Tumor spheroids or microtumors are important 3D in vitro tumor models that closely resemble a tumor's in vivo “microenvironment” compared to 2D cell culture. Microtumors are widely applied in the fields of fundamental cancer research, drug discovery, and precision medicine. In precision medicine tumor spheroids derived from patient tumor cells represent a promising system for drug sensitivity and resistance testing. Established and commonly used platforms for routine screenings of cell spheroids, based on microtiter plates of 96‐ and 384‐well formats, require relatively large numbers of cells and compounds, and often lead to the formation of multiple spheroids per well. In this study, an application of the Droplet Microarray platform, based on hydrophilic–superhydrophobic patterning, in combination with the method of hanging droplet, is demonstrated for the formation of highly miniaturized single‐spheroid‐microarrays. Formation of spheroids from several commonly used cancer cell lines in 100 nL droplets starting with as few as 150 cells per spheroid within 24–48 h is demonstrated. Established methodology carries a potential to be adopted for routine workflows of high‐throughput compound screening in 3D cancer spheroids or microtumors, which is crucial for the fields of fundamental cancer research, drug discovery, and precision medicine.

Numerous lines of evidence support the hierarchical model of cancer development and tumor initiation. According to the theory, cancer stem cells play a crucial role in the formation of the tumor and should be targeted for more effective anticancer treatment. However, cancer stem cells quickly loose their characteristics when propagated as 2D cell culture, indicating that the 2D cell culture does not provide the appropriate settings to maintain an in vivo environment. In this study we have investigated the expression of self-renewal, cancer stem cell and epithelial to mesenchymal transition markers after the transfer of human colorectal carcinoma cell DLD1 and HT29 lines from 2D cell cultures to scaffold-attached laminin rich extracellular matrix and scaffold-free multicellular spheroid 3D culture models. Based on the up-regulated expression of multipotency, CSC and EMT markers, our data suggests that human colorectal carcinoma cells grown in 3D exhibit enhanced cancer stem cell characteristics. Therefore, in order to design more efficient targeted therapies, we suggest that 3D cell culture models should be employed in cancer stem cell research.

In clinical practice ionizing radiation (IR) is primarily applied to cancer treatment in the form of fractionated dose (FD) irradiation. Despite this fact, a substantially higher amount of current knowledge in the field of radiobiology comes from in vitro studies based on the cellular response to single dose (SD) irradiation. In addition, intrinsic and acquired resistance to IR remains an issue in clinical practice, leading to radiotherapy treatment failure. Numerous previous studies suggest that an improved understanding of the molecular processes involved in the radiation-induced DNA damage response to FD irradiation could improve the effectiveness of radiotherapy. Therefore, the present study examined the differential expression of genes and microRNA (miRNA) in murine Lewis lung cancer (LLC)1 cells exposed to SD or FD irradiation. The results of the present study indicated that the gene and miRNA expression profiles of LLC1 cells exposed to irradiation were dose delivery type-dependent. Data analysis also revealed that mRNAs may be regulated by miRNAs in a radiation-dependent manner, suggesting that these mRNAs and miRNAs are the potential targets in the cellular response to SD or FD irradiation. However, LLC1 tumors after FD irradiation exhibited no significant changes in the expression of selected genes and miRNAs observed in the irradiated cells in vitro, suggesting that experimental in vitro conditions, particularly the tumor microenvironment, should be considered in detail to promote the development of efficient radiotherapy approaches. Nevertheless, the present study highlights the primary signaling pathways involved in the response of murine cancer cells to irradiation. Data presented in the present study can be applied to improve the outcome and development of radiotherapy in preclinical animal model settings.

Our results indicate altered pathways related to cancer development and progression and suggest potential ECM-regulated targets for the development of anticancer therapies.

Cells are constantly exposed to a multitude of DNA-damaging agents that can lead to mutation, dysregulation, and possibly cell death. To ensure genomic integrity, DNA Damage Response (DDR) mechanisms are set in motion to repair and mitigate any damage to the DNA structure. Although these pathways are well-studied in the context of nuclear function, relatively little is known of the regulatory function of cytoplasmic organelles. Here we show the first example of DDR regulation at the Golgi complex, coordinating Homologous Recombination (HR)-mediated DNA repair. We found that RAD51C, a regulatory HR protein, localises to the Golgi and nuclear compartments and in response to double-strand DNA breaks, the Golgi protein population of RAD51C redistributes to form nuclear foci. Furthermore, we found that the Golgi localisation of RAD51C is dependent on the Golgin Giantin. Depletion of Giantin induces the redistribution of the RAD51C Golgi pool to form nuclear foci, independent of DNA damage induction, and concurrent with a significant increase in genomic instability and inhibition of HR signalling regulators. This study presents evidence for a novel pathway where the Golgi is a central regulatory hub for HR DDR and potentially other repair pathways, a finding with important therapeutic implications.