p53-related protein kinase confers poor prognosis and represents a novel therapeutic target in multiple myeloma

Progression of monoclonal gammopathy of undetermined significance to multiple myeloma is associated with enhanced translational quality control and overall loss of surface antigens

BACKGROUND

Despite significant advancements in treatment strategies, multiple myeloma remains incurable. Additionally, there is a distinct lack of reliable biomarkers that can guide initial treatment decisions and help determine suitable replacement or adjuvant therapies when relapse ensues due to acquired drug resistance.

METHODS

To define specific proteins and pathways involved in the progression of monoclonal gammopathy of undetermined significance (MGUS) to multiple myeloma (MM), we have applied super-SILAC quantitative proteomic analysis to CD138 + plasma cells from 9 individuals with MGUS and 37 with MM.

RESULTS

Unsupervised hierarchical clustering defined three groups: MGUS, MM, and MM with an MGUS-like proteome profile (ML) that may represent a group that has recently transformed to MM. Statistical analysis identified 866 differentially expressed proteins between MM and MGUS, and 189 between MM and ML, 177 of which were common between MGUS and ML. Progression from MGUS to MM is accompanied by upregulated EIF2 signaling, DNA repair, and proteins involved in translational quality control, whereas integrin- and actin cytoskeletal signaling and cell surface markers are downregulated.

CONCLUSION

Compared to the premalignant plasma cells in MGUS, malignant MM cells apparently have mobilized several pathways that collectively contribute to ensure translational fidelity and to avoid proteotoxic stress, especially in the ER. The overall reduced expression of immunoglobulins and surface antigens contribute to this and may additionally mediate evasion from recognition by the immune apparatus. Our analyses identified a range of novel biomarkers with potential prognostic and therapeutic value, which will undergo further evaluation to determine their clinical significance.

Discovery of Highly Potent and Efficient CBP/p300 Degraders with Strong In Vivo Antitumor Activity

The transcriptional coactivator cAMP response element binding protein (CREB)-binding protein (CBP) and its homologue p300 have emerged as attractive therapeutic targets for human cancers such as acute myeloid leukemia (AML). Herein, we report the design, synthesis, and biological evaluation of a series of cereblon (CRBN)-recruiting CBP/p300 proteolysis targeting chimeras (PROTACs) based on the inhibitor CCS1477. The representative compounds 14g (XYD190) and 14h (XYD198) potently inhibited the growth of AML cells with low nanomolar IC50 values and effectively degraded CBP and p300 proteins in a concentration- and time-dependent manner. Mechanistic studies confirmed that 14g and 14h can selectively bind to CBP/p300 bromodomains and induce CBP and p300 degradation in bromodomain family proteins in a CRBN- and proteasome-dependent manner. 14g and 14h displayed remarkable antitumor efficacy in the MV4;11 xenograft model (TGI = 88% and 93%, respectively). Our findings demonstrated that 14g and 14h are useful lead compounds and deserve further optimization and activity evaluation for the treatment of human cancers.

The genetic architecture of complete blood counts in lactating Holstein dairy cows

Complete blood counts (CBCs) measure the abundance of individual immune cells, red blood cells, and related measures such as platelets in circulating blood. These measures can indicate the health status of an animal; thus, baseline circulating levels in a healthy animal may be related to the productive life, resilience, and production efficiency of cattle. The objective of this study is to determine the heritability of CBC traits and identify genomic regions that are associated with CBC measurements in lactating Holstein dairy cattle. The heritability of CBCs was estimated using a Bayes C0 model. The study population consisted of 388 cows with genotypes at roughly 75,000 markers and 16 different CBC phenotypes taken at one to three time points (n = 33, 131, and 224 for 1, 2, and 3 time points, respectively). Heritabilities ranged from 0.00 ± 0.00 (red cell distribution width) to 0.68 ± 0.06 (lymphocytes). A total of 96 different 1-Mb windows were identified that explained more than 1% of the genetic variance for at least one CBC trait, with 10 windows explaining more than 1% of the genetic variance for two or more traits. Multiple genes in the identified regions have functions related to immune response, cell differentiation, anemia, and disease. Positional candidate genes include RAD52 motif-containing protein 1 (RDM1), which is correlated with the degree of immune infiltration of immune cells, and C-X-C motif chemokine ligand 12 (CXCL12), which is critically involved in neutrophil bone marrow storage and release regulation and enhances neutrophil migration. Since animal health directly impacts feed intake, understanding the genetics of CBCs may be useful in identifying more disease-resilient and feed-efficient dairy cattle. Identification of genes responsible for variation in CBCs will also help identify the variability in how dairy cattle defend against illness and injury.

Evaluation of next-generation sequencing versus next-generation flow cytometry for minimal-residual-disease detection in Chinese patients with multiple myeloma

PURPOSE

To evaluate the efficacy of next-generation sequencing (NGS) in minimal-residual-disease (MRD) monitoring in Chinese patients with multiple myeloma (MM).

METHODS

This study analyzed 60 Chinese MM patients. During MRD monitoring in these patients' post-therapy, clonal immunoglobulin heavy chain (IGH) rearrangements were detected via NGS using LymphoTrack assays. MRD monitoring was performed using NGS or next-generation flow cytometry (NGF), and the results were compared. Additionally, the sensitivity and reproducibility of the NGS method were assessed.

RESULTS

The MRD detection range of the NGS method was 10-6-10-1, which suggested good linearity, with a Pearson correlation coefficient of 0.985 and a limit of detection of 10-6. Intra- and inter-assay reproducibility analyses showed that NGS exhibited 100% reproducibility with low variability in clonal cells. At diagnosis, unique clones were found in 42 patients (70.0%) with clonal IGH rearrangements, which were used as clonality markers for MRD monitoring post-therapy. Comparison of NGS and NGF for MRD monitoring showed 79.1% concordance. No samples that tested MRD-positive via NGF were found negative via NGS, indicating the higher sensitivity of NGS. MRD could be detected using NGS in 6 of 7 samples before autologous hematopoietic stem-cell transplantation, and 5 of them tested negative post-transplantation. In contrast, the NGF method could detect MRD in only 1 sample pre-transplantation.

CONCLUSION

Compared with NGF, NGS exhibits higher sensitivity and reproducibility in MRD detection and can be an effective strategy for MRD monitoring in Chinese MM patients.

IMiD-Free Interval and IMiDs Sequence: Which Strategy Is Better Suited for Lenalidomide-Refractory Myeloma?

This review discusses immunomodulatory drug (IMiDs) sequencing and IMiD-free interval strategies for lenalidomide-refractory myeloma. IMiDs and proteasome inhibitors (PIs) improve clinical outcomes in patients with myeloma; however, refractoriness to lenalidomide, a category of IMiD, predicts poor outcomes. Next-generation IMiDs, such as pomalidomide, are effective even for lenalidomide-refractory myeloma. Therefore, an IMiD-sequencing strategy from lenalidomide to pomalidomide would be desirable. PIs are an antimyeloma therapeutic agent with another mode of action that might restore cereblon, a target of IMiDs; therefore, an IMiD-free interval via class switching from lenalidomide to PIs may be a promising alternative for lenalidomide-refractory myeloma. Additionally, the anti-CD38 monoclonal antibody is a key drug for salvage therapy in anti-CD38 monoclonal antibody-naïve patients. In clinical practice, safety profiles and social convenience can play important roles in the choice of combination therapy. In the future, the selection of optimal treatments should be based on the status of the immunological environment and genetic alterations. This review aims to discuss IMiDs sequencing and IMiD-free interval strategies for lenalidomide- refractory myeloma.

Enitociclib, a Selective CDK9 Inhibitor, Induces Complete Regression of MYC+ Lymphoma by Downregulation of RNA Polymerase II Mediated Transcription

Double-hit diffuse large B-cell lymphoma (DH-DLBCL) is an aggressive, and often refractory, type of B-cell non-Hodgkin lymphoma (NHL) characterized by rearrangements in MYC and BCL2. Cyclin-dependent kinase 9 (CDK9) regulates transcriptional elongation and activation of transcription factors, including MYC, making it a potential targeted approach for the treatment of MYC+ lymphomas. Enitociclib is a well-tolerated and clinically active CDK9 inhibitor leading to complete metabolic remissions in 2 of 7 patients with DH-DLBCL treated with once weekly 30 mg intravenous administration. Herein, we investigate the pharmacodynamic effect of CDK9 inhibition in preclinical models and in blood samples from patients [DH-DLBCL (n = 10) and MYC+ NHL (n = 5)] treated with 30 mg i.v. once weekly enitociclib. Enitociclib shows significant regulation of RNA polymerase II Ser2 phosphorylation in a MYC-amplified SU-DHL-4 cell line and depletion of MYC and antiapoptosis protein MCL1 in SU-DHL-4 and MYC-overexpressing SU-DHL-10 cell lines in vitro. Tumor growth inhibition reaching 0.5% of control treated SU-DHL-10 xenografts is achieved in vivo and MYC and MCL1 depletion as well as evidence of apoptosis activation after enitociclib treatment is demonstrated. An unbiased analysis of the genes affected by CDK9 inhibition in both cell lines demonstrates that RNA polymerase II and transcription pathways are primarily affected and novel enitociclib targets such as PHF23 and TP53RK are discovered. These findings are recapitulated in blood samples from enitociclib-treated patients; while MYC downregulation is most robust with enitociclib treatment, other CDK9-regulated targets may be MYC independent delivering a transcriptional downregulation via RNA polymerase II.

SIGNIFICANCE

MYC+ lymphomas are refractory to standard of care and novel treatments that downregulate MYC are needed. The utility of enitociclib, a selective CDK9 inhibitor in this patient population, is demonstrated in preclinical models and patients. Enitociclib inhibits RNA polymerase II function conferring a transcriptional shift and depletion of MYC and MCL1. Enitociclib intermittent dosing downregulates transcription factors including MYC, providing a therapeutic window for durable responses in patients with MYC+ lymphoma.

TP53RK Drives the Progression of Chronic Kidney Disease by Phosphorylating Birc5

Renal fibrosis is a common characteristic of various chronic kidney diseases (CKDs) driving the loss of renal function. During this pathological process, persistent injury to renal tubular epithelial cells and activation of fibroblasts chiefly determine the extent of renal fibrosis. In this study, the role of tumor protein 53 regulating kinase (TP53RK) in the pathogenesis of renal fibrosis and its underlying mechanisms is investigated. TP53RK is upregulated in fibrotic human and animal kidneys with a positive correlation to kidney dysfunction and fibrotic markers. Interestingly, specific deletion of TP53RK either in renal tubule or in fibroblasts in mice can mitigate renal fibrosis in CKD models. Mechanistic investigations reveal that TP53RK phosphorylates baculoviral IAP repeat containing 5 (Birc5) and facilitates its nuclear translocation; enhanced Birc5 displays a profibrotic effect possibly via activating PI3K/Akt and MAPK pathways. Moreover, pharmacologically inhibiting TP53RK and Birc5 using fusidic acid (an FDA-approved antibiotic) and YM-155(currently in clinical phase 2 trials) respectively both ameliorate kidney fibrosis. These findings demonstrate that activated TP53RK/Birc5 signaling in renal tubular cells and fibroblasts alters cellular phenotypes and drives CKD progression. A genetic or pharmacological blockade of this axis serves as a potential strategy for treating CKDs.

Genome-scale functional genomics identify genes preferentially essential for multiple myeloma cells compared to other neoplasias

Clinical progress in multiple myeloma (MM), an incurable plasma cell (PC) neoplasia, has been driven by therapies that have limited applications beyond MM/PC neoplasias and do not target specific oncogenic mutations in MM. Instead, these agents target pathways critical for PC biology yet largely dispensable for malignant or normal cells of most other lineages. Here we systematically characterized the lineage-preferential molecular dependencies of MM through genome-scale clustered regularly interspaced short palindromic repeats (CRISPR) studies in 19 MM versus hundreds of non-MM lines and identified 116 genes whose disruption more significantly affects MM cell fitness compared with other malignancies. These genes, some known, others not previously linked to MM, encode transcription factors, chromatin modifiers, endoplasmic reticulum components, metabolic regulators or signaling molecules. Most of these genes are not among the top amplified, overexpressed or mutated in MM. Functional genomics approaches thus define new therapeutic targets in MM not readily identifiable by standard genomic, transcriptional or epigenetic profiling analyses.

Past, Present, and a Glance into the Future of Multiple Myeloma Treatment

Multiple myeloma (MM) is a challenging hematological cancer which typically grows in bone marrow. MM accounts for 10% of hematological malignancies and 1.8% of cancers. The recent treatment strategies have significantly improved progression-free survival for MM patients in the last decade; however, a relapse for most MM patients is inevitable. In this review we discuss current treatment, important pathways for proliferation, survival, immune suppression, and resistance that could be targeted for future treatments.

Mechanism of immunomodulatory drug resistance and novel therapeutic strategies in multiple myeloma

OBJECTIVE

The mechanism of immunomodulatory drugs (IMiDs) resistance to multiple myeloma (MM) cells has been gradually demonstrated by recently studies, and some potential novel strategies have been confirmed to have antimyeloma activity and be associated with IMiD activity in MM.

METHODS

This article searched the Pubmed library, reviewed some recently studies related to IMiD resistance to MM cells and summarized some potent agents to improve IMiD resistance to MM cells.

RESULTS

Studies have confirmed that cereblon is a primary direct protein target of IMiDs. IRF4 not only is affected by the IKZF protein but also can directly inhibit the expression of BMF and BIM, thereby promoting the survival of MM cells. Additionally, the expression of IRF4 and MYC also plays an important role in three important signaling pathways (Wnt, STAT3 and MAPK/ERK) related to IMiD resistance. Notably, MYC, a downstream factor of IRF4, may be upregulated by BRD4, and upregulation of MYC promotes cell proliferation in MM and disease progression. Recently, some novel therapeutic agents targeting BRD4, a histone modification-related 'reader' of epigenetic marks, or other important factors (e.g. TAK1) in relevant signaling pathways have been developed and they may provide new options for relapse/refractory MM therapy, such as BET inhibitors, CBP/EP300 inhibitors, dual-target BET-CBP/EP300 inhibitors, TAK1 inhibitors, and they may provide new options for relapsed/refractory MM therapy.

CONCLUSIONS

Accumulated studies have revealed that some key factors associated with the mechanism of IMiD resistance to MM cells. Some agents represent promising new therapeutics of MM to regulate the IRF4/MYC axis by inhibiting BRD4 expression or signaling pathway activation.

Novel Expression of Thymine Dimers in Renal Cell Carcinoma, Demonstrated through Immunohistochemistry

Despite significant developments in renal cell carcinoma (RCC) detection and molecular pathology, mortality has been steadily rising. Advanced RCC remains an incurable disease. Better clinical management tools, i.e., RCC biomarkers, have yet to emerge. Thymine-dimers (TDs) were traditionally considered photo-dependent pre-mutagenic lesions, occurring exclusively during ultra-violet light exposure. Non-oxidative, direct, and preferential byproducts of DNA photochemical reactions, TDs, have recently shown evidence regarding UVR-independent formation. In this study, we investigate, for the first time, TD expression within RCC tumor tissue and tumor-adjacent healthy renal parenchyma using a TD-targeted IHC monoclonal antibody, clone KTM53. Remarkably, out of the 54 RCCs evaluated, 77.8% showed nuclear TD-expression in RCC tumor tissue and 37% in the tumor-adjacent healthy renal parenchyma. A comprehensive report regarding quantitative/qualitative TD-targeted immunostaining was elaborated. Two main distribution models for TD expression within RCC tumor tissue were identified. Statistical analysis showed significant yet moderate correlations regarding TD-positivity in RCC tissue/tumor-adjacent healthy renal parenchyma and TNM stage at diagnosis/lymphatic dissemination, respectively, indicating possible prognostic relevance. We review possible explanations for UVR-independent TD formation and molecular implications regarding RCC carcinogenesis. Further rigorous molecular analysis is required in order to fully comprehend/validate the biological significance of this newly documented TD expression in RCC.

Patent highlights December 2021-January 2022

A snapshot of noteworthy recent developments in the patent literature of relevance to pharmaceutical and medical research and development.

Kinases on Double Duty: A Review of UniProtKB Annotated Bifunctionality within the Kinome

Phosphorylation facilitates the regulation of all fundamental biological processes, which has triggered extensive research of protein kinases and their roles in human health and disease. In addition to their phosphotransferase activity, certain kinases have evolved to adopt additional catalytic functions, while others have completely lost all catalytic activity. We searched the Universal Protein Resource Knowledgebase (UniProtKB) database for bifunctional protein kinases and focused on kinases that are critical for bacterial and human cellular homeostasis. These kinases engage in diverse functional roles, ranging from environmental sensing and metabolic regulation to immune-host defense and cell cycle control. Herein, we describe their dual catalytic activities and how they contribute to disease pathogenesis.

Analysis of L Antigen Family Member 3 as a Potential Biomarker and Therapeutic Target Associated With the Progression of Hepatocellular Carcinoma

Background

Hepatocellular carcinoma (HCC) is the third cause of cancer-related deaths worldwide. L antigen family member 3 (LAGE3) is a prognostic biomarker and associated with progression in a variety of tumors. However, little has been reported about the role and potential mechanism of LAGE3 in HCC.

Methods

The clinical value and function of LAGE3 in HCC were obtained from multiple online databases. The potential functions and pathways of LAGE3 in HCC were analysed by R package of “clusterProfiler”. LAGE3 knockdown cells were constructed in HepG2, HuH7 and MHCC97H cell lines, respectively. The biological roles of LAGE3 were examined by in vitro and in vivo experiments.

Results

LAGE3 was upregulated in HCC tissues compared with normal tissues, and high expression of LAGE3 was significantly associated with several clinical characteristics and indicated a worse prognosis of HCC. The co-expressed genes of LAGE3 could be enriched in the mTOR signaling pathway in HCC. LAGE3 was upregulated in HCC cell lines. Functionally, knocking down LAGE3 expression not only increased apoptosis and inhibited growth rate, cell death mediated by T cells, colony formation, migration and invasion ability of HCC cell lines in vitro, but also reduced the progression of HCC in the subcutaneous xenotransplanted tumor model.

Conclusion

Our results suggested that LAGE3 served as an oncogenic factor of HCC and could be a potential biomarker and therapeutic target for HCC.

Genetic Aberrations and Interaction of NEK2 and TP53 Accelerate Aggressiveness of Multiple Myeloma

It has been previously shown that (never in mitosis gene A)-related kinase 2 (NEK2) is upregulated in multiple myeloma (MM) and contributes to drug resistance. However, the mechanisms behind this upregulation remain poorly understood. In this study, it is found that amplification of NEK2 and hypermethylation of distal CpG islands in its promoter correlate strongly with increased NEK2 expression. Patients with NEK2 amplification have a poor rate of survival and often exhibit TP53 deletion, which is an independent prognostic factor in MM. This combination of TP53 knockout and NEK2 overexpression induces asymmetric mitosis, proliferation, drug resistance, and tumorigenic behaviors in MM in vitro and in vivo. In contrast, delivery of wild type p53 and suppression of NEK2 in TP53^-/- MM cell lines inhibit tumor formation and enhance the effect of Bortezomib against MM. It is also discovered that inactivating p53 elevates NEK2 expression genetically by inducing NEK2 amplification, transcriptionally by increased activity of cell cycle-related genes like E2F8 and epigenetically by upregulating DNA methyltransferases. Dual defects of TP53 and NEK2 may define patients with the poorest outcomes in MM with p53 inactivation, and NEK2 may serve as a novel therapeutic target in aggressive MM with p53 abnormalities.

Differentially Expressed Circular Non-coding RNAs in Atherosclerotic Aortic Vessels and Their Potential Functions in Endothelial Injury

Background: Circular non-coding RNA (circRNA) has a variety of biological functions. However, the expression profile and potential effects of circRNA on atherosclerosis (AS) and vascular endothelial injury have not been fully elucidated. This study aims to identify the differentially expressed circRNAs in atherosclerotic aortic vessels and predict their potential functions in endothelial injury.

Method: ApoE-/- mice were fed with high-fat diet for 12 weeks to induce AS. Atherosclerotic plaques were evaluated by H&E and Masson staining and immunohistochemistry; differentially expressed circRNAs were detected by Arraystar Circular RNA Microarray and verified by RT-PCR; the potential target mircoRNAs of circRNAs were predicted by miRanda, Tarbase, Targetscan and their expression changes were verified by RT-PCR; the potential target genes of mircoRNAs were predicted by Targetscan and verified by Western blot; the signaling pathways that they might annotate or regulate and their potential functions in vascular endothelial injury were predicted by gene enrichment analysis.

Results: Fifty two circRNAs were up-regulated more than twice and 47 circRNAs were down-regulated more than 1.5 times in AS aortic vessels. Mmmu_circRNA_36781 and 37699 were up-regulated both in AS aortic vessels and H₂O₂-treated mouse aortic endothelial cells (MAECs). The expression of miR-30d-3p and miR-140-3p, the target microRNA of circRNA_37699 and circRNA_36781, were downregulated both in AS vessels and H₂O₂-treated MAECs. On the contrary, MKK6 and TP53RK, the potential target gene of miR-140-3p and miR-30d-3p, were upregulated both in AS aortic roots and H₂O₂-treated MAECs. Besides, gene enrichment analysis showed that MAPK and PI3K-AKT signaling pathway were the most potential signaling pathways regulated by the differentially expressed circRNAs in atherosclerosis.

Conclusions: Mmu_circRNA_36781 (circRNA ABCA1) and 37699 (circRNA KHDRBS1) were significantly up-regulated in AS aortic vessels and H₂O₂-treated MAECs. They have potential regulatory effects on atherosclerosis and vascular endothelial injury by targeting miR-30d-3p-TP53RK and miR-140-3p-MKK6 axis and their downstream signaling pathways.

ERK signaling mediates resistance to immunomodulatory drugs in the bone marrow microenvironment

Immunomodulatory drugs (IMiDs) have markedly improved patient outcome in multiple myeloma (MM); however, resistance to IMiDs commonly underlies relapse of disease. Here, we identify that tumor necrosis factor (TNF) receptor-associated factor 2 (TRAF2) knockdown (KD)/knockout (KO) in MM cells mediates IMiD resistance via activation of noncanonical nuclear factor κB (NF-κB) and extracellular signal-regulated kinase (ERK) signaling. Within MM bone marrow (BM) stromal cell supernatants, TNF-α induces proteasomal degradation of TRAF2, noncanonical NF-κB, and downstream ERK signaling in MM cells, whereas interleukin-6 directly triggers ERK activation. RNA sequencing of MM patient samples shows nearly universal ERK pathway activation at relapse on lenalidomide maintenance therapy, confirming its clinical relevance. Combination MEK inhibitor treatment restores IMiD sensitivity of TRAF2 KO cells both in vitro and in vivo. Our studies provide the framework for clinical trials of MEK inhibitors to overcome IMiD resistance in the BM microenvironment and improve patient outcome in MM.

Immunomodulatory drugs suppress Th1-inducing ability of dendritic cells but enhance Th2-mediated allergic responses

Immunomodulatory drugs (IMiDs), lenalidomide and pomalidomide, are widely used treatments for multiple myeloma; however, they occasionally lead to episodes of itchy skin and rashes. Here, we analyzed the effects of IMiDs on human myeloid dendritic cells (mDCs) as major regulators of Th1 or Th2 responses and the role they play in allergy. We found that lenalidomide and pomalidomide used at clinical concentrations did not affect the survival or CD86 and OX40-ligand expression of blood mDCs in response to lipopolysaccharide (LPS) and thymic stromal lymphopoietin (TSLP) stimulation. Both lenalidomide and pomalidomide dose-dependently inhibited interleukin-12 (IL-12) and TNF production and STAT4 expression, and enhanced IL-10 production in response to LPS. When stimulated with TSLP, both IMiDs significantly enhanced CCL17 production and STAT6 and IRF4 expression and promoted memory Th2-cell responses. In 46 myeloma patients, serum CCL17 levels at the onset of lenalidomide-associated rash were significantly higher than those without rashes during lenalidomide treatment and those before treatment. Furthermore, serum CCL17 levels in patients who achieved a very good partial response (VGPR) were significantly higher compared with a less than VGPR during lenalidomide treatment. The median time to next treatment was significantly longer in lenalidomide-treated patients with rashes than those without. Collectively, IMiDs suppressed the Th1-inducing capacity of DCs, instead promoting a Th2 response. Thus, the lenalidomide-associated rashes might be a result of an allergic response driven by Th2-axis activation. Our findings suggest clinical efficacy and rashes as a side effect of IMiDs are inextricably linked through immunostimulation.

Facts and Hopes in Multiple Myeloma Immunotherapy

Among the hallmarks of cancer is the ability of neoplastic cells to evade and suppress immune surveillance to allow their growth and evolution. Nowhere is this as apparent as in multiple myeloma, a cancer of antibody-producing plasma cells, where a complex interplay between neoplastic cells and the immune microenvironment is required for the development and progression of disease. Decades of research has led to the discovery of a number of therapeutic agents, from cytotoxic drugs to genetically engineered cells that mediate their antimyeloma effects at least partially through altering these immune interactions. In this review, we discuss the history of immunotherapy and current practices in multiple myeloma, as well as the advances that promise to one day offer a cure for this deadly disease.

Small-molecule HDAC and Akt inhibitors suppress tumor growth and enhance immunotherapy in multiple myeloma

Background

Multiple myeloma (MM) is an incurable disease. The acquisition of resistance to drugs, including immunomodulatory drugs (IMiDs), has a negative effect on its prognosis. Cereblon (CRBN) is a key mediator of the bioactivities of IMiDs such as lenalidomide. Moreover, genetic alteration of CRBN is frequently detected in IMiD-resistant patients and is considered to contribute to IMiD resistance. Thus, overcoming resistance to drugs, including IMiDs, is expected to improve clinical outcomes. Here, we examined potential mechanisms of a histone deacetylase (HDAC) inhibitor and Akt inhibitor in relapsed/refractory MM patients.

Methods

We established lenalidomide-resistant cells by knocking down CRBN with RNAi-mediated downregulation or knocking out CRBN using CRISPR-Cas9 in MM cells. Additionally, we derived multi-drug (bortezomib, doxorubicin, or dexamethasone)-resistant cell lines and primary cells from relapsed/refractory MM patients. The effects of HDAC and Akt inhibitors on these drug-resistant MM cells were then observed with a particular focus on whether HDAC inhibitors enhance immunotherapy efficacy. We also investigated the effect of lenalidomide on CRBN-deficient cells.

Results

The HDAC inhibitor suppressed the growth of drug-resistant MM cell lines and enhanced the antibody-dependent cellular cytotoxicity (ADCC) of therapeutic antibodies by upregulating natural killer group 2D (NKG2D) ligands in MM cells. CRBN-deficient cells showed lenalidomide-induced upregulation of phosphorylated glycogen synthase kinase-3 (p-GSK-3) and c-Myc phosphorylation. Moreover, HDAC and Akt inhibitors downregulated c-Myc by blocking GSK-3 phosphorylation. HDAC and Akt inhibitors also exhibited synergistic cytotoxic and c-Myc-suppressive effects. The dual HDAC and PI3K inhibitor, CUDC-907, exhibited cytotoxic and immunotherapy-enhancing effects in MM cells, including multi-drug-resistant lines and primary cells from lenalidomide-resistant patients.

Conclusions

The combination of an HDAC and an Akt inhibitor represents a promising approach for the treatment of relapsed/refractory MM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-021-01909-7.

Crystal structure of the human PRPK-TPRKB complex

Mutations of the p53-related protein kinase (PRPK) and TP53RK-binding protein (TPRKB) cause Galloway-Mowat syndrome (GAMOS) and are found in various human cancers. We have previously shown that small compounds targeting PRPK showed anti-cancer activity against colon and skin cancer. Here we present the 2.53 Å crystal structure of the human PRPK-TPRKB-AMPPNP (adenylyl-imidodiphosphate) complex. The structure reveals details in PRPK-AMPPNP coordination and PRPK-TPRKB interaction. PRPK appears in an active conformation, albeit lacking the conventional kinase activation loop. We constructed a structural model of the human EKC/KEOPS complex, composed of PRPK, TPRKB, OSGEP, LAGE3, and GON7. Disease mutations in PRPK and TPRKB are mapped into the structure, and we show that one mutation, PRPK K238Nfs*2, lost the binding to OSGEP. Our structure also makes the virtual screening possible and paves the way for more rational drug design.

Jian Li and Xinli Ma et al. present a 2.53 Å crystal structure of a complex consisting of the human p53-related protein kinase (PRPK), TP53RK-binding protein, and adenylyl-imidodiphosphate. They find that one disease mutation, PRPK K238Nfs*2, is important for PRPK’s binding to O-sialoglycoprotein endopeptidase, providing insights into rational drug design.

Immunotherapy and Immunomodulation in Myeloproliferative Neoplasms

Myeloproliferative neoplasms are characterized by chronic inflammation. The discovery of constitutively active JAK-STAT signaling associated with driver mutations has led to clinical and translational breakthroughs. Insights into the other pathways and novel factors of potential importance are being actively investigated. Various classes of agents with immunomodulating or immunosuppressive properties have been used with varying degrees of success in treating myeloproliferative neoplasms. Early clinical trials are investigating the feasibility, effectiveness, and safety of immune checkpoint inhibitors, cell-based immunotherapies, and SMAC mimetics. The dynamic landscape of immunotherapy and immunomodulation in myeloproliferative neoplasms is the topic of the present review.

Immunomodulatory drugs activate NK cells via both Zap-70 and cereblon-dependent pathways

Immunomodulatory drugs (IMiDs) lenalidomide and pomalidomide show remarkable anti-tumor activity in multiple myeloma (MM) via directly inhibiting MM cell growth in the bone marrow (BM) microenvironment and promoting immune effector cell function. They are known to bind to the ubiquitin 3 ligase CRBN complex and thereby trigger degradation of IKZF1/3. In this study, we demonstrate that IMiDs also directly bind and activate zeta-chain-associated protein kinase-70 (Zap-70) via its tyrosine residue phosphorylation in T cells. IMiDs also triggered phosphorylation of Zap-70 in NK cells. Importantly, increased granzyme-B (GZM-B) expression and NK cell activity triggered by IMiDs is associated with Zap-70 activation and inhibited by Zap-70 knockdown, independent of CRBN. We also demonstrate a second mechanism whereby IMiDs trigger GZM-B and NK cytotoxicity which is CRBN- and IKZF3-mediated and inhibited by knockdown of CRBN or IKZF-3, independent of Zap-70. Our studies therefore show that IMiDs can enhance NK and T cell cytotoxicity in (1) ZAP-70-mediated CRBN independent, as well as (2) CRBN-mediated ZAP-70 independent mechanisms; and provide the framework for developing novel therapeutics to activate Zap-70 and thereby enhance T and NK anti-MM cytotoxicity.

Thalidomide Inhibits Human iPSC Mesendoderm Differentiation by Modulating CRBN-dependent Degradation of SALL4

Exposure to thalidomide during a critical window of development results in limb defects in humans and non-human primates while mice and rats are refractory to these effects. Thalidomide-induced teratogenicity is dependent on its binding to cereblon (CRBN), the substrate receptor of the Cul4A-DDB1-CRBN-RBX1 E3 ubiquitin ligase complex. Thalidomide binding to CRBN elicits subsequent ubiquitination and proteasomal degradation of CRBN neosubstrates including SALL4, a transcription factor of which polymorphisms phenocopy thalidomide-induced limb defects in humans. Herein, thalidomide-induced degradation of SALL4 was examined in human induced pluripotent stem cells (hiPSCs) that were differentiated either to lateral plate mesoderm (LPM)-like cells, the developmental ontology of the limb bud, or definitive endoderm. Thalidomide and its immunomodulatory drug (IMiD) analogs, lenalidomide, and pomalidomide, dose-dependently inhibited hiPSC mesendoderm differentiation. Thalidomide- and IMiD-induced SALL4 degradation can be abrogated by CRBN V388I mutation or SALL4 G416A mutation in hiPSCs. Genetically modified hiPSCs expressing CRBN E377V/V388I mutant or SALL4 G416A mutant were insensitive to the inhibitory effects of thalidomide, lenalidomide, and pomalidomide on LPM differentiation while retaining sensitivity to another known limb teratogen, all-trans retinoic acid (atRA). Finally, disruption of LPM differentiation by atRA or thalidomide perturbed subsequent chondrogenic differentiation in vitro. The data here show that thalidomide, lenalidomide, and pomalidomide affect stem cell mesendoderm differentiation through CRBN-mediated degradation of SALL4 and highlight the utility of the LPM differentiation model for studying the teratogenicity of new CRBN modulating agents.

Bone marrow morphologic features, MyPRS, and gene mutation correlations in plasma cell myeloma

Genetics has played an important role in risk stratification for plasma cell myeloma patients, providing therapeutic guidance. In this study, we investigated the correlation of bone marrow morphologic features and genetic aberrations, including gene expression profiles, translocations, and gene mutations. For the first time we show that high plasma cell volume, diffuse sheet growth pattern, immature cell morphology, high mitotic index, and increased reticulin fibrosis, significantly correlates with high risk disease determined by MyPRS gene expression profiles. Furthermore, we show the association between MyPRS risk stratification and chromosomal alterations and specific gene mutations. We also demonstrate the combinational effect of TP53 mutation and 17p loss on the histological changes in bone marrow.

High expression of chaperonin-containing TCP1 subunit 3 may induce dismal prognosis in multiple myeloma

The prognosis role of CCT3 in MM and the possible pathways it involved were studied in our research. By analyzing ten independent datasets (including 48 healthy donors, 2220 MM, 73 MGUS, and 6 PCL), CCT3 was found to express higher in MM than healthy donors, and the expression level was gradually increased from MGUS, SMM, MM to PCL (all P < 0.01). By analyzing three independent datasets (GSE24080, GSE2658, and GSE4204), we found that CCT3 was a significant indicator of poor prognosis (all P < 0.01). KEGG and GSEA analysis showed that CCT3 expression was associated with JAK-STAT3 pathway, Hippo signaling pathway, and WNT signaling pathway. In addition, different expressed genes analysis revealed MYC, which was one of the downstream genes regulated by JAK-STAT3 pathway, was upregulated in MM. This confirms that JAK-STAT3 signaling pathway may promote the progress of disease which was regulated by CCT3 expression. Our study revealed that CCT3 may play a supporting role at the diagnosis of myeloid, and high expression of CCT3 suggested poor prognosis in MM. CCT3 expression may promote the progression of MM mainly by regulating MYC through JAK-STAT3 signaling pathway.

Systematic screening for potential therapeutic targets in osteosarcoma through a kinome-wide CRISPR-Cas9 library

Objective: Osteosarcoma is the most common primary malignant bone tumor. However, the survival of patients with osteosarcoma has remained unchanged during the past 30 years, owing to a lack of efficient therapeutic targets.

Methods: We constructed a kinome-targeting CRISPR-Cas9 library containing 507 kinases and 100 nontargeting controls and screened the potential kinase targets in osteosarcoma. The CRISPR screening sequencing data were analyzed with the Model-based Analysis of Genome-wide CRISPR/Cas9 Knockout (MAGeCK) Python package. The functional data were applied in the 143B cell line through lenti-CRISPR-mediated gene knockout. The clinical significance of kinases in the survival of patients with osteosarcoma was analyzed in the R2: Genomics Analysis and Visualization Platform.

Results: We identified 53 potential kinase targets in osteosarcoma. Among these targets, we analyzed 3 kinases, TRRAP, PKMYT1, and TP53RK, to validate their oncogenic functions in osteosarcoma. PKMYT1 and TP53RK showed higher expression in osteosarcoma than in normal bone tissue, whereas TRRAP showed no significant difference. High expression of all 3 kinases was associated with relatively poor prognosis in patients with osteosarcoma.

Conclusions: Our results not only offer potential therapeutic kinase targets in osteosarcoma but also provide a paradigm for functional genetic screening by using a CRISPR-Cas9 library, including target design, library construction, screening workflow, data analysis, and functional validation. This method may also be useful in potentially accelerating drug discovery for other cancer types.

Regulatory mechanisms of B cell responses and the implication in B cell-related diseases

Terminally differentiated B cell, the plasma cell, is the sole cell type capable of producing antibodies in our body. Over the past 30 years, the identification of many key molecules controlling B cell activation and differentiation has elucidated the molecular pathways for generating antibody-producing plasma cells. Several types of regulation modulating the functions of the important key molecules in B cell activation and differentiation add other layers of complexity in shaping B cell responses following antigen exposure in the absence or presence of T cell help. Further understanding of the mechanisms contributing to the proper activation and differentiation of B cells into antibody-secreting plasma cells may enable us to develop new strategies for managing antibody humoral responses during health and disease. Herein, we reviewed the effect of different types of regulation, including transcriptional regulation, post-transcriptional regulation and epigenetic regulation, on B cell activation, and on mounting memory B cell and antibody responses. We also discussed the link between the dysregulation of the abovementioned regulatory mechanisms and B cell-related disorders.

Identification of TP53RK-Binding Protein (TPRKB) Dependency in TP53-Deficient Cancers

Tumor protein 53 (TP53; p53) is the most frequently altered gene in human cancer. Identification of vulnerabilities imposed by TP53 alterations may enable effective therapeutic approaches. Through analyzing short hairpin RNA (shRNA) screening data, we identified TP53RK-Binding Protein (TPRKB), a poorly characterized member of the tRNA-modifying EKC/KEOPS complex, as the most significant vulnerability in TP53-mutated cancer cell lines. In vitro and in vivo, across multiple benign-immortalized and cancer cell lines, we confirmed that TPRKB knockdown in TP53-deficient cells significantly inhibited proliferation, with minimal effect in TP53 wild-type cells. TP53 reintroduction into TP53-null cells resulted in loss of TPRKB sensitivity, confirming the importance of TP53 status in this context. In addition, cell lines with mutant TP53 or amplified MDM2 (E3-ubiquitin ligase for TP53) also showed high sensitivity to TPRKB knockdown, consistent with TPRKB dependence in a wide array of TP53-altered cancers. Depletion of other EKC/KEOPS complex members exhibited TP53-independent effects, supporting complex-independent functions of TPRKB. Finally, we found that TP53 indirectly mediates TPRKB degradation, which was rescued by coexpression of PRPK, an interacting member of the EKC/KEOPS complex, or proteasome inhibition. Together, these results identify a unique and specific requirement of TPRKB in a variety of TP53-deficient cancers. IMPLICATIONS: Cancer cells with genomic alterations in TP53 are dependent on TPRKB.

Matching tRNA modifications in humans to their known and predicted enzymes

tRNA are post-transcriptionally modified by chemical modifications that affect all aspects of tRNA biology. An increasing number of mutations underlying human genetic diseases map to genes encoding for tRNA modification enzymes. However, our knowledge on human tRNA-modification genes remains fragmentary and the most comprehensive RNA modification database currently contains information on approximately 20% of human cytosolic tRNAs, primarily based on biochemical studies. Recent high-throughput methods such as DM-tRNA-seq now allow annotation of a majority of tRNAs for six specific base modifications. Furthermore, we identified large gaps in knowledge when we predicted all cytosolic and mitochondrial human tRNA modification genes. Only 48% of the candidate cytosolic tRNA modification enzymes have been experimentally validated in mammals (either directly or in a heterologous system). Approximately 23% of the modification genes (cytosolic and mitochondrial combined) remain unknown. We discuss these 'unidentified enzymes' cases in detail and propose candidates whenever possible. Finally, tissue-specific expression analysis shows that modification genes are highly expressed in proliferative tissues like testis and transformed cells, but scarcely in differentiated tissues, with the exception of the cerebellum. Our work provides a comprehensive up to date compilation of human tRNA modifications and their enzymes that can be used as a resource for further studies.

Unraveling the Prenylation-Cancer Paradox in Multiple Myeloma with Novel Geranylgeranyl Pyrophosphate Synthase (GGPPS) Inhibitors

Post-translational prenylation of the small GTP-binding proteins (GTPases) is vital to a plethora of biological processes, including cellular proliferation. We have identified a new class of thienopyrimidine-based bisphosphonate (ThP-BP) inhibitors of the human geranylgeranyl pyrophosphate synthase (hGGPPS) that block protein prenylation in multiple myeloma (MM) cells leading to cellular apoptosis. These inhibitors are also effective in blocking the proliferation of other types of cancer cells. We confirmed intracellular target engagement, demonstrated the mechanism of action leading to apoptosis, and determined a direct correlation between apoptosis and intracellular inhibition of hGGPPS. Administration of a ThP-BP inhibitor to a MM mouse model confirmed in vivo downregulation of Rap1A geranylgeranylation and reduction of monoclonal immunoglobulins (M-protein, a biomarker of disease burden) in the serum. These results provide the first proof-of-principle that hGGPPS is a valuable therapeutic target in oncology and more specifically for the treatment of multiple myeloma.

A genome-scale CRISPR-Cas9 screening in myeloma cells identifies regulators of immunomodulatory drug sensitivity

Immunomodulatory drugs (IMiDs) including lenalidomide and pomalidomide bind cereblon (CRBN) and activate the CRL4^CRBN ubiquitin ligase to trigger proteasomal degradation of the essential transcription factors IKZF1 and IKZF3 and multiple myeloma (MM) cytotoxicity. We have shown that CRBN is also targeted for degradation by SCF^Fbxo7 ubiquitin ligase. In the current study, we explored the mechanisms underlying sensitivity of MM cells to IMiDs using genome-wide CRISPR-Cas9 screening. We validate that CSN9 signalosome complex, a deactivator of Cullin-RING ubiquitin ligase, inhibits SCF^Fbxo7 E3 ligase-mediated CRBN degradation, thereby conferring sensitivity to IMiDs; conversely, loss of function of CSN9 signalosome activates SCF^Fbxo7 complex, thereby enhancing degradation of CRBN and conferring IMiD resistance. Finally, we show that pretreatment with either proteasome inhibitors or NEDD8 activating enzyme (NAE) inhibitors can abrogate degradation and maintain levels of CRBN, thereby enhancing sensitivity to IMiDs. These studies therefore demonstrate that CSN9 signalosome complex regulates sensitivity to IMiDs by modulating CRBN expression.

Update on the role of lenalidomide in patients with multiple myeloma

Lenalidomide is a derivative of thalidomide and belongs to the class of drugs known as the immunomodulatory drugs (IMiDs). The IMiDs have played a large role in improving the survival outcomes of patients with multiple myeloma. In particular, lenalidomide is currently standard of care in the newly diagnosed setting, in the maintenance setting post-autologous stem cell transplant, as well as in the relapsed/refractory setting. While the combination of lenalidomide and various proteasome inhibitors has proven particularly effective, there are emerging data demonstrating the effectiveness of lenalidomide in combination with other important classes of drugs including the monoclonal antibodies. Recent studies have provided insight into the molecular target of lenalidomide and the other IMiDs, although there is still much to be learned regarding the mechanisms by which lenalidomide affects the myeloma cell and the immune system. Here we review the molecular mechanisms of action, side effects, and the results of the clinical trials which have led to the widespread incorporation of lenalidomide into the myeloma therapeutic armamentarium.

Prognostic and clinicopathological value of p53 expression in renal cell carcinoma: a meta-analysis

Background

The prognostic value of p53 expression in renal cell carcinoma (RCC) had been investigated in previous studies; however, the results remain inconsistent. This study was performed to investigate the prognostic and clinicopathological significance of p53 protein expression in RCC.

Materials and Methods

Literature was identified from PubMed, Embase, Web of Science, and Cochrane database, which investigated the relationships between p53 expression and outcomes. Hazard ratios (HRs) for survival outcomes and odds ratios (ORs) for clinical parameters associated with p53 were extracted from eligible studies. Heterogeneity was assessed using the I2 value. The fixed-effects model was used if there was no evidence of heterogeneity; otherwise, the random-effects model was used. Publication bias was evaluated using Begg's funnel plots and Egger's regression test.

Results

A total of 2,013 patients from 22 studies were included in the meta-analysis. The results showed that p53 positive expression is associated with poor overall survival (OS) (HR = 2.17, 95% confidence [CI]: 1.51–3.13) and cancer-specific survival (CSS) (HR = 1.59, 95% CI: 1.19–2.12) in RCC. In addition, p53 positive expression was closely correlated with TNM stage (III/IV vs. I/II: OR = 2.51, 95% CI: 1.05–6.00), Fuhrman grade (III/IV vs. I/II: OR = 1.80, 95% CI: 1.24–2.63), and distant metastasis (M1 vs. M0: OR = 1.70, 95% CI: 1.16–2.49), but not related to lymph node involvement (N1 vs. N0: OR = 1.32, 95% CI: 0.80–2.18), primary tumor stage (pT3/pT4 vs. pT1/pT2: OR = 1.16, 95% CI: 0.88–1.53), and sex (n = 2, male vs. female, OR = 1.09, 95% CI: 0.70–1.68).

Conclusions

This study suggests that p53 positive expression is correlated with poor prognosis and advanced clinicopathological features in patients with RCC, which indicates that p53 is a potentially effective therapeutic target.