Aberrant expression of caspase cascade regulatory genes in adult T-cell leukaemia: survivin is an important determinant for prognosis

Mechanisms of Oncogenesis by HTLV-1 Tax

The human T-cell lymphotropic virus type 1 (HTLV-1) is the etiological agent of adult T-cell leukemia/lymphoma (ATLL), a neoplasm of CD4+CD25+ T cells that occurs in 2-5% of infected individuals after decades of asymptomatic latent infection. Multiple HTLV-1-encoded regulatory proteins, including Tax and HTLV-1 basic leucine zipper factor (HBZ), play key roles in viral persistence and latency. The HTLV-1 Tax oncoprotein interacts with a plethora of host cellular proteins to regulate viral gene expression and also promote the aberrant activation of signaling pathways such as NF-κB to drive clonal proliferation and survival of T cells bearing the HTLV-1 provirus. Tax undergoes various post-translational modifications such as phosphorylation and ubiquitination that regulate its function and subcellular localization. Tax shuttles in different subcellular compartments for the activation of anti-apoptotic genes and deregulates the cell cycle with the induction of DNA damage for the accumulation of genomic instability that can result in cellular immortalization and malignant transformation. However, Tax is highly immunogenic and therefore HTLV-1 has evolved numerous strategies to tightly regulate Tax expression while maintaining the pool of anti-apoptotic genes through HBZ. In this review, we summarize the key findings on the oncogenic mechanisms used by Tax that set the stage for the development of ATLL, and the strategies used by HTLV-1 to tightly regulate Tax expression for immune evasion and viral persistence.

Expression of miR-34a in T-Cells Infected by Human T-Lymphotropic Virus 1

Human T-lymphotropic virus 1 (HTLV-1) immortalizes T-cells and is the causative agent of adult T-cell leukemia/lymphoma (ATLL). HTLV-1 replication and transformation are governed by multiple interactions between viral regulatory proteins and host cell factors that remain to be fully elucidated. The present study investigated the impact of HTLV-1 infection on the expression of miR-34a, a microRNA whose expression is downregulated in many types of cancer. Results of RT-PCR assays showed that five out of six HTLV-1-positive cell lines expressed higher levels of miR-34a compared to normal PBMC or purified CD4+ T-cells. ATLL cell line ED, which did not express miR-34a, showed methylation of the miR-34a promoter. Newly infected PBMC and samples from 10 ATLL patients also showed a prominent increase in miR-34a expression compared to PBMC controls. The primary miR-34a transcript expressed in infected cell line C91PL contained binding motifs for NF-κB and p53. Pharmacological inhibition of NF-κB with Bay 11-7082 indicated that this pathway contributes to sustain miR-34a levels in infected cells. Treatment of infected cell lines with the p53 activator nutlin-3a resulted in a further increase in miR-34a levels, thus confirming it as a transcriptional target of p53. Nutlin-3a-treated cells showed downregulation of known miR-34a targets including the deacetylase SIRT1, which was accompanied by increased acetylation of p53, a substrate of SIRT1. Transfection of C91PL cells with a miR-34a mimic also led to downregulation of mRNA targets including SIRT1 as well as the pro-apoptotic factor BAX. Unlike nutlin-3a, the miR-34a mimic did not cause cell cycle arrest or reduce cell viability. On the other hand, sequestration of miR-34a with a sponge construct resulted in an increase in death of C91PL cells. These findings provide evidence for a functional role for miR-34a in fine-tuning the expression of target genes that influence the turnover of HTLV-1-infected cells.

Human T Cell Leukemia Virus Type 1: Persistence and Pathogenesis

Human T cell leukemia virus type 1 (HTLV-1), also known as human T lymphotropic virus type 1, was the first exogenous human retrovirus discovered. Unlike the distantly related lentivirus HIV-1, HTLV-1 causes disease in only 5-10% of infected people, depending on their ethnic origin. But whereas HIV-1 infection and the consequent diseases can be efficiently contained in most cases by antiretroviral drug treatment, there is no satisfactory treatment for the malignant or inflammatory diseases caused by HTLV-1. The purpose of the present article is to review recent advances in the understanding of the mechanisms by which the virus persists in vivo and causes disabling or fatal diseases.

IL-10-mediated signals act as a switch for lymphoproliferation in Human T-cell leukemia virus type-1 infection by activating the STAT3 and IRF4 pathways

Human T-cell leukemia virus type-1 (HTLV-1) causes two distinct diseases, adult T-cell leukemia/lymphoma (ATL) and HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Since there are no disease-specific differences among HTLV-1 strains, the etiological mechanisms separating these respective lymphoproliferative and inflammatory diseases are not well understood. In this study, by using IL-2-dependent HTLV-1-infected T-cell lines (ILTs) established from patients with ATL and HAM/TSP, we demonstrate that the anti-inflammatory cytokine IL-10 and its downstream signals potentially act as a switch for proliferation in HTLV-1-infected cells. Among six ILTs used, ILTs derived from all three ATL patients grew much faster than those from three HAM/TSP patients. Although most of the ILTs tested produced IFN-γ and IL-6, the production of IL-10 was preferentially observed in the rapid-growing ILTs. Interestingly, treatment with exogenous IL-10 markedly enhanced proliferation of the slow-growing HAM/TSP-derived ILTs. The IL-10-mediated proliferation of these ILTs was associated with phosphorylation of STAT3 and induction of survivin and IRF4, all of which are characteristics of ATL cells. Knockdown of STAT3 reduced expression of IL-10, implying a positive-feedback regulation between STAT3 and IL-10. STAT3 knockdown also reduced survivin and IRF4 in the IL-10- producing or IL-10- treated ILTs. IRF4 knockdown further suppressed survivin expression and the cell growth in these ILTs. These findings indicate that the IL-10-mediated signals promote cell proliferation in HTLV-1-infected cells through the STAT3 and IRF4 pathways. Our results imply that, although HTLV-1 infection alone may not be sufficient for cell proliferation, IL-10 and its signaling pathways within the infected cell itself and/or its surrounding microenvironment may play a critical role in pushing HTLV-1-infected cells towards proliferation at the early stages of HTLV-1 leukemogenesis. This study provides useful information for understanding of disease mechanisms and disease-prophylactic strategies in HTLV-1 infection.

Role of the HTLV-1 viral factors in the induction of apoptosis

Adult T-cell leukemia (ATL) and HTLV-1-associated Myelopathy/Tropical Spastic Paraparesis (HAM/TSP) are the two main diseases that are caused by the HTLV-1 virus. One of the features of HTLV-1 infection is its resistance against programmed cell death, which maintains the survival of cells to oncogenic transformation and underlies the viruses' therapeutic resistance. Two main genes by which the virus develops cancer are Tax and HBZ; playing an essential role in angiogenesis in regulating viral transcription and modulating multiple host factors as well as apoptosis pathways. Here we have reviewed by prior research how the apoptosis pathways are suppressed by the Tax and HBZ and new drugs which have been designed to deal with this suppression.

Novel interactions between the HTLV antisense proteins HBZ and APH-2 and the NFAR protein family: Implications for the HTLV lifecycles

The human T-cell leukaemia virus type 1 and type 2 (HTLV-1/HTLV-2) antisense proteins HBZ and APH-2 play key roles in the HTLV lifecycles and persistence in the host. Nuclear Factors Associated with double-stranded RNA (NFAR) proteins NF90/110 function in the lifecycles of several viruses and participate in host innate immunity against infection and oncogenesis. Using GST pulldown and co-immunoprecipitation assays we demonstrate specific novel interactions between HBZ/APH-2 and NF90/110 and characterised the protein domains involved. Moreover we show that NF90/110 significantly enhance Tax mediated LTR activation, an effect that was abolished by HBZ but enhanced by APH-2. Additionally we found that HBZ and APH-2 modulate the promoter activity of survivin and are capable of antagonising NF110-mediated survivin activation. Thus interactions between HTLV antisense proteins and the NFAR protein family have an overall positive impact on HTLV infection. Hence NFARs may represent potential therapeutic targets in HTLV infected cells.

YM155 suppresses cell proliferation and induces cell death in human adult T-cell leukemia/lymphoma cells

Adult T-cell leukemia (ATL) is an aggressive malignancy of peripheral T cells infected with human T-cell leukemia virus type 1 (HTLV-1). The prognosis of patients with aggressive ATL remains poor because ATL cells acquire resistance to conventional cytotoxic agents. Therefore, development of novel agents is urgently needed. We examined the effects of YM155, sepantronium bromide, on cell proliferation and survival of ATL or HTLV-1-infected T-cell lines, S1T, MT-1, and MT-2. We found that YM155 suppressed cell proliferation in these cells and induced cell death in S1T and MT-1 cells. Both real-time quantitative polymerase chain reaction and immunoblot analyses showed suppression of survivin expression in S1T, MT-1, and MT-2 cells. In addition, we observed the cleavage of caspase-3 and poly(ADP-ribose) polymerase in YM155-treated S1T and MT-1 cells, indicating that YM155 induces caspase-dependent apoptosis in these cells. To clarify the mechanism of drug tolerance of MT-2 cells in terms of YM155-induced cell death, we examined intracellular signaling status in these cells. We found that STAT3, STAT5, and AKT were constitutively phosphorylated in MT-2 cells but not in S1T and MT-1 cells. Treatment with YM155 combined with the STAT3 inhibitor S3I-201 significantly suppressed cell proliferation compared to that with either YM155 or S3I-201 in MT-2 cells, indicating that STAT3 may play a role in tolerance of MT-2 cells to YM155 and that STAT3 may therefore be a therapeutic target for YM155-resistant ATL cells. These results suggest that YM155 presents potent antiproliferative and apoptotic effects via suppression of survivin in ATL cells in which STAT3 is not constitutively phosphorylated. YM155 merits further investigation as a potential chemotherapeutic agent for ATL.

HTLV-1 bZIP Factor RNA and Protein Impart Distinct Functions on T-cell Proliferation and Survival

Infection of T cells with human T-cell leukemia virus type-1 (HTLV-1) induces clonal proliferation and is closely associated with the onset of adult T-cell leukemia-lymphoma (ATL) and inflammatory diseases. Although Tax expression is frequently suppressed in HTLV-1-infected cells, the accessory gene, HTLV-1 bZIP factor (HBZ), is continuously expressed and has been implicated in HTLV-1 pathogenesis. Here, we report that transduction of mouse T cells with specific mutants of HBZ that distinguish between its RNA and protein activity results in differential effects on T-cell proliferation and survival. HBZ RNA increased cell number by attenuating apoptosis, whereas HBZ protein induced apoptosis. However, both HBZ RNA and protein promoted S-phase entry of T cells. We further identified that the first 50 bp of the HBZ coding sequence are required for RNA-mediated cell survival. Transcriptional profiling of T cells expressing wild-type HBZ, RNA, or protein revealed that HBZ RNA is associated with genes involved in cell cycle, proliferation, and survival, while HBZ protein is more closely related to immunological properties of T cells. Specifically, HBZ RNA enhances the promoter activity of survivin, an inhibitor of apoptosis, to upregulate its expression. Inhibition of survivin using YM155 resulted in impaired proliferation of several ATL cell lines as well as a T-cell line expressing HBZ RNA. The distinct functions of HBZ RNA and protein may have several implications for the development of strategies to control the proliferation and survival mechanisms associated with HTLV-1 infection and ATL.

Localization and upregulation of survivin in cancer health disparities: a clinical perspective

Survivin is one of the most important members of the inhibitors of apoptosis protein family, as it is expressed in most human cancers but is absent in normal, differentiated tissues. Lending to its importance, survivin has proven associations with apoptosis and cell cycle control, and has more recently been shown to modulate the tumor microenvironment and immune evasion as a result of its extracellular localization. Upregulation of survivin has been found in many cancers including breast, prostate, pancreatic, and hematological malignancies, and it may prove to be associated with the advanced presentation, poorer prognosis, and lower survival rates observed in ethnically diverse populations.

5-Azacitidine induces demethylation of PTPL1 and inhibits growth in non-Hodgkin lymphoma

Non-Hodgkin lymphoma (NHL) consists of various lymphoid malignancies with a diverse clinical pathology and biological characteristics. Methylation of cytosine residues by DNA methyltransferases at CpG dinucleotides in the promoter region of the genes is a major epigenetic modification in mammalian genomes that can have profound effects on gene expression. The PTPL1 methylation pattern was screened by methylation‑specific polymerase chain reaction (MSP) in 7 lymphoma‑derived cell lines and in 47 samples of diffuse large B cell lymphoma (DLBCL). The PTPL1 gene was hypermethylated in the CA46, Raji, Jurkat and DB cell lines; however, it was unmethylated in the Hut78, Maver and Z138 cell lines. The expression of PTPL1 mRNA was re‑inducible by 5‑azacytidine (5‑Aza), an agent of DNA demethylation. The methylations were detected in 59.6% of DLBCL versus 6.3% in reactive lymph node proliferation. Therefore, the present data showed that PTPL1 was epigenetically regulated in NHL suggesting an involvement of the PTPL1 tumor‑suppressor genes in NHL, and highlights 5-Aza as a potential therapeutic candidate for NHL.

Relationship between Survivin and gastric cancer

Survivin is a member of the apoptosis inhibitory protein family [inhibitor of apoptosis proteins (IAPs)] found in recent years. It is expressed in tumors and fetal tissue and closely related to tumor cell differentiation, proliferation, invasion and metastasis. Currently, functional studies reveal that survivin is directly related to invasion, metastasis, resistance to chemotherapy, angiogenesis, diagnosis and prognosis in gastric cancer. Survivin may provide a new target for early diagnosis, gene therapy and prognosis evaluation in gastric cancer. This paper reviews the structure and biological characteristics of Survivin and discuss its relationship with tumor susceptibility, treatment, diagnosis and prognosis in gastric cancer.

Survivin-targeting Artificial MicroRNAs Mediated by Adenovirus Suppress Tumor Activity in Cancer Cells and Xenograft Models

Survivin is highly expressed in most human tumors and fetal tissue, and absent in terminally differentiated cells. It promotes tumor cell proliferation by negatively regulating cell apoptosis and facilitating cell division. Survivin's selective expression pattern suggests that it might be a suitable target for cancer therapy, which would promote death of transformed but not normal cells. This was tested using artificial microRNAs (amiRNAs) targeting survivin. After screening, two effective amiRNAs, which knocked down survivin expression, were identified and cloned into a replication-defective adenoviral vector. Tumor cells infected with the recombinant vector downregulated expression of survivin and underwent apoptotic cell death. Further studies showed that apoptosis was associated with increases in caspase 3 and cleaved Poly (ADP-ribose) polymerase, and activation of the p53 signaling pathway. Furthermore, amiRNA treatment caused blockade of mitosis and cell cycle arrest at the G2/M phase. In vivo, survivin-targeting amiRNAs expressed by adenoviral vectors effectively delayed growth of hepatocellular and cervical carcinomas in mouse xenograft models. These results indicate that silencing of survivin by amiRNA has potential for treatment of cancer.

The relationships between the chemosensitivity of human gastric cancer to paclitaxel and the expressions of class III β-tubulin, MAPT, and survivin

Lack of effective biomarkers is one of the challenges in current chemotherapy to predict drug response and sensitivity. This study was carried out to investigate the relationships between the expressions of class III β-tubulin, microtubule-associated protein tau (MAPT), survivin, and the sensitivity of primary gastric cancer (GC) to paclitaxel treatment. Reverse transcription PCR and Western blot were used to evaluate the mRNA and protein expressions of class III β-tubulin, MAPT, and survivin in fifty-four GC tissues. Viable tumor cells from gastric carcinomas were tested for their sensitivity to paclitaxel using adenosine triphosphate-based tumor chemosensitivity assay in vitro. Out of 54 samples, 30 samples were sensitive to paclitaxel, while the other 24 samples were resistant. The overall efficacy of paclitaxel was 55.56% (30/54). The mRNA expressions of class III β-tubulin and survivin were significantly correlated with the histological grade (P = 0.029, 0.009, respectively). The sensitivity of GC patients to paclitaxel treatment was inversely correlated with the mRNA and protein expressions of class III β-tubulin (P < 0.01), MAPT (P < 0.05), and survivin (P < 0.05). A significant positive correlation was found between class III β-tubulin and MAPT expression at mRNA and protein levels (mRNA: P = 0.037; protein: P = 0.001). Our results indicate that the expression levels of class III β-tubulin, MAPT, and survivin are good biomarkers for predicting the sensitivity of GC to paclitaxel treatment.

Terameprocol (tetra-O-methyl nordihydroguaiaretic acid), an inhibitor of Sp1-mediated survivin transcription, induces radiosensitization in non-small cell lung carcinoma

INTRODUCTION

Survivin, an inhibitor of apoptosis protein and key regulator of mitosis, is up-regulated in a variety of cancers and is often associated with a worse prognosis. Terameprocol down-regulates the Sp1-mediated transcription of survivin and Cdk1, which is important for cell cycle progression and many other proteins. Survivin inhibition has previously been shown to result in the induction of apoptosis and radiosensitization.

METHODS

This study examined the effects of terameprocol administration on survivin transcription and expression in HCC2429 and H460 lung cancer cells. We also examined the combined effects of radiation and terameprocol on apoptosis and radiosensitivity.

RESULTS

Using immunoblot analysis and luciferase assays, we confirmed that terameprocol decreases survivin transcription and protein expression. Ultimately, however, decreases in survivin expression failed to correlate with an increase in apoptosis. Nonetheless, clonogenic assay revealed that terameprocol induces increased radiosensitization in HCC2429 (dose enhancement ratio = 1.26, p = 0.019) and H460 (dose enhancement ratio = 1.18, p = 0.001) cells. Additionally, the data show no effect of terameprocol on cell cycle in either HCC2429 or H460 cells.

CONCLUSIONS

Terameprocol significantly enhances the sensitivity of non-small cell lung carcinoma cell lines to radiation therapy, although the mechanism of action remains unclear. Further study is warranted to assess the potential of terameprocol as an agent that may enhance the therapeutic ratio of radiotherapy in lung cancer.

Impacting tumor cell-fate by targeting the inhibitor of apoptosis protein survivin

Survivin (BIRC5), a member of the inhibitor of apoptosis protein (IAP) family that inhibits caspases and blocks cell death is highly expressed in cancer and is associated with a poorer clinical outcome. Functioning simultaneously during cell division and apoptosis inhibition, survivin plays a pivotal role in determining cell survival. Survivin has consistently been identified by molecular profiling analysis to be associated with higher tumor grade, more advanced disease, abbreviated survival, accelerated rates of recurrence, and chemotherapy and radiation resistance. Survivin's differential expression in cancer compared to normal tissue and its role as a nodal protein in a number of cellular pathways make it a highly flexible therapeutic target, suitable for small-molecule inhibitiors, molecular antagonists, and vaccination-based therapies. By targeting survivin it is hoped that multiple tumor signaling circuitries may be simultaneously disabled. This effect may be applicable to many tumor histologies irrespective of specific genetic makeup. To date, survivin inhibitors have shown modest activity as single agents, but it is anticipated that when given in combination with cytotoxic chemotherapy or monoclonal antibodies they may exhibit enhanced efficacy. This review discusses the complex circuitry of survivin in human cancers and highlights clinical trials involving novel agents that target this important protein.

Down-modulation of survivin expression and inhibition of tumor growth in vivo by EZN-3042, a locked nucleic acid antisense oligonucleotide

Survivin plays an important role in preventing apoptosis and permitting mitosis, and is highly expressed in various human cancers. EZN-3042 is a locked nucleic acid antisense oligonucleotide (LNA-AsODN) against survivin. We report the effects of EZN-3042 in animal models. In a chemical-induced liver regeneration model, treatment with a mouse homolog of EZN-3042 resulted in 80% down-modulation of survivin mRNA. In A549 and Calu-6 lung xenograft models, treatment with EZN-3042 single agent induced 60% down-modulation of survivin mRNA in tumors and 37-45% tumor growth inhibition (TGI). In Calu-6 model, when EZN-3042 was combined with paclitaxel, an 83% TGI was obtained. EZN-3042 is currently being evaluated in a Phase 1 clinical trial as a single agent and in combination with docetaxel.

Deguelin suppresses cell proliferation via the inhibition of survivin expression and STAT3 phosphorylation in HTLV-1-transformed T cells

Adult T-cell leukemia (ATL) is an aggressive malignancy of peripheral T cells infected with human T-cell leukemia virus type 1 (HTLV-1). The prognosis of aggressive ATL patients remains poor because of its resistance to conventional chemotherapy. We examined the effect of deguelin, a naturally occurring rotenoid, on HTLV-1-transformed T-cell lines, KUT-1 and MT-2 cells. We found that deguelin suppressed cell proliferation and induced cell death in these cells. Immunoblot analysis showed the inhibition of survivin expression and signal transducers, and activators of transcription (STAT) 3 phosphorylation of both cells. We also observed the cleavage of caspase-3 and poly(ADP-ribose) polymerase (PARP) in deguelin-treated cells, indicating that deguelin induces caspase-dependent apoptosis in these cells. Furthermore, proteasome inhibitor MG132 prevented the down-regulation of survivin expression and STAT3 dephosphorylation by deguelin, suggesting that the action mechanism of deguelin involves the degradation of survivin and phosphorylated STAT3 through the ubiquitin/proteasome pathway. Our data indicate that deguelin presents a potent anti-proliferative effect in part via the down-regulation of survivin expression and STAT3 phosphorylation in HTLV-1-transformed cells. Deguelin merits further investigation as a potential chemotherapeutic agent for ATL.

Detection of survivin mRNA in healthy oral mucosa, oral leucoplakia and oral cancer

BACKGROUND

Survivin is involved in modulation of cell death and cell division processes. Survivin expression in normal adult tissues has not been fully understood, although it is markedly lower than in cancer, where it is over-expressed.

OBJECTIVE

To investigate survivin expression in normal, potentially malignant and cancerous oral mucosa.

METHODS

We measured survivin mRNA levels by real-time RT-PCR in specimens of oral mucosa (15 from normal mucosa, 17 from potentially malignant lesions, 17 from neoplasms). Scores were compared using Kruskal-Wallis test and post hoc according to Conover. Chi-squared test was used for dichotomous data.

RESULTS

The median relative levels of survivin mRNA resulted six for normal mucosa, eight for potentially malignant lesions, 13 for cancers: differences among these three groups were statistically significant, as between cancer and potentially malignant lesions. Expression in normal mucosa and potentially lesions group showed no significant difference. Low, but not marginal expression of survivin in normal mucosa is a new finding, and it could be explained with the higher sensibility of our methods.

CONCLUSIONS

Survivin expression in oral potentially malignant lesions might indicate a progressive deregulation of expression paralleling oncogenesis, particularly during the first stages of process, suggesting a putative predictive role for survivin.

Survivin expression in the progression of chronic myeloid leukemia: A sequential study in 16 patients

An increase in the proliferation and resistance to apoptosis of leukemic cells has been found in chronic myeloid leukemia (CML) as the disease evolves from the chronic phase to blast crisis (BC). To contribute to a better knowledge of the molecular mechanisms involved in such biological abnormality, the expression of the survivin gene was studied by quantitative real-time polymerase chain reaction (PCR) in the chronic phase of CML and at BC in 16 patients in whom sequential RNA samples from the 2 phases of the disease were available. Survivin was significantly overexpressed in both the chronic phase and BC as compared with granulocytes from controls. In BC, survivin expression was 7-fold higher than in the chronic phase, with such an increase being more pronounced in the myeloid (17-fold) than in the lymphoid cases (3-fold) (P = 0.03). Cell proliferation was significantly increased at BC, with Ki-67 expression being 2.8-fold higher than in the chronic phase. Despite the overexpression of both survivin and Ki-67 at BC, no significant correlation between their expression levels was observed. These data support a possible role for survivin overexpression in the pathogenesis of the progression of CML. However, further studies are required to elucidate the possible prognostic importance of such biological findings in this disease.

Enhancement of TRAIL cytotoxicity by AG-490 in human ALL cells is characterized by downregulation of cIAP-1 and cIAP-2 through inhibition of Jak2/Stat3

The ability of death-inducing tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) to selectively kill a variety of cancer cells has been largely described, but one of the major concerns with the treatment is the occurrence of drug resistance and possible toxic side effects. Here, we report that TRAIL induces apoptosis in Jurkat and SUPT1 T cell lines and in human T-ALL blasts but not in healthy subject-derived peripheral blood mononuclear cells. In parallel, the treatment with TRAIL and Tyrphostin (AG-490), a selective Janus kinase 2 inhibitor, produces an evident enhancement of cytotoxicity, characterized by a significant inhibition of Stat3 phosphorylation compared to controls or to TRAIL alone-treated samples, and associated with a dramatic decrease of both cIAP-1 and cIAP-2 mRNA levels. Downregulation of cIAP-1 and cIAP-2 by specific small interference RNAs significantly amplifies TRAIL-reduced cytotoxicity. All together, these findings strongly indicate that cIAP-1 and cIAP-2 downregulation is a fundamental step in the signaling pathways mediating the combinatorial effect of TRAIL and AG-490 on T cell leukemia. These findings may help to open new routes for the development of less toxic pharmacological strategies in the treatment of patients affected by TRAIL-sensitive leukemias.

Overexpression of Aurora A by loss of CHFR gene expression increases the growth and survival of HTLV-1-infected T cells through enhanced NF-kappaB activity

Human T-cell leukemia virus type 1 (HTLV-1) is the etiologic agent for adult T-cell leukemia (ATL). Aurora A, a mitotic checkpoint protein, is overexpressed in human cancer cells. The cell cycle-dependent turnover of Aurora A is regulated by E3 ubiquitin ligases such as checkpoint with fork head-associated and ring finger (CHFR). Here, we found overexpression of Aurora A protein in HTLV-1-infected T-cell lines and primary ATL cells. The expression of CHFR mRNA was reduced in these cells by abnormal methylation of CHFR promoter region. Knockdown of Aurora A using small interfering RNA suppressed the growth of HTLV-1-infected T-cell line. Transfection of Aurora A expression plasmid enhanced Tax-induced nuclear factor-kappaB (NF-kappaB) reporter activity. Transfection of CHFR expression plasmid into an HTLV-1-infected T-cell line reduced cell growth, Aurora A protein level and constitutive NF-kappaB reporter activity. Aurora kinase inhibitor suppressed the growth and survival of HTLV-1-infected T-cell lines and primary ATL cells. It also reduced constitutive NF-kappaB activity in an HTLV-1-infected T-cell line by reducing IkappaB kinase beta phosphorylation and the expression of antiapoptotic protein survivin. Our results suggested that loss of CHFR expression resulted to accumulation of Aurora A, which increased NF-kappaB activity. These findings highlight the critical role of Aurora A in HTLV-1-infected T cells, making this molecule a potentially suitable target for future therapies for ATL.

Antisense RNA of survivin gene inhibits the proliferation of leukemia cells and sensitizes leukemia cell line to taxol-induced apoptosis

The effects of survivin antisense RNA on proliferation of leukemia cell line HL-60 and taxol-induced chemotherapy was explored. A cDNA fragment of survivin obtained by RT-PCR was inserted into a plamid vector named pcDNA3 in the reverse direction. The vector encoding antisense RNA of survivin was confirmed by restriction enzyme digestion and DNA sequencing. The recombinant plasmid was delivered into HL-60 cells by electroporation. Growth curves were plotted based on cell counting. Trypan blue dye exclusion assay and MTT assay were carried out after the cells were incubated with taxol. DNA gel electrophoresis and nuclear staining were performed for cell apoptosis assay. The correct construction of the recombinant plasmid has been identified by restriction enzyme digestion and DNA sequencing. A stable down-regulation has been achieved in HL-60 SVVas cells after G418 selection. Compared to HL-60 cells, the proliferation of HL-60 SVVas cells was significantly inhibited (P<0.05). Cytotoxicity assays indicated that IC(50) of HL-60 SVVas for taxol was relatively lower than controls (P<0.01). Apoptosis assays revealed that taxol-induced apoptosis was detected in HL-60 SVVas cells incubated with 50 ng/ml taxol for 12 h, while in HL-60 cells incubated with 100 ng/ml taxol for 72 h. It was suggested that Survivin antisense RNA could inhibit the proliferation of HL-60 cells and enhance taxol-induced apoptosis in HL-60 cells, which may lay an experimental foundation for further research on gene therapy in leukemia.

Human T-cell lymphotropic virus type 1 infection of CD34+ hematopoietic progenitor cells induces cell cycle arrest by modulation of p21(cip1/waf1) and survivin

Human T-cell lymphotropic virus type 1 (HTLV-1) is an oncogenic retrovirus and the etiologic agent of adult T-cell leukemia (ATL), an aggressive CD4(+) malignancy. HTLV-2 is highly homologous to HTLV-1; however, infection with HTLV-2 has not been associated with lymphoproliferative diseases. Although HTLV-1 infection of CD4(+) lymphocytes induces cellular replication and transformation, infection of CD34(+) human hematopoietic progenitor cells (HPCs) strikingly results in G(0)/G(1) cell cycle arrest and suppression of in vitro clonogenic colony formation by induction of expression of the cdk inhibitor p21(cip1/waf1) (p21) and concurrent repression of survivin. Immature CD34(+)/CD38(-) hematopoietic stem cells (HSCs) were more susceptible to alterations of p21 and survivin expression as a result of HTLV-1 infection, in contrast to more mature CD34(+)/CD38(+) HPCs. Knockdown of p21 expression in HTLV-1-infected CD34(+) HPCs partially abrogated cell cycle arrest. Notably, HTLV-2, an HTLV strain that is not associated with leukemogenesis, does not significantly modulate p21 and survivin expression and does not suppress hematopoiesis from CD34(+) HPCs in vitro. We speculate that the remarkable differences in the activities displayed by CD34(+) HPCs following infection with HTLV-1 or HTLV-2 suggest that HTLV-1 uniquely exploits cell cycle arrest mechanisms to establish a latent infection in hematopoietic progenitor/hematopoietic stem cells and initiates preleukemic events in these cells, which eventually results in the manifestation of ATL.

Enhancement of docetaxel-induced cytotoxicity and apoptosis by all-trans retinoic acid (ATRA) through downregulation of survivin (BIRC5), MCL-1 and LTbeta-R in hormone- and drug resistant prostate cancer cell line, DU-145

Background

The management of hormone-refractory prostate cancer (HRPC) still remains as an important challenge of daily oncology practice. Docetaxel has proved to be a first line treatment choice. All-trans retinoic acid (ATRA) could potently inhibit the growth of prostate cancer cells in vitro and its combination with various anticancer agents results in increased cytotoxicity. Based on these data, our aim was to examine the synergistic/additive cytotoxic and apoptotic effects of combination of docetaxel and ATRA, in hormone- and drug refractory human DU-145 prostate cancer cells. Furthermore, we have searched for the underlying mechanisms of apoptosis by demonstrating apoptosis-related genes.

Methods

XTT cell proliferation assay was used for showing cytotoxicity. For verifying apoptosis, both DNA Fragmentation by ELISA assay and caspase 3/7 activity measurement were used. For detecting the mechanism of apoptosis induced by docetaxel-ATRA combination, OligoGeArray^® which consists of 112 apoptosis related genes was used.

Results

Our results revealed that docetaxel and ATRA were synergistically cytotoxic and apoptotic in DU-145 cells, in a dose- and time dependent manner. It was also shown by our studies that apoptosis was induced in DU-145 prostate carcinoma cells with significant cytotoxicity, no matter which agent applied first. We have found out that docetaxel-ATRA combination significantly downregulates survivin (BIRC5), myeloid cell leukemia-1 (MCL-1) and lymphotoxin β-receptor (LTβR) genes, which all three have pivotal roles in regulation of apoptosis and cell cycle progression.

Conclusion

In conclusion, we strongly suggest that docetaxel and ATRA combination is a good candidate for this challenging era of daily oncologic practice. Also, the combination of docetaxel and ATRA might allow a reduction in docetaxel doses and by this way may diminish docetaxel adverse effects while maintaining the therapeutic effect in patients with HRPC.

Thrombospondin-1 (TSP-1) and Survivin (S) expression in non-Hogkin's lymphomas

Survivin (S) is a member of inhibitor of apoptosis family (IAP) and is expressed in the majority of malignant tumors but undetectable in normal differentiated adult tissues. S is an encouraging target for cancer therapy. TSP-1 is a multifunctional protein regulating cell growth, motility and apoptosis in both physiological and pathological conditions. The role of TSP-1 in cancer progression remains controversial. We aimed to determine the pathogenetic and prognostic role of TSP-1 and S in non-Hodgkin's lymphomas (NHL). S and TSP-1 expressions were looked for in 177 cases with NHL. S was found to be positive in 94 of the cases (53%). TSP-1 was found to be positive in 31 of the cases (17.5%). There was a strong association between S and TSP-1 and also aggressive histology with S and TSP-1. The overall survival (OS) times were longer in cases without S expression than cases with S expression (p=0.0514). Although the OS was shorter in TSP-1 expressing cases as compared with TSP-1 (-) cases, difference was not significant (p=0.2428). In conclusion, S and TSP-1 expressions were detected in 53 and 17.5% of the cases with NHL, and are associated with aggressive histology and shorter OS.

Up-regulation of c-FLIPS+R upon CD40 stimulation is associated with inhibition of CD95-induced apoptosis in primary precursor B-ALL

Previous studies on apoptosis defects in acute lymphoblastic leukemia (ALL) have focused on chemotherapy-induced, primarily mitochondrial death pathways. Yet, immunologic surveillance mechanisms including sensitization to apoptotic signals mediated via the death receptor CD95 might contribute to leukemic control. Here, we show that primary B-cell precursor ALL cells from children escape from receptor-dependent cell death in 2 ways: Resting ALL blasts are protected from receptor-mediated apoptosis due to the absence of CD95 surface expression. However, even though CD40 ligation results in up-regulation of CD95, ALL blasts, unlike normal B cells, remain resistant to apoptosis. We show that this apoptosis resistance involves the selective up-regulation of the short isoforms of the caspase-8 inhibitor c-FLIP acting directly at the CD95 receptor level. Treatment with cycloheximide during CD40 activation prevents up-regulation of those c-FLIP isoforms and sensitizes ALL cells toward CD95-mediated apoptosis. We therefore propose that induction of the short c-FLIP isoforms inhibits the onset of CD95-induced apoptosis in primary CD40-stimulated ALL cells despite high CD95 expression.

IRF-4 and c-Rel expression in antiviral-resistant adult T-cell leukemia/lymphoma

Adult T-cell leukemia/lymphoma (ATLL) is a generally fatal malignancy. Most ATLL patients fare poorly with conventional chemotherapy; however, antiviral therapy with zidovudine (AZT) and interferon alpha (IFN-alpha) has produced long-term clinical remissions. We studied primary ATLL tumors and identified molecular features linked to sensitivity and resistance to antiviral therapy. Enhanced expression of the proto-oncogene c-Rel was noted in 9 of 27 tumors. Resistant tumors exhibited c-Rel (6 of 10; 60%) more often than did sensitive variants (1 of 9; 11%). This finding was independent of the disease form. Elevated expression of the putative c-Rel target, interferon regulatory factor-4 (IRF-4), was observed in 10 (91%) of 11 nonresponders and in all tested patients with c-Rel+ tumors and occurred in the absence of the HTLV-1 oncoprotein Tax. In contrast, tumors in complete responders did not express c-Rel or IRF-4. Gene rearrangement studies demonstrated the persistence of circulating T-cell clones in long-term survivors maintained on antiviral therapy. The expression of nuclear c-Rel and IRF-4 occurs in the absence of Tax in primary ATLL and is associated with antiviral resistance. These molecular features may help guide treatment. AZT and IFN-alpha is a suppressive rather than a curative regimen, and patients in clinical remission should remain on maintenance therapy indefinitely.

Survivin and EPR-1 expression in acute leukemias: prognostic significance and review of the literature

The aim of this study is to detect the biologic and/or prognostic significance of survivin (S) and effector protease receptor 1: EPR-1 (E) expression in acute leukemias (34 ALL and 40 AML) by using RT-PCR. S and E expressions were found in 83.8 and 20.3% of the cases, respectively. S was detected in 90%, 76.5% and E was detected in 17.5%, 23.5% of the cases with AML and ALL, respectively. There was a significant correlation between S and E (r=0.30 p=0.01). Mortality rate was higher in E(-) cases than E(+) cases (83.1 % versus 66.7%) (p=0.04). The median DFS and OS rates were shorter in S(+) and E(-) cases. In subgroup analysis, there was not a significant difference for OS between S(-) and S(+) cases and E(-) and E(+) cases in ALL group. The median OS rate was significantly longer in S(-) cases than S(+) cases, and longer in E(+) cases than E(-) in AML groups (p=0.04, 0.001, respectively). OS and DFS rates were longest in S(-) E(+) cases and shortest in S(+) E(-) cases (p=0.04 and 0.03, respectively). In multivariate analyses EPR1 negativity was found to be an independent poor risk factor for survival (OR: 2.4, p=0.02). In conclusion S expression is a bad prognostic indicator in cases with acute leukemia especially in AML. S negativity and E positivity show good clinical outcome in acute leukemias. E expression is important due to its property of the possible natural anti-sense of the S.

Induction of cell death in adult T-cell leukemia cells by a novel IkappaB kinase inhibitor

NF-kappaB is constitutively activated in adult T-cell leukemia (ATL) and is considered responsible for cell growth and prevention of cell death. In this study, we demonstrate that NF-kappaB is constitutively activated in various HTLV-1-infected T-cell lines and ATL-derived cell lines irrespectively of Tax expression as evidenced by the phosphorylation of IkappaBalpha and p65 subunit of NF-kappaB, activation of NF-kappaB DNA binding, and upregulation of various target genes including bcl-xL, bcl-2, XIAP, c-IAP1, survivin, cyclinD1, ICAM-1 and VCAM-1. The effects of a novel IkappaB kinase (IKK) inhibitor, 2-amino-6-[2-(cyclopropylmethoxy)-6-hydroxyphenyl]-4-piperidin-4-yl nicotinonitrile (ACHP), were examined on cell growth of these cell lines and fresh ATL leukemic cells. We found that ACHP could inhibit the phosphorylation of IkappaBalpha and p65, as well as NF-kappaB DNA-binding, associated with downregulation of the NF-kappaB target genes and induce cell growth arrest and apoptosis in these cells. When Tax-active and Tax-inactive cell lines were compared, ACHP could preferentially inhibit cell growth of Tax-active cells. Moreover, ACHP exhibited strong apoptosis-inducing activity in fresh ATL cells. These findings indicate that ACHP and its derivatives are effective in inducing ATL cell death and thus feasible candidates for the treatment of ATL.

Overexpression of survivin in primary ATL cells and sodium arsenite induces apoptosis by down-regulating survivin expression in ATL cell lines

Patients with acute- or lymphoma-type adult T-cell leukemia (ATL) have a poor outcome because of the intrinsic drug resistance to chemotherapy. Protection from apoptosis is a common feature involved in multidrug-resistance of ATL. IAP (inhibitor of apoptosis) family proteins inhibit apoptosis induced by a variety of stimuli. In this study, we investigated the expression of IAP family members (survivin, cIAP1, cIAP2, and XIAP) in the primary leukemic cells from patients with ATL. We found that survivin was overexpressed in ATL, especially in acute-type ATL. Sodium arsenite was shown to down-regulate the expression of survivin at both the protein and RNA levels in a time- and dose-dependent manner, thus inhibiting cell growth, inducing apoptosis, and enhancing the caspase-3 activity in ATL cells. Nuclear factor-κB (NF-κB) enhances the transcriptional activity of survivin. Sodium arsenite suppressed the constitutive NF-κB activation by preventing the IκB-α degradation and the nuclear translocation of NF-κB. These findings suggest that survivin is an important antiapoptotic molecule that confers drug resistance on ATL cells. Sodium arsenite was shown to down-regulate the expression of survivin through the NF-κB pathway, thus inhibiting cell growth and promoting apoptosis of ATL cells.

Apoptotic effect of fludarabine is independent of expression of IAPs in B-cell chronic lymphocytic leukemia

Despite the efficiency of fludarabine in the induction of clinical responses in B-cell chronic lymphocytic leukemia (B-CLL) patients, resistance to this drug has been documented. The present study tested whether resistance to fludarabine is related to the expression of inhibitor of apoptosis proteins (IAPs) family members. We analyzed the expression of c-IAP1, c-IAP2 and XIAP, by immunocytochemistry, in 30 blood samples from B-CLL patients and correlated protein expression to fludarabine-induced apoptosis estimated by an annexin-V assay. Expression of c-IAP1, c-IAP2 and XIAP were found predominantly in the cytoplasm, and a wide range of staining intensities was observed among distinct samples. No correlation was found between the levels of IAPs expression and prognostic factors such as age, gender, lymphocyte doubling time, white blood cell count or previous treatment. The expression of IAPs also failed to predict the sensitivity to fludarabine-induced apoptosis. Alternative pathways of cell death may explain the independence of fludarabine-induced apoptosis from the high expression of IAPs.

Nuclear expression of the antiapoptotic protein survivin in malignant melanoma

BACKGROUND

Expression of the antiapoptotic protein survivin has been demonstrated in some melanocytic lesions and is believed to be required for melanoma cell viability. However, its diagnostic value in differentiating melanomas from nevi has not yet been examined.

METHODS

Tissue microarray blocks were constructed with paraffin-fixed tissue of 19 nevi, 18 dysplastic nevi, 24 malignant melanomas, and 31 metastatic melanomas. Sections were then reacted with three antisurvivin antibodies (two monoclonal and one polyclonal) assessing labeling intensity (absent or weak, and moderate to strong) as well as the percentage of cells labeled (< 25%, > or = 25%).

RESULTS

Of the antibodies evaluated, the polyclonal one was found to be the most sensitive. Nuclear immunoreactivity for survivin (i.e., > or = 25% of cells exhibiting and/or at least moderately intense staining) was seen in a subset of melanomas but not in nevi or dysplastic nevi (P < 0.05).

CONCLUSIONS

Survivin is variably expressed in the cytoplasm in the entire spectrum of melanocytic lesions, with nuclear expression detectable only in melanomas. These data may underscore the importance of nuclear survivin in progression to melanoma and may prove useful in the differential diagnosis of melanoma versus nevus.

The expression of 70 apoptosis genes in relation to lineage, genetic subtype, cellular drug resistance, and outcome in childhood acute lymphoblastic leukemia

Childhood acute lymphoblastic leukemia (ALL) consists of various subtypes that respond differently to cytotoxic drugs and therefore have a markedly different clinical outcome. We used microarrays to investigate, in 190 children with ALL at initial diagnosis, whether 70 key apoptosis genes were differentially expressed between leukemic subgroups defined by lineage, genetic subtype, in vitro drug resistance, and clinical outcome. The expression of 44 of 70 genes was significantly different in T-versus B-lineage ALL, 22 genes differed in hyperdiploid versus nonhyperdiploid, 16 in TEL-AML1-positive versus-negative, and 13 in E2A-rearranged versus germ-line B-lineage ALL. Expression of MCL1 and DAPK1 was significantly associated with prednisolone sensitivity, whereas BCL2L13, HRK, and TNF were related to L-asparaginase resistance. BCL2L13 overexpression was also associated with unfavorable clinical outcome (P < .001). Multivariate analysis including known risk factors revealed that BCL2L13 expression was an independent prognostic factor (P = .011). The same trend was observed in a validation group of 92 children with ALL treated on a different protocol at St Jude (P = .051). In conclusion, ALL subtypes have a unique expression pattern of apoptosis genes and our data suggest that selective genes are linked to cellular drug resistance and prognosis in childhood B-lineage ALL.

A potent immunogenic general cancer vaccine that targets survivin, an inhibitor of apoptosis proteins

We reported previously a HLA-A24-restricted antigenic peptide, survivin-2B80-88 (AYACNTSTL), recognized by CD8(+) CTL. This peptide was derived from survivin protein, an inhibitor of apoptosis proteins, expressed in a variety of tumors, such as adenocarcinoma, squamous cell carcinoma, and malignant melanoma. In this report, we provide further evidence that survivin-2B80-88 peptide might serve as a potent immunogenic cancer vaccine for various cancer patients. Overexpression of survivin was detected in surgically resected primary tumor specimens of most breast and colorectal cancers and some gastric cancers as assessed by immunohistochemical study. HLA-A24/survivin-2B80-88 tetramer analysis revealed that there existed an increased number of CTL precursors in peripheral blood mononuclear cells (PBMC) of HLA-A24(+) cancer patients, and in vitro stimulation of PBMCs from six breast cancer patients with survivin-2B80-88 peptide could lead to increases of the CTL precursor frequency. Furthermore, CTLs specific for this peptide were successfully induced from PBMCs in all 7 (100%) patients with breast cancers, 6 of 7 (83%) patients with colorectal cancers, and 4 of 7 (57%) patients with gastric cancers. These data indicate that survivin expressed in tumor tissues is antigenic in cancer patients, and survivin-2B80-88-specific CTLs are present in PBMCs of various cancer patients. Our study raises the possibility that this peptide may be applicable as a general cancer vaccine to a large proportion of HLA-A24(+) cancer patients.

Transcriptional activation of survivin through the NF-kappaB pathway by human T-cell leukemia virus type I tax

Survivin, a unique member of the inhibitor of apoptosis protein family, is overexpressed in many cancers and considered to play an important role in oncogenesis. We previously reported the survivin expression profile in ATL, a CD4-positive T-cell malignancy caused by HTLV-I. HTLV-I Tax is thought to play an important role in immortalization of T cells. We have shown also that the expression of Tax protected the mouse T-cell line CTLL-2 against apoptosis induced by deprivation of IL-2 and converted its growth from being IL-2 dependent to being IL-2 independent through the NF-kappaB pathway. In our study, we demonstrate that constitutive expression of survivin was associated with resistance to apoptosis after IL-2 deprivation in Tax-expressing CTLL-2 cells. Transient transfection assays showed that survivin promoter was transactivated by Tax, via the activation of NF-kappaB. Pharmacological NF-kappaB inhibition resulted in suppression of survivin expression and caused apoptosis of Tax-expressing CTLL-2 cells. Our findings suggest that activated NF-kappaB signaling contributes directly to malignant progression of ATL by preventing apoptosis, acting through the prosurvival protein survivin.

Immunohistochemical detection of the apoptosis-related proteins FADD, FLICE, and FLIP in Langerhans cell histiocytosis

Langerhans cell histiocytosis (LCH) is characterized by an accumulation of dendritic Langerhans cells in granulomatous lesions in various organs. The etiology of LCH remains enigmatic. Fas/APO-1/CD95 belongs to the "death receptor" family of apoptosis regulators and has been implicated in the downregulation of immune responses. The authors examined the expression of three proteins that are engaged in the Fas signaling cascade-FADD/Fas-associated death domain-containing protein, FLICE/FADD-like interleukin-1beta-converting enzyme (both pro-apoptotic), and FLIP/FLICE-inhibitory protein (anti-apoptotic)-in lesions from LCH patients. Immunohistochemistry was performed on paraffin-embedded tissue specimens from 43 children with LCH. The infiltrates were scored according to the amount of positive pathologic Langerhans cells (pLCs). In all investigated specimens, the majority of the pLCs expressed FADD, active FLICE, and FLIP. The clinical outcome of the disease could not be correlated to the expression of the investigated proteins. This study shows a high expression of the apoptosis-related proteins FADD, active FLICE, and FLIP in pLCs. The authors previously showed that pLCs express Fas and Fas ligand. Taken together, these findings suggest that the Fas signaling pathway may be involved in the pathogenesis of LCH.

A novel plasmacytoid dendritic cell line, CAL-1, established from a patient with blastic natural killer cell lymphoma

Blastic natural killer (NK) cell lymphoma corresponding to CD4+CD56+ malignancies is a novel disease entity, according to the results of clinical, morphologic, and immunologic studies. It is especially noteworthy that this disease likely arises from plasmacytoid dendritic cells (pDCs), described previously as plasmacytoid T-cells, which have an important role in innate and adaptive immunity. However, the exact relationship between the tumor cells and pDCs remains to be elucidated. We encountered a patient with typical blastic NK cell lymphoma, which later converted to leukemic manifestations, and tried to establish a cell line using the leukemic cells. We succeeded in establishment of a novel cell line, CAL-1, which originated from the primary malignant cells. The genetic and phenotypic features of CAL-1 cells bear a similarity to those of pDCs, namely, plasmacytoid morphology at light and electron microscopy; negative results for CD11c and lineage-associated markers of CD3, CD14, CD19, and CD16; positive results for HLA-DR, CD4, CD56, CD45RA, and CD123; and negative results for TCR and IgH gene rearrangements. An interesting finding was that CAL-1 cells change morphologically into the mature DC appearance with many long dendrites after short-term culture in the presence of granulocyte-macrophage colony-stimulating factor and interleukin 3. CAL-1 cells can secrete tumor necrosis factor alpha but not interferon alpha. Thus although they do not share in part phenotypic and functional features with their normal counterparts, CAL-1 cells mostly exhibit a striking pDC phenotype. We describe the first novel pDC cell line of CAL-1. This cell line should open the opportunity for study not only of CD4+CD56+ tumor cells but also of pDCs in vitro.

Current views in HTLV-I-associated adult T-cell leukemia/lymphoma

Epidemiological studies have demonstrated that the relative percentage of malignant lymphoid proliferations varies widely according to geographical location and ethnic populations. HTLV-I is the etiological agent of adult T-cell leukemia/lymphoma (ATLL) and is also associated with cutaneous T-cell lymphoma (CTCL). However, a definite role of HTLV-I in mycosis fungoides (MF) and/or Sezary syndrome (SS) remains controversial. While most HTLV-I-infected individuals remain asymptomatic carriers, 1-5% will develop ATLL, an invariably fatal expansion of virus-infected CD4+ T cells. This low incidence and the long latency period preceding occurrence of the disease suggest that additional factors are involved in development of ATLL. In this review, diagnosis, clinical features, and molecular pathogenesis of HTLV-I are discussed.

Prognostic significance and different properties of survivin splicing variants in gastric cancer

Survivin, a novel antiapoptosis gene, was identified as a member of the inhibitor of apoptosis protein (IAP) family. Unique among IAP, survivin has been found to be abundantly expressed in a wide variety of human malignancies, whereas it is undetectable in normal adult tissues. Recently, three splicing variants of survivin have been further characterized with different subcellular localization, but their different functions in carcinogenesis are largely unknown. We used real time quantitative RT-PCR to analyse survivin variants' mRNA expression levels in 77 gastric carcinoma cases whose frozen samples were available. All the cases and seven cell lines tested expressed wild-type survivin mRNA, which was not only the dominant transcript, but also was a poor prognostic biomarker (P = 0.003). Non-antiapoptosis survivin-2B mRNA was negatively correlated with tumor stage (P = 0.001) histological type (P = 0.007) and depth of tumor invasion (P = 0.031) while survivin-DeltaEx3 mRNA showed a significant reverse association with apoptosis ( P = 0.019). These data demonstrated that survivin mRNA expression levels are of important prognostic value, suggesting the significant participation of survivin-2B and survivin-DeltaEx3 in gastric cancer development.

Balance between survivin, a key member of the apoptosis inhibitor family, and its specific antibodies determines erosivity in rheumatoid arthritis

Rheumatoid arthritis (RA) is a highly heterogeneous disease with respect to its joint destructivity. The reasons underlying this heterogeneity are unknown. Deficient apoptosis in rheumatoid synovial tissue has been recently demonstrated. We have therefore decided to study the synovial expression of survivin, a key member of the apoptosis inhibitor family. The levels of survivin and antibodies against survivin were assessed by an ELISA in matched blood and synovial fluid samples collected from 131 RA patients. Results were related to joint erosivity at the time of sampling. Monocytes were transfected with survivin anti-sense oligonucleotides and were assessed for their ability to produce inflammatory cytokines. Survivin levels were significantly higher in patients with destructive disease as compared with in RA patients displaying a non-erosive disease. High survivin levels were an independent prognostic parameter for erosive RA. In contrast, high levels of antibodies against survivin were found in patients with non-erosive RA, and were negatively related to erosivity. Survivin levels in RA patients were influenced by treatment, being significantly lower among patients treated with disease-modifying anti-rheumatic drugs. Specific suppression of survivin mRNA resulted in downregulation of IL-6 production. We conclude that survivin determines the erosive course of RA, whereas survivin antibodies lead to a less aggressive course of the disease. These findings together with decreased survivin levels upon disease-modifying anti-rheumatic drug treatment, and the downregulation of inflammatory response using survivin anti-sense oligonucleotides, suggest that extracellular survivin expression mediates the erosive course of joint disease whereas autoimmune responses to the same molecule, manifested as survivin targeting antibodies, mediate protection.