Chloroxoquinoline

The spheroid/tumor organoid invasion assay measures outward movement of cancer cells from a compact 3D aggregate into an extracellular matrix, usually collagen I, basement membrane matrix, or mixed collagen-Matrigel hydrogels; the readout is generated by bright-field, fluorescence, confocal, or time-lapse imaging of cell egress, invasion area, invasion distance, dispersion, protrusion formation, basement-membrane perforation, or cell trajectories. The assay reflects cell-cell cohesion, cell-matrix adhesion, matrix remodeling, protease-dependent invasion, contractility, and invasion behavior in a 3D microenvironment rather than migration on a flat 2D surface.

Ex vivo organotypic tissue slice cultures are based on maintaining thin, viable tissue sections at an air-liquid interface to preserve native cytoarchitecture and local cell-matrix interactions, enabling observation of cell behavior such as migration and tissue infiltration within a physiologically relevant 3D microenvironment. The method relies on maintaining tissue viability on porous membrane supports, allowing diffusion of nutrients and oxygen while preserving structural integrity for extended culture periods, which makes it suitable for studying dynamic cellular processes in intact tissue contexts such as cell movement and tissue remodeling. .

Patient-derived organoid (PDO) invasion assays are based on the ability of epithelial tumor organoids to self-organize in three-dimensional extracellular matrix (ECM) hydrogels (commonly Matrigel) and to recapitulate key aspects of in vivo tissue architecture, including polarity, proliferation, and invasive outgrowth when exposed to permissive microenvironmental cues. In this system, invasion is operationally defined as the emergence of multicellular protrusions, collective budding, or single-cell dissemination from the organoid core into the surrounding ECM, reflecting epithelial-mesenchymal plasticity and matrix remodeling capacity. Organoid morphology and invasive behavior are typically monitored using brightfield or confocal microscopy over time, enabling quantitative assessment of invasion area, protrusion number, and structural disruption of the organoid spheroid architecture.

Live/dead viability and cytotoxicity staining assays are based on the simultaneous detection of intracellular esterase activity in metabolically active (viable) cells and membrane integrity loss in non-viable cells. In commonly used dual-staining approaches, membrane-permeant fluorogenic substrates are converted by intracellular esterases into fluorescent products in live cells, while impermeant DNA-binding dyes selectively enter cells with compromised plasma membranes and label nucleic acids in dead or dying cells, enabling discrimination between viable and non-viable populations by fluorescence microscopy or flow cytometry.

Breast cancer is a heterogeneous cancer, and it has been distinguished into four subtypes: luminal A, luminal B, HER2-positive and basal-like. Molecular mutations, epigenetic alterations, hormone exposure and immune microenvironment are related to the progression of breast cancer.

3D tumor spheroid invasion assay measures outward tumor-cell movement from a compact multicellular spheroid into a surrounding extracellular matrix, producing image-based readouts such as invasion area, invasion distance, cell dispersion, or time-resolved cell movement. The method models tumor-cell interaction with matrix components in three dimensions and is used to study invasive phenotypes in cancer models including glioblastoma, squamous cell carcinoma, breast cancer, prostate cancer, ovarian cancer, and other solid tumor systems.

Matrigel Transwell/Boyden chamber invasion assay measures the ability of cells to degrade or traverse an extracellular matrix-coated porous membrane and move from an upper chamber toward a chemoattractant in a lower chamber. Invasion is distinguished from migration by coating the membrane with Matrigel or basement membrane matrix; uncoated inserts measure migration, while coated inserts require cells to cross an ECM barrier before reaching the underside of the membrane.

Invadopodia/fluorescent gelatin degradation assay detects proteolytic extracellular matrix degradation by cancer-cell invadopodia, which are actin-rich protrusive structures associated with matrix remodeling, invasion, and metastasis. The readout is generated by culturing cells on fluorescent gelatin and measuring dark degraded areas where fluorescent substrate has been locally removed, often together with immunofluorescent detection of invadopodia markers such as F-actin, cortactin, and TKS5.

Cytotoxicity assays are usually based on the assessment of cell membrane damage, which can also be indirectly detected by measuring cell viability. Detection methods include MTT assay, CKK-8 assay, LDH assay and ATP assay, etc.

Patient-derived xenograft (PDX) models are generated by engrafting primary human tumor tissue directly into immunodeficient mice, allowing in vivo propagation of patient tumor biology without initial in vitro adaptation. These models are used to preserve key histopathological and molecular characteristics of the original tumor and enable assessment of tumor growth dynamics and therapeutic response in a living organism. The biological readout is tumor engraftment and subsequent growth in the murine host, which reflects the ability of human tumor cells to survive, vascularize, and expand in an immunocompromised microenvironment.

Apoptosis is a regulated, generally non-lytic cell-death pathway that removes unwanted, damaged, infected, or abnormal cells through coordinated morphological changes, caspase activation, DNA fragmentation, and membrane remodeling. The intrinsic apoptosis pathway is controlled mainly by mitochondrial outer membrane permeabilization, BCL-2 family proteins, cytochrome c release, apoptosome formation, caspase-9 activation, and downstream executioner caspase-3/7 activation. The extrinsic apoptosis pathway is initiated by death receptors such as Fas, TNFR, and TRAIL receptors, which recruit adaptor proteins and activate caspase-8 before engaging executioner caspases or mitochondrial amplification through BID cleavage. Apoptosis is linked to many phenotypes, including cancer cell killing, tissue homeostasis, immune regulation, neurodegeneration, infection response, and treatment-induced cytotoxicity; unresolved questions include how apoptosis interacts with necroptosis, pyroptosis, ferroptos

The organotypic 3D invasion assay measures carcinoma-cell invasion into a fibroblast-remodeled extracellular matrix, usually collagen I with or without basement-membrane matrix, under an air-liquid or grid-supported culture condition; the readout is invasion depth, invaded area, or an invasion index from histological or fluorescence images. This assay models stromal regulation of invasion because fibroblasts or CAFs remodel matrix, generate tracks, and can lead collective carcinoma-cell invasion; the resulting cancer-cell penetration into the gel reflects tumor-stroma-ECM interactions rather than migration on a rigid 2D substrate.

Cell invasion is the ability of cells to migrate from one area to another via the extracellular matrix. Cell invasion is the response of normal and cancer cells to chemical and mechanical stimuli. Before migrating to a new region, the extracellular matrix is degraded by proteases within the cell. Cell invasion often occurs during wound repair, vascularization and inflammation, abnormal tissue invasion, and tumor cell metastasis.

The Matrigel/ECM Transwell invasion assay measures the ability of cells to move toward a chemoattractant while crossing an extracellular-matrix barrier placed on a porous membrane; therefore, the readout reflects both chemotactic motility and matrix invasion rather than migration alone. Matrigel is a basement-membrane-rich matrix derived from Engelbreth-Holm-Swarm mouse sarcoma and has been used as a reconstituted basement membrane barrier in chemoinvasion assays. The assay readout is generated by quantifying cells that reach the underside of the insert membrane or lower compartment after incubation, commonly by staining and counting invaded cells or by fluorescence-based quantification.

Splenic and portal-vein liver metastasis xenograft models deliver tumor cells into the portal circulation so that cells reach the liver first and form hepatic metastatic lesions; splenic injection uses the spleen as an access route to the portal system, while direct portal-vein injection introduces cells into the portal vein without requiring splenectomy. The assay detects liver colonization, intrahepatic tumor growth, tumor distribution, treatment response, survival, and liver-metastasis microenvironment changes; readouts include bioluminescence or fluorescence imaging, gross liver nodule counts, liver weight or tumor burden, histology, and survival.

Subcutaneous cell-line-derived xenograft (CDX) models are established by implanting cultured human cancer cell lines into immunodeficient mice, where the injected cells form localized tumors that can be monitored in vivo as a measure of tumorigenic potential, growth kinetics, and treatment response. These models are widely used in oncology research because they allow reproducible tumor formation and enable comparative assessment of tumor growth between different cell lines or genetic manipulations in a controlled in vivo microenvironment. Subcutaneous implantation of cancer cells in immunodeficient mice is a standard approach for evaluating tumor growth behavior and therapeutic response across multiple cancer types, including prostate, esophageal, pancreatic, and colon cancer models.

Orthotopic cell-line xenograft models involve implantation of human cancer cell lines into the anatomically corresponding organ of immunodeficient mice to reproduce tumor growth within a native microenvironment, enabling more clinically relevant tumor behavior compared with subcutaneous models. These models are widely used because orthotopic placement better recapitulates tumor progression, including invasion and metastatic spread, which are often underrepresented in heterotopic implantation systems. Compared with conventional xenografts, orthotopic implantation is described as more technically complex but provides improved simulation of tumor-microenvironment interactions and metastatic behavior, making it particularly valuable for translational oncology research. Surgical orthotopic implantation approaches have been emphasized as enabling faithful reproduction of clinical cancer features, including metastasis and disease progression patterns that align with the tumor’s organ of origi

The 3D collagen/hydrogel matrix invasion assay is based on embedding cells within or on top of a three-dimensional fibrillar extracellular matrix (typically type I collagen or collagen-rich hydrogels) to model cell migration through a physiologically relevant physical barrier. In this system, invasive behavior is quantified by measuring the ability of cells to degrade, remodel, and migrate through the 3D matrix architecture, which better reflects in vivo tissue invasion compared to 2D migration assays. Collagen-based 3D matrices provide structural cues such as fiber alignment and porosity that influence cell motility and integrin-mediated adhesion, enabling observation of collective or single-cell invasion modes depending on matrix density and organization.

Intraperitoneal (IP) or peritoneal dissemination xenograft models are based on the introduction of human cancer cells into the peritoneal cavity of immunodeficient mice, where they attach to peritoneal surfaces, form multicellular aggregates or spheroids, and progressively generate disseminated tumor nodules that mimic advanced peritoneal metastatic disease. These models are widely used to study ovarian cancer progression, tumor-microenvironment interactions, and intraperitoneal therapeutic responses, often incorporating bioluminescence or fluorescence imaging to longitudinally monitor tumor burden in vivo. The biological principle relies on the capacity of tumor cells such as SKOV3 or related ovarian carcinoma lines to survive in suspension, aggregate within ascites-like fluid, adhere to mesothelial surfaces, and invade peritoneal organs, thereby recapitulating human peritoneal carcinomatosis patterns observed in advanced disease.