The Influence of Antitumor Unsymmetrical Bisacridines on 3D Cancer Spheroids Growth and Viability

An acoustic levitation platform for high-content histological analysis of 3D tissue culture

Miniaturized three-dimensional (3D) cell culture systems, in particular organoids and spheroids, hold great potential for studying morphogenesis, disease modeling, and drug discovery. However, sub-cellular resolution 3D imaging of these biological samples remains a challenge. Histology, the gold standard for ex vivo microscopic interrogation of tissue anatomy, may address this challenge once the associated techniques are adapted. Due to their small size and delicate structure, organoids must be embedded in a supporting hydrogel. The histological sections have low information content because the distribution of the organoids within the gel is not controlled. To address this issue, we introduce an acoustic micromanipulation platform that concentrates and aligns organoids within a histology-compatible hydrogel block. Utilizing an array of micromachined lead zirconate titanate (PZT) transducers, the platform generates localised and precisely controlled acoustic standing waves to levitate organoids to a prescribed plane and fix their positions within a polyethylene glycol diacrylate (PEGDA)-gelatine hydrogel. Organoids from different culture conditions can be co-embedded in a traceable fashion with the use of a custom-design hydrogel grid. Our results demonstrate that more than 70% of spheroids can be positioned within a 150 μm-thick hydrogel block, substantially increasing the information content of histology sections. The platform's versatility, scalability, and ease of use will make histological assessment accessible to every life science laboratory.

Advancing Radiobiology: Investigating the Effects of Photon, Proton, and Carbon-Ion Irradiation on PANC-1 Cells in 2D and 3D Tumor Models

Introduction: Pancreatic cancer (PC) is one of the most aggressive and lethal malignancies, calling for enhanced research. Pancreatic ductal adenocarcinoma (PDAC) represents 70-80% of all cases and is known for its resistance to conventional therapies. Carbon-ion radiotherapy (CIRT) has emerged as a promising approach due to its ability to deliver highly localized doses and unique radiobiological properties compared to X-rays. In vitro radiobiology has relied on two-dimensional (2D) cell culture models so far; however, these are not sufficient to replicate the complexity of the in vivo tumor architecture. Three-dimensional (3D) models become a paradigm shift, surpassing the constraints of traditional models by accurately re-creating morphological, histological, and genetic characteristics as well as the interaction of tumour cells with the microenvironment. Materials and Methods: This study investigates the survival of pancreatic cancer cells in both 2D and spheroids, a 3D model, following photon, proton, and carbon-ion irradiation by means of clonogenic, MTT, spheroid growth, and vitality assays. Results: Our results demonstrate that carbon ions are more efficient in reducing cancer cell survival compared to photons and protons. In 2D cultures, carbon-ion irradiation reduced cell survival to approximately 15%, compared to 45% with photons and 30% with protons. In the 3D culture model, spheroid growth was similarly inhibited by carbon-ion irradiation; however, the overall survival rates were higher across all irradiation modalities compared to the 2D cultures. Carbon ions consistently showed the highest efficacy in reducing cell viability in both models. Conclusions: Our research highlights the pivotal role of 3D models in unraveling the complexities of pancreatic cancer radiobiology, offering new avenues for designing more effective and precise treatment protocols.

Cancer Epithelial Cells Participate in the Self-Organization of Lung Tumor Spheroids: A Morphological Approach

INTRODUCTION/AIMS

The tumor microenvironment is known to play an important role in tumor progression. However, the specific mechanisms underlying this process are still not known in detail and more research is needed on the elements that control tumor progression in lung cancer. In this work, we aimed to investigate the involvement of epithelial and stromal cancer cells in growth, cell migration, and epithelial-to-mesenchymal transition (EMT) in a 3D in vitro model consisting of cell spheroids cultured in a type I collagen scaffold.

METHODS

Spheroids were manufactured using different combinations of epithelial cells, particularly H460 and H1792 cell lines, with cancer-associated fibroblasts and normal fibroblasts, both isolated from adenocarcinoma patients. We evaluated the morphology of the spheroids by analysis of F-actin and pankeratin with confocal microscopy. We determined the ultrastructure of cells in the spheroids by transmission electron microscopy and the expression of CDH1, CDH2, and VIM by RT-PCR.

RESULTS

We observed that, on the one hand, the type of epithelial cell influences the morphology of spheroids. Stromal cells stimulated spheroid growth and cell dissemination through the collagen matrix, either alone or organized in branches with a nucleus of epithelial cells preceded by fibroblast cells. They also induced the appearance of new cell groups in the scaffold and the presence of EMT markers.

CONCLUSION

The results presented here indicate the participation of both epithelial and stromal cells in the control of spheroid self-organization. The experimental model proposed here, although preliminary, is useful for the study of some aspects related to tumor progression in lung cancer.

3D tumor spheroids: morphological alterations a yardstick to anti-cancer drug response

Tumor spheroids are one of the well-characterized 3D culture systems bearing close resemblance to the physiological tissue organization and complexity of avascular solid tumor stage with hypoxic core. They hold a wide-spread application in the field of pharmaceutical science and anti-cancer drug research. However, the difficulty in determining optimal technique for the generation of spheroids with uniform size and shape, evaluation of experimental outputs, or mass production often limits their usage in anti-cancer research and in high-throughput drug screening. In recent times, several studies have demonstrated various simple techniques for generating uniform-size 3D spheroids, including the hanging drop (HD), liquid overlay technique (LOT), and microfluidic approaches. Morphological alterations apart from biochemical assays, and staining techniques are suitably employed for the evaluation of experimental outcomes within 3D spheroid models. Morphological alterations in response to effective anti-cancer drug treatment in 3D tumor spheroids such as reduced spheroid size, loss of spheroid compactness and integrity or smooth surface, are highly reliable. These alterations can significantly reduce the need for biochemical assays and staining techniques, resulting in both time and cost savings. The present article specifically covers a variety of available procedures in spheroid generation. For practical applicability, we have supplemented our review study with the generation of glioblastoma U87 spheroids using HD and LOT methods. Additionally, we have also incorporated the outcome of U87 spheroid treatment with doxorubicin on spheroid morphology.

Cellular Effects of Selected Unsymmetrical Bisacridines on the Multicellular Tumor Spheroids of HCT116 Colon and A549 Lung Cancer Cells in Comparison to Monolayer Cultures

Multicellular tumor spheroids are a good tool for testing new anticancer drugs, including those that may target cancer stem cells (CSCs), which are responsible for cancer progression, metastasis, and recurrence. Therefore, we applied this model in our studies of highly active antitumor unsymmetrical bisacridines (UAs). We investigated the cellular response induced by UAs in 2D and 3D cultures of HCT116 colon and A549 lung cancer cells, with an additional focus on their impact on the CSC-like population. We showed that UAs affected the viability of the studied cells, as well as their spherogenic potential in the 2D and 3D cultures. Furthermore, we proved that the most promising UAs (C-2045 and C-2053) induced apoptosis in the HCT116 and A549 spheres to a similar, or even higher, extent than what was found in monolayer conditions. Next, we identified the population of the CSC-like cells in the 2D and 3D cultures of the studied cell lines by determining the levels of CD166, CD133, CD44, and EpCAM markers. We showed that the selected UAs affected the CSC-like population in both of the cell lines, and that A549 was affected more profoundly in 3D than in 2D cultures. Thus, the UAs exhibited high antitumor properties in both the 2D and 3D conditions, which makes them promising candidates for future therapeutic applications.

In Vitro Enzyme Kinetics and NMR-Based Product Elucidation for Glutathione S-Conjugation of the Anticancer Unsymmetrical Bisacridine C-2028 in Liver Microsomes and Cytosol: Major Role of Glutathione S-Transferase M1-1 Isoenzyme

This work is the next step in studying the interplay between C-2028 (anticancer-active unsymmetrical bisacridine developed in our group) and the glutathione S-transferase/glutathione (GST/GSH) system. Here, we analyzed the concentration- and pH-dependent GSH conjugation of C-2028 in rat liver microsomes and cytosol. We also applied three recombinant human GST isoenzymes, which altered expression was found in various tumors. The formation of GSH S-conjugate of C-2028 in liver subfractions followed Michaelis-Menten kinetics. We found that C-2028 was conjugated with GSH preferentially by GSTM1-1, revealing a sigmoidal kinetic model. Using a colorimetric assay (MTT test), we initially assessed the cellular GST/GSH-dependent biotransformation of C-2028 in relation to cytotoxicity against Du-145 human prostate cancer cells in the presence or absence of the modulator of GSH biosynthesis. Pretreatment of cells with buthionine sulfoximine resulted in a cytotoxicity decrease, suggesting a possible GSH-mediated bioactivation process. Altogether, our results confirmed the importance of GSH conjugation in C-2028 metabolism, which humans must consider when planning a treatment strategy. Finally, nuclear magnetic resonance spectroscopy elucidated the structure of the GSH-derived product of C-2028. Hence, synthesizing the compound standard necessary for further advanced biological and bioanalytical investigations will be achievable.

Xanthohumol hinders invasion and cell cycle progression in cancer cells through targeting MMP2, MMP9, FAK and P53 genes in three-dimensional breast and lung cancer cells culture

BACKGROUND

Despite recent advances in the treatment of lung and breast cancer, the mortality with these two types of cancer is high. Xanthohumol (XN) is known as a bioactive compound that shows an anticancer effect on cancer cells. Here, we intended to investigate the anticancer effects of XN on the breast and lung cancer cell lines, using the three-dimensional (3D) cell culture.

METHODS

XN was isolated from Humulus lupulus using Preparative-Thin Layer Chromatography (P-TLC) method and its authenticity was documented through Fourier Transform Infrared spectroscopy (FT-IR) and Hydrogen Nuclear Magnetic Resonance (H-NMR) methods. The spheroids of the breast (MCF-7) and lung (A549) cancer cell lines were prepared by the Hanging Drop (HD) method. Subsequently, the IC50s of XN were determined using the MTT assay in 2D and 3D cultures. Apoptosis was evaluated by Annexin V/PI flow cytometry and NFκB1/2, BAX, BCL2, and SURVIVIN expressions. Cell cycle progression was determined by P21, and P53 expressions as well as PI flow cytometry assays. Multidrug resistance was investigated through examining the expression of MDR1 and ABCG2. The invasion was examined by MMP2, MMP9, and FAK expression and F-actin labeling with Phalloidin-iFluor.

RESULTS

While the IC50s for the XN treatment were 1.9 µM and 4.74 µM in 2D cultures, these values were 12.37 µM and 31.17 µM in 3D cultures of MCF-7 and A549 cells, respectively. XN induced apoptosis in MCF-7 and A549 cell lines. Furthermore, XN treatment reduced cell cycle progression, multidrug resistance, and invasion at the molecular and/or cellular levels.

CONCLUSIONS

According to our results of XN treatment in 3D conditions, this bioactive compound can be introduced as an adjuvant anti-cancer agent for breast and lung cancer.

The interactions of monomeric acridines and unsymmetrical bisacridines (UAs) with DNA duplexes: an insight provided by NMR and MD studies

Members of a novel class of anticancer compounds, exhibiting high antitumor activity, i.e. the unsymmetrical bisacridines (UAs), consist of two heteroaromatic ring systems. One of the ring systems is an imidazoacridinone moiety, with the skeleton identical to the structural base of Symadex. The second one is a 1-nitroacridine moiety, hence it may be regarded as Nitracrine's structural basis. These monoacridine units are connected by an aminoalkyl linker, which vary in structure. In theory, these unsymmetrical dimers should act as double-stranded DNA (dsDNA) bis-intercalators, since the monomeric units constituting the UAs were previously reported to exhibit an intercalating mode of binding into dsDNA. On the contrary, our earlier, preliminary studies have suggested that specific and/or structurally well-defined binding of UAs into DNA duplexes might not be the case. In this contribution, we have revisited and carefully examined the dsDNA-binding properties of monoacridines C-1305, C-1311 (Symadex), C-283 (Ledakrin/Nitracrine) and C-1748, as well as bisacridines C-2028, C-2041, C-2045 and C-2053 using advanced NMR techniques, aided by molecular modelling calculations and the analysis of UV-VIS spectra, decomposed by chemometric techniques. These studies allowed us to explain, why the properties of UAs are not a simple sum of the features exhibited by the acridine monomers.

Inhibition of histone deacetylase 6 destabilizes ERK phosphorylation and suppresses cancer proliferation via modulation of the tubulin acetylation-GRP78 interaction

BACKGROUND

The leading cause of cancer-related mortality worldwide is lung cancer, and its clinical outcome and prognosis are still unsatisfactory. The understanding of potential molecular targets is necessary for clinical implications in precision diagnostic and/or therapeutic purposes. Histone deacetylase 6 (HDAC6), a major deacetylase enzyme, is a promising target for cancer therapy; however, the molecular mechanism regulating cancer pathogenesis is largely unknown.

METHODS

The clinical relevance of HDAC6 expression levels and their correlation with the overall survival rate were analyzed based on the TCGA and GEO databases. HDAC6 expression in clinical samples obtained from lung cancer tissues and patient-derived primary lung cancer cells was evaluated using qRT-PCR and Western blot analysis. The potential regulatory mechanism of HDAC6 was identified by proteomic analysis and validated by immunoblotting, immunofluorescence, microtubule sedimentation, and immunoprecipitation-mass spectrometry (IP-MS) assays using a specific inhibitor of HDAC6, trichostatin A (TSA) and RNA interference to HDAC6 (siHDAC6). Lung cancer cell growth was assessed by an in vitro 2-dimensional (2D) cell proliferation assay and 3D tumor spheroid formation using patient-derived lung cancer cells.

RESULTS

HDAC6 was upregulated in lung cancer specimens and significantly correlated with poor prognosis. Inhibition of HDAC6 by TSA and siHDAC6 caused downregulation of phosphorylated extracellular signal-regulated kinase (p-ERK), which was dependent on the tubulin acetylation status. Tubulin acetylation induced by TSA and siHDAC6 mediated the dissociation of p-ERK on microtubules, causing p-ERK destabilization. The proteomic analysis demonstrated that the molecular chaperone glucose-regulated protein 78 (GRP78) was an important scaffolder required for p-ERK localization on microtubules, and this phenomenon was significantly inhibited by either TSA, siHDAC6, or siGRP78. In addition, suppression of HDAC6 strongly attenuated an in vitro 2D lung cancer cell growth and an in vitro 3D patient derived-lung cancer spheroid growth.

CONCLUSIONS

HDAC6 inhibition led to upregulate tubulin acetylation, causing GRP78-p-ERK dissociation from microtubules. As a result, p-ERK levels were decreased, and lung cancer cell growth was subsequently suppressed. This study reveals the intriguing role and molecular mechanism of HDAC6 as a tumor promoter, and its inhibition represents a promising approach for anticancer therapy.

Acid–Base Equilibrium and Self-Association in Relation to High Antitumor Activity of Selected Unsymmetrical Bisacridines Established by Extensive Chemometric Analysis

Unsymmetrical bisacridines (UAs) represent a novel class of anticancer agents previously synthesized by our group. Our recent studies have demonstrated their high antitumor potential against multiple cancer cell lines and human tumor xenografts in nude mice. At the cellular level, these compounds affected 3D cancer spheroid growth and their cellular uptake was selectively modulated by quantum dots. UAs were shown to undergo metabolic transformations in vitro and in tumor cells. However, the physicochemical properties of UAs, which could possibly affect their interactions with molecular targets, remain unknown. Therefore, we selected four highly active UAs for the assessment of physicochemical parameters under various pH conditions. We determined the compounds’ pK_a dissociation constants as well as their potential to self-associate. Both parameters were determined by detailed and complex chemometric analysis of UV-Vis spectra supported by nuclear magnetic resonance (NMR) spectroscopy. The obtained results indicate that general molecular properties of UAs in aqueous media, including their protonation state, self-association ratio, and solubility, are strongly pH-dependent, particularly in the physiological pH range of 6 to 8. In conclusion, we describe the detailed physicochemical characteristics of UAs, which might contribute to their selectivity towards tumour cells as opposed to their effect on normal cells.

c-Myc Protein Level Affected by Unsymmetrical Bisacridines Influences Apoptosis and Senescence Induced in HCT116 Colorectal and H460 Lung Cancer Cells

Unsymmetrical bisacridines (UAs) are highly active antitumor compounds. They contain in their structure the drugs previously synthesized in our Department: C-1311 and C-1748. UAs exhibit different properties than their monomer components. They do not intercalate to dsDNA but stabilize the G-quadruplex structures, particularly those of the MYC and KRAS genes. Since MYC and KRAS are often mutated and constitutively expressed in cancer cells, they can be used as therapeutic targets. Herein, we investigate whether UAs can affect the expression and protein level of c-Myc and K-Ras in HCT116 and H460 cancer cells, and if so, what are the consequences for the UAs-induced cellular response. UAs did not affect K-Ras, but they strongly influenced the expression and translation of the c-Myc protein, and in H460 cells, they caused its full inhibition. UAs treatment resulted in apoptosis, as confirmed by the morphological changes, the presence of sub-G1 population and active caspase-3, cleaved PARP, annexin-V/PI staining and a decrease in mitochondrial potential. Importantly, apoptosis was induced earlier and to a greater extent in H460 compared to HCT116 cells. Moreover, accelerated senescence occurred only in H460 cells. In conclusion, the strong inhibition of c-Myc by UAs in H460 cells may participate in the final cellular response (apoptosis, senescence).