Survivin and Leukemia

FLI1 promotes protein translation via the transcriptional regulation of MKNK1 expression

The disruption of protein translation machinery is a common feature of cancer initiation and progression, and drugs that target protein translation offer new avenues for therapy. The translation initiation factor, eukaryotic initiation factor 4E (eIF4E), is induced in a number of cancer cell lines and is one such candidate for therapeutic intervention. Friend leukemia integration 1 (FLI1) is a potent oncogenic transcription factor that promotes various types of cancer by promoting several hallmarks of cancer progression. FLI1 has recently been implicated in protein translation through yet unknown mechanisms. This study identified a positive association between FLI1 expression and mitogen-activated protein kinase (MAPK)-interacting serine/threonine kinase1 (MKNK1), the immediate upstream regulator of the eIF4E initiation factor. The short hairpin RNA (shRNA)-mediated silencing or overexpression of FLI1 in leukemic cell lines downregulated or upregulated MKNK1 expression, respectively. Promoter analysis identified a potent FLI1 binding site in the regulatory region of the MKNK1 promoter. In transient transfection experiments, FLI1 increased MKNK1 promoter activity, which was blocked by mutating the FLI1 binding site. FLI1 specifically affected the expression of MKNK1, but not that of MKNK2. The siRNA-mediated downregulation of MKNK1 downregulated the expression of survivin (BIRC5) and significantly suppressed cell proliferation in culture. FLI1 inhibitory compounds were shown to downregulate this oncogene through the suppression of MAPK/extracellular-regulated kinase (ERK) signaling and the subsequent activation of miR-145, leading to a lower MKNK1 expression and the suppression of leukemic growth. These results uncover a critical role for FLI1 in the control of protein translation and the importance of targeting its function and downstream mediators, such as MKNK1, for cancer therapy.

Therapeutic Potency of Nanoformulations of siRNAs and shRNAs in Animal Models of Cancers

RNA Interference (RNAi) has brought revolutionary transformations in cancer management in the past two decades. RNAi-based therapeutics including siRNA and shRNA have immense scope to silence the expression of mutant cancer genes specifically in a therapeutic context. Although tremendous progress has been made to establish catalytic RNA as a new class of biologics for cancer management, a lot of extracellular and intracellular barriers still pose a long-lasting challenge on the way to clinical approval. A series of chemically suitable, safe and effective viral and non-viral carriers have emerged to overcome physiological barriers and ensure targeted delivery of RNAi. The newly invented carriers, delivery techniques and gene editing technology made current treatment protocols stronger to fight cancer. This review has provided a platform about the chronicle of siRNA development and challenges of RNAi therapeutics for laboratory to bedside translation focusing on recent advancement in siRNA delivery vehicles with their limitations. Furthermore, an overview of several animal model studies of siRNA- or shRNA-based cancer gene therapy over the past 15 years has been presented, highlighting the roles of genes in multiple cancers, pharmacokinetic parameters and critical evaluation. The review concludes with a future direction for the development of catalytic RNA vehicles and design strategies to make RNAi-based cancer gene therapy more promising to surmount cancer gene delivery challenges.

Artificial human antigen-presenting cells are superior to dendritic cells at inducing cytotoxic T-cell responses

Peptide recognition through the MHC class I molecule by cytotoxic T lymphocytes (CTLs) leads to the killing of cancer cells. A potential challenge for T-cell immunotherapy is that dendritic cells (DCs) are exposed to the MHC class I-peptide complex for an insufficient amount of time. To improve tumour antigen presentation to T cells and thereby initiate a more effective T-cell response, we generated artificial antigen-presenting cells (aAPCs) by incubating human immature DCs (imDCs) with poly(lactic-co-glycolic) acid nanoparticles (PLGA-NPs) encapsulating tumour antigenic peptides, followed by maturation with lipopolysaccharide. Tumour antigen-specific CTLs were then induced using either peptide-loaded mature DCs (mDCs) or aAPCs, and their activities were analysed using both ELISpot and cytotoxicity assays. We found that the aAPCs induced significantly stronger tumour antigen-specific CTL responses than the controls, which included both mDCs and aAPCs loaded with empty nanoparticles. Moreover, frozen CTLs that were generated by exposure to aAPCs retained the capability to eradicate HLA-A2-positive tumour antigen-bearing cancer cells. These results indicated that aAPCs are superior to DCs when inducing the CTL response because the former are capable of continuously presenting tumour antigens to T cells in a sustained manner. The development of aAPCs with PLGA-NPs encapsulating tumour antigenic peptides is a promising approach for the generation of effective CTL responses in vitro and warrants further assessments in clinical trials.

IFNγ enhances cytotoxic efficiency of the cytotoxic T lymphocytes against human glioma cells

Cytotoxic T lymphocytes (CTLs) are a key player in cancer immunotherapies, and MHC class I molecules on the cell surface are crucial for cellular recognition. However, the aberrant expression of MHC class I molecules is frequently found in various malignancies. IFNγ has dual functions in cancer progression, and its effect on tumor immunity is controversial. To investigate whether IFNγ can enhance cytotoxic efficiency of the tumor antigen-specific CTLs, we generated the CTLs using modified human dendritic cells as antigen presenting cells, then studied the activities of CTLs on human leukocyte antigen (HLA)-A2 positive glioma cells treated with, or without IFNγ. The results from both ELISpot and cytotoxicity assays demonstrated that the CTLs recognized and eliminated the HLA-A2 positive glioma cells treated with IFNγ more effectively when compared to the glioma cells deprived of IFNγ treatment. In addition, in vitro experiments showed that the levels of MHC class I molecules were upregulated in all of the HLA-A2 positive glioma cells. Using the publicly accessed TCGA data of low-grade glioma, we found significantly positive associations between IFNγ and both MHC class I molecules and CD8⁺ T cell activation score (p<0.0001). Furthermore, we found a significantly reduced risk of death in the glioma patients with high T cell activation score in comparison to those with low score (p=0.022). These findings suggest that a clinical application of IFNγ treatment may have potential benefits.

Identification of bile survivin and carbohydrate antigen 199 in distinguishing cholangiocarcinoma from benign obstructive jaundice

AIM

To investigate whether bile survivin and carbohydrate antigen 199 (CA199) can be helpful in distinguishing cholangiocarcinoma (malignant obstructive jaundice) from benign obstructive jaundice.

METHODS

Receiver operating characteristic curve was used to evaluate the feasibility of bile survivin and CA199 in differentiating cholangiocarcinoma from benign obstructive jaundice.

RESULTS

The area under the curve for survivin and CA199 in bile and serum were 0.780 (p < 0.001), 0.6 (p = 0.084), 0.746 (p < 0.001) and 0.542 (p = 0.464), respectively. Combination of bile survivin and CA199 could improve the diagnostic capability.

CONCLUSION

Bile survivin and CA199 are significantly increased in patients with cholangiocarcinoma and may be useful biomarkers in differentiating distinguishing cholangiocarcinoma from benign obstructive jaundice.

Survivin isoform expression in arsenic trioxide-treated acute promyelocytic leukemia cell line and patients: The odd expression pattern of survivin-2α

AIM

Survivin, an inhibitor of apoptosis protein, is overexpressed in most cancers and is associated with chemotherapy resistance, increased tumor recurrence and shorter patient survival. Several survivin splice variants have been described, and none of their expressions have been defined in acute promyelocytic leukemia (APL).

METHODS

Expression of the survivin gene isoforms (survivin, -2α, -2B, -ΔΕx3 and -3B) were analyzed in 50 peripheral blood and 19 bone marrow samples that were collected at different phases of the disease (diagnostic, remission and relapse) in APL patients treated with arsenic trioxide (ATO) as a front-line therapy. In addition, the human APL-derived cell line (NB4) was analyzed for the expression of survivin isoforms and capsase-3 in response to the ATO.

RESULTS

Survivin and its variants were overexpressed significantly in patient's bone marrow samples compared to peripheral blood or normal samples. Their expression was decreased after ATO treatment in both NB4 cells (except survivin-2α) and APL patients along with PML-RARα copy number reduction. Downregulation of survivin isoforms was associated with an increase in both caspase-3 gene expression and its enzymatic activity levels. In a patient who did not respond to ATO treatment, expression of survivin isoforms (except survivin-2α) were highly increased during the induction therapy.

CONCLUSION

Survivin isoforms are upregulated in APL patients, and their expression is diminished during the ATO treatment. In addition, overexpression of survivin and its variants (except survivin-2α) are associated with unfavorable results, suggesting that they may play an important role in mechanisms underlying the resistance of APL cells to ATO.

Phase I study of the novel Cdc2/CDK1 and AKT inhibitor terameprocol in patients with advanced leukemias

PURPOSE

Inhibiting survivin and Cdc2 (CDK1) has preclinical anti-leukemic activity. Terameprocol is a small molecule survivin and Cdc2/CDK1 inhibitor that was studied in a Phase I dose-escalation trial.

PATIENTS AND METHODS

Sixteen patients with advanced acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS) were enrolled and 15 treated with Terameprocol in three dose cohorts intravenously three times per week for 2 weeks every 21 days.

RESULTS

Patients had AML (n = 11), chronic myelogeneous leukemia in blast phase (CML-BP, n = 2) and one each T-cell acute lymphoblastic leukemia (T-ALL) and MDS. Four, five and six patients were treated at the 1000, 1500 and 2200 mg Terameprocol dose cohorts respectively. Common related treatment emergent adverse events (TEAE) were grade 1 or 2 headache, transaminitis and pruritus, with one grade 4 serious AE (SAE) of pneumonia. No dose limiting toxicity (DLT) was observed, however, due to other observed grade 3 TEAE the recommended phase 2 dose (RP2D) was determined at 1500 mg 3×/week for 2 weeks of a 21-day cycle. Partial remission and transfusion independence in a CML-BP patient (1500 mg cohort) and hematological improvement in erythroid (HI-E) and platelet lineage (HI-P) in an AML patient were observed. Five AML patients had stable disease greater/equal to 2 months. Pharmacodynamic studies showed a reduction of CDK1 and phospho-AKT protein expression.

CONCLUSION

Terameprocol can be safely administered to advanced leukemia patients, sufficient drug exposure was obtained and clinical activity and biomarker modulation were observed.

YM155 induces apoptosis through downregulation of specificity protein 1 and myeloid cell leukemia-1 in human oral cancer cell lines

BACKGROUND

YM155 is a small-molecule pro-apoptotic agent which has shown to inhibit survivin expression and induce apoptosis in various cancer cells. In this study, we investigated the function and molecular mechanism of YM155 in human oral cancer cells.

METHODS

The apoptotic effects and related signaling pathways of YM155 were evaluated using trypan blue exclusion assay, 4'-6-diamidino-2-phenylindole staining, Western blotting, RT-PCR, and siRNA.

RESULTS

YM155 inhibited the growth and caused caspase-dependent apoptosis in MC3 and HN22 cells. YM155 significantly suppressed the level of survivin protein expression through proteasome-dependent protein degradation to confirm its survivin-inhibiting function. YM155 reduced myeloid cell leukemia-1 (Mcl-1) protein, but it did not alter Mcl-1 mRNA. It was associated with the facilitation of lysosome-dependent protein degradation. The modifications of Mcl-1 and survivin by YM155 were caspase-independent manner. Treatment of MC-3 and HN22 cells with YM155 inhibited specificity protein 1 (Sp1) and the knockdown of Sp1 by siRNA demonstrated that Mcl-1 was regulated by Sp1 protein.

CONCLUSIONS

We demonstrated the novel mechanism that YM155 causes apoptosis of human oral cancer cell lines through downregulation of Sp1 and Mcl-1. Therefore, it may be a potential anticancer drug candidate for the treatment of oral cancer.

Inhibitors of apoptotic proteins: new targets for anticancer therapy

Inhibitors of apoptotic proteins (IAPs) can play an important role in inhibiting apoptosis by exerting their negative action on caspases (apoptotic proteins). There are eight proteins in this family: NAIP/BIRC1/NLRB, cellular IAP1 (cIAP1)/human IAP2/BIRC2, cellular IAP2 (cIAP2)/human IAP1/BIRC3, X-linked IAP (XIAP)/BIRC4, survivin/BIRC5, baculoviral IAP repeat (BIR)-containing ubiquitin-conjugating enzyme/apollon/BIRC6, livin/melanoma-IAP (ML-IAP)/BIRC7/KIAP, and testis-specific IAP (Ts-IAP)/hILP-2/BIRC8. Deregulation of these inhibitors of apoptotic proteins (IAPs) may push cell toward cancer and neurodegenerative disorders. Inhibitors of apoptotic proteins (IAPs) may provide new target for anticancer therapy. Drugs may be developed that are inhibiting these IAPs to induce apoptosis in cancerous cells.

Survivin as a preferential target for cancer therapy

Cancer is typically a consequence of imbalance between cell death and proliferation in a way favorable to cell proliferation and survival. Most conventional cancer therapies are based on targeting rapidly growing cancerous cells to block growth or enhance cell death, thereby, restoring the balance between these processes. In many instances, malignancies that develop resistance to current treatment modalities, such as chemotherapy, immunotherapy, and radiotherapy often present the greatest challenge in subsequent management of the patient. Studies have shown that under normal circumstances, cells utilize different death mechanisms, such as apoptosis (programmed cell death), autophagy, mitotic catastrophe, and necrosis to maintain homeostasis and physiological integrity of the organism, but these processes often appear to be altered in cancer. Thus, in recent years developing various strategies for administration of cytotoxic chemotherapeutics in combination with apoptosis-sensitizing reagents is receiving more emphasis. Here, we review the properties of the anti-apoptotic protein, survivin, a member of the inhibitor of apoptosis protein (IAP) family and the clinical feasibility and anti-cancer potential of drugs targeting this protein. We also discuss some key points and concerns that should be taken into consideration while developing drugs that target apoptotic proteins, such as survivin.

Detection and preliminary characterization of CD8+T lymphocytes specific for Wilms' tumor antigen in patients with non-Hodgkin lymphoma

Wilms' tumor antigen (WT1) is overexpressed in many different solid tumors and hematologic malignancies. However, little is known about WT1 expression or WT1-specific immune responses in patients with non-Hodgkin lymphoma (NHL). In a cross-sectional survey study, we investigated the immune recognition of WT1 by patients with NHL. Utilizing a WT1 overlapping peptide library, we discovered that a large percentage of patients with NHL of all grades maintain WT1-specific T cells. Ex vivo frequencies of these T cells measured from unfractionated samples by the CD137 activation marker assay were high in many patients (some > 1% CD8+). Using standard in vitro techniques we discovered that they were cytotoxic to WT1 peptide library-loaded T2 cells and WT1 antigen-primed autologous Epstein-Barr virus-transformed B cell lines (EBV-LCLs) and expressed interferon gamma (IFN-γ). In addition, we detected WT1 mRNA transcripts in diseased lymph node tissues of patients with NHL utilizing real-time quantitative polymerase chain reaction (RT-qPCR) technology. These results are the first example of strong T cell reactivity against WT1 in patients with NHL which also demonstrate strong cytotoxicity against peptide-loaded tumor cells. The potential for developing WT1 as a target for immunotherapy in NHL deserves further exploration.

Safety and pharmacokinetics of the antisense oligonucleotide (ASO) LY2181308 as a single-agent or in combination with idarubicin and cytarabine in patients with refractory or relapsed acute myeloid leukemia (AML)

Survivin is expressed in tumor cells, including acute myeloid leukemia (AML), regulates mitosis, and prevents tumor cell death. The antisense oligonucleotide sodium LY2181308 (LY2181308) inhibits survivin expression and may cause cell cycle arrest and restore apoptosis in AML. In this study, the safety, pharmacokinetics, and pharmacodynamics/efficacy of LY2181308 was examined in AML patients, first in a cohort with monotherapy (n = 8) and then post-amendment in a cohort with the combination of cytarabine and idarubicin treatment (n = 16). LY2181308 was administered with a loading dosage of three consecutive daily infusions of 750 mg followed by weekly intravenous (IV) maintenance doses of 750 mg. Cytarabine 1.5 g/m(2) was administered as a 4-hour IV infusion on Days 3, 4, and 5 of Cycle 1, and idarubicin 12 mg/m(2) was administered as a 30-minute IV infusion on Days 3, 4, and 5 of Cycle 1. Cytarabine and idarubicin were administered on Days 1, 2, and 3 of each subsequent 28-day cycle. Reduction of survivin was evaluated in peripheral blasts and bone marrow. Single-agent LY2181308 was well tolerated and survivin was reduced only in patients with a high survivin expression. In combination with chemotherapy, 4/16 patients had complete responses, 1/16 patients had incomplete responses, and 4/16 patients had cytoreduction. Nine patients died on study: 6 (monotherapy), 3 (combination). LY2181308 alone is well tolerated in patients with AML. In combination with cytarabine and idarubicin, LY2181308 does not appear to cause additional toxicity, and has shown some clinical benefit needing confirmation in future clinical trials.

Survivin selective inhibitor YM155 induce apoptosis in SK-NEP-1 Wilms tumor cells

Background

Survivin, a member of the family of inhibitor of apoptosis proteins, functions as a key regulator of mitosis and programmed cell death. YM155, a novel molecular targeted agent, suppresses survivin, which is overexpressed in many tumor types. The aim of this study was to determine the antitumor activity of YM155 in SK-NEP-1 cells.

Methods

SK-NEP-1 cell growth in vitro and in vivo was assessed by MTT and nude mice experiments. Annexin V/propidium iodide staining followed by flow cytometric analysis was used to detect apoptosis in cell culture. Then gene expression profile of tumor cells treated with YM155 was analyzed with real-time PCR arrays. We then analyzed the expression data with MEV (Multi Experiment View) cluster software. Datasets representing genes with altered expression profile derived from cluster analyses were imported into the Ingenuity Pathway Analysis tool.

Results

YM155 treatment resulted in inhibition of cell proliferation of SK-NEP-1cells in a dose-dependent manner. Annexin V assay, cell cycle, and activation of caspase-3 demonstrates that YM155 induced apoptosis in SK-NEP-1 cells. YM155 significantly inhibited growth of SK-NEP-1 xenografts (YM155 5 mg/kg: 1.45 ± 0.77 cm³; YM155 10 mg/kg: 0.95 ± 0.55 cm³) compared to DMSO group (DMSO: 3.70 ± 2.4 cm³) or PBS group cells (PBS: 3.78 ± 2.20 cm³, ANOVA P < 0.01). YM155 treatment decreased weight of tumors (YM155 5 mg/kg: 1.05 ± 0.24 g; YM155 10 mg/kg: 0.72 ± 0.17 g) compared to DMSO group (DMSO: 2.06 ± 0.38 g) or PBS group cells (PBS: 2.36 ± 0.43 g, ANOVA P < 0.01). Real-time PCR array analysis showed between Test group and control group there are 32 genes significantly up-regulated and 54 genes were significantly down-regulated after YM155 treatment. Ingenuity pathway analysis (IPA) showed cell death was the highest rated network with 65 focus molecules and the significance score of 44. The IPA analysis also groups the differentially expressed genes into biological mechanisms that are related to cell death, cellular function maintenance, cell morphology, carbohydrate metabolism and cellular growth and proliferation. Death receptor signaling (3.87E-19), TNFR1 signaling, induction of apoptosis by HIV1, apoptosis signaling and molecular mechanisms of cancer came out to be the top four most significant pathways. IPA analysis also showed top molecules up-regulated were BBC3, BIRC3, BIRC8, BNIP1, CASP7, CASP9, CD5, CDKN1A, CEBPG and COL4A3, top molecules down-regulated were ZNF443, UTP11L, TP73, TNFSF10, TNFRSF1B, TNFRSF25, TIAF1, STK17A, SST and SPP1, upstream regulator were NR3C1, TP53, dexamethasone , TNF and Akt.

Conclusions

The present study demonstrates that YM155 treatment resulted in apoptosis and inhibition of cell proliferation of SK-NEP-1cells. YM155 had significant role and little side effect in the treatment of SK-NEP-1 xenograft tumors. Real-time PCR array analysis firstly showed expression profile of genes dyes-regulated after YM155 treatment. IPA analysis also represents new molecule mechanism of YM155 treatment, such as NR3C1 and dexamethasone may be new target of YM155. And our results may provide new clues of molecular mechanism of apoptosis induced by YM155.

Overexpression of survivin initiates hematologic malignancies in vivo

Survivin is an inhibitor of apoptosis protein family member that has an essential role in cellular proliferation as a component of the chromosome passenger complex. Survivin is highly expressed in embryos and in proliferating adult tissues, but it is not expressed in most differentiated cells. During tumorigenesis, however, survivin expression is dramatically upregulated. Although many studies have shown that survivin is required for cancer cells, the extent to which survivin contributes to the initiation of tumors is unknown. Here we show that transgenic mice that overexpress survivin in hematopoietic cells are at an increased risk of hematologic tumors. In examining how survivin might contribute to tumorigenesis, we observed that hematopoietic cells engineered to overexpress survivin are less susceptible to apoptosis. We conclude that survivin may promote tumorigenesis by imparting a survival advantage to cells that acquire additional genetic lesions.

TEL-AML1 regulation of survivin and apoptosis via miRNA-494 and miRNA-320a

There is increasing evidence that miRNA and transcription factors interact in an instructive fashion in normal and malignant hematopoiesis. We explored the impact of TEL-AML1 (ETV6-RUNX1), the most common fusion protein in childhood leukemia, on miRNA expression and the leukemic phenotype. Using RNA interference, miRNA expression arrays, and quantitative polymerase chain reaction, we identified miRNA-494 and miRNA-320a to be up-regulated upon TEL-AML1 silencing independently of TEL expression. Chromatin immunoprecipitation analysis identified miRNA-494 as a direct miRNA target of the fusion protein TEL-AML1. Using bioinformatic analysis as well as functional luciferase experiments, we demonstrate that survivin is a target of the 2 miRNAs. miRNA-494 and miRNA-320a were introduced to the cells by transfection and survivin expression determined by Western blot analysis. These miRNAs blocked survivin expression and resulted in apoptosis in a similar manner as TEL-AML1 silencing by itself; this silencing was also shown to be Dicer-dependent. miRNAs-494 and -320a are expressed at lower levels in TEL-AML1+ leukemias compared with immunophenotype-matched nonTEL-AML1 acute lymphoblastic leukemia subtypes, and within TEL-AML1+ leukemias their expression is correlated to survivin levels. In summary our data suggest that TEL-AML1 might exert its antiapoptotic action at least in part by suppressing miRNA-494 and miRNA-320a, lowering their expression causing enhanced survivin expression.

Transcriptional regulation of survivin by c-Myc in BCR/ABL-transformed cells: implications in anti-leukaemic strategy

BCR/ABL can cause chronic myelogenous leukaemia (CML) in part by altering the transcription of specific genes with growth- and/or survival-promoting functions. Recently, BCR/ABL has been shown to activate survivin, an important regulator of cell growth and survival, but the precise molecular mechanisms behind its expression and consequences thereof in CML cells remain unclear. Here, we reported that BCR/ABL promotes survivin expression and its cytoplasmic accumulation. The increase of survivin was largely controlled at the transcriptional level through a mechanism mediated by JAK2/PI3K signal pathways that activated c-Myc, leading to transactivation of survivin promoter. Dynamic down-regulation of survivin was a key event involved in imatinib-induced cell death while forced expression of survivin partially counteracted imatinib's effect on cell survival. Additionally, shRNA-mediated silencing of survivin or c-Myc eradicated colony formation of K562 cells in semi-solid culture system, implying an essential role for this transcriptional network in BCR/ABL-mediated cell transformation and survival. Finally, interruption of c-Myc activity by 10058-F4 exerted an anti-leukaemia effect with a synergistic interaction with imatinib and overcame the anti-apoptosis rescued by IL-3 supplement. In conclusion, we have identified JAK2/PI3K-mediated and c-Myc-dependent transactivation of survivin as a novel pathway in the transcriptional network orchestrated by BCR/ABL. These results suggest that the interference with this circuitry might be a potential utility for CML treatment.

Survivin: a new target for anti-cancer therapy

Survivin is one of the most cancer-specific proteins identified to date, being upregulated in almost all human tumors. Biologically, survivin has been shown to inhibit apoptosis, enhance proliferation and promote angiogenesis. Because of its upregulation in malignancy and its key role in apoptosis, proliferation and angiogenesis, survivin is currently attracting considerable attention as a new target for anti-cancer therapies. In several animal model systems, downregulation of survivin or inactivation of its function has been shown to inhibit tumor growth. Strategies under investigation to target survivin include antisense oligonucleotides, siRNA, ribozymes, immunotherapy and small molecular weight molecules. The translation of these findings to the clinic is currently ongoing with a number of phase I/II clinical trials targeting survivin in progress. These include use of the antisense oligonucleotide LY2181308, the low molecular weight molecule inhibitor YM155 and survivin-directed autologous cytotoxic T lymphocytes. The optimum use of survivin antagonists in the treatment of cancer is likely to be in combination with conventional cancer therapies.

Ponicidin inhibits monocytic leukemia cell growth by induction of apoptosis

In this study two monocytic leukemia cell lines, U937 and THP-1 cells, were used to investigate the anti-proliferation effects caused by ponicidin. Cell viability was measured by an MTT assay. Cell apoptosis was assessed by flow cytometry as well as DNA fragmentation analysis. Cell morphology was observed using an inverted microscope and Hoechst 33258 staining. RT-PCR and Western blot analysis were used to detect survivin as well as Bax and Bcl-2 expressions after the cells were treated with different concentrations of ponicidin. The results revealed that ponicidin could inhibit the growth of U937 and THP-1 cells significantly by induction of apoptosis. The suppression was in both time- and dose-dependent manner. Marked morphological changes of cell apoptosis were observed clearly after the cells were treated with ponicidin for 48 approximately 72 h. RT-PCR and Western blot analysis demonstrated that both survivin and Bcl-2 expressions were down-regulated remarkably while Bax expression remained constant before and after apoptosis occurred. We therefore conclude that ponicidin has significant anti-proliferation effects by inducing apoptosis on leukemia cells in vitro, downregulation of survivin as well as Bcl-2 expressions may be the important apoptosis inducing mechanisms. The results suggest that ponicidin may serve as potential therapeutic agent for leukemia.

Leukemia-associated antigens are critical for the proliferation of acute myeloid leukemia cells

Acute myeloid leukemia (AML) is the most common acute leukemia in adults. With intensive induction therapy, most patients younger than 60 years achieve complete remission. However, even if these younger patients were treated intensively, more than 50% will relapse. Clinical results of patients older than 60 years are more unfavorable. Therefore, in all patients with AML, the overall survival is still low. In the past decade, several leukemia-associated antigens (LAA) have been identified in patients with acute myeloid leukemia. BAGE, BCL-2, OFA-iLRP, FLT3-ITD, G250, hTERT, PRAME, proteinase 3, RHAMM, survivin, and WT-1 are all LAAs that have been shown to induce CD8+ T-cell recognition and for some antigens also humoral immune responses. Interestingly, most of these LAAs are linked to cell cycle or proliferation. This article discusses the balance between LAA-driven leukemia cell expansion and the elimination of these cells through attacks on LAAs by the immune system. Current knowledge of the function and CD8+ T-cell recognition of LAAs is reviewed and an outlook is given on how to improve T-cell responses to LAAs in acute myeloid leukemia cells.

INCENP (inner centromere protein) is overexpressed in high grade non-Hodgkin B-cell lymphomas

Inner centromere protein (INCENP) is a member of the Chromosomal Passenger Complex (CPC), which is a four member protein complex essential for proper completion of mitosis and cell division (cytokinesis). Inappropriate chromosomal segregation and cytokinesis due to deregulated expression of chromosome passenger proteins may lead to aneuploidy and cancer including lymphomas. According to our knowledge this is the first study investigating immunohistochemical expression of INCENP in lymphoma cases and cancer tissues in general. Our purpose was to characterize the expression of INCENP in cases of non-Hodgkin B-cell lymphomas, to compare the immunoreactivity between low and high grades and to evaluate the correlation between INCENP and MIB-1 labeling indices. We examined INCENP and MIB-1 immunoreactivity in paraffin sections of 55 samples of non-Hodgkin B-cell lymphomas, obtained from 55 patients, 31 men and 24 women. Thirty were of high grade and 25 were of low grade. Our results showed significantly higher nuclear immunohistochemical expression of INCENP in high grade B-cell lymphomas versus low grade ones. Also INCENP expression was significantly correlated with MIB-1 labeling index. Taken together our results point to a possible association between increased INCENP immunostaining and B-cell lymphoma aggressiveness and also stress the need for further investigating the expression of INCENP and other mitotic regulatory proteins in lymphomas and other malignant neoplasms.

Src kinase inhibitors induce apoptosis and mediate cell cycle arrest in lymphoma cells

Src kinases are involved in multiple cellular contexts such as proliferation, adhesion, tumor invasiveness, angiogenesis, cell cycle control and apoptosis. We here demonstrate that three newly developed dual selective Src/Abl kinase inhibitors (SrcK-I) (AZM559756, AZD0530 and AZD0424) are able to induce apoptosis and cell cycle arrest in BCR-ABL, c-KIT and platelet-derived growth factor-negative lymphoma cell lines. Treatment of DOHH-2, WSU-NHL, Raji, Karpas-299, HUT78 and Jurkat cells with SrcK-I revealed that the tested substances were effective on these parameters in the cell lines DOHH-2 and WSU-NHL, whereas the other tested cell lines remained unaffected. Phosphorylation of Lyn and in particular Lck were affected most heavily by treatment with the SrcK-I. Extrinsic as well as intrinsic apoptosis pathways were activated and elicited unique expressional patterns of apoptosis-relevant proteins such as downregulation of survivin, Bcl-XL and c-FLIP. Protein levels of c-abl were downregulated and Akt phosphorylation was decreased by treatment with SrcK-I. Basal expression levels of c-Myc were notably lower in sensitive cell lines as compared with nonsensitive cell lines, possibly providing an explanation for sensitivity versus resistance against these novel substances. This study provides the first basis for establishing novel SrcK-I as weapons in the arsenal against lymphoma cells.

Survivin, a cancer target with an emerging role in normal adult tissues

Survivin, an inhibitor of apoptosis protein, is highly expressed in most cancers and associated with chemotherapy resistance, increased tumor recurrence, and shorter patient survival, making antisurvivin therapy an attractive cancer treatment strategy. However, growing evidence indicates that survivin is expressed in normal adult cells, particularly primitive hematopoietic cells, T lymphocytes, polymorphonuclear neutrophils, and vascular endothelial cells, and may regulate their proliferation or survival. In preclinical animal models, targeted antisurvivin therapies show efficacy without overt toxicity. However, consequences of prolonged survivin disruption in normal cells, particularly those associated with continuous renewal, have not been clearly determined. Understanding the role of survivin in normal versus malignant cells will be important in identifying strategies that maximally disrupt survivin in cancer cells with minimal effect on normal tissues. In this review, we summarize the prognostic relevance of survivin in cancer that justifies the pursuit of antisurvivin therapies and discuss differences in survivin expression between normal and cancer cells. We subsequently review expression of survivin in normal adult tissues and evaluate preclinical antisurvivin therapies reported to date in light of emerging roles for survivin in normal physiology, particularly hematopoiesis, angiogenesis, and immune function.

Tetraploidy/aneuploidy and stem cells in cancer promotion: The role of chromosome passenger proteins

While polyploidy, a state of having fully duplicated sets of chromosomes per cell, has been described in normally developing bone marrow megakaryocytes or as an adaptive response in other cell types, aneuploidy is never detected in normal cells. Tetraploidy or aneuploidy can be induced by several signals and it is highly prevalent in different forms of cancers, suggesting a role for this cell cycle state in promoting cellular transformation. Investigations suggested that loss of heterozygosity of cancer-related genes in stem cells might contribute to genetic instability in progeny cells and to subsequent cancer development. Deregulated expression of chromosome passenger proteins, such as Aurora kinases or Survivin, is a hallmark of various cancers, and experimentally induced changes in these regulators can promote tetraploidy or aneuploidy and loss of heterozygosity. Our studies described an induction of tetraploidy/aneuploidy by a stable form of Aurora-B, leading to acquisition of transformation properties. It is intriguing to speculate that in some cancers, tetraploidy/aneuploidy induced by deregulated expression of a mitotic regulator represents a primary event that leads to unbalanced expression of a cluster of crucial genes and to cellular transformation.

Loss of SHP1 enhances JAK3/STAT3 signaling and decreases proteosome degradation of JAK3 and NPM-ALK in ALK+ anaplastic large-cell lymphoma

Previous studies showed that most cases of ALK(+) anaplastic large-cell lymphoma (ALK(+)ALCL) do not express SHP1, a tyrosine phosphatase and an important negative regulator for cellular signaling pathways such as that of JAK/STAT. To fully assess the biologic significance of loss of SHP1 in ALK(+)ALCL, we transfected SHP1 plasmids into 2 SHP1(-), ALK(+)ALCL cell lines, Karpas 299 and SU-DHL-1. After 24 hours of transfection, pJAK3 and pSTAT3 were decreased, and these changes correlated with down-regulation of STAT3 downstream targets including cyclin D3, mcl-1, and bcl-2. Expression of SHP1 in these 2 cell lines also resulted in marked decreases in the protein levels of JAK3 and NPM-ALK, and these effects were reversible by proteosome inhibitor MG132. Conversely, when SHP1 expression in SUP-M2 (a SHP1(+) ALK(+)ALCL cell line) was inhibited using siRNA, pSTAT3, pJAK3, JAK3, and NPM-ALK were all up-regulated. Coimmunoprecipitation studies showed that SHP1 was physically associated with JAK3 and NPM-ALK. SHP1 expression in Karpas 299 and SU-DHL-1 led to significant G(1) cell cycle arrest but not apoptosis. To conclude, loss of SHP1 contributes to the pathogenesis of ALK(+)ALCL by 2 mechanisms: (1) it leaves the tyrosine phosphorylation and activation of JAK3/STAT3 unchecked and (2) it decreases proteosome degradation of JAK3 and NPM-ALK.

Disruption of the inhibitor of apoptosis protein survivin sensitizes Bcr-abl-positive cells to STI571-induced apoptosis

The Bcr-abl oncogene induces hematopoietic cell transformation and protects cells from apoptosis; however, the mechanisms whereby Bcr-abl blocks apoptosis are poorly defined. We examined whether the inhibitor of apoptosis protein (IAP) family, in particular survivin, are regulated by Bcr-abl. Overexpression of Bcr-abl in Mo7e or BaF3 hematopoietic cells elevated survivin mRNA and protein concomitant with a 4-fold increase in survivin promoter activity. The region of the survivin promoter responding to Bcr-abl was narrowed down to a 116 bp fragment between nucleotides -1,194 and -1,078. The IAP family member IAP-like protein-2 was also up-regulated by Bcr-abl. Disruption of Bcr-abl in Bcr-abl-transduced BaF3 cells by small interfering RNA resulted in 3- to 4-fold reduction in survivin protein confirming the link between Bcr-abl and survivin. Survivin disruption in Bcr-abl-transduced Mo7e cells, or in K562 cells that endogenously express Bcr-abl, by transfection with dominant-negative or antisense survivin constructs promoted apoptosis induced by the Bcr-abl tyrosine kinase inhibitor STI571, which was accompanied by caspase-dependent cleavage of Bcr-abl, mitochondrial membrane potential disruption, and enhanced mitochondrial cytochrome c release. Although ectopic survivin protected K562 cells from apoptosis induced by STI571, it did not protect cells from apoptosis induced either by tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) or the combination of TRAIL plus Hemin. Our results identify a new signal pathway downstream of Bcr-abl, in addition to the Bcl-2 family involved in the antiapoptotic effects of Bcr-abl, and suggest that anti-survivin therapy may have utility in patients with chronic myelogenous leukemia.