Overcome Drug Resistance Research Articles

Abstract IA023: Dual-drug ADC platform for effective and safe cancer treatment

Abstract Breast tumor heterogeneity presents significant treatment challenges, particularly in overcoming drug resistance and tumor relapse driven by heterogeneous gene expression variability. Antibody-drug conjugates (ADCs) have demonstrated therapeutic success, yet intratumor heterogeneity remains a hurdle. We investigated dual-drug ADCs as a promising approach to address this clinical challenge. Our conjugates achieved potent and antigen-specific cytotoxicity, favorable pharmacokinetic properties, and high tolerability. In xenograft models with heterogeneous HER2 expression, our anti-HER2 dual-drug ADC significantly outperformed co-administration of two separate single-drug ADCs, demonstrating enhanced capacity to surmount tumor heterogeneity and resistance. Additionally, we developed a novel glutamic acid-glycine-citrulline (EGCit) linker, which enhances ADC hydrophilicity and stability in circulation. This EGCit linker also resists neutrophil protease degradation, a factor implicated in ADC-associated neutropenia. Compared to currently approved ADCs, our EGCit-based ADC exhibited reduced blood and liver toxicity, alongside superior antitumor efficacy in preclinical xenograft studies. These findings underscore the potential of our technology platform for advancing safer, more effective treatments for breast and other refractory cancers. Citation Format: Kyoji Tsuchikama. Dual-drug ADC platform for effective and safe cancer treatment [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Optimizing Therapeutic Efficacy and Tolerability through Cancer Chemistry; 2024 Dec 9-11; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Mol Cancer Ther 2024;23(12_Suppl):Abstract nr IA023.

Rationalizing the crosslinking reaction of an α,β unsaturated carbonyl of clovamide from Adansonia digitata L. and the cysteine residue of HIV-1 integrase enzyme

In this study, clovamide was identified for the first time in Adansonia digitata L. fruit pulp using the UHPLC-q-TOF-MS. The inhibition potential of the naturally occurring clovamide, specifically in the SE and SZ configurations and their yet to be identified enantiomers (RE and RZ) on HIV-1 integrase (HIV-1 INT) were investigated using molecular docking studies. The results revealed that all the four stereoisomers of clovamide bind to key residues crucial for the catalytic activity of HIV-1 INT (ASP64, ASP116 and GLU152) as well as other significant residues including, LYS152 and LYS159. This indicates that clovamide has the potential to inhibit this enzyme and possibly slow down HIV-1 replication. Interestingly, the docking results showed that CYS65 was in close proximity to ASP64, allowing nearly all isomers of clovamide to interact with this residue. This suggested a potential crosslinking reaction via Michael addition between clovamide and CYS65. The consistent proximity of all ligands to CYS65 in the studied protein throughout the entire molecular dynamics simulation period also showed the potential of permanent covalent bonds formation via a Michael addition reaction. Density functional theory modelling confirmed that the α,β-unsaturated carbonyl group of clovamide and cysteine interact, forming a clovamide-integrase adduct, potentially leading to irreversible inhibition of HIV-1 INT. This study not only highlighted the potential of clovamide as an inhibitor of HIV-1 INT but also demonstrated that clovamide possesses various functional groups that can be exploited in different biological activity studies. Findings of this study suggest that clovamide and its stereoisomers could be valuable candidates for the development of new antiretroviral therapies, offering a novel approach to overcoming drug resistance through multiple inhibition mechanisms.

Cedrus atlantica extract inhibits melanoma progression by suppressing epithelial-mesenchymal transition and inducing mitochondria-mediated apoptosis.

Melanoma has a low incidence, accounting for less than 5% of skin cancers; however, it is the most lethal cancer, primarily because of its high potential for metastasis and resistance to different treatments. Natural products can sensitize melanoma to chemotherapy and overcome drug resistance. Previous studies have reported Cedrus atlantica extract has various pharmacological benefits such as anti-inflammatory, antioxidant, antibacterial, and analgesic properties. This study aimed to explore the effects of C. atlantica extract (CAt) against melanoma in vitro and in vivo. The effects of CAt on B16F10 cell viability, proliferation, migration, invasion, and apoptosis were detected using MTT, colony formation, wound-healing, Boyden chamber, and TUNEL assays. Semi-quantitative RT-PCR and western blotting were used to measure mRNA and protein expression, respectively. Results revealed that CAt selectively decreased the viability of B16F10 cells and inhibited colony formation in a dose-dependent manner. CAt reduces cell migration and invasion by regulating epithelial-mesenchymal transition-associated proteins (Snail, E-cadherin, and vimentin). Moreover, CAt enhanced the Bax/Bcl-2 ratio and the expression of cleaved-caspase-9, caspase-3, and PARP1, resulting in the activation of mitochondria-mediated apoptosis. In an in vivo study, CAt significantly inhibited tumor growth and prolonged the lifespan of mice at a well-tolerated dose. Importantly, the combination of CAt and 5-fluorouracil (5-FU) exhibited synergistic growth suppression and attenuated the development of 5-FU resistance. Overall, the findings suggest that CAt holds promise as a potential drug or adjuvant to improve melanoma treatment.

Advances in Understanding Drug Resistance Mechanisms and Innovative Clinical Treatments for Melanoma.

Melanoma, a highly invasive skin cancer resulting from melanocyte malignant transformation, is the third most common skin malignancy. Despite accounting for only 4% to 5% of all skin malignancies, it is responsible for 80% of skin cancer-related deaths. Targeted therapies and immune checkpoint inhibitors have improved survival rates, yet drug resistance remains a major challenge. In this review, I explore the latest research progress on melanoma drug resistance mechanisms and clinical treatment methods. This aims to provide insights for more effective treatment strategies and improve patient prognosis and quality of life. I also discuss potential strategies to overcome drug resistance based on the latest scientific findings, with a particular focus on the complex and multi-factorial drug resistance mechanisms of melanomas, including genetic mutations, epigenetic changes, and tumor microenvironment factors. Understanding these mechanisms is crucial for developing new drugs and combination therapies targeting drug-resistant tumors. Analyzing complex drug resistance pathways paves the way for personalized medical approaches, which is expected to provide enlightenment on breaking through drug resistance barriers and enhancing the effectiveness of melanoma treatment.

Furopyridine Derivatives as Potent Inhibitors of the Wild Type, L858R/T790M, and L858R/T790M/C797S EGFR.

The treatment of patients with nonsmall cell lung cancer (NSCLC) using epidermal growth factor receptor (EGFR) inhibitors is complicated by drug-sensitive activating L858R/T790M and L858R/T790M/C797S mutations. To overcome drug resistance, a series of furopyridine (PD) compounds were virtually screened to identify potent EGFR inhibitors using molecular docking and molecular dynamics (MD) simulations based on the solvated interaction energy (SIE) method. Several PD compounds identified from virtual screening demonstrated the potential to suppress both wild-type and mutant forms of EGFR, with IC50 values in the nanomolar range. Among these, PD18 and PD56 exhibited highly potent inhibitory activity against both wild-type and mutant forms of EGFR, surpassing the efficacy of known drugs. Additionally, both PD compounds were cytotoxic to NSCLC cell lines (A549 and H1975) while being nontoxic to normal cell lines (Vero). The interaction mechanisms of both PD compounds complexed with wild-type and mutant forms of EGFR were elucidated through 500 ns molecular dynamics simulations. The predicted binding affinity from molecular mechanics/Poisson-Boltzmann surface area (MM/PBSA) correlated well with the experimental binding affinity derived from IC50 values. Furthermore, it was observed that van der Waals interactions, rather than electrostatic interactions, played a significant role in interacting with EGFR's active site. The strong inhibitory activity against EGFR was attributed to two key residues, M793 and S797, via hydrogen bonding, corresponding with lower solvent accessibility and a higher number of atomic contacts. Therefore, these potent compounds could be developed as promising drugs targeting both wild-type and mutant EGFR for the treatment of NSCLC.

Innovative Nanomedicine Delivery: Targeting Tumor Microenvironment to Defeat Drug Resistance

Nanodrug delivery systems have revolutionized tumor therapy like never before. By overcoming the complexity of the tumor microenvironment (TME) and bypassing drug resistance mechanisms, nanotechnology has shown great potential to improve drug efficacy and reduce toxic side effects. This review examines the impact of the TME on drug resistance and recent advances in nanomedicine delivery systems to overcome this challenge. Characteristics of the TME such as hypoxia, acidity, and high interstitial pressure significantly reduce the effectiveness of chemotherapy and radiotherapy, leading to increased drug resistance in tumor cells. Then, this review summarizes innovative nanocarrier designs for these microenvironmental features, including hypoxia-sensitive nanoparticles, pH-responsive carriers, and multifunctional nanosystems that enable targeted drug release and improved drug penetration and accumulation in tumors. By combining nanotechnology with therapeutic strategies, this review offers a novel perspective by focusing on the innovative design of nanocarriers that interact with the TME, a dimension often overlooked in similar reviews. We highlight the dual role of these nanocarriers in therapeutic delivery and TME modulation, emphasize their potential to overcome drug resistance, and look at future research directions.

Thiazolidinedione derivatives in cancer therapy: exploring novel mechanisms, therapeutic potentials, and future horizons in oncology.

Thiazolidinedione derivatives have shown significant potential as targeted cancer therapies by leveraging their various mechanisms of action. These include suppressing cell proliferation, triggering apoptosis, and influencing signaling pathways associated with tumor development. Their multifaceted effects make them promising candidates for advancing cancer treatment strategies. They have shown significant promise as anti-cancer agents, particularly through their ability to inhibit lipogenesis pathways and apoptosis essential for cancer cell survival and proliferation. This review comprehensively examines the anti-cancer potential of thiazolidinedione derivatives by targeting key aspects of lipid metabolism, apoptosis, and various mechanistic pathways. This review provides an in-depth examination of the anti-cancer potential of TZD derivatives, focusing on their mechanisms of action, therapeutic applications, and future directions in oncology. The anti-tumor effects of TZDs primarily involve the stimulation of peroxisome proliferator-activated receptor gamma (PPAR-γ), suppressing cell proliferation, induction of apoptosis, and inhibition of angiogenesis. Moreover, recent evidence highlights their ability to modulate non-PPAR-γ pathways, such as PI3K/Akt, NF-κB, and MAPK, further expanding their role in overcoming drug resistance and enhancing therapeutic outcomes. This review explores the preclinical (in vitro and in vivo) and clinical research investigating TZD derivatives efficacy in various cancer types. The insights underscore the significance of targeting lipogenesis as a novel anti-cancer strategy, positioning thiazolidinedione derivatives as potent candidates for future cancer therapeutics. As the oncology landscape evolves, TZD derivatives (rosiglitazone, pioglitazone, inolitazone, troglitazone, and 2,4-thiazolidinedione derivatives) represent a promising class of agents with the potential to contribute meaningfully to cancer treatment. By integrating existing knowledge with recent advancements, this study provides valuable insights into the role of thiazolidinedione derivatives in cancer treatment, paving the way for further research and clinical applications.

The Association between NADPH Oxidase 2 (NOX2) and Drug Resistance in Cancer.

NADPH oxidase, as a major source of intracellular reactive oxygen species (ROS), assumes an important role in the immune response and oxidative stress response of the body. NADPH oxidase 2 (NOX2) is the first and most representative member of the NADPH oxidase family, and its effects on the development of tumor cells are gaining more and more attention. Our previous study suggested that NCF4 polymorphism in p40phox, a key subunit of NOX2, affected the outcome of diffuse large B-cell lymphoma patients treated with rituximab. It hypothesized that NOX2-mediated ROS could enhance the cytotoxic effects of some anti-tumor drugs in favor of patients with tumors. Several reviews have summarized the role of NOX2 and its congeners-mediated ROS in anti-tumor therapy, but few studies focused on the relationship between the expression of NOX2 and anti-tumor drug resistance. In this article, we systematically introduced the NOX family, represented by NOX2, and a classification of the latest inhibitors and agonists of NOX2. It will help researchers to have a more rational and objective understanding of the dual role of NOX2 in tumor drug resistance and is expected to provide new ideas for oncology treatment and overcoming drug resistance in cancer.

Innovative Nanomaterials for Targeting Hypoxia to Improve Treatment for Triple-negative Breast Cancer.

Triple-negative breast cancer (TNBC) is an aggressive breast cancer with a high rate of metastases, a short overall survival time, and a poor response to targeted therapy. Improving tumor hypoxia by lowering the oxygen consumption rate of breast tumor cells is a powerful strategy. A viable way to address this issue is to improve therapeutic efficacy by improving the effectiveness of radiation and overcoming drug resistance in TNBC treatment by controlling hypoxia in the tumor microenvironment. The failure of radiation and chemotherapy in TNBC is frequently caused by hypoxia. In TNBC therapy, novel nanomaterials are used for oxygen delivery or generation to affect the tumor microenvironment to improve the effects of ionizing radiation using nanoplatforms. One of the growing fields is novel nano-based drug delivery devices for hypoxic regions and hypoxia- inducible factor-1 (HIF1) targeted therapeutics. Biocompatible nanoparticles may be used in the treatment of TNBC patients in the clinic. Because of the rising market and competition, intellectual property rights (IPR), patents, and tactics may be critically considered. To better comprehend the current state of IPR and patents in cancer nanotechnology, this overview examines recent advances and sophisticated protection measures in this area.

Kinetic and structural studies of gamma-carbonic anhydrase from the oral pathogen Porphyromonas gingivalis.

Porphyromonas gingivalis, a key pathogen in periodontal disease, plays a critical role in systemic pathologiesdiseases by evading host defence mechanisms and invading periodontal tissues. Targeting its virulence mechanisms and overcoming drug resistance are essential steps toward effective therapeutic development. In this study, we focused on the Carbonic Anhydrase (CA, EC: 4.2.1.1) encoded by P. gingivalis as a potential drug target. We determined the crystal structure of PgiCA γ at a resolution of 2.4 Å and conducted kinetic characterization. The structure revealed that active PgiCA γ forms a trimer, with each monomer comprising a left-handed β-helix capped by a C-terminal α-helix and coordinated to a catalytic zinc ion through three histidine residues. Interestingly, one monomer displayed an atypical α-helix conformation, likely due to close interactions with neighbouring trimers within the crystal lattice (a probable crystallographic artefact). These findings provide new insights into the structural and functional properties of PgiCA γ, emphasizing its potential as a target for the development of novel anti-virulence therapies against P. gingivalis.

Genetic and microenvironmental evolution of colorectal liver metastases under chemotherapy.

Drug resistance limits the efficacy of chemotherapy for colorectal cancer liver metastasis (CRLM). However, the evolution of CRLM during drug treatment remains poorly elucidated. Multi-omics and treatment response data from 115 samples of 49 patients with CRLM undergoing bevacizumab (BVZ)-based chemotherapy show little difference in genomic alterations in 92% of cases, while remarkable differences are observed at the transcriptomic level. By decoupling intrinsic and acquired resistance, we find that hepatocyte and myeloid cell infiltration contribute to 38.5% and 23.1% of acquired resistance, respectively. Importantly, SMAD4 mutations and chr20q copy-number gain are associated with intrinsic chemoresistance. Gene interference experiments suggest that SMAD4R361H/C mutations confer BVZ and 5-fluorouracil (5-FU) resistance through STAT3 signaling. Notably, supplementing BVZ and 5-FU with the STAT3 inhibitor GB201 restores therapeutic efficacy in SMAD4R361H/C cancer cells. Our study uncovers the evolutionary dynamics of CRLM and its microenvironment during treatment and offers strategies to overcome drug resistance.

Pt(IV) Prodrug Photoactivation: A Promising Strategy for Cancer Therapy.

Platinum (II) drugs, including cisplatin, carboplatin, and oxaliplatin, have achieved significant clinical success in cancer treatment. However, their clinical application has been greatly hindered by various adverse factors, such as non-specific activation and drug resistance. Compared with Pt(II) drugs, the axial ligands within Pt(IV) compounds can improve the pharmacokinetic properties, selectivity, and biological activity, implementing alternative cytotoxic mechanisms beyond DNA cross-linking and partially overcoming drug resistance. The controlled conversion of Pt(IV) prodrugs into Pt(II) agents at the tumor site has been extensively explored internationally. In this review, Pt(IV) prodrug modification strategies are first summarized, and the development of the predominant external and internal photosensitizers is listed. Finally, three representative photoreduction mechanisms and strategies for developing corresponding Pt(IV) prodrugs are discussed. This work provides constructive instruction for the subsequent molecular design of Pt(IV) prodrugs.

ATR inhibition potentiates FOLFIRINOX cytotoxic effect in models of pancreatic ductal adenocarcinoma by remodelling the tumour microenvironment.

In pancreatic ductal adenocarcinoma (PDAC), the dense stroma rich in cancer-associated fibroblasts (CAFs) and the immunosuppressive microenvironment confer resistance to treatments. To overcome such resistance, we tested the combination of FOLFIRINOX (DNA damage-inducing chemotherapy drugs) with VE-822 (an ataxia-telangiectasia and RAD3-related inhibitor that targets DNA damage repair). PDAC spheroid models and organoids were used to assess the combination effects. Tumour growth and the immune and fibrotic microenvironment were evaluated by immunohistochemistry, single-cell analysis and spatial proteomics in patient-derived xenograft (PDX) and orthotopic immunocompetent KPC mouse models. The FOLFIRINOX and VE-822 combination had a strong synergistic effect in several PDAC cell lines, whatever their BRCA1, BRCA2 and ATM mutation status and resistance to standard chemotherapy agents. This was associated with high DNA damage and inhibition of DNA repair signalling pathways, leading to increased apoptosis. In immunocompetent and PDX mouse models of PDAC, the combination inhibited tumour growth more effectively than FOLFIRINOX alone. This was associated with tumour microenvironment remodelling, particularly decreased proportion of fibroblast activated protein-positive CAFs and increased anti-tumorigenic immune cell infiltration and interaction. The FOLFIRINOX and VE-822 combination is a promising strategy to improve FOLFIRINOX efficacy and overcome drug resistance in PDAC.

Mechanical forces inducing oxaliplatin resistance in pancreatic cancer can be targeted by autophagy inhibition

Pancreatic cancer remains one of the most lethal malignancies, with limited treatment options and poor prognosis. A common characteristic among pancreatic cancer patients is the biomechanically altered tumor microenvironment (TME), which among others is responsible for the elevated mechanical stresses in the tumor interior. Although significant research has elucidated the effect of mechanical stress on cancer cell proliferation and migration, it has not yet been investigated how it could affect cancer cell drug sensitivity. Here, we demonstrated that mechanical stress triggers autophagy activation, correlated with increased resistance to oxaliplatin treatment in pancreatic cancer cells. Our results demonstrate that inhibition of autophagy using hydroxychloroquine (HCQ) enhanced the oxaliplatin-induced apoptotic cell death in pancreatic cancer cells exposed to mechanical stress. The combined treatment of HCQ with losartan, a known modulator of mechanical abnormalities in tumors, synergistically enhanced the therapeutic efficacy of oxaliplatin in murine pancreatic tumor models. Furthermore, our study revealed that the use of HCQ enhanced the efficacy of losartan to alleviate mechanical stress levels and restore blood vessel integrity beyond its role in autophagy modulation. These findings underscore the potential of co-targeting mechanical stresses and autophagy as a promising therapeutic strategy to overcome drug resistance and increase chemotherapy efficacy.

Vibrational spectroscopic characterization, quantum chemical, molecular docking and molecular dynamics investigations of cyclo(L-phenylalanyl-L-proline), an anticancer agent

The molecular structure and spectral properties of cyclo(L-Phenylalanyl-L-Proline) dipeptide, which has several biological activities, were investigated. Firstly, conformational preference of the cyclo(L-Phenylalanyl-L-Proline) was searched and obtained lowest energy conformer of the cyclic dipeptide was then optimized using Density Functional Theory with wb97xd/6-311++G(d,p) level of theory. A detailed vibrational spectral analysis has been carried out and assignments of the fundamental modes have been proposed. The experimental vibrational wavenumbers of the investigated compound display good agreement with the computed values. The Frontier Molecular Orbitals, Molecular Electrostatic Potential and electronic transitions of the investigated compound were discussed. In addition, the 1H and 13C NMR chemical shifts of the cyclic dipeptide were calculated and the results were compared with the experimental values. Also, to evaluate the anticancer potential, molecular docking studies of cyclo(L-Phenylalanyl-L-Proline) within the ATP-binding sites of both wild type (EGFRWT; ID: 4HJO) and mutant (EGFRT790M; ID: 3W2O) Epidermal Growth Factor Receptor were performed. The results indicated that cyclo(Phe-Pro) has high binding affinities toward both EGFRWT (−6.6 kcal/mol) and EGFRT790M (−7.7 kcal/mol) receptors, thus, has good anticancer activity and also has potential to overcome drug resistance in therapy. Molecular dynamics simulations on cyclo(L-Phenylalanyl-L-Proline)-wild type complex were conducted through a 50-nanosecond timed to investigate the ligand-receptor interactions in more detail, and to determine the binding free energy accurately. The binding free energy of the cyclo(L-Phenylalanyl-L-Proline)-wild type complex was calculated to be −27.18 kcal/mol.

Preventing human influenza and coronaviral mono or coinfection by blocking virus-induced sialylation

Influenza A viruses (IAVs) and endemic coronaviruses (eCoVs) are common etiologic agents for seasonal respiratory infections. The human H1N1 of IAV and coronavirus OC43 (HCoV-OC43) can result in hospitalization, acute respiratory distress syndrome (ARDS), and even death, particularly in immunocompromised individuals. They infect the epithelium of the respiratory tract by interacting with host cell sialic acid (Sia)- linked receptors whose synthesis is catalyzed by sialyltransferases (STs). Viral coinfection is challenging to treat because of the need to target specific components of two or more distinct pathogens. Emerging drug and vaccine resistance due to the high mutation rate of viral genomes further complicates the treatment and prevention of viral infection. Sialylation mediated by STs may be a potential drug target for treating viral diseases. ST is an attractive target because it could be effective before identifying the pathogen that has occurred, providing a novel direction for overcoming drug resistance and achieving a broad-spectrum antiviral effect. We developed an H1N1 and OC43 mono or coinfection model using 14 days post-plating (14PP) human primary small airway epithelial cells (HSAEC) grown on transwell inserts at an air-fluid interface (ALI), mimicking in vivo cellular dynamics. Using this model, we have observed that mono or coinfection with OC43 and H1N1 results in increased sialic acid levels and synergistic viral infection. We showed for the first time that H1N1 and OC43 mono- and coinfection in HSAEC caused increased expression and activity of STs, which can be blocked by pan-STs inhibitor (3Fax-Peracetyl Neu5Ac) with no host cell toxicity.

ScStateDynamics: deciphering the drug-responsive tumor cell state dynamics by modeling single-cell level expression changes

Understanding tumor cell heterogeneity and plasticity is crucial for overcoming drug resistance. Single-cell technologies enable analyzing cell states at a given condition, but catenating static cell snapshots to characterize dynamic drug responses remains challenging. Here, we propose scStateDynamics, an algorithm to infer tumor cell state dynamics and identify common drug effects by modeling single-cell level gene expression changes. Its reliability is validated on both simulated and lineage tracing data. Application to real tumor drug treatment datasets identifies more subtle cell subclusters with different drug responses beyond static transcriptome similarity and disentangles drug action mechanisms from the cell-level expression changes.

KLF4 promotes cisplatin resistance by activating mTORC1 signaling in ovarian cancer

Ovarian cancer (OC) is a highly fatal gynecological malignancy worldwide, and cisplatin (CDDP) is commonly used as an initial chemotherapy treatment for OC. Nonetheless, most patients ultimately face recurrence because of resistance to cisplatin. Therefore, it is imperative to investigate the underlying mechanisms of drug resistance in OC. By analyzing differential gene expression using TCGA, GDSC, and GEO public databases, we discovered that increased KLF4 expression is strongly linked to chemotherapy resistance and unfavorable outcomes in OC. Subsequent validation through immunohistochemistry and western blotting confirmed the upregulated KLF4 expression in cisplatin-resistance OC cells lines and tissues. To investigate the function of KLF4, functional experiments were performed both in vitro and in vivo. We observed that knocking down KLF4 impaired cisplatin-resistance of OC. Further mechanism research based on RNA-seq and gene enrichment analysis revealed that interfering KLF4 suppressed the activation of mTORC1 pathway. Finally, rescue experiment demonstrated that using mTORC1 pathway inhibitor could attenuate the cisplatin resistance induced by the overexpression of KLF4. In conclusion, our research indicates that KLF4 promotes cisplatin resistance through the activation of mTORC1 signaling, and proposes that inhibiting KLF4 might serve as a viable therapeutic approach to overcoming drug resistance in ovarian cancer.

PKN2 is a dependency of the mesenchymal-like cancer cell state.

Cancer cells exploit a mesenchymal-like transcriptional state (MLS) to survive drug treatments. Although the MLS is well characterized, few therapeutic vulnerabilities targeting this program have been identified. Here, we systematically identify the dependency network of mesenchymal-like cancers through an analysis of gene essentiality scores in ~800 cancer cell lines, nominating a poorly studied kinase, PKN2, as a top therapeutic target of the MLS. Co-essentiality relationships, biochemical experiments, and genomic analyses of patient tumors revealed that PKN2 promotes mesenchymal-like cancer growth through a PKN2-SAV1-TAZ signaling mechanism. Notably, pairing genetic PKN2 inhibition with clinically relevant targeted therapies against EGFR, KRAS, and BRAF oncogenes suppresses drug resistance by depleting mesenchymal-like drug-tolerant persister cells. These findings provide evidence that PKN2 is a core regulator of the Hippo tumor suppressor pathway and highlight the potential of PKN2 inhibition as a generalizable therapeutic strategy to overcome drug resistance driven by the MLS across cancer contexts.

Solasodine Downregulates ABCB1 Overexpression in Multidrug Resistant Cancer Cells Via Inhibiting Nrf2/Keap1 Signaling Pathway.

Multidrug-resistant (MDR) cancer cells maintain redox homeostasis to eliminate oxidative stress-mediated cell death. This study explores the effects of solasodine on regulating P-glycoprotein (P-gp) expression through the Nrf2/Keap1 signaling pathway and oxidative stress-induced sensitization of drug-resistant cancer cells to chemotherapeutics. Initially, the oxidative stress indicators such as intracellular ROS generation, the levels of 8-hydroxy-2-deoxyguanosine (8-OHdG) and gamma-H2AX (γ-H2AX) in the KBChR-8-5 drug-resistant cells were measured. Additionally, the protein expression levels of Nuclear factor erythroid 2-related factor 2 (Nrf-2), Kelch-like ECH-associated protein 1 (Keap1), and ATP Binding Cassette Subfamily B Member 1 (ABCB1)/P-gp were measured at various concentrations of solasodine (1, 5, & 10 µM) through immunofluorescence and western blot analysis. The antioxidant activities in the KBChR-8-5 cells were assessed using established protocols. In this investigation, the treatment with solasodine and doxorubicin combination showed a notable increase in intracellular ROS generation in KBChR-8-5 cells. Furthermore, this combination treatment led to enhanced nuclear condensation, elevated levels of 8-OHdG, and increased γ-H2AX foci formation in the KBChR-8-5 cells. Solasodine treatment effectively inhibited the nuclear translocation of Nrf2 and activation of the ABCB1 gene, consequently preventing overexpression of P-gp in KBChR-8-5 cells. Additionally, the combination therapy increased the lipid peroxidation levels while simultaneously reducing the activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and the levels of glutathione (GSH). These results demonstrated that solasodine disrupts redox balance, and overcomes drug resistance by downregulating P-gp via regulating Nrf2/Keap1 signaling pathway in MDR cancer cells.