Three-dimensional Tumor Spheroids Research Articles

Spatial Metabolomics Profiling Reveals Curcumin Induces Metabolic Reprogramming in Three-Dimensional Tumor Spheroids

Curcumin is widely recognized for its diverse antitumor properties, ranging from breast cancer to many other types of cancers. However, its role in the tumor microenvironment remains to be elucidated. In this study, we established a 3D tumor spheroids model that can simulate the growth environment of tumor cells and visualized the antitumor metabolic alteration caused by curcumin using mass spectrometry imaging technology. Our results showed that curcumin not only exerts a profound impact on the growth and proliferation of breast cancer cells but in situ multivariate statistical analysis also reveals the significant effect on the overall metabolic profile of tumor spheroids. Meanwhile, our visualization map characterized curcumin metabolic processes of reduction and glucuronidation in tumor spheroids. More importantly, abnormal metabolic pathways related to lipid metabolism and polyamine metabolism were also remodeled at the metabolite and gene levels after curcumin intervention. These insights deepen our comprehension of the regulatory mechanism of curcumin on the tumor metabolic network, furnishing powerful references for antitumor treatment.

Activatable near-infrared fluorescence probe for real-time imaging of PD-L1 expression in tumors.

In clinical practice, determining programmed death-ligand 1 (PD-L1) expression is crucial for selecting patients and monitoring immune checkpoint blockade therapies. Currently, PD-L1 expression is quantified using immunohistochemistry (IHC). However, IHC-based methods do not capture the heterogeneous and dynamic nature of PD-L1 expression. Thus, there is a pressing need for a rapid and efficient method for monitoring PD-L1 expression both in vitro and in vivo, which would considerably aid in prognosis and treatment selection. In this study, we present for the first time an activatable near-infrared (NIR) fluorescence imaging probe (Q-Atezol) for the real-time monitoring of PD-L1 expression in vitro and in vivo. The ability of Q-Atezol to detect PD-L1 expression quickly and in real-time was evaluated in both tumor spheroid and lung cancer xenograft models. An always-on optical probe (ON-Atezol) was synthesized and tested for comparison. In vivo NIR fluorescence imaging studies were conducted on A549 and H1975 tumor-bearing mice, and their tumor-to-background ratios (TBRs) were analyzed. The quenched NIR fluorescence of Q-Atezol is activated upon binding to PD-L1 proteins on the surface of cancer cells, thereby enabling PD-L1 detection in the three-dimensional (3D) tumor spheroids without a washing step. Notably, PD-L1-positive H1975 tumors were clearly visualized with a high TBR 6 hours after Q-Atezol injection, whereas ON-Atezol treatment could not detect H1975 tumors even 24 hours post-injection. The activatable fluorescence probe Q-Atezol demonstrated great potential as an exceptional sensor for assessing PD-L1 expression in 3D cell structures and for in vivo applications.

109Pd/109mAg in-vivo generator in the form of nanoparticles for combined β- - Auger electron therapy of hepatocellular carcinoma

BackgroundConvenient therapeutic protocols for hepatocellular carcinoma (HCC) are often ineffective due to late diagnosis and high tumor heterogeneity, leading to poor long-term outcomes. However, recently performed studies suggest that using nanostructures in liver cancer treatment may improve therapeutic effects. Inorganic nanoparticles represent a unique material that tend to accumulate in the liver when introduced in-vivo. Typically, this is a major drawback that prevents the therapeutic use of nanoparticles in medicine. However, in HCC tumours, this may be advantageous because nanoparticles may accumulate in the target organ, where the leaky vasculature of HCC causes their accumulation in tumour cells via the EPR effect. On the other hand, recent studies have shown that combining low- and high-LET radiation emitted from the same radionuclide, such as 161Tb, can increase the effectiveness of radionuclide therapy. Therefore, to improve the efficacy of radionuclide therapy for hepatocellular carcinoma, we suggest utilizing radioactive palladium nanoparticles in the form of 109Pd/109mAg in-vivo generator that simultaneously emits β− particles and Auger electrons.ResultsPalladium nanoparticles with a size of 5 nm were synthesized using 109Pd produced through neutron irradiation of natural palladium or enriched 108Pd. Unlike the 109Pd-cyclam complex, where the daughter radionuclide diffuses away from the molecules, 109mAg remains within the nanoparticles after the decay of 109Pd. In vitro cell studies using radioactive 109Pd nanoparticles revealed that the nanoparticles accumulated inside cells, reaching around 50% total uptake. The 109Pd-PEG nanoparticles exhibited high cytotoxicity, even at low levels of radioactivity (6.25 MBq/mL), resulting in almost complete cell death at 25 MBq/mL. This cytotoxic effect was significantly greater than that of PdNPs labeled with β− (131I) and Auger electron emitters (125I). The metabolic viability of HCC cells was found to be correlated with cell DNA DSBs. Also, successful radioconjugate anticancer activity was observed in three-dimensional tumor spheroids, resulting in a significant treatment response.ConclusionThe results indicate that nanoparticles labeled with 109Pd can be effectively used for combined β− - Auger electron-targeted radionuclide therapy of HCC. Due to the decay of both components (β− and Auger electrons), the 109Pd/109mAg in-vivo generator presents a unique potential in this field.

Saikosaponin D potentiates the antineoplastic effects of doxorubicin in drug-resistant breast cancer through perturbing NQO1-mediated intracellular redox balance

BackgroundDrug resistance to doxorubicin (DOX) significantly limits its therapeutic efficacy in breast cancer (BC) patients. Saikosaponin D (SSD), a triterpene saponin derived from the traditional herb Radix Bupleuri, has shown promise as a chemotherapeutic sensitizer in preclinical studies due to its notable antitumor activity. However, the role and mechanism of SSD in DOX-resistant BC cells remain largely unexplored. PurposeThis study aimed to investigate the chemosensitizing effect of SSD on DOX-resistant BC and the underlying molecular mechanisms both in vitro and in vivo. MethodsIn vitro assays, including cell viability, clone formation, three-dimensional tumor spheroid growth, and apoptosis analysis, were conducted to evaluate the synergistic effect of SSD and DOX on resistant BC cells. Reactive oxygen species (ROS), GSH/GSSG, NADPH/NADP+, and NADH/NAD+ detections were employed to assess the impact of SSD on cellular redox homeostasis. Western blotting, cell cycle distribution assay, and DOX uptake assay were performed to further elucidate the possible antineoplastic mechanism of SSD. Finally, a subcutaneous MCF7/DOX cell xenografted model in nude mice was established to identify the in vivo anticarcinogenic effect of SSD combined with DOX. ResultsSSD significantly inhibited cell viability, proliferation, and clone formation, enhancing DOX's anticancer efficacy in vitro and in vivo. Mechanistically, SSD reduced STAT1, NQO1, and PGC-1α protein levels, leading to cellular redox imbalance, excessive ROS generation, and depletion of GSH, NADPH, and NADH. SSD induced DNA damage by disrupting redox homeostasis, resulting in G0/G1 phase cell cycle arrest. Additionally, SSD increased DOX accumulation in BC cells via inhibiting P-gp protein expression and efflux activity. ConclusionWe demonstrated for the first time that SSD enhances the sensitivity of chemoresistant BC cells to DOX by disrupting cellular redox homeostasis through inactivation of the STAT1/NQO1/PGC-1α signaling pathway. This study provides evidence for SSD as an adjuvant agent in drug-resistant BC treatment.

A Nanoencapsulated Ir(III)-Phthalocyanine Conjugate as a Promising Photodynamic Therapy Anticancer Agent.

Despite the potential of photodynamic therapy (PDT) in cancer treatment, the development of efficient and photostable photosensitizing molecules that operate at long wavelengths of light has become a major hurdle. Here, we report for the first time an Ir(III)-phthalocyanine conjugate (Ir-ZnPc) as a novel photosensitizer for high-efficiency synergistic PDT treatment that takes advantage of the long-wavelength excitation and near infrared (NIR) emission of the phthalocyanine scaffold and the known photostability and high phototoxicity of cyclometalated Ir(III) complexes. In order to increase water solubility and cell membrane permeability, the conjugate and parent zinc phthalocyanine (ZnPc) were encapsulated in amphoteric redox-responsive polyurethane-polyurea hybrid nanocapsules (Ir-ZnPc-NCs and ZnPc-NCs, respectively). Photobiological evaluations revealed that the encapsulated Ir-ZnPc conjugate achieved high photocytotoxicity in both normoxic and hypoxic conditions under 630 nm light irradiation, which can be attributed to dual Type I and Type II reactive oxygen species (ROS) photogeneration. Interestingly, PDT treatments with Ir-ZnPc-NCs and ZnPc-NCs significantly inhibited the growth of three-dimensional (3D) multicellular tumor spheroids. Overall, the nanoencapsulation of Zn phthalocyanines conjugated to cyclometalated Ir(III) complexes provides a new strategy for obtaining photostable and biocompatible red-light-activated nano-PDT agents with efficient performance under challenging hypoxic environments, thus offering new therapeutic opportunities for cancer treatment.

Promising G-Quadruplex-Targeted Dibenzoquinoxaline Type-1 Photosensitizer Triggers DNA Damage in Triple-Negative Breast Cancer Cells.

G-quadruplexes (G4s) are potential drug targets in cancer treatment. However, the G4-targeted ligands seem to lack sufficient selectivity between tumors and normal tissues, appealing for a new modified anticancer strategy on the basis of them. Type-1 photodynamic therapy (PDT) is a promising strategy possessing excellent spatiotemporal precision for solid tumors with a hypoxic microenvironment. However, type-1 photosensitizers that target G4s and induce in situ photodamage have never been previously reported. In this study, we reported a promising type-1 photosensitizer based on a G4-targeted, high-contrast fluorescent ligand (TR2). The subsequent studies demonstrated that TR2 could transfer from lysosomes to nuclei and induce elevated G4 formation as well as DNA damage upon irradiation. Notably, it was observed that TR2 may not activate DNA damage repair machinery upon irradiation, suggesting a durable, strong effect on inducing DNA damage. Consequently, light-irradiated TR2 exhibited excellent photocytotoxicity on triple-negative breast cancer cell proliferation (at nanomolar concentration) and showed obvious inhibition on the growth of three-dimensional (3D) tumor spheroids. Finally, RNA-seq analysis demonstrated that TR2-mediated PDT may have a negative impact on enhancing the DNA damage repair machinery and may activate the antitumor immunity pathways. Overall, this study provided a promising chemical tool for image-guided PDT.

N-desmethyldauricine from Menispermum dauricum DC suppresses triple-negative breast cancer growth in 2D and 3D models by downregulating the NF-κB signaling pathway

Triple negative breast cancer (TNBC) is the most aggressive subtype of breast cancer, for which targeted therapy regimens are lacking. The traditional Chinese medicine Menispermum dauricum DC (M. dauricum) and its compounds have been reported to have antitumor activity against various cancers; however, their anti-TNBC activity is unknown. In this work, dauricine and N-desmethyldauricine from M. dauricum were separated and identified to have anti-TNBC via a multi-component bioactivity and structure-guided method. The cell counting kit 8 assay showed that dauricine and N-desmethyldauricine inhibited the proliferation of four tested TNBC cell lines, with half maximal inhibitory concentration values ranging from 5.01 μM to 13.16 μM. Further research suggested that N-desmethyldauricine induced cell apoptosis, arrested cell cycle progression in the G0/G1 phase, and inhibited cell migration. Western blot analysis revealed that the proapoptotic protein cleaved-poly-ADP-ribose polymerase 1 was upregulated, and the G0/G1 phase-related proteins cyclin-dependent kinase 2 and cyclin D1 and the migration-related protein matrix metallopeptidase 9 were downregulated. Furthermore, N-desmethyldauricine decreased the protein expression of p65, an important subunit of nuclear factor kappa-beta (NF-κB). Moreover, an antiproliferation assay of three-dimensional (3D) tumor spheroids showed that N-desmethyldauricine diminished cell‒cell adhesion and suppressed the growth of TNBC 3D spheroids. Taken together, these findings indicate that N-desmethyldauricine inhibited the proliferation of TNBC cells and decreased the expression of p65 in the NF-κB pathway.

Preclinical Evaluation of a Novel Series of Polyfluorinated Thalidomide Analogs in Drug-Resistant Multiple Myeloma.

Immunomodulatory imide drugs (IMiDs) play a crucial role in the treatment landscape across various stages of multiple myeloma. Despite their evident efficacy, some patients may exhibit primary resistance to IMiD therapy, and acquired resistance commonly arises over time leading to inevitable relapse. It is critical to develop novel therapeutic options to add to the treatment arsenal to overcome IMiD resistance. We designed, synthesized, and screened a new class of polyfluorinated thalidomide analogs and investigated their anti-cancer, anti-angiogenic, and anti-inflammatory activity using in vitro and ex vivo biological assays. We identified four lead compounds that exhibit potent anti-myeloma, anti-angiogenic, anti-inflammatory properties using three-dimensional tumor spheroid models, in vitro tube formation, and ex vivo human saphenous vein angiogenesis assays, as well as the THP-1 inflammatory assay. Western blot analyses investigating the expression of proteins downstream of cereblon (CRBN) reveal that Gu1215, our primary lead candidate, exerts its activity through a CRBN-independent mechanism. Our findings demonstrate that the lead compound Gu1215 is a promising candidate for further preclinical development to overcome intrinsic and acquired IMiD resistance in multiple myeloma.

Kaempferol from Alpinia officinarum hance induces G2/M cell cycle arrest in hepatocellular carcinoma cells by regulating the ATM/CHEK2/KNL1 pathway

Ethnopharmacological relevanceAlpinia officinarum Hance (A. officinarum), a perennial herb known for its medicinal properties, has been used to treat various ailments, such as stomach pain, abdominal pain, emesis, and digestive system cancers. A. officinarum is extensively cultivated in the Qiongzhong and Baisha regions of Hainan, and it holds substantial therapeutic value for the local Li people of Hainan. Kaempferol, a flavonoid derived from A. officinarum, has demonstrated anticancer properties in various experimental and biological studies. Nevertheless, the precise mechanisms through which it exerts its anti-hepatocellular carcinoma (HCC) effects remain to be comprehensively delineated. Aim of the studyThis investigation aims to elucidate the anti-HCC effects of kaempferol derived from A. officinarum and to delve into its underlying mechanistic pathways. Materials and methodsUsing ultra-high performance liquid chromatography-mass spectrometry/mass spectrometry (UPLC-MS/MS) to identify active compounds in A. officinarum. HCCLM3 and Huh7 cells were used to study the anti-HCC effect of kaempferol from A. officinarum. The cytotoxicity and proliferation of kaempferol and A. officinarum were measured using CCK-8 and EDU staining. Wound-healing assays and three-dimensional tumor spheroid models were further used to evaluate migration and the anti-HCC activity of kaempferol. The cell cycle and apoptosis were evaluated by flow cytometry. Western blot and qRT-PCR were used to detect the expression of proteins and genes associated with the cell cycle checkpoints. Finally, bioinformatics was used to analyze the relationship between the differential expression of core targets in the ATM/CHEK2/KNL1 pathway and a poor prognosis in clinical HCC samples. ResultsUPLC-MS/MS was employed to detect five active compounds in A. officinarum, such as kaempferol. The CCK-8 and EDU assays showed that kaempferol and A. officinarum significantly inhibited the proliferation of HCC cells. A wound-healing assay revealed that kaempferol remarkably inhibited the migration of HCC cells. Kaempferol significantly suppressed the growth of tumor spheroids. In addition, kaempferol markedly induced G2/M arrest and promoted apoptosis of HCC cells. Mechanically, kaempferol significantly reduced the protein and mRNA expression levels of ATM, CHEK2, CDC25C, CDK1, CCNB1, MPS1, KNL1, and Bub1. Additionally, the combination of kaempferol and the ATM inhibitor KU55933 had a more significant anti-HCC effect. The results of bioinformatics showed that ATM, CHEK2, CDC25C, CDK1, and KNL1 were highly expressed in patients with HCC and cancer tissues, indicating that these genes have certain value in the clinical diagnosis of HCC. ConclusionsCollectively, our results revealed that kaempferol from A. officinarum inhibits the cell cycle by regulating the ATM/CHEK2/KNL1 pathway in HCC cells. In summary, our research presents an innovative supplementary strategy for HCC treatment.

Temozolomide resistance mechanisms: unveiling the role of translesion DNA polymerase kappa in glioblastoma spheroids in vitro.

Temozolomide (TMZ) is the leading therapeutic agent for combating Glioblastoma Multiforme (GBM). Nonetheless, the persistence of chemotherapy-resistant GBM cells remains an ongoing challenge, attributed to various factors, including the translesion synthesis (TLS) mechanism. TLS enables tumor cells to endure genomic damage by utilizing specialized DNA polymerases to bypass DNA lesions. Specifically, TLS polymerase Kappa (Polκ) has been implicated in facilitating DNA damage tolerance against TMZ-induced damage, contributing to a worse prognosis in GBM patients. To better understand the roles of Polκ in TMZ resistance, we conducted a comprehensive assessment of the cytotoxic, antiproliferative, antimetastatic, and genotoxic effects of TMZ on GBM (U251MG) wild-type (WTE) and TLS Polκ knockout (KO) cells, cultivated as three-dimensional (3D) tumor spheroids in vitro. Initial results revealed that TMZ: (i) induces reductions in GBM spheroid diameter (10-200 µM); (ii) demonstrates significant cytotoxicity (25-200 μM); (iii) exerts antiproliferative effects (≤25 μM) and promotes cell cycle arrest (G2/M phase) in Polκ KO spheroids when compared with WTE counterparts. Furthermore, Polκ KO spheroids exhibit elevated levels of cell death (Caspase 3/7) and display greater genotoxicity (53BP1) than WTE following TMZ exposure. Concerning antimetastatic effects, TMZ impedes invadopodia (3D invasion) more effectively in Polκ KO than in WTE spheroids. Collectively, the results suggest that TLS Polκ plays a vital role in the survival, cell death, genotoxicity, and metastatic potential of GBM spheroids in vitro when subjected to TMZ treatment. While the precise mechanisms underpinning this resistance remain elusive, TLS Polκ emerges as a potential therapeutic target for GBM patients.

Shrimp Lipids Inhibit Migration, Epithelial-Mesenchymal Transition, and Cancer Stem Cells via Akt/mTOR/c-Myc Pathway Suppression.

Shrimp is a rich source of bioactive molecules that provide health benefits. However, the high cholesterol content in shrimp oil may pose a risk. We utilized the cholesterol elimination method to obtain cholesterol-free shrimp lipids (CLs) and investigated their anticancer potential, focusing on cancer stem cells (CSCs) and epithelial-to-mesenchymal transition (EMT). Our study focused on CSCs and EMT, as these factors are known to contribute to cancer metastasis. The results showed that treatment with CLs at doses ranging from 0 to 500 µg/mL significantly suppressed the cell migration ability of human lung cancer (H460 and H292) cells, indicating its potential to inhibit cancer metastasis. The CLs at such concentrations did not cause cytotoxicity to normal human keratinocytes. Additionally, CL treatment was found to significantly reduce the levels of Snail, Slug, and Vimentin, which are markers of EMT. Furthermore, we investigated the effect of CLs on CSC-like phenotypes and found that CLs could significantly suppress the formation of a three-dimensional (3D) tumor spheroid in lung cancer cells. Furthermore, CLs induced apoptosis in the CSC-rich population and significantly depleted the levels of CSC markers CD133, CD44, and Sox2. A mechanistic investigation demonstrated that exposing lung cancer cells to CLs downregulated the phosphorylation of Akt and mTOR, as well as c-Myc expression. Based on these findings, we believe that CLs may have beneficial effects on health as they potentially suppress EMT and CSCs, as well as the cancer-potentiating pathway of Akt/mTOR/c-Myc.

Abstract 2306: A deep learning framework for automated segmentation and analysis of 3D breast cancer spheroid invasion dynamics

Abstract Invasion of neighboring tissues is a cardinal feature of malignancy, notably observed in aggressive cancers like breast cancer, where it can lead to significant morbidity. To explore cancer invasion dynamics, the implementation of a three-dimensional (3D) tumor spheroid invasion assay offers a swift approach to mimicking a tumor micro-region or micro-metastasis. Differential Interference Contrast (DIC) time-lapse imaging was chosen for its fluorescence-free and non-destructive advantages in capturing live spheroid movement. However, the subsequent analysis posed challenges, including out-of-focus cells and a voluminous dataset with diverse microscope planes and time points. Our study introduces a segmentation framework featuring in-focus spatial stacking algorithm and novel training architecture that enabling in-depth automated analysis of 3D spheroid invasion behaviors within a microenvironment. Firstly, the MDA-MB-231 breast cancer spheroids were cultured in a microwell dish and then incorporated into a collagen type I matrix for the 3D spheroid invasion assay. Capturing spheroid invasion dynamics involved acquiring 15 z-plane images (spaced at 20 µm intervals) per timepoint for each spheroid using DIC microscopy at 15-minute intervals over a 28-hour period, employing a 20X objective lens. We refined the Focus Stacking framework into Multiple Slices Blurry Stacking (MSB-Stack) by pre-filtering blurred areas before stacking images. This process produced 6390 slices consolidated into 426 labeled stacked images, highlighting Invasive area, Spheroid core, and Invasive cells post-invasion. We then enhanced Mask R-CNN (Region based-Convolutional Neural Networks) with a weak-to-strong augmentation mechanism, leveraging well-segmented samples from MSB-Stack for training on both fully stacked and blurred images. Blurry Consistency Mask R-CNN (BCMask R-CNN) demonstrates overall improvement across feature extractors, outperforming Mask R-CNN. Using Mean average precision (mAP) as the main metric for instance segmentation and detection, our proposed model achieves 73.0% and 65.2% on mAP @[0.5, 0.95], showcasing robustness. Notably, our best results for mAP @0.5 reach 96.6% and 96.7% on both tasks, underscoring the effectiveness of consistency training in mitigating unclear boundary issues during preprocessing. In conclusion, our proposed method, MSB-Stack, effectively addresses the challenge of unclear boundaries in 3D breast cancer cell DIC microscopy datasets. The integration of weak-to-strong consistency training in our model, BCMask R-CNN, not only mitigates biases but also enhances performance across different backbones, setting the stage for future advancements in cell-tracking tasks and broader migratory analyses. Citation Format: Thi Kim Ngan Ngo, Thanh-Huy Nguyen, Fang-Yu Lin, Ting-Yuan Tu. A deep learning framework for automated segmentation and analysis of 3D breast cancer spheroid invasion dynamics [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 2306.

Chemical Characterization and Evaluation of the Antitumoral Activity of Annona tomentosa R.E.Fr. on Breast (MCF-7) Three-Dimensional (3D) Tumor Spheroids

Annona tomentosa, popularly known as “araticum marolo”, is an Annonaceae with little scientific evidence regarding its phytochemistry and biological activities. Based on this, the present study carried out the chemical characterization of the methanolic extract and fractions of ethyl acetate and alkaloid of the stem bark of A. tomentosa, in addition to evaluating their influence on the viability, proliferation and migration of breast (MCF-7) cells in a three-dimensional (3D) model. The samples were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS), and the Global Natural Products Social Networking (GNPS) platform was used to construct a molecular network. 21 compounds were identified, of which 16 belong to the alkaloid class. Multicellular spheroids (MCTS) growth was reduced after 216 h of treatment, as well as their viability (ca. 50% for the extract and ca. 25% for the alkaloid fraction). The extract and the alkaloid fraction showed greater antiproliferative (at a concentration of 100 µg mL-1 after 216 h, ca. 48% for the extract and ca. 20% for the fraction) and antimigratory (at concentrations 50-500 µg mL-1 for the extract and 100-250 µg mL-1 for the fraction) effects. This study is pioneering in demonstrating the antitumor effects in a 3D culture model, also revealing its potential for the isolation of alkaloids.

Aptamer Conjugate-Based Ratiometric Fluorescent Probe for Precise Imaging of Therapy-Induced Cancer Senescence.

Therapy-induced cellular senescence has been increasingly recognized as a key mechanism to promote various aspects of carcinogenesis in a nonautonomous manner. Thus, real-time imaging monitoring of cellular senescence during cancer therapy is imperative not only to further elucidate its roles in cancer progression but also to provide guidance for medical management of cancer. However, it has long been a challenging task due to the lack of effective imaging molecule tools with high specificity and accuracy toward cancer senescence. Herein, we report the rational design, synthesis, and evaluation of an aptamer conjugate-based ratiometric fluorescent probe for precise imaging of therapy-induced cancer senescence. Unlike traditional senescence imaging systems, our probe targets two senescence-associated markers at both cellular and subcellular dimensions, namely, aptamer-mediated membrane marker recognition for active cell targeting and lysosomal marker-triggered ratiometric fluorescence changes of two cyanine dyes for site-specific, high-contrast imaging. Moreover, such a two-channel fluorescence response is activated after a one-step reaction and at the same location, avoiding the diffusion-caused signal decay previously encountered in dual-marker activated probes, contributing to spatiotemporally specific imaging of therapy-induced cancer senescence in living cells and three-dimensional multicellular tumor spheroids. This work may offer a valuable tool for a basic understanding of cellular senescence in cancer biology and interventions.

Nuclear localization of Argonaute 2 is affected by cell density and may relieve repression by microRNAs.

Argonaute protein is associated with post-transcriptional control of cytoplasmic gene expression through miRNA-induced silencing complexes (miRISC). Specific cellular and environmental conditions can trigger AGO protein to accumulate in the nucleus. Localization of AGO is central to understanding miRNA action, yet the consequences of AGO being in the nucleus are undefined. We show nuclear enrichment of AGO2 in HCT116 cells grown in two-dimensional culture to high density, HCT116 cells grown in three-dimensional tumor spheroid culture, and human colon tumors. The shift in localization of AGO2 from cytoplasm to nucleus de-represses cytoplasmic AGO2-eCLIP targets that were candidates for canonical regulation by miRISC. Constitutive nuclear localization of AGO2 using an engineered nuclear localization signal increases cell migration. Critical RNAi factors also affect the localization of AGO2. Knocking out an enzyme essential for miRNA biogenesis, DROSHA, depletes mature miRNAs and restricts AGO2 localization to the cytoplasm, while knocking out the miRISC scaffolding protein, TNRC6, results in nuclear localization of AGO2. These data suggest that AGO2 localization and miRNA activity can be regulated depending on environmental conditions, expression of mature miRNAs, and expression of miRISC cofactors. Localization and expression of core miRISC protein machinery should be considered when investigating the roles of miRNAs.

Molecular mechanisms of tumor cell stemness modulation during formation of spheroids: a review

Cancer stem cells (CSCs), their properties and interaction with the microenvironment are of interest in modern medicine and biology. There are many studies on the emergence of CSCs and their involvement in tumor pathogenesis. The most important property inherent to CSCs is their stemness. Stemness combines the ability of the cell to maintain its pluripotency, give rise to differentiated cells and interact with the environment to maintain a balance between dormancy, proliferation and regeneration. While adult stem cells exhibit these properties by participating in tissue homeostasis, CSCs behave as their malignant equivalents. High tumor resistance to therapy, the ability to differentiate, activate angiogenesis and metastasis arise precisely due to stemness of CSCs. These cells can be used as a target for therapy of different types of cancer. Laboratory models are needed to study cancer biology and find new therapeutic strategies. A promising direction is three-dimensional tumor models or spheroids. Such models form properties resembling stemness in a natural tumor. By modifying spheroids, it becomes possible to investigate the effect of therapy on CSCs, thus contributing to the development of anti-tumor drug test systems. The review examines the niche of CSCs, the possibility of their study using three-dimensional spheroids, and existing markers for assessing stemness of CSCs.

Radiobiological Assessment of Targeted Radionuclide Therapy with [177Lu]Lu-PSMA-I&T in 2D vs. 3D Cell Culture Models

In vitro therapeutic efficacy studies are commonly conducted in cell monolayers. However, three-dimensional (3D) tumor spheroids are known to better represent in vivo tumors. This study used [177Lu]Lu-PSMA-I&T, an already clinically applied radiopharmaceutical for targeted radionuclide therapy against metastatic castrate-resistant prostate cancer, to demonstrate the differences in the radiobiological response between 2D and 3D cell culture models of the prostate cancer cell lines PC-3 (PSMA negative) and LNCaP (PSMA positive). After assessing the target expression in both models via Western Blot, cell viability, reproductive ability, and growth inhibition were assessed. To investigate the geometric effects on dosimetry for the 2D vs. 3D models, Monte Carlo simulations were performed. Our results showed that PSMA expression in LNCaP spheroids was highly preserved, and target specificity was shown in both models. In monolayers of LNCaP, no short-term (48 h after treatment), but only long-term (14 days after treatment) radiobiological effects were evident, showing decreased viability and reproductive ability with the increasing activity. Further, LNCaP spheroid growth was inhibited with the increasing activity. Overall, treatment efficacy was higher in LNCaP spheroids compared to monolayers, which can be explained by the difference in the resulting dose, among others.

Efficient Radial-Shell Model for 3D Tumor Spheroid Dynamics with Radiotherapy

Understanding the complex dynamics of tumor growth to develop more efficient therapeutic strategies is one of the most challenging problems in biomedicine. Three-dimensional (3D) tumor spheroids, reflecting avascular microregions within a tumor, are an advanced in vitro model system to assess the curative effect of combinatorial radio(chemo)therapy. Tumor spheroids exhibit particular crucial pathophysiological characteristics such as a radial oxygen gradient that critically affect the sensitivity of the malignant cell population to treatment. However, spheroid experiments remain laborious, and determining long-term radio(chemo)therapy outcomes is challenging. Mathematical models of spheroid dynamics have the potential to enhance the informative value of experimental data, and can support study design; however, they typically face one of two limitations: while non-spatial models are computationally cheap, they lack the spatial resolution to predict oxygen-dependent radioresponse, whereas models that describe spatial cell dynamics are computationally expensive and often heavily parameterized, impeding the required calibration to experimental data. Here, we present an effectively one-dimensional mathematical model based on the cell dynamics within and across radial spheres which fully incorporates the 3D dynamics of tumor spheroids by exploiting their approximate rotational symmetry. We demonstrate that this radial-shell (RS) model reproduces experimental spheroid growth curves of several cell lines with and without radiotherapy, showing equal or better performance than published models such as 3D agent-based models. Notably, the RS model is sufficiently efficient to enable multi-parametric optimization within previously reported and/or physiologically reasonable ranges based on experimental data. Analysis of the model reveals that the characteristic change of dynamics observed in experiments at small spheroid volume originates from the spatial scale of cell interactions. Based on the calibrated parameters, we predict the spheroid volumes at which this behavior should be observable. Finally, we demonstrate how the generic parameterization of the model allows direct parameter transfer to 3D agent-based models.

Patient-derived exosomes facilitate therapeutic targeting of oncogenic MET in advanced gastric cancer.

Gastric cancer (GC) with peritoneal metastases and malignant ascites continues to have poor prognosis. Exosomes mediate intercellular communication during cancer progression and promote therapeutic resistance. Here, we report the significance of exosomes derived from malignant ascites (EXOAscites) in cancer progression and use modified exosomes as resources for cancer therapy. EXOAscites from patients with GC stimulated invasiveness and angiogenesis in an ex vivo three-dimensional autologous tumor spheroid microfluidic system. EXOAscites concentration increased invasiveness, and blockade of their secretion suppressed tumor progression. In MET-amplified GC, EXOAscites contain abundant MET; their selective delivery to tumor cells enhanced angiogenesis and invasiveness. Exosomal MET depletion substantially reduced invasiveness; an additive therapeutic effect was induced when combined with MET and/or VEGFR2 inhibition in a patient-derived MET-amplified GC model. Allogeneic MET-harboring exosome delivery induced invasion and angiogenesis in a MET non-amplified GC model. MET-amplified patient tissues showed higher exosome concentration than their adjacent normal tissues. Manipulating exosome content and production may be a promising complementary strategy against GC.

Assessing the Layer-by-Layer Assembly of Cellulose Nanofibrils and Polyelectrolytes in Pancreatic Tumor Spheroid Formation.

Three-dimensional (3D) tumor spheroids are regarded as promising models for utilization as preclinical assessments of chemo-sensitivity. However, the creation of these tumor spheroids presents challenges, given that not all tumor cell lines are able to form consistent and regular spheroids. In this context, we have developed a novel layer-by-layer coating of cellulose nanofibril-polyelectrolyte bilayers for the generation of spheroids. This technique builds bilayers of cellulose nanofibrils and polyelectrolytes and is used here to coat two distinct 96-well plate types: nontreated/non-sterilized and Nunclon Delta. In this work, we optimized the protocol aimed at generating and characterizing spheroids on difficult-to-grow pancreatic tumor cell lines. Here, diverse parameters were explored, encompassing the bilayer count (five and ten) and multiple cell-seeding concentrations (10, 100, 200, 500, and 1000 cells per well), using four pancreatic tumor cell lines-KPCT, PANC-1, MiaPaCa-2, and CFPAC-I. The evaluation includes the quantification (number of spheroids, size, and morphology) and proliferation of the produced spheroids, as well as an assessment of their viability. Notably, our findings reveal a significant influence from both the number of bilayers and the plate type used on the successful formation of spheroids. The novel and simple layer-by-layer-based coating method has the potential to offer the large-scale production of spheroids across a spectrum of tumor cell lines.