C-terminal binding protein 2 is a novel tumor suppressor targeting the MYC-IRF4 axis in multiple myeloma.

ABSTRACT: Multiple myeloma (MM) cells are addicted to MYC and its direct transactivation targets IRF4 for proliferation and survival. MYC and IRF4 are still considered "undruggable," as most small-molecule inhibitors suffer from low potency, suboptimal pharmacokinetic properties, and undesirable off-target effects. Indirect inhibition of MYC/IRF4 emerges as a therapeutic vulnerability in MM. Here, we uncovered an unappreciated tumor-suppressive role of C-terminal binding protein 2 (CTBP2) in MM via strong inhibition of the MYC-IRF4 axis. In contrast to epithelial cancers, CTBP2 is frequently downregulated in MM, in association with shortened survival, hyperproliferative features, and adverse clinical outcomes. Restoration of CTBP2 exhibited potent antitumor effects against MM in vitro and in vivo, with marked repression of the MYC-IRF4 network genes. Mechanistically, CTBP2 impeded the transcription of MYC and IRF4 by histone H3 lysine 27 deacetylation (H3K27ac) and indirectly via activation of the MYC repressor IFIT3. In addition, activation of the interferon gene signature by CTBP2 suggested its concomitant immunomodulatory role in MM. Epigenetic studies have revealed the contribution of polycomb-mediated silencing and DNA methylation to CTBP2 inactivation in MM. Notably, inhibitors of Enhance of zeste homolog 2, histone deacetylase, and DNA methyltransferase, currently under evaluation in clinical trials, were effective in restoring CTBP2 expression in MM. Our findings indicated that the loss of CTBP2 plays an essential role in myelomagenesis and deciphers an additional mechanistic link to MYC-IRF4 dysregulation in MM. We envision that the identification of novel critical regulators will facilitate the development of selective and effective approaches for treating this MYC/IRF4-addicted malignancy.

R4 RGS proteins suppress engraftment of human hematopoietic stem/progenitor cells by modulating SDF-1/CXCR4 signaling.

Homing and engraftment of hematopoietic stem/progenitor cells (HSPCs) into the bone marrow (BM) microenvironment are tightly regulated by the chemokine stromal cell-derived factor-1 (SDF-1) and its G-protein-coupled receptor C-X-C motif chemokine receptor 4 (CXCR4), which on engagement with G-protein subunits, trigger downstream migratory signals. Regulators of G-protein signaling (RGS) are GTPase-accelerating protein of the Gα subunit and R4 subfamily members have been implicated in SDF-1-directed trafficking of mature hematopoietic cells, yet their expression and influence on HSPCs remain mostly unknown. Here, we demonstrated that human CD34+ cells expressed multiple R4 RGS genes, of which RGS1, RGS2, RGS13, and RGS16 were significantly upregulated by SDF-1 in a CXCR4-dependent fashion. Forced overexpression of RGS1, RGS13, or RGS16 in CD34+ cells not only inhibited SDF-1-directed migration, calcium mobilization, and phosphorylation of AKT, ERK, and STAT3 in vitro, but also markedly reduced BM engraftment in transplanted NOD/SCID mice. Genome-wide microarray analysis of RGS-overexpressing CD34+ cells detected downregulation of multiple effectors with established roles in stem cell trafficking/maintenance. Convincingly, gain-of-function of selected effectors or ex vivo priming with their ligands significantly enhanced HSPC engraftment. We also constructed an evidence-based network illustrating the overlapping mechanisms of RGS1, RGS13, and RGS16 downstream of SDF-1/CXCR4 and Gαi. This model shows that these RGS members mediate compromised kinase signaling and negative regulation of stem cell functions, complement activation, proteolysis, and cell migration. Collectively, this study uncovers an essential inhibitory role of specific R4 RGS proteins in stem cell engraftment, which could potentially be exploited to develop improved clinical HSPC transplantation protocols.

CD9 blockade suppresses disease progression of high-risk pediatric B-cell precursor acute lymphoblastic leukemia and enhances chemosensitivity.

CD9 has been implicated in cancer progression but its prognostic relevance and therapeutic potential in B-cell precursor acute lymphoblastic leukemia (BCP-ALL) are largely unknown. In a cohort of pediatric BCP-ALL patients, we found that CD9+ cases had a significantly lower 5-year relapse-free survival rate than CD9- cases. Multivariate analysis demonstrated that CD9 positivity independently predicted inferior survival outcomes, and could be applied with established prognostic features, including prednisone response and cytogenetic status, to refine patient stratification. Administration of CD9 antibody substantially suppressed disease progression in NOD/SCID mice xenografted with CD9+ cell lines and primary leukemic blasts from patients with high-risk and refractory BCP-ALL, without compromising hematopoietic stem cell engraftment. Combination of anti-CD9 with conventional chemotherapy further reduced leukemic burden and prolonged animal survival. Mechanistically, CD9 blockade inhibited leukemic cell proliferation, induced G0/G1 cell cycle arrest, activated p38, and enhanced chemotherapeutic agent-induced apoptosis. Further, CD9 physically interacted with integrin very late antigen-4, regulated affinity to vascular cell adhesion molecule-1, and was involved in leukemia-stroma interaction. Collectively, our study established CD9 as a new prognostic marker, validated the preclinical efficacy of CD9 antibody, and laid the foundation for clinical development of CD9-targeted therapy for high-risk and refractory pediatric BCP-ALL.

Transfer of Extracellular Vesicle-Associated-RNAs Induces Drug Resistance in ALK-Translocated Lung Adenocarcinoma.

Anaplastic lymphoma kinase (ALK) translocation is an actionable mutation in lung adenocarcinoma. Nonetheless tumour consists of heterogeneous cell subpopulations with diverse phenotypes and genotypes, and cancer cells can actively release extracellular vesicles (EVs) to modulate the phenotype of other cells in the tumour microenvironment. We hypothesized that EVs derived from a drug-resistant subpopulation of cells could induce drug resistance in recipient cells. We have established ALK-translocated lung adenocarcinoma cell lines and subclones. The subclones have been characterized and the expression of EV-RNAs determined by quantitative polymerase chain reaction. The effects of EV transfer on drug resistance were examined in vitro. Serum EV-RNA was assayed serially in two patients prescribed ALK-tyrosine kinase inhibitor (ALK-TKI) treatment. We demonstrated that the EVs from an ALK-TKI-resistant subclone could induce drug resistance in the originally sensitive subclone. EV-RNA profiling revealed that miRNAs miR-21-5p and miR-486-3p, and lncRNAs MEG3 and XIST were differentially expressed in the EVs secreted by the resistant subclones. These circulating EV-RNA levels have been found to correlate with disease progression of EML4-ALK-translocated lung adenocarcinoma in patients prescribed ALK-TKI treatment. The results from this study suggest that EVs released by a drug-resistant subpopulation can induce drug resistance in other subpopulations and may sustain intratumoural heterogeneity.

A single nucleotide polymorphism in microRNA-146a is associated with the risk for nasopharyngeal carcinoma.

A common GC polymorphism within miRNA-146a precursor region (rs2910164) has been associated with the risk of various cancers despite the underlying mechanism is unclear. In the current study, we aimed to examine the role of rs2910164 in the pathogenesis and predisposition to nasopharyngeal carcinoma (NPC). The GC polymorphism in 233 NPC patients, 173 matched controls and 3613 healthy elderly subjects in our locality were first determined using melting temperature (T(m))-shift allele-specific genotyping method. Results in our case-control study indicated that CC genotype was associated with the risk effect of NPC (adjusted odds ratio of GC + GG vs. CC, 0.49; 95% confidence interval, 0.35-0.69; P < 0.0001). Using real-time polymerase chain reaction (PCR) assay, we subsequently revealed that expressions of both miR-146a and its passenger strand (miR-146a*C or miR-146a*G) were increased in NPC samples (P < 0.001), albeit expression of miR-146a was not linked to the genotype. Furthermore, miR-146a*C in NPC was significantly increased in CC genotype (CC vs. GC, P = 0.038). Finally, we demonstrated by co-immunoprecipitation and luciferase reporter assays that all three miR-146a precursor-derived mature miRNAs interacted with Argonaute2 (Ago2) protein complex and could function as gene silencers. Taken together, our results showed that the variant C in rs2910164 was associated with the predisposition of NPC in Chinese population. This polymorphism may influence the risk of NPC by producing active mature miR-146a*C that regulate distinct set of target genes. These findings may enrich our understanding of how miRNA single nucleotide polymorphism affect NPC pathogenesis, and may have potential implications to improve NPC treatment in the future.

Thrombophilia among Chinese women with venous thromboembolism during pregnancy.

AIMS: To assess the prevalence of thrombophilia among Chinese women with venous thromboembolism (VTE) developed during pregnancy. METHODS: Based on information from a tertiary teaching unit, all recorded cases of deep vein thrombosis (DVT) and pulmonary embolism (PE) during pregnancy diagnosed between 1997 and 2005, were assessed for prevalence of thrombophilia. Fifty-five healthy women, who had at least one normal pregnancy but without any previous history of VTE, were recruited as controls. RESULTS: A total of 44 subjects completed thrombophilia screening, of whom 5 (11%) were confirmed to have thrombophilia [protein C (PC) deficiency (2), protein S (PS) deficiency (1), combined PC & PS deficiency (1) and antithrombin III deficiency (1)]. Homozygous 5,10-methylenetetrahydrofolate reductase (C677T) gene mutation was found in 6 (14%) subjects but not in the controls. There was no antiphospholipid syndrome, activated PC resistance, factor V Leiden or prothrombin gene mutations. CONCLUSION: In the Chinese population, PS and PC deficiencies are common thrombophilia for VTE during pregnancy and thrombophilia screening should be recommended in all pregnant women who suffer from VTE.

Sustained antitumor activity by co-targeting mTOR and the microtubule with temsirolimus/vinblastine combination in hepatocellular carcinoma.

The mammalian target of rapamycin (mTOR) and the microtubules are prominent druggable targets for hepatocellular carcinoma (HCC). PI3K/Akt/mTOR activation is associated with resistance to microtubule inhibitors. Here, we hypothesized that co-targeting of mTOR (by mTOR inhibitor temsirolimus) and the microtubule (by microtubule-destabilizing agent vinblastine) would be more efficacious than single targeting in HCC models. In vitro studies showed that effective inhibition of mTOR signaling with temsirolimus alone was able to suppress HCC cell growth in a dose-dependent manner. Among five cell lines tested, Huh7 was the most temsirolimus-sensitive (IC(50)=1.27±0.06µM), while Hep3B was the most temsirolimus-resistant (IC(50)=52.95±17.14µM). We found that co-targeting of mTOR (by temsirolimus) and the microtubule (by vinblastine, at low nM) resulted in marked growth inhibition in Huh7 cells and synergistic growth inhibition in Hep3B cells (achieving maximal growth inhibition of 80-90%), demonstrating potent antitumor activity of this novel combination. In vivo studies showed that temsirolimus treatment alone for 1 week was able to inhibit the growth of Huh7 xenografts. Strikingly, the temsirolimus/vinblastine combination induced a significant and sustained antitumor activity (up to 27 days post-treatment), with effective reduction of tumor vessel density in both Huh7 and Hep3B xenograft models. Mechanistic investigation revealed that this marked antitumor effect was accompanied by specific and concerted down-regulation of several key anti-apoptotic/survival proteins (survivin, Bcl-2, and Mcl-1), which was not observed in single agent treatments. Our findings demonstrated that the potent anti-cancer activity of this co-targeting strategy was indeed mediated in parts by inhibition of these key survival/anti-apoptotic proteins.

CD44+ cancer stem-like cells in EBV-associated nasopharyngeal carcinoma.

Nasopharyngeal carcinoma (NPC) is a unique EBV-associated epithelial malignancy, showing highly invasive and metastatic phenotype. Despite increasing evidence demonstrating the critical role of cancer stem-like cells (CSCs) in the maintenance and progression of tumors in a variety of malignancies, the existence and properties of CSC in EBV-associated NPC are largely unknown. Our study aims to elucidate the presence and role of CSCs in the pathogenesis of this malignant disease. Sphere-forming cells were isolated from an EBV-positive NPC cell line C666-1 and its tumor-initiating properties were confirmed by in vitro and in vivo assays. In these spheroids, up-regulation of multiple stem cell markers were found. By flow cytometry, we demonstrated that both CD44 and SOX2 were overexpressed in a majority of sphere-forming C666-1 cells. The CD44+SOX2+ cells was detected in a minor population in EBV-positive xenografts and primary tumors and considered as potential CSC in NPC. Notably, the isolated CD44+ NPC cells were resistant to chemotherapeutic agents and with higher spheroid formation efficiency, showing CSC properties. On the other hand, microarray analysis has revealed a number of differentially expressed genes involved in transcription regulation (e.g. FOXN4, GLI1), immune response (CCR7, IL8) and transmembrane transport (e.g. ABCC3, ABCC11) in the spheroids. Among these genes, increased expression of CCR7 in CD44+ CSCs was confirmed in NPC xenografts and primary tumors. Importantly, blocking of CCR7 abolished the sphere-forming ability of C666-1 in vitro. Expression of CCR7 was associated with recurrent disease and distant metastasis. The current study defined the specific properties of a CSC subpopulation in EBV-associated NPC. Our findings provided new insights into developing effective therapies targeting on CSCs, thereby potentiating treatment efficacy for NPC patients.

Improved survival outcome of childhood acute myeloid leukemia with intensified chemotherapy in Chinese children.

With the use of intensive chemotherapy and hematopoietic stem cell transplantation (HSCT), the prognosis of childhood acute myeloid leukemia (AML) improved over the last 2 decades. Survival data of Chinese pediatric patients were seldom reported. The authors adopted modified UK Medical Research Council (MRC) AML protocols for treatment of childhood AML since 1994. From 1994 to 2008, the outcomes of Chinese AML patients were studied. Sixty-eight patients were studied. The median age at diagnosis was 9.9 years. Twenty-five patients (36.8%) had favorable cytogenetic karyotypes, including t(15;17), t(8;21) and inv(16). Complete remission (CR) rate was 91.2%. The relapse rate was 29.4%. For non-M3 patients, the 5-year overall survival (pOS) was 64% ± 7% and event-free survival (pEFS) was 53% ± 7%. For those non-good-risk patients who achieved CR, there were no significant differences in outcomes between patients who received HSCT in CR1 and those received chemotherapy alone (5-year pOS 80% ± 13% and 69% ± 9%, P = .52), 5-year pEFS 69% ± 15% and 55% ± 10%, P = .40). The pOS of the 20 relapsed patients was 29% ± 11%. Sixteen patients with t(8;21) and inv(16) had similar outcome with those without favorable cytogenetics (pOS 66% ± 12% versus 65% ± 7%, P = .39; pEFS 60% ± 11% versus 54% ± 8%, P = .45). Patients who achieved CR after 2 or more courses of chemotherapy and presenting white blood cell count (WBC) ≥ 100 × 10(9)/L had poorer outcome (pOS 40% versus 80%P < .01; 43% versus 70%, P = .02, respectively). Intensified chemotherapy improved outcome of Chinese AML children. CR after first course of chemotherapy and WBC at diagnosis were important prognostic factors.

Anti-invasion, anti-proliferation and anoikis-sensitization activities of lapatinib in nasopharyngeal carcinoma cells.

Nasopharyngeal cancer (NPC) is a highly prevalent and invasive head and neck cancer in Asia. Disease recurrence and distant metastasis account for major NPC deaths. Therefore, more effective therapy is needed. Lapatinib, a dual tyrosine kinase inhibitor (TKI) against both EGFR and HER-2, has been known to exert potent antitumor activity against several cancer models. Given that both EGFR and HER-2 are co-expressed in NPC, we hypothesized that dual targeting of EGFR and HER-2 by this small molecule EGFR/HER-2 TKI would elicit anti-tumor activity in NPC. Using in vitro models of NPC, we demonstrated that lapatinib was able to efficiently inhibit the phosphorylation of both EGFR and HER-2. This was accompanied by significant growth inhibition of NPC cells (with maximal growth inhibition >90%). For the most lapatinib-sensitive cell line (HK1-LMP1, with IC(50) ∼ 600 nM), which harbored the highest levels of both EGFR and HER-2, inhibition of cell growth was associated G(0)/G(1) cell cycle arrest, marked PARP cleavage, caspase-3 cleavage, as well as significant downregulation of several important survival proteins (e.g. survivin, Mcl-1 and cyclin D1). NPC cells are intrinsically invasive. We found that lapatinib was able to inhibit cellular invasion of both HK1-LMP1 and HONE-1 cells. Furthermore, our data demonstrated for the first time that lapatinib harbored potent anoikis-sensitization activity (i.e. sensitizing cancer cells to detachment-induced apoptosis) in human cancer cells overexpressing both EGFR and HER-2 (HK1-LMP1 and HK1). Taken together, our findings suggest that lapatinib is a promising anti-cancer agent for NPC with anti-invasion and anoikis-sensitization activities.

An RNA-directed nucleoside anti-metabolite, 1-(3-C-ethynyl-beta-d-ribo-pentofuranosyl)cytosine (ECyd), elicits antitumor effect via TP53-induced Glycolysis and Apoptosis Regulator (TIGAR) downregulation.

1-(3-C-ethynyl-beta-d-ribo-pentofuranosyl)cytosine (ECyd) is a ribose-modified nucleoside analog of cytidine with potent anticancer activity in several cancers. The main antitumor mechanism of this promising RNA-directed nucleoside anti-metabolite is efficient blockade of RNA synthesis in cancer cells. Here, we examined the therapeutic potential of this RNA-directed anti-metabolite in in vitro models of nasopharyngeal cancer (NPC). In a panel of 6 NPC cell lines, ECyd effectively inhibited cellular proliferation at nM concentrations (IC(50): approximately 13-44nM). Moreover, cisplatin-resistant NPC cells were highly sensitive to ECyd (at nM concentration). The ECyd-mediated growth inhibition was associated with G(2)/M cell cycle arrest, PARP cleavage (a hallmark of apoptosis) and Bcl-2 downregulation, indicating induction of apoptosis by ECyd in NPC cells. Unexpectedly, ECyd-induced significant downregulation of TIGAR, a newly described dual regulator of apoptosis and glycolysis. More importantly, this novel action of ECyd on TIGAR was accompanied by marked depletion of NADPH, the major reducing power critically required for cell proliferation and survival. We hypothesized that ECyd-induced TIGAR downregulation was crucially involved in the antitumor activity of ECyd. Indeed, overexpression of TIGAR was able to rescue NPC cells from ECyd-induced growth inhibition, demonstrating a novel mechanistic action of ECyd on TIGAR. We demonstrated for the first time that an RNA-directed nucleoside analog, ECyd, exerts its antitumor activity via downregulation of a novel regulator of apoptosis, TIGAR. Moreover, ECyd may represent a novel therapy for NPC.

Preclinical activity of gefitinib in non-keratinizing nasopharyngeal carcinoma cell lines and biomarkers of response.

This study evaluated the preclinical activity and molecular predictors of response to gefitinib (Iressa(R), Astra Zeneca Inc, UK) in nasopharyngeal carcinoma (NPC). The activity of gefitinib was evaluated in four human NPC cell lines--HK1, HONE-1, CNE2, C666-1. A representative gefitinib-sensitive (HK1, IC(50) = 250 nM) and gefitinib-resistant cell line (HONE-1, IC(50) > 15 microM) were selected and compared for expression of epidermal growth factor receptor (EGFR) and related ligands, and activation of downstream proteins. Gefitinib induced G1 cycle arrest, apoptosis and inhibited cell invasion more significantly in HK1 than HONE-1 cells. HK1 expressed higher levels of p-EGFR, lower p-AKT and phospho-signal transducer and activator of transcription 3 (p-STAT3) than other cell lines. EGFR gene was found to be amplified in HK1. Gefitinib at IC(50) concentrations significantly suppressed EGF-induced activation of p-EGFR, phospho-mitogen-activated protein kinase (p-MAPK) and p-STAT3, but p-AKT showed persistent activation in HK1 and HONE-1 cells. There was no difference in EGFR-ligand expression between the 4 NPC cell lines. In NPC samples derived from non-responders to gefitinib, 50% and 60% showed cytoplasmic and nuclear pi-EGFR expression, respectively, and 33% showed p-AKT expression. EGFR or KRAS mutations were not detected. This study suggests that most NPC cell lines are intrinsically resistant to gefitinib (except HK1 cells), and further studies are needed to confirm whether EGFR gene amplification and persistent AKT activation may influence response to gefitinib in NPC.

A small molecule inhibitor of NF-kappaB, dehydroxymethylepoxyquinomicin (DHMEQ), suppresses growth and invasion of nasopharyngeal carcinoma (NPC) cells.

Despite the demonstrated constitutive activation of NF-kappaB in nasopharyngeal carcinoma (NPC), the therapeutic potential of targeting this pathway has not been investigated. Here, we employed a small molecule inhibitor of NF-kappaB, DHMEQ (which mainly blocks nuclear translocation of activated NF-kappaB) and demonstrated significant inhibition of NPC cell proliferation, migration, invasion, as well as anchorage-independent growth. These antitumor effects were associated with induction of G(2)/M cell cycle arrest and apoptosis, and downregulation of NF-kappaB target genes (EGFR, cyclin D1 and survivin). This first demonstration of therapeutic benefits of NF-kappaB targeting in NPC implicates the importance of targeting this pathway in NPC.

Clonal evolution of 8p11 stem cell syndrome in a 14-year-old Chinese boy: a review of literature of t(8;13) associated myeloproliferative diseases.

We describe a case of coexisting BCR-ABL negative myeloproliferative disorder and precursor T-cell lymphoblastic lymphoma associated with t(8;13) involving FGFR1 at 8p11 in a 14-year-old boy who presented with generalized lymphadenopathy and an abdominal mass. JAK2 mutation and FIP1L1-PDGFRalpha were not detected. RT-PCR revealed the ZNF198-FGFR1 fusion transcript in both the bone marrow (BM) and lymph node (LN) of the patient at diagnosis. Of interest, reciprocal FGFR1-ZNF198 fusion transcript was demonstrated in the BM but not LN. Also differential clonal TcRgamma gene rearrangements in the BM and LN samples were observed. These findings provide novel insights into the genetic pathogenesis.

Establishment and characterization of a cytogenetically complex Chinese multiple myeloma-derived cell line with homozygous p53 deletion and cyclin E overexpression.

We describe the establishment and characterization of a new myeloma-derived cell line (MM17), originating from the sacral plasmacytoma of a 54-year-old Chinese woman diagnosed with multiple myeloma (MM). MM17 was confirmed morphologically and immunophenotypically to be clonal plasma cells positive for CD38 and CD138 and negative for EBV marker. Authenticity was confirmed using comparative genomic hybridization and DNA fingerprinting studies on bone marrow aspirate, sacral tumor tissue and MM17. Combined G-banding and multicolor fluorescence in situ hybridization analyses demonstrated a primarily hypodiploid karyotype with two sidelines sharing common stemline aberrations: +6, -7, -10, -13, -14, -17, -X, der(1;17)(q10;q10), t(2;7)(q23;q11.2), t(8;14)(q24;q32) and ins(16;1)(q13;?q22q41); and a number of hypertriploid cells. The involvement of p53 alteration and cyclin E overexpression, both with relevance to the induction of chromosomal instability, was investigated in MM17 and together with two other MM derived cell lines (U266 and IM-9) for cyclin E expression. Homozygous deletion of p53 gene hitherto not reported in MM, was detected. Both MM17 and U266 with complex cytogenetic aberrations demonstrated overexpression of cyclin E1 and E2, whereas IM-9 with a normal karyotype showed cyclin E2 but not E1 overexpression. These data suggested that E1 but not E2 overexpression was associated with chromosomal abnormalities observed in MM17 and U266, which provides the first supporting evidence for the link of cyclin E and chromosomal instability in MM. This is the first characterized Chinese MM-derived cell line with homozygous p53 deletion which may serve as a valuable in vitro system for studying MM pathogenesis particularly for Chinese.

Translocation (11;13)(q23;q14) as the sole abnormality in a childhood de novo acute myelocytic leukemia.

We report a case of childhood de novo acute myelocytic leukemia (AML) with hyperleukocytosis with monoblastic features and deranged hemostasic function. G-band karyotyping demonstrated a previously unreported t(11;13)(q23;q14) in metaphase preparations from a fluorodeoxyuridine synchronized 1-day culture of leukophoresed cells. Multicolor fluorescence in situ hybridization revealed no cryptic rearrangements except for the translocation. Reverse transcriptase polymerase chain reaction showed no concomitant positivity of AML1/ETO, BCR/ABL, PML/RARA, and CBFbeta/MYH11 resulting from t(8;21)(q22;q22), t(9;22)(q34;q11), t(15;17)(q22;q11), and inv(16) (p13q22), respectively. This report of childhood de novo AML harboring t(11;13)(q23;q14) as the sole cytogenetic abnormality provides more data on the leukemogenesis of de novo AML with a 11q23 rearrangement.

Detection of micrometastasis of neuroblastoma to bone marrow and tumor dissemination to hematopoietic autografts using flow cytometry and reverse transcriptase-polymerase chain reaction.

BACKGROUND: The identification of neuroblastoma metastases to bone marrow (BM) is requisite in staging disease for risk-adopted therapy. However, micrometastases were not elucidated fully. METHODS: Flow cytometry (FCM) with CD45/CD56/CD81 and reverse transcriptase-polymerase chain reactions (RT-PCR) for tyrosine hydroxylase (TH) transcripts were used to evaluate neuroblastoma in bilateral BM aspirates at diagnosis, BM autografts, peripheral blood stem cell (PBSC) collections, and CD34(+) cell products of 27 children. RESULTS: TH transcripts were amplified in histology-negative (H(-)) BM specimens from seven patients (four patients with Stage 3 disease, two with Stage 4 disease, and one with Stage 4S disease), revealing a prevalence of submicroscopic metastasis. The median number of CD45(-)CD81(+)CD56(+) cells in four H(-) TH(-) BM samples from two patients with Stage 1 and Stage 2 disease, respectively, was comparable to that encountered in 10 normal BM controls (0.003% [range, 0.002-0.004%] vs. 0.004% [0-0.008%], P = 0.724). In six H(-) TH(+) BM specimens from three patients whom were otherwise diagnosed with neuroblastoma Stage 3, 0.031% (0.009-0.06%) CD45(-)CD81(+)CD56(+) cells were detected. Besides, 1.474% (0.088-3.009%) CD45(-)CD81(+)CD56(+) cells were identified in four H(-) TH(+) BM specimens from two patients at Stage 4. TH transcripts were evident in four of five BM autografts and in 22 of 45 (48.9%) PBSC specimens. FCM demonstrated 0.018% and 0.049% CD45(-)CD81(+)CD56(+) cells in two TH(+) BM autografts, respectively. The number of CD45(-)CD81(+)CD56(+) cells was higher in 19 TH(+) PBSC specimens than in 20 TH(-) PBSC specimens (0.026% [0.006-1.128%] vs. 0% [0-0.009%], P < 0.0001). CD34(+) cell selection achieved 2.9 (2.1-3.5) log depletion of CD45(-)CD81(+)CD56(+) cells in four manipulated products, rendering six of seven PBSC autografts TH-free. CONCLUSIONS: FCM in combination with RT-PCR evaluated neuroblastoma micrometastasis and assessed the purity of hematopoietic autografts for transplant. However, the clinical relevance remains to be elucidated.

Thrombospondin-1 inhibits in vitro megakaryocytopoiesis via CD36.

Thrombospondin-1 (TSP-1) is an inhibitor of angiogenesis, inducing apoptosis of the endothelial cells via CD36 signaling mechanism. We investigated CD36 expression and the effect of TSP-1 on megakaryocytopoiesis, with and without pegylated recombinant human megakaryocyte growth and development factor (PEG-rHuMGDF), and with and without blocking TSP-1 binding with receptor CD36 on megakaryocytic cells. Our data showed that TSP-1 induced a dose-dependent growth inhibition in both murine and human colony forming unit-megakaryocyte (CFU-MK) assays and significantly counteracted the mitogenic effect from PEG-rHuMGDF. Moreover, the growth suppression induced by TSP-1 was correlated with CD36 expression in megakaryocytic cell lines, where growth inhibition was demonstrated in CD36 positive (Meg-01, Dami and CHRF-288-11) but not in CD36 negative (M-07e) cell lines. More importantly, the inhibitory effect of TSP-1 on both human CFU-MK and Meg-01 cells was partially but significantly reversed by the addition of FA6-152 (anti-CD36), a blocking antibody which blocks the access of TSP-1 to CD36 receptor, suggesting that the TSP-1-induced inhibition of megakaryocytopoiesis is probably mediated in part by the binding of TSP-1 to CD36 expressed on the megakaryocytic progenitors. Thus, our findings represent the first demonstration that TSP-1 inhibits in vitro megakaryocytopoiesis via interaction with CD36.

Chromosomal aberrations of multiple myeloma in Chinese patients at diagnosis: a study by combined G-banding and multicolor spectral karyotyping.

Cytogenetic investigation of multiple myeloma (MM) has been difficult by conventional methods and most of the data have been derived from western population where incidence of MM is much higher as compared to that of Asians. The current study represents the first report of chromosomal aberrations of multiple myeloma in Chinese. We investigated 25 consecutive Chinese patients with MM for chromosomal aberrations at diagnosis using G-banding and multicolor spectral karyotyping (SKY). Of the 21 patients successfully analyzed by G-banding, 11 patients revealed cytogenetic abnormalities showing complex numerical and structural aberrations, which were further characterized with SKY. An abnormal karyotype significantly associated with blastic MM was observed. Consistent with the western literature, structural rearrangements involving chromosomes 1, 6, 8, 19, numerical abnormalities of gains in chromosomes 9, 3, and 5, and losses in chromosomes 13 and 14 were observed. However, there were notably higher incidences of -22/22q- (4/11) and structural aberrations of chromosome X but a lower incidence of -X. The biological implications of these findings, if confirmed, deserve further evaluation.