Human T-cell Lymphoblastic Lymphoma Research Articles

The Expression of Paks and Its Clinical Significance in T-Cell Lymphoblastic Lymphoma

Background: T-cell lymphoblastic lymphoma (T-LBL) is a highly aggressive non-Hodgkin's lymphoma with poor prognosis and lacks of standard treatment approaches. PAK2, a member of the p21 activated kinase (PAKs) family, is a component of the gene-expression-based classifier which made great contributions to prognostic prediction of T-LBL(Cai et al. Leukemia 2020). This study aims to analyze the expression of PAKs in human T-LBL cell lines and tissues to clarify its clinical significance and evaluate the therapeutic activity of PAKs inhibitor in T-LBL. Methods: The mRNA and protein expression levels of PAKs in human T-lymphoid cell lines (H9) and T-LBL cell lines (Jurkat, SUP-T1 and CCRF-CEM) were detected by quantitative real-time PCR and western blot, respectively. We retrospectively collected 69 Formalin-fixed, Paraffin-embedded (FFPE) samples and corresponding clinical information from T -LBL patients between September 2000 and May 2015 at Sun Yat-sen University Cancer Center (SYSUCC). Affymetrix Human Gene 2.0 ST microarray (Thermo Fisher Scientific, Waltham, MA, USA) was used to detect the expression of PAKs. Mann-Whitney U test was used for comparing the expression differences between relapsed and non-relapsed patients. Cumulative relapse-free survival (RFS) time was calculated using the Kaplan-Meier method (Expression level higher than the upper quartile (P75) was defined as PAK1 or PAK 2 high expression. High expression (median as cutoff point) of both PAK1 and PAK2 was defined as PAK1/2 high expression). Pearson's chi-square test and Fisher's exact test were used to compare the distribution of clinical variables. Correlations between PAK1, PAK2 and NOTCH1 were evaluated using Spearman's correlation coefficient. Two PAK inhibitors, PF3758309 (PF) and FRAX597, were used to block PAK kinase activity pharmacologically. Cell viability was determined using the viability assay kit CCK-8. Cell cycle and cell apoptosis were analyzed by flow cytometry. All statistical analyses were performed using SPSS 24.0 software (SPSS, Armonk, NY, USA) or GraphPad Prism 8.0 (GraphPad, La Jolla, CA, USA). A P value < 0.05 was considered significant. The study protocol was approved by the Institutional Review Board of SYSUCC. Results: The mRNA and protein expression levels of PAK1 in T-LBL cell lines of Jurkat, SUP-T1 and CCRF-CEM cell lines were significantly higher than those in T-lymphoid cell lines H9 cell line (P<0.05) (Figure 1). Of the 69 T-LBL patients, 44 (63.8%) were male and the median age at diagnosis was 30 years (range: 16-44). The majority (72.5%) of the patients received acute lymphoblastic leukemia (ALL)-type chemotherapy regimens. The PAK2 mRNA expression level of 32 patients with relapsed disease was significantly higher than that of 37 cases without relapse (P=0.012), and no difference was found in mRNA expression of PAK1, 3, 4, 7(Figure 2). Patients with high PAK1 and PAK2 expression had significantly shorter median RFS than those with low PAK1 and PAK2 expression (PAK1 mRFS 31.5 months vs not reached(NR), HR=3.001, P=0.028; PAK2 mRFS 25.7 months vs NR, HR=3.981, P=0.027)(Figure 3). Patients with high PAK1/2 mRNA expression experienced earlier relapse than patients with low PAK1/2 mRNA expression (mRFS 26.0 months vs NR, HR=2.721, P=0.032)(Figure 3). PAK1/2 mRNA expression was found to be associated with hemoglobin concentration, Ki-67 expression, pleural and pericardia effusion, bone marrow involvement and chemotherapy response (P<0.05)(Table 1). Further, the PAK1 mRNA was correlated with the expression of NOTCH1, which is frequently mutated in T-LBL (r=0.5716, P<0.0001)(Figure 4). The PAK inhibitors PF and FRAX597 demonstrated strong anti-tumor activity in vitro (Table 2). Both inhibitors suppressed cell proliferation in a time- and dose-dependent manner (Figure 5). Both inhibitors induced cell cycle arrest in the G1/0 phase, accompanied by corresponding S phase reductions in all tested cells(Figure 6). The synergistic effect between PAK inhibitor PF and doxorubicin was also observed (Figure 7). Besides, PF could inhibit the phosphorylation of PAK1/2, Cyclin D1 and NF-κB in Jurkat cell line(Figure 8). Conclusions: PAK1 and PAK2 play certain roles in the occurrence and recurrence of T-LBL, and their potential as novel biomarkers deserves further exploring. Our results underscore the potential of PAK inhibitor as effective target therapy for T-LBL. Disclosures No relevant conflicts of interest to declare.

S194-P-FADD as a marker of aggressiveness and poor prognosis in human T-cell lymphoblastic lymphoma.

T-cell lymphoblastic lymphoma is a haematological disease with an urgent need for reliable prognostic biomarkers that allow therapeutic stratification and dose adjustment. The scarcity of human samples is responsible for the delayed progress in the study and the clinical management of this disease, especially compared with T-cell acute lymphoblastic leukaemia, its leukemic counterpart. In the present work, we have determined by immunohistochemistry that S194-P-FADD protein is significantly reduced in a cohort of 22 samples from human T-cell lymphoblastic lymphoma. Notably, the extent of such reduction varies significantly among samples and has revealed determinant for the outcome of the tumour. We demonstrate that Fas-associated protein with death domain (FADD) phosphorylation status affects protein stability, subcellular localization and non-apoptotic functions, specifically cell proliferation. Phosphorylated FADD would be more stable and preferentially localized to the cell nucleus; there, it would favour cell proliferation. We show that patients with higher levels of S194-P-FADD exhibit more proliferative tumours and that they present worse clinical characteristics and a significant enrichment to an oncogenic signature. This supports that FADD phosphorylation may serve as a predictor for T-cell lymphoblastic lymphoma aggressiveness and clinical status. In summary, we propose FADD phosphorylation as a new biomarker with prognostic value in T-cell lymphoblastic lymphoma.

FADD phosphorylation is altered in human T-cell lymphoblastic lymphoma.

FADD phosphorylation is altered in human T-cell lymphoblastic lymphoma.

RNA-Seq reveals the existence of a CDKN1C-E2F1-TP53 axis that is altered in human T-cell lymphoblastic lymphomas

BackgroundPrecursor T-cell lymphoblastic lymphomas (T-LBL) are rare aggressive hematological malignancies that mainly develop in children. As in other cancers, the loss of cell cycle control plays a prominent role in the pathogenesis in these malignancies that is primarily attributed to loss of CDKN2A (encoding protein p16INK4A). However, the impact of the deregulation of other genes such as CDKN1C, E2F1, and TP53 remains to be clarified. Interestingly, experiments in mouse models have proven that conditional T-cell specific deletion of Cdkn1c gene may induce a differentiation block at the DN3 to DN4 transition, and that the loss of this gene in the absence of Tp53 led to aggressive thymic lymphomas.ResultsIn this manuscript, we demonstrated that the simultaneous deregulation of CDKN1C, E2F1, and TP53 genes by epigenetic mechanisms and/or the deregulation of specific microRNAs, together with additional impairing of TP53 function by the expression of dominant-negative isoforms are common features in primary human T-LBLs.ConclusionsPrevious experimental work in mice revealed that T-cell specific deletion of Cdkn1c accelerates lymphomagenesis in the absence of Tp53. If, as expected, the consequences of the deregulation of the CDKN1C-E2F1-TP53 axis were the same as those experimentally demonstrated in mouse models, the disruption of this axis might be useful to predict tumor aggressiveness, and to provide the basis towards the development of potential therapeutic strategiesin human T-LBL.

MicroRNA-374b Suppresses Proliferation and Promotes Apoptosis in T-cell Lymphoblastic Lymphoma by Repressing AKT1 and Wnt-16.

Deregulation of microRNA (miRNA) has been extensively investigated in both Hodgkin and non-Hodgkin lymphomas (NHL); however, little is known about the roles of miRNAs in T-cell lymphoblastic lymphoma (T-LBL). The aim of the present study was to investigate the potential roles of miR-374b in the development and treatment of T-LBL. MiRCURY LNA array was used to generate a miRNA-expressing profile. Real-time quantitative PCR and immunohistochemistry (IHC) were applied to detect the expression of miR-374b, AKT1, and Wnt16 in T-LBL samples. The dual-luciferase reporter assay was conducted to confirm target associations of miR-374b. The tumor-suppressive effect of miR-374b was determined by both in vitro and in vivo studies. The expression of 380 miRNAs was evaluated in five human T-LBL tissues and five infantile thymus samples by microRNA microarrays. Downregulation of miR-374b was frequently detected in primary T-LBL tissues, which was significantly associated with worse overall survival and increased risk of recurrence of the 58 patients enrolled in this study. miR-374b suppressed T-LBL cell proliferation in vitro and in vivo and sensitized cells to serum starvation- and chemotherapeutic agent-induced apoptosis. Furthermore, we characterized two AKT pathway-associated molecules, AKT1 and Wnt16, as direct targets of miR-374b. Consistently, in T-LBL patient tissues, AKT1 and Wnt16 expression was inversely correlated with miR-374b levels, and was an independent predictor of recurrence and survival. Our data highlight the molecular etiology and clinical significance of miR-374b in T-LBL. Targeting miR-374b may represent a new therapeutic strategy to improve therapy and survival for T-LBL patients.

Microrna-374b Suppresses Proliferation and Promotes Apoptosis in T-Cell Lymphoblastic Lymphoma By Repressing Wnt-16 and AKT1 and Is a Promising Predictive Biomarker for Patients Survival

Background: De-regulation of microRNA (miRNA) has been extensively investigated in both Hodgkin (HL) and non-Hodgkin lymphomas (NHL), however, little is known about the roles of miRNAs in T-cell lymphoblastic lymphoma (T-LBL). To understand the involvement of miRNAs in the development and treatment of (T-LBL), miRNA profiles were compared between tumor and corresponding non-tumor tissues.Methods: miRCURY LNA array was used to generate miRNA expressing profile. Real-time quantitative PCR and immunohistochemistry (IHC) were applied to detect the expression of miR-374b, AKT1 and Wnt16 in T-LBL samples. Dual-luciferase reporter assay was conducted to confirm target associations of miR-374b. The tumor suppressive effect of miR-374b was determined by both in-vitro and in-vivo studies.Results: The expression of 380 miRNAs was evaluated in five human T-LBL tissues and correspondence normal peripheral blood T-cells by microRNA microarrays. The down-regulation of miR-374b was frequently detected in primary T-LBL tissues, which was significantly associated with patients worse overall survival (P<0.001) and increasing risk of recurrence (P=0.012). Functional assays demonstrated that miR-374b could suppress T-NHL cells proliferation in vitro and in vivo. Furthermore, miR-374b could also sensitize cells to both serum starvation- and chemotherapeutic agent-induced apoptosis. Significantly, subsequent investigation characterized two AKT pathway associated molecules, AKT1 and Wnt16, as direct targets of miR-374b and account for the effect of miR-374b in T-NHL cells. Consistently, in tissues of our T-LBL patients, AKT1 and Wnt16 expression was inversely correlated with miR-374b levels, and could also be independent predictors of recurrence and survival of these patients.Conclusions: Our data highlight the molecular etiology and clinical significance of miR-374b in T-LBL. Targeting miR-374b may represent a new therapeutic strategy to improve the therapy effect and survival for T-LBL patients. [Display omitted] [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

FAS system deregulation in T-cell lymphoblastic lymphoma

The acquisition of resistance towards FAS-mediated apoptosis may be required for tumor formation. Tumors from various histological origins exhibit FAS mutations, the most frequent being hematological malignancies. However, data regarding FAS mutations or FAS signaling alterations are still lacking in precursor T-cell lymphoblastic lymphomas (T-LBLs). The available data on acute lymphoblastic leukemia, of precursor origin as well, indicate a low frequency of FAS mutations but often report a serious reduction in FAS-mediated apoptosis as well as chemoresistance, thus suggesting the occurrence of mechanisms able to deregulate the FAS signaling pathway, different from FAS mutation. Our aim at this study was to determine whether FAS-mediated apoptotic signaling is compromised in human T-LBL samples and the mechanisms involved. This study on 26 T-LBL samples confirms that the FAS system is impaired to a wide extent in these tumors, with 57.7% of the cases presenting any alteration of the pathway. A variety of mechanisms seems to be involved in such alteration, in order of frequency the downregulation of FAS, the deregulation of other members of the pathway and the occurrence of mutations at FAS. Considering these results together, it seems plausible to think of a cumulative effect of several alterations in each T-LBL, which in turn may result in FAS/FASLG system deregulation. Since defective FAS signaling may render the T-LBL tumor cells resistant to apoptotic cell death, the correct prognosis, diagnosis and thus the success of anticancer therapy may require such an in-depth knowledge of the complete scenario of FAS-signaling alterations.

Down-regulation of specific miRNAs enhances the expression of the gene Smoothened and contributes to T-cell lymphoblastic lymphoma development

Inappropriate activation of the GLI/hedgehog (GLI/Hh) signalling occurs in several human cancers, including haematological neoplasms. However, little is known about its relevance in precursor T-cell lymphoblastic lymphomas (T-LBL) development. Moreover, the mechanisms whereby GLI/Hh signalling is activated in haematological malignancies are not fully clear. Here, we show that the gene Smoothened (SMO), the only non-redundant gene of this pathway, is up-regulated in mouse and human T-LBL. Interestingly, down-regulation of micro-RNAs mmu-miR-30a and mmu-miR-141 as well as hsa-miR-193b clearly contributes to enhance the expression of this gene in mouse and human lymphomas and, subsequently, to activate the GLI/Hh signalling. Activation of the GLI/Hh signalling in T-LBL promotes cell survival and proliferation, since inhibition of the pathway using short-hairpin-RNA-mediated SMO knockdown, or cyclopamine as a specific antagonist, significantly reduces these cellular processes. These findings suggest that sustained SMO up-regulation may contribute to T-LBL development and advocate the use of specific SMO inhibitors or microRNAs-based therapies as an attractive possibility to treat an important subset of T-LBL.

Gene Expression Profiling of Murine T-Cell Lymphoblastic Lymphoma Identifies Deregulation of S-Phase Initiating Genes.

AbstractAbstract 2395Human T-cell lymphoblastic lymphomas (T-LBLs) are neoplasms of immature T-cells and constitute a group of rare, heterogeneous and clinically very aggressive tumors. The molecular pathogenesis that contributes to T-LBL development is not fully elucidated. Since murine T-LBLs are histopathologically and phenotypically comparable to human T-LBLs, mouse models of T-LBLs are ideal to obtain additional insight into the mechanism of T-LBL development in humans. When injected into newborn mice of the NMRI inbred strain, the SL3-3 murine leukemia virus (MLV) induces various types of hematological malignancies, including T-LBLs. The oncogenic effects of the SL3-3 MLV are caused by integration of the viral genome into the host cell DNA through multiple rounds of infection, and subsequent deregulation of nearby cellular genes – a process defined as insertional mutagenesis. If the integration occurs near or within a gene of importance for cancer development, the cell in which the virus has integrated, may gain a growth advantage, eventually leading to malignant transformation and development of a full blown tumor. Screening the murine genome for resulting integration sites in the end-stage tumors, is therefore an efficient method for identifying genes involved in murine and potentially also human T-cell lymphomagenic processes.In a search for genes and pathways implicated in T-cell lymphoblastic lymphoma (T-LBL) development, we used a murine lymphoma model, where mice of the NMRI inbred strain were inoculated with mutants of SL3-3 MLV. The mutants were affected in the glucocorticoid response element and an overlapping E-box of the viral enhancer in the long termial releat. By performing integration analysis on 19 and global gene expression profiling on 22 of the resulting T-LBL tumors, we determined both the effect of the retroviral integrations on the summarized expression of the nearby genes, and the deregulated pathways in the tumors. Fifty two different genes were identified within a 10 kb distance of the retroviral integrations, whereof 15 were specifically involved in G1/S phase transition. Gene expression dot-plots showed an activating effect of the retrovirus on Mr1, Stx6, Cask and Sh3gl3. Gene expression profiling identified increased expression of genes involved in the minichromosome maintenance (Mcm) and origin of recognition (Orc) pathway as well as downregulation in negative regulators of G1/S transition, indicating that murine T-LBLs have increased S-phase initiation. In conclusion, both the integration analysis and patterns of mRNA expression identified by gene expression profiling in the mouse models of T-LBL strongly indicate that genes involved in G1/S phase transition and/or S-phase initiation are deregulated suggesting similar mechanisms to be of importance in human T-LBL pathogenesis. Disclosures:No relevant conflicts of interest to declare.

Methylation status of cyclin-dependent kinase inhibitor genes within the transforming growth factor beta pathway in human T-cell lymphoblastic lymphoma/leukemia

Epigenetic silencing of downstream components of the transforming growth factor beta pathway including the cyclin-dependent kinase inhibitors (CDKIs) p15INK4B, p27KIP1 and p21CIP1 is implicated in the pathogenesis of some hematological malignancies. Loss of p15INK4B expression due to promoter methylation occurs frequently in human T-cell acute lymphoblastic leukemia (T-ALL) but the expression and methylation status of p27KIP1 remains to be characterized in T-ALL or T-cell lymphoblastic lymphoma (T-LBL). As well, while some have reported a high frequency of p21CIP1 methylation in ALL patient samples others have found the gene to be unmethylated in this disease and the relationship between p21CIP1 expression and promoter methylation has not been examined in T-LBL. Using RNase protection assays (RPA) and methylation specific PCR (MSP), we found p27KIP1 to be expressed and its promoter unmethylated in 20 of 20 (100%) and 28 of 28 (100%) T-LBL/ALL samples, respectively. In contrast, p21CIP1 mRNA was absent in 7 of 14 (50%) T-LBL biopsies and 5 of 6 (83%) T-ALL cell lines. However, like p27KIP1 there was no evidence of p21CIP1 promoter methylation by MSP or temporal temperature gradient electrophoresis (TTGE) analysis of 35 CpG sites in any of the 28 T-LBL/ALLs analyzed. Similar to T-ALL, we found p15INK4B mRNA was absent in 13 of 14 (93%) T-LBL biopsies and its promoter methylated in 6 of 10 (64%) cases. Our results indicate that p21CIP1 mRNA is absent in human T-LBL biopsies and T-ALL cell lines at a high frequency. However, unlike p15INK4B, reduced p21CIP1 expression in T-LBL/ALL is independent of dense promoter-associated CpG methylation. In contrast to some hematological malignancies p27KIP1 methylation does not appear to contribute significantly to T-LBL/ALL pathogenesis.