Impairment of DNA Methylation Maintenance Is the Main Cause of Global Demethylation in Naive Embryonic Stem Cells.

Global demethylation is part of a conserved program of epigenetic reprogramming to naive pluripotency. The transition from primed hypermethylated embryonic stem cells (ESCs) to naive hypomethylated ones (serum-to-2i) is a valuable model system for epigenetic reprogramming. We present a mathematical model, which accurately predicts global DNA demethylation kinetics. Experimentally, we show that the main drivers of global demethylation are neither active mechanisms (Aicda, Tdg, and Tet1-3) nor the reduction of de novo methylation. UHRF1 protein, the essential targeting factor for DNMT1, is reduced upon transition to 2i, and so is recruitment of the maintenance methylation machinery to replication foci. Concurrently, there is global loss of H3K9me2, which is needed for chromatin binding of UHRF1. These mechanisms synergistically enforce global DNA hypomethylation in a replication-coupled fashion. Our observations establish the molecular mechanism for global demethylation in naive ESCs, which has key parallels with those operating in primordial germ cells and early embryos.

Decreased intracellular pH induced by cariporide differentially contributes to human umbilical cord-derived mesenchymal stem cells differentiation.

BACKGROUND/AIMS: Na+/H+ exchanger 1 (NHE1) is an important regulator of intracellular pH (pHi). High pHi is required for cell proliferation and differentiation. Our previous study has proven that the pHi of mesenchymal stem cells is higher than that of normal differentiated cells and similar to tumor cells. NHE1 is highly expressed in both mesenchymal stem cells and tumor cells. Targeted inhibition of NHE1 could induce differentiation of K562 leukemia cells. In the present paper we explored whether inhibition of NHE1 could induce differentiation of mesenchymal stem cells. METHODS: MSCs were obtained from human umbilical cord and both the surface phenotype and functional characteristics were analyzed. Selective NHE1 inhibitor cariporide was used to treat human umbilical cord-derived mesenchymal stem cells (hUC-MSCs). The pHi and the differentiation of hUC-MSCs were compared upon cariporide treatment. The putative signaling pathway involved was also explored. RESULTS: The pHi of hUC-MSCs was decreased upon cariporide treatment. Cariporide up-regulated the osteogenic differentiation of hUC-MSCs while the adipogenic differentiation was not affected. For osteogenic differentiation, ß-catenin expression was up-regulated upon cariporide treatment. CONCLUSION: Decreased pHi induced by cariporide differentially contributes to hUC-MSCs differentiation.

Chromosome 1q21 gains confer inferior outcomes in multiple myeloma treated with bortezomib but copy number variation and percentage of plasma cells involved have no additional prognostic value.

Chromosome 1q21 aberrations have not been yet been made part of routine clinical tests and their effect in multiple myeloma is still under investigation. The prognostic value of copy number variation and percentage of plasma cells involved have remained unclear. In the present study, we analyzed the prognostic value of 1q21 in a series of 290 cases of newly diagnosed multiple myeloma treated in a prospective, non-randomized clinical trial (BDH 2008/02). We found that incidence of 1q21 aberration increased at relapse, but its copy numbers and proportion of cells involved did not change. Gains of 1q21 had no impact on survival in patients receiving thalidomide-based treatment but conferred a significantly inferior prognosis in patients under bortezomib-based chemotherapy and was an independent adverse prognostic factor for progression free survival (HR 3.831; 95%CI: 2.125-6.907; P<0.001) and overall survival (HR 3.245; 95%CI: 1.555-6.773; P=0.002). Strikingly, our results showed that the copy number variation and clone size harboring 1q21 gains carried no additional prognostic value and patients with 1q21 gains did not benefit significantly from regimens incorporating bortezomib. Our results indicate that three copies of 1q21 and 20% of plasma cells with this abnormality were enough to confer bortezomib resistance. Therefore, chromosome 1q21 gains should be considered a high-risk feature in multiple myeloma receiving bortezomib therapy.

A pivotal role of bone remodeling in granulocyte colony stimulating factor induced hematopoietic stem/progenitor cells mobilization.

The majority of hematopoietic stem/progenitor cells (HSPCs) reside in bone marrow (BM) surrounded by a specialized environment, which governs HSPC function. Here we investigated the potential role of bone remodeling cells (osteoblasts and osteoclasts) in homeostasis and stress-induced HSPC mobilization. Peripheral blood (PB) and BM in steady/mobilized state were collected from healthy donors undergoing allogeneic transplantation and from mice treated with granulocyte colony stimulating factor (G-CSF), parathyroid hormone (PTH), or receptor activator of nuclear factor kappa-B ligand (RANKL). The number and the functional markers of osteoblasts and osteoclasts were checked by a series of experiments. Our data showed that the number of CD45(-) Ter119(-) osteopontin (OPN)(+) osteoblasts was significantly reduced from 4,085 ± 135 cells/femur on Day 0 to 1,032 ± 55 cells/femur on Day 5 in mice (P = 0.02) and from 21.38 ± 0.66 on Day 0 to 14.78 ± 0.65 on Day 5 in healthy donors (P < 0.01). Decrease of osteoblast number leads to reduced level of HSPC mobilization regulators stromal cell-derived factor-1 (SDF-1), stem cell factor (SCF), and OPN. The osteoclast number at bone surface (OC.N/B.s) was significantly increased from 1.53 ± 0.12 on Day 0 to 4.42 ± 0.46 on Day 5 (P < 0.01) in G-CSF-treated mice and from 0.88 ± 0.20 on Day 0 to 3.24 ± 0.31 on Day 5 (P < 0.01) in human. Serum TRACP-5b level showed a biphasic trend during G-CSF treatment. The ratio of osteoblasts number per bone surface (OB.N/B.s) to OC.N/B.s was changed after adding PTH plus RANKL during G-CSF treatment. In conclusion, short term G-CSF treatment leads to reduction of osteoblasts and stimulation of osteoclasts, and interrupting bone remodeling balance may contribute to HSPC mobilization.

[Regulation of miRNA-15a/-16 expression on the drug resistance of myeloma cells].

OBJECTIVE: To explore the effects and mechanism of bone marrow stromal cells (BMSCs) on the drug resistance of multiple myeloma (MM). METHODS: Fresh untreated MM patient (5 samples) and health donor (5 samples) bone marrow samples were collected from May 2011 to July 2011 at our hospital. Their BMSCs were separated respectively. The supernatant expression of cytokines in BMSCs was detected by enzyme-linked immunosorbent assay (ELISA). Myeloma cells were co-cultured with BMSCs and treated with melphalan or bortezomib. Cell proliferation and miRNA-15a/-16 expression of myeloma cells were measured in different culture conditions with thiazoyl blue tetrazolium bromide (MTT) assay and quantitative real-time PCR (qRT-PCR). miRNA-15a was transfected into myeloma cells. And the miRNA-15a functions on cell cycle and cell apoptosis were detected by flow cytometry. RESULTS: ELISA assay showed that cytokine IL-6 and VEGF were at higher levels in MM-BMSCs than healthy BMSCs ((189 ± 9) vs (115 ± 15) pg/ml, (1497 ± 40) vs (1239 ± 21) pg/ml, both P < 0.05). The miRNA-15a/-16 expressions of myeloma cells were up-regulated after the treatment of melphalan and bortezomib (all P < 0.05). However, the miRNA-15a/-16 up-regulation by melphalan or bortezomib became inhibited when MM cells were co-cultured with MM-BMSCs (melphalan: 4.690 ± 0.050 vs 34.440 ± 4.100, 0.760 ± 0.070 vs 12.030 ± 1.020, bortezomib: 1.440 ± 0.230 vs 11.480 ± 1.488, 0.880 ± 0.040 vs 3.680 ± 0.420, all P < 0.05). Furthermore, IL-6 suppressed the expression of miRNA-15a/-16 in a dose and time-dependent pattern. The transfection of miRNA-15a led to the arrest of MM cell cycle in G(1)/S phase. CONCLUSIONS: BMSCs suppress the proliferation of myeloma cells and regulate the drug sensitivity of myeloma cells through the inhibited expression of miRNA-15a/-16. IL-6 plays a pivotal role in the occurrence of drug resistance.

Four and a Half LIM Domains Protein 2 Mediates Bortezomib-Induced Osteogenic Differentiation of Mesenchymal Stem Cells in Multiple Myeloma Through p53 Signaling and ß-Catenin Nuclear Enrichment.

Myeloma bone disease (MBD), caused by the inhibition of osteoblast activity and the activation of osteoclast in the bone marrow environment, is the most frequent and life-threatening complication in multiple myeloma (MM) patients. Bortezomib (Bzb) was shown to promote MM-derived mesenchymal stem cells (MM-MSCs) differentiation to osteoblast in vitro and in animal models, promoting the bone formation and regeneration, may be mediated via ß-catenin/T-cell factor (TCF) pathway. Further defining molecular mechanism of Bzb-enhanced bone formation in MM will be beneficial for the treatment of myeloma patients. The present study has identified for the first time four and a half LIM domains protein 2 (FHL2), a tissue-specific coregulator that interacts with many osteogenic marker molecules, as a therapeutic target to ameliorate MM bone disease. First, increased messenger RNA (mRNA) and protein levels of FHL2, and the mRNA level of main osteoblast markers (including Runx2, ALP, and Col1A1), were found in MM-patients-derived MSCs after Bzb treatment. FHL2 KD with short hairpin RNA (shRNA) reduced the expression of osteoblast marker genes and blocked the osteogenic differentiation of MM-MSCs regardless of the presence or absence of Bzb, implying that FHL2 is an important activator of the osteogenic differentiation of human MSCs under a proteasome inhibition condition. Molecular analysis showed that the enhanced expression of FHL2 was associated with the Bzb-induced upregulation of p53. No significant change at protein level of total ß-catenin was observed with or without Bzb treatment. However, it was mostly enriched to nuclei in MSCs after Bzb treatment. Moreover, ß-catenin was restricted to the perinuclear region in FHL2 KD cells. These data provide evidence that FHL2 is essential for promoting ß-catenin nuclear enrichment in MM-MSCs. In conclusion, FHL2 is critical for Bzb-induced osteoblast differentiation of MM-MSCs and promotes the osteogenesis, through p53 signaling and ß-catenin activation. Targeting FHL2 in MM may provide a new therapeutic strategy for treating MBD.

t(11;14) multiple myeloma: a subtype associated with distinct immunological features, immunophenotypic characteristics but divergent outcome.

UNLABELLED: t(11;14)(q13;q32) is the most common chromosome translocation in multiple myeloma (MM), but a consensus of clinicopathological features and impact on survival is yet to be reached. We analyzed a cohort of 350 patients with various plasma cell malignancies, including newly diagnosed MM (NDMM, n=253), relapsed/refractory MM (RRMM, n=77), as well as primary and secondary plasma cell leukemia (PCL, n=10 and n=10, respectively). RESULTS: A remarkably higher frequency of t(11;14) was observed in the PCL than in the NDMM. A high incidence of t(11;14) was detected in the IgD, IgM, and nonsecretory MM. The t(11;14) MM group was associated with a significantly higher positive rate of B-lineage associated antigens CD20 and CD79a as well as the lack of CD56 expression. t(11;14) was less likely to be accompanied by 13q14 deletion than 13q14 deletion frequency in non-t(11;14) population (p=0.026), and fewer patients displaying t(11;14) were identified as belonging to the high-risk cytogenetic group due to the extremely low incidence of t(4;14) and t(14;16). As a whole, patients exhibiting t(11;14) had a comparable outcome with the control cohort in NDMM, but CD20 was able to identify two subsets of the disease with dissimilar outcomes. Among patients receiving bortezomib-based treatment, patients harboring t(11;14) without CD20 expression had a significantly shortened PFS (11.0 versus 43.0 months, p=0.005) and OS (16.5 versus 54.0 months, p=0.016) compared with patients displaying t(11;14) with CD20. Our findings suggest that although the t(11;14) plasma cell disorder displayed distinct biological, clinical and laboratory features, it was a heterogeneous disease with divergent outcome.

Further stratification of patients with multiple myeloma by International Staging System in combination with ratio of serum free κ to λ light chains.

The serum free light chain (sFlc) levels were measured for 122 Chinese patients with newly diagnosed symptomatic multiple myeloma (NDSMM), and κ/λ ratios (rFlc) were calculated. The data were analyzed for the roles of sFlc and rFlc in the diagnosis and prognosis of MM. Abnormal sFlc and/or rFlc were detected in 99.2% of patients, demonstrating that the FLC assay is much more sensitive than the commonly used methods. Baseline sFlc and rFlc successfully predicted the overall survival (OS). The median OS was not reached (NR) versus 23 months for the low sFLC group (sFLC-κ < 180 mg/L or sFLC-λ < 592.5 mg/L) and high sFLC group (sFLC-κ ≥ 180 mg/L or sFLC-λ ≥ 592.5 mg/L) (p = 0.001), and NR versus 21 months for the low rFLC group (0.04 ≤ rFLC ≤ 25) and high rFLC group (p < 0.001), respectively. Interestingly, the significant differences in OS between the low and high rFLC groups were not changed by bortezomib chemotherapy. In addition, patients were further stratified by three novel poor-prognosis factors (ß(2)-microglobulin [ß2-MG] > 3.5 mg/L, albumin [ALB] < 35 g/L, rFLC > 25 or rFLC < 0.04) that were developed from combination of the rFlc with the International Staging System (ISS): the low risk group (no factor), the low-intermediate risk group (one factor), the high-intermediate risk group (two factors) and the high risk group (three factors). The median OS for those groups was NR, NR, 24 months and 13 months, respectively (p < 0.05). In conclusion, the sFLC assay was highly sensitive in the diagnosis of MM in Chinese patients. The prognostic potential of the ISS may be improved with the addition of rFLC.

[Cytogenetic abnormality of chromosome 13q14 in 112 patients with multiple myeloma detected by using LSI-RB1 and LSI-D13S319 probes].

Chromosome 13q14 deletion is one of the most common cytogenetic abnormalities in multiple myeloma (MM). LSI (locus-specific identification)-RB1 (13q14.1-14.2 region) and LSI-D13S319 (13q14.3 region) probes are usually used to detect 13q14 deletion. The aims of this study was to compare the incidence of chromosome 13q14.1-14.2 and 13q14.3 deletion and to detect 13q14 deletion size and number of involved cells in MM patients. The chromosome 13q14 region was detected by fluorescence in situ hybridization using probes LSI-RB1 and LSI-D13S319 in plasma cells of 112 MM patients. The results showed that 47.3% (53 out of 112) MM patients had both LSI-RB1 and LSI-D13S319 13q14 deletion (cut-off value: 7%), and the deletion rates detected by probes LSI-RB1 and LSI-D13S319 were accordant. The positive rates of 13q14 deletion were 46.4% and 47.3% respectively when the cut-off level was increased to 20%, and the corresponding rate was 98%. MM patients carrying 13q14 deletion showed 18% - 98% (median value: 72.5%) and 22% - 98.5% (median value: 76.5%) of deleted nuclei involving the RB1 and the D13S319 locus (P = 0.38). There were 67.9% (36 out of 53) and 66% (35 out of 53) cases carrying > 65% of 13q14.1-14.2 and 13q14.3 deleted nuclei as high proportion deletion patients, respectively (P = 0.188). The positive rate of the high proportion deletion patients had still no difference between LSI-RB1 and LSI-D13S319 groups when the cut-off value was defined as 85% (P = 0.439). In conclusion, in this cohort of 112 MM patients, there was no significant difference between the LSI-RB1and LSI-D13S319 probes to detect 13q14 deletion. Both LSI-RB1 and LSI-D13S319 probes can be selected to detect 13q14 deletion in MM patients. All the 53 MM patients with 13q14 deletion had deletions of 13q14.1-14.2 and 13q14.3 regions, which is a large deletion as one of the important characters in MM patients with 13q14 deletion.

[Expression of SOX11 mRNA in mantle cell lymphoma and its clinical significance].

OBJECTIVE: To investigate the expression level of SOX11 mRNA in mantle cell lymphoma (MCL) and other B-cell non-Hodgkin lymphoma (B-NHL) and its prognostic value in MCL. METHODS: The expression level of SOX11 mRNA in 80 B-NHL patients were determined by real-time quantitative RT-PCR, GAPDH was used as internal control. The dispersion of SOX11 expression ratio of groups with different prognostic factors was described by Mann-Whitney U test. RESULTS: The SOX11 mRNA expression level was 2.90 (0.75 - 4.63) in 80 B-NHL patients, and the expression level was significantly higher in MCL than that in other B-NHL (P = 0.014). The SOX11 expression level was statistically lower in the group of MCL with hyperleukocytosis, 12 trisomy, MYC amplification and therapeutic effect < PR (P = 0.042, 0.013, 0.028, 0.009) than that of MCL in other group. But SOX11 expression was not associated with MCL international prognostic index (MIPI) (P = 0.333), lactate dehydrogenase (LDH) (P = 0.790), ATM mutation (P = 0.865) and P53 deletion (P = 0.116). The progression free survival (PFS) and overall survival (OS) were significantly longer in the MCL patients with high level of SOX11 than that of other MCL patients. CONCLUSION: There was statistically significant differences in SOX11 mRNA expression between MCL with other B-NHL. SOX11 maybe a good prognostic factor in MCL.

Bone marrow stromal cells protect myeloma cells from bortezomib induced apoptosis by suppressing microRNA-15a expression.

Despite unsurpassed anti-tumor activity of bortezomib for multiple myeloma (MM), drug resistance has emerged as a challenge, especially when MM cells adhere to the stroma. This study aimed to determine whether bone marrow stromal cells (BMSCs) have a role in the development of chemoresistance in MM. Our data demonstrate that the secretion of interleukin-6 (IL-6), vascular endothelial growth factor (VEGF), and cell-to-cell contact with microenvironment-derived stromal cells from patients with multiple myeloma (MM-BMSCs) significantly decreased the sensitivity of myeloma cells to bortezomib treatment. Mechanistically, we found that microRNA (miRNA)- 15a expression was up-regulated in U266 and NCI-H929 cells treated by bortezomib, which was inhibited by MM-BMSCs. miRNA-15a transfected myeloma cells were arrested in G1/S checkpoint and secreted less VEGF compared to control transfected cells, although no significant difference was found in VEGF mRNA levels. In conclusion, our data suggest that via suppressing miRNA-15a expression, BMSCs provide survival support and protect myeloma cells from bortezomib induced apoptosis.

[Comparative study of genetic aberrations in human multiple myeloma cell lines and newly diagnosed MM by fluorescence in situ hybridization].

Multiple myeloma (MM) is a neoplasm of a terminally differentiated B-cell. Human myeloma cell lines were shown to be suitable model systems for use in various fields of the biological sciences. This study was aimed to investigate the genetic aberrations in human multiple myeloma cell lines. Interphase fluorescence in situ hybridization (FISH) with probes for the regions containing 13q14 (RB-1), 13q14.3 (D13S19), 14q32 (IGHC/IGHV) , 1q12 (CEP1), 17p13 (TP53) were was used to detect 7 HMCL and 85 cases of newly diagnosed MM. FISH with LSI IGH/CCND1 , LSI IGH/FGFR3 and LSI IGH/MAF probes were used to detect t(11;14) (q13;q32) , t(4;14) (p16;q32) and t(14;16) (q32;q23) in HMCL and MM with 14q32 rearrangement. The results showed that molecular cytogenetic aberrations were found in all 7 HMCL, six (85.7%) HMCL simultaneously had 13q14, 13q14.3 deletion. Chromosome 1q21 abnormality was found in six (33.3%) HMCL with at least 3 copies amplifications. Illegitimate 14q32 rearrangement was found in five (71.4%) HMCL, including one with t(11;14), two with t(4;14) and three with t(14;16). 17p13 deletion was detected in 5 HMCL. Chromosomal changes were observed in 85.9% of the 85 cases of newly diagnosed MM. The del(13), 1q12 amplification, del(17p), 14q32 rearrangement, t(11;14), t(4;14), t(14;16) were present in 44.7%, 52.9%, 20%, 62.4%, 27.1%, 24.7% and 3.5% of the patients respectively. There was no significant difference in the prevalence of genetic abnormalities of del(13q), 14q32 rearrangement, 1q12 amplification, t(11;14), t(4;14) except del(17p) and t(14;16). It is concluded that HMCL representative of the most aggressive phase of plasma cell neoplasms accumulated a large amount of genetic aberrations. Loss of p53 are strikingly common in HMCL suggesting that the impairment of the P53 tumor suppressor pathway is an important contributor to extramedullary tumor expansion.

[Effect of mesenchymal stem cells on multiple myeloma cells growth and inhibition of bortezomib induced cell apoptosis].

OBJECTIVE: To investigate the role of mesenchymal stem cells (BMSCs) in multiple myeloma (MM) bone marrow (BM) microenrivonment and their effect on myeloma cells survival and bortezomib induced apoptosis. METHODS: BMSCs were derived from BM of untreated myeloma patients (MM-BMSCs) and healthy donors (HD-BMSCs), respectively. The phenotype, proliferation time and cytokine secretion of MM-BMSCs were detected and compared with HD-BMSCs. Then BMSCs were co-cultured with myeloma cell line NCI-H929 and bortezomib in vitro. The NCI-H929 cells proliferation and bortezomib induced cell apoptosis were investigated. RESULTS: MM-BMSCs and HD-BMSCs were isolated successfully. The phenotype of MM-BMSCs was similar to that of HD-BMSCs. Expressions of CD73, CD105, CD44 and CD29 were positive, but those of CD31, CD34, CD45 and HLA-DR (< 1%) negative. The proliferation time of MM-BMSCs was longer than that of HD-BMSCs (82 h vs 62 h, P < 0.05). Moreover, over-expressions of IL-6 and VEGF in MM-BMSCs culture supernatant were detected as compared with that in HD-BMSCs [(188.8 ± 9.4) pg/ml vs (115.0 ± 15.1) pg/ml and (1497.2 ± 39.7) pg/ml vs (1329.0 ± 21.1) pg/ml, respectively]. MM- BMSCs supported survival of the myeloma cells NCI-H929 and protected them from bortezomib induced cell apoptosis. CONCLUSIONS: MM-BMSCs is benefit for myeloma cells proliferation and against cell apoptosis induced by bortezomib. Over-expression of IL-6 and VEGF maybe play a critical role in these effects.