Pioneering the Battle Against Breast Cancer: The Promise of New Bcl-2 Family.

Currently, breast cancer is the most common cancer type, accounting for 1 in every 4 cancer cases. Leading both in mortality and incidence, breast cancer causes 1 in 4 cancer deaths. To decrease the burden of breast cancer, novel therapeutic agents which target the key hallmarks of cancer, are being explored. The Bcl-2 family of proteins has a crucial role in governing cell death, making them an attractive target for cancer therapy. As cancer chemotherapies lead to oncogenic stress, cancer cells upregulate the Bcl-2 family to overcome apoptosis, leading to failure of treatment. To fix this issue, Bcl-2 family inhibitors, which can cause cell death, have been introduced as novel therapeutic agents. Members of this group have shown promising results in in-vitro studies, and some are currently in clinical trials. In this review, we will investigate Bcl-2 family inhibitors, which are already in trials as monotherapy or combination therapy for breast cancer, and we will also highlight the result of in vitro studies of novel Bcl-2 family inhibitors on breast cancer cells. The findings of these studies have yielded encouraging outcomes regarding the identification of novel Bcl-2 family inhibitors. These compounds hold significant potential as efficacious agents for employment in both monotherapy and combination therapy settings.

MEF2A is a transcription factor for circPVT1 and contributes to the malignancy of acute myeloid leukemia.

Acute myeloid leukemia (AML) is a hematological malignancy with a high relapse rate and a poor survival rate. The circular RNA circPVT1 and myocyte enhancer factor 2A (MEF2A) have unique functions in the progression of AML; however, the underlying mechanisms and clinical significance remain to be clarified. Bioinformatics and database analyses were used to assess the transcription factors and target genes of circPVT1. Dual­luciferase reporter gene and argonaute 2­RNA immunoprecipitation assays were used to verify the targeted relationships. The expression levels of related genes and proteins were detected by reverse transcription­quantitative PCR and western blotting. Cell viability and apoptosis were detected by Cell Counting Kit­8 assay and flow cytometry, respectively. The results revealed that circPVT1 was highly expressed in AML samples and cell lines, and that MEF2A regulated the expression of circPVT1. MEF2A overexpression promoted cell viability and epithelial­mesenchymal transition (EMT), and inhibited cell apoptosis. In addition, circPVT1 was revealed to target the regulation of microRNA (miR)­455­3p, and miR­455­3p targeted the regulation of MCL1 expression, thus indicating that circPVT1 promoted MCL1 expression through its interaction with miR­455­3p. Furthermore, cells were transfected with the small interfering RNA­(si)­circPVT1, miR­455­3p inhibitor or si­MCL1, and si­circPVT1 and si­MCL1 inhibited the viability and EMT of NB4 and HL­60 cells. However, the miR­455­3p inhibitor had the opposite effect on cells. In conclusion, MEF2A may act as a transcription factor of circPVT1 to promote the malignant process of AML, and knockdown of circPVT1 could inhibit the viability and EMT of AML cells through the miR­455­3p/MCL1 axis.

Polyribonucleotide nucleotidyltransferase 1 participates in metabolic-associated fatty liver disease pathogenesis by affecting lipid metabolism and mitochondrial homeostasis.

OBJECTIVE: Metabolic-associated fatty liver disease (MAFLD) represents one of the most prevalent chronic liver conditions worldwide, but its precise pathogenesis remains unclear. This research endeavors to elucidate the involvement and molecular mechanisms of polyribonucleotide nucleotidyltransferase 1 (PNPT1) in the progression of MAFLD. METHODS: The study employed western blot and qRT-PCR to evaluate PNPT1 levels in liver specimens from individuals diagnosed with MAFLD and in mouse models subjected to a high-fat diet. Cellular studies investigated the effects of PNPT1 on lipid metabolism, apoptosis, and mitochondrial stability in hepatocytes. Immunofluorescence was utilized to track the subcellular movement of PNPT1 under high lipid conditions. RNA immunoprecipitation and functional assays were conducted to identify interactions between PNPT1 and Mcl-1 mRNA. The role of PPARα as an upstream transcriptional regulator of PNPT1 was investigated. Recombinant adenoviral vectors were utilized to modulate PNPT1 expression in vivo. RESULTS: PNPT1 was found to be markedly reduced in liver tissues from MAFLD patients and HFD mice. In vitro, PNPT1 directly regulated hepatic lipid metabolism, apoptosis, and mitochondrial stability. Under conditions of elevated lipids, PNPT1 relocated from mitochondria to cytoplasm, modifying its physiological functions. RNA immunoprecipitation revealed that the KH and S1 domains of PNPT1 bind to and degrade Mcl-1 mRNA, which in turn affects mitochondrial permeability. The transcriptional regulator PPARα was identified as a significant influencer of PNPT1, impacting both its expression and subsequent cellular functions. Alterations in PNPT1 expression were directly correlated with the progression of MAFLD in mice. CONCLUSIONS: The study confirms the pivotal function of PNPT1 in the development of MAFLD through its interactions with Mcl-1 and its regulatory effects on lipid metabolism and mitochondrial stability. These insights highlight the intricate association between PNPT1 and MAFLD, shedding light on its molecular pathways and presenting a potential new therapeutic avenue for MAFLD management.

Distinct pathway activities are associated with prognosis and response to bortezomib-containing treatment in MCL1-M based molecular subtypes of multiple myeloma.

Multiple myeloma (MM) is the second most prevalent hematological malignancy and remains incurable with remarkable heterogeneity in prognosis and treatment response across the patients. Clinical diagnosis and the existing molecular classification systems are inadequate for predicting treatment responses. Based on the convergence between plasma cell development and MM pathogenesis, we identified a gene co-expression module centered on the plasma cell survival regulator MCL1 (MCL1 module, MCL1-M) in the transcriptomes of pre-treated MM, which enabled stratification of MM patients into MCL1-M high and MCL1-M low molecular subtypes with subtype-specific prognosis and response to bortezomib-containing treatment. Here, we aimed to examine the mechanism underlying the disparate prognosis and treatment responses between the two molecular subtypes. Our findings reveal that MCL1-M high MM displays significant activation of pathways associated with cell proliferation, while MCL1-M low MM exhibits activation of immune-related signaling pathways. The relative enrichment of immune cells within the bone marrow microenvironment of MCL1-M low MM, particularly plasmacytoid dendritic cells, likely contributes to the activation of immune-related signaling pathways in this subset of myeloma cells. Using phase III trial data, we show that responses to bortezomib-containing treatment are associated with the extent of unfolded protein response (UPR) signaling activity. Further, bortezomib-mediated killing of MM cells could be enhanced or inhibited by in vitro manipulation of UPR activities in representative cell lines. In conclusion, MCL1-M based molecular subtypes of MM are characterized by distinct signaling activities from both malignant cells and bone marrow microenvironment, which may drive distinct prognosis and treatment responses.

The Protective Effects of Mcl-1 on Mitochondrial Damage and Oxidative Stress in Imiquimod-Induced Cancer Cell Death.

Mitochondria, vital organelles that generate ATP, determine cell fate. Dysfunctional and damaged mitochondria are fragmented and removed through mitophagy, a mitochondrial quality control mechanism. The FDA-approved drug IMQ, a synthetic agonist of Toll-like receptor 7, exhibits antitumor activity against various skin malignancies. We previously reported that IMQ promptly reduced the level of the antiapoptotic Mcl-1 protein and that Mcl-1 overexpression attenuated IMQ-triggered apoptosis in skin cancer cells. Furthermore, IMQ profoundly disrupted mitochondrial function, promoted mitochondrial fragmentation, induced mitophagy, and caused cell death by generating high levels of ROS. However, whether Mcl-1 protects mitochondria from IMQ treatment is still unknown. In this study, we demonstrated that Mcl-1 overexpression induced resistance to IMQ-induced apoptosis and reduced both IMQ-induced ROS generation and oxidative stress in cancer cells. Mcl-1 overexpression maintained mitochondrial function and integrity and prevented mitophagy in IMQ-treated cancer cells. Furthermore, IL-6 protected against IMQ-induced apoptosis by increasing Mcl-1 expression and attenuating IMQ-induced mitochondrial fragmentation. Mcl-1 overexpression ameliorates IMQ-induced ROS generation and mitochondrial fragmentation, thereby increasing mitochondrial stability and ultimately attenuating IMQ-induced cell death. Investigating the roles of Mcl-1 in mitochondria is a potential strategy for cancer therapy development.

Flow cytometric expression of Bcl-2, Mcl-1, and their ratios correlates with primary and secondary cytogenetic changes and their combinations in multiple myeloma.

Response to BH3 mimetics in multiple myeloma (MM) correlates with CCND1-rearrangement or expression of anti-apoptotic molecules, particularly Bcl-2 and Mcl-1. Our study investigates the relationship between cytogenetic abnormalities (CGAs) and intracellular Bcl-2 and Mcl-1 expression in myeloma plasma cells (MPCs) using flow cytometry (FCM). We measured median fluorescence intensity (MFI) of Bcl-2 and Mcl-1 in 163 bone marrow samples (143 MM, 20 controls) across various cell types. Both Bcl-2MFI and Mcl-1MFI were significantly higher in MPCs compared to other cells, with Bcl-2 MFI exceeding Mcl-1 MFI in MPCs. Bcl-2 expression peaked in CCND1-rearranged cases, while Mcl-1 expression was highest in cases with 1q21 gain/amplification. Notably, 65-74% of cases with other CGAs exhibited moderate to strong Bcl-2 or Mcl-1 expression, indicating potential utility of BH3 mimetics in this group, while 25% showed dim to absent expression of one or both markers, suggesting potential futility in these patients. Our study highlights FCM's potential for rapid Bcl-2 and Mcl-1 quantification, surpassing traditional methods. We propose that direct measurement of Bcl-2 and Mcl-1 expression in PCs by FCM, combined with cytogenetic characterization, could improve therapeutic decision-making regarding the use of BH3 mimetics in MM, potentially enhancing outcomes and overcoming resistance.

NL101 synergizes with the BCL-2 inhibitor venetoclax through PI3K-dependent suppression of c-Myc in acute myeloid leukaemia.

BACKGROUND: Acute myeloid leukaemia (AML) comprises a group of heterogeneous and aggressive haematological malignancies with unsatisfactory prognoses and limited treatment options. Treatments targeting B-cell lymphoma-2 (BCL-2) with venetoclax have been approved for patients with AML, and venetoclax-based drug combinations are becoming the standard of care for older patients unfit for intensive chemotherapy. However, the therapeutic duration of either single or combination strategies is limited, and the development of resistance seems inevitable. Therefore, more effective combination regimens are urgently needed. METHODS: The efficacy of combination therapy with NL101, a SAHA-bendamustine hybrid, and venetoclax was evaluated in preclinical models of AML including established cell lines, primary blasts from patients, and animal models. RNA-sequencing and immunoblotting were used to explore the underlying mechanism. RESULTS: NL101 significantly potentiated the activity of venetoclax in AML cell lines, as evidenced by the enhanced decrease in viability and induction of apoptosis. Mechanistically, the addition of NL101 to venetoclax decreased the stability of the antiapoptotic protein myeloid cell leukaemia-1 (MCL-1) by inhibiting ERK, thereby facilitating the release of BIM and triggering mitochondrial apoptosis. Moreover, the strong synergy between NL101 and venetoclax also relied on the downregulation of c-Myc via PI3K/Akt/GSK3ß signalling. The combination of NL101 and venetoclax synergistically eliminated primary blasts from 10 AML patients and reduced the leukaemia burden in an MV4-11 cell-derived xenograft model. CONCLUSIONS: Our results encourage the pursuit of clinical trials of combined treatment with NL101 and venetoclax and provide a novel venetoclax-incorporating therapeutic strategy for AML.

Clitocine enhances the drug sensitivity of colon cancer cells by promoting FBXW7-mediated MCL-1 degradation via inhibiting the A2B/cAMP/ERK axis.

Chemotherapy resistance to colon cancer is an unavoidable obstacle in the clinical management of the disease. Clitocine, an adenosine analog, played a significant role in the chemosensitivity of human colon cancer cells by promoting myeloid cell leukemia 1 (MCL-1) protein degradation. However, the detailed mechanism remains to be further elucidated. We found that clitocine upregulates the expression of F-box and WD repeat domain containing 7 (FBXW7), a ubiquitin ligase involved in the MCL-1 degradation. Transcriptome sequencing analysis revealed that clitocine significantly inhibits the cyclic adenosine monophosphate (cAMP) and extracellular regulated protein kinases (ERK) downstream signaling pathways in colon cancer cells, thereby enhancing FBXW7 expression and subsequently promoting the ubiquitination degradation of MCL-1 protein. We verified that clitocine regulated intracellular cAMP levels by competitive binding with the adenosine receptor A2B. A molecular docking assay also verified the binding relationship. By decreasing intracellular cAMP levels, clitocine blocks the activation of downstream signaling pathways, which ultimately enhances the drug sensitivity of colon cancer cells through increased FBXW7 expression due to the inhibition of its promoter DNA methylation. Both knockout of the adenosine receptor A2B and Br-cAMP treatment can effectively attenuate the function of clitocine in vitro and in vivo. This study clarified that clitocine enhanced the drug sensitivity of colon cancer cells by promoting FBXW7-mediated MCL-1 degradation via inhibiting the A2B/cAMP/ERK axis, providing further knowledge of the clinical application for clitocine.NEW & NOTEWORTHY Our study found that clitocine enhances the drug sensitivity of colon cancer cells by promoting FBXW7-mediated MCL-1 degradation via inhibiting the A2B/cAMP/ERK axis.

Regulatory axis of circular RNA DTNB, microRNA-485-5p, and myeloid cell leukemia 1 attenuates inflammation and apoptosis in caerulein-treated AR42J cells.

Acute pancreatitis (AP) is an inflammatory disease of the pancreas and the main cause of hospital admissions for gastrointestinal diseases. Here, the work studied the circular RNA DTNB/microRNA-485-5p/MCL1 axis in AP and hoped to unravel the related mechanism. Caerulein exposure replicated an AP model in AR42J cells, and caerulein-mediated expression of circDTNB, miR-485-5p, and MCL1 was recorded. After exposure, cells were intervened with transfection plasmids and tested for LDH release, apoptosis, and inflammation. To determine the interwork of circDTNB, miR-485-5p, and MCL1, prediction results and verification experiments were conducted. Caerulein exposure reduced circDTNB and MCL1, while elevated miR-485-5p levels in AR42J cells. Upregulating circDTNB protected AR42J cells from caerulein-induced LDH cytotoxicity, apoptosis, and inflammation, but circDTNB upregulation-induced protections could be muffled by inhibiting MCL1. On the contrary, downregulating circDTNB further damaged AR42J cells under caerulein exposure, however, this phenomenon could be partially rescued after silencing miR-485-5p. miR-485-5p was mechanistically verified to be a target of circDTNB to mediate MCL1. Overall, the circDTNB/miR-485-5p/MCL1 axis protects inflammatory response and apoptosis in caerulein-exposed AR42J cells, promisingly identifying circDTNB as a novel molecule for AP treatment.

Targeting MCL1 with Sanggenon C overcomes MCL1-driven adaptive chemoresistance via dysregulation of autophagy and endoplasmic reticulum stress in cervical cancer.

BACKGROUND: Cervical cancer ranks as one of the most prevalent malignancies among women worldwide and poses a significant threat to health and quality of life. MCL1 is an antiapoptotic protein closely linked to tumorigenesis, drug-resistance and poor prognosis in various cancers. Sanggenon C, a natural flavonoid derived from Morus albal., exhibits multiple activities, including anti-oxidant, anti-inflammatory, antivirus, and antitumor properties. However, the molecular mechanisms by which Sanggenon C exerts antitumor effects on in cervical cancer remain unclear. PURPOSE: To investigate the oncogenic role of MCL1 and elucidate the antitumor activity of Sanggenon C, along with its molecular mechanisms, in cervical cancer. METHODS: In vitro, the effects of Sanggenon C on proliferation, the cell cycle, apoptosis, and autophagy were explored. Transcriptome sequencing was employed to analyze critical genes and pathways. The expression of genes or proteins was evaluated via immunofluorescence, qRT-PCR, immunohistochemistry, and Western blotting. To identify targets of Sanggenon C, various techniques such as clinical database analysis, molecular docking, cellular thermal shift assays, co-immunoprecipitation, and ubiquitination assays were utilized. Additionally, Xenograft mouse models were established to further investigate Sanggenon C as a novel MCL1 inhibitor and its anti-tumor activity in vivo. RESULTS: Our investigation reveals that Sanggenon C effectively inhibits cervical cancer cell proliferation both in vitro and in vivo. Furthermore, Sanggenon C induces endoplasmic reticulum stress and triggers protective autophagy via activation of the ATF4-DDIT3-TRIB3-AKT-MTOR signaling axis. Furthermore, Sanggenon C specifically targets MCL1 to exert its antitumor effects by modulating MCL1 protein stability through SYVN1-mediated ubiquitination. Notably, MCL1 overexpression attenuates the Sanggenon C-induced decrease in cell viability and apoptosis. Our study further characterizes the role of MCL1 in cisplatin resistance and identifies MCL1 as a promising target for Sanggenon C, which effectively inhibits proliferation and induces apoptosis in cisplatin-resistant cervical cancer cells. Importantly, combining Sanggenon C with an autophagy inhibitor represents a promising strategy to enhance therapeutic outcomes in cisplatin-resistant cervical cancer cells. CONCLUSION: Our findings demonstrates that Sanggenon C induces endoplasmic reticulum stress and highlights the potential of targeting MCL1 to exploit vulnerabilities in drug-resistant cervical cancer cells. Sanggenon C emerges as a promising therapeutic agent against MCL1-driven adaptive chemoresistance through disruption of autophagy and endoplasmic reticulum stress in cervical cancer.

Discovery and development of thiazolidine-2,4-dione derivatives as Bcl-2/Mcl-1 dual inhibitors.

Increasing the levels of antiapoptotic Bcl-2 proteins is an important way that cancer cells utilize to get out of apoptosis, underscoring their significance as promising targets for anticancer therapies. Lately, a primary compound 1 bearing thiazolidine-2,4-dione was discovered to exhibit comparable Mcl-1 inhibitory activity in comparison to WL-276. Herein, thirty-nine thiazolidine-2,4-dione analogs were yielded through incorporating different biphenyl moieties (R1), amino acid side chains (R2) and sulfonamides (R3) on 1. The findings indicated that certain compounds exhibited favorable inhibitory effects against Bcl-2/Mcl-1, while demonstrating limited or negligible binding affinity towards Bcl-xL. In particular, compounds 16 and 20 exhibited greater Bcl-2/Mcl-1 inhibition compared to AT-101, WL-276 and 1. Moreover, they demonstrated notable antiproliferative effects and significantly induced apoptosis in U937 cells. The western blot and co-immunoprecipitation assays confirmed that 20 could induce alterations in the expression of apoptosis-associated proteins to result in apoptosis through on-target Bcl-2 and Mcl-1 inhibition. In addition, 20 exhibited favorable stability profiles in both rat plasma and rat liver microsomes. In total, 20 could be used as a promising compound to discover Bcl-2/Mcl-1 dual inhibitors with favorable therapeutic properties.

Initial AXL and MCL-1 inhibition contributes to abolishing lazertinib tolerance in EGFR-mutant lung cancer cells.

Lazertinib, a novel third-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI), demonstrates marked efficacy in EGFR-mutant lung cancer. However, resistance commonly develops, prompting consideration of therapeutic strategies to overcome initial drug resistance mechanisms. This study aimed to elucidate the adaptive resistance to lazertinib and advocate novel combination treatments that demonstrate efficacy in preventing resistance as a first-line treatment for EGFR mutation-positive NSCLC. We found that AXL knockdown significantly inhibited lung cancer cell viability in the presence of lazertinib, indicating that AXL activation contributes to lazertinib resistance. However, long-term culture with a combination of lazertinib and AXL inhibitors led to residual cell proliferation and increased the MCL-1 expression level, which was mediated by the nuclear translocation of the transcription factor YAP. Triple therapy with an MCL-1 or YAP inhibitor in combination with lazertinib and an AXL inhibitor significantly reduced cell viability and increased the apoptosis rate. These results demonstrate that AXL and YAP/MCL-1 signals contribute to adaptive lazertinib resistance in EGFR-mutant lung cancer cells, suggesting that the initial dual inhibition of AXL and YAP/MCL-1 might be a highly effective strategy in eliminating lazertinib-resistant cells.

Capivasertib reverses chemotherapy-induced esophageal cancer resistance via inhibiting Akt-associated Mcl-1 upregulation.

The development of resistance to chemotherapy in esophageal cancer represents a significant challenge in cancer treatment. Therefore, our study aimed to identify effective therapeutic strategies by examining the molecules involved in this chemoresistance. We consistently observed an increase in the expression of Mcl-1 in cells exposed to both short and long-term treatment with cisplatin, a drug commonly used in esophageal cancer therapy. Functional analysis showed that Mcl-1 regulates esophageal cancer cell response to cisplatin treatment. Notably, this upregulation of Mcl-1 was not dependent on eukaryotic initiation factor 4E (eIF4E). Instead, it was associated with increased stability due to the activation of Akt. Capivasertib, a potent pan-Akt kinase drug, significantly decreased Mcl-1 level via inhibiting Akt signaling pathway in chemo-resistant cells. In addition, capivasertib not only decreased the viability of chemo-resistant esophageal cancer cells but also synergistically enhanced the effects of cisplatin. In multiple mouse models, representing both chemo-resistant and chemo-sensitive esophageal cancer, capivasertib administered at non-toxic doses demonstrated remarkable efficacy. It significantly extended the overall survival of the mice. Our research underscores the pivotal role of Akt-associated Mcl-1 upregulation in the development of chemo-resistance in esophageal cancer cells. Furthermore, it highlights the potential of capivasertib to reverse this resistance mechanism.

The HTLV-I oncoprotein Tax inactivates the tumor suppressor FBXW7.

Human T-cell leukemia virus type 1 (HTLV-I) is the etiological agent of adult T-cell leukemia (ATL). Mutational analysis has demonstrated that the tumor suppressor, F-box and WD repeat domain containing 7 (FBXW7/FBW7/CDC4), is mutated in primary ATL patients. However, even in the absence of genetic mutations, FBXW7 substrates are stabilized in ATL cells, suggesting additional mechanisms can prevent FBXW7 functions. Here, we report that the viral oncoprotein Tax represses FBXW7 activity, resulting in the stabilization of activated Notch intracellular domain, c-MYC, Cyclin E, and myeloid cell leukemia sequence 1 (BCL2-related) (Mcl-1). Mechanistically, we demonstrate that Tax directly binds to FBXW7 in the nucleus, effectively outcompeting other targets for binding to FBXW7, resulting in decreased ubiquitination and degradation of FBXW7 substrates. In support of the nuclear role of Tax, a non-degradable form of the nuclear factor kappa B subunit 2 (NFκB2/p100) was found to delocalize Tax to the cytoplasm, thereby preventing Tax interactions with FBXW7 and Tax-mediated inhibition of FBXW7. Finally, we characterize a Tax mutant that is unable to interact with FBXW7, unable to block FBXW7 tumor suppressor functions, and unable to effectively transform fibroblasts. These results demonstrate that HTLV-I Tax can inhibit FBXW7 functions without genetic mutations to promote an oncogenic state. These results suggest that Tax-mediated inhibition of FBXW7 is likely critical during the early stages of the cellular transformation process. IMPORTANCE: F-box and WD repeat domain containing 7 (FBXW7), a critical tumor suppressor of human cancers, is frequently mutated or epigenetically suppressed. Loss of FBXW7 functions is associated with stabilization and increased expression of oncogenic factors such as Cyclin E, c-Myc, Mcl-1, mTOR, Jun, and Notch. In this study, we demonstrate that the human retrovirus human T-cell leukemia virus type 1 oncoprotein Tax directly interacts with FBXW7, effectively outcompeting other targets for binding to FBXW7, resulting in decreased ubiquitination and degradation of FBXW7 cellular substrates. We further demonstrate that a Tax mutant unable to interact with and inactivate FBXW7 loses its ability to transform primary fibroblasts. Collectively, our results describe a novel mechanism used by a human tumor virus to promote cellular transformation.

The CDK9 inhibitor enitociclib overcomes resistance to BTK inhibition and CAR-T therapy in mantle cell lymphoma.

Inhibitors of Bruton's tyrosine kinase (BTKi) and chimeric antigen receptor T-cell (CAR-T) therapy targeting CD19 are paradigm-shifting advances in treating patients with aggressive mantle cell lymphoma (MCL). However, clinical relapses following BTKi and CD19-directed CAR-T treatments are a fast-growing medical challenge. Development of novel therapies to overcome BTKi resistance (BTKi-R) and BTKi-CAR-T dual resistance (Dual-R) are urgently needed. Our single-cell RNA sequencing data revealed major transcriptomic reprogramming, with great enrichment of MYC-targets evolving as resistance to these therapies developed. Interestingly, cyclin-dependent kinase 9 (CDK9), a critical component of the positive transcription elongation factor-b complex, was among the top upregulated genes in Dual-R vs. BTKi-R samples. We therefore hypothesized that targeting CDK9 may turn off MYC-driven tumor survival and drug resistance. Enitociclib (formerly VIP152) is a selective CDK9 inhibitor whose potency against MCL has not been assessed. In this study, we found that enitociclib was highly potent in targeting lymphoma cells, with the half-maximal inhibitory concentration (IC50) ranging from 32 to 172 nM in MCL and diffuse large B-cell lymphoma cell lines. It inhibited CDK9 phosphorylation and downstream events including de novo synthesis of the short-lived proteins c-MYC, MCL-1, and cyclin D1, and induced apoptosis in a caspase-3-dependent manner. Enitociclib potently inhibited in vivo tumor growth of cell line-derived and patient-derived xenografts having therapeutic resistance. Our data demonstrate the potency of enitociclib in overcoming therapeutic resistance in MCL models and provide evidence in favor of its clinical investigation.

Modeling the Binding of Anticancer Peptides and Mcl-1.

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.

Gypenosides exert cardioprotective effects by promoting mitophagy and activating PI3K/Akt/GSK-3ß/Mcl-1 signaling.

Background: Gynostemma pentaphyllum (Thunb.) Makino, a well-known edible and medicinal plant, has anti-aging properties and is used to treataging-associated conditions such as diabetes, metabolic syndrome, and cardiovascular diseases. Gypenosides (GYPs) are the primary constituents of G. pentaphyllum. Increasing evidence indicates that GYPs are effective at preserving mitochondrial homeostasis and preventing heart failure (HF). This study aimed to uncover the cardioprotective mechanisms of GYPs related to mitochondrial regulation. Methods: The bioactive components in GYPs and the potential targets in treating HF were obtained and screened using the network pharmacology approach, followed by drug-disease target prediction and enrichment analyses. The pharmacological effects of GYPs in cardioprotection, mitochondrial function, mitochondrial quality control, and underlying mechanisms were further investigated in Doxorubicin (Dox)-stimulated H9c2 cardiomyocytes. Results: A total of 88 bioactive compounds of GYPs and their respective 71 drug-disease targets were identified. The hub targets covered MAPK, EGFR, PI3KCA, and Mcl-1. Enrichment analysis revealed that the pathways primarily contained PI3K/Akt, MAPK, and FoxO signalings, as well as calcium regulation, protein phosphorylation, apoptosis, and mitophagy process. In Dox-stimulated H9c2 rat cardiomyocytes, pretreatment with GYPs increased cell viability, enhanced cellular ATP content, restored basal oxygen consumption rate (OCR), and improved mitochondrial membrane potential (MMP). Furthermore, GYPs improved PINK1/parkin-mediated mitophagy without influencing mitochondrial fission/fusion proteins and the autophagic LC3 levels. Mechanistically, the phosphorylation of PI3K, Akt, GSK-3ß, and the protein level of Mcl-1 was upregulated by GYP treatment. Conclusion: Our findings reveal that GYPs exert cardioprotective effects by rescuing the defective mitophagy, and PI3K/Akt/GSK-3ß/Mcl-1 signaling is potentially involved in this process.

Novel markers of MCL1 inhibitor sensitivity in triple-negative breast cancer cells.

Triple-negative breast cancer (TNBC) is an aggressive breast cancer sub-type with limited treatment options and poor prognosis. Currently, standard treatments for TNBC include surgery, chemotherapy, and anti-PDL1 therapy. These therapies have limited efficacy in advanced stages. Myeloid-cell leukemia 1 (MCL1) is an anti-apoptotic BCL2 family protein. High expression of MCL1 contributes to chemotherapy resistance and is associated with a worse prognosis in TNBC. MCL1 inhibitors are in clinical trials for TNBC, but response rates to these inhibitors can vary and predictive markers are lacking. Currently, we identified a 4-member (AXL, ETS1, IL6, EFEMP1) gene signature (GS) that predicts MCL1 inhibitor sensitivity in TNBC cells. Factors encoded by these genes regulate signaling pathways to promote MCL1 inhibitor resistance. Small molecule inhibitors of the GS factors can overcome resistance and sensitize otherwise resistant TNBC cells to MCL1 inhibitor treatment. These findings offer insights into potential therapeutic strategies and tumor stratification for MCL1 inhibitor use in TNBC.

Targeting MCL1-driven anti-apoptotic pathways overcomes blast progression after hypomethylating agent failure in chronic myelomonocytic leukemia.

RAS pathway mutations, which are present in 30% of patients with chronic myelomonocytic leukemia (CMML) at diagnosis, confer a high risk of resistance to and progression after hypomethylating agent (HMA) therapy, the current standard of care for the disease. Here, using single-cell, multi-omics technologies, we seek to dissect the biological mechanisms underlying the initiation and progression of RAS pathway-mutated CMML. We identify that RAS pathway mutations induce transcriptional reprogramming of hematopoietic stem and progenitor cells (HSPCs) and downstream monocytic populations in response to cell-intrinsic and -extrinsic inflammatory signaling that also impair the functions of immune cells. HSPCs expand at disease progression after therapy with HMA or the BCL2 inhibitor venetoclax and rely on the NF-κB pathway effector MCL1 to maintain survival. Our study has implications for the development of therapies to improve the survival of patients with RAS pathway-mutated CMML.

Chitosan-TPP encapsulated quercetin nanoparticles: amplified protection mechanisms unveiled against Ethion-induced developmental toxicity through comprehensive in-vivo and in-silico elucidation.

Aim: The study investigated Ethion-induced developmental toxicity in Wistar albino rats and the potential ameliorative effects of quercetin and nano-quercetin co-administration. Further, In-silico docking of Ethion and quercetin with MCL-1 was conducted. Methodology: Quercetin nanoparticles were synthesized by ionic-gelation method. The encapsulated quercetin nanoparticles were characterized for Zeta size, UV-Vis spectroscopy, encapsulation efficiency, and TEM studies. Male rats were administered Ethion (high/low dose), quercetin, and nano-quercetin alone or in combination for 60 days. Female rats were introduced for mating on the 61st day, and pregnant females were observed for 20 gestational days. On GD 20, rats were sacrificed and evaluated for body/organ weight, reproductive indices, fetal morphology, skeletal, and visceral deformities.In silico binding energies of ethion and quercetin with MCL-1 were determined. Results: Nanoparticle size was 363.2 ± 1.23 nm on day 0 and 385.63 ± 1.53 nm on day 60, with PDI of 0.247 and charge of 22.9 mV. Absorbance maxima were at 374 nm, with encapsulation efficacy of 85.16 ± 0.33%. EHD male crossed females showed decreased body/organ weights, reduced fertility, hematoma, cleft palate, tail curling, and absence of extremity. Nano-quercetin co-administration normalized parameters comparable to controls. Both Ethion and quercetin interacted with MCL-1, with quercetin exhibiting stronger binding energy. Conclusion: Nano-quercetin demonstrated stronger antioxidant properties than quercetin, counteracting ethion-induced maternal/fetal abnormalities.