Activating KRAS, NRAS, and BRAF mutants enhance proteasome capacity and reduce endoplasmic reticulum stress in multiple myeloma

Leukemic Stem Cells and Hematological Malignancies

The association between leukemic stem cells (LSCs) and leukemia development has been widely established in the context of genetic alterations, epigenetic pathways, and signaling pathway regulation. Hematopoietic stem cells are at the top of the bone marrow hierarchy and can self-renew and progressively generate blood and immune cells. The microenvironment, niche cells, and complex signaling pathways that regulate them acquire genetic mutations and epigenetic alterations due to aging, a chronic inflammatory environment, stress, and cancer, resulting in hematopoietic stem cell dysregulation and the production of abnormal blood and immune cells, leading to hematological malignancies and blood cancer. Cells that acquire these mutations grow at a faster rate than other cells and induce clone expansion. Excessive growth leads to the development of blood cancers. Standard therapy targets blast cells, which proliferate rapidly; however, LSCs that can induce disease recurrence remain after treatment, leading to recurrence and poor prognosis. To overcome these limitations, researchers have focused on the characteristics and signaling systems of LSCs and therapies that target them to block LSCs. This review aims to provide a comprehensive understanding of the types of hematopoietic malignancies, the characteristics of leukemic stem cells that cause them, the mechanisms by which these cells acquire chemotherapy resistance, and the therapies targeting these mechanisms.

ctDNA improves prognostic prediction for patients with relapsed/refractory MM receiving ixazomib, lenalidomide, and dexamethasone

ABSTRACT

It remains elusive how driver mutations, including those detected in circulating tumor DNA (ctDNA), affect prognosis in relapsed/refractory multiple myeloma (RRMM). Here, we performed targeted-capture sequencing using bone marrow plasma cells (BMPCs) and ctDNA of 261 RRMM cases uniformly treated with ixazomib, lenalidomide, and dexamethasone in a multicenter, prospective, observational study. We detected 24 and 47 recurrently mutated genes in BMPC and ctDNA, respectively. In addition to clonal hematopoiesis-associated mutations, varying proportion of driver mutations, particularly TP53 mutations (59.2% of mutated cases), were present in only ctDNA, suggesting their subclonal origin. In univariable analyses, ctDNA mutations of KRAS, TP53, DIS3, BRAF, NRAS, and ATM were associated with worse progression-free survival (PFS). BMPC mutations of TP53 and KRAS were associated with inferior PFS, whereas KRAS mutations were prognostically relevant only when detected in both BMPC and ctDNA. A total number of ctDNA mutations in the 6 relevant genes was a strong prognostic predictor (2-year PFS rates: 57.3%, 22.7%, and 0% for 0, 1, and ≥2 mutations, respectively) and independent of clinical factors and plasma DNA concentration. Using the number of ctDNA mutations, plasma DNA concentration, and clinical factors, we developed a prognostic index, classifying patients into 3 categories with 2-year PFS rates of 57.9%, 28.6%, and 0%. Serial analysis of ctDNA mutations in 94 cases revealed that TP53 and KRAS mutations frequently emerge after therapy. Thus, we clarify the genetic characteristics and clonal architecture of ctDNA mutations and demonstrate their superiority over BMPC mutations for prognostic prediction in RRMM. This study is a part of the C16042 study, which is registered at www.clinicaltrials.gov as #NCT03433001.

Multikinase inhibitors modulate non-constitutive proteasome expression in colorectal cancer cells

Introduction: Proteasomes are multi-subunit protein complexes responsible for protein degradation in cells. Immunoproteasomes and intermediate proteasomes (together non-constitutive proteasomes) are specific forms of proteasomes frequently associated with immune response, antigen presentation, inflammation and stress. Expression of non-constitutive proteasome subunits has a prognostic value in several types of cancer. Thus, factors that modulate non-constitutive proteasome expression in tumors are of particular interest. Multikinase inhibitors (MKIs) demonstrate promising results in treatment of cancer. At the same time, their immunomodulatory properties and effects on non-constitutive proteasome expression in colorectal cancer cells are poorly investigated. Methods: Proteasome subunit expression in colorectal cancer was evaluated by bioinformatic analysis of available datasets. Two colorectal cancer cell lines, expressing fluorescent non-constitutive proteasomes were treated with multikinase inhibitors: regorafenib and sorafenib. The proteasome subunit expression was assessed by real-time PCR, Western blotting and flow cytometry. The proteasome activity was studied using proteasome activity-based probe and fluorescent substrates. Intracellular proteasome localization was revealed by confocal microscopy. Reactive oxygen species levels following treatment were determined in cells. Combined effect of proteasome inhibition and treatment with MKIs on viability of cells was estimated. Results: Expression of non-constitutive proteasomes is increased in BRAF-mutant colorectal tumors. Regorafenib and sorafenib stimulated the activity and synthesis of non-constitutive proteasomes in examined cell lines. MKIs induced oxidative stress and redistribution of proteasomes within cells. Sorafenib stimulated formation of cytoplasmic aggregates, containing proteolyticaly active non-constitutive proteasomes, while regorafenib had no such effect. MKIs caused no synergistic action when were combined with the proteasome inhibitor. Discussion: Obtained results indicate that MKIs might affect the crosstalk between cancer cells and immune cells via modulation of intracellular proteasome pool. Observed phenomenon should be considered when MKI-based therapy is applied.

Targeting RAF dimers in RAS mutant tumors: From biology to clinic

RAS mutations occur in approximately 30% of tumors worldwide and have a poor prognosis due to limited therapies. Covalent targeting of KRAS G12C has achieved significant success in recent years, but there is still a lack of efficient therapeutic approaches for tumors with non-G12C KRAS mutations. A highly promising approach is to target the MAPK pathway downstream of RAS, with a particular focus on RAF kinases. First-generation RAF inhibitors have been authorized to treat BRAF mutant tumors for over a decade. However, their use in RAS-mutated tumors is not recommended due to the paradoxical ERK activation mainly caused by RAF dimerization. To address the issue of RAF dimerization, type II RAF inhibitors have emerged as leading candidates. Recent clinical studies have shown the initial effectiveness of these agents against RAS mutant tumors. Promisingly, type II RAF inhibitors in combination with MEK or ERK inhibitors have demonstrated impressive efficacy in RAS mutant tumors. This review aims to clarify the importance of RAF dimerization in cellular signaling and resistance to treatment in tumors with RAS mutations, as well as recent progress in therapeutic approaches to address the problem of RAF dimerization in RAS mutant tumors.

Acute accumulation of PIM2 and NRF2 and recovery of β5 subunit activity mitigate multiple myeloma cell susceptibility to proteasome inhibitors

Resistance to proteasome inhibitors (PIs) has emerged as an important clinical issue. We investigated the mechanisms underlying multiple myeloma (MM) cell resistance to PIs. To mimic their pharmacokinetic/pharmacodynamic (PK/PD) profiles, MM cells were treated with bortezomib and carfilzomib for 1 h at concentrations up to 400 and 1,000 nM, respectively. Susceptibility to these PIs markedly varied among MM cell lines. Pulsatile treatments with PIs suppressed translation, as demonstrated by incorporation of puromycin at 24 h in PI-susceptible MM.1S cells, but not PI-resistant KMS-11 cells. Inhibition of β5 subunit activity decreased at 24 h in KMS-11 cells, even with the irreversible PI carfilzomib, but not under suppression of protein synthesis with cycloheximide. Furthermore, the proteasome-degradable pro-survival factors PIM2 and NRF2 acutely accumulated in MM cells subjected to pulsatile PI treatments. Accumulated NRF2 was trans-localized into the nucleus to induce the expression of its target gene, HMOX1, in MM cells. PIM and Akt inhibition restored the anti-MM effects of PIs, even against PI-resistant KMS-11 cells. Collectively, these results suggest that increased synthesis of β5 proteasome subunit and acute accumulation of PIM2 and NRF2 reduce the anti-MM effects of PIs.

Mechanisms of the role of proto-oncogene activation in promoting malignant transformation of mature B cells

Malignant tumors continue to pose a significant threat to human life and safety and their development is primarily due to the activation of proto-oncogenes and the inactivation of suppressor genes. Among these, the activation of proto-oncogenes possesses greater potential to drive the malignant transformation of cells. Targeting oncogenes involved in the malignant transformation of tumor cells has provided a novel approach for the development of current antitumor drugs. Several preclinical and clinical studies have revealed that the development pathway of B cells, and the malignant transformation of mature B cells into tumors have been regulated by oncogenes and their metabolites. Therefore, summarizing the key oncogenes involved in the process of malignant transformation of mature B cells and elucidating the mechanisms of action in tumor development hold significant importance for the clinical treatment of malignant tumors.

DNA Sequencing of CD138 Cell Population Reveals TP53 and RAS-MAPK Mutations in Multiple Myeloma at Diagnosis

Multiple myeloma is a hematologic neoplasm caused by abnormal proliferation of plasma cells. Sequencing studies suggest that plasma cell disorders are caused by both cytogenetic abnormalities and oncogene mutations. Therefore, it is necessary to detect molecular abnormalities to improve the diagnosis and management of MM. The main purpose of this study is to determine whether NGS, in addition to cytogenetics, can influence risk stratification and management. Additionally, we aim to establish whether mutational analysis of the CD138 cell population is a suitable option for the characterization of MM compared to the bulk population. Following the separation of the plasma cells harvested from 35 patients newly diagnosed with MM, we performed a FISH analysis to detect the most common chromosomal abnormalities. Consecutively, we used NGS to evaluate NRAS, KRAS, BRAF, and TP53 mutations in plasma cell populations and in bone marrow samples. NGS data showed that sequencing CD138 cells provides a more sensitive approach. We identified several variants in BRAF, KRAS, and TP53 that were not previously associated with MM. Considering that the presence of somatic mutations could influence risk stratification and therapeutic approaches of patients with MM, sensitive detection of these mutations at diagnosis is essential for optimal management of MM.

Novel mutation in EFEMP1 identified from two Chinese POAG families differentially activated endoplasmic reticulum stress markers and induced glaucoma in mouse

Primary open-angle glaucoma (POAG) is the most common type of glaucoma. Using whole-exome sequencing, we identified two independent families diagnosed as POAG from the China with a novel EFEMP1 variant (Exon3, c.175A>C p.Met59Leu); Three previously reported variants c.1160G>A p.R387Q, c.1189T>C p.Y397H, and c.1429C>T p.R477C in EFEPM1 from 55 sporadic POAG individuals were also identified. The variant c.175A>C p.Met59Leu co-segregated with the disease phenotype within the families. Immunoprecipitation and western blot assays showed that all three EFEMP1 mutants (p.Met59Leu, pArg140Trp, pArg345Trp) increased intracellular protein aggregations, and pMet59Leu and pArg140Arg also enhanced their extracellular proteins secretion, compared to WT in HEK293T. The differential regulations to endoplasmic reticulum (ER) stress markers ATF4, GPR78/94, and CHOP, and differential phosphorylation activations to CREB at Ser133, AKT at Ser473, p44/42 at Thr202/Tyr204, and STAT3 at Tyr705, were also detected among the mutants and WT. Finally, we revealed a significant increment of intraocular pressure and obvious reduction of RGC cells at the sixth week following intravitreal injection of adenovirus 5 (Ad5) expressing in pMet59Leu compared to WT and GFP controls. Together, variant c.175A>C p.Met59Leu in EFEMP1 is pathogenic and different mutants in EFEMP1 triggered distinct signaling pathways, explaining the reason of mutation-dependent disease phenotypes of EFEMP1.

Effect of MAPK activation via mutations in NRAS, KRAS and BRAF on clinical outcome in newly diagnosed multiple myeloma

Until now, next generation sequencing (NGS) data has not been incorporated into any prognostic stratification of multiple myeloma (MM) and no therapeutic considerations are based upon it. In this work, we correlated NGS data with (1) therapy response and survival parameters in newly diagnosed multiple myeloma, treated by VRd * and (2) MM disease stage: newly diagnosed multiple myeloma (ndMM) versus relapsed and/or refractory (relapsed/refractory multiple myeloma). We analyzed 126 patients, with ndMM and relapsed refractory multiple myeloma (rrMM), treated at the University Hospital of Bern (Inselspital). Next generation sequencing was performed on bone marrow, as part of routine diagnostics. The NGS panel comprised eight genes CCND1, DIS3, EGR1, FAM46C (TENT5C), FGFR3, PRDM1, TP53, TRAF3 and seven hotspots in BRAF, IDH1, IDH2, IRF4, KRAS, NRAS. The primary endpoint was complete remission (CR) after VRd in ndMM, in correlation with mutational profile. Mutational load was generally higher in rrMM, with more frequently mutated TP53: 11/87 (13%) in ndMM versus 9/11 (81%) in rrMM (OR 0.0857, p = 0.0007). In ndMM, treated by VRd, mutations in MAPK-pathway members (NRAS, KRAS or BRAF) were associated with reduced probability of CR (21/38, 55%), as compared with wild type NRAS, KRAS or BRAF (34/40, 85%; OR 0.2225, p = 0.006). NRAS c.181C > A (p.Q61K) as a single mutation event showed a trend to reduced probability of achieving CR (OR 0.0912, p = 0.0247). Activation of MAPK pathway via mutated NRAS, KRAS and BRAF genes seems to have a negative impact on outcome in ndMM patients receiving VRd therapy. VRd* - bortezomib (Velcade®), lenalidomide (Revlimid®) and dexamethasone.

LMP2 and TAP2 impair tumor growth and metastasis by inhibiting Wnt/β-catenin signaling pathway and EMT in cervical cancer

BACKGROUND

The roles of low molecular mass polypeptide 2 (LMP2) and transporter-associated with antigen processing (TAP2) in tumorigenesis are controversial. Here we aimed to explore the effect of LMP2 and TAP2 on the oncogenesis and metastasis of cervical cancer cells.

METHODS

The expressions of LMP2 and TAP2 in cervical cancer and normal tissues were determined by qPCR. Plate colony formation, cell counting kit-8 analysis and in vivo tumor xenograft assays were used to detect the tumor growth. Wound healing and transwell assays were used to detect the metastasis of cervical cancer. Gelatin zymography and western blotting assays were used to detect the effect of LMP2 and TAP2 on the EMT and Wnt/β-catenin pathway in cervical cancer cells.

RESULTS

In the present study, we reported that LMP2 and TAP2 levels were overexpressed in cervical cancer. Overexpression of LMP2 and TAP2 impaired the proliferation of Hela cells. In vivo studies substantiated that LMP2 and TAP2 antagonized tumor growth. Likewise, LMP2 and TAP2 overexpression decreased the migration and invasion ability of Hela cells by regulating the process of epithelial-mesenchymal transition (EMT). Mechanically, LMP2 and TAP2 subverted the protein abundance of Wnt1 and β-catenin, thereby downregulating their downstream targets Cyclin D1 and c-Myc. In addition, Wnt1 overexpression partially rescued the observed consequences of ectopic expression of LMP2 and TAP2 in cervical cancer cells. Taken together, our study revealed that LMP2 and TAP2 suppress the oncogenesis and metastasis of cervical cancer cells by Wnt/β-catenin pathway and altering EMT.

CONCLUSION

LMP2 and TAP2 may inhibit the oncogenesis and metastasis of cervical cancer cells by inhibiting the process of EMT and the Wnt/β-catenin signaling pathway, which may provide important insight into prospective targets for the treatment of cervical cancer.

Proteasome inhibitors reduce CD73 expression partly via decreasing p-ERK in NSCLC cells

Ecto-5'-nucleotidase (CD73), encoded by the NT5E gene, mediates tumor immunosuppression and has been targeted for the development of new anticancer drugs. Proteasome inhibitors impair protein degradation by inhibiting proteasome and have been used in the clinic for cancer therapy. Here we report that proteasome inhibitors reduce the protein and mRNA levels of CD73. Among 127 tested small-molecule drugs, proteasome inhibitors were found to consistently decrease the protein and mRNA levels of CD73 in NSCLC NCI-H1299 cells. This effect was further confirmed in different NSCLC cells exposed to different proteasome inhibitors. In those treated cells, the protein levels of ERK and its active form p-ERK, the vital components in the MAPK pathway, were reduced. Consistently, inhibitors of MEK and ERK, another two members of the MAPK pathway, also lowered the protein and mRNA levels of CD73. Correspondingly, treatments with fibroblast growth factor 2 (FGF2), an activator of the MAPK pathway, enhanced the levels of p-ERK and partly rescued the proteasome inhibitor-driven reduction of CD73 mRNA and protein in NSCLC cells. However, exogenous CD73 overexpression in murine Lewis lung carcinoma (LLC) cells was not lowered either in vitro or in vivo, by the treatments with proteasome inhibitors and basically, did not affect their in vitro proliferative inhibition either. In contrast, CD73 overexpression dramatically reduced the in vivo anticancer activity of Bortezomib in immunocompetent mice, with tumor growth inhibition rates from 52.18 % for LLC/vector down to 8.75 % for LLC/NT5E homografts. These findings give new insights into the anticancer mechanisms of proteasome inhibitors.

Optical Genome Mapping Reveals the Complex Genetic Landscape of Myeloma

Fluorescence in situ hybridization (FISH) on enriched CD138 plasma cells is the standard method for identification of clinically relevant genetic abnormalities in multiple myeloma. However, FISH is a targeted analysis that can be challenging due to the genetic complexity of myeloma. The aim of this study was to evaluate the potential of optical genome mapping (OGM) to detect clinically significant cytogenetic abnormalities in myeloma and to provide larger pangenomic information. OGM and FISH analyses were performed on CD138-purified cells of 20 myeloma patients. OGM successfully detected structural variants (SVs) (IGH and MYC rearrangements), copy number variants (CNVs) (17p/TP53 deletion, 1p deletion and 1q gain/amplification) and aneuploidy (gains of odd-numbered chromosomes, monosomy 13) classically expected with myeloma and led to a 30% increase in prognosis yield at our institution when compared to FISH. Despite challenges in the interpretation of OGM calls for CNV and aneuploidy losses in non-diploid genomes, OGM has the potential to replace FISH as the standard of care analysis in clinical settings and to efficiently change how we identify prognostic and predictive markers for therapies in the future. To our knowledge, this is the first study highlighting the feasibility and clinical utility of OGM in myeloma.

Shutting off the fuel supply to target metabolic vulnerabilities in multiple myeloma

Pathways that govern cellular bioenergetics are deregulated in tumor cells and represent a hallmark of cancer. Tumor cells have the capacity to reprogram pathways that control nutrient acquisition, anabolism and catabolism to enhance their growth and survival. Tumorigenesis requires the autonomous reprogramming of key metabolic pathways that obtain, generate and produce metabolites from a nutrient-deprived tumor microenvironment to meet the increased bioenergetic demands of cancer cells. Intra- and extracellular factors also have a profound effect on gene expression to drive metabolic pathway reprogramming in not only cancer cells but also surrounding cell types that contribute to anti-tumor immunity. Despite a vast amount of genetic and histologic heterogeneity within and between cancer types, a finite set of pathways are commonly deregulated to support anabolism, catabolism and redox balance. Multiple myeloma (MM) is the second most common hematologic malignancy in adults and remains incurable in the vast majority of patients. Genetic events and the hypoxic bone marrow milieu deregulate glycolysis, glutaminolysis and fatty acid synthesis in MM cells to promote their proliferation, survival, metastasis, drug resistance and evasion of immunosurveillance. Here, we discuss mechanisms that disrupt metabolic pathways in MM cells to support the development of therapeutic resistance and thwart the effects of anti-myeloma immunity. A better understanding of the events that reprogram metabolism in myeloma and immune cells may reveal unforeseen vulnerabilities and advance the rational design of drug cocktails that improve patient survival.

VCP/p97, a pleiotropic protein regulator of the DNA damage response and proteostasis, is a potential therapeutic target in KRAS-mutant pancreatic cancer

We and others have recently shown that proteins involved in the DNA damage response (DDR) are critical for KRAS-mutant pancreatic ductal adenocarcinoma (PDAC) cell growth in vitro. However, the CRISPR-Cas9 library that enabled us to identify these key proteins had limited representation of DDR-related genes. To further investigate the DDR in this context, we performed a comprehensive, DDR-focused CRISPR-Cas9 loss-of-function screen. This screen identified valosin-containing protein (VCP) as an essential gene in KRAS-mutant PDAC cell lines. We observed that genetic and pharmacologic inhibition of VCP limited cell growth and induced apoptotic death. Addressing the basis for VCP-dependent growth, we first evaluated the contribution of VCP to the DDR and found that loss of VCP resulted in accumulation of DNA double-strand breaks. We next addressed its role in proteostasis and found that loss of VCP caused accumulation of polyubiquitinated proteins. We also found that loss of VCP increased autophagy. Therefore, we reasoned that inhibiting both VCP and autophagy could be an effective combination. Accordingly, we found that VCP inhibition synergized with the autophagy inhibitor chloroquine. We conclude that concurrent targeting of autophagy can enhance the efficacy of VCP inhibitors in KRAS-mutant PDAC.

Increased Expression of SRSF1 Predicts Poor Prognosis in Multiple Myeloma

Background

Multiple myeloma (MM) is a clonal plasma cell disorder which still lacks sufficient prognostic factors. The serine/arginine-rich splicing factor (SRSF) family serves as an important splicing regulator in organ development. Among all members, SRSF1 plays an important role in cell proliferation and renewal. However, the role of SRSF1 in MM is still unknown.

Methods

SRSF1 was selected from the primary bioinformatics analysis of SRSF family members, and then we integrated 11 independent datasets and analyzed the relationship between SRSF1 expression and MM clinical characteristics. Gene set enrichment analysis (GSEA) was conducted to explore the potential mechanism of SRSF1 in MM progression. ImmuCellAI was used to estimate the abundance of immune infiltrating cells between the SRSF1^high and SRSF1^low groups. The ESTIMATE algorithm was used to evaluate the tumor microenvironment in MM. The expression of immune-related genes was compared between the groups. Additionally, SRSF1 expression was validated in clinical samples. SRSF1 knockdown was conducted to explore the role of SRSF1 in MM development.

Results

SRSF1 expression showed an increasing trend with the progression of myeloma. Besides, SRSF1 expression increased as the age, ISS stage, 1q21 amplification level, and relapse times increased. MM patients with higher SRSF1 expression had worse clinical features and poorer outcomes. Univariate and multivariate analysis indicated that upregulated SRSF1 expression was an independent poor prognostic factor for MM. Enrichment pathway analysis confirmed that SRSF1 takes part in the myeloma progression via tumor-associated and immune-related pathways. Several checkpoints and immune-activating genes were significantly downregulated in the SRSF1^high groups. Furthermore, we detected that SRSF1 expression was significantly higher in MM patients than that in control donors. SRSF1 knockdown resulted in proliferation arrest in MM cell lines.

Conclusion

The expression value of SRSF1 is positively associated with myeloma progression, and high SRSF1 expression might be a poor prognostic biomarker in MM patients.

Correlation of changes in subclonal architecture with progression in the MMRF CoMMpass study

Multiple myeloma (MM) is a heterogeneous plasma cell proliferative disorder that arises from its premalignant precursor stages through a complex cascade of interactions between clonal mutations and co-evolving microenvironment. The temporo-spatial evolutionary trajectories of MM are established early during myelomatogenesis in precursor stages and retained in MM. Such molecular events impact subsequent disease progression and clinical outcomes. Identification of clonal sweeps of actionable gene targets in MM could reveal potential vulnerabilities that may exist in early stages and thus potentiate prognostication and customization of early therapeutic interventions. We have evaluated clonal evolution at multiple time points in 76 MM patients enrolled in the MMRF CoMMpass study. The major findings of this study are (a) MM progresses predominantly through branching evolution, (b) there is a heterogeneous spectrum of mutational landscapes that include unique actionable gene targets at diagnosis compared to progression, (c) unique clonal gains/ losses of mutant driver genes can be identified in patients with different cytogenetic aberrations, (d) there is a significant correlation between co-occurring oncogenic mutations/ co-occurring subclones e.g., with mutated TP53+SYNE1, NRAS+MAGI3, and anticorrelative dependencies between FAT3+FCGBP gene pairs. Such co-trajectories may synchronize molecular events of drug response, myelomatogenesis and warrant future studies to explore their potential for early prognostication and development of risk stratified personalized therapies in MM.

Pathogenesis and treatment of multiple myeloma

Multiple myeloma (MM) is the second‐ranking malignancy in hematological tumors. The pathogenesis of MM is complex with high heterogeneity, and the development of the disease is a multistep process. Chromosomal translocations, aneuploidy, genetic mutations, and epigenetic aberrations are essential in disease initiation and progression. The correlation between MM cells and the bone marrow microenvironment is associated with the survival, progression, migration, and drug resistance of MM cells. In recent decades, there has been a significant change in the paradigm for the management of MM. With the development of proteasome inhibitors, immunomodulatory drugs, monoclonal antibodies, chimeric antigen receptor T‐cell therapies, and novel agents, the survival of MM patients has been significantly improved. In addition, nanotechnology acts as both a nanocarrier and a treatment tool for MM. The properties and responsive conditions of nanomedicine can be tailored to reach different goals. Nanomedicine with a precise targeting property has offered great potential for drug delivery and assisted in tumor immunotherapy. In this review, we summarize the pathogenesis and current treatment options of MM, then overview recent advances in nanomedicine‐based systems, aiming to provide more insights into the treatment of MM.

High levels of chromosomal instability facilitate the tumor growth and sphere formation

Most cancer cells show chromosomal instability (CIN), a condition in which chromosome missegregation occurs at high rates. Growing evidence suggests that CIN is not just a consequence of, but a driving force for, oncogenic transformation, although the relationship between CIN and tumorigenesis has not been fully elucidated. Here we found that conventional two‐dimensional (2D) culture of HeLa cells, a cervical cancer‐derived cell line, was a heterogenous population containing cells with different CIN levels. Although cells with high‐CIN levels (high‐CIN cells) grew more slowly compared with cells with low‐CIN levels (low‐CIN cells) in 2D monolayer culture, they formed tumors in nude mice and larger spheres in three‐dimensional (3D) culture, which was more representative of the in vivo environment. The duration of mitosis was longer in high‐CIN cells, reflecting their higher mitotic defects. Single‐cell genome sequencing revealed that high‐CIN cells exhibited a higher karyotype heterogeneity compared with low‐CIN cells. Intriguingly, the karyotype heterogeneity was reduced in the spheres formed by high‐CIN cells, suggesting that cells with growth advantages were selected, although genomic copy number changes specific for spheres were not identified. When we examined gene expression profiles, genes related to the K‐ras signaling were upregulated, while those related to the unfolded protein response were downregulated in high‐CIN cells in 3D culture compared with 2D culture, suggesting the relevance of these genes for their survival. Our data suggested that, although CIN is disadvantageous in monolayer culture, it promotes the selection of cells with growth advantages under in vivo environments, which may lead to tumorigenesis.

The molecular mechanism and challenge of targeting XPO1 in treatment of relapsed and refractory myeloma

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Significant progress has been made on the treatment of MM during past two decades.

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Acquired drug-resistance continues to drive early relapse in primary refractory MM.

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XPO1 over-expression and cargo mislocalization are associated with drug-resistance.

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XPO1 inhibitor selinexor restores drug sensitivity to subsets of RR-MM cells.

Multiple myeloma (MM) treatment regimens have vastly improved since the introduction of immunomodulators, proteasome inhibitors, and anti-CD38 monoclonal antibodies; however, MM is considered an incurable disease due to inevitable relapse and acquired drug resistance. Understanding the molecular mechanism by which drug resistance is acquired will help create novel strategies to prevent relapse and help develop novel therapeutics to treat relapsed/refractory (RR)-MM patients. Currently, only homozygous deletion/mutation of TP53 gene due to “double-hits” on Chromosome 17p region is consistently associated with a poor prognosis. The exciting discovery of XPO1 overexpression and mislocalization of its cargos in the RR-MM cells has led to a novel treatment options. Clinical studies have demonstrated that the XPO1 inhibitor selinexor can restore sensitivity of RR-MM to PIs and dexamethasone. We will elaborate on the problems of MM treatment strategies and discuss the mechanism and challenges of using XPO1 inhibitors in RR-MM therapies while deliberating potential solutions.

Systematic discovery of mutation-directed neo-protein-protein interactions in cancer

Comprehensive sequencing of patient tumors reveals genomic mutations across tumor types that enable tumorigenesis and progression. A subset of oncogenic driver mutations results in neomorphic activity where the mutant protein mediates functions not engaged by the parental molecule. Here, we identify prevalent variant-enabled neomorph-protein-protein interactions (neoPPI) with a quantitative high-throughput differential screening (qHT-dS) platform. The coupling of highly sensitive BRET biosensors with miniaturized coexpression in an ultra-HTS format allows large-scale monitoring of the interactions of wild-type and mutant variant counterparts with a library of cancer-associated proteins in live cells. The screening of 17,792 interactions with 2,172,864 data points revealed a landscape of gain of interactions encompassing both oncogenic and tumor suppressor mutations. For example, the recurrent BRAF V600E lesion mediates KEAP1 neoPPI, rewiring a BRAF^V600E/KEAP1 signaling axis and creating collateral vulnerability to NQO1 substrates, offering a combination therapeutic strategy. Thus, cancer genomic alterations can create neo-interactions, informing variant-directed therapeutic approaches for precision medicine.

SHP2 Inhibitors Show Anti-Myeloma Activity and Synergize With Bortezomib in the Treatment of Multiple Myeloma

Multiple myeloma (MM) is a plasma cell malignancy that remains incurable. The protein tyrosine phosphatase SHP2 is a central node regulating RAS/mitogen-activated protein kinase (MAPK)/extracellular signal regulated kinase (ERK) signaling pathway which plays a crucial role in the pathogenesis and proteasome inhibitor (PI) resistance of MM. Several preclinical studies have demonstrated that SHP2 inhibitors exerted antitumor activity in cancer-harboring diverse mutations in the RAS pathway, offering the potential for targeting myeloma. In this study, we showed that pharmacological inhibition of SHP2 activity using SHP099 and RMC-4550 efficiently inhibited the proliferation of MM cells by inducing apoptosis and cell cycle arrest. As per the mechanism, SHP2 inhibitors activated the level of cleaved caspase3, BAK, and P21 and downregulated ERK phosphorylation in MM cells. Moreover, the blockade of SHP2 exhibited anti-myeloma effect in vivo in a mouse xenograft model. In addition, SHP2 inhibitors synergized the antineoplastic effect of bortezomib in bortezomib-sensitive MM cells and showed identical efficacy in targeting bortezomib-resistant MM cells. Overall, our findings suggest that SHP2-specific inhibitors trigger anti-myeloma activity in vitro and in vivo by regulating the ERK pathway and enhancing cytotoxicity of bortezomib, providing therapeutic benefits for both bortezomib naïve and resistant MM.

The Rationale for the Dual-Targeting Therapy for RSK2 and AKT in Multiple Myeloma

Multiple myeloma (MM) is characterized by remarkable cytogenetic/molecular heterogeneity among patients and intraclonal diversity even in a single patient. We previously demonstrated that PDPK1, the master kinase of series of AGC kinases, is universally active in MM, and plays pivotal roles in cell proliferation and cell survival of myeloma cells regardless of the profiles of cytogenetic and genetic abnormalities. This study investigated the therapeutic efficacy and mechanism of action of dual blockade of two major PDPK1 substrates, RSK2 and AKT, in MM. The combinatory treatment of BI-D1870, an inhibitor for N-terminal kinase domain (NTKD) of RSK2, and ipatasertib, an inhibitor for AKT, showed the additive to synergistic anti-tumor effect on human MM-derived cell lines (HMCLs) with active RSK2-NTKD and AKT, by enhancing apoptotic induction with BIM and BID activation. Moreover, the dual blockade of RSK2 and AKT exerted robust molecular effects on critical gene sets associated with myeloma pathophysiologies, such as those with MYC, mTOR, STK33, ribosomal biogenesis, or cell-extrinsic stimuli of soluble factors, in HMCLs. These results provide the biological and molecular rationales for the dual-targeting strategy for RSK2 and AKT, which may overcome the therapeutic difficulty due to cytogenetic/molecular heterogeneity in MM.

Circular RNA-microRNA-mRNA network identified circ_0007618 and circ_0029426 as new valuable biomarkers for lung adenocarcinoma

Circular RNAs (circRNAs) are involved in multiple physiological processes. However, whether circRNAs function as the indicators of lung adenocarcinoma (LUAD) remains unclear. Three LUAD-related microarray datasets were downloaded from the Gene Expression Omnibus database, and overlapping differentially expressed circRNAs (DECs) in LUAD were identified. circ_0007618 and circ_0029426 were revealed to be significantly dysregulated in LUAD and verified in LUAD tissues and serum obtained in this study. Subsequently, the overall survival curve and receiver operating characteristics curve analyses were performed to evaluate the prognosis, sensitivity, and specificity of circ_0007618 and circ_0029426 for LUAD diagnosis. The results indicate that the combination of circ_0007618 and circ_0029426 is a potential biomarker for LUAD diagnosis and prognosis. TargetScan and miRDB were used to predict interactions between microRNAs (miRNAs) and circRNAs/mRNAs. A circRNA–miRNA–mRNA network was established for LUAD diagnosis. The Kyoto Encyclopedia of Genes and Genomes and protein–protein interaction network identified four hub genes. In conclusion, circ_0007618 and circ_0029426 may be novel biomarkers for LUAD diagnosis and prognosis. For LUAD diagnosis, PIK3CA and NRAS, and KRAS and ETS1, were targeted by circ_0007618 and circ_0029426, respectively.

RAS-mediated tumor stress adaptation and the targeting opportunities it presents

Cellular stress is known to function in synergistic cooperation with oncogenic mutations during tumorigenesis to drive cancer progression. Oncogenic RAS is a strong inducer of a variety of pro-tumorigenic cellular stresses, and also enhances the ability of cells to tolerate these stresses through multiple mechanisms. Many of these oncogenic, RAS-driven, stress-adaptive mechanisms have also been implicated in tolerance and resistance to chemotherapy and to therapies that target the RAS pathway. Understanding how oncogenic RAS shapes cellular stress adaptation and how this functions in drug resistance is of vital importance for identifying new therapeutic targets and therapeutic combinations to treat RAS-driven cancers.

KRAS and RAS-MAPK Pathway Deregulation in Mature B Cell Lymphoproliferative Disorders

KRAS mutations account for the most frequent mutations in human cancers, and are generally correlated with disease aggressiveness, poor prognosis, and poor response to therapies. KRAS is required for adult hematopoiesis and plays a key role in B cell development and mature B cell proliferation and survival, proved to be critical for B cell receptor-induced ERK pathway activation. In mature B cell neoplasms, commonly seen in adults, KRAS and RAS-MAPK pathway aberrations occur in a relevant fraction of patients, reaching high recurrence in some specific subtypes like multiple myeloma and hairy cell leukemia. As inhibitors targeting the RAS-MAPK pathway are being developed and improved, it is of outmost importance to precisely identify all subgroups of patients that could potentially benefit from their use. Herein, we review the role of KRAS and RAS-MAPK signaling in malignant hematopoiesis, focusing on mature B cell lymphoproliferative disorders. We discuss KRAS and RAS-MAPK pathway aberrations describing type, incidence, mutual exclusion with other genetic abnormalities, and association with prognosis. We review the current therapeutic strategies applied in mature B cell neoplasms to counteract RAS-MAPK signaling in pre-clinical and clinical studies, including most promising combination therapies. We finally present an overview of genetically engineered mouse models bearing KRAS and RAS-MAPK pathway aberrations in the hematopoietic compartment, which are valuable tools in the understanding of cancer biology and etiology.

Identification and Validation of an EMT-Related LncRNA Signature for HNSCC to Predict Survival and Immune Landscapes

Long noncoding RNAs (lncRNAs) are increasingly recognized as decisive factors in the progression of head and neck squamous cell carcinoma (HNSCC), and they participate in the epithelial–mesenchymal transformation (EMT) of HNSCC. LncRNAs are closely related to the prognosis of patients with HNSCC; thus, it is essential to identify EMT-related lncRNAs with prognostic value for HNSCC. The coexpression network of EMT-related lncRNAs was constructed using The Cancer Genome Atlas (TCGA). An EMT-related eight-lncRNA-based prognostic signature was constructed using LASSO Cox regression and Cox proportional hazards analyses. Univariate and multivariate analyses and stratified prognosis confirmed that the prognostic signature was an independent predictive factor. Subsequently, we performed immune cell infiltration analysis, gene set enrichment analysis (GSEA), and single-sample GSEA (ssGSEA) pathway enrichment analysis to uncover the potential molecular mechanisms of prognostic differences in the high- and low-risk groups. Next, we discussed the relationship between the prognostic signature and immune checkpoint-related genes, their TIDE scores, and the sensitivity of common chemotherapeutics. Finally, we further verified the expression differences in lncRNAs that were included in our signature via RT–qPCR in eighteen paired tissues. In summary, this prognostic signature provides powerful prognostic biomarkers for HNSCC and could serve as a predictor for the sensitivity of common chemotherapeutics and immunotherapy responses as well as providing a reference for further personalized treatment.

Where We Stand With Precision Therapeutics in Myeloma: Prosperity, Promises, and Pipedreams

Multiple myeloma remains an incurable disease despite numerous novel agents being approved in the last decade. Furthermore, disease behavior and susceptibility to current treatments often vary drastically from patient to patient. To date there are no approved therapies in myeloma that are targeted to specific patient populations based on genomic or immunologic findings. Precision medicine, using biomarkers descriptive of a specific tumor’s biology and predictive of response to appropriate agents, may continue to push the field forward by expanding our treatment arsenal while refining our ability to expose patients to only those treatments likely to be efficacious. Extensive research efforts have been carried out in this endeavor including the use of agents targeting Bcl2 and the RAS/MAPK and PI3K/AKT/mTOR pathways. Thus far, clinical trials have yielded occasional successes intermixed with disappointments, reflecting significant hurdles which still remain including the complex crosstalk between oncogenic pathways and the nonlinear genetic development of myeloma, prone to cultivating sub-clones with distinctive mutations. In this review, we explore the landscape of precision therapeutics in multiple myeloma and underscore the degree to which research efforts have produced tangible clinical results.

Proteasome regulators in pancreatic cancer

Pancreatic adenocarcinoma is one of the most lethal cancers with rising incidence. Despite progress in its treatment, with the introduction of more effective chemotherapy regimens in the last decade, prognosis of metastatic disease remains inferior to other cancers with long term survival being the exception. Molecular characterization of pancreatic cancer has elucidated the landscape of the disease and has revealed common lesions that contribute to pancreatic carcinogenesis. Regulation of proteostasis is critical in cancers due to increased protein turnover required to support the intense metabolism of cancer cells. The proteasome is an integral part of this regulation and is regulated, in its turn, by key transcription factors, which induce transcription of proteasome structural units. These include FOXO family transcription factors, NFE2L2, hHSF1 and hHSF2, and NF-Y. Networks that encompass proteasome regulators and transduction pathways dysregulated in pancreatic cancer such as the KRAS/ BRAF/MAPK and the Transforming growth factor beta/SMAD pathway contribute to pancreatic cancer progression. This review discusses the proteasome and its transcription factors within the pancreatic cancer cellular micro-environment. We also consider the role of stemness in carcinogenesis and the use of proteasome inhibitors as therapeutic agents.

Anti-tumor activity of the pan-RAF inhibitor TAK-580 in combination with KPT-330 (selinexor) in multiple myeloma

RAS/RAF/MEK/ERK pathway inhibitors exhibit significant anti-tumor effects against various tumor types, including multiple myeloma (MM), and they are predicted to play a pivotal role in precision medicine. The XPO1 inhibitor KPT-330 has also exhibited promising efficacy in combination with other novel drugs in treating relapsed/refractory MM (RRMM). In this study, we explored the anti-tumor effects of a combination of the pan-RAF inhibitor TAK-580 and KPT-330. Importantly, TAK-580 enhanced KPT-330-induced cytotoxicity and apoptosis in human myeloma cell lines and primary myeloma cells from RRMM patients. Moreover, TAK-580 and KPT-330 synergistically inhibited nuclear phospho-FOXO3a and enhanced cytoplasmic phospho-FOXO3a in MM cells, leading to cytoplasmic enhanced Bim expression and finally apoptosis. This indicates that TAK-580 enhances KPT-330-induced cytotoxicity and apoptosis primarily via the FOXO3a-Bim axis. In addition, TAK-580 enhanced the cytotoxicity of KPT-330 against MM cells even in the presence of IGF-1. Taken together, our results demonstrate that a combination of pan-RAF inhibitor and XPO1 inhibitor is a potential therapeutic option in treating MM.

Targeting the Interplay between HDACs and DNA Damage Repair for Myeloma Therapy

Multiple myeloma (MM) is a malignancy of terminally differentiated plasma cells, and accounts for 10% of all hematologic malignancies and 1% of all cancers. MM is characterized by genomic instability which results from DNA damage with certain genomic rearrangements being prognostic factors for the disease and patients’ clinical response. Following genotoxic stress, the evolutionary conserved DNA damage response (DDR) is activated and, in turn, coordinates DNA repair with cell-cycle events. However, the process of carcinogenesis cannot be attributed only to the genetic alterations, but also involves epigenetic processes. Regulation of expression and activity of key players in DNA repair and checkpoint proteins are essential and mediated partly by posttranslational modifications (PTM), such as acetylation. Crosstalk between different PTMs is important for regulation of DNA repair pathways. Acetylation, which is mediated by acetyltransferases (HAT) and histone deacetylases (HDAC), not only affects gene expression through its modulation of histone tails but also has recently been implicated in regulating non-histone proteins. Currently, several HDAC inhibitors (HDACi) have been developed both in pre-clinical and clinical studies, with some of them exhibiting significant anti-MM activities. Due to reversibility of epigenetic changes during the evolutionary process of myeloma genesis, the potency of epigenetic therapies seems to be of great importance. The aim of the present paper is the summary of all data on the role of HDACi in DDR, the interference with each DNA repair mechanism and the therapeutic implications of HDACi in MM.

Disease heterogeneity, prognostication and the role of targeted therapy in multiple myeloma

Multiple myeloma (MM) is a clonal plasma cell malignancy with a heterogeneous disease course. Insights into the genetics of the disease have identified certain high-risk cytogenetic features that are associated with adverse outcomes. While the advances in therapy have translated into dramatic improvements in the outcome of patients with MM, those with high-risk genetic features continue to perform poorly. This has resulted in a need for clinical trials focusing on the high-risk subgroup of MM as they search for additional biomarkers and therapeutic targets continue. In this review, we discuss the currently existing data on prognostic and predictive biomarkers in MM and speculate the role of treatment stratification based on the genetic features of the disease.

Targeting Reactive Oxygen Species Metabolism to Induce Myeloma Cell Death

Multiple myeloma (MM) is a common hematological disease characterized by the accumulation of clonal malignant plasma cells in the bone marrow. Over the past two decades, new therapeutic strategies have significantly improved the treatment outcome and patients survival. Nevertheless, most MM patients relapse underlying the need of new therapeutic approaches. Plasma cells are prone to produce large amounts of immunoglobulins causing the production of intracellular ROS. Although adapted to high level of ROS, MM cells die when exposed to drugs increasing ROS production either directly or by inhibiting antioxidant enzymes. In this review, we discuss the efficacy of ROS-generating drugs for inducing MM cell death and counteracting acquired drug resistance specifically toward proteasome inhibitors.

The importance of Ras in drug resistance in cancer

In this review, we analyse the impact of oncogenic Ras mutations in mediating cancer drug resistance and the progress made in the abrogation of this resistance, through pharmacological targeting. At a physiological level, Ras is implicated in many cellular proliferation and survival pathways. However, mutations within this small GTPase can be responsible for the initiation of cancer, therapeutic resistance and failure, and ultimately disease relapse. Often termed "undruggable," Ras is notoriously difficult to target directly, due to its structure and intrinsic activity. Thus, Ras-mediated drug resistance remains a considerable pharmacological problem. However, with advances in both analytical techniques and novel drug classes, the therapeutic landscape against Ras is changing. Allele-specific, direct Ras-targeting agents have reached clinical trials for the first time, indicating there may, at last, be hope of targeting such an elusive but significant protein for better more effective cancer therapy.

Melanoma Cell Resistance to Vemurafenib Modifies Inter-Cellular Communication Signals

The therapeutic success of BRAF inhibitors (BRAFi) and MEK inhibitors (MEKi) in BRAF-mutant melanoma is limited by the emergence of drug resistance, and several lines of evidence suggest that changes in the tumor microenvironment can play a pivotal role in acquired resistance. The present study focused on secretome profiling of melanoma cells sensitive or resistant to the BRAFi vemurafenib. Proteomic and cytokine/chemokine secretion analyses were performed in order to better understand the interplay between vemurafenib-resistant melanoma cells and the tumor microenvironment. We found that vemurafenib-resistant melanoma cells can influence dendritic cell (DC) maturation by modulating their activation and cytokine production. In particular, human DCs exposed to conditioned medium (CM) from vemurafenib-resistant melanoma cells produced higher levels of pro-inflammatory cytokines—that potentially facilitate melanoma growth—than DCs exposed to CM derived from parental drug-sensitive cells. Bioinformatic analysis performed on proteins identified by mass spectrometry in the culture medium from vemurafenib-sensitive and vemurafenib-resistant melanoma cells suggests a possible involvement of the proteasome pathway. Moreover, our data confirm that BRAFi-resistant cells display a more aggressive phenotype compared to parental ones, with a significantly increased production of interferon-γ, interleukin-8, vascular-endothelial growth factor, CD147/basigin, and metalloproteinase 2 (MMP-2). Plasma levels of CD147/basigin and MMP-2 were also measured before the start of therapy and at disease progression in a small group of melanoma patients treated with vemurafenib or vemurafenib plus cobimetinib. A significant increment in CD147/basigin and MMP-2 was observed in all patients at the time of treatment failure, strengthening the hypothesis that CD147/basigin might play a role in BRAFi resistance.

Signaling Pathway Mediating Myeloma Cell Growth and Survival

Simple Summary

The bone marrow (BM) microenvironment plays a crucial role in pathogenesis of multiple myeloma (MM), and delineation of the intracellular signaling pathways activated in the BM microenvironment in MM cells is essential to develop novel therapeutic strategies to improve patient outcome.

Abstract

The multiple myeloma (MM) bone marrow (BM) microenvironment consists of different types of accessory cells. Both soluble factors (i.e., cytokines) secreted from these cells and adhesion of MM cells to these cells play crucial roles in activation of intracellular signaling pathways mediating MM cell growth, survival, migration, and drug resistance. Importantly, there is crosstalk between the signaling pathways, increasing the complexity of signal transduction networks in MM cells in the BM microenvironment, highlighting the requirement for combination treatment strategies to blocking multiple signaling pathways.

Rapid Response in a Patient with Relapsed/Refractory Multiple Myeloma Treated with BRAF/MEK Inhibitors

Patients with relapsed and refractory multiple myeloma have a poor prognosis. The mitogen-activated protein kinase (MAPK) pathway has been implicated in the pathogenesis of multiple myeloma. Several mutations in this pathway can lead to its constitutive activation leading to oncogenesis. One such mutation is BRAFV600E which is a therapeutic target in the treatment of melanoma, lung cancer, colon cancer, thyroid cancer, and hairy cell leukemia. BRAFV600E-directed therapy currently does not have approval in multiple myeloma. It has been proposed that this mutation leads to proteasome inhibitor resistance. About 4-10% of multiple myeloma cases harbor the BRAFV600E mutation. Herein, we report a case of a patient with relapsed and refractory multiple myeloma who had a progression-free survival (PFS) of 8.5 months on BRAF-targeted therapy.

HLA-DPA1 gene is a potential predictor with prognostic values in multiple myeloma

Background

Multiple myeloma (MM) is an incurable hematological tumor, which is closely related to hypoxic bone marrow microenvironment. However, the underlying mechanisms are still far from fully understood. We took integrated bioinformatics analysis with expression profile GSE110113 downloaded from National Center for Biotechnology Information-Gene Expression Omnibus (NCBI-GEO) database, and screened out major histocompatibility complex, class II, DP alpha 1 (HLA-DPA1) as a hub gene related to hypoxia in MM.

Methods

Differentially expressed genes (DEGs) were filtrated with R package “limma”. Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway were performed using “clusterProfiler” package in R. Then, protein-protein interaction (PPI) network was established. Hub genes were screened out according to Maximal Clique Centrality (MCC). PrognoScan evaluated all the significant hub genes for survival analysis. ScanGEO was used for visualization of gene expression in different clinical studies. P and Cox p value < 0.05 was considered to be statistical significance.

Results

HLA-DPA1 was finally picked out as a hub gene in MM related to hypoxia. MM patients with down-regulated expression of HLA-DPA1 has statistically significantly shorter disease specific survival (DSS) (COX p = 0.005411). Based on the clinical data of GSE47552 dataset, HLA-DPA1 expression showed significantly lower in MM patients than that in healthy donors (HDs) (p = 0.017).

Conclusion

We identified HLA-DPA1 as a hub gene in MM related to hypoxia. HLA-DPA1 down-regulated expression was associated with MM patients’ poor outcome. Further functional and mechanistic studies are need to investigate HLA-DPA1 as potential therapeutic target.