Natural killer/T-cell Lymphoma Cell Research Articles

Abstract 7276: Potent anti-proliferative activity of brincidofovir in Diffuse Large B-cell Lymphoma with overexpression of transcriptional repressor TLE1

Abstract Introduction: Brincidofovir (BCV) is a biologically-active acyclic nucleoside phosphonate and clinically-approved anti-viral agent. Recently, BCV has been demonstrated to display potent anti-proliferative and immunogenic properties in NK/T cell lymphoma (NKTCL). However, its effect on other lymphoma types remain unclear. Methods: We investigated BCV in an expanded cohort of B-cell lymphoma cell-lines (diffuse large B-cell lymphoma [DLBCL], n = 16; Burkitt lymphoma, n = 2; Hodgkin lymphoma, n = 1), in comparison with NKTCL cell lines (n = 11). Mouse xenograft models were deployed to assess in vivo effects. Whole transcriptomic sequencing (RNAseq) was performed to examine Epstein-Barr virus (EBV) status and explore potential mechanisms of action. Results: BCV inhibited viability in all B-cell lymphoma cell-lines in a dose-dependent manner (IC50 0.0798 to 8.414 µg/ml). Marked sensitivity (IC50 < 1 µg/ml) was demonstrated in nine cell-lines, including the MYC/BCL2-rearranged double-hit DLBCL cell-line OCI-LY18 (IC50 0.5 µg/ml). Intraperitoneal BCV (40 mg/kg, 2X per week) inhibited tumor growth in NOD/SCID mice OCI-LY18 xenografts, compared with vehicle alone (p < 0.001, two-tailed t-test). RNAseq showed that most cell-lines (n = 16) were EBV negative. Interestingly, the transcriptional repressor TLE1 was amongst the top upregulated genes in the BCV-sensitive cell-lines (log2foldchange = 8.12, adjusted p = 0.0004). DLBCL patient samples from two independent datasets showed that TLE1-high tumors conferred worse overall survival (GSE11318, n = 200: HR 2.77, 95%CI 1.78 to 4.30, p < 0.0001; GSE10846, n = 414: HR 1.94, 95%CI 1.35 to 2.80, p = 0.0004). Gene set enrichment analysis showed that pathways involved in oxidative phosphorylation and oncogenic signaling were significantly upregulated in the BCV-resistant cell-lines compared to the rest. Notably, these findings are in stark contrast to NKTCL, in which TLE1 loss instead confers BCV sensitivity in vitro and is associated with poor survival outcomes in patients (n = 36; HR 3.44, 95% CI 1.23-10.49, p = 0.0301). Conclusions: Taken together, these results suggest that BCV may be a potential novel therapeutic agent for the treatment of B-cell lymphomas. Further work will be required to investigate the role of TLE1 and other molecular features as potential predictive biomarkers. Citation Format: Jing Yi Lee, Tun Kiat Ko, Elizabeth Chun Yong Lee, Bavani Kannan, Boon Yee Lim, Zhimei Li, Zexi Guo, Jui Wan Loh, Cedric Chuan-Young Ng, Kelila Xin Ye Chai, Nur Ayuni Binte Muhammad Taib, Kerry Lim, Dachuan Huang, Jing Quan Lim, Masatoshi Hazama, Koji Fukushima, Bin Tean Teh, Soon Thye Lim, Choon Kiat Ong, Jason Yongsheng Chan. Potent anti-proliferative activity of brincidofovir in Diffuse Large B-cell Lymphoma with overexpression of transcriptional repressor TLE1 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7276.

Novel Protac-Based EZH2 Degraders Effectively Target EZH2-Driven Lymphoid Malignancies By Abolishing Both Methylation-Dependent and -Independent Functions

Across various cancers, overexpression or mutation of the epigenetic silencer EZH2 correlates with invasive cancer growth, resistance and poor survival outcomes. While the tumorigenic role of EZH2 is largely attributed to the H3K27me3-mediated repression of tumor suppressor genes, reports have also established a methylation-independent role for EZH2 in the transcriptional activation of oncogenes, particularly in aggressive cancers like Natural Killer T-cell Lymphoma (NKTL). Here, traditional EZH2 inhibitors have been ineffective. We hypothesized that targeted depletion of the EZH2 protein will more effectively disrupt oncogenic signals arising from enzyme-independent activities of EZH2. Thus, we embarked on the development of EZH2 Proteolysis Targeting Chimeras (PROTACs) to trigger targeted ubiquitination and proteasome-mediated degradation of EZH2. No clinical EZH2 PROTAC has been reported yet. Our initial efforts focused on the iterative synthesis of a series of PROTAC candidates considering factors such as permeability, solubility and stable ternary complex formation. We developed a library of 53 compounds with various permutations of EZH2- and E3 ligase-binding ligands as well as linker lengths. Through extensive screening and testing of the EZH2 degradation activity via the Nano-Glo HiBiT lytic detection system and immunoblotting, we identified three lead Protac candidates. Compared to the clinical EZH2 inhibitor Tazemetostat (Taz), EZH2 PROTACs, C2911 and C1311 demonstrated higher cytotoxic activity in diffuse large B-cell lymphoma (DLBCL), a cancer in which Taz was evaluated during clinical trial. Importantly, C2911 and C1311 also successfully triggered EZH2 degradation in a dose-dependent manner thereby qualifying for further evaluation in NKTL. Previous work has highlighted a critical role for JAK3-mediated phosphorylation of EZH2 in promoting NKTL proliferation. Treatment of NKTL with C2911 and C1311 leads to a dose and time-dependent EZH2 degradation, loss of cell viability and increased apoptosis. These effects were absent with Taz and Pomalidomide treatments. The concomitant loss of H3K27me3 levels as well as PRC2 complex subunits, SUZ12 and EED suggest effective degradation of the EZH2 protein. We also observed that induction of NKTL cell death required a longer treatment period as compared to DLBCL. This may be potentially ascribed to the longer half-life of the EZH2 protein in NKTL as determined through cycloheximide treatment. In order to validate the mechanism of action of the EZH2 PROTACs, cells were either pretreated with pomalidomide or siRNA targeting cereblon. Indeed, this mitigated PROTAC-induced degradation of the EZH2 protein and rescued cancer cell death. Similarly, inhibiting the activity of the 26S proteasome through bortezomib also prevented EZH2 degradation. Characterization of EZH2 PROTAC-induced protein expression changes through immunoblotting highlighted that there was specific loss of H3K27me3 and H3K27me2 but not H3K27me1. Of note, we detected a concomitant decrease of Jak3 protein expression and STAT5 phosphorylation levels, more pronounced than PRC2 complex subunits. This suggests that the PROTAC may act by disrupting the non-canonical binding of EZH2 to Jak3 in NKTL. Furthermore, gene expression analyses revealed that EZH2 PROTAC treatment more effectively reactivated canonical EZH2 target genes such as MYT1 and ANPEP as compared to Taz. As the JAK-STAT-MYC axis is dysregulated in NK leukemia, we also evaluated the gene expression of c-Myc and c-Myc target gene, E2F1. EZH2 PROTAC treatment reduces the transcription levels of these oncogenes corroborating with loss of c-Myc protein expression. Studying the pharmacokinetics of the lead PROTACs in a mouse model revealed good plasma stability, half-life (> 4 h), and low clearance. Collectively, our data supports a critical role for EZH2 PROTACs in abolishing both the enzyme-dependent and independent activities of EZH2 through protein degradation, resulting in enhanced anti-cancer activity against DLBCL and NKTL. This may potentially benefit other EZH2-driven cancers. Further evaluation of the EZH2 PROTACs for clinical application is in progress. EZH2 PROTACs will next be tested in vivo. An in-depth investigation of the mechanisms stabilizing EZH2 protein levels and underlying PROTAC induced-cell death will be made to identify potential mechanisms of resistance.

Targeting Aberrantly Activated Glycolysis in Natural Killer T Cell Lymphomas

Background and aims: With advances in the diagnosis and treatment of malignant lymphoma, improvements in long-term survival have been achieved for most common lymphoma types. However, natural killer/T-cell lymphoma (NKTL), which is rare in Europe and North America (0.3%) but relatively common in Asia and Latin America, has been left behind as a subtype of lymphoma with a high relapse rate and a poor prognosis. In particular, the outcome of patients with advanced or recurrent NKTL is dismal, with an overall survival of only a few months. This is mainly attributed to the intrinsic resistance of NKTL cells to anthracycline due to the high expression of P-glycoprotein. Molecular-targeted drugs used for other hematological malignancies, such as anti-CD30 and anti-CD52 monoclonal antibodies, have only limited effects on NKTL, and conversely, these drugs can cause severe immunodeficiency and severe autoimmune diseases, often with a fatal course. The development of NKTL-specific and effective molecular-target therapies is expected to improve the prognosis of NKTL. Methods: We performed a gene expression array targeting genes involved in glucose cell metabolism to compare the gene signatures of NK cell lines (NKL, NK92, YT, and KYHG1) and freshly isolated NK cells from three healthy donors (FNK). Results: The expression of various glucose metabolism genes was higher in NK cell lines than in FNK cells, and in particular, the PKM gene was highly enriched in NK cell lines. The PKM gene encodes the pyruvate kinase muscle isozyme 2 (PKM2), which is responsible for ATP production within the glycolytic sequence and plays an essential role in aerobic glycolysis (the Warburg effect), a dominant metabolic pathway used by cancer cells. Immunohistochemistry studies revealed high PKM2 protein expression in 17 out of 20 tumor tissues derived from patients with extranodal NK/T cell lymphoma. Treatment of NKL, NK92, YT, and KYHG1 cells with Benserazide or Shikonin, two known PKM2 inhibitors, robustly induced cell apoptosis in a time- and dose-dependent manner and inhibited colony formation in in vitro clonogenic assays. Western blotting studies showed a dose-dependent inhibition of STAT1 and STAT3 in NK cell lines exposed to PKM2 inhibitors. A colorimetric assay showed that PKM2 glycolytic activity correlated with the PKM2 gene expression in NK cells, with significantly higher glycolytic activity in malignant NK cell lines than in normal FNK cells. Further mechanistic studies showed that in normal FNK cells, PKM2 is mainly in the tetrameric form, where glucose is converted to pyruvate to generate ATP. In contrast, in malignant NK cell lines, PKM2 is mainly expressed in its dimeric form, with a low affinity for pyruvate and a higher affinity for glycolytic intermediates that promote the synthetic processes and thereby lead to persistent cell proliferation. Conclusions: These results substantiate the importance of aerobic glycolysis in malignat NK cells and indicate that targeting this pathway by blocking PKM2 activity has therapeutic potential for NKTL.

Enhanced efficacy of combined fluzoparib and chidamide targeting in natural killer/T-cell lymphoma.

The treatment of natural killer/T-cell lymphoma (NKTCL) presents an onerous challenge, and a search for new therapeutic targets is urgently needed. Poly ADP-ribose polymerase inhibitors (PARPi) were initially used to treat breast and ovarian cancers with BRCA1/2 mutations. Their excellent antitumor efficacy led to a series of clinical trials conducted in other malignancies. However, the exploration of PARPi and their potential use in combination treatments for NKTCL remains unexplored. We treated NKTCL cell lines with fluzoparib (a novel inhibitor of PARP) and chidamide (a classical inhibitor of HDACs) to explore their cytotoxic effects in vitro. Then, their antitumor efficacy in vivo was confirmed in YT-luciferin xenograft mouse models. Fluzoparib or chidamide alone inhibited NKTCL cell proliferation in a dose-dependent manner. Cotreatment with both drugs synergistically induced excessive accumulation of DNA double-strand breaks and massive apoptotic cell death by inhibiting the DNA damage repair pathway, as shown by the decreased protein levels of p-ATM, p-BRCA1, p-ATR, and Rad51. Moreover, the combination treatment apparently increased the level of intracellular reactive oxygen species (ROS) to enhance apoptosis, and pretreatment with an ROS scavenger reduced the proapoptotic effect by 30-60% in NKTCL cell lines. In vivo, this combined regimen also showed synergistic antitumor effects in xenograft mouse models. The combination of fluzoparib and chidamide showed synergistic effects against NKTCL both in vitro and in vivo and deserves further exploration in clinical trials.

PARP inhibitor exerts an anti-tumor effect via LMO2 and synergizes with cisplatin in natural killer/T cell lymphoma

BackgroundPARP inhibitor (PARPi), as a kind of DNA damage repair inhibitor, has been shown to be effective in various solid tumors and hematologic malignancies. Natural killer/T cell lymphoma (NKTCL) is a highly aggressive malignancy, the treatment of which has long been a major challenge in the clinic. Here, we investigated the efficacy and mechanism of PARPi, and the therapeutic value of PARPi combined with cisplatin in NKTCL.MethodsThe cell proliferation, cell apoptosis, and cell cycle of NKTCL cells were detected respectively by CCK-8 and flow cytometry. The changes of mRNA expression and protein level were measured respectively by mRNA-sequencing, quantitative real-time PCR, western blotting, and immunofluorescence. LMO2 expression was detected by immunohistochemistry and western blotting. Targeted knockdown of LMO2 was conducted by short hairpin RNA. The tumor xenograft models were established to evaluate the efficacy of drugs in vivo.ResultsPARPi inhibited cell proliferation, promoted cell apoptosis, and induced S-phase cell cycle arrest in NKTCL cells. PARPi led to the accumulation of DNA damage by blocking DNA repair and DNA replication. Additionally, LMO2 deficiency reduced the sensitivity of NKTCL cells to PARPi. Finally, the combination of PARPi and cisplatin exhibited significant synergistic effects both in vitro and in vivo.ConclusionsIn summary, we found that PARPi exerted an anti-tumor effect via LMO2 and synergized with cisplatin in NKTCL, which provides the theoretical basis for the clinical application of PARPi.

CAR-T cells targeting CD38 and LMP1 and anti-tumor activity against NK/T cell lymphoma.

e19529 Background: Natural killer/T-cell lymphoma (NKTCL) is an aggressive lymphoma with poor prognosis. In the past decade, chimeric antigen receptor transduced T (CAR-T) cell therapy has been a promising strategy against hematologic malignancies. Researchers have evaluated the efficacy of CAR-T cell targeting CD38 in multiple myeloma and NKTCL. LMP1 may induce a malignant transformation in B cells and epithelial cells, making it a non-negligible molecule in NKTCL. These suggest the potential clinical administration of CD38 and LMP1 targeting therapy. Methods: Four second-generation CAR-T cells including two single-targeted CAR (CD38-CAR and LMP1-CAR) and two tandem CAR (CD38-LMP1 Tan CAR 1 and Tan CAR 2) were constructed. Then the effects of four CAR-T cells on NKTCL cells were evaluated both in vitro and in vivo. Results: Four CAR-T cells could effectively eliminate malignant target-positive NKTCL cells in vitro. They could be activated and produce inflammatory cytokines in a target-dependent manner. Stimulated by CD38+LMP1+ NKTCL cells, two Tan CAR-T cells produced more IL-13, Granzyme B, IFN-γ and TNF-α than LMP1-CAR-T cells. In vivo test showed that CAR-T cells also exhibit significant anti-tumor effects in a xenotransplant NKTCL mice models. Two Tan CAR-T cells showed higher cytolytic activity against CD38+LMP1+ NKTCL cells than single-targeted CAR-T cells both in vitro and in vivo. Conclusions: We explored the feasibility of CAR-T cell therapy targeting both CD38 and LMP1 molecule. Our results indicated a promising effective therapeutic strategy for NKTCL.

T-cell dysfunction in natural killer/T-cell lymphoma

ABSTRACT Natural killer/T-cell lymphoma (NKTCL) is an incurable aggressive T-cell lymphoma closely correlated with Epstein‒Barr virus (EBV) infection. Chronic and consistent viral infection induces T-cell exhaustion. Herein, we describe T-cell dysfunction in NKTCL patients for the first time. Peripheral blood mononuclear cells (PBMCs) from age-matched healthy donors (HDs) and NKTCL patients were collected, and lymphocyte distributions, multiple surface inhibitory receptors (IRs), effector cytokine production and cell proliferation were determined by flow cytometry. PBMCs from HDs were cocultured with NKTCL cell lines to verify the clinical findings. IR expression was further assessed in NKTCL tumor biopsies using multiplex immunohistochemistry (mIHC). NKTCL patients have higher frequencies than HDs of inhibitory T regulatory cells (Tregs) and myeloid-derived suppressor cells (MDSCs). T-cell distribution also varies between NKTCL patients and HDs. T cells from NKTCL patients demonstrated higher expression levels of multiple IRs than HDs. Meanwhile, T-cell proliferation and interferon-γ production was significantly reduced in NKTCL patients. More importantly, the number of EBV-specific cytotoxic cells was lower in NTKCL patients, and these cells demonstrated upregulation of multiple IRs and secreted fewer effector cytokines. Interestingly, NKTCL cells caused normal PBMCs to acquire T-cell exhaustion phenotypes and induced generation of Tregs and MDSCs. In line with ex vivo finding, mIHC results showed that CD8+ T cells from NKTCL tumor biopsies expressed much higher level of IRs compared with reactive lymphoid hyperplasia individuals. The immune microenvironment of NKTCL patients exhibited T-cell dysfunction and accumulation of inhibitory cell components, which may contribute to impaired antitumor immunity.

Inhibition of extranodal NK/T-cell lymphoma by Chiauranib through an AIF-dependent pathway and its synergy with L-asparaginase

Extranodal NK/T-cell lymphoma (NKTL) is a rare and aggressive form of extranodal lymphoma with a poor prognosis. Currently, there are very limited treatment options for patients with advanced-stage disease or those with relapsed/recurrent disease. Here we show that Chiauranib, an orally small molecule inhibitor of select serine-threonine kinases (aurora B, VEGFRs, PDGFR, CSF1R, c-Kit), inhibited NKTL cell proliferation, induced cell cycle arrest, as well as suppressed the microvessel density in vitro and in vivo similar as in other types of cancer cells. Surprisingly, Chiauranib unfolded a new effect to induce apoptosis of NKTL cells by triggering AIF-dependent apoptosis other than the traditional cyt-c/caspase mitochondrial apoptosis pathway. The knockdown of AIF in vitro and in vivo dramatically blocked the efficacy of Chiauranib on NKTL. Mechanistically, the release of AIF from mitochondria is due to the upregulation of VDAC1 by the AKT-GSK3β pathway and activation of calcium-dependent m-calpain, which promotes the cleavage of VDAC1 and therefore permits the release of AIF. Notably, the low expression of Bax in both NKTL cells and patient tissues restrained the cyt-c release. It resulted in the inhibition of cyt-c/caspase mitochondrial pathway, suggesting that drugs targeting this traditional pathway may not be effective in NKTL. Furthermore, we found that L-asparaginase triggered CD95 (Fas/Apo-1)-caspase 8-caspase 3 apoptotic pathway in NKTL cells, and combination of Chiauranib and L-asparaginase exhibited a synergistic effect, suggesting a feasibility to combine these two drugs for effective treatment of NKTL. This study demonstrates Chiauranib’s positive efficacy toward NKTL through the activation of the AIF-dependent apoptosis pathway for the first time. The novel and multi-targets of Chiauranib and the synergistic effect with L-asparaginase may provide a promising therapy for NKTL patients.

Super-enhancer-driven TOX2 mediates oncogenesis in Natural Killer/T Cell Lymphoma

BackgroundExtranodal natural killer/T-cell lymphoma (NKTL) is an aggressive type of non-Hodgkin lymphoma with dismal outcome. A better understanding of disease biology and key oncogenic process is necessary for the development of targeted therapy. Super-enhancers (SEs) have been shown to drive pivotal oncogenes in various malignancies. However, the landscape of SEs and SE-associated oncogenes remain elusive in NKTL.MethodsWe used Nano-ChIP-seq of the active enhancer marker histone H3 lysine 27 acetylation (H3K27ac) to profile unique SEs NKTL primary tumor samples. Integrative analysis of RNA-seq and survival data further pinned down high value, novel SE oncogenes. We utilized shRNA knockdown, CRISPR-dCas9, luciferase reporter assay, ChIP-PCR to investigate the regulation of transcription factor (TF) on SE oncogenes. Multi-color immunofluorescence (mIF) staining was performed on an independent cohort of clinical samples. Various function experiments were performed to evaluate the effects of TOX2 on the malignancy of NKTL in vitro and in vivo.ResultsSE landscape was substantially different in NKTL samples in comparison with normal tonsils. Several SEs at key transcriptional factor (TF) genes, including TOX2, TBX21(T-bet), EOMES, RUNX2, and ID2, were identified. We confirmed that TOX2 was aberrantly overexpressed in NKTL relative to normal NK cells and high expression of TOX2 was associated with worse survival. Modulation of TOX2 expression by shRNA, CRISPR-dCas9 interference of SE function impacted on cell proliferation, survival and colony formation ability of NKTL cells. Mechanistically, we found that RUNX3 regulates TOX2 transcription by binding to the active elements of its SE. Silencing TOX2 also impaired tumor formation of NKTL cells in vivo. Metastasis-associated phosphatase PRL-3 has been identified and validated as a key downstream effector of TOX2-mediated oncogenesis.ConclusionsOur integrative SE profiling strategy revealed the landscape of SEs, novel targets and insights into molecular pathogenesis of NKTL. The RUNX3-TOX2-SE-TOX2-PRL-3 regulatory pathway may represent a hallmark of NKTL biology. Targeting TOX2 could be a valuable therapeutic intervene for NKTL patients and warrants further study in clinic.

Histone deacetylases inhibitor chidamide synergizes with humanized PD1 antibody to enhance T-cell chemokine expression and augment Ifn-γ response in NK-T cell lymphoma.

Whether immunotherapy combined with different histone deacetylases (HDAC) inhibitors in refractory or relapsed natural killer/T-cell lymphoma (NKTCL) is superior to each agent is still lacking in head-to-head clinical trials or preclinical evidence. NKTCL cell line xenograft models (CDX) in immunocompetent, human programmed cell death protein 1(PD1) knock-in genetically engineered mice were used to investigate the combination effects. Different types and dosages of HDAC inhibitors were investigated. We explored the underlying mechanisms by RNA-sequencing and ChIP-sequencing. Two clinical cases treated with anti-PD1/chidamide were presented. Anti-PD1/chidamide shows significant tumour rejection in two CDX models. RNA-seq and CHIP-seq revealed that chidamide is synergistic to enhance T-cell chemokine expression, augment the Ifn-γ response, and increase CD8 T-cell infiltration via histone modification. Ifn-γ neutralizing antibody can attenuate the efficacy of combination drugs. However, the anti-PD1/romidepsin failed to augment the Ifn-γ response. The expressions of Ifn-γ related gene set signatures are significantly correlated with tumour rejection in anti-PD1/chidamide. In the clinic, two NKTCL patients treated with the PD1/chidamide show promising efficacy and limited toxicity. Anti-PD1/chidamide enhances T-cell chemokine expression and augments the IFN-γ response in preclinical NKTCL immunocompetent models. IFN-γ signatures may be good response biomarkers for the selection of potentially benefit patients. This study was supported by the Chinese National Major Project for New Drug Innovation (2017ZX09304015) and the Chinese Society of Clinical Oncology Research Fund (Y-BMS2019-026).

MiR-363 suppresses the tumor growth of natural killer/T-cell lymphoma via the SIRT6/PI3K/AKT axis

Natural killer/T cell lymphoma (NKTCL) is a rare and aggressive tumor of non-Hodgkin's lymphoma. The role of micro ribonucleic acid (RNA) (miR)-363 in NKTCL has not yet been elucidated. The present study aimed to investigate the potential role of miR-363 in NKTCL. The expression of the top five differentially expressed microRNAs (miRNAs) as well as sirtuin 6 (SIRT6) in NK normal cells and its tumor cell lines were explored. The clinical tissues of NKTCL patients were collected and analyzed for expression of miR-363 and SIRT6. In addition, human NK/T-cell lymphoma cells (SNK-6) were transfected into different groups to detect cell proliferation and apoptosis abilities through cell counting kit 8 (CCK-8) experiment and flow cytometry analysis. Western blot assay was employed to examine protein expression. NKTCL nude mice models were constructed by subcutaneous injection of stably transfected SNK-6 cells to validate the mechanism of miR-363 in NKTCL via SIRT6 in vivo. MiR-363 was down-regulated in NKTCL tissues and cell lines. Overexpression of miR-363 inhibited cell proliferation and promoted cell apoptosis. In contrast, SIRT6 was up-regulated in NKTCL and proved to be a downstream target of miR-363. SIRT6 could activate the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT) signaling pathway. Also, miR-363 mimic could suppress the proliferation and induce the apoptosis of NKTCL via the SIRT6/PI3K/AKT axis both in vitro and in vivo. MiR-363 suppresses the SIRT6/PI3K/AKT pathway to restrain cell proliferation and accelerate cell apoptosis during NKTCL progression.

Methyltransferase-like 3 enhances cell proliferation and cisplatin resistance in natural killer/T-cell lymphoma through promoting N6-methyladenosine modification and the stability of staphylococcal nuclease and Tudor domain-containing protein 1 mRNA.

Nasal-type natural killer/T-cell lymphoma (NKTCL) is a typical class of non-Hodgkin's lymphoma, which is quite malignant because of its high resistance to chemotherapy. N6-methyladenosine (m6A) modification, a prevalent modification of eukaryotic RNA, was emerging as an important regulatory mechanism in progression of various tumors. Here, we demonstrated that methyltransferase-like 3 (METTL3), an RNA methyltransferase, was obviously upregulated in human NKTCL cell lines (NK-92, YTS, SNT-8, and SNK-6) compared with normal NK cells. Knockdown of METTL3 noticeably repressed proliferation and facilitated apoptosis in SNT-8 cells, whereas overexpression of METTL3 showed opposite results in SNK-6 cells. In the mechanism exploration, we found that METTL3 stimulated the m6A modification of staphylococcal nuclease and Tudor domain-containing protein 1 (SND1) mRNA, recruited YTH m6A RNA binding protein 1 to recognize the m6A site, thereby enhancing its mRNA stability. Rescue experiments demonstrated that METTL3 significantly prohibited NKTCL cell chemotherapy sensitivity to cisplatin (DDP) through regulating SND1 expression. Furthermore, knockdown of SND1 suppressed tumor growth and reduced DDP resistance in vivo . Taken together, our findings uncovered the role of METTL3 in the regulation of chemotherapy resistance in NKTCL oncogenesis.

A Comprehensive, Multiomics Analysis of Natural Killer-Cell Malignancies

Natural killer/T cell lymphoma (NKTCL) and aggressive NK cell leukemia (ANKL) are rare mature NK cell malignancies which show a geographic predilection for Asia and Central/South America and are strongly associated with EBV infection. Despite recent advances in chemotherapeutical agents, the prognosis (especially for ANKL) remain poor. On the contrary, NK cell proliferations of a more indolent nature also exist. NK-large granular lymphocytic leukemia (NK-LGLL) is a disorder of NK cells with indolent clinical manifestation. Additionally, chronic active Epstein-Barr virus infection (CAEBV) affecting NK cells can have variable presentation, between indolent and aggressive. Due to their rarity, a comprehensive understanding of the events differentiating the wide spectrum of NK malignancies remains elusive. Here, we use a multi-omics approach to investigate the genetic differences underlying the different clinical manifestations of NK malignancies. To discover the pathogenesis behind indolent and aggressive NK malignancies, we studied whole-genome/exome sequencing and whole transcriptome sequencing (RNA-seq) data from over 200 NK-cases collected from 11 previous publications. We investigated driver genes from 145 WES and WGS samples, and transcriptomes from 91 samples. Single-cell RNA-seq analysis was performed to identify and characterize distinct NK-cell subsets. We used pooled CRISPR screens with a single-cell RNA sequencing readout (CROP-seq) to investigate the effect of knocking out the most frequently mutated genes on the transcriptome of NKTCL cells under the effect of commonly used chemotherapeutic agents. We also aim to construct a comprehensive host-EBV interaction map to elucidate the role of EBV in the pathogenesis of NK malignancies We validated previously found driver genes STAT3 and DDX3X as the most frequently mutated genes in NK malignancies, being mutated in 15% and 14% of samples, respectively. STAT3 mutations were found only in NKTCL and ANKL samples. Additionally, our combinatorial analysis allowed for identification of previously unappreciated putative driver genes, MSN and HLA-A, which were mutated in 8% and 4% of samples, respectively. We also discovered associations between important genes, such as significant co-occurrence of mutations in STAT3 and novel driver gene MSN (p <0.05). Samples originating from different diseases were intermingled in non-negative matrix factorization (NMF) analyses, highlighting the effect of mutational profile, rather than disease type, on sample clustering. Using RNA-seq, differentially expressed genes (Q-value < 0.01) were identified between ANKL, NKTCL and healthy samples. Gene set enrichment analysis revealed differential enrichment and depletion of biological processes in ANKL and NKTCL. Upregulation of chemokine signalling and macrophage-associated processes in NKTCL reflected the inflammatory microenvironment of the disease. Of 17 putative driver genes, CRISPR knockout of STAT3 and TP53 led to most transcriptional changes. Knockout of STAT3 caused upregulation of HLA I and II molecules and downregulation of IL10 signaling, thus promoting tumor cell immune evasion. Our preliminary results indicate that NK malignancies are, contrary to previous knowledge, a spectrum of manifestations rather than distinct diseases. Our results concerning the heterogeneous genetic landscape of NK malignancies can lead to better and faster diagnosis as well as improved treatment stratification in the future. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Therapeutic Repurposing of Brincidofovir in Natural Killer/T-Cell Lymphoma Reveals Potent Induction of Replication Stress, Sting Pathway Activation and Immunogenic Cell Death

Introduction Natural killer/T-cell lymphoma (NKTCL) is an aggressive subtype of non-Hodgkin lymphoma associated with Epstein-Barr virus (EBV) infection. Brincidofovir (BCV), a lipid conjugated form of cidofovir, is a biologically active acyclic nucleoside phosphonate known for both antiviral and antiproliferative properties. Methods We investigated BCV in a panel of NKTCL cell lines (n=11) and mouse xenograft models. The mechanism of action was examined using bulk and single cell RNA sequencing (10X Chromium 3' Gene Expression Profiling), and validated in orthogonal assays. Results BCV evoked a dose- and time-dependent inhibition of cell viability in all NKTCL cell lines, independent of EBV presence. Exquisite sensitivity was observed in 4 cell lines KAI-3, NK-S1, NK-92 and KHYG-1 (IC50 range, 36.0 to 303.6 ng/ml), accompanied by increase in sub-G1 fraction and S-phase arrest on cell cycle analyses. Bulk RNA sequencing of BCV-treated cell lines (KAI-3 and NK-S1) revealed pervasive downregulation of MYC target pathways, along with upregulation of immune-related and DNA repair pathways. Single cell RNA sequencing revealed distinct temporal cell states evoked by BCV. In KAI-3 cells, a significant shift in transcriptomic cell states occurred upon BCV treatment for 48h, with appearance of cell clusters enriched for type I interferon and cytokine signaling pathways, as well as activation of p53 and apoptosis pathways. Cell cycle and DNA repair pathways were also evident. At 72h post-BCV treatment, type II interferon signaling and endoplasmic reticulum stress response pathways were prominent. Similarly in NK-S1 cells, cell clusters enriched for immune signals, including interleukin-18 and cytokine pathways emerged, as did cell cycle, DNA repair, and apoptosis pathways. Western blot demonstrated increase in replication stress markers (p-CHK1 S317 and S345, RRM2, p-RPA2 S33), p-H2AX (DNA double strand break) and p-TBK1 (STING pathway activation). In keeping with this result, BCV triggered micronuclei formation, DNA fragmentation, and cytoplasmic DNA release. Gene expression levels of type I (IFNA, IFNB1) and II (IFNY) interferons and cytokines (CCL5, CXCL10) were upregulated following BCV treatment, as did the proportion of calreticulin-expressing cells and amount of extracellular HMGB1 released, indicative of immunogenic cell death. Notably, nuclear and membranous protein expression of the immune checkpoint protein PD-L1 also markedly increased. Intraperitoneal administration of BCV (40 mg/kg, twice per week) inhibited tumor volume in NOD/SCID mouse xenografts of NKTCL, compared with vehicle alone (p=0.0005, two-tailed t-test). On immunohistochemistry, PD-L1 was significantly overexpressed in BCV-treated tumor xenografts compared with control, with a 1.9-fold higher median H-score (p=0.0007, Mann-Whitney test). Conclusions Taken together, these results demonstrate a novel repurposed role of BCV in the treatment of NKTCL. The activation of DNA damage-induced STING pathway and immune-related signals suggests a further potential for combination with checkpoint immunotherapy.

CircKIF4A Is a Prognostic Factor and Modulator of Natural Killer/T-Cell Lymphoma Progression.

Simple SummaryCircKIF4A is significantly upregulated in NKTL cell lines and its upregulation correlates with the poor prognosis of NKTL. CircKIF4A regulates PDK1 and BCL11A expressions by sponging miR-1231. Our data indicated that circKIF4A is oncogenic in NKTL and that it is a predictor of poor prognosis of NKTL. Background: Natural killer/T-cell lymphoma (NKTL) is difficult to treat. Circular RNAs (circ RNAs) have been implicated in tumorigenesis. However, the function of circKIF4A in NKTL has not been investigated. Methods: QPCR analysis was used to compare circKIF4A levels in NKTL cell lines versus normal cell lines. Kaplan–Meier survival analysis was used to assess the effect of circKIF4A on the prognosis of NKTL. The correlation between clinicopathological features and circKIF4A expression was examined using cox regression analysis. Luciferase reporter, RNA immunoprecipitation and immunohistochemistry assays were also used to investigate the mechanisms of circKIF4A in NKTL. Results: Our analyses revealed that circKIF4A is significantly upregulated in NKTL cell lines and that its upregulation correlates with the poor prognosis of NKTL. The silencing of circKIF4A significantly suppressed glucose uptake and lactate production in NKTL cells. Moreover, we showed that circKIF4A, PDK1, and BCL11A bind miR-1231 and that circKIF4A regulates PDK1 and BCL11A expressions by sponging miR-1231. Conclusions: During NKTL progression, circKIF4A regulated PDK1 and BCL11A levels by sponging miR-1231. Our data indicated that circKIF4A is oncogenic in NKTL and that it is a predictor of poor prognosis of NKTL.

Brentuxinmab vedotin, alone or combine with bendamustine in the treatment of natural killer T cell lymphoma.

Natural killer (NK)/T cell lymphoma is a highly aggressive subtype of non-Hodgkin lymphoma. The prognosis of patients with natural killer T cell lymphoma (NKTCL) remains poor. More potent treatment strategies are urgently needed to improve the survival of these patients with R/R NKTCL. CD30 expression has been reported to occur in about 40% of NK/T cell lymphoma. Brentuximab vedotin (BV), a monomethyl auristatin E conjugated CD30 antibody, targets CD30 to kill cancer cells. Therapeutic combination of BV and bendamustine has been shown to be highly effective in Hodgkin lymphoma. We investigated efficacy of BV in treating NKTCL as a single therapy, and in combination with bendamustine in vitro and in vivo. We determined CD30 expression levels in 6 NKTCL cell lines. The efficiency of lymphoma cell inhibition by BV correlates with CD30 expression. We also determined the efficacy of BV in combination with bendamustine and found synergistic effects with bendamustine in NKTCL. Combined BV and bendamustine treatment exerted synergistic antiproliferation effect and enhanced cell apoptotic in vitro and in vivo. Brentuximab vedotin and bendamustine synergistically arrested cell cycle at the G2/M phase in NKTCL cell lines. The combination of BV and bendamustine was demonstrated to synergistically damage DNA in NKTCL. This study provides a reference for possible application on using BV for the treatment of NKTCL, either as a single agent or in combination with bendamustine.

Kayadiol exerted anticancer effects through p53-mediated ferroptosis in NKTCL cells

BackgroundExtranodal natural killer/T cell lymphoma (NKTCL) is a highly aggressive type of non-Hodgkin lymphoma that facing the treatment challenges. Natural compounds are important sources for drug development because of their diverse biological and chemical properties, among which terpenoids have strong anticancer activities.MethodsThe human NK/T cell lymphoma cell line YT and peripheral blood lymphocytes isolated from NKTCL patients were treated with different concentrations of kayadiol. Then, the following experiments were performed: CCK-8 assay for cell viability, reactive oxygen species (ROS) and glutathione (GSH) assay and co-treatment with NAC, reduced GSH, or ferrostatin-1 for ferroptosis, the proteome profiling for elucidating signaling pathways, and western blot for the expression of p53, SCL7A11, and GPX4. siRNA and CRISPR/Cas9 plasmid for p53 knockout was designed and transfected into YT cells to evaluate the causal role of p53 in kayadiol-induced ferroptosis. The synergistic effect was evaluated by CCK8 assay after co-treatment of kayadiol with L-asparaginase or cisplatin.ResultsIn this study, we found that kayadiol, a diterpenoid extracted from Torreya nucifera, exerted significant killing effect on NKTCL cells without killing the healthy lymphocytes. Subsequently, we observed that kayadiol treatment triggered significant ferroptosis events, including ROS accumulation and GSH depletion. ROS scavenger NAC, GSH, and ferroptosis inhibitor ferrostatin-1 (Fer-1) reversed kayadiol-induced cell death in NKTCL cells. Furthermore, kayadiol decreased the expression of SLC7A11 and GPX4, the negative regulatory proteins for ferroptosis. We then demonstrated that p53 was the key mediator of kayadiol-induced ferroptosis by SLC7A11/GPX4 axis through p53 knockout experiments. In addition, kayadiol exerted a synergistic effect with L-asparaginase and cisplatin in NKTCL cells.ConclusionTaken together, our results suggested that the natural product kayadiol exerted anticancer effects through p53-mediated ferroptosis in NK/T cell lymphoma cells. Hence, it can serve as an effective alternative in the treatment of NK/T cell lymphoma, especially for patients exhibiting chemoresistance.

HDAC inhibitor Chidamide, but not romidepsin, synergizes with humanized PD1 antibody to enhance T-cell chemokine expression and augment IFN-gamma response in NK-T-cell related lymphoma: A preclinical study.

e14568 Background: The incidence of NK-T cell lymphoma (NKTL) in Asia is significantly higher than that in European and American countries. The median survival time of EKTL is only 8-12 months, and the 5-year overall survival rate is still less than 30%. New therapies or combinations are warranted. Methods: The murine NKTL cell line EL4 and RMA were used to establish cell line xenograft models in transgenic humanized PD1 mice. Different dosages or sequential HDAC inhibitors were combined with humanized PD1 antibody in vivo to test whether the synergistic effect is existing. RNA-seq, qPCR, and IHC were performed to illustrate the potential mechanisms. Three NTKL patients who were treated with hPD1 and Chidamide in clinical were recorded in this study. Results: Romidepsin combined with hPD1 antibody is superior to hPD1 antibody alone in the treatment of two NKTL CDX models (EL4 and RMA), but it is similar with romidepsin single agent, either in different dosages or sequence. However, Chidamide combined with hPD1 antibody significantly inhibits the tumor growth compared to single agents in these two pre-clinical models. RNA-seq reveals Chidamide synergizes with humanized PD1 antibody to enhance T-cell chemokine expression, augment IFN-gamma response and increase CD8 T cell infiltration. String PPI analysis and ingenuity pathway analysis suggest IFN-gamma is the hub upstream regulator in the combination. On the contrary, the romidepsin combinations decrease the activity of T cell immune responses and the function of immune cell migration. The expression of IFN-gamma gene set signatures is decreased in the romidepsin combination. Three NKTL patients who received PD1 antibody and Chidamide are showed promising efficacy, and the progression-free survival is 26+ months, 8 months, and 9+ months respectively. Conclusions: Different HDAC inhibitor shows different combination effects with immunotherapy. Chidamide combination shows a synergistic effect with immunotherapy by enhancing INF-gamma response, but romidepsin combination antagonizes this effect significantly.

GNAQ T96S mutation abrogates the ability of wild-type GNAQ to induce apoptosis by phosphorylating annexin A2 in natural killer/T cell lymphoma.

Our previous study identified annexin A2 (ANXA2) as a Gaq‐interacting partner in natural killer/T cell lymphoma (NKTCL) cells transfected with the GNAQ T96S mutation vector by immunoprecipitation and mass spectrometry; however, the detailed molecular mechanisms by which GNAQ T96S might regulate ANXA2 remain to be defined in NKTCL. Herein, we found that the GNAQ T96S mutation significantly promotes the phosphorylation of ANXA2 at the Y24 site, whereas phosphorylation of ANXA2 abolishes the ability of WT GNAQ to trigger cell apoptosis. Further investigation revealed that a GNAQ T96S peptide inhibitor induced apoptosis by competing with ANXA2 binding to GNAQ T96S in NKTCL cells. In vivo animal experiments showed that a GNAQ T96S peptide inhibitor suppresses the growth of NKTCL cells carrying the GNAQ T96S mutation. Our current data suggest a role for GNAQ T96S/Src/ANXA2 in mediating the apoptosis of NKTCL cells, and the GNAQ T96S peptide could be a promising agent for therapy in NKTCL patients.

The potential efficacy and mechanism of bendamustine in entra-nodal NK/T cell lymphoma.

Bendamustine has been shown to have anti-tumor activities in hematological malignancies, but the role of bendamustine in natural killer (NK)/T cell lymphoma (NKTCL) treatment is unclear. Our study has shown that bendamustine had potent growth-inhibitory and apoptosis-inducing effects on NKTCL cells. Interestingly, we noticed that the combination of either gemcitabine or etoposide results in additive or synergistic cytotoxicity. Bendamustine induced mitochondria-mediated apoptosis in concentration- and time-dependent manners in NKTCL cells, shown as down-regulation of Bcl-2 and activation of cleavage of caspases 3, 7, 9 and poly adenosinediphosphate-ribose polymerase (PARP). Bendamustine arrested NKTCL cells in G2/M phase, with downregulation of expression of cyclin B1 and upregulation of expression of p-cdc2, p-cdc25c and p-P53. Furthermore, we confirmed that bendamustine activated DNA damage response (DDR) directly or through Ataxia Telangiectasia Mutated Protein (ATM)/Chk2 and ATR/Chk1 pathway and increased the intracellular reactive oxygen species (ROS) level in NKTCL cells, which caused G2/M phase arrest and apoptosis. Bendamustine also inhibited phosphorylation of transcriptional factor STAT3, contributing to cell apoptosis and proliferation inhibition. Finally, we verified the effect of bendamustine on NKTCL cells in vivo. It showed that bendamustine dramatically inhibited the growth of the subcutaneous tumor, with no obvious impact on mice weight. These findings demonstrate that bendamustine activates DDR pathway, induces the accumulation of intracellularROS level as well as inhibition of STAT3, leading to cell apoptosis and G2/M cell cycle arrest in NKTCL cells, which indicates that bendamustine dramatically suppressed NKTCL both in vitro and in vivo and provides a potential therapeutic strategy in the treatment of NK/T lymphoma.