Apoptosis In Multiple Myeloma Cells Research Articles

PDCD4 interacting with PIK3CB and CTSZ promotes the apoptosis of multiple myeloma cells.

The role of programmed cell death 4 (PDCD4) in multiple myeloma (MM) development remains unknown. Here, we investigated its role and action mechanism in MM. Bioinformatic analysis indicated that patients with MM and high PDCD4 expression had higher overall survival than those with low PDCD4 expression. PDCD4 expression promoted MM cell apoptosis and inhibited their viability invitro and tumor growth invivo. RNA-binding protein immunoprecipitation sequencing analysis showed that PDCD4 is bound to the 5' UTR of the apoptosis-related genes PIK3CB, Cathepsin Z (CTSZ), and X-chromosome-linked apoptosis inhibitor (XIAP). PDCD4 knockdown reduced the cell apoptosis rate, which was rescued by adding PIK3CB, CTSZ, or XIAP inhibitors. Dual luciferase reporter assays confirmed the internal ribosome entry site (IRES) activity of the 5' UTRs of PIK3CB and CTSZ. An RNA pull-down assay confirmed binding of the 5' UTR of PIK3CB and CTSZ to PDCD4, identifying the specific binding fragments. PDCD4 is expected to promote MM cell apoptosis by binding to the IRES domain in the 5' UTR of PIK3CB and CTSZ and inhibiting their translation. Our findings suggest that PDCD4 plays an important role in MM development by regulating the expression of PIK3CB, CTSZ, and XIAP, and highlight new potential molecular targets for MM treatment.

Epigallocatechin gallate induces apoptosis in multiple myeloma cells through endoplasmic reticulum stress induction and cytoskeletal disruption

Multiple myeloma (MM) is an incurable plasma cell malignancy that has prompted investigations into new potential therapeutic avenues. Epigallocatechin-3-gallate (EGCG), a major component of green tea, confers antioxidant, anti-inflammatory, and anti-tumor properties. Previous studies have shown that EGCG inhibits proliferation and induces apoptosis of multiple myeloma cells, however its underlying molecular mechanisms are largely unknown. In this study, we accordingly sought to examine the therapeutic effects and underlying mechanisms of EGCG on MM.Initially, using CCK8 (Cell Counting Kit-8) assays and Annexin V-FITC/PI staining, we demonstrated that EGCG dose-dependently reduced cell viability and induced apoptosis in the MM cell lines MM.1S and RPMI 8226. Subsequently, mRNA sequencing of EGCG-treated MM.1S cells revealed a significant upregulation of genes associated with endoplasmic reticulum stress (ERS), including P-eIF2α (phosphorylation-eukaryotic translation initiation factor 2 alpha), ATF4 (activating transcription factor 4), CHOP (C/EBP homologous protein, DDIT3), and PUMA (p53 upregulated modulator of apoptosis, BBC3), which were confirmed at the protein level by western blotting. Furthermore, treatment with the eIF2α inhibitor ISRIB reduced the rates of EGCG-induced apoptosis and promoted increases in the protein expression of all four ER stress-related molecules in MM cells. Additionally, mRNA-seq data revealed a downregulation of α-Tubulin 1b (TUBA1B) expression in EGCG-treated MM cells, which was confirmed by western blotting and immunofluorescence analyses. Moreover, we utilized a mouse model to show that EGCG inhibited myeloma tumor growth, which was inhibited by ISRIB.In summary, the findings of this novel study indicated that EGCG promotes apoptosis of MM cells, both via activation of the ER stress pathway and disruption of cytoskeletal integrity. These findings highlight the multi-faceted anti-tumor effects of EGCG and its potential clinical application in MM treatment.

Identification of USP2 as a novel target to induce degradation of KRAS in myeloma cells

Inducing the degradation of KRAS represents a novel strategy to combat cancers with KRAS mutation. In this study, we identify ubiquitin-specific protease 2 (USP2) as a novel deubiquitinating enzyme of KRAS in multiple myeloma (MM). Specifically, we demonstrate that gambogic acid (GA) forms a covalent bond with the Cysteine 284 residue of USP2 through an allosteric pocket, inhibiting its deubiquitinating activity. Inactivation or knockdown of USP2 leads to the degradation of KRAS, resulting in the suppression of MM cell proliferation in vitro and in vivo. Conversely, overexpressing USP2 stabilizes KRAS and partially abrogates GA-induced apoptosis in MM cells. Furthermore, elevated USP2 levels may be associated with poorer prognoses in MM patients. These findings highlight the potential of the USP2/KRAS axis as a therapeutic target in MM, suggesting that strategically inducing KRAS degradation via USP2 inhibition could be a promising approach for treating cancers with KRAS mutations.

Clotrimazole inhibits growth of multiple myeloma cells in vitro via G0/G1 arrest and mitochondrial apoptosis

Patients with multiple myeloma (MM) experience relapse and drug resistance; therefore, novel treatments are essential. Clotrimazole (CTZ) is a wide-spectrum antifungal drug with antitumor activity. However, CTZ’s effects on MM are unclear. We investigated CTZ’s effect on MM cell proliferation and apoptosis induction mechanisms. CTZ’s effects on MM.1S, NCI- H929, KMS-11, and U266 cell growth were investigated using Cell Counting Kit-8 (CCK-8) assay. The apoptotic cell percentage was quantified with annexin V-fluorescein isothiocyanate/7-amino actinomycin D staining. Mitochondrial membrane potential (MMP) and cell cycle progression were evaluated. Reactive oxygen species (ROS) levels were measured via fluorescence microscopy. Expression of apoptosis-related and nuclear factor (NF)-κB signaling proteins was analyzed using western blotting. The CCK-8 assay indicated that CTZ inhibited cell proliferation based on both dose and exposure time. Flow cytometry revealed that CTZ decreased apoptosis and MMP and induced G0/G1 arrest. Immunofluorescence demonstrated that CTZ dose-dependently elevated in both total and mitochondrial ROS production. Western blotting showed that CTZ enhanced Bax and cleaved poly ADP-ribose polymerase and caspase-3 while decreasing Bcl-2, p-p65, and p-IκBα. Therefore, CTZ inhibits MM cell proliferation by promoting ROS-mediated mitochondrial apoptosis, inducing G0/G1 arrest, inhibiting the NF-κB pathway, and has the potential for treating MM.

AP-1 inhibitor induces ferroptosis via the PI3K/AKT pathway in multiple myeloma cells

Multiple myeloma (MM) is an incurable malignancy of plasma cells that is sensitive to T-5224, an AP-1 inhibitor. Previous study indicated that T-5224 inhibits proliferation and induces apoptosis in MM cells. However, the high mortality cannot be fully explained. To date, no studies have investigated ferroptosis induced by T-5224 in MM. Therefore, we further investigated the mechanism by which T-5224 kills MM cells. We observed that T-5224 exhibits antimyeloma properties both in vitro and in vivo. T-5224-induced MM cell death was reversed by the ferroptosis-specific inhibitor ferropstatin-1 (Fer-1). The protein levels of the key ferroptosis regulators GPX4 and SLC7A11 were decreased by T-5224 in MM cells. Furthermore, T-5224 reduced the phosphorylation of PI3K and AKT signaling pathway components, ultimately causing MM cell death. Using 740 Y–P, a PI3K activator, and Fer-1, a ferroptosis inhibitor, we discovered that T-5224 induces ferroptosis through the PI3K/AKT pathway. Bortezomib (BTZ), an FDA-approved drug for MM treatment, can be administered in combination with other agents. We evaluated the synergistic effect of BTZ combined with AP-1 inhibitors on MM in vivo. Our findings provide a better theoretical basis for the potential mechanism of T-5224 and a new perspective on MM treatment.

Ultradiluted Homeopathic Medicines Cause Apoptosis in RPMI-8226 Multiple Myeloma Cells in vitro: a Pilot Study.

Multiple myeloma (MM) is the second most common type of cancer among hematological malignancies and is difficult to treat. Although controversial in nature, homeopathy's effects have been tested on a wide range of cancer cell types in vitro, as well as clinically. However, homeopathic medicines have yet to be tested in MM cells. In this preliminary study, we investigated the effects of Arsenicum album, Hecla lava, Carcinosinum and Carboneum sulphuratum 200C on a human MM cell line. The RPMI-8226 MM cell line was cultured in vitro for up to 96 hours and treated with each of four homeopathic preparations. The spectrophotometric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, flow cytometric Annexin V-PE/7-actinomycin D (7-AAD) and propidium iodide (PI) staining were each used to examine cell viability, apoptosis and cell cycle, respectively. The MTT assay showed that all four homeopathic preparations reduced cell viability over time when compared to the control group cells, especially at 72 and 96 hours whereby only 50% of cells remained viable. Similarly, after 96 hours of treatment, the proportion of viable cells was significantly decreased and the proportion of early apoptotic (Annexin-V-PE +/7AAD-) cells was significantly increased for all four homeopathic preparations. Based on the PI-staining cell cycle data, cells treated with Hecla lava and Carboneum sulphuratum showed a statistically significant accumulation in the sub-G0/G1 phase of the cell cycle (p < 0.05). This is the first study to demonstrate that each of four homeopathic medicines causes apoptosis in a MM cell line. Further exploration of the potential of Arsenicum album, Hecla lava, Carcinosinum and Carboneum sulphuratum as a complementary therapeutic option in MM is warranted.

Interleukin-33 increases the sensitivity of multiple myeloma cells to the proteasome inhibitor bortezomib through reactive oxygen species-mediated inhibition of nuclear factor kappa-B signal and stemness properties.

The proteasome inhibitor bortezomib (BTZ) is the first-line therapy for multiple myeloma (MM). BTZ resistance largely limits its clinical application in MM. Interleukin-33 (IL-33) exerts antitumor effects through various mechanisms, including enhancing antitumor immunity and promoting the apoptosis of cancer cells. Here, the synergistic anti-MM effect of IL-33 and BTZ was verified, and the underlying mechanisms were elucidated. Bioinformatic analysis indicated that IL-33 expression levels were downregulated in MM, and that BTZ-treated MM patients with high IL-33 levels had better prognosis than those with low IL-33 levels. Moreover, the patients with high IL-33 levels had a better treatment response to BTZ. Further immune analysis suggested that IL-33 can enhance the anti-MM immunity. IL-33 and BTZ synergistically inhibited proliferation and induced apoptosis of MM cells, which was mediated by the excessive accumulation of cellular reactive oxygen species (ROS). Furthermore, increased ROS hindered the nuclear translocation of NF-κB-p65, thereby decreasing the transcription of target stemness-related genes (SOX2, MYC, and OCT3/4). These effects induced by the combination therapy could be reversed by eliminating ROS by N-acetylcysteine. In conclusion, our results indicated that IL-33 enhanced the sensitivity of MM to BTZ through ROS-mediated inhibition of nuclear factor kappa-B (NF-κB) signal and stemness properties.

Phenylalanine deprivation inhibits multiple myeloma progression by perturbing endoplasmic reticulum homeostasis

Amino acid metabolic remodeling is a hallmark of cancer, driving an increased nutritional demand for amino acids. Amino acids are pivotal for energetic regulation, biosynthetic support, and homeostatic maintenance to stimulate cancer progression. However, the role of phenylalanine in multiple myeloma (MM) remains unknown. Here, we demonstrate that phenylalanine levels in MM patients are decreased in plasma but elevated in bone marrow (BM) cells. After the treatment, phenylalanine levels increase in plasma and decrease in BM. This suggests that changes in phenylalanine have diagnostic value and that phenylalanine in the BM microenvironment is an essential source of nutrients for MM progression. The requirement for phenylalanine by MM cells exhibits a similar pattern. Inhibiting phenylalanine utilization suppresses MM cell growth and provides a synergistic effect with Bortezomib (BTZ) treatment in vitro and murine models. Mechanistically, phenylalanine deprivation induces excessive endoplasmic reticulum stress and leads to MM cell apoptosis through the ATF3–CHOP–DR5 pathway. Interference with ATF3 significantly affects phenylalanine deprivation therapy. In conclusion, we have identified phenylalanine metabolism as a characteristic feature of MM metabolic remodeling. Phenylalanine is necessary for MM proliferation, and its aberrant demand highlights the importance of low-phenylalanine diets as an adjuvant treatment for MM.

Design, synthesis, and activity evaluation of 2-iminobenzimidazoles as c-Myc inhibitors for treating multiple myeloma

Multiple myeloma (MM) is a plasma cell malignancy that remains incurable and poses a significant threat to global public health. The multifunctional transcription factor c-Myc plays a crucial role in various cellular processes and is closely associated with MM progression. As part of the basic-helix-loop-helix-leucine zipper (bHLHZip) family, c-Myc forms heterodimers with its obligate partner Max, binds to the Enhancer-box (E-box) of DNA, and ultimately co-regulates gene expression. Therefore, impeding the capacity for heterodimerization to bind to DNA represents a favored strategy in thwarting c-Myc transcription. In this study, we first synthesized a series of novel 2-iminobenzimidazole derivatives and further estimated their potential anti-MM activity. Notably, among all the derivatives, 5b and 5d demonstrated remarkable inhibitory activity against RPMI-8226 and U266 cells, with IC50 values of 0.85 μM and 0.97 μM for compound 5b, and 0.96 μM and 0.89 μM for compound 5d. Western blot and dual-luciferase reporter assays demonstrated that compounds 5b and 5d effectively suppressed both c-Myc protein expression and transcriptional activity of the c-Myc promoter in RPMI-8226 and U266 cells. Furthermore, these compounds induced apoptosis and G1 cell cycle arrest in the aforementioned MM cells. Molecular docking studies revealed that 5b and 5d exhibited strong binding affinity to the interface between c-Myc/Max and E-box of DNA. Taken together, our findings suggest that further investigations are warranted for potential therapeutic applications of 5b and 5d for c-Myc-related diseases.

Abstract 5772: Structural insights and rational design, optimization of highly potent and selective novel GRK5/6 inhibitors for cancer therapy

Abstract G protein-coupled receptor kinases (GRKs) regulate cell signaling by triggering receptor desensitization via phosphorylation on G protein-coupled receptors (GPCRs). There are seven human GRKs (GRK1−GRK7) where GRK5 and GRK6 are structurally similar. GRK5 is ubiquitous and required for cancer progression in various cancer types. Knock-down of GRK5 has been shown to suppress prostate cancer and non-small-cell lung cancer growth. GRK6 is highly abundant in immune cells and is overexpressed in multiple myeloma (MM). Knocking down GRK6 has been shown to cause apoptosis of MM cells. Therefore, targeting GRK5 or 6 is a potential chemotherapeutic strategy. Currently, we are developing a series of inhibitors for GRK5/6 based on a lead compound derived from sunitinib and utilizing Cys474 residue unique in GRK5/6 to enhance selectivity by covalent capture. We tested a series of novel inhibitor warheads to improve potency and selectivity without potentially toxic functional groups. So far, we have identified several inhibitors with low nanomolar IC50 for GRK5 and more than 100,000-fold selectivity over GRK2, another closely related member expressed in the heart. I have developed a pipeline of X-ray crystallography of GRK5 available for soaking various ligands and have solved several structures of novel inhibitor-bound GRK5. The structure elucidated the binding mode of this new class of GRK5 inhibitors, where the core interacts with the adenine site, a fluorophenyl group stabilizes the P loop and density suggests in some cases covalent bond forming between the reversible covalent warhead and Cys474. Our ongoing studies focus on further compound optimizations based on SAR. Overall, the discovery of the inhibitors can significantly facilitate understanding and treatment and cancers. Citation Format: Yueyi Chen, Amol D. Sonawane, Rajesh Manda, Ranjith K. Gadi, Arun K. Ghosh, John J. Tesmer. Structural insights and rational design, optimization of highly potent and selective novel GRK5/6 inhibitors for cancer therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5772.

Abstract 4670: KS18, an Mcl-1 inhibitor, triggers cell death and enhances the therapeutic efficacy of venetoclax in bortezomib-resistant multiple myeloma cells

Abstract A critical clinical challenge in the management of multiple myeloma (MM) is the development of both innate and acquired resistance to the treatment with bortezomib. Our prior research showed that the overexpression of the anti-apoptotic Bcl-2 family protein Mcl-1 can result in resistance to the chemotherapy drugs bortezomib and venetoclax. In order to overcome the issues posed by resistance, this study investigates the possibility of a small chemical called KS18, a novel Mcl-1 inhibitor. KS18 outperforms other Mcl-1 inhibitors such as S63845, VU661013, and AZD5991, according to the findings of our research, which shows that it is extraordinarily effective against MM cells that have become resistant to bortezomib. We establish the selectivity of KS18 through tests employing Mcl-1 knock-down (KD), and we find that it is both effective and efficient. In addition, we used immunoprecipitation (IP) and protein-protein interaction analysis (PPIs) to investigate the dynamic connections that exist between Mcl-1 and pro-apoptotic proteins. The KS18 therapy exhibits an outstanding ability to cause complete apoptosis, as seen by the remarkable 88.8% apoptosis rate recorded in MM patient samples. Not only does KS18 restore apoptosis in bortezomib-resistant MM cells, but it also synergizes with venetoclax to enhance the apoptotic response. This is an important finding. It has been demonstrated through both in vitro and in vivo research that KS18 can re-sensitize MM cells to the effects of bortezomib, which represents a potential step forward in the treatment of the disease. In bortezomib-resistant MM cells, treatment with KS18 led to a remarkable 92% reduction in colony formation compared to untreated controls. In vivo experiments that were performed on mice models that were resistant to bortezomib provide additional evidence that KS18 is effective. The extraordinary reduction in tumor weight of 55% that occurred as a direct result of treatment with KS18 at a dose of 1 mg/kg for a period of 15 days exemplifies the powerful anti-resistance characteristics of this compound. These intriguing findings highlight the potential value of KS18 as an adjunct to therapies aimed at overcoming bortezomib resistance in MM and other associated cancers. Bortezomib-resistant malignancies provide a challenge for patients, but additional research into the clinical value of KS18 holds the potential to improve treatment outcomes and broaden the range of therapeutic alternatives available to these patients. Citation Format: Omar S. Al Odat, Osama Aloudat, Emily Nelson, Tulin Budak-Alpogan, Subash Jonnalagadda, Yong Chen, Manoj Pandey. KS18, an Mcl-1 inhibitor, triggers cell death and enhances the therapeutic efficacy of venetoclax in bortezomib-resistant multiple myeloma cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4670.

Daptomycin Inhibits Multiple Myeloma Progression through Downregulating the Expression of RPS19.

This study aimed to explore new therapeutic drugs for multiple myeloma (MM). MM is a common plasma cell malignant proliferative disease, accounting for 15% of hematological malignancies. The role of daptomycin (DAP), a potential anti-tumor drug, remains unclear in MM. In the present research, we investigated the anticancer effect of DAP in MM cell line RPMI 8226. RPMI 8226 cells were treated with DAP (20 μM, 40 μM, and 80 μM) with 20 nM bortezomib (BZ) as a positive control. Cell function was detected using CCK8, flow cytometry, and transwell assay. In MM cells, DAP inhibited proliferation and induced apoptosis. The cell cycle was arrested at the G1 phase after the treatment of DAP. The migration and invasion abilities were also inhibited by DAP treatment in RPMI 8226 cells. Importantly, the mRNA and protein levels of RPS19 were downregulated in DAP-treated RPMI 8226 cells. DAP inhibited the proliferation, migration, and invasion and promoted the apoptosis of MM cells. Mechanistically, the RPS19 expression was significantly decreased in DAPtreated cells. This research provides a potential therapeutic drug for MM therapy.

ST2825, independent of MyD88, induces reactive oxygen species-dependent apoptosis in multiple myeloma cells

Myeloid differentiation factor 88 (MyD88), which is a key regulator of nuclear factor kappa B (NF-κB), plays an important role in tumorigenesis in lymphoid malignancies such as Waldenstrom's macroglobulinemia (WM). However, its biological function in multiple myeloma (MM), which is a malignant plasma cell disorder like WM, remains unexplored. In this article, we first demonstrated that higher expression MyD88 was significantly correlated with poor survival in patients with MM using multiple publicly available datasets. Interestingly, bioinformatic analysis also revealed that MyD88 gene alteration, which is recognized in nearly 80% of patients with WM, was extremely rare in MM. In addition, ST2825 (a specific inhibitor of MyD88) suppressed cell growth followed by apoptosis. Furthermore, ST2825 induced intracellular reactive oxygen species (ROS) in MM cells, and N-acetyl-l-cysteine, which is known as a ROS scavenger, significantly decreased the number of apoptotic MM cells evoked by ST2825 treatment. Taken together, our results indicated that ST2825 leads to ROS-dependent apoptosis in MM cells and could be an attractive therapeutic candidate for patients with MM. By highlighting the pathological mechanism of MyD88 in MM, this study also provides novel treatment strategies to conquer MM.

Deguelin inhibits the proliferation of human multiple myeloma cells by inducing apoptosis and G2/M cell cycle arrest: Involvement of Akt and p38 MAPK signalling pathway.

Deguelin exhibits antiproliferative activity against various cancer cell types. Previous studies have reported that deguelin exhibits pro-apoptotic activity against human cancer cells. The current study aimed at further elaborating the anticancer effects of deguelin against multiple myeloma cells. Cell growth estimations were made through MTT assay. Phase contrast microscopy was used for the analysis of the viability of multiple myeloma cells. Colony formation from multiple myeloma cells was studied using a clonogenic assay. Antioxidative assays for determining levels of glutathione (GSH) and superoxide dismutase (SOD) were carried out after treating multiple myeloma cells with deguelin. The apoptosis of multiple myeloma cells was studied using AO/EB and Annexin V-FITC/PI staining methods. Multiple myeloma cell cycle analysis was performed through flow cytometry. mRNA expression levels were depicted using qRT-PCR. Migration and invasion of multiple myeloma cells were determined with the wound-healing and transwell assays, respectively. Deguelin specifically inhibited the multiple myeloma cell growth while the normal plasma cells were minimally affected. Multiple myeloma cells when treated with deguelin exhibited remarkably lower viability and colony-forming ability. Multiple myeloma cells treated with deguelin produced more SOD and had higher GSH levels. The multiple myeloma cell growth, migration, and invasion were significantly declined by in vitro administration of deguelin. In conclusion, deguelin treatment, when applied in vitro, induced apoptotic cell death and resulted in mitotic cessation at the G2/M phase through modulation of cell cycle regulatory mRNAs in multiple myeloma cells.

NT157 exhibits antineoplastic effects by targeting IRS and STAT3/5 signaling in multiple myeloma

Multiple myeloma (MM) is a prevalent hematological malignancy with high recurrence and no definitive cure. The current study revisits the role of the IGF1/IGF1R axis in MM, introducing a novel inhibitor, NT157. The IGF1/IGF1R pathway is pivotal in MM, influencing cell survival, proliferation, and migration and impacting patient survival outcomes. NT157 targets intracellular proteins such as IRS and STAT proteins and demonstrates antineoplastic potential in hematological malignancies and solid tumors. In the present study, we assessed IGF1R signaling-related gene expression in MM patients and healthy donors, unveiling significant distinctions. MM cell lines displayed varying expression patterns of IGF1R-related proteins. A gene dependence analysis indicated the importance of targeting receptor and intracellular elements over autocrine IGF1. NT157 exhibited inhibitory effects on MM cell viability, clonal growth, cell cycle progression, and survival. Moreover, NT157 reduced IRS2 expression and STAT3, STAT5, and RPS6 activation and modulated oncogenes and tumor suppressors, fostering a tumor-suppressive molecular profile. In summary, our study demonstrates that the IGF1/IGF1R/IRS signaling axis is differentially activated in MM cells and the NT157’s capacity to modulate crucial molecular targets, promoting antiproliferative effects and apoptosis in MM cells. NT157 may offer a multifaceted approach to enhance MM therapy.

Novel Midkine Inhibitor Induces Cell Cycle Arrest and Apoptosis in Multiple Myeloma.

Multiple myeloma (MM), the second most common hematological malignancy, is characterized by the accumulation of malignant plasma cells within the bone marrow. Despite various drug classes for MM treatment, it remains incurable, necessitating novel and efficacious agents. This study aims to explore the anti-cancer activity of a midkine inhibitor, iMDK (C21H13FN2O2S), in myeloma cell lines. This study assessed the antiproliferative activity using the MTT assay. Cell cycle and apoptosis were evaluated using flow cytometry. To further investigate the inhibitory mechanism, western blotting was used to detect cell cycle-related proteins, pro-apoptotic proteins, and anti-apoptotic proteins. iMDK inhibits MM cell proliferation in a dose- and time-dependent manner, inducing cell cycle arrest and apoptosis. The reduction in Cdc20 expression by iMDK treatment leads to G2/M phase cell cycle arrest. Furthermore, iMDK down-regulates anti-apoptotic proteins (Bcl-2, Bcl-xL, Mcl-1, and c-FLIP), thereby activating both intrinsic and extrinsic apoptosis pathways. iMDK could be a potential candidate for MM treatment.

Targeting of mitochondrial fission through natural flavanones elicits anti-myeloma activity.

Mitochondrial alterations, often dependent on unbalanced mitochondrial dynamics, feature in the pathobiology of human cancers, including multiple myeloma (MM). Flavanones are natural flavonoids endowed with mitochondrial targeting activities. Herein, we investigated the capability of Hesperetin (Hes) and Naringenin (Nar), two aglycones of Hesperidin and Naringin flavanone glycosides, to selectively target Drp1, a pivotal regulator of mitochondrial dynamics, prompting anti-MM activity. Molecular docking analyses were performed on the crystallographic structure of Dynamin-1-like protein (Drp1), using Hes and Nar molecular structures. Cell viability and apoptosis were assessed in MM cell lines, or in co-culture systems with primary bone marrow stromal cells, using Cell Titer Glo and Annexin V-7AAD staining, respectively; clonogenicity was determined using methylcellulose colony assays. Transcriptomic analyses were carried out using the Ion AmpliSeq™ platform; mRNA and protein expression levels were determined by quantitative RT-PCR and western blotting, respectively. Mitochondrial architecture was assessed by transmission electron microscopy. Real time measurement of oxygen consumption was performed by high resolution respirometry in living cells. In vivo anti-tumor activity was evaluated in NOD-SCID mice subcutaneously engrafted with MM cells. Hes and Nar were found to accommodate within the GTPase binding site of Drp1, and to inhibit Drp1 expression and activity, leading to hyperfused mitochondria with reduced OXPHOS. In vitro, Hes and Nar reduced MM clonogenicity and viability, even in the presence of patient-derived bone marrow stromal cells, triggering ER stress and apoptosis. Interestingly, Hes and Nar rewired MM cell metabolism through the down-regulation of master transcriptional activators (SREBF-1, c-MYC) of lipogenesis genes. An extract of Tacle, a Citrus variety rich in Hesperidin and Naringin, was capable to recapitulate the phenotypic and molecular perturbations of each flavanone, triggering anti-MM activity in vivo. Hes and Nar inhibit proliferation, rewire the metabolism and induce apoptosis of MM cells via antagonism of the mitochondrial fission driver Drp1. These results provide a framework for the development of natural anti-MM therapeutics targeting aberrant mitochondrial dependencies.

Research Progress on the Mechanism of PI3K/AKT/mTOR Signaling Pathway in Multiple Myeloma --Review

PI3K/AKT/mTOR signaling pathway is of great significance in the development and prognosis of tumors, and is closely related to the pathogenesis of multiple myeloma (MM). PI3K/AKT/mTOR signaling pathway can participate in the regulation of MM through multichannel and multitarget, such as regulating the tumor microenvironment of MM cells survival, affecting tumor development and migration, regulating the proliferation, apoptosis and autophagy of MM cells. It have shown that after the PI3K/AKT/mTOR signaling pathway is inhibited, the apoptosis and autophagy of MM cells are activated, which promote the death of MM cells and inhibit the metastasis and recurrence of MM cells. Therefore, indepth study of the mechanism of PI3K/AKT/mTOR signaling pathway in MM is helpful to elucidate the pathogenesis and prognosis of MM.

A novel pterostilbene compound DCZ0825 induces macrophage M1 differentiation and Th1 polarization to exert anti-myeloma and immunomodulatory.

Multiple myeloma (MM) is an incurable and recurrent malignancy characterized by abnormal plasma cell proliferation. There is an urgent need to develop effective drugs in MM. DCZ0825 is a small molecule compound derived from pterostilbene with direct anti-myeloma activity and indirect immune-killing effects though reversal of the immunosuppression. DCZ0825 inhibits the activity and proliferation of MM cells causing no significant toxicity to normal cells. Using flow cytometry, this study found that DCZ0825 induced caspase-dependent apoptosis in MM cells and arrested the cell cycle in the G2/M phase by down-regulating CyclinB1, CDK1 and CDC25. Moreover, DCZ0825 up-regulated IRF3 and IRF7 to increase IFN-γ, promoting M2 macrophages to transform into M1 macrophages, releasing the immunosuppression of CD4T cells and stimulated M1 macrophages and Th1 cells to secrete more INF-γ to form immune killing effect on MM cells. Treatment with DCZ0825 resulted in an increased proportion of positive regulatory cells such as CD4T, memory T cells, CD8T, and NK cells, with downregulation of the proportion of negative regulatory cells such as Treg cells and MDSCs. In conclusion, DCZ0825 is a novel compound with both antitumor and immunomodulatory activity.

Multidimensional role of adapalene in regulating cell death in multiple myeloma.

Multiple myeloma (MM) remains a challenging condition to cure, with persistent drug resistance negating the benefits of treatment advancements. The unraveling complexities in programmed cell death (PCD), inclusive of apoptosis, autophagy, and ferroptosis, have highlighted novel therapeutic avenues. Our study focuses on deciphering how adapalene (ADA), a small molecule compound, accelerates the demise of MM cells via targeting their compensatory survival mechanisms. To assess the impact of ADA on MM, we employed flow cytometry and trypan blue exclusion assays to determine cell viabilities across MM cell lines and primary patient samples post-treatment. To delineate ADA's therapeutic targets and mechanisms, we conducted RNA sequencing (RNA-seq), gene set enrichment analysis (GSEA), molecular docking, and molecular dynamics simulations. We further designed pre-clinical trials emphasizing MM, exploring the efficacy of ADA as a standalone and in combination with bortezomib (BTZ). ADA elicited a dose-responsive induction of MM cell death. Building upon ADA's anti-MM capabilities as a single agent, we proposed that ADA-BTZ co-treatment might amplify this lethality. Indeed, ADA and BTZ together greatly potentiated MM cell death. ADA proved beneficial in restoring BTZ susceptibility in BTZ-resistant relapsed or refractory MM (RRMM) patient cells. Molecular simulations highlighted ADA's high affinity (-9.17kcal/mol) for CD138, with MM-GBSA revealing a binding free energy of -27.39kcal/mol. Detailed interaction analyses indicated hydrogen-bonding of ADA with CD138 at the Asp35 and Gln34 residues. Additionally, ADA emerged as a versatile instigator of both ferroptosis and apoptosis in MM cells. Furthermore, ADA disrupted activation of the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway triggered by BTZ, fostering cell death in BTZ-resistant MM subsets. ADA demonstrates a comprehensive capability to orchestrate MM cell death, exerting pronounced anti-MM activity while disrupting NF-κB-related drug resistance. ADA sensitization of MM cells to BTZ unravels its potential as a novel therapeutic drug for MM management.