Functional Characterization of HLA SNPs Associated with Risk of Follicular Lymphoma

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1551-1551
Author(s):  
Christine F. Skibola ◽  
Lucia Conde ◽  
Martyn T. Smith ◽  
Fenna C.M. Sille
Keyword(s):  
Gene Expression ◽  
Flow Cytometry ◽  
Protein Structure ◽  
Protein Expression ◽  
Follicular Lymphoma ◽  
Wild Type ◽  
Extended Haplotype ◽  
Protein Levels ◽  
Risk Alleles ◽  
Hla Dqa1

Abstract Abstract 1551 Background: Genome-wide association studies (GWAS) suggest an important role of genetic variation in the etiology of follicular lymphoma (FL). Multiple susceptibility alleles in the human leukocyte antigen (HLA) Class I and II regions on chromosome 6p21.33–32 have been identified for FL, including rs10484561 (OR = 1.95, P = 1.12×10−29) and rs2647012 SNP (OR = 0.64, P = 2×10−21) (Conde et al., Nat Gen, 2010; Smedby et al. Plos Gen, 2011). Moreover, high-resolution HLA typing using next-generation sequencing has identified a number of HLA alleles associated with FL including the extended haplotype DRB1*01:01—DQA1*01:01—DQB1*05:01 that is in complete linkage disequilibrium with rs10484561 (D'=1), and DRB1*15-DQA1*01-DQB1*06, which is highly correlated with rs2647012 (D'=1) (Skibola et al., Tissue Antigens, 2012). We hypothesized that these SNPs or protein variants may alter immune responses to specific antigens and influence tumor development through effects on gene expression or protein structure. To gain a further understanding of the mechanisms involved, here we explored the effects of HLA alleles on expression at the transcriptional and protein level. Methods: HLA-DRB1, HLA-DQB1 and HLA-DQA1 mRNA expression and protein levels were measured by RT-qPCR and flow cytometry, respectively, in 40 lymphoblastoid cell lines (Coriell) where wild type and variant rs10484561 and rs2647012 genotypes were compared. Results: HLA-DQB1 gene expression changes were significantly associated with rs2647012 genotypes, where the presence of the variant (protective) allele correlated with higher HLA-DQB1 transcript levels. Flow cytometry with HLA-specific antibodies and pan-HLA antibodies (against DR/DQ/DP) also confirmed that the variant rs2647012 allele was associated with higher HLA-DQB1 protein levels. No significant changes were observed in HLA-DRB1, HLA-DQB1 or HLA-DQA1 transcript or protein levels when comparing rs10484561 wild type versus variant alleles. Conclusions: We did not detect significant differences in transcript or surface protein levels based on rs10484561 genotypes. These findings suggest that the increased risk of FL associated with rs10484561 that is in high LD with the HLA-DRB1*0101—DQA1*0101—DQB1*0501 extended haplotype is not due to transcriptional modulation, but may be due to effects on protein structure. On the other hand, the protective rs2647012 variant was associated with higher HLA-DQB1 mRNA and protein expression, suggesting that rs2647012 or a SNP in LD influences FL risk through effects on gene expression. We are currently testing the influence of additional FL risk alleles in the 6p21.3 region on HLA gene and protein expression, as well as investigating whether FL risk alleles alter HLA expression in other cell types. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Role of Sigma Factors in Controlling Global Gene Expression in Light/Dark Transitions in the Cyanobacterium Synechocystis sp. Strain PCC 6803

2007 ◽  
Vol 189 (21) ◽  
pp. 7829-7840 ◽  
Author(s):  
Tina C. Summerfield ◽  
Louis A. Sherman
Keyword(s):  
Gene Expression ◽  
Global Gene Expression ◽  
Growth Conditions ◽  
Day Length ◽  
Regulation Of Transcription ◽  
Wild Type ◽  
Protein Levels ◽  
In The Wild ◽  
Altered Gene ◽  
Pcc 6803

ABSTRACT We report on differential gene expression in the cyanobacterium Synechocystis sp. strain PCC 6803 after light-dark transitions in wild-type, ΔsigB, and ΔsigD strains. We also studied the effect of day length in the presence of glucose on a ΔsigB ΔsigE mutant. Our results indicated that the absence of SigB or SigD predominately altered gene expression in the dark or in the light, respectively. In the light, approximately 350 genes displayed transcript levels in the ΔsigD strain that were different from those of the wild type, with over 200 of these up-regulated in the mutant. In the dark, removal of SigB altered more than 150 genes, and the levels of 136 of these were increased in the mutant compared to those in the wild type. The removal of both SigB and SigE had a major impact on gene expression under mixotrophic growth conditions and resulted in the inability of cells to grow in the presence of glucose with 8-h light and 16-h dark cycles. Our results indicated the importance of group II σ factors in the global regulation of transcription in this organism and are best explained by using the σ cycle paradigm with the stochastic release model described previously (R. A. Mooney, S. A. Darst, and R. Landick, Mol. Cell 20:335-345, 2005). We combined our results with the total protein levels of the σ factors in the light and dark as calculated previously (S. Imamura, S. Yoshihara, S. Nakano, N. Shiozaki, A. Yamada, K. Tanaka, H. Takahashi, M. Asayama, and M. Shirai, J. Mol. Biol. 325:857-872, 2003; S. Imamura, M. Asayama, H. Takahashi, K. Tanaka, H. Takahashi, and M. Shirai, FEBS Lett. 554:357-362, 2003). Thus, we concluded that the control of global transcription is based on the amount of the various σ factors present and able to bind RNA polymerase.

scholarly journals Electroporation-mediated delivery of catalytic oligodeoxynucleotides for manipulation of vascular gene expression

2003 ◽  
Vol 285 (5) ◽  
pp. H2240-H2247 ◽  
Author(s):  
Elizabeth A. Nunamaker ◽  
Hai-Ying Zhang ◽  
Yuichi Shirasawa ◽  
Joseph N. Benoit ◽  
David A. Dean
Keyword(s):  
Gene Expression ◽  
Experimental Studies ◽  
Wild Type ◽  
Protein Levels ◽  
Dna Oligonucleotides ◽  
Pkc Isoforms ◽  
Cell Layers ◽  
Cultured Smooth Muscle Cells ◽  
Decrease Gene Expression

The development of inexpensive and effective approaches to transiently decrease gene expression in vivo would be useful for the study of physiological processes in living animals. DNAzymes are a novel class of DNA oligonucleotides that can catalytically cleave target mRNAs and thereby reduce protein production. However, current methods for their delivery in vivo are limited and inefficient. In this study, we show that electroporation can be used to deliver DNAzymes to the intact mesenteric vasculature of rats. With the use of PKC-ϵ as a target, a set of wild-type and mutant control DNAzymes was designed and shown to reduce both PKC-ϵ mRNA and protein levels in cultured smooth muscle cells in a specific manner. The wild-type DNAzyme reduced PKC-ϵ protein levels by 70% at 24 h in two different cell lines without decreasing the levels of the five other PKC isoforms tested. When delivered to the intact vasculature using electroporation, the DNAzyme reduced PKC-ϵ protein levels by >60% without affecting these other PKC isoforms. Electroporation was required for oligonucleotide transfer and was able to deliver the DNAzymes to multiple cell layers in the vessel wall. Protein levels were reduced maximally by 24 h postelectroporation and returned to normal by 48 h. These results suggest that electroporation can be used to deliver DNAzymes and other DNA oligonucleotides to the vasculature in vivo and can decrease gene expression for a window of time that can be used for experimental studies.

Cold-induced RNA-binding protein (CIRBP) regulates the expression of Src-associated during mitosis of 68 kDa (Sam68) and extracellular signal-regulated kinases (ERK) during heat stress-induced testicular injury

2020 ◽  
Vol 32 (18) ◽  
pp. 1357
Author(s):  
Chengcheng Xu ◽  
Dandan Ke ◽  
Liping Zou ◽  
Nianyu Li ◽  
Yingying Wang ◽  
...  
Keyword(s):  
Gene Expression ◽  
Heat Stress ◽  
Protein Expression ◽  
Rna Binding ◽  
Cell Model ◽  
Binding Protein ◽  
Rna Binding Protein ◽  
Protein Levels ◽  
Extracellular Signal ◽  
Testicular Injury

In this study, the ability of cold-induced RNA-binding protein (CIRBP) to regulate the expression of Src-associated during mitosis of 68 kDa (Sam68) and extracellular signal-regulated kinases (ERK) in the mouse testis and mouse primary spermatocytes (GC-2spd cell line) before and after heat stress was examined to explore the molecular mechanism by which CIRBP decreases testicular injury. A mouse testicular hyperthermia model, a mouse primary spermatocyte hyperthermia model and a low CIRBP gene-expression cell model were constructed and their relevant parameters were analysed. The mRNA and protein levels of CIRBP and Sam68 were significantly decreased in the 3-h and 12-h testicular heat-stress groups, extracellular signal-regulated kinase 1/2 (ERK1/2) protein expression was not significantly affected but phospho-ERK1/2 protein levels were significantly decreased. GC-2spd cellular heat-stress results showed that the mRNA and protein concentrations of CIRBP and Sam68 were reduced 48h after heat stress. In the low CIRBP gene-expression cell model, CIRBP protein expression was significantly decreased. Sam68 mRNA expression was significantly decreased only at the maximum transfection concentration of 50nM and Sam68 protein expression was not significantly affected. These findings suggest that CIRBP may regulate the expression of Sam68 at the transcriptional level and the expression of phospho-ERK1/2 protein, both of which protect against heat-stress-induced testicular injury in mice.

Upregulation of the Anti-Apoptotic Protein, Survivin, in Hematopoietic Cells in Sickle Cell Anemia and Effects of Hydroxyurea Therapy.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 1532-1532
Author(s):  
Carolina Lanaro ◽  
Carla Fernanda Franco-Penteado ◽  
Mariana R. B. Mello ◽  
Kleber Yotsumoto Fertrin ◽  
Marcos André C Bezerra ◽  
...  
Keyword(s):  
Gene Expression ◽  
Protein Expression ◽  
Sickle Cell Anemia ◽  
Survivin Expression ◽  
Erythroid Differentiation ◽  
Mrna Levels ◽  
Gene Expressions ◽  
Protein Levels ◽  
Survivin Protein ◽  
Inflammatory State

Abstract Abstract 1532 Poster Board I-555 Survivin (BIRC5) is a member of the inhibitors of apoptosis family implicated in both prevention of cell death and control of mitosis. Although the actions of survivin in control of cancer cell division and apoptosis have been studied, its role in nonneoplastic diseases is not elucidated. Chronic inflammation is associated with STAT-3 upregulation, which can induce survivin production. Sickle cell anemia (SCA) has been characterized as a chronic inflammatory state and growing evidence indicates that inflammatory stress within the microvasculature may play a significant role in the vasoocclusion that is characteristic of SCA. Long-term treatment with hydroxyurea (HU) has been shown to reduce the production of inflammatory cytokines in SCA patients and leukocyte number. Since enhanced survivin expression has been reported in leukocytes under inflammatory conditions, and during hematopoietic cell survival and proliferation, the aim of this study was to investigate changes in survivin levels during erythroid differentiation, and determine expression in neutrophils (NS), mononuclear cells (MC) and red blood cell (RBC) in steady-state SCA patients (n≥10), SCA patients on HU therapy (n≥16), and healthy controls (HC, n≥5). Survivin and STAT-3 gene expression were determined by qRT-PCR analysis in primary human erythroblasts cultures for 7, 10 and 13 days and leukocytes separated from peripheral blood samples. Survivin protein expression was determined by flow cytometry with survivin-specific antibodies. Survivin gene expression was significantly increased during erythroid differentiation, but survivin mRNA levels showed similar patterns between SCA and HC (7d: 0.8±0.1 × 0.7±0.08; 10d: 1.7±0.3 × 1.6±0.2; 13d: 2.2± 0.27 × 1.8±0.19,U.A.,P>0.05,respectively). However, protein levels of survivin in mature RBC (glicophorin A +) was significantly higher in SCA patients compared to HC (41.90± 2.9 × 25.76±1.9, P=0.0006, respectively). BIRC-5 gene expression in MC was significantly higher in SCA patients compared to HC (0.9±0.1 × 0.5±0.2, P=0.04, respectively). Survivin protein levels in MC from SCA was significantly increased to compared to HC (51.7±3.2 × 39.7±1.7, MFI, P=0.01,respectively). Survivin protein levels are elevated in NS of SCA patients compared to HC (28.4±1.6 × 21.9±1.5, MFI, P=0.02,respectively). No significant alterations in the mRNA levels of the gene encoding STAT-3 were found during erythroid differentiation (7d: 1.1±0.04 × 1.1±0.08; 10d: 0.6±0.07 × 0.8±0.08; 13d: 0.6±0.07 × 0.9±0.1, P>0.05,respectively) or MC cells (1.2±0.1 × 1.1± 0.1, P>0.05,respectively) in SCA patients compared to HC. Patients on HU therapy demonstrated lower survivin MC gene expressions and protein levels compared to non-treated patients (0.6±0.3 × 0.9±0.1; 37.9±1.5 × 51.7±3.3, P=0.02; P<0.0001,respectively), but no difference was shown in STAT-3 gene expressions (1.1±0.04 × 1.2 ±0.1, respectively). Survivin protein levels were not significantly different in NS and RBC in patients on HU therapy compared to SCA (27.1±1.8 × 28.4± 1.6; 45.9± 3.2× 41.9± 2.9, MFI, P>0.05, respectively). Our data showed that survivin gene and protein expression are upregulated in MC in SCA patients, independently of STAT-3 expression. In addition, a high protein expression was observed in NS and RBC in these patients. HU therapy was associated with lower survivin expression in MC, but not NS and RBC, indicating that the beneficial effect that HU has on the inflammatory state, may participate in the reduced levels of survivin. In conclusion, the exact importance of survivin in SCA vasooclusion is not clear, but data indicates a high expression of this protein in leukocytes and RBC of SCA patients and may imply a role for this protein in leukocytosis and RBC proliferation in SCA. Disclosures No relevant conflicts of interest to declare.

Role for PP2A Regulatory Subunit B55α as A Regulator of AKT and Other Signaling Pathways In AML.

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 1668-1668
Author(s):  
Peter P. Ruvolo ◽  
YiHua Qui ◽  
Kevin R Coombes ◽  
Nianxiang Zhang ◽  
Vivian Ruvolo ◽  
...  
Keyword(s):  
Gene Expression ◽  
Bone Marrow ◽  
Protein Expression ◽  
Normal Bone Marrow ◽  
Protein Levels ◽  
B Subunit ◽  
Normal Bone ◽  
Cd34 Cells ◽  
Blast Cells ◽  
B Subunits

Abstract Abstract 1668 Activation of survival kinases such as Protein Kinase B (AKT), Protein Kinase C (PKC), and Extracellular Receptor Activated Kinase (ERK) predict poor clinical outcome for patients with acute myeloid leukemia (AML; Kornblau et al Blood 2006). A better understanding of how the activities of these kinases are regulated by phosphorylation and dephosphorylation will enable the development of targeted therapies directed against this axis. Protein Phosphatase 2A (PP2A) negatively regulates PKC, AKT, and ERK but its role in AML is not clear. In the current study we examined the role of PP2A in regulating AKT in AML. Activation of AKT involves phosphorylation of threonine 308 (T308) and serine 473 (S473). A recent study has indicated that phosphorylation of AKT at T308 but not S473 is a poor prognostic factor for AML patients and that PP2A activity negatively correlated with T308 phosphorylation (Gallay et al Leukemia 2009). PP2A is a family of different isoforms that form hetero-trimers consisting of a catalytic C subunit, a scaffold A subunit, and one of at least 21 different regulatory B subunits. The functionality of each PP2A isoform is determined by the regulatory B subunit. Thus to understand PP2A regulation of AKT in AML, it is essential to study the B subunit that regulates the AKT phosphatase. The PP2A isoform regulating AKT in the AML patients is currently unknown. Evidence suggests that the B55a subunit is responsible for dephosphorylation of AKT at T308. In the current study, we compared B55α gene expression in blast cells derived from AML patients with normal counterpart (i.e. CD34+) cells derived from normal bone marrow donors by real time PCR. Surprisingly, B55α gene expression was higher in the patients. Reverse Phase Protein Analysis (RPPA) is a powerful tool that allows for the analysis of protein expression from patient samples. Protein levels of the PP2A B subunit were analyzed by RPPA in AML blast cells obtained from 511 newly diagnosed AML patients and CD34+ cells obtained from 11 normal bone marrow donors. Levels of B55α protein were significantly lower in the blast cells from the AML patients compared to normal CD34+ cells. While the mechanism for the observed difference in gene versus protein expression in the leukemia cells has yet to be determined, a plausible mechanism is that the B55α protein is being proteolyzed since monomeric PP2A B subunits that are not part of the PP2A hetero-trimer are degraded. Importantly the reduced levels of B55α protein observed would be predicted if AKT were activated in the AML blast cells. We next compared AKT phosphorylation status with B55α protein expression in the AML blast cells using RPPA to answer this question. Analysis of RPPA data revealed that there was no correlation between B55α protein levels and levels of total AKT protein or with levels of AKT phosphorylated at S473 in the AML samples. However, there was a moderate but significant negative correlation between B55α protein levels and levels of AKT phosphorylated at T308. This result suggests that B55α is mediating dephosphorylation of AKT at T308 but not S473 in the AML cells. B55α expression was not associated with FAB classification but was positively correlated with high blast and peripheral blood counts. While the level of expression of the B subunit did not correlate with overall survival, intermediate levels of B55α expression were associated with longer complete remission duration. We predict that higher levels of B55α would reflect low levels of other PP2A B subunits. Consistent with this prediction, B55α expression positively correlated with MYC expression in the AML patients. MYC expression is regulated by a B subunit that competes with B55α (i.e. B56α). These findings suggest that B55α may play an important role in AML as a negative regulator of AKT and perhaps by other as yet unidentified functions. Activation of B55α is a potential therapeutic target for overcoming the AKT activation frequently observed in AML. Disclosures: No relevant conflicts of interest to declare.

MET overexpression as a hallmark of the epithelial-mesenchymal transition (EMT) phenotype in colorectal cancer.

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. 3529-3529 ◽  
Author(s):  
Kanwal Pratap Singh Raghav ◽  
Hesham M. Amin ◽  
Wenting Wang ◽  
Ganiraju C. Manyam ◽  
Bradley Broom ◽  
...  
Keyword(s):  
Gene Expression ◽  
Colorectal Cancer ◽  
Overall Survival ◽  
Protein Expression ◽  
Protein Gene ◽  
Epithelial Mesenchymal Transition ◽  
Mesenchymal Transition ◽  
Gene Signatures ◽  
Protein Levels ◽  
Emt Markers

3529 Background: Epithelial-mesenchymal transition (EMT) has been identified as a dominant molecular subtype of colorectal cancer (CRC). This EMT phenotype as recognized by complex gene signatures is prognostic and associated with chemoresistance, but a biomarker for EMT suitable for clinical utilization has not yet been validated. The purpose of this study was to compare MET protein expression with protein/gene expression of EMT markers and to evaluate its impact on overall survival (OS). Methods: We performed an exploratory analysis of 139 untreated primary CRC samples using data from The Cancer Genome Atlas. Protein and gene expressions were measured using reverse-phase protein array (RPPA) and RNA-sequencing, respectively. MET high/overexpressed group was defined by protein level in the highest quartile. Mann-Whitney U-test and Spearman rank correlation was used to determine association between MET protein expression and protein/gene expression of EMT markers and EMT gene signature scores. Regression tree method and Kaplan-Meier estimates were used to assess overall survival (OS). Results: The MET protein distribution is right skewed, demonstrating a unique population of MET high expressing tumors (P < 0.01). Colon tumors had higher MET protein levels compared to rectal tumors (P < 0.01). MET overexpression was associated with decreased OS (HR 2.92; 95% CI: 1.45 - 5.92). MET protein expression correlated strongly with protein expressions of SLUG (transcription factor for EMT) (r = 0.6) and ERCC1 (a marker for oxaliplatin chemo-resistance) (r = 0.6) (P < 0.01). Higher MET protein levels were associated with higher gene expression of 28 EMT markers including AXL, VIM, ZEB1, ZEB2, FGF1, TGFB1I1 and MMP11 (P < 0.05). Higher MET protein levels were also associated with higher gene scores derived from three published EMT gene signatures (P < 0.05). MET protein expression did not correlate with MET gene expression (r = 0.16). Conclusions: Increased MET protein expression strongly correlates with a molecular EMT phenotype and poor survival in patients with CRC. MET protein expression may be used as a surrogate biomarker to represent and select for this unique molecular subset of CRC driven by EMT biology.

Tumor-Infiltrating T Cells Are Not Predictive of Clinical Outcome in Follicular Lymphoma.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 824-824 ◽  
Author(s):  
Wei Yun Z. Ai ◽  
Debra Czerwinski ◽  
Sandra J. Horning ◽  
John Allen ◽  
Robert Tibshirani ◽  
...  
Keyword(s):  
Gene Expression ◽  
Flow Cytometry ◽  
Overall Survival ◽  
T Cells ◽  
Clinical Outcome ◽  
Follicular Lymphoma ◽  
Clinical Features ◽  
Training Set ◽  
Hla Dr ◽  
Validation Set

Abstract Background: Follicular lymphoma (FL) has variable clinical outcomes. It has been suspected that tumor-infiltrating immune cells affect the biology and outcome of this disease. Using gene expression profiling and immunoperoxide tissue staining techniques, T cells and macrophages have been related to the survival outcome in some studies, but not others. In the current study, we used flow cytometry to analyze T cells and their subsets in follicular lymphoma biopsy specimens and determined whether these cell populations correlated with clinical features and outcomes. Methods: Two hundred and eighty-nine follicular lymphoma patients (pt) presented from 1997 to 2003 underwent an excisional lymph node biopsy prior to any treatment. The median age of pt at diagnosis was 45.7 yrs, median follow-up was 8.6 yrs for living pts, and median survival was 15.7 yrs. All but 8 patients had stage III/IV disease, 5 had stage I/II, and 3 were unknown. The histological grades were: 162 (56%) grade 1, 112 (39%) grade 2, 13 (4.5%) grade 3 and 2 (0.5%) unknown. Among the 289 patients, 41(17%) had low FLIPI score, 150 (63%) intermediate, 48 (20%) high and 50 unknown. All biopsies were analyzed for CD20, CD3, CD4, CD8 and HLA-DR expression by single-parameter flow cytometry. The 289 pts were divided into a training set of 147 and a validation set of 142, stratified by age and era of diagnosis. We used these two factors to stratify the pts because age at diagnosis is the most important prognostic factor for survival, and, in our data set, the era of diagnosis had an impact on survival and on the time from diagnosis to first treatment. For our analysis, we began with the training set and used the percentages of each immune cell population as a continuous variable in a univariate analysis in relation to clinical features and outcomes. We chose 8 phenotypic variables: CD20, CD3, CD4, CD8, HLA-DR, CD4/CD3 ratio, CD8/CD3 ratio, and activated T cells [defined as (HLA-DR-CD20)/CD3]. Five parameters were used as clinical endpoints: overall survival, FLIPI score at diagnosis, the time from diagnosis to first treatment (defined as the time from the first treatment to second treatment), response to CVP as the first treatment and the duration of the benefit from the first treatment (defined as the time interval between initiation of first treatment and initiation of second treatment). Results: The number of pt evaluable for each of the outcome parameters was as follows: 289 for time to first treatment and for overall survival, 239 for FLIPI scores, 164 for response to CVP and 129 for duration of the benefit from the first treatment., Of the 8 variables tested in the training set, only CD4/CD3 ratio and CD8/CD3 ratio were marginally significant for the survival endpoint, with p 0.034 and 0.088, respectively. None of the variables was significant for any of the other endpoints. A multivariate analysis yielded CD4/CD3 as the only significant predictor for survival. When CD4/CD3 was tested in the validation set, it yielded a p value of 0.48. Conclusion: We find no evidence that the percentage of tumor-infiltrating T cells or their subsets is predictive of clinical outcome in follicular lymphoma. Any gene expression signature involving T cells that does relate to clinical outcome could therefore be a property of the activity of the cells rather than a simple reflection of their numbers.

TYK2-STAT1 Pathway Positively Regulates BCL2 Gene Expression in T-Cell Acute Lymphoblastic Leukemia

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 1470-1470
Author(s):  
Takaomi Sanda ◽  
Jeffrey W Tyner ◽  
Alejandro Gutierrez ◽  
Vu N Ngo ◽  
Jason M Glover ◽  
...  
Keyword(s):  
Gene Expression ◽  
Acute Lymphoblastic Leukemia ◽  
T Cell ◽  
Protein Expression ◽  
Cell Lines ◽  
Lymphoblastic Leukemia ◽  
Wild Type ◽  
Cell Acute Lymphoblastic Leukemia ◽  
Bcl2 Protein ◽  
Bcl2 Expression

Abstract Abstract 1470 To discover oncogenic pathways that are characteristically deregulated in T-cell acute lymphoblastic leukemia (T-ALL), we performed RNA interference screens both in T-ALL cell lines and primary specimens. We found that the JAK tyrosine kinase family member, TYK2, and its downstream effector, STAT1, are each required for the survival of T-ALL cells. To identify the effector molecules downstream of the TYK2-STAT1 pathway in T-ALL, we analyzed global gene expression profiles in TYK2-dependent T-ALL cell lines after silencing of TYK2 or STAT1. As expected, gene set enrichment analysis revealed that genes downregulated by TYK2 knockdown were generally also downregulated by knockdown of STAT1. Importantly, we found that expression of the anti-apoptotic gene BCL2 was significantly downregulated after silencing of both TYK2 and STAT1. Analysis by quantitative PCR of additional T-ALL cell lines revealed that silencing of TYK2 resulted in significant reductions of BCL2 mRNA expression in multiple TYK2-dependent cell lines. Expression of the wild-type but not the kinase-dead TYK2 protein was sufficient to rescue BCL2 protein expression and to prevent apoptosis after knockdown of endogenous TYK2, indicating that the tyrosine kinase activity of TYK2 is required for BCL2 upregulation. Similarly, expression of the shRNA-resistant wild-type STAT1A protein partially rescued BCL2 protein expression and prevented apoptosis, while a variant of STAT1A (Y701F) that is incapable of becoming phosphorylated on a requisite tyrosine residue did not rescue BCL2 levels. Taken together, our findings indicate that aberrant activation of a TYK2-STAT1 pathway upregulates BCL2 expression in T-ALL cells, and that the T-ALL cells develop pathway dependence, in that they require these sustained high levels BCL2 expression for survival. Disclosures: No relevant conflicts of interest to declare.

Proliferating CLL Cells Express Abundant But Transcriptionally Compromised TP53 Protein

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 4134-4134 ◽  
Author(s):  
Jesvin J Samuel ◽  
Alice H Wignall ◽  
Hishyar Najeeb ◽  
Aneela Majid ◽  
Sandrine Jayne ◽  
...  
Keyword(s):  
Dna Damage ◽  
Protein Expression ◽  
Time Course ◽  
Target Genes ◽  
Wild Type ◽  
Proliferating Cells ◽  
Protein Levels ◽  
L Cells ◽  
High Level ◽  
Tp53 Protein

Abstract Current models of CLL pathogenesis invoke specialized microenvironments within the lymph nodes and bone marrow that harbor proliferating cells. Such proliferating CLL cells are more resistant to current immuno-chemotherapeutic regimens than cells in the peripheral blood and are thought to be the cause of resistant disease. Various models have been used to recapitulate these CLL proliferation centers in vitro, including stimulating cells with CD154 and IL4. We studied 40 patients (6 with p53 mutations/deletions) using this system and observed that >50% of CLL cells undergo proliferation after 72 hours of stimulation, as assessed by Ki67 staining. Unexpectedly, under these conditions we also observed a 30-40 fold induction of TP53 protein in all cases of CLL analyzed, irrespective of TP53 mutational status. Nearly all cells showed increased TP53 protein expression (Figure 1), suggesting that such high-level TP53 protein expression did not hinder cell proliferation. Given that induction of wild-type TP53 protein usually induces cell cycle arrest if not apoptosis, we examined for transcriptional up-regulation of TP53 target genes using a combination of qRT-PCR, RNA arrays and RNA-Seq approaches. 4 out of 12 cases showed induction of some TP53 target genes, but overall there was no consistent pattern of transcriptional up-regulation of target genes, suggesting that the induced TP53 is transcriptionally compromised in CLL cells following CD154/IL4 stimulation. In contrast, DNA damage induced by doxorubicin in CD154/IL4 stimulated cells induced wild type TP53 protein to even higher levels, resulting in TP53 target gene up-regulation and apoptosis, as expected. CD154/IL4 stimulation also induced a 10-fold elevation in ROS levels in all cases. This resulted in significant oxidative DNA damage, as measured by a modified comet assay, which could explain the induction of TP53 in proliferating cells. qRT-PCR and RNA-Seq experiments failed to show a significant increase in TP53 mRNA levels, indicating that elevation of TP53 protein levels was occurring post-transcriptionally. Increased phosphorylation of TP53 at S15 was seen in all cases, which may account for the observed increased protein stability through dissociation from MDM2. All TP53 mRNA isoforms expressed retained transcriptional activation and DNA binding domains. In view of these results, we propose a model whereby oxidative stress induced by proliferation in CLL triggers TP53 protein expression. TP53 becomes phosphorylated but, for reasons that remain unclear, is unable to transactivate its target genes normally and induce cell-cycle arrest. Apoptosis could be suppressed by high-level expression of anti-apoptotic BCL2 proteins. However, TP53 remains able to trigger a full apoptotic response after further DNA damage and a higher threshold of protein levels is reached. Reactivation of the full transcriptional activities of wild-type TP53 in proliferating CLL cells may provide a new therapeutic approach.Figure 1CD154/IL4 stimulation increases CLL proliferation and induces TP53 expression. Top panel: Time course of Ki67 and TP53 expression in CD19+ CLL cells stimulated with rhCD154 and rhIL4. Bottom panel: Representative immunoblot of TP53 expression in CLL cells after 1, 3 and 7 days of co-culture with mouse L cells (NTL) or rhCD154 transfected-L Cells and rhIL4.Figure 1. CD154/IL4 stimulation increases CLL proliferation and induces TP53 expression. Top panel: Time course of Ki67 and TP53 expression in CD19+ CLL cells stimulated with rhCD154 and rhIL4. Bottom panel: Representative immunoblot of TP53 expression in CLL cells after 1, 3 and 7 days of co-culture with mouse L cells (NTL) or rhCD154 transfected-L Cells and rhIL4. Disclosures: No relevant conflicts of interest to declare.

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