Search Results (90)

The MIM1-BH3 mimetic, which inhibits the Mcl-1 antiapoptotic protein, may be an efficacious molecule able to induce apoptosis. Previously, we found that moxifloxacin (MXFL) is able to modulate Mcl-1 protein expression. Therefore, in the current study, we assessed the impact of the MXFL, MIM1, and MXFL/MIM1 mixtures on viability and apoptosis in amelanotic A375 and melanotic G361 melanoma cells. The obtained results showed that MXFL and MIM1 exerted high cytotoxic and proapoptotic potential. In the case of two-component models, we have demonstrated that the use of the MIM1 and MXFL mixtures resulted in a significant intensification of both cytotoxic and proapoptotic activity, shown as a modulatory effect on the early and late phases of apoptosis toward the analyzed melanoma cells when compared with MIM1 or MXFL alone. We report, for the first time, the high proapoptotic activity of MIM1 and MXFL applied in a two-component model toward melanoma cells, pointing to the Mcl-1 protein as an important molecular target. The observed potential synergistic mode of action—expressed as cytotoxic and proapoptotic activity enhancement, detected for MIM1 and MXFL—may represent a new direction for further in vitro and in vivo experiments concerning the role of the Mcl-1 protein in the treatment of melanoma. Moreover, the presented results certainly contribute to expanding the knowledge of the pharmacology of both fluoroquinolones and BH3 mimetics, and also enable a better understanding of melanoma cell biology. Full article

Cellular senescence is a state of the durable cell cycle arrest of dysfunctional cells, which has been associated with the promotion of tumor cell reprogramming into a stem cell state. We previously reported that the mixed lineage kinase (MLK) inhibitor CEP-1347 promotes the differentiation of glioma stem cells (GSCs)—key contributors to glioblastoma recurrence and therapy resistance—into non-stem tumor cells. However, we also noted that CEP-1347–treated GSCs exhibited a morphological change suggestive of senescence. Therefore, we herein investigated whether CEP-1347 induces senescence in GSCs and, consequently, if senescent GSCs may be eliminated using senolytics. Cell death induced by CEP-1347 in combination with senolytic agents or with the knockdown of anti-apoptotic BCL2 family genes, as well as the effects of CEP-1347 on the expression of senescence markers and anti-apoptotic Bcl-2 family proteins, were examined. The results obtained showed that CEP-1347 induced senescence in GSCs accompanied by the increased expression of Bcl-xL. Among the panel of senolytic agents tested, navitoclax, a BH3 mimetic, efficiently induced cell death in GSCs when combined with CEP-1347 at concentrations clinically achievable in the brain. The knockdown of Bcl-xL resulted in more pronounced GSC death in combination with CEP-1347 than that of Bcl-2. These results suggest that combining CEP-1347 with the targeting of Bcl-xL, the expression of which increases with CEP-1347-induced senescence, is a rational approach to ensure the elimination of GSCs, thereby improving the outcomes of glioblastoma treatment. Full article

Oral squamous cell carcinoma (OSCC) is a prevalent and aggressive malignancy with poor prognosis, largely due to its high metastatic potential and resistance to conventional therapies. Recent advances in cancer biology have underscored the significance of regulated cell death pathways, including apoptosis, autophagic cell death (ACD), necroptosis, pyroptosis, and ferroptosis, in modulating tumor progression and therapeutic responses. This review provides the current insights into the molecular mechanisms underlying these cell death pathways and explores their therapeutic relevance in OSCC. Restoration of apoptosis using BH3 mimetics, tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) receptor agonists, and p53 reactivators shows promise for sensitizing OSCC cells to treatment. Autophagy plays context-dependent roles in cancer, acting as a tumor suppressor during early carcinogenesis by maintaining cellular homeostasis, and as a tumor promoter in established tumors by supporting cancer cell survival under stress. Targeting necroptosis and pyroptosis has emerged as a novel strategy for inducing cancer cell death, with compounds such as acetylshikonin and okanin demonstrating antitumor effects. Additionally, the induction of ferroptosis via lipid peroxidation and glutathione peroxidase 4 (GPX4) inhibition offers a promising avenue for overcoming drug resistance, with agents such as quercetin and trifluoperazine exhibiting preclinical success. Integration of these therapeutic approaches may enhance the OSCC treatment efficacy, reduce chemoresistance, and provide novel prognostic biomarkers for clinical management. Future studies should focus on optimizing combinatorial strategies that effectively leverage these pathways to improve OSCC patient outcomes. Full article

Background: The treatment landscape for multiple myeloma (MM) has significantly evolved in recent decades with novel therapies like proteasome inhibitors, immunomodulatory drugs and monoclonal antibodies. However, MM remains incurable, necessitating new pharmacological strategies. Mitotic kinases, such as Aurora proteins, have emerged as potential targets. Selective inhibitors of Aurora A and B,- alisertib (MLN8237) and barasertib (AZD1152), respectively, have shown anti-myeloma activity in preclinical studies, with alisertib demonstrating modest efficacy in early clinical trials. Methods and Results: This study investigated the mechanisms of action of alisertib and barasertib and their combination with antitumor agents in a panel of five MM cells lines. Both drugs induced cell cycle arrest phase and abnormal nuclear morphologies. Alisertib caused prolonged mitotic arrest, whereas barasertib induced transient arrest, both resulting in the activation of mitotic catastrophe. These findings revealed three potential outcomes: cell death, senescence, or polyploidy. High mitochondrial reactive oxygen species (mROS) were identified as possible drivers of cell death. Caspase inhibition reduced caspase-3 activation but did not prevent cell death. Interestingly, alisertib at low doses remained toxic to Bax/Bak^DKO cells, although mitochondrial potential disruption and cytochrome c release were observed. Sequential combinations of high-dose Aurora kinase inhibitors with BH3-mimetics, and in specific cases with panobinostat, showed a synergistic effect. Conversely, the simultaneous combination of alisertib and barasertib showed mostly antagonistic effects. Conclusions: Alisertib and barasertib emerge as potential in vitro candidates against MM, although further studies are needed to validate their efficacy and to find the best combinations with other molecules. Full article

One of the hallmarks of cancer cells is their failure to respond to the cellular mechanism of apoptosis. The B-cell lymphoma 2 (BCL-2) family of proteins regulate apoptosis. Their ability to do so can be measured using several methods that in turn anticipate the fate of the cancer cell in response to apoptosis-inducing treatment. These assays ultimately identify the readiness of the cancer cell to undergo apoptosis, which is referred to as the mitochondrial priming state. These metrics, however, have been challenging to implement in the clinic. Methods: Here, we describe a unique method that relies on a panel of novel conformation-specific antibodies (termed PRIMAB) that can directly measure the mitochondrial priming state. These reagents are highly specific for complexes of their corresponding pro-survival protein interactions with the pro-apoptotic protein BIM. These BIM-containing heterodimeric complexes have long been established as hallmarks of primed cancer cells. Results: Using clinically amenable assay formats, PRIMABs were shown to detect the presence of these anti-apoptotic–pro-apoptotic complexes and their disruption by BH3-mimetic drugs. Moreover, PRIMABs were able to detect a shift in priming status following BH3-mimetic treatment, a factor associated with resistance to these drugs. In a panel of AML patient samples, we report a wide range of priming levels for each PRIMAB complex, demonstrating the potential for heterogeneity in responses. We also show that PRIMABs could be predictive of outcomes for AML patients following cytarabine-based treatment. Conclusions: PRIMABs provide novel and useful tools for cancer research and for clinical implementation as reagents providing predictive tests for treatment response. Full article

Acute myeloid leukemia (AML) has traditionally been linked to a poor prognosis, particularly in older patients who are ineligible for intensive chemotherapy. The advent of Venetoclax, a powerful oral BH3 mimetic targeting anti-apoptotic protein BCL2, has significantly advanced AML treatment. Its combination with the hypomethylating agent azacitidine (AZA/VEN) has become a standard treatment for this group of AML patients, demonstrating a 65% overall response rate and a median overall survival of 14.7 months, compared to 22% and 8 months with azacitidine monotherapy, respectively. However, resistance and relapses remain common, representing a significant clinical challenge. Recent studies have identified molecular alterations, such as mutations in FLT3-ITD, NRAS/KRAS, TP53, and BAX, as major drivers of resistance. Additionally, other factors, including metabolic changes, anti-apoptotic protein expression, and monocytic or erythroid/megakaryocytic differentiation status, contribute to treatment failure. Clinical trials are exploring strategies to overcome venetoclax resistance, including doublet or triplet therapies targeting IDH and FLT3 mutations; novel epigenetic approaches; menin, XPO1, and MDM2 inhibitors; along with immunotherapies like monoclonal antibodies and antibody–drug conjugates. A deeper understanding of the molecular mechanisms of resistance through single-cell analysis will be crucial for developing future therapeutic strategies. Full article

Background: Acute myeloid leukemia (AML) is a common and aggressive form of leukemia, yet current treatment strategies remain insufficient. Venetoclax, a BH3-mimetic approved for AML treatment, induces Bcl-2-dependent apoptosis, though its therapeutic efficacy is still limited. Therefore, new strategies to enhance the effect of venetoclax are highly sought. Valproic acid (VPA), commonly used for epilepsy, has also been studied for potential applications in AML treatment. Methods: AML cells were treated with venetoclax, with or without VPA. Cell viability was assessed using the trypan blue dye exclusion assay, while cell cycle progression was analyzed by flow cytometry. The expression of pro-apoptotic proteins Bax and Bak was measured by RT-qPCR. Results: Venetoclax and VPA individually had only mild effects on AML cell proliferation. However, their combination significantly inhibited cell growth and triggered pronounced cell death. This combination also led to the cleavage of poly (ADP-ribose) polymerase (PARP), a substrate of caspases, indicating activation of apoptosis. VPA treatment upregulated the expression of Bax and Bak, further supporting apoptosis induction. The cell death induced by the venetoclax–VPA combination was predominantly apoptotic, as confirmed by the near-complete blockade of cell death by a pan-caspase inhibitor. Conclusions: Our study demonstrates that VPA enhances venetoclax-induced apoptosis in AML cell lines, providing a novel role for VPA and suggesting a promising combinatory strategy for AML treatment. These findings offer valuable insights into potential clinical applications of venetoclax and VPA in AML management. Full article

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy with poor response to conventional therapy, derived from hematopoietic progenitors committed to T-cell lineage. Relapsed/Refractory patients account for nearly 20% of childhood and 45% of adult cases. Aberrant Notch signaling plays a critical role in T-ALL pathogenesis and therapy resistance. Notch inhibition is a promising therapeutic target for personalized medicine, and a variety of strategies to prevent Notch activation, including γ-secretase (GS) inhibitors (GSIs) and antibodies neutralizing Notch receptors or ligands, have been developed. Disruption of apoptosis is pivotal in cancer development and progression. Different reports evidenced the interplay between Notch and the anti-apoptotic Bcl-2 family proteins in T-ALL. Although based on early research data, this review discusses recent advances in directly targeting Notch receptors and the use of validated BH3 mimetics for the treatment of T-ALL and their combined action in light of current evidence of their use. Full article

B-cell lymphoma 2 protein (Bcl-2) is an important regulator of cell apoptosis. Inhibitors that mirror the structural domain 3 (BH3) of Bcl-2 can activate apoptosis in cancer cells, making them a promising target for anticancer treatment. Hence, the present study aimed to investigate potential BH3-mimetic peptides from two vicilin-derived legume proteins from soybean and cowpea bean. The proteins were isolated and sequentially hydrolyzed with pepsin/pancreatin. Peptides < 3 kDa from vicilin-derived proteins from soybean and cowpea beans experimentally inhibited the growth of cultivated breast and prostate cancer cells. In silico analysis allowed the identification of six potential candidates, all predicted to be able to interact with the BH3 domain. The VIPAAY peptide from the soybean β-conglycinin β subunit showed the highest potential to interact with Bcl-2, comparable to Venetoclax, a well-known anticancer drug. Further experiments are needed to confirm this study’s findings. Full article

Acute leukemia is a group of aggressive hematological malignancies, with acute lymphoblastic leukemia (ALL) and acute myeloid leukemia (AML) being the most common types. The biology of acute leukemia involves complex genetic and epigenetic alterations that lead to uncontrolled cell proliferation and resistance to apoptosis. Mitochondrial dysfunction is a feature of acute leukemia that results in altered energy production, unregulated cell death pathways, and increased cancer cell survival. Apoptosis, particularly via the mitochondrial pathway, is crucial for cellular homeostasis and cancer prevention. In acute leukemia, disruption of apoptosis is pivotal in disease development and progression, with elevated levels of anti-apoptotic proteins conferring a survival advantage to leukemia cells and promoting resistance to conventional therapies. Targeting mitochondrial apoptosis using BH3 mimetics and anti-apoptotic protein inhibitors is a viable therapeutic strategy. Alterations in the mitochondrial membrane potential, metabolism, and dynamics also contribute to the pathogenesis of acute leukemia. Continued research is vital for developing novel therapies and enhancing survival outcomes in patients with acute leukemia while minimizing the long-term adverse effects of treatment. In this narrative review, we provide a birds-eye view of the available scientific literature on the importance of mitochondria in acute leukemia, and discuss the role of BH3 mimetics in targeting the mitochondrial internal apoptotic machinery. Full article

This review article is focused on the progress made in the synthesis of 5′-α-P-modified nucleoside triphosphates (α-phosphate mimetics). A variety of α-P-modified nucleoside triphosphates (NTPαXYs, Y = O, S; X = S, Se, BH₃, alkyl, amine, N-alkyl, imido, or others) have been developed. There is a unique class of nucleoside triphosphate analogs with different properties. The main chemical approaches to the synthesis of NTPαXYs are analyzed and systematized here. Using the data presented here on the diversity of NTPαXYs and their synthesis protocols, it is possible to select an appropriate method for obtaining a desired α-phosphate mimetic. Triphosphates’ substrate properties toward nucleic acid metabolism enzymes are highlighted too. We reviewed some of the most prominent applications of NTPαXYs including the use of modified dNTPs in studies on mechanisms of action of polymerases or in systematic evolution of ligands by exponential enrichment (SELEX). The presence of heteroatoms such as sulfur, selenium, or boron in α-phosphate makes modified triphosphates nuclease resistant. The most distinctive feature of NTPαXYs is that they can be recognized by polymerases. As a result, S-, Se-, or BH₃-modified phosphate residues can be incorporated into DNA or RNA. This property has made NTPαXYs a multifunctional tool in molecular biology. This review will be of interest to synthetic chemists, biochemists, biotechnologists, or biologists engaged in basic or applied research. Full article

Triple-negative breast cancer (TNBC) patients are treated with traditional chemotherapy, such as the taxane class of drugs. One such drug, paclitaxel (PTX), can be effective in treating TNBC; however, many tumors will develop drug resistance, which can lead to recurrence. In order to improve patient outcomes and survival, there lies a critical need to understand the mechanism behind drug resistance. Our lab made the novel observation that decreased expression of the Adenomatous Polyposis Coli (APC) tumor suppressor using shRNA caused PTX resistance in the human TNBC cell line MDA-MB-157. In cells lacking APC, induction of apoptosis by PTX was decreased, which was measured through cleaved caspase 3 and annexin/PI staining. The current study demonstrates that CRISPR-mediated APC knockout in two other TNBC lines, MDA-MB-231 and SUM159, leads to PTX resistance. In addition, the cellular consequences and molecular mechanisms behind APC-mediated PTX response have been investigated through analysis of the BCL-2 family of proteins. We found a significant increase in the tumor-initiating cell population and increased expression of the pro-survival family member Bcl-2, which is widely known for its oncogenic behavior. ABT-199 (Venetoclax), is a BH3 mimetic that specifically targets Bcl-2. ABT-199 has been used as a single or combination therapy in multiple hematologic malignancies and has shown promise in multiple subtypes of breast cancer. To address the hypothesis that APC-induced Bcl-2 increase is responsible for PTX resistance, we combined treatment of PTX and ABT-199. This combination treatment of CRISPR-mediated APC knockout MDA-MB-231 cells resulted in alterations in apoptosis, suggesting that Bcl-2 inhibition restores PTX sensitivity in APC knockout breast cancer cells. Our studies are the first to show that Bcl-2 functional inhibition restores PTX sensitivity in APC mutant breast cancer cells. These studies are critical to advance better treatment regimens in patients with TNBC. Full article

Mcl-1 (myeloid cell leukemia 1), a member of the Bcl-2 family, is upregulated in various types of cancer. Peptides representing the BH3 (Bcl-2 homology 3) region of pro-apoptotic proteins have been demonstrated to bind the hydrophobic groove of anti-apoptotic Mcl-1, and this interaction is responsible for regulating apoptosis. Structural studies have shown that, while there is high overall structural conservation among the anti-apoptotic Bcl-2 (B-cell lymphoma 2) proteins, differences in the surface groove of these proteins facilitates binding specificity. This binding specificity is crucial for the mechanism of action of the Bcl-2 family in regulating apoptosis. Bim-based peptides bind specifically to the hydrophobic groove of Mcl-1, emphasizing the importance of these interactions in the regulation of cell death. Molecular docking was performed with BH3-like peptides derived from Bim to identify high affinity peptides that bind to Mcl-1 and to understand the molecular mechanism of their interactions. The interactions of three identified peptides, E2gY, E2gI, and XXA1_F3dI, were further evaluated using 250 ns molecular dynamics simulations. Conserved hydrophobic residues of the peptides play an important role in their binding and the structural stability of the complexes. Understanding the molecular basis of interaction of these peptides will assist in the development of more effective Mcl-1 specific inhibitors. Full article

Many proteins regulating mitosis have emerged as targets for cancer therapy, including the kinesin spindle protein (KSP) and Aurora kinase B (AurB). KSP is crucial for proper spindle pole separation during mitosis, while AurB plays roles in chromosome segregation and cytokinesis. Agents targeting KSP and AurB selectively affect dividing cells and have shown significant activity in vitro. However, these drugs, despite advancing to clinical trials, often yield unsatisfactory outcomes as monotherapy, likely due to variable responses driven by cyclin B degradation and apoptosis signal accumulation networks. Accumulated data suggest that combining emerging antimitotics with various cytostatic drugs can enhance tumor-killing effects compared to monotherapy. Here, we investigated the impact of inhibiting anti-apoptotic signals with the BH3-mimetic Navitoclax in oral cancer cells treated with the selective KSP inhibitor, Ispinesib, or AurB inhibitor, Barasertib, aiming to potentiate cell death. The combination of BH3-mimetics with both KSP and AurB inhibitors synergistically induced substantial cell death, primarily through apoptosis. A mechanistic analysis underlying this synergistic activity, undertaken by live-cell imaging, is presented. Our data underscore the importance of combining BH3-mimetics with antimitotics in clinical trials to maximize their effectiveness. Full article

Venetoclax is a Bcl-2 homology domain 3 (BH3) mimetic currently approved for the treatment of chronic lymphocytic leukemia (CLL) and acute myeloid leukemia (AML) that has proven to be highly effective in reinstating apoptosis in leukemic cells through the highly selective inhibition of the anti-apoptotic protein B-cell lymphoma-2 (Bcl-2). Clinically, venetoclax has provided lasting remissions through the inhibition of CLL and AML blasts. However, this activity has often come at the cost of grade III/IV neutropenia due to hematopoietic cells’ dependence on Bcl-2 for survival. As life-threatening infections are an important complication in these patients, an effective management of neutropenia is indispensable to maximize patient outcomes. While there is general consensus over dose reduction and scheduling modifications to minimize the risk of neutropenia, the impact of these modifications on survival is uncertain. Moreover, guidelines do not yet adequately account for patient-specific and disease-specific risk factors that may predict toxicity, or the role combination treatment plays in exacerbating neutropenia. The objective of this review is to discuss the venetoclax-induced mechanism of hematological toxicity, the potential predictive risk factors that affect patient vulnerability to neutropenia, and the current consensus on practices for management of neutropenia. Full article