Treatment of acute promyelocytic leukemia: strategy toward further increase of cure rate

Vacuolin-1 enhances RA-induced differentiation of human myeloblastic leukemia cells: evidence for involvement of a CD11b/FAK/LYN/SLP-76 axis subject to endosomal regulation that drives late differentiation steps

BACKGROUND

Retinoic acid(RA), an embryonic morphogen, regulates cell differentiation. Endocytosis regulates receptor signaling that governs such RA-directed cellular processes. Vacuolin-1 is a small molecule that disrupts endocytosis, motivating interest in its effect on RA-induced differentiation/arrest. In HL-60 myeloblastic-leukemia cells, RA causes differentiation evidenced by a progression of cell-surface and functional markers, CD38, CD11b, and finally reactive oxygen species(ROS) production and G1/0 cell cycle arrest in mature cells.

RESULTS

We found that Vacuolin-1 enhanced RA-induced CD11b, ROS and G1/0 arrest, albeit not CD38. Enhanced CD11b expression was associated with enhanced activation of Focal Adhesion Kinase(FAK). Adding vacuolin-1 enhanced RA-induced tyrosine phosphorylation of FAK, Src Family Kinases(SFKs), and the adaptor protein, SLP-76, expression of which is known to drive RA-induced differentiation. Depleting CD11b cripples late stages of progressive myeloid differentiation, namely G1/0 arrest and inducible ROS production, but not expression of CD38. Loss of NUMB, a protein that supports early endosome maturation, affected RA-induced ROS and G1/0 arrest, but not CD38 expression.

CONCLUSION

Hence there appears to be a novel CD11b/FAK/LYN/SLP-76 axis subject to endosome regulation which contributes to later stages of RA-induced differentiation. The effects of vacuolin-1 thus suggest a model where RA-induced differentiation consists of progressive stages driven by expression of sequentially-induced receptors.

ZNF117 regulates glioblastoma stem cell differentiation towards oligodendroglial lineage

Glioblastoma (GBM) is a deadly disease without effective treatment. Because glioblastoma stem cells (GSCs) contribute to tumor resistance and recurrence, improved treatment of GBM can be achieved by eliminating GSCs through inducing their differentiation. Prior efforts have been focused on studying GSC differentiation towards the astroglial lineage. However, regulation of GSC differentiation towards the neuronal and oligodendroglial lineages is largely unknown. To identify genes that control GSC differentiation to all three lineages, we performed an image-based genome-wide RNAi screen, in combination with single-cell RNA sequencing, and identified ZNF117 as a major regulator of GSC differentiation. Using patient-derived GSC cultures, we show that ZNF117 controls GSC differentiation towards the oligodendroglial lineage via the Notch pathway. We demonstrate that ZNF117 is a promising target for GSC differentiation therapy through targeted delivery of CRISPR/Cas9 gene-editing nanoparticles. Our study suggests a direction to improve GBM treatment through differentiation of GSCs towards various lineages.

Phytol Down-Regulates Expression of Some Cancer Stem Cell Markers and Decreases Side Population Proportion in Human Embryonic Carcinoma NCCIT Cells

Cancer stem cells (CSCs), a subgroup of cancer cells, have self-renewal capacity and differentiation potential and drive tumor growth. CSCs are highly-resistant to conventional chemo-radio therapy. Phytochemicals were shown to be able to eliminate CSCs. Phytol is a diterpene alcohol with demonstrated anticancer effects. The current study compared the effect of phytol with retinoic acid (RA) as a well-known inducers of CSC differentiation and cisplatin, a common chemotherapy drug, on CSC markers in human embryonic carcinoma NCCIT cells. NCCIT cells were exposed to 10 mM RA for 14 day to induce differentiation. Moreover, NCCIT cells were treated with IC₅₀ dose of cisplatin (12 µM) and phytol (40 µM) for 7 day. Real-time PCR showed that phytol was more effective that RA and cisplatin in down-regulating the CSC markers OCT4, NANOG, SOX2, ALDH1, ABCB1, CD44 and CD133. Percentage of SP (13%) and ABCB1⁺ (0.34%) in NCCIT cells decreased to 7% and 0.1% respectively after treatment with phytol. A very small proportion of NCCIT cells were positive for CD44 (0.2%) and CD133 (0.48%) and this fraction did not change significantly after treatment with three agents. In conclusion, phytol has the greatest inhibitory effect on CSC population and markers than RA and cisplatin.

Regulation of N6-Methyladenosine in the Differentiation of Cancer Stem Cells and Their Fate

N6-methyladenosine (m6A) is one of the most common internal RNA modifications in eukaryotes. It is a dynamic and reversible process that requires an orchestrated participation of methyltransferase, demethylase, and methylated binding protein. m6A modification can affect RNA degradation, translation, and microRNA processing. m6A plays an important role in the regulation of various processes in living organisms. In addition to being involved in normal physiological processes such as sperm development, immunity, fat differentiation, cell development, and differentiation, it is also involved in tumor progression and stem cell differentiation. Curiously enough, cancer stem cells, a rare group of cells present in malignant tumors, retain the characteristics of stem cells and play an important role in the survival, proliferation, metastasis, and recurrence of cancers. Recently, studies demonstrated that m6A participates in the self-renewal and pluripotent regulation of these stem cells. However, considering that multiple targets of m6A are involved in different physiological processes, the exact role of m6A in cancer progression remains controversial. This article focuses on the mechanism of m6A and its effects on the differentiation of cancer stem cells, to provide a basis for elucidating the tumorigenesis mechanisms and exploring new potential therapeutic approaches.

Identification and characterization of a phenyl-thiazolyl-benzoic acid derivative as a novel RAR/RXR agonist

Objective

To identify an agonist of RXRα and RARα with reduced undesired profiles of all-trans retinoic acid for differentiation-inducing therapy of acute promyelocytic leukemia (APL), such as its susceptibility to P450 enzyme, induction of P450 enzyme, increased sequestration by cellular retinoic acid binding protein and increased expression of P-glycoprotein, a virtual screening was performed.

Results and conclusion

In this study, a phenyl-thiazolyl-benzoic acid derivative (PTB) was identified as a potent agonist of RXRα and RARα. PTB was characterized in nuclear receptor binding, reporter gene, cell differentiation and cell growth assays. PTB bound directly to RXRα and RARα, but not to PPARα, δ(β) or γ. PTB fully activated reporter genes with enhancer elements for RXRα/RXRα, and partially activated reporter genes with enhancer elements for RARα/RXRα, PPARδ(β) and PPARγ. Furthermore, PTB induced differentiation and inhibited the growth of human APL cells. Thus, PTB is a novel dual agonist of RXRα and RARα and works as both a differentiation inducer and a proliferation inhibitor to leukemic cells.

Therapeutic targeting of gastrointestinal cancer stem cells

Gastrointestinal cancers remain a tremendous burden on society. Despite advances in therapy options, including chemotherapy and radiation, cancer mortality from recurrences and metastases occur frequently. Cancer stem cells (CSCs) drive disease recurrence and metastasis, as these cells are uniquely equipped to self-renew and evade therapy. Therefore, cancer eradication requires treatment strategies that target CSCs in addition to differentiated cancer cells. This review highlights current literature on therapies targeting CSCs in gastrointestinal cancer.

Simultaneous determination of AM80 (tamibarotene) and WJD-A-1 in rat plasma by ultra high-performance liquid chromatography-tandem mass spectrometry and its application to a pharmacokinetic study

A compound (WJD-A-1) was previously reported as a candidate prodrug of Am80 (tamibarotene), which was approved in Japan in 2005 as a therapeutic agent for recurrent refractory acute promyelocytic leukaemia. A rapid, selective and sensitive ultra high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed for the first time to simultaneously determine WJD-A-1 and its major phase-I metabolites AM80 in rat plasma. After a simple sample preparation procedure by protein precipitation with methanol and acetonitrile, WJD-A-1, AM80 and the internal standard were chromatographed on an ACQUITY UPLC^TM BEH C₁₈ column. The mobile phase consisted of methanol-0.1% formic acid (80:20, v/v) and the flow rate was 0.20 mL/min. The detection was performed on a triple quadrupole tandem mass spectrometer by multiple reaction monitoring (MRM) mode via electrospray ionization (ESI) source. Each plasma sample was chromatographed within 2.6 min. The linear calibration curves for WJD-A-1 and the AM80 were obtained in the concentration range of 5.40-5.40 × 10³ and 5.08-5.08 × 10³ ng/mL, respectively (r ≥ 0.99). The intra- and inter-day precision (relative standard deviation, RSD) values were less than 8% and the accuracy (relative error, RE) was within ±6.8%, determined from quality control (QC) samples for the analytes. The method herein described was fully validated and successfully applied to pharmacokinetic study of WJD-A-1 following an intravenous administration of 300 μg/kg WJD-A-1 to rats.

Use of Cellular and Plasma Apheresis in the Critically Ill Patient: Part II: Clinical Indications and Applications

Apheresis is the process of separating the blood and removing or manipulating a cellular or plasma component for therapeutic benefit. Such procedures may be indicated in the critical care setting as primary or adjunctive therapy for certain hematologic, neurologic, renal, and autoimmune/rheumatologic disorders. In part I of this series, the technical aspects of apheresis were described and the physiologic rationale and clinical considerations were discussed. This review highlights the pathophysiologic basis, specific clinical indications, and treatment parameters for disorders that more commonly require management in the intensive care unit. The choice of plasma or cellular apheresis in these cases is guided by wellaccepted, evidence-based clinical treatment guidelines. For some disorders, such as liver failure, severe sepsis, and multiple-organ dysfunction syndrome, apheresis treatment approaches remain experimental. Ongoing studies are investigating the potential utility of conventional plasma exchange, ex vivo plasma manipulation, and newer technologies for these and other disorders in severely ill patients.

Acute myeloid leukemia in children: Current status and future directions

Acute myeloid leukemia (AML) accounts for 25% of pediatric leukemia and affects approximately 180 patients annually in Japan. The treatment outcome for pediatric AML has improved through advances in chemotherapy, hematopoietic stem cell transplantation (HSCT), supportive care, and optimal risk stratification. Currently, clinical pediatric AML studies are conducted separately according to the AML subtypes: de novo AML, acute promyelocytic leukemia (APL), and myeloid leukemia with Down syndrome (ML-DS). Children with de novo AML are treated mainly with anthracyclines and cytarabine, in some cases with HSCT, and the overall survival (OS) rate now approaches 70%. Children with APL are treated with an all-trans retinoic acid (ATRA)-combined regimen with an 80-90% OS. Children with ML-DS are treated with a less intensive regimen compared with non-DS patients, and the OS is approximately 80%. HSCT in first remission is restricted to children with high-risk de novo AML only. To further improve outcomes, it will be necessary to combine more accurate risk stratification strategies using molecular genetic analysis with assessment of minimum residual disease, and the introduction of new drugs in international collaborative clinical trials.

Refractory acute promyelocytic leukemia successfully treated with combination therapy of arsenic trioxide and tamibarotene: A case report

A 40-year-old male developed refractory acute promyelocytic leukemia (APL) after various treatments including all-trans retinoic acid, tamibarotene, arsenic trioxide (As₂O₃), conventional chemotherapy, and autologous peripheral blood stem cell transplantation. We attempted to use both tamibarotene and As₂O₃ as a combination therapy, and he achieved molecular complete remission. Grade 2 prolongation of the QTc interval on the electrocardiogram was observed during the therapy. The combination therapy of As₂O₃ and tamibarotene may be effective and tolerable for treating refractory APL cases who have no treatment options, even when they have previously been treated with tamibarotene and As₂O₃as a single agent.

New nanoplatforms based on upconversion nanoparticles and single-walled carbon nanohorns for sensitive detection of acute promyelocytic leukemia

New nanoplatforms were prepared by using upconversion nanoparticles as energy donor and single-walled carbon nanohorns as energy acceptor.

Persistent Hypoplastic Acute Promyelocytic Leukemia with a Novel Chromosomal Abnormality of 46, XY, t(15;17), t(9;11)(q13;p13)

A diagnosis of acute promyelocytic leukemia (APL) is usually made when normal hematopoietic cells are substituted by APL cells. We encountered a unique APL patient who presented with persistent hypoplastic features of APL. An 84-year-old man presented with leukopenia (2.2 × 10(9)/L) and anemia (Hb 12.5 g/dL). Five months later, the bone marrow (BM) was hypoplastic with a normal proportion of blasts and promyelocytes (5.2%), although the latter cells were hypergranular. The karyotype of BM cells was 46, XY, t(15;17)(q22;q12), t(9;11)(q13;p13). Two months later, the BM remained hypoplastic with 8.5% hypergranular promyelocytes, some of which contained faggot of Auer rods. RT-PCR examination yielded the PML-RARα transcript, and its sequencing revealed the breakpoint of PML to be bcr2. The patient was treated with all-trans retinoic acid under a diagnosis of APL with improvement of the bicytopenia. FISH analysis of BM cells yielded a negative result regarding t(15;17), although RT-PCR was positive for PML-RARα mRNA. Six months later, APL recurred with the same karyotypic abnormalities and therapeutic resistance, and the patient died of pneumonia. A persistent hypoplastic state of APL may be a rare event, and the association of t(15;17) and t(9;11) is novel.

Induction, consolidation, and maintenance therapies with arsenic as a single agent for acute promyelocytic leukaemia in a 11-year follow-up

The aim of this study was to evaluate the effect of arsenic trioxide as a single agent in acute promyelocytic leukaemia cases for induction, consolidation, and maintenance therapy in a long-term, 11-year follow-up. We studied 60 patients with acute promyelocytic leukaemia. Sixty percent of the patients were aged between 12 and 24 years. Arsenic trioxide was infused at a 0.15 mg/kg daily dose until complete remission was achieved. After 2 weeks of rest, arsenic trioxide was infused daily for 28 days as a consolidation therapy. Then, arsenic infusions were given every 3-4 months for 14 days for 2 years, and the patients were followed until relapse or death. The rates of complete remission, disease-free survival, overall survival, and drug toxicity were evaluated. The morphologic complete remission was observed in 55 out of the 60 patients. The most common causes of a remission failure were early mortality because of the APL differentiation syndrome and the lack of response to arsenic treatment. The mean follow-up was 90 months. The primary outcomes for males and females were a mean disease-free survival of 101 and 97 months, respectively, and a mean overall survival of 103 and 101 months, respectively. From the 55 cases with remission, three patients died (late mortality). Of the 60 patients, 85% are still alive. Arsenic trioxide was generally well tolerated. The long-term follow-up of patients with APL, treated with arsenic alone as induction, consolidation, and maintenance therapy, shows high cure rates and excellent outcomes. Copyright © 2015 John Wiley & Sons, Ltd.

Cyanidin induces apoptosis and differentiation in prostate cancer cells

Several natural antioxidants, including anthocyanins, have been reported to have chemotherapeutic activity in vivo and in vitro. The aim of the present study was to delineate the anti-proliferative activity and the cytodifferentiation properties mediated by cyanidin-3-O-β-glucopyranoside (C3G) treatment in the DU145 and LnCap human prostatic cancer cell lines. C3G produced anti-proliferative effects through activation of caspase-3 and induction of p21 protein expression. The reduced cell viability was associated with a clear increase of DNA fragmentation in both cell lines after C3G treatment. Since LnCap and DU145 exhibited differences in sensitivity to C3G treatment, the redox state of these cells was further investigated by estimating the levels of ROS and GSH. C3G antioxidant activity was confirmed only in DU145 cell line. Treatment with C3G increased the levels of tumor suppressor P75NGFR, indicating a possible role of C3G in the acquisition of a normal-like cell phenotype. Results reported in the present study demonstrate that C3G, the most abundant anthocyanin in diet, may represent a new approach and highly effective strategy in reducing carcinogenesis. C3G may be considered a new therapeutic agent with both anti-proliferative and pro-differentiation properties.

Acute promyelocytic leukemia harbouring rare FLT3-TKD and WT1 mutations: A case report

The involvement of the central nervous system (CNS) is rare in acute promyelocytic leukemia (APL). The present study reported the case of a 34-year-old male patient with APL that possessed a rare point mutation (p.Asn841Gly, c.2523C>A) in the tyrosine kinase domain of the FMS-like tyrosine kinase 3 (FLT3) gene and a novel Wilm tumor gene mutation (c.1209_1210insT/p.K404X). The patient suffered central nervous system and systemic relapses twice during systemic and intrathecal chemotherapy. At present, the patient is undergoing alternative induction and consolidation therapies, including the administration of FLT3 inhibitor, tetraarsenic tetrasulfide and novel cytotherapy, and is prepared for salvage allogeneic hematopoietic stem cell transplantion (allo-HSCT). The present study indicated that patients with APL that are at a high risk of relapse and unfavorable gene mutations should receive immediate allo-HSCT, whenever possible.

CPEB1 modulates differentiation of glioma stem cells via downregulation of HES1 and SIRT1 expression

Glioma stemness has been recognized as the most important reason for glioma relapse and drug resistance. Differentiation of glioma stem cells (GSCs) has been implicated as a novel approach to target recurrent glioma. However, the detailed molecular mechanism involved in the differentiation of GSCs has not yet been elucidated. This study identified CPEB1 as the key modulator that induces the differentiation of GSCs at the post-transcriptional level. Gain and loss of function experiments showed that CPEB1 expression reduced sphere formation ability and the expression of stemness markers such as Nestin and Notch. To elucidate the detailed molecular mechanism underlying the action of CPEB1, we investigated the interacting ribonome of the CPEB1 complex using a Ribonomics approach. CPEB1 specifically suppressed the translation of HES1 and SIRT1 by interacting with a cytoplasmic polyadenylation element. The expression profile of CPEB1 negatively correlated with overall survival in glioma patients. Overexpression of CPEB1 decreased the number of GSCs in an orthotopically implanted glioma animal model. These results suggest that CPEB1-mediated translational control is essential for the differentiation of GSCs and provides novel therapeutic concepts for differentiation therapy.

[Involvement of oxidative stress in embelin-induced cell death in leukemia HL-60 cells]

OBJECTIVE

To evaluate the effects of Embelin on HL-60 cells by the impact of oxidative stress on DNA double-strain breaks (DSBs).

METHODS

HL-60 cells were treated with Embelin in different concentration (3, 10, 30, 100, and 300 μg/ml) for 24 h, and inhibitory effects was examined by CCK-8 assay. Reactive oxygen species (ROS) levels were evaluated by flow cytometry using DCFH-DA. Comet assay was used to detect the extent of DSBs.

RESULTS

Embelin inhibited proliferation of HL-60 cells in a dose-dependent manner. At the concentration of 10, 30, 100, and 300 μg/ml, the inhibition rate was (12.74 ± 2.27)%, (23.49 ± 1.96)%, (30.30±1.89)%, and (57.55 ± 3.59)% (P<0.05). Embelin also lead to high level of intracellular ROS and deterioration of DNA damage (P<0.05). When HL-60 cells were pretreated with ROS scavenger N-acetyl-l-cysteine (NAC) for 2 h and then treated with 300 μg/ml Embelin for 24 h, the intracellular ROS level declined and DSBs relieved (P<0.05). Meanwhile, embelin-induced cell viability significantly declined to (32.75 ± 2.70)% (P<0.05).

CONCLUSION

Embelin induced the death of HL-60 cells by increasing the generation of intracellular oxidation and the oxidative stress, which drived the damage of DNA double-strand.

De-differentiation confers multidrug resistance via noncanonical PERK-Nrf2 signaling

Upregulation of PERK-Nrf2 signaling is a key mechanism by which de-differentiated cancer cells gain multi-drug resistance.

Malignant carcinomas that recur following therapy are typically de-differentiated and multidrug resistant (MDR). De-differentiated cancer cells acquire MDR by up-regulating reactive oxygen species (ROS)–scavenging enzymes and drug efflux pumps, but how these genes are up-regulated in response to de-differentiation is not known. Here, we examine this question by using global transcriptional profiling to identify ROS-induced genes that are already up-regulated in de-differentiated cells, even in the absence of oxidative damage. Using this approach, we found that the Nrf2 transcription factor, which is the master regulator of cellular responses to oxidative stress, is preactivated in de-differentiated cells. In de-differentiated cells, Nrf2 is not activated by oxidation but rather through a noncanonical mechanism involving its phosphorylation by the ER membrane kinase PERK. In contrast, differentiated cells require oxidative damage to activate Nrf2. Constitutive PERK-Nrf2 signaling protects de-differentiated cells from chemotherapy by reducing ROS levels and increasing drug efflux. These findings are validated in therapy-resistant basal breast cancer cell lines and animal models, where inhibition of the PERK-Nrf2 signaling axis reversed the MDR of de-differentiated cancer cells. Additionally, analysis of patient tumor datasets showed that a PERK pathway signature correlates strongly with chemotherapy resistance, tumor grade, and overall survival. Collectively, these results indicate that de-differentiated cells up-regulate MDR genes via PERK-Nrf2 signaling and suggest that targeting this pathway could sensitize drug-resistant cells to chemotherapy.

The development of multidrug resistance is the primary obstacle to treating cancers. High-grade tumors that are less differentiated typically respond poorly to therapy and carry a much worse prognosis than well-differentiated low-grade tumors. Therapy-resistant cancer cells often overexpress antioxidants or efflux proteins that pump drugs out of the cell, but how the differentiation state of cancer cells influences these resistance mechanisms is not well understood. Here we used genome-scale approaches and found that the PERK kinase and its downstream target, Nrf2—a master transcriptional regulator of the cellular antioxidant response—are key mediators of therapy resistance in poorly differentiated breast cancer cells. We show that Nrf2 is activated when cancer cells de-differentiate and that this activation requires PERK. We further show that blocking PERK-Nrf2 signaling with a small-molecule inhibitor sensitizes drug-resistant cancer cells to chemotherapy. Our results identify a novel role for PERK-Nrf2 signaling in multidrug resistance and suggest that targeting this pathway could improve the responsiveness of otherwise resistant tumors to chemotherapy.

Implications of stemness-related signaling pathways in breast cancer response to therapy

There is accumulating evidence that breast cancer may arise from a small subpopulation of transformed mammary stem/progenitor cells, termed breast cancer-initiating cells (BCICs), responsible for initiation and maintenance of cancer. BCICs have been identified in clinical specimens based on CD44(+)/CD24(-/low) membrane expression and/or enzymatic activity of aldehyde dehydrogenase 1 (ALDH1+), or isolated and in vitro propagated as non-adherent spheres. This cell population has been demonstrated to be able to recreate, when injected in mice even at very low concentrations, the same histopathological features of the tumor they were derived from and to escape from current therapeutic strategies. Alterations in genes involved in stemness-related pathways, such as Wnt, Notch, and Sonic Hedgehog, have been proven to play a role in breast cancer progression. Targeting these key elements represents an attractive option, with a solid rationale, although possible concerns may derive from the poor knowledge of tolerance and efficacy of inhibiting these mechanisms without inducing severe side effects. In addition, efforts to develop alternative BCIC-targeted therapies against stemness markers (CD44 and ALDH1) and molecules involved in regulating EMT- and HER2-related pathways, or able to reverse the multi-drug resistance phenotype, or to induce differentiation and to control cell survival pathways are currently ongoing and encouraging results from pre-clinical studies have already been obtained using in vitro and in vivo models.

Hepatocellular Carcinoma: Basic and Transitional Research

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related deaths worldwide. The outcome of HCC therapy depends on the stage of HCC. Early-stage HCC patients can be cured with radical treatment approaches, whereas no standard treatment regimens can be recommended for patients with advanced disease.

SUMMARY

In-depth basic research into the molecular mechanisms of HCC has contributed to the development of novel therapeutic agents. This article reviews several key classes of novel therapeutic agents that are under development, including molecular-targeted therapies, cancer stem cell (CSC)-based therapy and differentiation therapy.

KEY MESSAGE

A greater understanding of the molecular pathogenesis of HCC has contributed to the development of novel therapeutic agents. This article reviews several key classes of novel therapeutic agents that are under development, including molecular-targeted therapies, CSC-based therapy and differentiation therapy.

PRACTICAL IMPLICATIONS

Molecular-targeted therapies based on signaling pathways involved in hepatocarcinogenesis and progression are being evaluated in several clinical trials. There are three main categories of targeted agents: tyrosine kinase inhibitors (TKIs), monoclonal antibodies and enzyme inhibitors. The best-established agent is sorafenib, a non-specific TKI that is accepted as first-line therapy for specific patients. Other similar agents under investigation include erlotinib, linifanib and brivanib. CSC-based therapies are still in the earlier stages of development and include a neutralizing anti-CD44 antibody, small interfering RNA to suppress epithelial cell adhesion molecular levels, a neutralizing anti-CD13 antibody and a CD13 inhibitor. An important point is that CSC-targeted therapy should be combined with conventional therapies to achieve complete tumor regression. Differentiation therapy is defined as a strategy that induces malignant reversion of tumor cells. Hepatocyte nuclear factor 4α or 1α, important transcriptional factors for hepatocyte differentiation and phenotype maintenance, have shown significant antitumor effects by inducing differentiation of both non-CSCs and CSCs in HCC towards a hepatocyte-like phenotype.

Thrombomodulin alfa treatment in patients with acute promyelocytic leukemia and disseminated intravascular coagulation: a retrospective analysis of an open-label, multicenter, post-marketing surveillance study cohort

INTRODUCTION

Patients with acute promyelocytic leukemia (APL) can develop disseminated intravascular coagulation (DIC) that results in life-threatening hemorrhagic complications. Studies regarding the safety and efficacy of thrombomodulin alfa (TM-α; recombinant human soluble thrombomodulin) in patients with APL and DIC are limited.

MATERIALS AND METHODS

A retrospective evaluation was performed on a cohort of 172 patients with APL from an open-label, multicenter, post-marketing surveillance study of TM-α.

RESULTS

Of the 172 patients, 31 were relapse/refractory APL patients, and 141 were newly diagnosed APL patients. Within the first 30 days, 24 patients (14.0%) died, and six of those deaths (3.5%) were due to hemorrhage. In total, 12 patients (7.0%) had severe hemorrhagic complications. Both the early death rate due to hemorrhage as well as the severe hemorrhage rate did not exceed those in some recent population-based studies of patients with APL. Forty-nine patients received TM-α prior to the initiation of antileukemic treatment, and one patient experienced hemorrhagic early death (ED), suggesting that early TM-α treatment appeared to result in a reduction in the hemorrhagic ED rate. Moreover, TM-α improved coagulopathy regardless of concomitant all-trans retinoic acid treatment.

CONCLUSIONS

This study confirmed the safety and efficacy of TM-α in daily clinical practice for patients with APL and DIC. TM-α appeared to reduce hemorrhagic early deaths due to DIC in patients with APL who were receiving antileukemic treatment.

p53: the barrier to cancer stem cell formation

The role of p53 as the "guardian of the genome" in differentiated somatic cells, triggering various biological processes, is well established. Recent studies in the stem cell field have highlighted a profound role of p53 in stem cell biology as well. These studies, combined with basic data obtained 20 years ago, provide insight into how p53 governs the quantity and quality of various stem cells, ensuring a sufficient repertoire of normal stem cells to enable proper development, tissue regeneration and a cancer free life. In this review we address the role of p53 in genomically stable embryonic stem cells, a unique predisposed cancer stem cell model and adult stem cells, its role in the generation of induced pluripotent stem cells, as well as its role as the barrier to cancer stem cell formation.

How I treat children and adolescents with acute promyelocytic leukaemia

Acute promyelocytic leukaemia (APL) is a rare subtype of acute myeloid leukaemia. The outcome of paediatric APL has improved substantially over the past 20 years; cure rates above 80% are expected when all-trans retinoic acid (ATRA) is given with anthracycline-based regimens. The presenting features of paediatric APL may include severe bleeding and thrombotic complications, which contribute to the high early death rate. The incidence of leucocytosis and the microgranular subtype is greater in paediatric than adult APL, and children experience greater ATRA-related toxicity. It is crucial to begin ATRA therapy and intensive platelet and fibrinogen replacement on first suspicion of APL. Recent risk-adapted therapeutic trials have shown that patients at greater risk of relapse benefit from the introduction of high-dose cytarabine during consolidation. Combination therapy with ATRA and arsenic trioxide provides very effective frontline treatment and may reduce the need for subsequent anthracycline therapy.

Gastric cancer stem cells: therapeutic targets

During the past decade, a growing body of evidence has implied that cancer stem cells (CSCs) play an important role in the development of gastric cancer (GC). The notion that CSCs give rise to GC and may be responsible for invasion, metastasis, and resistance to treatment has profound implications for anti-cancer therapy. Recent major advances in the rapidly evolving field of CSCs have opened novel exciting opportunities for developing CSC-targeted therapies. Discovery of specific markers and signaling pathways in gastric CSCs (GCSCs), with the perfecting of technologies for identification, isolation, and validation of CSCs, may provide the basis for a revolutionary cancer treatment approach based on the eradication of GCSCs. Emerging therapeutic tools based on specific properties and functions of CSCs, including activation of self-renewal signaling pathways, differences in gene expression profiles, and increased activity of telomerase or chemoresistance mechanisms, are developing in parallel with advances in nanotechnology and bioengineering. The addition of GCSC-targeted therapies to current oncological protocols and their complementary application may be the key to successfully fighting GC.

Innate immune control of EBV-infected B cells by invariant natural killer T cells

Individuals with X-linked lymphoproliferative disease lack invariant natural killer T (iNKT) cells and are exquisitely susceptible to Epstein-Barr virus (EBV) infection. To determine whether iNKT cells recognize or regulate EBV, resting B cells were infected with EBV in the presence or absence of iNKT cells. The depletion of iNKT cells increased both viral titers and the frequency of EBV-infected B cells. However, EBV-infected B cells rapidly lost expression of the iNKT cell receptor ligand CD1d, abrogating iNKT cell recognition. To determine whether induced CD1d expression could restore iNKT recognition in EBV-infected cells, lymphoblastoid cell lines (LCL) were treated with AM580, a synthetic retinoic acid receptor-α agonist that upregulates CD1d expression via the nuclear protein, lymphoid enhancer-binding factor 1 (LEF-1). AM580 significantly reduced LEF-1 association at the CD1d promoter region, induced CD1d expression on LCL, and restored iNKT recognition of LCL. CD1d-expressing LCL elicited interferon γ secretion and cytotoxicity by iNKT cells even in the absence of exogenous antigen, suggesting an endogenous iNKT antigen is expressed during EBV infection. These data indicate that iNKT cells may be important for early, innate control of B cell infection by EBV and that downregulation of CD1d may allow EBV to circumvent iNKT cell-mediated immune recognition.

Update on optimal management of acute myeloid leukemia

Acute myeloid leukemia (AML) represents a malignant accumulation of immature myeloid cells in the marrow, presenting with impaired hematopoiesis and its attendant complications, including bleeding, infection, and organ infiltration. Chromosomal abnormalities remain the most powerful predictors of AML prognosis and help to identify a subgroup with favorable prognosis. However, the majority of AML patients who are not in the favorable category succumb to the disease. Therefore, better efforts to identify those patients who may benefit from more aggressive and investigational therapeutic approaches are needed. Newer molecular markers aim at better characterizing the large group of intermediate-risk patients and to identify newer targets for therapy. A group that has seen little improvement over the years is the older AML group, usually defined as age ≥ 60. Efforts to develop less intensive but equally efficacious therapy for this vulnerable population are underway.

Efficacy and resistance of gemtuzumab ozogamicin for acute myeloid leukemia

Seventy to 80 % of patients with acute myeloid leukemia (AML) achieve complete remission following intensive chemotherapy, but more than 50 % of patients in remission subsequently relapse, which is often associated with clinical drug resistance. Therapy based on monoclonal antibodies (mAbs) has been developed to increase the selectivity of cytotoxic agents by conjugating them with a mAb. Gemtuzumab ozogamicin (GO) is a conjugate of a cytotoxic agent, a calicheamicin derivative, linked to a recombinant humanized mAb directed against the CD33 antigen, which is expressed on leukemia cells from more than 90 % of patients with AML. This conjugated mAb was introduced following promising results from phase I and II studies. However, the initial phase III study did not confirm the efficacy of GO in combination with conventional chemotherapies. Several subsequent phase III studies have shown the efficacy of GO in favorable and intermediate risk AML. Several resistance mechanisms against GO have been reported. Multidrug resistant (MDR) P-glycoprotein (P-gp), a trans-membrane glycoprotein that pumps out many anti-leukemic agents from cells, also affects GO. For this reasons, GO has been used in combination with MDR modifiers, such as cyclosporine, and in cases without P-gp. Several investigators have reported successful results of the use of GO in acute promyelocytic leukemia (APL). GO has also been described as effective in cases relapsed after treatment with all-trans retinoic acid (ATRA), arsenic acid and conventional chemotherapeutic agents. The efficacy of GO will be studied mainly in a favorable risk of AML, such as core binding factor leukemia and APL. In addition, suitable combinations with other chemotherapies and administration schedules should be discussed.

NPM1, FLT3, and c-KIT mutations in pediatric acute myeloid leukemia in Russian population

We evaluated frequencies of NPM1, FLT3, c-KIT mutations in childhood acute myeloid leukemia (AML) in Russia and assessed prognostic relevance of the mutations. RNA and DNA were extracted from bone marrow samples of 186 (106 male and 80 female) pediatric patients younger than 17 year with de novo AML. Mutations and chromosomal rearrangements were detected by sequencing of a corresponding gene. NPM1 mutations were found in 5.2%, FLT3 mutations in 12.1%, c-KIT mutations in 3.7% of the patients. NPM1 mutations were associated with the absence of chromosomal aberrations (P=0.007) and FLT3/ITD (P=0.018). New data on incidence of c-KIT mutations in various AML subtypes as well as new variations of c-KIT mutations in the exon 8 are presented. The results are compared to previously published studies on NPM1, FLT3, c-KIT mutations in various populations. No statistically significant differences in survival rates between groups with or without of FLT3, NPM1, c-KIT mutations were found (P>0.05). Meanwhile, 4-year overall survival rates were higher in patients having NPM1 mutations comparing with NPM1/WT patients (100% vs. 50%) and in patients having FLT3 mutations comparing with FLT3/WT patients (70% vs. 50%). The data presented contribute to knowledge on incidence and prognostic significance of the mutations in pediatric AML.

Lung cancer-initiating cells: a novel target for cancer therapy

Lung cancer is a major public health problem causing more deaths than any other cancer. A better understanding of the biology of this disease and improvements in treatment are greatly needed. Increasing evidence supports the concept that a rare and specialized population of cancer cells, so-called cancer-initiating cells with stem cell-like characteristics, is responsible for tumor growth, maintenance, and recurrence. Cancer-initiating cells also exhibit characteristics that render them resistant to both radiation and chemotherapy, and therefore they are believed to play a role in treatment failure. This has led to the hypothesis that traditional therapies that indiscriminately kill tumor cells will not be as effective as therapies that selectively target cancer-initiating cells. Investigating putative cancer-initiating cells in lung cancer will greatly benefit the understanding of the origins of this disease and may lead to novel approaches to therapy by suggesting markers for use in either further isolating this population for study or for selectively targeting these cells. This review will discuss (1) lung cancer, (2) stem cells, and the role of cancer-initiating cells in tumorigenesis; (3) markers and functional characteristics associated with lung cancer-initiating cells; and (4) the potential to selectively target this subpopulation of tumor cells.

Acute promyelocytic leukemia with Flt3-TKD and WT1 mutations relapsing in a testicle and followed by systemic relapse

Extramedullary relapse is a rare phenomenon in patients with acute promyelocytic leukemia (APL), especially that derived from urogenital systems like the testicles. In this report, we describe an APL patient who had received standard induction/maintenance therapy resulting in durable remission for 4.5 years, when he presented with a unilateral testicular mass confirmed as myeloid sarcoma; this was followed by systemic relapse of APL. Retrospective analysis of the involved blood and bone marrow samples at the time of the initial diagnosis revealed a rare point mutation of FLT3-TKD and a novel mutation of WT1. These mutations were detected recurrently throughout the course of the disease. After reinduction therapy with arsenic trioxide and all-trans retinoic acid combined with daunorubicin, complete hematological remission was achieved for the ensuing salvage allogeneic hematopoietic stem cell transplant.

Breast cancer stem cells: new therapeutic approaches

SUMMARY Breast cancer stem cells are defined as a small subset of cells within a cancer that constitutes a reservoir of self-sustaining cells; they are low-dividing, have a reduced ability to undergo apoptosis and a higher ability of DNA repair, making them more resistant to conventional radiation and chemotherapy. The recent better understanding of the mechanisms of resistance to therapy related to stem cells has opened new scenarios and perspectives for therapeutic approaches. Some drugs active against breast cancer stem cells have been used in cancer therapy for years, other approaches are currently under clinical trials and many drugs are still in a preclinical phase. Only controlled clinical trials will answer the question whether or not these new therapeutical approaches alone or combined with the ongoing treatments significantly improve the outcome of breast cancer patients.

Tumor endothelial markers as a target in cancer

INTRODUCTION

Several anti-angiogenic agents have been developed and some of them have been clinically applied in the tumor therapy. Anti-angiogenic therapy faces some hurdles: inherent or acquired resistance, increased invasiveness, and lack of biomarkers. Characterization of tumor endothelial markers may help to target endothelium and to identify potential predictive factors of response to anti-angiogenic therapies. Numerous surrogates, angiogenic and endothelium markers have emerged from recent pre-clinical studies, including physiological and soluble molecules in plasma and from platelets, circulating cells, tumor tissue factors and imaging markers. However, no wholly validated biomarkers currently exist to predict the success or the failure of the anti-angiogenic therapy of cancer. Therefore, the research of suitable and validate biomarkers is currently ongoing.

AREAS COVERED

This review provides an overview of the status of our knowledge concerning tumor endothelial markers, therapeutics targeting, possible resistance mechanisms and predictive value of these biomarkers and discuss future strategies to use and identify them in the anti-angiogenic therapy.

EXPERT OPINION

Anti-angiogenesis is a milestone to improve the treatment of several types of cancer and predictive biomarkers for a response to anti-endothelium therapy are one of the most important challenges for anti-angiogenesis research.

Recombinant human soluble thrombomodulin safely and effectively rescues acute promyelocytic leukemia patients from disseminated intravascular coagulation

We treated individuals for disseminated intravascular coagulation (DIC) caused by acute promyelocytic leukemia (APL) (n=9) using human soluble thrombomodulin (rTM) in combination with all-trans retinoic acid (ATRA) and chemotherapy, and compared the clinical outcomes with historical control patients (n=8) treated with ATRA and/or chemotherapy. Two control patients developed intracranial vascular incidents. On the other hand, no bleeding related mortality was noted in rTM-treated patients. Notably, treatment with rTM rescued patients from DIC earlier than historical controls (log rank test, p=0.019). These results suggest that administration of rTM should be considered for the treatment of individuals with DIC associated with APL.

Statin-dependent activation of protein kinase Cδ in acute promyelocytic leukemia cells and induction of leukemic cell differentiation

Statins are HMG-CoA (3-hydroxy-3-methyl-glutaryl-coenzyme A) reductase inhibitors, which block the conversion of HMG-CoA to mevalonate and have potent cholesterol lowering properties. Beyond their importance in the generation of lipid lowering effects, the regulatory effects of statins on the mevalonate pathway have a significant impact on multiple other cellular functions. There is now extensive evidence that statins have anti-inflammatory and anti-neoplastic properties, but the precise mechanisms by which such responses are generated are not well understood. In the present study we demonstrate that statins engage a member of the protein kinase C (PKC) family of proteins, PKCδ, in acute promyelocytic leukemia (APL) cells. Our study shows that atorvastatin and fluvastatin induce proteolytic activation of PKCδ in the APL NB4 cell line, which expresses the t(15;17) translocation. Such engagement of PKCδ results in induction of its kinase domain and downstream regulation of pathways important for statin-dependent leukemia cell differentiation. Our research shows that the function of PKCδ is essential for statin-induced leukemic cell differentiation, as demonstrated by studies involving selective targeting of PKCδ using siRNAs. We also demonstrate that the potent enhancing effects of statins on all-trans retinoic acid (ATRA)-induced gene expression for CCL3 and CCL4 requires the function of PKCδ, suggesting a mechanism by which statins may promote ATRA-induced antileukemic responses. Altogether, our data establish a novel function for PKCδ as a mediator of statin-induced differentiation of APL cells and antileukemic effects.

Cancer stem cells and tumor angiogenesis

Cancer stem cells (CSCs) have been identified in several human solid and hematological tumors. They are able to initiate tumor formation and metastasis and express specific cell surface markers. CSC tend to be more resistant to chemotherapeutic agents and radiation therapy than more mature cell types from the same tissue because of increased expression of antiapoptotic proteins. In this context, the development of agents that eliminate or control CSC may be an effective strategy for cancer prevention.

Thrombomodulin enhances the antifibrinolytic and antileukemic effects of all-trans retinoic acid in acute promyelocytic leukemia cells

This study found that levels of thrombomodulin (TM) were downregulated in freshly isolated leukemia cells from patients with acute promyelocytic leukemia (APL, n = 7) and acute myelogenous leukemia (n = 14), as compared with CD34(+)/CD38(-) hematopoietic stem/progenitor cells and CD34(-)/CD33(+)/CD11b(-) promyelocytes isolated from healthy volunteers (n = 3). Exposure of APL NB4 cells to recombinant human soluble TM (rTM, 1500 ng/mL) inhibited clonogenic growth of these cells by approximately 30%, and induced expression of CD11b, a marker of myeloid differentiation, on their surfaces, in association with upregulation of nuclear levels of myeloid-specific transcription factor CCAAT/enhancer binding protein ε. These antileukemic effects of rTM were mediated by thrombin/activated protein C-dependent mechanisms, as hirudin, an inhibitor of thrombin and a blocking antibody against endothelial receptor for protein C to which activated protein C binds, hampered the ability of rTM to induce expression of CD11b in NB4 cells. This study also found that rTM downregulated expression of Annexin II, a receptor for both plasminogen and tissue plasminogen activator, and inhibited plasmin activity in APL cells. Interestingly, rTM significantly enhanced the ability of all-trans retinoic acid to induce growth arrest, differentiation and apoptosis, and inhibited plasmin activity in APL cells. Taken together, these results suggest that administration of rTM should be considered for treatment of individuals with disseminated intravascular coagulation associated with APL.

Extramedullary disease in acute promyelocytic leukemia: two-in-one disease

In acute promyelocytic leukemia (APL), extramedullary disease (EMD) is particularly rare and shows special clinical and biological features. It is estimated that about 3-5% of APL patients will suffer extramedullary relapse. The most common site of EMD in APL is the central nervous system (CNS). At present, there are still many issues of EMD in APL needing further clarification, including pathogenesis, risk factors, prognosis and treatment. A better understanding of the biological mechanisms underlying EMD is important to be able to devise more effective CNS prophylaxis and induction-consolidation therapeutic strategies.

Cancer stem cells in the human mammary gland and regulation of their differentiation by estrogen

The identification and characterization of normal and breast cancer stem cells have provided a new vision of breast tumorigenesis. Cancer stem cells may be responsible for breast tumor initiation, progression and development of resistance to therapy. Most breast cancers express the estrogen receptor, and several studies have linked long-term estrogen exposure to enhanced breast cancer risk; however, estrogen receptor-positive tumors usually present a better prognosis than estrogen receptor-negative ones. The finding that estrogen reduces the pool of human breast stem cells may explain the more differentiated phenotype observed in estrogen receptor-positive tumors. In this article, our current understanding of the complex role of estrogen in human breast stem cells is discussed in the context of breast malignancy.

Cancer stem cells and cancer therapy

Cancer stem cells (CSCs) are a subpopulation of tumour cells that possess the stem cell properties of self-renewal and differentiation. Stem cells might be the target cells responsible for malignant transformation, and tumour formation may be a disorder of stem cell self-renewal pathway. Epigenetic alterations and mutations of genes involved in signal transmissions may promote the formation of CSCs. These cells have been identified in many solid tumours including breast, brain, lung, prostate, testis, ovary, colon, skin, liver, and also in acute myeloid leukaemia. The CSC theory clarifies not only the issue of tumour initiation, development, metastasis and relapse, but also the ineffectiveness of conventional cancer therapies. Treatments directed against the bulk of the cancer cells may produce striking responses but they are unlikely to result in long-term remissions if the rare CSCs are not targeted. In this review, we consider the properties of CSCs and possible strategies for controlling the viability and tumourigenecity of these cells, including therapeutic models for selective elimination of CSCs and induction of their proper differentiation.

Changing paradigm of the treatment of Philadelphia chromosome-positive acute lymphoblastic leukemia

In the pre-imatinib era, the treatment outcome of patients with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph(+) ALL) was dismal. Complete remission was generally achieved only in about 50% to 60% of patients, and allogeneic hematopoietic stem cell transplantation (allo-HSCT), when feasible in younger patients, was virtually the sole curative modality. Imatinib has changed the situation dramatically, however, in combination with conventional chemotherapy or with corticosteroid alone, producing about 95% complete remission and thus increasing the number of patients undergoing allo-HSCT. Currently, the overall survival of patients who have undergone allo-HSCT exceeds 50%, and a considerable proportion of patients for whom allo-HSCT is not feasible are predictably curable. The next question is how to prevent relapse, which is observed not only in more than half of patients for whom allo-HSCT is not feasible but also in a considerable number of patients after allo-HSCT. Thus, improvement of postremission therapy is crucial. Whether intensive chemotherapy with currently available cytotoxic drugs contributes to the prevention of relapse is questionable, because intensive chemotherapy alone in the pre-imatinib era nearly always failed to cure this disease. Promising partners to be combined with imatinib or with a second-generation tyrosine kinase inhibitor (TKI) will be corticosteroids and vincristine. New TKIs such as dasatinib should be incorporated into the early phase of postremission therapy. Recognizing the small number of patients with Ph(+) ALL, intergroup or international studies are necessary to develop the best postremission therapy. In the near future, it is hoped that Ph(+) ALL will become one of the leukemias for which allo-HSCT is offered only for relapsed or extremely high-risk patients.