the activity of P-gp in Caco-2 and CEM/ADR 5000 cells was measured. Consistent with the combination results, tannic acid and curcumin decreased the activity of P-gp both in Caco-2 and CEM/ADR 5000. EGCG, which weakly affected the activity of P-gp in CEM/ADR 5000, only had an effect on P-gp under higher concentration in Caco-2 cells. Conclusion: Our results show that EGCG, curcumin, and tannic acid, when combined with doxorubicin, can exert synergism, mediated by a reduced activity of P-gp. This study suggests that polyphenols, by modulating the activity of P-gp, may be used as chemosensitisers.

Triterpenic azines, a new class of compounds with selective cytotoxicity to leukemia cells CCRF-CEM.

From betulinic acid (1a), we synthesized 30-oxobetulinic acid (2a) that is highly cytotoxic against many cancer cell lines; however, its generic toxicity is the main obstacle in further development as cytostatic. Methodology & results: From 2a, we prepared a new class of compounds - nonsymmetrical azines and tested their in vitro cytotoxicity. All new azines with a free 28-COOH group (4a-4e) were highly and selectively cytotoxic against the T-lymphoblastic leukemia cell line CCRF-CEM and exhibited dose-dependent inhibition of RNA and DNA synthesis and other cell-cycle alterations, including the M-phase block. The potential use of azines (4a-4e) in drug development focused on hematological cancers is significantly higher than that of previously studied acids 1a and 2a.

BMI1 Inhibitors Down-regulate NOTCH Signaling and Suppress Proliferation of Acute Leukemia Cells.

B cell-specific Moloney murine leukemia virus integration site 1 (BMI1) is up-regulated in several cancers; therefore, we investigated the effects of BMI1 inhibitors on leukemia cells. Four acute myeloid leukemia and two T-lymphoblastic leukemia cell lines were treated with BMI1 inhibitors artemisinin, PRT4165, and PTC-209 and analyzed for cell proliferation and gene expression by microarray and immunoblotting. PTC-209 and PRT4165 suppressed the growth of all cell lines through apoptosis.Artemisinin acted only on Jurkat cells. BMI1 inhibitors and BMI1-specific siRNA down-regulated the expression of NOTCH signaling proteins NOTCH1, HES1, and MYC. All but one cell lines did not have the cyclin-dependent kinase inhibitor 2A (CDKN2A) gene targeted by BMI1, thus the inhibitors acted through CDKN2A-independent pathways. BMI1 inhibition suppressed proliferation of leukemia cells through NOTCH signaling which functions downstream of BMI1, suggesting that BMI1 inhibitors can be candidate targeted drugs against leukemia.

Synthesis and in vitro anticancer activity of 23(23′)E-benzylidenespirostanols derived from steroid sapogenins

Benzylidenespirostanols were prepared by two-step synthesis including BF3·Et2O-catalyzed aldol condensation of several acetylated steroid sapogenins with benzaldehyde followed by saponification. The obtained compounds showed moderate cytotoxicity against three cancer cell lines (T-lymphoblastic leukemia cell line CEM, breast carcinoma cell line MCF7 and cervical carcinoma cell line HeLa) and normal human fibroblasts (BJ). The most active of the five tested substances was 3c (lowest IC50 for MCF7 cells 19.9±0.1µM) without any selectivity towards human cancer and normal cells, respectively.

Repairing effects of interleukin 11 (IL-11) towards high dose methotrexate-induced rat small intestinal mucositis and its impacts on T-lymphoblastic leukemia cell line.

To investigate the efficacy of interleukin 11 (IL-11) towards the high dose methotrexate (HDMTX)-concurrent rat small intestinal mucositis and its impacts on the proliferation of the human T-lymphoblastic leukemia (CEM) cell line. 95 Wistar rats were randomly divided into five groups, the normal control group (A), the methotrexate (MTX) control group (B), the IL-11-pre-treated high-dose group (C), the post-IL-11-treatment high-dose group (D) and the post-IL-11-treatment low-dose group (E). After the intraperitoneal injection of MTX in the groups B-E, the rats were sacrificed at 1, 3, 5 and 7 days. The mortality, morphological and ultrastructural changes of small intestine of each group were observed. The cells were then cultured in vitro, and the MTT method was used to investigate the effects of different concentration of IL-11 on CEM proliferation and also on HDMTX-induced mucositis. IL-11 could reduce the intestinal histopathological score, increase the height of small intestinal villi, promote the proliferation of intestinal lacunar cells and reduce the mortality rate of rats. The IL-11 pre-treatment group exhibited the best efficacies, demonstrating significant difference with the control group (P<0.01). In addition, the proliferation of CEM was not promoted, indicating that IL-11 could not inhibit HDMTX. IL-11 could reduce the severity of HDMTX-induced intestinal mucositis, and improve the survival rate of experimental rats, and could be safely used as the adjuvant treatment of HDMTX in childhood leukemia.

Overexpression of SORCIN is a Prognostic Biomarker for Multidrug-Resistant Pediatric Acute Lymphoblastic Leukemia and Correlates with Upregulated MDR1/P-gp.

Multidrug resistance is one of the major causes of treatment failure in pediatric acute lymphoblastic leukemia (ALL), and SORCIN is an intracellular calcium modulator protein. The current study was designed to investigate the in vitro and in vivo relationships between the expression levels of SORCIN: in tumor cell lines and children with ALL; its possible correlation with MDR1/P-glycoprotein (P-gp), a multidrug resistance-related gene; and response to therapy. Childhood T-lymphoblastic leukemia (CCRF-CEM) cell lines resistant to methotrexate (MTX) were developed. Patient studies were performed by including 30 children with ALL at diagnosis, 3 children with bone marrow relapse, and 15 children with no symptoms of cancer. The mRNA expression profiles of SORCIN and MDR1/P-gp was assessed using quantitative polymerase chain reaction (qPCR). Minimal residual disease (MRD) was measured in the patient population, a year following the initial therapy using qPCR. Cell line data analyses showed a positive correlation between SORCIN mRNA levels and resistance to MTX. The difference between patient and control groups for SORCIN expression levels was not significant. However, patients with a negative response to therapy showed an increase in SORCIN mRNA levels (up to 6.8-fold) compared with those with negative MRD. In addition, the results demonstrated a significant positive correlation between SORCIN and MDR1/P-gp gene expression levels. The current study introduces, for the first time, a possible prognostic value of SORCIN in childhood ALL, which may be correlated with MDR1/P-gp gene expression in these patients.

The Synergistic Repressive Effect of NF-κB and JNK Inhibitor on the Clonogenic Capacity of Jurkat Leukemia Cells

Deregulation of Nuclear Transcription Factor-κB (NF-κB) and Jun N-terminal kinase (JNK) signaling is commonly detected in leukemia, suggesting an important role for these two signaling pathways in the pathogenesis of leukemia. In this study, using Jurkat cells, an acute T-lymphoblastic leukemia (T-ALL) cell line, we evaluated the effects of an NF-κB inhibitor and a JNK inhibitor individually and in combination on the proliferation, survival and clonogenic capacity of leukemic cells. We found that leukemic stem/progenitor cells (LSPCs) were more sensitive to NF-κB inhibitor treatment than were healthy hematopoietic stem/progenitor cells (HSPCs), as shown by a reduction in the clonogenic capacity of the former. Inactivation of NF-κB leads to the activation of JNK signaling in both leukemic cells and healthy HSPCs. Interestingly, JNK inhibitor treatment enhanced the repressive effects of NF-κB inhibitor on LSPCs but prevented such repression in HSPCs. Our data suggest that JNK signaling stimulates proliferation/survival in LSPCs but is a death signal in HSPCs. The combination of NF-κB inhibitor and JNK inhibitor might provide a better treatment for T-ALL leukemia by synergistically killing LSPCs while simultaneously preventing the death of normal HPCs.

Reduced drug incorporation into DNA and antiapoptosis as the crucial mechanisms of resistance in a novel nelarabine-resistant cell line.

BackgroundNine-beta-D-arabinofuranosylguanine (ara-G), an active metabolite of nelarabine, enters leukemic cells through human Equilibrative Nucleoside Transporter 1, and is then phosphorylated to an intracellular active metabolite ara-G triphosphate (ara-GTP) by both cytosolic deoxycytidine kinase and mitochondrial deoxyguanosine kinase. Ara-GTP is subsequently incorporated into DNA, thereby inhibiting DNA synthesis.MethodsIn the present study, we developed a novel ara-G-resistant variant (CEM/ara-G) of human T-lymphoblastic leukemia cell line CCRF-CEM, and elucidated its mechanism of ara-G resistance. The cytotoxicity was measured by using the growth inhibition assay and the induction of apoptosis. Intracellular triphosphate concentrations were quantitated by using HPLC. DNA synthesis was evaluated by the incorporation of tritiated thymidine into DNA. Protein expression levels were determined by using Western blotting.ResultsCEM/ara-G cells were 70-fold more ara-G-resistant than were CEM cells. CEM/ara-G cells were also refractory to ara-G-mediated apoptosis. The transcript level of human Equilibrative Nucleoside Transporter 1 was lowered, and the protein levels of deoxycytidine kinase and deoxyguanosine kinase were decreased in CEM/ara-G cells. The subsequent production of intracellular ara-GTP (21.3 pmol/107 cells) was one-fourth that of CEM cells (83.9 pmol/107 cells) after incubation for 6 h with 10 μM ara-G. Upon ara-G treatment, ara-G incorporation into nuclear and mitochondrial DNA resulted in the inhibition of DNA synthesis of both fractions in CEM cells. However, DNA synthesis was not inhibited in CEM/ara-G cells due to reduced ara-G incorporation into DNA. Mitochondrial DNA-depleted CEM cells, which were generated by treating CEM cells with ethidium bromide, were as sensitive to ara-G as CEM cells. Anti-apoptotic Bcl-xL was increased and pro-apoptotic Bax and Bad were reduced in CEM/ara-G cells.ConclusionsAn ara-G-resistant CEM variant was successfully established. The mechanisms of resistance included reduced drug incorporation into nuclear DNA and antiapoptosis.

Amides derived from heteroaromatic amines and selected steryl hemiesters

The current interest of the team has been focused on investigation of novel amides with potential cytotoxicity. The presented series of compounds was synthesized from selected steryl hemiesters and heteroaromatic amines. The synthetic protocol was designed in a simple and economic way, and divided into several general methodologies applicable to the compounds synthesized. The cytotoxicity was tested on cells derived from human T-lymphoblastic leukemia, breast adenocarcinoma and cervical cancer, and compared with tests on normal human fibroblasts. Most of the lanosterol-based compounds (3–5 and 7–10) showed medium to good cytotoxicity, while only two derivatives of cholesterol (18 and 19) showed medium cytotoxicity on human T-lymphoblastic leukemia cell line. The compounds 8 and 9 displayed the reasonable cytotoxicity among this series of amides, tested on the cell lines of T-lymphoblastic leukemia [14.5±0.4μM (8) and 18.5±3.9μM (9)], breast adenocarcinoma [19.5±2.1μM (8) and 23.1±4.0μM (9)] and cervical cancer [24.8±5.3μM (8) and 29.1±4.7μM (9)]. Only the compound 8 was adequately less active on normal human fibroblasts (40.4±11.1μM).

New propanoyloxy derivatives of 5β-cholan-24-oic acid as drug absorption modifiers

A series of final twelve propanoyloxy derivatives of 5β-cholan-24-oic acid (O-propanoyl derivatives of cholic acid) as potential drug absorption modifiers (skin penetration enhancers, intestinal absorption promoters) was generated by multistep synthesis. Structure confirmation of all generated compounds was accomplished by 1H NMR, 13C NMR, IR and MS spectroscopy methods. All the prepared compounds were analyzed using RP-TLC, and their lipophilicity (RM) was determined. The hydrophobicity (log P), solubility (log S), polar surface area (PSA) and molar volume (MV) of the studied compounds were also calculated. All the target compounds were tested for their in vitro transdermal penetration effect and as potential intestinal absorption enhancers. The cytotoxicity of all the evaluated compounds was evaluated against normal human skin fibroblast cells. Their anti-proliferative activity was also assessed against human cancer cell lines: T-lymphoblastic leukemia cell line and breast adenocarcinoma cell line. One compound showed selective cytotoxicity against human skin fibroblast cells and another compound possessed the highest cytotoxicity against all the tested cell lines. Only one compound expressed anti-proliferative effect on leukemia cancer cells without affecting the growth of normal cells, which should be promising in potential development of new drugs. Most of the target compounds showed minimal anti-proliferative activity (IC50>37μM), indicating they would have moderate cytotoxicity when administered as chemical absorption modifiers. The relationships between the lipophilicity/polarity and the chemical structure of the studied compounds as well as the relationships between their chemical structure and enhancement effect are discussed in this article.

Investigation of new acyloxy derivatives of cholic acid and their esters as drug absorption modifiers

Skin penetration enhancers are used in the formulation of transdermal delivery systems for drugs that are otherwise not sufficiently skin-permeable. Intestinal absorption promoters/enhancers are used as excipients in oral formulations of poorly oral-bioavailable drugs. Series of fourteen acyloxy derivatives of 5β-cholic acid as potential drug absorption modifiers was generated by multistep synthesis. The synthesis of all newly prepared compounds is presented here. Structure confirmation of all generated compounds was accomplished by 1H NMR, 13C NMR, IR and MS spectroscopy methods. All the prepared compounds were analyzed using RP-TLC, and their lipophilicity ( R M) was determined. The hydrophobicity (log P) and solubility (log S) of the studied compounds were also calculated using two commercially available programs. All the target compounds were tested for their in vitro transdermal penetration activity and as potential intestinal absorption enhancers. The anti-proliferative activity of all the final compounds was also assessed against the human cancer cell lines: T-lymphoblastic leukemia cell line and the breast adenocarcinoma cell line. Their cytotoxicity was also evaluated against the normal human skin fibroblast cells. Two compounds showed anti-proliferative effect on cancer cells without affecting the growth of normal cells, which should be promising in potential development of new drugs. Most of the target compounds showed minimal anti-proliferative activity (IC 50 > 37 μM), indicating they would have low cytotoxicity when administered as chemical absorption modifiers. The relationships between the lipophilicity and the chemical structure of the studied compounds as well as the relationships between their chemical structure and enhancement effects are discussed in this article.

Distinct modulation of telomere length in two T-lymphoblastic leukemia cell lines by cytotoxic nucleoside phosphonates PMEG and PMEDAP

We have previously shown that PMEG diphosphate (PMEGpp) and PMEDAP diphosphate (PMEDAPpp) inhibit the enzymatic activity of human telomerase in a cell-free assay. Here, we investigated the ability of PMEG and PMEDAP to induce telomere shortening and telomerase inhibition at both transcriptional and activity level in T-lymphoblastic leukemia cells CCRF-CEM and MOLT-4. At defined time points (3 days and 9 weeks), the telomerase activity and relative levels of hTERT and c-myc mRNA were determined using real-time RT-PCR. Telomere length was measured by the flow-FISH method. Both PMEDAP and PMEG induced telomere shortening in CCRF-CEM cells after 9 weeks of exposure by 50% and 20%, respectively, without major impairment of telomerase activity. The effect of the tested compounds on telomere length in MOLT-4 cells was the opposite, with telomere elongation by 50% and 40% after 9-week treatment with PMEDAP and PMEG, respectively. At this time point, telomerase activity in MOLT-4 cells appeared to be slightly higher than that of CCRF-CEM cells, nevertheless no correlation between telomerase activity and telomere length was found. Both compounds down-regulated the expression of hTERT and c-myc mRNA in CCRF-CEM and MOLT-4 cells at 72 h in a concentration-dependent manner while prolonged exposure to PMEG or PMEDAP for 9 weeks had weaker effects. In conclusion, PMEDAP and PMEG are able to modulate telomere length in leukemic cells and this effect is cell-type specific. It is neither due to direct telomerase inhibition nor impairment of hTERT expression and it is likely to be telomerase-independent.